Intra-articular injection of a substance P inhibitor affects gene expression in a joint contracture model.

Substance P (SP), a neurotransmitter released after injury, has been linked to deregulated tissue repair and fibrosis in musculoskeletal tissues and other organs. Although SP inhibition is an effective treatment for nausea, it has not been previously considered as an anti-fibrotic therapy. Although there are extensive medical records of individuals who have used SP antagonists, our analysis of human registry data revealed that patients receiving these antagonists and arthroplasty are exceedingly rare, thus precluding a clinical evaluation of their potential effects in the context of arthrofibrosis. Therefore, we pursued in vivo studies to assess the effect of SP inhibition early after injury on pro-fibrotic gene expression and contractures in an animal model of post-traumatic joint stiffening. Skeletally mature rabbits (n = 24) underwent surgically induced severe joint contracture, while injected with either fosaprepitant (a selective SP antagonist) or saline (control) early after surgery (3, 6, 12, and 24 h). Biomechanical testing revealed that differences in mean contracture angles between the groups were not statistically significant (P = 0.27), suggesting that the drug neither mitigates nor exacerbates joint contracture. However, microarray gene expression analysis revealed that mRNA levels for proteins related to cell signaling, pro-angiogenic, pro-inflammatory, and collagen matrix production were significantly different between control and fosaprepitant treated rabbits (P < 0.05). Hence, our study demonstrates that inhibition of SP alters expression of pro-fibrotic genes in vivo. This finding will motivate future studies to optimize interventions that target SP to reduce the formation of post-traumatic joint contractures.

Psychologic Factors Do Not Affect Placebo Responses After Upper Extremity Injections: A Randomized Trial.

BACKGROUND: Studies on how psychologic factors influence the placebo effect have shown conflicting results in an experimental setting. Pessimists are more likely to experience a nocebo effect (feel worse after an inert intervention), whereas other studies suggest that patients with more symptoms of depression or anxiety or greater neuroticism have a greater response to a placebo. This is important because treatment benefits are potentiated by placebo effects, and optimal utilization of this phenomenon may improve clinical outcomes. QUESTIONS/PURPOSES: (1) What psychologic factors are associated with a decrease in magnitude of limitations (Disabilities of the Arm, Shoulder and Hand [DASH] score) and pain intensity (visual analog scale [VAS] for pain) after placebo injections for the treatment of painful nontraumatic upper extremity conditions? (2) What psychologic factors are associated with achieving a minimum clinically important difference (MCID) in disability and pain intensity? METHODS: We performed a secondary analysis of data acquired in two prospective, double-blind, randomized controlled trials of patients with lateral elbow pain, trapeziometacarpal arthrosis, and de Quervain tendinopathy who received a single injection of dexamethasone and lidocaine or lidocaine alone (placebo). One hundred six patients were included between June 2003 and February 2008. Sixty-three patients (59%) received dexamethasone and lidocaine, and we analyzed the subset of 43 patients (41%) who received lidocaine alone. The primary outcomes of interest were the DASH questionnaire and the VAS for pain measured three times: when they received the injection, between 1 and 3 months after the injection, and between 5 and 8 months after the injection. Seven patients missed the first followup visit and 14 patients missed the second visit. Based on previous research, we chose a MCID threshold of 10 for the DASH and a threshold of 1.0 for the VAS score. In bivariate analysis, we accounted for sex, race, marital status, degree, education, work status, pretreatment pain, diagnosis, symptoms of depression (Center of Epidemiologic Studies-Depression Scale), coping strategies in response to nociception (Pain Catastrophizing Scale), and personality traits (measured with the Multidimensional Health Locus of Control scale and the Eysenck Personality Questionnaire-Revised score). Variables with p values < 0.10 in bivariate analysis were included in the multivariable regression models. An a priori power analysis showed that a sample of 43 participants provides 80% statistical power, with α set at 0.05, for a regression with five predictors if the depression score would account for 15% or more of the variability in pain score. We used multiple imputations (imputations = 50) for a total of 66 (8.5%) missing or incomplete questionnaires. RESULTS: In the final multivariable models, no psychologic factors were associated with a change in DASH score between injection and followup, and no factors were associated with greater decrease in pain intensity. After injection, no psychologic factors were independently associated with achieving a MCID in the DASH and VAS. CONCLUSIONS: Our study confirms that patient factors are less important mediators of the placebo effect than clinician factors. In other words, clinician warmth and competence can help diminish symptoms and limitations of people in various states of mind, even when using inert or ineffective treatments. LEVEL OF EVIDENCE: Level II, therapeutic study.

