Purpose of study and background. Psychological factors are considered to play a role in development and maintenance of chronic low back pain (CLBP). Stress or anxiety can change pain sensitivity; however, this has predominantly been studied in healthy individuals with limited work in individuals with musculoskeletal pain. The objective of this study was to quantify the effect of acute exposure to a psychosocial stressor on mechanical pain sensitivity in individuals with and without CLBP. Summary of methods and results. Six individuals with CLBP and 10 individuals without CLBP performed a 10-minute computer task under conditions of low and high psychosocial stress. Psychosocial stress was manipulated using mental maths and memory tasks combined with social evaluative threat. The effect of the stressor was evaluated using blood pressure, heart rate and the state anxiety component of the Spielberger State-Trait Anxiety Index. Mechanical pressure pain threshold (PPT) was recorded on the tibialis anterior muscle using a handheld digital pressure algometer. The stress manipulation increased self-reported anxiety (p<0.001), but not blood pressure or heart rate (p>0.06). Change in PPT from low to high stress was greater in the CLBP group (median ΔPPT = −0.5 kg/cm. 2. ) than in the control group (−0.15 kg/cm. 2. ; p=0.005). Conclusion. Individuals experienced an increase in pain sensitivity after acute exposure to a stressor designed to mimic low-level workplace stressors, and this increase was greater in individuals with CLBP than asymptomatic individuals. These results indicate that this experimental model can be used to study links between pain sensitivity and psychosocial stressors and increase our understanding of their potential role in CLBP. Conflicts of Interest: No conflicts of interest. Sources of funding: No funding obtained

Introduction: Algometry has been shown to be an effective way of quantifying pressure pain threshold (PPT), although it’s reliability in assessing spinal muscle pain (excluding trigger points) has not been robustly analysed. Method: Intra-rater test re-test reliability PPT assessment by algometry over the belly of four pairs of spinal muscles, (iliocostalis, multifidus, gluteus maximus and trapezius) in a healthy sample (80 assessments) was analysed. Healthy subjects were tested twice (within 15mins) on three occasions (separated by a week); 240 sets of assessments revealed good within-session reliability (ICC> .91) and good between session reliability (ICC> .87), with a relatively small measurement error (approximately 3kg/cm. 2. ) and no systematic difference within session or between sessions. Conclusion: In conclusion, PPT assessment by algometry is a reliable, both within and between sessions, measure of a subject’s pain. This study provides further validity to the use of this measure as a suitable, convenient method of monitoring treatment effects

Aims. The involvement of cyclin D1 in the proliferation of microglia, and the generation and maintenance of bone cancer pain (BCP), have not yet been clarified. We investigated the expression of microglia and cyclin D1, and the influences of cyclin D1 on pain threshold. Methods. Female Sprague Dawley (SD) rats were used to establish a rat model of BCP, and the messenger RNA (mRNA) and protein expression of ionized calcium binding adaptor molecule 1 (IBA1) and cyclin D1 were detected by reverse transcription-polymerase chain reaction (RT-PCR) and western blot, respectively. The proliferation of spinal microglia was detected by immunohistochemistry. The pain behaviour test was assessed by quantification of spontaneous flinches, limb use, and guarding during forced ambulation, mechanical paw withdrawal threshold, and thermal paw withdrawal latency. Results. IBA1 and cyclin D1 in the ipsilateral spinal horn increased in a time-dependent fashion. Spinal microglia proliferated in BCP rats. The microglia inhibitor minocycline attenuated the pain behaviour in BCP rats. The cyclin-dependent kinase inhibitor flavopiridol inhibited the proliferation of spinal microglia, and was associated with an improvement in pain behaviour in BCP rats. Conclusion. Our results revealed that the inhibition of spinal microglial proliferation was associated with a decrease in pain behaviour in a rat model of BCP. Cyclin D1 acts as a key regulator of the proliferation of spinal microglia in a rat model of BCP. Disruption of cyclin D1, the restriction-point control of cell cycle, inhibited the proliferation of microglia and attenuated the pain behaviours in BCP rats. Cyclin D1 and the proliferation of spinal microglia may be potential targets for the clinical treatment of BCP. Cite this article: Bone Joint Res 2022;11(11):803–813

