Introduction
The Bristow procedure was firstly described in 1958 to address recurrent anterior instability with significant glenoid bone loss. This procedure has been widely adopted and modified. Recently arthroscopic Bristow procedures has gained popularity. During the procedure, coracoid fragment is fixed to the glenoid neck via anteroinferior portals (AIP) or pectoralis major portals (PMP).
Purpose
The purpose of this study was to compare the insertion angles of guidewire between through PMP and AIP in modified arthroscopic Bristow procedure.
Materials And Methods
Eight cadaveric shoulders (5 right and 3 left shoulders, 2 men and 3 women) were included. The mean age at death was 90.2 years (84-96 years). Cadavers were placed in beach-chair position, and modified arthroscopic Bristow procedure was performed. Following the osteotomy of the coracoid tip, PMP (7 cm medial and 7 cm distal from the coracoid process) and AIP (5 cm distal from the coracoid process along the conjoint tendon) were created. A guidewire was inserted at the 4 o’clock position and 5 mm medial from the glenoid edge through PMP and AIP. Fluoroscopy was used to define two different angles of guidewires on radiographs: true anteroposterior view of the glenohumeral joint (anterior–posterior tilt of scapula was adjusted for the coracoidal base to be seen as an ellipse), and axial view. The angles between the guidewire and the glenoid articular surface were measured using ImageJ.
Paired t test was used to compare the angles with significance set at p<0.05.
Results
The insertion angles against the glenoid articular surface were significantly smaller in PMP group both in the anteroposterior view (19.5±14.9 degrees in PMP group, and 50.3±8.7 degrees in AIP group) and axial view (16.2±14.3 degrees in PMP group, and 39.5±4.9 degrees in AIP group).
Conclusion
This study clarified that PMP enabled surgeons to insert guidewires in smaller angles against the glenoid articular surface when fixing coracoid fragment. Lower union rate of the coracoid fragment was reported when guidewire was tilted medially more than 25 degrees. In our study, use of PMP allowed surgeons to insert guidewire smaller than 25 degrees in both anteroposterior and axial view. Therefore, in terms of the coracoid fragment union, PMP can be useful in modified arthroscopic Bristow procedure.