Impingement syndrome in the shoulder has generally been considered to be a clinical condition of mechanical origin. However, anomalies exist between the pathology in the subacromial space and the degree of pain experienced. These may be explained by variations in the processing of nociceptive inputs between different patients. We investigated the evidence for augmented pain transmission (central sensitisation) in patients with impingement, and the relationship between pre-operative central sensitisation and the outcomes following arthroscopic subacromial decompression. We recruited 17 patients with unilateral impingement of the shoulder and 17 age- and gender-matched controls, all of whom underwent quantitative sensory testing to detect thresholds for mechanical stimuli, distinctions between sharp and blunt punctate stimuli, and heat pain. Additionally Oxford shoulder scores to assess pain and function, and PainDETECT questionnaires to identify ‘neuropathic’ and referred symptoms were completed. Patients completed these questionnaires pre-operatively and three months post-operatively. A significant proportion of patients awaiting subacromial decompression had referred pain radiating down the arm and had significant hyperalgesia to punctate stimulus of the skin compared with controls (unpaired t-test, p < 0.0001). These are felt to represent peripheral manifestations of augmented central pain processing (central sensitisation). The presence of either hyperalgesia or referred pain pre-operatively resulted in a significantly worse outcome from decompression three months after surgery (unpaired t-test, p = 0.04 and p = 0.005, respectively). These observations confirm the presence of central sensitisation in a proportion of patients with shoulder pain associated with impingement. Also, if patients had relatively high levels of central sensitisation pre-operatively, as indicated by higher levels of punctate hyperalgesia and/or referred pain, the outcome three months after subacromial decompression was significantly worse

Aims

The aim of this study was to determine if positive Waddell signs were related to patients’ demographics or to perception of their quality of life.

We suggest that different mechanisms underlie joint pain at rest and on movement in osteoarthritis and that separate assessment of these two features with a visual analogue scale (VAS) offers better information about the likely effect of a total knee replacement (TKR) on pain. The risk of persistent pain after TKR may relate to the degree of central sensitisation before surgery, which might be assessed by determining the pain threshold to an electrical stimulus created by a special tool, the Pain Matcher. Assessments were performed in 69 patients scheduled for TKR. At 18 months after operation, separate assessment of pain at rest and with movement was again carried out using a VAS in order to enable comparison of pre- and post-operative measurements. A less favourable outcome in terms of pain relief was observed for patients with a high pre-operative VAS score for pain at rest and a low pain threshold, both features which may reflect a central sensitisation mechanism

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

The majority of patients with osteoarthritis present to orthopaedic surgeons seeking relief of pain and associated restoration of function. Although our understanding of the physiology of pain has improved greatly over the last 25 years there remain a number of unexplained pain-related observations in patients with osteoarthritis. The understanding of pain in osteoarthritis, its modulation and treatment is central to orthopaedic clinical practice and in this annotation we explore some of the current concepts applicable. We also introduce the concept of the ‘phantom joint’ as a cause for persistent pain after joint replacement.

A rat model of lumbar root constriction with an additional sympathectomy in some animals was used to assess whether the sympathetic nerves influenced radicular pain. Behavioural tests were undertaken before and after the operation.

On the 28th post-operative day, both dorsal root ganglia and the spinal roots of L4 and L5 were removed, frozen and sectioned on a cryostat (8 μm to 10 μm). Immunostaining was then performed with antibodies to tyrosine hydroxylase (TH) according to the Avidin Biotin Complex method. In order to quantify the presence of sympathetic nerve fibres, we counted TH-immunoreactive fibres in the dorsal root ganglia using a light microscope equipped with a micrometer graticule (10 x 10 squares, 500 mm x 500 mm). We counted the squares of the graticule which contained TH-immunoreactive fibres for each of five randomly-selected sections of the dorsal root ganglia.

The root constriction group showed mechanical allodynia and thermal hyperalgesia. In this group, TH-immunoreactive fibres were abundant in the ipsilateral dorsal root ganglia at L5 and L4 compared with the opposite side. In the sympathectomy group, mechanical hypersensitivity was attenuated significantly.

We consider that the sympathetic nervous system plays an important role in the generation of radicular pain.

We describe 261 peripheral nerve injuries sustained in war by 100 consecutive service men and women injured in Iraq and Afghanistan. Their mean age was 26.5 years (18.1 to 42.6), the median interval between injury and first review was 4.2 months (mean 8.4 months (0.36 to 48.49)) and median follow-up was 28.4 months (mean 20.5 months (1.3 to 64.2)). The nerve lesions were predominantly focal prolonged conduction block/neurapraxia in 116 (45%), axonotmesis in 92 (35%) and neurotmesis in 53 (20%) and were evenly distributed between the upper and the lower limbs. Explosions accounted for 164 (63%): 213 (82%) nerve injuries were associated with open wounds. Two or more main nerves were injured in 70 patients. The ulnar, common peroneal and tibial nerves were most commonly injured. In 69 patients there was a vascular injury, fracture, or both at the level of the nerve lesion. Major tissue loss was present in 50 patients: amputation of at least one limb was needed in 18. A total of 36 patients continued in severe neuropathic pain.

This paper outlines the methods used in the assessment of these injuries and provides information about the depth and distribution of the nerve lesions, their associated injuries and neuropathic pain syndromes.

The outcomes of 261 nerve injuries in 100 patients were graded good in 173 cases (66%), fair in 70 (26.8%) and poor in 18 (6.9%) at the final review (median 28.4 months (1.3 to 64.2)). The initial grades for the 42 sutures and graft were 11 good, 14 fair and 17 poor. After subsequent revision repairs in seven, neurolyses in 11 and free vascularised fasciocutaneous flaps in 11, the final grades were 15 good, 18 fair and nine poor. Pain was relieved in 30 of 36 patients by nerve repair, revision of repair or neurolysis, and flaps when indicated. The difference in outcome between penetrating missile wounds and those caused by explosions was not statistically significant; in the latter group the onset of recovery from focal conduction block was delayed (mean 4.7 months (2.5 to 10.2) vs 3.8 months (0.6 to 6); p = 0.0001). A total of 42 patients (47 lower limbs) presented with an insensate foot. By final review (mean 27.4 months (20 to 36)) plantar sensation was good in 26 limbs (55%), fair in 16 (34%) and poor in five (11%). Nine patients returned to full military duties, 18 to restricted duties, 30 to sedentary work, and 43 were discharged from military service. Effective rehabilitation must be early, integrated and vigorous. The responsible surgeons must be firmly embedded in the process, at times exerting leadership.