CHAPTER 16 Open bony augmentation of glenoid bone loss—the latarjet and variants—surgical technique

Allan A. Young, MBBS, MSpMed, PhD, FRACS (Orth), Gilles Walch, MD

The Latarjet procedure is effective in treating anterior instability by providing a “triple blocking” mechanism. The “triple blocking” mechanism is comprised of (1) a bone effect—increased anteroposterior (AP) diameter of glenoid articular surface, (2) a muscular effect—action of the conjoint tendon on the inferior subscapularis, and (3) a ligamentous effect—repair of the capsule to the coracoacromial ligament stump.

Performing the procedure via a subscapularis splitting technique prevents muscle scarring or rupture and loss of external rotation.

Stable fixation of the coracoid with two screws in the lying position is recommended to maximize bony union.

Suturing the capsular flap to the stump of the coracoacromial ligament with the arm in external rotation allows immediate rehabilitation exercises in external rotation.

A precise surgical technique is essential to avoid complications.

Introduction

Glenoid bone loss is commonly observed in anterior instability and varies greatly in both its extent and significance.¹^,² In 2000, Burkhart et al reported a recurrence rate following arthroscopic Bankart repair for anterior instability of 4% in patients without significant bone deficiency, whereas the rate of recurrence was 67% in the presence of a bone lesion.³ They defined significant glenoid bone loss as an “inverted pear glenoid” in which there is a greater than 25% loss of the inferior glenoid diameter. In the setting of anterior instability with significant bone loss, a Latarjet procedure is recommended.

In 1954, Latarjet described a coracoid bone block technique to prevent anterior dislocation, suggesting that the horizontal limb of the coracoid process be fixed to the anteroinferior margin of the glenoid with a screw.⁴ Augmentation of the anteroinferior glenoid with this procedure has obvious advantages in cases of glenoid bone loss. However, this “bone blocking effect” only contributes in part to the stabilizing mechanism of the Latarjet procedure. Although the precise mechanism is still unknown, the success of the intervention is explained by a triple effect first proposed by Patte et al⁵: (1) the effect of the conjoint tendon when the arm is abducted and externally rotated, where it acts as a sling on the inferior subscapularis and anteroinferior capsule; (2) the “bony effect,” increasing or restoring the glenoid AP diameter; and (3) the effect of repairing the capsule to the stump of the coracoacromial ligament (Fig. 16-1).

FIGURE 16-1 Triple blocking effect. A, Normal position of scapularis providing no inferior support in provocative position of the shoulder (i.e., abduction and external rotation). B, Completed Latarjet with arm in neutral, anterior bone block, and capsule repaired to coracoacromial ligament (CAL). C, The inferior displacement of the subscapularis by the conjoint tendon creates a sling beneath the anteroinferior capsule, especially in the abducted, externally rotated position of the arm.

The technique described in this chapter includes a number of modifications from the original, most notably the use of two screws instead of one to provide stable fixation of the coracoid and utilization of a subscapularis splitting approach. Performing the Latarjet procedure through a horizontal split in the subscapularis preserves the continuity of the muscle fibers and allows for immediate postoperative range of motion exercises in external rotation. Numerous additional variations have been proposed relating to the subscapularis management, the position and alignment of the coracoid process, including intra- or extraarticular placement, methods of coracoid fixation, the management of the capsulolabral structures, and performing the procedure arthroscopically. Regardless of which specific variations are used, a precise surgical technique is essential to avoid potential complications. With appropriate patient selection, the Latarjet procedure can be expected to prevent recurrent anterior instability without the loss of external rotation in more than 98% of cases.⁶

Preoperative history, examination, and radiographic findings

Preoperative history

• The history is typical for any patient presenting with instability symptoms and should include the mechanism of dislocation (although this is often not clear), the direction of dislocation, reduction maneuvers required, recurrence, associated injuries, inter-episodic pain, and location of any pain.

• Recurrent anterior subluxation may be difficult to diagnose. A history of pain in the abducted externally rotated arm, pain resulting in a temporarily useless arm (dead arm syndrome), and more subtle variations can occur.

Examination findings

• Always assess for axillary nerve injury by examining for sensation in the regimental badge area and motor power of the deltoid.

• Presence of the sulcus sign suggests hyperlaxity.

• Ninety degrees or more of external rotation with the elbow at the side defines “multidirectional constitutional hyperlaxity.”

• Positive anterior and posterior drawer tests suggest hyperlaxity.

• Positive anterior apprehension tests (+/− relocation test) suggest instability.

• With Gagey’s hyperabduction test,⁷ more than 105 degrees in abduction-internal rotation suggests distention of the inferior glenohumeral ligament (IGHL), and asymmetric difference in abduction of more than 20 degrees implies significant pathologic IGHL distention.

Pearls and Pitfalls

The finding of a large, painless anterior drawer test, or positive sulcus sign, is evidence of constitutional hyperlaxity but not necessarily of instability. Comparison should be made with the asymptomatic shoulder, and usually the positive tests for hyperlaxity are bilateral. Clinical examination should aim to differentiate general hyperlaxity from pathologic laxity associated with true instability. To identify pathologic laxity of the IGHL, we have found the Gagey sign most useful, specifically looking for significant asymmetry compared with the asymptomatic side.