Adverse bone remodeling in the proximal femur may be detrimental to the long term survival of resurfacing prosthesis. Bone resorption beneath the femoral shell and thinning of the femoral neck have been observed. We present a radiological analysis of the incidence, rate, site of neck thinning and changes observed within the femoral neck, in 100 cases, with a minimum of five years follow-up.

Femoral neck diameter was measured at zero, two and five years post-operatively, at the head neck junction and five mm distally. Pre and post-operative head to neck ratios, natural and reconstructed offset, femoral neck-shaft and stem-shaft angles and cup inclination angle were measured.

Two distinct patterns of neck thinning were observed. In 76 cases (slow thinning group), we observed a reduction of < 5% of original neck diameter at two years and < 10 % at five years (mean 1.5%, sd+/− 1.5). In 24 cases (rapid thinning group), a reduction of > 5% of original neck diameter at two years and > 10% at five years (mean 10.4%, sd+/− 4.8) was observed. The difference in the percentage reduction in neck diameter was significantly different between the two groups at both time points (p< 0.01). Larger head-neck ratios were observed in the rapid thinning group, both pre and post operatively (p< 0.01).

The viability of bone underneath the femoral head may be compromised as a consequence of a non-physiological bone loading mechanism. FEA has predicted stress shielding underneath the femoral head and loading of the mini stem. Compromised blood supply of the retained epiphyseal remnant may play a part in femoral head resorption.

Femoral neck thinning is a phenomenon of unproven aetiology which affects almost 25% of our resurfacing cases.

Hip resurfacing is widely recognised as a bone conserving procedure with respect to proximal femoral resection. However, it has been argued that this is not the case for the acetabulum due to the thickness of the acetabular component and the large diameter bearing surfaces. We have investigated whether the Birmingham Hip is a bone conserving procedure with respect to the acetabular bone stock.

Data was obtained from 257 consecutive Midland Medical Technology (MMT) surface replacements and 458 primary hybrid total hip replacements implanted under our care. The surface replacement group comprised 185 males (185 hips) and 72 females (72 hips) with a mean age at surgery of 55 years. The hybrid primary total hip replacement group comprised 207 males (207) and 251 females (251 hips). The mean age at surgery was 65 years old. In the surface replacement group the mean uncemented acetabular size implanted was 54.88 mm (females = 51.9 mm; males = 57.8 mm). In the hybrid primary total hip replacement group the mean uncemented acetabular size of 55.04 mm (females =52.9 mm; males = 57.2 mm).

Statistical analysis was undertaken to compare the uncemented acetabular sizes in the surface replacement group with the uncemented acetabular sizes implanted in the primary hybrid total hip replacement group. We report no significant difference in the size of acetabular component used for the two groups (p = 0.4629; 95% C.I. −0.28 to 0.61). The effect of gender was analysed and the mean size of uncemented acetabular component implanted in males for the surface replacement group was not significantly different (p = 0.06) to the hybrid primary total hip replacement group. However the mean size of uncemented acetabular component in females for the surface replacement group was significantly smaller (p = 0.016) compared to the primary total hip replacement group.

We conclude hip resurfacing is not bone sacrificing on the acetabular bone stock and can be bone conserving for females.

We have reviewed 20 cases of parosteal osteosarcoma treated by wide local resection and prosthetic replacement and followed up for six to 17 years. Limb function was excellent in 85%. One patient with grade III histological disease developed pulmonary metastases. Four patients had local recurrences, which were related to repeated preliminary biopsies, inappropriate siting of biopsy and vascular encroachment by the tumour. After this mode of treatment, the outcome was not related to medullary invasion by the tumour.

Between 1969 and 1971 20 prototypes of the Stanmore total knee prosthesis were used to replace severely arthritic knees in 18 patients. Seven patients died before the final follow-up and one had to have her leg amputated because of deep infection; in none of these patients had the prosthesis become loose. Ten patients (11 knees) were reviewed at least 10 years after operation. There was no significant clinical deterioration in 7 of these 11 surviving knees when the results at one year were compared with those at 10 years.

We review 210 Stanmore knee replacements in 163 patients to assess the survival of the prostheses and the long-term results. The annual rate of failure reached a maximum of 4.6% in the fourth year after operation; thereafter it declined to reach zero by the eighth year. Between two and eight years after operation, 66.3% of the surviving knees were completely free of pain and 30.2% had mild retropatellar pain. Fixed flexion deformities present before operation were completely corrected in 73% of the knees, and varus or valgus deformities were invariably corrected. Stability was always restored to unstable knees and 80.8% of knees flexed to 90 degrees or more after replacement. Aseptic loosening (8.1%), prosthetic infection (4.3%) and femoral fracture (2.9%) led to 8.5% of the prostheses being revised or removed over eight years. Modifications in prosthetic design and operative techniques have been introduced to minimise such complications in the future.