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1.
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   

2.
OBJECTIVE: To compare the mechanical properties of two stabilization methods for ostectomized equine third metacarpi (MC3): (1) an interlocking nail system and (2) two dynamic compression plates. Animal or Sample Population-Ten pairs of adult equine forelimbs intact from the midradius distally. METHODS: Ten pairs of equine MC3 were divided into two test groups (five pairs each): caudocranial four-point bending and torsion. Interlocking nails (6 hole, 13-mm diameter, 230-mm length) were placed in one randomly selected bone from each pair. Two dynamic compression plates one dorsally (12 hole, 4.5-mm broad) and one laterally (10 hole, 4.5-mm broad) were attached to the contralateral bone from each pair. All bones had 1 cm mid-diaphyseal ostectomies. Five construct pairs were tested in caudocranial four-point bending to determine stiffness and failure properties. The remaining five construct pairs were tested in torsion to determine torsional stiffness and yield load. Mean values for each fixation method were compared using a paired t-test within each group. Significance was set at P<.05. RESULTS: Mean (+/-SEM) values for the MC3-interlocking nail composite and the MC3-double plate composite, respectively, in four-point bending were: composite rigidity, 3,454+/-407.6 Nm/rad and 3,831+/-436.5 Nm/rad; yield bending moment, 276.4+/-40.17 Nm and 433.75+/-83.99 Nm; failure bending moment, 526.3+/-105.9 Nm and 636.2+/-27.77 Nm. There was no significant difference in the biomechanical values for bending between the two fixation methods. In torsion, mean (+/-SEM) values for the MC3-interlocking nail composite and the MC3-double plate composite were: composite rigidity, 124.1+/-16.61 Nm/rad and 262.4+/-30.51 Nm/rad; gap stiffness, 222.3+/-47.32 Nm/rad and 1,557+/-320.9 Nm/rad; yield load, 94.77+/-7.822 Nm and 130.66+/-20.27 Nm, respectively. Composite rigidity, gap stiffness, and yield load for double plate fixation were significantly higher compared with interlocking nail fixation in torsion. CONCLUSIONS: No significant differences in biomechanical properties were identified between an interlocking nail and double plating techniques for stabilization of ostectomized equine MC3 in caudocranial four-point bending. Double plating fixation was superior to interlocking nail fixation in torsion.  相似文献   

3.
OBJECTIVE--To compare the mechanical properties of 2 interlocking-nail systems for fixation of ostectomized equine third metacarpi (MC3): (1) a standard interlocking nail with 2 parallel screws proximal and distal to a 1-cm ostectomy; and (2) a modified interlocking nail with 2 screws proximal and distal to a 1-cm ostectomy with the screws offset by 30 degrees. ANIMAL OR SAMPLE POPULATION--Twelve pairs of adult equine forelimbs intact from the midradius distally. METHODS--Twelve pairs of equine MC3 were divided into 2 test groups (6 pairs each): torsion and caudocranial 4-point bending. Standard interlocking nails (6-hole, 13-mm diameter, 230-mm length) were placed in 1 randomly selected bone from each pair. Modified interlocking nails (6-hole, 13-mm, 230-mm length, screw holes offset by 30 degrees) were placed in the contralateral bone from each pair. All bones had 1-cm mid-diaphyseal ostectomies. Six construct pairs were tested in caudocranial 4-point bending to determine stiffness and failure properties. The remaining 6 construct pairs were tested in torsion to determine torsional stiffness and yield load. Mean values for each fixation method were compared using a paired t test within each group. Significance was set at P <.05. RESULTS--Mean (+/-SEM) values for the MC3-standard interlocking-nail composite and the MC3-modified interlocking-nail composite, respectively, in 4-point bending were: composite rigidity, 3,119 +/- 334.5 Nm/rad (newton. meter/radian) and 3,185 +/- 401.2 Nm/rad; yield bending moment, 205.0 +/- 18.46 Nm and 186.7 +/- 6.17 Nm; and failure bending moment, 366.4 +/- 21.82 Nm and 378.1 +/- 20.41 Nm. There were no significant differences in the biomechanical values for bending between the 2 fixation methods. In torsion, mean (+/-SEM) values for the MC3-standard interlocking-nail composite and the MC3-modified interlocking-nail composite were: composite rigidity, 135.5 +/- 7.128 Nm/rad and 112.5 +/- 7.432 Nm/rad; gap stiffness, 207.6 +/- 10.57 Nm/rad and 181.7 +/- 12.89 Nm/rad; and yield load, 123.3 +/- 2.563 Nm and 107.5 +/- 8.353 Nm, respectively. Composite rigidity and gap stiffness for standard interlocking-nail fixations were significantly higher than the modified interlocking-nail fixation technique in torsion. Yield load had a tendency to be higher for the standard interlocking-nail fixation (P =.15). CONCLUSIONS--No significant differences in biomechanical properties were identified between a standard interlocking nail and one with the screw holes offset by 30 degrees in caudocranial 4-point bending. The standard interlocking nail was superior to the modified interlocking nail in torsional gap stiffness and composite rigidity. The torsional yield load also tended to be higher for the standard interlocking nail. CLINICAL RELEVANCE--The standard interlocking nail with parallel screw holes is superior to a modified interlocking nail with the screw holes offset by 30 degrees in ostectomized equine MC3 bones in vitro when tested in torsion.  相似文献   

