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.


METHODS
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.


CONCLUSIONS
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.
Trauma and Orthopaedic Department, University Hospital Aintree Longmoor Lane, Liverpool, UK.
Katie A
KA
Herman
Alan J
AJ
Highcock
John D
JD
Moorehead
Simon J
SJ
Scott
D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects* / Q000379:methods*; D001696:Biomechanical Phenomena; D005269:Femur / Q000473:pathology; D005270:Femur Head / Q000601:surgery; D005500:Follow-Up Studies; D006621:Hip Joint / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D006622:Hip Prosthesis; D006801:Humans; D007870:Leg Length Inequality / Q000000981:diagnostic imaging / Q000209:etiology* / Q000503:physiopathology; D015588:Observer Variation; D011474:Prosthesis Design; D011859:Radiography; D016896:Treatment Outcome