The relationships between instrumented measurements of ankle and knee ligamentous laxity and generalized joint laxity.

AIM: The purpose of this study was to evaluate whether lower extremity joint laxity is a function of a particular joint and/or a generalizable characteristic (trait) of the person. Validated instrumented measurements of ankle and knee joint-specific laxity in the same individual were correlated to determine whether a relationship exists. In addition, ankle and knee joint-specific laxity were correlated with generalized joint laxity using the modified Beighton mobility index. METHODS: Fifty-seven male and female athletes were studied. We examined dominant ankle laxity using an ankle arthrometer and dominate knee anterior laxity using the KT 2000. The dominant ankle was loaded in anteroposterior (AP) drawer and inversion-eversion (I-E) rotation. Laxity was measured as total AP displacement (millimeters) after +/-125 N of applied force and total I-E rotation (degrees) was measured after +/-4 N x m of applied torque. The dominant knee was loaded with an anterior drawer and laxity (millimeters) was measured after manual maximum displacement. RESULTS: Non-significant correlations were observed among the test variables for generalized joint laxity (0.21 to 0.37; P>0.05) and instrumented ankle and knee joint laxity (0.19 to 0.21; P>0.05). When examined by gender, no statistically significant correlations (0.05 to 0.40; P>0.05) were found for either generalized laxity or instrumented ankle and knee joint laxity. CONCLUSIONS: These results imply that ankle and knee joint laxity are joint-specific and not generalizable.

Radiographic findings associated with symptomatic rotator cuff tears.

This study compared shoulder radiographs of patients with a documented rotator cuff tear with those of asymptomatic age-matched controls. Radiographs of 40 subjects with documented rotator cuff tears were evaluated along with similar films of 84 asymptomatic age-matched controls. Three radiographs were taken of each shoulder: (1) acromioclavicular joint view, (2) anterior-posterior view with 30 degrees of external rotation, and (3) supraspinatus outlet view. Two fellowship-trained radiologists interpreted 14 radiographic areas in a blinded fashion. Inspection of the greater tuberosity showed large positive abnormal ratings for sclerosis, osteophytes, subchondral cysts, and osteolysis. No association was noted between acromial morphology and rotator cuff tears. These results indicate that shoulder radiographs of subjects with a documented rotator cuff tear have greater tuberosity radiographic abnormalities that are not noted in asymptomatic subjects without a rotator cuff tear. No relationship was found between tear length and any of the degenerative conditions.

Upper and lower body strength in relation to underhand pitching speed by experienced and inexperienced pitchers.

The relation of legs, arms, shoulders, and grip strength with underhand pitching speed of experienced and inexperienced female pitchers was investigated. For 16 experienced female underhand pitchers and 16 inexperienced women with no softball experience (control group) leg and arm strength were measured using a Hydrafitness exercise machine. Grip strength was measured with a handgrip dynamometer. Underhand throwing speed was measured with a radar gun. Regression analysis showed arm and grip strength correlated with throwing speed (p < or = .05) for the experienced group. For the inexperienced control group, the only correlate of throwing speed was arm strength (p < or = .05). There was a significant difference between the two groups on all measures of strength and ball speed in favor of the experienced group (p < or = .05).

The relationship of age, gender, and degenerative changes observed on radiographs of the shoulder in asymptomatic individuals.

Radiographs of the shoulders of 84 asymptomatic individuals aged between 40 and 83 years were evaluated to determine changes in 23 specific areas. Two fellowship-trained orthopaedic radiologists graded each area on a scale of 0 to II (normal 0, mild changes I, advanced changes II). Logistic regression analysis indicated age to be a significant predictor of change (p < 0.05) for sclerosis of the medial acromion and lateral clavicle, the presence of subchondral cysts in the acromion, formation of osteophytes at the inferior acromion and clavicle, and narrowing and degeneration of the acromioclavicular joint. Gender was not a significant predictor (p > 0.05) for radiological changes. Student's t-test determined significance (p < 0.05) between age and the presence of medial acromial and lateral clavicular sclerosis, subchondral acromial cysts, inferior acromial and clavicular osteophytes, and degeneration of the acromioclavicular joint. Radiological analysis in conditions such as subacromial impingement, pathology of the rotator cuff, and acromioclavicular degeneration should be interpreted in the context of the symptoms and normal age-related changes.

Measurement of upper and lower body strength and its relationship to underhand pitching speed.

This study investigated the possible relationship for legs, arms, shoulders, and grip strength with underhand throwing speed. 40 female subjects had their legs, arms, and shoulder strength measured using a multipurpose exercise machine for assessing resistive force. Grip strength was measured using a handgrip dynamometer. Underhand throwing speed was measured with a radar gun. Regression analysis indicated a relationship (p < or = .05) between strength of the arms and underhand pitching speed. No significant relationships were found for legs, shoulders, and grip strength, and underhand pitching speed.

Instrumented measurement of anteroposterior and inversion-eversion laxity of the normal ankle joint complex.

