Aim: The aim of this study was to examine radiological and functional outcome measurements after anterior cruciate ligament (ACL) reconstruction with a bone-tendon-bone (BTB) graft. Investigations included assessment of bony integration conditions regarding the use of bioabsorbable cross pins or a lateral screw for femoral graft fixation. A description of radiological parameters in contrast with IKDC findings is also given.
Method: After ACL injuries, 45 patients underwent an ACL repair. For tibial tunnel placement the tibial guide was used in full knee extension. A size-specific femoral aimer was placed by using the transtibial technique in the "over the top" position and the tunnel was reamed with the acorn reamer to 30 mm depth. In 15 patients the BTB graft was fixed with a titanium blunt nose screw from the lateral aspect. The cross-pin technique with bioabsorbable RIGIDFIX implants was used in 30 patients. All patients underwent a follow-up study 36 month postoperatively. Geometric tests of digitised X-rays were performed. For clinical and functional outcome studies of ACL repairs the IKDC score is widely accepted. The score was modified into numeric parameters for 15 selected groups of the IKDC score. All 15 categories were rated from 1 to 4 points (Category A = 4, B = 3, C = 2, D = 1). Clinical and radiological results were statistically analysed.
Results: According to the literature, tunnel placement tibial was physiological in 91% and femoral in 93% of the cases. The femoral tunnel was completely invisible in all patients. No necrosis or pathological findings in former pin holes were seen. In 24 patients the medial compartment space was smaller, but less than 50 % compared to intraoperative X-rays. Even if the mean of tibial tunnel widening was 2.65 mm it was statistically not connected to the results of the IKDC score or X-ray findings of the femoral tunnel. Results in the IKDC groups and categories were seen to be in accord with overall very good and good outcomes. The modified IKDC score showed a mean of 55 points with a range from 46 as lowest (1 patient) and 60 in 4 patients (9%) as highest numeric score.
Conclusion: Lateral femoral fixation with screws or bioabsorbable cross-pins shows a biological bony incorporation of a BTB graft. Tibial tunnel widening was seen but without any functional effects. Overall radiological and functional outcomes based on the IKDC score demonstrate results in favour of ACL reconstruction with BTB grafts. Due to the narrowing of the medial compartment space, more radiological outcome studies with a special emphasis on degenerative aspects have to be done.