Total elbow arthroplasty: a prospective clinical outcome study of Discovery Elbow System with a 4-year mean follow-up.

BACKGROUND: Total elbow arthroplasty (TEA) is increasingly used for the treatment of advanced elbow conditions to reduce pain and improve function. However, TEA is still associated with a higher complication rate than total hip and knee arthroplasty despite advances in the design and surgical techniques. This prospective clinical study reports the outcome of the Discovery Elbow System (Biomet, Warsaw IN, USA), which has been in clinical use in the United Kingdom since 2003. METHODS: The study included a total of 100 Discovery Elbows (April 2003 to January 2010) with a minimum 2-year follow-up, including 75 primary and 25 revisions (60% women and 40% men; mean age, 62 years). Outcome was assessed by means of the Liverpool Elbow Score, pain experience, patient satisfaction, range of motion, and radiographic imaging. RESULTS: The mean follow-up period was 48.5 months (range, 24-108 months). The Liverpool Elbow Score improved from 3.79 to 6.36 (P < .001). The percentage of pain-free patients was substantially increased from 7% preoperatively to 64% at the final follow-up. The patient satisfaction rate was over 90%. The flexion-extension arc and pronation-supination arc increased from 72° to 93° and from 86° to 111°, respectively (P < .001). Major postoperative complications included deep infection (2%), progressive aseptic loosening requiring revision (primary, 5%; revision 12%), persistent ulnar neuropathy (3%), and periprosthetic fracture (primary, 6.8%; revision, 8%). CONCLUSION: The Discovery Elbow System resulted in improved function, reduced pain, and high patient satisfaction. Long-term results are required to assess the survivorship of this system.

Muscle strength and its relationship with skeletal muscle mass indices as determined by segmental bio-impedance analysis.

PURPOSE: Despite increasing interest in bio-impedance analysis (BIA) for estimation of segmental skeletal muscle mass (SMM), published results have not been entirely convincing. Furthermore, a better understanding of the relationship between muscle strength and SMM will be useful in interpreting outcomes of physical/training interventions particularly in groups with diverse body sizes (e.g. men vs women). This study aimed to measure SMM in the upper body (upper extremity and torso), to determine its correlation with muscle strength and to examine the effects of gender on muscle strength-muscle mass relationship. METHODS: Segmental (upper extremity and torso) SMM and muscle strength in five distinct shoulder planes (forward flexion, abduction in scapular plane, abduction in coronal plane, internal and external rotation) were measured in 45 healthy participants (22 males, 23 females) with mean age 30.3 years. Statistical analysis included independent t tests, Pearson correlation, and multiple regression analysis. RESULTS: Men and women differed significantly in body mass (BMI: 25.9 ± 4.3 vs 23 ± 3.6) and SMM (p < 0.01). A strong relationship correlation was found between the five shoulder strength measurements and upper extremity SMM (r = 0.66-0.80, p < 0.01), which was not affected by gender. There was a significant gender difference (p < 0.01) in absolute shoulder strength, but not after normalisation to the SMM. CONCLUSION: BIA-estimated SMM of upper extremity and torso was highly correlated with upper extremity (shoulder) strength independent of gender. SMM may, therefore, be useful for the normalisation of muscle strength allowing size-independent comparisons of muscle strength in individuals with diverse physical characteristics.

Responsiveness of the Liverpool Elbow Score in elbow arthroplasty.

