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Stabilizing effect of the transferred conjoined tendon on shoulder stability
Lei-Sheng Jiang1, Yi-Min Cui, Zhi-De Zhou
1Department of Orthopedic Surgery, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, 1665 Kongjiang Road, Shanghai 200092, China.
Summary
The conjoined tendon stabilizes the shoulder by reducing humeral head displacement. Transferring it deep to the subscapularis offers the most significant stabilization for shoulder instability.
Area of Science:
- Orthopedic Surgery
- Biomechanics
- Sports Medicine
Background:
- Recurrent anterior glenohumeral instability is a common issue.
- The modified Boytchev procedure, involving conjoined tendon rerouting, is used with debated efficacy.
- The dynamic role of the conjoined tendon in shoulder stability is not fully understood.
Purpose of the Study:
- To investigate the stabilizing effect of the conjoined tendon.
- To compare the effects of the conjoined tendon in situ versus transferred.
- To evaluate its role in both stable and unstable glenohumeral joints.
Main Methods:
- Eight cadaveric shoulders were tested.
- Anterior translation force applied to the proximal humerus.
- Load applied to the conjoined tendon before and after simulated Bankart lesion and modified Boytchev procedure.
Main Results:
- Conjoined tendon loading significantly reduced anterior humeral head displacement.
- The greatest reduction in displacement occurred when the conjoined tendon was transferred deep to the subscapularis.
- This effect was observed in both intact and Bankart-lesioned shoulder models.
Conclusions:
- The conjoined tendon possesses intrinsic stabilizing properties for the shoulder.
- The modified Boytchev procedure, by rerouting the conjoined tendon, provides biomechanical support for recurrent anterior shoulder instability.
- Findings support the clinical use of the modified Boytchev procedure for shoulder instability.
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