597237

research-article2015
JOR0010.1177/2055116915597237Journal of Feline Medicine and Surgery Open ReportsCabon et al

Case Series
Journal of Feline Medicine and Surgery

Digital flexor tendon contracture Open Reports

1­–7
© The Author(s) 2015
treated by tenectomy: different Reprints and permissions:
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clinical presentations in three cats DOI: 10.1177/2055116915597237

jfmsopenreports.com

Quentin Cabon2, Jérôme Plante1 and Matthieu Gatineau1

Abstract
Case series summary Three cats, Siamese or Siamese cross, were presented with a chronic thoracic limb weightbearing
lameness. Previous anti-inflammatory administrations were unable to improve lameness consistently in the three
cats. Two of the three cats had undergone onychectomy several years before presentation. A permanent flexion
of the proximal interphalangeal joint of one or more digits, associated with a difficult and painful extension of the
proximal interphalangeal joint, was noticed during orthopedic examination. A digital flexor tendon contracture was
suspected and confirmed with radiographic examination. Surgical exploration was then performed. For all cats,
treatment consisted of a tenectomy or tenotomy of the superficial and deep digital flexor tendons in order to release
the contracture. The three cats responded well to the surgical treatment and became sound around 2–4 weeks after
surgery.
Relevance and novel information Digital flexor tendon contracture is rarely reported as a cause of lameness in cats.
It should be considered in a differential diagnosis of feline lameness whenever onychectomy has been performed in
the past. The precise etiology that explains this tendon contracture is unknown, but trauma or breed predisposition
could represent potential causes.

Accepted: 17 April 2015

Introduction consequences on the range of motion of adjacent

Digit pathologies are quite common in dogs and cats. joints.4 Most contractures are associated with a previ-
Digit lesions are most often associated with fractures, ous trauma, weeks to months before the contracture
luxations, wounds, shearing injuries or tumors, and, occurs, but repetitive strains, infectious diseases,
less commonly, osteomyelitis or osteoarthritis.1 Various ischemia, compartment syndrome or neoplasia may
surgical interventions are feasible, and digit amputa- also lead to contracture.4 This case series reports three
tion or luxation reduction is the most frequently different clinical presentations of digital flexor tendon
performed treatment.1 Feline onychectomy is also a contracture in three cats, all successfully treated by
common surgery in North America, despite debate tenectomy.
over the ethics of this procedure. Complications after
digit surgery or onychectomy are quite common. 2 Case 1
Flexor tendon contracture has been described as a A 4-year-old neutered male Siamese cat weighing 4.8 kg
chronic complication of this procedure.3 Feline digital was presented to a referral hospital for chronic left
flexor tendon pathology, especially tendon contrac- forelimb weight-bearing lameness of 1 year’s duration.
ture, is not well described. To our knowledge, only one
report in the veterinary literature describes this type of 1DMV Veterinary Centre, Montréal (Lachine), Québec, Canada
pathology.3 The term contracture refers to an abnormal 2SurgeryDepartment, VetAgroSup, Veterinary Campus of Lyon,
pathologic process resulting in fibrosis and permanent Marcy l’Etoile, France
damage to a muscle, characterized by replacement of
Corresponding author:
the muscle and/or associated tendon with fibrous con- Jérôme Planté PhD, DES, Dipl ECVS, DMV Veterinary Centre,
nective tissue.4 This phenomenon leads to shortening 2300 54th Avenue, Montréal, Québec, Canada
of the tendon or the muscle, and can have functional Email: jplante@centredmv.com

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2 Journal of Feline Medicine and Surgery Open Reports 

carpal pad to the proximal aspect of the metacarpal pad.

