Progressive submaximal effort hamstring muscle endurance is reduced after reconstruction of the anterior cruciate ligament.

BACKGROUND: Endurance capability in the muscles controlling the knee is poorly understood post anterior cruciate ligament (ACL) reconstruction, despite many sporting activities requiring notable muscle endurance. The hamstring muscles, when active, provide important anatomical support to protect the reconstructed graft. In the absence of good hamstring endurance, fatigue may predispose individuals to re-injury. OBJECTIVE: To assess whether ACL reconstruction (ACLR) with a hamstring graft leads to reduced hamstring endurance 9-13 months post-surgery. STUDY DESIGN: A cross-sectional inter-limb comparison study was undertaken with participants 9-13 months after an ACLR with a hamstring graft, and a group of age, sex, and activity-matched controls. There were 22 participants in each group. METHOD: Submaximal hamstring endurance was measured using a progressive fatigue test on an isokinetic dynamometer at a joint angular velocity of 120°/second. The dependant variable was the maximum number of repetitions performed. Statistical comparisons were made across injured, uninjured and control group limbs. RESULTS: There was a significant (p < 0.05) deficit in hamstring endurance observed between the injured leg (mean: 111 repetitions, SD 49) and uninjured leg (mean: 136 repetitions, SD 67) of the ACL group, but not between the uninjured and control group legs (mean: 124 repetitions, SD 50). CONCLUSION: The 18% deficit in submaximal hamstring endurance across the ACL-reconstructed individual's limbs is indicative of a notable loss in muscle performance at 9-13 months post-surgery. These results provide initial evidence for supporting further research examining the inclusion of hamstring endurance training in ACL rehabilitation programmes post-surgery.

Validity and Reliability of 3-D Ultrasound Imaging to Measure Hamstring Muscle and Tendon Volumes.

OBJECTIVE: The validity and reliability of 3-D ultrasound (US) in estimation of muscle and tendon volume was assessed in a very limited number of muscles that can be easily immersed. The objective of the present study was to assess the validity and reliability of muscle volume measurements for all hamstring muscle heads and gracilis (GR), as well as tendon volume for the semitendinosus (ST) and GR using freehand 3-D US. METHODS: Three-dimensional US acquisitions were performed for 13 participants in two distinct sessions on separate days, in addition to one session dedicated to magnetic resonance imaging (MRI). Volumes of ST, semimembranosus (SM), biceps femoris short (BFsh) and long (BFlh) heads, and GR muscles and from the tendon from semitendinosus (STtd) and gracilis (GRtd) were collected. RESULTS: The bias and the 95% confidence intervals of 3-D US compared with MRI ranged from -1.9 mL (-0.8%) to 1.2 mL (1.0%) for muscle volume and from 0.01 mL (0.2%) to -0.03 mL (-2.6%) for tendon volume. For muscle volume assessed using 3-D US, intraclass correlation coefficients (ICCs) ranged from 0.98 (GR) to 1.00, and coefficients of variation (CV) from 1.1% (SM) to 3.4% (BFsh). For tendon volume, ICCs were 0.99, and CVs between 3.2% (STtd) and 3.4% (GRtd). CONCLUSION: Three-dimensional US can provide a valid and reliable inter-day measurement of hamstrings and GR for both muscle and tendon volumes. In the future, this technique could be used as an outcome for strengthening interventions and potentially in clinical environments.

Trajectories of Pain and Function Outcomes up to 5 to 8 Years Following Total Knee Arthroplasty.

BACKGROUND: There appears to be substantial variability in outcomes > 2 years following total knee arthroplasty (TKA) that is masked by whole group analyses. The goal of the study was to identify trajectories of pain and function outcomes up to 5 to 8 years post-TKA and to identify baseline factors that are associated with different trajectories of recovery. METHODS: Baseline, 6-month, and 12-month pain and function data were collected in a previous study investigating predictors of outcome following primary TKA (n = 286), along with a variety of baseline predictor variables. The present study obtained pain and function data at 5 to 8 years following TKA in the same cohort (n = 201). Latent class linear mixed models were used to identify different classes of pain and functional trajectories over time. The extent to which differences across latent classes were explained by baseline predictor variables was determined. RESULTS: Three classes of pain and two classes of function trajectory were identified. While most patients (84% to 93%) followed a trajectory that showed an initial rapid gain following surgery that was sustained through 5 to 8 years, both pain and function included at least one trajectory class that showed a meaningful change after 12 months. No predictor variables were significantly associated with either the pain or function classes. CONCLUSIONS: Most patients follow a traditional trajectory of recovery in knee pain and function over 5 to 8 years. However, alternative trajectories are observed in an important minority of patients such that knee pain and function at 12 months after surgery does not always reflect outcomes at 5 to 8 years.

