SHOULDER AND HIP ARTHROSCOPY: WHAT IS THE DIFFERENCE?
by Kenneth J. Westerheide, M.D.
With the growing popularity of hip arthroscopy, the masses are becoming more educated about the structures of the hip. News reports of famous athletes undergoing hip arthroscopy have brought these conditions into mainstream media. However, many terms and structures are similar to that of the shoulder, so what is the difference?
The hip and the shoulder are both ball and socket joints that have cartilage, ligaments, labrum, and a surrounding capsule. There are some differences between these joints that influence the treatment for injuries and painful conditions. The hip is much more constrained or inherently stable than the shoulder. The hip obviously is a "weight bearing joint" unlike the shoulder which introduces many differences. The shoulder is much more dependent on muscles connecting directly to the ball for movement and function, namely the rotator cuff, however, oddly enough, there are muscles of the hip that have been coined "the rotator cuff of the hip."
Some common pathology includes labral tears, instability, impingement, bursitis, "rotator cuff" tears and arthritis.
Labral Tears/ Instability
The labrum is a fibrocartilage structure that surrounds the "socket" of both joints. The socket of the shoulder is called the glenoid and that of the hip is referred to as the acetabulum. The labrum in the shoulder is responsible for acting as a "bumper" that the ligaments connect to and aid in stability of the shoulder. In the hip, the labrum acts as a gasket seal that helps to contain joint fluid but also helps in stability.
When the labrum tears in the shoulder it depends upon where the tear occurs, and the age of the patient as to the symptoms experienced. In patients less than age 40 with a traumatic injury where the shoulder dislocates (comes out of the socket) the labrum and connected ligaments often tear and the shoulder may continue to be unstable. These labral tears are treated with arthroscopy to reconnect the labrum and ligaments to "tighten" the shoulder and lessen the risk of dislocating again. A shoulder labral tear in patients older than 40 is often more degenerative and is treated with "debridement" or trimming the labrum to reduce pain.
The hip, however, is a much deeper joint and therefore has more inherent stability from the boney constraint of the deep socket. The hip rarely "dislocates" unless there is significant trauma such as a car accident. Labral tears of the hip are often experienced as groin pain, with catching and locking with rotation of the leg or hip. These tears can also be treated with arthroscopy to trim or repair the labrum.
The recovery after labral surgery for both joints depends upon whether the labrum was trimmed or repaired. If the labrum was trimmed or "debrided" a sling or crutches are used for 2 to 3 weeks. If the labrum is repaired, a sling or crutches are used for longer to allow the labrum to heal back to the socket, then physical therapy is intensified.
Impingement refers to two objects rubbing against one another. It occurs in both the shoulder and hip; however, the associated damage differs. In the shoulder, prolonged impingement classically occurs as "external impingement" between the rotator cuff and the acromion, the boney part of the top of the shoulder. This can result in "bursitis" (inflammation of the bursa), or even a tear of the rotator cuff. In the hip, however, impingement is referred to as FAI or "Femoral Acetabular Impingement" where the shape or orientation of the femur and acetabulum cause them to rub against each other. The labrum of the hip gets caught between these two bones and can tear and then damage to the cartilage can occur.
Impingement of the shoulder is treated with arthroscopy by trimming the acromion to make more room for the rotator cuff. The inflamed, swollen bursa is removed for pain relief. If the rotator cuff is torn more than fifty percent, it is repaired.
Impingement of the hip can come from extra bone on the acetabulum (socket) or the neck of the femur rubbing together. Often it is a combination of both. This can be treated by removing the extra bone to make more room between them and the labrum is either trimmed or repaired depending on the amount of damage.
Bursitis differs between the shoulder and hip. The bursa in the shoulder is on and around the rotator cuff and can become inflamed as described above. The most common area of bursitis of the hip, however, is on the outside or boney point of the hip called the trochanter and becomes inflamed due to a number of reasons. Hip bursitis is felt as pain on the outside of the hip and is often treated with a cortisone injection and stretching of the IT (Ileotibial) band, which is a muscle/tendon band that connects between the hip and knee. On rare occasions, this does not successfully treat the pain and the bursa of the hip can be removed with the arthroscope and the IT band can be released.
The shoulder has four muscles that make up the rotator cuff. They are responsible for elevation and rotation of the shoulder. Tearing of the rotator cuff is rare below the age of 40 unless trauma occurs. However, as we age, the rotator cuff becomes more degenerative and tears are more common. Studies have shown that up to 50 percent of people in their sixties have some degree of rotator cuff tearing. The hip has three muscles known as the abductors, or gluteus muscles, that have been referred to as "the rotator cuff of the hip". Tears of these muscles, most commonly the gluteus medius, occur in older individuals and are much less common than rotator cuff tears in the shoulder. Both shoulder and hip "rotator cuff" tears can be treated with the arthroscope through three small incisions or "portals."
Both the shoulder and the hip develop arthritis over time in many individuals. Arthritis is the wearing down of the smooth cartilage lining on the ball and socket of both joints. The arthroscopic treatments are limited for both joints but could be effective for removal of loose bodies and relieving mechanical symptoms. Advanced arthritis is best treated with replacement if conservative efforts are not effective.
If you experience any of these symptoms, discuss your options with your orthopaedic surgeon, who can help you determine the best course of action to improve your quality of life.