Previously, we reported impaired biomechanical bone properties and inferior bone matrix quality in tachykinin1 (Tac1)-deficient mice lacking the sensory neuropeptide substance P (SP). Additionally, fracture callus development is affected by the absence of SP indicating a critical effect of sensory nerve fibers on bone health and regeneration. For α-calcitonin gene-related peptide (α-CGRP)-deficient mice, a profound distortion of bone microarchitecture has also been described. We hypothesize that SP and α-CGRP modulate inflammatory as well as pain-related processes and positively affect bone regeneration during impaired fracture healing under osteoporotic conditions. Therefore, this study investigates the effects of SP and α-CGRP on fracture healing and fracture-related pain processes under conditions of experimental osteoporosis using SP- and α-CGRP-deficient mice and WT controls. We ovariectomized female WT, Tac1−/− and α-CGRP−/− mice (age 10 weeks, all strains on C57Bl/6J background) and set intramedullary fixed femoral fractures in the left femora 28 days later. We analyzed pain threshold (Dynamic Plantar Aesthesiometer Test) and locomotion (recorded at day and night, each for 1 hour, EthoVision®XT, Noldus) at 5, 9, 13, 16 and 21 days after fracture. At each time point, fractured femora were prepared for histochemical analysis of callus tissue composition (alcian blue/sirius red staining). Pain threshold is significantly higher in Tac1−/− mice 13 days after fracture and tends to be higher after 21 days compared to WT controls. In contrast, touch sensibility was similar in α-CGRP−/− mice and WT controls but compared to Tac1−/− mice pain threshold was significantly lower in α-CGRP−/− mice 13 and 16 days and tends to be lower 21 days after fracture. Locomotion of Tac1−/− mice during daylight was by trend higher 9 days after fracture and significantly higher 16 days after fracture whereas nightly locomotion is reduced compared to WT mice. Analysis of locomotion during daylight or night revealed no differences between α-CGRP−/− and WT mice. During early fracture healing phase, 5 and 9 days after fracture, transition of mesenchymal to cartilaginous callus tissue tends to be faster in Tac1−/− mice compared to WT controls whereas no difference was observed during late stage of fracture healing, 13, 16 and 21 days after fracture. In contrast, callus tissue maturation seems to be similar in α-CGRP−/− and WT mice. Our data indicate different effects of SP and α-CGRP on fracture healing under conditions of experimental osteoporosis as a model for impaired bone tissue. Lack of α-CGRP seems to have no effects, but loss of SP affects locomotion throughout osteoporotic fracture healing and fracture-related pain processes during late phases of osteoporotic fracture healing. This indicates a modified role of SP during fracture healing under impaired versus healthy conditions, where SP changed early fracture-related pain processes and had no influence on callus tissue composition

