# Background Achilles tendinopathy is a common overuse condition that can become persistent despite conservative treatment. Sensitization of both the peripheral and central nervous systems may contribute to the persistent pain. Both exercise and electrical stimulation have the potential to modulate the nervous system’s sensitivity to painful stimuli. # Hypothesis/Purpose The purpose of this study was to describe the changes in pain sensitivity and self-reported function in runners with chronic Achilles tendon pain following sequential treatment with noxious electrical stimulation (NxES) and eccentric plantarflexion exercise. # Study Design Single group, repeated measures design. # Methods Sixteen participants with chronic Achilles tendinopathy completed the Lower Extremity Functional Scale (LEFS) and the Victorian Institute of Sport Assessment-Achilles scale (VISA-A) and quantitative sensory tests (pressure pain threshold, heat temporal summation, and heat pain threshold) at baseline, one week, seven weeks, and then at a one month post intervention follow-up. The NxES was applied for one week, then followed by plantarflexion eccentric exercise for six weeks. Changes across timepoints were assessed using repeated measures ANOVA and post hoc analysis to describe differences. Hedges g effect sizes were also calculated. # Results There was a significant improvement in LEFS (p < 0.001) and VISA-A (p < 0.001) from baseline to one month follow-up, with a mean change of 9.6 ± 7.7 and 19.4 ± 17.7 points respectively. Pressure pain threshold of the involved Achilles tendon increased over time (p < 0.001) with significant improvements after NxES application (p = 0.002) and after six weeks of eccentric exercise (p < 0.001). There were significant improvements from baseline to one month follow-up for heat temporal summation (p = 0.001) and heat pain threshold ( p < 0.001). # Conclusions For individuals with chronic Achilles tendinopathy, a sequential treatment of NxES followed by eccentric exercise resulted in a clinically significant improvement in self-reported pain and function. During the first week of treatment there was a reduction in mechanical hyperalgesia during the NxES-only phase, while a large reduction in primary heat hyperalgesia and additional desensitization to mechanical pain occurred during the eccentric training phase of treatment. # Level of Evidence 2b

Background Neuromuscular electrical stimulation (NMES) is effective in muscle strengthening after orthopedic injury particularly when muscle activation failure is present, but the associated pain can be a barrier. Pain itself can produce a pain inhibitory response called Conditioned Pain Modulation (CPM). CPM is often used in research studies to assess the state of the pain processing system. However, the inhibitory response of CPM could make NMES more tolerable to patients and could improve functional outcomes in people with pain. This study compares the pain-inhibitory effect of NMES compared to volitional contractions and noxious electrical stimulation (NxES). Methods Healthy participants, 18–30 years of age experienced 3 conditions: 10 NMES contractions, 10 bursts of NxES on the patella, and 10 volitional contractions on the right knee. Pressure pain thresholds (PPT) were measured before and after each condition in both knees and the middle finger. Pain was reported on an 11-point VAS. Repeated measures ANOVAs with 2 factors: site and time were performed for each condition followed by post-hoc paired t-tests, with Bonferroni correction. Results Pain ratings were higher in the NxES condition compared to NMES ( p = .000). No differences in PPTs prior to each condition were observed but PPTs were significantly higher in the right and left knees after the NMES contractions ( p = .000, p = .013, respectively) and after the NxES ( p = .006, P -.006, respectively). Pain during NMES and NxES did not correlate with pain inhibition ( p > .05). Self-reported pain sensitivity correlated with pain during NxES. Conclusion NxES and NMES produced higher PPTs in both knees but not in the finger, suggesting that the mechanisms responsible for the reduction in pain are located in the spinal cord and local tissues. Pain reduction was elicited during the NxES and NMES conditions regardless of the self-reported pain ratings. When NMES is used for muscle strengthening significant pain reduction can also occur, which is an unintended benefit of the intervention that could improve functional outcomes in patients.

