Shortening of the patellar tendon length does not influence the patellofemoral alignment in a cadaveric model

Introduction Anterior cruciate ligament (ACL) reconstruction with the use of autograft tissue represents the standard treatment. The use of a bone-patellar tendon-bone transplant for symptomatic ACL deficiency achieves good long-term results. The purpose of the study was to investigate in a cadaveric model whether reproducible patellar tendon shortening changes the patellofemoral alignment. Materials and methods Using five cadaveric knees, an MRI investigation was performed with the patellar tendon left unchanged, shortened 5 mm and shortened 10 mm, respectively, in both 20 and 45° of knee flexion. The lateral patellofemoral and the congruence angles were measured and compared using a one-way analysis of variance for repeated measurements. Results Shortening the patella tendon by approximately 20% did not significantly influence the patellofemoral alignment. Conclusion Although anterior cruciate ligament-reconstruction using the patellar tendon has become a standard procedure, postoperative problems such as anterior knee pain, and patellofemoral osteoarthritis occur quite often. In this cadaver study we did not find a significant difference for the patellofemoral alignment, irrespective of the patellar tendon length.