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

Introduction: Sensory hypersensitivity, central hyper-excitability (lowered nociceptive flexion reflex (NFR) thresholds) and psychological distress are features of chronic whiplash. Relationships between these substrates are not clear. The aim of this study was to investigate relationships between psychological factors (distress, catastrophization) and pain threshold responses to sensory stimuli and spinal cord excitability as assessed by the NFR. The former assessments are considered as global pain responses to sensory stimuli as reported by the patient, whereas the latter, an objective measurement for spinal cord excitability to peripheral stimulation. Methods: 30 individuals with chronic (> 3 months) whiplash (Grade II or III; Grade IV were excluded) and 30 asymptomatic controls participated. Pressure pain thresholds (PPTs) and thermal pain thresholds (Thermotest, Somedic AB, Sweden) were measured at the cervical spine, upper and lower limbs. The NFR (intensity of electrical stimulation at the sural nerve required to elicit reflex EMG activity of biceps femoris) was measured as per previous protocols (1). Pain and disability levels (NDI), psychological distress (GHQ-28) and catastrophisation (PCS) were also measured in the whiplash group. Ethical clearance for this study was granted by the Medical Research Ethics Committee of the University of Qld. A MANCOVA was used to determine differences between the whiplash group and controls for sensory measures and the NFR. GHQ-28 and PCS scores were used as covariates in the analysis. Group differences for questionnaire data (GHQ-28 and PCS) were analysed using one way ANOVA. Pearson’s correlation coefficients were used to determine the relationship between the psychological measures (PCS and GHQ-28), pain and disability levels (NDI) and the pain threshold measures (mechanical and thermal) and to determine relationships between the psychological measures, pain and disability measures (NDI) and NFR responses (pain intensity at threshold, threshold). p< 0.05. Results: Whiplash injured participants (23 females, mean (SD) age: 37.7 (11.5) years, NDI: 46.2 (17.6) and VAS scores of pain: 4.2 (2.4)) demonstrated lowered pain thresholds to pressure and cold (p< 0.05); lowered NFR thresholds (p=0.003) and above threshold levels of psychological distress (GHQ-28) compared to controls and levels of catastrophisation comparable to other musculoskeletal conditions. There were no group differences for heat pain thresholds or pain at NFR threshold. In the whiplash group, PCS scores correlated moderately with cold pain threshold (r =0.51, p=0.01). In contrast there were no significant correlations between GHQ-28 scores and pain threshold measures or between psychological factors and NFR responses in whiplash participants. There were no significant correlations between psychological factors and pain thresholds or NFR responses in controls. Discussion: We have demonstrated that psychological factors have some association with sensory hypersensitivity (cold pain threshold measures) in chronic whiplash but do not seem to influence spinal cord excitability. This suggests that psychological disorders are important, but not the only, determinants of central hypersensitivity in whiplash patients. These findings suggest that both physical and psychological factors will need to be addressed in the management of whiplash

Introduction: Long-term treatment of chronic muscu-loskeletal pain with opioids often causes a cluster of unpleasant side effects such as constipation, dizziness and cognitive impairment and is likely to lead to tolerance and to hyperalgesia, which is clinically important but not yet well researched. In this study we investigated the development of hyperalgesia after long-term treatment with opioids in patients with chronic low back pain (cLBP). The goal of this prospective longitudinal study was to investigate the long-term (> 1.5 years) effects of opioid analgetics on thermal sensation and pain thresholds and to follow the changes in pain sensitivity for 6 months during opioid withdrawal. Methods: Using quantitative sensory testing (QST), we compared thermal sensation and pain thresholds on the palm of the hand and the low back bilaterally among three groups: patients with cLBP and long-term treatment with opioids (group 1, n=35); opioid-naive patients with chronic low back pain (group 2, n=34) and subjects with neither pain nor opioid intake (group 3, n=27). The effects of age, sex, pain duration, duration and dose of opioid intake, comorbidity (depression) and self-reported pain intensity assessed by QST were investigated. All patients were allocated to a 3-week multidisciplinary functional restoration programme that emphasized biopsychosocial factors and included continuous tapering of opioid dose. During the study all patients kept records of the medication they used. Results: Group 1 patients showed significantly delayed reaction to cold and warm stimuli on the back, compared with both group 2 and group 3. Pain thresholds for cold and heat on the hand were similar in group 1 and 2 but significantly reduced in these groups compared with group 3. Age, sex, pain duration, duration and dose of opioid intake, and self-reported pain intensity, but not depression, correlated significantly with QST results. Discussion: The present study demonstrated that long-term opioid use significantly delayed thermal QST responses but had no measureable analgesic effects in patients with chronic low back pain. While the pain thresholds in groups 1 and 2 did not differ before opioid withdrawal, both groups 1 and 2 were more sensitive to pain than group 3 (healthy controls). This finding confirms that chronic low back pain itself might cause increased pain sensitivity, which seems not to be counteracted by opioid medication. Rather, treatment in the multidisciplinary pain therapy programme had positive effects on pain thresholds in opioid-naive patients but not in patients after opioid withdrawal. The opioid-naive patients of group 2 showed normalized pain thresholds 6 months after therapy, while the former opioid-positive patients of group 1 still had significantly decreased pain thresholds despite 6 months’ abstinence

