Comparison of Structural Subscapularis Integrity After Latarjet Procedure Versus Iliac Crest Bone Graft Transfer

Abstract

Background: Although clinical outcome scores are comparable after coracoid transfer procedure (Latarjet) and iliac crest bone graft transfer (ICBGT) for anterior shoulder instability with glenoid bone loss, a significant decrease in internal rotation capacity has been reported for the Latarjet procedure. Hypothesis: The subscapularis (SSC) musculotendinous integrity will be less compromised by ICBGT than by the Latarjet procedure. Study Design: Cohort study; Level of evidence, 3. Methods: We retrospectively analyzed pre- and postoperative computed tomography (CT) scans at short-term follow-up of 52 patients (26 Latarjet, 26 ICBGT) previously assessed in a prospective randomized controlled trial. Measurements included the preoperative glenoid defect area and graft area protruding the glenoid rim at follow-up and tendon thickness assessed through SSC and infraspinatus (ISP) ratios. Fatty muscle infiltration was graded according to Goutallier, quantified with muscle attenuation in Hounsfield units, and additionally calculated as percentages. We measured 3 angles to describe rerouting of the SSC musculotendinous unit around the bone grafts. Results: SSC fatty muscle infiltration was 2.0% ± 2.2% in the Latarjet group versus 2.4% ± 2.2% in ICBGT ( P = .546) preoperatively and showed significantly higher values in the Latarjet group at follow-up (5.3% ± 4.5% vs 2.3% ± 1.7%; P = .001). In total, 4 patients (15.4%) in the Latarjet group showed a progression from grade 0 to grade 1 at follow-up, whereas no changes in the ICBGT group were noted. The measured rerouting angle of the SSC muscle was significantly increased in the Latarjet group (11.8° ± 2.1°) compared with ICBGT (7.5° ± 1.3°; P < .001) at follow-up, with a significant positive correlation between this angle and fatty muscle infiltration ( R = 0.447; P = .008). Ratios of SSC/ISP tendon thickness were 1.03 ± 0.3 in the Latarjet group versus 0.97 ± 0.3 ( P = .383) in ICBGT preoperatively and showed significantly lower ratios in the Latarjet group (0.7 ± 0.3 vs 1.0 ± 0.2; P < .001) at follow-up. Conclusion: Although clinical outcome scores after anterior shoulder stabilization with a Latarjet procedure and ICBGT are comparable, this study shows that the described decline in internal rotation capacity after Latarjet procedure has a radiographic structural correlate in terms of marked thinning and rerouting of the SSC tendon as well as slight fatty degeneration of the muscle.

Primary Open Latarjet Procedure Results in Functional Differences but No Structural Changes in Subscapularis Muscle Quality vs the Healthy Contralateral Shoulder at Long-term Follow-up

“…36 Besides this stabilizing effect, there are concerns that this permanent redirection of the muscle and tendon may jeopardize subscapularis structure and function. 31 Although the consequence of this redirection may solely be altering the moment arm of the subscapularis, the integrity of the inferior half of the subscapularis is without any doubt one of the prerequisites of a stable and functioning glenohumeral joint. 10,11 The Latarjet procedure was reported to be associated with varying loss of glenohumeral rotation strength.…”

The Subscapularis-Sparing “Flipped Latarjet” Procedure

“…Siegert et al. 22 retrospectively compared the changes to the subscapularis muscle in patients who underwent an iliac crest bone graft to the anterior glenoid and patients who were treated with a Latarjet procedure. They found that the progress of fatty infiltration of the subscapularis muscle and the rerouting angle of the muscle were significantly higher for Latarjet patients on CT scans, and this correlated with a lower capacity of internal rotation.…”

“… 11 , 12 , 13 , 19 , 21 Moreover, due to the permanent split of the subscapularis, weakness and muscle atrophy with fatty degeneration of the inferior part of the muscle itself have been described. 22 , 23 …”

Is sling immobilization necessary after open Latarjet surgery for anterior shoulder instability? A randomized control trial

“…Lastly, a potential benefit of avoiding a sling postoperatively is the prevention of muscle atrophy. Recent studies suggested a negative impact on internal rotation at 90° of abduction after the Latarjet procedure secondary to subscapularis rerouting compared to iliac bone grafts ( 42 , 60 ).…”