BIOMECHANICS OF WRIST

&
HAND COMPLEX
• THE HAND CONSIST OF 5 DIGITS – 1 THUMB & 4 FINGERS
• THERE ARE 8 CARPAL BONES.
• IN HAND COMPLEX THERE ARE 19 BONES & 19JOINTS, DISTAL TO CARPAL
BONES.
• EACH DIGIT HAS A CARPOMETACARPAL JOINT (CMC) & A
METACARPOPHALANGEAL JOINT (MCP).
• EACH FINGER HAS 2 INTERPHALANGEAL JOINTS ONE DISTAL (DIP) & ONE
PROXIMAL (PIP) EXCEPT THUMB HAVING ONLY 1 INTERPHALANGEAL
JOINT.
THE WRIST COMPLEX
• THE WRIST (CORPUS) CONSIST OF 2 JOINTS –
• RADIOCARPAL JOINT
• MIDCARPAL JOINT

RADIOGRAPHIC REPRESENTATION SCHEMATIC REPRESENTATION

• THE MAJOR CONTRIBUTION OF WRIST COMPLEX IS TO CONTROL LENGTH TENSION RELATIONSHIP
IN MULTIARTICULAR HAND MUSCLES & TO ALLOW FINE ADJUSTMENTS OF GRIP.
• WRIST MUSCLES ARE DESIGNED FOR BALANCE & CONTROL RATHER THAN MAXIMIZING TORQUE
PRODUCTION.
• WRIST COMPLEX AS A WHOLE IS CONSIDERED BIAXIAL WITH MOTIONS OF FLEXION/EXTENSION
(CORONAL AXIS) & ULNAR DEVIATION / RADIAL DEVIATION (AP AXIS).
• THE ROM OF ENTIRE COMPLEX IS VARIABLE & REFLECT DIFFERENCES IN CARPAL KINEMATICS WHICH
COULD BE DUE TO –
• LIGAMENTOUS LAXITY
• THE SHAPE OF ARTICULAR SURFACES
• THE CONSTRAINING EFFECT OF MUSCLES
• NORMAL VARYING RANGES OF WRIST JOINT ARE –
Flexion 65° - 85°
Extension 60° - 85°
Radial deviation 15° - 21°
Ulnar deviation 20° - 45°

• THE 2 JOINT RATHER THAN SINGLE JOINT COMPLEX PROVIDES –

• LARGE ROM WITH LESS EXPOSED ARTICULAR SURFACES & TIGHTER
JOINT CAPSULE
• LESS TENDENCY FOR STRUCTURAL PINCH AT EXTREME RANGES
• FLATTENED MULTIJOINT SURFACES THAT ARE MORE CAPABLE OF
WITHSTANDING IMPOSED PRESSURES
 RADIOCARPAL JOINT STRUCTURE

• FORMED BY RADIUS & RADIOULNAR DISCS AS A PART OF

TRIANGULAR FIBROCARTILAGE COMPLEX (TFCC) PROXIMALLY &
SCAPHOID, LUNATE & TRIQUETRUM DISTALLY.
 PROXIMAL & DISTAL SEGMENTS OF RC
JOINT
• DISTAL RADIUS HAS SINGLE CONTINUOUS BICONCAVE CURVATURE THAT IS LONG
& SHALLOW SIDE TO SIDE & SHARPER & SHORTER ANTEROPOSTERIORLY.
• PROXIMAL JOINT SURFACE CONSIST OF –
1. LATERAL RADIAL FACET (SCAPHOID)
2. MEDIAL RADIAL FACET (LUNATE)
3. TFCC (TRIQUETRUM & LITTLE WITH LUNATE IN NEUTRAL POSITION)
• PROXIMAL RADIOCARPAL JOINT SURFACE IS OBLIQUE & ANGLED SLIGHTLY
VOLARLY & ULNARLY.
• AVERAGE INCLINATION OF RADIUS IS 23° & TILTED 11° VOLARLY.
TFCC –
• CONSIST OF RADIOULNAR DISC & VARIOUS FIBROUS ATTACHMENTS
PROVIDING SUPPORT TO DISTAL RADIOULNAR JOINT.
• THE DISC IS CONNECTED MEDIALLY VIA 2 DENSE, FIBROUS
CONNECTIVE TISSUE LAMINAE. UPPER LAMINAE INCLUDE DORSAL &
VOLAR RADIOULNAR LIGAMENT WHEREAS LOWER LAMINAE HAS
CONNECTIONS TO SHEATH OF ECU TENDON, TRIQUETRUM, HAMATE &
BASE OF 5TH METACARPAL THROUGH ULNAR COLLATERAL LIGAMENT.
• MENISCUS HOMOLOG – REGION OF IRREGULAR CONNECTIVE TISSUE
(PART O LOWER LAMINAE) TRAVERSE VOLARLY & ULNARLY FROM
DORSAL RADIUS TO INSERT ON THE TRIQUETRUM.
• OVERALL TFCC FUNCTIONS AT WRIST AS AN EXTENSION OF DISTAL
RADIUS.
• SCAPHOID, LUNATE & TRIQUETRUM – PROXIMAL CARPAL ROW.
• BONES ARE INTERCONNECTED BY 2 LIGAMENTS IE. SCAPHOLUNATE
INTEROSSEOUS & LUNOTRIQUETRAL INTEROSSEOUS LIGAMENTS.
• PROXIMAL CARPAL ROW & LIGAMENTS TOGETHER APPEARS AS A
SINGLE BICONVEX CARTILAGE COVERED JOINT SURFACE THAT CAN
CHANGE SHAPE TO ACCOMMODATE TO THE DEMANDS OF SPACE
BETWEEN FOREARM & HAND.
• IN RADIOCARPAL JOINT DISTAL SURFACE IS SHARPER THAN PROXIMAL
BOTH IN CORONAL & SAGITTAL PLANE – MAKES JOINT INCONGRUENT.
• THIS CAUSES GREATER RANGE OF FLEXION THAN EXTENSION &
GREATER ULNAR DEVIATION THAN RADIAL DEVIATION.
• AS THE CURVATURE & INCLINATION OF THE RADIOCARPAL SURFACES
AFFECTS FUNCTION, THE LENGTH OF ULNA IN RELATION TO RADIUS ALSO
AFFECTS IT.
• ULNAR NEGATIVE VARIANCE – SHORTER ULNA THAN RADIUS AT THE DISTAL
END.
• ULNAR POSITIVE VARIANCE – LONGER DISTAL ULNA THAN DISTAL RADIUS.
• POSITIVE VARIANCE IS ASSOCIATED WITH CHANGES IN TFCC THICKNESS –
POTENTIAL FOR IMPINGEMENT OF TFCC BETWEEN ULNA & TRIQUETRUM.
• RELATIVELY LONGER ULNA IS PRESENT AFTER DISTAL RADIUS FRACTURE
HEALED IN SHORTENED POSITION – PAIN AT END RANGE OF PRONATION
ULNAR DEVIATION.
• NEGATIVE VARIANCE – ABNORMAL FORCE DISTRIBUTION AT RADIOCARPAL
JOINT – POTENTIAL DEGENERATION – AVASCULAR NECROSIS OF LUNATE
(KIENBOCK’S DISEASE).
 RADIOCARPAL CAPSULE & LIGAMENTS
• HAS STRONG BUT SOMEWHAT LOOSE CAPSULE & REINFORCED
BY CAPSULAR & INTRACAPSULAR LIGAMENTS.
• MOST LIGAMENTS & MUSCLES CROSSING RADIOCARPAL JOINT
ALSO CONTRIBUTES TO MIDCARPAL JOINT STABILITY
 MIDCARPAL JOINT STRUCTURE

• ARTICULATION BETWEEN SCAPHOID, LUNATE & TRIQUETRUM PROXIMALLY & TRAPEZIUM,

TRAPEZOID, CAPITATE & HAMATE DISTALLY.
• FUNCTIONAL UNIT RATHER THAN AN ANATOMICAL UNIT.
• HAS SEPARATE FIBROUS CAPSULE & SYNOVIAL LINING THAT IS CONTINUOUS WITH EACH
INTERCARPAL ARTICULATION & SOME WITH CMC JOINT.
• COMPLEX AS IT HAS OVERALL RECIPROCALLY CONCAVE CONVEX CONFIGURATION.
• FUNCTIONALLY DISTAL CARPAL ROW MOVES AS A FIXED UNIT.
• UNION OF DISTAL CARPALS ALSO RESULTS IN EQUAL DISTRIBUTION OF LOADS ACROSS
SCAPHOID-TRAPEZIUM-TRAPEZOID, SCAPHOID-CAPITATE, LUNATE-CAPITATE & TRIQUETRUM-
HAMATE ARTICULATIONS.
• DISTAL ROW CONTRIBUTES TO 2 DEGREES OF FREEDOM TO
WRIST COMPLEX WITH VARYING AMOUNTS OF ULNAR/RADIAL
DEVIATION & FLEXION/EXTENSION.
• DISTAL CARPAL ROW LADS TO THE FOUNDATION OF
TRANSVERSE & LONGITUDINAL ARCHES OF HAND.
 LIGAMENTS OF THE WRIST COMPLEX

• THE LIGAMENTOUS STRUCTURE OF CARPUS IS RESPONSIBLE

FOR ARTICULAR STABILITY AS WELL AS GUIDING & CHECKING
MOTIONS BETWEEN & AMONG THE CARPALS.
• IN GENERAL, DORSAL LIGAMENTS ARE THIN & NUMEROUS
Ligaments
VOLAR LIGAMENTS ARE THICKER & STRONGER.
•
Extrinsic Intrinsic

Connects carpals to radius ulna proximally or Interconnects the

metacarpals distally carpals
PROPERTIES EXTRINSIC LIGAMENTS INTRINSIC LIGAMENTS

CONNECTION Carpals to radius ulna Interconnect carpals

proximally & metacarpals (intercarpals /
distally inrterosseous)

Stronger & less stiff

Lie within synovial lining

Nutrition Contiguous vascularized Through synovial fluid

tissue

Risk of injury High Low

Healing Fast Slow

Accept forces first

 VOLAR CARPAL LIGAMENTS

• ORGANIZED INTO 2 GROUPS : RADIOCARPAL & ULNOCARPAL LIGAMENTS – COMPOSITE

VOLAR RADIOCARPAL LIGAMENTS.
• HAS 3 DISTINCT BANDS – THE RADIOSCAPHOCAPITATE (RADIOCAPITATE); SHORT & LONG
RADIOLUNATE & RADIOSCAPHOLUNATE LIGAMENTS.
• RADIOSCAPHOLUNATE – STABILIZES SCAPHOID – DISRUPTION CAUSES SCAPHOID
INSTABILITY. - ???
• RADIAL COLLATERAL LIGAMENT – EXTENSION OF VOLAR RADIOCARPAL LIGAMENTS &
CAPSULE.
• ULNOCARPAL LIGAMENT COMPLEX – COMPOSED OF TFCC INCLUDING ARTICULAR DISC &
MENISCUS HOMOLOG; ULNOLUNATE LIGAMENT & ULNAR COLLATERAL LIGAMENT.
• 2 VOLAR INTRINSIC LIGAMENTS – IMPORTANT IN WRIST
FUNCTION.
• SCAPHOLUNATE INTEROSSEOUS LIGAMENT – MAINTAINS
SCAPHOID STABILITY & SO WRIST STABILITY.
• LUNOTRIQUETRAL INTEROSSEOUS LIGAMENT – MAINTAINS
STABILITY BETWEEN LUNATE & TRIQUETRUM
• STRETCHED WHILE WRIST EXTENSION.
 DORSAL CARPAL LIGAMENTS

• DORSAL RADIOCARPAL LIGAMENT

• DORSAL INTERCARPAL LIGAMENT
• TOGETHER FORMS A HORIZONTAL ‘V’ THAT CONTRIBUTES TO
RADIOCARPAL STABILITY; NOTABLY STABILIZES SCAPHOID
DURING WRIST ROM.
• TAUT WITH WRIST FLEXION.
 FUNCTIONS OF WRIST COMPLEX

MOVEMENTS OF RADIOCARPAL & MIDCARPAL JOINTS :-

• PROXIMAL CARPALS ACTS AS MECHANICAL LINK BETWEEN
RADIUS & DISTAL CARPALS & METACARPALS TO WHICH THE
MUSCULAR FORCES ARE DIRECTLY APPLIED – INTERCALATED
SEGMENT.
FLEXION / EXTENSION OF THE WRIST –
• IN 3 PROXIMAL CARPAL BONES, SCAPHOID HAS GREATEST MOTION &
LUNATE MOVES LEAST.
• THE MOVEMENTS OF COMPLEX FROM COMPLETE FLEXION TO
EXTENSION ARE – DISTAL CARPAL ROW MOVES ON PROXIMAL
CARPAL ROW → SCAPHOID & DISTAL CARPALS MOVES ON LUNATE &
TRIQUETRUM → CARPALS AS A UNIT MOVE OVER RADIUS & TFCC.
• EXTENSION TO FLEXION – REVERSE PROCESS.
RADIAL / ULNAR DEVIATION –
• IN RADIAL DEVIATION, CARPALS SLIDE ULNARLY OVER RADIUS WITH
SIMULTANEOUS FLEXION OF PROXIMAL CARPALS & EXTENSION OF
DISTAL CARPALS. THE OPPOSITE OCCURS IN ULNAR DEVIATION.
• IN FULL RADIAL DEVIATION, BOTH THE RADIOCARPAL & MIDCARPAL
JOINTS ARE IN CLOSED PACKED POSITION.
• RANGES VARY ACCORDING TO THE WRIST POSITION – MORE TO
LESS – NEUTRAL → FULLY FLEXED → FULLY EXTENDED.
 MUSCLES OF WRIST COMPLEX
PRIMARY ROLE –
• TO PROVIDE A STABLE BASE FOR HAND WHILE PERMITTING
POSITIONAL ADJUSTMENTS & ALLOW FOR OPTIMAL LENGTH
TENSION RELATIONSHIPS.

Muscles

Volar (cause flexion) Dorsal (cause extension)

PL,FCR,FCU ECRL, ECRB,ECU

FDS,FDP,FPL EDC,EIP,EDM,EPL,EPB,APL
THE HAND COMPLEX
• HAND COMPLEX CONSIST OF 5 DIGITS – 4 FINGERS & ONE THUMB.