BACKGROUND: Responsiveness and floor and ceiling effect are important parameters for evaluating the sensitivity of an outcome instrument in detecting the changes in the clinical condition of patients after an intervention as well as evaluating the content validity of the instrument. The aim of this prospective observational study was to assess these parameters for the Liverpool Elbow Score (LES) in total elbow replacement (TER). METHODS: The study included 121 cemented TER cases with linked elbow prosthesis (Discovery Elbow, Biomet Orthopaedics, Swindon, UK) for various conditions, including inflammatory arthritis, noninflammatory arthritis, trauma, and loosening. The proportion of patients with the lowest score (0 points; floor effect) and maximum score (10 points; ceiling effect) was checked preoperatively and 1 year postoperatively. Distribution-based methods (effect size [ES], standardized response mean [SRM], Guyatt responsiveness ratio [GRR]) and anchor-based methods (receiver operating characteristic [ROC] curve and Spearman correlation coefficient) were used to assess responsiveness. Patient satisfaction after TER was used as an external anchor. RESULTS: Patients were a mean age of 63 years (range, 20-86 years). Large ES (1.64), SRM (1.25), and GRR (1.69) were found during the follow-up period. Area under the ROC curve was 0.71 (95% confidence interval, 0.56-0.87; P = .03). There was significant positive correlation (Spearman correlation coefficient, 0.35; P = .004) between changes in LES and satisfaction level. LES showed no floor and ceiling effect preoperatively and at 1 year postoperatively. CONCLUSION: LES is a responsive measure and has no floor and ceiling effect. LEVEL OF EVIDENCE: This encourages its use as an outcome instrument for TER. Basic Science Study, Development or Validation of Outcome Instruments.

Outcome of Copeland shoulder resurfacing arthroplasty with a 4-year mean follow-up.

BACKGROUND: Published data on the outcome of Copeland shoulder resurfacing arthroplasty (CSRA) are limited. This observational case series study reports the functional and radiological outcome of CSRA during a mean follow-up of 4 years and highlights the correlation between key outcome measures. METHODS: One-hundred two consecutive patients with osteoarthritis (OA-47.1%), rheumatoid arthritis (RA-40.2%), rotator cuff arthropathy (RCA-8.8%), and avascular necrosis (AVN-3.9%) underwent CSRA. The outcome assessment included pain and satisfaction, physical limitation, Oxford Shoulder score (OSS), Constant score (CS), and SF-12. Imaging was reviewed for glenoid morphology (Walch classification) and humeral head (HH) migration. RESULTS: Highest patient satisfaction and lowest pain levels were related to the primary pathology with AVN best followed by OA, RA, and with RCA having the poorest outcome. Comparing the two largest groups the CS was significantly higher in OA (61 ± 21.3) than RA (44 ± 20.5). OSS showed a significant correlation with CS and physical subscale of SF-12. Walch type A (67.6%) and HH migration (47%) were the commonest radiographic observations. OSS, CS, pain, and satisfaction were significantly different between migration and nonmigration groups. CONCLUSION: The CSRA resulted in satisfactory outcome in many patients. AVN and OA were associated with the best and RCA with the poorest results. The CSRA was associated with glenoid erosion and HH migration particularly in RCA. CSRA remains an option in the treatment of arthritic conditions of the shoulder but its future use may be limited to younger patients where implanting a glenoid may be regarded as problematic.

Gaze training supports self-organization of movement coordination in children with developmental coordination disorder.

Children with developmental coordination disorder (DCD) struggle with the acquisition of coordinated motor skills. This paper adopts a dynamical systems perspective to assess how individual coordination solutions might emerge following an intervention that trained accurate gaze control in a throw and catch task. Kinematic data were collected from six upper body sensors from twenty-one children with DCD, using a 3D motion analysis system, before and after a 4-week training intervention. Covariance matrices between kinematic measures were computed and distances between pairs of covariance matrices calculated using Riemannian geometry. Multidimensional scaling was then used to analyse differences between coordination patterns. The gaze trained group revealed significantly higher total coordination (sum of all the pairwise covariances) following training than a technique-trained control group. While the increase in total coordination also significantly predicted improvement in task performance, the distinct post-intervention coordination patterns for the gaze trained group were not consistent. Additionally, the gaze trained group revealed individual coordination patterns for successful catch attempts that were different from all the coordination patterns before training, whereas the control group did not. Taken together, the results of this interdisciplinary study illustrate how gaze training may encourage the emergence of coordination via self-organization in children with DCD.

Subacromial impingement syndrome: An electromyographic study of shoulder girdle muscle fatigue.

