Exercise and Pain Neuroscience Education for Patients With Chronic Pain After Total Knee Arthroplasty: A Randomized Clinical Trial.

Importance: Up to 20% of patients develop chronic pain after total knee arthroplasty (TKA), yet there is a scarcity of effective interventions for this population. Objective: To evaluate whether neuromuscular exercise and pain neuroscience education were superior to pain neuroscience education alone for patients with chronic pain after TKA. Design, Setting, and Participants: A superiority randomized clinical trial was conducted at 3 outpatient clinics at Aalborg University Hospital in Denmark. Participants with moderate-to-severe average daily pain intensity and no signs of prosthesis failure at least 1 year after primary TKA were included. Participant recruitment was initiated on April 12, 2019, and completed on October 31, 2022. The 12-month follow-up was completed on March 21, 2023. Interventions: The study included 24 sessions of supervised neuromuscular exercise (2 sessions per week for 12 weeks) and 2 total sessions of pain neuroscience education (6 weeks between each session) or the same pain neuroscience education sessions alone. The interventions were delivered in groups of 2 to 4 participants. Main Outcomes and Measures: The primary outcome was change from baseline to 12 months using the mean score of the Knee Injury and Osteoarthritis Outcome Score, covering the 4 subscales pain, symptoms, activity of daily living, and knee-related quality of life (KOOS4; scores range from 0 to 100, with higher scores indicating better outcomes). The outcome assessors and statistician were blinded. All randomized participants were included in the intention-to-treat analysis. Results: Among the 69 participants (median age, 67.2 years [IQR, 61.2-71.9 years]; 40 female [58%]) included in the study, 36 were randomly assigned to the neuromuscular exercise and pain neuroscience education group, and 33 to the pain neuroscience education-alone group. The intention-to-treat analysis showed no between-group difference in change from baseline to 12 months for the KOOS4 (7.46 [95% CI, 3.04-11.89] vs 8.65 [95% CI, 4.67-12.63] points; mean difference, -1.33 [95% CI, -7.59 to 4.92]; P = .68). Among the 46 participants who participated in the 12-month assessment in the 2 groups, 16 (34.8%) experienced a clinically important improvement (a difference of ≥10 points on the KOOS4) with no between-group difference. No serious adverse events were observed. Conclusions and Relevance: In this randomized clinical trial, the results demonstrated that neuromuscular exercises and pain neuroscience education were not superior to pain neuroscience education alone in participants with chronic pain after TKA. Approximately one-third of the participants, regardless of intervention, experienced clinically important improvements. Future studies should investigate which patient characteristics indicate a favorable response to exercises and/or pain neuroscience education. Trial Registration: ClinicalTrials.gov Identifier: NCT03886259.

Stable fixation of an ultra-short femoral neck-preserving hip prosthesis: a 5-year RSA, DXA, and clinical prospective outcome study of 48 patients.

BACKGROUND AND PURPOSE: We previously showed promising primary stability and preservation of bone stock with the ultra-short neck-loading hip implant in total hip arthroplasty (THA). The aim of this study was to evaluate clinical outcome, implant stability, and bone mineral density (BMD). METHODS: 50 patients were treated with the ultra-short neck Primoris hip implant at baseline and 48 were available for evaluation at 5-year follow-up. 5 different patient-reported outcome measures (PROMs) including hip-specific scores, disease-specific and generic quality of life outcome measures, and an activity score were used. Furthermore, implant stability using radiostereometric analysis (RSA) and assessment of periprosthetic BMD using dual-energy X-ray absorptiometry (DXA) were applied. RESULTS: By 1-year follow-up, all PROMs showed improvements and remained high at 5-year follow-up. After initial distal translation (subsidence) and negative rotation around the z-axis (varus tilt) the implant showed stable fixation at 5-year follow-up with no further migration beyond 12 months. In the regions of interest (ROI) 3 and 4, BMD remained stable. In ROI 2, further bone loss of 12% was found at 5-year follow-up. CONCLUSION: Clinical outcome including PROMs was satisfying throughout the 5-year follow-up period. The hip implant remains stable with both bone preservation and loss 5 years after surgery.

Hospital variation in revision rates after primary knee arthroplasty was not explained by patient selection: baseline data from 1452 patients in the Danish prospective multicenter cohort study, SPARK.

