Osteochondritis Dissecans

Transcription

1 P R O C E D U R E 1 4 Ammar Anbari, Adam B. Yanke, and Brian J. Cole ch014-x4397.indd 221 4/11/ :50:21 AM

2 222 Treatment Options Conservative management Fixation in situ Elevate the OCD lesion, débride its base, and perform rigid fixation. Bone grafting Removal of any loose bodies followed by microfracture Osteoarticular autograft Osteoarticular allograft Autologous chondrocyte implantation (ACI) Indications Treatment of osteochondritis dissecans (OCD) lesions depends on the stage of the disease as developed by Brendt and Harty: Stage I: lesions not visible on plain radiographs Stage II: visible fragments that are still attached to the overlying cartilage Stage III: nondisplaced, unattached fragments Stage IV: displaced, unattached fragments Nonoperative treatment Reserved for skeletally immature patients with open physes and stage I or II OCD lesions. Includes protective weight bearing, limitation of sports activities, and the use of assistive devices (canes, crutches). Casting should be avoided because it leads to stiffness. Operative treatment Patients who fail conservative management Patients with detached and/or unstable lesions Examination/Imaging OCD lesions tend to present in a patient s second decade of life, with a 2 : 1 male-to-female ratio. The medial femoral condyle is affected three times more commonly than the lateral condyle. 30% of juvenile patients with OCD present with bilateral lesions, although both are not necessarily symptomatic. Patients usually present with vague symptoms of pain and stiffness for a long duration. Symptoms are worse with increasing activities. Weight-bearing pain in the involved region with or without loose body symptoms may be present. Examination Patients may walk with the tibia externally rotated to minimize contact between the tibial spine and the affected lateral aspect of the medial femoral condyle (in patients with medial lesions). Wilson s sign is a specific test for medial femoral condyle lesions. The knee is flexed 90 with the tibia internally rotated. As the knee is slowly extended, catching symptoms are felt at about 30 of flexion as the tibial spine abuts the lateral aspect of the medial femoral condyle. External rotation of the tibia relieves these symptoms. ch014-x4397.indd 222 4/11/ :50:21 AM

3 223 Plain radiographs Useful for sizing and mapping the location of the lesion In addition to the standard weight-bearing anteroposterior and lateral views, a 45 flexion posteroanterior view and a skyline view can be helpful to diagnose and localize an OCD lesion (Fig. 1A and 1B). The majority of OCD lesions are visible on the lateral view within the area between a line drawn through the posterior cortex and another drawn through Blumensaat s line. In skeletally immature patients, views should be obtained of the contralateral knee even if it is asymptomatic (Fig. 2). A FIGURE 1 B FIGURE 2 ch014-x4397.indd 223 4/11/ :50:23 AM

4 224 FIGURE 3 Bone scans (especially pinhole views of the knees) can visualize stage I OCD lesions that radiographs may not detect. MRI is used to assess lesion size and the integrity of the cartilage and underlying subchondral bone (Fig. 3). Arthroscopy The gold standard in staging an OCD lesion An arthroscopic classification system is used to categorize the different lesions: Stage 1: intact cartilage overlying the lesion Stage 2: early signs of cartilage separation Stage 3: partially detached cartilage Stage 4: craters with or without a loose body ch014-x4397.indd 224 4/11/ :50:24 AM

5 Positioning If planning to fix the OCD lesion, place the patient in the supine position with the foot of the bed flexed and the affected extremity placed in a leg holder. If planning to remove the loose fragment and microfracture the base, either a supine position with a side post or a flexed position in a leg holder can be used. If planning to place an osteoarticular allograft, it is easier to perform these surgeries with the patient in a supine position with a side post. If planning an ACI procedure: The biopsy stage of the ACI procedure can be performed in either position. The implantation stage of the ACI procedure is easier to perform with the patient supine. 225 Portals/Exposure Standard arthroscopic anteromedial and anterolateral portals are used for the initial diagnostic arthroscopy. If planning to fix the OCD lesion, a spinal needle is used to localize an accessory portal to place the fixation device perpendicular to the OCD fragment. If planning to utilize an osteoarticular autograft: Depending on the surgeon s preference, accessory portals can be created to perform the harvesting and implantation of the autograft plugs arthroscopically. Alternatively, two small incisions are utilized. If planning to utilize an osteoarticular allograft: A small arthrotomy is performed on the ipsilateral side of the OCD lesion. Z-retractors are useful to achieve a clear exposure of the lesion. If planning an ACI: A cartilage biopsy can be performed using the standard arthroscopic portals. The implantation procedure is done through a small arthrotomy incision made on the side ipsilateral to the lesion. ch014-x4397.indd 225 4/11/ :50:24 AM

