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January 20, 2012

Collateral Damage

Rounding Up the Usual Suspects: Hip Labrum Tears and FAI

by Corey Dawkins and Ben Lindbergh

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Among major-league players, treatments for torn labrums in the hip are on the rise. In our database, only eight major leaguers underwent surgery on their hips from 2002-2006. From 2007-2011, 33 players had a hip procedure performed. Improvements in surgical technique and technology have significantly shortened the rehabilitation, making surgery a viable option in the middle of the season.

While hip arthroscopy has been around for many years, it has been only relatively recently that its role in treatment for athletes with femoroacetabular impingements and/or labral tears has significantly increased. Nevertheless, much like other conditions seen in baseball players, its frequency will continue to rise in the near future, perhaps limiting the severity of acquired osteoarthritis later in life.

Like the glenohumeral joint in the shoulder, the hip is a ball-and-socket joint, with the femoral head representing the ball and the acetabulum forming the socket. It also has a tough fibrocartilagenous labrum that serves as a buffer between the bones and deepens the socket. That’s where the similarities end, though. Designed for mobility, the shoulder has the most motion among all of the joints in the body, while the hip is built with much more restraint in mind. Standing upright, walking, and running would not be possible if the hip was built like the shoulder. Since the shoulder is so complex, it’s not surprising when it develops problems. Hip damage in athletes is more rare but can be just as serious.

The hip joint includes just two bones: the femur and the acetabulum on the ilium, one of the pelvic bones. The bony coverage is much more significant than it is in the glenohumeral joint, with the labrum further deepening the joint.

                          Source: Hfmhealth.org                                               Source: Orthopaedicclinic.com.sg      

We have learned over the years that when athletes suffer labral tears and hip pain, it’s due to something called femoroacetabular impingement, or FAI, for short. Caused by anatomical factors on the femur, acetabulum, or a combination of both, FAI has become more widely recognized in recent years. Other, less common factors are the degree of rotation of the femoral head on the long shaft of the femur, and the rotational position of the acetabulum itself.

Of the common reasons for FAI, one subtype that causes secondary labrum tears is called a “cam impingement.” In these cases, an extra area of bone (cam) arises off the head of the femur in the general area of the old growth plate, which decreases the joint space for the femur to move. The differences between a normal hip and a hip with cam impingement (blue arrows) are highlighted in the pictures and video below.

Source Lifebridgehealth.org

Source: Ernestschilders.com

Cam impingement is more prevalent in the athletic population and therefore is believed to be related to minor injuries to the growth plate during childhood or adolescence. Other conditions involving the hip joint have also been shown to be associated with FAI, but in high-level baseball players, cam impingement is a much more common cause.

A second subtype of impingement is termed pincer impingement. In these cases, the culprit is not a bump on the femur, but extra boney growth or a rotation of the acetabulum. When this occurs, it causes the same difficulties by decreasing available motion and causing contact with the femur earlier. One difference, however, is that the labrum is injured in a different pattern and over a greater area, as we see in the video below.

A third type of FAI occurs when both a cam lesion and a pincer lesion are found.

Source: Ernestschilders.com

It is important to note that impingement occurs in completely normal hips, as well. At some point in extreme ranges of motion, the edge of the femur and the edge of the acetabulum are going to collide. The difference between a pathologic hip with FAI and a normal hip is that the collision occurs earlier in the motion, sometimes much more so.

Impingement can often be present without the patient knowing it until there is tearing of the labrum or complete loss of cartilage in an area. As mentioned earlier, it is often a result of abnormal bone development at a young age that leads to the lesion. Therefore, once you get it, it doesn’t go away, and not much can be done to avoid future FAI if the patient remains active.

Once it does start to become a problem, common complaints include groin or anterior hip pain, and at times, wrapping around toward the back. The patient usually doesn’t remember a single episode that caused the pain to start—unless it was a high-velocity injury like a car accident—but instead, a gradual increase in frequency and intensity over time. He or she does experience pain in the same area after sitting for a long time. Painful clicking can be present due to mechanical symptoms of a flap tear. The patient also may complain of pain as a result of altered biomechanics during walking or exercise, which can cause significant inflammation and clicking surrounding the hip flexor tendons or the ITB tendon on the outside of the hip.

In the examination office, the clinician takes the hip through many different motions and tests. First, range of motion is tested, in particular these three: flexion, flexion internal rotation, and flexion external rotation. These are measured with the athlete supine on his or her back, with the hip and knee flexed to 90 degrees. The hip is externally rotated by moving the foot inwards and rotating the thigh while keeping the hip flexed at 90 degrees. The leg is then rotated in the opposite direction for internal rotation.

Source: Hipandkneeadvice.com – Flexion with Internal Rotation

Flexion internal rotation pictured above is often painful and limited to less than five degrees in cases of FAI. A modification to this test in cases where an impingement is likely involves bringing the leg across the body and into a more flexed position while internally rotating the hip. This can be helpful in clinically assessing how much of a problem the labrum tear or impingement is. These tests can also be positive if there is a torn labrum without FAI or hip flexor-related pain.

