Arthroscopic shoulder surgery for the treatment of rotator cuff tears: why, when and how it is done.

Figure 1. This patient displays a common gesture used to describe the pain of a rotator cuff tear. Usually this is described as a ?dull?, ?constant? and ?toothache-like??particularly during evening hours.

Figure 2a. Anatomy of the rotator cuff. The four muscles that comprise the cuff are the supraspinatus, infraspinatus, subscapularis, and teres minor. (A) The shoulder as viewed from behind, with the supraspinatus, infraspinatus, and teres minor visible. Courtesy of Carol Teitz, MD, University of Washington.

Figure 2(B) The shoulder as viewed from the front, with the subscapularis visible. While all of the muscles can be torn, the most common tears involve only the supraspinatus and infraspinatus. Courtesy of Carol Teitz, MD, University of Washington.

Figure 3a. Magnetic Resonance Imaging (MRI) of the rotator cuff and corresponding arthroscopic views. Views of shoulders in two different patients. (A) Normal MRI image of the rotator cuff, the white arrow points to the supraspinatus tendon at its attachment to the head of the humerus (arm bone).

Figure 3b. Magnetic Resonance Imaging (MRI) of the rotator cuff and corresponding arthroscopic views. Views of shoulders in two different patients. The typical appearance of the rotator cuff in ?(A)? viewed through the arthroscope from below the cuff. The view is from the back of the shoulder joint looking forward.

Figure 3c. Magnetic Resonance Imaging (MRI) of the rotator cuff and corresponding arthroscopic views. Views of shoulders in two different patients. MRI image of a moderately torn rotator cuff. The red arrow marks the torn edge of the rotator cuff, note the ?wavy? tendon edge

Figure 3d. Magnetic Resonance Imaging (MRI) of the rotator cuff and corresponding arthroscopic views. Views of shoulders in two different patients. The typical appearance of the torn cuff in ?(C)? as viewed through the arthroscope. This view is from above the cuff, looking down at the torn edge.

Figure 4 A/B - The margin convergence technique for rotator cuff repair. Views from above the shoulder before (A) and after (B) margin convergence.

Figure 4c - View from behind shoulder, showing the cuff after side-to-side repair before fixation to bone. (Redrawn from Burkhart SS. Arthroscopic treatment of massive rotator cuff tears. Clin Orthop, 390:107-118.)

Summary

Overview

Tears of the rotator cuff of the shoulder are potentially painful and disabling conditions, and the treatments for these conditions vary widely depending upon the severity of symptoms and signs. The person with a rotator cuff tear can have a sudden (acute/traumatic) or gradual (chronic) onset of shoulder pain with or without weakness.  Although tears can occur as a result of a traumatic injury, many tears occur gradually and no specific injury can be recalled.  The pain is usually located at the front and side of the shoulder or upper arm, and is frequently described as having a “aching”, “burning” or “toothachy” quality.  The usually occurs with overhead motions, but can progress to the point that it is present with normal activities, or wake the patient during sleep. (Figure 1)

While most people have heard of the “rotator cuff”, many are unclear about why we have one and how it functions.  The term “rotator cuff” refers collectively to a group of four relatively small muscles that surround the “ball and socket” joint of the shoulder.  These muscles are called the supraspinatus, infraspinatus, subscapularis and teres minor. (Figure 2.)  One function of these muscles is to aid in the rotation of the arm around its long axis (as when one throws a Frisbee or passes a plate from side to side).  Another, perhaps more important function of the rotator cuff is to keep the humeral head (the “ball” of the joint, connected to the arm) centered in the shallow glenoid (the “socket” of the joint, which attaches the arm to the body).  When the larger muscles around the shoulder (the deltoids, pectoralis, latissimus, and others) move the arm, they tend to impart forces that act to displace the humeral head from the socket.  The rotator cuff muscles must contract to keep the ball and socket joint centered.  When the cuff muscles become weak, torn, or injured, they can no longer perform this centering function, and the abnormal motions affect the normal function of the shoulder.  This usually causes pain and weakness with shoulder motion.

