Michael Cohn1, Sergio A Glait2, Anthony Sapienza1, Young W Kwon1. 1. Department of Orthopaedic Surgery, NYU Hospital for Joint Diseases, New York, NY. 2. Department of Orthopaedic Surgery, NYU Hospital for Joint Diseases, New York, NY. Electronic address: sergio.glait@nyumc.org.
Abstract
PURPOSE: To determine the radial head arthroplasty length that best replicates the native radiocapitellar contact pressure. METHODS: Eight cadaveric elbows (4 matched pairs) with an average age of 73 years were tested. All specimens were ligamentously stable and without visible cartilage wear. Radiocapitellar contact pressures were digitally analyzed during simulated joint loading at 0°, 45°, and 90° of elbow flexion and neutral rotation in the intact specimens and after ligament-preserving radial head arthroplasty at -2 mm, 0 mm, and +2 mm of the native length. The results were analyzed using 1-way analysis of variance and post hoc Tukey pairwise comparison tests. RESULTS: Paired analysis demonstrated significantly decreased mean contact pressures when comparing the native versus the minus 2 groups. Significantly decreased maximum contact pressures were also noted between the native and the minus 2 groups. Examining the mean contact pressures showed no significant difference between the native and the zero group and the native and the plus 2 groups. As for the maximum contact pressures, there was also no significant difference between the native and the zero group and the native and the plus 2 group. CONCLUSIONS: Up to 2 mm of overlengthening may be tolerated under simulated loading conditions without significantly increasing contact pressures of the radiocapitellar joint. Surgeons can use this knowledge along with radiographic parameters and intraoperative examination of elbow stability to gauge the appropriate size of the radial head implant to be used in order to decrease the risk of overstuffing the joint and minimizing radiocapitellar chondral wear. TYPE OF STUDY/LEVEL OF EVIDENCE: Prognostic IV.
PURPOSE: To determine the radial head arthroplasty length that best replicates the native radiocapitellar contact pressure. METHODS: Eight cadaveric elbows (4 matched pairs) with an average age of 73 years were tested. All specimens were ligamentously stable and without visible cartilage wear. Radiocapitellar contact pressures were digitally analyzed during simulated joint loading at 0°, 45°, and 90° of elbow flexion and neutral rotation in the intact specimens and after ligament-preserving radial head arthroplasty at -2 mm, 0 mm, and +2 mm of the native length. The results were analyzed using 1-way analysis of variance and post hoc Tukey pairwise comparison tests. RESULTS: Paired analysis demonstrated significantly decreased mean contact pressures when comparing the native versus the minus 2 groups. Significantly decreased maximum contact pressures were also noted between the native and the minus 2 groups. Examining the mean contact pressures showed no significant difference between the native and the zero group and the native and the plus 2 groups. As for the maximum contact pressures, there was also no significant difference between the native and the zero group and the native and the plus 2 group. CONCLUSIONS: Up to 2 mm of overlengthening may be tolerated under simulated loading conditions without significantly increasing contact pressures of the radiocapitellar joint. Surgeons can use this knowledge along with radiographic parameters and intraoperative examination of elbow stability to gauge the appropriate size of the radial head implant to be used in order to decrease the risk of overstuffing the joint and minimizing radiocapitellar chondral wear. TYPE OF STUDY/LEVEL OF EVIDENCE: Prognostic IV.