Introduction

SLAP (Superior Labral Anterior Posterior) lesions have become rather well described in the last few years. SLAP tears were only described in the late 20th century and became more established as a condition in early 2000s.

In the world of medicine, that’s a rather short amount of time! They are a very common cause of shoulder pain in athletic individuals and are one of the most common conditions that I treat.

To learn more about SLAP tears, basic knowledge of the anatomy of the shoulder joint is necessary.

Anatomy of the Shoulder Joint

The shoulder joint is made up of 3 bones: the shoulder blade (scapula), the humeral head and the collar-bone (clavicle).

Movements around the shoulder involve 3 separate articulations: the glenohumeral joint, the acromioclavicular joint and the scapulothoracic articulation. When the arm is raised, the majority of movement occur at the glenohumeral joint and the scapulothoracic articulation.

The glenohumeral joint is a ball and socket joint, comprising the socket (the glenoid) and the ball (the humeral head). Both surfaces of the joint are covered with an extremely smooth and rubbery cartilage (known as articular cartilage). The smooth surfaces create a frictionless articulation when lubricated with a small amount of joint fluid.

The glenoid is really a rather shallow socket. In fact, a dish is probably a more accurate description! This, however, is a design which is intended to allow the shoulder joint to have great range of movement. Unfortunately, the price of big range of movement is stability. You can probably image that a big ball sitting on a shallow dish will fall off very easily.

While that is true to a certain extent, the body has ways of preventing this from happening. A ring of cartilage attached to the rim of the glenoid helps to not only deepen the socket, but also serves as the attachment point of ligaments that help to hold the humeral head in place. This ring of cartilage is known as the labrum.

The view of the glenoid seen end-on further demonstrates the labrum. Note: Ligaments attaching the labrum and glenoid to the humeral head are not shown in order to allow readers to appreciate the importance of the labrum.

What is a SLAP lesion?

As mentioned in the introduction, SLAP is an acronym for superior labrum anterior posterior lesion. In this condition, the part of the labrum that is directly underneath the attached long head of biceps, together with part of the labrum to the front as well as to the back, becomes detached from the underlying socket.

Who gets SLAP lesions?

Sports injuries are the leading cause of shoulder dislocation. They are often seen in either throwing or overhead athletes. In countries where sports like baseball or handball are popular, these athletes often suffer SLAP lesions.

In Singapore where these sports are not so popular, I tend to see overhead athletes presenting with this condition. People who play sports such as tennis, badminton and volleyball are the most common patients I see with SLAP lesions.

How does a SLAP lesion occur?

There are a couple of theories currently. Some believe it happens when overhead throwing athletes torque their shoulders back when cocking their arms to pitch the ball hard. The extreme external rotation of the shoulder causes the humeral head to “peel” the superior labrum and the attached long head of biceps tendon off, resulting in a SLAP lesion.

Another theory is that the forceful follow through that occurs after throwing a ball or serving during a game of tennis, creates huge traction forces that causes the long head of biceps to pull on, and eventually tear the superior labrum.

What symptoms do a SLAP tear cause?

The most common complaints are pain and clicking. However, most patients do not have much pain at all with activities of daily living. They can actually go about their lives absolutely pain free and that includes lifting heavy loads.

However, they will get pain when they participate in sports that involve throwing like baseball, handball, dodgeball, water polo etc. They will also have pain with sports that involve a lot of overhead movements like tennis, badminton, volleyball etc.

Sometimes, patients may find that they pain is most bothersome when they first start playing. It may then mellow down a little throughout the game, but they may get a sore shoulder that lasts for a few days after the game. Others may find that they are no longer able to serve or throw as hard as they used to.

Many will also experience a clicking or clunking sensation with certain movements. In rare cases, patients may even get pain with daily activities.

What will the doctor do?

He will have a suspicion that you might have suffered a labral injury, after having heard your symptoms and your sporting activities. Examining your shoulder will help to further strengthen his suspicion but tests performed during physical examination are notoriously poorly accurate in diagnosis of SLAP tears. He will need to investigate further by way of an MRI scan.

Why do I need an elaborate MRI scan? How about an x-ray?

MRI scans are required to diagnose SLAP tears. Other investigations are either woefully inaccurate or outright useless! MRI scans are not elaborate at all and are actually extremely commonly performed these days.

Some doctors still prefer an invasive form of MRI scans known as MR arthrography. In an MR arthrography, the radiologist first injects a dye into the shoulder prior to performing the MRI scan.

While an MR arthrography does increase the accuracy of the scan slightly, I do not find it absolutely necessary. A “normal” MRI scan will suffice. This is especially true since MRI scans have a tendency to over-diagnose SLAP tears due to the fact that there are some anatomical variants in this area of the shoulder and some normal variants may mimic the appearance of a SLAP tear on MRI scans.

It is hence, very important, to see a doctor who is familiar with shoulders and shoulder surgery as a misdiagnosis will result in wrong treatment being advised! To learn more about MRI scans, please read the section on Investigations.

Will the SLAP tear heal by itself?

SLAP tears, as with many types of labral tears, do not often heal by themselves. It is postulated that the presence of joint fluid tends to flush away chemical factors that the body produces to effect healing, hence interfering with the labrum’s ability to heal.

How are SLAP tears treated?

Patients usually only have 2 options:
1. Leave it alone and perhaps try a course of physiotherapy. It is unlikely that physiotherapy will “heal” the SLAP tear but it may improve the shoulder dynamics, hence improving function and reducing pain
2. Repair the tear via surgery

What does SLAP repair surgery entail?

The surgery is performed under general anaesthesia and is done via keyhole surgery (minimally invasive surgery). Stitches are passed through the torn labrum and securely fastened to the glenoid using small implants known as suture anchors.

There are endless types of suture anchors and most perform similarly. Which type of suture anchors to use ultimately depend on surgeon preference and familiarity. To know more about keyhole surgery, please read the section on Keyhole Surgery.

What is the success rate of the surgery?

Chances of success are excellent! In excess of 90%! However, this is only true if the right diagnosis is made. The variety of anatomical variants in this area was not well understood for a while. This coupled with the fact that surgical techniques were not so advanced then resulted in suboptimal outcomes in the past.

These days, however, SLAP tears are so well understood, and shoulder surgeons are so familiar with the spectrum of SLAP tears, that surgical outcomes are excellent. In fact, repairing SLAP tears have become one of my favourite surgeries to perform!

Will I be able to participate in sports after the surgery?

Absolutely. The aim of the surgery is to restore stability to your shoulder, not just during daily activities, but also during sports.

What should I do now?

If you have managed to get to this part of this long article, your shoulder must be bothering you significantly! Consult your family doctor or see an orthopaedic specialist and he/she should be able to advise you accordingly.