Working Diagnosis:
Left pectoralis major avulsion fracture

Treatment:
The case was discussed with the upper extremity orthopedics team. The patient was deemed to have good non-operative healing potential given his skeletal immaturity, bony avulsion without imaging evidence of tendon involvement, and minimal displacement of the bony fragment. He was immobilized in internal rotation with a shoulder sling and abduction pillow.

Outcome:
At follow-up two weeks later, he reported resolution of pain and the ecchymosis. Repeat x-rays revealed early bridging and ongoing periosteal reaction Case Photo #5 . The plan was for a total of 4 weeks of immobilization followed by PT and gradual loading. Unfortunately, the patient was lost to follow up, and did not present again until 3 months after the original injury. By then, he reported full pain-free range of motion but had mild muscle soreness with weightlifting. He had trace strength asymmetry on exam, and x-rays revealed a smooth bridging callus consistent with a healing avulsion fracture Case Photo #6 . PT was encouraged, but the patient declined given his full return to activity. He was seen for an unrelated issue in the pediatric ED one year after the original injury, where x-rays showed complete osseous healing Case Photo #7 .

Author's Comments:
Pectoralis major tendon injuries are rare, especially in the pediatric population. They are grouped into three categories based on the anatomic location of injury: the muscle origin or muscle belly, musculotendinous junction, and a bony avulsion fracture. Traditionally distal, full thickness tears require operative repair. However certain patient characteristics may favor non-operative management. While minimal literature exists on non-operative management of pediatric pectoralis major avulsion fractures, there is precedent for non-operative management of other large bony avulsion fractures in adolescents, specifically pelvic avulsion fractures.

Injury features that were favorable for non-operative management in our patient included that he was skeletally immature, had a true avulsion fracture without evidence of tendon injury, and had minimal displacement of the bony fragment. Adolescents with open physes have strong bony healing potential, especially with minimally displaced bony fragments like in our patient. However, if there is tendon involvement, tendon retraction, significant displacement of the bony fragment (>1cm), the standard of care remains operative repair. Non-operative management consists of immobilization in internal rotation to offload the pectoralis major tendon for 4-6 weeks followed by physical therapy and gradual loading.

Editor's Comments:
Pectoralis major muscle injuries are a rare occurrence. The most common scenario that results in this type of injury is weightlifting and more specifically related to bench press. Because this is a rare injury it can be missed and lead to a delay in diagnosis and can lead to poor outcomes for the patient. The treatment can be influenced by several factors including activity level, severity of injury and activities of daily living (1). Pectoralis major injuries are commonly caused by tension on the eccentrically contracted muscle. While most common in weightlifting it can also be seen in many other activities including football (3). There has also been some correlation with anabolic steroid use cited in case reports (2). These injuries tend to be most common in young males in the 3rd and 4th decade of life. The pectoralis major tendon inserts on the humerus and most commonly injuries involve avulsion of the tendon but can also lead to myotendinous junction tears. The musculotendinous junction tears are more commonly associated with direct trauma (1). The presentation usually includes a history of an activity that ended with a popping sensation. Discussing the mechanism of injury can often help lead to the diagnosis. The patient will generally report a popping sensation followed by swelling, pain and ecchymosis. Inspection of the area can help lead to further concern if abnormalities are noted in the muscle. Patients can also have some pain and weakness with adduction and internal rotation of the arm (1). In some cases, an X-ray can show an avulsion injury but are utilized more frequently to rule out other differentials. In some cases, ultrasound can be helpful as a diagnostic tool but most of the literature that exists is limited to case studies. MRI is considered the preferred imaging choice as it can help assess location and help further evaluate for acute vs chronic injury. The most common treatment modality for a full tear is operative management, although non operative management can be utilized in some cases as shown in this case. Studies have shown that surgical intervention is generally the preferred treatment options due to impact on overall mobility and performance (4)

References:
Bodendorfer BM, et al. Treatment of Pectoralis Major Tendon Tears: A Systematic Review and Meta-analysis of Operative and Nonoperative Treatment. Orthop J Sports Med. 2020 Feb 6;8(2): doi: 10.1177/2325967119900813.
Schepsis AA, et al. Rupture of the Pectoralis Major Muscle: Outcome After Repair of Acute and Chronic Injuries. The American Journal of Sports Medicine. 2000;28(1):9-15. doi: 10.1177/03635465000280012701.
Shepard NP, Westrick RB, Owens BD, Johnson MR. Bony avulsion injury of the pectoralis major in a 19 year-old male judo athlete: a case report. Int J Sports Phys Ther. 2013 Dec;8(6):862-70. PMID: 24377072.
Yeager KC, Silva SR, Richter DL. Pelvic Avulsion Injuries in the Adolescent Athlete. Clin Sports Med. 2021 Apr;40(2):375-384. doi: 10.1016/j.csm.2020.12.002. Epub 2021 Feb 5. PMID: 33673893.

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