Pelvic Tilt in Adults With Cerebral Palsy and Its Relationship With Prior Hamstrings Lengthening.

BACKGROUND: Current studies assessing the change in pelvic tilt for ambulatory patients with cerebral palsy (CP) after surgical hamstring lengthening (SHL) lack a comparison cohort without prior SHL and are limited to younger patients. This study presents gait data of middle-aged adults with CP, primarily focusing on the pelvis, and compares pelvic tilt, trunk tilt, and knee flexion between those with and without prior SHL. MATERIALS AND METHODS: A consecutive series of 54 adults with CP, a mean age of 36±13 years, and Gross Motor Function Classification System (GMFCS) levels I-III were included. Thirty-two (59%) had SHL performed at a mean age of 8±5 years. Three-dimensional gait analysis data prospectively collected at a mean of 28±14 years postoperatively were retrospectively analyzed. Chi-square tests were used to compare demographic and surgical history data and statistical parameter mapping was used to compare knee flexion during stance and pelvic and trunk tilts during the gait cycle between SHL and SHL-naive groups. RESULTS: Age, GMFCS level, sex, race, topography, and ethnicity were not different between the groups (P=.217-.612). Anterior pelvic tilt throughout gait was significantly greater in the SHL group compared with the SHL-naive group (63%-87%; P=.033). This difference was augmented after accounting for other surgical history and revision SHL (0%-32%, P=.019; and 46%-93%, P=.007). CONCLUSION: Within a cohort of adults with CP, GMFCS levels I-III, and a mean age of 36 years, those with a history of SHL, performed a mean of 28 years prior to 3-dimensional gait analysis, walked with increased anterior pelvic tilt compared with those without a history of SHL. [Orthopedics. 2024;47(5):270-275.].

Body mass affects kinetic symmetry and inflammatory markers in adolescent knees during gait.

BACKGROUND: Early-onset osteoarthritis has been attributed to pro-inflammatory factors and biomechanical changes in obesity. However, research has yet to explore whether knee joint moments are asymmetrical in children with obesity and could precede the onset of knee osteoarthritis. The present study compares knee moment asymmetry between adolescents with and without obesity and examines the relationship between asymmetries and inflammatory biomarkers. METHODS: Twenty-eight adolescents (13-16 years) were classified as with (n = 12) or without (n = 16) obesity. Lower extremity kinetics were measured using three-dimensional motion analysis. Bilateral knee joint moments were analyzed in the sagittal, frontal, and transverse planes across stance phase. Kinetic asymmetry was calculated between the right and left sides and represented by the R2 value. Enzyme-linked immunosorbent assays analyzed serum 25-hydroxy vitamin D, interferon gamma, tumor nercrosis factor alpha, interleukin-6, and C-reactive protein levels. Parametric and non-parametric tests determined significant group differences in asymmetries and biomarkers, respectively. Spearman's correlations identified relationships between biomarkers and asymmetries with statistically significant group differences. FINDINGS: Adolescents with obesity had greater sagittal (loading, midstance) and frontal (midstance, pre-swing) plane kinetic knee asymmetry and higher concentrations of interleukin-6 and C-reactive protein. A moderately negative correlation existed between C-reactive protein and sagittal (loading, midstance) plane asymmetry, and also between interleukin-6 and frontal (pre-swing) plane asymmetry. INTERPRETATION: Inflammatory response increases with greater knee joint asymmetry, suggesting knee joint damage and altered joint loading co-exist in adolescents with obesity. Increased risk to joint health may exist in sub-phases where knee joints are improperly loaded.

Dynamic Assessment of Femoroacetabular Impingement Syndrome Hips.