Diagnostically, multiple x-rays are taken to provide a good idea of the shape of the bones. Yes, there is radiation involved, but it is significantly less than that associated with CT scans, and MRIs are not as effective for the bony aspect. An MR arthrogram can provide excellent resolution of the soft tissue injuries in the hip, including the labrum, and thus is usually the next step after plain x-rays. Sometimes, the doctor injects an analgesic into the hip joint, along with a corticosteroid similar to cortisone. This lets the surgeon know whether the pain is originating from inside the hip joint itself.

If you want to see an example of what some of the new medical software packages can do to visualize impingement, check out the video below.

In addition to standard rest and physical therapy, viscosupplementation injections can be helpful in the short term when degenerative arthritis is present due to FAI. They don’t resolve the issue—that can be done only surgically—but they can allow the gliding mechanism to improve temporarily.

Surgically, open hip dislocation has been considered the gold standard, as it allows for direct, complete visualization of the joint. In cases of very large deformities, this is still considered the best treatment option. After the patient is prepped and placed into a specially designed table, a long incision (about eight to 10 inches) is made, usually on the side of the hip, to allow access. The leg is distracted in order to dislocate the hip joint itself, while at the same time carrying the dissection very carefully down into the hip joint itself.

If the issue is a rotated acetabulum causing a pincer impingement, the surgeon can free the acetabulum and then reattach it in a new position with three different screws. If the problem is excessive rotation of the femoral head, the surgeon can cut the femur, rotate it, and reattach it in a better-aligned position.

If there is no rotational deformity of the acetabulum or the femoral head, the surgeon shaves down the pincer lesion and reattaches the labrum to the acetabulum. In cases of cam impingement, the cam lesion is smoothed down, and the surgeon reshapes the area called the femoral neck, which is located between the femoral head and the rest of the femur.

Recovery from the more simple versions of the open hip surgical dislocation procedure takes at least 12 months, but the more advanced procedures, such as rotating the socket part of the hip, can take 18 months or more. As a result, sports medicine physicians try to avoid open hip surgical dislocation surgeries whenever possible, to limit the negative effects on a player’s career.

Hip arthroscopy is gaining popularity in the United States as more surgeons become comfortable with the procedure, but it has been popular for well over 10 years in Europe. Most of the time, all of the components involved with FAI can be addressed through arthroscopy, although there are very small areas that cannot be visualized. Repair of the labrum, shaving down the cam lesion, shaving the pincer lesion, and microfracture for articular cartilage injuries are all possible in hip arthroscopy.

A lateral portal is used for the arthroscope, while the other portals are used for the instruments. The premise remains the same as the open procedure, but with different-sized instruments and alternative techniques. While the joint is being distracted, a needle in inserted using specialized x-rays as a guide. The needle punctures the joint capsule and eliminates the vacuum seal that was present, allowing a greater degree of distraction to occur. A guidewire replaces the needle before a dilator is used to prepare the capsule for the arthroscope. The dilator is replaced by arthroscopic guides before finally introducing the arthroscope.

A second portal is used anteriorly to get the instruments into the joint. The process of needle to guidewire to dilator is repeated before the other instruments are used. If there is a pincer lesion present, the labrum is separated from the area before the bone is smoothed down to the appropriate size. The labrum is then repaired and reattached with sutures. From there, the cam lesion can be trimmed down to the appropriate shape.

If you are interested in viewing a full hip arthroscopy with a narrative—don’t worry, it’s not either one of us—check out the four videos below from Dr. Marc Wagner. It takes about 40 minutes, so make sure you grab a drink first.

Recovery time from hip arthroscopy is much shorter than open hip surgical dislocation surgery, even if the same amount of pincer or cam material is removed. In cases of hip arthroscopy, recovery generally takes about three to four months, but it may be stretched out to six months depending on the sport and the amount of bone taken down. Each surgeon’s protocol is different, but in general, a short period of using crutches and starting physical therapy follows the procedure. Impact activities can begin around the third month, but again, if the bones were shaved down, this may be pushed back to ensure that there is no damage to the blood supply in the bone. Regardless, this is still significantly better than the roughly 12-month minimum recovery from an open hip surgical dislocation procedure. On top of that, hip arthroscopy is now producing results just as favorable as the open procedure, if not more so.

The sudden rise in hip surgeries is going to continue now that the techniques have been honed in the United States. Such a significant difference in the length of rehabilitation—three to four months for an arthroscopy, versus one full year for an open procedure—almost guarantees that any active baseball player will have the hip arthroscopy.

Corey Dawkins is an author of Baseball Prospectus. 
Click here to see Corey's other articles. You can contact Corey by clicking here
Ben Lindbergh is an author of Baseball Prospectus. 
Click here to see Ben's other articles. You can contact Ben by clicking here

Related Content:  Labrum,  Torn Labrum

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