The Cuistow: A Modified Arthroscopic Bristow Procedure for the Treatment of Recurrent Anterior Shoulder Instability.

Abstract

The rate of nonunion observed among the variety of Bristow-Latarjet procedures reportedly ranges from 9.4% to 28%¹. In Chinese timber buildings, the mortise-tenon joint is commonly utilized to connect beams to columns. Drawing inspirations from this concept, we created a bone trough in the glenoid neck to serve as a mortise and trimmed the coracoid graft to serve as a tenon, then fixed this mortise-tenon joint with a metal screw. Compared with a standard Bristow-Latarjet procedure, the key feature of this technique was that the coracoid process was placed into a trough (5 to 10 mm deep) in the glenoid neck, which substantially increased the bone contact area between the graft and glenoid neck. We called this surgical technique the Chinese unique inlay Bristow (Cuistow).

Description: Specific instruments have been designed to improve the safety and accuracy of the arthroscopic inlay Bristow procedure (Weigao, Shangdong, China). The posterior portal (A), superolateral portal (B), and 3 anterior portals (i.e., proximal [C], inferolateral [D], and inferomedial [E]) were utilized. General anesthesia and an interscalene block were administered with the patient in the beach-chair position. The surgical technique can be divided into 6 steps: (1) evaluation of the shoulder joint; (2) coracoid preparation, drilling, and osteotomy; (3) subscapularis splitting and labrum detachment; (4) glenoid preparation and drilling; (5) coracoid retrieval, trimming, transfer, and fixation; and (6) Bankart repair.

Alternatives: Soft-tissue capsulolabral repairs or bone reconstruction procedures are commonly performed for the treatment of anterior glenohumeral instability². The arthroscopic Bristow-Latarjet procedure is increasingly popular for the treatment of anterior shoulder instability with a substantial osseous defect of the glenoid³. Defects that are too large to be restored with the coracoid process can be treated with use of the Eden-Hybbinette procedure or a distal tibial allograft^4,5.

Rationale: This procedure was inspired by the structure of mortise-tenon joints, resulting in a modified version of the Bristow-Latarjet technique in which the coracoid process is trimmed and placed into a trough (5 to 10 mm deep) in the glenoid neck. This procedure substantially increases the contact area between the fresh bone surface and the coracoid and glenoid neck. Another important advantage of this technique is that it can facilitate accurate positioning of the coracoid on the glenoid. This procedure resulted in a high rate of graft healing, excellent functional outcomes (Rowe and American Shoulder and Elbow Surgeons Shoulder scores), and a high rate of return to sport⁶. Currently, indications of this procedure are (1) participation in high-demand sports (i.e., collision and overhead) combined with the presence of a glenoid defect involving <25% of the glenoid, or (2) any glenoid defect involving 10% to 25% of the glenoid.

Expected outcomes: Increased bone-contact area and accurate positioning of the graft helped to facilitate osseous union, with a union rate of 96.1% at 12 months postoperatively. The clinical outcomes were excellent, with a high rate of return to sport (87%) at a minimum of 3 years of follow-up⁶.

Important tips: When the coracoid is retrieved through portal D (the inferolateral portal), there is a risk of stretching the musculocutaneous nerve.Trimming the coracoid graft could lead to stretching of the graft and the surrounding soft tissue, resulting in overstretching of the musculocutaneous nerve.To minimize the risk of musculocutaneous nerve injury, (1) the graft should be gently retrieved through portal D, (2) the graft should be trimmed with caution without overstretching it and surrounding soft tissue, and (3) a cannula should be utilized when driving the screw to fix the graft in order to avoid the surrounding soft tissue.

Acronyms & abbreviations: RHD = right-hand dominantMRA = magnetic resonance angiography3D-CT = 3-dimensional computed tomographyPDS = polydioxanone sutureMCN = musculocutaneous nerve.