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1.
Objective— To compare the biomechanical properties of cervical arthroplasty to a ventral slot procedure and pin‐polymethylmethacrylate (pin‐PMMA) fixation. Sample Population— Fresh cadaveric cervical (C2–T1) spines from 6 large dogs. Methods— Four spinal conditions were studied in each spinal specimen: intact, disk arthroplasty, ventral slot, and fixation with smooth pin‐PMMA at C5–C6 intervertebral space. Axial compression, torsion, flexion–extension, and lateral bending moments were sequentially tested on each specimen for the 4 spinal conditions. Data from the C3–C4, C4–C5, C5–C6, and C6–C7 vertebral motion units (VMUs) were compared among treatments. Results— In axial compression and torsion, the ventral slot procedure allowed significantly less motion than intact, pin‐PMMA, and arthroplasty groups at C5–C6. In lateral bending and flexion–extension, pin‐PMMA had the least motion of C5–C6, followed by the arthroplasty group, intact spine, and ventral slot, all of which were significantly different from each other. Overall, the artificial disk was better able to mimic the behavior of the intact specimens compared with the ventral slot and pin‐PMMA, producing similar displacements in axial compression and rotation in torsion, but more limited motion than intact in flexion–extension and in lateral bending. Conclusion— Cervical spine specimens with an implanted prosthesis have biomechanical behaviors more similar to an intact spine compared with spinal specimens with ventral slot and pin‐PMMA procedures. Cervical arthroplasty may then preserve some of the motion in the affected area after neural decompression while providing distraction. Clinical Relevance— Cervical arthroplasty should be further investigated in vivo to determine if it is a viable alternative to the ventral slot or pin‐PMMA procedures for surgical treatment of cervical diseases in dogs and in particular for treatment of disk‐associated caudal cervical spondylomyelopathy. 相似文献
2.
OBJECTIVE: To investigate the mechanical characteristics of a nontoxic, low-cost, rigid polymer (RP) and to compare the structural and mechanical properties of a full-frame external skeletal fixator (ESF) with either RP connecting bars, polymethylmethacrylate (PMMA) connecting bars, or stainless-steel (SS) clamps and connecting bars. STUDY DESIGN: In vitro mechanical evaluation. METHODS: Mechanical properties were assessed using an in vitro bone fracture model with a bilateral uniplanar ESF (type II). Identical ESF were built with connecting bars using RP (n = 8), PMMA (n = 8), and SS connecting bars and clamps (System Meynard; n = 3). Nondestructive mechanical tests were performed in uniaxial compression (AC) and craniocaudal (CC) 4-point bending, as well as fatigue AC. Composite stiffness for each specimen and for each loading mode was calculated from 6 replicate measures using the slope of the load displacement curve at small displacements. RESULTS: RP, PMMA, and SS ESF constructs yielded mean +/- SD composite stiffness values of 227 +/- 15, 381 +/- 30, and 394 +/- 9 N/mm in AC and of 35 +/- 2, 24 +/- 2, and 15 +/- 0 N/mm in CC, respectively. CONCLUSIONS: Structural and mechanical properties of RP are satisfactorily rigid and fatigue resistant for its use as a connecting bar in ESF. CLINICAL RELEVANCE: RP connecting bars in an ESF are a reliable, versatile, nontoxic and inexpensive option for the veterinary surgeon. 相似文献
3.
OBJECTIVE: To evaluate a dorsoproximal extra-articular approach for insertion of 8.25-mm, solid-titanium, intramedullary (IM) interlocking nails into ostectomized foal third metacarpal (MC3) and third metatarsal (MT3) bones; to compare the monotonic mechanical properties of IM nail constructs with paired intact bones; and to determine the effects of age, body weight, fore- or hindlimb, and left or right limb on the mechanical testing variables. ANIMAL OR SAMPLE POPULATION: Twenty bone pairs (10 MC3, 10 MT3) collected from 10 foals of various weights and ages. METHODS: One bone from each pair was randomly selected to be ostectomized and stabilized using an 8.25-mm, solid-titanium IM nail, and four 3.7-mm titanium interlocking screws (construct). Constructs and contralateral intact bone specimens were tested in axial compression and palmaro-/plantarodorsal (PD) 4-point bending. Monotonic mechanical properties were compared between intact specimens and constructs with an ANOVA; significance was set at P <.05. RESULTS: Nail insertion caused bone failure in 6 MC3 and 2 MT3. In general, mean mechanical testing values indicated that intact specimens were significantly stronger and stiffer than constructs for all age and weight ranges when tested in compression and PD 4-point bending (P <.05). Bone strength and stiffness of intact specimens tested in compression and bending tended to increase linearly with age and weight. CONCLUSION: IM interlocking nail fixation of gap-ostectomized MC3 and MT3 with 8.25-mm IM nails and 3.7-mm interlocking screws did not achieve sufficient strength or stiffness to be recommended as the sole means of repair for comminuted MC3 and MT3 fractures in young foals. CLINICAL RELEVANCE: IM interlocking nail fixation of foal cannon bone fractures may be useful to decrease soft-tissue disruption at the fracture site; however, there is a risk of bone failure associated with extra-articular insertion. This method should be combined with other forms of external coaptation for added stability in axial compression and PD bending. 相似文献
4.
