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Purpose: Displaced tibial eminence fractures require surgical fixation in order to obtain a stable knee joint. Suture fixation with FiberWire seems to be the most favorable therapeutic option. Biomechanical studies show failure of this technique most commonly due to a suture cutout with subsequent fracture of the tibial eminence fragment. The goal of this study is to compare the biomechanical properties of three different techniques of suture fixation using FiberWire. Methods: Bone mineral density was evaluated in 18 human knee specimens by pqCT, and three similar groups were formed. A standardized anterior tibial eminence fracture was created, and suture fixation was performed using one of three different techniques in 6 specimens each. Cyclic and destructive testing was conducted. Results: Significant differences between the three techniques could be shown neither in the cycles needed to achieve a steady state nor in a failure load or initial stiffness. Almost all specimens failed by suture cutout. Conclusion: The presented modification of the existing technique for suture fixation of tibial eminence fractures did not lead to an increased initial stability nor did it lower the rate of suture cutout. All tested suture techniques showed comparable initial stiffness and failure load. [ABSTRACT FROM AUTHOR]

Introduction: A tibial nail with fixed-angle locking screws intends to combine the advantages of angular stability and intramedullary stabilization in extraarticular proximal tibial fractures. The goal of this study is to analyze if the angle stable tibial nail (ASN) is biomechanically more stable than an established conventional standard nail (CN). Methods: Two types of nails were compared on a series of ten matched pairs of human tibiae. After setting a proximal tibial defect fracture, the intramedullary stabilized tibiae were axially loaded starting from 100 N increasing in steps of 100 N after every 200 cycles until failure was reached. Failure was defined as deformation of the fracture gap, fracturing of the bone or the implant. Results: The two types of nails showed no significant difference in terms of maximum tolerated load, maximum cycles repeated or axial deformation of the bone-implant construct. The mean load at failure was 1,365 N for the CN and 1,195 N for the ASN. The mean axial deformation for conventional (19 mm) and angle stable nail (21 mm) did not differ significantly. Slightly less nail or screw loosening was noticed with the fixed-angle nail. Conclusion: No significant difference in stability between the two compared implants could be demonstrated. A trend could be shown indicating that the rate of nail loosening in the proximal osteotomized part of the bone was lower for the angle stable nail. This trend, however, could not be substantiated statistically. [ABSTRACT FROM AUTHOR]

Purpose: To identify the wrist tendon most effectively maintaining the trapezial space in interpositional arthroplasty in osteoarthritis of the carpometacarpal joint of the thumb. Methods: The morphometrics of the os trapezium and the tendons of the flexor carpi radialis, extensor carpi radialis longus, and abductor pollicis longus were determined. The stiffness and compressive loading characteristics of the rolled-up tendons were compared to the os trapezium. Results: No significant morphometric differences between the three tendons were found. The mass and volume of the trapezium was significantly larger when compared to the tendon balls. No significant differences in the compressive loading resistance were found between the tendons, but the mean stiffness was 85% lower when compared to the os trapezium. Conclusions: Neither tendon material approached the volume nor the stiffness provided by the os trapezium. Any tendon is considered to insufficiently maintain the trapezial space following trapeziectomy. [ABSTRACT FROM AUTHOR]

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Abstract: Background: Heterogeneous distribution of tendon strain is considered to contribute to the development of the Achilles tendon overuse injuries. Force distribution between the three portions of the triceps surae muscle and position of the calcaneus might affect the extent of strain differences within the Achilles tendon. Purpose of this study was to determine the effect of changes in force distribution within the triceps muscle and changes in calcaneus position on intratendinous strain distribution of the Achilles tendon. Methods: Five cadaveric Achilles tendons including complete triceps surae and calcaneus were dissected. Specimens were mounted in a loading simulator allowing independent force application for the three parts of triceps muscle and changes calcaneus eversion and inversion position. Strain was determined in different aspects of the Achilles tendon. Findings: Changes of calcaneus position resulted in intratendinous strain differences up to 15%, changes in force distribution within the triceps muscle resulted in strain differences up to 2.5%. Calcaneal eversion was connected to a higher degree of strain in medial tendon portions, while inversion increased strain in lateral tendon portions. Interpretation: Medio-lateral, proximo-distal and dorsal–ventral distribution of tendon strain is rather influenced by kinematics of the subtalar joint than by muscular imbalances within the triceps muscle. Clinical movement analyses should focus on motion pattern combining rearfoot eversion with high Achilles tendon load. The results indicate that twist of the Achilles tendon fascicles seems of paramount importance in balancing tendon strain. To get more insight into the Achilles tendon injuries pathogenesis future research should focus on methods monitoring heterogeneous distribution of strain in vivo. [Copyright &y& Elsevier]