Biomedical subjects

D Lanctot

Publications and source records attributed to D Lanctot.

7 recordsLinked to original sources

PubMed2000

Effects of fluid flow on the in vitro degradation kinetics of biodegradable scaffolds for tissue engineering.

Scaffolds fabricated from biodegradable polymers are used extensively in the field of tissue engineering. Many of these scaffolds are subjected to fluid flow, either in vivo or in bioreactors ex vivo. The goal of this study was to examine the effects of fluid flow on the degradation characteristics and kinetics of scaffolds in vitro. Scaffolds with different porosity and permeability values were fabricated using a copolymer of polylactic acid and polyglycolic acid. These scaffolds were subjected to degradation in phosphate buffered saline at 37 degrees C for up to 6 weeks under two test conditions: static and flow (250 microl/min). The porosity of the scaffolds decreased up to 2 weeks and then increased, while the elastic modulus first increased and then decreased over the course of the study. The mass and molecular weight of the scaffolds exhibited a steady decrease up to 6 weeks. The results further indicated that lower the porosity and permeability of the scaffolds, the faster their rate of degradation. Additionally, fluid flow decreased the degradation rate significantly. It is possible that the high rates of degradation observed here were due to autocatalysis of the degradation reaction by the acidic degradation products.

Biocompatible Materials↗

PubMed2000

Knot security in simple sliding knots and its relationship to rotator cuff repair: how secure must the knot be?

We sought to determine which simple sliding knot configurations would have adequate strength for rotator cuff repair. Four knot configurations were tied with both No. 1 polydioxanone suture and No. 2 Ethibond suture (Ethicon, Somerville, NJ) using 3 different tying techniques: hand-tie, standard knot pusher, and cannulated double-diameter knot pusher. The knots were then tested to failure on a materials testing system. The weakest standard knot configuration was S=S=S=S. The other 3 knot configurations (S//S//S//S, SxSxSxS, and S//xS//xS//xS) generally failed in the 35 to 50 N range. Ultimate strength in this range can be shown to be adequate to withstand, without suture failure, a maximal contraction of a repaired rotator cuff tear within the rotator crescent, assuming certain conditions are met (suture anchors placed 1 cm apart, 2 sutures per anchor). More complex knots are not necessary for adequate knot security. However, the same configuration with only 1 suture per anchor will not be strong enough because the suture will fail under maximum physiological load. This study shows that we can predict the adequacy of a given knot configuration under maximum physiological loading conditions.

Arthroscopy↗

PubMed1998

Loop security as a determinant of tissue fixation security.

Secure arthroscopic repair of rotator cuff tears and Bankart lesions requires tight knots (knot security). Equally important, but usually overlooked, is the tightness of the suture loop (loop security). This study compared loop security in knots tied with No. 1 PDS suture using three different methods: (1) hand-tied, (2) single-hole standard knot pusher, and (3) cannulated double-diameter knot pusher. The results of this study show that the double-diameter knot pusher maintained tight suture loops that were equivalent in circumference to hand-tied loops and were significantly tighter than suture loops tied with a standard single-hole knot pusher. This study highlights the fact that loop security is equally important to knot security in tissue fixation.

Arthroscopy↗

PubMed1998

How effective is manual palpation in detecting subtle temperature differences?

In the management of diabetic, neuropathic sequelae, namely ulceration and Charcot's arthropathy, appropriate quantification of inflammation is critically important in predicting future events and charting current progress. This article evaluates the ability of the physician to quantify subtle differences in temperature through manual palpation. The "laying on of hands" in a clinical setting is a necessary, crucial component of the doctor-patient relationship; however, our data suggest that manual palpation, even in a controlled environment, may not be an objective means to assess temperature, a cardinal sign of inflammation.

Adult↗

PubMed1996

Comparison of the mechanical performance of trochanteric fixation devices.

The transtrochanteric surgical approach to the hip is commonly used, especially for revision hip surgery. Failure of the trochanter to heal can lead to hardware failure, persistent pain, and limp. Rigid internal fixation is needed in this approach to achieve an adequate rate of healing. Newer cable and cable grip systems have been designed to improve trochanteric fixation, but have not been compared to the older Charnley wire fixation techniques. In this study, an in vitro mechanical method previously used to test wire fixation methods was used to compare wire, cable, and cable grip fixation methods. A quasistatic mechanical distraction device was used to compare structural stiffness, load to clinical failure, energy to clinical failure, and maximum load resisted by the fixation devices. The cable grip system was found to be stiffer, to resist a larger load to mechanical failure at 1-cm displacement, and to absorb a greater amount of energy to clinical failure when compared with the other systems. These data suggest that use of the cable grip fixation method should result in improved clinical success compared with the Charnley wire technique.

Adolescent↗

PubMedDate not supplied

The effects of diabetes mellitus on the material properties of human metatarsal bones.

While some investigations have focused on the effect of diabetes on the material properties of connective tissue in both the human and animal model, no study to date has investigated the effects of the disease process on human metatarsal bones. This investigation compared the material properties of human metatarsal bones from young diabetic donors (51.3 +/- 8 years) and older nondiabetic donors (72.3 +/- 10 years). The results demonstrated no significant differences between the two groups. This would seem to suggest that the effects of aging are comparable to the effects of diabetes on the structural integrity of human metatarsal bones.

Adult↗

PubMedDate not supplied

Cruciate injury patterns in knee hyperextension: a cadaveric model.

We created an experimental model to evaluate the effects of strain rate on the mechanism of combined cruciate ligament injuries in knee hyperextension. Using straight knee hyperextension to rupture the anterior and posterior cruciates, two strain rates (approximately 100% per second and 5400% per second) were applied to reproduce two clinical injury patterns of the knee: low energy (sporting) and high energy (pedestrian-motor vehicle accident). Ten pairs of fresh-frozen cadaveric knees were injured to 45 degrees of hyperextension. Strain rate sensitivity of the posterior cruciate ligament was shown in this model, with midsubstance tears occuring in specimens tested at a low rate and avulsion "stripping" injuries from the femoral side occuring at a high rate. A variable pattern of anterior cruciate ligament tears at both high and low rates suggests that the specific injury mechanism may also involve other factors including notch morphology. We present a simplified mathematic model used to estimate posterior cruciate ligament strain during knee hyperextension.

Adult↗