AIMS: To provide veterinarians with confidence when using a commercially available epoxy resin in external skeletal fixators (ESF), testing was conducted to determine exothermia during curing of the epoxy resin compared to polymethylmethacrylate (PMMA), the hardness of the epoxy resin as a bar over 16 weeks, and the strength of the epoxy resin bar compared with metal clamps in similarly constructed Type 1a ESF constructs simulating the repair of feline long bone fractures.METHODS: Exothermia of the epoxy resin during curing was tested against PMMA with surface temperatures recorded over the first 15 minutes of curing, using four samples of each product. The hardness of 90 identical epoxy resin bars was tested by subjecting them to cyclic loads (1,000 cycles of 20.5?N, every 7 days) over a 16-week period and impact testing 10 bars every 2 weeks. Ten bars that were not subjected to cyclic loads were impact tested at 0 weeks and another 10 at 16 weeks. Strength of the epoxy resin product, as a bar and clamp composite, was tested against metal SK and Kirschner-Ehmer (KE) clamps and bars in Type 1a, tied-in intramedullary pin, ESF constructs with either 90° or 75° pin placement, subjected to compressive and bending loads to 75?N.RESULTS: The maximum temperature during curing of the epoxy resin (min 39.8, max 43.0)°C was less than the PMMA (min 85.2, max 98.5)°C (p<0.001). There was no change in hardness of the epoxy resin bars over the 16 weeks of cyclic loading (p=0.58). There were no differences between the median strength of the epoxy resin, SK or KE ESF constructs in compression or bending when tested to 75?N (p>0.05). Stiffness of constructs with 75° pin placement was greater for SK than epoxy resin constructs in compression (p=0.046), and was greater for KE than epoxy resin constructs in bending (p=0.033).CONCLUSIONS: The epoxy resin tested was found to be less exothermic than PMMA; bars made from the epoxy resin showed durability over an expected fracture healing timeframe and had mechanical strength characteristics comparable to metal bar and clamp ESF constructs.CLINICAL RELEVANCE: The epoxy resin ESF construct tested in this study can be considered a suitable replacement for SK or KE ESF constructs in the treatment of feline long-bone fractures, in terms of mechanical strength. 相似文献
5.
Objective: To report pullout force to failure at the acrylic–pin interface for variably treated 3.2 mm external skeletal fixator pins. Study Design: In vitro biomechanical evaluation. Sample Population: 3.2 mm external skeletal fixator pins in polymethylmethacrylate bars. Methods: 3.2 mm external skeletal fixator pins were used for each of 5 treatment groups: polished, unpolished, 3 notched, 5 notched, and machine knurled. Each pin was seated into a 2‐cm‐diameter acrylic connecting bar and tested in pullout force to failure. Each group consisted of 6 pins. The force required to remove the pins from the acrylic bar was measured and compared between groups. Results: Significant differences between treatment groups were determined (P<.05). Within a construct group failure mode was consistent. Fracture of the acrylic bar was only seen with knurled pin ends. Conclusions: When using 2 cm acrylic bars in external skeletal fixation (ESF), a knurled pin shaft or a pin surface with 5 notches should be considered to improve the overall stability of the ESF construct. 相似文献
6.
Objectives: To (1) define mechanical properties in flexion, extension, and left lateral bending of cadaveric equine 4th and 5th cervical (C4–C5) articulations, (2) compare biomechanical properties of C4–C5 when stabilized with a kerf cut cylinder (KCC) compared with a ventrally placed 4.5 mm locking compression plate (LCP). Study Design: In vitro biomechanical investigation. Sample Population: Cadaveric adult equine cervical vertebral columns (n=54). Methods: Cervical vertebrae aged by horse dentition and size measured from radiographs were divided into 3 age groups then randomly allocated to 3 groups. The C4–C5 articulation was treated differently in each of the groups: KCC group; KCC‐implanted LCP group; 8‐hole 4.5 mm LCP implanted and intact group; no implant. Specimens were randomly subdivided into 1 of 3 loading conditions, before testing to failure under 4‐point bending. Stiffness, yield bending moment, failure bending moment, and failure mode were recorded. General linear models were performed to analyze associations between biomechanical properties and test variables. Results: All specimens failed at the C4–C5 intervertebral articulation. The cervical vertebrae with the LCP construct had significantly higher stiffness, yield bending moment, and failure bending moment than the KCC‐implanted cervical vertebrae. Failure modes differed between groups and varied with loading direction: KCC group, fractures of C5 associated with the KCC were common; LCP group, screw pull out or fractures (of C4 and C5 bodies, during extension and the caudal aspect of C4 during left lateral bending) were common; and intact group, subluxations were most common. Conclusions: In this model, LCP constructs had superior biomechanical properties compared with KCC constructs. Further research investigating the effect of repetitive loading is indicated. 相似文献
7.
