The shoulder or glenohumeral joint is a “ball-and-socket” joint that is formed by the head of the upper arm bone (humerus) and the glenoid fossa of the shoulder blade (scapula). The glenoid fossa, forming the “socket”, is small and barely covers a quarter of the head of the humerus.
This makes the shoulder an inherently unstable joint that is susceptible to dislocation or subluxation (partial dislocation), but to address this the glenoid has a rim of fibrocartilage, the glenoid labrum, that deepens to “socket” to provide greater stability to the glenohumeral joint. The labrum and the shoulder are further supported by the long head of biceps tendon that attaches to the upper part of the glenoid and the labrum and provides stability at the front (anterior) of the joint.
A superior labrum anterior to posterior, or SLAP, tear is an injury to the top (superior) part of the labrum near where the long head of biceps tendon attaches. A SLAP tear will involve the area in front (anterior) and behind (posterior) this tendon and can also involve the tendon.
SLAP tears can be as the result of acute trauma, such as a fall onto an outstretched arm, forceful pulling at the arm, or a shoulder dislocation. They can also be due to repetitive shoulder movements that can cause repeated microtrauma and result in labral tears.
This is commonly seen in athletes that are involved in overhead or throwing sports such as baseball or cricket. However, many SLAP tears in the general population are due to normal ageing processes and repetitive motion over time and can slowly develop in those over thirty years old.
The most common symptom of a SLAP tear will be pain in the shoulder that is typically worse with overhead movements, reaching, or lying on the affected side. The pain is described as dull and throbbing and can be felt deep in the joint. There can also be associated “clicking” and “popping” at the shoulder.
Instability is often reported with SLAP tears as the labrum is no longer providing adequate support and stability to the humeral lead. It might feel as though the joint will dislocate or sublux (partially dislocate), especially in overhead positions or when the hands are resting behind the head. Due to this pain and the feeling of instability the joint can lose range of motion and strength as the rotator cuff and scapula stabilisers become inhibited and stiff.
Athletes might notice a decline in their sporting performance and throwing athletes can develop a “dead arm” with pain, heaviness and weakness after throwing, which will impact their ability to throw at pre-injury levels.
An initial diagnosis of a SLAP tear is usually done through physical assessment performed by a doctor, physiotherapist, or Orthopaedic Consultant. An MRI scan or an MR arthrogram can be performed to confirm with diagnosis and the planning of further management.
There are many grades of a SLAP tear and each grade can be classified according to the extent of the tear and the various structures that are involved. MRI scans or MR arthrograms are helpful in trying to grade each tear.
There is evidence to support both conservative and surgical management for SLAP tears. However, the extent of the SLAP tear and factors such as age, general health and past medical history, smoking and alcohol history, and prior levels of activity and function can all impact the type of treatment and the prognosis for recovery.
Initially, most SLAP tears will be treated conservatively through a combination of pain medication and progressive rehabilitation. As the labral tear does not repair itself it is important that the rotator cuff and scapula stabiliser muscles be rehabilitated and strengthened so that they are able to assist with active joint stability and movement. As strength and confidence improves there should be a reduction in pain, increase in range of motion, and a gradual return to full function or sport.
If pain and the symptoms related to the SLAP tear do not improve with conservative management, or the grade of the tear indicates it, surgery might be considered and discussed as an alternative treatment.
Repairs of a SLAP tear are predominantly performed through keyhole surgery (arthroscopy) and the exact type of procedure will be determined by the extent of the injury. For the surgery to be successful it is essential that a rehabilitation program is completed post-surgery. This will help to improve strength, stability and movement, and aim to prevent re-injury.
A return to sport could be considered at four to six months following surgery if the surgeon and physiotherapist are happy with the recovery.