The purpose of this study was to investigate the influence of sensitivity to sensory input, including pain, on the conditioned pain modulation (CPM) effect of oxious Electrical Stimulation (NxES). Seventeen healthy participants (24.8 (+/- 2) years) were enrolled in this study that was approved by the IRB. Each person participated in a familiarization session, and 2 testing sessions 24 hours apart. Sensory sensitivity was assessed with the Sensory Hypersensitivity Scale, touch and heat/cold detection thresholds. Pain sensitivity was assessed with the Pain Sensitivity Questionnaire, heat/cold pain thresholds, and pressure pain threshold (PPT). Pain modulation was assessed with temporal summation (TS) and CPM involved a test stimulus of PPT and conditioning stimulus was immersion in a cold water bath for 2 min. The NxES: 20 min of electrical stimulation (400 μs pulse duration, 50 pulses/s; 10s on:10s off; intensity was maximum tolerated). The difference between PPT before and after the NxES comprised the treatment effect. Neither Sensitivity to touch or temperature sensations nor pain sensitivity related to the treatment effect of the NxES. A higher the amplitude of pain perception of NxES was associated with greater treatment effect. The NxES was effective in inhibiting pain and reduced the extent of pain facilitation 24 hours after the treatment. CPM was no different after the NxES. The finding suggests that people who are more sensitive to sensations also experience pain inhibition from NxES. The nervous system is not as "reactive" to pain after a treatment of NxES and the lack of change in the CPM after the treatment of NXES suggests that artificially inducing pain inhibition with NXES does not interfere with the normal pain inhibitory function of the nervous system. Thus, any inhibition due to NXES treatment could augment that which is produced by a patient's own nervous system. The purpose of this study was to investigate the influence of sensitivity to sensory input, including pain, on the conditioned pain modulation (CPM) effect of oxious Electrical Stimulation (NxES). Seventeen healthy participants (24.8 (+/- 2) years) were enrolled in this study that was approved by the IRB. Each person participated in a familiarization session, and 2 testing sessions 24 hours apart. Sensory sensitivity was assessed with the Sensory Hypersensitivity Scale, touch and heat/cold detection thresholds. Pain sensitivity was assessed with the Pain Sensitivity Questionnaire, heat/cold pain thresholds, and pressure pain threshold (PPT). Pain modulation was assessed with temporal summation (TS) and CPM involved a test stimulus of PPT and conditioning stimulus was immersion in a cold water bath for 2 min. The NxES: 20 min of electrical stimulation (400 μs pulse duration, 50 pulses/s; 10s on:10s off; intensity was maximum tolerated). The difference between PPT before and after the NxES comprised the treatment effect. Neither Sensitivity to touch or temperature sensations nor pain sensitivity related to the treatment effect of the NxES. A higher the amplitude of pain perception of NxES was associated with greater treatment effect. The NxES was effective in inhibiting pain and reduced the extent of pain facilitation 24 hours after the treatment. CPM was no different after the NxES. The finding suggests that people who are more sensitive to sensations also experience pain inhibition from NxES. The nervous system is not as "reactive" to pain after a treatment of NxES and the lack of change in the CPM after the treatment of NXES suggests that artificially inducing pain inhibition with NXES does not interfere with the normal pain inhibitory function of the nervous system. Thus, any inhibition due to NXES treatment could augment that which is produced by a patient's own nervous system.