Muscle fatigue affecting glenohumeral and/or scapular muscles is suggested as one of the contributing factors to the development of subacromial impingement syndrome (SAIS). Nonetheless, the fatigability of shoulder girdle muscles in association with the pathomechanics of SAIS has not been reported. This study aimed to measure and compare fatigue progression within the shoulder girdle musculature of patients and healthy controls. 75 participants including 39 patients (20 females; 19 males) and 36 healthy controls (15 females; 21 males) participated in the study. Study evaluated the progression of muscle fatigue in 15 shoulder girdle muscles by means of surface and fine-wire EMG during submaximal contraction of four distinct movements (abduction, flexion, internal and external rotation). Shoulder strength, subjective pain experience (McGill Pain Questionnaire), and psychological status (Hospital Anxiety and Depression Scale) were also assessed. The results were compared between patient and control groups according to the gender. Despite marked fatigue observed in the majority of muscles particularly during flexion and abduction at 90°, overall results indicated a lower tendency of fatigue progression in the impingement group across the tests (p < 0.05 - p < 0.001). Shoulder Strength, pain experience, and psychological status were significantly different between the two groups (P < .05). Lower tendency to fatigue progression in the impingement group can be attributed to the presence of fear avoidance and pain-related muscle inhibition, which in turn lead to adaptations in motor programme to reduce muscle recruitment and activation. The significantly higher levels of pain experience and anxiety/depression in the impingement group further support this proposition.

Pain, functional disability, and psychologic status in tennis elbow.

OBJECTIVES: First to compare pain and functional disability in tennis elbow (TE) patients with healthy controls. Second, to evaluate the relationship between the 2 major psychologic factors (anxiety and depression) and TE. METHODS: Sixteen TE patients were recruited from 46 consecutive attendees at an upper limb clinic: inclusion criteria were lateral epicondyle tenderness, pain with resisted wrist and middle finger extension and at least 3 months localized lateral elbow pain. Sixteen healthy controls with no upper limb problem were recruited from students and staff. Participants were given 4 questionnaires, together with instructions for completion: Disabilities of the Arm, Shoulder, and Hand, Patient-Rated Forearm Evaluation Questionnaire, Patient-Rated Wrist Evaluation Questionnaire, and Hospital Anxiety and Depression Scale. The independent t test was used to compare the total and subscale scores between the groups. RESULTS: Significantly higher scores were found in TE for pain and function subscales and also total score for Disabilities of the Arm, Shoulder, and Hand, Patient-Rated Forearm Evaluation Questionnaire, and Patient-Rated Wrist Evaluation Questionnaire. For Hospital Anxiety and Depression Scale, both anxiety and depression subscales (P<0.001) and the total score (P<0.01) were significantly higher in TE. According to the anxiety and depression subscales, 55% and 36% of patients, respectively, were classified as probable cases (score >11). DISCUSSION: TE patients showed markedly increased pain and functional disability. Significantly elevated levels of depression and anxiety pointed out the importance of psychologic assessment in TE patients. In the development of supportive and treatment strategies, we suggest the combination of "upper limb" and "psychologic" assessment tools.

POSTURAL ALTERATIONS IN PATIENTS WITH SUBACROMIAL IMPINGEMENT SYNDROME.

BACKGROUND: An aberrant upper body posture has been proposed as one of the etiological factors contributing to the development of subacromial impingement syndrome (SAIS). Clinicians have translated this supposition into assessment and rehabilitation programs despite insufficient and conflicting evidence to support this approach. PURPOSE: The purpose of this study was to compare several postural variables between the SAIS patients and asymptomatic healthy controls. STUDY DESIGN: Case-Control Study. METHODS: A total of 75 participants including 39 patients (20 females; 19 males) and 36 healthy controls (15 females; 21 males) participated in the study. Study evaluated several postural variables including forward head posture (FHP), forward shoulder posture (FSP), thoracic kyphosis index (TKI), scapular index (SI), normalized scapular protraction (NSP), and the lateral scapular slide test (LSST). The variables were compared between patient and control groups according to sex. RESULTS: Significant differences were observed in the female patients compared to asymptomatic controls for the FHP (49.38 + 9.6o vs 55.5o+8.38, p=0.03), FSP (45.58 + 10.1o vs 53.68 + 7.08, p=0.02), and LSST in third position (10.2 + 2.1cm vs 11.5 + 0.7cm, p=0.01). Male patients showed a significant difference only in the FSP compared to controls (61.9o+9.4o vs 49.78 + 9.28, p<0.001). CONCLUSIONS: While inadequate data on the relationship between dysfunctional posture and SAIS has led to broad variations in current rehabilitation strategies, the results of the present study revealed different patterns of postural aberrations in female and male patients with SAIS. This clarifies the need to develop individualized or sex-specific approaches for assessing posture in men and women with SAIS and rehabilitation programs based on the assessment results. LEVEL OF EVIDENCE: 3b.

