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Predicting Results of a Second ACL Knee Surgery

Revision surgery (a second procedure) to reconstruct a ruptured anterior cruciate ligament (ACL) is fairly rare -- thank goodness! They call this a low volumesurgery. But that makes it difficult to study the results of the first surgery and predict outcomes for the second (revision) procedure.

That's why this group of surgeons got together and formed the MARS group. MARS stands for Multicenter ACL Revision Study Group. By combining patients from multiple centers under the care of multiple surgeons (87 total), it was possible to gather data on 460 patients.

For those of you who understand the complexities of research, you will be impressed to know what went into being one of the centers or surgeons included in this study. Membership in the American Orthopaedic Society for Sports Medicine was a requirement.

Attendance at a special surgeon training session was the next step. Everyone viewed videos of knees to unify how injuries were classified for the study. A manual of operating procedures was also required reading and study. Once everyone was on board and all the proper paperwork completed, then patient enrollment could begin.

The basic requirements for being in the study were: 1) an initial diagnosis of ACL deficiency, 2) surgery to reconstruct the ACL, 3) failure of the reconstruction requiring a second surgery, and 4) a willingness to stay in the study for two years.

Information collected on each of the 460 patients included typical demographic variables such as sex (male versus female), race, and age at the time of the revision. Type of first injury, type of graft used, reason for graft failure, and time between surgery and failure were recorded.

They also looked at the presence (size, location, and severity) of injury to other soft tissue structures in the knee at the time of the ACL injury. And a summary of tools used during rehab (e.g., bracing, limited weight-bearing, range-of-motion) was provided.

By combining data from a large number of patients, it is possible to conduct a research analysis called a multivariable analyses. With all the various factors that could affect treatment outcomes, this type of research design allows the surgeons to find variables that might predict treatment success or failure.

The results showed a group of mostly Caucasian (white) adults who injured (and reinjured) themselves playing sports that required jumping or cutting/changing directions suddenly.

Soccer and basketball were the two sports activities named most often but skiing, volleyball, gymnastics, football, and baseball or softball were also reported. A smaller number of patients were engaged in "other" activities listed as biking, cheerleading, dancing, martial arts, roller skating, tennis, hockey, jumping on a trampoline, or wrestling.

This study showed that multiple factors are probably at play here. The results of previous (much smaller) studies seemed to point to technical problems such as tunnel malposition for the graft as the most likely reason for graft failure.

And, in fact, this study confirmed that technical considerations are important. But age, type of graft (bone-patellar tendon-bone), and injury to the knee cartilage were also significant factors. The source of the graft (whether taken from the patient or from a donor bank) might be important but this study was unable to prove that one way or the other.

Women tended to reinjure their knees after the first surgery at an earlier age than men. Most ACL failures (62 per cent) occurred two or more years after the initial reconstructive surgery. About one-third presented during the first or second year post-op.

In summary, this is the first study of its kind to examine risk factors or predictors of failure after ACL reconstruction surgery. Using a large-scale research network in the United States and Canada, collective expertise from 87 surgeons was possible. With this type of high-level evidence, surgeons have the information they need to better counsel patients who reinjure a previously surgically reconstructed ACL.



The MARS Group. Descriptive Epidemiology of the Multicenter ACL Revision Study (MARS) Cohort. In The American Journal of Sports Medicine. October 2010. Vol. 38. No. 10. Pp. 1979-1986.


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*Disclaimer:* The information contained herein is compiled from a variety of sources. It may not be complete or timely. It does not cover all diseases, physical conditions, ailments or treatments. The information should NOT be used in place of visit with your healthcare provider, nor should you disregard the advice of your health care provider because of any information you read in this topic.
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