A 15-year-old male, right hand dominant baseball player, presented to the sports medicine clinic with 1 wk of left shoulder pain. He reported that while performing two arm body weight pull-ups, he felt a pop in the front of his shoulder as he was lowering himself down. The pop was associated with immediate anterior shoulder pain and swelling. When he presented to our clinic 1 wk later, his pain had improved significantly. However, he continued to endorse some weakness and pain with forward flexion of his shoulder. Of note, the patient did endorse recently starting a work-up for a possible connective tissue disorder because of a family and personal history of hypermobility and skin hyperplasticity. He denies any prior injuries to the left upper extremity or shoulder.
On initial physical examination, upon inspection, he had slight swelling about the anterior inferior shoulder and was tender on palpation over the coracoid and long head of the biceps tendon. He did not have tenderness to palpation of the sternoclavicular and acromioclavicular joints, the deltopectoral junction, or pectoralis tendon. His active range of motion was full and unrestricted and symmetric to the contralateral side. He also had slightly decreased strength with shoulder forward flexion compared with contralateral side, as well as a positive Speeds and Biceps Load maneuvers. He had a negative Popeye's sign. He had normal light touch to axillary nerve distribution, and his radial and ulnar pulses were regular rate and rhythm. His Beighton score was a 4/9 (points for MCP >90 degrees and thumb opposition bilaterally).
Anterior-posterior and axillary radiographs of the shoulder were unremarkable. Magnetic resonance imaging (MRI) of the left shoulder was ordered to evaluate the soft tissue structures of the shoulder. The MRI revealed a complete rupture of the origin of the coracobrachialis tendon from the coracoid process with 11 mm of distal tendinous retraction (Fig. 1). The fibers of the short head biceps tendon origin were intact more laterally on the coracoid process. The rotator cuff, labrum, and long head of biceps tendon were all intact. Because of the rarity of the injury, he was referred to sports medicine surgery for consultation and further management. It should be noted that by the time reevaluation occurred, the strength deficit had resolved. A brief literature review indicates that there is currently a paucity of documented guidance in the literature for management of isolated coracobrachialis ruptures, so the initial course of treatment recommended by our surgical colleague relied solely on clinical reasoning.
Thus, the decision to initially treat nonoperatively was based on the following:
- The patient had regained full range of motion and strength on examination.
- The amount of retraction was only 11 mm, which effectively preserves the muscle length tension relationship.
- With the short head of the biceps still intact and because they share a common origin, this will likely serve as a scaffold for the ruptured coracobrachialis (Fig. 2) (1).
- The affected arm was the patient's nondominant arm.
He was followed medically for 3 wk from initial onset of injury and returned to high school sports under the supervision of his athletic trainer once released from our care. After 6 wk of total rest, our patient slowly returned to activity as tolerated without any recurrence of pain or subjective deficits.
Coracobrachialis ruptures are extremely rare. There have only been four documented coracobrachialis ruptures reported in the literature (2). All four of the cases documented in the literature were managed surgically due to either concomitant ruptures, penetrating trauma, or the development of musculocutaneous traction neuropathy (3–6). In 1939, Gilcreest and Albi (3) were the first to describe a coracobrachialis rupture in the literature. They described a complete rupture of the muscle belly that resulted from direct penetrating trauma and was surgically repaired. A parachute injury in a military adult paratrooper, which resulted in ruptures of both the short head of the biceps and coracobrachialis, was described 2 years later in 1941 by Tobin et al. (4). More recently in 2014, Spiegel et al. (5), documented an isolated coracobrachialis rupture of the distal tendon in a 41-year-old man. This went on to be surgically repaired months later after a delayed diagnosis and the development of musculocutaneous traction neuropathy. The fourth documented coracobrachialis rupture came 1 year later in 2015. Saltzman et al. (6) described an anterior shoulder dislocation that resulted in a rupture of the proximal coracobrachialis tendon rupture and a concomitant rupture of the subscapularis in a 57-year-old woman. Both of which went on to be surgically repaired. To the best of our knowledge, this is the first documented case of an isolated rupture of the proximal origin of the coracobrachialis in an adolescent. This also is the first published case of a coracobrachialis rupture managed nonoperatively.
