Thrower’s Exostosis of the Shoulder: A Systematic Review With a Novel Classification

Abstract

Background: A variety of thrower’s exostoses are grouped under the term Bennett lesion, which makes understanding diagnosis and treatment difficult. Purpose: To identify all types of reported thrower’s and overhead athlete’s exostoses and categorize them into a classification system to allow a morphology-based classification. Study Design: Systematic review; Level of evidence, 4. Methods: A systematic review of all articles pertaining to Bennett lesions and thrower’s exostosis was performed. The classification and treatments were evaluated to describe the types, proposed causes, diagnosis, and treatment options. Results: A total of 27 studies were included in the systematic review. The anatomic locations referenced in the study demonstrated posteroinferior, posterior, and posterosuperior glenoid lesions. Aggregate radiographic data demonstrated 158 of 306 patients (52%) with a thrower’s exostosis of any type and location. Of these 158 patients with a radiographic lesion, 119 (75%) patients were symptomatic. The locations were posteroinferior in 110 patients (70%), directly posterior in 2 patients (1.3%), posterosuperior in 44 patients (28%), and unknown in 2 patients (1.3%). Avulsed lesions were present in 9 (5.7%) posteroinferior lesions, 0 direct posterior lesions, and 2 (1.3%) posterosuperior lesions. Treatment plans included both nonoperative and operative strategies, but operative intervention was more commonly reported for detached lesions. After operative intervention, only 61% of reported athletes returned to preinjury performance. Conclusion: Based on a comprehensive review of the literature, we identified several anatomic locations for a thrower’s exostosis beyond the classic Bennett lesion. We categorized the reported exostoses into a new classification system for description of location and type (subperiosteal or free fragment) of the thrower’s exostosis, which may be used to study future treatments. Current treatment strategies recommend that surgical treatment of thrower’s exostosis is considered only after exhausting nonoperative management because reported return to sport is variable after surgery. The effectiveness of excision or repair for both subperiosteal and detached lesions has not been established.

Arthroscopic Bennett Lesion Resection and Posterior Labral Repair Using All-Suture Anchors

“…Some prefer labral repair with suture anchor constructs, whereas others routinely perform labral debridement in the presence of fraying or small tears. 2 In addition, a posterior capsulotomy is typically performed to access the exostosis, and previously reported techniques involve capsular repair following excision of the lesion. 4,5,12 Others recommend a more selective approach, reserving repair of the capsulotomy for cases with associated posterior subluxation 13 and foregoing repair if patients show glenohumeral internal rotation deficit.…”

“…The Bennett lesion, also known as thrower’s exostosis, is a calcification located at the posterior glenoid rim that is common in throwing athletes. 1 , 2 An incidence of approximately 22% has been reported among professional baseball pitchers. 3 Exostoses in several locations along the posterior glenoid may be referred to as Bennett lesions 2 ; however, the conventional location originally described by Bennett refers to an extra-articular ossification at the posteroinferior glenoid rim.…”

“… 1 , 2 An incidence of approximately 22% has been reported among professional baseball pitchers. 3 Exostoses in several locations along the posterior glenoid may be referred to as Bennett lesions 2 ; however, the conventional location originally described by Bennett refers to an extra-articular ossification at the posteroinferior glenoid rim. 1 Although this lesion was initially thought to be due in part to an epiphysitis of the triceps origin, 1 it is now believed to be reactive bone formation in the posterior capsule and posterior inferior glenohumeral ligament due to repeated traction.…”

“… 10 , 11 Symptoms related to these lesions are initially treated nonoperatively, with physical therapy focused on posterior capsular stretching (i.e., sleeper stretch) and strengthening of the rotator cuff. 2 Excision of the Bennett lesion and addressing associated intra-articular pathology are considered in patients with recalcitrant symptoms or inability to return to previous level of activity despite 3 to 6 months of nonoperative treatment.…”

“…Some prefer labral repair with suture anchor constructs, whereas others routinely perform labral debridement in the presence of fraying or small tears. 2 …”