The shoulder is such an interesting joint, from so many points of view. At the most basic level, the skeleton of the shoulder is formed by a relatively large sphere (the head of the humerus) that rotates and glides on the surface of a relatively small dish (the socket of the shoulder joint or glenoid). The fact that the sphere is much larger than the dish explains why the shoulder has such a large range of motion in every direction. However, this difference in size also places the shoulder at risk for dislocation: the sphere can fall out of the socket. Most commonly, the sphere comes out in front of the socket, known as an anterior shoulder dislocation. In some individuals, the shoulder dislocates to the back, or posteriorly. The Latarjet procedure is a very successful operation for some individuals with recurrent anterior dislocations.
What keeps the shoulder joint in place so that it does not dislocate all the time? The labrum, the capsule and the muscles of the rotator cuff are most important to maintain the joint in place. The labrum is a rubbery flexible structure all around the socket. It makes the socket dish wider and deeper, and prevents the sphere to jump over the edge of the socket to some extent. The capsule connects the socket and the humeral head, restricting the amount of translation. The rotator cuff is a group of muscles that keep the sphere centered on the socket, amongst other functions.
What is damaged when the shoulder keeps dislocating in the front?
The very first time the shoulder dislocates anteriorly, the humeral head commonly tears the labrum and capsule off the socket rim. In Orthopedic Surgery, this disruption is called a Bankart lesion (Dr. Bankart was an orthopedic surgeon who noticed these injuries for the very first time). Sometimes, the humeral head chips off a portion of the socket rim along with the labrum and capsule. This is called a bony Bankart lesion. As the back of the humeral head comes in contact with the edge of the socket during the dislocation, the sphere can become fractured and depressed: think of the imprint left by a thumb pushing on a ping-pong ball; this fracture is called Hill-Sachs lesion (again honoring surgeons who noticed these injuries early on). In older patients, shoulder dislocation can lead to a rotator cuff tear as well and these are specially important to diagnose and treat as soon as possible.
All of these lesions can make it easier for the joint to continue to dislocate with minor injuries, or sometimes just by moving the shoulder. The labrum and capsule in the front can no longer avoid the sphere from moving excessively, and as the sphere rotates, the depression in the back can catch on the socket rim and dislocate the joint as well (when this happens, surgeons use the term engaging Hill-Sachs lesion).
Without treatment, individuals may suffer from many dislocation episodes. With each dislocation episode, the sphere may end up eroding the rim of the socket, and eventually the socket becomes much narrower than it should, which makes dislocation even more likely to happen. By the time some individuals consider surgery, there will be a lot of bone missing in the front of the socket. In these circumstances, simply fixing the labrum and capsule to the socket –the most common operation for patients with recurrent anterior shoulder instability- will just not work. The Latarjet procedure then becomes a surgical option.
Latarjet, Bristow, Eden-Hybinette,…
Dr. Latarjet came up with an interesting operation to correct anterior shoulder instability. The shoulder blade has a bony prominence that looks like a bent finger. It is called the coracoid. It serves as a take off point for muscles that either fine-tune the position of the shoulder blade in space (like the pectoralis minor) or flexes the elbow (like the brachialis and the biceps). In the Latarjet procedure, the coracoid is cut with a saw-blade, moved to the rim of the socket, and fixed to the socket with two screws. If you read more about the Latarjet procedure, you may run into other names. In the Bristow procedure, a smaller amount of the coracoid is secured to the glenoid at a 90 degree angle compared to the Latarjet procedure. They are both called coracoid transfer procedures. In the Eden-Hybinette procedure, bone from the waist line is transferred to the shoulder socket.
How does the Latarjet procedure work?
The Latarjet procedure improves shoulder stability two ways: (1) adding bone to the socket rim and (2) adding tendon support to the humeral head. The coracoid bone is wide enough to turn the socket to the normal width or even wider in most people. In addition, when the shoulder rotates into a position that could lead to dislocation, the tendons connected to the tip of the coracoid now function as a hammock to provide even more stability.
When will you be offered a Latarjet procedure?
The Latarjet procedure is most commonly considered for individuals who present a fair amount of bone missing in the front of the glenoid by the time they choose to undergo surgery. Although the amount of bone missing can be inferred from radiographs or magnetic resonance, it is best assessed in computed tomography with three-dimensional reconstruction (3D-CT scan). Your orthopedic surgeon will measure the amount of bone that is missing on your 3D-CT scan and will tell you if the Latarjet procedure is best for you. Making the socket wider with the Latarjet procedure may also compensate for an engaging Hill-Sachs lesion to some extent.
Some surgeons also consider the Latarjet procedure in two additional circumstances: when a previous repair of the labrum and capsule failed, or when it is very, very likely to fail. A number of factors make a repair of the labrum and capsule more likely to fail: very young age (under 20), participation in contact sports or other risky activities, and having very loose joints in general. Thus, if an individual has several of these risk factors, a Latarjet procedure is probably best.
What is the typical recovery time?
Actually, pretty fast. Since most of the time screws provides solid fixation of the coracoid to the socket, and the operation is done with just separation of muscle fibers, without really cutting through muscles, patients are allowed to start physical therapy within two weeks, and can be completely recovered in three months or less.
Any downsides?
Yes. The anterior rim of the shoulder socket is a deep structure, and the Latarjet procedure can be difficult to perform for the surgeon. Placing the screws in the right location can be difficult, especially in very muscular or overweight individuals. The many nerves around the coracoid are at some risk for injury. The transferred coracoid could also not heal, which is more likely to happen in people who smoke or patients with osteoporosis.