Computerized Navigation Technique Aided Tibial Tunnel Localization in Arthroscopic Posterior Cruciate Ligament Reconstruction

BACKGROUND: Routine posterior cruciate ligament (PCL) reconstruction can improve posterior stability of the knee joint. But the wear between graft and outlet of tibial tunnel always reduces graft mechanical strength or enlarges tunnel, resulting residual laxity. OBJECTIVE: To explore the clinical application of fluoroscopy-based navigation technique for assisting tibial tunnel placement in arthroscopic PCL reconstruction and to investigate the efficacy and feasibility of the technique. DESIGN, TIME AND SETTING: Case analysis was performed at Beijing Jishuitan Hospital between August 2006 and March 2007. PARTICIPANTS: Of 15 cases with compound ligament injury, 14 underwent allograft, and 1 underwent autograft bone-1/3 of patellar tendon-bone. METHODS: The navigation system consisted of tibia tracker fixed into the proximal tibia and tool tracker attached with PCL tibial drill guide. With registration and calibration, the navigation system identified and captured the infrared signals actively from the two trackers. The computer calculated the 3D-position of the knee joint relative to the PCL tibial drill guide and then the virtue tibial tunnel was imposed into the interactive images formed by the intraoperative C-arm images. The virtue tunnel was precisely adjusted according to the intraoperative planning protocol until the ideal position achieved. In the standard anteroposterior view, the centre of the outlet of tunnel should be in the midpoint between the medial and lateral eminence and 1.5 cm from the articular surface. In sagittal plane, with the intact posterior wall, the tibial tunnel should be as close as to the posterior proximal tibial cortex to get a maximum angulation. MAIN OUTCOME MEASURES: Fluoroscopy time and times, postoperative standard anterior and lateral X-ray, outlet of tibial tunnel, angle between graft and tunnel, attachment of tunnel to posterior cortex, and integrity of posterior wall. RESULTS: Among 15 patients, 14 succeeded without navigation related complications and I failed. The frequency of intraoperative fluoroscopy reduced from 2-10 times to 2-4 times and the exposure time for fluoroscopy shortened 10-30 minutes. The tibial outlet in all success cases was located within the tibial insertion area of posterior cruciate ligament. The average angulation between the tibial tunnel and the graft was 123.3° all cases showed close spatial relationship between tunnel and posterior proximal tibial cortex within 2 mm, with intact posterior wall in 10 cases and slightly broken in 4 cases. CONCLUSION: With high accuracy and time-saving features, fluoroscopy-based navigation system is a feasible technique in assisting tibial tunnel placement in arthroscopic PCL reconstruction surgery.