PURPOSE: The purpose of our study was to compare lower extremity rotational kinematics and kinetics (angles, torques, and powers) and hip muscle electromyography (EMG) activity between cam-type femoroacetabular impingement syndrome (FAIS) and age- and sex-matched controls during walking, fast walking, stair ascent, stair descent, and sit-to-stand. METHODS: This study included 10 males with unilateral FAIS and 10 control males with no FAIS. We measured kinematics, kinetics, and electromyographic signals during stair ascent/descent, sit-to-stand, self-selected walk, and fast walk. Peak signal differences between groups were compared with independent t-tests with statistical significance when P < .05. RESULTS: FAIS hips showed significant differences compared to controls, including increased hip flexion during walking (+4.9°, P = .048) and stair ascent (+7.8°, P =.003); diminished trunk rotation during stair ascent (-3.4°; P = .015), increased knee flexion during self-selected walking (+5.1°, P = .009), stair ascent (+7.4°, P = .001), and descent (+5.3°, P = .038); and increased knee valgus during fast walking (+4.7°, P = .038). gMed and MedHam showed significantly decreased activation in FAIS during walking (gMed: -12.9%, P = .002; MedHam: -7.4%, P = .028) and stair ascent (gMed: -16.7%, P = .036; MedHam: -13.0%, P = .041); decreased gMed activation during sit-to-stand (-8.8%, P = .004) and decreased MedHam activation during stair descent (-8.0%, P = .039). CONCLUSIONS: Three-dimensional motion analysis and EMG evaluation of functional kinematics and kinetics in subjects with symptomatic unilateral cam-type FAIS across a spectrum of provocative tasks demonstrated significant differences compared to controls in hip flexion, trunk rotation, knee flexion, and valgus. FAIS hips had significantly decreased gMed and MedHam activity. These findings may explain altered torso-pelvic, hip, and knee mechanics in FAIS patients and suggest that evaluation of FAIS should include the patient's hip, knee, and torso-pelvic relationships and muscle function. CLINICAL RELEVANCE: The clinical and functional manifestation of FAIS hip pathomechanics is not entirely understood, and previous literature to date has not clearly described the alterations in gait and functional movements seen in patients with cam-type FAIS. The current study used 3D motion analysis and EMG evaluation of functional kinematics and kinetics to identify a number of differences between FAIS and control hips, which help us better understand the lower extremity kinematics and kinetics and muscle activation in FAIS.

Differences in Gait and Stair Ascent After Total Ankle Arthroplasty and Ankle Arthrodesis.

BACKGROUND: Ankle arthrodesis has historically been the standard of care for end-stage ankle arthritis; however, total ankle arthroplasty (TAA) is considered a reliable alternative. Our objective was to compare 3-dimensional foot and ankle kinetics and kinematics and determine the ankle power that is generated during level walking and stair ascent between TAA and ankle arthrodesis patients. METHODS: Ten patients who underwent TAA with a modern fixed-bearing ankle prosthesis and 10 patients who previously underwent ankle arthrodesis were recruited. Patients were matched for age, sex, body mass index, time from surgery, and preoperative diagnosis. A minimum of 2-year follow-up was required. Patients completed instrumented 3D motion analysis while walking over level ground and during stair ascent. Between-group differences were assessed with a 2-tailed Mann-Whitney exact test for 2 independent samples. RESULTS: Sagittal ankle range of motion (ROM) was significantly higher in the TAA group (21.1 vs 14.7 degrees, P = .003) during level walking. In addition, forefoot-tibia motion (25.3±5.9 degrees vs 18.6±5.1 degrees, P = .015) and hindfoot-tibia motion (15.4±3.2 degrees vs 12.2±2.5 degrees, P = .022) were significantly greater in the TAA group. During stair ascent, sagittal ankle ROM (25 vs 17.1 degrees, P = .026), forefoot-tibia motion (27.6 vs 19.6 degrees, P = .017), and hindfoot-tibia motion (16.8 vs 12 degrees, P = .012) was greater. CONCLUSION: There were significant differences during level walking and stair ascent between patients with TAA and ankle arthrodesis. TAA patients generated greater peak plantarflexion power and sagittal motion within the foot and ankle compared to patients with an ankle arthrodesis. Further investigation should continue to assess biomechanical differences in the foot and ankle during additional activities of daily living. LEVEL OF EVIDENCE: Level III, comparative study.

Changes in Lower Extremity Kinematics and Temporal Parameters of Adolescent Baseball Pitchers During an Extended Pitching Bout.

