Conversion Total Hip Replacement

Orthopedic Technologies &Techniques

After Malunited Intertrochanteric

Fracture: A Technical Note
Aasis Unnanuntana, MD, and Stuart B. Goodman, MD, PhD

Abstract Surgical Technique

Malunited intertrochanteric fracture involves ana- Surgical approaches for conversion THR from failed
tomical changes such as medialization of the sliding hip screw fixation are similar to those for prima-
femoral canal and intramedullary remodeling ry THR. We prefer to use the direct lateral approach with
and sclerosis. These changes introduce difficul-
a “wafer-thin” modified anterior trochanteric osteotomy
ties that are not ordinarily encountered with rou-
tine total hip replacement. Possible intraopera-
and dislocate the hip anteriorly. However, a trochanteric
tive complications include spiral femoral fracture slide with a larger bony fragment is strongly considered
during hip dislocation and failure to identify the when the greater trochanter is malunited or when we
femoral canal. Therefore, recognizing the anatomi- want to transfer the trochanteric fragment distally at the
cal changes before and during surgery is crucial.
In this article, we describe specific surgical steps
and techniques by which these problems may be “[We describe] a stepwise
avoided, thus minimizing potential complications.
approach that can be
used to prevent potential

T
otal hip replacement (THR) is one treatment
option for failed hip fracture fixation. First, the
surgeon identifies the cause of symptoms and
complications.”
the reason for failure, which may include infec-
tion, malunion, nonunion, femoral head osteonecrosis, end of the operation in order to adjust abductor tension.
and progressive degenerative osteoarthritis, or any com- Plate and screws are left in place until the hip is dislo-
bination thereof. For patients with malunited fractures cated to minimize the risk for intraoperative fracture.
after sliding hip screw fixation, additional anatomical After exposure of the hip joint, the lesser trochanter
changes should be considered, such as medialization of is identified. The femoral neck is then osteotomized
the femoral canal, retroverted metaphysis, cortical thin- (around the lag screw) after making a direct measure-
ning, intramedullary remodeling and sclerosis around the ment of neck length above the lesser trochanter, accord-
lag screw tract, and malpositioned greater trochanter.1 ing to the preoperative plan. Because of a potential
Knowing these anatomical changes may help the surgeon medial bone defect of the proximal femur, this cut is
prepare for the instrumentation and implants needed and sometimes right at the lesser trochanter. If the lesser
anticipate intraoperative problems in order to prevent
potential complications.
We describe the surgical steps and technique to deal
specifically with a malunited intertrochanteric fracture
causing pain, shortening, and poor function.

Dr. Unnanuntana is Orthopaedic Surgeon, and Dr. Goodman is

Professor of Orthopaedic Surgery, Department of Orthopaedic
Surgery, Stanford University Medical Center, Stanford,
California.

Address correspondence to: Aasis Unnanuntana, MD, Department

of Orthopaedic Surgery, Stanford University Medical Center,
Stanford, CA 94035 (tel, 650-723-7072; fax, 650-723-6396; e-mail,
uaasis@yahoo.com). Figure 1. Conversion of failed fixation of an intertrochan-
teric fracture to total hip replacement. After a high-femoral
Am J Orthop. 2008;37(10):506-509. Copyright Quadrant HealthCom neck osteotomy was made around the lag screw, the femo-
Inc. 2008. All rights reserved. ral head was taken out in retrograde fashion.