Introduction: Although the primary aim of Total Knee Replacement (TKR) is to relieve chronic joint pain, 10–20% of patients experience unexplained chronic pain after surgery. One possible cause of this pain is central sensitisation. Prolonged exposure to a noxious input can lead the central nervous system to become sensitised to pain (central sensitisation), which can become self-sustaining and persist after the removal of the noxious stimuli i.e after TKR. The aim of this study was to determine if knee osteoarthritis (OA) patients awaiting TKR have evidence of sensory perception abnormalities, by comparing detection and pain thresholds from OA patients to those of age- and gender-matched healthy participants. Patients and Methods: Quantitative Sensory Testing (QST) was performed on 107 knee OA patients on the waiting list for primary TKR and 50 age- and gender-matched healthy participants without knee pain or TKR. QST assesses somatosensory function through measuring participant responses to external stimuli of controlled intensity. QST was performed on both knees and the pain-free forearm of all participants. Von Frey filaments were used to measure touch detection thresholds, a digital Algometer to measure pressure pain thresholds, and the MSA Thermotest to measure detection and pain thresholds to hot and cold. Significant differences in the median threshold values between knee OA patients and healthy participants were tested for using Mann-Whitney U tests. Results: Detection thresholds: OA patients had significantly higher detection thresholds for hot and cold (both p< 0.05) in the index knee (but not at other sites) compared to healthy participants. Touch detection thresholds were significantly higher at all body sites in OA patients compared to healthy participants (all p< 0.001). Pain thresholds: Pressure pain thresholds were significantly lower in OA patients at all body sites (all p< 0.001) but there were no significant differences in hot or cold pain thresholds between OA patients and healthy participants at any body site (all p> 0.05). Discussion: This study showed that knee OA patients have modality-specific sensory and pain perception abnormalities. These included thermal hypoesthesia (reduced sensitivity) in the index knee and tactile hypoesthesia at all body sites tested, alongside hyperalgesia (increased pain sensitivity) to pressure pain at all body sites. Future research aims to determine if these sensory perception abnormalities are predictive of chronic pain after TKR

Introduction: Lumbar mobilisations are commonly used in clinical practise to reduce pain and increase function. Mobilisations to the cervical spine have been shown to reduce pain using pressure pain thresholds (PPT). Yet there is no evidence to confirm that this happens in the lumbar spine. Furthermore there is little known about the effects of different treatment doses on the amount of hypoalgesia produced. It is unknown if changing the rate of application of mobilisations has an effect on hypoalgesia. The aim of this study was to investigate the immediate effects of lumbar posteroanterior mobilisations performed at different rates on PPT. Pressure pain thresholds were measured in a number of locations in order to assess the extent of the analgesic response. Method and Results: A repeated measures single blind, randomised-trial was conducted on 30 asymptomatic subjects (22 female and 8 males). Pressure pain thresholds were measured at 4 sites in the upper and lower quadrants, before and after the application of lumbar spine posteroanterior mobilisations performed at 2Hz, 1Hz and quasi-static. The results demonstrated an immediate and significant improvement in PPT measures (P< 0.000) irrespective of the rate or site tested. The effects were both local and widespread. There was no significant difference between the rates of mobilisations on PPT. Conclusion: This study provides new experimental evidence that lumbar spine posteroanterior mobilisations produce an immediate and significant widespread hypoalgesic effect, regardless of the rate of mobilisation. Further research is now needed to investigate the effect on a patient population with low back pain

