The subscapularis tendon is located at the anterior part of the shoulder and is one of the four tendons that make up the rotator cuff of the shoulder. It is the strongest tendon of the rotator cuff and its function is to assist shoulder joint movements, such as the inner rotation of the humerus, which occurs when the upper extremity moves towards the torso during movement e.g. a strike in tennis or swimming.
ETIOLOGY – HOW IS THE SUBSCAPULARIS TENDON INJURED?
Subscapularis tendon injuries are relatively rare. Most ruptures of the rotator cuff relate to the tendon of the supraspinatus or the infraspinatus in the upper and posterior part of the shoulder joint. Subscapularis ruptures occur after injury (e.g. fall) and usually affect younger patients compared to those who suffer a supraspinatus rupture. Rupture of the subscapularis tendon can also occur after surgery, such as a total shoulder arthroplasty, in which the subscapularis tendon is cut and then stitched as a part of the surgical procedure.
A 46-year-old truck driver fell off his truck and in his attempt to avoid falling he grabbed with his right hand the truck door. He reported that he felt a tear, severe pain and weakness. Clinical examination revealed typical findings of subscapularis tendon rupture.
MRI imaging depicted a subscapularis tendon rupture and a subluxation of the long head of the biceps.
The examiner is trying to push the hand outwards (yellow arrows) while the patient is resisting. The internal rotation on the injured side is weaker (black arrow), so the patient’s hand can be pushed outwards more easily.
From the healthy side the patient is able to raise his hand from behind (picture on the left with a yellow arrow). On the injured side the patient is unable to raise his hand (picture on the right with a yellow arrow). (Lift-off sign)
Since the tendon of the subscapularis performs a very important part of the normal shoulder movements, its rupture is usually surgically treated. In the majority of cases, the arthroscopic method is preferred. This type of surgery can be performed with regional anesthesia (nerve blocking) and the patient is discharged from hospital on the same day. The procedure involves locating the tendon, mobilizing it and fixing it to the lesser tubercle. This is achieved with special tools and the use of arthroscopic surgery. Initially, the fixation point is roughened to promote tendon healing on the bone. The anchors are then inserted into the bone. The sutures from these anchors pass through the tendon to be stabilized on the bone.
It is important to protect the operated limb for at least 4 weeks after surgery. For this reason, the limb is fixed with the help of a special suspension folder and physiotherapy cannot be started before the end of these 4 weeks. At the end of this period, the suspension folder is removed and shoulder movement can be allowed to the patient. This is followed by physiotherapy consisting of active and passive exercises under the supervision of the physiotherapist. After 12 weeks, shoulder strengthening begins gradually and after 16 weeks, the patient can return to sporting activities such as tennis, golf, and swimming. Team contact sports are avoided for at least 24 weeks after surgery.
SUBSCAPULARIS RESTORATION AND PREDICTIVE FACTORS
The most important factors for the success of the surgical procedure are the quality of the tendon and the patient’s cooperation during recovery with the gradual return to daily activities. Some of the most important factors affecting the qualitative characteristics of the tendon are delay in surgery and smoking. Clinical experience has proven that patients undergoing surgery within 6 months of injury perform better.
Smoking also affects the quality of tissues, since after rupture the tendon may degenerate as a result of the effect of chemicals in tobacco. Finally, early active movement and overuse of the shoulder can also lead to a new subscapularis tendon rupture. Based on the literature, the results of surgical repair are excellent. Over 90% of patients report significant improvement in pain and strength after surgery.