Shahar R 《Veterinary surgery : VS》2000,29(1):59-69
OBJECTIVE: To compare the stiffness and pin stresses of three sizes of external fixator systems with stainless-steel and acrylic connecting bars. STUDY DESIGN: Finite element analysis. METHODS: Small, medium, and large external fixator systems of type I and type II configurations were modeled for finite element analysis. Each model was evaluated with a standard stainless-steel and three different diameters of acrylic connecting bar. Displacements and stresses were calculated for the loading modes of axial compression, medio-lateral bending, cranio-caudal bending, and torsion. The location of the pin experiencing maximum stress was determined for all configurations and loading modes. RESULTS: Acrylic column diameters of 9.53 mm for the small external fixator system and 15.9 mm for the medium external fixator system provide equivalent stiffness and maximum pin stresses to those provided by the standard stainless-steel connecting bars (3.2- and 4.8-mm diameter, respectively). The largest diameter acrylic column tested (31.75-mm) produced lower stiffness and higher maximum pin stresses than the standard stainless-steel connecting bar (11.1-mm diameter). CONCLUSIONS: When applying a small or medium external fixator, an acrylic column of 9.53-mm or 15.9-mm diameter, respectively, can be used. For a large external fixator system, an acrylic column of diameter >31.75 mm is required. CLINICAL RELEVANCE: The sizes of acrylic connecting bars for use in small and medium external fixator systems have been determined. Large systems should incorporate the standard stainless-steel connecting bar. 相似文献
8.
OBJECTIVE: To conduct an in vitro investigation of the biomechanical characteristics of the canine lumbar spinal column in flexion and extension and measure the destabilizing effects of multiple consecutive unilateral and bilateral hemilaminectomies. SAMPLE POPULATION: 30 isolated multisegmental spinal units (L1-L4) from nonhypochondroplastic dogs weighing 15 to 30 kg. PROCEDURES: Physically normal and surgically altered spinal specimens were subjected to 4-point bending in flexion and extension to determine effects of multiple consecutive hemilaminectomies on the basis of analysis of test system load-displacement data. Six groups with 5 spinal columns in each were defined on the basis of the following procedures: hemilaminectomy at L2-L3, 2 adjacent hemilaminectomies at L1-L3, 3 adjacent hemilaminectomies at L1-L4, bilateral hemilaminectomies at L2-L3, 2 bilateral hemilaminectomies at L1-L3, and no hemilaminectomy (intact). Spinal stability before and after surgery was determined in all groups. Each group served as its own control for nondestructive testing. Spinal strength was evaluated through destructive testing to determine deformation at failure, strength to failure, and mode of catastrophic failure. The intact group served as the control for destructive testing. RESULTS: Stability in extreme flexion and extreme extension did not change significantly following any hemilaminectomy procedure. Postoperative stability within the neutral zone was significantly decreased in all groups. Range of motion within the neutral zone was not significantly different from the intact condition in any group. CONCLUSIONS AND CLINICAL RELEVANCE: Multiple hemilaminectomies did not decrease stiffness of the lumbar spinal column during flexion and extension. These results support clinical recommendations regarding multiple consecutive hemilaminectomies in dogs. 相似文献
9.
STEVEN A. MARTINEZ DVM MS Diplomate ACVS STEVEN P. ARNOCZKY DVM Diplomate ACVS GRETCHEN L. FLO DVM MS WADE O. BRINKER DVM MS Diplomate ACVS 《Veterinary surgery : VS》1997,26(4):290-294
Objective — To determine the amount of heat conducted by transfixation intramedullary pins (IP) and Kirschner wires (KW) during polymerization of acrylics used for external skeletal fixator (ESF) connecting bars.
Study Design — Thermal conduction was measured using thermistors applied to IP and KW surfaces during the polymerization phase of acrylics.
