Christopher R Adams1, Brendan Comer2, Bastian Scheiderer3, Florian B Imhoff4, Daichi Morikawa5, Cameron Kia6, Lukas N Muench7, Joshua B Baldino2, Augustus D Mazzocca2. 1. Department of Orthopaedic Surgery, Naples Community Hospital, Naples Florida, U.S.A. 2. Department of Orthopaedic Surgery, University of Connecticut, Farmington, Connecticut, U.S.A. 3. Department of Orthopaedic Sportsmedicine, Technical University, Munich, Germany. 4. Department of Orthopaedic Surgery, University Hospital Balgrist, Zurich, Switzerland. 5. Department of Orthopaedic Surgery, Juntendo University, Tokyo, Japan. 6. Department of Orthopaedic Surgery, University of Connecticut, Farmington, Connecticut, U.S.A. Electronic address: ckia@uchc.edu. 7. Department of Orthopaedic Surgery, University of Connecticut, Farmington, Connecticut, U.S.A; Department of Orthopaedic Sportsmedicine, Technical University, Munich, Germany.
Abstract
PURPOSE: To evaluate the effect of dermal allograft fixation at different angles of glenohumeral abduction on deltoid forces during superior capsule reconstruction (SCR). METHODS: Fifteen cadaveric specimens were tested using a dynamic shoulder simulator. Following testing in the native state, shoulders underwent SCR in 2 of 5 possible fixation angles; 0°, 15°, 30°, 45°, or 60° of glenohumeral abduction, allowing for 6 specimens per group. Angles were measured radiographically with the glenoid fixed perpendicular to the floor. Maximum mean deltoid abduction force was compared among 5 separate conditions within each angle group: (1) native shoulder, (2) complete supraspinatus (SSP) and superior capsule tear, (3) SCR alone, (4) SCR with posterior margin sutured, and (5) SCR with anterior and posterior margins sutured. RESULTS: SSP tears significantly increased the maximum deltoid forces for all 5 fixation angles compared with the native state (P < .05). Specimens repaired at 0°, 30°, and 45° were unable to restore deltoid forces compared with the native state in any condition (P < .05). SCR at 15° with anterior and posterior margin convergence showed similar abduction forces compared with the native state (P = .19). When fixed at 60° abduction, SCR alone significantly reduced deltoid forces compared to SSP (Δ143N, P < .001) and native (Δ48N, P < .001). No significant differences were found between the 3 repair subtypes (SCR ± anterior/posterior margin repair) in the 60° group. CONCLUSIONS: SCR with anterior and posterior margin convergence tensioned at 15° of glenohumeral abduction showed similar deltoid abduction force requirements compared with the native state, whereas graft fixation in 60° significantly reduced deltoid force in all SCR conditions. CLINICAL RELEVANCE: Increased graft tension with a greater abduction angle may provide greater functional outcome by placing less load on the deltoid. In contrast, graft fixation in lower abduction angles may require additional margin convergence to reproduce native forces.
PURPOSE: To evaluate the effect of dermal allograft fixation at different angles of glenohumeral abduction on deltoid forces during superior capsule reconstruction (SCR). METHODS: Fifteen cadaveric specimens were tested using a dynamic shoulder simulator. Following testing in the native state, shoulders underwent SCR in 2 of 5 possible fixation angles; 0°, 15°, 30°, 45°, or 60° of glenohumeral abduction, allowing for 6 specimens per group. Angles were measured radiographically with the glenoid fixed perpendicular to the floor. Maximum mean deltoid abduction force was compared among 5 separate conditions within each angle group: (1) native shoulder, (2) complete supraspinatus (SSP) and superior capsule tear, (3) SCR alone, (4) SCR with posterior margin sutured, and (5) SCR with anterior and posterior margins sutured. RESULTS: SSP tears significantly increased the maximum deltoid forces for all 5 fixation angles compared with the native state (P < .05). Specimens repaired at 0°, 30°, and 45° were unable to restore deltoid forces compared with the native state in any condition (P < .05). SCR at 15° with anterior and posterior margin convergence showed similar abduction forces compared with the native state (P = .19). When fixed at 60° abduction, SCR alone significantly reduced deltoid forces compared to SSP (Δ143N, P < .001) and native (Δ48N, P < .001). No significant differences were found between the 3 repair subtypes (SCR ± anterior/posterior margin repair) in the 60° group. CONCLUSIONS: SCR with anterior and posterior margin convergence tensioned at 15° of glenohumeral abduction showed similar deltoid abduction force requirements compared with the native state, whereas graft fixation in 60° significantly reduced deltoid force in all SCR conditions. CLINICAL RELEVANCE: Increased graft tension with a greater abduction angle may provide greater functional outcome by placing less load on the deltoid. In contrast, graft fixation in lower abduction angles may require additional margin convergence to reproduce native forces.
Authors: Felix Dyrna; Daniel P Berthold; Lukas N Muench; Knut Beitzel; Cameron Kia; Elifho Obopilwe; Leo Pauzenberger; Christopher R Adams; Mark P Cote; Bastian Scheiderer; Augustus D Mazzocca Journal: Orthop J Sports Med Date: 2020-10-06