Zeevi Dvir

Reproducibility and instrument validity of a new ultrasonography-based system for measuring cervical spine kinematics

OBJECTIVE To report instrument validity of CMS 70P, a new ultrasonography-based system for spatial kinematic analysis of the spine and its application in studying the reproducibility of cervical motion findings in healthy subjects. BACKGROUND Reproducibility of cervical motion has been investigated using various instruments and consisting in most cases of short test-retest time intervals of between minutes to days. METHODS Performance of the instrument was validated against a digital inclinometer, at ranges of motion compatible with actual cervical motion. To study reproducibility, 25 healthy individuals, 22 women and 3 men aged 26-48 were tested twice within an average time interval of 3.3 weeks. Performed in the seated position and at a self-determined pace, cervical motion was defined in terms of head motion relative to a sternal (reference) system, in all six primary motions: flexion, extension, right rotation, left rotation, right lateral flexion and left lateral flexion. RESULTS The system exhibited excellent agreement with the digital inclinometer, establishing its instrument validity for testing cervical motion. No significant differences were indicated between the test and retest for both the net maximal displacements and average velocities. The correlation coefficients for the single plane motions (e.g. flexion+extension) were higher than those derived for the primary motions, and ranged between 0.78 (sagittal plane) and 0.88 (frontal plane). The magnitude of the standard error of the measurement reflected the same trend with the lowest value recorded for the frontal plane. The self-selected velocity at which these motions were performed was similar in the frontal and saggital planes but was significantly higher for the transverse plane (rotations). CONCLUSIONS This study indicates that spanned over time intervals that are measured in weeks, cervical motion findings derived from the CMS 70P are well reproducible. Findings also imply the need for a more stringent control of subject positioning and stabilization. RELEVANCE Reduction of range of motion and average is typically observed in various pathologies of the cervical spine and is regarded, together with pain, as a major impairment. Therefore, valid assessment of cervical motion which is essential for follow-up and treatment outcome strongly depends on reproducibility of the findings. This study indicates that acceptable reproducibility is maintained over periods of time which are clinically meaningful using the system described herewith.

Reproducibility indices applied to cervical pressure pain threshold measurements in healthy subjects.

Objectives:To apply various statistical indices for reproducibility analysis of pressure pain threshold measurements and to derive a preferred pressure pain threshold measurement protocol based on these indices. Methods:The pressure pain threshold of 3 pairs of right and left homologous cervical region sites were measured in 20 healthy subjects (10 women, 10 men) using a hand-held pressure algometer. Measurements took place on 2 occasions (test 1 and test 2) separated by a mean interval of 1 week. On each testing session, the site-related pressure pain thresholds were measured 3 times each according to 2 different protocols. Protocol A consisted of a repetitive order, namely 3 consecutive measurements at each site before proceeding to the next, whereas protocol B consisted of an alternate order in which 3 consecutive rounds of all individually tested sites took place. For test 1, protocol A was followed by protocol B with an hour interval. For test 2, the reverse order took place. Results:The findings revealed no significant differences between the two protocols and indicated a significant rise (P < 0.0001) in the absolute scores from test 1 to test 2 in both protocols. Absolute values (mean ±SD) derived from the entire sample of pressure pain threshold sites ranged from 140 ± 60 to 198.7 ± 95 kPa (1.60 ± 0.6 to 1.99 ± 0.95 kg/cm2, respectively). No significant gender or side differences were noted. Pearson r as well as the intraclass correlation coefficient revealed good to excellent reproducibility for both protocols and for all sites measured: r = 0.79–0.94 and intraclass correlation coefficient(3,3) = 0.85–0.96, respectively. To define site-specific cutoff values indicating change at the 95% confidence level, 1.96*SEM was calculated, and its values ranged from 31.6 to 58.2 kPa, which correspond to 16.8% to 32.8% of the absolute mean values. In addition, the limits of agreement, which depict the individual test-retest differences relative to their mean, indicated a heteroscedastic trend. Discussion:The two protocols yielded very similar results. However, on the grounds of patient’s comfort and compliance as well as facility of application, protocol B stands out as the more preferred between the two.

Grade 4 in manual muscle testing: the problem with submaximal strength assessment

Objective: To compare the static moment of force required for a muscle group to support a limb segment against gravity with the maximal dynamic moment it can generate. Design: Based on anthropometric measures of both sexes and theoretical calculations, the estimated anti-gravity static muscular moments (MGM) at the shoulder, elbow, hip and knee joints were compared with published data relating to the isokinetic strength (MIM) of the same muscle groups. Results: The ratio of static to dynamic moment, MGM/MIM, was drastically higher in muscles operating on the proximal compared with the more distal joints. In women, the values of this ratio in the shoulder, hip, elbow and knee muscles were 7-27%, 5-65%, 7% and 5-10% respectively. The corresponding figures in men were 7-21 %, 4-44%, 8-10% and 5-8%. The ratios relating to the abductors, flexors and extensors of the hip joint were substantially higher in women than in men. Conclusions: Since MGM and MIM correspond to grades 3 and 5 in manual muscle testing, the findings of this theoretical analysis indicate that elbow and knee muscles assessed as having grade 4 may generate as low as 10% of their maximal strength. With regard to shoulder and hip muscles the corresponding values are typically around 20% and 30-40%. Coupled with the very limited human precision in sensing of force, these findings indicate that where quantitative targets in muscle strength conditioning are set or when an accurate measure of impairment is being sought, grade 4 cannot and should not serve as a valid criterion.

