Improvements in functional results and long-term survival are variable following conversion of hip fusion to total hip arthroplasty (THA) and complications are high. The aim of the study was to analyze the clinical and functional results in patients who underwent conversion of hip fusion to THA using a consistent technique and uncemented implants. A total of 39 hip fusion conversions to THA were undertaken in 38 patients by a single surgeon employing a consistent surgical technique and uncemented implants. Parameters assessed included Harris Hip Score (HHS) for function, range of motion (ROM), leg length discrepancy (LLD), satisfaction, and use of walking aid. Radiographs were reviewed for loosening, subsidence, and heterotopic ossification (HO). Postoperative complications and implant survival were assessed.Aims
Methods
It may not be possible to undertake revision total hip arthroplasty
(THA) in the presence of massive loss of acetabular bone stock using
standard cementless hemispherical acetabular components and metal
augments, as satisfactory stability cannot always be achieved. We
aimed to study the outcome using a reconstruction cage and a porous
metal augment in these patients. A total of 22 acetabular revisions in 19 patients were performed
using a combination of a reconstruction cage and porous metal augments.
The augments were used in place of structural allografts. The mean
age of the patients at the time of surgery was 70 years (27 to 85)
and the mean follow-up was 39 months (27 to 58). The mean number
of previous THAs was 1.9 (1 to 3). All patients had segmental defects
involving more than 50% of the acetabulum and seven hips had an
associated pelvic discontinuity. Aims
Patients and Methods
We retrospectively reviewed 44 consecutive patients
(50 hips) who underwent acetabular re-revision after a failed previous
revision that had been performed using structural or morcellised
allograft bone, with a cage or ring for uncontained defects. Of
the 50 previous revisions, 41 cages and nine rings were used with
allografts for 14 minor-column and 36 major-column defects. We routinely
assessed the size of the acetabular bone defect at the time of revision
and re-revision surgery. This allowed us to assess whether host
bone stock was restored. We also assessed the outcome of re-revision
surgery in these circumstances by means of radiological characteristics,
rates of failure and modes of failure. We subsequently investigated
the factors that may affect the potential for the restoration of bone
stock and the durability of the re-revision reconstruction using
multivariate analysis. At the time of re-revision, there were ten host acetabula with
no significant defects, 14 with contained defects, nine with minor-column,
seven with major-column defects and ten with pelvic discontinuity.
When bone defects at re-revision were compared with those at the
previous revision, there was restoration of bone stock in 31 hips, deterioration
of bone stock in nine and remained unchanged in ten. This was a
significant improvement (p <
0.001). Morselised allografting
at the index revision was not associated with the restoration of
bone stock. In 17 hips (34%), re-revision was possible using a simple acetabular
component without allograft, augments, rings or cages. There were
47 patients with a mean follow-up of 70 months (6 to 146) available
for survival analysis. Within this group, the successful cases had
a minimum follow-up of two years after re-revision. There were 22 clinical
or radiological failures (46.7%), 18 of which were due to aseptic
loosening. The five and ten year Kaplan–Meier survival rate was
75% (95% CI, 60 to 86) and 56% (95% CI, 40 to 70) respectively with
aseptic loosening as the endpoint. The rate of aseptic loosening
was higher for hips with pelvic discontinuity (p = 0.049) and less
when the allograft had been in place for longer periods (p = 0.040). The use of a cage or ring over structural allograft bone for
massive uncontained defects in acetabular revision can restore host
bone stock and facilitate subsequent re-revision surgery to a certain
extent. Cite this article:
The use of ilioischial cage reconstruction for
pelvic discontinuity has been replaced by the Trabecular Metal (Zimmer,
Warsaw, Indiana) cup-cage technique in our institution, due to the
unsatisfactory outcome of using a cage alone in this situation.
We report the outcome of 26 pelvic discontinuities in 24 patients
(20 women and four men, mean age 65 years (44 to 84)) treated by
the cup-cage technique at a mean follow-up of 82 months (12 to 113)
and compared them with a series of 19 pelvic discontinuities in
19 patients (18 women and one man, mean age 70 years (42 to 86))
treated with a cage at a mean follow-up of 69 months (1 to 170).
The clinical and radiological outcomes as well as the survivorship
of the groups were compared. In all, four of the cup-cage group
(15%) and 13 (68%) of the cage group failed due to septic or aseptic
loosening. The seven-year survivorship was 87.2% (95% confidence interval
(CI) 71 to 103) for the cup-cage group and 49.9% (95% CI 15 to 84)
for the cage-alone group (p = 0.009). There were four major complications
in the cup-cage group and nine in the cage group. Radiological union
of the discontinuity was found in all successful cases in the cup-cage
group and three of the successful cage cases. Three hips in the
cup-cage group developed early radiological migration of the components,
which stabilised with a successful outcome. Cup-cage reconstruction is a reliable technique for treating
pelvic discontinuity in mid-term follow-up and is preferred to ilioischial
cage reconstruction. If the continuity of the bone graft at the
discontinuity site is not disrupted, early migration of the components
does not necessarily result in failure. Cite this article:
In this retrospective study we evaluated the
proficiency of shelf autograft in the restoration of bone stock
as part of primary total hip replacement (THR) for hip dysplasia,
and in the results of revision arthroplasty after failure of the primary
arthroplasty. Of 146 dysplastic hips treated by THR and a shelf
graft, 43 were revised at an average of 156 months, 34 of which
were suitable for this study (seven hips were excluded because of
insufficient bone-stock data and two hips were excluded because
allograft was used in the primary THR). The acetabular bone stock
of the hips was assessed during revision surgery. The mean implant–bone
contact was 58% (50% to 70%) at primary THR and 78% (40% to 100%)
at the time of the revision, which was a significant improvement
(p <
0.001). At primary THR all hips had had a segmental acetabular
defect >
30%, whereas only five (15%) had significant segmental
bone defects requiring structural support at the time of revision.
In 15 hips (44%) no bone graft or metal augments were used during
revision. A total of 30 hips were eligible for the survival study. At a
mean follow-up of 103 months (27 to 228), two aseptic and two septic
failures had occurred. Kaplan-Meier survival analysis of the revision
procedures demonstrated a ten-year survival rate of 93.3% (95% confidence
interval (CI) 78 to 107) with clinical or radiological failure as
the endpoint. The mean Oxford hip score was 38.7 (26 to 46) for
non-revised cases at final follow-up. Our results indicate that the use of shelf autografts during
THR for dysplastic hips restores bone stock, contributing to the
favourable survival of the revision arthroplasty should the primary
procedure fail. Cite this article:
