Manual landmark identification and tracking during the medial rotation test of the shoulder: an accuracy study using three-dimensional ultrasound and motion analysis measures.

Palpation of movement is a common clinical tool for assessment of movement in patients with musculoskeletal symptoms. The purpose of this study was to measure the accuracy of palpation of shoulder girdle translation during the medial rotation test (MRT) of the shoulder. The translation of the gleno-humeral and scapulo-thoracic joints was measured using both three-dimensional ultrasound and palpation in order to determine the accuracy of translation tracking during the MRT of the shoulder. Two movements of 11 normal subjects (mean age 24 (SD=4), range 19-47 years) were measured. The agreement between measures was good for scapulo-thoracic translation (r=0.83). Gleno-humeral translation was systematically under estimated (p=0.03) although moderate correlation was found (r=0.65). These results indicate that translation of the measured joints can be tracked by palpation and further tests of the efficacy of palpation tracking during musculoskeletal assessment may be warranted.

The effect of serial casting on gait in children with cerebral palsy: preliminary results from a crossover trial.

Serial casting aims to improve an equinus gait pattern in children with spastic cerebral palsy (SCP). We evaluated the effect of short-term stretch casting on gait in children with SCP, compared to the natural history. A crossover trial, consisting of a control phase and a casting phase, was conducted with children randomised into two groups. Both groups were assessed clinically, and using 3D gait analysis, at 0, 5 and 12 weeks. Subjects in one group had the 3 month casting phase first and in the other had the 3 month control period first. Casts were changed weekly and set at maximum available ankle dorsiflexion. The mean changes at 5 weeks and 12 weeks from baseline measurements in the casting phase were compared with the change within the same time interval in the control phase. Significant improvements in passive ankle dorsiflexion (knee flexed) were found at 5 and 12 weeks. Passive ankle dorsiflexion (knee extended), ankle dorsiflexion in single support, ankle dorsiflexion in swing and minimum hip flexion in stance improved significantly at 5 weeks but not at 12 weeks from baseline. Other kinematic parameters, the score on the Gillette Functional Assessment Questionnaire, and maximum reported walking distance were not changed by casting. Casting to improve range appears to improve passive and dynamic ankle dorsiflexion, but the changes are small, short lived and do not appear to affect function.

Number of repetitions to maximum in hop tests in patients with anterior cruciate ligament injury.

The unilateral horizontal, triple cross-over and vertical hops are commonly used as outcome measures after knee injury but there is little knowledge of the number of repetitions needed to reach maximum performance. Seventy subjects who had either an anterior cruciate ligament deficient or reconstructed knee participated in this study. Unilateral vertical, horizontal, and triple cross-over hop testing was applied to each leg until two consecutive decrements in performance occurred. The number of repetitions to reach maximum during these tests were calculated. Fifteen repetitions of the horizontal and vertical hops, and 10 repetitions of the triple-crossover hop enable distances to be achieved that are acceptably close to maximal levels in these knee-injured patients. In order to increase the likelihood of finding a patient's maximum hop performance after knee injury, more repetitions are suggested than has been reported in the literature.

Relationship of leg muscle strength and knee function in the early period after anterior cruciate ligament reconstruction.

The purpose of this descriptive study was to assess the relationship between knee function and the strength testing performance of various leg muscles in the early period after anterior cruciate ligament reconstruction (ACLR). Twenty-four patients who had recent ACLR (seven females and 17 males, mean age=27 years) were tested for leg muscle strength and knee function 2 weeks after surgery. The concentric peak torques of the hip and knee extensors and knee flexors were measured at 210 degrees s(-1). In addition, the latter two muscle groups were measured at 60 degrees s(-1), and also isometrically (at a knee angle of 60 degrees). Knee function was assessed using a three-dimensional motion analysis system combined with a force platform. This system determined knee joint angles, torques and powers during level walking, stair ascent and stair descent. Pearson's correlation coefficients were calculated to assess the relationships between the injured knee function variables and the injured/uninjured strength ratios. The correlation coefficients ranged (in absolute value) from 0.03 to 0.81, and were generally higher for the stair tasks compared with level walking, and highest for the knee extensors (as compared with the knee flexors and hip extensors), and the strength test velocity appears much less important than the muscle group tested. These results contribute evidence indicating the importance of knee extensor strength to knee function in the early period after ACLR.

The effect of different knee angles on knee volume measured with the Perometer device in uninjured subjects.

The Perometer is an optoelectronic device used to calculate limb volume. However, knee angle effect on knee volume during a Perometer measurement has not been reported. This could be a potential confounding factor in assessing knee volume in subjects with impaired knee mobility and where volume measurements are taken over time. To address this issue, bilateral knee volume measurements were recorded from 20 uninjured subjects in seven different knee angles from 0-60 degrees flexion. All 40 knees were not measured in all seven angles because of obstruction of the measurement frame when some knees were in 50 degrees and 60 degrees flexion. Thus, the volume data was separated into three subgroups for analysis: 40 knees at knee flexion angles 0, 10, 20, 30 and 40 degrees; 36 knees at 50 degrees; and 16 knees at 60 degrees. Repeated measures analysis of variance showed a statistically significant difference between the volume measurements in the three subgroups: 0-40 degrees knee flexion [F(4,156) = 35.146, P<0.001], 50 degrees knee flexion (F(5,175) = 56.826, P<0.001] and 60 degrees knee flexion, [F(6,90) = 45.825, P<0.001]. Subsequent paired t-tests showed statistically significant [P<0.001] differences in knee volume for all angle comparisons except for 0 and 10 degrees (absolute volume difference of 1.2 ml; P = 0.772) and 0 and 20 degrees (absolute volume difference of 10.9 ml; P = 0.036) (Bonferroni adjustment applied). The absolute values of the differences that were shown to be statistically significantly different ranged from 12-47 ml for the 0-40 degrees subgroup; 39-85 ml for the 50 degrees subgroup and 35-107 ml for the 60 degrees subgroup. In conclusion, knee angle affects Perometer knee volume measurements and statistically significant differences occur as knee flexion exceeds 20 degrees with greater differences occurring as the knee is more flexed. Hence, knee angle should be reproduced in re-testing and in side-to-side comparisons when evaluating knee volume with the Perometer.

Gait adaptations in patients with chronic posterior instability of the knee.

OBJECTIVE: A retrospective analysis was performed to assess gait in individuals with a long history of posterior knee instability. DESIGN: Descriptive study. BACKGROUND: There are few studies in the literature concerning evaluation of the biomechanics of the knee in patients with knee posterior instability. METHODS: Nine individuals with posterior knee instability and a matched control group of uninjured subjects were tested in regards to knee kinematics and kinetics while walking and ascending and descending stairs. The mean follow up time for the individuals with posterior instability was 11.1 years. Individual satisfaction with the knee was measured by having participants complete the Flandry (also known as Hughston Clinic) self-assessment questionnaire. RESULTS: It was found that patients with knee posterior instability who indicated a higher level of satisfaction on the Flandry score walked in a manner that demonstrated greater peak knee extensor torque during stance phase, while less satisfied patients with knee posterior instability demonstrated lower peak knee extensor torque. There was a significant correlation between the self-assessment score and the peak knee extensor torque during level walking (P=0.003). During stair ascent and descent, patients with posterior instability averaged lower knee extensor torque and power than the control subjects, but those differences were only statistically significant in power while descending stairs (P=0.048). CONCLUSIONS: Individuals with chronic knee posterior instability modify their gait, and the adaptation can be predicted based upon the individuals self-assessment of their knee using the Flandry questionnaire. RELEVANCE: These data suggest that gait retraining may be a valuable addition to the traditional muscle strengthening programs, which are commonly used during conservative management of knee posterior instability.

Validation of the Hughston Clinic subjective knee questionnaire using gait analysis.

