Gwinn, David E. MD; Wilson, Kevin MD; Sracic, Michael K. MD; Hebert, Daniel J. MD
The pectoralis major acts to internally rotate, elevate, and adduct the shoulder. It has a broad double origin from the anterior thorax. The clavicular head originates from the sternal half of the clavicle. The sternal head originates from the anterolateral half of the sternum between the first and sixth ribs and includes muscle fibers from the cartilage of the true ribs. Fibers converge to form a 5-cm-long tendon that inserts on the crest of the greater tuberosity of the humerus at the lateral lip of the intertubercular groove, lateral and superficial to the biceps tendon. The tendon consists of 2 main laminae placed 1 in front of the other. The thicker anterior lamina consists of fibers from the clavicular head and uppermost fibers of the sternal head. It extends distal to the deltoid tendon. The posterior lamina consists of fibers from the bulk of the sternal head and deep costochondral origins. The costochondral fibers turn deep into the sternal fibers, giving the tendon a twisted appearance at its insertion.1 The insertion of the posterior laminae starts more proximal than that of the anterior laminae, with fibers extending to the shoulder capsule and across the intertubercular groove. The overlapping anatomy of the 2 laminae gives the insertional footprint a narrow triangular shape (Fig. 1).
Pectoralis major tears can lead to significant functional deficits and unacceptable cosmesis. Fortunately, the injury is rare, and operative management has shown excellent results. The incidence of pectoralis major tears is on the rise and is most commonly the result of strenuous eccentric muscle contraction during athletic maneuvers found in weightlifting, wrestling, football, rugby, and waterskiing. Anatomical studies have shown a mechanical disadvantage and disproportionate lengthening during the final 30 degrees of the eccentric phase of a simulated bench press. Complete tears involving both the clavicular and sternal heads are more frequent than partial tears.2 The inferior sternal fibers of the humeral insertion are most commonly affected in partial tears.3
The literature has consistently shown that surgical repair of complete tears and most partial tears produces results superior to nonsurgical management in patient satisfaction, strength, cosmesis, and returning to competitive sports.4 In a 2001 study, Hanna et al5 showed that surgical repair resulted in recovery of 99% of the peak torque to the contralateral shoulder, whereas in nonoperatively managed patients, recovery was only 56%.
Although a recent series published by Schepsis et al showed no difference between those injuries treated immediately (within 8 weeks of injury) and those treated in the long term, other authors have noted more difficulty and worse outcomes with delayed surgery.2,3 Specifically, chronic cases involved adhesions of the torn portion of the muscle. These adhesions hinder mobilization but, in some cases, can contribute to the success of delayed repair when retraction of the tendon is limited. Anbari et al6 described a repair on a 13-year-old injury that was only possible because the ruptured sternal portion of the muscle was scarred to the intact clavicular portion. Long-term repairs involve larger incisions for greater soft tissue dissections to find avulsed and scarred-down tendon ends. There is danger in deep dissection because the pectoral nerves lie deep and medial to the muscle bellies. Surrounding muscle bellies of the coracobrachialis, pectoralis minor, and serratus anterior are also at risk during deep surgical dissection. We have used transcutaneous electrical nerve stimulation (TENS) to define the anatomy intraoperatively to guide dissection.
Transcutaneous electrical nerve stimulation is the application of electrical current through electrodes placed on the skin to stimulate underlying neuromuscular tissue. Pain control is the most common application of TENS, and it has reported use in orthopaedics, physiatry, obstetrics and gynecology, and psychiatry with an excellent safety and complication profile.7-13 We have used this technique as an adjunct to the standard repair of pectoralis major tendon ruptures to aid the definition of anatomy. With stimulation of the injured pectoralis muscles in the operating room (OR), it is possible to localize the displaced and retracted tendon and to better define the surrounding anatomy. These findings can then be correlated with preoperative magnetic resonance imaging to further define the nature of the injury and guide the planning for repair.
It is important to consider the age, function, and cosmetic concerns of the patient with a complete pectoralis major tear. Partial tears and neglected complete tears with near-complete restoration of muscle strength after rehabilitation may be treated nonoperatively with good results.14 In an older or sedentary patient, nonoperative management may be appropriate with any degree of tendon rupture.4 Because the muscle is not required for activities of daily living, a relative contraindication to surgery would be any patient where significant medical comorbidities would lead to an unacceptable surgical or medical complication rate. Pain and inflammation should subside for weeks, and the residual weakness can be well compensated for by other shoulder girdle muscles, aided by physical therapy. An absolute contraindication for any surgery would be active infection.