The influence of early cycling training on balance in stroke patients at the subacute stage. Results of a preliminary trial

Objective: To investigate the effect of early cycling training on balance and motor abilities of stroke patients in their subacute stage. Design: Randomized clinical trial. Setting: Inpatient rehabilitation. Subjects: Twenty-four patients who had had a first stroke were randomly assigned to a cycling training group (n = 10) or to a control (n = 14) group. Intervention: All subjects received their usual rehabilitation programme; the cycling training group received in addition a daily session of leg cycle ergometer, lasting three weeks. Both groups were followed for six weeks. Main outcome measurements: Balance was assessed using the Postural Assessment Scale for Stroke Patients (PASS) and the standing balance test. The motor function of the lower extremity was also assessed by the Fugl-Meyer Assessment (FMA). Results: In the within-group comparison, both the exercise group and the control group had improved significantly (P B=0.01) with time with respect to PASS total (exercise group 18.79=2.8 to 31.19=2.2, control group 18.19=3.2 to 26.49=3.8) and PASS subscores, as well as the FMA score (exercise group 17.29=7.5 to 29.19=5.9, control group 16.69=6.4 to 22.19=6.8). In addition there was a significant group=time interaction effect, with exercise group patients demonstrating better performance in both the total PASS score and PASS subscores and FMA score relative to the control patients (P B=0.01). Conclusions: These preliminary findings suggest that stroke patients in the subacute stage can improve their motor and balance abilities after an early short duration of cycling training.

Thigh muscle activity and anterior cruciate ligament insufficiency

The purpose of this study was to examine the dynamic relationship between the quadriceps femoris and hamstrings in anterior cruciate ligament (ACL) insufficiency. Thirty-five young active patients with an untreated complete tear of the ACL took part in the study. Using a KINCOM isokinetic dynamometer, the dynamic capacity of each muscle group at 30° in concentric and eccentric exertion in both the deficient and sound knee was measured. Findings demonstrated a significant reduction (P<0.05) in the torque produced by the deficient-side quadriceps compared to the sound side but no significant variations in the hamstring torque. Discussion of the findings considers a possible involvement of neurophysiological inhibition of the quadriceps as a cause for the observed weakness.

Muscular and Gait Abnormalities in Persons With Early Onset Multiple Sclerosis

Background and Purpose: Muscular and gait abnormalities are common complaints among persons with multiple sclerosis, even in the early stages of the disease. Our aim was to evaluate peak isometric strength, major lower limb muscle fatigue, and spatiotemporal gait parameters in persons with a first neurological event suggestive of multiple sclerosis, defined as a clinically isolated syndrome (CIS). Methods: Fifty-two individuals (36 women, 16 men) with CIS, aged 35.2 (SD = 7.2) with an Expanded Disability Status Scale score of 1.7 (SD = 1.3), participated in the study. Peak isometric torque and fatigue index were measured at the knee and ankle bilaterally as well spatiotemporal parameters of gait. Twenty-eight age- and gender-matched healthy subjects served as controls. Results: The CIS group demonstrated increased muscle fatigue, and greater ankle muscle torque asymmetries compared with the control group. The overall fatigue index scores intensified on an average of 40% in the CIS group (27% vs 19% in controls). Participants in the CIS group walked with a larger step length difference, longer step time difference, wider base of support, and prolonged double support period compared with the control group. Positive correlations were identified between double support period and some muscle parameters. Discussion and Conclusion: At this early stage of clinically isolated syndrome, evidence of a reduction in lower limb motor performance can already be identified. The possibility of early identification and potential for developing an intervention program that may alter treatment outcome warrants further exploration.

Cervical motion in patients with chronic disorders of the cervical spine: a reproducibility study.

Study Design. Test-retest of cervical motion in patients with chronic disorders of the cervical spine. Objectives. To determine the reproducibility of cervical motion and examine the feasibility of its representation by a single parameter. Summary of Background Data. Reproducibility of cervical motion findings has been largely limited to normal subjects, leaving a conspicuous void regarding the measurement error in clinical groups. Methods. There were 2 groups of 25 chronic patients with whiplash and degenerative changes of the cervical spine tested twice (4–7 days). Head movement was measured along the 6 directions, as well as during rotation out of flexion and extension (cervical degenerative changes only). Results. Compared to normal subjects, both groups had a 25% to 35% reduction in cervical motion. High intraclass correlation coefficients (ICCs) (range 0.8–0.92) were derived for all directions. The ICCs for rotation out of flexion and extension were low. The relative standard error of measurement ranged from 15% to 28% for all directions, whereas the corresponding scores of the total cervical motion excursion were 10.6 (cervical degenerative changes) and 13.6% (whiplash). Conclusions. Judged by the ICCs cervical motion, findings were reproducible. However, in view of the measurement error as well as the homogenous reductions, total cervical range of motion should be considered a suitable parameter for interpretation of cervical motion limitations in these patients.

