Patients
Between April 2006 and June 2019, endoscopic release of the pectoralis minor tendon was performed in a series of 11 shoulders with pectoralis minor syndrome using the same surgical technique. All patients had previously undergone conservative treatment with a specific physiotherapy program. Surgeries were performed by four different surgeons. Patients who underwent endoscopic release of the Pm tendon in conjunction with other procedures, such as shoulder reconstruction for dysplasia or formal brachial plexus neurolysis, were excluded from this study in order to isolate the potential benefit of Pm release for this particular syndrome. One patient (1 shoulder) was lost to follow-up. The remaining 10 shoulders (10 patients) are reported in this study. The median follow-up time was 14 months (6 to 49) months.
There were six females and four males with a median age at the time of surgery of 42 (range from 20 to 58) years. Three patients recalled a traumatic event (one patient had sustained a proximal humerus fracture and two patients had suffered a traction injury to their arm) possibly linked to the initiation of their symptoms. Three shoulders had undergone surgery previously for capsular release, biceps tenodesis associated to rotator cuff repair, and acromioplasty with biceps tenotomy respectively. Two patients had a concomitant capsular release together with the endoscopic pectoralis minor release, one had a suprascapular (SSN) nerve release, and one had a revision of the previously done biceps tenodesis.
At the time of presentation to their treating orthopedic surgeon, all patients complained of vague pain on the anterior shoulder region centered over the coracoid process and medial to it. We classify the pectoralis minor syndrome in three grades: Grade I (muscular Pm syndrome), Pm abnormalities associated to isolated scapulothoracic abnormal motion (STAM) without neurologic symptoms; Grade II (neurological Pm syndrome), Pm abnormalities lead to intermittent or constant compressive brachial plexopathy, with or without STAM or vascular compression; Grade III (multifocal thoracic outlet syndrome), Pm abnormalities contribute to compression of the brachial plexus and/or brachial vessels in the setting of double or triple crush at the interscalene triangle or costoclavicular space. Four shoulders were categorized as grade I (Fig. 1A), and six as grade II (Fig. 1B).
Patients with grade II complained of intermittent paresthesia involving various areas of the ipsilateral upper extremity. Symptoms were reproduced with direct manual compression over the location of the pectoralis minor, with a positive Tinel sign on this location. Physical examination was completed to exclude compression of the brachial plexus at the interscalene triangle. None of the patients included in this study had a frank abnormal distal vascular examination with thoracic outlet syndrome maneuvers.
All shoulders were evaluated with plain radiographs, and all patients presented with a prior shoulder MRI. No additional studies were performed. To be considered for surgery, patients with the clinical diagnosis of pectoralis minor syndrome had to have failed 6 months of physical therapy, including shoulder horizontal abduction stretching exercises -such as the unilateral corner stretch exercise-, and scapular stabilizing exercises.
Surgical technique
All surgeries were performed in the beach-chair position with the patient under a preoperative interscalene brachial plexus block and general anesthesia. Standard arthroscopic equipment was used, including a 30-degree arthroscope, an arthroscopic shaver, and an arthroscopic radiofrequency ablation device.
After a standard diagnostic arthroscopy, bursoscopy, treatment of other associated pathology was performed when indicated. The arthroscope is placed in the lateral subacromial portal. The anterior bursal tissues are removed with a shaver or radiofrequency ablation device in the space between the anterior deltoid and the subscapularis in order to visualize the lateral aspect of the coracoid and the lateral conjoined tendon (Fig. 2A). Maintaining the shoulder in flexion with the help of an arm holder will relax the anterior deltoid and provide a larger anterior working space.
An anterior portal is then established under direct visualization at the level of the coracoid process from medial to lateral and slightly inferior to the tip of the coracoid from superior to inferior. The arthroscope is inserted through this portal, visualizing the coracoid process directly in front, the acromioclavicular ligament laterally, and the tendon of the pectoralis minor medially (Fig. 2B). A more medial working portal is established under direct vision.
A blunt instrument, such as a blunt Steinmann pin or the blunt end of a Howard periosteal elevator, is introduced through the medial working portal to identify and dissect the superior and inferior margins of the Pm tendon. Care is taken to avoid injury to the brachial plexus and vessels and to identify any abnormal adhesions. Next, a radiofrequency ablation device is used to detach the tendon of the Pm subperiosteally off the medial aspect of the coracoid with the thermal end facing superiorly and laterally (Fig. 2C-D). Complete release of the Pm tendon with medial retraction of the free Pm is confirmed under direct vision.
Postoperative management
After arthroscopic release of the Pm tendon, patients are provided with a sling that may be used for comfort over the first day or two. Sutures are removed at week two postoperatively, and physical therapy exercises are initiated for motion and strength. Particular attention is paid to improve the strength and coordination of the periscapular muscles.
Evaluation
All patients were evaluated prior to surgery and at most recent follow-up regarding pain level using a visual analogue scale (VAS), subjective shoulder value (SSV), shoulder ASES scores, and quick-DASH scores. A retrospective review of the chart was completed to identify any complications or reoperations. Postoperative persistence of symptoms was considered a failure.
Statistical analysis
Data are reported using standard summary statistics, including medians for continuous variables, and counts and percentages for categorical variables. Comparisons between preoperative and postoperative values were performed using Wilcoxon test. Alpha risk was set to 5% (α = 0.05). Statistical analysis was performed with EasyMedStat (version 3.16; www.easymedstat.com).