Manual examination is the most common method for the evaluation of ankle anteroposterior (AP) and inversion-eversion (I-E) laxity. Objective assessment data of normal ankle laxity must be provided before comparison with an injured ankle can be made. The purpose of this study was to compare AP translation and I-E rotation at three force loads between dominant and nondominant ankles and to assess the test-retest reliability of a portable arthrometer in obtaining these measurements. The arthrometer consists of a frame that is fixed to the foot, a pad that is attached to the tibia, and a load-measuring handle that is attached to the foot plate through which the load is applied. A six-degrees-of-freedom spatial kinematic linkage system is connected between the tibial pad and the foot frame to measure motion. Instrumented measurement testing of total AP displacement and I-E rotation of both ankles was performed in 41 subjects (21 men and 20 women; mean age, 23.8 +/- 4.4 years). Subjects had no history of ankle injury. Subjects were tested in the supine position while lying on a table with the knee secured in extension and the foot positioned at 0 degrees of flexion. Laxity was measured from total AP displacement (millimeters) during loading to 125 N of AP force and from total I-E rotation (degrees of range of motion) during loading to 4000 N-mm. Reliability was evaluated by calculating intraclass correlation coefficients (2,1) at 75 N, 100 N, and 125 N of AP force and at 2000, 3000, and 4000 N-mm torque loads. Mean differences for displacement and rotation between the dominant and nondominant ankles at each of the force and torque loads were analyzed by dependent t-tests. For both the dominant and nondominant ankles, respectively, the reliability coefficients at each of the force loads for AP displacement (range, 0.82-0.89) and I-E rotation (range, 0.86-0.97) were high. The t-test analyses showed no significant differences (P > or = 0.05) for total AP displacement or I-E rotation between the dominant and nondominant ankles at any of the force loads. The results are clinically useful in providing information about the reliability of measures at different AP and I-E force loads using a portable ankle ligament arthrometer.

Reliability and effects of arm dominance on upper extremity isokinetic force, work, and power using the closed chain rider system.

OBJECTIVE: The purpose of our study was to assess the reliability of the Closed Chain Rider System between exercise sessions and to determine the effects of arm dominance using muscle force, work, and power measures during closed chain chest-press exercise. DESIGN AND SETTING: Sitting subjects underwent identical testing on 2 occasions and performed 5 reciprocal chest-press movements at speeds of 51 and 76 cm/s. SUBJECTS: Thirty-eight healthy college students. MEASUREMENTS: Average force, total work, average power, and linear range of motion were recorded. Reliability was evaluated by calculating intraclass correlation coefficients. Mean differences between the dominant and nondominant arms for the measured variables were analyzed by dependent t tests. RESULTS: For both the dominant and nondominant arms at the 51 and 76 cm/s speeds, reliabilities of average force (range = 0.85 to 0.91), total work (range = 0.88 to 0.92), and average power (range = 0.86 to 0.89) were clinically acceptable. The dominant arm produced significantly greater average force, total work, and average power compared with the nondominant arm. CONCLUSIONS: Our results provide clinically useful information about the reliability of force, work, and power measures during multijoint bilateral chest-press movement. Clinicians should be aware of measured differences between dominant and nondominant arms.

Effects of isokinetic velocity spectrum exercise on average power and total work.

In this study we compared the influence that the order of the performance of different velocity exercise progressions has on average muscle power and total work production during a velocity spectrum isokinetic training session. Twenty-two college students were assigned randomly to four exercise trials, each containing an isokinetic exercise training session involving dominant knee extensors and flexors. Each exercise trial consisted of two sets of ten repetitions at speeds of 30 degrees , 90 degrees , 150 degrees , and 210 degrees /sec. The pretest, posttest, and experimental session muscle function measurements were assessed. Selected measurements of average power (joules/sec) and total work (joules) were used to make comparisons between the protocols. There was no training effect (change in peak torque) during the study for either extension or flexion at any of the four speeds. Total work was similar across the four protocols. There was a difference in average power for both extension and flexion among the protocols. We conclude that when performing velocity spectrum type training, performing faster speed sets early in the exercise session will produce a greater average power.

Effects of blocked versus random practice by mentally retarded subjects on learning a novel skill.

The purpose of this study was to assess the effects of different practice conditions on mentally retarded subjects learning a novel task. 20 subjects with a mean IQ of 51.82 were randomly assigned to one of two practice conditions. The first group practiced at three different speeds (60, 30, and 15 rpm) on the pursuit rotor using a block arrangement in which each speed was practiced for five consecutive trials of 20 sec. duration before practicing at the next speed. The second group used random practice performing 15 trials of the pursuit rotor so three speeds were randomly distributed over the 15 trials. Both groups on the next day performed 15 trials of 20 sec. duration on the pursuit rotor at the transfer speed of 45 rpm. Analysis showed no significant differences among practice conditions which provided 10 min. of experience prior to test.

Effects of social reinforcement on motor performance of trainable retarded students on speed and persistence tasks.

The effects of social reinforcement on two motor tasks by 40 retarded subjects with high and low MAs were investigated. Ages ranged from 10 to 18 yr., M = 14.46 yr. Mean IQ was 46.82; mental age for the high subjects was 8.09 yr., for the low 5.45 yr. Significant main effects for social reinforcement were found for the persistence measure but none for the speed measure. The effectiveness of praise on retarded subjects' performance is related to the type of motor task used.

Effects of mental age, knowledge of results, and social reinforcement on motor performance.

The effects of mental age (MA), knowledge of results, and social reinforcement on performance on a speed motor task by mildly mentally retarded children was investigated. Significant main effects were found for the variables of MA and social reinforcement and significant interactions for the MA x Social-Reinforcement conditions and the Knowledge of Results x Social-Reinforcement conditions. Post hoc analysis indicated that high-MA subjects performed significantly better under verbal praise conditions than did low-MA subjects. Also, knowledge of results was most effective in the presence of verbal praise. We suggested that verbal praise sensitized subjects to attend to the knowledge of results cue.