Objective. To compare the knee-alignment angle from a full-limb radiograph (mechanical axis) with the anatomic-axis angle as measured by physical examination using a goniometer and by 2 other radiographic methods.Methods. The knee-alignment angle was measured in 114 knees of 57 subjects who had radiographic osteoarthritis (OA), with a Kellgren/Lawrence grade of >1 in at least one knee. The mechanical axis was defined as the angle formed by the intersection of 2 lines, one from the center of the head of the femur to the center of the tibial spines, and a second from the center of the talus to the center of the tibial spines. The anatomic axis was defined as the angle formed by 2 lines, each originating from a point bisecting the femur and tibia and converging at the center of the tibial spine tips. The anatomic-axis angle was measured by 3 methods: 1) physical examination using a goniometer, 2) a posteroanterior (PA) fixed-flexion knee radiograph (anatomic PA axis), and 3) an anteroposterior (AP) fulllimb radiograph (anatomic AP axis).Results. Significant correlations were found between the mechanical-axis angle and the anatomic-axis angle measured by each of the 3 methods: by goniometer (r ‫؍‬ 0.70, P < 0.0001), by anatomic PA axis (r ‫؍‬ 0.75, P < 0.0001), and by anatomic AP axis (r ‫؍‬ 0.65, P < 0.0001). The anatomic axis was offset a mean 4.21°v algus from the mechanical axis (3.5°in women, 6.4°in men), which was consistent across all methods.Conclusion. Knee alignment assessed clinically by goniometer or measured on a knee radiograph is correlated with the angle measured on the more cumbersome and costly full-limb radiograph. These alternative measures have the potential to provide useful information regarding the risk of progression of knee OA when a full-limb radiograph is not available.

Brian 1. Pease, MS, P p lanet Wigglesworth, PhDS 0 bjective and reliable measurements of subtalar joint (STJ) motion and position are absolutely necessary for clinicians involved in treatment of lower extremity dysfunctions, specifically foot orthotic fabrication, prescription, and management. Overuse injuries of the lower extremity are common, and the position and mobility of the foot and ankle have been reported to influence overuse injuries in the lower extremity (1,3,6).Because of its anatomical position, STJ position influences foot and ankle function. The STJ consists of the articulation between the talus and the calcaneus. The predominant motion at this joint is inversion/eversion, with components of abduction/ adduction and dorsiflexion/plantar flexion also present (8). The STJ provides the triplanar motions of pronation and supination. Pronation in the closed kinetic chain consists of calcaneal eversion, and adduction and plantar flexion of the talus. Supination in the closed kinetic chain consists of calcaneal inversion, and abduction and dorsiflexion of the talus.In order to clinically measure motion at the subtalar joint, bony landmarks are required. Two such landmarks are the posterior calcaneus and the navicular tuberosity.

During an unloaded squat, hamstring and quadriceps co-contraction has been documented and explained via a co-contraction hypothesis. This hypothesis suggests that the hamstrings provide a stabilizing force at the knee by producing a posteriorly-directed force on the tibia to counteract the anterior tibial force imparted by the quadriceps. Research support for this hypothesis, however, is equivocal. Therefore, the purposes of this study were 1) to determine muscle recruitment patterns of the gluteus maximus, hamstrings, quadriceps, and gastrocnemius during an unloaded squat exercise via EMG and 2) to describe the amount of hamstring-quadriceps co-contraction during an unloaded squat. Surface electrodes were used to monitor the EMG activity of six muscles of 41 healthy subjects during an unloaded squat. Each subject performed three 4-s maximal voluntary isometric contractions (MVIC) for each of the six muscles. Electrogoniometers were applied to the knee and hip to monitor joint angles, and each subject performed three series of four complete squats in cadence with a metronome (50 beats.min-1). Each squat consisted of a 1.2-s eccentric, hold, and concentric phase. A two-way repeated measures ANOVA (6 muscles x 7 arcs) was used to compare normalized EMG (percent MVIC) values during each arc of motion (0-30 degrees, 30-60 degrees, 60-90 degrees, hold, 90-60 degrees, 60-30 degrees, 30-0 degrees) of the squat. Tukey post-hoc analyses were used to quantify and interpret the significant two-way interactions. Results revealed minimal hamstring activity (4-12% MVIC) as compared with quadriceps activity (VMO: 22-68%, VL: 21-63% of MVIC) during an unloaded squat in healthy subjects. This low level of hamstring EMG activity was interpreted to reflect the low demand placed on the hamstring muscles to counter anterior shear forces acting at the proximal tibia.

