INSTABILITY OF THE GLENOHUMERAL JOINT
The Normal Glenohumeral Joint
The normal glenohumeral joint consists of multiple bones, tendons, and ligaments structures that work together to form the most mobile joint in the body.
Multidirectional Glenohumeral Joint Instability
Multidirectional instability (MDI) is a common condition affecting the shoulder joint. It may be a bilateral occurrence and is usually atraumatic in nature. MDI is characterized by diffuse capsular laxity due to inadequate ligament structures. This laxity is referred to as MDI because of the increase in mobility of the glenohumeral joint (ball and cup of shoulder) in all directions. However, there may be a specific direction in which most difficulties arise. These being anteroinferior and posteroinferior.
Making the Diagnosis
MDI is most often a clinical diagnosis.The practitioner will first obtain a proper history of the patient's shoulder pain or stiffness. Important information consists of the onset of the symptoms, if there was a specific injury, the duration of the symptoms, the location of the symptoms, and prior medical health conditions. Previous treatment modalities should also be discussed. This may include physical therapy or anti-inflammatory medications. Radiographic studies may be obtained to further investigate the patient's symptoms.
The one most common symptom of MDI is pain. Patients with a history of MDI usually complain of a sore shoulder that worsens with activity or specific arm movements, such as overhead activities, carrying items, overuse, or recent injury. Other less common symptoms include relative instability episodes (dislocations or subluxations) or mechanical signs of catching or locking in the shoulder joint. Signs and symptoms vary in course and severity. The patient may notice that past episodes of instability are relieved with rest and arm support.
Most patients usually do not describe one specific traumatic episode with obvious dislocation, but they may provide symptoms of shoulder looseness. Athletics may aggravate MDI especially in sports with high demand of the shoulder including swimming, throwing, volleyball, or gymnastics.
On physical examination, the patient's shoulders generally reveal symmetrical findings. Range of motion is usually within normal limits, but the shoulder may be hypermobile. A good physical examination is likely if the patient is able to fully relax. Hyperlaxity may be shown through a positive sulcus sign (inferior laxity), anterior and posterior capsule testing.
Routine x-rays may be obtained but are most often negative. If a traumatic instability is present, then a Hill-Sachs lesion may be seen on the humeral head. MRI evaluation may demonstrate abnormalities of the labrum (cartilage that encircles the cup of the shoulder) and generalized capsular laxity.
Initially, the treatment method consists of supportive care with emphasis on strengthening the rotator cuff and scapular muscles. Anti-inflammatory medication and ice may also be used as an adjuvant.
If there is a recurrence or failure of conservative methods, then surgical intervention is entertained. This is performed as an arthoscopic procedure through small incisions. During surgery, the shoulder capsule is tightened by either electrothermal shrinkage (heat) or suture techniques (referred to as a capsulorraphy). Other soft tissue structures are identified and injury to them addressed. Most common associated procedure is repairing the labrum to the glenoid (cup of shoulder) through a Bankart or SLAP repair.
The Day of Surgery
This surgery is usually completed on an outpatient basis. The arm is supported with an immobilizer. The length of time needed in the immobilizer depends on the surgical procedures completed. A dressing and ice applied to the incision site. Ice is important to help reduce swelling of the shoulder.
The patient returns home and is advised to schedule light with any activities. The patient will been seen in the office for a post-operative visit around 10 to 14 days following surgery. At this time, the incisions are checked and range of motion evaluated. After this first office visit, formal physical therapy is then started. The number and frequency of therapy sessions depends on the progression of the patient's recovery. Physical therapy is essential in maintaining the balance between having too tight or too loose of a shoulder. Continuing the stretching and strengthening exercises are vital components of the recovery process.
Patients are in formal physical therapy for the next several weeks after surgery with the duration depending on how quickly the patient's recovery is progressing. Initially, the patient will attend therapy 2 to 3 times a week; however, most of the shoulder rehabilitation exercises are completed on your own at home.
Once the patient is able to complete the therapy exercises on his or her own, then he or she will continue the stretching and strengthening exercises at home for the next several months.
Article by Paul A. Nitz, M.D.