Methods — Type II ESF were created from IP or KW placed into wooden dowels and plastic tubing used to create connecting bars filled with one of two types of acrylic (Acrylic Pin External Fixation System or Technovit, Jorgensen Laboratories, Loveland, CO). Thermistors were positioned on the acrylic column surface and on IP or KW surfaces 5 or 10 mm from the acrylic column. Five ESF test groups were created. The maximum temperature (Tmax) of the acrylic column (Tmax-A), IP (Tmax-IP), KW (Tmax-KW), and duration that Tmax-IP or Tmax-KW remained greater than or equal to 55°C were calculated.
Results — All IP and KW thermistors placed 5 mm from acrylic columns reached mean temperatures greater than 50°C and had peak temperature ranges greater than 55°C compared with all IP and KW thermistors placed 10 mm from the acrylic columns in all groups. Thermistors placed 5 mm from the acrylic column in two groups maintained temperatures greater than 55°C for greater than or equal to 0.5 minutes.
Conclusions — Acrylic columns positioned 5 mm from a thermistor on a IP or KW had the potential to reach or exceed temperatures that have been reported to cause thermal necrosis of tissues.
Clinical Relevance — Acrylic Pin External Fixation System or Technovit acrylic connecting bars used in ESF designs have the potential to cause thermal injury to soft and bony tissue by thermal conduction along transfixation pins or wires. 相似文献
Study Design — Thermal conduction was measured using thermistors applied to IP and KW surfaces during the polymerization phase of acrylics.
Methods — Type II ESF were created from IP or KW placed into wooden dowels and plastic tubing used to create connecting bars filled with one of two types of acrylic (Acrylic Pin External Fixation System or Technovit, Jorgensen Laboratories, Loveland, CO). Thermistors were positioned on the acrylic column surface and on IP or KW surfaces 5 or 10 mm from the acrylic column. Five ESF test groups were created. The maximum temperature (Tmax) of the acrylic column (Tmax-A), IP (Tmax-IP), KW (Tmax-KW), and duration that Tmax-IP or Tmax-KW remained greater than or equal to 55°C were calculated.
Results — All IP and KW thermistors placed 5 mm from acrylic columns reached mean temperatures greater than 50°C and had peak temperature ranges greater than 55°C compared with all IP and KW thermistors placed 10 mm from the acrylic columns in all groups. Thermistors placed 5 mm from the acrylic column in two groups maintained temperatures greater than 55°C for greater than or equal to 0.5 minutes.
Conclusions — Acrylic columns positioned 5 mm from a thermistor on a IP or KW had the potential to reach or exceed temperatures that have been reported to cause thermal necrosis of tissues.
Clinical Relevance — Acrylic Pin External Fixation System or Technovit acrylic connecting bars used in ESF designs have the potential to cause thermal injury to soft and bony tissue by thermal conduction along transfixation pins or wires. 相似文献
10.
Haerdi-Landerer C Steiner A Linke B Wahl D Schneider E Hehli M Frei R Auer JA 《Veterinary surgery : VS》2002,31(6):582-588
OBJECTIVE: To compare the mechanical properties of 2 configurations of a veterinary fixation system (VFS) for large animal long bones with dynamic compression plating (DCP). SAMPLE POPULATION: Eighteen pairs of Canevasit tubes (Canevasit; Amsler und Frei, Schinznach Dorf, Switzerland) (length, 170 mm; diameter, 47.5 mm; cortex thickness, 10 mm), aligned with a 10-mm gap, and stabilized with 2 DCP or 2 VFS implants. METHODS: Three groups (n = 6) were compared. Group 1 Canevasit tubes were stabilized with two 10-hole, broad 4.5-mm stainless steel DCP applied with both plates centered over the gap, in orthogonal planes parallel to the long axis of the tubes and staggered to allow bicortical fixation with ten 4.5-mm, 52-mm-long cortex screws each. Group 2 tubes were stabilized similarly with 2 VFS implants, each composed of a stainless steel rod (length, 167 mm; diameter, 8 mm), and 10 clamps were applied in alternating fashion left and right on the rod and fixed bicortically with ten 4.5-mm, 52-mm-long, cortex screws. Group 3 tubes were stabilized similarly, but using only 6 clamps/rod. All groups were tested initially in torsion within elastic limits and subsequently in 4-point bending, with 1 implant on the tension side, until gap closure occurred. RESULTS: None of the constructs failed, but all had plastic deformation after 4-point bending. No statistically significant differences were found among the 3 groups in torsional stiffness. Double DCP fixation was significantly stiffer and stronger in 4-point bending, compared with both configurations of double VFS fixation. CONCLUSIONS: The plate design was favored in this study. The VFS system may have to be adapted before further tests are conducted. Test modalities have to be chosen closer to clinical conditions (real bone, cyclic loading, closed gap). CLINICAL RELEVANCE: The veterinary fixation system has not yet proven its advantages for large animal long bone fracture repair. From the pure mechanical point of view, double DCP is the favored method for the treatment mentioned. 相似文献
11.