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Study Design: Repeated measures analysis o i joint angle e i i~t s on hip and k n w muscle cltrtromyographic IEMGI activitv. Objectives: To simultan~~usly determine angle-dependent changes in maximal voluntary isometric contraction IMVICI torque and EMG activity during hip extension and knee ilexion. Background: Procedures ior normalizing EMG data and ior determining torque-angle relationships for various joint motions both entail asking suhjects to exert an MVIC. The implicit assumption in t h r w paradigms is that magnitude of the EMG response is at a constant, m.iximum level so that ohservcd angle-tlepcndmt variations in torque are due to mechanical iactors, such as muscle length and muscle moment arm.Methods and Measures: Fifty suhjects (25 men and 25 women1 particip.itcd in this study (age, 23.5 + 4.6 y; range, 18-38 y). Subjects periormed maximal isometric knee ilexion at 4 kncv angles and maximal isometric h~p extension at 4 hip angles. The dependent variahlrr were nnrmalizrd root-mean-square EMG and torque. The process ior normalizing EMG and torque data consisted o i determining the largc3t mean value ior each suhject across tcrting positions for the muscle o i interest. That value was designated as corrcqmnding to 100% MVIC, and all other data ior that muscle were expressed as a percentage of the MVIC value. Repeated measures was used to determine angle-dependent changes in normalized MVICtorque and MVIC-EMG values ior each muscle group. Results: Mean torque-angle relationships were generally consistent with previous r e p m , though ~~n s i d e r d~l e intersuhject variability was observed. There were signiiicant .inglc-dependent diiierenccr in maximal EMG ior Ix)th the hamstring and gluteus maximus muscles. Worrell, Duke Universitv Medical Center, Deptartment oi Physical and Occupational Therapy PO 3965, Durham, NC 27710. E-mail: ~vorreOO6@mc.duke.edu xperimental approache.5 to the study of neuromuscular function frequently entail asking subjects to perform a maximal voluntary isornetric contraction (MVIC) of selected muscle groups. This approach is commonly used for amplitude normalization of electroinyographic (EMG) activity in order to determine the potential efficacv of various strengthening exercises by comparing the relative activity elicited by each e x e r c i~e . " . ' . ' .~"~ Maximal voluntary isometric contraction has also been used to determine in vivo torque-angle relationships of various joint motions by having subjects exert an MVIC at multiple points in the range of lnotion.~.~ t.21.22 The implicit assumption in these paradigms is that the instruction to perform an MVIC elicits a constant, rnaxi~nal level of motor iunit activity in the muscle of interest.The question of whether performance of an MVIC results in a

The purpose of this study was to compare isokinetic strength and flexibility measures between hamstring injured and noninjured athletes. Sixteen university athletes with history of hamstring injury were matched by motor dominance, sport, and position to sixteen university athletes without history of hamstring injury. Each subject was tested for concentric and eccentric quadriceps and hamstring peak torque and reciprocal muscle group ratios on a Kinetic Communicator(R) (KIN-COM) dynamometer at 60 degrees /sec and 180 degrees /sec. Each subject's hamstring flexibility was determined by passively extending the knee while the hip was maintained at 90 degrees of flexion. Analysis of variance indicated that the injured extremity was significantly less flexible than the noninjured extremity within the hamstring injured group, and the hamstring injured group was less flexible than the noninjured group. No significant strength differences existed between the hamstring injured and noninjured group on any isokinetic measure evaluated. The importance of assessing hamstring flexibility is emphasized. J Orthop Sports Phys Ther 1991;13(3):118-125.

Background and Purpose. The volume of all limbs can be determined by water displacement methods or calculations derived from girth measurements. The purpose of this study was to determine the concurrent validity of calculated volume and water displacement volume measurements. Subjects. Both upper extremities of 14 women with lymphedema were measured. Methods. Volumetric measurements were taken with a volumeter, and circumferential measurements were taken with a tape measure. Calculated volume was determined by summing segment volumes derived from the truncated cone formula. Pearson product moment correlations, paired t tests, and linear regression tests were used to assess relative association and absolute differences between calculated and actual volumes. Results. The correlation coefficient for calculated volume versus upper extremity minus fingers (UE-F) water displacement volume was .99. Paired t tests showed differences between calculated volume and UE-F water displacement volume (t=−3.88, mean difference=−95.62 mL), and the linear regression slope was 0.83 with an intercept of 255.28 mL. Discussion and Conclusion. Calculated volume measurements were highly associated with measurements based on water displacement; therefore, clinicians should feel confident in using either calculated volume or water displacement volume. The differences, however, indicated that the measures were not interchangeable. Thus, clinicians should not mix or substitute measurement methods with a single patient or in a single study.

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