• EACH FINGER HAS 1 CMC, 1 MCP & 2 IP (PROXIMAL & DISTAL) JOINTS
WHEREAS THUMB HAS 1 CMC, 1 MCP & ONLY 1 IP JOINT.

• OVERALL THERE ARE 19 BONES & 19 JOINTS DISTAL TO THE CARPALS.

CARPOMETACARPAL JOINTS OF FINGERS
• ARTICULATION BETWEEN DISTAL CARPAL ROW WITH 2ND
TO 5TH BASES OF METACARPALS (MC).
• THE 2ND MC ARTICULATES PRIMARILY WITH TRAPEZOID &
SECONDARILY WITH TRAPEZIUM & CAPITATE; 3RD MC
WITH CAPITATE; 4TH WITH CAPITATE & HAMATE & 5TH MC
ARTICULATES WITH ONLY HAMATE.
• SUPPORTED BY STRONG TRANSVERSE & WEAKER
LONGITUDINAL LIGAMENTS.
• DEEP TRANSVERSE METACARPAL LIGAMENT COVERS 2ND
TO 4TH MC VOLARLY – TETHERS TOGETHER THE MC HEADS
& PREVENTS EXCESSIVE ABDUCTION WHICH CONTRIBUTES
TO CMC STABILITY.
• PROXIMAL TRANSVERSE (CARPAL) ARCH – AFFECTS CMC &
HAND FUNCTION BUT NOT THE WRIST FUNCTION.
• IT IS FORMED BY TRAPEZIUM, TRAPEZOID, CAPITATE & HAMATE
(DISTAL CARPAL ROW) – WHICH IS CONCAVE VOLARLY.
• THIS CONCAVITY IS MAINTAINED BY TRANSVERSE CARPAL
LIGAMENT & INTERCARPAL LIGAMENT. THIS FORMS CARPAL
TUNNEL WHICH CONTAINS MEDIAN NERVE & 9 EXTRINSIC
FLEXOR TENDONS.
 CMC JOINT RANGE OF MOTION

• IN THE ARTICULATING SURFACE MORE RANGE IS AVAILABLE AT MC

HEADS. THE MOBILITY INCREASES FROM RADIAL TO ULNAR SIDE OF
HAND.
• 2ND TO 4TH CMC JOINTS ARE PLANE SYNOVIAL JOINTS HAVING ONLY
1° OF FREEDOM (FLEXION/EXTENSION) WHEREAS 5TH CMC JOINT IS
SADDLE JOINT WITH 2° OF FREEDOM. (FLEXION/EXTENSION,
ABDUCTION/ADDUCTION & LIMITED OPPOSITION)
• 2ND & 3RD CMC JOINTS – ESSENTIALLY IMMOBILE – CONSIDERED TO
HAVE 0° OF FREEDOM – AS IT PROVIDES FIXED & STABLE AXIS FOR 1ST,
4TH & 5TH MC HEADS.
 PALMAR ARCHES

• THE FUNCTION OF FINGERS CMC JOINTS & THEIR SEGMENT IS TO

CONTRIBUTE TO PALMAR ARCH SYSTEM.
• PROXIMAL TRANSVERSE ARCH – CONCAVITY FORMED BY CARPAL BONES.
• DISTAL TRANSVERSE ARCH – FORMED BY 1ST, 4TH & 5TH MC HEADS & IS
RELATIVELY MOBILE.
• LONGITUDINAL ARCH – TRAVERSE LENGTH OF THE DIGITS FROM
PROXIMAL TO DISTAL.
• DEEP TRANSVERSE MC LIGAMENT CONTRIBUTES TO STABILITY OF MOBILE
ARCHES DURING GRIP FUNCTIONS.
PALMAR ARCHES
• ALLOWS THE PALM & DIGITS TO CONFORM OPTIMALLY TO THE
SHAPE OF THE OBJECT BEING HELD – ALLOWING MAXIMUM
SURFACE CONTACT, ENHANCE STABILITY & INCREASE SENSORY
FEEDBACK.
• MUSCLES CROSSING CMC JOINT CONTRIBUTES TO PALMAR
CUPPING – HOLLOWING OF PALM ACCOMPANIES FINGER
FLEXION & RELATIVE FLATTENING OF PALM ACCOMPANIES
FINGER EXTENSION.
 METACARPOPHALANGEAL JOINTS OF
FINGERS
• CONVEX METACARPAL HEAD PROXIMALLY & CONCAVE BASE OF 1ST
PHALANX DISTALLY.
• CONDYLOID JOINT WITH 2° OF FREEDOM (FLEXION/EXTENSION &
ABDUCTION/ADDUCTION)
• IN SAGITTAL PLANE, MC HEAD HAS 180° OF ARTICULAR SURFACE
(PREDOMINANT PORTION LYING VOLARLY), OPPOSED TO 20° OF
ARTICULAR SURFACE ON 1ST PHALANX.
• IN FRONTAL PLANE THERE IS LESS BUT MORE CONGRUENT FRONTAL
PLANE.
• SURROUNDED BY A CAPSULE – LAX IN EXTENSION –
ALLOWS SOME PASSIVE AXIAL ROTATION OF PHALANX.
• COLLATERAL LIGAMENT AT THE VOLARLY LOCATED DEEP
TRANSVERSE MC LIGAMENT – ENHANCES JOINT STABILITY.
• VOLAR PLATES – ACCESSORY JOINT STRUCTURE TO
ENHANCE JOINT STABILITY.
 VOLAR PLATES

• ALSO CALLED AS PALMAR PLATES

• INCREASES JOINT CONGRUENCE; PROVIDES STABILITY TO MCP JOINTS (LIMITS
HYPEREXTENSION) – SO PROVIDES INDIRECT SUPPORT TO THE LONGITUDINAL
ARCH.
• COMPOSED OF FIBROCARTILAGE & IS FIRMLY ATTACHED TO BASE OF PROXIMAL
PHALANX.
• BECOMES MEMBRANOUS PROXIMALLY TO BLEND WITH VOLAR CAPSULE AT MC
HEADS.
• DURING MCP EXTENSION, THE PLATE ADDS UP THE AMOUNT OF SURFACE IN
CONTACT WITH LARGE MC HEADS.
• FIBROCRTILAGE COMPOSITION RESIST BOTH TENSILE STRESSES (MCP
HYPEREXTENSION) & COMPRESSIVE FORCES (TO PROTECT MC HEADS
FROM OBJECTS HELD IN PALM)
• DURING FLEXION – GLIDES PROXIMALLY – PREVENTS PINCHING OF
LONG FLEXOR TENDONS IN MCP JOINT.
• ALSO BLENDS WITH & ARE INTERCONNECTED SUPERFICIALLY BY DEEP
TRANSVERSE MC LIGAMENT.
• SAGITTAL BANDS (DORSAL TO DEEP TRANSVERSE MC LIGAMENTS) –
STABILIZES VOLAR PLATES.
 COLLATERAL LIGAMENT

• THE RADIAL & ULNAR COLLATERAL LIGAMENTS OF MCP JOINTS

ARE COMPOSED OF 2 PARTS: COLLATERAL LIGAMENT PROPER
(CORDLIKE) & ACCESSORY COLLATERAL LIGAMENT.
• TENSION IN COLLATERAL LIGAMENT AT FULL MCP JOINT
FLEXION (CLOSED PACK POSITION) – LIMITS MCP ABDUCTION
IN FULL FLEXION.
• PROVIDES STABILITY THROUGHOUT THE MCP JOINT ROM
 RANGE OF MOTION

• ROM AT EACH JOINT VARIES; FLEXION/EXTENSION INCREASES

RADIALLY TO ULNARLY WITH INDEX FINGER (90°) & LITTLE FINGER
(110°).
• HYPEREXTENSION – CONSISTENT BETWEEN FINGERS BUT VARIES
AMONG INDIVIDUALS.
• RANGE OF PASSIVE HYPEREXTENSION IS USED TO ASSESS FLEXIBILITY.
• ABDUCTION/ADDUCTION IS MAXIMAL IN MCP EXTENSION &
RESTRICTED IN FLEXION.
 INTERPHALANGEAL JOINTS OF FINGERS

• EACH PROXIMAL & DISTAL IP JOINTS IS COMPOSED OF HEAD OF THE

PHALANX & THE BASE OF THE PHALANX DISTAL TO IT.
• TRUE SYNOVIAL HINGE JOINT WITH 1° OF FREEDOM
(FLEXION/EXTENSION), A JOINT CAPSULE, A VOLAR PLATE & 2
COLLATERAL LIGAMENTS.
• STRUCTURE SIMILAR TO MCP JOINT BUT WITH LITTLE POSTERIOR
ARTICULAR SURFACE (PERMITS HYPEREXTENSION)
• VOLAR PLATES – REINFORCE EACH IP JOINT CAPSULE, ENHANCES
STABILITY & LIMITS HYPEREXTENSION. SIMILAR TO MCP JOINT PLATES
EXCEPT NO CONNECTION WITH DEEP TRANSVERSE LIGAMENT.
• COLLATERAL LIGAMENTS – CORD LIKE, SIMILAR TO MCP JOINT, PROVIDES
STABILITY. INJURIES TO PROXIMAL IP JOINT COLLATERAL LIGAMENT ARE
COMMON IN SPORTS & AT WORKPLACE (RADIAL > ULNAR COLLATERAL)
• FLEXION/EXTENSION OF IP JOINTS OF INDEX FINGER – PROXIMAL (100°-
110°) > DISTAL (80°).
• RANGE OF PIP & DIP JOINT FLEXION INCREASES ULNARLY WITH 5TH PIP &
DIP HAVING FLEXION RANGES OF 135° & 90° RESPECTIVELY.
• ADDITIONAL RANGE TO ULNARLY FINGERS – FAVORS ANGULATION OF
FINGERS TOWARDS SCAPHOID & OPPOSITION WITH THUMB.
 EXTRINSIC FINGER FLEXORS
• MUSCLES OF FINGERS & THUMB HAVING PROXIMAL
ATTACHMENT ABOVE WRIST.
• 2 MUSCLES CONTRIBUTING TO FINGER FLEXION – FLEXOR
DIGITORUM SUPERFICIALIS (FDS) & FLEXOR DIGITORUM
PROFUNDUS (FDP).
• FDS –
• FLEXES PROXIMAL IP JOINT & MCP JOINT.
• PRODUCES MORE TORQUE THAN FDP.
• CROSSES FEWER JOINTS & SUPERFICIAL TO FDP AT MCP
JOINT.
• GREATER MOMENT ARM FOR MCP JOINT.
• FDP – FLEXES MCP, PIP, DIP JOINTS – MORE ACTIVE.
• DURING FINGER FLEXION WITH WRIST FLEXION – FDS & FDP WORKS
TOGETHER.
• AT THE PROXIMAL PHALANX (PROXIMAL TO PIP), FDP EMERGES THROUGH
SPLIT IN FDS (CAMPER’S CHIASMA) & FDS ATTACHES TO BASE OF MIDDLE
PHALANX.
• BOTH FDS & FDP ARE DEPENDENT ON WRIST POSITION FOR OPTIMAL
LENGTH TENSION RELATIONSHIP.
• COUNTERBALANCING EXTENSOR TORQUE AT WRIST IS PROVIDED BY
EXTENSOR CARPI RADIALIS BREVIS (ECRB) OR SOMETIMES BY EXTENSOR
DIGITORUM COMMUNIS (EDC).
 MECHANISM OF FINGER FLEXION

• OPTIMAL FUNCTION OF FDS & FDP DEPENDS ON –

• STABILIZATION BY WRIST MUSCULATURE
• INTACT FLEXOR GLIDING MECHANISM

• GLIDING MECHANISM CONSIST OF –

• FLEXOR RETINACULA
• BURSAE
• DIGITAL TENDON SHEATHS
• THE FIBROUS RETINACULAR STRUCTURES (PROXIMAL FLEXOR RETINACULA,
TRANSVERSE CARPAL LIGAMENT, & EXTENSOR RETINACULUM) TETHERS THE LONG
FLEXOR TENDONS TO HAND – PREVENTS BOWSTRINGING OF TENDONS.
• BURSAE & TENDON SHEATHS FACILITATE FRICTION FREE EXCURSION OF TENDONS
ON RETINACULA.
• FDS & FDP TENDONS – CROSSES WRIST – PASS BENEATH PROXIMAL FLEXOR
RETINACULUM – THROUGH CARPAL TUNNEL – ULNAR BURSA (ALL 8 TENDONS).
• FLEXOR POLLICIS LONGUS (FPL) – PASS THROUGH CARPAL TUNNEL WITH FDS &
FDP – THEN RADIAL BURSA ENCASES IT.
• FDS & FDP TENDONS OF EACH FINGER PASS THROUGH A FIBROOSSEOUS TUNNEL
WHICH COMPRISES 5 TRANSVERSELY ORIENTED ANNULAR PULLEYS (VAGINAL
LIGAMENTS) & 3 OBLIQUELY ORIENTED CRUCIATE PULLEYS.
• ANNULAR PULLEYS –
• A1 – AT HEAD OF MC
• A2 – VOLAR MIDSHAFT OF PROXIMAL PHALANX
• A3 – DISTAL MOST PART OF PROXIMAL PHALANX
• A4 – CENTRALLY ON THE MIDDLE PHALANX
• A5 – BASE OF THE DISTAL PHALANX
• THE BASE OF EACH PULLEY IS LONGER THAN THE ROOF
SUPERFICIALLY & ROOF HAS SLIGHT CONCAVITY
VOLARLY.
• THIS PREVENTS THE PULLEYS FROM PINCHING EACH
OTHER AT EXTREMES OF FLEXION & MINIMIZES THE
PRESSURE ON THE TENDON WHEN IT IS UNDER TENSION.
• THE CRUCIATE PULLEYS –
• C1 – BETWEEN A2 & A3
• C2 – BETWEEN A3 & A4
• C3 – BETWEEN A4 & A5
• A4, A5 & C3 CONTAINS ONLY FDP TENDON & NO FDS.
• THUMB HAS DIFFERENT PULLEY SYSTEM.
• FUNCTION OF ANNULAR PULLEYS –
• TO KEEP THE FLEXOR TENDONS CLOSE TO THE BONE
• TO ALLOW ONLY A MINIMUM AMOUNT OF BOWSTRINGING &
MIGRATION VOLARLY FROM THE JOINT AXES.
• ENHANCES TENDON EXCURSION EFFICIENCY & WORK EFFICIENCY
OF LONG TENDONS
 EXTRINSIC FINGER EXTENSORS

