Publications (6)18.39 Total impact
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Article: The relationship of lower extremity alignments and anterior knee laxity to knee translations during a vertical drop landing.
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ABSTRACT: Background Lower extremity alignment (LEA) measures have been linked to non-contact anterior cruciate ligament (ACL) injuries. High deceleration movements have been implicated in non-contact ACL injury mechanisms; and, evidence suggests that greater anterior tibial translation (ATT) may occur in healthy knees that demonstrate greater laxity compared to a stiff knee. Objective To determine the relationship between LEA measures, KT1000 anterior laxity values and ATT during landings using biplane fluoroscopy. Design Descriptive laboratory study. Setting Controlled laboratory setting. Subjects had a sport participation history at the high school or college level. Participants 16 healthy adults (10 females; 6 males). Assessment of risk factors KT1000 values and seven measures of LEA (pelvic angle, hip anteversion, Q-angle, genu recurvatum, tibial torsion, navicular drop and rear foot angle) were measured. Main outcome measurements Subjects performed a drop-landing (40 cm) while being filmed using a high speed, biplane fluoroscopy system. Initial, peak and excursions for ATT were calculated and regression analysis used to determine the relationships. Results KT1000 values were positively correlated with peak ATT values for group (r=0.89) and both genders (males, r=0.97; females, r=0.93) (p=<0.0001). Navicular drop was also significantly correlated to maximal ATT (r=0.56) (p<0.05). No other LEA was significantly correlated with initial, peak or range of ATT (all p>0.05). Conclusion A strong relationship was observed between passive anterior knee laxity measured via KT1000 and ATT experienced during a landing activity in otherwise healthy persons. Navicular drop was significantly correlated with ATT during landing and is a relationship that warrants further investigation as it relates to ACL injury. Anterior knee laxity measured via the KT1000 should be considered in non-contact ACL injury risk assessment for all athletes.British journal of sports medicine 04/2011; 45(4):350. · 2.55 Impact Factor -
Article: The relationship between indicators of 'high risk' landing mechanics and knee translations in female athletes.
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ABSTRACT: Background When assessing non-contact anterior cruciate ligament (ACL) injury risk, prospective measures of high valgus knee angle (>8°) and high knee abduction moment (>25 Nm) measured during landings have been shown to predict ACL injury in female athletes. Objective The purpose of this study was to determine the relationships between these 'high risk' landing variables and anterior tibial translation (ATT) and lateral tibial translations (LTT). We hypothesised individuals exhibiting high knee valgus angles and/or knee abductor moments will also experience larger ATT and/or LTT during a landing. Design Descriptive laboratory study. Setting Controlled laboratory setting; highly active recreational, high school and college athletes. Participants 15 healthy female athletes (26.1 ± 6.3 years; 167.9 cm ± 6.3, 58.2 ± 5.2 Kg). Assessment of risk factors The subjects performed a drop-landing motion by stepping off a 40 cm platform onto a force plate and then immediately performed a maximum effort vertical jump. Main outcome measurements Knee abductor moment and valgus angle were measured using motion capture and inverse dynamic analyses. ATT and LTT were measured concurrently using high-speed biplane fluoroscopy with sub-millimeter accuracy. Results No significant relationship was noted between peak knee valgus angle (range: -2.9° to 20.8°) and peak ATT or LTT (r=-0.17, r=-0.42, respectively); nor, between peak knee abductor moment (range: 2.5-37.2 N*m) and peak ATT or LTT (r=-0.23, r=-0.09, respectively)(p>0.05). Conclusion The results did not support the hypothesis that high knee valgus angles or abductor moment values will lead to larger ATT or LTT during landing. Although compelling evidence has identified high knee valgus angle and high knee abductor moment as predictive of ACL injury, these parameters did not result in greater knee translations during landing.British journal of sports medicine 04/2011; 45(4):350. · 2.55 Impact Factor -
Article: Effects of walking poles on lower extremity gait mechanics.
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ABSTRACT: The purpose of this study was to determine whether walking with poles reduces loading to the lower extremity during level over ground walking. Three-dimensional gait analysis was conducted on 13 healthy adults who completed 10 walking trials using three different poling conditions (selected poles, poles back, and poles front) and without the use of poles (no poles). The inverse dynamics approach was used to calculate kinetic data via anthropometric, kinematic, and kinetic data. All walking with poles conditions increased walking speed (P = 0.0001-0.0004), stride length (P < 0.0001), and stance time (P < 0.0001) compared with the no poles condition. There also was a decrease in anterior-posterior GRF braking impulse (P = 0.0001), a decrease in average vertical GRF walking with poles (P < 0.0001-0.0023), and a decrease in vertical (compressive) knee joint reaction force (P < 0.0001-0.0041) compared with the no poles condition. At the knee, extensor impulse decreased a 7.3% between the no poles and selected poles conditions (P = 0.0083-0.0287) and 10.4% between the no poles and poles back conditions (P < 0.0001). The support moment was reduced between the no poles and poles back (P = 0.0197) and poles front (P = 0.0002) conditions. Ankle plantarflexor work (A2) was reduced in the poles-front condition (P = 0.0334), but no differences were detected in all other ankle, knee or hip power and work variables (P > 0.05). There were differences in kinetic variables between walking with and without poles. The use of walking poles enabled subjects to walk at a faster speed with reduced vertical ground reaction forces, vertical knee joint reaction forces, and reduction in the knee extensor angular impulse and support moment, depending on the poling condition used.Medicine & Science in Sports & Exercise 01/2001; 33(1):142-7. · 4.43 Impact Factor -
Article: Intra-articular knee joint effusion induces quadriceps avoidance gait patterns.
