Continuous-Loop Tape Technique Has Greater Stiffness and Less Elongation Compared With Tied-Suture Fixation of Full-Thickness All–Soft Tissue Quadriceps Tendon Autografts

Background: Many graft fixation techniques are utilized for full-thickness soft tissue quadriceps tendon autografts during anterior cruciate ligament reconstruction (ACLR). Purpose: To determine the tensile properties of all–soft tissue quadriceps tendon graft fixation using a tied-suture versus continuous-loop tape technique. It was hypothesized that the continuous-loop tape technique would have less cyclic elongation and greater ultimate load to failure and stiffness compared with a commonly used tied-suture technique. Study Design: Controlled laboratory study. Methods: Sixteen fresh-frozen human knee specimens were used to harvest a full-thickness all–soft tissue quadriceps tendon graft; half were secured using a Krackow suture technique with 2 braided sutures, and half were secured using a continuous-loop tape suspensory fixation button with a rip-stop stitch. Cyclic and permanent elongation, toe- and linear-region stiffness, and ultimate load were determined. Statistical analysis was performed at P <.05. Results: The tied-suture fixation group demonstrated significantly higher permanent elongation (11.7 ± 3.6 vs 4.2 ± 1.0 mm, P < .001) and cyclic elongation (5.9 ± 1.3 vs 2.0 ± 0.4 mm, P < .001) compared with the continuous-loop tape fixation group. There was a significantly higher linear-region stiffness with continuous-loop tape fixation compared with tied-suture fixation (98.8 ± 12.7 vs 85.5 ± 7.5 N/mm, P = .022). No significant difference in ultimate load between groups (517.1 ± 149.2 vs 465.6 ± 64.6 N) was found. The mode of failure was tendon pull-through for the continuous-loop tape group and suture breakage in the tied-suture group ( P < .001). Conclusion: Continuous-loop tape fixation is superior to tied-suture fixation in regard to elongation and stiffness for all–soft tissue quadriceps tendon grafts, but there was no significant difference in ultimate load. Clinical Relevance: Continuous-loop tape fixation of all–soft tissue quadriceps tendon grafts for ACLR is a valid technique with superior tensile properties.

Biomechanical Evaluation Comparing Pulvertaft Weave and Side-to-Side Tenorrhaphy Using Porcine Tendons

Background: Pulvertaft Weave (PTW) is an established method of tenorrhapy in tendon transfers. Previous studies have suggested that a Side-to-Side (STS) tenorrhapy is easier to perform has the same advantages and has greater load to failure, ultimate load and stiffness compared to PTW. However, there is insufficient data comparing behaviour of STS and PTW during cyclical loading. The aim of this study is to compare these two methods in terms of creep after cyclic landing. Methods: Fresh porcine flexor digitorum tendons were used. Ten tendon PTW and ten STS repairs were performed. Cross sectional diameter was measured. The tendon repairs were tested by applying tension up to 25N for 100 cycles, followed by tension up to 75N for 100 cycles, followed by loading to failure. Force-displacement data was used to determine the creep of the repaired tendon. Results: All tendons survived 100 cycles of loading at 25N. After 1 cycle of loading, the mean cyclic creep in the PTW group was almost 3 mm larger than in the STS group (p = 0.046). After 100 cycles, the mean cyclic creep in the PTW group was 4.4 mm larger (p = 0.008). The cyclic creep rate was significantly larger in the PTW group (p < 0.001). All STS but only four PTW repairs survived after cyclic loading at 75N (p = 0.01). After 1 cycle and 100 cycles, mean creep of the surviving PTW samples was almost 7 mm (p = 0.006) and almost 9 mm (p = 0.004) larger than the STS group. The mean load to failure was four times larger in the STS group than the PTW group (p = 0.004). Conclusions: STS repairs have a significantly smaller permanent elongation after cyclic loading at 25N and 75N, a significantly smaller cyclic creep rate, require a significantly larger load to fail. This implies that STS repairs are less likely to elongate after cyclic loading and can withstand greater loads. These properties can be valuable in allowing patients to commence mobilisation immediately after surgery.

