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1.
Objective —To test a crimp clamp system designed to secure monofilament nylon leader (MNL) material commonly used as lateral fabellotibial sutures (LFS) in extra-articular stabilization of the canine stifle joint.
Study Design — In vitro biomechanical tests of MNL loops secured with either the crimp clamp system or knots were performed. Suture loops (n = 94) were created from 27.3 kg tensile strength MNL and fastened with knots or crimp clamps. Tests were conducted on steam-sterilized, ethylene-oxide-sterilized, and nonsterilized MNL sutures. Loops were evaluated in single load tests and cycled tests. Values for load to failure, initial loop tension, loop elongation, mode of failure, and point of failure were determined.
Results —Crimp-clamped loops were superior to knotted loops in all parameters tested in both cycled and noncycled tests. Loop failure generally occurred by breaking within 3 mm of the fixation in both clamped and knotted tests. Loop elongation after cycling was greater in the knotted loops compared with clamped loops ( P < .001). Load to failure was greater in clamped tests than in knotted tests (P < .001), regardless of sterilization technique used. Significantly higher initial loop tension could be achieved with the clamp system compared with knot fixation ( P < .001).
Conclusions —The crimp clamp system provides superior in vitro loop fixation characteristics compared with knot fixation in 27.3 kg test MNL.
Clinical Relevance —Based on the results of biomechanical testing and the known biocompatibility of the system's implant components, clinical trials using the crimp clamp system are warranted.  相似文献   

2.
OBJECTIVE: To compare mechanical properties of knotted and crimped nylon loops. STUDY DESIGN: In vitro mechanical evaluation. SAMPLE POPULATION: Loops of 27 kg-test nylon leader. Single strand-clamped square knot compared with 2 crimp systems. Two strand--self-locking knot compared with 2 crimped loops. METHODS: (a) Single pull to failure (n = 10) at 500 mm/min. Initial loop tension (N), peak load (N), peak elongation (mm), stiffness of the linear portion of the curve (N/mm), and failure mode were recorded. (b) Incremental cyclic loading to failure (n = 5)--each loop was cycled 5 times to 100 N at a loading rate of 200 mm/min. Cycling was repeated, with the load increased by 50 N after each set. Elongation (mm), tension remaining (N), and after permanent deformation was present, elongation at 10 N (mm) were measured. RESULTS: Initial tension and stiffness were greater for crimped loops when compared with knotted loops. There were no differences between crimped loops. The self-locking knot elongated more, and was less stiff, when compared with 2 crimped loops. With incremental loading, knotted loops elongated more than crimped loops. The tension remaining in the loop fell below 10 N more quickly for knotted loops compared with crimped loops. CONCLUSION: Crimped loops are stiffer, and resist both static and cyclic load more effectively before becoming permanently elongated, when compared with knotted loops. CLINICAL RELEVANCE: Stifle stability will be maintained more effectively by crimped nylon loops when compared with knotted loops.  相似文献   

3.
Objective— To evaluate the effect of 6 different knotting methods on the mechanical properties of 3 large absorbable suture materials used in large animal surgery. Study Design— In vitro mechanical study. Sample Population— Knotted suture loops (n=15 per group). Methods— Suture loops were created between two low‐friction pulleys with either 2 polydioxanone, 2 polyglactin 910 or 3 polyglactin 910. Strands were tied using 1 of 6 knotting technique: square knot, surgeon knot, clamped surgeon's knot, sliding half‐hitch knot (HH), Delimar knot and self‐locking knot (SLK). A single cycle to failure test was performed on each suture loop with a distraction rate of 100 mm/min. Failure modes were evaluated and breaking strength, elongation to failure and stiffness were compared. Results— All loops except two HH failed at the knot by acute breaking. The double‐stranded SLK was both stronger and stiffer than all other knots for each suture material. Clamping the first throw of the surgeon knot decreased load to failure significantly (143.11 ± 8.64 N) compared with not clamping (159.21 ± 6.14 N) for polydioxanone. Stiffness and elongation to failure were respectively lower and increased for 2 polydioxanone compared with both polyglactin 910 materials for all knotting techniques. Conclusions— Knotting techniques do influence structural properties of suture loops. The double strand loop conferred stiffer and stronger properties to the SLK Clinical Relevance— Clamping the first throw of polydioxanone should be avoided when tying a suture under tension even using large diameter suture materials. Using a SLK might be considered as a useful alternative when excessive tension is present.  相似文献   

