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Biomedical subjects

L Labey

Publications and source records attributed to L Labey.

7 recordsLinked to original sources
PubMed2002

Fixation strength of meniscal repair devices.

The aim of this study was to measure and compare the ultimate failure strengths and cyclic fatigue strengths of currently available meniscal suturing devices. No statistically significant difference in failure load was found between a vertical loop suture (mean 46.3 N), a horizontal mattress suture (52.5 N), the T-fix Device (47.5 N), and the 16-mm (39.2 N) and 13-mm (32.8 N) Bionix Arrow. Statistically inferior results were seen with the 10-mm Bionix Arrow (18.8 N), the S.D. Sorb Stapler (4.3 N), and the 12-mm Arthrex Meniscal Dart (10.5 N) (P<0.01). The Mitek Meniscal Repair System (28.1 N) performed intermediate, with significantly better results than the S.D. Sorb Stapler and the 12-mm Arthrex Dart, but significantly worse than the vertical and horizontal sutures, the T-fix and Bionix 16-mm Device (P<0.01). Cyclic fatigue strength was significantly less for the 10-mm Bionix Arrow, the S.D. Sorb Stapler, and the 12-mm Arthrex Meniscal Dart (P<0.01) compared to all other devices. We conclude that the 13- and 16-mm Bionix Arrow and the T-fix Device have comparable ultimate failure strengths and cyclic fatigue strengths to conventional meniscal suturing techniques. The 10-mm Bionix Arrow, S.D. Sorb Stapler, and the 12-mm Arthrex Meniscal Dart, however, have far inferior failure and cyclic fatigue strengths and their clinical application should be questioned.

Equipment Failure Analysis↗
PubMed2002

Posterior transosseous capsulotendinous repair in total hip arthroplasty : a cadaver study.

BACKGROUND: While recent clinical articles have reported a dramatic reduction in rates of total hip dislocation after posterior transosseous repair, we are not aware of any published biomechanical data to support this finding. The objectives of this study were to investigate the functional anatomy of the posterior transosseous repair and its effect on stability after total hip replacement. METHODS: Six total hip prostheses were implanted into three fresh cadavera. Three different repair situations (no repair, soft-tissue repair, and transosseous fixation) were then consecutively tested on each hip. Values for torque resistance and the angular range of motion at dislocation were recorded. Each repair was tested twice, yielding a total of thirty-six torque values and thirty-six angles of rotation. RESULTS: The transosseous repair was superior with regard to both torsion strength (four times stronger than that after no repair [p = 0.0002] and more than twice as strong as that after soft-tissue repair [p = 0.002]) and the magnitude of the angle of rotation observed prior to dislocation (an increase of 83% in comparison with that after no repair [p = 0.0005] and an increase of 46% in comparison with that after soft-tissue repair [p = 0.004]). CONCLUSIONS: In a cadaver model, posterior transosseous repair provides superior stability of a total hip replacement. Optimal surgical technique with a slightly modified approach allows greater retention of capsule and tendon length and a more anatomical reinsertion of the soft tissues.

Arthroplasty, Replacement, Hip↗
PubMed2000

Bone strains and anterior lift-off, measured with three alternative designs of tibial components of TKA.

Total knee replacement is a successful procedure with high clinical success rates. Problems are mostly initiated on the tibial side, and may be due to - amongst others - improper mechanical design of the tibial base plate. In this paper some new design concepts for the tibial component of a total knee prosthesis are presented. They are evaluated experimentally using a model for a proximal tibia, and strain gauge measurements and displacement measurements as experimental techniques. The designs are meant to yield a physiological load sharing between the trabecular and the cortical bone in the proximal tibia, and to minimize anterior lift-off of the tibial base plate. The optimal design required a metal backing of the plastic part and a thin continuous metallic rim in contact with the proximal tibial cortex. An optimal macro-composite structure within the plastic part was obtained by using thin steel wires in the transversal direction, connected to the metallic rim. With this optimal design, it was shown that the force required to close the anterior gap at simulated knee bending was smaller than 250 N, which can easily be applied clinically by an anteriorly placed clamp or bone screw.

Journal Article↗
PubMed1998

Materials selection and design for orthopaedic implants with improved long-term performance.

Design and materials selection are equally important in the development of orthopaedic implants. Two case studies are presented to illustrate this: the development of a femoral component of a total hip prosthesis and the study of alternative designs of a tibial component of a total knee prosthesis. Bioactive surface coatings may be applied to enhance the stability of fixation of the implant, even in difficult clinical cases. It is argued that an improved long-term performance of an implant can only be achieved by considering the biomechanics and biomaterials aspects of joint replacement together, and at the same time guaranteeing the quality of surgery by providing the surgeon with better pre-surgical planning systems and advanced surgical tools.

Biocompatible Materials↗
PubMed1997

A new technique for the three-dimensional study of the spine in vitro and in vivo by using a motion-analysis system.

We introduce a new method with a motion-analysis system (MAS) to study the vertebral model in vitro. Compared with the currently most accurate technique, roentgen stereophotogrammetric analysis (RSA), the difference between the RSA and the MAS is 0.12 degree +/- 1.64 degrees. An accuracy with an error of 0.08 degree +/- 1.15 degrees is determined by means of an angle gauge. Although a significant difference between the MAS and the goniometer (p = 0.04) is found around the X-axis (theta; transverse plane), it is limited to < 1 degree. The MAS provides an in-depth insight into the mechanism of the three-dimensional rotation at each vertebra in vivo. The backward inclination of the apical vertebra (AV) and forward inclination of the upper-end vertebra (UEV) around the Y-axis (phi) results in a correction of the hypokyphosis shown by the Cobb angle in the sagittal plane. The clockwise rotation of the UEV in the Z-axis (psi) leads to a reduction of the Cobb angle in the frontal plane. Additionally, the MAS as an intraoperative alternative shows different results of the derotation maneuver by the Cotrel-Dubousset instrumentation (CDI) compared with the computed tomography (CT) scan. Our method gives more direct details of the derotation not influenced by patient posture, as observed in the CT scan.

Adolescent↗
PubMed1993

The development of a physiological hip prosthesis: evaluation of the strains after implantation of a prototype of hip implant: experiment in a dry femur.

Based upon previous research on the relation between hip prosthesis designs and strain distributions in a proximal femur model, a prototype of a "physiological" hip prosthesis was designed and manufactured. Strain gauge measurements on a dry femur before and after implantation of this prosthesis were made in different loading conditions simulating one-legged stance with and without torsional loading and two-legged stance. The strains in the outer cortex were within 10% of the physiological values along the whole medial side in all measurement conditions.

Biomechanical Phenomena↗