In 12 patients, we measured the oxygen concentration in the femoral head-neck junction during hip resurfacing through the anterolateral approach. This was compared with previous measurements made for the posterior approach. For the anterolateral approach, the oxygen concentration was found to be highly dependent upon the position of the leg, which was adjusted during surgery to provide exposure to the acetabulum and femoral head. Gross external rotation of the hip gave a significant decrease in oxygenation of the femoral head. Straightening the limb led to recovery in oxygen concentration, indicating that the blood supply was maintained. The oxygen concentration at the end of the procedure was not significantly different from that at the start.

The anterolateral approach appears to produce less disruption to the blood flow in the femoral head-neck junction than the posterior approach for patients undergoing hip resurfacing. This may be reflected subsequently in a lower incidence of fracture of the femoral neck and avascular necrosis.

This study aims to investigate femoral blood flow during Metal-on-Metal Hip Resurfacing (MMHR) by monitoring oxygen concentration during the operative procedure.

Patients undergoing MMHR using the posterior approach were evaluated. Following division of fascia lata, a calibrated gas-measuring electrode was inserted into the femoral neck, aiming for the supero-lateral quadrant of the head. Baseline oxygen concentration levels were detected after electrode insertion 2-3cm below the femoral head surface and all intra-operative measures were referenced against these. Oxygen levels were continuously monitored throughout the operation. Data from ten patients are presented.

Oxygen concentration dropped most noticeably during the surgical approach and was reduced by 62% (Std.dev +/-26%) following dislocation and capsulectomy. Insertion of implants resulted in a further oxygenation decrease by 18% (Std.dev +/-28%). The last obtained measure before wound closure detected 22% (Std.dev +/-31%) of initial baseline oxygen levels. Variation between subjects was observed and three patients demonstrated a limited recovery of oxygen levels during implant insertion and hip relocation.

Intra-operative measurement of oxygen concentration in blood perfusing the femoral head is feasible. Results in ten patients undergoing MMHR showed a dramatic effect on the oxygenation in the femoral head during surgical approach and implant fixation. This may increase the risk of avascular necrosis and subsequent femoral neck fracture. Future experiments will determine if less invasive procedures or specific positioning of the limb can protect the blood supply to femoral neck and head.

Introduction: Avascular necrosis of the femoral head after resurfacing hip replacement is an important complication which may lead to fracture or failure. The surgical approach may affect the blood supply to the femoral head. We compared the changes in femoral head oxygenation resulting from the extended posterior approach to those resulting from the anterolateral approach, the trochanteric flip approach and a modified, soft tissue preserving posterior approach.

Methods: We recruited 48 patients who underwent hip resurfacing arthroplasty (HRA) to measure bone oxygen levels. A calibrated gas-sensitive electrode was inserted in the femoral head following division of the fascia lata. Intra-operative X-ray confirmed correct electrode placement. Base-line oxygen concentration levels were recorded immediately after electrode insertion and continuous measurements were then performed throughout surgery. All results were expressed relative to the baseline, which was considered as 100% relative oxygen concentration and changes during surgery through the posterior approach (n=10), the antero-lateral approach (n=12), the trochanteric flip approach (n=15) and the modified posterior approach (n=11) were compared.

Results: The relative oxygen concentration at the end of the procedure was significantly reduced when hip resurfacing was performed through the posterior (22%, SD 31%, p< 0.005) or a modified posterior (35%, SD 31%, p< 0.005) approach, but recovered in the anterolateral (123%, SD 99%, p=0.6) and trochanteric flip group (89%, SD 62%, p=0.5). Sub-group analysis of these two relatively blood preserving approaches showed that intra-operative oxygen concentration was significantly more consistent during surgery through the trochanteric flip approach (p< 0.02).

Discusssion and conclusion: This study has demonstrated that disruption of blood flow to the femoral head during HRA is dependent on the surgical approach. We therefore believe that blood supply preserving approaches (i.e. anterolateral, trochanteric flip) may be associated with a lower risk of avascular necrosis and femoral neck fracture.

Introduction: Although resurfacing hip replacements are widely used there are few little independent outcome data to support this. The aim of this study was to report the 5 year clinical outcome and 7 year survival of an independent series.

Method: 610 Birmingham hip resurfacings were implanted in 532 patients with an average age of 51.8 years (range 16.5–81.6 years) and were followed for between 2 to 8 years; 120 of this series had minimum five year follow-up. Two patients were lost. There were 23 revisions, giving an overall survival of 95% (95% CI 85–99%) at seven years. Fractured neck of femur (n=13) was the most common reason for revision, followed by aseptic loosening (n=4). There were also 3 patients who had failures that were possibly related to metal debris. At a minimum of 5 year follow-up 93% had excellent or good outcome according to the Harris Hip Score. The mean Oxford Hip Score was 16.1 points (SD 7.7) and the mean UCLA activity score was 6.6 points (SD 1.9). There were no patients with definite evidence of radiographic loosening or greater than 10% of neck narrowing.