4.
OBJECTIVE: To compare anatomic reduction and the biomechanical properties of a circular external skeletal fixator (CESF) construct to pin and tension band wire (PTBW) fixation for the stabilization of olecranon osteotomies in dogs. STUDY DESIGN: Cadaveric study. ANIMALS: Forelimbs from 12 skeletally mature mixed-breed dogs, weighing 23 to 28 kg. METHODS: An olecranon osteotomy was stabilized with either a CESF construct or PTBW fixation. A single distractive load to failure was applied to each specimen through the triceps tendon. Osteotomy reduction and biomechanical properties were compared between fixation groups. RESULTS: Reduction was not significantly different (gap: P =.171; malalignment: P =.558) between fixation groups. Osteotomies stabilized with the CESF had greater stiffness (P <.0001) and maximum load sustained (P <.0001) compared to PTBW fixation. There was no significant difference for yield load (P =.318) or for load at 1 mm of axial displacement (P =.997) between fixation groups. Failure of fixation occurred by bending of the intramedullary Steinmann pin and the fixation wires in the CESF specimens and by untwisting of the tension band wire knot with pullout and bending of the Kirschner wires in the PTBW specimens. CONCLUSIONS: Specimens stabilized with the CESF construct had similar reduction and yield load, greater stiffness and maximum load sustained, and less elastic deformation than specimens stabilized with PTBW fixation. CLINICAL RELEVANCE: The CESF construct may provide a biomechanically favorable alternative to PTBW fixation for stabilization of olecranon osteotomies in dogs, and its application warrants clinical investigation.  相似文献   

5.
OBJECTIVE: To evaluate the effect of knotting method on the mechanical properties of large diameter nonabsorbable monofilament suture materials. STUDY DESIGN: In vitro mechanical evaluation. METHODS: A conventional square knot was compared with the surgeon's knot, sliding half-hitch, and clamped square knot. Knotted suture loops were created in a uniform manner and acutely tensioned to failure (20 mm/min loading rate; n = 20 per knot type for each material). Stiffness, yield, and failure characteristics of USP #2 nylon, #2 polybutester, #2 polypropylene, 27 kg test monofilament nylon fishing line, and 27 kg nylon leader material were evaluated. RESULTS: Compared with a conventional square knot, a surgeon's knot decreased stiffness for #2 polypropylene, 27 kg fishing line, and 27 kg leader (P < .05). A sliding half-hitch weakened all materials except 27 kg leader (P < .05). Clamping the first throw of a square knot increased the stiffness of 27 kg leader loops (P < .05). CONCLUSIONS: Based on clinically relevant parameters (stiffness and yield), knotting method had no effect on #2 nylon and #2 polybutester. The surgeon's knot is not recommended for #2 polypropylene and 27 kg fishing line and leader material. A sliding half-hitch decreased the yield of leader material. Clamping the first throw of a square knot had no adverse effects on acute properties of tested materials; it increased the stiffness for leader material. CLINICAL RELEVANCE: Knotting method does influence the structural properties of suture materials and should be considered when tying knots under tension.  相似文献   

6.
The knot security of chromic gut, polyglycolic acid, polyglactin 910, polydioxanone, polypropylene, and monofilament nylon size 2-0 suture materials were tested biomechanically in vitro. Twenty reproducible knots were tied and incubated in canine serum at 37 degrees for 24 hours before testing. A "secure knot" was defined as a knot that, when tested to failure, broke rather than untied by slippage. The minimum number of throws necessary to make a secure, snug (1500 g tension) square knot was three for gut, polyglycolic acid, polyglactin 910, and polypropylene and four for polydioxanone and nylon. All throws including the first were counted. With all suture materials tested, surgeon's knots were as secure as square knots. Only gut, polyglycolic acid, and polydioxanone granny knots were as secure as square knots; no loosely tied (500 g tension) asymmetric square knots were as secure as snug square knots, and only polydioxanone and polypropylene loose square knots were as secure as snug square knots. Square knots used to start a continuous pattern required one additional throw with gut, polydioxanone, and nylon. Square knots used to end a continuous pattern required two to three additional throws with all materials tested.  相似文献   

