Comparison of exposure of the radius afforded by the craniomedial and craniolateral open surgical approaches in dog cadavers

Management of antebrachial fractures in dogs typically involves open reduction and bone plate stabilisation of the radius performed using either a craniomedial approach (CMA) or craniolateral approach (CLA). The aim of this cadaveric study was to compare radial exposure afforded via the craniomedial and craniolateral approaches, without and with releasing the abductor digiti I longus (ADIL) muscle. The CMA and CLA were performed on alternate paired cadaver forelimbs with the subsequent release (CMA) or elevation (CLA) of the ADIL muscle (n = 12). The percent area of exposure was calculated in defined longitudinal radial segments (LRSs) and hemi-circumferential radial segments (HRSs) using digitally uploaded images. A non-parametric rank sum test was used for statistical analysis (p < 0.05). While both the CMA and CLA provided sufficient exposure for radial cranial plate placement in the mid-to-distal diaphyseal region (50-80% LRSs), the CMA afforded greater exposure to the distal metaphysis (80-90% LRS). The CLA was advantageous in exposing the proximal diaphysis (20-50% LRSs) and distal epiphysis (90-100% LRS). Exposure of the distal diaphyseal, metaphyseal, and epiphyseal regions (80-100% LRSs) was impeded by the ADIL muscle. A tenotomy of the tendon of insertion of the ADIL muscle increased exposure afforded by the CMA in the distal metaphyseal and epiphyseal regions. The exposure afforded by the CLA in the distal diaphyseal and metaphyseal regions was significantly improved by elevating the origin of the ADIL muscle. The results of this study provide useful clinical information when surgeons are deciding which approach to use for cranial radial plating.

Use of Preoperative 3D Virtual Planning and 3D-Printed Patient-Specific Guides to Facilitate a Single-Stage Cranial Closing Wedge Ostectomy and Tibial Plateau Leveling Osteotomy Procedure to Address Proximal Tibial Deformity, an Excessive Tibial Plateau Angle, and Cranial Cruciate Ligament Insufficiency in a Dog

A 9-month-old mixed-breed dog was presented for bilateral proximal tibial deformity resulting in an excessive tibial plateau angle and cranial cruciate ligament insufficiency. Initial surgical management of the right pelvic limb was done by performing a cranial closing wedge ostectomy. Inadequate leveling of the plateau resulted in a postliminal meniscal tear which was addressed during a revision tibial plateau leveling osteotomy. The left pelvic limb was managed in a single-session surgery using three-dimensional (3D) virtual surgical planning and custom 3D-printed surgical guides to perform a combined cranial closing wedge ostectomy and tibial plateau leveling osteotomy. Postoperative 3D analysis of the left tibia revealed the accuracy of the surgical result within 2° of the virtual surgical plan. The dog developed a transient grade II/IV left medial patellar luxation following surgery but ultimately attained a full functional recovery and was actively engaged in competitive agility work 46 months following surgery on the left pelvic limb.

An assessment of the fixin tplo jig to generate effective compression using a transverse fracture model

The objective of this study was to determine compressive loads that could be generated using a tibial plateau leveling osteotomy (TPLO) jig with a tensioned strand of 18-gauge stainless steel orthopedic wire in a simulated transverse fracture model. The wire was sequentially tensioned using heavy needle holders or an AO wire tightener. Recorded loads were subsequently compared to loads generated by applying a 3.5 mm limited contact-dynamic compression plate (LC-DCP) as a compression plate. Two segments of 2 cm diameter Delrin rod were placed in a testing apparatus and used to simulate a transverse fracture. A load cell was interposed between the two segments to measure the compressive loads generated during the application of the TPLO jig or the LC-DCP. Compression was generated by sequential tensioning a strand of 18-gauge wire secured through the base of the arms of the TPLO jig or by placing one or two load screws in the LC-DCP. Wires were tensioned using heavy needle holders or an AO wire tightener. Eight replicates of each construct were tested. Recorded loads were compared using a one-way repeated measures ANOVA and Tukey Honestly Significant Difference test. The wire being tensioned broke while attempting a second quarter rotation of the needle holders and when the crank handle of the AO wire tightener was advanced beyond two rotations. The mean + SD peak compressive loads recorded when tensioning the wire using the heavy needle holders and AO wire tightener was 148 ± 7 N and 217 ± 16 N, respectfully. The mean ± SD load recorded after placement of the first and second load screw in the LC-DCP was 131 ± 39 N and 296 ± 49 N, respectively. The compression generated by placing two load screws in the LC-DCP was superior to the compression generated using the jig. The maximum load recorded by tensioning the wire secured through the TPLO jig using the AO wire tightener was superior to the compression generated by placing a single load screw and tensioning the wire using needle holders. Our results demonstrate that the TPLO jig allows surgeons to compress transverse fractures or osteotomies effectively. Tensioning the AO wire tightener allows for sequential tensioning and generates superior compressive loads than tensioning wires with heavy needle holders.

Evaluation of a 3-D printed drill guide to facilitate fluoroscopic-assisted Kirschner wire placement for minimally invasive iliosacral screw placement in dog cadavers

OBJECTIVE

To evaluate the ease and accuracy of using a 3-D printed (3-DP) drill guide to insert Kirschner wires through the ilium and into the sacral body in preparation for minimally invasive iliosacral screw placement in dog cadavers.

ANIMALS

10 dog cadavers weighing 20 to 30 kg (mean ± SD, 24.5 ± 5 kg).

METHODS

Kirschner wires were placed using a limited approach to the lateral ilium. Fluoroscopy was used in freehand and 3-DP drill guide application groups to facilitate the placement of a 1.0-mm Kirschner wire that was over-drilled using a 2.5-mm cannulated drill bit. Kirschner wires were placed using a 3-DP drill guide on 1 hemipelvis and freehand wire placement was done on the contralateral hemipelvis. Postprocedural CTs were obtained, and 2-D and 3-D analyses were performed. The Student t-test and Wilcoxon rank sum test were used to compare groups. A Pearson correlation coefficient was performed to evaluate the in-group correlation.