Discussion: The results demonstrate that with the Birmingham Hip Resurfacing, implanted using the extended posterior approach, the five year survival is similar or better to the reported survival rates for cemented and hybrid THR’s in young patients.

Conclusions: Considering these patients are young and active these results are good and support the use of resurfacing. However, further study is needed to address the early failures; particularly those related to fracture and metal debris.

Introduction: Avascular necrosis of the femoral head after resurfacing hip replacement is an important complication which may lead to fracture or failure. We compared the changes in femoral head oxygenation resulting from the posterior approach to those resulting from the anterolateral approach and the trochanteric flip approach.

Methods: In 37 patients undergoing hip resurfacing surgery, a calibrated gas-sensitive electrode was inserted superolaterally in the femoral head via the femoral neck following division of the fascia lata. Inter-operative X-ray confirmed correct electrode placement. Baseline oxygen concentration levels were recorded immediately after electrode insertion. All results were expressed relative to this baseline, which was considered as 100% relative oxygen concentration. Oxygen levels were monitored continuously throughout the operation. 10 patients underwent surgery through the posterior approach, 12 patients through the anterolateral approach and 15 through the trochanteric flip approach.

Results: A similar pattern of intra-operative reduction in femoral oxygen concentration was observed for all reviewed approaches. The average change in oxygen concentration during surgery through the trochanteric flip approach was found to be significantly less than through posterior (p< 0.02) and anterolateral (p< 0.02) approaches. Oxygen concentration following joint relocation and soft tissue reconstruction recovered significantly in the anterolateral and trochanteric flip group only. The posterior approach resulted in significantly lower oxygen concentration at the end of the procedure (22%, SD 31) than the anterolateral approach (123%, SD 99; p< 0.05) and the trochanteric flip approach (89%, SD 62, p< 0.02).

Discussion and Conclusion: The anterolateral and trochanteric flip approaches disrupt the femoral head blood supply significantly less than the posterior approach in patients undergoing resurfacing. The most consistent intra-operative oxygen levels were observed during surgery through the trochanteric flip approach. Oxygen concentration during the anterolateral approach was found to be highly dependent upon leg position. The incidence of complications related to avascular necrosis might be decreased by adopting blood supply conserving surgical approaches.

Introduction: Avascular necrosis of the femoral head after resurfacing hip replacement is an important complication which may lead to fracture or failure. We compared the changes in femoral head oxygenation resulting from the anterolateral approach to those resulting from the posterior approach.

Methods: In 22 patients undergoing hip resurfacing surgery, a calibrated gas-sensitive electrode was inserted supero-laterally in the femoral head via the femoral neck following division of the fascia lata. Inter-operative X-ray confirmed correct electrode placement. Baseline oxygen concentration levels were recorded immediately after electrode insertion. All results were expressed relative to this baseline, which was considered as 100% relative oxygen concentration. Oxygen levels were monitored continuously throughout the operation. 10 patients underwent surgery through the posterior approach, 12 patients through the antero-lateral approach.

Results: During the operation patterns were similar for both groups, except following joint relocation and soft tissue reconstruction; oxygen concentration recovered significantly in the anterolateral group only. The posterior approach resulted in significantly lower (p< 0.01) oxygen concentration at the end of the procedure (22%, SD 31) than the antero-lateral approach (123%, SD 99).

Discussion and Conclusion: The anterolateral approach disrupts the femoral head blood supply significantly less than the posterior approach in patients undergoing resurfacing. The incidence of complications related to avascular necrosis might be decreased by adopting blood supply conserving surgical approaches.

Purpose This study aims to investigate blood flow in the femoral head during Metal-on-Metal Hip Resurfacing (MMHR) through the posterior approach by monitoring oxygen concentration during the operative procedure.

Methods Following division of fascia lata, a calibrated gas-measuring electrode was inserted into the femoral neck, aiming for the anterolateral quadrant of the head. Baseline oxygen concentration levels were detected after electrode insertion 2–3cm below the femoral head surface and all intra-operative measures were referenced against these. Oxygen levels were continuously monitored throughout the operation. Results of measurements from ten patients are presented.

Results Oxygen concentration was reduced during the surgical approach and average oxygen concentration following dislocation and circumferential capsulotomy dropped to 43% of baseline (Std.dev +/−37%), this was a highly significant reduction (p< 0.005). Insertion of implants resulted in a further significant drop in oxygen concentration (p< 0.02) to 16% of baseline (Std. dev +/−27%). Oxygen concentration rose slightly after relocation of the resurfaced joint and reconstruction of posterior soft tissues, reaching 22% (Std.dev +/−31%) of initial baseline oxygen levels. Considerable variation between subjects was observed. Three subjects had no remaining oxygen concentration at the end of surgery.