The type, duration and intensity of exercise required to induce mechanical hypoalgesia is poorly defined. We are interested in identifying the exercise parameters required to induce raised pressure pain thresholds. This pilot study investigates the effect of indoor rowing on pressure pain threshold (PPT) in high performance rowers. Our ultimate aim is to investigate the potential of utilising exercise in the treatment of chronic pain and specifically in relation to the management of knee osteoarthritis. 20 high performance rowers (13M:7F; Mean Age 20.8 years; SD 1.74) were recruited from the University of Nottingham and Nottingham Boat Club high performance rowing teams under a research protocol approved by the University of Nottingham Ethics Committee. PPT measurements were made in triplicate using an algometer (SOMEDIC, Sweden) at the medial knee joint line, anterior tibia and sternum, pre- and post-exercise. Anthropomorphic and rowing ergometer power output data were also recorded. There was significant increase in PPT values at all sites following exercise (Medial joint line: 127.6Nm-2, 26%, p=0.001; Tibia: 110.8Nm-2, 24.7%, p<0.001; Sternum: 48.9Nm-2, 11.7%, p=0.005 – Wilcoxon Signed Rank) statistical power was 97.1%, 100% and 88.1%, respectively. PPT was greater at baseline at the medial joint line compared to other sites, reaching highly significant relative to the sternum (p<0.001). We determined that ten minutes of high intensity indoor rowing induced hypoalgesia in high performance rowers. Further research is required to investigate the detailed interplay between exercise and hypoalgesia, including its duration post exercise, to identify suitability for use in pain management strategies

INTRODUCTION. This study describes the prevalence of pain, functional loss and rotator cuff tears (RCTs) in a general population cohort. It is the first multidisciplinary assessment in such a cohort. METHODS. The Chingford cohort is a 19-year old longitudinal population study comprising 1003 women aged between 44 and 67 at baseline. To date 183 consecutive subjects (366) shoulders have been interviewed about their shoulders. Myometric strength assessment and high-definition ultrasound examination (US) have been performed on all shoulders. Additionally pain thresholds and perceptions of pain have been tested using quantitative sensory testing (QST) and a number of validated questionnaires, including the illness attitudes scale and the pain detect score. RESULTS. The population prevalence of at least one full-thickness RCT was 24%, with 19% being unilateral and 5% bilateral. Of the 366 shoulders: 56% had no tendon abnormality on ultrasound: Of which, 68% were asymptomatic, 23% had pain, and 24% had functional loss. 20% had abnormalities of the tendon-bone attachment: Of which, 56% were asymptomatic, 35.6% had pain and 36.1% had functional loss. 9% had a partial-thickness RCT: Of which, 53% were asymptomatic, 29% had pain and 38% had functional loss. 7% had a full-thickness RCT (less than 2cm): Of which, 58% were asymptomatic, 29% had pain and 29% had loss of function. 8% had a full-thickness RCT (greater than 2cm): Of which, 38% were asymptomatic, 55% had pain and 48% had functional loss. The pain and functional loss was significantly greater in the abnormal tendon-bone attachment group, and the full-thickness RCT (greater than 2cm) group, compared to those with no abnormality on high-definition ultrasound examination. Strength testing showed progressive weakness through all disease stages. Pain thresholds from the QST data will be presented. DISCUSSION. In a unique normal population-cohort study 44% of patients were found to have some form of degenerative tendon abnormality on high-definition ultrasound. Of these significant pain and/or loss of function was found in 48% of shoulders. High-definition US has allowed us to identify a group of tendons with an abnormality at the tendon bone interface. The pain and functional loss increases at this early stage and then only further increases once a tear is greater than 2cm. However over 50% remain asymptomatic

Purpose: We wanted to ascertain whether the advantages of functional treatment on trophicity could be combined with the advantages of surgical treatment on anatomic results in patients with displaced calcaneal join fractures. Material and methods: Using the AO 3.5 reconstruction plates with specific stereotypic modelling we were able to obtain solid fixation in almost all cases of calcaneal joint fractures using a rigorous technique and following precise principles, notably the direction of the screw into the sustentaculum tali.As the osteosynthesis is very stable, we postulate that partial and progressive early weight bearing would be acceptable as long as pain was under a threshold level used as sign of micromobility. The first cases were very favourable so we extended this method, using it as a routine procedure for all cases (excepting those with an associated injury excluding weight bearing). Among 122 fractures operated with this method, 118 were reviewed. Results: According to the Duparc classification, we treated one type 2, 34 type 3, 76 type 4 and seven type 5 fractures. Weight bearing was initiated on the average at 14 days, with a median of seven days. The Boehler angle improved from 0° preoperatively to 22° postoperatively. We did not have any cases of secondary displacement greater than 2°. The functional outcome was, according to the SOFCOT criteria: very good 34.5%, good 41.4%, fair 9.5% and poor 0%. Physical results (SOFCOT criteria) were: very good 17.2%, good 54.3%, fair 26.7%, poor 1.7%. Anatomic results according to AFC criteria were: very good and good 69%, fair 25.9%, poor 5.1%. Discussion: These result demonstrate that a rigorous therapeutic management scheme can combine the advantages of functional and surgical treatment of displaced calcaneal joint fractures. Early weight-bearing below the pain threshold was effective since all our bilateral cases could be discharged after walking a few steps. Recovery was more rapid when weight bearing was late. Crutches could be abandoned at two months on the average. Conclusion: We believe that solid osteosynthesis is possible in almost all cases of displaced calcaneal fractures with joint involvement if a rigorous technique is used. Progressive early weight bearing below the pain threshold is a significant adjuvant factor favouring rapid and quality outcome

