A periprosthetic fracture around the femoral stem is a rare yet
potentially problematic complication of total hip arthroplasty. Studies
ranging in size from 159 to 2360 patients have demonstrated periprosthetic
fracture rates ranging from 1% to
6%1-3.
With the predicted rise in the number of patients undergoing total hip
arthroplasty in the future and the increase in the number of patients with
long-standing total hip implants in place, the prevalence of periprosthetic
fractures is expected to
rise4,5.
Surgical intervention is commonly required for the treatment of femoral
periprosthetic
fractures6. The type
of surgical intervention that is selected depends on three main factors: the
site of fracture, the status of the host bone, and the status of the femoral
stem in place. The Vancouver classification, a validated system, is the most
commonly used classification scheme that takes these factors into account and
provides an algorithm for
treatment7,8.
Periprosthetic femoral fractures in patients with severe proximal bone
deficiency and a loose femoral stem (Vancouver type-B3 fractures) represent a
challenging problem. Available options for the treatment of these fractures
include a fully coated
stem9, a fluted
tapered stem10, a
proximal femoral
replacement7,11,
an allograft-prosthesis
composite12, and
resection
arthroplasty13. The
use of an uncemented stem may be precluded because of a lack of adequate
diaphyseal bone support for
fixation14,15.
A proximal femoral replacement may be utilized in some of these cases,
particularly in elderly patients.
The present report describes the outcomes for a cohort of patients who had
been managed with revision total hip arthroplasty with use of a proximal
femoral replacement for the treatment of a Vancouver type-B3 periprosthetic
fracture.
Demographic Data
With use of a computerized institutional database, all patients in
whom a periprosthetic femoral fracture had been treated with proximal femoral
replacement from 1995 to 2002 were identified. During this period, 139
patients with a periprosthetic femoral fracture had been managed at our
institution. Twenty-one of these patients had received a proximal femoral
replacement for the treatment of a Vancouver type-B3 fracture. These patients
included fourteen women and seven men who had had a mean age of 78.3 years
(range, fifty-two to ninety years) at the time of the index operation. The
clinical records and radiographs of these patients were reviewed in
detail.
Follow-up
The total joint registry at our institution prospectively collects clinical
and radiographic data on all patients undergoing arthroplasty. The average
duration of follow-up for the twenty-one patients in the present study was 3.2
years (range, two to seven years). All patients were followed clinically for a
minimum of two years, until failure of the hip prosthesis, or until death. No
patient was lost to follow-up, and all patients had a minimum of two years of
follow-up. Three patients died during the follow-up period; all of the deaths
were unrelated to the hip procedure. The clinical outcome was measured with
use of the Harris hip
score16.
Radiographic Evaluation
Serial anteroposterior and lateral radiographs of the involved joint were
reviewed in detail. Preoperative radiographs were reviewed to assess bone
stock, the position and status of the stem, and the morphological
characteristics of the fracture. Bone loss and radiolucent lines were assessed
with use of the seven femoral zones described by Gruen et
al.17 and the three
acetabular zones described by DeLee and
Charnley18.
Heterotopic ossification was graded according to the system of Brooker et
al.19.
Preoperative Data
A periprosthetic fracture had occurred around a cemented femoral stem in
sixteen patients and around an uncemented femoral stem in five patients. All
patients had undergone at least one and an average of three (range, one to
seven) previous operations on the involved joint. All patients were confirmed
to have severe proximal bone deficiency, and all had sustained a fracture
around the femoral stem that had led to loosening of the stem.
Surgical Data
A direct lateral (Hardinge) approach was used in all cases. The proximal
bone was of such poor quality that an extended osteotomy to remove the
component and/or cement usually was not necessary. If necessary, we split the
femur in the coronal plane and in continuation with the fracture line.
Débridement of the hip was carried out to remove metal debris and
hardware from around the femur, if present. The acetabulum was exposed and
examined carefully. If the acetabular component was appropriately placed and
stable, it was left in place and the liner was exchanged. If the acetabular
component was malpositioned or was loose, a new component was inserted in a
press-fit manner with screw fixation. A more complex acetabular reconstruction
was occasionally needed. The type of acetabular liner was determined after
completion of reconstruction of the femur because constrained liners were
utilized in patients with poor soft tissue and a high probability of
instability.
Following extraction of the femoral component and cement from the proximal
part of the femur, a transverse osteotomy was performed in the host bone at
the most proximal area with adequate circumferential quality bone. The maximum
length of the native femur was maintained at all costs. The proximal bone was
retracted and the femoral canal was prepared by broaching, with preservation
of the cancellous bone (when present) for better cement interdigitation. After
completion of femoral preparation, trial components were inserted and the
stability of the hip was examined. The position of the femoral component was
marked with cautery or an osteotome to ensure appropriate rotational alignment
of the final components. Limb length also was assessed carefully. One method
that was used was to apply traction to the limb and to measure the distance
from the cup to the host bone osteotomy site. With the long-stem trial
prosthesis in place, proper limb length usually was restored accurately.