BACKGROUND: Few studies have investigated detailed 3-dimensional lower extremity kinematics during baseball pitching in adolescent athletes during extended play. Changes in these parameters may affect performance outcomes. PURPOSE: To investigate whether adolescent baseball pitchers experience changes in lower extremity kinematics and event timing during a simulated game-length pitching bout. STUDY DESIGN: Descriptive laboratory study. METHODS: Twelve male adolescent pitchers (aged 14-16 years) threw 6 sets of 15 fastball pitches from an artificial pitching mound to a target at regulation distance. Joint angles and angular velocities at the hip, knee, and ankle of both legs were collected throughout the phases of the pitching cycle as well as stride length, pelvis orientation, pitch duration, timing of foot contact and ball release, ball speed, and pitching accuracy. Paired t tests ( P < .05) were used to compare the dependent variables between the last 5 pitches of the second (baseline) and sixth (final) sets. RESULTS: During the stride phase, decreased maximum angular excursions for hip extension (baseline: 14.7° ± 9.8°; final: 11.6° ± 10.3°; P < .05) and ankle plantar flexion (baseline: 30.2° ± 14.5°; final: 24.2° ± 15.3°; P < .05) as well as maximum angular velocity for knee extension (baseline: 144.9 ± 63.3 deg·s-1; final: 121.7 ± 62.0 deg·s-1; P < .05) were observed between sets in the trailing leg. At foot contact, pitchers had decreased hip flexion (baseline: 69.5° ± 10.1°; final: 66.5° ± 11.8°; P < .05) and increased hip abduction (baseline: 20.7° ± 8.9°; final: 25.4° ± 6.0°; P < .05) in the leading leg in the final set. Compared with the baseline set, ball speed significantly decreased in the final set (29.5 ± 2.5 m·s-1 vs 28.3 ± 2.5 m·s-1, respectively; P < .05). CONCLUSION: Kinematic changes and decreased ball speeds observed in the final set suggest that adolescent pitchers are unable to maintain lower extremity kinematics and performance as a result of extended play. CLINICAL RELEVANCE: The results from this study may warrant further investigation into how altered lower extremity kinematics may affect trunk and upper extremity function, performance, and risk of injuries during pitching in adolescent athletes, particularly during actual game play.

Surgical Treatments for Scapholunate Advanced Collapse Wrist: Kinematics and Functional Performance.

PURPOSE: The purpose of this investigation was to compare kinematic motion and functional performance during 2 tasks in patients following 4-corner fusion (4CF) or proximal row carpectomy (PRC) and to compare these data with those from healthy asymptomatic individuals. METHODS: Twenty men (10 4CFs and 10 PRCs, ages, 43-82 y) were recruited for 3-dimensional wrist motion analysis testing. Kinematic coupling (the ratio of wrist flexion/extension to radial-ulnar deviation), kinematic path length (a measure of total angle distance), clinical measures, and performance measures were collected during 2 tasks: dart throwing and hammering. For each outcome, between-group comparisons employed a 1-way analysis of variance with post hoc analysis using the Fisher least significant difference test. RESULTS: All clinical measures (flexion-extension, radial-ulnar deviation, and grip strength) were decreased for 4CF and PRC patients compared with healthy subjects. Coupling, kinematic path length, and performance were all significantly reduced in 4CF and PRC patients compared with healthy subjects during both tasks. Reduced coupling and a shorter kinematic path length are indicative of less global and combined wrist motion. There were no differences identified in coupling patterns or performance between the surgical groups for the dart-throwing task. However, in hammering, the kinematic path length and performance (time and total strikes) were worse in 4CF than in PRC. CONCLUSIONS: Differences in wrist kinematics and performance were identified between the groups. PRC subjects performed better on kinematic and performance variables. As expected, both groups demonstrated decreased wrist kinematic motion and functional performance compared with individuals with normal wrists. These results require confirmation and while they cannot be used to determine the benefits of one procedure over the other, they are an important step in quantifying differences in motion and function between procedures. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic II.

The functional effect of a distal rectus femoris tenotomy in adults with cerebral palsy.