4.
Eighteen intact canine cadaver radii underwent nondestructive axial testing, and were osteotomized, plated, and retested. Each bone was tested with and without mediolateral or craniocaudal restriction of motion. Fixation of the osteotomies was performed under static compression with a cranially applied 5-hole 3.5 mm dynamic compression plate, a cranially applied 7-hole 3.5 mm T-plate, or a medially applied 7-hole 2.7 mm dynamic compression plate. There was no loss of axial stiffness after osteotomy and fixation, and there were no differences in axial stiffness between the methods of fixation. Mediolateral stiffness (bending around the craniocaudal axis) was consistently greater than craniocaudal stiffness (bending around the mediolateral axis) before and after osteotomy and plate fixation. There was no difference in the axial stiffness of otherwise intact radii when craniocaudal or mediolateral screw holes were drilled; however, all radii with craniocaudal screw holes and one radius with mediolateral screw holes fractured at a screw hole at high axial loads.  相似文献   

5.
OBJECTIVE: To determine cyclic biomechanical properties of gap osteotomized adult equine tibiae stabilized with an equine interlocking nail (EIN). STUDY DESIGN: In vitro experimental biomechanical investigation. SAMPLE POPULATION: Thirteen adult equine cadaveric tibiae. METHODS: Adult equine tibiae with transverse, midshaft, 1-cm gap osteotomies, stabilized with an equine interlocking nail, underwent cyclic biomechanical testing in vitro under axial compression, 4-point bending, and torsion. Different specimens were subjected to different load levels that represented estimated in vivo loads at 2 Hz for 740,000 cycles. Fatigue life and gap strain were calculated. RESULTS: Compression and bending, but not torsional, fatigue life were longer than time necessary for bone healing. Compressive, but not bending or torsional, gap strains were small enough to be compatible with fracture healing by primary bone formation. Gap strains for compressive, bending, and torsional loads were compatible with indirect, or secondary, bone formation. CONCLUSIONS: Further modification should be made to the equine interlocking nail to increase bending stiffness and torsional fatigue life. CLINICAL RELEVANCE: The stainless steel equine intramedullary interlocking nail is unlikely to provide appropriate long-term stability for fracture healing in adult equine tibiae without modifications in the nail design and material.  相似文献   

6.
Objective— To compare monotonic biomechanical properties and fatigue life of a broad locking compression plate (LCP) fixation with a broad limited contact dynamic compression plate (LC‐DCP) fixation to repair osteotomized equine third metacarpal (MC3) bones. Study Design— In vitro biomechanical testing of paired cadaveric equine MC3 with a mid‐diaphyseal osteotomy, stabilized by 1 of 2 methods for fracture fixation. Animal Population— Cadaveric adult equine MC3 bones (n=12 pairs). Methods— MC3 were divided into 3 groups (4 pairs each) for: (1) 4‐point bending single cycle to failure testing; (2) 4‐point bending cyclic fatigue testing; and (3) torsional single cycle to failure testing. The 8‐hole, 4.5 mm LCP was applied to the dorsal surface of 1 randomly selected bone from each pair. One 8‐hole, 4.5 mm LC‐DCP) was applied dorsally to the contralateral bone from each pair. All plates and screws were applied using standard ASIF techniques. All MC3 bones had mid‐diaphyseal osteotomies. 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 yield load, yield bending moment, composite rigidity, failure load and failure bending moment, under 4‐point bending, single cycle to failure, of the LCP fixation were significantly greater than those of the LC‐DCP fixation. Mean cycles to failure for 4‐point bending was significantly greater for the LCP fixation compared with LC‐DCP fixation. Mean yield load, mean composite rigidity, and mean failure load under torsional testing, single cycle to failure was significantly greater for the broad LCP fixation compared with the LC‐DCP fixation. Conclusion— The 4.5 mm LCP was superior to the 4.5 mm LC‐DCP in resisting the static overload forces (palmarodorsal 4‐point bending and torsional) and in resisting cyclic fatigue under palmarodorsal 4‐point bending. Clinical Relevance— The results of this in vitro study may provide information to aid in the selection of a biological plate for the repair of equine long bone fractures.  相似文献   