A combination of high preoperative pain and low radiological grade of arthritis is associated with a greater intensity of persistent pain 12 months after total knee arthroplasty.

AIMS: Despite new technologies for total knee arthroplasty (TKA), approximately 20% of patients are dissatisfied. A major reason for dissatisfaction and revision surgery after TKA is persistent pain. The radiological grade of osteoarthritis (OA) preoperatively has been investigated as a predictor of the outcome after TKA, with conflicting results. The aim of this study was to determine if there is a difference in the intensity of pain 12 months after TKA in relation to the preoperative radiological grade of OA alone, and the combination of the intensity of preoperative pain and radiological grade of OA. METHODS: The preoperative data of 300 patients who underwent primary TKA were collected, including clinical information (age, sex, preoperative pain), psychological variables (depression, anxiety, pain catastrophizing, anticipated pain), and quantitative sensory testing (temporal summation, pressure pain thresholds, conditioned pain modulation). The preoperative radiological severity of OA was graded according to the Kellgren-Lawrence (KL) classification. Persistent pain in the knee was recorded 12 months postoperatively. Generalized linear models explored differences in postoperative pain according to the KL grade, and combined preoperative pain and KL grade. Relative risk models explored which preoperative variables were associated with the high preoperative pain/low KL grade group. RESULTS: Pain 12 months after TKA was not associated with the preoperative KL grade alone. Significantly increased pain 12 months after TKA was found in patients with a combination of high preoperative pain and a low KL grade (p = 0.012). Patients in this group were significantly more likely to be male, younger, and have higher preoperative pain catastrophizing, higher depression, and lower anxiety (all p ≤ 0.05). CONCLUSION: Combined high preoperative pain and low radiological grade of OA, but not the radiological grade alone, was associated with a higher intensity of pain 12 months after primary TKA. This group may have a more complex cause of pain that requires additional psychological interventions in order to optimize the outcome of TKA.Cite this article: Bone Joint J 2022;104-B(11):1202-1208.

A Prospective, Median 15-Year Comparison of Ponseti Casting and Surgical Treatment of Clubfoot.

BACKGROUND: In 2010, 2 authors of this current study reported the results of Ponseti treatment compared with primary posteromedial release (PMR) for congenital talipes equinovarus in a cohort of 51 prospective patients. This current study shows outcomes recorded at a median of 15 years after the original treatment. METHODS: Patient health records were available for all 51 patients at a median of 15 years (range, 13 to 17 years) following treatment of congenital talipes equinovarus with either the Ponseti method (25 patients [38 feet]) or PMR (26 patients [42 feet]). Thirty-eight of 51 patients could be contacted, and 33 patients (65%) participated in the clinical review, comprising patient-reported outcomes, clinical examination, 3-dimensional gait analysis, and plantar pressures. RESULTS: Sixteen (42%) of 38 Ponseti-treated feet and 20 (48%) of 42 PMR-treated feet had undergone a further surgical procedure. The PMR-treated feet were more likely to undergo osteotomies and intra-articular surgical procedures (15 feet) than the Ponseti-treated feet (5 feet) (p < 0.05). Of the 33 patients reviewed with multimodal assessment, the Ponseti group, compared with the PMR group, demonstrated better Dimeglio scores (5.8 compared with 7.0 points; p < 0.05), Disease Specific Instrument (80.7 compared with 65.6 points; p < 0.05), Functional Disability Inventory (1.1 compared with 5.1; p < 0.05), and American Academy of Orthopaedic Surgeons (AAOS) Foot and Ankle Outcomes Questionnaire scores (52.2 compared with 46.6 points; p < 0.05), as well as improved total sagittal ankle range of motion in gait and ankle plantar flexion range at toe-off. The PMR group with clinical hindfoot varus displayed higher pressures in the lateral midfoot and the forefoot. CONCLUSIONS: Although the numbers of repeat surgical interventions following Ponseti treatment and primary PMR were similar, the PMR-treated feet had greater numbers of osteotomies and intra-articular surgical procedures. Functional outcomes were improved at a median of 15 years for feet treated with the Ponseti method compared with feet treated with PMR, with advantages seen in the Ponseti group over several domains. This study provides the most comprehensive evaluation of outcomes close to skeletal maturity in prospective cohorts, reinforcing the Ponseti method as the initial treatment of choice for idiopathic clubfeet. LEVEL OF EVIDENCE: Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

Experimental Hand and Knee Pain Cause Differential Effects on Corticomotor Excitability.

