title: Does cam osteochondroplasty compromise proximal femur strength?
abstract: Little is known about the effect on load bearing ability of cam-type femurs following osteochondroplasty. The aim of this study was to compare the change in deformation undergone by cam-type femoral acetabular impingement femur models after resection of different volumes. Dry-bone replicas (N = 10) of two cam-type femurs (cam A and B) underwent resections of increasing volume (Surgery I, II and III) representing conservative, adequate and radical resections. Deformation under cyclic loading of 700 N for five cycles after each surgery was compared. The 360° alpha angle and the change in head to neck ratio at four equidistant points along the femoral neck were used as measures of surgical efficacy and volume resected. Intact cam A and B replicas had a maximum alpha angle of 88° and 90°, respectively, which were reduced to 55° and 54° post Surgery I. Cam A replicas showed a significant reduction (p < 0.01) in mean axial displacement after Surgery I (up to 10% reduction in neck volume) and an increase after Surgery III (~20%-40% reduction in neck volume) compared to unresected controls (p < 0.01). Surgery II (~10%-15% reduction in neck volume) produced no significant change in mean displacement (p > 0.05). Cam B models exhibited lower mean displacement after Surgery I, II and III (p < 0.01) compared to unresected controls. Conservative surgery appears to improve the axial load bearing ability of dry-bone models. Radical resections may significantly decrease the fracture-resistant properties of bone following osteochondroplasty which should be noted when planning such a procedure.
authors.affiliation: Imperial College School of Medicine, Imperial College London, London, UK cn2509@ic.ac.uk.
authors.forename: Chandni
authors.initials: C
authors.lastname: Nigam
authors.affiliation: MSK Lab, Department of Orthopaedics, Imperial College London, Charing Cross Hospital, London, UK.
authors.forename: Milad
authors.initials: M
authors.lastname: Masjedi
authors.affiliation: MSK Lab, Department of Orthopaedics, Imperial College London, Charing Cross Hospital, London, UK.
authors.forename: James
authors.initials: J
authors.lastname: Houston
authors.affiliation: MSK Lab, Department of Orthopaedics, Imperial College London, Charing Cross Hospital, London, UK.
authors.forename: Charles
authors.initials: C
authors.lastname: Marquardt
authors.affiliation: MSK Lab, Department of Orthopaedics, Imperial College London, Charing Cross Hospital, London, UK.
authors.forename: Adeel
authors.initials: A
authors.lastname: Aqil
authors.affiliation: MSK Lab, Department of Orthopaedics, Imperial College London, Charing Cross Hospital, London, UK.
authors.forename: Justin
authors.initials: J
authors.lastname: Cobb
mesh_terms: D019245:Compressive Strength; D057925:Femoracetabular Impingement / Q000503:physiopathology* / Q000601:surgery*; D005269:Femur / Q000503:physiopathology* / Q000601:surgery*; D006801:Humans; D016896:Treatment Outcome; D016474:Weight-Bearing
keywords: Cam femoral acetabular impingement; alpha angle; femoral strength; fracture risk; head–neck ratio; osteochondroplasty; resection volume