7.
Objectives: To compare the monotonic biomechanical properties and fatigue life of a 5.5‐mm‐broad locking compression plate (5.5 LCP) fixation with a 4.5‐mm‐broad locking compression plate (4.5 LCP) fixation to repair osteotomized equine 3rd metacarpal (MC3) bones. Study Design: In vitro biomechanical testing of paired cadaveric equine MC3 with a middiaphyseal osteotomy, stabilized by 1 of 2 methods for fracture fixation. Animal Population: Fifteen pairs of adult equine cadaveric MC3 bones. Methods: Fifteen pairs of equine MC3 were divided into 3 test groups (5 pairs each) for (1) 4‐point bending single cycle to failure testing, (2) 4‐point bending cyclic fatigue testing, and (3) torsional single cycle to failure testing. An 8‐hole, 5.5 LCP was applied to the dorsal surface of 1 randomly selected bone from each pair and an 8‐hole, 4.5 LCP was applied dorsally to the contralateral bone from each pair using a combination of cortical and locking screws. All plates and screws were applied using standard ASIF techniques. All MC3 bones had middiaphyseal osteotomies. Mean test variable values for each method were compared using a paired t‐test within each group with significance set at P<.05. Results: Mean yield load, yield bending moment, composite rigidity, failure load, and failure bending moment, under 4‐point bending, single cycle to failure, of the 5.5 LCP fixation were significantly greater than those of the 4.5 LCP fixation. Mean cycles to failure in 4‐point bending of the 5.5 LCP fixation (170,535±19,166) was significantly greater than that of the 4.5 LCP fixation (129,629±14,054). Mean yield load, mean composite rigidity, and mean failure load under torsional testing, single cycle to failure was significantly greater for the broad 5.5 LCP fixation compared with the 4.5 LCP fixation. In single cycle to failure under torsion, the mean±SD values for the 5.5 LCP and the 4.5 LCP fixation techniques, respectively, were: yield load, 151.4±19.6 and 97.6±12.1 N m; composite rigidity, 790.3±58.1 and 412.3±28.1 N m/rad; and failure load: 162.1±20.2 and 117.9±14.6 N m. Conclusion: The 5.5 LCP was superior to the 4.5 LCP in resisting static overload forces (palmarodorsal 4‐point bending and torsional) and in resisting cyclic fatigue under palmarodorsal 4‐point bending. Clinical Relevance: These in vitro study results may provide information to aid in selection of an LCP for repair of equine long bone fractures.  相似文献   

8.
Objectives: To compare number of cycles to failure for palmarodorsal 4‐point bending of a modified 5.5 mm broad locking compression plate (M5.5‐LCP) fixation with a 5.5 mm broad LCP (5.5‐LCP) fixation used to repair osteotomized equine third metacarpal (MC3) bones. Study Design: In vitro biomechanical testing. Animal Population: Adult equine cadaveric MC3 bones (n=6 pairs). Methods: An 8‐hole, M5.5‐LCP, obtained by having a 1.0 mm thickness removed from the bone contact portion of the 5.5‐LCP, was applied to the dorsal surface of 1 randomly selected MC3 from each pair, and an 8‐hole, 5.5‐LCP was applied dorsally to the contralateral bone from each pair using a combination of cortical and locking screws. Plates and screws were applied using standard ASIF techniques to MC3 bones with a mid‐diaphyseal osteotomy. MC3 constructs had palmarodorsal 4‐point bending cyclic fatigue testing. Mean cycles to failure for each method were compared using a paired t‐test within each group. Significance was set at P<.05. Results: Mean±SD cycles to failure of the M5.5‐LCP fixation (188,641±17,971) was significantly greater than that of the 5.5‐LCP fixation (166,497±15,539). Conclusion: M5.5‐LCP fixation was superior to 5.5‐LCP fixation of osteotomized equine MC3 bones in resisting cyclic fatigue under palmarodorsal 4‐point bending. Clinical Relevance: This suggests that biological plate fixation is not the ideal choice for osteotomized equine MC3 bones.  相似文献   