Corticosteroid or placebo injection combined with deep transverse friction massage, Mills manipulation, stretching and eccentric exercise for acute lateral epicondylitis: a randomised, controlled trial.

BACKGROUND: Lateral epicondylitis of the elbow is a frequent condition with long-lasting symptoms. Corticosteroid injection is increasingly discouraged and there is little knowledge on the combined effect of corticosteroid injection and physiotherapy for acute conditions. We wanted to investigate the efficacy of physiotherapy alone and combined with corticosteroid injection for acute lateral epicondylitis. METHODS: A randomized, controlled study with one-year follow-up was conducted in a general practice setting in Sarpsborg, Norway. We included 177 men and women aged 18 to 70 with clinically diagnosed lateral epicondylitis of recent onset (2 weeks to 3 months). They were randomly assigned to one of three treatments: physiotherapy with two corticosteroid injections, physiotherapy with two placebo injections or wait-and-see (control). Physiotherapy consisted of deep transverse friction massage, Mills manipulation, stretching, and eccentric exercises. We used double blind injection of corticosteroid and single blind assessments. The main outcome measure was treatment success defined as patients rating themselves completely recovered or much better on a six-point scale. RESULTS: One hundred fifty-seven patients (89 %) completed the trial. Placebo injection with physiotherapy showed no significant difference compared to control or to corticosteroid injection with physiotherapy at any follow-up. Corticosteroid injection with physiotherapy had a 10.6 times larger odds for success at six weeks (odds ratio 10.60, p < 0.01) compared to control (NNT = 3, 99 % CI 1.5 to 4.2). At 12 weeks there was no significant difference between these groups, but at 26 weeks the odds for success were 91 % lower (OR 0.09, p < 0.01) compared to control, showing a large negative effect (NNT = 5, 99 % CI 2.1 to 67.4). At 52 weeks there was no significant difference. Both control and placebo injection with physiotherapy showed a gradual increase in success. CONCLUSIONS: Acute lateral epicondylitis is a self-limiting condition where 3/4 of patients recover within 52 weeks. Physiotherapy with deep transverse friction massage, Mills manipulation, stretching, and eccentric exercises showed no clear benefit, and corticosteroid injection gave no added effect. Corticosteroid injections combined with physiotherapy might be considered for patients needing a quick improvement, but intermediate (12 to 26 weeks) worsening of symptoms makes the treatment difficult to recommend. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT00826462.

Static progressive versus dynamic splinting for posttraumatic elbow stiffness: a systematic review of 232 patients.

INTRODUCTION: The elbow is prone to stiffness after trauma. To regain functional elbow motion, several conservative and surgical treatment options are available. Nonoperative treatment includes physical therapy, intra-articular injections with corticosteroids, and a static progressive or dynamic splinting program. The objective of this study was to perform a comprehensive review of the literature to evaluate the best current evidence for nonoperative treatment options for posttraumatic elbow stiffness. METHODS: We performed a search of all studies on nonoperative treatment for elbow stiffness in human adults. All articles describing nonoperative treatment of elbow stiffness, written in the English, German, French or Dutch language, including human adult patients and with the functional outcome reported were included in this study. RESULTS: Eight studies (including 232 patients) met our eligibility criteria and were included for data analysis and pooling. These studies included one randomized controlled trial and seven retrospective cohort studies. Static progressive splinting was evaluated in 160 patients. The average pre-splinting range of motion of all elbows was 72°, which improved by 36° after splinting to an average post-splinting arc of motion of 108°. Dynamic splinting was evaluated in 72 patients with an average pre-splinting range of motion of 63°. The average improvement was 37° to an average post-splinting arc of motion of 100°. CONCLUSIONS: Both dynamic orthoses and static progressive splinting show good results for the treatment of elbow stiffness, regardless of etiology. The choice for one treatment over the other is based on the preference of the surgeon and patient. We recommend to continue nonoperative treatment with dynamic or static bracing for 12 months or until patients stop making progression in range of elbow motion.

