Patients with ACL and concomitant injuries present with increased knee rotatory laxity

More research is needed on indicating when lateral tenodesis should be performed to treat patients with an ACL injury.

Volker Musahl

Recently published results showed an association between MRI evidence of a concomitant injury to the anterolateral capsule, medial meniscus or lateral meniscus in patients with ACL injury and increased knee rotatory laxity.

“The main take home message from this paper is that high-grade knee instability is multifactorial,” Volker Musahl, MD, medical director of University of Pittsburgh Medical Center Rooney Sports Complex, told Orthopedics Today. “In our study, we showed if the anterolateral capsule is injured, it increases the pivot shift (PS) test making the knee more unstable, but also the medial meniscus, as well as the lateral meniscus,” he said.

For the study, Musahl and his colleagues had two blinded musculoskeletal radiologists review MRI scans of 41 patients for the presence of ACL injuries and concomitant soft tissue injuries, including those of the anterolateral capsule, medial collateral ligament, lateral collateral ligament, posterolateral corner, medial meniscus and lateral meniscus. Researchers used software developed at the University of Pittsburgh and performed a standardized PS test with the patient under anesthesia, during which rotatory laxity was quantified according to anterior translation of the lateral tibial compartment.

MRI findings

Results showed all patients had a complete ACL rupture. Researchers noted MRI evidence showed 51% of patients had an anterolateral capsule injury, 41% of patients had a lateral meniscus injury and 46% of patients had a medial meniscus injury. Furthermore, patients with MRI evidence of either anterolateral capsule injury, medial meniscus injury or lateral meniscus injury also had significantly higher rotatory knee laxity.

“The current trend is to supplement ACL reconstruction with extra-articular tenodesis surgery,” Musahl said. “Some of the clinical implications from this study are that if you see certain additional injury to the ACL, such as lateral meniscus injury, medial meniscus injury or anterolateral capsule injury, you will have higher grade instability and in those cases, you might want to think repairing the meniscus or capsule. If the meniscus is irreparable, then adding extra-articular tenodesis to your ACL reconstruction would be a reasonable option,” he said.

Pivot shift measurement

Despite the advantage this research had of using a device to determine exactly how big the patients’ PS was, Musahl noted the small cohort of 41 patients studied and the fact it did not assess clinical outcomes are some of its downsides. Therefore, he noted the study’s results would need to be confirmed with a larger scale clinical trial. More research is also needed into indications for the lateral tenodesis procedure in patients like these, he said

“What confuses people is how do we actually indicate the lateral tenodesis procedure,” Musahl said. “Currently, this is based on just personal preference or subjective findings of surgeons. Some of the data from this paper will probably be helping with indications. But, what we need to know is what is the natural history and do these injuries heal and how do patients do with one vs. the other surgery in the long run?” – by Casey Tingle

Reference:

Musahl V, et al. Am J Sports Med. 2016;doi:10.1177/0363546516659649.

For more information:

Volker Musahl, MD, can be reached at University of Pittsburgh Medical Center, 3200 South Water St., Pittsburgh, PA 15203; email: musahlv@upmc.edu.

Disclosure: Musahl reports he has a patent on software used to quantify clinical examinations in this study.