9.
OBJECTIVES: To compare biomechanical properties of a prototype 5.5 mm tapered shaft cortical screw (TSS) and 5.5 mm AO cortical screw for an equine third metacarpal dynamic compression plate (EM-DCP) fixation to repair osteotomized equine third metacarpal (MC3) bones. STUDY DESIGN: Paired in vitro biomechanical testing of cadaveric equine MC3 with a mid-diaphyseal osteotomy, stabilized by 1 of 2 methods for fracture fixation. ANIMAL POPULATION: Adult equine cadaveric MC3 bones (n=12 pairs). METHODS: Twelve pairs of equine MC3 were divided into 3 groups (4 pairs each) for (1) 4-point bending single cycle to failure testing, (2) 4-point bending cyclic fatigue testing, and (3) torsional single cycle to failure testing. An EM-DCP (10-hole, 4.5 mm) was applied to the dorsal surface of each, mid-diaphyseal osteotomized, MC3 pair. For each MC3 bone pair, 1 was randomly chosen to have the EM-DCP secured with four 5.5 mm TSS (2 screws proximal and distal to the osteotomy; TSS construct), two 5.5 mm AO cortical screws (most proximal and distal holes in the plate) and four 4.5 mm AO cortical screws in the remaining holes. The control construct (AO construct) had four 5.5 mm AO cortical screws to secure the EM-DCP in the 2 holes proximal and distal to the osteotomy in the contralateral bone from each pair. The remaining holes of the EM-DCP were filled with two 5.5 mm AO cortical screws (most proximal and distal holes in the plate) and four 4.5 mm AO cortical screws. All plates and screws were applied using standard AO/ASIF techniques. 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 4-point bending yield load, yield bending moment, bending composite rigidity, failure load and failure bending moment of the TSS construct were significantly greater (P<.00004 for yield and P<.00001 for failure loads) than those of the AO construct. Mean cycles to failure in 4-point bending of the TSS construct was significantly greater (P<.0002) than that of the AO construct. The mean yield load and composite rigidity in torsion of the TSS construct were significantly greater (P<.0039 and P<.00003, respectively) than that of the AO construct. CONCLUSION: The TSS construct provides increased stability in both static overload testing and cyclic fatigue testing. CLINICAL RELEVANCE: The results of this in vitro study support the conclusion that the EM-DCP fixation using the prototype 5.5 mm TSS is biomechanically superior to the EM-DCP fixation using 5.5 mm AO cortical screws for the stabilization of osteotomized equine MC3.  相似文献   

10.
Objective— To compare the efficacy of recombinant human bone morphogenetic protein‐2 (rhBMP‐2)/calcium phosphate (CP) to autogenous cancellous bone graft (CBG) and to no treatment on bone healing, in surgically induced osteotomies and ostectomies of the accessory metatarsal bones in an equine model. Study Design— Experimental. Animals— Adult horses (n=9). Methods— Segmental ostectomies of the second metatarsal bone (MT2) and osteotomies of the fourth metatarsal bone (MT4) were performed bilaterally in 9 horses. There were a total of 35 defects (1 MT4 was previously fractured) created and supplemented randomly either with no treatment (untreated control), rhBMP‐2/CP cement, or matrix (CPC or CPM), or CBG. Radiography was performed every 2 weeks until study endpoint at 12 weeks. After euthanasia, bone healing was evaluated using radiography, mechanical testing, and histology. Data were analyzed with ANOVA followed by the Duncan's Multiple Range Test or nonparametric analyses. Results— At 12 weeks, radiographic scores for union were significantly greater for the rhBMP‐2 (P<.0001) and CBG (P=.004) groups compared with the untreated control group, for both MT2 ostectomies and MT4 osteotomies. The rhBMP‐2 treated MT2 had greater maximum torque to failure in torsion than CBG and control limbs at 12 weeks (P=.011). Histologic analysis demonstrated increased bone formation and more mature bone at the ostectomy site for MT2 in the rhBMP‐2 and CBG groups compared with the untreated control group. Conclusion— Injection of rhBMP‐2/CP into surgically induced ostectomies and osteotomies of the accessory metatarsal bones might accelerate early bone healing in the horse. Clinical Relevance— RhBMP‐2/CP may be as effective if not superior to CBG as an adjuvant treatment to accelerate healing of bone defects.  相似文献   