Surgical correction is indicated when the patient is relatively active and healthy and desires maximal return of function. The patient may also desire a correction of cosmetic deformity. Although successful repair has been documented in chronic tears with a 13-year delay, most literature report that optimal results are obtained from short-term diagnosis and repair within 8 weeks of injury.6,15 In 2000, a meta-analysis of 112 cases of pectoralis major rupture repair reported that surgical repair resulted in excellent or good results in 88% of patients compared with 27% of those treated nonoperatively.2 In 2006, Roller et al16 reported results of 4 cases of tears at the musculotendinous junction, 4 cases of tear at humeral insertion, and 2 cases of tears of the muscle belly. Six cases were repaired immediately (within 1 week of injury). Four ruptures were repaired in the long term (6 weeks to 4 years from injury). One long-term repair required an extraanatomic repair. Seven of the 9 cases showed good to very good subjective and objective results, whereas 2 of the delayed repairs still had a cosmetic defect with a reduction in strength. In 2000, Schepsis et al17 reported the results of 6 acute injuries (2 weeks from injury), 7 chronic injuries, and 4 nonoperatively managed injuries followed from 18 months to 6 years. No statistically significant subjective or objective differences in outcome were found between immediate and long-term repairs. Composite subjective ratings of 96% in acute, 93% in chronic, and 51% in nonoperatively managed injuries were reported for strength, pain, motion, function with strenuous sporting activities, cosmesis, and overall satisfaction. Objectively, isokinetic strength testing showed that short-term operative patients had the highest adduction strength at 102% of the uninjured side compared with 94% for patients with long-term tears, and 71% in nonoperatively managed patients.
Our experience is that a delay of more than 2 weeks is associated with the presence of adhesions that may make identification and mobilization of the tendon more difficult.
At presentation, most patients can recall a traumatic event involving the shoulder or anterior chest, and most of these cases involve weightlifting or similar athletic activities involving forced abduction against resistance.17 The pectoralis major muscle belly is usually involved in cases of direct trauma such as motor vehicle accidents and crushing injuries. Meta-analysis has shown sports injuries most often involve humeral insertion, whereas work-related injuries commonly involve the musculotendinous junction.2
Thorough history and physical examination should precede any surgical intervention. The goal of the preoperative visit is to determine the extent and chronicity of the tendon rupture. Patients often describe a pop or tearing sensation and immediate pain and weakness. Immediately, there is localized swelling and ecchymosis in the arm and axilla, which may obscure the classic finding of loss of contour of the anterior chest wall or axilla. The patient usually has deficiencies in strength with adduction and internal rotation of the shoulder. Range of motion of the shoulder may be limited because of pain. Patients frequently treat the initial injury as a common sprain but eventually seek treatment because of persistent symptoms and decreased range of motion.4 Long-term tears may present with completely resolved ecchymosis and edema, clearly revealing the anterior chest wall soft tissue defect. Patients may be dissatisfied by the cosmetic deformity of the anterior axillary fold. This deformity can be better defined by abducting the arm to 90 degrees and directly comparing the axillary fold to the unaffected side. Isometrically pressing the palms together in a clasped-hands position may reveal a medially retracted tendon pulling on overlying soft tissues. In this position, the pectoralis major should be palpated for discontinuity from the humerus through the defect in the axilla. The anterior axillary fold is formed by the investing fascia of the pectoralis major, which conforms to the brachium and medial antebrachial septum. Sometimes, a tendon tear can leave the investing fascia as a thin cord replacing the full axillary fold.
Injuries can be described anatomically as to whether the sternal, clavicular, or both heads are involved and whether the tear is complete or partial. Tietjen15 proposed a classification system based on the extent and site of closed pectoralis major muscle injuries. Type I includes sprains and contusions. Type II is a partial tear. Type III injuries are complete tears, further subdivided by location to origin (A), muscle belly (B), myotendinous junction (C), or tendon (D). The author suggested that Type IIID injuries are the best candidates for surgical repair. The injury can also be classified more simply by the location of the rupture: Type 1 at the humeral insertion, Type 2 at the musculotendinous junction, and Type 3 at the muscle belly.16
Imaging techniques may be useful for injury assessment and preoperative planning. Conventional radiographs should be obtained to evaluate for bony avulsions, dislocations, or fracture compounding the injury if so dictated by the injury mechanism and associated findings. Comparative ultrasound can identify tears with adequate surgical correlation.2,16 Magnetic resonance imaging remains the modality of choice for clearly defining the extent and location of injury, muscle atrophy, and amount of tendon retraction.18,19 Landmarks for visualizing the humeral insertion on magnetic resonance imaging include the quadrilateral space or the origin of the lateral head of the triceps superiorly and the deltoid tuberosity inferiorly.20
The preoperative visit should include a discussion of the possibility of augmentation procedures with either autograft or allograft tissue. This is especially imperative in patients with long-term ruptures or patients with a history that may portend tendon compromise such as steroid use, rheumatoid arthritis, or diabetes.