7.
Objective— To compare biomechanical properties of 3 new generation polyethylene sutures (FiberTape [FT], FiberWire [FW], and OrthoFiber [OF]) with nylon leader line (NL) for use during extraarticular fixation of cranial cruciate deficient stifles. Study Design— In vitro biomechanical testing of suture loops under monotonic tensile and cyclical loading until failure. Sample Population— Constructs of FT, FW, OF, and NL. Methods— Twenty loops of each of 12 combinations of fixation and suture had monotonic tensile and cyclical loading. Two knotting techniques (square knot [SQ], slip knot [SL]) and a crimp clamp (CR) system were evaluated. Elongation, stiffness, and strength of constructs was tested. The main effects of group, loop material, and their interaction were evaluated. Results— Knotted FT, FW, and OF had less elongation than knotted NL under monotonic tensile and cyclical loading. Under monotonic tensile loading, knotted FT and OF were stiffer than knotted NL. CR FT, CR FW, and CR OF were stiffer than CR NL and CR FT, CR FW, and CR OF were stiffer than knotted FT, FW, and OF. FW and OF knotted loops were weaker than knotted NL. CR FT was stronger than CR NL. CR FT and CR OF were weaker than knotted FT and OF. Conclusions— Polyethylene sutures are stronger, stiffer and elongate less than nylon leader. Crimping suture alters the biomechanical properties of the loop. Clinical Relevance— FW, FT, and OF may perform better in reconstructive procedures, where increased strength and stiffness are considered to be beneficial.  相似文献   

8.
The ability of six different instruments to apply a cerclage wire under tension to a tension gage was compared. The loop knot produced greater final wire tension than the twist knot, both before and after bending. No significant difference in tension was found between the Swiss Osteo and A.S.I.F. instruments. The Rhinelander and Richards instruments gave approximately the same tension before the bend. The Rhinelander, Richards, and Vise Grip instruments showed no statistical difference in tension produced after the bend. The Bowen instrument developed the least amount of tension, both before and after bending the twist. All twist knots lost a significant amount of tension during the bending process. The twist-type knots that were twisted until breakage in the middle of the knot produced greater tension than those that were cut once they were tight. Cutting the twisted knot caused a significant decrease in wire tension. No correlation was found between operator pull and final cerclage wire tension.  相似文献   

9.
OBJECTIVE: To compare tension of 3 cerclage wire knots tied by surgeons of various abilities and experience. DESIGN: Cross-sectional study. SAMPLE POPULATION: Participants and faculty at a postgraduate course in veterinary orthopedics. PROCEDURE: Subjects tied a cerclage of their choice on an instrumented tying stand that displayed the tension on a computer. Mean tensions in cerclage wires tied with twist, single loop, or double loop knots were compared. The relationship between level of surgeon experience and tension achieved was examined. RESULTS: 29 twist, 30 single loop, and 16 double loop wires were analyzed. Mean +/- SD tension for twist knots was significantly less than for single loop knots (82.3+/-46.1 vs 166.6+/-42.2 N, respectively). Double loop knots achieved significantly greater tension (392.0+/-116.6 N) than twist and single loop knots did, even though few participants had ever tied this knot previously. There was no correlation with experience of the participant. For twist knots, wiggling the wire during cutting and pushing the twist over to flatten it to the bone further reduced tension. CONCLUSIONS AND CLINICAL RELEVANCE: Cerclage applied with a twist knot does not compress fracture fragments as effectively as cerclage applied with single loop or double loop techniques. Because greater compression of fragments will improve the stability of a fracture, a surgeon should strive to maximize the tension in the cerclage that they use. Experience and abilities of the surgeon are not associated with ability to tie cerclage wires tightly.  相似文献   