RESULTS

Likert scores that assessed the ease of the procedure were significantly greater (P = .04) and the incision length was significantly shorter (P = .016) in the 3-DP drill guide group compared with the freehand group. The time of the procedure, the number of attempts to obtain accurate Kirschner wire placement, and fluoroscopy images did not differ (P > .05) between application groups. Drill tracks were primarily confined to the sacral body, with minor projected screw thread cortical breeches occurred in 1 cadaver in the freehand group and 2 cadavers in the 3-DP drill guide group.

CLINICAL RELEVANCE

The 3-DP drill guide simplified appropriate iliosacral Kirschner wire placement through a smaller incision compared with freehand drilling and would appear to be an efficient, practical instrument to facilitate accurate fluoroscopic-assisted screw placement when stabilizing sacroiliac luxations in dogs.

Minimally invasive plate osteosynthesis of femoral fractures with 3D-printed bone models and custom surgical guides: A cadaveric study in dogs

OBJECTIVE

Assess the accuracy and efficiency of reduction provided by application of plates precontoured to 3-dimensional (3D)-printed femoral bone models using a custom fracture reduction system (FRS) or intramedullary pin (IMP) to facilitate femoral minimally invasive plate osteosynthesis (MIPO) in dogs.

STUDY DESIGN

Experimental cadaveric study.

SAMPLE POPULATION

Seven dog cadavers.

METHODS

Virtual 3D femoral models were created using computed tomographic images. Simulated, virtual mid-diaphyseal femoral fractures were created and reduced. Reduced femoral models were 3D-printed and a plate was contoured. Custom drill guides for plate screw placement were designed and 3D-printed for the FRS. Mid-diaphyseal simulated comminuted fractures were created in cadavers, and fractures were aligned using FRS or IMP and stabilized with the precontoured plates. Number of fluoroscopic images acquired per procedure and surgical duration were recorded. Computed tomographic scans were repeated to assess femoral length and alignment.

RESULTS

Compared to the preoperative virtual plan, median change in femoral length and frontal, sagittal, and axial alignment was less than 3 mm, 2°, 3°, and 3° postoperatively, respectively, in both reduction groups. There was no difference in length or alignment between reduction groups (P > .05). During FRS, fewer fluoroscopic images were taken (P = .001), however, surgical duration was longer than IMP procedures (P = .011).

CONCLUSION

Femoral alignment was accurate when using plates precontoured to 3D printed models, regardless of reduction method.

CLINICAL SIGNIFICANCE

Accurate plate contouring using anatomically accurate models may improve fracture reduction accuracy during MIPO applications. Custom surgical guides may reduce fluoroscopy use associated with MIPO.

Stifle kinematics in 4 dogs with cranial cruciate ligament insufficiency treated by CORA-based leveling osteotomy

Objective

The purpose of this study was to quantify three-dimensional (3D) stifle kinematics during walking in dogs with complete cranial cruciate ligament insufficiency (CCL-I) treated with a CORA-based leveling osteotomy (CBLO).

Study design

Four client-owned dogs with unilateral complete CCL-I were prospectively enrolled. Custom digital 3D models of the femora and tibiae were created from pre-and postoperative computed tomographic scans for each dog. Lateral view fluoroscopic images were collected during treadmill walking preoperatively and 6 months after CBLO. Results were generated using a 3D-to-2D image registration process. Pre-and postoperative stifle kinematics (craniocaudal translation, extension angle) were compared to that of the unaffected contralateral (control) stifle. Force plate gait analysis was performed, and symmetry indices (SI) were calculated for peak vertical force (PVF) and vertical impulse (VI).

Results

After CBLO, craniocaudal femorotibial motion was reduced by a median (range) of 43.0 (17.0–52.6) % over the complete gait cycle. Median (range) PVF SI was 0.49 (0.26–0.56) preoperatively and 0.92 (0.86–1.00) postoperatively, and VI SI was 0.44 (0.20–0.48) preoperatively and 0.92 (0.82–0.99) postoperatively.

Conclusion

CBLO mitigated but did not fully resolve abnormal craniocaudal translation; lameness was substantially improved at 6 months.

Frequency dependent growth of bacteria in living materials

The fusion of living bacteria and man-made materials represents a new frontier in medical and biosynthetic technology. However, the principles of bacterial signal processing inside synthetic materials with three-dimensional and fluctuating environments remain elusive. Here, we study bacterial growth in a three-dimensional hydrogel. We find that bacteria expressing an antibiotic resistance module can take advantage of ambient kinetic disturbances to improve growth while encapsulated. We show that these changes in bacterial growth are specific to disturbance frequency and hydrogel density. This remarkable specificity demonstrates that periodic disturbance frequency is a new input that engineers may leverage to control bacterial growth in synthetic materials. This research provides a systematic framework for understanding and controlling bacterial information processing in three-dimensional living materials.

Efficacy of two reduction methods in conjunction with 3-D-printed patient-specific pin guides for aligning simulated comminuted tibial fractures in cadaveric dogs

OBJECTIVE

To assess the feasibility and accuracy of using 2 methods for reduction and alignment of simulated comminuted diaphyseal tibial fractures in conjunction with 3-D-printed patient-specific pin guides.

SAMPLE

Paired pelvic limbs from 8 skeletally mature dogs weighing 20 to 35 kg.

METHODS

CT images of both tibiae were obtained, and 3-D reconstructions of the tibiae were used to create proximal and distal patient-specific pin guides. These guides were printed and used to facilitate fracture reduction and alignment in conjunction with either a 3-D-printed reduction guide or a linear type 1A external fixator. Postreduction CT images were used to assess the accuracy of pin guide placement and the accuracy of fracture reduction and alignment.

RESULTS

The 3-D-printed guides were applied with acceptable ease. Guides for both groups were placed with minor but detectable deviations from the planned location (P = .01), but deviations were not significantly different between groups. Fracture reduction resulted in similar minor but detectable morphological differences from the intact tibiae (P = .01). In both groups, fracture reduction and alignment were within clinically acceptable parameters for fracture stabilization by means of minimally invasive plate osteosynthesis.

