Abstract. Background. 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. Methods. 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. Results. Patients with moderate-to-severe postoperative pain demonstrated higher grades of Hoffa synovitis (P<0.001) and effusion size (P<0.001), lower PPTs (P=0.039), higher TSP (P=0.001) and lower CPM (P=0.014) when compared to patients with non-to-mild postoperative pain. No differences were found in PCS scores. Linear regression models found TSP (P=0.013), PCS (P<0.001), Hoffa synovitis (P=0.036) and effusion size (P=0.003) as independent parameters contributing to the postoperative pain severity. Conclusion. These finding indicate that chronic postoperative after TKR is a combination of joint-related synovitis and effusion in combination with sensitization of central pain mechanisms and pain catastrophizing thoughts

The Banff Patellofemoral Instability Instrument 2.0 (BPII 2.0) is a patient-reported disease-specific quality of life (QOL) outcome measure used to assess patients with recurrent lateral patellofemoral instability (LPI) both pre- and post-operatively. The purpose of this study was to compare the BPII 2.0 to four other relevant patient reported outcome measures (PROMs): the Tampa Scale-11 for kinesiophobia (TSK-11), the pain catastrophizing scale (PCS), a general QOL (EQ-5D-5L), and a return to sport index (ACL-RSI). This concurrent validation sought to compare and correlate the BPII 2.0 with these other measures of physical, psychological, and emotional health. The psychological and emotional status of patients can impact recovery and rehabilitation, and therefore a disease-specific PROM may be unable to consistently identify patients who would benefit from interventions encompassing a holistic and person-focused approach in addition to disease-specific treatment. One hundred and ten patients with recurrent lateral patellofemoral instability (LPI) were assessed at a tertiary orthopaedic practice between January and October 2021. Patients were consented into the study and asked to complete five questionnaires: the BPII 2.0, TSK-11, PCS, EQ-5D-5L, and the ACL-RSI at their initial orthopaedic consultation. Descriptive demographic statistics were collected for all patients. A Pearson's r correlation coefficient was employed to examine the relationships between the five PROMs. These analyses were computed using SPSS 28.0 © (IBM Corporation, 2021). One hundred and ten patients with a mean age of 25.7 (SD = 9.8) completed the five PROMs. There were 29 males (26.3%) and 81 females (73.6%) involving 50% symptomatic left knees and 50% symptomatic right knees. The mean age of the first dislocation was 15.4 years (SD = 7.3; 1-6) and the mean BMI was 26.5 (SD = 7.3; range = 12.5-52.6) The results of the Pearson's r correlation coefficient demonstrated that the BPII 2.0 was statistically significantly related to all of the assessed PROM's (p. There was significant correlation evident between the BPII 2.0 and the four other PROMs assessed in this study. The BPII 2.0 does not explicitly measure kinesiophobia or pain catastrophizing, however, the significant statistical relationship of the TSK-11 and PCS to the BPII 2.0 suggests that this information is being captured and reflected. The preliminary results of this concurrent validation suggest that the pre-operative data may offer predictive validity. Future research will explore the ability of the BPII 2.0 to predict patient quality of life following surgery