Minimal clinically important difference of Liverpool Elbow Score in elbow arthroplasty.

BACKGROUND: The minimal clinically important difference (MCID) that allows the interpretation of small but meaningful changes after intervention has not been reported for the Liverpool Elbow Score (LES). This study aimed to determine the MCID for the LES in patients undergoing total elbow replacement. METHODS: This observational study is based on preoperative and 1-year postoperative clinical outcome of total elbow replacement (Discovery Elbow System) in 71 patients using the LES. A 4-point Likert-like transition scale was used to evaluate patient satisfaction after total elbow replacement. A combination of distribution-based methods (standard deviation [SD] of change in the LES, standard error of mean, smallest detectable change [SDC]) and anchor-based methods (receiver operating curve, difference of mean of change in LES) was used to determine range of MCID values. RESULTS: The mean change in the LES value was 2.4 (SD, 2.1). The estimated SDC value with upper limit of 90% confidence interval was 1.5. The mean change in LES of "satisfied" and "somewhat satisfied" patient groups was 2.4 (SD, 2.1) and 1.1 (SD, 1.4), respectively, and the difference between both means (MCID based on difference of mean in 2 subgroups) was 1.3. According to receiver operating curve analysis, the value of MCID was 1.6. CONCLUSION: The MCID value for the LES was estimated to range between 0.7 and 1.8. The estimated SDC value was 1.5. We propose that the "true" MCID value of the LES would be between 1.6 and 1.8 to ensure that the value is higher than the measurement error of the LES.

A2 Milk Enhances Dynamic Muscle Function Following Repeated Sprint Exercise, a Possible Ergogenic Aid for A1-Protein Intolerant Athletes?

Hyperaminoacidemia following ingestion of cows-milk may stimulate muscle anabolism and attenuate exercise-induced muscle damage (EIMD). However, as dairy-intolerant athletes do not obtain the reported benefits from milk-based products, A2 milk may offer a suitable alternative as it lacks the A1-protein. This study aimed to determine the effect of A2 milk on recovery from a sports-specific muscle damage model. Twenty-one male team sport players were allocated to three independent groups: A2 milk (n = 7), regular milk (n = 7), and placebo (PLA) (n = 7). Immediately following muscle-damaging exercise, participants consumed either A2 milk, regular milk or PLA (500 mL each). Visual analogue scale (muscle soreness), maximal voluntary isometric contraction (MVIC), countermovement jump (CMJ) and 20-m sprint were measured prior to and 24, 48, and 72 h post EIMD. At 48 h post-EIMD, CMJ and 20-m sprint recovered quicker in A2 (33.4 ± 6.6 and 3.3 ± 0.1, respectively) and regular milk (33.1 ± 7.1 and 3.3 ± 0.3, respectively) vs. PLA (29.2 ± 3.6 and 3.6 ± 0.3, respectively) (p < 0.05). Relative to baseline, decrements in 48 h CMJ and 20-m sprint were minimised in A2 (by 7.2 and 5.1%, respectively) and regular milk (by 6.3 and 5.2%, respectively) vs. PLA. There was a trend for milk treatments to attenuate decrements in MVIC, however statistical significance was not reached (p = 0.069). Milk treatments had no apparent effect on muscle soreness (p = 0.152). Following muscle-damaging exercise, ingestion of 500 mL of A2 or regular milk can limit decrements in dynamic muscle function in male athletes, thus hastening recovery and improving subsequent performance. The findings propose A2 milk as an ergogenic aid following EIMD, and may offer an alternative to athletes intolerant to the A1 protein.

A randomized controlled trial of a group-based gaze training intervention for children with Developmental Coordination Disorder.