J D Langhoff J Mayer L Faber S B Kaestner G Guibert K Zlinszky J A Auer B von Rechenberg 《Veterinary and comparative orthopaedics and traumatology》2008,21(3):202-210
OBJECTIVES: Titanium implants have a tendency for high bone-implant bonding, and, in comparison to stainless steel implants are more difficult to remove. The current study was carried out to evaluate, i) the release strength of three selected anodized titanium surfaces with increased nanohardness and low roughness, and ii) bone-implant bonding in vivo. These modified surfaces were intended to give improved anchorage while facilitating easier removal of temporary implants. MATERIAL AND METHODS: The new surfaces were referenced to a stainless steel implant and a standard titanium implant surface (TiMAX). In a sheep limb model, healing period was 3 months. Bone-implant bonding was evaluated either biomechanically or histologically. RESULTS: The new surface anodized screws demonstrated similar or slightly higher bone-implant-contact (BIC) and torque release forces than the titanium reference. The BIC of the stainless steel implants was significant lower than two of the anodized surfaces (p = 0.04), but differences between stainless steel and all titanium implants in torque release forces were not significant (p = 0.06). CONCLUSION: The new anodized titanium surfaces showed good bone-implant bonding despite a smooth surface and increased nanohardness. However, they failed to facilitate implant removal at 3 months. 相似文献
12.
Singh GR Aithal HP Saxena RK Kinjavdekar P Amarpal Hoque M Maiti SK Pawde AM Joshi HC 《Veterinary surgery : VS》2007,36(1):80-87
OBJECTIVE: To report the biomechanical properties of 3 external skeletal fixation (ESF) devices for use in large ruminants. STUDY DESIGN: In vitro biomechanical testing of ESF constructs. SAMPLE POPULATION: Adult buffalo (weighing, 250-350 kg) tibiae (n=27). METHODS: ESF constructs (bilateral linear fixator [BLF], 4-ring circular external fixator [CEF], and hybrid fixator [HF]) were made using mild (low carbon) steel implants plated with nickel and cadaveric buffalo tibiae. After ESF application, a 1 cm mid-diaphyseal gap was created. Constructs were loaded to failure, on a materials testing machine, in axial compression (n=5/ESF type) and craniocaudal bending (n=3/ESF type). In addition, 3 CEF constructs were tested in intact tibiae under craniocaudal bending. RESULT: In compression, HF was the strongest and most rigid construct; yield load was significantly higher for HF than for BLF or CEF. Under bending, both CEF and HF had similar strength and modulus of elasticity. Strength for BLF was higher than CEF and HF, whereas the reverse was true for modulus of elasticity. CONCLUSIONS: ESF made from mild steel for use in large ruminants could withstand相似文献
13.
In vitro comparison of three fixation methods for humeral fracture repair in adult horses 总被引：1，自引：0，他引：1
M D Markel D M Nunamaker J D Wheat A E Sams 《American journal of veterinary research》1988,49(4):586-593
The stiffness, load to failure, and bending moments of adult intact equine humeri and humeri repaired with 3 fixation techniques were determined in vitro. Bones were tested in axial compression (30 pairs), mediolateral 3-point bending (15 pairs), and caudocranial 3-point bending (15 pairs). An oblique osteotomy of 1 humerus of each pair was performed to simulate the long spiral oblique fractures that occur clinically in horses. Bones were repaired in 3 ways: group 1--nylon band cerclage fixation (20 bones); group 2--multiple intramedullary pinning (20 bones); and group 3--nylon band cerclage fixation and multiple intramedullary pinning (20 bones). Intact bones were significantly (P less than 0.05) stronger than repaired bones in each testing mode. Bones repaired with bands only were significantly less stiff in bending than were bones repaired with pins only or with pins and bands. In compression, only specimens repaired with pins and bands were significantly stiffer than were bones repaired with bands only. Bones repaired with bands only required significantly less load to failure in compression and in caudocranial bending than did bones repaired with pins only or with pins and bands. Bones repaired with pins only deformed through the full displacement of the actuator (5 cm), and pins deformed plastically. Bones repaired with pins and bands were stiffer and had higher bending moments than did bones repaired with pins only, but the differences were not significant. 相似文献
14.