506 The American Journal of Orthopedics ®

 A. Unnanuntana and S. B. Goodman

Figure 2. Intramedullary remodeling and sclerosis around A

lag screw results in obliteration of the femoral canal, leav-
Figure 3. (A) Preoperative
ing a large hole as a false tract (pointed by the forceps).
anteroposterior radiograph
of woman in her mid-50s
8 years after sliding hip
trochanteric fragment is malunited or not united, other screw fixation of an inter-
landmarks must be used. The femoral head together with trochanteric fracture. The
the lag screw is taken out in retrograde fashion (Figure patient presented with
1). The plate and screws over the lateral femoral cortex chronic groin and thigh
are exposed and removed through a longitudinal split pain and left hip shortening.
She required a 3-inch shoe
posteriorly over the vastus lateralis muscle. We always buildup and had fixed, 20°
prepare the femur first for hip replacement because it is flexion and external rota-
adequately exposed at this point. tion contracture of the hip.
Usually, bone remodeled around the lag screw tract The radiograph shows a
leads to intramedullary sclerosis and then obliteration 6-hole sliding screw plate.
There is medial displace-
of the femoral canal (Figure 2). A power burr may be ment of the femoral shaft
needed for removal of sclerotic bone and recanalization and varus malunion. The
of the femoral canal. Next, we use the smallest avail- femoral head has col-
able reamers or rasps to prepare the femoral canal. This lapsed, and the sliding hip
screw has penetrated the
step is performed with great care because the risk for B
femoral head and eroded
intraoperative femoral fracture is increased during con- the acetabulum. The lateral femoral cortex is very thin. (B)
version THR as a result of disuse osteoporosis, cortical Postoperative anteroposterior radiograph after conversion
defects and remodeling, deformity from malunion, and total hip replacement using cementless femoral stem and
so forth. An appropriately sized femoral component socket demonstrates good prosthetic position. A structural
should be selected before surgery. A calcar-replacing allograft reinforces the thin lateral femoral cortex. The abduc-
tor position and length are restored.
implant or an extended offset stem may be needed for
restoring the proximal medial bone loss and obtaining
a stable hip with equalization of limb lengths. Longer as is done for any other primary THR. Two potential
stemmed implants should be considered for bypassing problems are disuse osteoporosis and hardware pen-
the distal screw holes. Local bone grafting from the etration causing an acetabular defect. Careful, non-
excised femoral head and structural allografts may be aggressive reaming with frequent observation of the
needed to augment the thinned lateral femoral cortex, acetabular bed prevents iatrogenic protrusio. Defects
commonly found at the plate site (Figure 3). from screw penetration are usually contained and eas-
Fixation of the femoral component can be accom- ily managed with autologous bone grafting from the
plished using either cemented or cementless implants. femoral head.
For cemented stems, care must be taken to prevent We tend to use larger femoral heads (32 or 36 mm)
cement extrusion through the old screw holes during in the conversion THR setting because the patients
pressurization and prosthesis insertion. This can be usually have poor preoperative abductor tension and
done by various surgical techniques. We prefer simply shortening, which increases the risk for postoperative
bone grafting from the femoral head into the screw dislocation. We prefer that the polyethylene liner be at
holes and having the assistant use his or her fingers least 6 mm thick.
to press firmly over the screw holes during cement
pressurization, prosthesis insertion, and cement curing Postoperative Regimen
(Figure 4). For patients without any special considerations, gait
For the acetabular component, we usually use training and ambulation are similar to those used for
cementless fixation and prepare the acetabulum much primary THR. For trochanteric slide and fixation per-
October 2008 507
Conversion Total Hip Replacement After Malunited Intertrochanteric Fracture
Figure 4. (A) Preoperative
anteroposterior radiograph
of woman in her early 70s
8 months after sliding hip
screw fixation of an inter-
trochanteric fracture. The
patient presented with
severe pain and a limp that
limited ambulation. The
radiograph shows a mal-
united intertrochanteric
fracture with medializa-
tion of the femoral canal,
intramedullary remodel-
ing around the lag screw
tract, and lag screw cut
A B out of the femoral head. (B)
Postoperative conversion total hip replacement using a cemented stem shows proper position of the prosthesis, good cement
technique, correction of limb-length discrepancy, and restoration of abductor position and length. The trochanteric fragments
had united previously. The excised femoral head was morselized and used as a bone graft laterally.

formed because of trochanteric nonunion, we recom- head, have been used to minimize intraoperative com-
mend partial weight-bearing and use of an abduction plications. If the plate and screws are taken out first, the
brace for 6 weeks after surgery, and then progression remaining thin cortices may not withstand the torsional
as tolerated. force from dislocating the hip, which may result in a
fracture of the proximal femur. Bone remodeling around
Discussion the lag screw tract causes the femoral canal to be obliter-
Conversion to THR from malunited intertrochanteric ated by sclerotic bone, leaving a large hole in the lateral
fracture is indicated for posttraumatic osteoarthritis, femoral cortex (Figure 2). This can easily result in the
penetration of the lag screw into the acetabulum, or surgeon’s reaming and broaching too far laterally in the
(uncommonly) femoral head osteonecrosis. Clinical false tract. Using a power burr to open the femoral canal
results are not comparable to those of primary THR.2-5 first is an important step before reaming and broaching
In one study, Kaplan-Meier analysis with implant revi- to prevent fracture of the base of the greater trochanter.
sion as an endpoint showed 10-year survivorship to be The other often overlooked problem is abductor
87.5%.2 Because of the anatomical changes in patients weakness secondary to trochanteric nonunion or mal-

