PLANTAR PRESSURE DISTRIBUTION AND FORCES MEASURED DURING SLALOM AND GIANT SLALOM TURNS PERFORMED BY ELITE SKIERS

The purpose of the study was to measure plantar force and pressure distribution during slalom (S) and giant slalom (SG) runs performed by elite professional ski instructors. Three elite professional ski instructors performed three slalom and two giant slalom runs. All test trials were recorded synchronously with a video camera and a plantar pressure distribution. The total maximum forces compared between left and right foot for foot position during the turn are not significantly different. However, the total maximal force is about 1.2 to 2 times larger for the outside foot. The regional maximum mean pressure is applied under the medial aspect of the forefoot and the heel. This provides more steering control and forces during both types of turns. It should be noted that the inside foot has less steering contribution for S and GS turns

EFFICACY OF FUNCTIONAL KNEE BRACES IN SPORT: A REVIEW

The purpose of this work was to review previously published studies on functional knee braces in an attempt to understand their functionality. A better comprehension of the effects of functional knee bracing could assist ACL-deficient athletes in deciding whether or not these devices could be beneficial in supporting their unstable knee joint during sports. Results showed that functional knee braces alter knee joint kinematics, kinetics and muscle activity. Their mechanism of action, however, might be attributed to the modification of proprioception and motor patterns of the lower limb rather than their mechanical stabilizing effect

GAIT DOES NOT RETURN TO NORMAL FOLLOWING TOTAL HIP ARTHROPLASTY: IMPLICATIONS FOR A RETURN TO ATHLETIC ACTIVITIES

The purpose of this study was to determine the effect of total hip arthroplasty (THA) on the biomechanics of the lower extremity during walking. Twenty THA patients and 20 healthy control participants performed several trials of level walking for which three-dimensional (3D) hip, knee and ankle angles, forces, moments and powers were recorded and calculated. Results revealed that the gait mechanics of THA patients do not return to normal following surgery, especially during the transition from double- to single-limb stance. These patients produced lower hip abduction moments that are perhaps a result of hip abductor weakness. Kinematic and kinetic adaptations at the distal joints were also found. Hip musculature deficiencies should be addressed in rehabilitation programs, especially if patients want to return to athletic activities

DO PEOPLE WITH UNILATERAL CAM FAI FAVOUR THEIR SYMPTOMATIC LEG DURING MAXIMAL DEPTH SQUATS?

Cam Femoroacetabular Impingement (FAI) is caused by an abnormally convex femoral head-neck junction and can damage the peripheral acetabulum in activities requiring a large hip range of motion (ROM). This study analyzed the three-dimensional (3D) ground reaction forces (GRF) and moments (GRM) and the resultant GRF of the symptomatic and asymptomatic legs in participants with unilateral cam FAI during a maximal depth squat. Seventeen participants with unilateral cam FAI performed 5 maximal depth squats with each leg on a separate forceplate. No significant differences were found between the two legs. These results indicate that participants with cam FAI do not favour their affected leg during maximal depth squats

LOWER LIMB BIOMECHANICAL ADAPTATIONS TO TOTAL HIP ARTHROPLASTY EXIST DURING SITTING AND STANDING TASKS

The purpose of this study was to determine the effect of total hip arthroplasty (THA) on lower limb mechanics during the tasks of sit-to-stand and stand-to-sit. Twenty THA patients and 20 control participants performed three trials of sit-to-stand and stand-to-sit. Three-dimensional (3D) hip, knee and ankle angles were calculated. Forces, moments and powers were obtained with an inverse dynamics approach. THA patients exhibited lower joint forces and moments, as well as lower hip flexion and higher abduction angles, near seat-on and seat-off. These results indicate that THA patients were able to adopt a strategy that allowed them to reduce loading at the operated lower limb joints. Although such a strategy may be desirable given that higher loads can increase friction and accelerate wear of the prosthesis, reduced loading may be an indication of inadequate muscle strength that needs to be addressed

A COMPARISON OF PRE- AND POST-OPERATIVE THREE-DIMENSIONAL HIP KINEMATICS DURING LEVEL WALKING IN PATIENTS WITH CAM FEMOROACETABULAR IMPINGEMENT

Cam femoroacetabular impingement (FAI) is an idiopathic progressive pathological condition of the hip joint characterized by an abnormal bony protuberance on the femoral head-neck junction (Beck, Leunig, Parvizi, Boutier, Wyss & Ganz, 2004). During the limits of hip range of motion (ROM), the protuberance jams into the acetabulum (Ganz, Parvizi, Beck, Leunig, Nötzli & Siebenrock, 2003), resulting in acute hip and groin pain (Beaulé, LeDuff, & Zaragoza, 2007). Impingement has also been shown to occur within normal ROM of the hip during basic tasks such as walking, reducing peak hip abduction angles as well as hip frontal and sagittal ROM (Kennedy, Lamontagne & Beaulé, 2009). Cam FAI primarily affects young and athletic males (Ganz, Parvizi, Beck, Leunig, Nötzli & Siebenrock, 2003), and is common in hockey, football, soccer, rugby, martial arts and tennis athletes (Philippon, Schenker, Briggs & Kuppersmith, 2007). Restricted hip mobility during activities requiring low ROM suggests more pronounced limitations during demanding athletic tasks. Surgical procedures have been developed to remove the bony abnormality from the femoral head-neck junction with the objective of attenuating hip pain and restoring normal hip biomechanics, enabling athletes to return to sport. The purpose of this study is to assess the clinical outcome of cam FAI corrective surgery by comapring pre-operative and post-operative three-dimensional (3-D) hip kinematics during level walking

Double label autoradiography : an improvement

A convenient method for double-label autoradiography is described that uses an aqueous mountant, Gelutol (polyvinyl alcohol), which keeps the gelatin spacer in the final autoradiograph permanently swollen to a thickness of around 18 microns in contrast to its 5 microns thickness during exposure of the autoradiograph. This greatly improves optical discrimination between upper and lower layers without the loss of sensitivity or resolution that would result if a 18 microns spacer were used during exposure

Annual and monthly range fidelity of female boreal woodland caribou in respons to petroleum development

Petroleum-sector development in northern Alberta, Canada has been implicated as one factor influencing the decline of boreal woodland caribou (Rangifer tarandus caribou). Previous research showed that caribou are farther from petroleum-sector disturbances within their home range than expected. As petroleum development increases, the distance caribou can selectively place themselves relative to industrial disturbance must decrease, because distances between disturbances decrease. Conceptually, the number of local disturbances becomes so large that caribou either abandon their local avoidance behaviour or leave their traditional home range. We evaluated whether an intense petroleum- development event in northern Alberta was sufficient to result in home range abandonment by female woodland caribou. Using well locations as an index of petroleum development, we found that caribou studied from 1992 to 2000 did not change their annual or monthly range fidelity as a function of development intensity. Caribou remained in peatland complexes containing a large number of petroleum-sector disturbances rather than move to new areas, presumably because the risks of dispersing across upland habitat to reach other suitable habitat are high. Such range fidelity may have fitness consequences for woodland caribou if they suffer greater predation in areas where petroleum development is occurring