Following blunt dissection, the deep and superficial dig-
ital flexor muscle tendons were visualized and elevated,
and a portion of the tendons (5 mm) were transected
with a #15 scalpel blade (Figure 1). The surgical wound
was copiously lavaged with 0.9% sodium chloride (0.9%
Sodium Chloride Irrigation; Baxter). The subcutaneous
tissues were closed with a continuous pattern, using
a 4-0 absorbable monofilament (Poliglecaprone 25,
Monocryl; Ethicon). The skin was closed with an inter-
rupted pattern, using a 4-0 non-absorbable monofila-
ment (Polyamide 6, Ethilon II; Ethicon). The recovery and
postoperative periods were uneventful. The patient was
discharged from the hospital the day after the surgery
Figure 1  Intraoperative plantar visualization of the flexor with strict rest instructions for 3 weeks and meloxicam
tendons of the third digit before tenectomy (black arrow), (0.05 mg/kg q24 h PO) for 2 weeks.
exposed with a periosteal elevator (*). Left is distal, right is Two weeks after surgery, the owner mentioned that the
proximal, up is medial, down is lateral)
cat was very active, walking normally at home and was
more playful than before surgery. Upon follow-up exami-
The cat showed mild and transient lameness improve- nation no lameness was observed, and manipulation of
ment with meloxicam (0.05 mg/kg PO q24h Metacam; the left proximal interphalangeal joint of the second digit
Boehringer Ingelheim), but long-term medication did was normal and pain free. Two years after surgery the
not show any additional benefits. The cat had undergone owner reported that the cat was totally sound, very active
onychectomy 3.5 years before presentation. Upon exami- and had returned to its usual activity level.
nation, the cat showed very mild lameness, with the left
forelimb constantly non-weight bearing at rest. A perma-
nent flexion of the proximal interphalangeal joint of the Case 2
left forelimb second digit was noted. Asymmetry of the A 7-month-old neutered female Siamese weighing 3 kg
proximal interphalangeal joint was obvious when com- was presented for a lameness of the left forelimb of
pared with the contralateral limb. Extension of the proxi- 2 months’ duration. The owner reported that the lame-
mal interphalangeal joint was possible but very difficult ness was most likely due to a trauma that occurred
and palpation of this digit was significantly painful. The 2 months previously and was permanent since the incident.
rest of the physical and orthopedic examination was The cat received two different unknown non-steroidal
uneventful. anti-inflammatories before presentation at our hospital
Six months after initial presentation, the cat was pre- and did not show any improvement. The cat had not
sented for follow-up, without improvement. Radio- undergone onychectomy. Upon examination, the lame-
graphic views of the left forelimb extremity revealed an ness was moderate at a walk and severe and non-weight
abnormal positioning of the middle phalanx. Indeed, the bearing when the cat was running. At rest, a non-weight
angulation between the middle and proximal phalanges bearing stance was also obvious on the left forelimb. A
was decreased and reached almost 90º between these permanent flexion of the proximal interphalangeal joint
two phalanges on the second digit. There was no was noted on the fourth digit of the left forelimb.
evidence of retention of remnants, osteomyelitis or Asymmetry of the proximal interphalangeal joint was
hyperostosis of the distal phalanx. After discussion obvious when compared with the contralateral limb.
with the owner, exploratory surgery was scheduled. Extension of the proximal interphalangeal joint was pos-
Following premedication with hydromorphone (0.1 sible but very difficult. Palpation of this digit also induced
mg/kg IV Hydromorphone; Summit) and acepromazine some discomfort.
(0.02 mg/kg IV Atravent; Boehringer Ingelheim), gen- Five months after initial presentation, the cat was
eral anesthesia was induced with propofol (4 mg/kg IV presented for the same condition, without any improve-
Diprivan; AstraZeneca) and maintained with 2% isoflu- ment regarding lameness or comfort upon palpation.
rane (Forane; Baxter) in 100% oxygen after orotracheal Radiographic views of the left forelimb extremity
intubation. The cat was placed in dorsal recumbency, revealed an abnormal positioning of the middle phalanx
and the palmar surface from mid-radius to the extremity compared with the proximal phalanx, characterized by a
of the limb was clipped and aseptically prepared. decreased angulation between these two phalanges on
Surgery involved a palmar approach to the proximal the fourth digit. All three phalanges were observed in this
interphalangeal joint of the second digit, with a midline cat, without bony or articular lesions. After discussion
skin incision extending from the distal aspect of the with the owner, an exploratory surgery was scheduled.
Cabon et al 3

Figure 2  Preoperative aspect of the distal extremity of the

thoracic limb in case 3. Flexor contracture of all digits can be
visualized (left is distal, right is proximal, up is dorsal, down is
plantar)