CLINICAL RELEVANCE

Virtual surgical planning and fabrication of patient-specific 3-D-printed pin guides have the potential to facilitate fracture reduction and alignment during use of minimally invasive plate osteosynthesis for fracture stabilization.

Accuracy of virtual surgical planning and custom three-dimensionally printed osteotomy and reduction guides for acute uni- and biapical correction of antebrachial deformities in dogs

OBJECTIVE

To report clinical experience using virtual surgical planning (VSP) and surgical application of 3D printed custom surgical guides to facilitate uni- and biapical correction of antebrachial deformities in dogs.

ANIMALS

11 dogs (13 antebrachial deformity corrections).

PROCEDURES

Using CT-based bone models, VSP was performed, and surgical guides were designed and 3D printed. The guides were used to execute osteotomies and align bone segments. Postoperative CTs were obtained to compare limb alignment with the VSP. Long-term assessment of lameness and cosmesis were compared with preoperative status.

RESULTS

Guides were successfully utilized and postoperative analysis was available for 10 of 13 deformities. Guides were abandoned in 2 deformities due to soft tissue tension. Evaluation of postoperative frontal, sagittal, axial, and translational limb alignment revealed that over 90% of parameters were within the acceptable range of ≤ 5° angulation and rotation or ≤ 5 mm of translation from the VSP. Lameness scores were improved in 7/8 deformities with associated preoperative lameness, and posture was improved in 10/10 deformities in which guides were deployed. Complications included reduced range of carpal motion (n = 2), implant sensitivity (n = 2), fracture (n = 1), and tendon laceration (n = 1).

CLINICAL RELEVANCE

VSP and customized surgical guide application facilitated accurate antebrachial limb deformity correction in the majority of deformities in this case series. The use of VSP and 3D printed guides would appear to be a viable and accurate approach for correction of both uni- and biapical antebrachial deformities in dogs.

A review of minimally invasive fracture stabilization in dogs and cats

OBJECTIVE

To summarize and discuss peer-reviewed studies on minimally invasive osteosynthesis (MIO) of long bone, physeal, and articular fractures in dogs and cats.

STUDY DESIGN

Invited review.

METHODS

A critique of literature was performed to assess MIO feasibility, outcomes, and complications through PubMed, Scopus, and CAB abstracts research databases (2000-2020).

RESULTS

More than 40 MIO articles have been published in the last 15 years, but most studies had small numbers, lacked control groups, and used limited outcome measures. Studies generally showed that MIO was feasible in dogs and cats with low complication rates. The current evidence does not demonstrate superior bone healing or functional outcomes with MIO when compared to standard methods. Although treatment principles, case selection, and techniques varied depending on the anatomical location, there were no salient differences in complication rates among long bones, physeal, and articular fractures treated by MIO.

CONCLUSION

The current available evidence and the personal experience of the authors support MIO as a promising fracture management modality. MIO can yield excellent outcomes when applied in carefully selected cases, performed by surgeons experienced in the technique. We cannot, however, conclude that MIO is superior to open fracture stabilization based on the available evidence in veterinary literature. Randomized controlled studies are warranted to prospectively compare MIO with other osteosynthesis techniques and thereby validate its role in fracture management for dogs and cats.

Use of a hybrid external skeletal fixator construct for managing tibial tuberosity avulsion fractures in three dogs

CASE DESCRIPTION

3 juvenile (4 to 5 months of age) medium- to large-breed or crossbred dogs were evaluated for sudden unilateral non-weight-bearing lameness in a pelvic limb after a fall during strenuous activity.

CLINICAL FINDINGS

All dogs had non-weight-bearing lameness (n = 2) or bore minimal weight (1) on the affected pelvic limb, had soft tissue swelling over the cranial aspect of the stifle joint in the affected limb, seemed to resist manipulation of the affected joint, and had tibial tuberosity avulsion fracture confirmed with radiography.

TREATMENT AND OUTCOME

Each dog underwent surgical fracture reduction and stabilization with a hybrid circular-linear external skeletal fixator construct with interfragmentary Kirschner wires used to stabilize the avulsed tibial tuberosity. Successful fracture reduction and stabilization were achieved, and only minor postoperative complications occurred. Construct removal 2 weeks postoperatively resulted in no displacement of the tibial tuberosity in 2 dogs and only minor proximal displacement in the remaining dog, allowed for continued unencumbered growth through the apophysis and proximal tibial epiphysis in all dogs, and did not result in tibial conformational anomalies. Clinical outcome was considered excellent in 2 dogs with complete resolution of lameness and good in 1 dog with subsequent occasional mild lameness.

CLINICAL RELEVANCE

Our findings suggested that the described hybrid external skeletal fixator construct could be used as a minimally invasive strategy to successfully manage tibial tuberosity avulsion fractures in dogs and may be advantageous in very young medium- to large-breed dogs in which premature closure of the tibial tuberosity apophysis could result in distal translocation of the tibial tuberosity and deformity of the tibial plateau.

Biomechanical Comparison of Three Stabilization Methods for Tibial Tuberosity Fractures in Dogs: A Cadaveric Study

OBJECTIVE

 The aim of this study was to compare the biomechanical properties of a hybrid external skeletal fixator (HESF) construct to the placement of paired interfragmentary Kirschner wires alone, and pin and tension band wire (PTBW) fixation for the stabilization of simulated tibial tuberosity fractures in dogs.

STUDY DESIGN

 Tibias were harvested from 12 skeletally mature dog cadavers weighing 20 to 30 kg. An osteotomy was made through the base of the tibial tuberosity, which was subsequently repaired with either paired Kirschner wires, PTBW fixation or a HESF. A tensile load was applied to the tibial tuberosity until failure occurred. Mode of failure was described and biomechanical parameters obtained were compared between fixation groups.

