Biceps Brachii Tendonitis Definition
Biceps brachii tendonitis is inflammation of the tendon around the long head of the biceps muscle, though the term is often a misnomer since most cases actually represent tendinosis—chronic degenerative changes rather than acute inflammation. 1, 2
Pathophysiology and Classification
The condition involves two distinct pathologic processes that are frequently confused:
- True tendonitis represents acute inflammatory changes in the biceps tendon, occurring in only 5% of patients with biceps tendon pathology 2
- Tendinosis is the more common presentation, caused by chronic degeneration of the tendon from repetitive overhead motion or normal aging, characterized by changes in tenocyte size, ground substance, collagen organization, and vascularity 1, 3
- Most patients have prolonged symptoms before presentation, by which time acute inflammation has subsided and been replaced by degeneration of the normally highly arranged collagen fiber structure 1
Clinical Presentation
The typical presentation includes:
- Insidious onset of load-related localized pain coinciding with increased activity, particularly in athletes requiring overhead motion 1, 2
- Deep, throbbing ache in the anterior shoulder that is exacerbated by repetitive overhead arm motion 2
- Pain described as "sharp" or "stabbing" in quality 1
- Early-stage pain present during activity but may subside after warm-up, progressing to constant pain at rest in later stages 1
Physical Examination Findings
Key examination findings include:
- Bicipital groove point tenderness with the arm in 10 degrees of internal rotation is the most common isolated clinical finding 2
- Inspection may reveal muscle atrophy (indicating chronicity), swelling, erythema, and asymmetry 1
- Palpation elicits well-localized tenderness similar in quality and location to activity-related pain 1
- Range-of-motion testing often limited on the symptomatic side 1
- Physical maneuvers that simulate tendon loading predictably reproduce the patient's pain 1
Associated Pathology
Biceps tendinitis and tendinosis are commonly accompanied by rotator cuff tears or SLAP (superior labrum anterior to posterior) lesions, and are rarely isolated findings. 2, 4
Important Caveats
- The presence of multiple symptomatic tendons should prompt evaluation for rheumatic disease or rheumatologic referral 1
- Joint effusions are uncommon with tendinopathy and suggest intra-articular pathology 1
- Clinical diagnosis can be difficult given nonspecific physical examination findings 4
- MRI has low sensitivity and frequently results in missed or misdiagnosed biceps pathology, so clinical decision-making should be guided by strong clinical suspicion based on patient history and physical examination 3