Search Results

Abstract

Objective—To evaluate changes in strain patterns in normal equine hooves following 4-point trimming, using photoelastic stress analysis.

Sample Population—15 equine front limbs with normal hoof configuration.

Procedure—Limbs were disarticulated at the carpometacarpal joint. Weight-bearing surfaces of each hoof were trimmed level to ensure 100% ground contact. Hoof walls were coated with a custom-made strain-sensitive plastic, and limbs were loaded to a third of body weight. Using a polariscope, strain distribution, magnitudes, and directions were evaluated in level hooves as well as before and after standardized 4-point trimming. Repeated-measures ANOVA was used to compare strain magnitudes and directions before and after trimming.

Results—In leveled specimens, strain fields were symmetrically distributed above the heels and at quarter-toe junctions along a line between the middle and distal thirds of the hoof wall. After 4-point trimming, strain epicenters localized above the contact points, whereas strain magnitudes significantly increased by approximately 50%. Decreasing contact area by 50% resulted in an additional significant increase (32%) in strain magnitude. Trimming did not have a significant effect on strain orientations.

Conclusion and Clinical Relevance—This study documents that 4-point trimming results in strain concentration above the hoof contact points and that strain magnitude is dependent on contact area. (Am J Vet Res 2001;62:467–473)

Abstract

OBJECTIVE To determine which method (lateral fabellotibial suture [LFS], tibial plateau leveling osteotomy [TPLO], tibial tuberosity advancement [TTA], or tightrope-like braided multifilament suture secured with metallic buttons [TR]) Veterinary Orthopedic Society (VOS) members preferred for treating cranial cruciate ligament rupture (CCLR) in dogs weighing > 15 kg (33 lb), identify factors associated with this preference, and assess concerns related to surgical implant material used.

DESIGN Cross-sectional study.

SAMPLE 187 VOS members.

PROCEDURES All registered VOS members received an online survey from June to July 2016. Responses were compiled and evaluated for associations with method preferences and perceived complications.

RESULTS Overall response rate was 38.4% (221/575). Respondents had graduated from veterinary school a mean of 23 years prior to survey completion, and collectively they performed approximately 30,000 CCLR surgeries annually. The most commonly preferred method was TPLO (147 [78.6%]), followed by TTA (26 [13.9%]), the LFS procedure (11 [5.9%]), and the TR procedure (3 [1.6%]). The preference for TPLO was independent of board certification or college of training (American, European, or other College of Veterinary Surgeons). Non-board-certified surgeons, including general practitioners, also favored TPLO. The most common perceptions were that titanium implants (used for TTA) were associated with the lowest incidence of major complications, whereas braided multifilament suture (used for the TR procedure) was associated with the highest incidence of major complications.

CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that TPLO was preferred for treating CCLR in dogs weighing > 15 kg and that the TR procedure was perceived as having the highest complication rate. With results of this survey in mind, use of the TR procedure should be considered cautiously when treating CCLR.

Abstract

Objective—To describe a novel interlocking nail (ILN) and locking system and compare the torsional properties of constructs implanted with the novel ILN or a standard 8-mm ILN (ILN8) by use of a gap-fracture model.

Sample Population—8 synthetic specimens modeled from canine tibiae.

Procedures—An hourglass-shaped ILN featuring a tapered locking mechanism was designed. A synthetic bone model was custom-made to represent canine tibiae with a 50-mm comminuted diaphyseal fracture. Specimens were repaired by use of a novel ILN or an ILN8 with screws. Specimens were loaded for torsional measurements. Construct compliance and angular deformation were compared.

Results—Compliance of the ILN8 was significantly smaller than that of the novel ILN. Mean ± SD maximum angular deformation of the ILN8 construct (23.12 ± 0.65°) was significantly greater, compared with that of the novel ILN construct (9.45 ± 0.22°). Mean construct slack for the ILN8 group was 15.15 ± 0.63°, whereas no slack was detected for the novel ILN construct. Mean angular deformation for the ILN8 construct once slack was overcome was significantly less, compared with that of the novel ILN construct.

Conclusions and Clinical Relevance—Analysis of results of this study suggests that engineering of the locking mechanism enabled the novel hourglass-shaped ILN system to eliminate torsional instability associated with the use of current ILNs. Considering the potential deleterious effect of torsional deformation on bone healing, the novel ILN may represent a biomechanically more effective fixation method, compared with current ILNs, for the treatment of comminuted diaphyseal fractures.

Abstract

Objective—To determine whether autologous jugular veins provide functional grafts with high 30-day patency rates in an experimental model of systemic-to-pulmonary shunting performed with a modified Blalock-Taussig procedure.

Animals—15 healthy Beagles.

Procedure—A segment of the left jugular vein was implanted between the left subclavian and pulmonary arteries. Echocardiograms were obtained prior to surgery, at day 4 to 7, and at day 30 after surgery. Selective angiograms were performed immediately after surgery and on day 30. Oximetric shunt calculations were made via terminal angiography prior to euthanasia. Gross and histologic evaluations of the grafts were conducted.

Results—Grafts were patent in 12 of 15 dogs 30 days after surgery as assessed via auscultation, color Doppler ultrasonography, angiography, and histologic examination. Echocardiographic analysis revealed compensatory eccentric left ventricular hypertrophy. Mean pulmonary-to-systemic flow ratio was 1.5:1. Histologic evidence of endothelialization of the anastomotic sites and vein graft arterialization was detectable at 30 days.