Reproducibility and validity of a new test protocol for measuring isokinetic trunk extension strength.

OBJECTIVE To investigate the reproducibility and validity of isokinetic trunk extension strength scores obtained using a range of motion of 20 degrees and velocities of 10 and 40 degrees /s. BACKGROUND Common protocols for testing trunk extension strength incorporate a range of motion of 40 degrees or more and test velocities of between 30 and 180 degrees/s. These test parameters may be neither necessary for portraying the strength profile of the muscles involved nor suitable for patients impaired with low back dysfunction. DESIGN Test-retest of maximal concentric and eccentric isokinetic trunk extension strength in healthy subjects. METHODS 17 women and 18 men were tested twice within 1-2 weeks. Tests were performed with subjects positioned in sitting. RESULTS The trunk extension strength scores revealed excellent agreement with the expected physiological moment-velocity curve. On average womens trunk extension strength was 62% that of men (range: 59.3-64.4%). The test-retest correlation coefficients were generally higher in women (0.70-0.87) than in men (0.52-0.78) and significant at P=0.01. The standard error of measurement ranged between 13 and 21 N m for women and between 35 and 50 N m for men, which were equivalent to 9% and 15% of the mean strength in women and men, respectively. CONCLUSION This study indicates that the present protocol may be validly applied in assessing trunk extension strength in normal women. RELEVANCE Reproducible and valid trunk extension strength findings are essential if measurable strength deficiency of the extensors is to be formally accepted as an impairment. The present protocol incorporates or meets most of the relevant problems associated with trunk concentric and eccentric strength testing, and hence has the potential of becoming a standard method for clinical applications.

Maximal versus feigned active cervical motion in healthy patients : The coefficient of variation as an indicator for sincerity of effort

Study Design. Maximal and submaximal (feigned) cervical motions in healthy patients were compared. Objective. To test the efficiency of the coefficient of variation in differentiating maximal (sincere) from submaximal (feigned) cervical motion in healthy patients. Summary of Background Data. Although limitation of cervical motion is a recognized impairment, no well-founded approach for verifying the degree to which a patient is maximizing his or her performance is available currently. Methods. A new ultrasound-based system for three-dimensional motion analysis of the head was used to test 25 healthy patients (22 women and 3 men) ages 26 to 48 years. During the first test, (Test 1), the patients were asked initially to move the head maximally at a self-determined velocity in all the primary directions: flexion, extension, right and left rotation, and right and left lateral flexion. They then were presented with a short vignette describing a fictitious accident and asked, using the same protocol, to perform the same types of cervical motions as if they had experienced an injury. No further instructions were provided. A retest (Test 2) in reverse order (feigned effort first) took place 1 to 16 weeks (mean, 3.3 weeks) later. Results. The range of motion and average velocity were significantly smaller (P = 0.0001) in the feigned than in the maximal performance in all directions and on both tests. Feigned range of motion and velocity also were significantly reduced in Test 2 (P = 0.006), as compared with those in Test 1 (P = 0.0001). The range of motion coefficient of variation in the feigned performance (CVf) remained stable on the retest, but was significantly larger on both tests (P < 0.001) than the corresponding CV derived from maximal performance (CVm). Furthermore, a case-by-case analysis showed that whereas the American Medical Association guidelines identified only 16% of the feigned cases, the use of CVf and CVm resulted in a corresponding rate of 87%. Tolerance intervals at 95% and 99% indicated total separation between the distributions of CVf and CVm, respectively. The average velocity-based CVf and CVm were not of a comparable differentiating power. Conclusions. This study indicates that in healthy patients, feigned performance may be differentiated from maximal (sincere) performance effectively and reproducibly using the coefficient of variation.

Cervical motion testing: methodology and clinical implications.

BACKGROUND Measurement of cervical motion (CM) is probably the most commonly applied functional outcome measure in assessing the status of patients with cervical pathology. In general terms, CM refers to motion of the head relative to the trunk as well as conjunct motions within the cervical spine. SPECIAL FEATURES Multiple techniques and instruments have been used for assessing CM. These were associated with a wide variety of parameters relating to accuracy, reproducibility, and validity. Modern measurement systems enable recording, processing, and documentation of CM with a high degree of precision. SUMMARY Cervical motion measures provide substantial information regarding the severity of motion limitation and level of effort in cervically involved patients. They may also be used for following up performance during and after conservative or invasive interventions.