Background/Purpose: Knee joint replacement (KR) is a cost-effective procedure with good long-term outcome. However, at present there is no clear consensus on indications for KR. Imaging biomarkers capable of predicting KR therefore are urgently needed and will aid in the decision making process on a patient level as well as in clinical studies and trials.

The aim of the study was to assess if presence and severity of meniscal damage and extrusion at the time point prior to KR increases for the odds of KR, using a matched case-control study design.

Methods:

Participants were drawn from the Osteoarthritis Initiative (OAI), a multicenter observational study, including 4796 participants with, or at risk of knee osteoarthritis. 120 knees from 113 OAI participants that received KR before the 48 month visit were studied at the time point prior to KR ((e.g. for a KR reported at the 48 month (M) visit, T0 = 36M). These were matched with the same number of control knees for radiographic disease stage, gender, and age (+/- 5 y). 3Tesla MRIs were read for medial and lateral meniscal morphology and extrusion using the semiquantitative MOAKS system, which scores meniscal morphology from 0 to 8 and for the following locations: anterior horn, body, posterior horn, medial and lateral. Grades 0 and 1 are considered the reference as a grade 1 lesion depicts intrameniscal signal changes of unknown relevance. Grades 2-5 code different types of meniscal tears while grades 6-8 code different grades of meniscal maceration. Extrusion was graded from 0-3 at the medial and lateral joint lines on the coronal images.

Conditional logistic regression was applied to assess the odds of KR at T0 considering different measures of meniscal morphology.

Results:

240 knees;one knee per subject from 120 cases of KR and 120 matched controls that had available T0 data were included. Subjects were on average 65.5 ears old (SD ± 8.6), predominantly female (58.1%) and overweight (mean BMI 29.5 SD ± 4.88). Odds of KR was significantly greater for the subgroup exhibiting any type of maceration of the medial meniscal body and the medial posterior horn at T0 compared to knees without any meniscal pathology in these locations as the reference. Knees with a maximum grade of any meniscal maceration (i.e., grades 6-8)  in any of the 3 medial compartment locations had an greater odds for KR when compared to knees with a maximum  of zero or one (Figure 1).No significant associations were observed for the lateral compartment or for mensical extrusion

Conclusion:

Presence of any medial meniscal pathology of the body and any type of maceration of the medial posterior horn at T0 increases the odds for KR compared to knees without relevant meniscal alterations. Further, the odds of  KR is greater when a maximum grade of mensical maceration is present in any of the medial meniscal locations. Meniscal extrusion or pathology in the lateral compartment did not increase the odds of KR.