Pectoralis major muscle and tendon tears: diagnosis and grading using magnetic resonance imaging

Objective. To assess the accuracy and utility of magnetic resonance (MR) imaging in the detection and grading of pectoralis major muscle and tendon tears.Design and patients. A retrospective review was carried out of 10 patients referred for MR imaging for suspected pectoralis muscle injury and possible operative therapy. The pectoralis muscle and tendon were imaged using thin (3-4 mm) axial sections with a variety of sequences combined for anatomical delineation (T1-weighted SE or PD SE) and fluid detection (T2-weighted SE, T2-weighted FSE with fat suppression, or STIR). Surgical correlation was available in six patients. Clinical follow-up was available in four patients treated by nonoperative therapy.Results. MR imaging identified five complete tears, four partial tears and one normal tendon. One complete and one partial tear were at the myotendinous junction. The remaining seven injuries were at the enthesis. Surgical correlation consisted of five complete tears and one partial tear. One complete and one partial tear were at the myotendinous junction with the remaining four complete tears at the enthesis. The MR interpretation and surgical findings were in agreement in all six cases. All four patients treated with nonoperative therapy demonstrated improvement at a clinical follow-up examination, with restoration of function and strength consistent with a healed prior partial injury.Conclusion. MR imaging is accurate and useful in detecting and grading tears involving the pectoralis major muscle and tendon, facilitating the identification of patients with complete tears who are candidates for operative therapy. (orig.)