Oral creatine supplementation augments the repeated bout effect.

PURPOSE: We examined the effects of creatine supplementation on the response to repeated bouts of resistance exercise. METHODS: Young men (24.1 ± 5.2 yr) were divided into Creatine (CM, n = 9) and Placebo (PL, n = 9) groups. On day (D) 1 and D15, subjects performed four sets of bicep curls at 75% 1-RM to concentric failure. On D8-D13, subjects consumed either 20g/d creatine monohydrate or placebo. Muscle soreness and elbow joint range of motion (ROM) were assessed on D1-D5 and D15-D19. Serum creatine kinase activity (CK) was assessed on D1, D3, D5, D15, D17, and D19. RESULTS: The first exercise bout produced increases in muscle soreness and CK, and decreases in ROM in both groups (p < .001). The second bout produced lesser rises in serum CK, muscle soreness, and a lesser decrease in ROM (bout effect, p < .01 for all), with greater attenuation of these damage markers in CM than PL. CK levels on D17 were lower (+110% over D15 for CM vs. +343% for PL), muscle soreness from D15-19 was lower (-75% for CM vs. -56% for PL compared with first bout), and elbow ROM was decreased in PL, but not CM on D16 (p < .05 for all). CONCLUSIONS: Creatine supplementation provides an additive effect on blunting the rise of muscle damage markers following a repeated bout of resistance exercise. The mechanism by which creatine augments the repeated bout effect is unknown but is likely due to a combination of creatine's multifaceted functions.

The natural progression of adult elbow osteonecrosis related to corticosteroid treatment.

BACKGROUND: In patients with corticosteroid treatment, the elbow is a rare site of osteonecrosis; there is little information about the rate and risk factors of disease progression in symptomatic and asymptomatic elbows. QUESTION/PURPOSES: We determined the delay between the beginning of corticosteroid treatment and different stages of osteonecrosis and which stage and dose of steroids influenced disease progression. METHODS: Osteonecrosis related to corticosteroids was diagnosed by MRI in 50 elbows of 35 adult patients. Thirty elbows were asymptomatic at initial evaluation (19 with Stage I, 11 with Stage II osteonecrosis). Among the 20 elbows symptomatic at initial evaluation, 13 had radiographic evidence of osteonecrosis without collapse (Stage II) and seven had lesions evident only on MRI (Stage I). RESULTS: At latest followup (average, 17 years; range, 10-25 years), of the 30 previously asymptomatic elbows, pain developed in 24 and collapse occurred in 14; of the 20 previously symptomatic elbows, 15 showed collapse (seven initially with Stage I, eight with Stage II osteonecrosis). The average time between diagnosis and collapse was 8 and 5 years, respectively, for symptomatic elbows with Stages I and II osteonecrosis. Stage at initial visit, development of pain, and continuation of peak doses of corticosteroids were risk factors for disease progression in asymptomatic elbows. In symptomatic elbows, the extent in contact with the articular surface and lesion location were the main risk factors for disease progression. CONCLUSIONS: Untreated asymptomatic and symptomatic elbow osteonecrosis related to corticosteroids has a moderate likelihood of elbow collapse, with decrease in ROM, but none of the patients in this case series followed for 10 to 20 years had elbow arthroplasty. LEVEL OF EVIDENCE: Level IV, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

Brachialis tendinopathy: a rare cause of antecubital pain and ultrasound-guided injection technique.

Antecubital pain can be caused by a myriad of pathologies. Abnormalities of the brachialis, in particular, tendinopathy at its insertion, are extremely rare, with no case report in the literature. We report the first case of tendinopathy of the brachialis tendon at its insertion in a 42-year-old male who presented with a year-long history of antecubital pain. The anatomy of the brachialis and the technique for ultrasound-guided steroid injection of the brachialis will also be described.

Efficacy of recombinant human alpha-L-iduronidase (laronidase) on restricted range of motion of upper extremities in mucopolysaccharidosis type I patients.