Background. Chronic pain after joint replacement is common, affecting approximately 10% of patients after total hip replacement (THR) and 20% of patients after total knee replacement (TKR). Heightened generalised sensitivity to nociceptive input could be a risk factor for the development of this pain. The primary aim of this study was to investigate whether preoperative widespread pain sensitivity was associated with chronic pain after joint replacement. Methods. Data were analysed from 254 patients receiving THR and 239 patients receiving. TKR. Pain was assessed preoperatively and at 12 months after surgery using the Western Ontario and McMaster Universities Osteoarthritis Pain Scale. Preoperative widespread pain sensitivity was assessed through measurement of pressure pain thresholds (PPTs) at the forearm using an algometer. Statistical analysis was conducted using linear regression and linear mixed models, and adjustments were made for confounding variables. Results. In both the THR and TKR cohort, lower PPTs (heightened widespread pain. sensitivity) were significantly associated with higher preoperative pain severity. Lower PPTs were also significantly associated with higher pain severity at 12 months after surgery in the THR cohort. However, PPTs were not associated with the change in pain severity from preoperative to 12 months postoperative in either the TKR or THR cohort. Conclusions. These findings suggest that although preoperative widespread pressure pain sensitivity is associated with pain severity before and after joint replacement, it is not a predictor of the amount of pain relief that patients gain from joint replacement surgery, independent of preoperative pain severity. Level of Evidence. 2. Approvals. The APEX trials were registered as an International Standardised Randomised Controlled Trial (96095682), approved by Southampton and South West Hampshire Research Ethics Committee(09/H0504/94) and all participants provided informed written consent

Background. To investigate whether the interaction between pre-operative widespread hyperalgesia and radiographic osteoarthritis (OA) was associated with pain severity before and after total hip replacement (THR) and total knee replacement (TKR). Methods. Data were analysed from 232 patients receiving THR and 241 receiving TKR. Pain was assessed pre-operatively and at 12 months post-operatively using the WOMAC Pain Scale. Widespread hyperalgesia was assessed through forearm pressure pain thresholds (PPTs) measured using an algometer. The severity of radiographic OA was evaluated using the Kellgren and Lawrence scheme. Statistical analysis was conducted using linear regression and multilevel models, and adjusted for confounding variables. Results. Pre-operative. In knee patients, there was weak evidence that the effect of PPTs on pain severity was greater in patients with more severe OA compared to patients with less severe OA (Grade 3 OA: ß=0.96 vs Grade 4 OA: ß=4.03). However, in hip patients, the effect of PPTs on pain severity did not differ with the extent of radiographic OA (Grade 3 OA: ß=3.95 vs Grade 4 OA: ß=3.67). Post-operative. Patients undergoing TKR with less severe OA who had lower PPTs (greater widespread hyperalgesia) benefitted less from surgery than patients with higher PPTs (Grade 3 OA: ß=2.28). Conversely, patients undergoing THR with more severe OA who had lower PPTs benefited more from surgery than patients with higher PPTs (Grade 4 OA: ß=−2.92). Conclusion. Central sensitisation may be a determinant of how much patients benefit from joint replacement, but the effect varies by joint and severity of structural joint changes. Level of Evidence. 2. Approvals. The APEX trials were registered as an International Standardised Randomised Controlled Trial (96095682), approved by Southampton and South West Hampshire Research Ethics Committee (09/H0504/94) and all participants provided informed written consent