11.
This study biomechanically evaluates solid and tubular interlocking nails in bovine neonatal femurs. Paired femurs from 40 neonatal dairy calves were obtained for mechanical testing. Intact femurs and four combinations of experimentally manipulated femurs (intact or ostectomized femurs with either a solid or tubular interlocking nail) were tested in craniocaudal and lateromedial bending, eccentric axial compression, and external torsion to evaluate composite rigidity, local/gap stiffness, and load to failure (compression and torsion only). In torsional composite rigidity, femurs with tubular interlocking nails were more compliant than intact femurs or intact femurs with solid interlocking nails (P <.001). Ostectomized femurs with solid interlocking nails were similar to intact femurs with tubular interlocking nails. Within femurs with tubular interlocking nails, ostectomized femurs were more compliant than intact femurs (P <.0001). In craniocaudal and lateromedial bending rigidity, ostectomized femurs were more compliant than intact femurs, regardless of interlocking nail type (P <.001). Within ostectomized femurs, tubular interlocking nails were more compliant than solid interlocking nails in craniocaudal bending (P <.05) and there was a similar trend in lateromedial bending (P=.06). In eccentric axial compression, local/ gap stiffness was significantly greater in intact femurs compared with intact femurs with solid (48% of intact bone) or tubular (45% of intact bone) interlocking nails and ostectomized femurs with solid (18% of intact bone) or tubular (11 % of intact bone) interlocking nails (P <.0001). In torsional testing, local/gap stiffness was not significantly different between intact femurs and intact femurs with interlocking nails, but was significantly lower in ostectomized femurs with solid (2% of intact bone) and tubular (0.2% of intact bone) interlocking nails (P <.0001). In torsional and compressive failure testing, plastic deformation of the tubular interlocking nail occurred at the unoccupied screw hole at the ostectomy site before bone failure. Interlocking nails should be considered as an optional repair method for neonatal bovine femoral fractures. Until the actual physiological loading characteristics of neonatal calf femurs are measured, it is uncertain whether solid or tubular interlocking nails tested in this study will provide sufficient strength and stiffness to stabilize neonatal bovine femoral fractures and facilitate healing.  相似文献   

12.
Objectives— To compare monotonic biomechanical properties and fatigue life of a 5.5 mm broad limited‐contact dynamic compression plate (5.5‐LC‐DCP) fixation with a 4.5 mm broad LC‐DCP (4.5‐LC‐DCP) fixation to repair osteotomized equine third metacarpal (MC3) bones. Study Design— In vitro biomechanical testing of paired cadaveric equine MC3 with a mid‐diaphyseal osteotomy, stabilized by 1 of 2 methods for fracture fixation. Sample Population— Adult equine cadaveric MC3 bones (n=18 pair). Methods— MC3 were divided into 3 test groups (6 pairs each) for: (1) 4‐point bending single cycle to failure testing; (2) 4‐point bending cyclic fatigue testing; and (3) torsional single cycle to failure testing. The 8‐hole, 5.5 mm broad LC‐DCP (5.5‐LC‐DCP) was applied to the dorsal surface of 1 randomly selected bone from each pair. One 8‐hole, 4.5 mm broad LC‐DCP (4.5‐LC‐DCP) was applied dorsally to the contralateral bone from each pair. Plates and screws were applied using standard ASIF techniques. All MC3 bones had mid‐diaphyseal osteotomies. 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 yield load, yield bending moment, composite rigidity, failure load and failure bending moment under 4‐point bending, single cycle to failure, of the 5.5‐LC‐DCP fixation were significantly greater (P<.024) than those of the 4.5‐LC‐DCP fixation. Mean cycles to failure for 4‐point bending was significantly (P<.05) greater for the 4.5‐LC‐DCP fixation compared with the 5.5‐LC‐DCP fixation. Mean yield load, mean composite rigidity, and mean failure load in torsion for the 5.5‐LC‐DCP fixation was not significantly different (P>.05) than those with the 4.5‐LC‐DCP fixation. Conclusion— 5.5‐LC‐DCP fixation was superior to 4.5‐LC‐DCP fixation in resisting the static overload forces under palmarodorsal 4‐point bending. There was no significant difference between 5.5‐LC‐DCP fixation and 4.5‐LC‐DCP fixation in resisting static overload forces under torsion; however, the 5.5‐LC‐DCP offers significantly less stability (80% of that of the 4.5‐LC‐DCP) in cyclic fatigue testing. Clinical Relevance— The results of this in vitro study may provide information to aid in the selection of a biological plate for long bone fracture repair in horses.  相似文献   

