Summary

Allogenic bone graft shows comparable results in tunnel filling and clinical outcome compared to the gold standard autologous bone graft in two-staged ACL revision surgery.

Abstract

Introduction

With the increasing number of ACL reconstructions, the number of failures also rises. Often a two-staged treatment with tunnel filling and secondary ACL reconstruction is necessary in ACL revision surgery due to tunnel widening or poor tunnel placement. Aim of this study was to investigate if allogeneic bone graft is non inferior to autologous corticocancellous iliac crest graft in terms of radiological bone regeneration.

Materials And Methods

The study was designed as a prospective, randomized trial. 41 patients who required 2 staged ACL revision surgery were included. In 17 patients, the void filling was performed using iliac crest corticocancellous autograft and in 24 patients with allogeneic femoral head graft. 3 months postoperatively a CT scan was performed. Tunnel filling was measured in the axial planes dividing the area of the bone graft by the area of the whole tunnel. Additionally, the Hounsfield units of the bone graft were compared to a representative native cancellous bone area of the proximal tibia. Clinical assessments with testing of knee function (ROM), stability (KT 1000) and PROM's were performed 6, 12 and 24 months postoperatively.

Results

Tunnel filling showed comparable results for autologous and allogenic grafts. The mean percentage of tunnel filling for allogenic bone graft was 82,61% to 84,94% (p=0,4415) for autologous corticocancellous graft. Hounsfield units differed in both groups significantly (p<0,0001) compared to a representative native bone area of the proximal tibia. There was also a significant difference between the Hounsfield units with a mean of 630,5 for allograft and 431,7 for autograft (p=0,0015).
KOOS score was significantly higher 6 months postoperatively with a mean of 80 in the autograft group compared to 68 in the allograft group. Whereas there was no significant difference between the two study groups in IKDC score 6 months postoperatively. In the clinical examination, no relevant differences in range of motion or ligamentous stability (KT 1000) were found.

Conclusion

Allogeneic bone graft is non inferior to the gold standard autologous corticocancelleous bone graft in terms of tunnel filling, knee function, IKDC and stability 6 months postoperatively. The difference in the KOOS score at 6 months postoperatively below the minimally clinically important difference (MCID) and substantial clinical benefit (SCB). Both allograft and autograft showed Hounsfield units of cortical bone, however autologous bone graft was closer to normal cancellous bone than the allogeneic graft.