Does Type of Tendon Graft for ACL Reconstruction Lead to Arthritis Later?Arthritis is a well-known long-term effect of anterior cruciate ligament (ACL) reconstructive surgery. Many studies have shown that more than half the patients treated with ACL surgery end up with osteoarthritis in that knee. And that seems to be true whether the procedure was done early after the injury or later when knee instability has become chronic. There is some evidence that waiting too long can certainly make matters worse.
In this study, the question is raised: does the type of grafting done to reconstruct the torn ligament make a difference? In other words, does having a patellar tendon-bone graft contribute to more cases of knee arthritis than the 4-strand hamstring graft? Or vice versa? Or does everyone develop arthritis no matter what type of graft is done? Maybe it's just a matter of degree -- everyone gets arthritis but patients with one type of graft or the other end up with a more severe case.
To find out, a group of researchers from Norway hypothesized that there would be no difference in knee function or degree of arthritis between patients having a patellar tendon-bone graft versus a hamstring graft. Patients were randomly assigned to have one or the other reconstruction procedure. They were matched by age, gender, and activity level so the patients were very similar from one group to the other.
For surgeons interested in how the two surgical procedures were done, the authors provide a detailed description of both the patellar tendon-bone and 4-strand hamstring grafts. Harvesting and grafting techniques are provided. All grafts were autografts (tendon tissue taken from the patient) and all procedures were done by the same surgeon. Everyone followed the same postoperative and rehab program from day one through return to full activities after six months.
Over the next 10 years, the patients were followed at regular intervals. The authors summarized their findings after two years and published the results at that time. Now they are reporting their 10-year follow-up results. Activity level, knee joint laxity (looseness), muscle strength, and knee range-of motion were recorded and compared from the two year mark to the 10-year mark and between the two groups. X-rays were taken and compared with an eye toward any signs of joint arthritis.
In terms of complications, there were an equal number of graft failures in both groups requiring an ACL revision surgery. There were an equal number of patients in both groups who ended up with a torn ACL on the other side. As far as additional risk factors goes, patients in both groups gained weight and increased in their body mass index (BMI, a measure of obesity). BMI is a potential indicator of a sedentary (inactive) lifestyle. Both inactivity and being overweight are risk factors for joint osteoarthritis.
When all the data was analyzed and factors sifted through, there simply weren't any statistically significant differences between the two groups. About half of the patients who were athletes went back to their preinjury level of sports participation. But by the end of the 10 years, most were over 30 years old and no longer engaged in competitive sports events. Competitive sports had taken a back seat to recreational activities instead.
The procedures were considered a success despite the fact that there were a large number of patients (again, in both groups) who did indeed have signs of mild to moderate knee osteoarthritis. There was a tendency for patients with patellar tendon grafts to develop arthritis more often than patients with hamstring grafts but it wasn't considered statistically significant in this study.
The authors do point out that other similar studies have found differences in the long-term development of arthritis based on graft technique used. Taking a closer look at their own study and comparing to others' they thought there might be three reasons why the results of this study did not match previous studies.
First, there were quite a few patients who moved, died, dropped out, or were lost to follow-up. The reduced number of patients at the 10-year point might have made a difference in results. Second, X-rays used to identify the presence and severity of arthritis are subject to interpretation. The radiologist who read the X-rays in this study might have made different interpretations compared with radiologists involved in other studies. And third, although only two types of grafts were compared in this study, there were two different ways those grafts were attached. These different fixation techniques could have had an impact on the outcomes of surgery but were not tested for.
The conclusion drawn from this study was that the choice of graft type for ACL reconstruction surgery does not have a direct effect on the development of knee joint osteoarthritis 10 years later. This problem will continue to need further study until all risk factors and predictive factors can be identified. The goal is to find a way to prevent this complication from occurring -- either by changing when and how the surgery is performed or by choosing patients more carefully for each type of reconstructive procedure performed.
Inger Holm, PT, PhD, et al. No Difference in Knee Function or Prevalence of Osteoarthritis After Reconstruction of the Anterior Cruciate Ligament with 4-Strand Hamstring Verus Patellar Tendon-Bone Autograft. In The American Journal of Sports Medicine. March 2010. Vol. 38. No. 3. Pp. 448-454.
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