• EXTRINSIC FINGER EXTENSORS ARE EXTENSOR DIGITORUM COMMUNIS (EDC),

EXTENSOR INDICIS PROPRIUS (EIP) & EXTENSOR DIGITI MINIMI (EDM).
• PASSES FROM FOREARM – BENEATH EXTENSOR RETINACULUM THAT MAINTAINS
PROXIMITY OF TENDONS TO THE JOINTS & IMPROVES EXCURSION EFFICIENCY.
• AT MCP JOINT LEVEL EDC TENDON OF EACH FINGER MERGES WITH BROAD
APONEUROSIS KNOWN AS DORSAL HOOD OR EXTENSOR HOOD.
• EIP & EDM TENDONS INSERTS INTO EDC TENDON OF INDEX & LITTLE FINGER AT
OR JUST PROXIMAL TO EXTENSOR HOOD.
• I
• EDC, EIP & EDM – EXTENSION OF MCP JOINTS OF FINGERS VIA
CONNECTION TO EXTENSOR HOOD & SAGITTAL BAND; ALSO
CAUSES WRIST EXTENSION.
• DISTAL TO THE EXTENSOR HOOD, TENDON SPLITS INTO 3
BANDS, AS –
• CENTRAL TENDON (INSERTS ON BASE OF MIDDLE HALANX)
• 2 LATERAL BANDS – REJOINS AS TERMINAL TENDON
(INSERTS INTO BASE OF DISTAL PHALANX)
 EXTENSOR MECHANISM

• FORMED BY EDC, EIP, EDM, EXTENSOR HOOD, CENTRAL TENDON, & THE LATERAL
BANDS THAT MERGE INTO TERMINAL TENDON.
• PASSIVE COMPONENTS ARE –TRIANGULAR LIGAMENTS (HELPS STABILIZE THE
BANDS ON THE DORSUM OF FINGERS) & SAGITTAL BANDS (CONNECTS VOLAR
SURFACE OF HOOD TO VOLAR PLATES & DEEP TRANSVERSE MC LIGAMENT –
PREVENTS BOWSTRINGING OF EXTENSOR TENDONS).
• THE DORSAL INTEROSSEI (DI), VOLAR INTEROSSEI (VI) & LUMBRICAL (INTRINSIC
MUSCULATURE) ARE ACTIVE COMPONENTS OF EXTENSOR MECHANISM.
• PASSIVE ELEMENT – OBLIQUE RETINACULAR LIGAMENT (ORL)
 INTRINSIC FINGER MUSCULATURE

• WITH ALL ATTACHMENTS DISTAL TO RADIOCARPAL JOINT.

DORSAL & VOLAR INTEROSSEI MUSCLES :-
• ARISE BETWEEN THE MC & ARE IMPORTANT PART OF EXTENSOR
MECHANISM.
• 4 DI & 3-4 VI MUSCLES
• DI & VI ARE ALIKE IN THEIR LOCATIONS & SOME OF THEIR
ACTIONS; CHARACTERIZED BY THEIR ABILITY TO PRODUCE MCP
JOINT ABDUCTION & ADDUCTION RESPECTIVELY.
• THE INTEROSSEI MUSCLE FIBERS JOIN EXTENSOR EXPANSION IN 2
LOCATIONS; SOME FIBERS ATTACH PROXIMALLY TO THE PROXIMAL
PHALANX & TO EXTENSOR HOOD; SOME ATTACH MORE DISTALLY TO
LATERAL BANDS & CENTRAL TENDONS.
• 1ST DI HAS MOST CONSISTENT ATTACHMENT - INTO BONY BASE OF
PROXIMAL PHALANX & EXTENSOR HOOD.
• 2ND & 3RD DI HAVE BOTH PROXIMAL & DISTAL ATTACHMENTS.
• 4TH DI – NOT ACTUALLY PRESENT – ABDUCTOR DIGITI MINIMI (ADM)
PLAYS THAT ROLE
• 3 VI MUSCLES – HAVE DISTAL ATTACHMENT ONLY (LATERAL
BAND / CENTRAL TENDON).
• PROXIMAL INTEROSSEI HAVE PREDOMINANT EFFECT ON MCP
JOINT ONLY, BUT DISTAL INTEROSSEI WILL PRODUCE THEIR
PREDOMINANT ACTION AT IP JOINTS & SOME EFFECT ON MCP
JOINTS.
• ALL DI & VI MUSCLES PASS DORSAL TO TRANSVERSE MC
LIGAMENT BUT VOLAR TO AXIS OF MCP JOINTS
FLEXION/EXTENSION.
ROLE OF INTEROSSEI AT MCP JOINT IN EXTENSION :-
• EFFECTIVE STABILIZERS & PREVENT CLAWING DUE TO FLEXION TORQUE.
• BALANCES PASSIVE TENSION IN THE EXTRINSIC EXTENSORS AT MCP JOINT
AT REST.
• INTEROSSEI MUSCLES ARE EFFECTIVE ABDUCTORS & ADDUCTORS AT MCP
JOINT WHEN MCP JOINT IS IN EXTENSION.
• PROXIMAL INSERTION MUSCLES ARE MORE EFFECTIVE THAN DISTAL
INSERTION MUSCLES. SO ABDUCTION IS STRONGER THAN ADDUCTION.
ROLE OF INTEROSSEI AT MCP JOINT IN FLEXION :-
• FROM EXTENSION TO FLEXION – TENDONS & ACTION LINES OF
INTEROSSEI MUSCLES MIGRATE VOLARLY AWAY FROM CORONAL AXIS
OF MCP JOINT – INCREASES MOMENT ARM FOR MCP FLEXION –
ACTION LINE BEING NEARLY PERPENDICULAR TO MOVING SEGMENT.
• INCREASES THE FLEXION TORQUE AT MCP JOINT AS IT APPROACHES TO
FULL FLEXION.
• THE VOLAR MIGRATION OF INTEROSSEI IS RESTRICTED BY DEEP
TRANSVERSE MC LIGAMENT – PREVENTS LOSS OF ACTIVE TENSION &
SERVES AS ANATOMICAL PULLEY.
• IN FULL MCP FLEXION, ABDUCTION/ADDUCTION IS RESTRICTED DUE TO
– TIGHT COLLATERAL LIGAMENTS, SHAPE OF CONDYLES ON MC HEADS
& ACTIVE INSUFFICIENCY OF FULLY SHORTENED INTEROSSEI MUSCLES.
ROLE OF INTEROSSEI AT IP JOINT IN IP EXTENSION:-
• ABILITY TO CAUSE IP EXTENSION IS INFLUENCED BY ITS ATTACHMENTS.
• IP JOINT EXTENSION PRODUCED BY DISTAL INTEROSSEI IS STRONGER
THAN MCP ABDUCTION/ADDUCTION DURING MCP EXTENSION.
• INDEX & LITTLE FINGER HAS WEAKER IP EXTENSION THAN MIDDLE &
RING FINGERS (FEWER DISTAL INTEROSSEI MUSCLES).
• OVERALL, PROXIMAL COMPONENTS ARE EFFECTIVE IN MCP FLEXION &
DISTAL COMPONENT IN IP EXTENSION. SO MOST CONSISTENT
ACTIVITY OF INTEROSSEI IS WHEN MCP JOINTS ARE FLEXED & IP
JOINTS ARE EXTENDED – ADVANTAGE OF OPTIMAL BIOMECHANICS
FOR BOTH DI & VI.
LUMBRICAL MUSCLES:-
• ONLY MUSCLES IN THE BODY THAT ATTACHES TO TENDONS OF OTHER MUSCLES.
• EACH MUSCLE ORIGINATES FROM TENDON OF FDP MUSCLE IN THE PALM – VOLAR
TO DEEP TRANSVERSE MC LIGAMENT – ATTACHES TO LATERAL BAND OF
EXTENSOR MECHANISM ON RADIAL SIDE.
• CROSSES MCP JOINT VOLARLY & IP JOINTS DORSALLY.
• DIFFERENCE IN INTEROSSEI & LUMBRICALS IS – MORE DISTAL INSERTION OF
LUMBRICALS, ORIGIN AT FDP & GREAT CONTRACTILE RANGE OF LUMBRICALS.
• EFFECTIVE IP EXTENSORS THAN MCP JOINT POSITION.
• DEEP TRANSVERSE MC LIGAMENT PREVENTS LUMBRICALS
MIGRATION DORSALLY & LOOSING TENSION AS MCP & IP EXTENDS.
• LUMBRICAL CONTRACTION INCREASES TENSION IN LATERAL BAND &
FDP TENDON TOO.
• ACTS AS BOTH AGONIST & SYNERGIST FOR IP EXTENSION.
• AS LUMBRICALS ACTIVATE TO CAUSE IP EXTENSION, THERE IS
EFFECTIVE RELEASE OF PASSIVE TENSION IN FDP TENDON.
• ALSO ASSIST FDP INDIRECTLY DURING HAND CLOSURE.
• FUNCTIONALLY MCP JOINT FLEXION IS WEAKER IN LUMBRICALS
THAN INTEROSSEI.
• LARGE RANGE OF LUMBRICALS, PREVENTS ACTIVE INSUFFICIENCY
WHEN SHORTENING OVER MCP & IP JOINTS.
THE THUMB
• CARPOMETACARPAL (CMC) OR
TRAPEZIOMETACARPAL (TM)
JOINT – BETWEEN TRAPEZIUM &
BASE OF 1ST METACARPAL HEAD.

• SADDLE JOINT WITH 2° OF

FREEDOM –
FLEXION/EXTENSION,
ABDUCTION/ADDUCTION ;
PERMITS SOME AXIAL ROTATION
– NET EFFECT BEING
CIRCUMDUCTION CALLED
“OPPOSITION” – PERMITS TIP OF
THUMB TO OPPOSE TIPS OF
FINGERS.
 CARPOMETACARPAL JOINT OF THUMB
• SADDLE SHAPED PORTION OF TRAPEZIUM IS CONCAVE IN
SAGITTAL PLANE (ABDUCTION/ADDUCTION) & CONVEX IN
FRONTAL PLANE (FLEXION/EXTENSION).
• SPHERICAL PORTION ON TRAPEZIUM – CONVEX IN ALL
DIRECTIONS.
• BASE OF 1ST MC HAS RECIPROCAL SHAPE TO THE TRAPEZIUM.
• FLEXION/EXTENSION & ABDUCTION/ADDUCTION OCCURS ON
SADDLE SURFACE BUT AXIAL ROTATION AT SPHERICAL SURFACE.

MOVEMENT PLANE AXIS

Flexion/extension Sagittal Oblique AP axis
Abduction/adduction Frontal Oblique coronal axis
• CAPSULE OF 1ST CMC JOINT IS RELATIVELY LAX BUT IS REINFORCED BY
RADIAL, ULNAR, VOLAR & DORSAL LIGAMENTS.
• INTERMETACARPAL LIGAMENT – HELPS TO TETHER THE BASE OF 1ST &
2ND MC, PREVENTS EXTREMES OF RADIAL & DORSAL DISPLACEMENT OF
BASE OF 1ST MC JOINT.
• DORSORADIAL & ANTERIOR OBLIQUE LIGAMENTS – KEY STABILIZERS
OF CMC JOINT.
• OA CHANGES WITH AGING ARE COMMON AT 1ST CMC JOINT, MAY BE
DUE TO CARTILAGE THINNING IN HIGH LOAD AREAS IMPOSED ON THIS
JOINT BY PINCH & GRASPS ACROSS INCONGRUENT SURFACES.
• CLOSED PACK POSITION – EXTREMES OF BOTH ABDUCTION &
ADDUCTION
• UNIQUE RANGE & DIRECTION OF MOTION.
• OPPOSITION IS SEQUENTIAL ABDUCTION, FLEXION &
ADDUCTION OF 1ST MC WITH SIMULTANEOUS ROTATION.
• THE FUNCTIONAL SIGNIFICANCE OF 1ST CMC JOINT IS
APPRECIATED IN ALL FORMS OF PREHENSION.
 MCP & IP JOINTS OF THUMB
MCP JOINT :-
• BETWEEN HEAD OF 1ST MC & BASE OF PROXIMAL PHALANX.
• CONDYLOID JOINT WITH 2° OF FREEDOM – FLEXION/EXTENSION &
ABDUCTION/ADDUCTION.
• THE JOINT CAPSULE, VOLAR PLATES & COLLATERAL LIGAMENTS ARE
SIMILAR TO OTHER MCP JOINTS.
• FUNCTION – TO PROVIDE ADDITIONAL FLEXION RANGE TO THUMB IN
OPPOSITION & TO ALLOW THUMB TO GRASP & CONTOUR TO OBJECTS.
• THOUGH STRUCTURE IS SAME FLEXION/EXTENSION RANGES ARE HALF OF
THE OTHER FINGERS. ABDUCTION/ADDUCTION IS EXTREMELY LIMITED.
IP JOINTS :-
• BETWEEN HEAD OF PROXIMAL PHALANX & BASE OF
DISTAL PHALANX.
• SIMILAR TO OTHER IP JOINTS OF THE FNGERS.
 MUSCULATURE

