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Arthroscopic Technique for the Treatment of Pigmented Villonodular Synovitis of the Hip

Open synovectomy remains the treatment of choice for pigmented villonodular synovitis (PVNS) of the hip but has shown modest results compared with the treatment of other joints. Recent advances in hip arthroscopy permit a thorough evaluation of the joint surfaces, improved access, and decreased postoperative morbidity. We describe an arthroscopic synovectomy technique for PVNS of the hip. The use of additional arthroscopic portals and creation of a large capsulotomy enable successful visualization and extensive synovectomy of the entire synovial lining of the hip. The T-capsulotomy enables extensive soft-tissue retraction for complete exposure. The midanterior portal enables use of an arthroscopic grasper and shaver to directly access and excise the synovial lining of the peripheral compartment while avoiding damage to the medial and lateral retinacular vessels. Technical innovations in hip arthroscopy have enhanced visualization in the central and peripheral compartments, as well as instrument management and diagnostic evaluation of the capsule, therefore allowing enhanced management of PVNS of the hip.

P igmented villonodular synovitis (PVNS) is a benign, locally aggressive proliferative disorder of the synovium involving a joint, bursa, or tendon sheath. 1 It is characterized by exuberant proliferation of synovium, and although its etiology is unknown, it shows characteristics consistent with a neoplastic process. 2 PVNS most commonly affects individuals aged 20 to 40 years; the gender distribution of this disease is uncertain, with reports in the literature ranging from a 2:1 male-female ratio to a slight female predominance. 3 It has a predilection for large joints, with the knee involved in up to 80% of cases and the hip involved in 15% of cases, followed by the shoulder and ankle. 4 PVNS may occur in either a diffuse or a localized form; diffuse PVNS and localized PVNS are histologically identical but have very different clinical presentations. In the hip the disease typically presents as the diffuse villonodular type, but the localized type has also been reported.

Treatment Options
Treatment of PVNS typically involves early surgical resection to limit articular destruction and the potential for recurrence. Open synovectomy remains the treatment of choice for PVNS of the hip, 4 but it has shown modest results compared with the treatment of other joints. Mankin et al. 5 reported that 11 of 12 patients (92%) with hip PVNS required eventual total hip arthroplasty because of extensive joint damage. Similarly, Vastel et al. 4 reported high rates of revision surgery, osteoarthritis progression, and arthroplasty. Adjuvant external beam radiation and intra-articular radioisotope injection also have been proposed with promising results for specific indications.
Arthroscopy is widely used to treat PVNS of the knee and ankle, and it has been postulated that hip arthroscopy can provide successful treatment with less morbidity compared with open procedures. Hip arthroscopy is still in relative nascency; therefore there is a steep learning curve to obtain the appropriate exposure with arthroscopy. However, recent advances in the technique have permitted a thorough evaluation of the joint surfaces, improved access for synovectomy, and decreased postoperative morbidity. In a cohort of 32 patients with PVNS of the hip, Chen et al. 6 showed significant improvement in hip function and only 2 From Rush University Medical Center, Chicago, Illinois, U.S.A. recurrences of disease. Similarly, Byrd et al. 7 showed a significant increase of 27 points in modified Harris Hip Scores with no complications at 63 months in patients undergoing arthroscopic management for PVNS of the hip. In a recent long-term outcome analysis, arthroscopic treatment resulted in lower PVNS recurrence rates across all joints, mostly because of better joint visualization for tumor eradication. 4 The purpose of this article is to describe an arthroscopic technique for treating PVNS of the hip (Video 1, Tables 1 and 2).

Arthroscopic Surgical Technique
At our institution, the patent is placed in the supine position and general endotracheal anesthesia is initiated. Well-padded boots and an offset padded perineal post are placed. A sequential compression device is placed on the nonsurgical side, and preoperative antibiotics are administered before incision. Gentle traction in neutral extension using adduction maneuvers of the operative hip is applied until 1 cm of joint distraction is achieved, which is verified fluoroscopically (Hip Positioning System; Smith & Nephew, London, England).
The surgical area is subsequently prepared and draped in the standard surgical fashion.
Three portals are used for this procedure: anterolateral, midanterior, and distal anterolateral accessory (DALA) portals. These portals are created in standard fashion using cannulated instruments (spinal needle, guidewire, and metal trocars). Typically, the anterolateral portal is the viewing portal and the DALA portal is the working portal. Initially, an anterolateral portal is created under fluoroscopic guidance. The tip of the greater trochanter is identified, and an anterolateral portal is established approximately 1 cm anterior and 1 cm proximal to the anterior aspect of the greater trochanter. A spinal needle is introduced into the central compartment, followed by a guidewire and 4.5-mm metal cannula. By use of a 70 arthroscope (Stryker, Kalamazoo, MI) through this initial portal, a midanterior portal is created under direct visualization over the vastus ridge, and an arthroscopic shaver is introduced through this portal. Visual inspection of the central compartment should be performed before arthrotomy to determine the presence or absence of

