Injury to long bones in the lower extremities with involvement of the pyseal growth-plate is common in children and adolescents [1]. It is estimated that 15% of all long bone injuries during childhood involve the physeal growth-plate [2]. Chondral damage to the knee is common and retrospective reviews of large numbers of arthroscopic procedures have shown a prevalence of between 63% to 67% of focal chondral or osteochondral lesions [3, 4]. Breakdown of articular cartilage secondary to trauma or disease results in severe pain and disability, ultimately progressing to early onset osteoarthritis [5, 6]. The use of corrective high tibial osteotomy [7–9] and chondrocyte transplantation [10–12] for the treatment of isolated unicompartmental osteochondral defects of the knee are both well-described separately, as are the benefits of restoration of the mechanical axis of the knee prior to or in conjunction with chondrocyte transplantation to protect the graft site in a fully mobile knee [7, 13]. The use of combined techniques for cartilage repair is becoming commoner, especially in younger patients [Parratt MTR et al: Chondrocyte transplantation combined with high tibial osteotomy in the treatment of osteochondral defects in the adolescent knee. 2011 Submitted].
In this case distal femoral supracondylar osteotomy, to correct a valgus deformity at the knee caused by presumed trauma-related physeal arrest and subsequent dysplasia of the lateral femoral condyle was performed following ACI for a large 4 cm × 5 cm osteochondral defect.
Case Presentation
A 15 year-old male presented to his local Orthopaedic outpatient department complaining of a swollen painful right knee. A keen rugby player, he had also sustained an injury three months previously whilst skiing, and at the time of presentation complained of persistent pain, which had prevented him engaging in any further sporting activity. Plain radiographs confirmed the diagnosis of a stable osteochondral defect in the lateral femoral condyle. Eight months later, the patient was referred to our unit with continued pain in the right knee, unable to participate in sports. The patient, a semi-professional rugby player, was keen to return to high-level competitive sports again.
Clinical examination revealed a unilateral valgus deformity of the right knee, with a moderate effusion. He had a non-reciprocating stair-climbing gait. Range of movement was 0 to 140°. There was marked wasting of the right quadriceps. Patellar tracking and ligament examination was normal.
Standing AP radiographs showed a valgus alignment of 11 degrees on the right and 5 degrees on the left and an abnormality of the right lateral femoral condyle (Figure 1). Magnetic resonance imaging confirmed a full-thickness osteochondral lesion on the lateral femoral condyle measuring approximately 5 cm2. All of this was in keeping with a diagnosis of Osteochondritis dissecans.
His metabolic and haematological parameters were within the normal range. Pre-operatively, the patient's function was assessed using the Modified Cincinnati score [14] (40 out of 100) and Bentley functional rating system [15] (4 out of 5). Pain assessed using the visual analogue score (VAS) was 9 out of 10.
Arthroscopic assessment showed an extensive articular osteochondral defect with gross irregularity of the articular surface of the lateral femoral condyle measuring 4 × 5 cm (Figure 2), equivalent to a grade IV on the International Cartilage Repair Society (ICRS) scale. In view of the extent of these findings it was decided to attempt to repair the defect by autologous chondrocyte implantation (ACI). Because the valgus deformity was not very severe and the knee had a range of movement of only 10-90°, the ACI was performed first. Full thickness cartilage was harvested from the margin of the lateral femoral trochlea and sent for chondrocyte culture. At second stage surgery five weeks later, a total of 8 million expanded cultured chondrocytes were implanted beneath a porcine derived type I/III collagen membrane covering the large lateral femoral condyle defect via a medial arthrotomy. Post-operatively the patient was allowed to weight-bear in a cylinder cast for 2 weeks and underwent intensive protected low-impact physiotherapy.
After six months of protected weight-bearing and active mobilisation, when he had recovered from the chondrocyte transplantation procedure, the valgus deformity was corrected to restore the mechanical axis. This was achieved by a supracondylar medial closing-wedge femoral osteotomy and internal fixation with a blade-plate. At surgery it was aimed to correct the deformity to a physiological alignment of +3 degrees with the intention of off-loading the ACI graft. The metalwork was removed twelve months later and the patient was permitted to engage in competitive sports including rugby and football.
Modified Cincinnati, Bentley and VAS scores were taken at 12 and 24 months post-operatively. Modified Cincinnati scores were 60 and 76, and Bentley score was 3 and 2. VAS scores were 6 and 3 respectively.
Subsequent clinical assessment at eight years post-operatively, the patient complained of no pain, locking or giving way of the knee; he is able to kneel and squat without pain and has been able to resume full sporting activities including semi-professional rugby at university, skiing and free-weight gym activity. The right knee had a full range of unrestricted movement, there was no evidence of quadriceps wasting and there was equal leg length. His Modified Cincinnati Score was 92, Bentley score 0 and VAS 0.
Subsequently in the year, the patient presented with right knee pain secondary to a recent sports injury. Latest radiographic assessment revealed a neutral alignment of the right leg, with joint space narrowing laterally, new-spur formation and a well-healed osteochondral lesion (Figure 3). Continued pain warranted an arthroscopy, which showed a minor tear in the lateral meniscus. The lateral femoral condyle demonstrated an intact ACI graft with good cartilage growth (Figure 4). After debridement and trimming of the lateral meniscus the patient was pain free.