Summary
Anterior Closing-Wedge Slope Reducing High Tibial Osteotomy at the time of revision Anterior Cruciate Ligament reconstruction decreases anterior tibial translation during in vivo kinematic testing
Abstract
Introduction
The purpose of this study was to determine the changes in tibiofemoral kinematics in the operative knee following revision anterior cruciate ligament reconstruction (ACL-R) and anterior closing-wedge slope reducing high tibial osteotomy (ACWHTO) at 6- and 12-months follow-up. The hypotheses were that anterior tibial translation will be decreased after ACWHTO and that ACWHTO has no effect on tibial rotation.
Methods
This is an ongoing prospective single cohort study. Skeletally mature subjects with an ACL graft failure and posterior tibial slope greater than 12° who are scheduled for revision ACL-R and ACWHTO are being recruited and enrolled prospectively. Both knees were imaged within a biplane radiography imaging system (150 images/sec, 1ms exposure) for three trials per knee during downhill running (10° slope) at 3 m/s on an instrumented treadmill. Tibiofemoral motion was tracked with an accuracy of better than 1mm and 1° using a previously validated volumetric model-based tracking process that matched computed tomography (CT)-based subject-specific three-dimensional (3D) bone models to the synchronized biplane radiographs. CT scans were collected pre-operatively and post-operatively to create-patient-specific bone models. Tibiofemoral kinematics during stance were calculated following standard conventions and interpolated to 1% increments of stance to allow comparison among test dates and between knees. The same coordinate system was used in each knee at all test dates. Biplane radiography was collected preoperatively and at 6- and12-months follow-up in the same laboratory under the same test conditions. Postoperative tibiofemoral kinematics in the operative knee were compared to tibiofemoral kinematics preoperatively as well as the contralateral knee.
Results
At present, six subjects have been enrolled, with two subjects completing 12-month follow-up and one subject completing 6-month follow-up, with an average age of 28.0±7.6 years. Posterior tibial slope changed from 12°, 17°, and 14° preoperatively to 3°, 6°, and 5° postoperatively, respectively. Preoperatively, the average difference in anterior tibial translation between the operative and contralateral knees was 0.9 mm (operative: 9.2±4.1 mm, contralateral: 8.3±3.5 mm), but postoperatively, anterior tibial translation was decreased by an average of 4.5±2.0 mm on the operative side throughout the stance phase.
Discussion
In this ongoing prospective study, initial results suggest that ACWHTO decreases anterior tibial translation during in vivo kinematic testing, which confirms previous cadaveric studies. Further enrollment will allow for more definitive conclusions.