M. E. Steinberg, M.D., P. Larcom, M.D., B. Strafford, M.D.,
W. B. Hosick, M.D., A. Corces, M.D., R. E. Bands, M.D., K.
Hartman
Department of Orthopaedic Surgery, University of
Pennsylvania School of Medicine, Philadelphia, Pennsylvania.
Abstract: Core decompression is one of the more
popular procedures for the treatment of early stages of
avascular necrosis (AVN) of the femoral head. However, the
controversy regarding its safety and effectiveness
continues. In an attempt to clarify the situation, we are
reporting on a large series of cases performed by a single
surgeon with long-term follow-up. This is a prospective
study in which results have been evaluated using objective
clinical parameters and quantitative radiographic
measurements.
The classical core decompression, modified by using three
decompression tracks and placing a loosely fitted cancellous
graft into the larger central core, was performed on 406
hips with AVN between 1981 and 1995. Of these hips, 94 were
also treated with electrical stimulation; 74 with direct
current and 20 with capacitive coupling. Hips ranged from
Stage I (pre-radiographic) to Stage IV (femoral head
flattening without acetabular involvement). Results were
determined by change in Harris hip score (HHS), extent of
radiographic progression, and the need for total hip
replacement (THR).
Five complications occurred after the 406 procedures: 2
fractures, both resulting from falls; 1 non-fatal pulmonary
embolism; 1 femoral thrombophlebitis; and 1 pneumonia. There
was a minimum 2- to 14-year follow-up on 297 of the hips. Of
these, 107 (36%) required THR at a mean of 29 months. THR
was performed in 26% of hips in Stage I; 34% in Stage II;
31% in Stage III (crescent sign); and 48% in Stage IV.
Results were correlated with the size of the necrotic
lesion. In Stages I and II THR was performed in 22%, 39%,
and 40% of small (A), medium (B), and large (C) lesions,
respectively. In hips not requiring THR, 39% were
radiographically stable and the mean HHS improved by 10
points. No significant difference was noted in relation to
etiology. No differences were noted between hips treated
with or without supplemental electrical stimulation.
Core decompression with bone grafting, if carefully
performed, has a very low complication rate. In cases
treated before femoral head collapse, the outcome is
significantly better than with symptomatic or conservative
treatment. Results are correlated with both the stage of AVN
and the size of the necrotic lesion.
Introduction
It is generally recognized that without specific treatment
70% to 80% of hips with clinically established avascular
necrosis (AVN) will show radiologic and clinical
progression. Accordingly, several prophylactic procedures
have been used in the earlier stages of AVN to halt
progression and encourage repair. Of these, perhaps the most
frequently used to core decompression. This was described by
Arlet and Ficat in 1964 [5]. By 1980 they had performed more
than 800 cases [10,11]. This procedure has been used by
several investigators and was popularized in the United
States by Hungerford [12--14]; a complete review of the
literature was recently published by Mont, Carbone, and
Fairbank, 1996 [17]. Although the results reported in the
literature have been somewhat variable, satisfactory
clinical results are generally between two and three times
greater in hips treated with core decompression than in
those treated non-operatively [4,7,9--11,15--19,24,27,28].
After experiencing unsatisfactory outcomes in most of our
patients treated with protected weight bearing alone before
1980, we began using a modified type of core decompression
with supplemental bone grafting as our standard approach to
the treatment of hips with earlier stages of AVN, which was
later supplemented with electrical stimulation. By December
1995, this procedure had been performed on 406 hips, which
form the basis of this report.
Results
Patients ranged in age from 19 to 65 for a mean of 37 years,
166 (56%) were female and 131 (44%) were male. The follow-up
time for the entire group was between one and 156 months
with a mean of 46 months. This included patients who died or
came to THR before the minimum two-year follow-up for
inclusion in the study. The mean follow-up for patients not
requiring THR was 62 months.
Etiologic factors were as follows: steroid 38%, alcohol 37%,
both alcohol and steroid 15%, trauma 12%, idiopathic 10%.
Hips were placed in the following stages according to the
University of Pennsylvania system for staging [27,28]: Stage
I, 62 hips (21%); Stage II, 133 hips (45%); Stage III, 13
hips (4%); Stage IV, 85 hips (29%); Stage V, 4 hips (1%).
Results in the entire group of 406 hips were initially
evaluated regarding both the immediate post-operative and
longer term complications. Outcome was evaluated only in the
297 hips with a minimum two-year follow-up. This was
determined by the number of hips in each group which
required THR arthroplasty, the clinical status as determined
by a change in the HHS from the pre-operative to the most
recent post-operative evaluation, and the change in the
radiographic stage and extent of involvement as determined
by the University of Pennsylvania system for evaluation and
staging [25,26]...
...Summary and Conclusions
If untreated, approximately 70% to 80% of hips with
clinically established AVN show progression and most of
these eventually require replacement arthroplasty.
Accordingly, some method of prophylactic management is
indicated in hips diagnosed in the earlier stages of AVN. Of
the various treatment options, one of the more popular is
core decompression. We have reported on 406 hips treated
with a modified core decompression and supplemental
cancellous bone grafting. Some also received electrical
stimulation. Although we have personally had no experience
with PEMFs in AVN, we felt that it would be of interest to
make brief mention of this technique based on reports in the
literature [2--4,6,8]. In contrast to the two types of
electrical stimulation described earlier, this technique
produces an electrical and a magnetic field in the area of
bone being stimulated by the use of an externally applied
coil. Few investigators have reported promising results
using this technique in the treatment of AVN without
operative intervention. Aaron [1] recently reported on 633
patients treated with PEMFs and observed for thirty-six
months. These were compared with hips treated with core
decompression and those on protected weight bearing. In
Ficat I and II hips, the results of PEMF and core
decompression were essentially equal, and both were superior
to protected weight bearing. In Stage III the results with
PEMF were significantly better than either core
decompression or protected weight bearing. The survival of
the femoral heads in these three groups was 53%, 27%, and
10%, respectively.
Unfortunately, this device has not been released for general
use in the United States by the Food and Drug Administration
and further trials have been postponed. These results by a
few investigators are certainly promising and should be kept
in mind.
Our data demonstrate that core decompression and grafting is
quite safe with an extremely low complication rate including
only two transcervical fractures, both resulting from
post-operative falls. Although by no means a panacea, the
procedure appears to be effective as compared with protected
weight bearing alone. For the entire series only 36% of
treated hips required THR arthroplasty, as compared with 77%
of controls. Viewed in terms of survivorship, this meant
that in 64% of operated hips the femoral head was preserved,
as compared with only 23% of controls. As expected, the
results were better in hips with earlier stage lesions and
in hips in which the area of necrosis was small. Neither DC
nor CC improved the eventual outcome. PEMFs, as reported by
other investigators, may be a promising technique which
deserves further evaluation.
All hips treated here had both a decompression and
cancellous grafting. No attempt was made to compare the
results of core decompression with and without grafting. Our
results, however, are similar to those reported by most
other investigators regarding non-operative management and
core decompression alone.
Core decompression with or without bone grafting is a
simple, safe, and relatively effective method for treating
early stages of AVN. Other methods of treatment are
available, but most of these are more complicated and have a
higher potential incidence of complications. Only if these
are definitely shown to be more effective, would we advocate
using these techniques rather than the technique described
here. At this time, core decompression with bone grafting
remains our standard approach to hips with early stages of
AVN in most patients we encounter.
