Reduced Knee Flexion Strength 18 Years After ACL Reconstruction in Hamstring Group
Conditions: ACL, ACL Injury, Cruciate Ligament Rupture, ACL Tear, Surgery
Sponsor: St. Olavs Hospital

 
 
 
 
 
 
 
 
Long-term follow-up of ACL-reconstruction 
using patellar tendon graft versus hamstring 
tendon graft 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Popovic Marko 
Date 2023-04-17 
 
 

Protocol:  
 
Participating parts  
St. Olav’s Hospital, Department of Orthopedics: Marko Popovic, Jon Olav Drogset, Tone 
Gifstad.  
Lovisenberg Diaconal Hospital, Department of Orthopedics: Ingebjørg Strand.  
Haraldsplass Deaconess Hospital, Department of Orthopedics: Ingunn Fleten Mo 
Haraldsplass Deaconess Hospital, Department of Radiology: Cornelia Fischer-Bredenbeck  
Norwegian University of Science and Technology, Faculty of medicine: Julie Iren Haugseth 
Holen, Julie Rike Myhre.  
  
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 [1, 2]. Reconstructing the ligament may be 
important for maintaining the stability and preventing further damaging of the knee [1]. The 
two most commonly used grafts in reconstructions are the autologous patellar tendon grafts 
and hamstring tendon grafts [3, 4].  
There is yet to be a universally established agreement regarding which reconstruction method 
of an ACL is preferred [3-7]. 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 [6, 8]. When the technique using the hamstring tendon 
grafts was introduced, its popularity increased [7, 9]. 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 [5, 6, 8]. However, the overall assessment and satisfaction in multiple 
short-term/semi-long studies have shown little to no difference [6, 8, 10].  
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 [6]. 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. 
 
Inclusion and exclusion criteria from the original study, which also will be used for this study:  
Criteria for inclusion:   

Primary reconstructions of isolated ACL-ruptures. Surgery at least 6 weeks after injury.  Age 
18-45 years.  
The patient must understand and accept the written consent. The written consent must be 
signed by the patient before surgery. Normal two-plane X-ray of the knee.   
  
Criteria for exclusion:   
>5mm + chronic MCL-injury in the same knee.  
Patient with major additional injury in the knee: combined instability, cartilage injuries  
Outerbridge grade 3-4 and at least 1cm in diameter on the femoral condyle and major 
meniscal lesions with meniscal repairs.  
Patients having problems following the protocol.  
The patient does not understand the written consent or will not sign it.  
Patients with a history of alcohol or drug abuse the last three years.  
The patient has received any investigational drugs within 30 days prior to admittance to this 
study.  
The patient has O.A., podagra, RA, Bechterew’s disease or chondrocalcinosis.  
The patient has malalignment with more than 5 degrees valgus and no varus compared to a 
normal knee.  
The patient has patellofemoral instability.  
The patient is obese with BMI>30.  
The patient has a present or former serious illness that makes follow-up or rehabilitation of 
the patient difficult.  
Former major surgical procedures in the same knee, including prosthesis.   
Treated or untreated anterior cruciate ligament injury in the other knee.  
  
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, we will call the patients 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. We will 
try to accommodate for the patients’ needs as much as possible.   
   

Hypothesis 
Our 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. Other 
studies, such as Freedman et al., Wagner et al. and Samuelsen et al. have shown a lower rate 
of graft failure in the BPTB grafts compared to the DLSG grafts [11-13]. While Sajovic et al. 
showed the opposite; lower rate for the DLSG grafts compared to the BPTB grafts [10]. Our 
original study has yet to show any difference regarding this.  
  
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 we 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. The tentative order for the published 
article: Marko Popovic, Julie Holen, Julie Myhre, Ingebjørg Strand, Ingunn Fleten Mo, Tone 
Gifstad and Jon Olav Drogset.   
   
Economy  
Our estimated expenses include flights to Bergen and Oslo, to collect the patient data. We 
assume we’ll need two separate trips to each city, as some patients probably won’t be able to 
meet us for the first round. Round trip Bergen x2 2500 kr. Round trip Oslo x2 2500 kr.   
To contact all the possible patients, we will send out letters before contacting them by phone. 
Estimated expense: 1000 kr.  
Our intention is to include radiographs and Biodex as objective findings in the study.  
Estimated expenses for Biodex: 70000kr. Estimated expenses for radiographs: 170000kr. 
These are indicative prices from the companies we plan to buy the services from.  
We have applied to the hospital for funding at a total of 240000kr, which has been granted. 
From NTNU, our university, a total of 5000kr is granted for this project.  
 
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. 
 
  

References  
1. 
Tiamklang, T., et al., Double‐bundle versus single‐bundle reconstruction for anterior 
cruciate ligament rupture in adults. Cochrane Database of Systematic Reviews, 
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2. 
LaBella, C.R., W. Hennrikus, and T.E. Hewett, Anterior cruciate ligament injuries: 
diagnosis, treatment, and prevention. Pediatrics, 2014. 133(5): p. e1437-50.  
3. 
Sajovic, M., D. Stropnik, and K. Skaza, Long-term Comparison of Semitendinosus 
and Gracilis Tendon Versus Patellar Tendon Autografts for Anterior Cruciate 
Ligament Reconstruction: A 17-Year Follow-up of a Randomized Controlled Trial. 
The American Journal of Sports Medicine, 2018. 46(8): p. 1800-1808.  
4. 
Mascarenhas, R., et al., Bone-patellar tendon-bone autograft versus hamstring 
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Mohtadi, N.G.H., et al., Patellar tendon versus hamstring tendon autograft for 
anterior cruciate ligament rupture in adults. Cochrane Database of Systematic 
Reviews, 2011(9).  
6. 
Drogset, J.O., et al., Autologous patellar tendon and quadrupled hamstring grafts in 
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Goldblatt, J.P., et al., Reconstruction of the anterior cruciate ligament: meta-analysis 
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791-803.  
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Gifstad, T., et al., Long-term follow-up of patellar tendon grafts or hamstring tendon 
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9. 
Biau, D.J., et al., ACL Reconstruction: A Meta-analysis of Functional Scores. Clinical 
Orthopaedics and Related Research®, 2007. 458: p. 180-187.  
10. 
Sajovic, M., et al., A prospective, randomized comparison of semitendinosus and 
gracilis tendon versus patellar tendon autografts for anterior cruciate ligament 
reconstruction: five-year follow-up. Am J Sports Med, 2006. 34(12): p. 1933-40.  
11. 
Freedman, K.B., et al., Arthroscopic anterior cruciate ligament reconstruction: a 
metaanalysis comparing patellar tendon and hamstring tendon autografts. Am J 
Sports Med, 2003. 31(1): p. 2-11.  
12. 
Wagner, M., et al., Hamstring tendon versus patellar tendon anterior cruciate 
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matched-group analysis. Am J Sports Med, 2005. 33(9): p. 1327-36.  

13. 
Samuelsen, B.T., et al., Hamstring Autograft versus Patellar Tendon Autograft for  
ACL Reconstruction: Is There a Difference in Graft Failure Rate? A Meta-analysis of 
47,613 Patients. Clinical Orthopaedics and Related Research®, 2017. 475(10): p.  
2459-2468.