The purpose of this study was to determine the effect of a distal rectus femoris tenotomy on function and gait in adults with cerebral palsy who had diminished knee flexion during swing. A stiff knee gait pattern is commonly seen in individuals with cerebral palsy and frequently leads to tripping and falling. Five subjects, 25-51 years, (34.6±10.3 years) participated in the study; each individual had the surgery after the age of 18. Four of the five subjects underwent bilateral distal rectus femoris tenotomies for a total of nine limbs being studied. Four of the five subjects had a single procedure of a distal rectus femoris tenotomy and one subject also had bilateral adductor tenotomies. All individuals underwent a pre-operative and post-operative, (3.28±1.6 years) three-dimensional gait analysis. Pre-operative gait revealed diminished peak knee flexion and out of phase rectus femoris activity with a quiet vastus lateralis during swing in all subjects. Significant findings after a distal rectus femoris tenotomy included: improved peak swing knee flexion, improved peak stance hip extension, and increased total knee excursion without loss in knee extension strength. During swing, knee flexion angle improved on average 11° which correlated with subjective report of less shoe wear, tripping, and falling due to improved clearance. In conclusion, a distal rectus femoris tenotomy should be considered a surgical option for adults with cerebral palsy and a stiff knee gait pattern to improve mobility, function, and quality of life.

Development of an anatomical wrist joint coordinate system to quantify motion during functional tasks.

The purpose of this study was to develop a three-dimensional (3D) motion analysis based anatomical wrist joint coordinate system for measurement of in-vivo wrist kinematics. The convergent validity and reliability of the 3D motion analysis implementation was quantified and compared with manual and electrogoniometry techniques on 10 cadaveric specimens. Fluoroscopic measurements were used as the reference. The 3D motion analysis measurements (mean absolute difference [MAD] = 3.6°) were significantly less different (P < .005) than manual goniometry (MAD = 5.7°) but not (P = .066, power = 0.45) electrogoniometry (MAD = 5.0°) compared with fluoroscopy. The intraclass correlation coefficient (ICC[2,1]) was highest for 3D motion analysis compared with manual and electrogoniometry, suggesting better reliability for this technique. To demonstrate the utility of this new wrist joint coordinate system, normative data from 10 healthy subjects was obtained while throwing a dart.

Effect of shoe flexibility on plantar loading in children learning to walk.

BACKGROUND: In a previous pilot study of "cruisers" (nonindependent ambulation), "early walkers" (independent ambulation for 0-5 months), and "experienced walkers" (independent ambulation for 6-12 months), developmental age significantly affected the children's stability when walking and performing functional activities. We sought to examine how shoe structural characteristics affect plantar pressure distribution in early walkers. METHODS: Torsional flexibility was evaluated in four shoe designs (UltraFlex, MedFlex, LowFlex, and Stiff based on decreasing relative flexibility) with a structural testing machine. Plantar pressures were recorded in 25 early walkers while barefoot and shod at self-selected walking speeds. Peak pressure was calculated over ten masked regions for the barefoot and shod conditions. RESULTS: Torsional flexibility, the angular rotation divided by the applied moment about the long axis of the shoe, was different across the four shoe designs. As expected, UltraFlex was the most flexible and Stiff was the least flexible. As applied moment increased, torsional flexibility decreased in all footwear. When evaluating early walkers during gait, peak pressure was significantly different across shoe conditions for all of the masked regions. The stiffest shoe had the lowest peak pressures and the most flexible shoe had the highest. CONCLUSIONS: It is likely that increased shoe flexibility promoted greater plantar loading. Plantar pressures while wearing the most flexible shoe are similar to those while barefoot. This mechanical feedback may enhance proprioception, which is a desirable attribute for children learning to walk.

Foot Type Biomechanics Part 2: are structure and anthropometrics related to function?