Investigation of the Characteristics of Elasticised Woven Fabric by Using PBT Filament Yarns

Owing to growing demand for comfortable clothes, elastane filament yarns are being used in fabrics for several garments. In this study, core spun yarns were produced with cotton fibres and PBT/elastane filament yarns (cotton as sheath material, PBT yarn and elastane as core yarns). Twill woven (1/3 Z) fabrics were produced by using core spun yarns (30 tex) and cotton yarns (30 tex) as weft, and 100% cotton yarn (59 tex) as warp yarns. The fabrics consisting of PBT were washed at 100°C for 30 minutes to gain the elasticity. The woven fabrics’ weight, thickness, elongation, permanent elongation, dimensional stability, air permeability, thermal conductivity, thermal absorptivity characteristics were tested and statistically evaluated. According to the results, the fabrics containing PBT and elastane filaments had similar elongation and shrinkage values. PBT filament yarns have a great potential to produce lightweight elastic fabrics.

Development of Time Domain Model for Synthetic Rope Mooring Systems

Mooring of offshore structures in very deep water has been made possible through the use of lines made of fibres of synthetic material. The mechanical behaviour of synthetic ropes is considerably more complex than that of steel wire rope and chain, due to the visco-elastic and visco-plastic properties of the synthetic material. In particular, the gradually developing permanent increase in rope length will affect the offset and motion of the moored structure and make its characteristics change from one storm to the next. For design and analysis of offshore mooring systems incorporating synthetic ropes it is valuable to have good models that can be used for response simulation in the time domain. The paper describes the development of a time domain model for synthetic rope. The model structure and the values of the parameters are determined from experimental data using a system identification technique. The resulting model is implemented in an existing computer program for analysis of mooring and riser systems. In particular, the permanent elongation of the synthetic rope appears to be well represented.

Biomechanical Evaluation of Minimally Invasive Repairs for Complete Acromioclavicular Joint Dislocation

Background The conventional coracoclavicular ligament augmentation with a single polydioxanone loop has been shown to have some pivotal disadvantages. Hypothesis A minimally invasive flip button/polydioxanone repair provides similar biomechanical properties to the conventional polydioxanone cerclage around the coracoid. However, the authors expected a difference in linear stiffness, ultimate load, and permanent elongation between suture anchor repairs and polydioxanone repairs. Study Design Controlled laboratory study. Methods The tensile fixation strength of 4 different minimally invasive repairs was tested in a porcine metatarsal model: (1) 1.3-mm single polydioxanone cerclage with a subcoracoidal flip button fixation, (2) 1.3-mm single polydioxanone cerclage, (3) Twinfix Ti 3.5-mm/Ultrabraid 2-suture anchor, and (4) Twinfix Ti 5.0-mm/Ultrabraid 2-suture anchor. The testing protocol included cyclic superoinferior loading and a subsequent load to failure trial. Results The flip button repair (646 N) and the conventional polydioxanone banding (663 N) revealed significant higher ultimate loads than did the suture anchor repairs (295 and 331 N, respectively; P < .001), whereas no significant differences were found for the elongation behavior under cyclic loading. Conclusion There was no significant difference between the 2 polydioxanone repairs. The ultimate load of the flip button procedure reaches the level of the native coracoclavicular ligament complex as it has been quantified in the literature. Clinical Relevance Although the biomechanical results comparing a minimally invasive flip button procedure versus a conventional polydioxanone cerclage are similar, the authors recommend the flip button procedure because of its minimally invasive approach and the secure subcoracoidal fixation technique with a minimized risk of anterior loop dislocation and neurovascular damage.

Torque and Angle Controlled Tightening Over the Yield Point of a Screw—Based on Monte-Carlo Simulations

This paper presents a technique, based on Monte-Carlo simulations, of utilizing a screw over its yield point in a controlled fashion, even under simple tightening conditions. The simulations consider the probabilistic nature of different variables necessary to calculate screwed joints. The proposed torque and angle controlled tightening technique can be used in assembly plants as well as in small workshops. The technique predicts permanent elongation, maximum tightening angle, final torque and preload after tightening. Further, a recommendation on the minimum and maximum snug torques prior to application of the angle over the yield point of a screw is also presented.