PURPOSE: Revision rates following primary knee arthroplasty vary by country, region and hospital. The SPARK study was initiated to compare primary surgery across three Danish regions with consistently different revision rates. The present study investigated whether the variations were associated with differences in the primary patient selection. METHODS: A prospective observational cohort study included patients scheduled Sep 2016 Dec 2017 for primary knee arthroplasty (total, medial/lateral unicompartmental or patellofemoral) at three high-volume hospitals, representing regions with 2-year cumulative revision rates of 1, 2 and 5%, respectively. Hospitals were compared with respects to patient demographics, preoperative patient-reported outcome measures, motivations for surgery, implant selection, radiological osteoarthritis and the regional incidence of primary surgery. Statistical tests (parametric and non-parametric) comprised all three hospitals. RESULTS: Baseline data was provided by 1452 patients (89% of included patients, 56% of available patients). Patients in Copenhagen (Herlev-Gentofte Hospital, high-revision) were older (68.6 ± 9 years) than those in low-revision hospitals (Aarhus 66.6 ± 10 y. and Aalborg (Farsø) 67.3 ± 9 y., p = 0.002). In Aalborg, patients who had higher Body Mass Index (mean 30.2 kg/m2 versus 28.2 (Aarhus) and 28.7 kg/m2 (Copenhagen), p < 0.001), were more likely to be male (56% versus 45 and 43%, respectively, p = 0.002), and exhibited fewer anxiety and depression symptoms (EQ-5D-5L) (24% versus 34 and 38%, p = 0.01). The preoperative Oxford Knee Score (23.3 ± 7), UCLA Activity Scale (4.7 ± 2), range of motion (Copenhagen Knee ROM Scale) and patient motivations were comparable across hospitals but varied with implant type. Radiological classification ≥ 2 was observed in 94% (Kellgren-Lawrence) and 67% (Ahlbäck) and was more frequent in Aarhus (low-revision) (p ≤ 0.02), where unicompartmental implants were utilized most (49% versus 14 (Aalborg) and 23% (Copenhagen), p < 0.001). In the Capital Region (Copenhagen), the incidence of surgery was 15-28% higher (p < 0.001). CONCLUSION: Patient-reported outcome measures prior to primary knee arthroplasty were comparable across hospitals with differing revision rates. While radiographic classifications and surgical incidence indicated higher thresholds for primary surgery in one low-revision hospital, most variations in patient and implant selection were contrary to well-known revision risk factors, suggesting that patient selection differences alone were unlikely to be responsible for the observed variation in revision rates across Danish hospitals. LEVEL OF EVIDENCE: II, Prospective cohort study.

Patients in high- and low-revision hospitals have similar outcomes after primary knee arthroplasty: 1-year postoperative results from the Danish prospective multicenter cohort study, SPARK.

PURPOSE: It is well-known that revision rates after primary knee arthroplasty vary widely. However, it is uncertain whether hospital revision rates are reliable indicators of general surgical quality as defined by patients. The SPARK study compared primary knee arthroplasty surgery at three high-volume hospitals whose revision rates differed for unknown reasons. METHODS: This prospective observational study included primary knee arthroplasty patients (total, medial/lateral unicompartmental and patellofemoral) in two low-revision hospitals (Aarhus University Hospital and Aalborg University Hospital Farsø) and one high-revision hospital (Copenhagen University Hospital Herlev-Gentofte). Patients were followed from preoperatively (2016-17) to 1-year postoperatively with patient-reported outcome measures including Oxford Knee Score (OKS), EQ-5D-5L and Copenhagen Knee ROM (range of motion) Scale. The surgical outcomes were compared across hospitals for patients with comparable grades of radiographic knee osteoarthritis and preoperative OKS. Statistical comparisons (parametric and non-parametric) included all three hospitals. RESULTS: 97% of the 1452 patients who provided baseline data (89% of those included and 56% of those operated) responded postoperatively (90% at 1 year). Hospitals' utilization of unicompartmental knee arthroplasties differed (Aarhus 49%, Aalborg 14%, and Copenhagen 22%, p < 0.001). 28 patients had revision surgery during the first year (hospital independent, p = 0.1) and were subsequently excluded. 1-year OKS (39 ± 7) was independent of hospital (p = 0.1), even when adjusted for age, sex, Body Mass Index, baseline OKS and osteoarthritis grading. 15% of patients improved less than Minimal Important Change (8 OKS) (Aarhus 19%, Aalborg 13% and Copenhagen 14%, p = 0.051 unadjusted). Patients with comparable preoperative OKS or osteoarthritis grading had similar 1-year results across hospitals (OKS and willingness to repeat surgery, p ≥ 0.087) except for the 64 patients with Kellgren-Lawrence grade-4 (Aarhus 4-6 OKS points lower). 86% of patients were satisfied, and 92% were "willing to repeat surgery", independent of hospital (p ≥ 0.1). Hospital revision rates differences diminished during the study period. CONCLUSIONS: Patients in hospitals with a history of differing revision rates had comparable patient-reported outcomes 1 year after primary knee arthroplasty, supporting that surgical quality should not be evaluated by revision rates alone. Future studies should explore if revision rate variations may depend as much on revision thresholds and indications as on outcomes of primary surgery. LEVEL OF EVIDENCE: Level II (Prospective cohort study).

