Abstract
Background:
Cartilage defects are a common source of knee pain in pediatric patients and treatment options range from conservative management to surgical interventions such as fixation, microfracture, osteochondral transplantation, and autologous chondrocyte implantation (ACI) or matrix-induced autologous chondrocyte implantation (MACI). ACI/MACI is an established treatment for articular cartilage injuries, demonstrating superior long-term outcomes to microfracture in adults. While a multicenter trial is underway for FDA approval in pediatric patients, outcomes have yet to be established for this population.
Hypothesis:
This study hypothesizes that treatment of pediatric knee osteochondral defects with ACI/MACI leads to favorable radiographic and clinical outcomes.
Methods:
A retrospective review included patients aged 5 to 25 years who underwent MACI under a single surgeon performed at two institutions (2004–2021). Patient-reported Pediatric International Knee Documentation Committee (Pedi-IKDC) scores were collected pre- and postoperatively. Postoperative IKDC scores were compared to baseline scores using paired t-tests. Cartilage repair was evaluated via Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) scores, independently assessed by three orthopedic surgery residents. Images obtained at 6-month time intervals postoperatively.
Results:
A total of 47 patients for whom postoperative MRIs were available were included. At 6-12 months postoperatively, the mean MOCART score was 57.7 + 12.6 with 64% (28/44) of patients exhibiting favorable MOCART scores (>55). At 18-24 months postoperatively, the mean MOCART score was 60.9 + 13.6 with 75% (18/24) of patients exhibiting MOCART scores >55. Among 22 patients with paired MOCART scores at both 1 and 2 years postoperatively, the mean score improved from an average of 57.9 to 62.8 (p = 0.024).
Postoperative IKDC scores were available for 41 patients, who reported an average score of 71.6 + 19.4 at final follow-up (average 2.17 years). Pedi-IKDC scores were available preoperatively and at final follow-up for 33 patients, with improvement of mean score of 36.9 preoperatively to 65.2 (p < 0.001) at final follow-up.
Conclusion:
MACI treatment for knee osteochondral defects in pediatric populations demonstrated favorable outcomes at short term follow up (6 months to 2 years). Patients experienced significant functional improvement postoperatively, as reflected by IKDC scores. Most patients had favorable MOCART scores, suggesting good graft integration overall. Moreover, the improvement of MOCART scores over time suggests that cartilage repair tissue continues to mature for at least 2 years postoperatively. Further studies with longer and more consistent follow-up are needed to determine long-term durability and optimized treatment protocols.