10.
Objective—To compare the accuracy of reduction, biomechanical characteristics, and mode of failure of two methods of acetabular osteotomy repair. Study Design—Acetabular osteotomies were created in 16 paired hemipelves and stabilized with a screw/wire/polymethylmethacrylate composite fixation technique (SWP) or a 2-mm veterinary acetabular plate (VAP). Eight intact hemipelves were used as controls. Sample Population—Twelve canine cadavers. Methods—Accuracy of osteotomy reduction was evaluated grossly and by measurement of articular incongruencies formed in polyvinylsiloxane impression casts. Acetabula were loaded in modified bending until failure using a universal testing machine. Data from load-deformation curves were used to determine the biomechanical characteristics of the repaired and intact acetabula. Mode of failure was evaluated grossly and radiographically. Results—Osteotomy reduction was superior in acetabula stabilized with SWP. Mean values ± standard deviation for load at failure and stiffness of the intact acetabula were 2,796 ± 152.9 N and 267.5 ±61.9 N/mm. Corresponding values for SWP and VAP were 1,192 ± 202.7 N and 136.3 ± 76.5 N/mm, and 1,100.5 ± 331.6 N and 110.0 ± 51.3 N/mm, respectively. The mean load at failure and stiffness of intact acetabula was significantly greater than acetabula stabilized with SWP or VAP. There was no significant difference between SWP and VAP for load at failure or stiffness. Failure of acetabula stabilized with SWP occurred by fracture of the polymethylmethacrylate and ventrolateral bending of the wires. Acetabula stabilized with VAP failed by ventrolateral twisting of the plate and bending of the caudal screws. Conclusions—SWP and VAP provide comparable rigidity, however, the SWP facilitates more accurate osteotomy reduction. Clinical Relevance—These findings support the use of the SWP technique as an alternative method of acetabular fracture repair.  相似文献   

11.
OBJECTIVE: To determine a hand-tied ligature knot configuration, suture size, and suture type that would be an acceptable substitute to commercially available ligature knots for use in equine laparoscopic surgery. STUDY DESIGN: Three-factor ANOVA with the fixed effects being suture type, suture size, and knot type. The dependent variable was ligature security (load to failure). METHODS: Commercially available Endoloop and 4 hand-tied slipknot ligatures were compared with a 4-layer square knot. The hand tied ligature knots tested were the 4S modified Roeder knot, the Brooks knot, the modified Roeder knot, and the Weston knot. Two suture sizes (0, 2) of each of 2 suture types (polydioxanone, polyglactin 910) were tested with each hand tied knot. Two types (polydioxanone, polyglactin 910) of size 0 Endoloop were tested. Twenty repetitions of each knot suture type were tested for force to yield on a materials testing machine. Statistical analysis consisted of a 3-way ANOVA with individual comparisons made using the Bonferroni method. Significance was P< or = .05. RESULTS: Only the 4S modified Roeder knot in 2 polydioxanone (103 N) was comparable with the breaking strength of the square knots (157 N). All other knot suture combinations tested were significantly weaker than the square knot (range, 2-18 N). CONCLUSION: For equine laparoscopy, a 2 polydioxanone 4S modified Roeder knot would be an acceptable alternative to the commercially available Endoloop. CLINICAL RELEVANCE: Laparoscopic slip knots are commonly used in equine laparoscopic surgery. Various knot configuration and suture size and type combinations will affect the security of the slip knot.  相似文献   

12.
The in vitro biomechanical properties of three methods for internal fixation of femoral neck fractures were evaluated. Fifty cadaveric femura from Beagle dogs were used. Ten intact femora served as controls. In 40 femura, an osteotomy of the femoral neck was performed to simulate a transverse fracture. With the remaining 30 femura, three repair methods (two medium Orthofix pins, a 2.7 mm cortical bone screw placed in lag fashion and an anti- rotational Kirschner wire, or three divergent 1.1 mm Kirschner wires) were used to stabilize the osteotomies, and 10 osteotomies were stabilised per repair method. These 30 femura where then subject to monotonic loading to failure. Construct stiffness and load to failure were measured. In the remaining 10 femura, pressure sensitive film was placed at the osteotomy site prior to stabilization with either two Orthofix pins (n = 5) or a screw placed in lag fashion (n = 5) to determine the compressive pressure (MPa), compressive force (KN) and area of compression (cm2). There was no significant difference in the stiffness or load to failure for the three repair methods evaluated. There was no significant difference in the compressive pressure, compressive force or area of compression in osteotomies stabilized with Orthofix pins and 2.7 mm bone screws.  相似文献   

