Louis Dagneaux1, Hamid Rahmatullah Bin Abd Razak2, Pierre Laumonerie3, Ahmad Faizhan4, Sally LiArno4, Peter Wellings4, Matthieu Ollivier5, Christophe Jacquet5. 1. Department of Orthopaedic Surgery, Lapeyronie University Hospital, Montpellier University, 371 Av du Doyen Gaston Giraud, 34295, Montpellier Cedex 5, France. louisdagneaux@gmail.com. 2. SingHealth Duke-NUS Musculoskeletal Sciences Academic Clinical Programme, 20 College Road, Academia Level 4, Singapore, 169865, Singapore. 3. Department of Orthopedic Surgery, Hôpital Pierre-Paul Riquet, Place du Docteur Baylac, 31059, Toulouse, France. 4. Stryker, Mahwah, NJ, USA. 5. Department of Orthopedics and Traumatology, St. Marguerite Hospital, Aix Marseille University, APHM, CNRS, ISM, Institute of Movement and Locomotion, 270 Boulevard Sainte Marguerite, BP 29, 13274, Marseille, France.
Abstract
PURPOSE: Previous investigations suggested that femoral side-to-side differences were located in the upper femur anatomy. However, little is known about the asymmetry between distal femur and patella. The degree of bony asymmetry in the patellofemoral joint was evaluated using pairs of CT-scans with emphasis on morphometric measurements and risk factors relevant to patellofemoral disorders. METHODS: Patellofemoral morphometric parameters and anatomical risk factors were analyzed from 345 pairs of CT scans to evaluate side-to-side differences for each patient. All measurements were automatized using previously published algorithm-calculated bone landmarks. We analyzed asymmetry based on absolute differences (AD) and percentage asymmetry (AS%). Significant asymmetry was defined as AS% > 10%. RESULTS: Patellar height was found to be highly symmetric (mean AD 0.1 for both Insall-Salvatti and Caton-Deschamps methods, AS% 8% and 9%, respectively). Patellar and femoral morphometric parameters were found highly symmetric, except for the trochlear groove depth. Substantial asymmetry was reported in two patellofemoral risk factors: the lateral trochlear inclination (mean AD 2°, AS% 16%) and the tibial tuberosity-trochlear groove distance (1 mm, 116%). Patellar and femoral morphometric asymmetries were independent of demographics, including age, gender, height, weight and ethnicity. CONCLUSION: Patellar height was found to be highly symmetric and is, therefore, a reasonable index for contralateral templating. While very few patellofemoral morphometric parameters and anatomical risk factors were asymmetric, the mean differences were clinically negligible and independent of demographics. LEVEL OF EVIDENCE: III.
PURPOSE: Previous investigations suggested that femoral side-to-side differences were located in the upper femur anatomy. However, little is known about the asymmetry between distal femur and patella. The degree of bony asymmetry in the patellofemoral joint was evaluated using pairs of CT-scans with emphasis on morphometric measurements and risk factors relevant to patellofemoral disorders. METHODS: Patellofemoral morphometric parameters and anatomical risk factors were analyzed from 345 pairs of CT scans to evaluate side-to-side differences for each patient. All measurements were automatized using previously published algorithm-calculated bone landmarks. We analyzed asymmetry based on absolute differences (AD) and percentage asymmetry (AS%). Significant asymmetry was defined as AS% > 10%. RESULTS: Patellar height was found to be highly symmetric (mean AD 0.1 for both Insall-Salvatti and Caton-Deschamps methods, AS% 8% and 9%, respectively). Patellar and femoral morphometric parameters were found highly symmetric, except for the trochlear groove depth. Substantial asymmetry was reported in two patellofemoral risk factors: the lateral trochlear inclination (mean AD 2°, AS% 16%) and the tibial tuberosity-trochlear groove distance (1 mm, 116%). Patellar and femoral morphometric asymmetries were independent of demographics, including age, gender, height, weight and ethnicity. CONCLUSION: Patellar height was found to be highly symmetric and is, therefore, a reasonable index for contralateral templating. While very few patellofemoral morphometric parameters and anatomical risk factors were asymmetric, the mean differences were clinically negligible and independent of demographics. LEVEL OF EVIDENCE: III.