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    New Technique Uses the Principles of Mortise and Tenon Joints for Repair of Unstable Shoulders

    Surgical techniques to treat recurrent shoulder instability are effective but prone to non-union of bone grafts held in place by screws alone. A study published online by The Journal of Bone & Joint Surgery suggests that a new technique – borrowing a design used for centuries in Chinese architecture and woodworking – can provide an effective approach to shoulder stabilization.

    Inspired by the ancient woodworking technique of mortise and tenon joints, the arthroscopic inlay Bristow procedure is reported to have a high success rate in patients with recurrent shoulder instability. The technique “optimized the accuracy of graft positioning and resulted in a high rate of graft healing, excellent functional outcomes, and a high return to sports,” according to the study from Peking University Third Hospital in China.

    Recurrent anterior shoulder instability is a common problem among athletes, particularly those involved in collision or overhead sports, who may undergo a surgical procedure such as an arthroscopic Bristow-Latarjet procedure to stabilize the joint. With the Bristow-Latarjet technique, a small “hook” of bone (ie, the coracoid) is taken from the scapula and fixed with a screw to the glenoid bone, providing long-term anterior shoulder stability. This procedure has a good success rate in terms of preventing future shoulder dislocations.

    However, problems can occur if the graft does not heal properly, resulting in non-union. This can lead to bone deterioration and displacement or breakage of the screw, potentially causing recurrent instability.

    In their search for a way to create greater stability for the shoulder repair, the study authors considered the mortise and tenon joint technique commonly used in carpentry and woodworking. A projecting piece of wood (the tenon) is crafted to precisely fit into a gap (the mortise) in another piece of wood, thus joining the 2 pieces together.

    Their new inlay Bristow technique borrows the principles of the mortise and tenon joint: The coracoid graft is trimmed to form a tenon, which is fixed into a mortise created in the glenoid bone.

    The study published online by The Journal of Bone & Joint Surgery reports the results of 51 patients who had undergone the new arthroscopic inlay Bristow procedure for recurrent anterior shoulder instability. One year after the procedure, 96% of patients have experienced healing of the coracoid bone graft, with non-union in only 2 patients. Follow-up CT scans show good graft positioning with little or no sign of bone degeneration.

    Patients also exhibited better function with the inlay Bristow procedure, with significant improvements in shoulder stability (Rowe score) and overall joint function (American Shoulder and Elbow Surgeons score) at a minimum follow-up of 3 years. Eighty-seven percent of patients were able to return to sport.

    Inspired by traditional Chinese architecture, the arthroscopic inlay Bristow procedure provides a promising reconstructive approach in patients with recurrent shoulder instability. The inherent strength of the mortise and tenon joint increases the contact area and proper positioning of the bone graft, with high rates of bone healing and union and good clinical outcomes.

    The authors said that further studies will be needed to confirm the reliability of the procedure and to compare the outcomes of the procedure with other treatments for recurrent shoulder instability.

    Source

    Lin L, Zhang M, Song Q, et al. Cuistow: Chinese unique inlay Bristow. A novel arthroscopic surgical procedure for treatment of recurrent anterior shoulder instability with a minimum 3-year follow-up. J Bone Joint Surg Am. 2020 Nov 10. doi: 10.2106/JBJS.20.00382. Published online ahead of print.