Inhibition of rotator cuff activation and force after local experimental pain has been previously shown. Clinically, strength is often indexed to the uninvolved side in order to quantify deficits during injury and recovery. This study assessed the effect of experimental subacromial pain on contralateral shoulder external rotation (ER) force and activation. We hypothesized that subacromial pain would not affect contralateral shoulder external rotation force and voluntary activation (VA) of the contralateral infraspinatus because we believe that the effects of acute experimental pain will largely exert an ipsilateral, spinal segmental effect. Twenty healthy adults were tested. External rotation force and VA were tested while participants performed maximum voluntary isometric contractions of shoulder external rotation, during which a brief electrical stimulus was applied to the infraspinatus muscle at an intensity that maximized external rotation force. To elicit pain, 1.5 ml of 5% hypertonic saline was injected into the contralateral subacromial space. Mean (SD) pain immediately after injection was 6.3/10 (0.85) resulting in a 7.6% decline in contralateral external rotation force (p < .01) and 3.3% decline in infraspinatus muscle VA (p = .48). A subset of participants (n = 9) showed a more substantial decline in both force (15.4%; p < .000001; d = -3.53) and VA (8.7%; p = .045; d = -0.98). Experimental shoulder pain had a modest effect on contralateral ER force and VA in a subset of participants; therefore, it may be important to index or compare strength bilaterally throughout rehabilitation to capture this bilateral effect as pain resolves.

Background: The relationships between swelling after total knee arthroplasty (TKA) and quadriceps strength and functional performance are poorly understood. Therefore, the aim of this study was to examine the relationships between lower extremity swelling, measured using bioelectrical impedance assessment (SF-BIA), and quadriceps strength and timed up and go (TUG) times following TKA. Methods: 53 participants (64 +/- 9.5 y/o, 43% male) undergoing primary unilateral TKA were recruited for the longitudinal observational study with repeated measures. Quantities of swelling were examined for contribution to two and six-week outcomes of strength and TUG time using hierarchical regression controlling for age, sex, and the baseline value of the dependent variable. Swelling was assessed using bioelectrical impedance assessment and quantified as the peak level of swelling and cumulative swelling (integral) over the post-TKA time window. Maximum isometric quadriceps strength (MVIC) was measured using a electromechanical dynamometer and participant functional performance measured using the TUG. Results: Neither peak swelling nor cumulative swelling significantly contributed to the variance of two-week quadriceps strength. At six weeks, peak swelling significantly improved the variance in maximal quadriceps strength by an additional four percent (p = 0.05), while cumulative swelling did not significantly contribute. Peak swelling significantly contributed to the variance in two-week (16%) and six-week (five percent) TUG times (p < 0.05), but the cumulative swelling did not. Conclusions: Peak swelling represents a value of post-TKA swelling that is associated with strength and function. Reducing the peak level of swelling, occurring early after surgery, may improve patient functional recovery. (C) 2019 Elsevier B.V. All rights reserved.

Background: Achilles tendinopathy is a common overuse injury sustained by athletes (including runners) that often becomes chronic. There is evidence that chronic musculoskeletal pain conditions exhibit signs of nervous system sensitization. Hypothesis/Purpose: The objective of this study was to compare pain sensitivity (pressure pain threshold [PPT], heat pain threshold [HPT], and heat temporal summation [HTS]) between active healthy adults with and without chronic Achilles tendinopathy in order to determine if signs of peripheral and/or central sensitization exist in chronic Achilles tendinopathy. Study Design: Cohort study Methods: Seventeen participants with chronic (>= 3 months) Achilles tendinopathy (39.0 years +/- 10.81) and 24 healthy controls (31.83 years +/- 8.92) were included. All participants completed the Pain Catastrophizing Scale (PCS). Participants in the Achilles group also completed the Lower Extremity Functional Scale (LEFS) and the Victorian Institute of Sport Assessment-Achilles (VISAA). Pain processing was quantified using PPT, HPT and HTS tests. Results: There were no significant differences in PCS scores between groups. In the Achilles tendinopathy group, the mean VISA-A score was 58.5 +/- 18.4; the mean LEFS was 63.7 +/- 8.0. Primary hyperalgesia (decreased pain threshold at injury site) was detected in the Achilles tendinopathy group, as evidenced by lower PPT (p< 0.0001) and lower HPT (p =0.028). Mechanical secondary hyperalgesia, a sign of central sensitization, was found in the Achilles tendinopathy group at the tibialis anterior (p = 0.042) and non-involved Achilles (p =0.025), but not at the thenar eminence (p = 0.276). The degree of HTS was not different between groups (p = 0.981). Conclusion: Active participants with chronic Achilles tendinopathy showed signs of both peripheral and central sensitization; however, widespread hyperalgesia into the upper extremities and elevated temporal summation were not observed. Evidence of differences in pain sensitivity lend support to the theory for a multifactorial model of tendinopathy, which consists of an impaired motor system, local tendon pathology, and changes in the pain/nociceptive system. Physical therapy management of chronic Achilles tendinopathy may need to address potential changes in the nervous system. Interventions used to treat chronic tendinopathies should be investigated for their potential to resolve peripheral and central sensitization.