EXTRINSIC THUMB MUSCLES :-

• THE 4 EXTRINSIC THUMB MUSCLES ARE -
• FLEXOR POLLICIS LONGUS (FPL)
• EXTENSOR POLLICIS LONGUS (EPL)
• EXTENSOR POLLICIS BREVIS (EPB)
• ABDUCTOR POLLICIS LONGUS (APL)
FPL –
• INSERTS ON DISTAL PHALANX
• CORRELATES TO FDP
• AT WRIST, INVESTED BY RADIAL BURSA WHICH IS CONTINUOUS WITH ITS
DIGITAL TENDON SHEATH.
• UNIQUE; FUNCTIONS INDEPENDENTLY; ONLY MUSCLE RESPONSIBLE FOR
THUMB FLEXION AT IP JOINT.
• SITS BETWEEN THE SESAMOID BONES – DERIVES SOME PROTECTION
FROM THE BONES.
• OTHER 3 MUSCLES ARE LOCATED DORSORADIALLY.
• EPB & APL – COMMON COURSE – DORSAL FOREARM – 1ST DORSAL
COMPARTMENT-RADIAL ASPECT OF WRIST.
• ABL INSERTS ON BASE OF MC JOINT. EPB INSERTS ON BASE OF PROXIMAL
PHALANX - ABDUCTS CMC JOINT , SLIGHT RADIAL DEVIATION OF WRIST.
• EBP-EXTENSION OF MC JOINT
• EPL-INSERTS ON BASE ON BASE OF DISTAL PHALANX- AT PROXIMAL PHALANX EPL
IS JOINED BY EXPANSION FROM APB, 1ST VOLAR INTEROSSEI & ADDUCTOR
POLLICIS (ADP)-EXTENDS THUMBS IP JOINT TO NEUTRAL BUT NO
HYPEREXTENSION, EXTENDS AND ADDUCTS 1ST CMC JOINT
INTRINSIC THUMB MUSCLES :-
• 5 THENARS MUSCLES – ORIGINATES FROM CARPAL BONES
AND FLEXOR RETINACULUM.
• OPPONENS POLLICIS(OP)- ONLY INTRINSIC MUSCLE
HAVING DISTAL ATTACHMENT ON 1ST MC ON THE LATERAL
SIDE – VERY EFFECTIVE IN POSITIONING THE MC IN AN
ABDUCTED ,FLEXED AND ROTATED POSTURE
• APB , FPB , ADP &1ST VOLAR INTEROSSEI INSERTS ON
PROXIMAL PHALANX.
• FPB HAS TWO HEADS OF INSERTION.
• LARGE LAT. HEAD ATTACHES TO ABL-ABDUCTION.
• MEDIAL HEAD ATTACHES TO ADP-ADDUCTION
• 1ST DORSAL INTEROSSEI- THOUGH NOT CONSIDER AS A
THENAR MUSCLE CONTRIBUTES TO THUMB FUNCTION-CMC
JOINT DISTRACTION, ASSIST THUMB ADDUCTION.
• THENAR MUSCLES- ACTIVE IN MOST GRASPING ACTIVITIES
• ACTIVITY OF EXTRINSIC THUMB MUSCLE IN GRASP IS PARTIALLY
FUNCTION OF HELPING TO POSITION THE MCP AND IP JOINTS
, MAIN FUNCTION BEING RETURNING THE THUMB TO
EXTENSION FROM ITS POSITION
 OSTEOKINEMATICS

• THE OSTEOKINEMATICS OF THE WRIST ARE DEFINED FOR 2 DEGREES OF

FREEDOM:
• FLEXION-EXTENSION AND
• ULNAR-RADIAL DEVIATION
• WRIST CIRCUMDUCTION—A FULL CIRCULAR MOTION MADE BY THE WRIST—IS A
COMBINATION OF THE ALL FOUR MOVEMENTS, NOT A DISTINCT THIRD DEGREE
OF FREEDOM
• MOST NATURAL DYNAMIC MOVEMENTS OF THE WRIST COMBINE ELEMENTS OF
BOTH FRONTAL AND SAGITTAL PLANES:
• EXTENSION TENDS TO OCCUR WITH RADIAL DEVIATION, AND
• FLEXION WITH ULNAR DEVIATION
• THE RESULTING NATURAL PATH OF MOTION FOR THE
WRIST FOLLOWS A SLIGHTLY OBLIQUE PATH

• AXIS:

• THE AXIS OF ROTATION FOR WRIST MOVEMENTS IS

REPORTED TO PASS THROUGH THE HEAD OF THE
CAPITATE
• THE AXIS RUNS IN A NEAR MEDIAL-LATERAL
DIRECTION FOR FLEXION AND EXTENSION AND

• NEAR ANTERIOR-POSTERIOR DIRECTION FOR RADIAL

AND ULNAR DEVIATION

• ALTHOUGH THE AXES ARE DEPICTED AS

STATIONARY, IN REALITY THEY MIGRATE SLIGHTLY
THROUGHOUT THE FULL RANGE OF MOTION
• THE FIRM ARTICULATION BETWEEN THE CAPITATE AND THE BASE OF THE THIRD
METACARPAL BONE CAUSES THE ROTATION OF THE CAPITATE TO DIRECT THE
OSTEOKINEMATIC PATH OF THE ENTIRE HAND
• FLEXION-EXTENSION:
• THE WRIST ROTATES IN THE SAGITTAL PLANE ABOUT 130 TO 160 DEGREES
• THE WRIST FLEXES FROM 0 DEGREES TO ABOUT 70 TO 85 DEGREES AND
EXTENDS FROM 0 DEGREES TO ABOUT 60 TO 75 DEGREES
• END-RANGE EXTENSION IS NATURALLY LIMITED BY STIFFNESS IN THE THICK
PALMAR RADIOCARPAL LIGAMENTS
• IN SOME PERSONS, A GREATER THAN AVERAGE PALMAR TILT OF THE DISTAL
RADIUS MAY ALSO LIMIT EXTENSION RANGE
• ULNAR AND RADIAL DIVATION:
• THE WRIST ROTATES IN THE FRONTAL PLANE APPROXIMATELY 50 TO 60
DEGREES
• RADIAL AND ULNAR DEVIATION OF THE WRIST IS MEASURED AS THE ANGLE
BETWEEN THE RADIUS AND THE SHAFT OF THE THIRD METACARPAL
• ULNAR DEVIATION OCCURS FROM 0 DEGREES TO ABOUT 35 TO 40 DEGREES
• RADIAL DEVIATION OCCURS FROM 0 DEGREES TO ABOUT 15 TO 20 DEGREES
• PRIMARILY BECAUSE OF THE ULNAR TILT OF THE DISTAL RADIUS, MAXIMUM
ULNAR DEVIATION NORMALLY IS DOUBLE THE MAXIMUM AMOUNT OF RADIAL
DEVIATION
 ARTHROKINEMATICS

• MANY DIFFERENT METHODOLOGIES HAVE BEEN USED TO STUDY THE KINEMATICS OF THE WRIST
THESE TECHNIQUES INCLUDE THE FOLLOWING:
• • RADIOGRAPHY
• • CINERADIOGRAPHY
• • ANATOMIC DISSECTION
• • PLACEMENT OF PINS IN BONES
• • THREE-DIMENSIONAL (3D) COMPUTER IMAGING
• • ELECTROMAGNETIC TRACKING DEVICES
• • 3D COMPUTED TOMOGRAPHY (CT)
• • THE MOST FUNDAMENTAL AND ACCEPTED PREMISE OF CARPAL
KINEMATICS IS THAT THE WRIST IS A DOUBLE-JOINT SYSTEM, WITH
MOVEMENT OCCURRING SIMULTANEOUSLY AT BOTH THE
RADIOCARPAL AND MIDCARPAL JOINTS
WRIST EXTENSION AND FLEXION:

• THE ESSENTIAL KINEMATICS OF SAGITTAL PLANE

MOTION AT THE WRIST CAN BE APPRECIATED
BY VISUALIZING THE WRIST AS AN
ARTICULATED CENTRAL COLUMN, FORMED BY
THE LINKAGES BETWEEN

• THE DISTAL RADIUS,

• LUNATE,

• CAPITATE, AND

• THIRD METACARPAL
• WITHIN THIS COLUMN, THE RADIOCARPAL
JOINT IS REPRESENTED BY THE ARTICULATION
BETWEEN THE RADIUS AND LUNATE
• THE MEDIAL COMPARTMENT OF THE MIDCARPAL JOINT IS REPRESENTED BY THE ARTICULATION
BETWEEN THE LUNATE AND CAPITATE
• THE CARPOMETACARPAL JOINT IS A SEMI RIGID ARTICULATION FORMED BETWEEN THE CAPITATE
AND THE BASE OF THE THIRD METACARPAL
DYNAMIC INTERACTION WITHIN THE JOINTS OF THE CENTRAL COLUMN OF THE WRIST:
• THE ARTHROKINEMATICS OF EXTENSION AND FLEXION ARE BASED ON SYNCHRONOUS
• CONVEX-ON-CONCAVE ROTATIONS AT BOTH THE RADIOCARPAL AND THE MIDCARPAL JOINTS
AT THE RADIOCARPAL JOINT- (DEPICTED IN RED)
EXTENSION OCCURS AS THE CONVEX SURFACE OF THE LUNATE ROLLS DORSALLY ON THE RADIUS
AND SIMULTANEOUSLY SLIDES PALMARLY
THE ROLLING MOTION DIRECTS THE LUNATE’S DISTAL SURFACE DORSALLY, TOWARD THE DIRECTION
OF EXTENSION
• AT THE MIDCARPAL JOINT- (ILLUSTRATED IN WHITE)
• THE HEAD OF THE CAPITATE ROLLS DORSALLY ON THE LUNATE AND
SIMULTANEOUSLY SLIDES IN A PALMAR DIRECTION
• COMBINING THE ARTHROKINEMATICS OVER BOTH JOINTS PRODUCES FULL WRIST
EXTENSION
• FULL WRIST EXTENSION ELONGATES THE PALMAR RADIOCARPAL LIGAMENTS AND
ALL MUSCLES THAT CROSS ON THE PALMAR SIDE OF THE WRIST
• TENSION WITHIN THESE STRETCHED STRUCTURES HELPS STABILIZE THE WRIST IN ITS
CLOSE-PACKED POSITION OF FULL EXTENSION
THE ARTHROKINEMATICS OF WRIST FLEXION ARE SIMILAR TO THOSE DESCRIBED FOR
EXTENSION BUT OCCUR IN A REVERSE FASHION
• ULNAR AND RADIAL DEVIATION OF THE WRIST:
• DYNAMIC INTERACTION BETWEEN THE RADIOCARPAL AND MIDCARPAL JOINT:
LIKE FLEXION AND EXTENSION, ULNAR AND RADIAL DEVIATION OCCURS THROUGH
SYNCHRONOUS CONVEX-ON-CONCAVE ROTATIONS AT BOTH RADIOCARPAL AND MIDCARPAL
JOINTS
ULNAR DEVATION:
• THE MIDCARPAL JOINT AND, TO A LESSER EXTENT, THE RADIOCARPAL JOINT CONTRIBUTE TO
OVERALL WRIST MOTION
• AT THE RADIOCARPAL JOINT (SHOWN IN RED)-
• THE SCAPHOID, LUNATE, AND TRIQUETRUM ROLL ULNARLY AND SLIDE A SIGNIFICANT DISTANCE
• RADIALLY
• THE EXTENT OF THIS RADIAL SLIDE IS APPARENT BY THE FINAL POSITION OF THE LUNATE RELATIVE
TO THE RADIUS AT FULL ULNAR DEVIATION
• AT THE MIDCARPAL JOINT-
• OCCURS PRIMARILY FROM THE CAPITATE ROLLING ULNARLY AND
SLIDING SLIGHTLY RADIALLY
• FULL RANGE OF ULNAR DEVIATION CAUSES THE TRIQUETRUM TO
CONTACT THE ARTICULAR DISC
• COMPRESSION OF THE HAMATE AGAINST THE TRIQUETRUM PUSHES
THE PROXIMAL ROW OF CARPAL BONES AGAINST THE STYLOID
PROCESS OF THE RADIUS
• THIS COMPRESSION HELPS STABILIZE THE WRIST FOR ACTIVITIES THAT
REQUIRE LARGE GRIPPING FORCES
• RADIAL DEVATION:
• OCCURS THROUGH SIMILAR ARTHROKINEMATICS AS DESCRIBED
FOR ULNAR DEVIATION
• THE AMOUNT OF RADIAL DEVIATION AT THE RADIOCARPAL JOINT IS
LIMITED AS THE RADIAL SIDE OF THE CARPUS IMPINGES AGAINST
THE STYLOID PROCESS OF THE RADIUS
• CONSEQUENTLY, A GREATER AMOUNT OF THE RADIAL DEVIATION
OCCURS AT THE MIDCARPAL JOINT
 CARPAL INSTABILITY

• AN UNSTABLE WRIST DEMONSTRATES MALALIGNMENT OF ONE OR MORE CARPAL

BONES, TYPICALLY ASSOCIATED WITH ABNORMAL AND PAINFUL KINEMATICS
• THE PRIMARY CAUSE OF CARPAL INSTABILITY IS LAXITY OR RUPTURE OF SPECIFIC
LIGAMENTS
• THE INTRINSIC LIGAMENTS CAN TOLERATE GREATER RELATIVE STRETCH BEFORE RUPTURE
THAN CAN THE EXTRINSIC LIGAMENTS, THEY ARE MORE FREQUENTLY INJURED
• THE CLINICAL MANIFESTATION OF CARPAL INSTABILITY DEPENDS ON THE INJURED
LIGAMENT (OR LIGAMENTS) AND THE SEVERITY OF THE DAMAGE
• CARPAL INSTABILITY MAY BE STATIC (DEMONSTRATED AT REST) OR DYNAMIC
(DEMONSTRATED ONLY DURING FREE OR RESISTED MOVEMENT)
• TWO COMMON FORMS OF CARPAL INSTABILITY:
• 1. ROTATIONAL COLLAPSE OF WRIST: THE “ZIGZAG” DEFORMITY
• DORSAL INTERCALATED SEGMENT INSTABILITY (DISI)
• VOLAR INTERCALATED SEGMENT INSTABILITY (VISI)

• 2. ULNAR TRANSLOCATION OF THE CARPUS

• ROTATIONAL COLLAPSE OF WRIST:
• MECHANICALLY, THE WRIST CONSISTS OF A MOBILE PROXIMAL ROW OF CARPAL BONES
INTERCALATED OR INTERPOSED BETWEEN TWO RIGID STRUCTURES: THE FOREARM AND THE
DISTAL ROW OF CARPAL BONES
• LIKE CARS OF A FREIGHT TRAIN THAT ARE SUBJECT TO DERAILMENT, THE PROXIMAL ROW OF
CARPAL BONES IS SUSCEPTIBLE TO A ROTATIONAL COLLAPSE IN A “ZIGZAG” FASHION WHEN
COMPRESSED FROM BOTH ENDS
• THE COMPRESSION FORCES THAT CROSS THE WRIST
ARISE FROM MUSCLE ACTIVATION AND CONTACT WITH
THE SURROUNDING ENVIRONMENT

