Hamstring vs. Patellar Tendon ACL Reconstruction

Abstract & Commentary

Synopsis: Sixty-one of 72 patients randomized into hamstring vs. patellar tendon graft ACL reconstruction returned for 2-year follow-up. The only 2 significant differences between the 2 groups at that point were weakness in isokinetic knee flexion strength among the hamstring tendon group and an increase in kneeling pain in the patellar tendon group.

Source: Aune AK, et al. Four-strand hamstring tendon autograft compared with patellar tendon-bone autograft for anterior cruciate ligament reconstruction. Am J Sports Med. 2001;29(6):722-728.

There continues to be a great deal of controversy regarding the ideal graft choice for ACL reconstruction. Advocates of hamstring grafts point to a lower incidence of knee pain and smaller incisions in their patients. Patellar tendon advocates note that some studies have demonstrated persistent weakness with knee flexion and less initial fixation strength with hamstring grafts.

In the present paper, Aune and colleagues randomized 2 similar groups of patients with subacute ACL injuries to receive either hamstring or patellar tendon grafts. The hamstrings were fixed proximally with a first generation Endobutton device with 25 mm of hamstring graft in the tunnel, and distally with an interference screw and a staple. The patellar tendon grafts were fixed on both sides with 7 ´ 25 mm interference screws. Independent observers performed follow-up at 6, 12, and 24 months postoperatively. KT-1000 laxity measurements and the Cincinnati knee scoring system were used. Anterior knee pain, kneeling pain, and hop tests were also completed. Three patients were excluded from final follow-up because they injured their contralateral leg. Eight patients were lost to follow-up.

At final follow-up there were no differences in KT-1000, Cincinnati functional scores, or hop tests between the 2 groups. The hamstring group did have improved scores for both the hop tests and patient satisfaction at 6 and 12-month follow-up, but there were no differences at 24-month follow-up. Isokinetic strength testing at 60 and 240 deg/sec showed better extension strength and endurance for the hamstring group at 6 months, but there was no difference at 12 and 24-month follow-up. There was weakness in flexion strength in the hamstring group at 12 and 24-month follow-up. This persisted at 24-month follow-up but only with testing at 240 deg/sec. Kneeling pain was significantly higher in the patellar tendon group at all follow-up periods.

Comment by Mark D. Miller, MD

This study adds to the growing body of literature suggesting that there no longer is one single "gold standard" graft for ACL reconstruction. Although this study suggests that hamstring weakness persists in patients who have had semitendinosus-gracilis grafts, many other studies refute this point. Looking carefully at the relative values for this study, knee flexion strength is approximately 85-90% of that of the patellar tendon group, and although this may be a statistically significant amount, it is probably not a clinically significant amount. Kneeling pain in the patellar tendon group is of some importance, especially in patients who may require more kneeling due to professional or religious reasons.

In sum, more and more surgeons (including myself) advocate tailoring graft selection to the individual patient. We tend to use more patellar tendon grafts in young, active, male patients without any history of anterior knee pain, and in patients with systemic hyperlaxity. We tend to use hamstring grafts in patients who are older, have a history of anterior knee pain, are involved in jumping sports, or require frequent kneeling. We are still developing the ideal "algorithm" of when to use which graft. I feel that all ACL surgeons should be familiar with both grafts, and recommend the appropriate graft for the individual circumstances of each patient.

Dr. Miller, Associate Professor, UVA Health System, Department of Orthopaedic Surgery, Charlottesville, VA, is Associate Editor of Sports Medicine Reports.