Biomedical subjects

Benedikt Friemert

Publications and source records attributed to Benedikt Friemert.

3 recordsLinked to original sources

PubMed2006

Biological response to a new composite polymer augmentation device used for cruciate ligament reconstruction.

A resorbable composite augmentation cord braided of poly(L-lactide) and poly(L-lactide-co-glycolide) fibers was designed for the temporary protection of repaired cruciate ligaments. This study examined the biocompatibility of the new device and the influence of augmentation duration on ligament healing in a sheep model. The anterior cruciate ligament (ACL) was cut close to the femoral insertion and reinserted with sutures. The repaired ACLs were augmented with the slowly degrading new composite cord and alternatively with a faster degrading polydioxanone cord (PDS). A tendon graft group (gold standard) served as control. Histological evaluation and biomechanical testing were performed after 6 months. The composite cord showed no signs of degradation, whereas the PDS was intra-articularly resorbed. Both devices showed only minor foreign body reactions, proving their good biocompatibility. However, 9 of 11 composite cords had ruptured too early because of fatigue at the bone tunnel entrances. All operated knees were less stable than the nonoperated collateral joints. Knees equipped with the composite cord showed the largest anterior instabilities, whereas the PDS-augmented group exhibited in some cases knee instabilities comparable with that of the tendon group. A positive effect of a longer mechanical protection by a slowly degrading augmentation could not yet be shown. The fatigue strength of the device still needs improvement.

Animals↗

PubMed2006

Therapeutic cooling: no effect on hamstring reflexes and knee stability.

PURPOSE: Stretch reflexes contribute to joint stiffness, but the effects of therapeutic cooling on these reflexes are unknown. Therapeutic cooling is frequently used in knee rehabilitation, for instance, after rupture of the anterior cruciate ligament. Cooling a joint can affect nerve conduction velocity and the function of sensory organs. Such changes in neuromuscular coupling could reduce knee stability and increase the risk of knee injury. The aim of the present study was to evaluate whether there are negative effects of knee cooling on the hamstring short and medium latency reflex responses or on the anterior tibia trajectory after mechanically induced tibia translation. METHODS: In 15 healthy volunteers, the latency and size of short latency and medium latency reflex responses of hamstring muscles were assessed before and after 20 min of cold therapy of the knee joint as applied in rehabilitation. Reflex responses were evoked by a mechanically induced posterior-anterior tibia translation during standing. Reflexes were recorded by surface electromyography. The distance of anterior tibia motion and its velocity were assessed by potentiometric position transducer. RESULTS: Local cold therapy of the knee did not alter the latency or the size of short or medium latency responses. Also, the extent and the velocity of tibia translation were unchanged after knee cooling. CONCLUSION: Cold therapy does not seem to adversely influence the spinal reflexes of the hamstrings induced by anterior tibia translation. As neuromuscular coupling was not significantly affected, the cold therapy, as performed in the present study, is not likely to increase the risk of knee injury.

Adult↗

PubMed2005

The peroneal reaction time (PRT)--reference data in a healthy sample population.

BACKGROUND: Acute ankle sprains can result in severe residual symptoms, such as chronic ankle instability from weakness of the ligamentous complex or neuromuscular deficits. Measuring peroneal reaction time (PRT) has become a commonly accepted procedure for evaluating proprioceptive deficits. METHODS: The present experimental study was conducted to determine the effects of anthropometric factors on PRT in 120 healthy volunteers. The patients were asked to stand on a platform with a tilting mechanism. Surface electrodes were used to record peroneal muscle activity in response to sudden inversion stress. The reaction of the peroneal muscles was analyzed using electromyography. RESULTS: The statistical analysis showed similar intra-individual and inter-individual values for PRT. The results for the muscle groups measurements, however, varied considerably. PRT seems to increase significantly with age (long peroneal muscle: p < 0.0001, short peroneal muscle: p = 0.004). CONCLUSIONS: PRT was found to be an objective parameter that is unaffected by extrinsic and intrinsic factors. The present study, however, also showed that PRT significantly increases with age. As for studies on PRT, as well as for clinical routine, it is important to consider the patients' ages.

Adolescent↗