Nashville Sports Medicine and Orthopaedic Center

There is a growing understanding of conditions that lead to joint deterioration and arthritis.  With this understanding, we are being able to implement strategies that could prevent, or at least slow this eventual progression.  For an individual with painful arthritis, it is clearly understood that the single most important preventative factor is activity modification by the patient to protect and preserve their joint.  For example, an avid runner may need to transition to low-impact activities such as swimming, cycling, or an elliptical trainer.  A golfer experiencing pain when walking 18 holes of golf may be better served by using a cart.  We must each take responsibility for looking after our own joints because any surgery in the presence of arthritis is unlikely to restore it to normal.

Labral tears are the most common injuries encountered during arthroscopy and can often be diagnosed by MRI. However, many of these will have associated articular damage which may not be detected until seen at the time of arthroscopy.  This articular damage is the main long term problem.  If the cartilage is broken down to exposed bone underneath, a procedure called microfracture can be performed.  Small perforations are placed through the underlying bone, creating vascular channels that can stimulate a cartilage healing response.  The body will not grow new cartilage, but can form fibrocartilage.  This is a blend of scar tissue and cartilage and represents the body’s best effort at cartilage reformation.  While the cartilage may be imperfect, it is superior to leaving the raw bony surface to rub against the opposite side of the joint.  The microfracture technique is performed arthroscopically and adds little to the procedure.  However, in order for this defect to heal, it requires a period of protected weight bearing for 8-10 weeks following surgery.  The initial healing cartilage tissue is like an immature scab.  If the scab is not protected, it will repeatedly break open, and healing is less successful.  We have experienced an 86% success rate with 2-5 year follow up in properly selected cases.  It is not effective for diffuse cartilage loss, but is better for focal defects with healthy surrounding cartilage.

Patients with dysplasia, characterized by a shallow acetabulum, are especially susceptible to articular breakdown of the acetabulum. Microfracture has been successful in this group, but these patients must also have a careful radiographic assessment to determine whether they might be better served by a more extensive open operation to improve the depth of the socket.  This is done by making cuts in the bone, repositioning the socket, and fixing it back with screws.

Femoroacetabular impingement (FAI) often referred to simply as “impingement” is another condition that can subsequently lead to cartilage breakdown.  There are two types:  A lip of bone overhanging the front of the acetabulum can pinch the underlying labrum and articular cartilage; and a bony build-up on the front of the femoral head can squeeze against the cartilage as the hip is flexed.  These can be assessed on x-rays, and with computed tomography (CT scan) which is a three dimensional x-ray of the hip showing its bony contour.  Impingement can be addressed with arthroscopic surgery by sculpturing down the front of the acetabulum and recontouring the shape of the bone around the femoral head.

For inflammatory arthritis such as rheumatoid disease, chemotherapy drugs are often used in an effort to arrest the synovial proliferation.  When these fail, arthroscopic synovectomy to remove the diseased synovium can aid in eliminating the progressive destruction caused by the diseased synovium.

Dysplasia

Dysplasia is a word of Latin origin meaning altered growth.  In this case, the hip joint develops with an altered shape and is present from early childhood or even at birth.  The most drastic example is a congenitally dislocated hip where the femoral head (ball) is dislocated outside of the acetabulum (socket) at birth.  Left untreated, this results in a severely deformed hip.  More commonly, the hip remains partially seated within the socket and only a mild amount of deformity ensues.  This is best characterized by the acetabulum being abnormally shallow in the way that it surrounds the femoral head.  Many people live with this condition their entire lives, never even aware that there is an abnormality.  However, depending on the severity of the deformity, some people are susceptible to developing arthritis and other hip joint problems that begin to manifest themselves during adulthood.

This dysplasia has three life-long effects.  First, because the acetabulum is shallow, there is less articular surface area over which to distribute the normal body weight that is carried across the joint.  This results in higher than normal compressive forces on the articular cartilage.  Overtime, the cartilage may not be able to withstand this force, and begins to beak down.  Second, during growth, the body attempts to compensate for this shallow bony socket by enlarging the labrum cartilage that surrounds its rim.   This enlarged labrum is under greater stress, from the weight bearing forces and can tear.  Also, because of its altered shape it can flip inside the joint, becoming entrapped, causing pain and more cartilage breakdown.  Lastly, because of the shallow socket, the femoral head tends to partially slip out of the socket.  This causes the ligamentum teres to elongate and enlarge, making it susceptible to rupture and becoming another source of pain.

Injury to the labrum, articular surface, and ligamentum teres, can all be addressed by arthroscopy.  However, the severity of the dysplasia must be carefully assessed on xrays. Sometimes an open operation is necessary to cut the bone and redirect the socket, creating a larger surface area for acetabulum. This may improve the hip mechanics and potentially result in more long-term preservation of the joint.

Femoroacetabular Impingement

The etiology of femoroacetabular impingement is variable.  It is most clearly attributed to developmental abnormalities of the hip that occur during the childhood growing years.  Perhaps, more commonly it is associated with osteophytes (bone spurs) that form during adulthood.  This condition is diagnosed with x-rays and sometimes aided by computed tomography.  The most easily diagnosed type is an abnormal shape of the femoral head and neck.  There is a prominence of the bone on the front of the femoral head so that when the hip is flexed upward this bony prominence engages with the front of the acetabulum, resulting in breakdown of both the labrum and articular cartilage.  The less distinct type is a lip of bone overhanging the front of the acetabulum.  Because of its location it is harder to see on regular x-rays.  The lip of bone pinches the labrum causing it to tear.  Many individuals may have this abnormally shaped bone without symptoms and do not require specific treatment.  Symptoms usually occur as a consequence of cartilage breakdown and if arthroscopy is needed to address the cartilage damage it then becomes important to assess for impingement as the underlying cause and it can be addressed at the same time.

Management of impingement has traditionally been described with open techniques.  The transition to arthroscopic treatment carries the advantage of a less invasive procedure.  This advantage is especially evident in more advanced cases.  Once the articular loss has become severe, correcting the impingement becomes less critical since the irreversible damage has already been done.  Sometimes it is simply hard to tell the severity of the articular loss prior to surgery.  Arthroscopy has the advantage of being able to assess this severity in addition to addressing the impingement.  If the joint is beyond help, at least the surgery has not been too extreme.