An AI-based patient-specific clinical decision support system for OA patients choosing surgery or not: study protocol for a single-centre, parallel-group, non-inferiority randomised controlled trial.

BACKGROUND: Osteoarthritis (OA) affects 20% of the adult Danish population, and the financial burden to society amounts to DKK 4.6 billion annually. Research suggests that up to 75% of surgical patients could have postponed an operation and managed with physical training. ERVIN.2 is an artificial intelligence (AI)-based clinical support system that addresses this problem by enhancing patient involvement in decisions concerning surgical knee and hip replacement. However, the clinical outcomes and cost-effectiveness of using such a system are scantily documented. OBJECTIVE: The primary objective is to investigate whether the usual care is non-inferior to ERVIN.2 supported care. The second objective is to determine if ERVIN.2 enhances clinical decision support and whether ERVIN.2 supported care is cost-effective. METHODS: This study used a single-centre, non-inferiority, randomised controlled in a two-arm parallel-group design. The study will be reported in compliance with CONSORT guidelines. The control group receives the usual care. As an add-on, the intervention group have access to baseline scores and predicted Oxford hip/knee scores and HRQoL for both the surgical and the non-surgical trajectory. A cost-utility analysis will be conducted alongside the trial using a hospital perspective, a 1-year time horizon and effects estimated using EQ-5D-3L. Results will be presented as cost per QALY gain. DISCUSSION: This study will bring knowledge about whether ERVIN.2 enhances clinical decision support, clinical effects, and cost-effectiveness of the AI system. The study design will not allow for the blinding of surgeons. TRIAL REGISTRATION: ClinicalTrials.gov NCT04332055 . Registered on 2 April 2020.

Five-year follow-up of patients with knee osteoarthritis not eligible for total knee replacement: results from a randomised trial.

OBJECTIVES: The main objective was to investigate 5-year outcomes in patients with knee osteoarthritis, randomised to one of two non-surgical treatments. SETTING: Two outpatient clinics. PARTICIPANTS: At baseline, 100 patients with radiographic and symptomatic knee osteoarthritis not found eligible for knee replacement (KR) were included. Main exclusion criteria were average score above 75 of the Knee injury and Osteoarthritis Outcome Score (KOOS) subscales pain, symptoms, function of daily living and quality of life; KOOS4 and average knee pain the previous week greater than 60 mm on a 100 mm visual analogue scale. INTERVENTIONS: Patients were randomised to supervised non-surgical treatment consisting of patient education, supervised exercise, weight loss, insoles, and pain medication (the MEDIC treatment) or written advice. The 12-week MEDIC treatment included patient education, neuromuscular exercise, insoles and a dietary weight loss programme and/or pain medication if needed and written advice consisted of two leaflets. PRIMARY AND SECONDARY OUTCOME MEASURES: Primary outcome was 5-year mean change for KOOS4. Secondary outcomes included KOOS subscales, self-reported health, usage of pain medication and self-reported physical activity. RESULTS: Thirty-nine (78%) and 36 (72%) from the MEDIC and written advice groups responded at 5 years. There were no between-group differences in KOOS4 (difference 5.3 (95% CI -1.5 to 12.1) or any secondary outcomes. However, the 95% CI included the minimal clinically important difference for the main outcome.Seventy-six percent of the MEDIC group and 66% of the written advice group experienced clinically important improvements in KOOS4.Fifteen patients (30%) from the MEDIC group and 17 (34%) from the written advice group received KR in the index knee. Undergoing KR did not result in a statistically significant greater improvement in KOOS4 (difference 6.1 (95% CI -1.1 to 13.4). CONCLUSIONS: No statistically significant differences between supervised non-surgical treatment and written advice were demonstrated at 5 years. Most patients experienced clinically important improvements, irrespective of initial treatment strategy or KR. TRIAL REGISTRATION NUMBER: NCT01535001; ClinicalTrials.gov.

Patient-Reported Outcomes for Function and Pain in Total Knee Arthroplasty Patients.