RESULTS

 The PTBW fixation and HESF construct afforded greater stiffness and load at 3 mm of axial displacement compared with fixation with Kirschner wires alone. There was no significant difference in stiffness and load at 3 mm displacement between PTBW and HESF fixation. Failure occurred by bending and pullout of the Kirschner wires for all fixation groups, preceded by untwisting of the knot in PTBW specimens.

CONCLUSION

 The HESF may provide a favourable alternative to PTBW fixation for tibial tuberosity avulsion fracture stabilization in dogs with substantial remaining growth potential.

In vivo three-dimensional knee kinematics in goats with unilateral anterior cruciate ligament transection

Although the goat is an established animal model in anterior cruciate ligament (ACL) research, in vivo kinematics associated with ACL deficiency have not been previously described in this species. Three-dimensional knee kinematics were determined before and after unilateral ACL transection in eight goats. Fluoroscopic imaging of the knees during treadmill walking and force-platform gait analysis during over-ground walking were performed prior to ACL transection, and 2 weeks, 3 months, and 6 months after ACL transection. Transient lameness of the ACL-transected limb was noted in all goats but resolved by 3 months post-ACL transection. Increased extension of 8.7° to 17.0° was noted throughout the gait cycle in both the ACL-transected and the contralateral unaffected knees by 3 months post-ACL transection, in a bilaterally symmetric pattern. Peak anterior tibial translation increased by 3 to 6 mm after ACL transection and persisted over the 6-month study period. No changes in axial rotation or abduction angle were observed after ACL transection. Unilateral ACL deficiency in goats resulted in persistent kinematic alterations, despite the resolution of lameness by 3 months post-ACL transection.

Subsequent meniscal tears following tibial tuberosity advancement and tibial plateau leveling osteotomy in dogs with cranial cruciate ligament deficiency: An in vivo experimental study

OBJECTIVE

To evaluate the short- and mid-term effects of tibial tuberosity advancement (TTA) and tibial plateau leveling osteotomy (TPLO) on subsequent meniscal tears.

STUDY DESIGN

Experimental in vivo study.

ANIMALS

Purpose-bred beagle dogs (n = 15).

METHODS

For each dog, the cranial cruciate ligaments were transected; one limb underwent TTA and the other limb underwent TPLO. Orthopedic and radiographic examinations were performed preoperatively and at 12 and 32 weeks postoperatively. Gross evaluation of the stifle joint was performed after euthanasia at 12 (n = 10) and 32 (n = 5) weeks.

RESULTS

Lameness scores were not different between TTA and TPLO limbs at any time point. Radiographic osteoarthritis scores of TTA stifles (1.33 ± 0.49) were higher than TPLO stifles (0.67 ± 0.49) (p = .002) at 12 weeks postoperatively, but there was no difference between groups at 32 weeks postoperatively. Subsequent medial meniscal tears occurred in 6/10 TTA stifles, and 0/10 TPLO stifles at 12 weeks postoperatively and in 5/5 TTA stifles, and 1/5 TPLO stifles at 32 weeks postoperatively. Subsequent lateral meniscal tears occurred in 4/5 TTA stifles at 32 weeks postoperatively. Medial meniscal total gross pathology score was higher in TTA than TPLO stifles. TTA stifles had more articular cartilage damage when compared with TPLO stifles at 32 weeks postoperatively.

CONCLUSION

In this within-dog experimental comparison, subsequent medial meniscal tears and cartilage injury was more prevalent following TTA when compared to TPLO.

CLINICAL SIGNIFICANCE

In an experimental model, TPLO protects the medial meniscus and articular cartilage better than TTA in stifles with complete cranial cruciate ligament deficiency.

Femorotibial joint kinematics in nine dogs treated with lateral suture stabilization for complete cranial cruciate ligament rupture

OBJECTIVE

To quantify 3-D femorotibial joint kinematics during ambulation in dogs with cranial cruciate ligament (CCL) rupture treated with lateral fabellotibial suture stabilization (LFTS).

ANIMALS

9 adult dogs (body weight, 15 to 35 kg [33 to 77 lb]) with unilateral complete CCL rupture.

PROCEDURES

Digital 3-D bone models of the femur and fabellae and tibia and fibula were created from CT scans. Lateral fluoroscopic images of stifle joints were collected during treadmill walking before surgery and 6 months after LFTS. The LFTS was performed with nylon leader material secured with knots. Gait cycles were analyzed with a 3-D to 2-D image registration process. Femorotibial joint kinematics (craniocaudal translation, internal-external rotation, and flexion and extension angles) were compared among CCL-deficient stifle joints before LFTS, CCL-deficient stifle joints 6 months after LFTS, and unaffected contralateral (control) stifle joints. Owners and veterinarians subjectively assessed lameness by use of a visual analog scale and gait examination, respectively, at each time point.

RESULTS

At midstance phase, medial cranial tibial translation decreased from 9.3 mm before LFTS to 7.6 mm after LFTS but remained increased when compared with control stifle joint values. Following LFTS, axial rotation and stifle joint flexion and extension angles were not significantly different from control stifle joints. On the owner survey, the median walking lameness score improved from 9.3 of 10 before surgery to 0.3 after surgery. On gait examination, median walking lameness score improved from 2 of 4 before surgery to 0 after surgery.

CONCLUSIONS AND CLINICAL RELEVANCE

Stifle joint instability was only slightly mitigated at 6 months following LFTS performed with knotted nylon leader material in medium to large dogs with CCL rupture, despite improvement in lameness.

