Arthroscopy can address a spectrum of hip conditions

Patient selection and meticulous attention to technique are critical to optimizing outcomes.

Issue: June 2006

ByJoseph C. McCarthy, MD

The development of hip arthroscopy has given orthopedists the ability to evaluate, diagnose and treat an evolving series of conditions affecting the hip joint. The most common problems amenable to hip arthroscopy include labral tears, chondral lesions of the acetabulum or femoral head, loose or foreign bodies, synovial chondromatosis, injuries to the ligamentum teres, and impinging osteophytes.

However, arthroscopy is not recommended for patients with advanced degenerative arthritis, osteomyelitis, severe dysplasia, late stage osteonecrosis, or morbid obesity. Sources of referred pain from the lumbar spine, pelvis or extra-articular sources must be carefully ruled out prior to arthroscopic evaluation.

Hip arthroscopy can be performed as outpatient surgery. But proper patient selection along with meticulous attention to surgical technique are critical to optimizing surgical outcomes.

Figure 1: Gadolinium-enhanced MRI shows an oblique sagittal view of an anterior labral tear.

Figure 2: A patient in lateral position uses the Innomed Distractor.

Figure 3: The image intensifier shows the distracted hip with trochars placed in the joint.

Figure 4: The two main portals used are the anterior and posterior paratrochanteric shown after trocar placement. Saline infusion confirms the intra-articular location.

Images: McCarthy JC

Lateral approach

Most intra-articular hip problems are not detected with plain radiographs, bone scintigraphy, computed tomography (CT) and magnetic resonance imaging (MRI). For this reason, gadolinium-enhanced arthro-MRI has been developed to aid in diagnosing intra-articular hip pathology (Figure 1).

The crucial role of proper patient positioning and adequate joint distraction cannot be overemphasized in making hip arthroscopy a safe and efficacious procedure. It can be performed in either the lateral or supine position depending on the surgeon’s preference and availability of equipment.

The lateral approach with paratrochanteric portals allow excellent visualization of the articular surface of the acetabulum and femoral head using a 30° or 70° arthroscope (Figure 4). This approach passes through fewer muscle planes and avoids potential injury to the lateral femoral cutaneous nerve.

After superficial skin incisions are made, we use sheathed, conically tipped trocars to pass through the adipose tissue, fascia and muscle tissue. This technique protects all interceding neurovascular structures and muscle from sharp equipment and repetitive trauma during the exchange of instruments.

The hip capsule is also slightly thinner with this approach, but when entering the joint, we encounter a firm but gentle “pop,” followed by advancement of the trocar and sheath. Confirmation of intra-articular positioning with image intensification is recommended.

The hip must be distracted between 7 mm and 10 mm using a fracture table or dedicated distracter [Innomed] (Figure 2). Fluoroscopy can confirm adequate distraction and the position of the femoral head to accommodate safe portal placement and instrument insertion (Figure 3). It is not only important for visualization, but also to prevent scuffing of chondral surfaces. A well-padded perineal post is positioned and adjusted prior to applying traction. We apply axial traction via a carefully padded foot boot, with the heel firmly seated and secured.

Most labral and chondral lesions occur in the anterior quadrant of the hip and can be treated readily via the two primary portals of the lateral approach.

Clinical assessment

Patients who are candidates for hip arthroscopy will often have mechanical symptoms such as clicking, catching, locking or giving-way. Symptoms may be preceded by a traumatic event, such as a fall or twisting injury, or may have an insidious onset.

Labral tears are the most common cause of mechanical hip symptoms (Figure 5). Microvascular studies have shown avascularity at the labral chondral junction where the majority of lesions appear. For this reason, they do not heal biologically. Labral tears are most frequently found in the anterior portion of the joint and are often associated with chondral lesions. Treatment consists of judicious debridement back to a stable cartilage base. Although there are reports of suture repair of the labrum, there is no long-term outcome available.

The most frequently observed chondral lesion is the watershed lesion, which consists of a labral tear with separation of the labrum from the articular surface at the labral-cartilage junction (Figure 6). The lesions are difficult to detect and even more difficult to stage — even with MR arthrography. Surgical outcomes have been highly correlated with the extent of chondral damage; therefore, it is best to treat these lesions early.

Chondral lesions present with anterior inguinal pain and may or may not be accompanied by mechanical symptoms. Clinicians who see a case of intractable hip pain that does not respond to conservative treatment (ie, anti-inflammatories, rest, ice, physical therapy) but which does respond to an intra-articular injection with cortisone and/or a long acting anesthetic agent should suspect a chondral lesion. Chondral lesions are treated with chondroplasty and, depending on severity, microfracture drilling (Figure 7).

Loose bodies can also be associated with mechanical symptoms and, unless they are calcified, they are not detected on plain radiographs or MRI. In synovial chondromatosis, more than 300 loose bodies have been removed arthroscopically (Figure 8). These bodies are often clustered around the fovea and need to be morcellized to facilitate removal.

Arthroscopy can also be valuable for removing intra-articular third bodies, or after trauma for evacuating of hematomas and removal of chondral loose bodies.

Figure 5: An arthroscopic photo of an anteromedial bruised and torn labrum.

Figure 6: Arthroscopic photo with the probe demonstrating the “watershed lesion.”

Figure 7: Arthroscopic photo of an Outerbridge grade IV chondral lesion after being treated with chondroplasty and microfracture drilling.

Figure 8: Arthroscopic photo of a cluster of loose bodies congregated in the fovea as seen in a patient with synovial chondromatosis.

Images: McCarthy JC

Postop protocol

Following hip arthroscopy, most patients require crutches from two to seven days. Patients may progress to full weight-bearing as soon as comfort allows, and most are able to drive within 24 to 48 hours postop.

Activity is gradually increased as comfort permits. Aspirin is prescribed as an anticoagulant for the first four weeks after surgery. Patients should minimize twisting and pivoting motions for the first six weeks while the joint is swollen. Patients should also avoid early stair machines, leg press machines and deep squats. Depending upon the job and type of physical labor required, most patients return to work in four to seven days.

Again, it cannot be overstated that surgical outcomes are directly dependent on the extent of chondral cartilage involvement. If femoral and acetabular chondral surfaces are intact and the labral lesion is addressed, more than 90% of patients will have an excellent result.

Joseph C. McCarthy, MD, is a clinical professor of orthopedic surgery at Tufts University School of Medicine in Boston, and is the immediate past president of the American Association of Hip and Knee Surgeons.

For more information:
McCarthy JC. Hip arthroscopy: What problems does it solve? #25. Presented at 22nd Annual Current Concepts in Joint Replacement Winter 2005 Meeting. Dec. 14-17, 2005. Orlando, Fla.