6 226 Procedure Step 1: Diagnostic Arthroscopy A tourniquet is applied but rarely used. After establishing the standard arthroscopy portals, a thorough arthroscopic examination is performed. If any loose fragments are noted, they should be removed at this time (Fig. 4). The suspected site of the OCD lesion is localized, and a probe is used to evaluate the lesion s articular surface and attachment to the bed (Fig. 5). In some cases, the knee has to be flexed over 90 to expose the lesion. FIGURE 4 FIGURE 5 ch014-x4397.indd 226 4/11/ :50:27 AM

7 227 Step 2: Decision Making An algorithm is helpful for devising a treatment plan. If the lesion has subchondral bone and can be fixed: If the lesion is stable (stage I), perform retrograde or antegrade drilling (see Procedure 15) or fix the lesion in situ. If the lesion is partially detached (stage II) or detached but minimally displaced (stage III), elevate the lesion, débride both sides of the base of fibrous tissue, microfracture the base, and rigidly fix the lesion. If the fragment is loose and separated from the bed, yet appears healthy with good-quality subchondral bone (stage IV): A mini-arthrotomy may be required. The loose fragment is removed and débrided to fit anatomically in its bed. It is easier in this case to perform open fixation rather than continuing arthroscopically. If the lesion does not have subchondral bone or cannot be fixed: If the lesion is small (<1 cm 2 ) Remove the OCD fragment. Microfracture the bed (see Procedure 10). If the lesion is medium sized (1 2 cm 2 ) Remove the OCD fragment and any other loose bodies. Consider performing osteoarticular autograft or allograft if the patient remains symptomatic, especially after initial treatment is rendered (see Procedures 11 and 13). If the lesion is large (>2 cm 2 ) Remove the OCD fragment and any other loose bodies. Perform osteoarticular allograft or ACI if the patient remains symptomatic, especially after initial treatment is rendered (see Procedures 12 and 13). Consider performing an osteotomy in adult patients with malalignment overloading the affected compartment. ch014-x4397.indd 227 4/11/ :50:27 AM

8 228 P e a r l s Care is taken to avoid completely detaching the OCD fragment. If this occurs, it can be removed from the joint by enlarging the ipsilateral portal and performing the débridement on the back table. The small arthrotomy can be used to perform definitive fixation. If possible, the lesion can be atraumatically elevated at the level of the posterior cruciate ligament origin and hinged laterally to avoid inadvertent trauma to the intact articular margins. A basket can be helpful to remove the frayed and unstable cartilage pieces surrounding the lesion that may hinder an anatomic reduction. Step 3: Elevating a Partially Detached Lesion Using a probe or an arthroscopic elevator, the OCD piece is gently elevated from its bed (Fig. 6A and 6B). This step can be skipped only if the lesion is stable, has not displaced, and has a completely intact cartilage surface. The back side of the OCD fragment is inspected to ensure that it contains bone. A small (3.5-mm) arthroscopic shaver is placed between the OCD fragment and its bed to débride any fibrocartilage (Fig. 7). Alternatively, a curette can be used to gently remove the fibrocartilage lining the base and fragment. Small microfracture awls are gently wedged behind the OCD fragment in order to make a few holes in the bed of the lesion (Fig. 8). The pump is then turned down to verify the egress of blood from the bed of the lesion (Fig. 9). Subchondral bone loss can be grafted by obtaining 5-mm osteochondral autograft plugs arthroscopically from the medial edge of the lateral femoral condyle (i.e., the region where a notchplasty is performed during anterior cruciate ligament reconstruction). A FIGURE 6 B ch014-x4397.indd 228 4/11/ :50:30 AM

