title: Perception of imposed leg length inequality in normal subjects.
abstract: Lower limb length differences of up to 10mm exist in 60% - 95% of the population.There are usually no symptoms or functional effects. Following Total Hip Arthroplasty (THA), satisfactory clinical results can be spoiled by dissatisfaction due to a change in leg length. Although the change in leg length may be modest in comparison to the normal variation, the patient may perceive this as a leg length discrepancy. To study the average threshold for perception, artificial leg length discrepancies of 5 mm to 25 mm were created in 30 young healthy adults using calibrated wooden blocks. Responses were recorded and analysed using a chi-squared test for independence and an independent measures t-test. Awareness of leg length discrepancy was related to the magnitude of the discrepancy (X2 (15)= 156.6, p<0.05 on the right side, and X2 (15)= 178.725 p<0.05 on the left side). It was shown that no subject reported a 5mm increase in leg length to be uncomfortable while all subjects were aware of leg length discrepancies of 20 mm and 25 mm. When there was a discrepancy of 10 mm in either lower limb, 29 out of 30 subjects (96.7%) thought there was a difference in leg length. Consequently it is suggested that during total hip arthroplasty the surgeon should aim for a leg length discrepancy of less than 10 mm.
authors.affiliation: Outcomes Assessment Unit, Musgrave Park Hospital, Stockman's Lane, Belfast, Northern Ireland. seamus.obrien@belfasttrust.hscni.net
authors.forename: Seamus
authors.initials: S
authors.lastname: O'Brien
authors.forename: George
authors.initials: G
authors.lastname: Kernohan
authors.forename: Claire
authors.initials: C
authors.lastname: Fitzpatrick
authors.forename: Janet
authors.initials: J
authors.lastname: Hill
authors.forename: David
authors.initials: D
authors.lastname: Beverland
mesh_terms: D000293:Adolescent; D000328:Adult; D019644:Arthroplasty, Replacement, Hip; D001828:Body Image; D005260:Female; D006801:Humans; D007870:Leg Length Inequality / Q000523:psychology*; D008297:Male; D012649:Self Concept; D055815:Young Adult