The decision to manage nonoperatively was based on the factors described above. The intact short head of the biceps tendon and the minimal amount of retraction on advanced imaging were key factors in the decision to manage nonoperatively. In fact, in the case of the anterior shoulder dislocation described above, the coracobrachialis tendon was reattached to the lateral border of the short head of the biceps (tenodesis) (6). In our case, this supports the theory that the short head of the biceps will serve as a scaffold, and the muscle length tension relationship will be preserved. Another interesting point to consider is whether or not our patient would have reported subjective weakness if it had been his dominant arm. It is well known that overhead athletes, particularly baseball pitchers, are affected by minor changes in strength and range of motion (7–10). It is possible that had our patient injured his dominant arm, he may have experienced subjective or even measurable strength and/or range of motion deficits upon return to pitching. Finally, a special consideration for coracobrachialis ruptures is the potential to develop musculocutaneous traction neuropathy. This has been reported in the literature with muscle belly and distal tendon ruptures (5). The musculocutaneous nerve is vulnerable to injury in coracobrachialis ruptures as the nerve pierces through the muscle approximately 5 cm distal to the coracoid. Should our patient develop lateral forearm paresthesia in the future, further investigation into traction neuropathy is warranted.
A connective tissue disorder could have predisposed our patient to this rare injury. However, at this time, he does not have a confirmatory diagnosis. His Beighton score also did not meet the criteria for hypermobility, although you cannot fully rule out hypermobility based on this score. He was encouraged to continue the genetic hypermobility work-up.
We presented an exceedingly rare case of an isolated coracobrachialis tendon rupture in an adolescent athlete. This case report poses challenges of treatment given the rarity of this injury. Given the function of the coracobrachialis is to flex and adduct the arm at the shoulder joint, the mechanism of injury was likely an eccentric pull during the downward phase of the pull-up. Understanding of regional anatomy was helpful in decision making and to treat nonoperatively given the short head of the bicep was intact combined with only 11 mm of retraction of the coracobrachialis tendon occurred. Further, the patient regained full strength without range of motion limitations or signs of peripheral nerve injury. This case report may serve as an important reminder that multiple factors go into operative versus nonoperative treatment.
The authors declare no conflict of interest and do not have any financial disclosures.
1. Muscles of the upper arm-biceps-triceps—TeachMeAnatomy [Internet]. 2021. [cited 2021 May 18]. Available from: https://teachmeanatomy.info/upper-limb/muscles/upper-arm/
2. Trail IA, Funk L, Rangan A, Nixon M. Textbook of Shoulder Surgery
. Springer; 2019. 605 p.
3. Gilcreest E, Albi P. Unusual lesions of muscles and tendons of the shoulder girdle and upper arm. Surg. Gynecol. Obstet
. 1939; 68:903–17.
4. Tobin WJ, Cohen LJ, Vandover JT. Parachute injuries. JAMA
. 1941; 117:1318–21.
5. Spiegl UJ, Faucett SC, Millett PJ. Traumatic rupture of the coracobrachialis muscle: a case report. JBJS Case Connect
. 2014; 4:e54–e4.
6. Saltzman BM, Harris JD, Forsythe B. Proximal coracobrachialis tendon rupture, subscapularis tendon rupture, and medial dislocation of the long head of the biceps tendon in an adult after traumatic anterior shoulder dislocation. Int. J Shoulder Surg
. 2015; 9:52–5.
7. Tyler TF, Mullaney MJ, Mirabella MR, et al. Risk factors for shoulder and elbow injuries in high school baseball pitchers: the role of preseason strength and range of motion. Am. J. Sports Med
. 2014; 42:1993–9.
8. Shanley E, Kissenberth MJ, Thigpen CA, et al. Preseason shoulder range of motion screening as a predictor of injury among youth and adolescent baseball pitchers. J. Shoulder Elb. Surg
. 2015; 24:1005–13.
9. Wilk KE, Macrina LC, Fleisig GS, et al. Deficits in glenohumeral passive range of motion increase risk of elbow injury in professional baseball pitchers: a prospective study. Am. J. Sports Med
. 2014; 42:2075–81.
10. Camp CL, Zajac JM, Pearson DB, et al. Decreased shoulder external rotation and flexion are greater predictors of injury than internal rotation deficits: analysis of 132 pitcher-seasons in professional baseball. Arthroscopy
. 2017; 33:1629–36.