OBJECTIVE: To determine the optimal fixation technique for equine interdental space fractures by evaluating the biomechanical characteristics of 4 fixation techniques. STUDY DESIGN: In vitro randomized block design. SAMPLE POPULATION: Twenty-seven adult equine mandibles. METHODS: Mandibles with interdental osteotomies were randomly divided into 4 fixation groups (n = 6/group). Fixation techniques were the following: (1) dynamic compression plates (DCP), (2) external fixator (EF), (3) external fixator with interdental wires (EFW), and (4) intraoral splint with interdental wires (ISW). Three intact (nonosteotomized) mandibles were tested as controls. Mandibles were subjected to monotonic cantilever bending until failure. Angular displacement data (radians) were derived from continuously recorded gap width measurements provided by extensometers placed across the osteotomy site. Osteotomy gap width data (mm) at 50 and 100 Nm were selected for standardized comparison of gap width before the yield point and failure point, respectively of all constructs tested. Stiffness (Nm/radian), yield strength (Nm), and failure strength (Nm) were determined from bending moment-angular displacement curves and were compared using ANOVA with appropriate post hoc testing when indicated. Radiographs were obtained prefixation, postfixation, and posttesting. RESULTS: Bending stiffness, yield, and ultimate failure loads were greatest for intact mandibles. Among osteotomized mandibles, stiffness was greatest for DCP constructs (P <.05) and was not significantly different among EF, EFW, and ISW constructs. Yield load was greatest for ISW constructs (P <.05) and was not significantly different among DCP and EFW constructs. Yield and ultimate failure loads were lowest (P <.05) and osteotomy gap width at 50 and 100 Nm were greatest for EF constructs (P =.09 and P <.05, respectively). There was no significant difference in failure loads and osteotomy gap widths among DCP, EFW, and ISW constructs (P <.05). Failure occurred through the screw-bone interface (DCP), acrylic splint (ISW), acrylic connecting bar and/or pin-bone interface (EF, EFW), and wire loosening (EFW). All 3 intact mandibles fractured through the vertical ramus at its attachment to the testing apparatus. CONCLUSIONS: Among osteotomized mandibles, DCP fixation had the greatest stiffness under monotonic bending to failure; however, the relatively low yield value may predispose it to earlier failure in fatigue testing without supplemental fixation. Techniques using tension-band wiring (EFW and ISW) were similar to DCP constructs in yield, failure, and osteotomy displacement, whereas EF constructs were biomechanically inferior to all other constructs. CLINICAL RELEVANCE: DCP fixation is most likely the most stable form of fixation for comminuted interdental space fractures. However, for simple interdental space fractures, ISW fixation may provide adequate stability with minimal invasiveness and decreased expense. Tension-band wiring significantly enhances the strength of type II external skeletal fixators and should be used to augment mandibular fracture repairs. 相似文献
15.
An in vitro evaluation of plate luting using osteotomized equine third metacarpal bones with a limited contact-dynamic compression plate 总被引：1，自引：0，他引：1
OBJECTIVES: To evaluate the effects of plate luting on the biomechanical properties of a broad limited contact-dynamic compression plate (LC-DCP) fixation to repair osteotomized equine 3rd metacarpal (MC3) bones. STUDY DESIGN: In vitro biomechanical testing of paired cadaveric equine MC3 with a mid-diaphyseal osteotomy, stabilized by LC-DCP fixation, with 1 of the pair luted with polymethylmethacrylate (PMMA). ANIMAL POPULATION: Ten pairs of adult equine cadaveric MC3 bones. METHODS: Ten pairs of equine MC3 were divided into 2 test groups (5 pairs each) for (1) palmarodorsal 4-point bending single cycle to failure testing and (2) palmarodorsal 4-point bending cyclic fatigue testing. The LC-DCP (8 hole, 4.5 mm) was applied to the dorsal surface of each pair of MC3 bones. All plates and screws were applied using standard AO/ASIF techniques. All MC3 bones had mid-diaphyseal osteotomies. One of the matched pairs of LC-DCP-MC3 constructs were randomly chosen to be luted with PMMA. Mean test variable values for each method were compared using a paired t-test within each group; significance was set at P<.05. RESULTS: Mean palmarodorsal 4-point bending yield bending moment, failure bending moment of the LC-DCP fixation with luting was not significantly different (P>.05) than those of the LC-DCP fixation without luting. Mean cycles to failure for palmarodorsal 4-point bending was significantly (P<.0003) greater, with a 7.2-fold increase, for the LC-DCP fixation with luting compared with the LC-DCP fixation without luting. CONCLUSION: Luting the broad LC-DCP with PMMA in the fixation osteotomized equine MC3 bones increases the fatigue life of cyclic loading for palmarodorsal 4-point bending under the in vitro conditions studied. CLINICAL RELEVANCE: The cyclic fatigue data supports the conclusion that luted broad LC-DCP fixation is biomechanically superior to the non-luted broad LC-DCP fixation in osteotomized equine MC3 bones. 相似文献
16.