Acute pain elicits a well-known inhibitory effect on upper limb corticomotor excitability, whereas the temporal effects of lower-limb experimental pain and pain in a remote limb are less clear. The aim of this study was to compare the temporal corticomotor excitability changes in the upper and lower limbs in response to acute upper and lower limb pain. In a cross-over design, 13 participants (age 29 ± 9 years; 12 male) attended 2 sessions where experimental pain was induced by injecting hypertonic saline into either the first dorsal interosseous (FDI) muscle or infrapatellar fat pad at the knee, inducing a short-lasting pain experience scored on a numerical rating scale (NRS). Motor evoked potentials (MEPs) in response to transcranial magnetic stimulation were recorded in the FDI and vastus lateralis (VL) muscles before, during, and following pain. Hand and knee pain NRS scores were not significantly different. Hand pain elicited a short duration inhibition of the FDI MEPs (P < .0001) together with a facilitation of VL MEPs (P = .001) that outlasted the duration of pain. Knee pain elicited a short-duration facilitation of VL MEPs (P = .003) with no significant effect in the FDI MEPs (P = .46). The findings indicate a limb-specific corticomotor response to experimental pain that may be related to limb function. PERSPECTIVE: These data demonstrate the impact of acute, experimental pain on corticomotor excitability in the upper and lower limbs. This facilitates our understanding of the effect of pain on motor control of both local and distant muscles.

A Gel Pad Designed to Measure Muscle Volume Using Freehand 3-Dimensional Ultrasonography.

We developed an innovative gel pad that covers the entire lower leg to remove artifacts due to the pressure of the transducer in freehand 3-dimensional ultrasonography. In comparison to the reference method in water, this study showed that this new method was valid (bias, 3.4 mL; limit of agreement, 7.7 mL for a volume of ≈220 mL) and reliable (coefficient of variation, <1.1%) for the measurement of gastrocnemius medialis muscle volume. Considering that it is easier to use than the water tank technique, it has much promise for volumetric measurement of many muscles.

A Higher Grey Matter Density in the Amygdala and Midbrain Is Associated with Persistent Pain Following Total Knee Arthroplasty.

OBJECTIVE: The development of persistent pain following total knee arthroplasty (TKA) is common, but its underlying mechanisms are unknown. The goal of the study was to assess brain grey matter structure and its correlation with function of the nociceptive system in people with good and poor outcomes following TKA. SUBJECTS: Thirty-one people with LOW_PAIN (<3/10 on the numerical ratings scale [NRS]) at six months following TKA and 15 people with HIGH_PAIN (≥3/10 on the NRS) were recruited into the study. METHODS: Grey matter in key brain areas related to nociception was analyzed using voxel-based morphometry (VBM). Nociceptive facilitatory and inhibitory processes were evaluated using quantitative sensory testing (QST). QST scores and grey matter density in prespecified brain regions were compared between the LOW_PAIN and HIGH_PAIN groups. Regression analyses were used to analyze the associations between the grey matter and QST scores. RESULTS: There were no between-group differences in QST measures. In the VBM analysis, the HIGH_PAIN group had a higher grey matter density in the right amygdala, right nucleus accumbens, and in the periaqueductal grey (PAG), but lower grey matter density in the dorsal part of the left caudate nucleus. Grey matter density in the right amygdala and PAG correlated positively with temporal summation of pain. CONCLUSIONS: Persistent pain at six months after TKA is associated with a higher grey matter density in the regions involved in central sensitization and pain-related fear, which may contribute to the development of persistent pain after surgery.

Chronic effects of muscle and nerve-directed stretching on tissue mechanics.

