Paolo Arrigoni1,2, Davide Cucchi3, Francesco Luceri1, Alessandra Menon1,2, Carlo Zaolino1,2, Andrea Zagarella4, Michele Catapano4, Mattia Radici5, Nicola Migliaccio5, Dario Polli6, Pietro S Randelli1,2,7. 1. UOC 1° Clinica Ortopedica, ASST Centro Specialistico Ortopedico Traumatologico Gaetano Pini-CTO, Milan, Italy. 2. Laboratory of Applied Biomechanics, Department of Biomedical Sciences for Health, Università degli Studi di Milano, Milan, Italy. 3. Department of Orthopaedics and Trauma Surgery, Universitätsklinikum Bonn, Bonn, Germany. 4. UOC Radiodiagnostica, ASST Centro Specialistico Ortopedico Traumatologico Gaetano Pini-CTO, Milan, Italy. 5. Università degli Studi di Milano, Milan, Italy. 6. Physics Department, Politecnico di Milano, Milan, Italy. 7. Research Center for Adult and Pediatric Rheumatic Diseases, Department of Biomedical Sciences for Health, Università degli Studi di Milano, Milan, Italy.
Abstract
BACKGROUND: An elongation of the radial lateral collateral complex (R-LCL) can provoke symptomatic minor instability of the lateral elbow leading to lateral elbow pain. Biomechanical models investigating the effects of elongation and partial or complete lesions of the R-LCL on lateral elbow stability are lacking. PURPOSE: To evaluate how partial and complete R-LCL release affects radiocapitellar joint stability in a setting of controlled varus load and progressive soft tissue release. STUDY DESIGN: Controlled laboratory study. METHODS: Ten fresh-frozen cadaveric specimens were obtained and mounted on a custom-made support to control elbow flexion and extension and to allow for controlled varus loading. Stress tests were performed on all intact specimens under gravity load alone, a 0.5-kg load applied to the hand, and a 1-kg load applied to the hand. After load application, anteroposterior radiographs were obtained. The following release sequence was applied to all specimens: release of the anterior half of the common extensor origin, pie crusting of the R-LCL, and R-LCL release. After each release, stress tests and radiographs were performed. The varus joint angulation of the elbow (α) was measured by 2 examiners as the main outcome parameter. RESULTS: Significant changes in α from the initial condition occurred after each release, and a significant effect of varus load on α was documented for all release steps. A significant effect of the releases on α could be documented for all identical varus load conditions. A linear regression model was generated to describe the effect of varus load on α. CONCLUSION: Varus loads simulating everyday activities produce changes in the varus joint angulation of the elbow already in the intact specimen, which are linearly dependent on the applied moment and persist after release of the lateral stabilizing structures. With progressive load, a pie crusting of the R-LCL is the minimal procedure able to provoke a significant change in the varus joint angulation, and a complete R-LCL release produces additional increase in the varus joint angulation in all testing conditions. CLINICAL RELEVANCE: These findings confirm the role of the R-LCL as static lateral stabilizer, supporting a pathological model based on its insufficiency and culminating with a symptomatic minor instability of the lateral elbow.
BACKGROUND: An elongation of the radial lateral collateral complex (R-LCL) can provoke symptomatic minor instability of the lateral elbow leading to lateral elbow pain. Biomechanical models investigating the effects of elongation and partial or complete lesions of the R-LCL on lateral elbow stability are lacking. PURPOSE: To evaluate how partial and complete R-LCL release affects radiocapitellar joint stability in a setting of controlled varus load and progressive soft tissue release. STUDY DESIGN: Controlled laboratory study. METHODS: Ten fresh-frozen cadaveric specimens were obtained and mounted on a custom-made support to control elbow flexion and extension and to allow for controlled varus loading. Stress tests were performed on all intact specimens under gravity load alone, a 0.5-kg load applied to the hand, and a 1-kg load applied to the hand. After load application, anteroposterior radiographs were obtained. The following release sequence was applied to all specimens: release of the anterior half of the common extensor origin, pie crusting of the R-LCL, and R-LCL release. After each release, stress tests and radiographs were performed. The varus joint angulation of the elbow (α) was measured by 2 examiners as the main outcome parameter. RESULTS: Significant changes in α from the initial condition occurred after each release, and a significant effect of varus load on α was documented for all release steps. A significant effect of the releases on α could be documented for all identical varus load conditions. A linear regression model was generated to describe the effect of varus load on α. CONCLUSION: Varus loads simulating everyday activities produce changes in the varus joint angulation of the elbow already in the intact specimen, which are linearly dependent on the applied moment and persist after release of the lateral stabilizing structures. With progressive load, a pie crusting of the R-LCL is the minimal procedure able to provoke a significant change in the varus joint angulation, and a complete R-LCL release produces additional increase in the varus joint angulation in all testing conditions. CLINICAL RELEVANCE: These findings confirm the role of the R-LCL as static lateral stabilizer, supporting a pathological model based on its insufficiency and culminating with a symptomatic minor instability of the lateral elbow.