OBJECTIVE: To compare the fixation rigidity of recently developed external fixation systems (EFSs) to that of the traditional Kirschner-Ehmer (KE) system. STUDY DESIGN: In vitro biomechanical study. SAMPLE POPULATION: Five different EFSs (KE, Secur-U, small SK carbon fiber, small SK titanium, large SK carbon fiber) were assembled into 7 frame geometries to stabilize Delrin plastic rods with a 1-cm gap. METHODS: External skeletal fixation (ESF) constructs were tested in axial compression, torsion, medial-lateral bending, and cranial-caudal bending. Testing was conducted within the elastic range of each fixator. Mean stiffness in each mode was determined from the slope of the linear portion of the load-deformation curve. Comparison of stiffness values of each EFS within each loading mode and frame type was performed with 1-way analysis of variance (P <.05). RESULTS: Mean stiffness values were significantly higher for the large SK EFS in all frame types compared with KE but were equal in torsional stiffness in the double-bar type 1a frame. The small SK EFS with titanium connecting bar had greater stiffness than the KE in all modes for frame types Ia, Ia-accessory bar, and II-modified. No overall difference was detected between the KE EFS and the small SK with carbon fiber rod. The stiffness of the Secur-U type Ia frame with augmentation plate was significantly greater than the KE type Ia with accessory bar. CONCLUSIONS: The newer external fixation systems evaluated in this study provided fixation rigidity equal to or greater than that of the KE system. CLINICAL RELEVANCE: EFSs with increased frame rigidity should permit the use of less complex frame designs while providing fracture stability. 相似文献
17.
Adam M. Strom DVM MS Tanya C. Garcia MS Karl Jandrey DVM MAS Diplomate ACVECC Michael L. Huber DVM MS Diplomate ACVS Susan M. Stover DVM PhD Diplomate ACVS 《Veterinary surgery : VS》2010,39(7):824-828
Objective: To compare the bending structural stiffness and bending strength of thick and thin 2.4 mm limited contact dynamic compression plates (2.4 LC‐DCP), 2.0 mm LC‐DCP (2.0 LC‐DCP), and 2.0 dynamic compression plates (2.0 DCP). Study Design: In vitro mechanical study. Methods: Two thicknesses of 2.4 LC‐DCP, 2.0 LC‐DCP, and 2.0 DCP stainless‐steel plates were tested in 4‐point bending. Data were collected during bending until implants plastically deformed. Bending structural stiffness and bending strength were determined from load displacement curves. Mechanical properties were compared between plates and the effects of plate type, size, and thickness on stiffness and strength were assessed using ANOVA. Results: The thick 2.4 LC‐DCP implant was the stiffest and strongest; the thin 2.0 DCP implant was most compliant and weakest. Larger sized plates, thicker plates, and limited contact design of plates enhanced stiffness and strength. For the plates studied, plate size had a larger effect than plate type or thickness on stiffness and strength. Conclusion: Increasing the size (width) and thickness of plates increases both the bending structural stiffness and strength. For the plates studied, LC‐DCP implants were stiffer and stronger than DCP implants. Clinical Relevance: Plate bending structural stiffness and strength can be most effectively enhanced by using a larger sized plate, but gains can also be achieved by using a thicker plate and/or an LC‐DCP instead of a DCP implant when possible. 相似文献
18.
Fifty-three cases of equine mandibular fractures were managed surgically from 1988-1998, of which 16 (30%) were repaired by external skeletal fixation (ESF). Three surgical methods were utilised: transmandibular 4.76 or 6.35 mm Steinmann pins incorporated into fibreglass casting material or nonsterile dental acrylic (methyl methacrylate - MMA) bars reinforced with steel; transmandibular 9.6 mm self-tapping threaded pins +/- 4.76 or 6.35 mm Steinmann pins incorporated into MMA bars reinforced with steel; and 4.5 mm or 5.5 mm ASIF cortical bone screws incorporated into MMA bars reinforced with steel or a ventral MMA splint. Fourteen horses were presented to the hospital for fixator removal at an average of 56.2 days. At removal, fractures were stable and occlusion of incisor and cheek teeth was considered adequate. Complications of the procedure occurred in 3 horses. Two horses with persistent drainage and ring sequestra from pin tracts required curettage 4 or 5 months after ESF removal. A third horse required replacement of the original fibreglass ESF with MMA bars to regain access to open, infected wounds. Another horse required removal of the second premolar at the time of fixator removal because the tooth root had been damaged in the original injury. ESF for the surgical management of mandibular fractures in horses has produced good results, with incisive and cheek tooth alignment reestablished in all horses. Horses that were managed via ESF had a rapid return to full feed and did not require any supplementation via nasogastric tube or oesophagostomy to maintain bodyweight or hydration status. 相似文献
19.