• THE LUNATE IS THE MOST FREQUENTLY DISLOCATED

CARPAL BONE

• NORMALLY ITS STABILITY IS PROVIDED BY LIGAMENTS

AND ARTICULAR CONTACT WITH ADJACENT BONES OF
THE PROXIMAL ROW, MOST NOTABLY THE SCAPHOID

BY VIRTUE OF ITS TWO POLES, THE SCAPHOID FORMS AN

IMPORTANT MECHANICAL LINK BETWEEN THE LUNATE AND
THE MORE STABLE, DISTAL ROW OF CARPAL BONES

• DISRUPTION OF THE MECHANICAL LINK BETWEEN THE

TWO BONES CAN RESULT IN SCAPHOLUNATE
DISSOCIATION AND SUBSEQUENT MALALIGNMENT OF
EITHER OR BOTH BONES
• DORSAL INTERCALATED SEGMENT INSTABILITY (DISI):
THE MORE UNSTABLE LUNATE MOST OFTEN DISLOCATES, OR SUBLUXES , SO ITS DISTAL
ARTICULAR SURFACE FACES DORSALLY
THIS CONDITION IS REFERRED TO CLINICALLY AS DORSAL INTERCALATED SEGMENT
INSTABILITY
VOLAR INTERCALATED SEGMENT INSTABILITY (VISI):
• INJURY TO OTHER LIGAMENTS, SUCH AS THE LUNOTRIQUETRAL LIGAMENT, MAY
CAUSE THE LUNATE TO DISLOCATE SUCH THAT ITS DISTAL ARTICULAR SURFACE FACES
VOLARLY (PALMARLY)
• THIS CONDITION IS REFERRED TO AS VOLAR (PALMAR) INTERCALATED SEGMENT
INSTABILITY
• CHANGES IN THE NATURAL ARTHROKINEMATICS MAY CREATE REGIONS OF
HIGH STRESS, EVENTUALLY LEADING TO JOINT DESTRUCTION, CHRONIC
INFLAMMATION, AND CHANGES IN THE SHAPES OF THE BONES
• A PAINFUL AND UNSTABLE WRIST MAY FAIL TO PROVIDE A STABLE PLATFORM
FOR THE HAND
• ULNAR TRANSLOCATION OF THE CARPUS:
• AS POINTED OUT EARLIER, THE DISTAL END OF THE RADIUS IS ANGLED FROM
SIDE TO SIDE SO THAT ITS ARTICULAR SURFACE IS SLOPED ULNARLY ABOUT 25
DEGREES
• THIS ULNAR TILT OF THE RADIUS CREATES A NATURAL TENDENCY FOR THE
CARPUS TO SLIDE (TRANSLATE) IN AN ULNAR DIRECTION
• FIGURE SHOWS THAT A WRIST WITH AN ULNAR TILT
OF 25 DEGREES HAS AN ULNAR TRANSLATION
FORCE OF 42% OF THE TOTAL COMPRESSION
FORCE THAT CROSSES THE WRIST

• THIS TRANSLATIONAL FORCE IS NATURALLY RESISTED

BY PASSIVE TENSION FROM VARIOUS EXTRINSIC
LIGAMENTS, SUCH AS PALMAR RADIOCARPAL
LIGAMENT

• A DISEASE SUCH AS RHEUMATOID ARTHRITIS MAY

WEAKEN THE LIGAMENTS OF THE WRIST

• OVER TIME, THE CARPUS MAY MIGRATE ULNARLY

• AN EXCESSIVE ULNAR TRANSLOCATION CAN

SIGNIFICANTLY ALTER THE BIOMECHANICS OF THE
ENTIRE WRIST AND HAND
 FUNCTIONS OF THE MUSCLES

• THE WRIST IS CONTROLLED BY

• A PRIMARY AND
• A SECONDARY SET OF MUSCLES
• THE TENDONS OF THE MUSCLES WITHIN THE PRIMARY SET ATTACH DISTALLY
WITHIN THE CARPUS, OR THE ADJACENT PROXIMAL END OF THE METACARPALS;
THESE MUSCLES ACT ESSENTIALLY ON THE WRIST ONLY
• THE TENDONS OF THE MUSCLES WITHIN THE SECONDARY SET CROSS THE CARPUS
AS THEY CONTINUE DISTALLY TO ATTACH TO THE DIGITS
• THE SECONDARY MUSCLES THEREFORE ACT ON THE WRIST AND THE HAND
 FUNCTION OF THE WRIST EXTENSORS

• MUSCLE ANATOMY:

THE PRIMARY WRIST EXTENSORS ARE

EXTENSOR CARPI RADIALIS LONGUS,

EXTENSOR CARPI RADIALIS BREVIS, AND

EXTENSOR CARPIULNARIS

• THE SECONDARY WRIST EXTENSORS ARE

EXTENSOR DIGITORUM

• EXTENSOR INDICIS

• EXTENSOR DIGITI MINIMI

• EXTENSOR POLLICIS LONGUS

• THE PROXIMAL ATTACHMENTS OF THE PRIMARY WRIST EXTENSORS ARE LOCATED ON AND NEAR THE LATERAL (“EXTENSOR-
SUPINATOR”) EPICONDYLE OF THE HUMERUS AND DORSAL BORDER OF THE ULNA

DISTALLY, THE EXTENSOR CARPI RADIALIS LONGUS AND BREVIS ATTACH SIDE BY SIDE TO THE DORSAL BASES OF THE SECOND
AND THIRD METACARPALS, RESPECTIVELY; THE EXTENSOR CARPI ULNARIS ATTACHES TO THE DORSAL BASE OF THE FIFTH
METACARPAL

• THE TENDONS OF THE MUSCLES THAT CROSS THE DORSAL AND DORSAL-RADIAL SIDE OF THE WRIST ARE SECURED IN
PLACE BY THE EXTENSOR RETINACULUM

• ULNARLY, THE EXTENSOR RETINACULUM WRAPS AROUND THE STYLOID PROCESS OF THE ULNA TO ATTACH PALMARLY TO
THE TENDON OF THE FLEXOR CARPI ULNARIS, PISIFORM BONE, AND PISOMETACARPAL LIGAMENT

• RADIALLY, THE RETINACULUM ATTACHES TO THE STYLOID PROCESS OF THE RADIUS AND THE RADIAL

• COLLATERAL LIGAMENT

• THE EXTENSOR RETINACULUM PREVENTS THE UNDERLYING TENDONS FROM “BOWSTRINGING” UP AND AWAY FROM THE
RADIOCARPAL JOINT DURING ACTIVE MOVEMENTS OF THE WRIST
• BETWEEN THE EXTENSOR RETINACULUM AND THE UNDERLYING
BONES ARE SIX FIBROOSSEUS COMPARTMENTS THAT HOUSE THE
TENDONS ALONG WITH THEIR SYNOVIAL SHEATHS
• WRIST EXTENSOR ACTIVITY WHILE MAKING A FIST:

• THE MAIN FUNCTION OF THE WRIST EXTENSORS IS

TO POSITION AND STABILIZE THE WRIST DURING
ACTIVITIES INVOLVING ACTIVE FLEXION OF THE
FINGERS

OF PARTICULAR IMPORTANCE IS THE ROLE OF THE WRIST

EXTENSOR MUSCLES IN MAKING A FIST OR PRODUCING
A STRONG GRIP

RAPIDLY TIGHTEN AND RELEASE THE FIST AND NOTE THE

STRONG SYNCHRONOUS ACTIVITY FROM THE WRIST
EXTENSORS

THE EXTRINSIC FINGER FLEXOR MUSCLES, NAMELY THE

FLEXOR DIGITORUM PROFUNDUS AND FLEXOR
DIGITORUM SUPERFICIALIS, POSSESS A SIGNIFICANT
INTERNAL MOMENT ARM AS WRIST FLEXORS
• THE WRIST EXTENSOR MUSCLES MUST COUNTERBALANCE THE
SIGNIFICANT WRIST FLEXION TORQUE PRODUCED BY THE FINGER
FLEXOR MUSCLES
• AS A STRONG GRIP IS APPLIED TO AN OBJECT, THE WRIST
EXTENSORS TYPICALLY HOLD THE WRIST IN ABOUT 30 TO 35
DEGREES OF EXTENSION AND ABOUT 5 DEGREES OF ULNAR
DEVIATION
• GRIP STRENGTH IS SIGNIFICANTLY REDUCED WHEN THE WRIST IS
FULLY FLEXED
 FUNCTION OF THE WRIST FLEXORS

• MUSCLE ANATOMY:

• PRIMARY SET (ACT ON WRIST ONLY)

• • FLEXOR CARPI RADIALIS

• • FLEXOR CARPI ULNARIS

• • PALMARIS LONGUS

• SECONDARY SET (ACT ON WRIST AND HAND)

• • FLEXOR DIGITORUM PROFUNDUS

• • FLEXOR DIGITORUM SUPERFICIALIS

• • FLEXOR POLLICIS LONGUS

• • ABDUCTOR POLLICIS LONGUS

• • EXTENSOR POLLICIS BREVIS

• THE PROXIMAL ATTACHMENTS OF THE PRIMARY
WRIST FLEXORS ARE LOCATED ON AND NEAR THE
MEDIAL (“FLEXOR-PRONATOR”) EPICONDYLE OF THE
HUMERUS AND DORSAL BORDER OF THE ULNA

• TECHNICALLY, THE TENDON OF THE FLEXOR CARPI

RADIALIS DOES NOT CROSS THE WRIST THROUGH
THE CARPAL TUNNEL; RATHER, THE TENDON PASSES
IN A SEPARATE TUNNEL FORMED BY A GROOVE IN
THE TRAPEZIUM AND FASCIA FROM THE ADJACENT
TRANSVERSE CARPAL LIGAMENT

• THE TENDON OF THE FLEXOR CARPI RADIALIS

ATTACHES DISTALLY TO THE PALMAR BASE OF THE
SECOND AND SOMETIMES THE THIRD METACARPAL

• THE PALMARIS LONGUS HAS A DISTAL ATTACHMENT

PRIMARILY TO THE THICK APONEUROSIS OF THE
PALM
• THE TENDON OF THE FLEXOR CARPI ULNARIS COURSES DISTALLY TO ATTACH TO THE PISIFORM BONE
AND, IN A PLANE SUPERFICIAL TO THE TRANSVERSE CARPAL LIGAMENT, INTO THE PISOHAMATE AND
PISOMETACARPAL LIGAMENTS AND THE BASE OF THE FIFTH METACARPAL BONE

• FUNCTIONAL CONSIDERATION:
• DURING ACTIVE WRIST FLEXION, THE FLEXOR CARPI RADIALIS AND FLEXOR CARPI ULNARIS ACT
TOGETHER AS SYNERGISTS WHILE SIMULTANEOUSLY OPPOSING EACH OTHER’S RADIAL AND ULNAR
DEVIATION ABILITY

THE WRIST FLEXOR MUSCLES PRODUCE ABOUT 70% GREATER ISOMETRIC TORQUE THAN THE

• WRIST EXTENSOR MUSCLES

• ACTIVITIES SUCH AS LIFTING OR PULLING HEAVY OBJECTS NORMALLY DEMAND STRENGTH IN BOTH THE
WRIST FLEXOR AND FINGER FLEXOR MUSCULATURE
• STRONG COACTIVATION OF THE WRIST EXTENSOR MUSCLES IS REQUIRED DURING THESE ACTIVITIES TO
PREVENT A RELATIVELY INEFFECTIVE POSITION OF COMBINED WRIST AND FINGER FLEXION
 FUNCTION OF THE RADIAL AND ULNAR
DEVIATORS

• RADIAL DEVIATORS OF THE WRIST:

• EXTENSOR CARPI RADIALIS LONGUS
• EXTENSOR CARPI RADIALIS BREVIS
• EXTENSOR POLLICIS LONGUS
• EXTENSOR POLLICIS BREVIS
• FLEXOR CARPI RADIALIS
• ABDUCTOR POLLICIS LONGUS
• FLEXOR POLLICIS LONGUS
• FIGURE SHOWS THE RADIAL DEVIATOR MUSCLES
CONTRACTING DURING USE OF A HAMMER

• ALL THESE MUSCLES PASS LATERALLY TO THE

WRIST’S ANTERIOR-POSTERIOR AXIS OF ROTATION

• THE ACTION OF THE EXTENSOR CARPI RADIALIS

LONGUS AND THE FLEXOR CARPI RADIALIS, SHOWN
WITH MOMENT ARMS, ILLUSTRATES A FINE EXAMPLE
OF TWO MUSCLES COOPERATING AS SYNERGISTS
FOR ONE MOTION BUT AS ANTAGONISTS FOR
ANOTHER

• THE NET EFFECT OF THIS MUSCULAR COOPERATION

PRODUCES A RADIALLY DEVIATED WRIST, WELL
STABILIZED IN SLIGHT EXTENSION FOR OPTIMAL
GRASP OF THE HAMMER
• ULNA DEVIATOR OF THE WRIST:
• EXTENSOR CARPI ULNARIS
• FLEXOR CARPI ULNARIS
• FLEXOR DIGITORUM PROFUNDUS AND SUPERFICIALIS
• EXTENSOR DIGITORUM
FIGURE SHOWS THIS STRONG PAIR OF ULNAR DEVIATOR MUSCLES
CONTRACTING AS A NAIL IS STRUCK WITH A HAMMER
BOTH THE FLEXOR AND EXTENSOR CARPI ULNARIS CONTRACT SYNERGISTICALLY
TO PERFORM THE ULNAR DEVIATION BUT ALSO STABILIZE THE WRIST IN A
SLIGHTLY EXTENDED POSITION
• BECAUSE OF THE STRONG FUNCTIONAL ASSOCIATION BETWEEN
THE FLEXOR AND EXTENSOR CARPI ULNARIS MUSCLES, INJURY TO
EITHER MUSCLE CAN INCAPACITATE THE OVERALL KINETICS OF
ULNAR DEVIATION
PREHENSION
• PREHENSION ACTIVITIES INVOLVES GRASPING OR TAKING
HOLD OF AN OBJECT BETWEEN ANY 2 SURFACES OF
HAND. THUMB PATICIPATE IN MOST BUT NOT ALL THE
PREHENSION ACTIVITIES. Prehension

Power grip Precision handling

(full hand (finger thumb
prehension) prehension)
 POWER GRIP PRECISION
Forceful act resulting in flexion of Skillful placement of an object
all finger joints. The thumb acts as a between fingers or between
stabilizer to the object held in finger & thumb. No involvement
fingers or palm. of palm.