Title: Development of a reference chart to monitor postoperative swelling following total knee arthroplasty.Purpose: Lower extremity swelling is a feature of total knee arthroplasty. Until recently, clinicians lacked tools to accurately measure swelling in clinical settings, but bioelectrical impedance assessment has shown promise in this regard. The purpose of this study was to develop a reference chart of lower extremity swelling following total knee arthroplasty.Method: Fifty-six participants (54% male, mean age = 64 years) were followed for the first 7 weeks following total knee arthroplasty, during which frequent lower extremity bioelectrical impedance assessments were performed. Using Generalized Additive Models for Location Scale and Shape, a reference chart for swelling was developed with bioelectrical impedance assessment data from the first 40 patients enrolled in the study (223 observations) and preliminarily tested for performance in the remaining 16 patients' data (96 observations).Results: The reference chart illustrates approximately 10% per day increase for the first 3 days following surgery. Peak swelling occurs 6-8 days following surgery; the 10th percentile demonstrates a peak of 25%, whereas the 90th percentile peaks at 47%. In the test data, this reference chart demonstrated accurate coverage at each estimated centile.Conclusion: The reference chart provides a novel framework for monitoring swelling following total knee arthroplasty and may augment clinical decisions to improve postoperative swelling management.Implications for rehabilitationThe use of bioelectrical impedance assessment provides an accurate and easily implemented approach for rehabilitation professionals to measure swelling.The reference chart provided allows for monitoring of patient recovery of swelling following total knee arthroplasty.Precise depictions of where a patient's swelling is in reference to others will improve clinical decision making at the individual level.

Background The prone instability test is used to identify individuals with low back pain (LBP) who would benefit from trunk stabilization exercises. Although activity from muscles during the leg-raising portion of the prone instability test theoretically enhances spinal stiffness and reduces pain, evidence for this is lacking. Objectives To compare and contrast (1) pain and stiffness changes between prone instability testing positions, and (2) muscle activation patterns during the prone instability test leg raise in individuals with and without LBP. Methods Participants with (n = 10) and without (n = 10) LBP participated in this laboratory case-control study. Spinal stiffness was measured using a beam-bending model and 3-D kinematic data. Stiffness changes were compared across the test positions and between groups. Surface electromyographic data were collected on trunk and limb musculature. Principal-component analysis was used to extract muscle synergies. Results Spinal stiffness increased across testing positions in all participants (P<.05). Participants with LBP experienced reduced pain during the test (P<.001). No between-group difference was found in spinal stiffness during leg raising during the test (P>.05). Participants without LBP used 3 muscle synergies during the leg raise and participants with LBP used 2 muscle synergies. Conclusion Spinal stiffness increased in all participants; however, participants without LBP demonstrated a muscle synergy pattern where each synergy was associated with a distinct function of the prone instability test. Participants with LBP used a more global stabilization pattern, which may reflect a maladaptive method of enhancing spinal stability. J Orthop Sports Phys Ther 2019;49(12):899–907. Epub 3 Aug 2019. doi:10.2519/jospt.2019.8577

