Review Question - QID 214081

This patient has recurrent shoulder dislocations with significant glenoid bone loss on CT imaging indicating the need for a bony augmentation procedure (ie. Latarjet). His postoperative examination reveals a musculocutaneous neuropraxia.

This patient sustained an initial traumatic shoulder dislocation at the age of 17-years. The recurrence rate for patients <20-years is >90%. In addition to the recurrent dislocations, this patient's CT imaging demonstrates significant glenoid wear. With glenoid wear exceeding 20%, the ability of a soft tissue only procedure (ie. Bankart repair) is unlikely to restore adequate stability of the shoulder. In these patients, a bony augment is utilized to improve stability. The Latarjet triple effect includes bony restraint by increasing the glenoid track, a sling effect secondary to the conjoined tendon resting on top of subscapularis, and an anterior restraint from capsule reconstruction via the CA ligament.

Shin et al. reviewed the critical value of anterior glenoid bone loss that led to surgical failure in patients with anterior shoulder instability. They report that the optimal critical value of glenoid bone loss was 17.3%. They concluded that anterior glenoid bone loss exceeding 17.3% should be considered as the critical amount of bone loss that may result in recurrent glenohumeral instability after arthroscopic Bankart repair.

Streubel et al. review the recurrence of glenohumeral joint dislocations in young male athletes competing in contact sports. They report that diagnostic imaging is critical in assessing bone loss of the glenoid or humeral head. They concluded that in the setting of anterior glenoid bone loss >20% of the articular surface, iliac crest bone grafting or coracoid transfer via the Bristow or Latarjet procedures has demonstrated satisfactory outcomes.

Gupta et al. reviewed the complications following the Latarjet procedure. In their systematic review, they report a 1.4% rate of neurovascular injury across open and arthroscopic techniques; 11 musculocutaneous nerve injuries, of which 2 were either partial or temporary, while 9 were either partial permanent or complete injuries resulting in nerve deficit. They concluded that a musculocutaneous nerve palsy remains a well-documented albeit rare complication of this procedure.

Clavert et al. reviewed the anatomical relationships between the musculocutaneous nerve and the coracobrachialis in patients undergoing coracoid transfer. They found that lesion of the musculocutaneous nerve is secondary to lengthening of the nerve and modification of the penetration angle into the coracobrachialis. They concluded that some motor nerve destined to the coracobrachialis might be damaged during the proximal medial release of the muscle after the detachment of the pectoralis minor muscle.

Delaney et al. utilized intraoperative neuromonitoring to define the stages of the Latarjet procedure during which the nerves are at greatest risk. They reported that 76.5% of cases had nerve alert episodes, occurring most commonly during glenoid exposure and graft insertion. They noted that 20.6% of cases had a clinically detectable nerve deficit postoperatively, with all cases involving the axillary nerve and all resolving completely from 28-165 days postoperatively. They concluded that nerves, in particular the axillary and musculocutaneous nerves, are at risk during the Latarjet procedure, especially during glenoid exposure and graft insertion.

Figure A is a CT image demonstrating significant glenoid wear. Figures B&C are the axial and coronal CT images revealing a Hill-Sachs lesion of the humeral head.

Incorrect Answers:
Answers 1&4: A soft tissue only procedure (ie. Bankart repair) would not adequately address instability in the setting of significant glenoid bone loss and an off-track Hill-Sachs lesion
Answers 3&5: This patient's postoperative examination is concerning for a musculocutaneous neuropraxia as evident by his lateral forearm numbness (lateral antebrachial cutaneous nerve is a branch of the musculocutaneous nerve) and supination weakness (biceps is primarily a supinator)