The aim of this study was to integrate a gaze training intervention (i.e., quiet eye training; QET) that has been shown to improve the throwing and catching skill of children with Developmental Coordination Disorder (DCD), within an approach (i.e., group therapy) that might alleviate the negative psychosocial impact of these motor skill deficits. Twenty-one children with DCD were split into either QET (8 male 3 female, mean age of 8.6 years (SD = 1.04) or technical training (TT) groups (7 male 3 female, mean age of 8.6 years (SD = 1.84). The TT group were given movement-related instructions via video, relating to the throw and catch phases, while the QET group were also taught to fixate a target location on the wall prior to the throw (QE1) and to track the ball prior to the catch (QE2). Each group partook in a 4-week, group therapy intervention and measurements of QE duration and catching performance were taken before and after training, and at a 6-week delayed retention test. Parental feedback on psychosocial and motor skill outcomes was provided at delayed retention. Children improved their gaze control and catching coordination following QET, compared to TT. Mediation analysis showed that a longer QE aiming duration (QE1) predicted an earlier onset of tracking the ball prior to catching (QE2) which predicted catching success. Parents reported enhanced perceptions of their child's catching ability and general coordination in the QET group compared to the TT group. All parents reported improvements in their child's confidence, social skills and predilection for physical activity following the trial. The findings offer initial support for an intervention that practitioners could apply to address deficits in the motor and psychosocial skills of children with DCD. TRIAL REGISTRATION: ClinicalTrials.gov NCT02904980.

Electromyographic assessment of forearm muscle function in tennis players with and without Lateral Epicondylitis.

There is no consensus about the main aetiology of Lateral Epicondylitis (LE) or Tennis Elbow. While electromyographic assessment of alterations in neuromuscular control and activation patterns of forearm muscles has received increasing interest as potential intrinsic factors in non-tennis players, there has been insufficient attention in tennis players. The purpose of present review was to search the literature for the electromyographic studies of forearm muscles in tennis players in order to (1) identify related implications for LE, (2) highlight key technical and methodological shortcomings, and (3) suggest potential pathways for future research. An electronic search of PubMed, Scopus, Web of Science, and Google Scholars (1980 to October 2014) was conducted. Titles, abstracts, and full-text articles were screened to identify "peer-reviewed" studies specifically looking into "electromyographic assessment of forearm muscles" in "tennis players". After screening 104 articles, 13 original articles were considered in the main review involving a total of 216 participants (78% male, 22% female). There were indications of increased wrist extensor activity in all tennis strokes and less experienced single-handed players, however with insufficient evidence to support their relationship with the development of LE. Studies varied widely in study population, sample size, gender, level of tennis skills, electrode type, forearm muscles studied, EMG recording protocol, EMG normalisation method, and reported parameters. As a result, it was not possible to present combined results of existing studies and draw concrete conclusions in terms of clinical implications of findings. There is a need for establishment of specific guidelines and recommendations for EMG assessment of forearm musculature particularly in terms of electrode and muscle selection. Further studies of both healthy controls and tennis players suffering from LE with adequate sample sizes and well-defined demographics are warranted.

ELECTROMYOGRAPHIC ANALYSIS OF SHOULDER GIRDLE MUSCLES DURING COMMON INTERNAL ROTATION EXERCISES.

BACKGROUND: High level throwing performance requires the development of effective muscle activation within shoulder girdle muscles particularly during forceful internal rotation (IR) motions. STUDY DESIGN: Controlled Laboratory Descriptive Study. PURPOSE: To investigate activation pattern of 16 shoulder girdle muscles/muscle sub-regions during three common shoulder IR exercises. METHODS: EMG was recorded in 30 healthy subjects from 16 shoulder girdle muscles/muscle sub-regions (surface electrode: anterior, middle and posterior deltoid, upper, middle and lower trapezius, serratus anterior, teres major, upper and lower latissimus dorsi, upper and lower pectoralis major; fine wire electrodes: supraspinatus, infraspinatus, subscapularis and rhomboid major) using a telemetric EMG system. Three IR exercises (standing IR at 0° and 90° of Abduction, and IR at Zero-Position) were studied. EMG amplitudes were normalized to EMGmax (EMG at maximal IR force in a standard position) and compared using one-way repeated-measures analysis of variance (ANOVA). RESULTS: There were significant differences in muscles' activation across IR exercises (p<0.05-p<0.001). Rotator cuff and deltoid muscles were highly activated during IR at 90° of Abduction. Latissimus dorsi exhibited markedly higher activation during IR at Zero-Position. While upper trapezius had the highest activation during IR at Zero-Position, middle and lower trapezius were activated at highest during IR at 90° of Abduction. The highest activation of serratus anterior and rhomboid major occurred in IR at Zero-Position and IR at 90° of Abduction, respectively. CONCLUSIONS: Studied exercises have the potential to effectively activate glenohumeral and scapular muscles involved in throwing motions. Results provide further evidence for developing rehabilitation, injury prevention, and training strategies. LEVEL OF EVIDENCE: 4, Controlled laboratory study.