Tissue-directed stretching interventions can preferentially load muscular or nonmuscular structures such as peripheral nerves. How these tissues adapt mechanically to long-term stretching is poorly understood. This randomized, single-blind, controlled study used ultrasonography and dynamometry to compare the effects of 12-wk nerve-directed and muscle-directed stretching programs versus control on maximal ankle dorsiflexion range of motion (ROM) and passive torque, shear wave velocity (SWV; an index of stiffness), and architecture of triceps surae and sciatic nerve. Sixty healthy adults were randomized to receive nerve-directed stretching, muscle-directed stretching, or no intervention (control). The muscle-directed protocol was designed to primarily stretch the plantar flexor muscle group, whereas the nerve-directed intervention targeted the sciatic nerve tract. Compared with the control group [mean; 95% confidence interval (CI)], muscle-directed intervention showed increased ROM (+7.3°; 95% CI: 4.1-10.5), decreased SWV of triceps surae (varied from -0.8 to -2.3 m/s across muscles), decreased passive torque (-6.8 N·m; 95% CI: -11.9 to -1.7), and greater gastrocnemius medialis fascicle length (+0.4 cm; 95% CI: 0.1-0.8). Muscle-directed intervention did not affect the SWV and size of sciatic nerve. Participants in the nerve-directed group showed a significant increase in ROM (+9.9°; 95% CI: 6.2-13.6) and a significant decrease in sciatic nerve SWV (> -1.8 m/s across nerve regions) compared with the control group. Nerve-directed intervention had no effect on the main outcomes at muscle and joint levels. These findings provide new insights into the long-term mechanical effects of stretching interventions and have relevance to clinical conditions where change in mechanical properties has occurred.NEW & NOTEWORTHY This study demonstrates that the mechanical properties of plantar flexor muscles and sciatic nerve can adapt mechanically to long-term stretching programs. Although interventions targeting muscular or nonmuscular structures are both effective at increasing maximal range of motion, the changes in tissue mechanical properties (stiffness) are specific to the structure being preferentially stretched by each program. We provide the first in vivo evidence that stiffness of peripheral nerves adapts to long-term loading stimuli using appropriate nerve-directed stretching.

Stretch reflex changes in ACL-deficient individuals and healthy controls during normal and surprise landings.

No studies in ACL-D individuals have examined neuromuscular adaptations during landing from a jump where an unexpected mechanical event changes the pre-programmed course of movement. The purpose of this study was to compare pre- and post-landing muscle activation in ACL-D individuals and uninjured controls during normal and surprise landings. Nineteen ACL-D and 17 uninjured volunteered. Participants performed repeated single leg landings from 30 and 15 cm heights. During 15 cm landings, a single surprise landing was performed where participants unexpectedly fell through a false surface at 15 cm to the solid floor a further 15 cm below. Electromyography (EMG) amplitude from vastus lateralis (VL), lateral hamstrings (LH), and soleus (Sol) was recorded. Pre-landing (-60 to 0 ms), post-landing short latency (31-60 ms), and post-landing medium latency (61-90 ms) periods were examined. Comparisons in EMG amplitudes were made across limbs (ACL-D, ACL intact, and control) in 30 cm landings. Additionally, the ratio of EMG amplitude in surprise:30 cm normal landings was analyzed. Post-landing LH EMG was reduced in the ACL-D compared to control limbs at short latencies (P < 0.05). Post-landing VL EMG was reduced in the ACL-D and ACL intact compared to the control limb at both latencies (P < 0.05). Surprise landings notably increased post-landing EMG in all muscles, across all limbs (P < 0.001). However, the gain in VL EMG was significantly greater in ACL-D and ACL intact limbs (P < 0.05). These changes in neuromuscular control of ACL-D individuals during expected and surprise landings may have important implications for rehabilitation, instability, and the risk of secondary injury.

Experimental knee pain impairs joint torque and rate of force development in isometric and isokinetic muscle activation.

PURPOSE: To investigate the effects of acute experimental knee joint pain on maximum force generation and rate of force development (RFD) of the quadriceps muscle during isometric and dynamic muscle activations. METHODS: The right knee of 20 healthy people was injected with hypertonic saline to create an acute pain experience. Measurements of maximum knee extensor torque during isometric, concentric, and eccentric contractions were undertaken using a Biodex dynamometer. The RFD was also examined during the isometric contractions. Quadriceps muscle activity was obtained using electromyography (EMG). The outcome measures were obtained at baseline, during pain, and after knee pain had resolved. RESULTS: Maximum joint torque and peak EMG were significantly reduced during pain, but there were no differences across the three types of contraction. The maximum RFD and rate of EMG rise were also reduced during pain, primarily at 50-100 ms post-contraction onset. The RFD and EMG rise were largely unaffected at later time periods following contraction onset (150-200 ms). CONCLUSIONS: Acute joint pain has a similar impact on isometric and isokinetic contractions despite differences in neural control strategies. Joint pain also impairs rapid muscle activation and the RFD. These findings are important for people with musculoskeletal pain as it likely contributes to impairments in joint function in these populations.