“Preoperative recognition of the anatomical changes

in malunited intertrochanteric fractures is crucial in
planning optimal surgical technique, instrumentation,
and implants.”
with failed internal fixation after intertrochanteric frac- union or shortening of the femur. This problem can
ture, THR in this setting was technically challenging, be addressed with use of a large femoral head and/or
and the rates of intraoperative and postoperative compli- transfer of the greater trochanter distally to tighten
cations were higher than usual. Zhang and colleagues5 the abductor tension. In some patients with extensive
reported a 47% incidence of early complication from anatomical distortion, including disruption of the hip
conversion to THR in 19 patients. Thirty-two percent of abductors, a constrained liner may be considered.
the patients had a greater trochanteric fracture. Two issues regarding selection of the femoral com-
In addressing the difficulties of conversion to THR in ponent are still controversial: use of a cemented or
malunited intertrochanteric fracture, we have described cementless femoral implant and use of standard or lon-
a stepwise approach that can be used to prevent potential ger stemmed components. Whether to use a cemented
complications. Before surgery, the surgeon should check or a cementless femoral component depends on the
for distortion of bony figure (malposition or nonunion bone quality and geometry of the femoral canal. When
of greater trochanter, medialization of femoral canal, a cemented femoral stem is used, good cement pres-
intramedullary sclerosis) and for changes in surrounding surization is important. Because the cement might
soft-tissue tension. Some techniques, such as removal extrude through the previous screw holes, containment
of side plate and screws after dislocation of femoral of cement during pressurization into the femoral canal
508 The American Journal of Orthopedics ®
 A. Unnanuntana and S. B. Goodman
is difficult. Some relevant techniques are use of screws Zimmer, Inc. (Warsaw, IN). Dr. Unnanuntana reports
cut short to close the holes,6 placement of surgical no actual or potential conflict of interest in relation to
gloves injected with cement,7 fashioning of bone plugs this article.
into the screw holes, and application of the assistant’s
thumb directly over the firmly packed gauze. References
Theoretically, the surgeon should attempt to extend 1. Kelley SS. Total hip arthroplasty after failed hip fracture fixa-
tion. In: Lieberman JR, Berry DJ, eds. Advanced Reconstruction
the length of the stem to more than twice that of the Hip. Rosemont, IL: American Academy of Orthopaedic Surgeons;
canal diameter beyond the most distal screw hole in 2005:167-173.
2. Haidukewych GJ, Berry DJ. Hip arthroplasty for salvage of failed
order to prevent the “stress riser” effect. However, small treatment of intertrochanteric hip fractures. J Bone Joint Surg Am.
defects, less than 20% to 30% of the bone diameter 2003;85(5):899-904.
(eg, screw holes), were found in some studies to cause 3. Haentjens P, Casteleyn PP, Opdecam P. Hip arthroplasty for failed
internal fixation of intertrochanteric and subtrochanteric fractures in
no significant reduction in torsional strength.8,9 Zhang the elderly patient. Arch Orthop Trauma Surg. 1994;113(4):222-227.
and colleagues5 showed no stress fracture in any of 19 4. Mehlhoff T, Landon GC, Tullos US. Total hip arthroplasty following
patients with a standard femoral component. failed internal fixation of hip fractures. Clin Orthop. 1991;(269):32-
37.
Preoperative recognition of the anatomical changes 5. Zhang B, Chiu KY, Wang M. Hip arthroplasty for failed internal fixation
in malunited intertrochanteric fractures is crucial in of intertrochanteric fractures. J Arthroplasty. 2004;19(3):329-333.
planning optimal surgical technique, instrumentation, 6. Patterson BM, Salvati EA, Huo MH. Total hip arthroplasty for com-
plications of intertrochanteric fracture. A technical note. J Bone Joint
and implants. Such planning should help minimize Surg Am. 1990;72(5):776-777.
operative time and perioperative complications while 7. Slater R, Morrison J, Kelly S. Custom-made molds that prevent
cement extrusion through bone defects. Clin Orthop. 1995;(317):126-
maximizing postoperative hip biomechanics. 130.
8. Burstein AH, Currey J, Frankel VH, Heiple KG, Lunseth P, Vessely
Authors’ Disclosure Statement JC. Bone strength. The effect of screw holes. J Bone Joint Surg Am.
1972;54(6):1143-1156.
Dr. Goodman wishes to note that he is a paid con- 9. Edgerton BC, An KN, Morrey BF. Torsional strength reduction due to
sultant to and has received research grants from cortical defects in bone. J Orthop Res. 1990;8(6):851-855.

October 2008 509