The association of magnetic resonance imaging (MRI)-detected structural pathology of the knee with crepitus in a population-based cohort with knee pain: the MoDEKO study

Osteoarthritis (OA) is the most common arthropathy of the knee joint¹. Symptoms reported by patients and signs noted during physical examination guide clinicians in identifying subjects with knee OA ^{[2], [3] and [4]}.Pain is one of the most important symptoms reported by subjects with knee OA ^{[2] and [3]}. Although very common, pain is a non-specific symptom, related to pathology in several structures within the knee joint, and includes synovitis⁵, subchondral bone marrow lesions⁶, and joint effusion⁷. Further, pain is a subjective symptom that cannot be directly measured or assessed during physical examination.Crepitus or crepitation in association with arthritis is defined as a crackling or grinding sound on joint movement with a sensation in the joint. Crepitus may occur with or without pain and is a common finding during physical examination in subjects with knee OA ^{[2], [3], [4], [8] and [9]}.It is not known whether crepitus is related to pathology in various structures within the knee. The aim of our study was to determine the cross-sectional associations of structural pathologies within the knee with crepitus in a population-based cohort with knee pain, using magnetic resonance imaging (MRI).Subjects with knee pain were recruited as a random population sample, with crepitus assessed in each compartment of the knee using a validated and standardized approach during physical examination¹⁰. MRI of the knee was performed to assess cartilage morphology, meniscal morphology, osteophytes, cruciate ligaments, and collateral ligaments. For both compartment-specific and whole-knee analyses, a multiple logistic regression analysis was performed to assess the associations of MRI-detected structural pathology with crepitus, adjusting for potential confounders. Variables were selected by backwards elimination within each compartment and in the overall knee models, and only statistically significant variables remained in the “selected” models; remaining variables in these models are adjusted for each other. An increased risk for compartment-specific crepitus was associated with osteophytes at the patellofemoral (PF) and lateral tibiofemoral (LTF) joints. Crepitus was associated with osteophytes and medial collateral ligament (MCL) pathology at the medial tibiofemoral (MTF) compartment, but cartilage damage was negatively associated with crepitus at this compartment. In the selected whole-knee model, only meniscal tears were associated with an increased risk for general crepitus. Thus, it seems that crepitus may be associated with pathology in several internal structures.