BACKGROUND: Some patients undergoing total knee arthroplasty successfully manage their condition postoperatively, whereas others encounter challenges in regaining function and controlling pain during recovery at home. OBJECTIVE: The aim of this study was to use traditional statistics and machine learning to develop prediction models that identify patients likely to have increased care needs related to managing function and pain following total knee arthroplasty. METHODS: This study included 201 patients. Outcomes were changes between baseline and follow-up in the functional and pain subcomponents of the Oxford Knee Score. Both classification and regression modeling were applied. Twenty-one predictors were included. Tenfold cross-validation was used, and the regression models were evaluated based on root-mean-square error, mean absolute error, and coefficient of determination. Classification models were evaluated based on the area under the receiver operating curve, sensitivity, and specificity. RESULTS: In classification modeling, random forest and stochastic gradient boosting provided the best overall metrics for model performance. A support vector machine and a stochastic gradient boosting machine in regression modeling provided the best predictive performance. The models performed better in predicting challenges related to function compared to challenges related to pain. DISCUSSION: There is valuable predictive information in the data routinely collected for patients undergoing total knee arthroplasty. The developed models may predict patients who are likely to have enhanced care needs regarding function and pain management. Improvements are needed before the models can be implemented in routine clinical practice.

The potential of dividing the oxford knee score into subscales for predicting clinically meaningful improvements in pain and function of patients undergoing total knee arthroplasty.

BACKGROUND: Subdividing the Oxford Knee Score (OKS) into a pain component scale (OKS-PCS) and a function component scale (OKS-FCS) for predicting clinically meaningful improvements may provide a basis for identifying patients in need of enhanced support from health care professionals to manage pain and functional challenges following total knee arthroplasty. AIM: To assess the potential of dividing the OKS into subscales for predicting clinically meaningful improvements in pre- and postoperative pain and function by comparing two different versions of extracting pain and function derived from the OKS. METHODS: This retrospective observational cohort study included 201 patients undergoing total knee arthroplasty. Multiple logistic regression analysis was applied for binary classification of whether patients achieved clinically meaningful improvements in pain and function. RESULTS: The best overall version for predicting clinically meaningful improvements had an area under the receiver operating characteristic curve of 0.79 for both pain and function, whereas Nagelkerke's R2 was 0.322 and 0.334, respectively. CONCLUSION: The findings indicate that it is reasonable to subdivide the OKS into subscales for predicting clinically meaningful improvements in pain and function. However, more studies are needed to compare various types of classification algorithms in larger patient populations.

The influence of migration of the exeter V40 stem on patient reported outcome measures: a 2-year follow-up of 112 total hip arthroplasties using radiostereometric analysis.

PURPOSE: The cemented Exeter V40 stem is known to migrate distally. Several previous studies have reported on the extent of stem migration and its influence on clinical outcome. However, no studies have investigated the influence of stem migration on Patient Reported Outcome Measures (PROM). METHODS: One hundred and twelve total hip arthroplasties (THA) were included in a 2-year follow-up using Radiostereometric Analysis (RSA). Patients were evaluated using the Oxford Hip Score (OHS) and EQ-5D-3L PROMs. The purpose of this study was to assess the influence of stem migration, measured by Maximum Total Point Motion (MTPM), on the 2-year postoperative score (OHS and EQ-5D). Furthermore, the influence of pre-operative PROM, age, gender, acetabular component and BMI was associated with the 2-year postoperative OHS and EQ-5D scores. RESULTS: MTPM was a non-significant predictor of the 2-year postoperative OHS (regression coefficient (B) = - 2.38 (CI - 5.44; .69)) and of the 2-year postoperative EQ-5D (B = - .01 (CI - .04; .02)). The only significant predictor of the 2-year postoperative OHS and 2-year postoperative EQ-5D was gender (B = 8.71 (CI 3.52; 13.90)) and (B = .13 (CI .07; .18)), respectively. CONCLUSION: Stem migration did not significantly influence PROMs at 2 years post-operatively. Using a patient-focused approach, our results seem to corroborate results reported by previous studies, showing that slow migration of the Exeter V40 stem does not seem to influence the clinical outcome.

Development, construction, and validation of a thinner uniplanar calibration cage for radiostereometry.

Radiostereometric analysis (RSA) is an accurate and precise radiographic method that can be used to measure micromotion of implants and study joint kinematics in vivo. A calibration cage with radiopaque markers is used to calibrate the RSA images; however, the thickness (250 mm) of the calibration cage restricts the available area for the patient and equipment during RSA recordings. A thinner calibration cage would increase the recording area, facilitate handling of the cage, and ease integration of the cage with the RSA system. We developed a thinner calibration cage without compromise of accuracy and precision. First, we performed numerical simulations of an RSA system, and showed that the calibration cage thickness could be decreased to 140 mm maintaining accuracy and precision using 40 fiducial and 30 control markers. Second, we constructed a new calibration cage (NRT cage) according to the simulation results. Third, we validated the new calibration cage against two state-of-the-art calibration cages (Umeaa cage and Leiden cage) in a phantom study. All cages performed similar for marker-based analysis, except for y-rotation, where the Umeaa cage (SD = 0.064 mm) was less precise compared to the NRT (SD = 0.038 mm) and Leiden cages (0.042 mm) (p = .01). For model-based analysis the NRT cage had superior precision for translations (SD ≤ 0.054 mm) over the Leiden cage (SD ≤ 0.118 mm) and Umeaa cage (SD ≤ 0.093 mm) (p < .01). The combined study confirmed that the new and thinner calibration cage maintained accuracy and precision at the level of existing thicker calibration cages.