13.
OBJECTIVE: To evaluate the mechanical properties of the 18 and 36 kg Securos Cranial Cruciate Ligament Repair System. STUDY DESIGN: In vitro mechanical evaluation. SAMPLE POPULATION: Loop constructs of 18, 27, and 36 kilogram test (kgt) nylon leader line (NLL) secured with Securos crimp-clamps (SCC, n=40 per NLL test weight) or by a clamped square knot (CSK; n=40/NLL test weight). METHODS: The 36 kg SCC were used for the 27 and 36 kgt NLL, and 18 kg SCC were used for the 18 kgt NLL. Loop constructs were mounted on a material testing machine, and distracted at 500 mm/min for static tests, and for cyclic tests at 500 mm/min to a distraction limit of 6 mm (18 kgt) or 7.5 mm (27 and 36 kgt) for 49 cycles, until failure. Constructs were tested at 20 degrees C except for 1 group of 27 kgt CSK loops tested at 40 degrees C. Load at failure, elongation, and stiffness was recorded and compared between groups under static or cyclic testing conditions. RESULTS: All 27 and 36 kgt loops failed by disruption of NLL contained within the knot or crimp-clamp, whereas 18 kgt SCC loops failed by the NLL pulling through the crimp-clamp. The 18 kg SCC loops had considerable variability in ultimate load and elongation (coefficient of variation 29.6% and 18.3%, respectively). There was no significant difference in elongation between 27.3 kgt CSK loops tested at 20 degrees C and 40 degrees C. Generally, in both static and cyclic testing, SCC constructs formed with 27.3 or 36.4 kgt NLL performed as well or better than CSK constructs, resulting in loops that were strong, underwent minimal elongation, and had high stiffness. CONCLUSION: The results support use of the 36 kg Securos system but not the 18 kg Securos system (with the clamp and crimping device used). The significantly lower load required for failure, slippage through the clamp, and substantial variability suggested that the crimp tube diameter or the crimping device tested may be inappropriate for use with 18 kgt NLL. CLINICAL RELEVANCE: Surgeons should be aware that crimp-clamp design is important in controlling suture slippage or breakage within the clamp, and that novel systems should undergo mechanical testing with the size suture material they are intended to secure before clinical use.  相似文献   

14.
OBJECTIVE: To evaluate the effect of recombinant equine growth hormone (rEGH) on the in vitro biomechanical properties of normal adult equine superficial digital flexor tendon (SDFT). STUDY DESIGN: Completely randomized design. SAMPLE POPULATION: Nine Standardbred horses, 6 to 9 years of age with ultrasonographically normal forelimb SDFT. METHODS: Six horses were administered intramuscular (IM) rEGH at 10 microg/kg/day for 1 week, and then 20 microg/kg/day for another 5 weeks; 3 horses (control subjects) were administered an equivalent daily volume of sterile water IM. Horses were killed at the end of the 6-week treatment period, and both forelimb SDFT were harvested and stored at -70 degrees C. In vitro biomechanical testing was performed under uniaxial tension. Results were analyzed using a general linear model of analysis of variance; significance was set at P <.05. RESULTS: There were no differences in cross-sectional area, maximal load at failure, yield load, ultimate and yield tensile strain, ultimate and yield tensile stress, or stiffness between tendons from control and treated horses. CONCLUSIONS: Administration of rEGH to adult Standardbred horses for 6 weeks had no detectable effect on the in vitro biomechanical properties of normal SDFT. CLINICAL RELEVANCE: Administration of rEGH does not modulate the in vitro biomechanical properties of SDFT from adult Standardbred horses.  相似文献   

15.
Objective: To determine (1) the minimum number of throws to form secure Aberdeen (AB) and square knots to start (SS) and end (SE) continuous patterns, in fat‐ and plasma‐coated polydioxanone; and (2) compare relative knot security (RKS) and knot volumes of these secure SS, SE, and AB knots. Study Design: In vitro experimental materials testing. Sample Population: Polydioxanone suture material (3 metric). Methods: Each knot was tested 20 times, and throws incrementally added until secure SS, SE, and AB knots were found. RKS and knot volumes were calculated for SS, SE, and AB knots. Results: Secure SE knots needed 5 throws in plasma or fat. Secure SS knots needed 4 throws in plasma, but 5 in fat. The minimum AB configuration that was secure in plasma or fat was 3+1, however, the 4+1 AB knot was also secure in fat. Mean (SD) RKS of secure knots were: SE 59.69% (5.91), SS 67.92% (12.50), AB 81.08% (8.99). AB knots had significantly higher mean RKS than any SS or SE knot in plasma or fat (P<.001). Mean knot volume of 3+1 AB knot was significantly smaller than any secure SS or SE knots by 22.6–69.4% (P<.0001). Mean knot volume of 4+1 AB knots was significantly smaller than all fat secure SS and SE knots by 19.9–57.5% (P=.0001). Conclusion: The knot security of the SS knot was decreased by fat coating polydioxanone suture, requiring an additional throw to keep it secure. Secure AB knots had a higher breaking strength and smaller knot volume than secure SS and SE knots. Clinical Relevance: The AB may be preferable to square knots in continuous closures. As many body fluids contain lipid, surgeons should tie knot configurations considered secure in fat. We advise tying a 4+1 AB and placing a minimum of 5 throws to tie SS and SE knots using 3 metric polydioxanone.  相似文献   

