Robert J. Heitman

Chondrocyte Viability in Refrigerated Osteochondral Allografts Used for Transplantation Within the Knee

Purpose To evaluate cell viability and matrix characteristics of refrigerated osteochondral allografts implanted up to 44 days after harvest. Methods Sixteen refrigerated allografts underwent histologic and ultrastructural examination and fluorescence excitation analysis prior to implantation. The average size of the graft implanted was 6.2 cm2 (± 3.4 cm2). Refrigerated allografts averaged 30 days (range, 17 to 44 days) from donor expiration to implantation. Nine specimens underwent cell viability testing. The percent viability of refrigerated allografts prior to implantation averaged 67%. Results No significant correlations were noted between histologic score, electron microscopy score, matrix staining percent (MSP) score, and viability. When time to implantation was assessed, an inverse correlation was noted with MSP score (r= .539) (P< 0.05), indicating less matrix staining in grafts refrigerated longer after harvest. Conclusion The current data indicate that refrigerated osteochondral allografts can be maintained for up to 44 days with average chondrocyte viability of 67%.

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° 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 ≥ 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.

Upper and lower body strength in relation to ball speed during a serve by male collegiate tennis players

The relation of leg, shoulder, and grip strength to ball speed in the tennis serve was investigated. For 15 collegiate male tennis players, leg and shoulder strength were measured using a Lido Active isokinetic dynamometer, grip strength with a handgrip dynamometer, and ball speed with a radar gun. Regression analysis showed no significant (p<.05) relationship among the strength variables and ball speed. Results were explained in terms of strength not being the only factor involved in producing ball speed during the tennis serve.

Knee and Ankle Position, Anterior Drawer Laxity, and Stiffness of the Ankle Complex

CONTEXT Anterior drawer testing of the ankle is commonly used to diagnose lateral ligamentous instability. Our hypothesis was that changing knee and ankle positions would change the stability of the ankle complex during anterior drawer testing. OBJECTIVES To assess the effects of knee and ankle position on anterior drawer laxity and stiffness of the ankle complex. DESIGN A repeated-measures design with knee and ankle position as independent variables. SETTING University research laboratory. PATIENTS OR OTHER PARTICIPANTS Bilateral ankles of 10 female (age = 19.8 +/- 1.1 years) and 10 male (age = 20.8 +/- 1.2 years) collegiate athletes were tested. INTERVENTION(S) Each ankle complex underwent loading using an ankle arthrometer under 4 test conditions consisting of 2 knee positions (90 degrees and 0 degrees of flexion) and 2 ankle positions (0 degrees and 10 degrees of plantar flexion [PF]). MAIN OUTCOME MEASURE(S) Recorded anterior laxity (mm) and stiffness (N/mm). RESULTS Anterior laxity of the ankle complex was maximal with the knee positioned at 90 degrees of flexion and the ankle at 10 degrees of PF when compared with the knee positioned at 0 degrees of flexion and the ankle at 10 degrees or 0 degrees of PF (P < .001), whereas ankle complex stiffness was greatest with the knee positioned at 0 degrees of flexion and the ankle at 0 degrees of PF (P < .009). CONCLUSIONS Anterior drawer testing of the ankle complex with the knee positioned at 90 degrees of flexion and the ankle at 10 degrees of PF produced the most laxity and the least stiffness. These findings indicate that anterior drawer testing with the knee at 90 degrees of flexion and the ankle at 10 degrees of PF may permit better isolation of the ankle capsuloligamentous structures.

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.

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 ≤ .05) for the experienced group. For the inexperienced control group, the only correlate of throwing speed was arm strength (p≤ 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 ≤.05).

Arthrometric Measurement of Ankle-Complex Motion: Normative Values

CONTEXT Valid and reliable measurements of ankle-complex motion have been reported using the Hollis Ankle Arthrometer. No published normative data of ankle-complex motion obtained from ankle arthrometry are available for use as a reference for clinical decision making. OBJECTIVE To describe the distribution variables of ankle-complex motion in uninjured ankles and to establish normative reference values for use in research and to assist in clinical decision making. DESIGN Descriptive laboratory study. SETTING University research laboratory. PATIENTS OR OTHER PARTICIPANTS Both ankles of 50 men and 50 women (age = 21.78 ± 2.0 years [range, 19-25 years]) were tested. INTERVENTION(S) Each ankle underwent anteroposterior (AP) and inversion-eversion (I-E) loading using an ankle arthrometer. MAIN OUTCOME MEASURE(S) Recorded anterior, posterior, and total AP displacement (millimeters) at 125 N and inversion, eversion, and total I-E rotation (degrees) at 4 Nm. RESULTS Women had greater ankle-complex motion for all variables except for posterior displacement. Total AP displacement of the ankle complex was 18.79 ± 4.1 mm for women and 16.70 ± 4.8 mm for men (U = 3742.5, P < .01). Total I-E rotation of the ankle complex was 42.10 degrees ± 9.0 degrees for women and 34.13 degrees ± 10.1 degrees for men (U = 2807, P < .001). All variables were normally distributed except for anterior displacement, inversion rotation, eversion rotation, and total I-E rotation in the womens ankles and eversion rotation in the mens ankles; these variables were skewed positively. CONCLUSIONS Our study increases the available database on ankle-complex motion, and it forms the basis of norm-referenced clinical comparisons and the basis on which quantitative definitions of ankle pathologic conditions can be developed.

