A 16-year old male patient visited the hospital complaining of pain of right hip joint starting from 2 years ago. The patient complained of inguinal pain and limping. Visual analogue scale (VAS) pain score was 8. In physical examination, anterior hip impingement test and Patrick test were positive. When the leg of the patient was rotated internally and extended distally, the snapping movement happened in his hip joint. Plain radiograph showed pincer type of FAI which has positive crossover sign of the acetabulum. On the frog leg lateral view, a bony protuberance was found at posteromedial portion of the femoral neck (Fig. 1). Computed tomography (CT) images showed cranially retroverted acetabulum and a bony tumor which located just above the lesser trochanter with a size of 1.7 cm by 0.6 cm (Fig. 2). On magnetic resonance arthrography images, labral tear at the anterosuperior portion of acetabulum and a bony tumor with cartilaginous cap at posteromedial area of femoral neck were demonstrated (Fig. 3). We observed snapping motion between iliopsoas tendon and bony tumor at peripheral compartment in ultrasonographic examination. Since the pain did not subside even after conservative treatment using non-steroid anti-inflammatory drugs and physical therapy for 6 weeks, arthroscopic management for FAI with labral tear and bony tumor was performed.

We put the patient under general anesthesia and took a supine position on the fracture table for traction of the hip joint. We treated problems of central compartment first, and the procedure for peripheral compartment was executed later. Anterolateral and anterior portal were established in ordinary manner. In whole procedure, 70° arthroscope was used only. After making two portals, we made transverse capsulotomy connecting anterior to anterolateral portal using arthroscopic knife. For visualization of bony tumor, transverse capsulotomy was more extended medially rather than usual capsulotomy. In arthroscopic findings, labral displaced tear was found at anterosuperior aspect of the acetabulum. Acetabuloplasty was performed using a 4.5 mm arthroscopic spherical burr (Conmed Linvatec, Largo, FL, USA) and acetabular labral repair using two 2.7 mm absorbable suture anchor (Bioraptor; Smith & Nephew, Andover, MA, USA) was performed at anterior and anterolateral portion of the acetabulum (Fig. 4). After the procedure of central compartment, the patient's hip was flexed to 60° and arthroscope was moved toward peripheral compartment, and additional capsulotomy using the hook type radiofrequency (Arthrocare; Arthrocare Corporation, Austin, TX, USA) was performed distally for easier access of arthroscopic instruments to peripheral compartment. After femoroplasty for decompression of FAI, we rotated the patient's leg externally and made his posture a frog leg position for arthroscopic visualization of medial portion where bony tumor was existent (Fig. 5). For resection of the tumor, we used anterior and anterolateral portal as working portal and viewing portal, respectively. We extracted bony specimens which contained cartilaginous cap and bony tissue for biopsy and remnant bony protuberance was removed completely using arthroscopic spherical burr. To prevent femoral neck fracture that might occur after tumor resection, whole procedure was performed under the guidance of the fluoroscopic image intensifier. Because of widened capsulotomy, arthroscopic capsular repair using 2-0 Ethibond (Ethicon, Somerville, NJ, USA) was performed for stabilization of the hip joint. Postoperative rehabilitation included continuous passive motion and pendulum exercise of the hip joint from postoperative 1 day and the patient was permitted non-weight bearing for 6 weeks after surgery.

Complete resection of osteochondroma was confirmed using postoperative X-ray and CT images (Fig. 6) and osteochondroma was pathologically confirmed (Fig. 7). The VAS pain score was decreased from 8 preoperatively to 1 postoperatively and the inguinal pain and internal snapping were disappeared completely at postoperative 3 month. At last follow up, modified Harris hip score was improved from 52 preoperatively to 90 postoperatively and hip outcome score of activity of daily living and sport related activity were improved from 58 and 56 preoperatively to 91 and 90 postoperatively, each. The plain radiography and physical examination at postoperative 1 year showed no recurrence of osteochondroma and internal snapping hip (Fig. 8).

After FAI and acetabular labral tear have gained attention as a cause of hip pain, arthroscopic treatment for lesions of the hip joint has improved remarkably ever since. Whereas arthroscopic treatment for the hip lesions mainly focused on resolution for problems of the central compartment in the past, the operative indications are extended to pathologies of the peripheral compartment such as cam type FAI, synovial osteochondromatosis, loose bodies, internal snapping hip, etc7). Recently, arthroscopic treatment for extraarticular hip lesions such as gluteus tendon tear, greater trochanteric pain syndrome, piriformis syndrome, external snapping hip, etc is being attempted. Although some cases about osteochondroma in the hip joint involved FAI and acetabular labral tear were reported45), there is not any report about that which occurred internal snapping hip. As the location of tumor was the posteromedial area of the femoral neck, that is superior portion to lesser trochanter, arthroscopic approach for resection of osteochondroma is difficult more than other cases8). The main problems of this case were acetabular labral tear and internal snapping hip. For treatment of pathologies of central compartment such as acetabular labral tear and pincer type FAI, we performed arthroscopic acetabuloplasty and labral repair with two bioabsorbable suture anchors (Bioraptor). Arthroscopic treatment for internal snapping hip by iliopsoas tendinopathy is usually performed around femoral head-neck junction. But, because snapping phenomenon of this case was occurred by bony tumor, resection of osteochondroma was needed for resolution of this pathology. Authors usually used ordinary anterior and anterolateral portal, but as classic transverse capsulotomy is not enough to secure the space for resection of tumor in the peripheral compartment, T-shaped capsulotomy forward peripheral compartment was performed for widening of operative field. Lee et al.9) have reported the results of arthroscopic treatment by medial approach using medial portal and the site of medial portal is close to the passing route of obturator nerve and artery. So, risk of neurovascular injury can be not excluded, completely. In this reason, arthroscopic resection of bony tumor of far distal portion of peripheral compartment through widened T-shaped capsulotomy was attempt and we obtained successful result.

Complications of arthroscopic treatment of the hip joint include neurovascular injury and avascular necrosis of femoral head by long traction time, femoral neck fracture or hip joint instability after excessive osteoplasty, lateral femoral cutaneous nerve injury and extraarticular leakage of arthroscopic fluid. Arthroscopic procedure in far distal portion of peripheral compartment like this case may have an occurring chance of avascular necrosis of femoral head because this procedure need widened T-shaped capsulotomy which may make injury of medial femoral circumflex artery. So, we used small size osteotome for resection of stalk of osteochondroma and collection of biopsy specimen and removed remnant tumor using only arthroscopic burr. For preventing probable other complications, we used a plastic cannula for protecting neurovascular structure and performed femoroplasty under a fluoroscopic image intensifier. Though there was small amount of extraarticular leakage of the arthroscopic fluid and air bubbles along the iliopsoas muscle in postoperative CT images, that leakage did not make any symptom or complication (Fig. 9).

This case suggests that arthroscopic resection of intraarticular bony lesion of the hip joint can be applied depending on clinical situation. The patient needed arthroscopic treatment for FAI, acetabular labral tear and resection of osteochondroma and all procedures were performed simultaneously. When the operator have a plan for resection of intraarticular bony lesion, they must consider and find other intraarticular pathologies through preoperative evaluation. Arthroscopic management for coexistent problems must be performed for resolution of clinical symptoms of the patient.

Osteochondroma located in posteromedial portion of femoral neck can make a pathology of internal snapping hip and although technical demands are challenging, arthroscopic resection can be a good treatment option.