Pectoralis Major Rupture

Pectoralis major rupture is an increasingly recognised injury, particularly among weightlifters and athletes. Its incidence has risen significantly over recent decades, in parallel with the growing popularity of resistance training and with anabolic steroid use.

Who. Predominantly men aged 20 to 40. The bench press accounts for approximately 90% of cases, and the dominant side is more commonly affected.

What it costs. Weakness of shoulder adduction, flexion and internal rotation, which significantly impairs pressing and throwing. The lost anterior axillary fold is disfiguring, and the psychological impact is important in young active patients and bodybuilders.

Why it is missed. In the emergency setting the ecchymosis and swelling obscure the clinical picture, so the diagnosis is frequently missed or delayed. Early recognition and timely surgical repair of a complete tear yield excellent functional outcomes; delayed diagnosis leads to retraction, scarring and inferior results.

The muscle. A large fan-shaped muscle with two heads, clavicular and sternocostal, which converge on a bilaminar tendon. The tendon twists 90 degrees before inserting on the lateral lip of the bicipital groove of the humerus, where its anterior and posterior layers have a U-shaped morphology.

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Why the inferior fibres fail. The layered, twisted arrangement puts the inferior (sternocostal) fibres under the greatest tension when the arm is abducted and externally rotated. In that position they are maximally stretched, at a mechanical disadvantage, and they are the most vulnerable during eccentric loading.

Mechanism. The arm is abducted 60 to 90 degrees and externally rotated, in the eccentric (lowering) phase of the bench press or a similar pressing movement. A maximal eccentric contraction against heavy load exceeds the tensile strength of the tendon. Inadequate warm-up, excessive load and anabolic steroid use all contribute.

Why the insertion. Failure is most commonly at the humeral insertion, as a tendinous avulsion. The twist of the bilaminar tendon concentrates stress there, and the insertion zone is a vascular watershed with a relatively poor blood supply.

Anabolic steroids are a recognised risk factor. They rapidly increase muscle mass and contractile force, but the tendon does not strengthen at the same rate, and they also cause collagen dysplasia: disorganised, stiffer, less elastic collagen fibrils with altered crimp. A powerful muscle pulling on an under-adapted, stiffer tendon fails under eccentric load, the classic steroid user rupturing mid bench press.

What steroid use changes. It has consequences for the examination, the operation and the counselling:

• The drugs act systemically, so the other pectoralis, and other tendons, are also at risk: examine and counsel about the contralateral side, and be alert to a history of prior tendon ruptures
• The tendon is often of poorer quality, which can compromise suture purchase and is cited among the poor-prognosis factors; assess it intra-operatively and choose fixation accordingly
• Counsel on cessation, realistic expectations and modification of maximal single-rep lifting, because the underlying tendon vulnerability persists

Tietjen's classification, as modified by ElMaraghy, runs from a muscle belly strain to complete rupture of the tendon from the humerus; the modification adds subtypes for partial tears based on their extent. Which layer tears, and how far the tear runs proximally, is what the classification records. Type III is the most clinically significant and the most commonly reported in surgical series.

History. A sudden audible or palpable pop, or a tearing sensation, during the eccentric phase of a bench press or similar pressing movement. Sharp pain in the anterior chest or proximal arm settles to a dull ache, and weakness of pressing, adduction and internal rotation is immediate. Swelling and bruising develop over the following hours to days.

Examination. Compare with the other side throughout.

• Inspection - loss of the anterior axillary fold, asymmetric with the other side; the fold looks flattened or concave, a web-like deformity (webbing)
• Ecchymosis - over the anterior chest wall, the axilla and the medial proximal arm
• Palpation - a defect along the lateral chest wall or proximal humerus; the retracted muscle belly may be palpable medially
• Resisted adduction and internal rotation - tested with the arm forward-elevated; weak, and reproduces the pain

Radiographs. AP and axillary lateral views of the shoulder. Most ruptures are purely soft tissue and the films are normal, so their main job is to exclude other pathology. Look for a bony avulsion fragment from the lateral bicipital groove and for soft-tissue swelling; focal loss of the normal pectoralis major soft-tissue shadow on the AP view may suggest the diagnosis.

MRI is the gold standard and is indicated in all suspected ruptures. It shows discontinuity of the tendon at the humeral insertion, retraction of the muscle belly and the surrounding haemorrhage and oedema, and it places the tear as tendinous, musculotendinous or muscular.

• T1 and T2 weighted sequences in axial, coronal and sagittal planes
• T2 fat-suppressed sequences best demonstrate the tear and the fluid collection
• Axial T2-weighted images are the most useful for identifying the discontinuity at the humeral insertion

Why the detail matters. MRI accurately delineates the tear location, its extent and the degree of retraction, and that plans the operation: it determines whether direct repair is feasible or graft reconstruction will be needed. Tendinous avulsions are repaired directly to bone, while musculotendinous junction tears may require different reconstruction techniques. Do not delay MRI in a suspected complete tear, because the surgical window is time-sensitive.

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Ultrasound is the alternative for rapid bedside assessment when MRI is unavailable. It shows tendon discontinuity, haematoma and retraction, and it allows dynamic assessment, but it is operator-dependent and less accurate than MRI for tear extent and preoperative planning. The musculotendinous junction tear is the one that is easiest to miss on MRI and easiest to see on a targeted scan.

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The decision. For a complete tear (Type III) in an active patient or athlete, surgical repair is the treatment of choice, because conservative management leaves persistent weakness of adduction and internal rotation and a permanent cosmetic deformity. Conservative management is appropriate for Type I strains and partial tears in low-demand patients. The decision must factor in age, activity level, occupation and sporting demands.

Timing. Refer complete tears for surgical consultation urgently. Repair is ideally within 2 to 3 weeks and acceptable up to 6 weeks, and 6 weeks is the key threshold: beyond it, tissue retraction and scarring make repair more difficult and significantly compromise repair quality and functional outcomes. A tear that presents later is a delayed repair (6 weeks to 3 months) or a chronic one (over 3 months).

Rehabilitation is critical to a successful outcome. The protocol balances early motion, to prevent stiffness, against protection of the repair while it heals.

Milestones. Full passive ROM is expected at 6 weeks, and full active ROM, with strength training beginning, at 12 weeks. By 6 months the patient returns to sport with near-normal strength, and at 12 months has full strength and unrestricted activity.

Return to bench press. Light bench press at 3 months (50% body weight), moderate at 6 months (80% body weight) and heavy after 9-12 months. Maximal single-rep attempts are avoided permanently.

Strength and return to sport. Over 90% return to sport after acute surgical repair. Strength recovery is 95-100% after acute repair against 70-85% after chronic reconstruction, which also carries a higher re-rupture risk.