Does the killer turn angle in biceps tenodesis lead to a guillotine effect? A biomechanical study
JOURNAL OF ORTHOPAEDIC SURGERY AND RESEARCH, cilt.21, sa.1, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 21 Sayı: 1
- Basım Tarihi: 2026
- Doi Numarası: 10.1186/s13018-026-07007-8
- Dergi Adı: JOURNAL OF ORTHOPAEDIC SURGERY AND RESEARCH
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, CINAHL, EMBASE, MEDLINE, Directory of Open Access Journals, Academic Search Ultimate (EBSCO), Biomedical Reference Collection: Corporate Edition (EBSCO), Health Research Premium Collection (ProQuest)
- Dokuz Eylül Üniversitesi Adresli: Evet
Özet
Purpose The purpose of this study was to investigate whether a killer turn angle in biceps tenodesis creates a guillotine-like effect under physiological loading conditions and to evaluate its influence on tendon elongation and tunnel widening.Methods 30 fresh ovine humeri underwent biceps tenodesis using a bicortical endobutton technique. Specimens were divided into three groups according to the bone-tendon angle at the tunnel entrance (45 degrees, 60 degrees, and 90 degrees). Each construct was subjected to 500 cyclic loading cycles between 0 and 150 N. Tendon elongation and tunnel widening were measured and compared among groups.Results No tendon rupture or construct failure was observed in any group. Tendon elongation and residual creep were significantly greater in the 90 degrees group compared with the 45 degrees and 60 degrees groups (p = 0.001), whereas no significant difference was found between the 45 degrees and 60 degrees angles (p = 0.247). Tunnel widening did not differ significantly among groups, although a trend toward increased enlargement with higher angles was noted.Conclusions Sharp bone-tendon angulation increased tendon elongation during cyclic loading, suggesting the presence of a guillotine-like mechanical effect in biceps tenodesis. Reducing the killer turn angle to 60 degrees or less appeared sufficient to mitigate this effect. Although no acute failure was observed, these findings highlight the potential relevance of the guillotine effect in shoulder surgery and underscore the importance of considering the killer turn angle, particularly in tendon transfer procedures with higher reported failure rates.Level of evidence Level V, biomechanical study.