EFFECTS OF SPECIFIC VERSUS VARIABLE PRACTICE ON THE RETENTION AND TRANSFER OF A CONTINUOUS MOTOR SKILL

The effects of specific versus variable practice on retention and transfer was investigated. 30 participants were randomly assigned to one of three practice conditions. The variable speed group practiced on a pursuit rotor task at three different speeds (60, 45, 30 rpm) which were randomly distributed but equal in number for 30 10-sec. trials on Day 1. The Specific Practice group performed all 30 10-sec. trials at 45 rpm on Day 1. On Day 2, all groups performed 15 trials at the 45-rpm retention speed and 15 trials at the 75-rpm transfer speed. The Control group only performed on Day 2. Analysis showed the Specific Practice group had significantly higher scores on Day 1. On Day 2, the Specific Practice group had significantly higher retention scores and the Variable Practice group had higher transfer scores. Continuous motor skills might be practiced differently depending on the environmental context in which the skill may be used.

Joint Stability Characteristics of the Ankle Complex After Lateral Ligamentous Injury, Part I: A Laboratory Comparison Using Arthrometric Measurement

CONTEXT The mechanical property of stiffness may be important to investigating how lateral ankle ligament injury affects the behavior of the viscoelastic properties of the ankle complex. A better understanding of injury effects on tissue elastic characteristics in relation to joint laxity could be obtained from cadaveric study. OBJECTIVE To biomechanically determine the laxity and stiffness characteristics of the cadaver ankle complex before and after simulated injury to the anterior talofibular ligament (ATFL) and calcaneofibular ligament (CFL) during anterior drawer and inversion loading. DESIGN Cross-sectional study. SETTING University research laboratory. PATIENTS OR OTHER PARTICIPANTS Seven fresh-frozen cadaver ankle specimens. INTERVENTION(S) All ankles underwent loading before and after simulated lateral ankle injury using an ankle arthrometer. MAIN OUTCOME MEASURE(S) The dependent variables were anterior displacement, anterior end-range stiffness, inversion rotation, and inversion end-range stiffness. RESULTS Isolated ATFL and combined ATFL and CFL sectioning resulted in increased anterior displacement but not end-range stiffness when compared with the intact ankle. With inversion loading, combined ATFL and CFL sectioning resulted in increased range of motion and decreased end-range stiffness when compared with the intact and ATFL-sectioned ankles. CONCLUSIONS The absence of change in anterior end-range stiffness between the intact and ligament-deficient ankles indicated bony and other soft tissues functioned to maintain stiffness after pathologic joint displacement, whereas inversion loading of the CFL-deficient ankle after pathologic joint displacement indicated the ankle complex was less stiff when supported only by the secondary joint structures.

Application of Generalizability Theory in Estimating the Reliability of Ankle-Complex Laxity Measurement

CONTEXT Generalizability theory is an appropriate method for determining the reliability of measurements obtained across more than a single facet. In the clinical and research settings, ankle-complex laxity assessment may be performed using different examiners and multiple trials. OBJECTIVE To determine the reliability of ankle-complex laxity measurements across different examiners and multiple trials using generalizability theory. DESIGN Correlational study. SETTING Laboratory. PATIENTS OR OTHER PARTICIPANTS Forty male university students without a history of ankle injury. MAIN OUTCOME MEASURE(S) Measures of right ankle-complex anteroposterior and inversion-eversion laxity were obtained by 2 examiners. Each examiner performed 2 anteroposterior trials, followed by 2 inversion-eversion trials for each ankle at 0 degrees of ankle flexion. Using generalizability theory, we performed G study and D study analyses. RESULTS More measurement error was found for facets associated with examiner than with trial for both anteroposterior and inversion-eversion laxity. Inversion-eversion measurement was more reliable than anteroposterior laxity measurement. Although 1 examiner and 1 trial had acceptable reliability (G coefficient >/= .848), increasing the number of examiners increased reliability to a greater extent than did increasing the number of trials. CONCLUSIONS Within the range of examiner and trial facets studied, any combination of examiners or trials (or both) above 1 can change ankle laxity measurement reliability from acceptable (1 examiner, 1 trial) to highly reliable (3 examiners, 3 trials). Individuals may respond to examiners and their procedural nuances differently; thus, standardized procedures are important.