Three-dimensional-printed custom guides for bipolar coxofemoral osteochondral allograft in dogs

The objective of this experimental study was to develop and evaluate a three-dimensionally printed custom surgical guide system for performing bipolar coxofemoral osteochondral allograft transplantation in dogs. Five cadaver dogs, weighing 20–38 kg were used in the study. Custom surgical guides were designed and three-dimensionally printed to facilitate accurate execution of a surgical plan for bipolar coxofemoral osteochondral allograft transplantation. Guide-assisted technique was compared to freehand technique in each cadaver. Surgical time was recorded and postoperative computed tomography and three-dimensional segmentation was performed. Femoral version and inclination angles, femoral neck length, and gap present at the femoral and acetabular donor-recipient interface was compared between the virtual surgical plan and postoperative outcome for both techniques. One-tailed paired t-test (P < .05) was used for statistical analysis. When compared to free-hand preparation, mean donor femoral preparation time was 10 minutes longer and mean recipient preparation time was 2 minutes longer when using guides (p = 0.011 and p = 0.001, respectively). No difference in acetabular preparation time was noted between groups. Gap volume at the acetabular and femoral donor-recipient interface was not different between groups. Mean difference between the planned and postoperative version angle was 6.2° lower for the guide group when compared to the freehand group (p = 0.025). Mean femoral neck length was 2 mm closer to the plan when using guides than when performing surgery freehand (p = 0.037). Accuracy for femoral angle of inclination was not different between groups. Custom surgical guides warrants consideration in developing bipolar coxofemoral osteochondral allograft transplantation as an alternative surgical technique for managing hip disorders in dogs.

Use of a circular fixator construct to facilitate closed reduction and percutaneous stabilization of a distal femoral physeal fracture in a dog

Background:

Fractures of the distal femoral physis are the most common physeal fracture sustained by skeletally immature dogs. Reduction and stabilization of these fractures can sometimes be achieved through closed reduction, primarily in fractures that are nominally displaced. Circular external fixator constructs have been used to assist in indirect, closed reduction of fractures at other anatomic locations in dogs and this report describes application of this method to reduce a displaced Salter-Harris type II fracture of the distal femur in a 1-year-old dog.

Case Description:

A 1-year-old female spayed Akita was referred for treatment of a Salter-Harris type II fracture of the right distal femur. The epiphyseal segment was laterally and slightly caudally displaced. Multiple attempts to manually reduce the fracture during surgery were unsuccessful, so a two-ring circular external fixator construct was applied to facilitate distraction and reduction. The construct was applied by placing a medial-to-lateral Kirschner wire in both the mid-femoral diaphysis and in the distal femoral epiphysis. Distraction of the construct provided sufficient separation of the fracture segments to facilitate near anatomic reduction. The fracture was stabilized with two percutaneously placed Steinmann pins placed in Rush fashion. Radiographic union was confirmed 5 weeks after surgery. The dog was not lame and was bearing more weight on the right pelvic limb, as assessed using force plate analysis, 9 months following surgery. Goniometric measurements of stifle range of motion and thigh muscle circumference were similar between the pelvic limbs.

Conclusion:

Application of a two-ring circular construct would appear to be useful to facilitate closed reduction and percutaneous stabilization of distal femoral physeal fractures.

Calcium sulfate antibiotic-impregnated bead implantation for deep surgical site infection associated with orthopedic surgery in small animals

OBJECTIVE

To report the outcomes and complications associated with antibiotic-impregnated calcium sulfate beads for prevention and treatment of orthopedic-related surgical site infection (SSI) in companion animals.

STUDY DESIGN

Retrospective case series.

ANIMALS

Client-owned cats (n = 2) and dogs (n = 14).

METHODS

Medical records of 16 cases in which implantation of antibiotic-impregnated calcium sulfate beads was performed for the prevention or treatment of SSI were reviewed. Information collected included signalment, prior surgery, reason for bead placement, antibiotics used, bacterial culture results, and clinical outcomes.

RESULTS

Surgical site infection resolved in six of 10 animals treated therapeutically and did not occur in six of six animals treated prophylactically. Susceptibility of the causative bacteria to the antibiotic implanted was confirmed in five of six cases with resolved SSI treated therapeutically but in only one of four cases with unresolved SSI treated therapeutically. Complications directly related to bead placement were evident in only one case in which beads extruded from external skeletal fixator pin tracts 7 days after implantation. At final follow-up, 11 of 12 animals without SSI had satisfactory limb use and no clinical, cytologic, or radiographic evidence of infection.

CONCLUSION

Implantation was well tolerated. Resolution of SSI was inconsistent; however, when bacteria were susceptible to the antibiotic implanted, SSI resolved in all but one case.

CLINICAL SIGNIFICANCE

Antibiotic-impregnated calcium sulfate beads could be considered for prevention or treatment of orthopedic SSI in small animals. A prospective clinical study is required to obtain additional information, including the value of preoperative bacterial culture.

Long-term outcome following cranial biceps brachii tendon transposition in a dog with a traumatic cranial scapulohumeral luxation

Background:

Cranial luxation of the scapulohumeral has been rarely reported in dogs and there is limited information available regarding surgical management of this condition, particularly with respect to long-term functional outcomes.

Case Description:

This report describes the successful resolution of a chronic traumatic cranial scapulohumeral joint luxation in a dog that was stabilized by cranial transposition of the biceps brachii tendon of origin. At surgery, an osteotomy of the greater tubercle was performed and a trough was made in the exposed bed of the osteotomy. The transverse humeral ligament was incised, and the bicipital tendon was levered into the trough and secured in that location by reattachment of the greater tubercle using multiple Kirschner wires and a figure-of-eight tension band wire. Postoperatively, the dog was maintained in a Spica splint for 2 weeks. Although surgical reduction was performed 4 months after the original injury, the luxation did not recur and the dog did not have appreciable lameness 14 months following the surgery.

Conclusion:

Although cranial transposition of the bicipital tendon is an invasive procedure, this dog’s scapulohumeral luxation did not recur and the procedure yielded an excellent long-term functional outcome.

Evaluation of a novel technique involving ultrasound-guided, temporary, percutaneous gastropexy and gastrostomy catheter placement for providing sustained gastric decompression in dogs with gastric dilatation-volvulus

OBJECTIVE

To evaluate the feasibility of ultrasound-guided, temporary, percutaneous T-fastener gastropexy (TG) and gastrostomy catheter (GC) placement for providing sustained gastric decompression in dogs with acute gastric dilatation-volvulus (GDV) and to compare findings with those of trocarization.