Background: Quadriceps weakness is a hallmark of total knee arthroplasty and is driven by reduced voluntary muscle activation following the surgical procedure. The mechanisms underlying postoperative activation deficits are not well established, although nociception has been implicated via both spinal reflex and supraspinal pathways. The purpose of this study was to assess the role of nociception in postoperative recovery of strength and activation. Methods: A total of 53 participants were assessed prior to total knee arthroplasty and at 6 weeks postoperatively. Quadriceps strength was measured by maximum voluntary isometric contraction, and activation was measured by the doublet interpolation technique. The pressure-pain threshold was used to measure local sensitization (at the knee joint) and systemic sensitization (at the forearm). Changes in outcomes (strength and activation) were regressed against pressure-pain threshold measurements. Mediation analyses were planned for significant associations to investigate whether deficits in voluntary activation were implicated on a causal pathway between pressure-pain threshold measures and postoperative strength loss. Results: Knee pressure-pain threshold measures were significantly associated with reduced voluntary quadriceps activation (beta = −0.04; p = 0.009) and diminished quadriceps strength after total knee arthroplasty (beta = −0.07; p = 0.001). There was also a mediation effect of voluntary activation on the relationship between the knee pressure-pain threshold and quadriceps strength. After correcting for multiple comparisons, relationships between the forearm pressure-pain threshold and strength and activation did not reach significance. Conclusions: The measures of local nociceptor sensitization were related to reduced strength and activation following total knee arthroplasty. This is consistent with a causal pathway linking increased firing of knee joint nociceptors to reduced activation and reduced strength. Future randomized studies should investigate whether peripherally directed pain therapies reduce pain while also promoting the recovery of quadriceps strength via an improved capacity for voluntary activation. Level of Evidence: Therapeutic Level IV . See Instructions for Authors for a complete description of levels of evidence.

Total knee arthroplasty (TKA) is the most common elective orthopedic surgery performed in the United States. Following surgery patients experience significant lower extremity swelling that is related to poor satisfaction with surgery and is hypothesized to contribute to functional decline. However, in practice, precise and reliable methods for measuring lower extremity swelling do not exist. The purpose of this study was to provide reliability and precision parameters of an innovative approach, single frequency bioelectrical impedance assessment (SF-BIA), for measuring post-TKA lower extremity swelling. Swelling in 56 patients (64.3 ± 9.3 years; 29 males) was measured before and after TKA using SF-BIA and circumferential measures (CM). Reliability of the measures was calculated using Intraclass Correlation Coefficients (ICC). Precision of the measures was provided using standard error of the measurement and minimal detectable change (MDC90). Change values between time points for SF-BIA and CM are provided. SF-BIA was found to have greater reliability following surgery compared to CM (ICC = 0.99 vs 0.68). SF-BIA was found to have an MDC90 = 2% following surgery, indicating improved ability to detect minute fluctuations in swelling compared to CM (MDC90 = 6%) following surgery. These results indicate that SF-BIA improves the precision and reliability of swelling measurement compared to CM.

Determining volitional activation (VA) can provide insights on the cause of muscle weakness in orthopedic and neurological populations. Two electrical stimulation techniques are traditionally used to quantify VA: interpolation (IT) and superimposition (CAR). IT allows for a more accurate VA estimation, however it requires individuals to be stimulated twice, compared to once for CAR, and thus increases stimulation associated discomfort. To date, there is no agreement on what is the best practical technique for calculating quadriceps VA. This paper aims to address this problem by determining what reference force (i.e., using either peak force or force at the time of stimulation) and type of stimulation (train of pulses (burst), doublet, and twitch) is the best technique to use. Our findings showed that the IT with the force at the time of stimulation as a reference should be used to determine VA and that when a burst was used, the VA ratio computations were more accurate. Additionally, using a twitch with a 2ms pulse duration produced reliable VA calculations and may be an acceptable alternative for pain-sensitive subjects. Accurate assessment of VA deficits can help clinicians design rehabilitation programs that are based on subject-specific strength impairments and are more effective.