General endotracheal anesthesia and standard perioperative antibiotic prophylaxis are used. The authors prefer a "beach-chair" position, with the use of a foot stop at the end of a bed and a safety strap at the waist. The operative arm is prepared free to allow full range of motion during the procedure. The contralateral arm is placed on a padded arm board and secured in a slight abducted position. Transcutaneous electrical nerve stimulation unit electrodes are placed on the skin overlying the medial muscle belly of the sternal head just lateral to the sternum and the clavicular head just distal to the clavicle and lateral to the manubrium (Fig. 2). These leads are covered with nonsterile drapes before prepping and the TENS unit is brought out over the unaffected extremity for access by nonsterile OR personnel.
A deltopectoral approach is used with the distal most portion of the incision extending lateral to the axillary fold. The bare insertion of the pectoralis major tendon is determined using standard anatomical landmarks. Identification of the ruptured tendon ends is started from lateral to medial. In cases where adhesions or retraction limits identification, the TENS unit is stimulated by nonsterile OR personnel. Neuromuscular stimulation causes contraction of the pectoralis major only, without cocontraction of the surrounding pectoralis minor, serratus anterior, or coracobrachialis. Preoperative spacing of the leads allows selective stimulation of the clavicular or sternal heads to assist identification. Once defined, blunt and sharp soft tissue dissection can be safely carried out to mobilize the tendon ends to the humeral insertion while minimizing trauma to surrounding muscles.
In cases where intratendinous tears have occurred, a tendon-to-tendon repair will be attempted. If a little insertional tendon remains for suture, reinforcement with suture anchors may be attempted. Alternatively, the remaining tendon insertion will be removed and direct tendon-to-bone repair will be used.
In cases where direct tendon-to-bone repair is used, a shallow triangular bone trough is burred to maximize the surface area for tendon-to-bone healing. Cortical bone at the corners of the triangle is instrumented with 5.0-mm metal suture anchors using number 2 FiberWire (Arthrex, Naples, Fla; Fig. 3). If the clavicular and sternal heads are clearly defined separately, then anatomic repair is attempted by using a locking Krakow stitch from the most proximal suture anchor through the confluence of the superior borders of the anterior (clavicular) and posterior (sternal) laminae and continued into the muscle belly if needed for additional support. The remaining free end of the suture is sparsely woven through the adjacent tendon and muscle. This portion of the suture is used as a pulley through the bone anchor to approximate the tendon to bone and is then locked into place with a whip stitch. Attention is then directed to the inferior border of the posterior (sternal) lamina, which is secured to the posterior apex of the triangular footprint using the same technique. If the laminae cannot be separated at this juncture, then the suture is placed, as previously described, through the central portion of the tendon encompassing both the anterior and posterior laminae. The most distal anchor is used to secure the inferior limbs of the anterior (clavicular) lamina. In cases where the tendon ends are inseparable, the same footprint is used with the proximal and distal apices anchoring the superior and inferior tendon borders, respectively.
Postoperative rehabilitation is similar for both immediate and long-term tear repairs. A standard sling should be worn for at least 4 weeks, possibly longer, depending on the degree of intraoperative mobilization required and the tension of the repair. Pendulum range-of-motion exercises are started immediately. Active and active-assisted range-of-motion exercises begin 4 to 6 weeks postoperatively, and strengthening is allowed when symmetrical full range of motion is obtained at the shoulders.
Although uncommon, possible complications related to surgery include infection, continued pain, unimproved weakness, nerve damage, and shoulder stiffness. Reports of complications or need for reoperation are limited in the published series. The authors have encountered no complications related to the transcutaneous muscular stimulation by the TENS unit; neither have complications been described in the literature when TENS was used for other indications.
