Abstract
Background:
Overhead throwing athletes are predisposed to ossification along the superior to inferior posterior glenoid rim, termed thrower's exostosis or a Bennett lesion. These lesions can result in posterior shoulder pain during throwing and decreased shoulder range of motion, and they can be associated with posterior labral tears and undersurface rotator cuff tears. In this video technique, we describe the arthroscopic debridement and resection of a symptomatic unstable Bennett lesion in a collegiate baseball pitcher who had unsuccessful nonoperative treatment.
Indications:
Currently, there is no standard treatment algorithm for Bennett lesions. Arthroscopic intervention is typically indicated in overhead throwers who have unsuccessful nonoperative protocols, including stretching of the posterior capsule, strengthening of the rotator cuff, and injections.
Technique Description:
In the lateral decubitus position, standard posterior viewing and anterior working arthroscopic portals are created followed by diagnostic arthroscopy. A high anterior accessory portal is created to view the posterior labrum and evaluate for tears. The location of the Bennett lesion is determined using a switching stick or probe. In this case, an accessory posterior viewing portal and capsulotomy are created under spinal needle visualization and a 70° scope is utilized for an improved view. Through the capsulotomy, a motorized shaver and radiofrequency wand is used to work along the posterior inferior glenoid neck to expose the lesion. Once the lesion is fully demarked, a hooded bur is utilized to debride the entirety of the lesion back to the smooth bony surface of the glenoid neck. After resection, the capsule is left open to avoid overtightening the posterior capsule in overhead throwing athletes.
Results:
Arthroscopic debridement and resection of a symptomatic Bennett lesion in a collegiate baseball pitcher allowed the patient to return to pain-free pitching at the same level of collegiate play the following season.
Discussion/Conclusion:
An unstable Bennett lesion can be a source of pain in the overhead throwing athlete. If nonoperative treatment modalities fail to resolve symptoms, arthroscopic debridement and excision of this lesion utilizing a posterior capsulotomy and accessory posterior viewing portal as described in this video technique is a safe and effective surgical option.
Patient Consent Disclosure Statement:
The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.
This is a visual representation of the abstract.
Video Transcript
Here we present a surgical technique for arthroscopic debridement with resection of an unstable type 1B Bennett lesion.
The authors’ disclosures are listed here.
Background
The Bennett lesion, also known as “thrower’s exostosis,” was first described by George E. Bennett in professional baseball pitchers in 1941 as a posteroinferior exostosis lesion of the glenoid. 1 More recently, this lesion has been recognized in both symptomatic and asymptomatic throwing athletes and has been reported to occur in as many as 22% of asymptomatic major league pitchers. 6 These lesions are thought to result from excessive loading and the stress of repetitive throwing, leading to posterior capsule calcification. Symptomatic patients in general have pain and loss of shoulder range of motion. On examination, patients can have tenderness to palpation along the posterior inferior glenoid and radiating pain into the region of the latissimus dorsi and teres minor and major. 5 Bennett lesions can also be associated with posterior labral pathology and undersurface rotator cuff tears.
Historically, numerous types of thrower's exostosis have been categorized as a Bennett lesion, and in 2020, Freehill et al 3 created a classification system to help guide further research and management of these lesions. This classification system is based on the location of the lesion on the glenoid (posteroinferior being type 1, straight posterior being type 2, and posterosuperior being type 3). The authors also added a modifier system designating the lesion as A (stable and attached to glenoid) or B (an unstable detached fragment). This is clinically relevant as pain is the common indication for surgery, and detached, unstable type B lesions tend to more painful. 3
Indications
In general, patients with symptomatic Bennett lesions are initially managed nonoperatively with physical therapy focused on posterior capsular stretching and rotator cuff strengthening, as well as guided corticosteroid injections. 3 Surgical intervention is reserved for patients who have unsuccessful structured rehabilitation programs and are unable to return to throwing competition.2,3 Currently, there is no consensus regarding the optimal surgical management of Bennett lesions, and thus there is controversy regarding the role of Bennett lesion excision in the setting of concomitant shoulder pathology such as rotator cuff or labral injury. 3 The limited reports in the literature covering the surgical management of Bennett lesions involve debridement and resection of the lesion, with or without closure of the posterior capsulotomy. Some authors only recommend capsulotomy closure in the setting of posterior instability or when internal rotation is similar to the contralateral shoulder while avoiding closure in patients with glenohumeral internal rotation deficit or in throwing athletes due to concern for overtightening. 3
The purpose of this technique video is to describe an arthroscopic surgical technique for the visualization, debridement, and excision of a type 1B posteroinferior glenoid Bennett lesion.
Our case involves a 21-year-old right-hand-dominant National Collegiate Athletic Association Division I relief pitcher with no significant medical or surgical history who began to experience discomfort in his right shoulder during the fall season. Most of his pain occurred during the late cocking phase of throwing. He also reported a decrease in his pitch velocity.
On physical examination, the patient demonstrated mild scapular dyskinesia, and on examination at 90° of abduction, internal shoulder rotation was 30° on the right side and 45° on the left with an internal rotation deficit of 15°. External rotation was 120° bilaterally. He had symmetric shoulder forward flexion and abduction bilaterally. He had 5 out of 5 strength with Jobe and subscapularis strength testing, while external rotation strength was 5 out of 5. He had a positive Kim test but otherwise negative provocative testing.