The trial components were then removed, and a cement restrictor was
inserted distal to the isthmus to allow pressurization of the cement mantle.
Antibiotics (tobramycin and vancomycin) were added to the cement. The femoral
component was cemented into place, with care being taken to ensure that the
porous-coated proximal portion of the stem was placed directly and firmly
against diaphyseal bone with no interpositioning cement. The proximal portion
of the femur, however poor in quality, was maintained and wrapped around the
prosthesis at the conclusion of implantation. The muscle-tendon attachments
were preserved whenever possible. The soft tissues, and particularly the
abductor muscles if present, were secured meticulously around the prosthesis.
Either wires or multiple loops of nonabsorbable sutures such as Dacron tape
(Genzyme, Fall River, Massachusetts) were passed around the remnant of the
trochanter and the attached soft tissue. Then, the limb was placed in
abduction and the trochanter was fixed firmly onto the proximal portion of the
prosthesis by passing the sutures through the holes in the prosthesis or
around the proximal body of the prosthesis and the deep tissues. We
occasionally sutured the abductors to the vastus lateralis, the tensor fasciae
latae, or the host greater trochanter, if available.
A constrained liner was indicated for patients with properly positioned
components and equal or nearly equal limb lengths who had intraoperative
instability secondary to soft-tissue deficiency. The constrained liner was
either snap-fit or cemented into the shell, depending on the type of the
acetabular component that had been implanted.
A modular proximal femoral replacement (Stryker Orthopaedics, Mahwah, New
Jersey) was used in all patients. The acetabular component was revised in ten
patients. In the remaining eleven patients, the acetabular component was
examined and was found to be well fixed and well positioned. Fourteen patients
had a nonconstrained acetabular component; the diameter of the femoral head
that was used in conjunction with the nonconstrained acetabular component was
22 mm in two patients, 28 mm in six, and 32 mm in six. The remaining seven
patients had a constrained liner. Strut allograft was used to reinforce the
proximal part of the femur in four patients.
Postoperatively, all of the patients were allowed to walk and to bear
weight as tolerated. None of the patients in this group were managed with a
brace, but hip precautions, including limitation of flexion to 90°,
avoidance of leg-crossing, and the use of a high chair and elevated toilet
seat for six to twelve weeks, were instituted.
Functional Evaluation
Because of the fractures, all patients were in severe pain and were
unable to bear weight prior to the index procedure. Revision surgery restored
function to all patients but one. At the time of the latest follow-up, the
average Harris hip score was 71 points (range, 56 to 90 points) and twenty
patients were able to walk. These twenty patients were either pain-free
(eighteen hips) or had minimal pain (two hips). The remaining patient, who had
had an early failure of the acetabular cage reconstruction, had undergone a
resection arthroplasty and was unable to walk.
The outcome was considered to be excellent or good (as indicated by a hip
score of >80 points, no use of a walking aid, and a nonpainful hip) for
eleven hips, fair for nine, and poor for one. All patients who had a fair
outcome had adverse effects on the hip score due to symptomatic degenerative
joint disease affecting other joints or used a walking aid for support. The
outcome was considered to be poor for the one patient who had had a resection
arthroplasty because of failure of the acetabular cage.
Walking Ability
Prior to the fracture, all patients had been able to walk: two patients had
used a walker, four had used a cane or crutches on a full-time basis, four had
used a cane for long walks, and eleven had not used any walking aids. At the
time of the latest follow-up, one patient was unable to walk, six were able to
walk in the home only, and fourteen were able to walk outside the home. Among
the twenty patients who were able to walk, five used a walker full time, three
used two canes or crutches, four used a cane, and eight used no walking
aids.
Radiographic Findings
All fractures healed, and the strut allografts appeared to have
incorporated. In two patients there appeared to be resorption of proximal
bone, and in five patients the proximal part of the femur appeared to have
incorporated onto the prosthesis. In the remaining patients, the status of the
extremely poor-quality proximal femoral bone could not be determined because
of our inability to visualize the fragments on the radiographs. At the time of
the latest follow-up, all stems were found to be stable. A nonprogressive
radiolucent line (<2 mm in width) was identified around the cemented
portion of the femoral stem in four patients. These lines remained stable
throughout the period of study. The position of the acetabular component was
considered to be acceptable in twenty hips. One acetabular component had been
removed as part of a resection arthroplasty. No hip had evidence of gross
poly-ethylene wear, as indicated by eccentric positioning of the femoral head
on the acetabular cup, at the time of the latest follow-up. Three hips had
radiographic evidence of Brooker grade-I heterotopic ossification.
