title: Pelvic position and movement during hip replacement.
abstract: The orientation of the acetabular component is influenced not only by the orientation at which the surgeon implants the component, but also the orientation of the pelvis at the time of implantation. Hence, the orientation of the pelvis at set-up and its movement during the operation, are important. During 67 hip replacements, using a validated photogrammetric technique, we measured how three surgeons orientated the patient's pelvis, how much the pelvis moved during surgery, and what effect these had on the final orientation of the acetabular component. Pelvic orientation at set-up, varied widely (mean (± 2, standard deviation (sd))): tilt 8° (2sd ± 32), obliquity -4° (2sd ± 12), rotation -8° (2sd ± 14). Significant differences in pelvic positioning were detected between surgeons (p < 0.001). The mean angular movement of the pelvis between set-up and component implantation was 9° (sd 6). Factors influencing pelvic movement included surgeon, approach (posterior > lateral), procedure (hip resurfacing > total hip replacement) and type of support (p < 0.001). Although, on average, surgeons achieved their desired acetabular component orientation, there was considerable variability (2sd ± 16) in component orientation. We conclude that inconsistency in positioning the patient at set-up and movement of the pelvis during the operation account for much of the variation in acetabular component orientation. Improved methods of positioning and holding the pelvis are required.
authors.affiliation: University of Oxford, NDORMS, Windmill Road, Headington, Oxford, OX3 7LD, UK.
authors.forename: G
authors.initials: G
authors.lastname: Grammatopoulos
authors.affiliation: University of Oxford, NDORMS, Windmill Road, Headington, Oxford, OX3 7LD, UK.
authors.forename: H G
authors.initials: HG
authors.lastname: Pandit
authors.affiliation: Western Sussex Hospitals NHS Foundation Trust, Lyndhurst Rd, Worthing BN11 2DH, UK.
authors.forename: R
authors.initials: R
authors.lastname: da Assunção
authors.affiliation: Oxford University Hospitals, Nuffield Orthopaedic Centre, Windmill Road, Headington, OX3 7LD, UK.
authors.forename: A
authors.initials: A
authors.lastname: Taylor
authors.affiliation: Oxford University Hospitals, Nuffield Orthopaedic Centre, Windmill Road, Headington, OX3 7LD, UK.
authors.forename: P
authors.initials: P
authors.lastname: McLardy-Smith
authors.affiliation: ANCA Clinic, Xavier de Cocklaan 68/1, 9831 Sint-Martens-Latem, Deurle, Belgium.
authors.forename: K A
authors.initials: KA
authors.lastname: De Smet
authors.affiliation: University of Oxford, NDORMS, Windmill Road, Headington, Oxford, OX3 7LD, UK.
authors.forename: D W
authors.initials: DW
authors.lastname: Murray
authors.affiliation: University of Bath, Dept of Mechanical Engineering, Claverton Down, Bath BA2 7AY, UK.
authors.forename: H S
authors.initials: HS
authors.lastname: Gill
mesh_terms: D000077:Acetabulum / Q000502:physiology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000379:methods / Q000592:standards; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D056888:Patient Positioning; D010388:Pelvis / Q000502:physiology; D010780:Photogrammetry; D011446:Prospective Studies; D012399:Rotation
keywords: Hip arthroplasty; Movement; Orientation; Pelvis