Operative Technique

We perform hip arthroscopy using a standard fracture table with the patient in the modified supine position in which the hip is placed in a position of 10° flexion, 15° internal rotation, 10° lateral tilt, and neutral abduction [21]. Traction is placed on the affected limb using a foot stirrup. Adequate traction typically requires between 25 and 50 pounds of force [22]. Usually 7 mm to 15 mm of joint distraction is adequate for evaluation and instrumentation. The C-arm is used to confirm the amount of traction and to facilitate portal placement. Portal placement includes anterior, anterolateral, and peripheral portals [23-26].

A complete diagnostic examination of the hip joint should be performed. Once the chondral defect is identified, the extent of the lesion is noted (Fig. 1). Debridement of all remaining unstable cartilage from the exposed bone is completed using a full radius resector and curettes. Debridement of the rim

Fig. 1. Chondral lesion of the hip visualized at arthroscopically.

surrounding the defect should be careful and meticulous. A ring curette is particularly useful for preparation of the defect and creating a smooth, perpendicular border (Fig. 2). Debridement should remove the calcified cartilage layer; however, the integrity of the subchondral plate should be maintained [6,7]. The edges of the lesion should be perpendicular to the adjacent, unaffected cartilage to allow for the marrow clot to form more effectively. For lesions of the femoral head, where the cartilage is thinner, an adequate border must be prepared to maintain the clot. After preparation of the bed, arthroscopic awls (Fig. 3) with an angle that allows the tip of the awl to be perpendicular to the subchondral bone surface, are used to make multiple holes ("microfractures") in the exposed subchondral bone plate. Microfracture holes are made around the periphery of the bed first immediately adjacent to the healthy cartilage rim. As many holes as possible are created, leaving about 3 to 4 mm between each (Fig. 4). A depth of approximately 2 to 4 mm is usually sufficient to access marrow elements. With the irrigation pressure decreased, the release of fat droplets and blood from the microfracture holes can be observed (Fig. 5). Once microfracture is complete, the instruments are removed and the intraarticular fluid is drained from the hip.

Fig. 2. A curette is used to prepare the defect, including a perpendicular border.

Fig. 3. Microfracture awls used in the hip.

The portals or incisions are closed in standard fashion, and sterile dressings placed over the wounds. The patient usually is discharged the same day but may stay overnight to allow for optimal pain control and to initiate physical therapy contact [6,9,13].

Postoperative management parallels that of knee microfracture. Great care is taken to maintain the marrow clot, and thus the ideal environment for appropriate healing. Use of a continuous passive motion (CPM) machine is used throughout the 8-week period. Crutch-assisted touchdown weight bearing is allowed for 6 to 8 weeks, with advancement to full weight bearing after 8 weeks. Initial physical therapy consists of passive motion progressing to active-assisted motion and eventually active motion with particular emphasis on regaining hip internal rotation. The early phase of physical therapy should focus primarily on achieving range of motion. This phase is followed by an emphasis on muscular endurance. The last phase of therapy focuses on the return of power and strength. Stationary bicycle exercises without resistance are begun in the immediate postoperative period. Cryotherapy is also used in the immediate postoperative period to provide pain relief and to decrease the inflammatory response. Impact sports are delayed until at least 4 to 6 months postoperatively,

Fig. 4. Microfracture of the hip with holes approximately 3 to 4 mm apart.

Fig. 5. Clot formation following microfracture.

and only after range of motion, strength, and functional agility have returned to normal [9,13].

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