The association between sleep quality, preoperative risk factors for chronic postoperative pain and postoperative pain intensity 12 months after knee and hip arthroplasty.

BACKGROUND: Chronic postoperative pain following total joint replacement (TJA) is a substantial clinical problem, and poor sleep may affect predictive factors for postoperative pain, such as pain catastrophizing. However, the magnitude of these associations is currently unknown. This exploratory study investigated (1) the relationship between preoperative sleep quality, clinical pain intensity, pain catastrophizing, anxiety, and depression and (2) their associations with chronic postoperative pain following TJA. METHODS: This secondary analysis from a larger randomized controlled trial included rest pain intensity (preoperative and 12 months postoperative; visual analogue scale, VAS), preoperative Pittsburgh Sleep Quality Index (PSQI), Pain Catastrophizing Scale (PCS), Hospital Anxiety and Depression Scale (HADS) data from 74 knee and 89 hip osteoarthritis (OA) patients scheduled for TJA. Poor sleepers were identified based on preoperative PSQI scores higher than 5. RESULTS: Poor sleepers demonstrated higher preoperative VAS, pain catastrophizing, anxiety, and depression compared with good sleepers (all p < 0.003). Preoperative PSQI (ß = 0.23, p = 0.006), PCS (ß = 0.44, p < 0.005), and anxiety (ß = 0.18, p = 0.036) were independent factors for preoperative VAS. Preoperative VAS (ß = 0.32, p < 0.005), but not preoperative sleep quality (ß = -0.06, p = 0.5), was an independent factor for postoperative VAS. CONCLUSION: The OA patients reporting poor preoperative sleep quality show higher preoperative pain, pain catastrophizing, anxiety, and depression. High preoperative pain intensity, but not poor sleep quality, was associated with higher chronic postoperative pain intensity. Future studies are encouraged to explore associations between sleep and chronic postoperative pain.

Measurement properties of UCLA Activity Scale for hip and knee arthroplasty patients and translation and cultural adaptation into Danish.

Background and purpose - The UCLA Activity Scale (UCLA) is a questionnaire assessing physical activity level from 1 (low) to 10 (high) in patients undergoing hip or knee arthroplasty (HA/KA). After translation and cultural adaptation, we evaluated the measurement properties of the Danish UCLA.Patients and methods - After dual panel translation, cognitive interviews were performed among 55 HA/KA patients. An orthopedic surgeon and a physiotherapist estimated UCLA scores for 80 KA patients based on short interviews. Measurement properties were evaluated in 130 HA and 134 KA patients preoperatively and 1-year postoperatively.Results - To suit Danish patients of today, several adaptations were required. Prior to interviews, 4 patients were excluded, and 11 misinterpreted the answer options. Examiners rated the remaining 65 patients (mean age 67 years) 0.2-1.6 UCLA levels lower than patients themselves. The 130 HA and 134 KA patients (mean age 71/68 years) changed from 4.3 (SD 1.9)/4.5 (1.8) preoperatively to 6.6 (1.8)/6.2 (1.0) at 1-year follow-up. 103 (79%) HA and 89 (66%) KA patients reported increased activity. Effect sizes were large (1.2/0.96). Knee patients reaching minimal important change (MIC, ≥ 8 Oxford Knee Score points) had higher 1-year UCLA scores than patients not reaching MIC.Interpretation - Original scale development was undocumented. Content validity was questionable, and there was discrepancy between patient and examiner estimates. UCLA appears valuable for measuring change in self-reported physical activity on a group level. 4 out of 5 HA patients and 2 out of 3 KA patients were more physically active 1 year after joint replacement surgery.

Hip geometry in hip fracture patients in Greenland occurring over a 7.7-year period.

