Effect of compaction drilling during ACL reconstruction with hamstrings on postoperative tunnel widening.

TYPE OF STUDY

This study investigates whether the amount of tibial and femoral bone tunnel enlargement following anterior cruciate ligament (ACL) reconstruction with hamstrings can be reduced by compaction bone tunnel drilling.

METHODS

Patients undergoing primary ACL reconstruction with four-strand hamstrings (n = 26) were matched to either extraction drilling (n = 13) or compaction drilling (n = 13). Extracortical femoral fixation was by means of a 20 mm Endobutton CL and tibial fixation was by resorbable interference screw. A CT scan was performed on the second postoperative day and an average of 4 months (range 3.8-5 months) postoperatively in all patients. Tunnel enlargement was determined by digitally measuring the widths perpendicular to the long axis of the tunnels on an oblique coronal and axial plane. The CT measurements were compared to the intraoperative drill diameter.

RESULTS

With extraction drilling the average tibial tunnel diameter proximal to the interference screw increased from 8.5 to 10.4 mm (P < 0.0001) and the average femoral tunnel from 8.0 to 10.6 mm (P < 0.0001). With compaction drilling it increased from 8.2 to 10.0 mm (P < 0.0001) and from 7.6 to 9.7 mm (P < 0.002), respectively. Tunnel widening was 22% on the tibial side for both groups and 33 versus 28% on the femoral side (P = 0.09) for extraction versus compaction drilling.

CONCLUSION

There was a significant tibial and femoral tunnel widening on CT an average of only 4 months following ACL reconstruction with hamstrings. Compaction drilling with a stepped router did not prove to reduce the postoperative tunnel widening significantly. Tunnel widening was higher on the femoral side which could be related to the extracortical femoral fixation technique.

LEVEL OF EVIDENCE

Level 4.