INTRODUCTION: Subjective questionnaires, completed by the patient, are often used to document the status of a disabled knee. The purpose of this study was to validate the Hughston Clinic subjective knee questionnaire by describing how knee kinematics and kinetics correlated to subjective knee scores after knee injury and surgery. METHODS: Five groups were studied: patients 2 (N = 37), 6 (N = 37), and 24 (N = 8) wk after ACL reconstruction (ACLR); patients with a chronic PCL deficiency (N = 9); and uninjured controls (N = 8). A three-dimensional motion analysis system and force platform were used to measure flexion angles and knee moments during level walking and stair climbing. RESULTS: Hughston Clinic questionnaire scores were significantly correlated to mechanical descriptors measured during stair ascent and descent in the 2- and 6-wk ACLR groups (P < 0.05). The Hughston Clinic questionnaire score was correlated to several kinematic variables in the ACL reconstructed knee at 24 wk postoperative, e.g., knee flexion during walking. In the PCL deficient group, the Hughston Clinic questionnaire score was correlated with several kinetic measures, e.g., the peak moment (knee extensors). The Hughston Clinic questionnaire score was not correlated to knee mechanics in the control group. CONCLUSION: The Hughston Clinic questionnaire score has been shown to be valid in this study as it reflects some mechanical descriptors during activities of daily living in the first 6 wk post ACL reconstruction. The questionnaire also provides information on gait modifications by people coping with knee injuries.

Open and closed kinetic chain exercises in the early period after anterior cruciate ligament reconstruction. Improvements in level walking, stair ascent, and stair descent.

Thirty-seven patients who had undergone anterior cruciate ligament reconstruction were tested in a gait analysis laboratory at 2 and 6 weeks after surgery. Between test sessions, patients were randomly assigned to a course of either closed or open kinetic chain resistance exercises (3 sessions per week for 4 weeks). Gait analysis consisted of bilateral calculations of knee joint angle, moment, and power during level walking, stair ascent, and stair descent. An analysis of variance on the effects of training group and test session indicated that the only variable to be significantly affected by the type of exercise program was the amount of knee flexion at the beginning of step-up (P < 0.05). All other measures of knee angle, moment, and power (16 total variables) showed no significant difference between the exercise groups. All variables measured on the injured side showed significant improvement from test 1 to test 2 (P < 0.05), but the injured leg remained functionally deficient when compared with the uninjured leg. These data suggest that there are no clinically significant differences in the functional improvement resulting from the choice of open or closed kinetic chain exercises in the early period after this surgery.

Correlates of knee laxity change in early rehabilitation after anterior cruciate ligament reconstruction.

Factors other than ligament graft length (knee ROM, knee swelling, initial knee laxity) may need to be accounted for in interpreting changes in knee laxity during rehabilitation following anterior cruciate ligament reconstruction (ACLR) surgery. Twenty-three patients recovering from ACLR surgery (16 M, 7 F, age mean = 30) were tested at 2 and 6 weeks after ACLR with knee laxity measured using th Knee Signature System arthrometer, passive ROM with a standard goniometer and swelling by measuring knee circumference at the mid-patella level using a cloth measuring tape. Spearman correlation coefficients (in parentheses) were calculated using rankings of the change in the injured minus uninjured knee laxity as the dependent variable and the following independent variables: pre-test injured minus uninjured knee laxity (ranked; -0.457; statistically significant two-tailed P < 0.05); change in injured knee maximum extension relative to the uninjured side (ranked; 0.127); change in injured knee maximum flexion relative to the uninjured side (unranked; -0.073); and change in the injured minus uninjured knee girth (unranked; -0.159). These results indicate that consideration should be given to the patient's knee laxity at the start of intervention when using changes in laxity to guide rehabilitation after ACLR.

Velocity specificity in early training of the knee extensors after anterior cruciate ligament reconstruction.

