Magnetic resonance evaluation of the pediatric knee after arthroscopic fixation of osteochondral lesions with biodegradable nails.

ABSTRACT

PURPOSE: To use magnetic resonance imaging (MRI) to investigate the knee joint of children following arthroscopic fixation of osteochondral lesions using bioabsorbable nails and to correlate these imaging findings with time from arthroscopic treatment and with risk factors at the time of imaging. MATERIALS AND METHODS: Our study included postarthroscopic MRI studies from 58 children (mean age at arthroscopy, 13.8 + 2.1 years) who have undergone bioabsorbable nail fixation of unstable osteochondral lesions between February 1, 2011 and September 30, 2017. All studies were retrospectively reviewed for broken nails, intra-articular debris, and internal knee derangement. Demographic information and information pertaining to active symptoms was obtained from both MRI questionnaire that was completed at the time of the study and clinical note that preceded the study. Marginal logistic regression models estimated using generalized estimating equations (GEE) were used to identify factors associated with a broken nail and joint effusion. RESULTS: A total of 104 postoperative studies were reviewed, which included 60 with symptoms and 44 without symptoms. Nail breakage was present in 38 (36.6%) studies and associated with presence of symptoms (OR 2.43, p = 0.036) and effusion (OR 2.76, p = 0.025). An effusion was present in 40 (38.5%) studies which decreased with increasing time from treatment (OR 0.89, p = 0.007) and increased with symptoms (OR 10.87, p < 0.001). Meniscal tear was present on 8 (7.7%) and chondral irregularity on 14 (13.5%) studies. CONCLUSION: Broken nail, effusion, and less commonly, meniscal tears and chondral irregularity, are all complications that can arise following fixation of osteochondral lesions with bioabsorbable nails. MRI can serve as a valuable tool in assessing these complications.