9 229 FIGURE 7 FIGURE 8 FIGURE 9 ch014-x4397.indd 229 4/11/ :50:34 AM

10 230 Step 4: Reducing the OCD Fragment After thorough débridement is performed, the OCD fragment is reduced using a probe (Fig. 10). If an anatomic reduction cannot be performed, the fragment is elevated again to look for any bony or cartilage fragments that may be blocking the reduction. Kirschner wires (K-wires) can be inserted through the fragment to hold it reduced while definitive fixation is carried out (Fig. 11). If K-wires are used, be sure they do not interfere with the desired screw location. FIGURE 10 FIGURE 11 ch014-x4397.indd 230 4/11/ :50:37 AM

11 231 P e a r l s Varying the flexion angle of the knee can deliver the lesion so that one accessory portal can be used to place multiple fixation devices. Bone grafting can be performed when necessary as previously described. Step 5: Fixing the OCD Fragment With an assistant holding the fragment reduced with a probe and flexing the knee to expose the fragment, a spinal needle is placed in the ipsilateral compartment to achieve a perpendicular angle to the lesion. An accessory portal is created. Several fixation options exist. We prefer either metallic Acutrak standard or miniscrews (Acumed, Hillsboro, OR) or Bio-Compression Screws (Arthrex, Inc., Naples, FL). For Acutrak 2 screws Features Headless screws, which minimizes risk of damage to articular surface Metallic Cannulated Self-drilling Fully threaded Variable pitch is used to achieve compression as the screw is advanced. Miniscrews are available in lengths of mm with a head diameter of 3.6 mm. Technique A inch guidewire is placed through the accessory portal into the joint. Using a perpendicular angle, the wire is drilled into the center of the lesion and advanced about 3 4 cm (Fig. 12). If more than one screw is anticipated, then the first screw is placed centrally in one plane and eccentrically in the other to allow room for additional screws. FIGURE 12 ch014-x4397.indd 231 4/11/ :50:39 AM

12 232 Fluoroscopy can be used to verify an adequate depth of fixation. A depth gauge is used to measure the length of the screws. If the guidewire is within 2 mm of the posterior cortex, we recommend using a screw that is at least 2 mm shorter than the measured depth. Although the screws are self-drilling, we recommend using the profile drill on the set, especially in younger patients with dense subchondral bone. Insert the sized screw using a manual screwdriver (Fig. 13). If resistance is met, the screw should be removed and the hole should be redrilled further into the bone. Once the screw is seated, it should be recessed by advancing the screw two full turns to prevent the screw head from scuffing the tibial articular surface (Fig. 14A and 14B). If more screws are used, they should be slightly divergent to provide multiplanar stability. To avoid any future problems with the screw backing out or from fragmentation of the piece around the screw, we remove the hardware early for younger patients or in patients who have smaller fragments (i.e., 8 10 weeks). For Arthrex Bio-Compression screws Features Headless screws Bioabsorbable (PLLA) Fully threaded Stepped thread pitch and taper FIGURE 13 ch014-x4397.indd 232 4/11/ :50:40 AM

13 233 A FIGURE 14 B Head diameter of 3.7 mm and length of 20 mm Biomechanically equivalent to a 20-mm Acutrak miniscrew Technique A clear cannula available on the set is placed on the desired screw location perpendicular to the surface of the fragment. A dedicated tapered drill is pushed until the shoulder of the drill contacts the cannula (Fig. 15). Tap the drill hole until the tap contacts the cannula. Load the Bio-Compression screw on the hex screwdriver. The headless tip of the screw is separated by 3 mm from the smooth shaft of the driver (Fig. 16). FIGURE 15 ch014-x4397.indd 233 4/11/ :50:45 AM

14 234 FIGURE 16 Advance the screw through the clear cannula until fully seated. This will place the tip of the screw 3 mm below the articular surface. Step 6: Closure The portal sites are closed in a standard fashion. Sterile dressings are applied along with a cryotherapy cuff. Postoperative Care and Expected Outcomes Nonoperative treatment Weight bearing is protected for about 2 months. If symptoms improve, progressive weight bearing is instituted. Return to sports is achieved with elimination of symptoms and with radiographic evidence of progressive healing. Fifty percent of stable stage I and II lesions in young patients will heal in months. In situ fixation of OCD lesion Patients are kept heel-touch weight bearing for 6 8 weeks. ch014-x4397.indd 234 4/11/ :50:47 AM

