title: Using a calliper to restore the centre of the femoral head during total hip replacement.
abstract: Restoration of leg length and offset is an important   goal in total hip replacement. This paper reports a calliper-based technique   to help achieve these goals by restoring the location of the centre   of the femoral head. This was validated first by using a co-ordinate   measuring machine to see how closely the calliper technique could   record and restore the centre of the femoral head when simulating   hip replacement on Sawbone femur, and secondly by using CT in patients   undergoing hip replacement. Results from the co-ordinate measuring machine showed that the   centre of the femoral head was predicted by the calliper to within   4.3 mm for offset (mean 1.6 (95% confidence interval (CI) 0.4 to   2.8)) and 2.4 mm for vertical height (mean -0.6 (95% CI -1.4 to   0.2)).   The CT scans showed that offset and vertical height were restored   to within 8 mm    (mean -1 (95% CI -2.1 to 0.6)) and -14 mm (mean 4 (95% CI 1.8 to   4.3)), respectively. Accurate assessment and restoration of the centre of the femoral   head is feasible with a calliper. It is quick, inexpensive, simple   to use and can be applied to any design of femoral component.
authors.affiliation: Musgrave Park Hospital, Outcomes Assessment Unit, Stockman's Lane, Belfast BT9 7JB, UK. janet.hill@belfasttrust.hscni.net
authors.forename: J C
authors.initials: JC
authors.lastname: Hill
authors.forename: H A P
authors.initials: HA
authors.lastname: Archbold
authors.forename: O J
authors.initials: OJ
authors.lastname: Diamond
authors.forename: J F
authors.initials: JF
authors.lastname: Orr
authors.forename: B
authors.initials: B
authors.lastname: Jaramaz
authors.forename: D E
authors.initials: DE
authors.lastname: Beverland
mesh_terms: D019644:Arthroplasty, Replacement, Hip / Q000379:methods*; D001696:Biomechanical Phenomena; D005270:Femur Head / Q000000981:diagnostic imaging / Q000601:surgery*; D006621:Hip Joint / Q000000981:diagnostic imaging / Q000601:surgery*; D006622:Hip Prosthesis; D006801:Humans; D007870:Leg Length Inequality / Q000000981:diagnostic imaging / Q000601:surgery*; D014057:Tomography, X-Ray Computed