Conclusions and Clinical Relevance—Autologous jugular vein grafts were effectively used to create a systemic-to-pulmonary shunt by use of a modified Blalock-Taussig procedure. High patency, ready accessibility, low cost, and theoretical adaptative remodeling during patient growth make autologous jugular vein grafts a valuable alternative to synthetic materials.

Abstract

Objective—To compare the biomechanical properties of pantarsal arthrodesis achieved with a dorsal bone plate-alone (BPA) or pin-plate combination (PPC).

Sample Population—8 pairs of cadaver canine tarsi.

Procedure—Within a pair, 1 tarsus was arthrodesed by use of a 13-hole 3.5-mm broad dynamic compression bone plate applied to the dorsal aspect of the tarsus; the paired tarsus received an identical plate similarly applied, with the addition of an intramedullary pin filling approximately 40% of the tibial medullary canal, spanning the tibiotarsal joint. Plates were instrumented with strain gauges proximal and distal to the solid portion of the plate. Specimens were mounted on a servo-hydraulic testing machine and loaded at 20%, 40%, and 80% of body weight for 10 cycles at 1 Hz. Construct compliance, angular deformation, and plate strain were determined during the 10th cycle.

Results—PPC specimens were less compliant than BPA specimens at all loads and had significantly less angular deformation than BPA specimens at loads of 40% and 80% of body weight. Tibiotarsal gauge microstrain was significantly less in PPC specimens, compared with BPA specimens, regardless of loads. Maximal strains were 33.5% to 40.5% less in PPC than BPA specimens.

Conclusions and Clinical Relevance—For pantarsal arthrodesis in dogs, our results indicate that the PPC construct is biomechanically superior to the BPA construct. By improving construct stability, addition of an intramedullary pin to the traditional BPA technique may lessen implant-related complications and improve plate fatigue life. A subsequent decrease in postoperative morbidity may occur with little addition of time or complexity to the surgical procedure. (Am J Vet Res 2005;66:125–131)

Abstract

Objective—To compare the bending properties of pantarsal arthrodesis constructs involving either a commercially available medial arthrodesis plate (MAP1) or a specially designed second-generation plate (MAP2) implanted in cadaveric canine limbs and evaluate the effect of calcaneotibial screw (CTS) augmentation on the structural properties of both constructs.

Sample Population—5 pairs of canine hind limbs.

Procedures—Within pairs, specimens were stabilized with an MAP1 or MAP2 and loaded to 80% of body weight, with and without CTS augmentation. Compliance, angular deformation (AD), and plate strains were compared.

Results—Construct compliance and AD did not differ between plates. Maximum plate strain was lower in the MAP2 than in the MAP1 (difference of approx 30%). Augmentation with a CTS reduced compliance, AD, and strains in MAP1 constructs but had no effect on those variables in MAP2 constructs.

Conclusions and Clinical Relevance—Because of lower peak strains, the MAP2 may be less susceptible to failure than the MAP1. Furthermore, CTS augmentation was unnecessary with MAP2s, which could minimize intra- and postoperative morbidity. Compared with what is known for dorsal plates, MAP2 constructs were associated with approximately 35% less AD. As a result of improved local stability, one might anticipate earlier fusion of the talocrural joint with an MAP2. In addition, plate peak strain was approximately 3.5 times lower in MAP2s than in dorsal plate constructs, which should result in greater fatigue resistance. The use of MAP2s may be a better alternative to both MAP1s and dorsal plates and could contribute to lower patient morbidity.

Abstract

Objective—To compare structural properties of a plate-rod combination–bone construct (PRCbc) and interlocking nail–bone construct (ILNbc) by use of an experimentally induced gap fracture in canine tibiae.

Sample Population—12 paired canine tibiae.

Procedure—Specimens were implanted with a plate-rod combination consisting of a 3.5-mm, limited-contact, dynamic-compression plate combined with an intramedullary rod or 6-mm interlocking nail. Ostectomy (removal of 10-mm segment) was performed. Paired constructs were loaded for bending, compression, or torsion measurements (4 constructs/group). Compliance was determined by fitting regression lines to the load-position curves at low (initial compliance) and high (terminal compliance) loads.

Results—Bending compliances did not differ significantly between constructs. For the ILNbc, initial compliance was greater than terminal compliance in compression and torsion. Initial compliance and terminal compliance for the PRCbc were similar in compression and torsion. Initial compliance in compression and torsion was greater for the ILNbc, compared with initial compliance for the PRCbc. Maximum deformations in bending and compression were similar between constructs; however, maximum torsional angle was significantly greater for the ILNbc, compared with values for the PRCbc.

Conclusions and Clinical Relevance—The study documented that for an experimentally induced gap fracture in canine tibiae, a plate-rod combination is a significantly less compliant fixation method in torsion and compression, compared with an interlocking nail. Considering the deleterious effects of torsional deformation on bone healing, a plate-rod combination may represent a biomechanically superior fixation method, compared with an interlocking nail, for the treatment of dogs with comminuted tibial diaphyseal fractures. (Am J Vet Res 2005;66:1536–1543)