Resistance-training velocity specificity is known to occur in isotonic training of uninjured subjects and in isokinetic training of injured patients. Whether velocity specificity occurs with isotonic training in injured patients has not been tested, despite the common use of this exercise mode in patients. Thirty-two patients recovering from anterior cruciate ligament reconstruction (ACLR) surgery were tested at approximately 2 and 6 weeks after surgery. The isokinetic injured/uninjured strength ratios of the knee extensors were compared for the test velocities of 60 degrees x s(-1) and 210 degrees x s(-1), as assessed before and after a 4-week training period. Isotonic training of the knee extensors at 60 degrees x s(-1) was applied in formal sessions three times per week. The isokinetic injured/uninjured strength ratios were compared for the two test velocities, and there was no indication that training velocity specificity occurred in these patients. Possible reasons for this finding, which contrasts with previous work, are discussed.

Effects of open versus closed kinetic chain training on knee laxity in the early period after anterior cruciate ligament reconstruction.

Knee extensor resistance training using open kinetic chain (OKC) exercise for patients recovering from anterior cruciate ligament reconstruction (ACLR) surgery has lost favour mainly because of research indicating that OKC exercise causes greater ACL strain than closed kinetic chain (CKC) exercise. In this prospective, randomized clinical trial the effects of these two regimes on knee laxity were compared in the early period after ACLR surgery. Thirty-six patients recovering from ACLR surgery (29 males, 7 females; age mean = 30) were tested at 2 and 6 weeks after ACLR with knee laxity measured using the Knee Signature System arthrometer. Between tests subjects trained using either OKC or CKC resistance of their knee and hip extensors in formal physical therapy sessions three times per week. Following adjustment for site of treatment, pretraining injured knee laxity, and untreated knee laxity at post-training, the use of OKC exercise, when compared to CKC exercise, was found to lead to a 9% increase in looseness with a 95% confidence interval of -8% to +29%. These results indicate that the great concern about the safety of OKC knee extensor training in the early period after ACLR surgery may not be well founded.

Reliability of leg muscle electromyography in vertical jumping.

In this study we aimed to determine the reliability of the surface electromyography (EMG) of leg muscles during vertical jumping between two test sessions, held 2 weeks apart. Fifteen females performed three maximal vertical jumps with countermovement. The displacement of the body centre of mass (BCM), duration of propulsion phase (time), range of motion (ROM) and angular velocity of the knee and surface EMG of four leg muscles (rectus femoris, vastus medialis. biceps femoris and gastrocnemius) were recorded during the jumps. All variables were analysed throughout the propulsion and mid-propulsion phases. Intraclass correlation coefficients (ICC) for the rectus femoris, vastus medialis, biceps femoris and gastrocnemius were calculated to be 0.88, 0.70, 0.24 and 0.01, respectively. BCM, ROM and time values all indicated ICC values greater than 0.90, and the mean knee angular velocity was slightly lower, at 0.75. ICCs between displacement of the BCM and integrated EMG (IEMG) of the muscles studied were less than 0.50. The angular velocity of the knee did not correlate well with muscle activity. Factors that may have affected reliability were variations in the position of electrode replacement, skin resistance, cross-talk between muscles and jump mechanics. The results of this study suggest that while kinematic variables are reproducible over successive vertical jumps, the degree of repeatability of an IEMG signal is dependent upon the muscle studied.

The relationship between open and closed kinetic chain strength of the lower limb and jumping performance.

Closed kinetic chain (CKC) exercise has become popular in rehabilitation partly due to the belief that it is more closely related to function than open kinetic chain (OKC) resistance. This study's purpose was to investigate the relationship between OKC and CKC strength of the lower limb extensors and functional performance. Twenty uninjured female subjects performed isotonic strength tests for the knee extensors in OKC and for the hip, knee, and ankle extensors in the squat exercise (CKC). Vertical and standing long jump performance was assessed using an optoelectric motion analysis system. Pearson product-moment correlation analysis showed that CKC strength scores were correlated with vertical jump performance (r = 0.722, p = 0.002) and standing long jump performance (r = 0.650, p = 0.005). Open kinetic chain strength demonstrated minimal correlation with vertical jump (r = 0.097) and standing long jump performance (r = 0.070). We conclude that lower limb extensor CKC muscle strength is more highly related to jumping performance than knee extensor OKC strength, but further research is needed to assess possible differences in training effectiveness for these two regimes.

