Major Ruptures

Fig. 12.1

Pectoralis major anatomy: cadaveric dissection

Pectoralis major is a powerful adductor and internal rotator of the arm with some additional contribution to forward flexion [4, 7]. For the majority of mundane daily activities, the muscle is not considered essential; however, for more strenuous activity and particularly sporting endeavours, it becomes a necessity for maximal power production [8]. The muscle itself is under most stress when eccentrically loaded in extension with the inferior segments tending to fail first in a predictable sequence [9].

12.3 Aetiology

PM tendon ruptures typically occur in muscular, young, adult males aged between 20 and 40 years. The deep part of the bench press manoeuvre, used for weight training, is the most frequently associated mechanism of injury [2, 9] (Fig. 12.2). A number of other demanding activities have also been reported to result in the injury, including rugby, wrestling, jujitsu, boxing and gymnastics [7, 9–12]. PM ruptures occur predominantly in males, the preponderance thought to be due to a lower tendon to muscle diameter and lower tendon elasticity, along with an engagement in higher energy activities than in females [1]. In a review of all reported cases before 2010, only 11 out of 365 cases occurred in females with an age range of 73–97 years; 10 of whom were nursing home residents [2]. The elderly, in general, form a less common subset of PM ruptures that usually occur during activities such as manual transfers [13].

../images/473070_1_En_12_Chapter/473070_1_En_12_Fig2_HTML.png — Fig. 12.2

Schematic diagram depicting the bench press manoeuvre most commonly associated with ruptures of the pectoralis major tendon. Note the extended position of the arm with eccentric loading of the muscle

An additional aetiological factor that is commonly associated with tendon ruptures, including those of the PM, is the use of anabolic steroids. Animal studies have suggested that anabolic steroids lead to alterations in collagen dysplasia and lower rupture stress values [14, 15]. It has also been suggested that with anabolic steroid use, there is a disproportionate increase in muscle strength relative to tendon strength [16].

12.4 Presentation and Diagnosis

Patients commonly present early to healthcare professionals and can usually recall the exact mechanism and time of injury, frequently describing a “snap” or “pop” at the time of injury. The diagnosis is may not be appreciated however, resulting in late presentation for specialist treatment, and a case must be made for raising awareness of such injuries.

In the acute setting, physical examination may reveal a degree of swelling and bruising over the upper arm and chest wall. In comparison with the contralateral side, a “dropped nipple” [17], medially retracted pectoralis muscle belly, and loss of the anterior axillary fold are pathognomonic features and will usually be evident in both acute and chronic settings (Figs. 12.3 and 12.4). These features can be accentuated by passively abducting the arm or with attempted resisted adduction [7, 17].

../images/473070_1_En_12_Chapter/473070_1_En_12_Fig3_HTML.jpg — Fig. 12.3

Early presentation with bruising, swelling, “bunching of the Pectoral”, and a dropped nipple

../images/473070_1_En_12_Chapter/473070_1_En_12_Fig4_HTML.jpg — Fig. 12.4

Late presentation with loss of anterior Axillary fold, dimpling of the skin, and retraction of the pectoralis major tendon

The diagnosis is usually clear from the presenting history and examination findings. Where there is any doubt, ultrasound assessment can be a useful adjunct but magnetic resonance imaging (MRI) is the preferred imaging modality. This will not only confirm the diagnosis but will provide information to aid in surgical planning, such as the degree of tendon retraction and presence of any intact portion of the tendon in the case of a partial tear [7]. Where an MRI is requested this should be done in consultation with a musculoskeletal radiologist so that the correct sequence, to image the entire Pectoralis Major, is performed. A standard shoulder MRI sequence will not suffice [18].

12.5 Management and Outcomes

Complex classification systems have been described for PM ruptures [2, 19], but the key factors that determine the most appropriate course of management and subsequent outcome are the age and activity level of the patient, the chronicity of the injury and the location of the tear along the muscle tendon unit [1].

In frail, elderly patients with a sedentary lifestyle, non-operative management is favoured. In certain partial tears and tears of the muscle belly rather than tendon, non-operative management may also be indicated [1, 4, 7]. Initial management involves rest in a sling, cryotherapy and analgesia with passive exercises instituted as tolerated, followed sequentially by active-assisted and active exercises over a 6-week period. Resistance therapy is subsequently implemented and unrestricted activity allowed at 8–12 weeks [4, 7]. In the case of partial tears treated non-operatively there may be no cosmetic deficit, though in the case of complete tears there is likely to be a permanently visible deformity [4].

Surgical treatment is the management of choice for active individuals [1, 2, 4, 20], providing the best opportunity for restoring motion, strength and cosmesis to approach pre-injury levels [4, 7, 16, 21]. Ideally, surgery is instituted acutely, as there may be a degree of tendon retraction evident by as early as 3 weeks [1], highlighting the importance of early referral to a specialist with an interest in these injuries. Good results are still achievable in the delayed setting and should still be considered, particularly where there is a functional deficit [1, 2, 4, 7, 20]. In the majority of cases a direct repair is possible with a variety of techniques described, including the use of anchors, buttons and trans-osseous sutures, though none of these techniques have been clearly shown to be superior to the other [1, 8, 22]. In the chronic setting, where a direct repair is not possible, additional releases and grafting techniques may be required [1, 23–28].

The surgery is usually undertaken through a skin crease incision in the deltopectoral groove, which achieves a cosmetic scar (Fig. 12.5). The authors prefer to use bone anchors to achieve repair. A safe range of motion is determined at the time of surgery, which helps inform the postoperative rehabilitation regime. Following surgery, the patient is initially placed in a sling. Rehabilitation regimes are personalised and based upon patient factors and characteristics of the tear and repair. In most cases, active hand, wrist and elbow exercises are allowed immediately. Early closed-chain mobilisation for the shoulder is started within the safe range determined at surgery. In general, external rotation and abduction is avoided initially. Over a variable period of 3–6 weeks, the sling is weaned off and progression aimed at instituting active motion. Return to sports and unrestricted activity is usually achieved between 3 to 6 months from the time of surgery.