Poster 138: Hypertrophy of the Anterior Coracoacromial Ligament as an Etiology of Shoulder Pain in the Young Overhead Athlete: The CALPYSO condition
Authors: O’Brien Michael , McEwen Madeline , Gregory Bonnie , Nicholson Gregory 
Published: July 2022

Objectives: Shoulder pain in the young overhead athlete is commonly thought to result from instability and SLAP pathology, but not from a primary subacromial space pathology. We encountered a series of young overhead athletes with shoulder pain not due to instability or SLAP pathology. All had pain at the anterolateral (AL) corner of the acromion. We report the clinical characteristics, pathology, and results of treatment of this previously unreported association. Methods: 92 young (mean age 19 [13-26]) overhand athletes presented with shoulder pain unresponsive to conservative treatment. There were 54 (59%) males and 38 (41%) females. 76% had pain at the AL acromial corner. 71% had pain with an overhand arc of motion from Abd/ER to Abd/IR position. 53% had SLAP-type physical exam findings, but none had instability symptoms. Patients most commonly participated in the following sports: Baseball 38.5%, Swimming 16%, Softball 15%, and Volleyball 11%. Pre-op mean scores were: ASES= 60, SST= 7.5, and VAS pain= 4.3. All underwent EUA and arthroscopy. There was no evidence of instability or SLAP pathology. All had varying degrees of subacromial bursitis. But, the primary pathology was a thickened anterior CA ligament (CAL). The hypertrophic CAL inserted on the acromion, but also extended far laterally under the deltoid muscle. This formed an “awning” at the AL acromial corner which resulted in significant subacromial space compromise. The hypertrophic CAL anterior edge and lateral extension was excised and bursectomy performed in all and in 90% an osseous acromioplasty was performed as well. There were associated pathologic findings: 15 (16%) had posterior capsular contracture with GIRD, 10 (11%) had a posterior labral split tear at the equator of the glenoid. Results: At average follow-up of 2.2 years (1-5), all had returned to the former level of overhead sport activity. Rapid rehabilitation was possible and average time to return to sport was 19 weeks (8-52, SD 10.2). Seventy-five (81.5%) returned to the same level of sport. At final follow-up, mean VAS decreased from a preoperative level of 3.7 (SD 2.5, range 0-8) to a postoperative level of 0.6 (SD 1.1, range 0-4) (p<0.0001). Mean ASES score improved 30.7 points after surgery, corresponding to an improvement from a preoperative level of 63.1 (SD 19.7, range 26.7-100) to a postoperative level of 93.8 (SD 9.3, range 73.3-100) (p<0.0001). Simple shoulder test (SST) scores also improved from a preoperative level of 8.8 (SD 3.1, range 0-12) to a postoperative level of 11.6 (SD 1.0, range 8-12) (p<0.0001). There were no complications, re-operations, and no occult instability was revealed. Conclusions: Younger age (avg 19 yrs, high school and collegiate athletes) participating in overhand sports, typically year-round were defining, consistent factors in this patient population. Female athletes made up a substantial 41% of the series. We feel that symptomatic, hypertrophic anterior CAL is a variant of impingement, most likely due to use and overuse in a repetitive overhead sport. Overuse is recognized as an etiology for shoulder pathology including instability, SLAP lesion, and labral injury, but subacromial pathology is more thought of as a condition of an older age group. This clinical entity in this series, we feel, is another form of overuse pathology and is a primary subacromial space pathology. It was not secondary to occult instability or posterior capsule tightness or SLAP pathology. Thus, not all shoulder problems in young, overhead athletes should be attributed to occult instability or SLAP pathology. We have developed a mnemonic for this clinical entity: CALYPSO. C: Coracoacromial ligament A: Anterior band hypertrophy and L: Lateral extension under the deltoid. Y: Youth (high school and college age) P: Posterior capsular contracture and labral pathology. S: Subacromial bursitis; O: Overuse and Overhead sport Clinicians should maintain a high index of suspicion for this clinical entity when evaluating young overhead athletes. In all cases, arthroscopy was successful in identifying and treating the pathology and all athletes were able to return to their previous level of sport.