Summary

Arthroscopic transmalleolar fixation using cortical bone pegs combined with retrograde autologous cancellous bone grafting is a low invasive and effective technique even for chronic osteochondral lesion of the talus. The healing rate was 71.4%, but clinical outcome was satisfied in 90.5%. The related factor of fragment healing after operation is the iso intensity lesion of T2W in preoperative MRI.

Abstract

Background

The indication of the fixation for osteochondral lesion of the talus (OLT) is generally limited to acute and large lesions. However, if cartilaginous status is almost normal even though in chronic OLTs, we have performed arthroscopic transmalleolar fixation using cortical bone pegs combined with retrograde autologous cancellous bone grafting (ATFRB) since 2012, to preserve osteochondral fragment. The purpose of this study is to investigate the clinical outcomes of ATFRB for chronic OLTs retrospectively and examine the appropriate factor of fragment healing for ATFRB.

Methods

Twenty-one patients who underwent ATFRB for medial OLT were included in this study (mean age: 15.2y.o. / sex: male11, female10, mean follow up: 24.9 months). All lesions included full-thickness articular cartilage with solitary or separated subchondral fragment. Firstly, after 7mm of retrograde drilling beneath the OLT to perforate the sclerotic margin, autologous cancellous bone harvested from the proximal tibial metaphyses was transplanted into the bone tunnel. Secondly, after 3mm of transmalleolar drilling using fluoroscopic device, the lesion was fixed with a few 2.5mm of cortical bone pegs harvested from the proximal tibia. The clinical outcome was evaluated using AOFAS ankle-hindfoot score and the Self-Administered Foot Evaluation Questionnaire (SAFE-Q). Fragment healing was assessed using CT and MRI, postoperatively. We compared both scores between healing group (H) and non-healing group (N). In addition, morphology of fragment (solitary 17, or separated 4) and the intensity of fragments in T2W MRI image (iso 12, or low 9) were analyzed for the related factor of fragment healing. Statistical analysis was performed using Fisher exact test, paired t-test and Student t-test, and the significance was set at P<0.05

Results

The mean AOFAS score significantly improved from 79.8 preoperatively to 95.0 at final follow up. Fifteen feet (71.4%) were healed, and 6 feet (28.6%) were non-healed. Nineteen patients (90.5%) including 4 non-healed patients were satisfied, but 2 non-healed patients remained pain. One patient underwent autologous osteochondral transplantation and another patient dropped out. Between group H and N, there were significant difference in AOFAS score (98.2 vs 88.3, P<0.01), and there was no significant difference in all 6 subscales of SAFE-Q. Fragment healing and the iso intensity lesion of T2W in preoperative MRI was significantly related to positive correlation (P<0.01). Meanwhile, 3 of 9 with the low intensity lesions were healed after ATFRB.

Discussion

Kumai has reported that the success rate of fixation with bone pegs after malleolar osteotomy was 89% in 27 feet. In our study of ATFRB, the healing rate was 71.4%, but clinical outcome was satisfied in 90.5%, which is equivalent with Kumai’s report. In addition, this is the first report demonstrated that the associated factor of fragment healing after fixation was the iso intensity lesion of T2W in preoperative MRI. We concluded that ATFRB is a low invasive and effective technique even though for chronic OLT.