OBJECTIVE: To compare monotonic mechanical properties of gap-ostectomized third metacarpal bones (MC3) stabilized with an MP35N interlocking nail system with contralateral intact bones. ANIMALS OR SAMPLE POPULATION: Twenty-four pairs of cadaveric equine MC3s. METHODS: Third metacarpal bones were divided into 4 mechanical testing groups (6 pairs per group): compression, palmarodorsal (PD) and mediolateral (ML) 4-point bending, and torsion. One MC3 from each pair was randomly selected as an intact specimen, and the contralateral gap ostectomized bone was stabilized with a 4-hole, 14-mm-diameter, 250-mm-long, MP35N intramedullary nail, and four, 7-mm-diameter, 60-mm-long MP35N interlocking screws (constructs). Mechanical testing properties were compared between intact specimens and constructs with a paired t test (significance set at P <.05). RESULTS: Intact specimens were significantly stronger and stiffer than constructs in all testing modes except PD bending. Constructs achieved mean yield strengths that were 57% (compression), 81% (PD bending), 68% (ML bending), and 78% (torque) of intact specimens. Constructs achieved mean stiffnesses that were 53% (compression), 58% (PD bending), 41% (ML bending), and 47% (torque) of intact specimens. CONCLUSION: Monotonic yield mechanical properties of MP35N intramedullary interlocking nail-stabilized, gap-ostectomized MC3 were lower than those of paired intact bones but exceeded reported in vivo loads for dorsopalmar bending and compression and estimated in vivo torsional loads. CLINICAL RELEVANCE: Considering the benefits associated with intramedullary interlocking nail fixation of fractures, this system should be considered for use for repair of MC3 fractures with applicable fracture configurations. 相似文献
20.
Radcliffe RM Lopez MJ Turner TA Watkins JP Radcliffe CH Markel MD 《Veterinary surgery : VS》2001,30(2):179-190
OBJECTIVE: To compare the biomechanical properties of intact immature horse femurs and 3 stabilization methods in ostectomized femurs. Animal or SAMPLE POPULATION: Eighteen pairs of femurs from immature horses aged 1 to 15 months, and weighing 68 to 236 kg. METHODS: Thirty-four immature horse femurs were randomly assigned to 1 of 5 test groups: 1) interlocking intramedullary nail (IIN) (n = 6); 2) IIN with a cranial dynamic compression plate (I/DCP) (n = 6); 3) 2 dynamic compression plates (2DCP) (n = 8); 4) intact femurs tested to failure in lateromedial (LM) bending (n = 6); and 5) intact femurs tested to failure in caudocranial (CaCr) bending (n = 8). Mid-diaphyseal ostectomies (1 cm) were performed in all fixation constructs. Biomechanical testing consisted of 4 nondestructive tests: CaCr bending, LM bending, compression, and torsion, followed by bending to failure. All groups were tested to failure in LM bending with the exception of 1 group of intact femurs tested to failure in CaCr bending. Stiffness and failure properties were compared among groups. RESULTS: The 2DCP-femur construct had greater structural stiffness in nondestructive bending than the IIN-femur construct in either LM or CaCr bending, and the I/DCP-femur construct in LM bending. Only the I/DCP and 2DCP fixations were similar to intact bone in nondestructive-bending tests. In addition, the 2DCP-femur construct had greater structural and gap torsional stiffness than the I/DCP-femur construct, and greater gap torsional stiffness than the IIN-femur construct. However, all of the fixation methods tested, including the 2DCP-femur construct, had lower structural stiffness in torsional loading compared with intact bone. No significant differences in structural stiffness were found between intact bones and femur constructs tested nondestructively in compression. In resistance to LM bending to failure, the 2DCP-femur construct was superior to the IIN-femur construct, yet similar to the I/DCP-femur construct. Also, evaluation of yield and failure loads revealed no significant differences between intact bone and any of the femur constructs tested to failure in LM bending. CONCLUSIONS: In general, the 2DCP-femur construct provided superior strength and stiffness compared with the IIN and I/DCP-femur constructs under bending and torsion. CLINICAL RELEVANCE: Double plating of diaphyseal comminuted femoral fractures in immature horses may be the best method of repair, because in general, it provides the greatest strength and stiffness in bending and torsion. 相似文献