Reduced Knee Flexion Strength 18 Years After ACL Reconstruction in Hamstring Group

Introduction Rupture of the anterior cruciate ligament (ACL) is a common soft-tissue knee injury, and has increased in number over the last twenty years. Reconstructing the ligament may be important for maintaining the stability and preventing further damaging of the knee. The two most commonly used grafts in reconstructions are the autologous patellar tendon grafts and hamstring tendon grafts There is yet to be a universally established agreement regarding which reconstruction method of an ACL is preferred. The method using the central third of the patellar tendon with proximal and distal bone blocks as the replacement has been used since the late 80s and is well documented with good results. When the technique using the hamstring tendon grafts was introduced, its popularity increased. Arguments favoring each of the methods depend on which variables one values the most. In some studies, the patellar tendon group reported problems regarding anterior knee pain and decreased sensitivity of the knee, whereas for the hamstring tendon group there was reported increased weakness of the hamstring muscles and knee laxity. However, the overall assessment and satisfaction in multiple short-term/semi-long studies have shown little to no difference .

The aim of this prospective randomized multicenter study is to compare the use of bone-patellar tendon-bone (BPTB) grafts and double-looped semitendinosus gracilis (DLSG) grafts for reconstruction of the anterior cruciate ligament, 17-20 years after the surgery. The null hypothesis is that there will be no significant differences at this long-term follow-up evaluation between the two methods.

Method and material of the first study- Drogset et al. recruited 115 patients with rupture of the anterior cruciate ligament in the period of 2001-2004, and randomized them to either reconstruction with bone-patellar tendon-bone (BPTB) grafts fixed with metal interference screw graft, or double-looped semitendinosus gracilis (DLSG) grafts fixed with Bone Mulch Screws and WasherLoc Screws. The surgeries were performed at four different hospitals.

After one and two years, the patients were examined by an independent observer, using a series of objective tests, as well as recording the patients' subjective opinion of their knee function. The subjective tests used were Tegner's activity score, Lysholm's functional score and Modified Cincinnati Score. The objective tests used were Lachmann's test, pivot shift and KT-1000, as well as Cybex and Biodex to measure muscle strength.

Method and material- The present study is a long-term follow-up of a prospective randomized multicenter study. The patient recorded outcome scores will be Tegner's activity score, Lysholms's functional score and the Knee injury Osteoarthritis Outcome Score (KOOS). The examinations include Lachmann's test, pivot shift and KT-1000. We also plan to include radiographs to evaluate the degree of arthrosis 17-20 years after the surgery, and Cybex or Biodex to examine the hamstring and quadriceps strength. The radiographic positioning will be knee AP weight-bearing standing bilateral and lateral view, as well as skyline projection. The Kellgren-Lawrence classification will be used to assess the degree of osteoarthritis.