BACKGROUND: Many foot pathologies are associated with specific foot types. If foot structure and function are related, measurement of either could assist with differential diagnosis of pedal pathologies. HYPOTHESIS: Biomechanical measures of foot structure and function are related in asymptomatic healthy individuals. METHODS: Sixty-one healthy subjects' left feet were stratified into cavus (n=12), rectus (n=27) and planus (n=22) foot types. Foot structure was assessed by malleolar valgus index, arch height index, and arch height flexibility. Anthropometrics (height and weight), age, and walking speed were measured. Foot function was assessed by center of pressure excursion index, peak plantar pressure, maximum force, and gait pattern parameters. Foot structure and anthropometric variables were entered into stepwise linear regression models to identify predictors of function. RESULTS: Measures of foot structure and anthropometrics explained 10-37% of the model variance (adjusted R(2)) for gait pattern parameters. When walking speed was included, the adjusted R(2) increased to 45-77% but foot structure was no longer a factor. Foot structure and anthropometrics predicted 7-47% of the model variance for plantar pressure and 16-64% for maximum force parameters. All multivariate models were significant (p<0.05), supporting acceptance of the hypothesis. DISCUSSION AND CONCLUSION: Foot structure and function are related in asymptomatic healthy individuals. The structural parameters employed are basic measurements that do not require ionizing radiation and could be used in a clinical setting. Further research is needed to identify additional predictive parameters (plantar soft tissue characteristics, skeletal alignment, and neuromuscular control) and to include individuals with pathology.

A spectral analysis of rotator cuff musculature electromyographic activity: surface and indwelling.

Electromyography (EMG) of the shoulder girdle is commonly performed; however, EMG spectral properties of shoulder muscles have not been clearly defined. The purpose of this study was to determine the maximum power frequency, Nyquist rate, and minimum sampling rate for indwelling and surface EMG of the normal shoulder girdle musculature. EMG signals were recorded using indwelling electrodes for the rotator cuff muscles and surface electrodes for ten additional shoulder muscles in ten healthy volunteers. A fast Fourier transform was performed on the raw EMG signal collected during maximal isometric contractions to derive the power spectral density. The 95% power frequency was calculated during the ramp and plateau subphase of each contraction. Data were analyzed with analysis of variance (ANOVA) and paired t tests. Indwelling EMG signals had more than twice the frequency content of surface EMG signals (p < .001). Mean 95% power frequencies ranged from 495 to 560 Hz for indwelling electrodes and from 152 to 260 Hz for surface electrodes. Significant differences in the mean 95% power frequencies existed among muscles monitored with surface electrodes (p = .002), but not among muscles monitored with indwelling electrodes (p = .961). No significant differences in the 95% power frequencies existed among contraction subphases for any of the muscle-electrode combinations. Maximum Nyquist rate was 893 Hz for surface electrodes and 1,764 Hz for indwelling electrodes. Our results suggest that when recording EMG of shoulder muscles, the minimum sampling frequency is 1,340 Hz for surface electrodes and 2,650 Hz for indwelling electrodes. The minimum sampling recommendations are higher than the 1,000 Hz reported in many studies involving EMG of the shoulder.

Mini-midvastus vs standard medial parapatellar approach: a prospective, randomized, double-blinded study in patients undergoing bilateral total knee arthroplasty.

The purpose of this study was to determine whether the mini-midvastus approach to total knee arthroplasty (TKA) results in differences in quadriceps muscle strength as well as previously cited advantages in a double blind prospective randomized trial. Twenty-seven patients (54 TKAs) scheduled for bilateral TKA were randomized to undergo mini-midvastus approach on one knee and standard approach on the other. Incision lengths were the same. Postoperative strength was determined by isokinetic and isometric peak torque testing. Range of motion, pain Visual analog scale, side-preference, and gait analysis were assessed preoperatively and postoperatively. The only significant difference in strength testing was increased isokinetic and isometric extension torque at 3 weeks postoperatively for the mini-midvastus approach. No differences between the mini-midvastus and standard approach were observed for stride length, stance time, pain Visual analog scale, or knee range of motion. The mini-midvastus approach has limited benefit compared to the standard approach for TKA.

Subacromial injection improves deltoid firing in subjects with large rotator cuff tears.