13.
Objectives: To compare the number of cycles to failure of 4.5 mm broad dynamic compression plates (DCP), 4.5 mm broad limited‐contact dynamic compression plates (4.5‐LC‐DCP), and 5.5 mm broad limited‐contact dynamic compression plates (5.5‐LC‐DCP) having a rough (denoted by a prefix R‐) versus a standard smooth contact surface for the fixation of osteotomized equine 3rd metacarpal (MC3) bones. Study Design: Experimental. Animal Population: Fifteen pairs of adult equine cadaveric MC3 bones. Methods: Fifteen pairs of equine MC3 were divided into 3 test groups (5 pairs each) for comparison of (1) R‐DCP fixation with DCP fixation, (2) R‐4.5‐LC‐DCP fixation with 4.5‐LC‐DCP fixation, and (3) R‐5.5‐LC‐DCP fixation with 5.5‐LC‐DCP fixation to repair osteotomized equine MC3 bones under palmarodorsal 4‐point bending cyclic fatigue testing. For each group an 8‐hole plate with rough contact surface was applied to the dorsal surface of one randomly selected bone from each pair and a corresponding 8‐hole plate with smooth contact surface was applied dorsally to the contralateral bone from each pair. All plates and screws were applied using standard ASIF techniques. All MC3 bones had mid‐diaphyseal osteotomies. Mean number of cycles to failure for each method were compared using a paired t‐test within each group. Significance was set at P<.05. Results: Mean cycles to failure ± standard deviation was significantly greater for the R‐DCP fixation (230,025 ± 23,129) compared with the DCP fixation (103,451 ± 14,556), for the R‐4.5‐LC‐DCP fixation (99,237 ± 14,390) compared with the 4.5‐LC‐DCP fixation (46,464 ± 6325) and for the R‐5.5‐LC‐DCP fixation (65,113 ± 7796) compared with the 5.5‐LC‐DCP fixation (34,224 ± 3835). Conclusion: For the fixation of osteotomized MC3 bones, the constructs with plates having rough contact surface were superior to the corresponding constructs with plates having standard smooth contact surfaces in resisting cyclic fatigue under palmarodorsal 4‐point bending.  相似文献   

