Better rotational stability with double-bundle ACL reconstruction than single-bundle procedures

An in-vivo study shows double-bundle ACL procedures yield better pivot shift test results.

CHICAGO — A recent Japanese study confirms that anatomical double-bundle ACL reconstruction better controls rotational torque in vivo than single-bundle procedures.

“Although anatomical double-bundle ACL reconstruction has [shown advantages] in controlling rotation torque, no one has been able to prove this in vivo,” Masayoshi Yagi, MD, of Kobe University in Kobe, Japan, said at the American Academy of Orthopaedic Surgeons 73rd Annual Meeting, here.

The prospective study compared the outcomes of 60 patients randomized to single-bundle anteromedial (AM) reconstruction, single-bundle posterolateral (PL) reconstruction or anatomical double-bundle ACL reconstruction.

“When we made a quantitative evaluation — the pivot shift test — we found that anatomic double-bundle reconstruction provides greater control of dynamic rotational stability than single-bundle reconstruction,” Yagi said.

He and his colleagues found no significant differences among the three groups in International Knee Documentation Committee (IKDC) scores or KT-1000 evaluation, but the anatomical ACL double-bundle group tended to show better results, Yagi said.

Surgical procedure

Age and gender were comparable in all three groups, Yagi said. Average age was 22.3 years in the double-bundle reconstruction group, and 22.9 years in both the single-bundle AM and PL groups.

For all procedures, surgeons used a six-strand hamstring tendon graft, fixed with an EndoButton CL (Smith & Nephew Endoscopy) in the femur and post screw in the tibia. In the double-bundle ACL reconstruction, surgeons created two femoral tunnels and two tibial tunnels, Yagi said. For single-bundle reconstruction, they created one femoral tunnel and one tibial tunnel.

Surgeons applied the same postoperative regimen to all patients: partial weight bearing at one week, full weight bearing at three weeks, running at four months and return to sports around nine months, Yagi said.

At one year postop, researchers examined the patients’ knee joint stability, compared to the contralateral side, with a KT-1000 arthrometer and the pivot shift test under general anesthesia. They also performed IKDC examinations.

During the pivot shift test, the researchers recorded the kinematics and velocity between the femur and tibia using three-dimensional electromagnetic sensors, Yagi said. They also measured the acceleration value of posterior tibial translation to determine dynamic rotational stability.

Double-bundle excels

For KT-1000 evaluation results, the double-bundle reconstruction group patients had a mean side-to-side laxity of 1.1 ± 1.6 mm. In the AM single-bundle reconstruction group patients, mean side-to-side laxity was 1.8 ± 1.8 mm and in PL single-bundle reconstruction group patients; 1.7 ± 1.9 mm.

“There was a tendency for double-bundle reconstruction to have better results,” Yagi said. “However, no significant difference was found among the three groups.”

The researchers also found slightly better results with the pivot shift test in the double-bundle reconstruction group. While 85% of double-bundle patients had a negative pivot shift test, 75% of the AM single-bundle and 80% of the PL single-bundle patients had a negative pivot shift test. But there was no significant difference between the groups.

The pivot shift test also revealed that 20% of patients in the single-bundle AM and PL reconstruction groups had an acceleration value for posterior tibial translation over 3000 mm/sec.² However, no patient in the double-bundle group had an acceleration value in this range (P<.05), Yagi said.

The single-bundle reconstruction groups also had larger values in femoro-tibial motion than the double-bundle ACL reconstruction group.

Yagi noted the study's limitations, including the short-term follow-up of one year, the small patient numbers in each group and lack of validation for the measuring system.

For more information:
Yagi M, Kuroda R, Mizuno K, et al. Prospective randomized comparison of single AM, PL and anatomical ACL reconstruction. #017. Presented at the American Academy of Orthopaedic Surgeons 73rd Annual Meeting. March 22-26, 2006. Chicago.