Conclusion Intra-operative measurement of oxygen concentration in blood perfusing the femoral head is feasible. During MMHR there is a dramatic decrease in femoral oxygenation during surgical approach and implant fixation. This may increase the risk of avascular necrosis and subsequent femoral neck fracture. Future experiments will determine if less invasive procedures or a different approach can protect the blood supply to femoral neck and head.

Introduction: The incidence of femoral neck fracture is approximately 2% after resurfacing hip replacement. Avascular necrosis is thought to be a contributory factor. The aim of this study was to investigate oxygen concentration in the femoral head during metal-on-metal hip resurfacing (MMHR).

Materials and Methods: In ten patients, following division of the fascia lata, a calibrated gas-measuring electrode was inserted into the supero-lateral quadrant of the femoral head via the femoral neck. Xsrays confirmed placement of the electrode 2-3 cms below the femoral head surface. Baseline oxygen concentration levels were recorded immediately upon electrode insertion and used as a reference for all intra-operative measures. Oxygen levels were monitored continuously throughout the operation.

Results: Oxygen concentration was reduced during the surgical approach and average oxygen concentration following dislocation and circumferential capsulotomy dropped significantly (p< 0.005) to 38% of baseline (SD=26%). Insertion of implants resulted in a further significant drop in oxygen concentration (p< 0.04) to 21% of baseline (SD=28%). Oxygen concentration rose slightly, but not significantly after relocation of the resurfaced joint and reconstruction of posterior soft tissues, reaching 22% of initial baseline oxygen levels. Considerable variation between subjects was observed.

Discussion: Intra-operative measurement of oxygen concentration in blood perfusing the femoral head is possible. During MMHR there is a dramatic decrease in femoral head oxygenation during surgical approach and implant fixation. This may increase the risk of avascular necrosis and subsequent femoral neck fracture. Future experiments will determine if a different surgical approach can protect the blood supply to the femoral head and neck. Measurements of femoral head oxygenation during metal-on-metal hip resurfacing demonstrated a significant concentration decrease during surgical approach and implant fixation.

Introduction Metal-on-Metal Hip Resurfacing (MMHR) has been established as a successful alternative to Total Hip Replacement (THR). However, several series report a 2 % incidence of early femoral neck fractures. Avascular necrosis (AVN) was considered to be responsible for the majority of observed fractures, raising concerns about the femoral head blood supply during MMHR. This study aims to further understand the mechanisms of femoral blood flow restriction by monitoring gas levels (O2) during the operative procedure.

Methods Patients undergoing MMHR using the posterior approach were evaluated. Following division of fascia lata, a guide wire was introduced up the femoral neck, aiming for the anterosuperior quadrant of the head. It was then removed. A calibrated gas-measuring electrode was inserted in the created bone channel. X-ray confirmation was obtained to ensure that the active measurement area of the electrode was 2–3cm below the femoral surface. O2 and N2O levels were then continuously monitored throughout the operation.

Results A preliminary analysis of four patients is presented: Stable N2O- measurements throughout the procedure confirmed valid electrode measurements. Baseline oxygen concentration levels of 40%– 60% were detected before division of short rotators. After hip dislocation oxygen concentration dropped in all patients to levels ranging between 0% and 5%. Oxygen concentration was found to remain depressed at these levels throughout the entire operation in three patients. Recovery of O2 concentration to baseline levels was observed in one patient 15 minutes after dislocation.

Discussion In three patients the extended posterior approach and joint dislocation had a dramatic effect on the perfusion in the femoral head. These patients have a high risk for development of AVN and potential femoral neck fracture. Whilst the results require further verification, subsequent experiments will determine if less invasive procedures or specific positioning of the limb can protect the femoral blood supply.

Background Recurrent haemarthroses in patients with haemophilia commonly affect the ankles. It can result in haemophilic arthropathy and necessitate arthrodesis. The purpose of this report was to present the results of arthroscopic arthrodesis performed for this condition and to highlight some of the potential difficulties encountered as part of the surgical management. The operative technique is also described.

Method Between January 2001 and May 2004, eight male patients underwent nine arthroscopic arthrodeses. The mean age was 34 years (range 19–44). The patients were identified retrospectively from a surgical database and the radiographs and outpatient notes reviewed. Patients were also contacted to determine their level of satisfaction with the procedure.

Results The mean length of follow-up was 9 months (range 3–18). All patients had united both clinically and radiographically by the time of maximal follow-up and all were satisfied with the result. One patient had minor post-operative bleeding which settled spontaneously. No other significant complications were encountered. Bony cysts were observed in three patients pre-operatively and these all resolved following the attainment of union.

Conclusion Arthroscopic arthrodesis of the ankle is a safe and reliable treatment for haemophilic ankle arthropathy. The union rate is high, the complication rate is low, the risk of disease transmission from patient to staff is lessened and the post-operative rehabilitation regime, including allowing immediate weight bearing is less arduous than with traditional open procedures. Factor requirements are lessened and the length of stay is also reduced compared with open arthrodesis. Collaboration with a haematology unit is essential for a good result to be achieved.