Previous studies demonstrate that scapulohumeral mechanics improve after subacromial injection. However, it is unclear how injection affects muscle firing. Forty-one subjects with two-tendon rotator cuff tears and 23 volunteer subjects with normal rotator cuffs documented by ultrasonography were examined. Electromyographic activity from 12 muscles was collected during ten functional tasks. Nine symptomatic subjects with rotator cuff tears underwent subacromial injection of anesthetic and underwent repeat electromyographic examination. Subjects with rotator cuff tears demonstrate global electromyographic differences when compared to normal controls. Asymptomatic subjects with rotator cuff tears had significantly increased anterior deltoid firing when compared to symptomatic counterparts during forward shoulder elevation. After subacromial injection, symptomatic subjects demonstrate increased anterior deltoid firing. Previous in vitro and in vivo studies have suggested that pain leads to deltoid inhibition and that subacromial injection leads to improved deltoid firing and, subsequently, improved shoulder function. This study provides direct evidence that subacromial injection improves deltoid firing in symptomatic subjects with rotator cuff tears. These findings reinforce the concept that deltoid inhibition resulting from pain is an important component of the motor disability associated with rotator cuff tears.

Accuracy and reliability of three different techniques for manual goniometry for wrist motion: a cadaveric study.

PURPOSE: Despite the ubiquitous use of manual goniometry in measuring objective outcomes of hand surgery and therapy, there are limited data concerning its accuracy or repeatability for wrist motion. The purpose of this study was to evaluate the accuracy and reliability (both inter- and intra-rater) in measuring wrist flexion and extension using 3 manual goniometric alignment techniques (ulnar, radial, and dorsal-volar) in cadaveric upper extremities, using fluoroscopic verification of posture as a gold standard. In addition, we sought to assess the accuracy and reliability of the dorsal-volar technique for measurement of radioulnar deviation. METHODS: External fixators were applied to 10 cadaveric wrists with intramedullary cannulated rods in the radius and third metacarpal for gold-standard fluoroscopic verification of posture. Manual goniometric measurements with each technique were captured by 2 raters (a hand surgeon and a hand therapist) for reliability measurements and by a single rater for accuracy. Wrists were positioned at angles of maximum flexion, extension, and radial and ulnar deviation for reliability testing and at preselected angles across the range of motion for accuracy testing. At each position, wrist angle was measured with a 1 degrees increment goniometer, and fluoroscopic angles were measured digitally. Intraclass correlation coefficients and root mean square values were calculated for all combinations, and analysis of variance was used to test differences between techniques. RESULTS: No technique was statistically less accurate than any other (6 degrees to 7 degrees ). Each method was found to have high intra-rater reliability. For measurement of wrist flexion and extension, the dorsal-volar technique demonstrated the greatest inter-rater reliability, as compared to ulnar and radial, respectively. CONCLUSIONS: Although each measurement technique demonstrated a similar degree of accuracy and intra-rater reliability, the dorsal-volar technique demonstrates the greatest level of inter-rater reliability for measurement of wrist flexion and extension. This information is important clinically, as measurements are regularly exchanged between hand surgeons and therapists as a basis for decisions regarding patient care.

Lower extremity muscle activation and alignment during the soccer instep and side-foot kicks.

STUDY DESIGN: Controlled laboratory study. OBJECTIVES: To quantify phase duration and lower extremity muscle activation and alignment during the most common types of soccer kick-the instep kick and side-foot kick. A second purpose was to test the hypotheses that different patterns of lower extremity muscle activation occur between the 2 types of kicks and between the kicking limb compared to the support limb. BACKGROUND: Soccer players are at risk for lower extremity injury, especially at the knee. Kicking the soccer ball is an essential, common, and distinctive part of a soccer player's activity that plays a role in soccer player injury. Regaining the ability to kick is also essential for soccer athletes to return to play after injury. METHODS: Thirteen male soccer players underwent video motion analysis and electromyography (EMG) of 7 muscles in both the kicking and supporting lower extremity (iliacus, gluteus maximus, gluteus medius, vastus lateralis, vastus medialis, hamstrings, gastrocnemius) and 2 additional muscles in the kicking limb only (hip adductors, tibialis anterior). Five instep and 5 side-foot kicks were recorded for each player. Analysis-of-variance models were used to compare EMG activity between type of kicks and between the kicking and nonkicking lower extremity. RESULTS: Five phases of kicking were identified: (1) preparation, (2) backswing, (3) limb cocking, (4) acceleration, and (5) follow-through. Comparing the kicking limb between the 2 types of kick, significant interaction effects were identified for the hamstrings (P = .02) and the tibialis anterior (P<.01). Greater activation of the kicking limb iliacus (P<.01), gastrocnemius (P<.01), vastus medialis (P = .016), and hip adductors (P<.01) occurred during the instep kick. Significant differences were seen between the kicking limb and the support limb for all muscles during both types of kick. CONCLUSIONS: Certain lower extremity muscle groups face different demands during the soccer instep kick compared to the soccer side-foot kick. Similarly, the support limb muscles face different demands than the kicking limb during both kicks. Better definition of lower extremity function during kicking provides a basis for improved insight into soccer player performance, injury prevention, and rehabilitation.