ANIMALS

16 dogs with GDV.

PROCEDURES

Dogs were randomly assigned to undergo gastric decompression by means of percutaneous trocarization (trocar group; n = 8) or temporary TG and GC placement (TTG+GC group; 8) with ultrasound guidance. The gastric volvulus was then surgically corrected, and the decompression sites were examined. Outcomes were compared between groups.

RESULTS

The proportion of dogs with successful decompression did not differ significantly between the TTG+GC (6/8) and trocar (7/8) groups; median procedure duration was 3.3 and 3.7 minutes, respectively. After the failed attempts in the TTG+GC group, the procedure was modified to include ultrasound guidance during T-fastener placement. The decrease in intragastric pressure by 5 minutes after trocar or GC insertion was similar between groups. For dogs in the TTG+GC group, no significant difference in intragastric pressure was identified between 5 and 60 minutes after GC insertion. Complications included inadvertent splenic or jejunal placement in 2 dogs (TTG+GC group) and malpositioned and ineffective trocar placement in 1 dog (trocar group). All dogs survived for at least 2 weeks.

CONCLUSIONS AND CLINICAL RELEVANCE

Ultrasound-guided, temporary, percutaneous TG and GC placement was safe and effective at providing sustained gastric decompression in dogs with GDV, suggesting that this technique would be ideal for dogs in which surgical delays are anticipated or unavoidable.

Biomechanical Comparison of Two Conical Coupling Plate Constructs for Cat Tibial Fracture Stabilization

OBJECTIVE

 This study aimed to compare the biomechanical characteristics of two conical coupling plate (CCP) constructs in an ex vivo feline tibial fracture gap model.

STUDY DESIGN

 Paired tibiae harvested from eight recently euthanatized cats were alternately assigned to one of two stabilization groups. One tibia was stabilized with a standard, 6-hole, 2.5-mm CCP and the contralateral tibia was stabilized with a 6-hole, 2.5-mm prototype CCP (pCCP). Non-destructive cyclic four-point craniocaudal bending, mediolateral bending and axial compression testing were performed, and stiffness was recorded. The specimens were then loaded to failure in axial compression, and yield and failure loads were recorded.

RESULTS

 During non-destructive testing, the pCCP constructs were significantly stiffer than the CCP constructs in both modes of bending and axial loading. Both constructs demonstrated significantly greater craniocaudal bending stiffness compared with mediolateral bending. Yield load and failure load were significantly greater for the pCCP constructs.

CONCLUSION

 The augmented design of the pCCP yielded superior mechanical characteristics during both non-destructive and destructive testings compared with constructs employing standard CCP. The more rigid design of the pCCP suggests that this implant may be better at withstanding greater loads, particularly when applied in a bridging fashion, during the postoperative convalescence. Further investigations are warranted to prospectively evaluate the clinical performance of the pCCP.

Use of combined transarticular pinning and external skeletal fixation for the reduction and stabilization of multiple metatarsophalangeal luxations in a cat

Case summary

A 1-year-old spayed female domestic shorthair cat presented for evaluation of a non-weight bearing right pelvic limb lameness after falling from a 4 m height. On orthopedic examination there was substantial swelling and pain on manipulation of the right pes. Radiographs were obtained under sedation, and these revealed dorsoproximal luxations of the third, fourth and fifth metatarsophalangeal joints, and lateral rotation of the second digit. Closed manual reduction under sedation was unsuccessful and open reduction under general anesthesia was therefore performed. Combined transarticular pinning and external skeletal fixation were performed to maintain reduction of the third and fourth digits. Marked postoperative swelling of the distal pes and internal rotation of the third and fourth digits were noted within 24 h of surgery. Three weeks postoperatively, the cat had a persistent weight bearing right pelvic limb lameness and minor pin tract inflammation. All implants were removed and the limb was splinted for 1 week. Internal rotation and pin tract inflammation had resolved at the time of splint removal, and the lameness resolved within 6 weeks of surgery. The cat was not lame, but radiographs revealed mild-to-moderate degenerative osteoarthrosis when the cat was evaluated 6 months after surgery.

Relevance and novel information

There are limited reports describing metatarsophalangeal luxations in cats. Although several surgical techniques have been advocated, specific outcomes in clinical cases have not been reported. This report describes the clinical application and outcome of combined transarticular pinning and external skeletal fixation for the management of multiple metatarsophalangeal luxations in a cat.

Intra-Articular Umbilical Cord Derived Mesenchymal Stem Cell Therapy for Chronic Elbow Osteoarthritis in Dogs: A Double-Blinded, Placebo-Controlled Clinical Trial

Background: Intra-articular stem cell therapy may help alleviate lameness caused by osteoarthritis in dogs. Umbilical cord-derived stem cell (UMSC) therapy has not yet been investigated in a veterinary clinical study. We hypothesized that dogs treated with intra-articular UMSC will have improved limb function and quality of life when compared to dogs treated with a saline placebo injection. Methods: This was a prospective, double-blinded, placebo-controlled clinical trial in client-owned dogs with chronic elbow osteoarthritis with a follow-up time of 6 months. Dogs were assigned to receive intra-articular UMSC (n = 38) or a saline placebo intra-articular injection (n = 30). Outcome measures included the Canine Brief Pain Inventory score (CBPI) and peak vertical force (PVF) from force-platform gait analysis. Treatment was considered successful when there was a decrease in the Pain Severity Score of at least one and a decrease in the Pain Interference Score of at least one from baseline. Success rates and PVF were compared between groups. Results: No adverse effects associated with UMSC were noted. Of the dogs completing the study, treatment success in the UMSC (n = 28) vs. placebo groups (n = 23) was observed in 54 vs. 28% of dogs at 1 month, 50 vs. 27% at 3 months, and 46 vs. 14% at 6 months, respectively. Success rate in the UMSC group was significantly higher than the placebo group at 1 and 6 months after treatment. However, no differences in PVF of the affected limb over time was observed in either group. Conclusions: Intra-articular UMSC for osteoarthritis may improve clinical signs based on owner observations.

