Introduction

Advances in technology have allowed for the arthroscopic treatment of an evolving series of conditions in and around the hip joint. Labral tears are the most common pathologies that are treated with hip arthroscopy, and they may contribute to the progression of degenerative arthritis. Patients who are at increased risk for developing arthritis in the presence of labral tears are those with developmental dysplasia, those with full-thickness chondral lesions, and those who have had tears present for more than 5 years. The key point to be emphasized is that surgical outcomes are significantly correlated with the extent of articular surface involvement and the degree of damage.

The labrum is innervated with all types of nerve fibers, including pain fibers, and thus tears of the labrum can result in hip pain in addition to mechanical symptoms of locking, catching, and buckling. The limited capacity of the labrum to heal in combination with the relative ease of the partial labrectomy procedure (as compared with labral repair) explains why partial labrectomy is currently the most commonly performed hip arthroscopy procedure.

Basic science and rationale for treatment

Microvascular studies have confirmed that the vascular supply of the acetabular labrum comes via the obturator artery, the superior gluteal artery, and the inferior gluteal artery, which are the same vessels that supply the bony structure of the acetabulum. These studies also showed no evidence of the penetration of vessels from the underlying acetabular bone into the labral substance. Labral tears most frequently occur on the articular nonvascular white zone, and they will not heal with conservative treatment. These tears are often delaminating tears that are not amenable to suture repair (Figure 13-1).

Figure 13–1 Intraoperative photo of a delaminating tear (arrow) of the anterior acetabular labrum. Articular cartilage, AC; labrum, L; femoral head, FH.

Labral tears are most frequently seen in the anterior acetabular quadrant (more than 90% in most series), and they are common in patients with degenerative hip disease or acetabular dysplasia. A common finding even with mild acetabular dysplasia is hypertrophy of the anterior labrum, which makes this area more susceptible to tearing. Because of the avascularity and degenerative nature of these lesions, they too are usually not amenable to suture repair (Figure 13-2). Posterior labral tears are most frequently seen after a posterior hip dislocation. Lateral tears are usually associated with additional labral and acetabular lesions.

Figure 13–2 Intraoperative photo of a hypertrophied (arrow), degenerative, torn anteromedial labrum. Articular cartilage, AC; labrum, L; femoral head, FH.

When a labral tear occurs at the watershed zone, over time, it destabilizes the adjacent acetabular cartilage. When the destabilized cartilage is subjected to repetitive loading, joint fluid is pumped beneath the delaminating acetabular cartilage, thus accelerating the wear. Eventually, the fluid burrows beneath the subchondral bone to form a subchondral cyst. Thus, most labral tears have a limited capacity to heal, and the resultant treatment is a partial labrectomy.

History and physical examination

Labral tears most often present with mechanical symptoms such as buckling, clicking, or catching and a painful and restricted range of joint motion. Mechanical symptoms (i.e., catching, locking, or buckling) usually persist despite normal radiographic findings and failed conservative therapy. Positive examination findings include a positive McCarthy sign. (The hip is flexed, externally rotated, and then brought into extension. This may be repeated with internal rotation.) Most often, the painful click will accompany extension. The patient may also experience pain or a sensation of blocked range of motion with abduction or external rotation. Often patients will experience inguinal pain with resisted straight leg raising. Labral tears can also be associated with other intra-articular disorders. Degenerative labral tears, as mentioned previously, are seen with erosive changes in the acetabulum, the femoral head, or both. Anterior acetabular chondral injuries are frequently seen with anterior labral tears.

Imaging and diagnostic studies

Radiologic studies including plain radiographs, arthrography, bone scintigraphy, computed tomography, and magnetic resonance imaging often have a poor diagnostic yield for intra-articular lesions. Although the addition of contrast agents in conjunction with computed tomography and magnetic resonance imaging may increase their sensitivity for evaluating intra-articular lesions of the acetabular labrum, these studies still have a limited ability to accurately evaluate chondral lesions of the acetabulum and the femoral head.

Occasionally an intra-articular joint injection with a steroid and Marcaine that is performed under fluoroscopic control may help to clarify whether the source of pain is intra-articular.