Around 5–15% of patients will experience chronic postoperative pain after total knee replacement (TKR) surgery but the source of the pain is unknown. The aim of this study was to assesses patients six months after TKR using magnetic resonance imaging (MRI) of the knee, pain sensory profiles and assessments of pain catastrophizing thoughts. Forty-six patients had complete postoperative data and were included. MRI findings were scored according to the MRI Osteoarthritis Knee Score (MOAKS) recommendation for Hoffa synovitis, effusion size and bone marrow lesions. Pain sensory profiles included the assessment of pressure pain thresholds (PPTs), temporal summation of pain (TSP) and conditioned pain modulation (CPM). Pain catastrophizing was assessed using the pain catastrophizing scale (PCS). Clinical pain was evaluated using a visual analog scale (VAS, 0–10cm) and groups of moderate-to-severe (VAS>3) and non-to-mild postoperative pain (VAS≤3) were identified.Abstract
Background
Methods
Painful OA is linked to CNS changes in pain processing. Temporal summation of pain (TSP) is a measure of one such CNS change, central sensitization. TSP is defined using a series (≥0.33Hz) of painful stimuli and is a predictor of postoperative pain, experienced by 20% of patients after total knee replacement (TKR) surgery. This study has developed a protocol to use functional MRI to assess CNS changes in OA pain processing. This pilot includes 3 participants with chronic knee OA pain awaiting TKR (62 ± 4.4) and 5 healthy volunteers (50 ± 13.6). 3-Tesla BOLD fMRI brain scans were recorded during short series of one second painful stimuli, applied using an automated inflatable cuff to the calf muscle of the leg with the affected knee or left side in healthy volunteers. The pain intensity at onset and during the 10 painful stimuli were recorded using a numerical rating scale. The pattern of brain activation was averaged across noxious stimuli, and the differential activation compared the 1st vs. 10th (last) stimulus. Bone marrow lesions (BMLs), synovitis and effusion size were scored from 3-Tesla knee MRI's using MOAKS scoring. TSP was raised in OA patients compared to control group (p=0.023). TSP brain activity in the chronic OA patients displayed higher signal within the subgenual anterior cingulate (sgACC) compared to healthy volunteers. Knee MRI identified OA patient's exhibited higher BML scores (p=0.038) and more knee effusion (p=0.018), but the lack of synovitis did not differ from control group (p=0.107). Enhanced TSP in chronic knee OA pain may be linked with augmented responses in emotional circuitry. BMLs and effusion size appear to contribute more with pain than synovitis. These results may help understand sensitization to improve outcomes for patients with knee OA undergoing TKR surgery.
MRI findings associated with spondyloarthritis (SpA) can be difficult to distinguish from the more prevalent findings of degeneration. Despite this, the two groups of MRI-findings are often evaluated in separate studies and in different study populations, which may reduce their applicability in daily clinical practice. The purpose of this study was to estimate the prevalence of degenerative and SpA related MRI-findings in the spine and sacroiliac joints (SIJ) in patients with persistent LBP. Patients with persistent LBP (n=1037, median age 33 [IQR 27–37], 54% women) referred to an outpatient, secondary care and non-surgical department were included in the study. MRI of the whole spine and the SIJ was performed and degenerative and SpA-related MRI-findings were evaluated by experienced musculoskeletal radiologists.Purpose and background:
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