BACKGROUND: Hip geometry influences hip fracture risk. Hip fractures are common, and they are associated with pain, disability, premature death and marked costs on society. Osteoporotic fractures are frequent in Arctic populations and increase with advancing age in this society with a steep rise in life expectancy. Greenland Inuit is a distinct ethnic group, and data on hip geometry is missing. We thus aimed to describe hip geometry in 7.7 years of consecutive hip fracture patients in Greenland. METHODS: We evaluated collodiaphysial angle, femoral neck length, the outer and inner diameter of the femur at 2 and 5 centimetres below the centre of the lesser trochanter and the cortical thickness from pelvic and hip radiographs in all patients operated in Greenland over 7.7 years. We included all 84 patients with one non-fractured hip visible for geometric analysis. Analyses were conducted in duplicate. RESULTS: We found a collodiaphysial angle of 134.8/132.6o in men/women (p = 0.06) and a femoral neck length of 38.0/33.9 mm in men/women (p = 0.001). Cortical thickness was affected by sex in the adjusted analysis (p < 0.001). Cortical thickness index at 5 cm below the centre of the lesser trochanter decreased with age (p = 0.026) and may be influenced by height (2 cm below the centre of the lesser trochanter, p = 0.053). CONCLUSION: Our findings differed from European data and suggest a delicate balance in hip geometry in Arctic populations. Ethnic peculiarities influence the structure of the hip and may influence fracture risk. A focus on hip geometry and risk factors for osteoporotic fractures in Arctic populations is warranted.

The Combination of Preoperative Pain, Conditioned Pain Modulation, and Pain Catastrophizing Predicts Postoperative Pain 12 Months After Total Knee Arthroplasty.

OBJECTIVES: Approximately 20% of knee osteoarthritis patients undergoing total knee arthroplasty (TKA) report chronic postoperative pain. Studies suggest that preoperative variables such as impaired descending pain control, catastrophizing, function, and neuropathic pain-like symptoms may predict postoperative pain 12 months after TKA, but the combined prediction value of these factors has not been tested. The current prospective cohort study aimed to combine preoperative risk factors to investigate the predictive value for postoperative pain 12 months after TKA. DESIGN: Prospective cohort with follow-up 12 months after surgery. PATIENTS: A consecutive sample of 131 knee osteoarthritis patients undergoing TKA. METHODS: Pain intensity, Pain Catastrophizing Scale (PCS) scores, PainDETECT Questionnaire scores, conditioned pain modulation (CPM), and Oxford Knee Score (OKS) were obtained before and 12 months after TKA. RESULTS: TKA improved pain (P < 0.001), PCS scores (P < 0.001), PainDETECT Questionnaire scores (P < 0.001), and OKSs (P < 0.001). Preoperative pain correlated with preoperative PCS scores (r = 0.38, P  <  0.001), PainDETECT scores (r = 0.53, P  <  0.001), and OKSs (r = -0.25, P  =  0.001). Preoperative PainDETECT scores were associated with preoperative PCS scores (r = 0.53, P  <  0.001) and OKSs (r = -0.25, P  =  0.002). Higher postoperative pain was correlated with high preoperative pain (r = 0.424, P  <  0.001), PCS scores (r = 0.33, P  <  0.001), PainDETECT scores (r = 0.298, P  =  0.001), and lower CPM (r = -0.18, P  =  0.04). The combination of preoperative pain, PCS score, and CPM explained 20.5% of variance in follow-up pain. PCS scores had a significant effect on pain trajectory when accounting for patient variance (t  =  14.41, P  <  0.0005). CONCLUSION: The combination of high preoperative clinical pain intensity, high levels of pain catastrophizing thoughts, and impaired CPM may predict long-term postoperative pain 12 months after surgery.

Calcified cartilage in patients with osteoarthritis of the hip compared to that of healthy subjects. A design-based histological study.

OBJECTIVE: Calcified cartilage is suggested to be involved in the pathogenesis of osteoarthritis (OA) by facilitating endochondral ossification at the bone-cartilage unit. Therefore, the objective was to quantify the volume and surface area of the calcified cartilage in the femoral head in OA patients and healthy subjects. MATERIALS AND METHODS: We used design-based stereological principles, i.e., systematic uniform random sampling and vertical uniform random sections of the entire femoral head. We investigated the articular and calcified cartilage and femoral head surface area and volume, excluding fovea capitis and marginal osteophytes, in 20 patients with OA and 15 healthy subjects. RESULTS: The volume of the calcified cartilage was significantly larger for the patients with OA compared with the healthy subjects (mean difference [95% CI]) (284 [110,457] mm3, p = 0.002). The upper and lower surface area of the calcified cartilage, i.e. the tidemark and cement line, were both significantly larger for OA patients compared with the healthy subjects (17.8 [8.4,27.3] cm2, p < 0.001) and (38.7 [20.8,56.7] cm2, p = 0.002), respectively. The volume of the calcified cartilage and the volume of the femoral head were significantly correlated for the patients with OA (Spearman's ρ = 0.51, p = 0.021), but not for the healthy subjects (ρ = 0.41, p = 0.123). CONCLUSIONS: Patients with OA had a larger femoral head surface area and more calcified cartilage compared to healthy subjects. The volume of the calcified cartilage correlated positively with the volume of the femoral head for patients with OA, but not for healthy subjects. This strongly supports the existing view that bone growth in OA is associated with endochondral ossification.

