Determining optimal length of coracoid graft in the modified Bristow procedure for anterior shoulder instability: A three-dimensional finite element analysis

Article type: Research Article

Authors: Sano, Hirotaka^a; | Komatsuda, Tatsuro^b | Suzuki, Kazuhide^c | Abe, Hiroo^a | Ozawa, Hiroshi^d | Kumagai, Jun^e | Yokobori Jr, Toshimitsu A.^f

Affiliations: [a] Division of Orthopedics, Sendai City Hospital, Sendai, Japan | [b] North Sendai Orthopaedic Clinic, Sendai, Japan | [c] Department of Sports Medicine, Asao General Hospital, Kawasaki, Japan | [d] Department of Orthopaedic Surgery, Tohoku Medical and Pharmaceutical University, Sendai, Japan | [e] Department of Orthopaedic Surgery, Akaishi Hospital, Shiogama, Japan | [f] Laboratory of Strength of Material and Science, Advanced Comprehensive Research Organization, Teikyo University, Tokyo, Japan

Correspondence: [*] Corresponding author: Hirotaka Sano, Division of Orthopedics, Sendai City Hospital, 1-1-1Asuto Nagamachi, Taihaku-ku, Sendai, 982-8502, Japan. Tel.: +81 22 308 7111; Emails: sanohirotaka@med.tohoku.ac.jp, sanohirotaka@gmail.com

Abstract: BACKGROUND:There is a lack of consensus concerning the coracoid graft length in the modified Bristow procedure. OBJECTIVE:We attempted to determine the optimal graft length using the three-dimensional finite element method. METHODS:In a shoulder model with a 25% anterior glenoid defect, a coracoid graft of varying lengths (5, 10, 15, and 20 mm) was fixed using a half-threaded screw. First, a compressive load of 500 N was applied to the screw head to determine the graft failure load during screw tightening. Next, a tensile load (200 N) was applied to the graft to determine the failure load due to biceps muscle traction. RESULTS:In the screw compression, the failure loads in the 5-, 10-, 15-, and 20-mm models were 252, 370, 377, and 331 N, respectively. In the tensile load applied to the coracoid graft, the failure load exceeded 200 N for both the 5- and 10-mm models. CONCLUSION:The 5-mm graft had a high risk of fracture during intraoperative screw tightening. As for the biceps muscle traction, the 5- and 10-mm-grafts had a lower failure risk than the 15- and 20-mm-grafts. Therefore, we believe that the optimal length of the coracoid graft is 10 mm in the modified Bristow procedure.

Keywords: Coracoid graft length, anterior shoulder instability, modified Bristow procedure, failure load, compressive force, tensile stress

DOI: 10.3233/BME-230071

Journal: Bio-Medical Materials and Engineering, vol. 35, no. 1, pp. 65-75, 2024