A comparison of leg length and femoral offset discrepancies in hip resurfacing, large head metal-on- metal and conventional total hip replacement: a case series.

BACKGROUND: A discrepancy in leg length and femoral offset restoration is the leading cause of patient dissatisfaction in hip replacement surgery and has profound implications on patient quality of life. The aim of this study is to compare biomechanical hip reconstruction in hip resurfacing, large-diameter femoral head hip arthroplasty and conventional total hip replacement. METHOD: Sixty patient's post-operative radiographs were reviewed; 20 patients had a hip resurfacing (HR), 20 patients had a Large Head Metal-on-metal (LHM) hip replacement and 20 patients had a conventional small head Total Hip Replacement (THR). The leg length and femoral offset of the operated and unoperated hips were measured and compared. RESULTS: Hip resurfacing accurately restored hip biomechanics with no statistical difference in leg length (P = 0.07) or femoral offset (P = 0.95) between the operated and non-operative hips. Overall HR was superior for reducing femoral offset discrepancies where it had the smallest bilateral difference (-0.2%, P = 0.9). The traditional total hip replacement was least effective at restoring the hip anatomy. CONCLUSION: The use of a larger-diameter femoral head in hip resurfacing does not fully account for the superior biomechanical restoration, as LHM did not restore femoral offset as accurately. We conclude that restoration of normal hip biomechanics is best achieved with hip resurfacing.

Kinematic assessment of hip movement when retrieving an object from the floor.

BACKGROUND: Activities that require extreme hip movement can dislocate hip implants in the early post operative phase. One such activity is retrieving an object from the floor. The aim of this study was to assess hip movement using four different techniques to accomplish this task. This assessment would identify the techniques least likely to cause a hip dislocation. METHODS: An electromagnetic tracker was used to measure the movement of 50 hips in 25 normal subjects. Sensors were attached over the iliac crest and the mid-shaft of the lateral thigh. Data was then collected for 3 repetitions of each of the following retrieval techniques:--1. Flexing forward to pick up an object between the feet. 2. Flexing to pick up an object lateral to the foot. 3. Squatting to pick up an object between the feet. 4. Kneeling on one knee to pick up beside the knee. RESULTS: Kneeling required a mean movement of 30.4 degree(s) flexion and 7.2 degree(s) external rotation. This was significantly less than all the other techniques (paired t-test, P << 0.001). Squatting required 87.4 degree(s) flexion and 10.1 degree(s) internal rotation. CONCLUSION: The study showed that squatting had the most flexion and internal rotation, whereas kneeling has the least flexion. Thus, to minimise the dislocation risk when retrieving an object from the floor, kneeling should be adopted and squatting should be avoided.

Concomitant ipsilateral intracapsular and extracapsular femoral neck fracture: a case report.

INTRODUCTION: Intracapsular and extracapsular hip fractures are common amongst elderly patients but simultaneous intracapsular and extracapsular hip fractures are rare. CASE PRESENTATION: We present the case of an elderly woman who sustained simultaneous intracapsular and extracapsular hip fractures and describe the complications which ensued following fixation. CONCLUSION: Concomitant ipsilateral intracapsular and extracapsular femoral neck fracture is an uncommon injury pattern. It occurs most commonly in osteoporotic patients with low energy falls. Close examination of radiographs must be made to ensure that more subtle fractures are not overlooked and the injury managed appropriately. If doubt exists on initial radiographs further imaging should be considered.