Aims

In-hospital length of stay (LOS) and discharge dispositions following arthroplasty could act as surrogate measures for improvement in patient pathways, and have major cost saving implications for healthcare providers. With the ever-growing adoption of robotic technology in arthroplasty, it is imperative to evaluate its impact on LOS. The objectives of this study were to compare LOS and discharge dispositions following robotic arm-assisted total knee arthroplasty (RO TKA) and unicompartmental arthroplasty (RO UKA) versus conventional technique (CO TKA and UKA).

Aims

The aim of this study was to determine the effectiveness of home-based prehabilitation on pre- and postoperative outcomes in participants awaiting total knee (TKA) and hip arthroplasty (THA).

Purposes of the study and background. An increasing number of clinical studies involving a range of chronic pain conditions report widespread mechanical pressure pain hypersensitivity, which is commonly interpreted as resulting from central sensitization (CS). Secondary hyperalgesia (increased pinprick sensitivity surrounding the site of injury) is considered to be a manifestation of central sensitization. However, it has not been rigorously tested whether central sensitization induced by peripheral nociceptive input, involves widespread mechanical pressure pain hypersensitivity. The aim of this study was to assess whether high frequency electrical stimulation (HFS), which induces a robust secondary hyperalgesia, also induces a widespread decrease of pain pressure thresholds (PPTs). Summary of the methods and results. We measured PPTs bilaterally on the temples (temporalis muscles), on the legs (tibialis anterior muscles) and on the ventral forearm (flexor carpi radialis muscles) before, 20 min after, and 45 min after applying HFS on the ventral forearm of sixteen healthy young volunteers. To evaluate the presence of secondary hyperalgesia, mechanical pin-prick sensitivity was assessed on the skin surrounding the site where HFS was applied and also on the contralateral arm. HFS induced a significant increase in mechanical pinprick sensitivity on the HFS-treated arm. However, HFS did not decrease PPTs either in the area of increased pinprick sensitivity nor at more distant sites. Conclusion. The present study provides no evidence for the hypothesis that central sensitization, induced after intense activation of skin nociceptors, involves a widespread decrease of PPTs. No conflicts of interest. Sources of Funding: This study was funded by the Université Catholique de Louvain

Introduction. Regular, repeated stretching increases joint range of movement (RoM), however the physiology underlying this is not well understood. The traditional view is that increased flexibility after stretching is due to an increase in muscle length or stiffness whereas recent research suggests that increased flexibility is due to modification of tolerance to stretching discomfort/pain. If the pain tolerance theory is correct the same degree of micro-damage to muscle fibres should be demonstrable at the end of RoM before and after a period of stretch training. We hypothesise that increased RoM following a 3 weeks hamstrings static stretching exercise programme may partly be due to adaptive changes in the muscle/tendon tissue. Materials and Methods. Knee angle and torque were recorded in healthy male subjects (n=18) during a maximum knee extension to sensation of pain. Muscle soreness (pain, creatine kinase activity, isometric active torque, RoM) was assessed before knee extension, and 24 and 48 hours after maximum stretch. An exercise group (n=10) was given a daily home hamstring stretching programme and reassessed after 3 weeks and compared to a control group (n=8). At reassessment each subject's hamstring muscles were stretched to the same maximum knee extension joint angle as determined on the first testing occasion. After 24 hours, a reassessment of maximum knee extension angle was made. Results. At the start of the study RoM was 71.3 ± 10.0 degrees and there was no significant difference between groups. After 3 weeks stretching RoM increased significantly (p=0.01) by 9 degrees; the control group showed no change. Stiffness did not differ for either group. Pain score and RoM were the most sensitive markers of muscle damage and were significantly changed 24 and 48 hours after the initial stretch to end of range, (p<0.005) and (p=0.004) respectively. Discussion. The results show that a 3 week stretching programme causes muscle adaptation resulting in an increase in the extensibility of the hamstring muscle/tendon unit but no change in stiffness. The lack of evidence of muscle damage suggests that participants in the stretching group are likely to have undergone a physical change/adaptation rather than simply an increase in pain threshold

