The aims of this study were to examine the rate at which the
positioning of the acetabular component, leg length discrepancy
and femoral offset are outside an acceptable range in total hip
arthroplasties (THAs) which either do or do not involve the use
of intra-operative digital imaging. A retrospective case-control study was undertaken with 50 patients
before and 50 patients after the integration of an intra-operative
digital imaging system in THA. The demographics of the two groups
were comparable for body mass index, age, laterality and the indication
for surgery. The digital imaging group had more men than the group without.
Surgical data and radiographic parameters, including the inclination
and anteversion of the acetabular component, leg length discrepancy,
and the difference in femoral offset compared with the contralateral
hip were collected and compared, as well as the incidence of altering
the position of a component based on the intra-operative image.Aims
Patients and Methods
The orientation of the acetabular component is
influenced not only by the orientation at which the surgeon implants
the component, but also the orientation of the pelvis at the time
of implantation. Hence, the orientation of the pelvis at set-up
and its movement during the operation, are important. During 67
hip replacements, using a validated photogrammetric technique, we
measured how three surgeons orientated the patient’s pelvis, how
much the pelvis moved during surgery, and what effect these had
on the final orientation of the acetabular component. Pelvic orientation
at set-up, varied widely (mean (± 2, standard deviation ( Cite this article:
Femoroacetabular impingement (FAI) is commonly
associated with early hip arthritis. We reviewed our series of 1300
hip resurfacing procedures. More than 90% of our male patients,
with an average age of 53 years, had cam impingement lesions. In
this condition, there are anterior femoral neck osteophytes, and
a retroverted femoral head on a normally anteverted neck. It is
postulated that FAI results in collision of the anterior neck of
the femur against the rim of the acetabulum, causing damage to the
acetabular labrum and articular cartilage, resulting in osteoarthritis.
Early treatment of FAI involves arthroscopic or open removal of
bone from the anterior femoral neck, as well as repair or removal
of labral tears. However, once osteoarthritis has developed, hip
replacement or hip resurfacing is indicated. Hip resurfacing can
re-orient the head and re-shape the neck. This helps to restore
normal biomechanics to the hip, eliminate FAI, and improve range
of motion. Since many younger men with hip arthritis have FAI, and
are also considered the best candidates for hip resurfacing, it
is evident that resurfacing has a role in these patients.
A variety of radiological methods of measuring
version of the acetabular component after total hip replacement (THR)
have been described. The aim of this study was to evaluate the reliability
and validity of six methods (those of Lewinnek; Widmer; Hassan et
al; Ackland, Bourne and Uhthoff; Liaw et al; and Woo and Morrey)
that are currently in use. In 36 consecutive patients who underwent
THR, version of the acetabular component was measured by three independent
examiners on plain radiographs using these six methods and compared
with measurements using CT scans. The intra- and interobserver reliabilities
of each measurement were estimated. All measurements on both radiographs
and CT scans had excellent intra- and interobserver reliability
and the results from each of the six methods correlated well with
the CT measurements. However, measurements made using the methods
of Widmer and of Ackland, Bourne and Uhthoff were significantly
different from the CT measurements (both p <
0.001), whereas
measurements made using the remaining four methods were similar
to the CT measurements. With regard to reliability and convergent
validity, we recommend the use of the methods described by Lewinnek,
Hassan et al, Liaw et al and Woo and Morrey for measurement of version
of the acetabular component.
Bone preservation and physiological distribution of forces on the proximal femur are key elements in introducing a successful uncemented total hip replacement. In order to achieve this, in the mid 1990s, we developed an ultra short proximal loading custom-made component with a lateral flare, a high femoral neck osteotomy and without a diaphyseal stem. We report the outcome of 129 custom-made hydroxyapatite-coated uncemented short femoral components inserted into 109 patients between June 1995 and May 2004. The mean age of the patients was 51 years (21 to 71) and the mean follow-up was eight years (4.9 to 14.1). Bone behaviour around the implant was studied on the post-operative radiographs. The mean Harris hip score improved from 44 (8 to 66) pre-operatively to 95 (76 to 100) at final follow-up. The Western Ontario MacMaster University Osteoarthritis index was 93 of 100 at final review. None of the patients reported thigh pain. A total of five hips were revised, three for polyethylene liner exchange and two for complete revision of the acetabular component. No femoral components were revised. The radiological changes in the proximal femur were generally good, as evidenced by spot welds both on the medial and lateral aspects of the femur. No component migrated. The presence of a lateral flare and use of a high osteotomy of the femoral neck provided good clinical and radiological results. The absence of a diaphyseal portion of the stem did not impair stability.
Early failure associated with adverse reactions to metal debris is an emerging problem after hip resurfacing but the exact mechanism is unclear. We analysed our entire series of 660 metal-on-metal resurfacings (Articular Surface Replacement (ASR) and Birmingham Hip Resurfacing (BHR)) and large-bearing ASR total hip replacements, to establish associations with metal debris-related failures. Clinical and radiological outcomes, metal ion levels, explant studies and lymphocyte transformation tests were performed. A total of 17 patients (3.4%) were identified (all ASR bearings) with adverse reactions to metal debris, for which revision was required. This group had significantly smaller components, significantly higher acetabular component anteversion, and significantly higher whole concentrations of blood and joint chromium and cobalt ions than asymptomatic patients did (all p <
0.001). Post-revision lymphocyte transformation tests on this group showed no reactivity to chromium or cobalt ions. Explants from these revisions had greater surface wear than retrievals for uncomplicated fractures. The absence of adverse reactions to metal debris in patients with well-positioned implants usually implies high component wear. Surgeons must consider implant design, expected component size and acetabular component positioning in order to reduce early failures when performing large-bearing metal-on-metal hip resurfacing and replacement.
Using radiography and computer tomography (CT) we studied the morphology of 83 hips in 69 Caucasian adults with osteoarthritis secondary to developmental dysplasia of the hip (DDH). A previously published series of 310 hips with primary osteoarthritis was used as a control group. According to the Crowe classification, 33 of the dysplastic hips were graded as class I, 27 as class II and 23 as class III or class IV. The intramedullary femoral canal had reduced mediolateral and anteroposterior dimensions in all groups compared with the control group. Only in Crowe class II hips was the femoral neck-shaft angle increased. The proximal femur had more anteversion in all the developmental dysplasia of the hip groups, ranging from 2° to 80°. Templated measurement of acetabular dimensions for plain radiography closely matched measurements taken by CT. The results of our study confirm the observations previously confined to the Japanese population.