The aims of the study were to assess the effectiveness of enzyme replacement therapy (ERT) with laronidase on the range of motion (ROM) of upper extremities and influence on activities of daily living (ADLs) of patients with mucopolysaccharidosis type I (MPS I). The ROM of 17 patients with MPS I was followed from the first year of life until the introduction of ERT and after 52-208 weeks of treatment. In all patients (group 1, n = 10), passive ROM was assessed. In patients with Hurler/Scheie or Scheie phenotype (group 2, n = 7) both passive and active ROM, as well as daily life activities, were evaluated. Passive and active ROM was measured by a goniometer, while a health assessment questionnaire was used to assess activities of daily living. The data since the first months of life until the beginning of treatment were obtained by retrospective review of patients' charts. Restriction in ROM of the upper extremities of patients with MPS I was observed from the first year of life. These limitations intensified and became more severe with the patients' age, making patients' self-care more difficult or even impossible. Introduction of ERT led to slower progression of symptoms, especially in the passive range of motion in all patients. Additionally, patients with normal mental development, or only slightly delayed (group 2), who underwent active physical rehabilitation (including mobilisation of nerve system, passive techniques for joint mobility, active gymnastics for muscle power, as well as massage and the training of families for therapy at home) showed improvement in active movement followed by enhanced self-care.

Comparative impact of 2 botulinum toxin injection techniques for elbow flexor hypertonia.

OBJECTIVE: To compare 2 techniques of botulinum toxin injection for elbow flexor hypertonia. DESIGN: Parallel-group, randomized, controlled trial with blinded outcome assessment. SETTING: Laboratory, tertiary rehabilitation hospital. PARTICIPANTS: Adults (N=31) with acquired brain injury (21 with traumatic brain injury, 8 with stroke, 2 with hypoxic encephalopathy) provided 36 sets of elbow flexors with Ashworth Scale scores equal to 3. INTERVENTION: Botulinum toxin type A (BTX-A) was injected with a motor point or a multisite injection technique after obtaining 2 baseline evaluations of the main outcome measures. Motor point technique involved decremental electric stimulation with delivery of 60U of BTX-A (Botox) in 2.4mL or 30U BTX-A in 1.2mL of preservative-free saline at single biceps and brachioradialis motor points, respectively. Distributed injection was performed using electromyographic feedback. Fifteen units in 0.6mL were delivered to each of 4 biceps sites and 2 brachioradialis sites. Total dose (90U) and total injection volume (3.6mL) were identical across groups. Only sites and injection techniques varied. The brachialis was not injected in either group. MAIN OUTCOME MEASURES: Ashworth Scale, Tardieu catch angle, and root mean square surface electromyographic activity of the biceps, brachialis, and brachioradialis. RESULTS: Postintervention testing at 3 weeks showed no significant differences between groups (P range, .31-.82 across 3 outcome measures). However, within each group, significant treatment effects were observed on all outcome measures (all P<.01). For the uninjected brachialis muscle, electromyographic reduction was greater for the distributed group. CONCLUSIONS: In 31 adults with acquired brain injury, single motor point and multisite distributed injections of low-dose, high-volume BTX-A had similar impact. Findings suggest that low-dose, high-volume strategies may have a potential role in reducing drug cost and helping clinicians stay within accepted limits for total body dose in patients with upper motoneuron syndrome requiring many injections.

Time course analysis of the effects of botulinum toxin type a on elbow spasticity based on biomechanic and electromyographic parameters.

OBJECTIVE: To quantify changes of elbow spasticity over time after botulinum toxin type A (BTX-A) injection in the upper extremity of stroke patients. DESIGN: Before-after trial in which the therapeutic effects were followed up at 2, 6, and 9 weeks after the BTX-A injection (Botox). SETTING: Hospital. PARTICIPANTS: Chronic stroke patients (N=8) with upper-limb spasticity. INTERVENTION: BTX-A was injected in upper-limb muscles, including the biceps brachii. MAIN OUTCOME MEASURES: Treatment effects were quantified as the changes in the velocity and the length dependence of hyperexcitable stretch reflexes. Manual sinusoid stretches of the elbow joint at 4 frequencies (1/3, 1/2, 1, 3/2Hz) over a movement range of 60 degrees were performed on patients by using a portable device. The Modified Ashworth Scale (MAS), biomechanic viscosity, and the reflexive electromyography threshold (RET) of the biceps brachii were used to evaluate the degree of hypertonia. RESULTS: The statistical analyses of the MAS score, biomechanic viscosity, and RET revealed a significant decrease in spasticity after the injection (all P<.05). Moreover, our quantitative parameters (biomechanic viscosity, RET) revealed small changes in spasticity after the BTX-A injection that could not be observed from clinical MAS evaluations. Five of 8 subjects showed a maximal reduction in spasticity (in terms of biomechanic viscosity value) within 6 weeks after the injection, whereas it was notable that all subjects exhibited peak RET values at either 2 or 6 weeks after the injection with variable degrees of relapse of spasticity. CONCLUSIONS: Early relapse of spasticity (within 9 weeks of the injection) can be detected from biomechanic and neurophysiologic assessments in a clinical setup. These quantitative indices provide valuable information for clinicians when making decisions to perform additional rehabilitation interventions or another BTX-A injection in the early stages of treatment.