Early phase differential effects of slow and fast barbell squat training.

To examine the importance of resistance training movement speed, two groups of women (24 +/- 4 years, 162 +/- 5 cm, 59 +/- 7 kg) squatted repeatedly at 1) 2 seconds up, 2 seconds down (slow, N = 11); or 2) 1 second up, 1 second down (fast, N = 10), doing three warm-up sets and three eight-repetition maximum sets, three times per week for 7 weeks. Tests included force platform and video analysis of the vertical jump, long jump, and maximum squat, and isometric and isokinetic knee extensor testing at speeds from 25 to 125 deg/sec. The groups improved similarly in many variables with training but also showed some differences. In the long jump, the fast group was superior in numerous variables including knee peak velocity and total-body vertical and absolute power. In the vertical jump, fast training affected the ankle and hip more (e.g., average power), and slow training mostly affected the knee (average torque). In isokinetic testing, the fast group improved strength most at the faster velocities, while the slow group strength changes were consistent across the velocities tested. Although both slow and fast training improved performance, faster training showed some advantages in quantity and magnitude of training effects.

A kinematic comparison of overground and treadmill walking.

OBJECTIVE: To compare overground and treadmill ambulation for possible differences in gait temporal variables and leg joint kinematics. DESIGN: A human subject trial of walking in two conditions. BACKGROUND: The treadmill is frequently used to simulate overground ambulation; however, the literature shows a wide difference of opinion as to whether the treadmill replicates the overground environment. METHODS: A total of 17 uninjured subjects walked overground at their preferred velocity. The treadmill was then set at the average velocity obtained in overground walking. Gait temporal variables and leg joint kinematics were analysed using the three dimensional (3D) Kinemetrix Motion Analysis System. The data were analysed separately for the two gender groups and for the groups combined. RESULTS: In the females, only the maximum hip flexion angle was significantly different in the two conditions with greater flexion occurring on the treadmill. For males, significant differences were noted between the two conditions for cadence and maximum knee flexion angle with greater values in the treadmill walking. When all subjects were compared, significant increases were seen during treadmill walking in hip range of motion, maximum hip flexion joint angle and cadence, while a significant decrease was observed in stance time. CONCLUSIONS: Statistically significant differences exist between overground and treadmill walking in healthy subjects for some joint kinematic and temporal variables. RELEVANCE: The results of this and other studies demonstrate that the kinematics of human walking differ in treadmill and overground ambulation. The next step in this line of research is to assess whether the kinematic differences in the two walking conditions are exhibited in different patient groups. If differences do exist in patient groups, then the interpretation of treadmill-based gait analysis findings should not be extended to that of ground walking, particularly where the patient has an impaired hip function, such as that exemplified after total hip replacement.

Some effects of camera placement on the accuracy of the Kinemetrix three-dimensional motion analysis system.

OBJECTIVE: To assess the accuracy of the Kinemetrix motion analysis system to measure horizontal movement by a single reflective marker away from two cameras with differing camera placements. DESIGN: Trial of the effects of nine different camera arrangements on precision of non-human movement. BACKGROUND: In many cases the ability to arrange cameras to allow a separation of 60 degrees is not possible. Little is known about the precision of motion analysis systems for small camera angle separations. METHODS: The accuracy of the Kinemetrix system was assessed with camera horizontal separations of 15 degrees, 30 degrees and 45 degrees, and vertical separations of 0 degrees, 15 degrees and 30 degrees rendering nine different camera placements. The distance between the cameras and the object was always maintained at 4 m. During each test the marker was moved a known horizontal distance along a line bisecting the horizontal angular separation of the two cameras. The mean absolute errors of the Kinemetrix measurement were calculated. RESULTS: At the smallest camera separation tested (15 degrees horizontal, 0 degrees vertical), the Kinemetrix was unable to calculate the three-dimensional co-ordinate of the marker. For all other camera positions tested, the errors in measurements were small (mean absolute errors < 2 mm). CONCLUSIONS: Maintaining camera horizontal and vertical separations above a sum of 30 degrees is sufficient for clinical testing. RELEVANCE: Motion analysis systems are becoming more common for clinical evaluation where only confined testing areas are available. These confined areas often make positioning of cameras at greater than 60 degrees impossible; therefore, there is a need to explore the errors involved in placing two cameras at less than 60 degrees.