Effects of stroke injury on the shear modulus of the lower leg muscle during passive dorsiflexion.

Contractures are common complications of a stroke. The spatial location of the increased stiffness among plantar flexors and its variability among survivors remain unknown. This study assessed the mechanical properties of the lower leg muscles in stroke survivors during passive dorsiflexions. Stiffness was estimated through the measurement of the shear modulus. Two experiments were independently conducted, in which participants lay supine: with the knee extended ( experiment 1, n = 13 stroke survivors and n = 13 controls), or with the knee flexed at 90° ( experiment 2, n = 14 stroke survivors and n = 14 controls). The shear modulus of plantar flexors [gastrocnemius medialis (three locations), gastrocnemius lateralis (three locations), soleus (two locations), flexor digitorum longus, flexor hallucis longus), peroneus longus] and dorsiflexors (tibialis anterior and extensor digitorum longus) was measured using ultrasound shear wave elastography during passive dorsiflexions (2°/s). At the same ankle angle, stroke survivors displayed higher shear modulus than controls for gastrocnemius medialis and gastrocnemius lateralis (knee extended) and soleus (knee flexed). Very low shear modulus was found for the other muscles. The adjustment for muscle slack angle suggested that the increased shear modulus was arising from consequences of contractures. The stiffness distribution between muscles was consistent across participants with the highest shear modulus reported for the most distal regions of gastrocnemius medialis (knee extended) and soleus (knee flexed). These results provide a better appreciation of stiffness locations among plantar flexors of stroke survivors and can provide evidence for the implementation of clinical trials to evaluate targeted interventions applied on these specific muscle regions. NEW & NOTEWORTHY The shear modulus of 13 muscle regions was assessed in stroke patients using elastography. When compared with controls, shear modulus was increased in the gastrocnemius muscle (GM) when the knee was extended and in the soleus (SOL) when the knee was flexed. The distal regions of GM and SOL were the most affected. These changes were consistent in all the stroke patients, suggesting that the regions are a potential source of the increase in joint stiffness.

Orthostatic intolerance following hip arthroplasty: incidence, risk factors and effect on length of stay: A prospective cohort study.

BACKGROUND: Early postoperative mobilisation is important for enhanced recovery, but can be hindered by orthostatic intolerance, characterised by dizziness, nausea, vomiting, feeling of heat, blurred vision and ultimately syncope. Although the incidence of orthostatic intolerance following total hip arthroplasty has been identified, few studies have yet investigated potential risk factors for developing orthostatic intolerance after hip arthroplasty. OBJECTIVES: The aim of this study was to assess the incidence of orthostatic intolerance on the first postoperative day after total hip arthroplasty, potential predisposing risk factors for developing orthostatic intolerance and its effect on length of stay. DESIGN: A prospective observational study. SETTING: Tertiary hospital, Auckland, New Zealand, May to September 2015. PATIENTS: One hundred and seventeen consecutive patients undergoing unilateral total hip arthroplasty. Patients were excluded if they had revision surgery. MAIN OUTCOME MEASURES: Incidence of orthostatic intolerance during mobilisation on the first postoperative day. Significant peri-operative risk factors for developing orthostatic intolerance were identified using logistic regression. Length of stay was compared between orthostatic intolerant and orthostatic tolerant patients using the Mann-Whitney U-test. RESULTS: On the first postoperative day, 22% of patients failed mobilisation due to orthostatic intolerance. Factors independently associated with orthostatic intolerance were female sex; OR (95% CI), 3.11 (1.01 to 9.57), postoperative use of gabapentin; OR 3.55 (1.24 to 10.15) and high peak pain levels (≥5/10) during mobilisation; OR 4.05 (1.30 to 12.61). Overall, 78% of patients were correctly identified. The model was more accurate at predicting those who would not get orthostatic intolerance (89% correct), compared with those who did have orthostatic intolerance (39% correct). Length of stay was longer in patients with orthostatic intolerance (P = 0.019). CONCLUSION: Orthostatic intolerance is common after total hip arthroplasty. Optimising pain control prior to mobilisation and limiting gabapentin use may modify the risk of developing postoperative orthostatic intolerance. Although personalised recovery pathways appear attractive, at present, the ability to predict at-risk individuals is still limited.