15 235 Progressive weight bearing is started at 8 weeks. A continuous passive motion machine is used for the first 6 weeks for an average of 6 hr/day. Return to sports is delayed until the patient has full range of motion, no symptoms, and evidence of radiographic healing. This can take about 1 year. Evidence Anderson AF, Richard DB, Pagnani MJ, Hovis WD. Antegrade drilling of osteochondritis dissecans of the knee. Arthroscopy. 1997;13: Twenty-four patients with stable OCD lesions were treated with antegrade drilling. Twenty of 24 patients healed at an average of 4 months; 91.7% of the patients were rated as good or excellent. Only 50% of the skeletally mature patients healed. Garrett JC. Fresh osteochondral allografts for treatment of articular defects in osteochondritis dissecans of the lateral femoral condyle in adults. Clin Orthop. 1994;303:33-7. Seventeen patients with OCD lesions were treated with allografts and followed for an average of 3.5 years. The mean age was 20. Herbert screws were used to augment the fixation of the allografts. At follow-up, 94% of the patients had successful outcomes. Johnson LL, Uitvlgut G, Austin MD, Detrisac DA, Johnson C. Osteochondritis dissecans of the knee: arthroscopic compression screw fixation. Arthroscopy. 1990;6: The authors used compression screws to treat patients with mild cases of OCD. At a minimum of 2 years follow-up, 88% of the patients were rated as good or excellent. Kocher MS, Micheli LJ, Yaniv M, Zurakowski D, Ames A, Adrignolo AA. Functional and radiographic outcomes of juvenile osteochondritis dissecans of the knee treated with transarticular arthroscopic drilling. Am J Sports Med. 2001;29: Thirty skeletally immature patients with stable OCD lesions who had failed 6 months of conservative management were treated with antegrade drilling. One hundred percent of patients showed radiographic healing in 4.4 months. Peterson L, Minas T, Brittberg M, et al. Two- to 9-year outcome after autologous chondrocyte transplantation of the knee. Clin Ortho Rel Res. 2000;374: Ninety-four patients were followed for between 2 and 9 years. Isolated patellar ACI procedures had 62% good to excellent outcomes. When combined with a tibial tubercle osteotomy, the results improved to 85% good and excellent. Of the femoral condyle lesions, 96% had good to excellent results. In the OCD group, 89% of the patients had good to excellent results. About 15% of patients had a hypertrophic periosteal patch. Slawski DP. High tibial osteotomy in the treatment of adult osteochondritis dissecans. Clin Orthop. 1997;341: Seven knees in patients with an average age of 32 years who failed previous surgeries for OCD lesions underwent high tibial osteotomy to unload their affected medial compartment. None of the knees showed diffuse medial arthritis. The Lysholm scores improved from 39 to 89 at the latest follow-up of 30 months. All the patients reported subjective improvement in their symptoms. Wang CJ. Treatment of focal articular cartilage lesions of the knee with autogenous osteochondral grafts: a 2- to 4-year follow-up study. Arch Orthop Trauma Surg. 2002;122: A retrospective review of 16 knees with focal articular defects treated with osteochondral autografts. The results were not affected by the diagnosis (OCD, avascular necrosis, trauma). Good to excellent results were achieved by 80% of the patients. The improvement was time dependent and took up to 4 months to appear. ch014-x4397.indd 235 4/11/ :50:47 AM

16 236 Wright RW, McLean M, Matava MJ, Shively RA. Osteochondritis dissecans of the knee: long term results of excision of the fragment. Clin Orthop. 2004;424: The authors reviewed the results of simple fragment excision in OCD patients. Seventeen knees with OCD lesions that underwent this procedure were followed for an average of 8.9 years. The average age of the patients was 26 years. Using the Hughston rating scale, only 35% had good or excellent results. Based on these results, simple excision of OCD lesions should be discouraged. ch014-x4397.indd 236 4/11/ :50:47 AM