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ABSTRACT: (1) To identify adaptations caused by intra-articular knee joint effusion during walking and (2) to determine if knee joint effusion may be a causative factor in promoting quadriceps avoidance gait patterns. Gait testing of 14 healthy individuals who underwent incremental saline injections of the knee joint capsule.Background. Gait adaptations have been reported in the literature for knee injured and rehabilitating individuals. Knee joint capsular afferent activity can influence knee joint function. Gait analysis was employed in a pre- and post-test, repeated measures design to determine lower extremity joint kinematics, kinetics, energetics and thigh EMG adaptations due to intra-articular knee joint effusion. Knee effusion caused an increase in hip and knee flexion through the stance phase. Knee extensor torque, impulse and negative and positive work were diminished with increased effusion levels. Quadriceps activity decreased and hamstring activity increased due to intra-articular knee joint effusion. These adaptations cannot be attributed to an injury, surgery or rehabilitation. Thus, the results of this experiment suggest knee joint capsular distention, via knee joint effusion, may be responsible for many gait adaptations reported for knee injured individuals in previous investigations. Knee joint effusion and the subsequent capsular distention can cause major alterations in the normal gait cycle and can be considered a causative factor promoting the acquisition of quadriceps avoidance gait patterns. This study provides reference data on the effects of intra-articular knee joint effusion on gait parameters by which future studies of injured or rehabilitating individuals can be compared.Clinical Biomechanics 04/2000; 15(3):147-59. · 2.07 Impact Factor -
Article: Lower limb stability with ACL impairment.
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ABSTRACT: Repeated measures (3 separate day sessions) to determine test reliability; single-session repeated measures to compare stability between limbs. To develop a functional test measuring dynamic stability that is capable of differentiating between the injured and uninjured lower limb in 2 populations: (1) people with anterior cruciate ligament deficiency (ACLd) and (2) people with anterior cruciate ligament reconstruction (ACLr), and to establish the reliability of this test. Many functional tests of the lower limb used by clinicians, such as the 1-legged hop for distance, the 1-legged hop for time, the vertical jump, the triple hop for distance, shuttle run, and single-limb standing, do not allow the clinician to discern differences between function in the injured and uninjured limbs. Twenty-five nonimpaired subjects (14 men, 11 women, aged 31.2 +/- 9.1 years), 11 subjects with ACLr (9 men, 2 women, aged 26.3 +/- 10.4 years), and 13 subjects with ACLd (5 men, 8 women, aged 40.4 +/- 12.6 years) were tested. Twelve nonimpaired subjects participated in 3 testing sessions to determine the reliability of the force plate measures. Ground reaction forces (vertical, medial-lateral, and anterior-posterior) were measured while the subjects performed 1-legged hop and step-down tests onto a force plate. Stability was defined as the ability to transfer the vertical projection of the center of gravity to the supporting base and keep the knee still. A repeated-measures analysis of variance (2-factor; limbs by trials) was used to compare the stability between limbs. The majority of the measures used to calculate dynamic stability were reliable. Moreover, the data provide normal standards of functional knee stability for step-down and hop tests. In the step-down test, changes in vertical force did identify dysfunction in the injured limb (stabilization time = 1527 +/- 216 ms) compared to the uninjured limb (stabilization time = 892 +/- 498 ms) for subjects with ACLr. The normal standards may serve as a reference for comparing functional differences in ACLr or ACLd populations. The vertical force parameter during a step-down may be useful as an outcome measure to monitor progress during rehabilitation.Journal of Orthopaedic and Sports Physical Therapy 09/1999; 29(8):444-51; discussion 452-4. · 3.00 Impact Factor -
Article: Internal and external tibial rotation strength after anterior cruciate ligament reconstruction using ipsilateral semitendinosus and gracilis tendon autografts.
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ABSTRACT: The internal and external tibial rotation torques of subjects who had undergone anterior cruciate ligament reconstruction using semitendinosus and gracilis tendon grafts were measured to determine whether harvest of the tendons results in weakness of tibial internal and external rotation. Cybex NORM dynamometer examinations were performed to measure internal and external tibial torque at angular velocities of 60, 120, and 180 deg/sec in 23 subjects. The sex-specific average torque data of the reconstructed limbs were compared with those of the contralateral limbs. Relative internal and external torque scores were calculated for each subject by subtracting the peak torque of the reconstructed knee from that of the contralateral knee. These relative scores were averaged and compared with the null hypothesis that each score should be statistically similar to zero. Subjects were evaluated at an average of 51 +/- 40 months postoperatively. The mean relative internal torque scores of the reconstructed limbs showed a statistically significant decrease from those of the contralateral limbs at all angular velocities. The mean relative external torque scores of the reconstructed limbs were statistically similar to those of the contralateral limbs at all angular velocities. Subjects who had undergone ligament reconstruction using semitendinosus and gracilis tendons demonstrated internal tibial rotation weakness in their reconstructed knees compared with their contralateral knees at all angular velocities tested. These results suggest that semitendinosus and gracilis tendon harvest causes weakness of internal tibial rotation.The American Journal of Sports Medicine 28(4):552-5. · 3.79 Impact Factor