Following premedication with butorphanol (0.1 mg/

kg IV Torbugesic; Pfizer), general anesthesia was induced
with propofol (4 mg/kg IV) and maintained with 2% iso-
flurane in 100% oxygen after orotracheal intubation. A
tenectomy of the deep and superficial digital flexor mus-
cle tendons was performed as previously described for Figure 3  Forelimb oblique extremity radiographic view of
the left limb in case 3. An abnormal positioning between
the first case. The surgical preparation and operative
the middle and the proximal phalanx is observed in the
technique were similar to those used in case 1, except that four digits. The angulation between these two phalanges is
the surgical site was the tendons of the fourth digit. The decreased and reached almost 90º in all digits
cat was discharged from the hospital the day after sur-
gery with strict rest instructions for 3 weeks and meloxi- painful callus was palpable at the craniodistal aspect,
cam (0.05 mg/kg q24h orally) for 2 weeks. bilaterally, of the third and fourth digital pads.
At the 2 week re-evaluation, the cat still presented a Radiographic views of the forelimb extremity revealed
mild lameness of the left thoracic limb, although the an abnormal positioning on both limbs between the mid-
extension of the proximal interphalangeal joint of the dle and the proximal phalanx. Indeed, the angulation
fourth digit was improved compared with preoperative between these two phalanges was decreased and reached
examination. However, a mild stiffness of this joint was almost 90º in all digits. No bony or articular lesion or
still present. One month after surgery, the cat was totally osteomyelitis of the proximal and middle phalanges was
sound and manipulation of the digit was not painful. At observed. Remnants of the distal phalanx were not
a 1.5 year postoperative follow-up, the owner reported observed in the radiographs (Figure 3). A digital flexor
that the cat was not limping anymore, was pain free and tendon contracture of both forelimb digits was then sus-
had returned to its normal activity. pected, and, after discussion, the owner agreed to surgi-
cal treatment.
Case 3 Following premedication with hydromorphone (0.1
A 7-year-old neutered male Siamese cross weighing 6 kg mg/kg IV), general anesthesia was induced with alfax-
presented with right forelimb lameness, which had alone (2 mg/kg IV Alfaxan; Abbott Laboratories) and
appeared a month earlier. The owner also reported that maintained with 2% isoflurane in 100% oxygen after oro-
the cat had undergone onychectomy at 6 months of age. tracheal tube placement. A local regional anesthetic bloc
The cat received a non-steroidal anti-inflammatory treat- was performed bilaterally with bupivacaine (0.5 mg/kg
ment (0.05 mg/kg q24h PO meloxicam) for 2 weeks SC Marcaïne 0.5%; Hospira Healthcare Corporation).
before presentation and did not show any improvement The surgical preparation was similar to that used in case
in lameness. Upon examination, the cat’s right forelimb 1. The surgical procedure was performed as described in
was non-weight bearing at rest, and the cat was uncom- case 1 for digits III and IV of both forelimbs, and a
fortable while walking on both forelimbs. A permanent tenotomy was performed on digits II and V on both
flexion of the proximal interphalangeal joint was noted forelimbs (Figure 4). Some parts of the digital flexor
in all four digits of both forelimbs (Figure 2). Digit exten- tendons were submitted for histopathology. The cat
sion was still possible but was painful bilaterally for dig- was discharged from the hospital the day after the sur-
its III and IV. Moreover, a 3 mm diameter white firm and gery with strict rest instructions for 3 weeks, meloxicam
4 Journal of Feline Medicine and Surgery Open Reports 

Figure 4  Perioperative dorsal view of an operated limb (OL)

and a preoperative limb (PL) in case 3. Flexor contracture is
well visualized in PL compared with OL
OL = on the left; PL = on the right

Figure 5  Thoracic limbs of case 3, 4 weeks after flexor

(0.05 mg/kg q24h PO) for 6 days and buprenorphine
tendon tenectomy and tenotomy
(20 µg/kg q8h sublingually buprenorphine; Chiron
Compounding Pharmacy) for 7 days.
At the 2 week follow-up, the cat was totally sound
and manipulation of the forelimb digits was very
comfortable. At rest, digits were in hyperextension
(Figure 5). Histopathologic examination of some parts
of the flexor tendons revealed dense and thick colla-
gen bundles associated with a few non-reactive small
fibroblasts. Superficial, loosely arranged, fibrovascular
tissue was noted. These observations were considered
to be consistent with a chronic degeneration or trauma
of this tendon. A definitive diagnosis of flexor tendon
contracture was made (Figure 6).

