Aim: Analyse the outcome of primary and revision total hip replacement using the Oxford hip score. To determine any variation in outcome when analysing for age of patient. In addition, to compare the outcome in the National Health Service compared to the Private hospital. Method: We have used the Oxford Hip score to monitor the progress of 1441 primary and 173 revision hip replacements (THR) undertaken since the start of 1995 whose hips have been replaced, at St Helier Hospital, Carshalton and St Anthony’s Hospital, Cheam, over the last seven years. Our review programme was started in early 1999 and has generated 2286 Oxford assessments.). A subgroup of 634 National Health Service (NHS) and 322 private patients (PP), treated by the senior author, has provided 1277 Oxford assessments. Results: Mean preoperative scores were 39.06 and 39.48 for primary and revision THR respectively. The mean annual scores, for primary THR, from 12 to 84 months declined to 21 points at 1 year, 21 at 2 years, 21 at 3 years, 20 at 4 years, 22 at 6 years and 21 at 7 years. Conclusion: All postoperative reviews show a significant improvement (p ≤0.0001). The 50–60 year old group scored significantly better than the over 80 year patients up to 48 months, (p< 0.01) The mean preoperative score for the NHS patients was significantly higher than the PPs (p< 0.001). The PPs scored significantly better than the NHS group up to 36 months (p< 0.01).

Aim: To develop an accurate and reproducible validated digital technique for the two-dimensional measurement of longitudinal femoral stem migration on AP radiographs.

Method: Eight patients who underwent total hip replacement, under the care of the senior author, were randomly selected. In each case, three radio-opaque marker beads had been implanted into the greater trochanteric region at surgery. Using a standardised x-ray protocol, three consecutive AP standing hip x-rays were taken of each patient on the same day. The plain radiographs were digitised, and the vertical bead to stem tip distance measured by two orthopaedic trainees using Scion Image ‘freeware’ software package and standard computer equipment. Every patient had three different measurements on each of their three consecutive x-rays. The vertical bead to stem tip distance was averaged over the three beads.

Results: Statistical analysis was performed and the repeatability coefficient between x-rays was 0.61 (confidence interval 0.46 to 0.78). The limits of agreement for inter observer error for average bead to stem distance were −0.15 to 0.39.

Conclusion: Our results demonstrate the efficacy of our system for analysis of femoral stem migration in everyday clinical practice. This technique does require implantation of marker beads and a standardised protocol for patient positioning for radiographs.

Aim: Hip resurfacing is a bone conserving procedure with respect to proximal femoral resection. For previous generations of conservative hip replacement, preservation of the natural femoral head diameter necessitated additional sacrifice of acetabular bone in order to accommodate a sufficiently thick polyethylene acetabular component. We have investigated whether the BHR offers a bone conserving procedure with respect to the acetabular bone stock.

Method: We reviewed 284 Birmingham resurfacing hip replacements (BHR), and 479, primary hip replacements, in which an uncemented acetabular component (THUA) was used. The BHR and THUA group had mean age at surgery of 55 and 65 years respectively. In 32 BHR’s and 21 THUA, pre-operative templating measurements were available for subsequent comparison with size of component implanted.

Results: Comparison of component sizes, for both implant types, confirmed bi-modal distribution according to patient gender. BHR cups, implanted by the first author, in females, were significantly smaller than those implanted, by the same author, in THUA,(p< 0.0001). Pre-operative templating overestimated component size for all groups but the difference was only significant in male BHR cases;(p=0.03). BHR cups implanted by the first author were significantly smaller than the second author, for both male (p= 0.0001) and female patients;(p< 0.001).

Conclusion: In females, BHR is bone a conserving procedure for femoral and acetabular components. In males, the procedure is not bone sacrificing when compared to THUA. Pre-operative templating can overestimate size of acetabular component that will be used for men. A significant difference was found between size of acetabular components used by two surgeons for BHR.

