Purpose of the study: This prospective randomized study was conducted to analyze the anatomic and functional impact of an extra-articular lateral plasty associated with patellar tendon-bone autograft in anterior cruciate ligament reconstruction.
Material and methods: A consecutive series of 100 patients with grade II (Noyes classification) chronic anterior laxity confirmed on stress x-rays were included in the study. All patients had a positive Trillat-Lachman test, a direct anterior drawer at 90 degrees flexion confirmed on the lateral x-ray, and an instrumental differential laxity greater than 5 mm (manual arthrometry, Medmetric KT1000). Mean patient age was 27 years (range 16-29 years) and time from the accident to ligamentoplasty was 29 months (range 3-156 months). In the operating theater, the patients were assigned at random to two groups. Group 1 (50 patients) underwent arthroscopic free patellar tendon-bone autograft reconstruction of the anterior cruciate ligament. In the second group (50 patients) the same reconstruction was further supported by a lateral extra-articular plasty using the quadriceps tendon. All patients were followed prospectively. At 58 months follow-up (none of the patients were lost to follow-up) residual laxity (Medmetric KT1000) was noted and functional outcome was assessed using the IKDC criteria. The Aglietti method was used to assess the position of the drill holes.
Results: The two groups were strictly identical at inclusion. At last follow-up, the statistical analysis did not reveal any significant difference between the groups for subjective outcome, joint motion, instrumental residual laxity, meniscal stock, or radiological changes. The overall IKDC score was A or B in 80% of the patients in group 1 and 88% of the patients in group 2. Delay to resumed sports activities (about 12 months) was also equivalent in the two groups with a trend towards lower intensity and sports producing less stress on the knee. A minimally positive pivot test with no effect on stability was observed in 4 patients in group 1 (intra-articular plasty alone) and in 2 patients in group 2 (intra- and extra-articular plasty). 16% of the insufficient results (IKDC C and D) were related to repeated tears (n=8, 6 patients in group 1 and 2 patients in group 2, p=0.268), and failure (n=8, 4 in each group) due to defective motion and pain. Repeated tears were strongly correlated with incorrect drill hole position in the tibia (p=0.01) or femur (p=0.024). Despite the stabilization, radiological remodeling was observed in 31% of the patients in both groups.
Discussion: The results in this consecutive series of patients demonstrated the good results obtained with intra-articular ligamentoplasy using the mid third of the patellar tendon. The rate of repeated tears or minimally positive pivot tests was higher in group 1 with intra-articular plasty alone but did not reach statistical significance and was generally related to a technical error in positioning the autograft, making it difficult to draw any conclusion concerning the anatomic superiority of mixed plasty.
Conclusion: At the current follow-up of 5 years, this study was unable to demonstrate any advantage of systematic conjunction of an extra-articular lateral support for advanced chronic anterior laxity of the knee treated by a free patellar tendon graft.