Electromyographic Analysis of the Shoulder Girdle Musculature During External Rotation Exercises.

BACKGROUND: Implementation of overhead activity, a key component of many professional sports, requires an effective and balanced activation of the shoulder girdle muscles, particularly during forceful external rotation (ER) motions. PURPOSE: To identify activation strategies of 16 shoulder girdle muscles/muscle segments during common shoulder ER exercises. STUDY DESIGN: Descriptive laboratory study. METHOD: Thirty healthy subjects were included in this study, and 16 shoulder girdle muscles/muscle segments were investigated (surface electrode: anterior, middle, and posterior deltoid; upper, middle, and lower trapezius; serratus anterior; teres major; upper and lower latissimus dorsi; and upper and lower pectoralis major; fine wire electrodes: supraspinatus, infraspinatus, subscapularis, and rhomboid major) using a telemetric electromyography (EMG) system. Five ER exercises (standing ER at 0° and 90° of abduction, with underarm towel roll, prone ER at 90° of abduction, side-lying ER with underarm towel) were studied. Exercise EMG amplitudes were normalized to EMG at maximum ER force in a standard position. Univariate analysis of variance and post hoc analysis applied on EMG activity of each muscle were used to assess the main effect of the exercise condition. RESULTS: Muscular activity differed significantly among the ER exercises (P < .05 to P < .001). The greatest activation for anterior and middle deltoid, supraspinatus, upper trapezius, and serratus anterior occurred during standing ER at 90° of abduction; for posterior deltoid, middle trapezius, and rhomboid during side-lying ER with underarm towel; for lower trapezius, upper and lower latissimus dorsi, subscapularis, and teres major during prone ER at 90° of abduction; and for the clavicular and sternal part of the pectoralis major during standing ER with underarm towel. CONCLUSION: Key glenohumeral and scapular muscles can be optimally activated during specific ER exercises, particularly in positions that stimulate athletic overhead motions. CLINICAL RELEVANCE: These results enable sports medicine professionals to target specific muscles during shoulder rehabilitation protocols while minimizing the effect of others, providing a foundation for optimal evidence-based exercise prescription. They also provide information for tailored muscle training and injury prevention in overhead sports.

Normal shoulder muscular activation and co-ordination during a shoulder elevation task based on activities of daily living: an electromyographic study.

Studies of normal shoulder function have often failed to consider the inter-relationship between different muscle groups in activities relevant to daily life. Upper limb functional status was assessed in 12 healthy male volunteers using the Functional Impairment Test-Hand, Neck, Shoulder and Arm test (FIT-HaNSA). Electromyography was then used to study the activity and coordination of 13 muscles (10 by surface electrodes, 3 by fine-wire intramuscular electrodes) around the shoulder during a dynamic movement task based on the shelf-lifting task in FIT-HaNSA. Muscles were grouped for analysis into deltoid (anterior, middle, and posterior divisions), adductors (latissimus dorsi and teres major), rotator cuff (supraspinatus, infraspinatus, and subscapularis), and elbow flexor (brachioradialis, biceps brachii) groups. There were no significant inter-session effects. Using cross-correlation analysis to investigate the whole time-course of activation, there were highly significant positive correlations (p < 0.001) between the deltoid and rotator cuff, the deltoid and adductor and the adductor and rotator cuff groups, and a significant negative correlation between the deltoid and elbow flexor groups (p = 0.031). We conclude that the deltoid, adductor, and rotator cuff muscles all contribute to the muscular component of glenohumeral joint stability. Muscular stability can be adapted as required to meet task-specific demands.

