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Biomedical subjects

P Renstrom

Publications and source records attributed to P Renstrom.

6 recordsLinked to original sources
PubMed1989

Cross-country skiing injuries and biomechanics.

Cross-country skiing exercises most of the joints, muscles and tendons in the body giving the skier an all around workout. This, in combination with a low incidence of injury, makes cross-country skiing an ideal recreational and competitive sport. The new skating techniques developed during the last decade have resulted in greater velocity. The maximum speed during the diagonal stride technique is 6 m/sec compared to 8 to 9 m/sec when skating and double poling. Top-level skiers today use strong and ultra light skis of fiberglass and graphite. The ski weight is less than 500g. Today's skating technique does not require any waxing and only the cambered portion of the ski is waxed when performing the diagonal stride. The preparation of the ski course has improved with the development of special track machines. This allows top-level skiers to reach 60 to 80 km/h on downhill slopes, which has resulted in an increased risk of injury. Because cross-country skiing takes place wherever snow is available, it is difficult to establish accurate injury rates in comparison to alpine skiing which is performed on very specialised terrain at ski areas. Studies estimate the cross-country ski injury rate in Sweden to be around 0.2 to 0.5 per thousand skier days. A prospective study of cross-country ski injuries conducted in Vermont revealed an injury rate of 0.72 per thousand skier days. 75% of the injuries sustained by members of the Swedish national cross-country ski team during 1983 and 1984 were overuse injuries while 25% resulted from trauma. The most common overuse injuries included medial-tibial stress syndrome, Achilles tendon problems and lower back pain. Most common among traumatic injuries were ankle ligament sprains and fractures, muscle ruptures, and knee ligament sprains. Shoulder dislocation, acromioclavicular separation and rotator cuff tears are not infrequent in cross-country skiing. Injuries to the ulnar collateral ligament of the metacarpal phalangeal joint of the thumb (Stener's lesion) is the most common ski injury involving the upper extremity. Cross-country skiers 16 to 21 years of age complained more frequently of mild lower back pain than similarly aged non-skiers. This may result from repetitive hyperextension motions during the kick phase and the recurring spinal flexion and extension during the double poling phase. Repeated slipping on hard and icy tracks infrequently produce partial tears or microtrauma in the muscle tendinous units of the groin.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1988

Strain in the lateral ligaments of the ankle.

Strain was measured in the normal anterior talofibular ligament (ATF) and the calcaneofibular ligament (CF) using Hall effect strain transducers in five cadaveric ankles. These measurements were made in both ligaments with the ankle in neutral position and with the foot moving from 10 degrees dorsiflexion to 40 degrees plantarflexion in an apparatus that permits physiologic motion. The ankle ligaments were then tested with the foot placed in six different positions that combined supination, pronation, external rotation, and internal rotation. In the neutral position, through a range of motion of 10 degrees dorsiflexion to 40 degrees plantarflexion, the anterior talofibular ligament underwent an increasing strain of 3.3%. No significant strain increase was found with internal rotation. The only significant difference from the strains at the neutral position was in external rotation, which decreased strain 1.9%. In all positions, increased strain occurred with increased plantarflexion. The calcaneofibular ligament was essentially isometric in the neutral position throughout the flexion arc. The calcaneofibular ligament strain was significantly increased by supination and external rotation. However, with increasing plantarflexion in these positions, the strain in the calcaneofibular ligament decreased. Therefore, plantarflexion has a relaxing effect on the calcaneofibular ligament. Thus, the anterior talofibular and calcaneofibular ligaments are synergistic, such that when one ligament is relaxed, the other is strained and vice versa.

Adult↗
PubMed1987

A comparison of ankle taping methods.

Four different types of ankle tapings were applied to a model of the human ankle joint. The model was constructed so that it contained a hinge to represent the ankle joint and had an external shape identical to a real ankle and foot. A mechanical testing machine was used to apply moments to the model at a controlled loading rate. From these tests, the deflection and torque to failure and the tangent stiffness were determined. Loadings of an ankle joint in vivo revealed that the angular deflection to initiate pain was approximately 8 degrees. Only the figure eight and full tapings could withstand 8 degrees of angular displacement on the ankle model prior to failure. Analysis of athletic trauma revealed that torques of 420 Nm could be applied to the ankle joint. Only the figure eight taping with three or more wraps has adequate strength to withstand this moment, and thus this taping is recommended. In practice, tapings failed by shearing away from the surface of the foot of shrinking rather than by rupture of the tape.

Ankle Injuries↗
PubMed1986

Trauma in sport.

Explore the source record for details and available documents.

Athletic Injuries↗
PubMed1981

On the distribution and elimination of haloperidol in cholecystectomized patients.

A single oral dose of haloperidol was given to 19 patients prior to cholecystectomy. The concentration of haloperidol was assessed in serum, urine, fatty tissue, liver tissue, choledochal bile and bile bladder contents. The biological half-life of the drug in the serum was 25.1 +/- 12.9 hours, which is comparable to that in healthy volunteers. Only minute amounts of the drug were excreted with the urine. The drug concentration was only slightly elevated in choledochal bile but in the bile bladder contents it was about 11 times higher than that in the serum. The low concentration of haloperidol in the bile indicated that there was no substantial enterohepatic recirculation of the drug in this patient material. The concentration of haloperidol in fatty tissue was about 20 times, and in liver tissue 900 times higher than that in the serum. The corresponding figures for intramuscular administration of haloperidol were 10 and 325, respectively. A possible relationship between the side-effects and the route of administration is discussed.

Adipose Tissue↗