Phases • Opening of hand • Opening of hand

• Positioning the fingers • Positioning the fingers
• Bringing the fingers to the object • Bringing the fingers to the
• Maintaining the static phase object

Object is grasped to move through Fingers & thumb grasps the

space by some proximal joints object to manipulate it within the
hand
Thumb is generally adducted. Thumb is generally abducted.
 POWER GRIP

• FINGERS FUNCTION TO CLAMP ON OR HOLD AN OBJECT INTO THE PALM.

• FINGERS SUSTAIN FLEXION POSITION THAT VARIES IN DEGREE WITH SIZE, SHAPE
& WEIGHT OF THE OBJECT; PALMAR ARCHES AROUND IT.
• THUMB – SERVES AS ADDITIONAL SURFACE TO FINGER PALM BY ADDUCTING
AGAINST THE OBJECT.
• DIFFERENT POWER GRIPS –
• CYLINDRICAL GRIP
• SPHERICAL GRIP
• HOOK GRIP
• LATERAL PREHENSION
 CYLINDRICAL GRIP
• INVOLVES USE OF ALL FINGER FLEXORS
• FDP WORKS PREDOMINANTLY
• INTEROSSEI MUSCLES – PRIMARY MCP
FLEXORS, ABDUCTORS/ADDUCTORS
• FPL & THENAR MUSCLES- FLEXION &
ADDUCTION OF THUMB.
• HYPOTHENAR EMINENCE-FLEX &
ABDUCT MCP JOINT.
• TYPICALLY WITH WRIST IN NEUTRAL /
EXTENSION & SLIGHT ULNAR
DEVIATION.
• E.G. TURNING A DOOR KNOB.
 SPHERICAL GRIP

• MOST RESPECT TO
CYLINDRICAL GRIP BUT
GREATER SPREAD OF
FINGERS TO ENCOMPASS
THE OBJECT.
• MORE ACTIVITY OF
INTEROSSEUS FOR E.G.
HOLDING A BALL.
 HOOK GRIP

• SPECIALISED FORM OF
PREHENSION- FUNCTION
PRIMARILY OF FINGERS.
• MAJOR ACTIVITY OF FDP &FDS.
• LOAD – MORE DISTALLY FDP,
PROXIMALLY (FDS)
• THUMB- MODERATE TO FULL
EXTENSION.
• E.G. - CARRYING A BRIEFCASE.
 LATERAL PREHENSION

• CONTACT BETWEEN TWO

FINGERS.
• MCP & IP JOINT- IN EXTENSION
AS CONTIGIOUS MCP JOINT
SIMULTANEOUSLY ABDUCT &
ADDUCT
• EXTENSOR MUSCULATURE PRE
DOMINATES.
• E.G. HOLDING A PAPER
 PRECISION HANDLING

• REQUIRE MUCH FINER MOTOR CONTROL & MORE DEPENDENT ON

INTACT SENSATION.
• IN “TWO – JAW CHUCK”,ONE JAW IS THUMB( ABDUCTED & ROTATED)
& 2ND JAW IS BY DISTAL TIP, THE PAD OR THE SIDE OF FINGER.
• 3 VARIETIES OF PRCESION ARE –
• PAD TO PAD PREHENSION
• TIP TO TIP PREHENSION
• PAD TO SIDE PREHENSION.
 PAD TO PAD PREHENSION

• INVOLVES OPPOSITION OF PAD OR PULP OF

THUMB TO PAD OR PULP OF FINGER.

• THE PAD HAS GREATEST CONCENTRATION OF

TACTILE CORPUSCLES.

• MCP & PROXIMAL IP JOINT OF THE FINGER –

PARTIALLY FLEXED
• DISTAL IP JOINT- EXTENDED OR SLIGHTLY FLEXED.

• THUMB- CMC FLEXION, ABDUCTION & ROTATION;

MCP & IP JOINT PARTIALLY FLEXED OR EXTENDED.

• E.G. HOLDING A FORECEPS

 TIP TO TIP PREHENSION

• MUSCLE ACTIVITY ALMOST

SAME TO PAD TO PAD
PREHENSION WITH SOME KEY
DIFFERENCES LIKE IP JOINT OF
THE FINGERS & THE THUMB
HAVE RANGE & FORCE TO
CREATE FULL FLEXION.
• MCP JOINT OF OPPOSING
FINGER DEVIATES ULNARLY.
• E.G. HOLDING A PEN.
 SIDE TO SIDE PREHENSION

• KEY GRIP OR LATERAL

PINCH.
• BETWEEN THUMB & SIDE OF
INDEX FINGER
• THUMB-MORE ADDUCTED &
LESS ROTATED LEAST PRECISE
FORM OF PRECESION
HANDLING.
 FUNCTIONAL POSITION OF WRIST &
HAND

• THE FUNCTIONAL POSITION IS –

• WRIST COMPLEX IN SLIGHT EXTENSION (20°) &
SLIGHT ULNAR DEVIATION (10°)
• FINGERS MODERATELY FLEXED AT MCP JOINT (45°) &
PROXIMAL IP JOINT (30°) & SLIGHTLY FLEXED AT
DISTAL IP JOINT
 HAND DEFORMITY IN
RHEUMATOID ARTHRITIS
• RHEUMATOID ARTHRITIS IS A SYSTEMIC DISEASE BUT THE MOST
CHARACTERISTIC LESIONS ARE SEEN IN THE SYNOVIUM OR WITHIN
RHEUMATOID NODULES. THE SYNOVIUM IS ENGORGED WITH NEW
BLOOD VESSELS AND PACKED FULL OF INflAMMATORY CELLS.
 STAGES OF RA

1. PRE CLINICAL
2. SYNOVITIS
3. DESTRUCTION
4. DEFORMITY
• STAGE 1 – PRE-CLINICAL WELL BEFORE RA BECOMES
CLINI- CALLY APPARENT THE IMMUNE PATHOLOGY IS
ALREADY BEGIN- NING. RAISED ESR, C-REACTIVE PROTEIN
(CRP) AND RF MAY BE DETECTABLE YEARS BEFORE THE
fiRST DIAGNOSIS.
• STAGE 2 – SYNOVITIS EARLY CHANGES ARE VASCULAR CONGES-
TION WITH NEW BLOOD VESSEL FORMATION, PROLIFERATION OF
SYNOVIOCYTES AND INfiLTRATION OF THE SUBSYNOVIAL LAYERS BY
POLYMORPHS, LYMPHOCYTES AND PLASMA CELLS. THERE IS
THICKENING OF THE CAPSULAR STRUCTURES, VILLOUS FORMA- TION
OF THE SYNOVIUM AND A CELL-RICH EFFUSION INTO THE JOINTS
AND TENDON SHEATHS. ALTHOUGH PAINFUL, SWOLLEN AND TENDER,
THESE STRUCTURES ARE STILL INTACT AND MOBILE, AND THE
DISORDER IS POTENTIALLY REVERSIBLE
• STAGE 3 – DESTRUCTION PERSISTENT INflAMMATION CAUSES
JOINT AND TENDON DESTRUCTION. ARTICULAR CARTILAGE IS
ERODED, PARTLY BY PROTEOLYTIC ENZYMES, PARTLY BY VASCU-
LAR TISSUE IN THE FOLDS OF THE SYNOVIAL REflECTIONS, AND
PARTLY DUE TO DIRECT INVASION OF THE CARTILAGE BY A PAN-
NUS OF GRANULATION TISSUE CREEPING OVER THE ARTICULAR
SURFACE. AT THE MARGINS OF THE JOINT, BONE IS ERODED BY
GRANULATION TISSUE INVASION AND OSTEOCLASTIC
RESORPTION
• STAGE 4 – DEFORMITY THE COMBINATION OF ARTICULAR
DESTRUCTION, CAPSULAR STRETCHING AND TENDON RUPTURE LEADS
TO PROGRESSIVE INSTABILITY AND DEFORMITY OF THE JOINTS.
 DEVELOPMENT OF DEFORMITY

• AS THE DISEASE PROGRESSES, THE PERSISTENT INFLAMMATION

CAUSES JOINT & TENDON DESTRUCTION.
• EROSION OF THE ARTICULAR CARTILAGE, TENOSYNOVITIS &
EVENTUALLY RUPTURE OF TENDON OCCURS.
• COMBINATION OF ARTICULAR DESTRUCTION, CAPSULAR STRETCHING
AND TENDON RUPTURE LEADS TO PROGRESSIVE INSTABILTY &
DEFORMITY OF JOINTS.
 DEFORMITIES OF HAND
• DEF. OF FINGERS
• DEF OF THUMB
• DEF. OF WRIST
• RUPTURE OF TENDONS
 DEFORMITY IN RA
• MCP & WRIST AFFECTED EARLY
• IP JTS ARE AFFECTED LATE, TYPICALLY.
• MCP- MOST IMPORTANT JT AFFECTING FUNCTION IN RA.
• ULNAR DEVIATION & VOLAR SUBLUXATION OF FINGERS ARE TYPICAL
DEFORMITIES.
 FINGER DEFORMITIES CAUSED BY
RHEUMATOID ARTHRITIS

• NORMAL FORCES APPLIED TO DAMAGED JOINTS BY THE EXTRINSIC

FLEXORS AND EXTENSORS
• TIGHTNESS OF THE INTRINSIC MUSCLES
• DISPLACEMENT OF THE LATERAL BANDS OF THE EXTENSOR HOOD
• RUPTURE OF THE CENTRAL SLIP OF THE HOOD
• RUPTURE OF THE LONG EXTENSOR OR LONG FLEXOR TENDONS.
 DEFORMITY OF FINGERS

1.INTRINSIC PLUS DEFORMITY

2.SWAN NECK DEFORMITY
3.BUTTON HOLE DEFORMITY
4.ULNAR DEVIATION
 INTRINSIC PLUS DEFORMITY
• CAUSED BY INTRINSIC MUSCLE TIGHTNESS
AND CONTRACTURE.
• DEFORMITY
• PIP JOINT : EXTENSION
• MCP JOINT : FLEXION
• THUMB : ADDUCTION

• VOLAR SUBLUXATION OF MCP JOINT &

ULNAR DEVIATION OF FINGERS
• BUNNELL TEST
 1.INTRINSIC PLUS DEFORMITY

• THE INTRINSIC PLUS DEFORMITY IS CAUSED BY TIGHTNESS AND

CONTRACTURE OF THE INTRINSIC MUSCLES.
• IN HANDS WITH INTRINSIC PLUS DEFORMITY, THE PROXIMAL
INTERPHALANGEAL JOINT CANNOT BE FLEXED WHILE THE
METACARPOPHALANGEAL JOINT IS FULLY EXTENDED.
• OFTEN, THE DEFORMITY DEVELOPS IN COMBINATION WITH VOLAR
SUBLUXATION OF THE METACARPOPHALANGEAL JOINTS AND
ULNAR DEVIATION OF THE FINGERS
 BUNNELL TEST FOR INTRINSIC TIGHTNESS

METACARPOPHALANGEAL JOINT IS PASSIVELY HELD IN EXTENSION, CAUSING

PASSIVE EXTENSION OF THE PROXIMAL INTERPHALANGEAL JOINT AND
PREVENTING PASSIVE FLEXION OF THE PROXIMAL INTERPHALANGEAL JOINT
(FIG. 70-11). WHEN THE METACARPOPHALANGEAL JOINT IS PASSIVELY FLEXED,
THE INTRINSICS ARE RELAXED, AND PASSIVE FLEXION OF THE PROXIMAL
INTERPHALANGEAL JOINT IS INCREASED. WITH ULNAR DRIFT OF THE FINGERS,
THIS INTRINSIC TIGHTNESS MAY BE PRESENT ONLY ON THE ULNAR SIDE.
• TO TEST THIS ACCURATELY, AXIAL ALIGNMENT OF THE FINGER
WITH THE METACARPAL SHOULD BE MAINTAINED IN CHECKING
INTRINSIC TIGHTNESS.
• ANY ULNAR DEVIATION AT THE METACARPOPHALANGEAL JOINT
DURING THE TEST SLACKENS THE INTRINSICS ON THE ULNAR SIDE
OF THE FINGER AND CONFUSES THE FINDINGS.
• A TIGHT FIRST VOLAR INTEROSSEOUS MUSCLE PULLS THE
EXTENDED INDEX FINGER ULNARWARD, BUT IF THE FINGER IS HELD
IN LINE WITH THE SECOND METACARPAL DURING THE TEST,
TIGHTNESS OF THIS MUSCLE CAN BE SHOWN.
• THE FIRST VOLAR INTEROSSEOUS IS A FLEXOR AND AN ADDUCTOR
OF THE SECOND METACARPOPHALANGEAL JOINT, AND USUALLY
THE FIRST DORSAL INTEROSSEOUS IS AN ABDUCTOR ONLY.
TEST FOR TIGHTNESS OF OBLIQUE RETINACULAR LIGAMENT. PROXIMAL INTERPHALANGEAL
JOINT HELD IN MAXIMAL EXTENSION BY EXAMINER. RESISTANCE TO PASSIVE FLEXION OF
DISTAL INTERPHALANGEAL JOINT IS EVALUATED
 SWAN NECK DEFORMITY
• DEFORMITY
• DIP JOINT : FLEXION
• PIP JOINT : HYPEREXTENSION
• MCP JOINT : FLEXION

• CAUSED BY MUSCLE IMBALANCE & MAY

BE PASSIVELY CORRECTABLE.
• ALSO SEEN IN
• VOLAR PLATE LAXITY
• EHLER DANLOS SYNDROME
• CAUSES:
• MALLET DEFORMITY ASSOCIATED WITH
EXTENSOR TENDON DISRUPTION AT THE DIP
• CAPSULAR DISRUPTION, TIGHTENING OF THE
LATERAL BANDS AND CENTRAL TENDON, AND
ADHERENCE OF THE LATERAL BANDS AT PIP
• FLEXOR TENOSYNOVITIS
 2.SWAN-NECK DEFORMITY