Discussion
The three cats reported in this study presented with
chronic mild forelimb lameness associated with reduc-
tion of the normal extension of the proximal interphalan- Figure 6  Photomicrograph of a tendon section from
geal joint of one or more digits. A contracture of the a domestic cat. Note the presence of increased well-
digital flexor tendon was suspected and confirmed by differentiated fibroblasts (large arrows) in the tendon
histopathologic analysis in one case. This case series is of accompanied by few small-caliber blood vessels (arrowhead)
particular interest because it describes three different and thin collagen fibers (thin arrows). These changes
presentations of digital flexor tendon contracture in cats. have been interpreted as reactive fibroplasia. Stained with
hematoxylin and eosin (× 200, 5 μm section)
In case 1, which involved an onychectomized cat, tendon
contracture involved only one digit, which is different
from the two cases reported by Cooper et al.3 In case 2, contracture has not been previously reported. Tenectomy
the cat developed a tendon contracture on a digit, of the affected digits was performed in all cats. We
although it had not undergone onychectomy. Case 3 is elected to perform only tenotomy on digits II and V in
more comparable to the cases reported by Cooper et al case 3 because of a satisfactory intraoperative contrac-
because this case involved tendon contracture of all dig- ture release after tenotomy. However, although we
its in both forelimbs after onychectomy.3 However, such thought that tenectomy was not mandatory to relieve
an important delay, as seen in this case, between onych- contracture in theses digits, it could have been a valuable
ectomy and the development of digital flexor tendon option for treatment of contracture. The surgical outcome
Cabon et al 5

tendon damage that led to a chronic problem. Two cats

presented for bilateral and painful flexor tendon con-
tracture following onychectomy have been previously
reported.3 Both cats underwent onychectomy 6 weeks
and 3 months before presentation, respectively, and had
all digits of both front paws fixed in flexion.3 Tenectomy
of each deep digital flexor tendon successfully resolved
the condition, and the cats were sound 2 months after
surgery.3
The authors hypothesized that the postoperative
contracture was the result of inflammation due to a sub-
optimal surgical technique (excessive or rough tissue
Figure 7  Distal aspect of flexor tendon anatomy on a third
thoracic digit (distal digital annular ligament has been
manipulation, use of a dull scalpel blade, improper use
removed). *Deep flexor tendon; P1 = proximal phalanx; of tissue adhesives or poor aseptic technique).3 These
P2 = middle phalanx; P3 = distal phalanx; (+) = superficial factors could elicit an abnormal inflammatory response
flexor tendon and result in flexor fibrosis, adhesion formation and evo-
lution toward flexor tendon contracture.3 Tobias et  al
was excellent in all cats, as in the two cases reported else- reported that the duration of the surgery, which was
where.3 Flexor contracture can be painful and disabling potentially secondary to a suboptimal surgical tech-
and can induce abnormal contact on normally non-contact nique, was correlated with the occurrence of postopera-
areas of the digits. A phalangeal mechanical dysfunction tive lameness.2 This association could also be observed
can also be a cause of the lameness. Contracture release with persistent long-term lameness but the number of
by tenectomy or tenotomy seemed to improve the lame- cases observed was considered too low to determine
ness quickly, while long-term anti-inflammatory treat- such an association.2
ments failed in each of the cases reported here. The anatomic relation between the deep digital flexor
The deep and superficial digital flexor tendons pro- tendon and the middle phalanx could explain the long-
vide digital flexion through contraction of the muscle term contracture. Indeed, traumatic resection of the dis-
bellies.3 More precisely, the proximal interphalangeal tal phalanx could be the cause of an inflammatory
joint is flexed by the action of the superficial digital reaction in the area of the distal extremity of the middle
flexor and the distal interphalangeal joint is flexed by the phalanx and the deep digital flexor tendon. Fibrosis
deep digital flexor.3 The superficial digital flexor (flexor between these two anatomic parts could create clinical,
digitorum superficialis) tendon runs on the palmar sur- permanent digit flexion.
face of the deep digital flexor tendon (flexor digitorum In addition to contracture of the digital flexor, other
profondus). It splits distally into four parts, which complications have been associated in 0–40% of cases of
diverge to the second to fifth metacarpophalangeal onychectomy in cats, such as pain, hemorrhage, lameness,
joints, with the corresponding terminal tendons of the swelling, non-weightbearing, infection, claw regrowth,
deep flexor tendon.5 Each superficial digital flexor ends middle phalanx protrusion and palmigrade stance.2,6
on the proximal aspect of the palmar surface of the mid- Lameness is usually an early postoperative complication
dle phalanx after being perforated by its respective deep and is associated with pain, which resolves in 2 days but
flexor tendon, which ends on the tuberosity of the distal can persist for up to 2 months.2 However, some undiag-
phalanges of digits II–V (Figure 7).5 Those superficial nosed postoperative contracture could possibly explain
and deep tendons are bridged by three transverse liga- long-term lameness. Cases 1 and 3 underwent onychec-
ments, at the metacarpophalangeal joints and at the tomy 3.5 and 6.5 years before presentation, respectively.
proximal and middle phalangeal joints, on each of the The postoperative flexor contracture was previously
four main digits.5 In two of the cases reported here, ten- reported in the first months after onychectomy but long-
don contracture was only found on one digit. Therefore, term postoperative contracture after onychectomy could
the cause of the contracture must have been distal to the explain undiagnosed chronic pain in some cats and
common tendon. With the third cat, the contracture particularly in cats 1 and 3.3 Thus, digital flexor tendon
could have been located more proximally than the ten- contracture cannot be ruled out because of an increased
don division, but multiple contractures of the distal por- delay from the onychectomy. A trauma was suspected
tion of each superficial digital flexor tendon were for the second cat, as no previous onychectomy was
confirmed by histopathologic analysis. performed on this patient.
A precise etiology is unknown in these cats. However, Digital flexor tendon injuries in dogs and cats are
a traumatic episode was reported by the owner of case 2, uncommon and most often result from laceration by
and this could have been the initial cause of the flexor sharp or penetrating foreign objects.1 These types of
6 Journal of Feline Medicine and Surgery Open Reports 