Histomorphometric case-control study of subarticular osteophytes in patients with osteoarthritis of the hip.

OBJECTIVE: The objective of this cross-sectional case-control study was to determine the prevalence and size of marginal and subarticular osteophytes in patients with osteoarthritis (OA), and to compare these to that of a control group. DESIGN: We investigated femoral heads from 25 patients with OA following hip replacement surgery, and 25 femoral heads from a control group obtained post-mortem. The area and boundary length of the femoral head, marginal osteophytes, and subarticular osteophytes were determined with histomorphometry. Marginal osteophytes were defined histologically as bony projections at the peripheral margin of the femoral head, while subarticular osteophytes were defined as areas of bone that expanded from the normal curvature of the femoral head into the articular cartilage. RESULTS: The prevalence of OA patients with marginal- and subarticular osteophytes were 100 and 84%, respectively. Whereas the prevalence of the participants in the control group with marginal- and subarticular osteophytes were 56 and 28%, respectively. The area and boundary length of marginal osteophytes was (median (Interquartile range)) 165.3mm2 (121.4-254.0) mm2 and 75.1 mm (50.8-99.3) mm for patients with OA compared to 0 mm2 (0-0.5) mm2 and 0 mm (0-0.5) mm for the control group (P <  0.001). For the subarticular osteophytes, the area and boundary length was 1.0 mm2 (0-4.4) mm2 and 1.4 mm (0-6.5) mm for patients with OA compared to 0 mm2 (0-0.5) mm2 and 0 mm (0-0.5) mm for the control group (P <  0.001). CONCLUSION: As expected, both marginal- and subarticular osteophytes at the femoral head, were more frequent and larger in patients with OA than in the control group. However, in the control group, subarticular osteophytes were more prevalent than expected from the minor osteophytic changes at the femoral head margin, which may suggest that subarticular osteophytes are an early degenerative phenomenon that ultimately might develop into clinical osteoarthritis.

Evaluating the Use of a PRO Questionnaire in Clinical Practice.

Aalborg University Hospital in Farsø uses data from a patient-reported outcome (PRO) questionnaire in order to predict if patients diagnosed with osteoarthritis will benefit from surgery. The purpose of including PRO in the decision-making is to ensure quality and transparency, to include patients in their own treatment, and to make the patients central to both the decision-making and the dialogue. Our evaluation of the use of the PRO questionnaire is based on the observation of patients filling out the questionnaire and interviews with 7 patients and a doctor. We found that there were several usability issues especially for the patients, such as navigation problems and a lack of consistency in the layout of the measurement scales. Furthermore, some questions were difficult for the patients to interpret. The interviewed patients did not report any value from answering the questionnaire. We argue that it may take more than filling out a questionnaire for the patient to feel involved in their own treatment.

Cost-effectiveness of total knee replacement in addition to non-surgical treatment: a 2-year outcome from a randomised trial in secondary care in Denmark.

OBJECTIVE: To assess the 24-month cost-effectiveness of total knee replacement (TKR) plus non-surgical treatment compared with non-surgical treatment with the option of later TKR if needed. METHODS: 100 adults with moderate-to-severe knee osteoarthritis found eligible for TKR by an orthopaedic surgeon in secondary care were randomised to TKR plus 12 weeks of supervised non-surgical treatment (exercise, education, diet, insoles and pain medication) or to supervised non-surgical treatment alone. Including quality-adjusted life years (QALYs) data from baseline, 3, 6, 12 and 24 months, effectiveness was measured as change at 24 months. Healthcare costs and transfer payments were derived from national registries. Incremental healthcare costs, and incremental cost-effectiveness ratios (ICERs) were calculated. A probabilistic sensitivity analysis was conducted and the probability of cost-effectiveness was estimated at the 22 665 Euros/QALY threshold defined by the National Institute for Health and Care Excellence. RESULTS: TKR plus non-surgical treatment was more expensive (mean of 23 076 vs 14 514 Euros) but also more effective than non-surgical treatment (mean 24-month improvement in QALY of 0.195 vs 0.056). While cost-effective in the unadjusted scenario (ICER of 18 497 Euros/QALY), TKR plus non-surgical treatment was not cost-effective compared with non-surgical treatment with the option of later TKR if needed in the adjusted (age, sex and baseline values), base-case scenario (ICER of 32 611 Euros/QALY) with a probability of cost-effectiveness of 23.2%. Including deaths, TKR plus non-surgical treatment was still not cost-effective (ICERs of 46 277 to 64 208 Euros/QALY). CONCLUSIONS: From a 24-month perspective, TKR plus non-surgical treatment does not appear to be cost-effective compared with non-surgical treatment with the option of later TKR if needed in patients with moderate-to-severe knee osteoarthritis and moderate intensity pain in secondary care in Denmark. Results were sensitive to changes, highlighting the need for further confirmatory research also assessing the long-term cost-effectiveness of TKR. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov (NCT01410409).