14.
OBJECTIVE: To compare the biomechanical characteristics and mode of failure of two different dynamic compression plate (DCP) techniques for proximal interphalangeal joint (PIPJ) arthrodesis in horses. STUDY DESIGN: Randomized block-design blocking on horse (1-5), method of fixation (two 7-hole, 3.5-mm broad DCP vs two 5-hole, 4.5-mm narrow DCP), side (left, right), and end (front, hind). Constructs were loaded to failure in 3-point bending in a dorsal-to-palmar (plantar) direction. SAMPLE POPULATION: Ten paired limbs from 5 equine cadavers. METHODS: Two 7-hole, 3.5-mm broad dynamic compression plates (bDCP) were used in 1 limb of a pair, and two 5-hole 4.5-mm narrow dynamic compression plates (nDCP) were used on the contralateral limb. Plates were positioned abaxially across the dorsomedial and dorsolateral aspect of the PIPJ. Arthrodesis constructs were loaded (19 mm/s) in 3-point bending in a dorsal-to-palmar (plantar) direction using a materials-testing machine. Composite stiffness, yield point, and maximal bending moment at failure were obtained from bending moment-angular deformation curves. Data were analyzed using ANOVA, X(2) analysis, and Fisher's exact tests; the power of the test was calculated when differences were not significant. RESULTS: There were no significant differences in composite stiffness (P >.05; power = 0.8 @ delta = 21.9%), yield point (P >.05; power = 0.8 @ delta = 34.4%), or maximal bending moment (P >.05; power = 0.8 @ delta = 17.8%) between the two fixation techniques. For bDCP constructs, 11% (15 of 140) of the 3.5-mm screws were damaged; 7 of the screw heads pulled through plates where the plates bent, 1 screw head broke off, and 7 screws were bent or pulled out of the phalanx. For nDCP constructs, 8% (8 of 100) of the 4.5-mm screws were damaged; 1 screw head pulled through a plate, 1 screw head broke off, and 6 screws were bent or pulled out of the phalanx. CONCLUSIONS: There were no biomechanical or failure differences between bDCP and nDCP fixation of the PIPJ in horses when evaluated in single-cycle 3-point bending to failure. CLINICAL RELEVANCE: There is no biomechanical advantage to the use of two 7-hole, 3.5-mm bDCP in equine proximal interphalangeal arthrodesis compared with two 5-hole, 4.5-mm nDCP. Two 5-hole, 4.5-mm nDCP may be easier to place, whereas two 7-hole, 3.5-mm bDCP may provide more versatility in fracture repair.  相似文献   

15.
OBJECTIVES: To compare the monotonic biomechanical properties of a prototype equine third metacarpal dynamic compression plate (EM-DCP) fixation with a double broad dynamic compression plate (DCP) fixation to repair osteotomized equine third metacarpal (MC3) bones. STUDY DESIGN: In vitro biomechanical testing of paired cadaveric equine MC3 with a mid-diaphyseal osteotomy, stabilized by 1 of 2 methods for fracture fixation. POPULATION: Twelve pairs of adult equine cadaveric MC3 bones. METHODS: Twelve pairs of equine MC3 were divided into 3 test groups (4 pairs each) for (1) 4-point bending single cycle to failure testing, (2) 4-point bending cyclic fatigue testing, and (3) torsional testing. The EM-DCP (10-hole, 4.5 mm) was applied to the dorsal surface of one randomly selected bone from each pair. Two DCPs, 1 dorsally (10-hole, 4.5 mm broad) and 1 laterally (9-hole, 4.5 mm broad) were applied to the contralateral bone from each pair. All plates and screws were applied using standard AO/ASIF techniques to MC3 bones that had mid-diaphyseal osteotomies. 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 4-point bending yield load, yield bending moment, bending composite rigidity, failure load and failure bending moment of the EM-DCP fixation were significantly greater (P<.0001) than those of the double broad DCP fixation. Mean cycles to failure in 4-point bending of the EM-DCP fixation was significantly greater (P<.0008) than that of the double broad DCP fixation. Mean yield load, composite rigidity, and failure load in torsion of the EM-DCP fixation were significantly greater (P<.0035) than that of the double broad DCP fixation. CONCLUSION: The EM-DCP provides increased stability in both static overload testing and cyclic fatigue testing. CLINICAL RELEVANCE: Results of this in vitro study support the conclusion that the prototype EM-DCP fixation is biomechanically superior to the double broad DCP fixation for the stabilization of osteotomized equine MC3.  相似文献   

16.
Objectives— To compare (1) pullout properties between 3.5 mm cortical and locking screws, and (2) mechanical properties and gap displacements between the 3.5 mm broad limited‐contact dynamic compression plate (LC‐DCP), broad dynamic compression plate (DCP), and narrow locking compression plate (LCP), during axial loading of plate‐stabilized diaphyseal fragments with an interfragmentary gap. Study Design— In vitro mechanical testing of implanted polyurethane foam (PUF) hollow cylinders that simulated compact or osteopenic diaphyseal bone. Sample Population— (1) Five cortical and locking screws and (2) 4 PUF‐plate constructs for each plate type; using high‐ and low‐density (0.8 and 0.32 g/cm3) cylinders. Methods— (1) Screws were completely extracted at 5 mm/min. (2) Plated constructs were axially compressed at 300 N/s for 10 cycles from 5 to 355 N to determine gap displacement during physiologic loading, followed by single cycle increasing load to failure. Results— Pullout properties were not different between screw types. All plate constructs had yield loads over 3 times trotting loads. Gap closure occurred with LC‐DCP and DCP constructs, but not LCP constructs. LCP construct properties were most similar to LC‐DCP and DCP construct properties in the low‐density model. Conclusion— All plate systems sustained physiologic limb loads. Only LCP constructs maintained some gap integrity, although LC‐DCP and DCP screws were placed in neutral position. Clinical Relevance— The LCP system is more likely than LC‐DCP and DCP systems, with neutrally positioned screws, to maintain a planned interfragmentary gap, although gap strains range from 0% to 15% across the 2 mm gap during a trot load.  相似文献   