Background. Evidence supports that dysfunction of descending inhibition (endogenous analgesic (EA) modulation) contributes towards chronic pain conditions. Research suggests that manual therapy may influence EA modulation; however, this is poorly understood. Trials testing the effect of sustained digital pressure, a commonly used manual therapy technique, using pain pressure threshold (PPT) would give us a better understanding of the influence of manual therapy on EA modulation. A measurement of PPT has been shown to be most effective using fingertip pressure due to the palpatory feedback of symptomatic tissues. Design. A cross-sectional observational study, utilizing a repeated measure approach. Aim. The aim of this research study is to provide preliminary data on the variability of pressure in sustained fingertip pressure in comparison to algometer guided pressure. Methods. Utilizing a pressure algometer, 26 participants were used to test the variability of fingertip pressure in comparison to algometer guided pressure, over 120 seconds. In a randomized order and utilizing two sheets of skin, participants tried to attain, and sustain, a targeted pressure. In the fingertip pressure condition, participants were blinded to the exerted pressure. Conclusion. It was determined that, on average, participants were able to attain the target pressure, but this was highly variable from trial to trial. The test-retest measurement concluded that participants' accuracy was reproducible. Participants were not reproducible in variability when completing the test-retest measurement. There was a relatively higher variability with the lower pressures tested. The order in which the trial was performed, and type of skin did not affect the variability. It was concluded that, whilst some practitioners appear to have a high degree of accuracy with low variability of sustained finger-tip pressure, across a sample population this was not the case bringing into question the mechanism of effect of this common manual therapy technique. Conflict of interest: None. Funding: None

To consider bilateral simultaneous knee replacement, both knees must have significant structural damage. It is best if the patient can't decide which knee is more bothersome. In borderline cases, ask the patient to pretend that the worse knee is normal and if so, would they be seeing you for consideration of knee replacement on the less involved side. If the answer to this question is “yes,” consider the patient a potential candidate for bilateral knee replacement. If the answer is “no,” recommend operating only on the worse knee, and expect that the operation on the second knee can probably be delayed for a considerable period of time. Strong indications for bilateral simultaneous TKA are bilateral severe angular deformity, bilateral severe flexion contracture, and anesthesia difficulties, i.e., patients who are anatomically or medically difficult to anesthetise, such as some adult or juvenile rheumatoid arthritis patients or patients with severe ankylosing spondylitis. Relative indications for bilateral simultaneous TKA include the need for multiple additional surgical procedures to achieve satisfactory function and financial or social considerations for the patient. Contraindications to bilateral TKA include medical infirmity (especially cardiac), a reluctant patient, and a patient with a very low pain threshold. When performing bilateral simultaneous TKA, both limbs are prepped and draped at the same time. An initial dose of an intravenous antibiotic is given (usually 1g of a cephalosporin) before inflation of the tourniquet. Surgery begins on the more symptomatic side or on either side if neither knee is significantly worse than the other. The reason for starting on the more symptomatic side is in case surgery has to be discontinued after only one procedure owing to anesthetic considerations. After the components have been implanted on the first side, the tourniquet is deflated and a second dose of intravenous antibiotic is administered (usually 500mg of a cephalosporin). After the joint capsule is closed and flexion against gravity is measured, one team completes the subcutaneous and skin closure on the first side while the other team inflates the second tourniquet and begins the exposure of the second side. When the second tourniquet is deflated, a third dose of antibiotic is given (usually 500mg of a cephalosporin for a total dose of 2g for both knees). Because of concern about the potential for cross-contamination of the knee wounds when instruments used during the final stages of skin closure on the first knee are maintained on the field and used on the second knee, they should probably be handed off the field and outer surgical gloves changed. Most patients will report after their complete recovery that they are glad they did both knees at the same time. A patient who has any uncertainty about proceeding with bilateral surgery should have only one knee done at a time. In many cases, the second side receives a “reprieve,” becoming more tolerable after the first side has been operated on