XtraLok better than Intrafix for ACL reconstruction

Prospective trial found decreased laxity with BioScrew XtraLok.

A comparison of two tibial fixation devices for use with ACL reconstruction found that patients receiving the BioScrew XtraLok had significantly less clinical laxity than those who received Intrafix.

“Tibial fixation is currently the weak link in hamstring ACL reconstruction. The goal of tibial fixation devices is to secure the graft to the tunnel without the need for secondary fixation on the anterior tibia, which can be clinically problematic,” said Monika Volesky, MD, of the Carleton University Sports Medicine Clinic. Volesky and colleagues performed a randomized clinical comparison of two tibial fixation devices in hamstring ACL reconstruction: the BioScrew XtraLok (Conmed Linvatec) and Intrafix (Mitek Products).

Researchers hypothesized that there would be no difference in mechanical results or clinical laxity between the two devices after six months. Three surgeons using identical techniques performed all the operations.

The study included 103 sequential patients. All patients had to have no other ligamentous injury, no previous knee surgery and a normal contralateral ACL for comparison. “Patients were randomized by a computer-generated table that set them up to receive either the XtraLok or the Intrafix device,” Volesky said. “All patients received the EndoButton femoral fixation, and the Mitek tensioner was used prior to insertion of the tibial fixation device.” She spoke at the Arthroscopy Association of North America 24th Annual Meeting in Vancouver.

Results

Researchers assessed results at six, 12 and 26 weeks postoperatively by an independent surgeon using the KT-1000 arthrometer. Of the 103 patients enrolled, 84% had recorded follow-up after 6 months. Volesky said there were no significant differences in demographics between the two groups.

Researchers saw no variation in mean side-to-side differences between the two groups intraoperatively and after six weeks and three months. After six months, however, the mean side-to-side difference in the XtraLok group was 1.26 mm vs. 2.41 mm in the Intrafix group. This reached statistical significance, with the XtraLok showing less laxity.

Regarding the percentage of patients within 2 mm of their normal mean side-to-side difference, the two groups were again similar through three months. “At six months, however, there was a trend to significance with more patients within 2 mm of their normal mean in the XtraLok group,” Volesky said.

The study concluded after six months of follow-up because tendon and bone healing take approximately 12 weeks, Volesky said. After this period, the stresses on the tibial fixation device lessen. She noted that in cadavaric studies of pullout strength, Intrafix fared well, with less slippage than other devices. “More recent laboratory biomechanical studies support our data, suggesting that tapered or flared screws have less displacement at failure than the Intrafix.” This supports Volesky’s study findings.

“In conclusion, mechanical results at six months suggest that XtraLok has less clinical laxity than Intrafix, enhancing ACL reconstruction,” Volesky said. “But both devices have excellent clinical results, with less than 3 mm of side-to-side difference.”

For more information:
Volesky M, Pickle A, Wilkinson R, et al. Comparison of XtraLok vs. Intrafix tibial fixation in hamstring anterior cruciate ligament reconstruction: a randomized clinical trial. Presented at the Arthroscopy Association of North America 24th Annual Meeting. May 12-15. Vancouver, British Columbia.