Intra-articular injection of hyaluronic acid is not effective for the treatment of post-traumatic osteoarthritis of the elbow.

PURPOSE: In this study we evaluated the effect and safety of intra-articular injection of hyaluronic acid in 19 consecutive elbows with post-traumatic osteoarthritis. METHODS: In 18 patients (10 male and 8 female patients; mean age, 45.6 years [SD, 15.0 years]), 3 injections of sodium hyaluronate were given within 4 weeks at regular intervals. Evaluation took place just before the first injection, as well as after 3 and 6 months, and consisted of the Elbow Function Assessment Score, the Functional Rating Index of Broberg and Morrey, and the Modified Andrews Elbow Scoring System. Pain was also assessed by means of visual analog scales. RESULTS: Viscosupplementation resulted in slight, short-term pain relief and a very limited decrease in activity impairment at evaluation after 3 months. After 6 months, no beneficial effects were noticed in any of the 19 injected elbows. Other parameters were not influenced by treatment with viscosupplementation at any time. Systemic or local adverse effects did not occur. CONCLUSIONS: Because the use of viscosupplementation for the treatment of post-traumatic osteoarthritis of the elbow provides only slight, short-term pain relief and a very limited decrease in activity impairment and the other parameters were not modified, we believe that viscosupplementation is not suitable for this indication. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Efficacy and safety of ibuprofen for hemophilic arthropathy.

The safety and usefulness of ibuprofen (Motrin) were evaluated in 15 patients suffering from hemophilic arthropathy via a double-blind protocol with individual crossover. No significant increase in hemorrhagic episodes or alteration in platelet function was observed. A decrease in morning stiffness was noted in nine patients, and three decreased markedly their use of other pain medications. We conclude that ibuprofen represents a relatively safe agent for the management of discomfort caused by hemophilic arthropathy in a select group of hemophilic patients.

Botulinum toxin for treatment of cocontractions related to obstetrical brachial plexopathy.

Botulinum toxin type A was recently introduced for treatment of biceps-triceps muscle cocontraction, which compromises elbow function in children with obstetrical brachial plexopathy. This is our preliminary experience with this new approach. Eight children were treated with 2-3 U/kg of botulinum toxin injected in the triceps (4 patients) and biceps (4 patients) muscle, divided in 2 or 3 sites. All patients submitted to triceps injections showed a long-lasting improvement of active elbow flexion and none required new injections, after a follow-up of 3 to 18 months. Three of the patients submitted to biceps injections showed some improvement of elbow extension, but none developed anti-gravitational strength for elbow extension and the effect lasted only three to five months. One patient showed no response to triceps injections. Our data suggest that botulinum toxin can be useful in some children that have persistent disability secondary to obstetrical brachial plexopathy.

[Evaluation of the results of conservative treatment in cases of chronic lateral epicondylitis of the humerus in workers in the metal industry]. / Ocena wyników leczenia zachowawczego w przypadkach przewleklego zapalenia nadklykcia bocznego kosci ramiennej u pracowników zatrudnionych w przemysle metalowym.

The causes of occurrence of tennis elbow (epicondylitis humeri lateralis) in metal workers were analyzed. It has been found that the disease occurred most often in locksmiths and turners with over 20 years of service. After treatment of 35 patients which consisted in transfer to light work, paying respect to plaster cast immobilization, injections in the region of the muscular insertions and physical therapy, good results were achieved enabling 21 patients to resume their jobs.

Effect of treatment based on syndrome differentiation by Chinese medicine on post-traumatic elbow arthritis.