16.
OBJECTIVE: To determine relative effects of ring diameter and wire tension on axial biomechanical properties of 4-ring circular external skeletal fixator constructs. SAMPLE POPULATION: 4-ring circular external skeletal fixator constructs and artificial bone models. PROCEDURE: 4-ring constructs were assembled, using 50-, 66-, 84-, or 118-mm-diameter rings. Two 1.6-mm-diameter fixation wires were attached to opposing surfaces of each ring at intersection angles of 90 degrees and placed through a gap-fracture bone model. Three examples of each construct were loaded in axial compression at 7 N/s to a maximum load of 400 N at each of 4 wire tensions (0, 30, 60, and 90 kg). Response variables were determined from resulting load-displacement curves (construct stiffness, load at 1 mm of displacement, displacement at 400 N). RESULTS: Ring diameter and wire tension had a significant effect on all response variables and had a significant interaction for construct stiffness and displacement at 400 N. Significant differences within all response variables were seen among all 4 ring diameters and all 4 wire tensions. As ring diameter increased, effect of increasing wire tension on gap stiffness and gap displacement at 400 N decreased. Ring diameter had a greater effect than wire tension on all response variables. CONCLUSIONS AND CLINICAL RELEVANCE: Although effects of wire tension decrease as ring diameter increases, placing tension on wires in larger ring constructs is important because these constructs are inherently less stiff. The differential contribution of ring diameter, wire tension, and their interactions must be considered when using circular external skeletal fixators.  相似文献   

17.
OBJECTIVES: To compare the biomechanical properties, in full limb preparations, of intact second phalanx and a simulated comminuted second phalangeal fracture stabilized with either two bone plates or a custom Y-plate. STUDY DESIGN: In vitro biomechanical assessment of intact limbs and of paired limbs with a simulated second phalangeal fracture stabilized by one of two fixation methods. Animal Population-Thirteen pairs of equine cadaveric forelimbs. METHODS: A comminuted second phalangeal fracture was created in six paired cadaveric limbs. For each limb pair, the fracture was stabilized with two plates in one limb, and with a Y-plate in the contralateral limb. These limbs and seven pairs of intact limbs were subjected to axial compression in a single cycle until failure. Mechanical properties were compared with a mixed-model ANOVA and post hoc contrasts. Joint contact pressure, screw insertion torque, and final screw torque remaining after mechanical testing were also evaluated for constructs. RESULTS: No significant differences in mechanical testing variables were detected between construct types. However, the Y-Plate construct had significantly greater yield load, yield displacement and yield energy, and failure load and stiffness values than those for intact specimens, whereas the double-plate construct only had greater stiffness than intact specimens. There were no significant differences in joint contact pressures for both constructs. The final screw torque for proximal phalangeal screws was significantly greater for the Y-plate constructs than for double-plate constructs. CONCLUSIONS: The Y-plate was as effective as the double-plate technique for stabilization of simulated comminuted second phalangeal fractures in monotonically tested equine cadaveric forelimbs. CLINICAL RELEVANCE: This investigation supports evaluation of the Y-plate for repair of comminuted second phalangeal fractures in equine patients. Its specific design may facilitate repair of second phalangeal fractures, and may provide increased stability by allowing the proximal fragments of the second phalanx to be fixed with three screws placed through the plate.  相似文献   

