Effect of Subchondral Bone Condition on Repaired Tissue after Bone Marrow Stimulation for Osteochondral Talar Lesions

Abstract

Category: Ankle, Sports Introduction/Purpose: The arthroscopic bone marrow stimulation (ABMS) promotes repaired tissue healing of the osteochondral defect. Recently, T2 mapping has been used to evaluate the repair of cartilage tissue; however, the prognostic worth of T2 values after ABMS has not yet been clarified. Several articles have reported that the subchondral condition affects the articular cartilage condition, and subchondral bone edema (SBE) is reportedly associated with inferior outcome after ABMS. Furthermore, subchondral bone sclerosis (SBC) was found to be associated with an inferior outcome after ABMS. The purpose of the present study was to investigate the relationship between SBC/SBE and T2 values of repaired tissue on MRI after ABMS. We hypothesized that the presence of SBC/SBE would affect the characteristics of the repaired tissue after ABMS. Methods: We prospectively enrolled 18 patients (18 ankles) scheduled to undergo treatment with ABMS for OLT. The patients were six males and 12 females (age, 29.3 ± 22.1 years; lesion length, 10.8 ± 3.0 mm; lesion area, 59.7 ± 26.0 mm2). Repair tissue was assessed using a 3 T MRI unit, and T2 maps were calculated. Patients were divided into two groups for investigating effect of the SBE: those with SBE and those without SBE based on MRI performed pre-ABMS and 1 year post-ABMS. We investigated the relationship between T2 value and SBE presence. For investigating the relationship between SBC and T2 value, the patients were divided into two groups; with SBC and without SBC on pre-ABMS CT images. Clinical results were assessed using JSSF scale. Results: There were no significant differences in mean T2 values and JSSF score before ABMS between those with SBE versus those without SBE (T2 values, P = 0.5; JSSF score, P = 0.9). At 1 year post-ABMS, there was no significant difference between groups in T2 value (P = 0.8), but the JSSF score was significantly lower in the SBE group (P = 0.02). No significant mean differences were found in T2 values or JSSF scores between the with SBC and without SBC groups post-ABMS (T2 values, P=0.7 / JSSF scale score, P=0.25).Lesion length/area were correlated with T2 values of repaired tissue (length: r = 0.50, P = 0.005; area: r = 0.29, P = 0.04). Conclusion: The presence of pre- and/or post-ABMS SBE does not affect the T2 values of repaired tissue after ABMS for OLT. The presence of SBC prior to ABMS did not affect the T2 values of repair tissue after ABMS. However, post-ABMS SBE was associated with poorer clinical outcome. Larger lesion size is correlated with poorer condition of repaired tissue.