Introduction: The acetabular cup comprises a 3mm thick bearing surface of UHMPE, a 1.5mm backing of 30% carbon fibre reinforced polybutyleneterephthalate (CFRPBT). Young’s modulus, of CFRPBT layer is similar to natural subchondral bony plate. The cup deforms, when loaded, with the surrounding acetabular bone so that micro-motion at the bone-prosthesis interface is reduced. We measured BMD in the periacetabulum

Method: BMD was analysed for 2 years (n=11 females) with Mean Barthel Index at 2 years 19. Regions of interest were defined according to De-Lee and Charnley (ROI I-III) for the acetabulum. BMD during follow-up was compared with immediate post-operative values. Mean precision error (CV%) was 1.8±0.87%.

Results: By 2 years the mean BMD in HA cup was 0.73gms/cm2 representing a decrease of 7% and 0.78gms/cm2, which representing a 4% decrease with the non-HA cup. With the HA cup at 2 years we measured an increase in ROI I of 3% and a reduction in ROI II and III of 3% and 20% respectively. With the non-HA cup at 2 years we measured an increase in ROI II of 7% and a reduction in ROI I and III of 3% and 16%. There was a significant difference (p< 0.05) in the BMD changes measured in non-weight bearing zone III and one of the weight bearing zones (zone II).

Conclusion: Changes in BMD measured reflect a pattern of maximally reduced stress in zone III followed by zone II and least in the load bearing axis of the acetabulum zone I.

Aim: A prospective study was undertaken to define the pattern of bone remodelling using DXA following implantation of our polished, tri-tapered, collarless, cannulated cemented femoral component.

Method: Our stem was implanted in 20 primary THRs. Our subjects comprised 7 male and 13 female patients. At the time of surgery the mean age was 73 (range 65 to 131). The mean weight at surgery was 75.4kg (range 47kg to 131.8kg) with a mean BMI of 28(range 22 to 40). All patients had a pre operative diagnosis of osteoarthritis. All the hips were implanted via the anterolateral approach. Pre-operative and sequential post-operative DXA evaluations were undertaken at 3 weeks, 6 and 12 months.

Results: The mean precision error was 0.78%(range 0.8–3.4% depending on region of interest). Statistical analysis revealed a significant increase in BMD measured in zones 1,2,4,5,6 (p< 0.05). In zones 3 and 7, the increase in BMD was not significant (p> 0.05). The real percentage increase in BMD at 12 months was 43% in zone 1, 20% in zone 2, 8% in zone 3, 31% in zone 4, 12% in zone 5, 24% in zone 6 and 7% in zone 7.

Conclusion: Peri-prosthetic bone remodelling has been observed within one year following total hip replacement (THR), which has been demonstrated by an increase in BMD in all zones. The implantation of our tri-tapered cannulated cemented femoral component, thus provides favourable proximal femoral loading at 12 months. Additional studies will determine whether stabilization of this bone turnover continues in the long term.

Aim: Analyse the outcome of primary and revision total hip replacement using the Oxford hip score. To determine any variation in outcome when analysing for age of patient. In addition, to compare the outcome in the National Health Service compared to the Private hospital.

Method: We have used the Oxford Hip score to monitor the progress of 1441 primary and 173 revision hip replacements (THR) undertaken since the start of 1995 whose hips have been replaced, at St Helier Hospital, Carshalton and St Anthony’s Hospital, Cheam, over the last seven years. Our review programme was started in early 1999 and has generated 2286 Oxford assessments. ). A subgroup of 634 National Health Service (NHS) and 322 private patients (PP), treated by the senior author, has provided 1277 Oxford assessments.

Results: Mean pre-operative scores were 39.06 and 39.48 for primary and revision THR respectively. The mean annual scores, for primary THR, from 12 to 84 months declined to 21 points at 1 year, 21 at 2 years, 21 at 3 years, 20 at 4 years, 22 at 6 years and 21 at 7 years.

Conclusion: All postoperative reviews show a significant improvement (p≤0.0001). The 50–60 year old group scored significantly better than the over 80 year patients up to 48 months, (p< 0.01) The mean pre-operative score for the NHS patients was significantly higher than the PPs (p< 0.001). The PPs scored significantly better than the NHS group up to 36 months (p< 0.01).