Osteochondritis dissecans of the lateral femoral condyle

PATHOLOGY

Osteochondritis dissecans of the lateral femoral condyle

TREATMENT

Autologous chondrocyte implantation of the lateral femoral condyle

SUBMITTED BY

Brian J. Cole, MD, MBA, Rush Cartilage Restoration Center, Rush Univer- sity Medical Center, Chicago, Illinois, USA

CHIEF COMPLAINT AND

HISTORY OF PRESENT ILLNESS

The patient is a very active 19-year-old man who reports an injury to his right knee approxi- mately 6 months prior while jumping from a fence. He subsequently developed the onset of sudden pain and sweUing of his knee. He does recall occasional clicking before that time, but it became significantly worse after this recent traumatic event. Since the time of the injury, the patient has had weight-bearing discomfort with pain along the lateral aspect of his knee. He is unable to perform high-level activities because of the pain and activity-related swelling. Addi- tionally, he reports a catching sensation. As a result of his present symptoms, he is unable to compete in intramural college athletics as he was able to do before this injury.

PHYSICAL EXAMINATION

Height, 5 ft, 8in.; weight, 1701b. The patient walks with a nonantalgic gait. His standing alignment is in symmetric physiologic varus.

The right knee has a moderate effusion with positive lateral joint line tenderness, no medial joint line tenderness, and no varus or valgus instabiUty upon stress testing. His lateral femoral condyle is painful to direct palpation.

His ligament examination is within normal

limits. He has full range of motion and has no meniscal findings.

RADIOGRAPHIC EVALUATION

Plain radiographs of the right knee including 45-degree flexion weight-bearing posteroante- rior and nonweight-bearing lateral views reveal flattening of the lateral femoral condyle consis- tent with chronic osteochondritis dissecans.

There appears to be minimal subchondral bone loss. Magnetic resonance imaging (MRI) is also consistent with the diagnosis of osteochondritis dissecans with minimal bony involvement (Figure C19.1).

SURGICAL INTERVENTION

Based on the patient's history, age, symptoms, physical examination, and radiographic studies, he was indicated for diagnostic arthroscopy, debridement of the lateral femoral condyle lesion, and possibly microfracture depend- ing on the size and depth of the lesion. At arthroscopy, a grade IV 28 mm by 30 mm lesion of the lateral femoral condyle was noted. The lesion extended down to but not appreciably through the subchondral bone, and no loose bodies were identified (Figure C19.2). Because of the defect size, patient activity level, and

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FIGURE

C19.1. Preoperative (A) posteroanterior 45-degree flexion weight-bearing and (B) lateral radiographs demon- strate flattening and loss of contour of the lateral femoral condyle of the right knee with minimal loss of subchondral bone. (C) MRI confirms full-thickness cartilage loss of the lateral femoral condyle with minimal bony involvement.

FIGURE

C19.2. Arthroscopic photograph demon-

strates grade IV lateral femoral condyle lesion

measuring 28 mm by 30 mm, extending down to but

not appreciably through the subchondral bone.

64 Case 19 symptoms, it was elected to proceed with biopsy

of the articular cartilage for eventual autolo- gous chondrocyte implantation (ACI) and not to perform microfracture of the lesion.

The lesion was debrided, and a biopsy of 200 to 300 mg articular cartilage from the inter- condylar notch was harvested. Approximately 2

months later, the patient returned and under- went ACI through a lateral-based arthrotomy (Figure C19.3). Postoperatively, the patient was made heel-touch weight bearing for 6 weeks and utilized continuous passive motion (CPM) for 6 to 8h/day during that time. His range of motion was limited from full extension to 90

FIGURE

C19.3. (A) Intraoperative photograph of the

lateral femoral condyle lesion demonstrates full-thickness

cartilage loss. (B) Lateral femoral condyle lesion after

debridement. (C) Lateral femoral condyle lesion after the

periosteal patch is sewn into place.

Case 19 65

FIGURE

C19.4. Postoperative anteroposterior (A) and lateral (B) radiographs at 1-year follow-up demon- strate good fill and contour of the lateral femoral condyle with no evidence of collapse.

degrees of flexion. At 6 weeks, weight bearing and range of motion were advanced as toler- ated. He advanced through the traditional rehabilitation protocol for ACI of the femoral condyle and was asked to refrain from any impact or ballistic activities for at least 12 months.

FOLLOW-UP

The patient is now 24 months after ACI of the lateral femoral condyle of his right knee. He has no pain and has full range of motion. He runs, bikes, and skis on a regular basis. He is actively involved with intramural sports while attending college. His radiographs show early fill and restoration of contour of the lateral femoral condyle (Figure C19.4).

DECISION-MAKING FACTORS

1. Young, high>demand male with shallow osteochondritis dissecans lesion anticipated to be relatively unresponsive to micro- fracture and considered relatively large for osteochondral autograft transplantation.

2. Persistent symptoms of pain and sweUing in the exact location of the defect.

3. Patient preference for his own tissue and surgeon preference for ACI as a primary cartilage restoration procedure given the relatively young age of this patient and the desire to avoid creating a subchondral defect otherwise required for fresh osteochondral allograft transplantation.

4. AbiUty and willingness to be compUant with

the postoperative course.