An evaluation of accuracy and repeatability of a novel gait analysis device.

INTRODUCTION: Restoration of gait is a particularly important patient-based functional outcome following lower extremity trauma. A new portable device which measures gait parameters, the IDEEA, may be particularly useful in evaluating post-traumatic gait parameters in the office setting, but the accuracy and repeatability of this device relative to standard gait laboratory footswitches are unknown. MATERIAL AND METHODS: Twelve healthy subjects were tested simultaneously using the IDEEA device and standard gait laboratory footswitches, at slow, medium, and fast speeds. Parameters evaluated were single-limb support time (SLS), double-limb support time (DLS), swing phase duration (SPD), cycle duration, and cadence. RESULTS: The repeatability between right and left measurements tended to be better for the IDEEA, and was at least as good as the foot switches. The absolute differences of the timed gait parameters between the two devices were all in the range of 0.03 s, which is within the data sampling resolution of the gait laboratory foot switches (0.04 s). Furthermore, assuming a 1-s gait cycle, these differences account for only 3% of the gait cycle, which is also well within the clinical parameters for evaluating and differentiating between treatments. CONCLUSION: This device is accurate and repeatable, and may facilitate the evaluation of gait function in post-traumatic patients in settings outside of the traditional gait laboratory.

Differential patterns of muscle activation in patients with symptomatic and asymptomatic rotator cuff tears.

Patients with rotator cuff tears have varying degrees of symptom expression. Our purpose was to evaluate the differential firing patterns of the rotator cuff, deltoid, and scapular stabilizer muscle groups in normal control subjects and in patients with symptomatic and asymptomatic 2-tendon rotator cuff tears. Eighteen subjects were evaluated: six normal subjects and twelve with 2-tendon cuff tears (six asymptomatic and six symptomatic). All cuff tear patients had magnetic resonance imaging (MRI) scans documenting superoposterior tear configurations involving the supraspinatus and infraspinatus tendons; all normal subjects had an ultrasound examination confirming the absence of cuff pathology. Subjects were grouped based on shoulder examination and outcomes questionnaires. Asymptomatic patients had minimal pain (<3 on the visual analog scale and no loss of active range of motion compared with the contralateral side); symptomatic patients had pain greater than 3 on the visual analog scale and decreased range of motion compared with the contralateral side (>10 degrees of motion loss). Electromyographic activity from 12 muscles and kinematic data were collected simultaneously during 10 functional tasks. Both symptomatic and asymptomatic cuff subjects demonstrated a trend toward increased muscle activation during all tasks compared with normal subjects. During the internal rotation tasks, asymptomatic patients had significantly greater (P<.05) subscapularis activity than symptomatic patients (65% maximal voluntary contraction [MVC] vs 42% MVC). During the carrying task, asymptomatic patients demonstrated significantly less (P<.03) upper trapezius muscle activation than symptomatic patients (16% MVC vs 50% MVC). During shoulder elevation tasks, symptomatic patients had significantly greater supraspinatus (52% MVC vs 28% MVC, P<.03), infraspinatus (32% MVC vs 16% MVC, P<.05), and upper trapezius (39% MVC vs 20% MVC, P<.04) muscle activation compared with asymptomatic patients. During heavy elevation (8 lb), asymptomatic patients showed a trend toward increased activation (P<.06) of the subscapularis compared with symptomatic patients (34% MVC vs 21% MVC). Differential shoulder muscle firing patterns in patients with rotator cuff pathology may play a role in the presence or absence of symptoms. Asymptomatic subjects demonstrated increased firing of the intact subscapularis, whereas symptomatic subjects continued to rely on torn rotator cuff tendons and periscapular muscle substitution, resulting in compromised function.

