Association among meniscal tear morphology, meniscal symptoms and knee pain severity

Abstract

Purpose: Meniscal tears are present in a large percentage of patients with knee osteoarthritis (OA). It remains controversial whether all meniscal tears contribute similarly to knee symptoms and pain in patients with OA. We sought to examine the relationship between meniscal tear morphology documented onMRI and reported symptoms in patients with OA. We hypothesized that simple (e.g. vertical, radial) tears are associated with mechanical symptoms due to interference of meniscuswith smooth jointmotion,while complex andhorizontal tears, maceration, and root tears are associatedwith greater kneepain severity. Methods: We used baseline data from subjects enrolled in the Meniscal Tear in Osteoarthritis Research (MeTeOR) randomized clinical trial. Recruitedmales and females were 45 years or older and hadmeniscal tear onMRI, evidence of OAon radiographs orMRI, and at least 4weeks of knee pain and characteristicmeniscal symptoms.MRIs were read using theMRI OA Knee Score (MOAKS). Meniscal tears from both medial and lateral menisci were categorized in a hierarchical manner as follows: root tears; maceration (partial or complete, in any compartment); complex or horizontal tears. (This categorywas further stratified into longer tears spanning 2 or 3 subregions: anterior, posterior, body, and shorter tears only visualized in 1 subregion.) The final category in the hierarchy was simple tears, comprised of vertical and radial tears. Mechanical meniscal symptoms included clicking, catching and popping. Frequency of meniscal symptoms over the last week was scored 3-15, with 15 being most frequent. Pain severity was assessed using theWestern OntarioM andb)pain severity – after adjusting for age, sex, body mass index (BMI), KellgrenLawrence (KL) radiographic grade, MOAKS-based evidence of mensical extrusion, bone marrow lesions (BMLs, size and number), and Hoffa-synovitis. We also examined root tears as a binary predictor of WOMAC pain. Results: The sample consisted of 227 knees (one per person) with completeMRI and survey data. Root tearswere seen in 19%,maceration in 14%, long complexor horizontal tears in 22%, short complexor horizontal tears in 30%, and simple tears in 14% of subjects. We found neither statistically significant nor clinically important associations between meniscal tear morphology and frequency of meniscal symptoms. Root tears were associatedwith higher (worse)WOMAC pain scores than any of the other morphologies. We did not observe an association between pain severity and the BML indicators, meniscal extrusion, or Hoffa-synovitis and therefore did not include these covariates in the final model. The final models were adjusted for age, sex, BMI and KL grade because of these variables’ clinical relevance. The final models did not demonstrate associations between the tear morphologies and meniscal symptoms (Table 1). Root tear was assoiated with greater overall pain (Table 1). Further analysis with root tear as a binary predictor of WOMAC pain yielded an adjusted mean WOMAC Pain score of 45 for those with root tear and 39 without root tear (p1⁄40.03) afteradjustment forage, sex, BMIandKLgrade. Conclusions: We did not find evidence of a relationship between meniscal tear morphology and characteristic meniscal symptoms. Root tears were associated with greater knee pain than other types of meniscal lesions, even with adjustment for other demographic and imaging factors. These findings indicate that pain severity varies depending on the morphology of meniscal tear. Further studies examining the outcomes of surgical and conservativemanagement of patients with meniscal tears should take tear morphology into consideration.