Many patients will improve with appropriate rehabilitation of the rotator cuff.  However, some patients will have continued symptoms despite adequate rehabilitation and may require surgery.  Arthroscopic shoulder surgery should be used to both define and diagnose the exact nature of the tears.  In most cases, the problem can be treated using specially-designed instruments working through very small incisions with a minimum of discomfort and without the need for a hospital stay.

An experienced physician, therapist, shoulder surgeon or sports medicine surgeon can usually recognize the signs of rotator cuff problems.  While the rotator cuff can not be directly visualized on X-rays, there may be subtle signs on the bones of the shoulder joint that can suggest a problem.  If suspected, the diagnosis can almost always be made or confirmed using Magnetic Resonance Imaging techniques (MRI).  However, many different problems can present with shoulder pain, so a thorough clinical examination by an experienced orthopedic shoulder surgeon is recommended.  (Figure 3.)

For many people, a conservative approach with formal physical therapy and then a home-based strengthening program can resolve the pain, weakness and disability of a rotator cuff tear.  In fact, many persons who have documented rotator cuff tears will regain completely normal and painless shoulder function without surgery.  It should be emphasized that there are many people who have asymptomatic rotator cuff tears (they have no idea they have a tear)—having a rotator cuff tear does not automatically mean that one requires surgery to fix it.  However, certain people may require surgery to regain normal, painless shoulder function:

•  Persons who’s symptoms do not improve with appropriate physical therapy or rehabilitation
•  High-demand athletes after an acute injury
•  Overhead workers or laborers
•  Persons who have changes on X-ray or MRI that suggest that irrecoverable damage to the shoulder may occur if the shoulder mechanics are affected by the cuff tear.

Arthroscopic shoulder surgery, or shoulder arthroscopy is a valuable tool to treat rotator cuff tears.  Using the scope, an experienced surgeon who is facile with arthroscopic techniques can evaluate the entire shoulder joint and can usually fix the tear through very small incisions using specially-designed instruments and devices.  It is a common misconception that tears that are large should not be repaired arthroscopically—in fact the advantages of visualization and complete access to the tear make such large tears particularly amenable to arthroscopic repair.  The goals of repair are to restore normal and painless motion and full strength to the affected shoulder:

1.  the rotator cuff tear is identified and loose, degenerated, and frayed tissue around the cuff edge must be removed back to healthy tissue.  This process is called débridement.
2. The edge of the cuff tear must be brought back to its normal position without undue tension.  This process is accomplished using techniques called mobilization or in larger tears, a technique called margin convergence. ²(Figure 4).
3. The tear must be fixed into place using specially-designed suture anchors that allow the surgeon to approximate the cuff tear securely to the bone.   

The results are most predictable in the hands of a highly-specialized surgical team that is familiar with the various techniques and instruments and who perform this surgery often.  Such a team will maximize the benefits of the surgery and minimize the risks.  The procedure can usually be performed within a few hours under general (or nerve block) anaesthesia, and the patient can be discharged to home with a minimum of discomfort.  In addition, the scope allows the surgeon to take pictures and video to show to the patient what problem(s) existed and how the problem was addressed. 

Video 1:  A diagnostic arthroscopy of a left right shoulder as viewed from the back of the joint looking to the front. This patient has mild, partial thickness fraying at the rotator cuff insertion (this tear is analogous to the tear shown in the diagram in Figure 5).

Patients undergoing arthroscopic rotator cuff repair still require a limited period in a sling (usually 4- to 6-weeks) with some simple range-of-motion exercises at home.  They will require fairly intensive outpatient physical therapy for re-establishing pain-free motion and strengthening the shoulder muscles for a few months.  Normally, a person can return to most forms of normal activity within 6 to 8 weeks, and limited athletics between 12 and 16 weeks.  A return to all activities and even contact athletics can usually be accomplished by 4- to 6-months, depending on the sport.

Surgery for Rotator cuff tears, arthroscopic, minimally-invasive and open management at the University of Washington, Department of Orthopaedics and Sports Medicine, Seattle, Washington

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