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PVNS within the intra-articular space. An interportal arthrotomy using an arthroscopic scalpel (Samurai Blade; Pivot Medical, Sunnyvale, CA) between these first 2 portals is then performed with the use of a midanterior portal to gain access to the central compartment. The length of the incision will depend on whether the disease is focal or diffuse (longer for diffuse PVNS). The DALA portal is then established 4 cm distal to the anterolateral portal for instrumentation. Diagnostic arthroscopy is performed to characterize the extent of disease. The tumor may appear as a discrete mass (Fig 1A) or as a more diffuse villonodular synovitis (Fig 1B). If focal PVNS is identified within the central compartment, the mass can be retrieved with a Wishbone handle tissue grasper (Arthrex, Naples, FL) and removed from the field as a specimen. If diffuse PVNS is found, a 4.0-mm arthroscopic suction shaver (Tomcat; Stryker) may be used to perform a synovectomy in the perilabral areas (Fig 2). With placement of the 70 arthroscope in the midanterior portal, the pulvinar can be inspected to ensure that there is no evidence of diffuse PVNS that requires excision. Once the central compartment has been thoroughly inspected, a T-capsulotomy may be performed with an arthroscopic scalpel (Samurai Blade) to achieve better visualization and access to the peripheral compartment of the hip. With the arthroscope in the midanterior portal, traction can be released and the hip can be flexed to approximately 30 . A spinal needle, followed by a 5.0-mm metal cannula, may be placed in the DALA portal, which is 4 cm distal to and in line with the anterolateral portal. The T-capsulotomy is performed at the midpoint of the interportal capsulotomy and continued perpendicularly through the iliofemoral ligament to the intertrochanteric line, extending approximately 4 cm (Fig 3). A Wissinger rod is then placed through the anterolateral portal to retract the lateral leaflet of the iliofemoral ligament so that the entire synovial lining of the joint capsule can be visualized. By use of the DALA portal, the villonodular synovium is thoroughly debrided with a 4.0-mm suction shaver and tissue grasper (Fig 4). The T-capsular arthrotomy increases the mobility of the arthroscopic instruments, enabling the surgeon to reach the pathologic areas of PVNS within a wide range at least 180 and in most cases approximately 270 around the femoral head and neck (Fig 5). The extensile exposure in conjunction with manipulative articulation of the hip joint allows the surgeon optimal exposure of the synovial lining, and areas of synovitis that are otherwise inaccessible are readily visualized and debrided. If additional soft-tissue pathology, such as labral damage, is identified, repair, debridement, or reconstruction may be performed in the same setting. In addition, if abnormal osseous morphology, such as femoroacetabular impingement, is found, acetabular rim trimming or femoral osteochondroplasty may be performed.
Once all the procedures have been performed, it is imperative that a complete capsular closure be

Discussion
One of the foremost challenges of hip arthroscopy, particularly important in the setting of tumor excision, is obtaining adequate exposure. However, recent technical innovations have improved arthroscopic visualization. Specifically, the use of additional arthroscopic portals and creation of large capsulotomies enable successful visualization and resection of hip synovial proliferative disease. The T-capsulotomy enables extensive soft-tissue retraction for comprehensive exposure. Furthermore, the midanterior portal enables use of an arthroscopic grasper and shaver to directly access and excise the areas of pathology while avoiding damage to local neurovascular structures. In this way, technical innovations in hip arthroscopy have enhanced intracapsular visualization, as well as instrument management and diagnostic evaluation of the synovium. These improvements have been reflected in a recent systematic review that showed decreasing morbidity and complications in hip arthroscopy. 8 Literature on PVNS in the hip is sparse and primarily comprises case reports. Byrd et al. 7 recently published the largest clinical case series on arthroscopic management of PVNS of the hip in 13 patients with a mean follow-up period of 63 months. They reported favorable outcomes in this cohort and reported that the mean improvement in the modified Harris Hip Score was 27 points, with a range from 3 to 56 points, with similar improvement in patients with localized disease and those with diffuse disease.
Although arthroscopic management of PVNS has many advantages, caution must be exercised when deciding between arthroscopic and open excision of diffuse PVNS of the hip. Tumors in harder-to-access areas, such as the posterior capsule, may be best addressed with an open excision depending on the surgeon's level of expertise with hip arthroscopy. In addition, the recurrence rate for PVNS in any joint is variable and has been reported to be as high as 60%. Recurrence after the index surgery remains a primary complication, especially in large joints and for the diffuse type of PVNS. 9 However, studies on the recurrence rate in the hip are lacking. Vastel et al. 4 reported only 1 recurrence in a cohort of 16 patients undergoing complete hip synovectomy for PVNS; however, they also found a high incidence of secondary osteoarthritis.
PVNS of the hip is an uncommon pathology of the hip; however, it may be very locally destructive if present. Symptoms can usually be vague and insidious, prompting a high index of clinical suspicion. Diagnosis is typically suspected based on plain radiographs and magnetic resonance imaging findings and ultimately confirmed with biopsy (Fig 6). Arthroscopic management of hip PVNS has shown positive results, but caution must be used when selecting the appropriate patients for the procedure. PVNS, especially the diffuse variety, may be too extensive at the time of clinical presentation to be treated sufficiently with hip arthroscopy. For these patients, open synovectomy remains the treatment of choice. Further work is required to better characterize the arthroscopic treatment of PVNS within the hip.