We have used the TENS technique to define surgical anatomy in more than 10 cases. We initially used this technique for pectoralis tears with delayed presentations from 2 weeks to more than 1 year after injury. In many of these cases, the tendon retracts and rolls beneath the muscle, where it forms adhesions with the surrounding tissues. In all cases, the identification of the pectoralis muscle upon stimulation made dissection and localization of the torn tendons easier and, in our opinion, safer. We have not used this technique in acute tears or in partial tears where one of the pectoralis tendons is still intact. Although the surgical anatomy is usually easier to define in these cases, it reasons that the TENS unit could be used advantageously in these situations as well. Certainly, placing the leads preoperatively as a fallback option for difficult dissections would make sense. The senior author (D.J.H.) has since used this technique to guide dissections of the deltopectoral interval in total shoulder revision arthroplasty. This technique may have further applications in limited exposure surgeries such as mini open biceps tenodesis or at other anatomical locations with difficult anatomical approaches or previous surgical incisions.
1. Wolfe SW, Wickiewicz TL, Cavanaugh JT. Ruptures of the pectoralis major muscle. An anatomic and clinical analysis. Am J Sports Med. 1992;20(5):587-593.
2. Bak K, Cameron EA, Henderson IJ. Rupture of the pectoralis major: a meta-analysis of 112 cases. Knee Surg Sports Traumatol Arthrosc. 2000;8(2):113-119.
3. Alho A. Ruptured pectoralis major tendon. Acta Orthop Scand. 1994;65(6):652-653.
4. Petilon J, Carr DR, Sikiya JK, et al. Pectoralis major muscle injuries: evaluation and management. J Am Acad Orthop Surg. 2005;13(1):59-68.
5. Hanna CM, Glenny AB, Stanley SN, et al. Pectoralis major tears: comparison of surgical and conservative treatment. Br J Sports Med. 2001;359(3):202-206.
6. Anbari A, Kelly JD, Moyer RA. Delayed repair of a ruptured pectoralis major muscle. A case report. Am J Sports Med. 2000;28(2):254-256.
7. Osiri M, Welch V, Brosseau L, et al. Transcutaneous electrical nerve stimulation for knee osteoarthritis. Cochrane Database Syst Rev. 2000;(4): CD002823.
8. Jorgensen L, Nielsen LM, Kisling AK, et al. Transcutaneous nerve stimulation as palliative treatment of pain [Article in Danish]. Ugeskr Laeger. 1990;152(25):1809-1812.
9. Taylor DN. Clinical and experimental evaluation of cranial TENS in the US: a review. Acupunct Electrother Res. 1995;20(2):117-132.
10. Proctor ML, Smith CA, Farquhar CM, et al. Transcutaneous electrical nerve stimulation and acupuncture for primary dysmenorrhoea. Cochrane Database Syst Rev. 2002;(1): CD002123.
11. Cameron M, Lonergan E, Lee H. Transcutaneous electrical nerve stimulation (TENS) for dementia. Cochrane Database Syst Rev. 2003;(3): CD004032.
12. Burssens P, Forsyth R, Steyaert A, et al. Influence of burst TENS stimulation on the healing of Achilles tendon suture in man. Acta Orthop Belg. 2003;69(6):528-532.
13. Requena Sanchez B, Padial Puche P, Gonzalez-Badillo JJ. Percutaneous electrical stimulation in strength training: an update. J Strength Cond Res. 2005;19(2):438-448.
14. Potter BK, Lehman RA, Doukas WC. Pectoralis major ruptures. Am J Orthop. 2006;35(4):189-195.
15. Tietjen R. Closed injuries of the pectoralis major muscle. J Trauma. 1980;20(3):262-264.
16. Roller A, Becker U, Bauer G. Rupture of the pectoralis major muscle: classification of injuries and results of operative treatment [Article in German]. Z Orthop Ihre Grenzgeb. 2006;144(3):316-321.
17. Schepsis AA, Grafe MW, Jones HP, et al. Rupture of the pectoralis major muscle: outcome after repair of acute and chronic injuries. Am J Sports Med. 2000;28(1):9-15.
18. Carrino JA, Chandnanni VP, Mitchell DB, et al. Pectoralis major muscle and tendon tears: diagnosis and grading using magnetic resonance imaging. Skeletal Radiol. 2000;29:305-313.
19. Connell DA, Potter HG, Sherman MF, et al. Injuries of the pectoralis major muscle: evaluation with MR imaging. Radiology. 1999;210:785-791.
20. Lee J, Brookenthal KR, Ramsey ML, et al. MR imaging assessment of the pectoralis major myotendinous unit: an MR imaging-anatomic correlative study with surgical correlation. AJR Am J Roentgenol. 2000;174(5):1371-1375.
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