Biomechanical Comparison of Two Locking Plate Constructs for the Stabilization of Feline Tibial Fractures

OBJECTIVES

 The aim of this study was to compare the biomechanical characteristics of locking compression plate (LCP) and conical coupling plate (CCP) constructs for the stabilization of experimentally induced gap fractures in cat tibiae.

MATERIALS AND METHODS

 Pelvic limbs were harvested from eight cat cadavers. Paired tibiae were stripped of all soft tissues, and randomly assigned to the LCP or CCP stabilization group. An eight-hole 2.7 mm LCP or a six-hole 2.5 mm CCP was applied to the medial surface of each tibia. A 1-cm segment of the tibia was excised centrally beneath the plate. The specimens were potted, then tested in non-destructive four-point craniocaudal and mediolateral bending, followed by non-destructive axial compression. Each construct was subsequently loaded to failure in axial compression. Bending and axial stiffness, yield load and failure load were calculated for each specimen.

RESULTS

 The LCP constructs were significantly stiffer than the CCP constructs when subjected to non-destructive bending and axial loading. Craniocaudal bending stiffness was significantly greater than mediolateral bending stiffness for both constructs. Yield load and failure load were significantly greater for LCP constructs compared with CCP constructs.

CLINICAL SIGNIFICANCE

 LCP may be a more suitable implant for stabilizing complex diaphyseal tibial fractures in cats. Additional supplemental fixation should be considered when using CCP to stabilize unreconstructed diaphyseal tibial fractures in cats. Further clinical investigation of both implants is recommended.

Femorotibial kinematics in dogs treated with tibial plateau leveling osteotomy for cranial cruciate ligament insufficiency: An in vivo fluoroscopic analysis during walking

OBJECTIVE

To determine the ability of tibial plateau leveling osteotomy (TPLO) to address abnormal femorotibial kinematics caused by cranial cruciate ligament (CCL) rupture during walking in dogs.

STUDY DESIGN

Prospective, clinical.

ANIMALS

Sixteen dogs (20-40 kg) with unilateral complete CCL rupture.

METHODS

Lateral view fluoroscopy was performed during treadmill walking preoperatively and 6 months after TPLO. Digital three-dimensional (3D) models of the femora and tibiae were created from computed tomographic (CT) images. Gait cycles were analyzed by using a 3D-to-2D image registration process. Craniocaudal translation, internal/external rotation, and flexion/extension of the femorotibial joint were compared between preoperative and 6-month postoperative time points for the affected stifle and 6-month postoperative unaffected contralateral (control) stifles.

RESULTS

In the overall population, CCL rupture resulted in 10 ± 2.2 mm (mean ± SD) cranial tibial translation at midstance phase, which was converted to 2.1 ± 4.3 mm caudal tibial translation after TPLO. However, five of 16 TPLO-treated stifles had 4.1 ± 0.3 mm of cranial tibial subluxation during mid-to-late stance phase, whereas 10 of 16 TPLO-treated stifles had 4.3 ± 0.4 mm of caudal tibial subluxation throughout the gait cycle. Overall, postoperative axial rotational and flexion/extension patterns were not different from control, but stifles with caudal tibial subluxation had more external tibial rotation during mid-to-late stance phase compared with stifles with cranial tibial subluxation.

CONCLUSION

TPLO mitigated abnormal femorotibial kinematics but did not restore kinematics to control values in 15 of 16 dogs during walking.

CLINICAL SIGNIFICANCE

Tibial plateau leveling osteotomy reduces cranial tibial subluxation during walking, but persistent instability is common.

Percutaneous Plate Arthrodesis

Arthrodesis is an elective surgical procedure that aims at eliminating pain and dysfunction by promoting deliberate osseous fusion of the involved joint(s). Percutaneous plating can be used to perform carpal and tarsal arthrodeses in dogs and cats. After cartilage debridement is performed, the plate is introduced through separate plate insertion incisions made remote to the arthrodesis site and advanced along an epiperiosteal tunnel, and screws are inserted through the 3 existing skin incisions. The primary advantage of this technique is a decreased risk of soft-tissue complications, including postoperative swelling, ischemia, and wound dehiscence. Preliminary clinical results have been promising.

Minimally Invasive Plate Osteosynthesis: Radius and Ulna

Minimally invasive plate osteosynthesis (MIPO) is a biologically friendly approach to fracture reduction and stabilization that is applicable to many radius and ulna fractures in small animals. An appropriate knowledge of the anatomy of the antebrachium and careful preoperative planning are essential. This article describes the MIPO technique, which entails stabilization of the fractured radius with a bone plate and screws that are applied without performing an extensive open surgical approach. This technique results in good outcomes, including a rapid time to union and return of function.

Large Animal Models for Anterior Cruciate Ligament Research

Large animal (non-rodent mammal) models are commonly used in ACL research, but no species is currently considered the gold standard. Important considerations when selecting a large animal model include anatomical differences, the natural course of ACL pathology in that species, and biomechanical differences between humans and the chosen model. This article summarizes recent reports related to anatomy, pathology, and biomechanics of the ACL for large animal species (dog, goat, sheep, pig, and rabbit) commonly used in ACL research. Each species has unique features and benefits as well as potential drawbacks, which are highlighted in this review. This information may be useful in the selection process when designing future studies.

A biosensing soft robot: Autonomous parsing of chemical signals through integrated organic and inorganic interfaces

The integration of synthetic biology and soft robotics can fundamentally advance sensory, diagnostic, and therapeutic functionality of bioinspired machines. However, such integration is currently impeded by the lack of soft-matter architectures that interface synthetic cells with electronics and actuators for controlled stimulation and response during robotic operation. Here, we synthesized a soft gripper that uses engineered bacteria for detecting chemicals in the environment, a flexible light-emitting diode (LED) circuit for converting biological to electronic signals, and soft pneu-net actuators for converting the electronic signals to movement of the gripper. We show that the hybrid bio-LED-actuator module enabled the gripper to detect chemical signals by applying pressure and releasing the contents of a chemical-infused hydrogel. The biohybrid gripper used chemical sensing and feedback to make actionable decisions during a pick-and-place operation. This work opens previously unidentified avenues in soft materials, synthetic biology, and integrated interfacial robotic systems.