18.
This in vitro study compares the biomechanical properties of two methods of ilial fracture repair in dogs. Ten pelves were harvested from skeletally mature mixed breed dogs weighing 20-27 kg and bilateral oblique ilial body osteotomies were created. One hemipelvis from each dog was stabilized with a 2.7 mm plate and screws and the contralateral hemipelvis was stabilized with a five pin linear external fixator construct. Each hemipelvis was mounted at an angle of 30 degrees to an actuator platform, such that the acetabulum was centrally loaded by a steel sphere attached to the load cell of a servohydraulic materials testing machine. The construct was loaded at a constant rate of 20 mm/min. A load/displacement curve was generated for each hemipelvis by plotting the sustained load against the actuator movement. The stiffness, yield load and failure load for each hemipelvis were determined from the load/displacement curve. Bending stiffness was defined as the slope of the load/displacement curve from 100 N to yield load. The mode of failure was determined by observations made during testing and gross inspection of each specimen. The mean construct stiffness, yield load and failure load were compared between stabilization groups using a Student's paired t-test with statistical significance set at p<0.05. Nine out of 10 of the hemipelves that were stabilized by plates and screws failed catastrophically by fracture through the caudal screw holes and nine out of 10 of the hemipelves that were stabilized using an external fixator failed by fracture of the ischium in the region supported by the mounting roller, propagating through the most caudal ischial pin. There was not any significant difference (P=0.22) in bending stiffness between stabilization techniques, but yield (1467 N vs 2620 N; P=0.04) and failure (1918 N vs 2687 N; P=0.002) loads were significantly greater for hemipelves stabilized with external fixators.  相似文献   

19.
O bjectives : To determine the minimum number of throws/turns to form a secure Aberdeen knot and the maximum ear slippage for these knots using three metric polydioxanone coated in fat or plasma. To compare plasma and novel canine liquefied fat as suture coating mediums for in vitro knot security testing.
M ethods : Throws/turns were incrementally added until a secure knot was found for plasma and fat. Knots were tensioned until failure and remaining ear length measured. A secure knot was defined as ear slippage 3 mm or less in 20 consecutively tested knots. Ear slippages were statistically analysed.
R esults : Minimum secure configuration was a 3+1 knot in plasma and fat, and its ear slipped a maximum of 2 mm in plasma and 2·5 mm in fat. A secure 4+1 knot had a maximum ear slippage of 0·5 mm, which was significantly less than that of the 3+1 knot (P<0·0001). Fat coating suture significantly decreases in vitro knot security compared with plasma (P=0·0035).
C linical S ignificance : The novel fat coating medium should be considered when testing in vitro knot security as it simulates a clinical knot tying environment. A 4+1 Aberdeen knot with a 3 mm ear is recommended to tie a secure Aberdeen knot in any body fluid environment.  相似文献   

20.
OBJECTIVE: To determine whether recombinant equine growth hormone (rEGH) would alter the in vitro biomechanical properties of the forelimb superficial digital flexor tendon (SDFT) in exercising young Standardbred horses. STUDY DESIGN: Randomized complete block design. ANIMALS: Twelve Standardbred yearlings. METHODS: Horses were trained for 12 weeks on a high-speed treadmill (10% positive incline). rEGH was administered intramuscularly (IM) daily (10 microg/kg during week 4; 20 microg/kg for weeks 5-9) to 6 horses (treated group), whereas 6 horses (control group) were administered an equivalent daily volume of sterile water IM. At 12 weeks, horses were euthanatized and left forelimb SDFTs were collected and stored (-70 degrees C). A section from the mid-region of the SDFT was held in cryoclamps with a 4 cm interspace distance and distracted at 10 mm/s until failure. The variables evaluated were maximal load at yield and failure, ultimate and yield tensile stress and strain, tendon stiffness, and mode of failure. Data were analyzed using unpaired, two-tailed, Student's t-test. Statistical significance was set at P < or =.05. RESULTS: Yield and ultimate tensile stress were significantly lower in the rEGH-treated horses compared with controls. There was a trend toward increased maximal displacement, increased ultimate tensile strain, and decreased tendon stiffness in rEGH-treated horses compared with controls. Tensile stress and cross-sectional area, and tensile stress and stiffness were significantly correlated at yield and failure points. CONCLUSIONS: rEGH, administered at the manufacturer's recommended dose rates to maturing Standardbred horses in training, does not significantly augment the in vitro biomechanical properties of the forelimb SDFT. CLINICAL RELEVANCE: Administration of rEGH to young horses in training is unlikely to enhance the physiologic adaptation of the SDFT to exercise stress.  相似文献   

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