17.
OBJECTIVES: To compare the monotonic biomechanical properties and fatigue life of a broad, limited contact, dynamic compression plate (LC-DCP) fixation with a broad, dynamic compression plate (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 1 of 2 methods for fracture fixation. ANIMAL POPULATION: Twelve pairs of adult equine cadaveric MC3 bones. METHODS: Twelve pairs of equine MC3 were divided into 3 test groups (4 pairs each) for (1) 4-point bending single cycle to failure testing, (2) 4-point bending cyclic fatigue testing, and (3) torsional single cycle to failure testing. An LC-DCP (8-hole, 4.5 mm) was applied to the dorsal surface of 1 randomly selected bone from each pair. One DCP (8-hole, 4.5 mm broad) was applied dorsally to the contralateral bone from each pair. All plates and screws were applied using standard AO/ASIF techniques to MC3 bones that had mid-diaphyseal osteotomies. Mean test variable values for each method were compared using a paired t-test within each group. Significance was set at P<.05. RESULTS: The mean 4-point bending yield load, yield bending moment, composite rigidity, failure load, and failure bending moment of LC-DCP fixation were significantly greater (P<.01) than those of broad DCP fixation. Mean cycles to failure for 4-point bending was significantly (P<.001) greater for broad DCP fixation compared with broad LC-DCP fixation. Mean yield load, mean composite rigidity, and mean failure load in torsion was significantly (P<.02) greater for broad LC-DCP fixation compared with broad DCP fixation. CONCLUSION: Broad LC-DCP offers increased stability in static overload testing, however, it offers significantly less stability in cyclic fatigue testing. CLINICAL RELEVANCE: The clinical relevance of the cyclic fatigue data supports the conclusion that the broad DCP fixation is biomechanically superior to the broad LC-DCP fixation in osteotomized equine MC3 bones despite the results of the static overload testing.  相似文献   

18.
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   

19.
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   

20.
Objectives— To compare in vitro monotonic biomechanical properties of an axial 3‐hole, 4.5 mm narrow dynamic compression plate (DCP) using 5.5 mm cortical screws in conjunction with 2 abaxial transarticular 5.5 mm cortical screws inserted in lag fashion (DCP‐TLS) with 3 parallel transarticular 5.5 mm cortical screws inserted in lag fashion (3‐TLS) for the equine proximal interphalangeal (PIP) joint arthrodesis. Study Design— Paired in vitro biomechanical testing of 2 methods of stabilizing cadaveric adult equine forelimb PIP joints. Sample Population— Cadaveric adult equine forelimbs (n=15 pairs). Methods— For each forelimb pair, 1 PIP joint was stabilized with an axial 3‐hole narrow DCP (4.5 mm) using 5.5 mm cortical screws in conjunction with 2 abaxial transarticular 5.5 mm cortical screws inserted in lag fashion and 1 with 3 parallel transarticular 5.5 mm cortical screws inserted in lag fashion. Five matching pairs of constructs were tested in single cycle to failure under axial compression, 5 construct pairs were tested for cyclic fatigue under axial compression, and 5 construct pairs were tested in single cycle to failure under torsional loading. Mean values for each fixation method were compared using a paired t‐test within each group with statistical significance set at P<.05. Results— Mean yield load, yield stiffness, and failure load under axial compression and torsion, single cycle to failure, of the DCP‐TLS fixation were significantly greater than those of the 3‐TLS fixation. Mean cycles to failure in axial compression of the DCP‐TLS fixation was significantly greater than that of the 3‐TLS fixation. Conclusion— The DCP‐TLS was superior to the 3‐TLS in resisting the static overload forces and in resisting cyclic fatigue. Clinical Relevance— The results of this in vitro study may provide information to aid in the selection of a treatment modality for arthrodesis of the equine PIP joint.  相似文献   

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