Axial and sagittal T2 shoulder magnetic resonance imaging sequences demonstrate increased signal hyperintensity in the region of the posterior and posteroinferior capsule and an associated osseous lesion without evidence of associated labral tear or rotator cuff injury. Axial and sagittal computed tomography imaging further characterizes an unstable bony exostosis of the posterior inferior glenoid rim.
The patient was initially managed with ultrasound-guided injection directly to the Bennett lesion with 5 cc of 0.5% ropivacaine and 40 mg triamcinolone. This temporarily provided him with complete relief, and he was able to return to pitching for the duration of the baseball season. However, near the conclusion of the spring season, his previous symptoms of pain returned, and the effects of the injection had worn off. The patient was subsequently indicated for surgery.
Technique Description
We now demonstrate our technique for arthroscopic debridement and resection of a type 1B Bennett lesion.
After induction of general anesthesia, the patient was placed into the lateral decubitus position, and examination under anesthesia of the right shoulder was unremarkable without evidence of shoulder instability. Fifteen pounds of traction was hung from the operative arm, and a standard posterior viewing portal was made. We then made a low anterior working portal just over the superior border of the subscapularis. A diagnostic shoulder arthroscopy demonstrated minimal tenosynovitis of the long head of the biceps tendon, and there was mild undersurface fraying of the superior labrum consistent with an overhead thrower. The superior glenoid tubercle was gently roughened with a motorized shaver, and free edge tearing of the posterosuprior labrum was debrided. There was no anterior labral injury that required repair, and the cartilage surfaces of the glenoid and humeral head appeared normal.
Using a spinal needle for localization, a high anterior portal was created, and this was utilized to view and evaluate the posterior labrum. The exostosis lesion is an extra-articular structure and cannot be visualized initially. The overlying intra-articular structures appeared normal apart from some mild longitudinal fissuring of the posterior labrum, which demonstrated no complete tear at the chondrolabral junction. Using a switching stick, the Bennett lesion could be felt along the medial aspect of the posteroinferior glenoid neck.
A larger capsulotomy was performed to address the extra-articular Bennett lesion, and a cannula was inserted into this previously established posterior portal for instrumentation. An accessory posterior portal was created under spinal needle visualization and would act as a viewing portal with a 70° scope. Through the established capsulotomy, a motorized shaver and radiofrequency wand were used to work along the posterior inferior glenoid neck. Care was taken to stay on bone as soft tissue was elevated from the glenoid neck.
The osseous fragment of the Bennett lesion was identified at approximately the 7:30 position. The radiofrequency wand was used to outline the osseous fragment, and then a bur with a hood was used to debride the lesion to the smooth bony surface of the glenoid neck. Care was taken by not overutilizing suction to protect the axillary nerve inferiorly, as well as the suprascapular nerve along the medial glenoid neck.
After complete resection of the lesion, the capsule was left open to avoid overtightening the patient's shoulder given he was an overhead throwing athlete. The posterior labrum in this case did not need to be repaired. The arthroscopic portals were closed with a 3-0 absorbable suture. The patient was placed into a sling with an abduction pillow.
Results
Postoperatively, the patient started passive range of motion exercises at postoperative day 7. Taking the healing of the posterior capsulotomy into consideration, passive range of motion was limited to 90° of forward flexion and 90° of abduction for the first 2 weeks. Internal rotation was limited to the neutral position, and external rotation was limited to 45° over the first 4 weeks. Active range of motion started at 5 weeks postoperatively. Strength training was started at the 8-week mark, and he was started on a throwing program at 10 weeks postoperatively. After completion of the throwing program, the patient transitioned to mound work. He subsequently returned to pain-free pitching at the same level of collegiate play the following season.
Discussion
Several tips and tricks are important to keep in mind when treating patients with symptomatic Bennett lesions. Guided corticosteroid injections can be both diagnostic and therapeutic by confirming that the Bennett lesion is the source of the patient's shoulder pain and potentially relieving the patient's symptoms and allowing the athlete to return to play for the remainder of the season. The posterior labrum should be evaluated for a labral tear. If a large tear is present, the Bennett lesion can be visualized and addressed by working through this tear prior to repair at the end of the case. If no tear is present, a separate capsulotomy must be created to access the extra-articular Bennett lesion. Accessory portals should be utilized for optimal visualization of the Bennett lesion. Finally, the posterior capsule should not be closed in the overhead throwing athlete to avoid overtightening these patients. In the setting where internal rotation of the injured shoulder is similar to the contralateral shoulder, the surgeon may consider capsular closure to avoid instability with an obvious avoidance and caution to overtightening the posterior capsule.
Several small case series have reported outcomes of the arthroscopic treatment of Bennett lesions. Yoneda et al 7 reported an 88% satisfaction rate in 16 baseball players, and 11 of the 16 players (69%) returned to their preinjury level of competition. Nakagawa et al 4 reported on 5 throwing athletes who underwent arthroscopic resection of unstable Bennett lesions. At a minimum 2-year follow-up, all athletes had returned to their preinjury competition level.
In summary, an unstable Bennett lesion can be a source of pain in the overhead throwing athlete. If nonoperative treatment modalities fail to resolve symptoms, arthroscopic debridement and excision of this lesion utilizing a posterior capsulotomy and accessory posterior viewing portal is a safe and effective surgical treatment option.
Thank you.
Footnotes
Submitted March 11, 2024; accepted May 31, 2024.
One or more of the authors has declared the following potential conflict of interest or source of funding: M.F. receives consulting fees from Smith & Nephew and Tornier/Stryker, royalties from Smith & Nephew, hospitality payments from Sparta Biopharma and CONMED, and research funding from Major League Baseball and National Institutes of Health. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.
