Reduced Knee Flexion Strength 18 Years After ACL Reconstruction in Hamstring Group Compared to Patellar Tendon Group
Condition: ACL; ACL Injury; Cruciate Ligament Rupture; ACL Tear; Surgery
MeSH terms: Rupture; Anterior Cruciate Ligament Injuries
Study type: Observational

Summary: 
      Background: Bone-patellar tendon-bone (BPTB) and a double-looped semitendinosus gracilis
      (hamstring group) graft are commonly used for ACL reconstruction. Short-term and mid-term
      studies show little to no significant difference between the two groups, and there are a few
      long term studies to compare results between the two grafts.

      Purpose: To compare the results after using either BPTB grafts or hamstring grafts 18 years
      after ACL reconstruction.

      Study design: Randomized controlled trial; Level of evidence II. Methods: 114 patients with
      ACL rupture between 2001 and 2004 were randomized to reconstruction with either BPTB graft or
      a hamstring graft. Patients were operated at four major hospitals. The 18-year follow-up
      evaluation included isokinetic testing of muscle strength, patient-reported outcome measures,
      clinical knee examination and an assessment of radiological osteoarthritis using the
      Kellgren-Lawrence classification.

      Hypothesis:Hypothesis is that there will be no difference in the long-term outcome between
      the two groups, as well hypothesis of no difference in patients with prosthesis after ACL
      reconstruction, arthrosis difference in operated knees and the rate of graft failure between
      the two groups. Previous follow-up studies showed a significant difference in total flexion
      work between the two groups, so detecting a persistent difference between the groups will be
      point of interest.
    

Detailed description: 
      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.

      Even though 115 patients were included in the original study, we will only attempt to contact
      114 due to lost inclusion-papers between the 2-year and 7-year follow-up [8]. During the
      spring of 2022, the patients will receive an invite to participate in the follow-up study.
      Following this, patients will be contacted to uncover different circumstances that might
      exclude certain patients from the clinical assessment. This includes revision of the
      reconstruction in question, total knee replacement or total knee arthroplasty, and if the
      knee had been injured beforehand. The clinical examination will be carried out by both a
      medical student and an experienced orthopedic surgeon. Hopefully all the patients will be
      examined over the course of two days at each location, and if needed, the rest will be
      examined at a later date.

      Hypothesis- Current hypothesis is that there will be no difference in the long-term outcome
      between the two groups. However, it will be interesting to see how many patients have
      received a prosthesis, and how many patients struggle with arthrosis. As the previous
      follow-up studies showed a significant difference in total flexion work between the two
      groups, we will be interested in detecting a persistent difference between the groups.

      Another interesting aspect will be the rate of graft failure between the two groups.

      Feasibility- The strength of the study is the randomization and the long follow-up period of
      17-20 years. The possible limitations are the fact that there may be a problem recruiting
      enough patients to the follow-up, and that it might not be able to get x-rays of the patients
      at the different hospitals, as this is a matter of cost and availability. In addition, the
      different hospitals may not have a Biodex available.

      Publicity plan- The goal for the paper is to be published in an international journal and
      probably be presented at conferences. For article, that hopefully will be published in
      journals, Marko Popovic will stand as first author, and Julie Holen and Julie Myhre as
      contributing authors. Jon Olav Drogset will be listed last, as the main supervisor.

      Ethics- The REK-application was submitted on the 24th of December 2021. Application number:
      391796. Additionally, the project will be reported to NSD when the REK-application is
      approved.
    

Intervention name(s): ACL reconstruction
Intervention type(s): Procedure
Intervention description(s): Randomized between hamstring and patellar tendon graft
Other intervention name(s): Graft choice,
Observational model: Cohort
Time perspective: Prospective
Sampling method: Probability Sample
Study population: 
        Norwegian citizens. Patients from Trondelag county operated in Trondheim (StOlav Hospital),
        patients from Oslo operated at Lovisenberg Diaconal Hospital Oslo, patients from Hordaland
        operated at Haraldsplass Deaconess Hospital Bergen. Few patients from other counties who
        wanted operation at spesific hospital were also included if inclusion criteria were met.