• SWAN-NECK DEFORMITY IS DESCRIBED AS A FLEXION POSTURE OF

THE DISTAL INTERPHALANGEAL JOINT AND HYPEREXTENSION
POSTURE OF THE PROXIMAL INTERPHALANGEAL JOINT, AT TIMES
WITH FLEXION OF THE METACARPOPHALANGEAL JOINT
• . IT IS CAUSED BY MUSCLE IMBALANCE AND MAY BE PASSIVELY
CORRECTABLE, DEPENDING ON THE FIXATION OF THE ORIGINAL AND
SECONDARY DEFORMITIES .
• ALTHOUGH USUALLY ASSOCIATED WITH RHEUMATOID ARTHRITIS,
SWAN-NECK DEFORMITY MAY OCCUR IN PATIENTS WITH LAX JOINTS
AND IN PATIENTS WITH CONDITIONS SUCH AS EHLERS-DANLOS
SYNDROME.
 SWAN-NECK DEFORMITY. A, TERMINAL TENDON RUPTURE MAY BE ASSOCIATED WITH SYNOVITIS OF DISTAL
INTERPHALANGEAL JOINT, LEADING TO DISTAL INTERPHALANGEAL JOINT FLEXION AND SUBSEQUENT PROXIMAL
INTERPHALANGEAL JOINT HYPEREXTENSION. RUPTURE OF FLEXOR DIGITORUM SUPERFICIALIS TENDON CAN BE CAUSED
BY INFILTRATIVE SYNOVITIS, WHICH CAN LEAD TO DECREASED VOLAR SUPPORT OF PROXIMAL INTERPHALANGEAL JOINT
AND SUBSEQUENT HYPEREXTENSION DEFORMITY. B, LATERAL-BAND SUBLUXATION DORSAL TO AXIS OF ROTATION OF
PROXIMAL INTERPHALANGEAL JOINT. CONTRACTION OF TRIANGULAR LIGAMENT AND ATTENUATION OF TRANSVERSE
RETINACULAR LIGAMENT ARE DEPICTED
FIXED RHEUMATOID SWAN-NECK DEFORMITY, WITH PROXIMAL INTERPHALANGEAL
JOINT HYPEREXTENSION AND DISTAL INTERPHALANGEAL JOINT FLEXION
• THIS DEFORMITY MAY BEGIN AS A MALLET DEFORMITY
ASSOCIATED WITH A DISRUPTION OF THE EXTENSOR TENDON AT
THE DISTAL JOINT WITH SECONDARY OVERPULL OF THE CENTRAL
TENDON, CAUSING HYPEREXTENSION OF THE LAX PROXIMAL
INTERPHALANGEAL JOINT. THE PROXIMAL INTERPHALANGEAL
JOINT MAY ACTIVELY FLEX NORMALLY.
• THIS DEFORMITY ALSO MAY BEGIN AT THE PROXIMAL
INTERPHALANGEAL JOINT BECAUSE SYNOVITIS CAUSES HERNIATION
OF THE CAPSULE, TIGHTENING OF THE LATERAL BANDS AND CENTRAL
TENDON, AND EVENTUAL ADHERENCE OF THE LATERAL BANDS IN A
FIXED DORSAL POSITION, SO THEY CAN NO LONGER SLIDE OVER THE
CONDYLES WHEN THE PROXIMAL INTERPHALANGEAL JOINT IS FLEXED
• THIS LIMITS PROXIMAL INTERPHALANGEAL FLEXION. THE
DORSALLY AND CENTRALLY DISPLACED LATERAL BANDS BECOME
RELATIVELY SLACK AND MAY BE INEFFECTIVE IN EXTENDING THE
DISTAL INTERPHALANGEAL JOINT, WHICH MAY SECONDARILY
ASSUME A MALLET DEFORMITY WITHOUT ACTUAL RUPTURE OF THE
CENTRAL TENDONS. THIS MALLET DEFORMITY USUALLY IS NOT AS
SEVERE, HOWEVER, AS THAT PRODUCED BY A RUPTURE OF THE
CENTRAL TENDONS.
•
• NALEBUFF, FELDON, AND MILLENDER CATEGORIZED SWAN-NECK
DEFORMITIES INTO FOUR TYPES AND RECOMMENDED
APPROPRIATE TREATMENT PLANS FOR EACH TYPE
• TYPE I DEFORMITIES ARE FLEXIBLE AND REQUIRE DERMODESIS,
FLEXOR TENODESIS OF THE PROXIMAL INTERPHALANGEAL JOINT,
FUSION OF THE DISTAL INTERPHALANGEAL JOINT, AND
RECONSTRUCTION OF THE RETINACULAR LIGAMENT.
• TYPE II DEFORMITIES ARE CAUSED BY INTRINSIC MUSCLE
TIGHTNESS AND REQUIRE INTRINSIC RELEASE IN ADDITION TO ONE
OR MORE OF THE AFOREMENTIONED PROCEDURES.
• TYPE III DEFORMITIES ARE STIFF AND DO NOT ALLOW SATISFACTORY
FLEXION, BUT DO NOT HAVE SIGNIFICANT JOINT DESTRUCTION
RADIOGRAPHICALLY. THESE DEFORMITIES REQUIRE JOINT
MANIPULATION, MOBILIZATION OF THE LATERAL BANDS, AND
DORSAL SKIN RELEASE.
• TYPE IV DEFORMITIES HAVE RADIOGRAPHIC EVIDENCE OF
DESTRUCTION OF THE JOINT SURFACE AND STIFF PROXIMAL
INTERPHALANGEAL JOINTS, WHICH USUALLY CAN BE BEST TREATED
WITH ARTHRODESIS OF THE PROXIMAL INTERPHALANGEAL JOINT OR,
IN THE RING AND SMALL FINGERS, WITH SWANSON IMPLANT
ARTHROPLASTY OF THE PROXIMAL INTERPHALANGEAL JOINT.
 BOUTONNIÈRE DEFORMITY
(BUTTON HOLE)
• DEFORMITY
• PIP JOINT : FLEXION
• DIP JOINT : HYPEREXTENSION
• MP JOINT : HYPEREXTENSION
 PATHO ANATOMY
• SYNOVITIS OF THE PIP JOINT WITH A STRETCHING OUT OF THE CENTRAL SLIP,
FORCING THE LATERAL BANDS TO BEGIN SUBLUXATE VOLARWARD
• SHORTENING OF THE OBLIQUE RETINACULAR LIGAMENTS RESULTS IN
HYPEREXTENSION AND LIMITED ACTIVE FLEXION OF THE DIP JOINT.
• THE FLEXION DEFORMITY OF THE PIP JOINT IS COMPENSATED BY EXTENSION OF
THE MCP JOINT.
• MCP JOINT DEFORMITY NOT FIXED AS THE DISTAL TWO JOINTS.
 NALEBUFF AND MILLENDER GRADING
Grade Deformity PIP joint DIP Joint Radiograph

Mild •Passively •Flexion •Decreased flexion Normal

correctable deformity(15)
(Lateral band
subluxated volarly
but not adherent)

Moderate •Not correctable •Flexor contracture •Hyperextension Joint space

passively (40) preserved
•Normal flexor
tendon function

Severe •Fixed flexion •Hyperextension Joint

deformity (90) destruction
•Ankylosis
 3.BUTTONHOLE, OR BOUTONNIÈRE,
DEFORMITY

• BUTTONHOLE DEFORMITY HAS A FLEXED PROXIMAL

INTERPHALANGEAL JOINT, WITH A HYPEREXTENDED DISTAL
INTERPHALANGEAL JOINT.
• IT IS COMMONLY SEEN IN PATIENTS WITH RHEUMATOID ARTHRITIS,
ALTHOUGH THIS TENDON IMBALANCE IS NOT UNIQUE TO
RHEUMATOID DISEASE. IN A PATIENT WITH RHEUMATOID ARTHRITIS, IT
IS THOUGHT TO BE CAUSED BY SYNOVITIS OF THE PROXIMAL
INTERPHALANGEAL JOINT WITH A STRETCHING OUT OF THE CENTRAL
SLIP, FORCING THE LATERAL BANDS TO BEGIN SUBLUXATING
VOLARWARD.
• AS THE DEFORMITY PROGRESSES, THE LATERAL BANDS ARE FORCED
FARTHER OVER THE CONDYLES OF THE PROXIMAL INTERPHALANGEAL
JOINT AND BECOME TIGHTENED BY THEIR NEW COURSE AND BY
PRESSURE FROM THE UNDERLYING SWOLLEN JOINT
• THEY FINALLY BECOME FIXED IN A SUBLUXATED POSITION VOLAR TO THE
TRANSVERSE AXIS OF THE JOINT AND ACT AS FLEXORS OF THE PROXIMAL
INTERPHALANGEAL JOINT. THIS TIGHTENING CAUSES A SECONDARY
HYPEREXTENSION DEFORMITY OF THE DISTAL INTERPHALANGEAL JOINT.
• THE FLEXION DEFORMITY OF THE PROXIMAL INTERPHALANGEAL JOINT IS
COMPENSATED FOR BY AN EXTENSION OF THE METACARPOPHALANGEAL
JOINT .
• . THE METACARPOPHALANGEAL JOINT DEFORMITY DOES NOT BECOME FIXED,
AS DO THE DISTAL TWO JOINTS.
 BOUTONNIÈRE DEFORMITY. A, PRIMARY SYNOVITIS OF PROXIMAL INTERPHALANGEAL (PIP)
JOINT CAN LEAD TO ATTENUATION OF OVERLYING CENTRAL SLIP AND DORSAL CAPSULE AND
INCREASED FLEXION AT PIP JOINT. LATERAL BAND SUBLUXATION VOLAR TO AXIS OF ROTATION
OF PIP JOINT CAN LEAD IN TIME TO HYPEREXTENSION. CONTRACTION OF OBLIQUE
RETINACULAR LIGAMENT, WHICH ORIGINATES FROM FLEXOR SHEATH AND INSERTS INTO
DORSAL BASE OF DISTAL PHALANX, CAN LEAD TO EXTENSION CONTRACTURE OF DISTAL
INTERPHALANGEAL JOINT. B, CLINICAL PHOTOGRAPH ILLUSTRATES FLEXION POSTURE OF PIP
JOINT AND HYPEREXTENSION POSTURE OF DISTAL INTERPHALANGEAL JOINT IN BOUTONNIÈRE
DEFORMITY.
 NALEBUFF AND MILLENDER CATEGORIZED BUTTONHOLE DEFORMITIES ON THE BASIS OF THE
RADIOGRAPHIC APPEARANCE OF THE JOINT SURFACE AND THE AMOUNT OF ACTIVE AND
PASSIVE MOTION

MILD BUTTONHOLE DEFORMITIES

• THERE IS A FLEXION DEFORMITY AT THE PROXIMAL INTERPHALANGEAL
JOINT WITH LESSENED ABILITY TO FLEX THE DISTAL JOINT FULLY, BUT THE
JOINT IS NOT FIXED IN HYPEREXTENSION.
• THE FLEXION DEFORMITY AT THE PROXIMAL INTERPHALANGEAL JOINT IS
PASSIVELY CORRECTABLE FROM A POSITION OF APPROXIMATELY 15
DEGREES OF FLEXION.
• IN THESE DEFORMITIES, TREATMENT MAY CONSIST OF RELEASING THE
LATERAL TENDONS NEAR THEIR INSERTION INTO THE DISTAL PHALANX
• MODERATE BUTTONHOLE DEFORMITY
• HAS AN APPROXIMATELY 40-DEGREE FLEXION CONTRACTURE OF
THE PROXIMAL INTERPHALANGEAL JOINT, MOST OF WHICH IS
PASSIVELY CORRECTABLE. THE DISTAL JOINT IS HYPEREXTENDED,
AND USUALLY THE METACARPOPHALANGEAL JOINT IS
CORRECTABLE TO FULL FLEXION PASSIVELY. THE LATERAL BANDS
ARE FIXED IN THEIR SUBLUXATED POSITION VOLARWARD BY
VIRTUE OF THE CONTRACTED TRANSVERSE RETINACULAR
LIGAMENT.
 DIP JOINT DEFORMITY
• MALLET, HYPERFLEXED DISTAL
INTERPHALANGEAL JOINT
• DUE TO THE RUPTURE OF EXTENSOR
SLIP
 DEFORMITIES OF THE DISTAL JOINT

• THE RHEUMATOID DEFORMITIES AT THE DISTAL JOINT INCLUDE A

MALLET, HYPERFLEXED DISTAL INTERPHALANGEAL JOINT (FIG. 70-
22), WHICH MAY OCCUR IN CONJUNCTION WITH A SWAN-NECK
DEFORMITY OR AS A RESULT OF ATTENUATION OF THE TERMINAL
CENTRAL SLIP OF THE EXTENSOR TENDON, AND A
HYPEREXTENSIBLE DISTAL INTERPHALANGEAL JOINT, WHICH ALSO
MAY BE RELATED TO ATTENUATION OF CAPSULOLIGAMENTOUS
STRUCTURES OR TO FLEXOR TENDON RUPTURE.
• USUALLY EITHER OF THESE DEFORMITIES CAN BE TREATED WITH
DISTAL INTERPHALANGEAL JOINT ARTHRODESIS. IN A PATIENT WHO
HAS HAD A PROXIMAL INTERPHALANGEAL JOINT ARTHRODESIS, THE
DISTAL INTERPHALANGEAL JOINT MALLET DEFORMITY MIGHT BE LEFT
UNTREATED BECAUSE THE SMALL AMOUNT OF MOBILITY REMAINING
IN THE DISTAL INTERPHALANGEAL JOINT CAN CONTRIBUTE
SIGNIFICANTLY TO FINGERTIP FUNCTION
 ULNAR DRIFT OF FINGERS

• DUE TO
1. METACARPOPHALANGEAL JOINT SYNOVITIS THAT WEAKENS THE
DORSORADIAL CAPSULAR RESTRAINTS
2. LOOSENING OF THE METACARPOPHALANGEAL JOINT COLLATERAL
LIGAMENTS RESULTS IN DECREASED STABILITY
3. STRETCHING OF THE FLEXOR TUNNELS THAT PERMITS EVEN MORE
ULNAR DISPLACEMENT OF THE LONG FLEXOR TENDON
4. INTEROSSEOUS MUSCLE CONTRACTURE THAT CAUSES ULNAR
DEVIATION AND PROXIMAL INTERPHALANGEAL JOINT
HYPEREXTENSION AS WELL AS METACARPOPHALANGEAL JOINT
FLEXION AND EVENTUALLY SUBLUXATION;
5. LONG EXTENSOR TENDON RUPTURE AT THE WRIST LEVEL THAT
INCREASES THE POSSIBILITY OF METACARPOPHALANGEAL JOINT
DISLOCATIONS.
 4.ULNAR DRIFT OR DEVIATION OF THE
FINGERS

• THE DEFORMITY OF ULNAR DRIFT OR DEVIATION OF THE FINGERS (FIG. 70-23) IS FOUND IN CONDITIONS OTHER THAN
RHEUMATOID ARTHRITIS.