BACKGROUND:Achilles tendinopathy is a common overuse injury in running and jumping athletes. Currently, we do not understand why some conservative interventions (eg, noxious electrical stimulation and eccentric training) may reduce the pain associated with tendinopathy.OBJECTIVE:To determine whether noxious electrical stimulation (NES) or eccentric contractions would alter pain sensitivity around the asymptomatic Achilles tendon.DESIGN:A double-blind trial with block-randomization by gender into 3 intervention arms: NES, eccentric contractions, or low-intensity cycling.PARTICIPANTS:A total of 40 volunteers with no current pain conditions started the study, and 39 completed follow-up testing.METHODS:Participants underwent 2 baseline sessions to assess pain sensitivity response stability of pressure pain threshold (PPT), heat pain threshold (HPT), and heat temporal summation (HTS) over the Achilles tendon. Immediately after the second baseline session, participants performed 1 session of an intervention and were tested immediately postintervention and the next morning. Eccentric-only plantarflexor exercise was performed (4 sets of 15 repetitions) using full bodyweight and slow, 5-second contractions. Noxious electrical stimulation was applied to the Achilles for 20 minutes and dosed to the subjects' pain tolerance. Low-intensity cycling was dosed (60-70 W for 20 minutes) to minimize occurrence of exercise-induced hypoalgesia. The PPT was the primary outcome measure.RESULTS:For PPT, both NES (P < .001) and eccentric (P = .003) groups were less sensitive to pressure immediately posttreatment, and the eccentric group maintained this effect through the next morning (P = .043). No group differences were seen for HPT, but the NES (P = .031) and eccentric (P = .036) groups had less HTS the next morning.CONCLUSIONS:A single session of eccentric exercise and NES can produce immediate and next-day reductions in pain sensitivity in asymptomatic adults. The immediacy of these effects points toward a neurophysiologic mechanism. Future research needs to be performed in clinical populations and to assess any cumulative effects to repetitive intervention.

BACKGROUND AND PURPOSE:Achilles tendinopathy is a common overuse injury sustained by athletes including runners. The use of noxious electrical stimulation for the treatment of chronic tendinopathies is a novel treatment intervention, which may alter pain perception and serve as adjunct technique in the recovery of painfree function. The purpose of this case report is to demonstrate the use of noxious electrical stimulation for the treatment of chronic, bilateral Achilles tendinopathy that was resistant to conservative treatment using plantarflexor eccentric exercise.CASE DESCRIPTION:A 27-year old male runner was referred to physical therapy with a 7-year history of bilateral Achilles tendinopathy. He scored a 73/80 on the Lower Extremity Functional Scale (LEFS) and a 64% on the Victorian Institute of Sports Assessment-Achilles (VISA-A). Pain pressure threshold testing of the Achilles tendon was performed, followed by a single session of noxious electric stimulation to bilateral Achilles tendons, and the subject was instructed to continue with eccentric gastroc-soleus complex strengthening as previously performed.OUTCOMES:Pain pressure threshold testing was performed to the mid-portion of the posterior Achilles tendon. The left Achilles tendon mean was 10.50kg and right Achilles tendon was 8.33kg prior to the noxious stimulation intervention. Twenty-four hours after the noxious stimulation treatment, improvements in mean pain threshold testing were found for both the left (16.31kg) and right (12.36kg) Achilles tendons. At one month after the physical therapy noxious stimulation session, the subject was able to progress his workouts to include sprints and interval training. His LEFS improved to 76/80 and his VISA-A improved to 96%.DISCUSSION:The case illustrates the successful pain reduction and return to progressive sports activity in a runner with chronic Achilles tendinopathy. The utilization of noxious electric stimulation may have altered the pain perception of the nervous system as evidenced by the improvement in pain pressure threshold testing. Future studies on the application of noxious electric stimulation on chronic Achilles tendinopathy may help support the benefit of this intervention on pain and function.LEVEL OF EVIDENCE:Therapy, Level 4.