Structural Brain Alterations Before and After Total Knee Arthroplasty: A Longitudinal Assessment.

Objective: Many studies have provided evidence of altered brain structure in chronic pain conditions, as well as further adaptations following treatment that are coincident with changes in pain. Less is known regarding how these structural brain adaptations relate to assessments of nociceptive processing. The current study aimed to investigate brain structure in people with knee osteoarthritis (OA) before and after total knee arthroplasty (TKA) and to investigate the relationships between these findings and quantitative sensory testing (QST) of the nociceptive system. Methods: Twenty-nine people with knee OA underwent magnetic resonance imaging (MRI) scans and QST before and six months after TKA and were compared with a pain-free control group (N = 18). MRI analyses involved voxel-based morphometry and fractional anisotropy. Results: Before TKA, there was reduced gray matter volume and impaired fractional anisotropy in areas associated with nociceptive processing, with further gray matter adaptations and improvements in fractional anisotropy evident after TKA. QST revealed increased nociceptive facilitation and impaired inhibition in knee OA that was reversed after TKA. There were minimal relationships found between MRI data and QST assessments or pain report. Conclusions: In people with end-stage knee OA, region-specific gray matter atrophy was detected, with further changes in gray matter volume and improvements in white matter integrity observed after joint replacement. Despite coincident alterations in nociceptive inhibition and facilitation processes, there did not appear to be any association between these functional assessments of the nociceptive system and changes in brain structure.

A Comparison of Walking Gait Following Mechanical and Kinematic Alignment in Total Knee Joint Replacement.

BACKGROUND: Although previous studies have compared radiological, pain, and function scores in kinematically aligned (KA) and mechanically aligned (MA) total knee arthroplasty (TKA), no previous studies have undertaken a three-dimensional (3D) gait analysis in these groups. This study compared kinematic and kinetic variables recorded during level walking in patients at least 2 years post-surgery who underwent an MA or KA procedure. METHODS: Utilizing a 9-camera motion analysis system, gait analysis was undertaken on 29 patients (MA = 15, KA = 14). A 9-camera motion analysis system was used to collect 3D kinematic data of the involved and uninvolved limbs during walking at a self-selected speed. Additionally, 3D ground reaction forces and moments during the stance phase were recorded, and an inverse dynamics approach was utilized to analyze these data. RESULTS: There were no significant differences in spatial-temporal variables between MA and KA groups (P > .05). Local minima and maxima for knee joint angles were not significantly different (P > .05) across involved and uninvolved legs and MA/KA groups in any of the 3 planes of motion. Principal component analysis revealed a significant difference (P < .05) in the transverse plane moment in late stance. No other significant differences were observed for knee, hip, or ankle joint moments. CONCLUSION: Differences in gait parameters across the KA and MA groups at 2 years post-surgery were insufficient to support either one of the operative procedures over the other.

Non-Muscular Structures Can Limit the Maximal Joint Range of Motion during Stretching.

Stretching is widely used in sport training and clinical practice with the aim of increasing muscle-tendon extensibility and joint range of motion. The underlying assumption is that extensibility increases as a result of increased passive tension applied to muscle-tendon units. In some stretching protocols, this condition is not always met sufficiently to trigger adaptation within the muscle-tendon unit. For example, there is experimental evidence that both acute and chronic stretching interventions may increase the maximal range of motion in the absence of changes in the passive torque-angle curve. We contend that these results are partly explained by the influence of non-muscular structures that contribute only marginally to the passive torque. The potential candidates are the nervous system and fasciae, which would play an important role in the perception of the stretch and in the limitation of the range of motion of the maximal joints. At least in part, this may explain the lack of a significant effect of some chronic stretching interventions to change passive muscle tension.

Pain Catastrophizing is Not Associated With Spinal Nociceptive Processing in People With Chronic Widespread Pain.