Electromyographic activity in stiff and normal elbows during elbow flexion and extension.

This prospective, controlled pilot study investigated electromyographic activity in elbow muscles during active elbow flexion and extension and during prolonged elbow extension with and without resistance. Biceps brachii, brachialis, brachioradialis, and triceps activity was measured in 10 subjects with elbow motion deficits after injury and in 10 controls. Surface electromyography was recorded during active elbow flexion, extension, and passively positioned elbow extension with and without 3 lb on the distal forearm. All muscles of the stiff elbow group had greater activity compared with controls during active elbow flexion and extension. Biceps brachii of the stiff group showed antagonist activity equivalent to agonist. For all other flexors in both groups, agonist activity was greater than antagonist. During prolonged extension, biceps brachii, unweighted, showed greater activity in the stiff group than in controls. Both groups showed greater flexor activity when weighted. Across time, activity was sustained or increased in all muscles in both groups.

Electromyographic analysis and phase definition of the overhead football throw.

BACKGROUND: The phases of the football throw need definition so that muscle activation patterns during the overhead football throw can be fully described. HYPOTHESIS: Electromyographic analysis of shoulder musculature can better define muscle activation patterns during the football throw. STUDY DESIGN: Descriptive anatomic study. METHODS: Videos of 20 elite-level quarterbacks were reviewed to define phases of the overhead football throw; 14 recreational male athletes underwent electromyography and motion analysis testing. RESULTS: Four sequential phases of the football throw were consistently observed. Early cocking (49% +/- 11% of throw) was initiated at rear foot plant and continued to maximal shoulder abduction and internal rotation. Late cocking (20% +/- 6%) started at maximal shoulder abduction and internal rotation and ended with maximal shoulder external rotation. The acceleration phase (15% +/- 4%) began with maximal shoulder external rotation and ended with ball release. Follow-through (16% +/- 5%) was defined as the phase from ball release to maximal horizontal adduction (across the body). CONCLUSION: The four phases demonstrated little variation in motion analysis and electromyographic activation between subjects and were associated with muscle activation patterns consistent with upper extremity movements. CLINICAL RELEVANCE: A clearer understanding of muscle activation patterns may help to explain patterns of muscle injury and improve rehabilitation protocols in football-throwing athletes.

Characterization of gait function in patients with postsurgical sagittal (flatback) deformity: a prospective study of 21 patients.

STUDY DESIGN: This study prospectively analyzed gait in 21 patients with flatback and reviewed radiographs and charts. OBJECTIVE: To analyze the effect of sagittal imbalance on gait and hip and knee joints. SUMMARY OF BACKGROUND DATA: Loss of lumbar lordosis causes anterior displacement of the center of gravity, which creates instability and increases the work of gait. Several compensatory changes occur in response. The long-term effect of these changes on extra-axial joints has not been reported, nor have many studies analyzed the gait deviations in patients with flatback. Over time, as patients' ability to compensate is limited, increased gait deviations result. METHODS: A total of 21 of 44 patients who had gait analysis as part of the preoperative workup were selected based on outlined criteria. Kinetics and kinematics data were analyzed along with radiographic and chart review. Normal healthy individuals served as controls. RESULTS: Gait deviations were present in gait kinetics and kinematics, including decreased stride length and velocity, to almost 60% of controls. Stance duration was prolonged with increased hip and knee flexion during stance. Hip and knee extensor moments were decreased with vertical ground reaction force showing slower rate of loading, reduced peak values, and flattening of normal loading response. CONCLUSION: Patients with flatback develop several compensatory mechanisms. The goal of the compensation is to maintain an efficient gait and decrease joint damage, but these safeguards fail over time. Flatback not only causes backache, abnormal posture, and abnormal body mechanics but also compromises the stability of gait and taxes the knee and hip joints adversely.