Background: Cervical spinal cord injury (SCI) models in rats have become increasingly useful because of their translational potential. The goal of this study was to design, develop and validate a quick and reliable forelimb locomotor rating scale for adult rats with unilateral cervical SCI injury.New method: Adult female rats were subjected to a C5 unilateral mild contusion (n = 10), moderate contusion (n = 10) or hemisection injury (n = 9). Forelimb locomotion was evaluated before injury, four times during the first week (Days 2, 3, 4 and 7) and weekly for up to 8 weeks post-injury. Scoring categories were identified and animals were ranked based on their performance in these categories. The scale was validated for its usefulness by comparing animals with different injury models (dorsolateral funiculotomy C3/4), levels of injury (moderate contusion C4) and sex (male - moderate contusion C3/4) and also by correlating FLS scores with other established behavioral tests (grid walking and kinetic tests).Results and comparison with existing methods: Forelimb performance on both the grid-walking and kinetic tests was positively correlated with the forelimb locomotor rating scale (FLS). Histological analysis established a positive correlation between the spared tissue and the observed FLS score. Our results show that the new rating scale can reliably detect forelimb deficits and recovery predicted by other behavioral tests. Furthermore, the new method provides reproducible data between trained and native examiners.Conclusion: In summary, the proposed rating scale is a useful tool for assessment of injury and treatments designed to enhance recovery after unilateral cervical SCI. (c) 2014 Elsevier B.V. All rights reserved.

Background and Purpose: Cervical spinal cord injury results in specific deficits in forelimb function. In the rat, lesions to the rubrospinal tract impair forelimb function despite the presence of an intact corticospinal tract. Both functional and anatomical recovery have been promoted by transplantation of neuronal and glial restricted precursors (NRP/GRP) following injury, and task-specific practice is used clinically to maximize recovery of function. We tested the hypothesis that combination therapy of daily task practice and NRP/GRP cell transplants will improve reach-to-grasp function. Methods: Forty-one adult female rats received a lesion to the right cervical dorsolateral funiculus. They were randomly divided into 4 groups for the study: Control (n=11), NRP/GRP Transplant (n=14), Task Practice (n=8), and Task Practice + NRP/GRP (n=8). All animals were assessed pre-injury and during weeks 1 and 8 postoperatively on two reach-to-grasp tests (Single Pellet and Staircase Reaching). Results: Task Practice + NRP/GRP and Task Practice groups achieved significant recovery of function in the Staircase Reaching test at week 8 of recovery. Analysis of individual kinematic elements from the Single Pellet Reaching test allows detailed quantitation of specific movements. While major differences were not observed in the Single Pellet Reaching, the Digits Open and Pronation qualitative component scores were higher in the Task Practice + NRP/GRP group compared to controls at 8 weeks post injury. Conclusions: While task practice improves recovery of forelimb function following incomplete spinal cord injury, combination therapy of daily task practice and cell transplantation practice did not result in superior recovery of reach-to-grasp function.

Background: The effect of pain on muscle activation is poorly understood. This study examined the effects of acute experimental pain on rotator cuff muscle force and voluntary activation (VA). We hypothesized that acute subacromial pain would cause inhibition of infraspinatus VA with a corresponding decrease in external rotation force.Materials and methods: Seventeen healthy adults with no known shoulder pathology were tested. Isolated external rotation force was tested on a dynamometer. Participants performed 2 baseline maximum voluntary isometric contractions of external rotation, during which maximal electrical stimulation was used to assess VA. To elicit pain, 1.5 mL 5% hypertonic saline was injected into the subacromial space, and testing of maximum voluntary isometric contractions force and VA was repeated 3 times at 5-minute intervals.Results: Mean +/- standard deviation initial pain from the injection was 6.6 +/- 1.3 points of 10 possible and produced a 32.8% decline in force and a 22.7% decline in VA (P < .05). Pain diminished over a 10-minute period. As pain resolved, force and VA improved (P < .0125). There was a strong relationship between force and VA (r(2) = 0.78, P < .05) and a moderate relationship between pain and VA (r(2) = 0.31, P < .05).Conclusions: Experimental subacromial pain elicits a decline in force and VA of the infraspinatus. Although this study only examines acute experimental pain, it supports the concept that pain affects rotator cuff muscle recruitment and function, which may contribute to abnormal shoulder mechanics in patients with rotator cuff pathology.