OBJECTIVES: Pain catastrophizing has been associated with higher pain intensity, increased risk of developing chronic pain and poorer outcomes after treatment. Despite this, the mechanisms by which pain catastrophizing influences pain remain poorly understood. It has been hypothesized that pain catastrophizing may impair descending inhibition of spinal level nociception. The aims of this study were to compare spinal nociceptive processing in people with chronic widespread pain and pain-free controls and examine potential relationships between measures of pain catastrophizing and spinal nociception. MATERIALS AND METHODS: Twenty-six patients with chronic widespread pain and 22 pain-free individuals participated in this study. Spinal nociception was measured using the nociceptive flexion reflex (NFR) threshold and NFR inhibition, measured as the change in NFR area during exposure to a second, painful conditioning stimulus (cold water immersion). Pain catastrophizing was assessed using the Pain Catastrophizing Scale and a situational pain catastrophizing scale. RESULTS: Compared with pain-free controls, patients with chronic widespread pain had higher pain catastrophizing scores and lower NFR thresholds. Although NFR area was reduced by a painful conditioning stimulus in controls, this was not apparent in individuals with chronic widespread pain. No significant correlations were observed between measures of pain catastrophizing and spinal nociception. DISCUSSION: Despite increased excitability and decreased inhibition of spinal nociception in patients with chronic widespread pain, we could find no evidence of a significant relationship between pain catastrophizing and measures of spinal nociceptive processing.

The Association Between Corticomotor Excitability and Motor Skill Learning in People With Painful Hand Arthritis.

OBJECTIVES: Previous studies have shown a tendency for reduced motor cortex inhibition in chronic pain populations. People with chronic pain also routinely demonstrate motor deficiencies, including skill learning. The goals of the current study were to (1) provide a thorough analysis of corticomotor and intracortical excitability in people with chronic arthritic hand pain, and (2) examine the relationship between these measures and performance on a motor skill learning task. METHODS: Twenty-three people with arthritic hand pain and 20 pain-free controls participated in a cross-sectional study. Transcranial magnetic stimulation was used to assess corticomotor and intracortical excitability of the first dorsal interosseus muscle. Participants then completed a 30-minute motor skill training task involving the index finger of the same hand. RESULTS: Hand arthritis participants showed evidence of reduced intracortical inhibition and enhanced facilitation, which correlated with duration of hand pain. Arthritis participants were initially poorer at the motor skill task but over the total training time performance was equivalent between groups. There were no associations found between measures of intracortical excitability and motor skill learning. DISCUSSION: Our findings are the first to provide evidence of cortical disinhibition in people with painful arthritis, as previously demonstrated in other chronic pain populations. Cortical excitability changes may progress the longer pain persists, with increased pain duration being associated with greater cortical disinhibition. There was no evidence that these changes in cortical excitability are related to impaired motor function or skill learning.

Diagnostic Accuracy of Clinical Examination and Imaging Findings for Identifying Subacromial Pain.

BACKGROUND: The diagnosis of subacromial pathology is limited by the poor accuracy of clinical tests for specific pathologies. The aim of this study was to estimate the diagnostic accuracy of clinical examination and imaging features for identifying subacromial pain (SAP) defined by a positive response to diagnostic injection, and to evaluate the influence of imaging findings on the clinical diagnosis of SAP. METHODS AND FINDINGS: In a prospective, diagnostic accuracy design, 208 consecutive patients presenting to their primary healthcare practitioner for the first time with a new episode of shoulder pain were recruited. All participants underwent a standardized clinical examination, shoulder x-ray series and diagnostic ultrasound scan. Results were compared with the response to a diagnostic block of xylocaineTM injected into the SAB under ultrasound guidance using ≥80% post-injection reduction in pain intensity as the positive anaesthetic response (PAR) criterion. Diagnostic accuracy statistics were calculated for combinations of clinical and imaging variables demonstrating the highest likelihood of a PAR. A PAR was reported by 34% of participants. In participants with no loss of passive external rotation, combinations of three clinical variables (anterior shoulder pain, strain injury, absence of symptoms at end-range external rotation (in abduction)) demonstrated 100% specificity for a PAR when all three were positive (LR+ infinity; 95%CI 2.9, infinity). A full-thickness supraspinatus tear on ultrasound increased the likelihood of a PAR irrespective of age (specificity 98% (95%CI 94, 100); LR+ 6.2; 95% CI 1.5, 25.7)). Imaging did not improve the ability to rule-out a PAR. CONCLUSION: Combinations of clinical examination findings and a full-thickness supraspinatus tear on ultrasound scan can help confirm, but not exclude, the presence of subacromial pain. Other imaging findings were of limited value for diagnosing SAP.