OBJECTIVE: To compare the clinical efficacy of treatment based on syndrome differentiation of Chinese medicine and modern conservative therapeutic program on post-traumatic elbow arthritis (PTEA) in order to provide the guidance in clinical practice. METHODS: Seventy-six patients with PTEA requesting the conservative therapy were equally assigned to two groups randomly. The 38 patients in the treated group were administered with Chinese herbal medicines according to their syndrome typing for oral intake and external washing; while the other 38 patients in the control group were treated orally with glucosamine hydrochloride and Celecoxib, combined with intra-articular injection of sodium hyaluronate and peri-articular pain spot blocking with Triamcinolone Acetonaide Acetate injection. All were followed-up for six months with the therapeutic efficacy assessed by Japanese Orthopaedic Association (JOA) and the Hospital for Special Surgery (HSS) Scale scoring. RESULTS: All the 76 patients completed the trial. The JOA and HSS scores in the two groups were not significantly different before treatment (P>0.05), but they did show significant difference after treatment in terms of total score, joint pain, range of motion, and daily activity (P<0.05). However, there was no difference between the two groups in the improvement of joint stability and deformity (P>0.05). CONCLUSION: Both the Chinese drug therapy according to syndrome differentiation and modern conservative therapy are effective in treating PTEA, but the former shows more superiority, and so it is worthy of clinical spreading.

Influence of botulinum toxin type A treatment of elbow flexor spasticity on hemiparetic gait.

OBJECTIVE: To assess whether walking velocity could be improved in patients with disorders related to upper-motor neuron syndrome (UMNS) by treating elbow flexor spasticity with botulinum toxin type A (BoNTA). DESIGN: This was a prospective, open-label, multicenter, interventional evaluation. The study group of 15 patients (mean age, 51.3 yrs; ten men, five women) were independent ambulators with residual hemiparesis attributable to stroke or traumatic brain injury of at least 18-mo duration. Patients were injected with 120-200 units of BoNTA (BOTOX, Allergan, Inc., Irvine, CA) to the affected biceps, brachialis, and/or brachioradialis. Modified Ashworth scores and gait velocity were assessed before and after BoNTA treatment. An untreated control group was employed to assess the potential impact of time on test-retest reliability of the selected temporal spatial gait parameters. RESULTS: The BoNTA group demonstrated a statistically significant increase in walking velocity from 0.56 m/sec before treatment to 0.63 m/sec after treatment (P = 0.037). The mean modified Ashworth score was significantly reduced from 2.6 before BoNTA treatment to 1.4 after treatment (P = 0.00003). CONCLUSIONS: Treatment of upper-limb spasticity may be an important adjuvant treatment for patients with gait disturbance related to the UMNS.

Effect of load level and muscle pain intensity on the motor control of elbow-flexion movements.

This study assessed interactions between mild/moderate muscle pain and inertial load on the control of human elbow-flexion movements. It is hypothesized that high inertial load combined with moderate muscle pain intensity affect the motor control more than for low inertial-load combined with low-intensity pain. Fifteen subjects performed horizontal pointing movements (70 degree range) under three load conditions: 0, 4, and 10 kg. Pain was induced by injection of 0.5 ml and 1.5 ml hypertonic saline into the biceps muscle. Subjects scored the muscle pain intensity on a visual analogue scale (VAS). Elbow joint position, VAS, and the electromyograms (EMG, m. biceps brachii, m. triceps brachii, m. brachioradialis, and m. trapezius) were recorded. Mild and moderate muscle pain attenuated acceleration profiles [6.1(0.9)%], effective movement amplitude [3.2 (0.7)%], peak velocity [5.8 (0.9)%] and prolonged the reaction time [21 (5)%]. No interaction between muscle pain intensity and inertial load was found for the kinematic parameters. EMG profiles from m. biceps brachii, m. triceps brachii, and m. brachioradialis were similarly attenuated [10.2 (0.80)%] by mild and moderate muscle pain in all inertial load conditions. For high inertial load, the initial agonist EMG burst activity was more attenuated [50 (5.3)%] by moderate muscle pain compared with mild muscle pain [34 (4.2)%]. These data suggest that for high effort-demanding tasks muscle pain differently affects the motor planning according to the pain-intensity level. Perturbations of motor planning lead to changes on movement strategies, which might be a potential cause of musculoskeletal problems.