Since 2009, four randomized controlled trials have investigated the use of Neuromuscular Electrical Stimulation (NMES) as a treatment modality following total knee arthroplasty (TKA). Two of these studies demonstrated a treatment effect of NMES for improving physical function, while another study failed to find additional benefit of NMES relative to a progressive exercise intervention. The fourth study demonstrated non-inferiority of NMES compared supervised physical therapy. These studies differed substantially in their methodology, including the timing, duration, treatment volume and intensity of NMES interventions. The purpose of this review is to examine and discuss variations between these recent trials to synthesize the current state of evidence for NMES in post-TKA rehabilitation. When comparing intervention parameters across recent studies, it appears that high intensity NMES performed regularly during the immediate postoperative phase helped to attenuate dramatic losses in quadriceps strength following TKA, thereby resulting in overall improvements in strength and function.

Individually, motor training, pharmacological interventions, and housing animals in an enriched environment (EE) following spinal cord injury (SCI) result in limited functional improvement but, when combined, may enhance motor function. Here, we tested amphetamine (AMPH)-enhanced skilled motor training following a unilateral C3-C4 contusion injury on the qualitative components of reaching and on skilled forelimb function, as assessed using single-pellet and staircase reaching tasks. Kinematic analysis evaluated the quality of the reach, and unskilled locomotor function was also tested. Animals receiving AMPH and skilled forelimb training performed better than operated control animals on qualitative reaching, but not on skilled reaching. Those that received the combination treatment and were housed in EE cages showed significantly less improvement in qualitative reaching and grasping. Kinematic analysis revealed a decrease in digit abduction during skilled reaching among all groups, with no differences among groups. Kinematics provided no evidence that improved function was related to improved quality of reach. There was no evidence of neuroprotection in the cervical spinal cord. The absence of evidence for kinematic improvement or neuroprotection suggested that AMPH-enhanced motor training is due primarily to supraspinal effects, an enhancement of attention during skilled motor training, or plasticity in supraspinal circuitry involved with motor control.

HYPOTHESIS:Failure of voluntary activation is an important source of weakness in several different muscles after injury or surgery. Despite the high prevalence of shoulder rotator cuff disorders and associated weakness, no test currently exists to identify voluntary activation deficits for the rotator cuff. The purpose of this study was to develop a test to quantify voluntary activation of the infraspinatus. We hypothesized that there would be a consistent relationship between the voluntary activation level and different force levels and that reduced voluntary activation would partially account for reduced force with fatigue. MATERIALS AND METHODS:Twenty healthy volunteers underwent assessment of voluntary activation using an electrical stimulus applied to the infraspinatus muscle during active isometric external rotation. Voluntary activation was assessed across several levels of external rotation effort and during fatigue. RESULTS:The voluntary activation-percent force relationship was best fit using a curvilinear model, and the fatigue test reduced both force and voluntary activation by 46%. DISCUSSION:In the nonfatigued state, the voluntary activation-percent force relationship is similar to that reported for the quadriceps. After fatigue, however, greater failure of voluntary activation was observed compared with reported values for other upper and lower extremity muscles, which may have implications for the understanding and treatment of rotator cuff pathology. CONCLUSION:A measure of voluntary activation for the infraspinatus varied with the percent maximum force in a predictable manner that is consistent with the literature. The infraspinatus may be more susceptible to failure of voluntary activation during fatigue than other muscles.