Complications
Medical complications included arrhythmia (two patients), postoperative
confusion (one patient), pulmonary embolus (one patient), and urinary tract
infection (one patient).
With regard to orthopaedic complications, dislocation occurred in two hips
in which the acetabular component had not been revised at the time of the
index procedure. The dislocation in one patient was treated nonoperatively
with immobilization in an abduction orthosis, with no additional problems. The
other patient had recurrent dislocations and underwent revision arthroplasty
with use of a constrained acetabular liner, with retention of the proximal
femoral replacement. Two patients had persistent wound drainage and
superficial wound infections that were treated with incision and drainage as
well as intravenous administration of antibiotics. One patient sustained a
nondisplaced periprosthetic fracture distal to the stem after a fall and was
managed nonoperatively with a cast-brace. Finally, one patient had a failure
of an acetabular cage construct three weeks postoperatively. At the time of
rerevision, the acetabulum was determined not to be reconstructable and a
resection arthroplasty was performed. No other complications occurred, and no
other revisions or reoperations were performed.
Proximal femoral replacement originally was designed for the
treatment of femoral reconstruction after tumor
resection20.
Because of the relative success of this procedure, many surgeons began using
proximal femoral replacement for the treatment of failed total hip
arthroplasty in patients with severe proximal femoral bone
loss11,21.
Malkani et al.11
retrospectively reviewed and reported the Mayo Clinic experience with fifty
failed total hips treated with proximal femoral replacement and found a
substantial improvement in function as measured with use of the Harris hip
score. With revision as the end point, survivorship was reported to be 64% at
twelve years. That series included three patients with a periprosthetic
fracture of the femur. Springer et
al.22, in another
study from the Mayo Clinic, evaluated the results of treatment of
periprosthetic femoral fractures with use of an allograft-prosthesis composite
(fourteen hips) or a proximal femoral replacement (four hips). Fifteen of
these eighteen fractures were classified as Vancouver type-B3 fractures. After
5.7 years of follow-up, the results were modest as there had been six
revisions for the treatment of aseptic loosening and one revision for the
treatment of infection. However, as the majority of the patients in that study
received an allograft-prosthesis composite replacement, a direct comparison
between that study and the current one is not possible.
After short-term follow-up, we observed that modular proximal femoral
replacement provides acceptable results for the treatment of Vancouver type-B3
periprosthetic fractures. Similar to previous
investigators11,21,
we observed a relatively large number of complications. One of the more common
complications was dislocation. The etiology of dislocation following revision
surgery with proximal femoral replacement is likely to be multifactorial. The
first, and perhaps foremost, factor is that all of our patients had undergone
multiple previous operations with a breach of the abductor mechanism. Hence,
abductor deficiency probably was a major contributor to instability in these
patients. The second factor may be related to limb-length discrepancy and the
inability to restore adequate soft-tissue tension in some of these patients.
We believe that the use of a modular prosthesis has provided a better strategy
for dealing with this problem. We believe that the proximal femoral bone,
however poor in quality, should be retained and reapproximated to the
prosthesis in order to minimize dislocation. In addition, all efforts should
be made to achieve equal limb lengths and to obtain acceptable soft-tissue
tension. Another important factor in the prevention of instability is the use
of larger femoral heads in elderly patients who have a low level of activity.
Finally, the stability of the hip should be tested diligently and a
constrained liner should be utilized if instability is encountered
intraoperatively (Figs. 1-A and
1-B).
The extremely poor bone stock was related to many of the complications in
our series. One patient had early failure (pullout) of an acetabular cage and
subsequently required a resection arthroplasty. Another patient sustained a
refracture of the femur, distal to the prosthesis, and was managed
nonoperatively.
There were no failures of the femoral stem after short-term follow-up. In
order to obtain optimal cement interdigitation, we utilized a cement
restrictor and pressurized the cement. A nonprogressive radiolucent line was
observed around the cemented portion of the femoral stem in four patients. The
radiolucent lines remained stable and nonsymptomatic in these patients. We
continue to monitor all of these patients closely because aseptic loosening is
known to occur with a higher frequency, particularly in active patients. The
long lever arm of the femoral component with the distally fixed portion is
thought to create high torsional stresses at the bone-cement-prosthesis
interface and to lead to early loosening of the
construct23. In
order to avoid failure, we reserve proximal femoral replacement for older,
less active patients.
The present report describes the short-term results for a cohort of
patients who had been managed with a single design of proximal femoral
replacement for the treatment of a Vancouver type-B3 periprosthetic fracture
at a single institution. We found that the use of a proximal femoral
replacement for the treatment of these difficult fractures is a viable option
for low-demand patients. ?