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

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

Perioperative pain involves both neurogenic and inflammatory mediators. The neurogenic component is produced by the intense stimulation of the surgical procedure itself. However, inflammatory mediators resulting from tissue damage and the release of certain cytokines provoke the inflammatory response. Both the neurogenic and inflammatory elements create central nervous system (CNS) excitability. While conventional pain management responds to pain as it occurs, rather than anticipating it, a more appropriate protocol may involve pre-emptive administration of analgesic medication. By beginning this administration prior to surgery and continuing it throughout the rehabilitation process, CNS pharmacological agents are utilised to achieve the following goals: 1.) decrease the neurogenic component at the wound site; 2.) depress afferent pathways; and 3.) decrease central sensitisation in the spinal column. Our experience with such pre-emptive analgesic clinical trials have included implementation of three different protocols in three groups of patients, Groups A-C. In Group A, a continuous epidural for 72-hours was utilised. A short-term epidural for 2–3 hours, followed by the use of scheduled opioid drugs and the use of anti-inflammatory medications, was used in Group B. Finally, Group C included spinal analgesia with shortacting morphine and the continued use of patient-controlled analgesia (PCA) pumps. In all groups, patients were monitored for the return of motor function, respiratory depression, ileus, pain relief, efficacy in analgesia maintenance, and cost. The following trends were observed among the variances: 1.) approximately equal length of stay in all three groups; 2.) decreased motor function in the continuous epidural group (Group A); 3.) increased ileus in the spinal group (Group C); 4.) equal pain relief in all three groups; 5.) high maintenance in the continuous epidural group (Group A); and 6.) decreased cost when continuous epidurals (Group B) were utilised. In conclusion, of the three methodologies implemented, the continuous epidural had a high failure rate (26%). While spinal analgesia is technically easier and less expensive to perform, it has a poorly defined dose response curve and is associated with an increased incidence of ileus. The scheduled opioid medications proved effective. Pre-emptive analgesia not only significantly suppresses pain, it also provides protective sensation. Our recommendation for pre-emptive pain management consists of the use of multi-modal analgesics attacking various sites along the pain pathway, including regional blocks, oral and parental opioids, topical anaesthetics, and ice. However, ongoing study is required to further delineate appropriate protocol, thorough assessment of consequences, and complications associated with all methodologies. Future protocols to be evaluated at this practice include the local injection of bupivacaine hydrochloride prior to wound closure, in addition to assessing the postoperative integration of rofecoxib into the pain management regime

The patient with a painful arthritic knee awaiting total knee arthroplasty (TKA) requires a multidisciplinary approach. Optimal control of acute post-operative pain and the prevention of chronic persistent pain remains a challenge. The aim of this paper is to evaluate whether stratification of patients can help identify those who are at particular risk for severe acute or chronic pain. . Intense acute post-operative pain, which is itself a risk factor for chronic pain, is more common in younger, obese female patients and those suffering from central pain sensitisation. Pre-operative pain, in the knee or elsewhere in the body, predisposes to central sensitisation. Pain due to osteoarthritis of the knee may also trigger neuropathic pain and may be associated with chronic medication like opioids, leading to a state of nociceptive sensitisation called ‘opioid-induced hyperalgesia’. Finally, genetic and personality related risk factors may also put patients at a higher risk for the development of chronic pain. . Those identified as at risk for chronic pain would benefit from specific peri-operative management including reduction in opioid intake pre-operatively, the peri-operative use of antihyperalgesic drugs such as ketamine and gabapentinoids, and a close post-operative follow-up in a dedicated chronic pain clinic. Cite this article: Bone Joint J 2015;97-B(10 Suppl A):45–8

Background: Post-operative analgesia using parenteral opioids or epidural analgesia can be associated with troublesome side effects. Locally administered pre-emptive analgesia is effective, reduces central hyper sensitisation and avoids systemic drug related side-effects and may be of benefit in total knee replacement. Materials and Methods: 64 patients undergoing total knee replacement were randomised to receive a periarticular intra-operative injection containing ropivacaine, ketorolac, epimorphine and epinephrine or nothing. All patients received patient controlled analgesia (PCA) for 24 hours post surgery, followed by standard analgesia. Visual Analogue Scale (VAS) pain scores during activity and at rest and patient satisfaction scores were recorded pre and post operatively and at 6 week follow up. PCA consumption and overall analgesic requirement were measured. Results: PCA use at 6,12 and over 24 hours post surgery was significantly less in patients receiving the injection (P< 0.01, P=0.016, P< 0.01). Patient satisfaction in PACU and 4 hrs post operation was greater (P=0.016, P=0.013). VAS for pain during activity in PACU and at 4 hrs were significantly less (P= 0.04, P=0.007) in the injected group. The average ROM at 6 weeks was no different. Overall hospital stay and the incidence of wound complications was not different between the two groups. Conclusion: Peri-articular intra-operative multimodal analgesia significantly reduces post-operative PCA requirement. Patient satisfaction was greater in the injection group