Investigating the Effect of Perioperative Chlorzoxazone on Acute Postoperative Pain After Total Hip and Knee Replacement Surgery.

BACKGROUND AND AIMS: Severe preoperative and acute postoperative pain have been associated with the development of chronic postoperative pain. Chlorzoxazone (a muscle relaxant) has been suggested to enhance acute postoperative pain recovery, but the lack of larger randomized controlled trials has, however, questioned the continued use. Despite this, chlorzoxazone is still used for acute postoperative pain management following total knee replacement (TKR) or total hip replacement (THR). The current randomized, double-blinded, placebo-controlled, parallel-group, clinical trial aimed to assess the effect of chlorzoxazone for postoperative pain management following TKR or THR. METHODS: A total of 393 patients scheduled for TKR or THR were included in the trial. Patients were assigned to 250 mg chlorzoxazone 3 times daily for the first 7 days postoperatively or to placebo. The primary outcome was pain after 5 m walk assessed 24 hours postoperatively. Secondary outcomes included changes in preoperative pain at rest, worst pain in the last 24 hours, and Oxford Knee or Hip Score compared with 12 months' follow-up. In addition, adverse events were assessed in the perioperative period. RESULTS: No significant differences were found for any of the outcome parameters after TKR or THR. As regards TKR or THR, no effects were demonstrated for pain after 5 m walk 24 hours after surgery (P>0.313), or for any of the secondary outcomes (P>0.288) or adverse events (P>0.112) in the group receiving chlorzoxazone compared with placebo. CONCLUSION: The current study demonstrated no analgesic effects of postoperative chlorzoxazone administration compared with placebo on acute or chronic postoperative pain 12 months following TKR and THR.

An Ultra-Short Femoral Neck-Preserving Hip Prosthesis: A 2-Year Follow-up Study with Radiostereometric Analysis and Dual X-Ray Absorptiometry in a Stepwise Introduction.

BACKGROUND: Total hip arthroplasty (THA) with a diaphyseal stem may risk bone loss. In order to save proximal bone stock in young patients with a high activity level and a long life expectancy, the interest in short stems has evolved. The purpose of this prospective observational cohort study was to evaluate the fixation of, and bone remodeling around, the Primoris femoral neck-preserving hip implant. METHODS: Fifty younger patients with end-stage osteoarthritis were managed with the Primoris hip implant. We evaluated bone mineral density (BMD) using dual x-ray absorptiometry (DXA) and implant migration using radiostereometric analysis (RSA). A region-of-interest (ROI) protocol for 4 ROIs was applied to assess BMD. The association between BMD and migration was evaluated to determine the fixation of the Primoris implant and bone remodeling in the proximal part of the femur. Follow-up evaluation was performed at regular intervals from day 1 (baseline) until 24 months after surgery. RESULTS: The major stem migrations were subsidence (Y axis; mean, 0.38 mm) at 6 weeks and varus tilt (rotation) (Z axis; mean, 0.93°) at 6 to 12 months. In ROI4 (the calcar area), a significant gain in bone was found with a mean difference of 4.1% (95% confidence interval [CI], 0.8% to 7.4%; p < 0.02) at 24 months postoperatively. Significant bone loss was found in ROI1 and ROI2, with a mean difference of -4.9% (95% CI, -7.4% to -2.4%; p = 0.0003) and -8.9% (95% CI, -11.5% to -6.2%; p = 0.0001), respectively. Linear regression and multivariate regression analysis showed a significant negative association between maximal total point motion and BMD (p = 0.02, R = 15%; and p < 0.05, R = 26%, respectively). CONCLUSIONS: The Primoris component showed satisfactory primary stability with promising results at the 24-month follow-up. DXA scans showed limited stress-shielding with the proximal loading pattern of the Primoris. Better bone quality was associated with less implant migration. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.