LEG LENGTHENING AFTER TOTAL HIP ARTHROPLASTY. IDENTIFICATION OF PATIENTS AT RISK.

Abstract

Introduction: Leg length discrepancy in general and leg lengthening in particular has emerged as a topic of interest and a common cause for litigation

Theoretical considerations: Painful mobile hip functions in abduction. The load on the hip is reduced by pelvic tilt to the symptomatic side. For this to be possible the proximal lever - the head neck and the acetabulum - must be relatively intact.

Methods: A method to identify patients at risk for limb lengthening after total hip arthroplasty by establishing the aetiology of abduction deformity of the osteoar-thritic hip.

Clinically: by pelvic tilt to the symptomatic side apparent limb lengthening, restriction of adduction.

Radiologically: by a relatively well preserved geometry of the hip and infero-medial femoral “head –drop” osteophyte.

Results: In a group of 5000 patients presenting for primary Charnley low-frictional torque arthroplasty: 182 (3.64%) 80 males, 102 females, mean age 63 (20–80) were identified as being at risk for post-operative limb lengthening.

Aetiology – Primary: Unilateral 130, Bilateral 10.

– Secondary: Post-surgery 23, post-trauma 10, spinal 6, mixed 3.

122 (67%) had apparent limb lengthening – mean 3.2% and in 43 (24%) limb lengths were equal, 91% had a well preserved architecture and the proximal lever system.

Discussion: The tell tale signs in patients at risk for limb lengthening after total hip arthroplasty are: pelvic tilt to the symptomatic side with apparent limb lengthening, restricted adduction, history of backache, well preserved hip structure and normal contralateral hip.

Conclusion: Awareness of the pattern identifying patients at risk, detailed pre-operative assessment, avoidance of capsule excision and tight hip reduction are essential.