lesion require wound management and accurate ten- the metacarpophalangeal transverse ligament, with or
don surgical repair. Other conditions of digital flexor without resection of the superficial flexor tendon, and
tendons are rare, and only a few cases have been is highly effective with low associated complication and
reported. A report of a 10-month-old male Great Dane recurrence rates.11,14
affected by an excessive non-painful flexion of the dig-
its of the rightforelimb (more pronounced on the fourth Conclusions
digit) has been published.7 This dog was lame for Digital flexor contracture can affect an isolated digit or
2 months. Restricted extension of the fourth digit was all digits of a limb and is characterized by a chronic
confirmed under general anesthesia, and a modified lameness and a painful permanent flexion of the affected
Z-tenotomy was performed. Surgery provided a very digit. In contrast to medical management, tenectomy of
good outcome, as postoperative extension of the the deep and superficial flexor tendons is associated
affected digit was possible and pain free, and no lame- with a good-to-excellent surgical outcome for this condi-
ness was noted 7 months after surgery.7 A 5-month-old tion. Etiology of this contracture is unknown but trauma,
Basset Hound was also reported with simple incom- whether related to an onychectomy or not, seems to
plete syndactyly (fusion of the third and fourth digital predispose a cat to this condition. This pathology could
pads on a hindlimb) and secondary contracture of the therefore be considered as a long-term complication
deep digital flexor tendon of the third and fourth digit.8 of onychectomy in some cases. However, further cases
With this dog, the deep digital flexor tendon contrac- need to be reported to better understand the pathogene-
ture was suspected to be secondary to the primary con- sis of this condition. Digit evaluation seems to be of par-
genital anomaly and was treated by palmar tenotomy. amount importance when investigating cases of chronic
The surgical outcome was good, with no lameness 8 lameness in cats.
months postoperatively.
The first two cats reported here were middle-aged Funding  The authors received no specific grant from any
indoor Siamese cats, and the third case was a Siamese funding agency in the public, commercial or not-for-profit sec-
cross. Siamese cats are under-represented in our hospi- tors for the preparation of this case report.
tal population. They are known to be predisposed to
many diseases, including cardiovascular, dermatologic, Conflict of interest  The authors do not have any potential
endocrine, gastrointestinal, hematologic, infectious conflicts of interest to declare.
and musculoskeletal conditions, such as congenital
myasthenia gravis, mucopolysaccharidosis VI or hip References
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