By Jennie McKee

Changes in meniscal, chondral damage compared to pathology at primary reconstruction may affect prognosis

Much is known about intra-articular damage in patients who undergo primary anterior cruciate ligament (ACL) reconstruction; however, the same is not true of revision ACL reconstruction patients.

“Revision ACL reconstruction is performed much less than primary reconstruction, so the incidence of meniscal injury and chondral damage in those patients has not been well established,” Christopher C. Kaeding, MD, told members of the American Orthopaedic Society for Sports Medicine.

Dr. Kaeding and his colleagues conducted one of the first studies to compare intra-articular pathology at the time of revision ACL reconstruction and at primary reconstruction using similar measurement tools, he noted, because “it’s important to understand the injuries that accompany ACL tears to determine a patient’s long-term prognosis.”

Comparing intra-articular findings
The researchers analyzed data gathered by the Multicenter Orthopedic Outcomes Network (MOON) and the Multi Center ACL Revision Study (MARS) from Jan. 1, 2007, to Nov. 1, 2008, on patients who underwent primary or revision ACL reconstruction.

MOON is a multicenter, prospective cohort that includes patients from six centers who underwent primary or revision ACL surgery. Because such a small number of revision surgeries were performed, independent risk factors for associated outcome measures after revision ACL reconstruction could not be determined. MARS, a larger collaborative effort to obtain more evidence regarding revision surgery, was created to help address this issue.

“Multicenter collaboration on data collection was necessary to address the questions addressed in this study,” noted Dr. Kaeding. “We appreciate the efforts of all the surgeons and research assistants involved in the MOON and MARS research groups.”

Dr. Kaeding and his colleagues performed a retrospective review of the data collected at the time of ACL reconstruction regarding the presence of a medial meniscus tear, lateral meniscus tear, and grade 3 or 4 chondral lesion. Of the 789 patients in the study, 508 had primary ACL reconstruction and 281 had revision ACL surgery.

Meniscal and cartilage lesions were evaluated at the time of surgery and classified according to the Outerbridge grading system (Table 1). Meniscal tears were considered as a binary variable (yes/no). Chondral lesions were also considered as a binary variable for analysis (< grade 3/≥ grade 3).

Researchers analyzed the age, gender, and body mass index of all participants, as well as descriptive statistics for meniscal injuries and chondral damage. Using multivariable logistic regression, they calculated odds ratios to evaluate the difference in meniscal tears or chondral damage at the time of primary versus revision ACL reconstruction. They also analyzed chondral damage in the medial and lateral compartments.

How primary and revision patients differed
Differences existed in both the meniscal tears and chondral damage of primary versus revision patients (Table 2). When researchers controlled for the presence of previous meniscal treatment, revision patients had decreased odds of lateral meniscal tears (odds ratio [OR] =0.54, p<0.01) but not of medial meniscal tears (or="0.86," p="0.39)" when compared with primary reconstruction patients.>

Revision patients were more likely to have Outerbridge grade 3 and 4 chondral lesions in the lateral compartment and in the patellar-trochlear compartment than primary ACL reconstruction patients.

Subjects in both groups who had previously undergone a medial meniscectomy had increased odds of having Outerbridge grade 3 and 4 chondral lesions on the medial femoral condyle (OR=1.44, p<0.01) and on the medial tibial plateau (or="1.63," p><0.01). in addition, patients in both groups who had a prior lateral meniscectomy had increased odds of having outerbridge grade 3 and 4 chondral lesions on the lateral femoral condyle (or="1.65," p><0.01) and on the lateral tibial plateau (or="1.56," p><0.01).>

Previous meniscectomy in both revision and primary ACL reconstructions was confirmed as a significant risk factor for chondral damage in the medial and lateral compartments.

“In addition,” said Dr. Kaeding, “our results confirm that the presence of meniscal injury as a risk factor for the progression of chondral injury is significant in both primary and revision ACL reconstructions.”

The significantly increased odds of chondral damage in the lateral and patellofemoral compartments in revision patients compared to primary patients may be independent of meniscus status, he said. This suggests that the progression of chondral damage following primary ACL reconstruction may have other contributing factors that are not currently recognized.

“Although our current study cannot identify all risks for the progression of chondral damage following primary reconstruction, the results suggest the need to closely examine the early period following primary ACL reconstruction and the prevention of further chondral damage,” Dr. Kaeding said. “This should be an emphasis of further study for the prevention of osteoarthritis (OA) following primary or revision ACL reconstruction.”

A recent 2-year follow-up study from Denmark that analyzed 442 revision ACL reconstructions in a population-based registry found that 26 percent of revision patients had meniscal damage and 31 percent had chondral damage, noted Dr. Kaeding.

“The prevalence of meniscal and chondral damage in revision ACL reconstructions in our study and in the Danish study suggests that these are common findings,” he said. “This indicates that orthopaedic surgeons should address issues such as return to high levels of activity and the progression of OA with their patients.

“We could not have performed this study without the work of the MOON and MARS study groups,” added Dr. Kaeding. “We encourage others to take part in this kind of collaborative research in the future.”

Dr. Kaeding’s coauthors on “Intraarticular Findings in Primary and Revision ACL Reconstruction Surgery: A Comparison of the MOON and MARS Study Groups” included lead author James Borchers, MD, MPH; Angela Pedroza, MPH; and Laura Huston, MS. Dr. Kaeding reported ties to Biomet and DJ Orthopaedics. His co-authors reported no conflicts.

Jennie McKee is a staff writer for AAOS Now. She can be reached at mckee@aaos.org

Referencs
Lind M, Menhert F, Pedersen AB: The first results from the Danish ACL reconstruction registry: Epidemiologic and 2-year follow-up results from 5,818 knee ligament reconstructions. Knee Surg Sports Traumatol Arthrosc 2009;17:117-124.

AOSSM 2009 Annual Meeting Presentations