• IN THE NORMAL HAND, FACTORS ARE

• (1) THE ULNAR DEVIATION OF THE PHALANGES AT THE METACARPOPHALANGEAL JOINTS, ESPECIALLY OF THE INDEX
FINGER;

• (2) THE SMALL AND SLOPING ULNAR CONDYLE OF ASYMMETRICAL METACARPAL HEADS, ESPECIALLY THOSE OF THE
INDEX AND MIDDLE FINGERS;

• (3) THE APPROACH FROM THE ULNAR DIRECTION OF THE LONG FLEXOR AND EXTENSOR TENDONS TO THE
METACARPOPHALANGEAL JOINTS;

• (4) THE GREATER ULNAR DEVIATION THAN RADIAL DEVIATION OF THE DIGITS PERMITTED BY THE RADIAL COLLATERAL
LIGAMENTS WHEN THE METACARPOPHALANGEAL JOINTS ARE FLEXED; AND

• (5) THE GREATER STRENGTH OF THE ABDUCTOR DIGITI QUINTI AND FLEXOR DIGITI QUINTI THAN OF THE THIRD VOLAR
INTEROSSEOUS
• FACTORS FOUND IN THE RHEUMATOID HAND ARE
• (1) STRETCHING OF THE COLLATERAL LIGAMENTS OF THE METACARPOPHALANGEAL JOINTS BY
THE VOLARLY DIRECTED FORCES OF THE FLEXOR TENDONS, PERMITTING VOLAR DISPLACEMENT
OF THE PROXIMAL PHALANGES;
• (2) STRETCHING OF THE ACCESSORY COLLATERAL LIGAMENTS THAT PERMITS ULNAR
DISPLACEMENT OF THE FLEXOR TENDONS WITHIN THEIR TUNNELS;
• (3) STRETCHING OF THE FLEXOR TUNNELS THAT PERMITS EVEN MORE ULNAR DISPLACEMENT OF
THE LONG FLEXOR TENDONS;
• (4) ULNAR DISPLACEMENT OF THE LONG FLEXOR TENDONS CAUSED BY SURGICAL RELEASE OF
THEIR SHEATHS FOR MULTIPLE TRIGGER FINGERS OR FOR IMPROVING STRENGTH OF GRASP BY
CHANGING THEIR ANGLE OF APPROACH TO THE FINGERS;
• 5) CONTRACTURE OF THE INTEROSSEOUS MUSCLES THAT CAUSES (IN ADDITION TO
ULNAR DEVIATION OF THE DIGITS) HYPEREXTENSION OF THE PROXIMAL
INTERPHALANGEAL JOINTS, FLEXION, AND EVENTUALLY SUBLUXATION OF THE
METACARPOPHALANGEAL JOINTS AND EVENTUALLY SUBLUXATION OF THESE
LATTER JOINTS;
• (6) ATTENUATED RADIAL SAGITTAL BANDS THAT ALLOW ULNAR DISPLACEMENT OF
THE LONG EXTENSOR TENDONS, FURTHER INCREASING THEIR DEFORMING
INFLUENCE (THIS DISPLACEMENT IS CAUSED BY INEFFECTIVE RADIAL SAGITTAL
BANDS);
• (7) RUPTURE OF LONG EXTENSOR TENDONS AT THE DISTAL EDGE OF THE DORSAL
CARPAL LIGAMENT THAT INCREASES THE POSSIBILITY OF DISLOCATION OF THE
METACARPOPHALANGEAL JOINTS.
ULNAR DEVIATION OF FINGERS IN
RHUEMATOID ARTHRITIS
 SUBLUXATION OF METACARPOPHALANGEAL JOINTS OF FINGERS IN SEVERE
RHEUMATOID ARTHRITIS. B, SUBLUXATIONS HAVE BEEN TREATED BY RESECTING
METACARPAL HEADS. BECAUSE AT SURGERY ARTICULAR CARTILAGE OF JOINTS WAS
ERODED, INTRINSIC RELEASE WOULD HAVE BEEN INSUFFICIENT TREATMENT
 SEVERE ULNAR DRIFT AND
METACARPOPHALANGEAL DISLOCATION

• IN SEVERE ULNAR DRIFT, OFTEN ONE OR MORE

METACARPOPHALANGEAL JOINTS HAVE DISLOCATED (FIG. 70-27);
CONSEQUENTLY, THIS TYPE OF DRIFT AND DISLOCATION OF THESE
JOINTS ARE DISCUSSED TOGETHER.
• HERE THE DISLOCATION OF THE METACARPOPHALANGEAL JOINT
IN EFFECT HAS RELEASED THE SOFT-TISSUE STRUCTURES THAT
CROSS THE JOINT AND BY DECREASING TENSION HAS PROTECTED,
AT LEAST PARTIALLY, THE PROXIMAL INTERPHALANGEAL JOINT
• .
• . CONVERSELY, IF THE PROXIMAL INTERPHALANGEAL JOINT
DISLOCATES FIRST, THE METACARPOPHALANGEAL JOINT IS PARTIALLY
PROTECTED. BECAUSE OF THE DEFORMING FORCES MENTIONED
EARLIER IN THIS SECTION, THE METACARPOPHALANGEAL JOINTS
WOULD HAVE DEVIATED ULNARWARD MORE AND MORE
• FOR THIS TYPE OF ULNAR DRIFT, SURGERY IS DONE MAINLY ON THE
METACARPAL HEAD AND ITS SURROUNDING LIGAMENTS AND
TENDONS
METACARPOPHALANGEAL DISLOCATION IN
RHEUMATOID ARTHRITIS
 ULNAR DRIFT - GRADES

• MILD TO MODERATE ULNAR DRIFT

• ABSENCE OF SEVERELY DISEASED ARTICULAR SURFACES OR DISLOCATED
JOINTS

• SEVERE ULNAR DRIFT

• ONE OR MORE METACARPOPHALANGEAL JOINTS HAVE DISLOCATED &
SEVERELY DISEASED ARTICULAR SURFACE.
THUMB DEFORMITY - NALEBUFF
CLASSIFICATION
 BOUTONNIERE DEFORMITY
• SYNOVITIS BEGINNING IN THE
METACARPOPHALANGEAL JOINT
FREQUENTLY LEADS TO A
BOUTONNIÈRE DEFORMITY OF THE
THUMB.
• PROXIMAL PHALANX : SUBLUXATION
• METACARPOPHALANGEAL JOINT :
FLEXION
• INTERPHALANGEAL JOINT :
HYPEREXTENSION
 SWAN NECK DEFORMITY
• SYNOVITIS BEGINS IN THE
CARPOMETACARPAL JOINT
• DEFORMITY:
• DORSAL SUBLUXATION OF THE
METACARPAL BASE
• HYPEREXTENSION OF THE
METACARPOPHALANGEAL JOINT
(SWAN-NECK DEFORMITY).
 GAME KEEPER’S THUMB
• SYNOVITIC DESTRUCTION OF THE
CAPSULOLIGAMENTOUS SUPPORTS ON
THE ULNAR SIDE OF THE
METACARPOPHALANGEAL JOINT
• DUE TO LAXITY OF THE ULNAR COLLATERAL
LIGAMENT OF THE
METACARPOPHALANGEAL JOINT
 OPERA GLASS HAND
•
(LA MAIN
ARTHRITIS MUTILANS OF HAND
EN LORGNETTE)
• SHORTENING OF FINGERS DUE TO
DESTRUCTION OF PHALANGES.
• EXCESS SKIN GETS FOLDED
TRANSVERSELY RESEMBLING ‘OPERA
GLASS’
 WRIST DEFORMITY

• RHEUMATOID SYNOVITIS IN WRIST AFFECTS

• ULNAR STYLOID
• ULNAR HEAD
• MID PORTION OF SCAPHOID
• SYNOVITIS STRETCHES ULNAR CARPAL LIGAMENTOUS COMPLEX &
CAUSES ‘CAPUT ULNA SYNDROME’
• DORSAL PROMINENCE OF DISTAL ULNA
• SUPINATION OF CARPUS
• VOLAR SUBLUXATION OF ECU
• RADIAL DEVIATION OF WRIST
• SYNOVITIS BEGINS IN THE REGION OF DEEP VOLAR RADIOCARPAL LIGAMENT &
INTERCARPAL LIGAMENT WHICH RESULTS IN VOLAR SUBLUXATION OF SCAPHOID.

• COMBINATION OF
• ROTATORY SUBLUXATION OF THE SCAPHOID
• VOLAR SUBLUXATION OF THE ULNAR CARPUS
• DORSAL SUBLUXATION OF THE DISTAL ULNA

relative supination of
the wrist
• WRIST COLLAPSE LEADS TO
• IMBALANCE OF THE EXTENSOR TENDONS
• RADIAL SHIFT OF THE METACARPALS
• ULNAR DEVIATION OF THE FINGERS

• UNTREATED, END-STAGE RHEUMATOID WRIST

IS
• DISLOCATED VOLARWARD
• COMPLETE DESTRUCTION OF THE CARPAL
BONES
• COMPLETE DISSOCIATION OF THE
RADIOULNAR JOINT.
 TENOSYNOVITIS
• RHEUMATOID ARTHRITIS IS A DISEASE OF THE SYNOVIUM.
• TENDON SHEATH INVOLVEMENT IS COMMON AND MAY OCCUR MONTHS
BEFORE THE SYMPTOMS OF INTRA-ARTICULAR DISEASE ARE NOTED.
• COMMON SITES
• DORSAL ASPECT OF WRIST
• VOLAR ASPECT OF WRIST
• VOLAR ASPECT OF DIGITS
• PRESENTATION :
• PAIN
• TENDON DYSFUNCTION
• TENDON RUPTURE
 EXTENSOR TENOSYNOVITIS
• WRIST & DIGITAL EXTENSOR TENOSYNOVITIS
CAUSES PAINLESS SWELLING.

• IF PAINFUL LOOK FOR INVOLVEMENT OF

RADIOULNAR & RADIOCARPAL JOINT.

• MAY BE THE FIRST SIGN OF RA

• D/D : GANGLION CYST, DORSAL CAPSULAR
SYNOVITIS

• EXTENSOR NODULE MAY IMPINGE ON DISTAL

EXTENSOR RETINACULUM CAUSING
DISCOMFORT IN WRIST & FINGER EXTENSION.
 EXTENSOR TENDON RUPTURE
• EVENTUALLY TENOSYNOVITIS LEADS TO TENDON RUPTURE
• MAJOR CAUSE OF DEFORMITY AND DISABILITY.
• CAUSES
• ATTRITION RUPTURE
• INFILTRATION OF SYNOVIUM
• ISCHEMIC RUPTURE

• ATTRITION RUPTURE OCCURS AT

• DISTAL END OF THE ULNA
• LISTER’S TUBERCLE (PULLEY FOR EPL GLIDING)
• THE SMALL FINGER USUALLY IS INVOLVED FIRST AND SUBSEQUENTLY
THE RING (VAUGHN-JACKSON SYNDROME) AND THEN SEQUENTIALLY
MORE RADIAL DIGITAL EXTENSORS.

• THE LONG EXTENSOR TENDON OF THE THUMB, BECAUSE OF ITS

TORTUOUS COURSE, FREQUENTLY RUPTURES AT THE LISTER TUBERCLE,
WHERE IT ANGLES THROUGH AN ENCLOSED TUNNEL OR PULLEY.
 FLEXOR TENOSYNOVITIS
• VOLAR SURFACE OF THE WRIST AND
FINGERS.
• FUSIFORM SWELLING OF ONE OR MORE
FLEXOR TENDON SHEATHS EXTENDING
FROM THE MIDDLE OF THE PALM TO THE
DISTAL INTERPHALANGEAL JOINT.
• THE SWELLING IS TYPICALLY PAINFUL AND
CAUSES A GRADUAL DECREASE IN FINGER
FLEXION.
• SYNOVIUM IS THICKENED AND NODULES
CAN BE FELT ALONG THE TENDON SHEATH
WITH TENDON EXCURSION; CREPITUS AND
GRATING USUALLY ARE PRESENT.
 FLEXOR TENOSYNOVITIS
• PRESENTATION
• INTERFERES WITH FINGER MOTION
• COMPRESSES THE MEDIAN NERVE IN THE CARPAL TUNNEL
• TRIGGER FINGER
• TENDON RUPTURE.
• EROSION OF THE VOLAR CAPSULE AND LIGAMENTS OVER RADIAL
OSTEOPHYTES CONTRIBUTE TO FLEXOR POLLICIS LONGUS RUPTURE IN
THE CARPAL TUNNEL (MANNERFELT LESION).
 FLEXOR TENDON RUPTURE
• NOT AS COMMON AS EXTENSOR TENDON RUPTURE BUT IS MUCH MORE
DIFFICULT TO TREAT SURGICALLY.
• SITES:
• DIGIT (INFILTRATIVE TENOSYNOVITIS)
• WRIST (FPL TENDON : MOST COMMON TENDON TO RUPTURE)

• INFILTRATION, WEAKENING, AND EVENTUAL RUPTURE OF THE PROFUNDUS

TENDONS MAY LIKEWISE OCCUR AND ARE MORE OBVIOUS AND
DISABLING CLINICALLY.