Resistance training modes: specificity and effectiveness.

There is considerable demand for information on the effectiveness of various resistance exercises for improving physical performance, and on how exercise programs must match functional activities to produce the greatest performance gains (training specificity). Evidence supports exercise-type specificity; the greatest training effects occur when the same exercise type is used for both testing and training. Range-of-motion (ROM) specificity is supported; strength improvements are greatest at the exercised joint angles, with enough carryover to strengthen ROMs precluded from direct training due to injury. Velocity specificity is supported; strength gains are consistently greatest at the training velocity, with some carryover. Some studies have produced a training effect only for velocities at and below the training velocity while others have produced effects around the training velocity. The little, mainly isokinetic, evidence comparing different exercise velocities for improving functional performance suggests that faster exercise best improves fast athletic movements. Yet isometric exercise can improve actions like the vertical jump, which begin slowly. The rate of force application may be more important in training than actual movement speed. More research is needed into the specificity and efficacy of resistance exercise. Test populations should include both males and females of various ages and rehabilitation patients.

Static pre-load effect on knee extensor isokinetic concentric and eccentric performance.

The effect of two static pre-load levels on isokinetic concentric (CON) and eccentric (ECC) performance of the knee extensors at 90 degrees.s-1 was evaluated in 35 healthy subjects. The low pre-load level was 50 N, and the high level was 75% of a maximal voluntary isometric contraction, performed at the start angles of 100 degrees (CON) and 30 degrees (ECC) of knee flexion. A two-way ANOVA with two repeated measures (load and angle) and a Newman-Keuls post hoc analysis were performed to compare the interaction of pre-load and angle at every 5 degrees in the ROM. The differences in average torque, peak torque, and peak torque angle between the pre-load levels were also analyzed with repeated-measures t-tests. The high pre-load condition had a significant increase in torque at 99, 95, 90, and 85 degrees concentrically and 31, 35, 40, 45, and 50 degrees eccentrically. In comparing the two pre-load conditions over the whole torque curve, there was a significant difference in average torque values of both CON and ECC, no significant difference in peak torque in either contraction, and a significant shift in peak torque angle with CON contractions only.

Effects of different acceleration deceleration rates on isokinetic performance of the knee extensors.

The Kinetic Communicator provides three acceleration/deceleration rates (low, medium, and high) to control the limb and, thus, prevent impact forces and torque overshoot found with free acceleration. The purpose of this study was to examine the effect of three acceleration/deceleration rates on isokinetic performance of the knee extensors on the Kinetic Communicator. Thirty-one healthy females with no history of knee pathology performed three concentric/eccentric contractions of the knee extensors at each acceleration/deceleration rate at a velocity of 90 degrees /sec. A one-way repeated measures analysis of variance (ANOVA) and Scheffé post hoc tests were used to compare between each acceleration/deceleration rate: 1) the average velocity, peak torque, and average torque of the whole curve; and 2) the average velocity, average torque, and range of motion of the acceleration and deceleration phases. The acceleration/deceleration rate significantly affected the average velocity of the whole curve, acceleration phase, and deceleration phase. Although acceleration/deceleration rate had some effect on average torque in the acceleration and deceleration phases, peak torque and average torque of the whole curve were not significantly affected. Thus, in this study, the choice of acceleration/deceleration rate at 90 degrees /sec did not appear to have a clinically significant effect on average torque and peak torque for the whole curve. J Orthop Sports Phys Ther 1991;14(4):161-168.