PATHOLOGY
Bipolar focal chondral defects of the patellofemoral joint
TREATMENT
Autologous chondrocyte implantation of the patella and trochlea (Note that the use of ACI for the patella or for bipolar defects is considered off-label usage, but was indicated and performed with explicit patient informed consent.)
SUBMITTED BY
Jack Farr, MD, Cartilage Restoration Center of Indiana, Ortholndy, Indianapolis, Indiana, USA
CHIEF COMPLAINT AND
HISTORY OF PRESENT ILLNESS
The patient is a 28-year-old man who works in his family boiler company as an estimator/
troubleshooter. He has a long history of bilateral patellofemoral pain, right worse than left. In his late teens he enjoyed basketball, but had to stop all sports because of severe anterior knee pain and limited his activities to level-ground walking. Review of the operative record reveals that 4 years before presentation, at age 24, he underwent a lateral release and anteromedial- ization (AMZ) procedure, which was performed with a steep slope osteotomy as malalignment was mild.The articular surfaces at that time were intact, except at the patellofemoral joint where contained grade III chondral defects were noted on the patella and trochlea, each measuring 2 cm by 2 cm. These lesions were treated with mechanical chondroplasty at the time of the AMZ. The patient had minimal symptoms until 2 years later when symptoms similar to his con- dition 4 years ago developed.
PHYSICAL EXAMINATION
Height, 6 ft, 10in.; weight, 2801b. Level-ground gait is normal. Mild symmetric valgus alignment is present. He has a well-healed incision from
his prior AMZ. His range of motion is sym- metric from 0 to 135 degrees of flexion. His ligament examination is normal. Patellar appre- hension is absent. Tenderness is isolated to the patellofemoral joint, where there is 1cm of medial and lateral displacement. Tilt is reversible to neutral.
RADIOGRAPHIC EVALUATION
Preoperative radiographs of his right knee reveal maintenance of tibiofemoral joint space with near-neutral alignment. Merchant view shows joint space maintenance and a central patella. Evidence of a prior AMZ with internal fixation is present (Figure C34.1).
SURGICAL INTERVENTION
Right knee arthroscopy revealed progression in the size and grade (to grade IV) of the chon- dral defects of both the patella and trochlea.
The trochlea had an intralesional osteophyte treated with impaction (Figure C34.2). Carti- lage biopsy was performed. Six weeks later, autologous chondrocyte implantation (ACI)
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FIGURE C34.1. Radiographs after initial anteromedialization (AMZ) osteotomy. Anteroposterior (A), lateral (B), and Merchant (C) views show maintenance of joint space and central patella.
FIGURE C34.2. Intralesional trochlear osteophyte (A), raised appearance (B), impaction (C), and flush area of prior osteophyte (D).
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FIGURE C34.2. Continued
was performed on the patella and trochlear lesions, both of which remained contained, grade IV, and measured 2.5 cm by 3 cm at each site (Figure C34.3).
Although he was allowed to flex his knee daily to 90 degrees, continuous passive motion was restricted to 45 to 60 degrees of flexion
during its use for the first 4 postoperative weeks. He advanced through the traditional rehabilitation protocol for ACI of the patellofemoral joint allowing early weight bearing in extension. He was asked to refrain from any impact or ballistic activities for 18 months.
B FIGURE
C34.3. Intraoperative autologous chondrocyte implantation (ACI) patches in place in the (A)
trochlea and (B) patella.
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FIGURE
C34.4. Second-look arthroscopic view of ACI filling both the (A) patellar and (B) trochlear defects.
FOLLOW-UP DECISION-MAKING FACTORS
Postoperatively the patient had progressive diminution of pain. After his pain resolved, he slipped in mud and had acute, new onset medial joint line pain. The medial pain persisted and he was subsequently evaluated arthroscopically.
Arthroscopy revealed the areas of ACI were filling with full peripheral integration (Figure C34.4).The medial pain resolved with debride- ment of impinging scar. At present he is without pain during activities of daily living, and his contralateral patellofemoral pain is now his main concern.
1. Young, highly symptomatic patient with