Shoulder muscle activation and coordination in patients with a massive rotator cuff tear: an electromyographic study.

Adaptive muscle activation strategies following a massive rotator cuff tear (MRCT) are inadequately understood, and the relationship among muscles during everyday activities has not been considered. Thirteen healthy subjects comprised the control group, and 11 subjects with a MRCT the patient group. Upper limb function was assessed using the Functional Impairment test-hand, neck, shoulder, and arm (FIT-HaNSA). Electromyography (EMG) was recorded from 13 shoulder muscles, comprising five muscle groups, during a shelf-lifting task. Mean FIT-HaNSA scores were significantly lower in MRCT patients (p≤0.001), reflecting a severe functional deficit. In MRCT patients, EMG signal amplitude was significantly higher for the biceps brachii-brachioradialis (p < 0.001), upper trapezius-serratus anterior (p= 0.025), muscle groups and for the latissimus dorsi (p = 0.010), and teres major (p=0.007) muscles. No significant differences in the correlation among muscle groups were identified, pointing to an unchanged neuromuscular strategy following a tear. In MRCT patients, a reorganization of muscle activation strategy along the upper limb kinetic chain is aimed at reducing demand on the glenohumeral joint. Increased activation of the latissimus dorsi and teres major muscles is an attempt to compensate for the deficient rotator cuff. Re-education towards an alternate neuromuscular control strategy appears necessary to restore function.

Assessment of functional recovery in tennis elbow.

OBJECTIVES: (a) To investigate changes in muscular strength, fatigue and activity in recovered tennis elbow (RTE); (b) to assess the appropriateness of EMG and strength measurements in monitoring functional recovery in tennis elbow (TE). METHODS: Study included three age-matched female groups of Control (C) (n=8, no history of musculoskeletal problems), TE (n=7, local tenderness at the lateral epicondyle and pain with resisted wrist and middle finger extension) and RTE (n=6, asymptomatic for at least 6 months, no lateral epicondyle tenderness). Measurements included metacarpophalangeal (MCP), wrist, shoulder and grip isometric strength and EMG measures of muscle fatigue and activity for five forearm muscles (wrist extensors and flexors). RESULTS: Strength was greater (p<0.05) for all measurements in C compared to RTE and TE except for MCP extension. Only MCP extension was stronger in RTE than TE. EMG revealed increased activity of extensor carpi radialis (ECR) in RTE, decreased in TE. CONCLUSIONS: Despite attenuation of pain, global upper limb weakness in RTE indicated incomplete functional recovery. Increased strength of MCP extension may protect weakened wrist extensors from further injury. Monitoring the ECR activity as well as strength measurements may provide a useful assessment of functional recovery in TE.

Upper limb muscle imbalance in tennis elbow: a functional and electromyographic assessment.

The purpose of this study was to investigate strength, fatigability, and activity of upper limb musculature to elucidate the role of muscular imbalance in the pathophysiology of tennis elbow. Sixteen patients clinically diagnosed with tennis elbow, recruited from a university hospital upper limb orthopedic clinic, were compared with 16 control subjects with no history of upper limb musculoskeletal problem, recruited from university students and staff. Muscle strength was measured for grip, metacarpophalangeal, wrist, and shoulder on both sides. Electromyographic activity (RMS amplitude) and fatigue characteristics (median frequency slope) of five forearm and two shoulder muscles were measured during isometric contraction at 50% maximum voluntary contraction. All strength measurements showed dominance difference in C, but none in TE. In tennis elbow compared to controls, hand/wrist and shoulder strength and extensor carpi radialis (ECR) activity were reduced (p < 0.05), while fatigue was normal. A global upper limb weakness exists in tennis elbow. This may be due to disuse and deconditioning syndrome caused by fear avoidance, and needs to be addressed in prevention and treatment. Activation imbalance among forearm muscles (reduced extensor carpi radialis activity) in tennis elbow, probably due to protective pain-related inhibition, could lead to a widespread upper limb muscle imbalance.