Antebrachiometacarpal arthrodesis in five dogs

CASE REPORTS

Five dogs (4 with severe carpal contracture, 1 with a chronically infected carpal joint) underwent antebrachiometacarpal arthrodesis. Excision of all carpal bones, except the accessory carpal bone, was done, either because of persistent infection or to allow the manus to be arthrodesed in a functional position. All five dogs developed varying degrees of soft tissue swelling of the surgical site following surgery. All five arthrodeses achieved complete osseous union within 4-67 weeks. The immediate postoperative distal radiometacarpal frontal plane angulation ranged from 1° to 19° (mean ± SD: 7 ± 8°). The immediate postoperative distal radiometacarpal sagittal plane angulation ranged from 6° to 26° (mean ± SD: 17 ± 9°). Plate coverage of the secured metacarpal bone(s) ranged from 75% to 87% (mean ± SD: 80 ± 4%). Infection necessitated plate removal in four dogs, 3-17 (mean ± SD: 8 ± 6) months following surgery and 0-15 (mean ± SD: 5 ± 7) weeks following radiographic documentation of complete osseous union.

CONCLUSION

Despite one dog having marked elbow incongruency and degenerative joint disease and one dog having an ipsilateral radial nerve deficit, all five dogs improved and had acceptable limb function at the time of the final evaluation, which ranged from 25 to 296 (mean ± SD: 99 ± 111) weeks following surgery.

Comparison of three imaging modalities used to evaluate bone healing after tibial tuberosity advancement in cranial cruciate ligament-deficient dogs and comparison of the effect of a gelatinous matrix and a demineralized bone matrix mix on bone healing - a pilot study

Background

Bone healing and assessment of the state of bone bridging is an important part of clinical orthopedics, whether for fracture healing or for follow up of osteotomy procedures. Tibial tuberosity advancement (TTA) is designed to restore stability in cruciate deficient stifle joints by advancing the tuberosity while creating an osteotomy gap. The current study aims to: 1) compare three different imaging modalities to assess bone healing: ultrasound, radiographs and computed tomography (CT) and, to 2) compare the effect of a gelatinous matrix (GM) versus a demineralized bone matrix mix (DBM mix) on bone healing and bridging of this osteotomy gap in 10 otherwise healthy client-owned dogs with cranial cruciate ligament insufficiency. Osseous union of the osteotomy gap was evaluated with ultrasound, radiographs and CT at one, two, and 3 months postoperatively. Dogs were randomly selected to receive GM or DBM mix to fill the osteotomy gap created during the TTA procedure. Bone healing was assessed subjectively on all modalities as well as scored on radiographs and measured using Hounsfield units (HUs) on CT. Time to heal based on ultrasound, radiographs and CT were statistically compared between groups with significance set at p < 0.05.

Results

All osteotomy gaps were bridged with bone within 3 months for all modalities. Bridging bone was diagnosed in 5.6 weeks, 10.4 weeks and 9.6 weeks based on ultrasound, radiographs, and CT, respectively, in dogs treated with DBM mix. In dogs treated with GM osseous union was diagnosed in a mean of 4.0 weeks, 9.6 weeks and 7.2 weeks based on ultrasound, radiographs and CT. Ultrasound diagnosed osseous union significantly faster than both CT and radiographs (p < 0.001). The dimensions of the newly formed bone differed between treatment groups with the central portion of the bone only providing a small bridge in GM cases. Although bridging of the osteotomy gap occurred earlier in the group that received GM, no significant statistical difference was found between the two groups.

Conclusions

Radiographs overestimate the time needed for osseous union of the osteotomy gap. All osteotomy sites healed radiographically within 3 months.

Femorotibial kinematics in dogs with cranial cruciate ligament insufficiency: a three-dimensional in-vivo fluoroscopic analysis during walking

BACKGROUND

Cranial cruciate ligament (CrCL) insufficiency is a degenerative condition that is a common cause of pelvic limb lameness and osteoarthritis in dogs. Surgical therapies developed to treat dogs with naturally occurring CrCL insufficiency aim to address the resultant instability, but the in-vivo alterations in stifle kinematics associated with CrCL insufficiency have not been accurately defined. The objective of this study was to quantify the 3-dimensional femorotibial joint kinematics of dogs with naturally occurring cranial cruciate ligament (CrCL) insufficiency during ambulation. Eighteen client-owned dogs (20-40 kg) with natural unilateral complete CrCL rupture were included. Computed tomographic scans were used to create digital 3-dimensional models of the femur and tibia bilaterally for each dog. Lateral fluoroscopic images were obtained during treadmill walking and 3 complete gait cycles were analyzed. Stifle flexion/extension angle, craniocaudal translation, and internal/external rotation were calculated throughout the gait cycle using a previously described 3D-to-2D image registration process. Results were compared between the pre-operative CrCL-deficient and 6-month post-operative contralateral stifles (control).

RESULTS

CrCL-deficient stifles were maintained in greater flexion throughout the gait cycle. Cranial tibial subluxation was evident in CrCL-deficient stifles at all time points throughout the gait cycle [9.7 mm at mid-stance (P < 0.0001); 2.1 mm at mid-swing (P < 0.0017)], and the magnitude of cranial tibial subluxation was greater at mid-stance phase than at mid-swing phase (P < 0.0001). Greater internal tibial rotation was present in CrCL-deficient stifles during stance phase (P < 0.0022) but no difference in axial rotation was evident during swing phase.

CONCLUSIONS

Naturally occurring CrCL rupture causes profound craniocaudal translational and axial rotational instability, which is most pronounced during the stance phase of gait. Surgical stabilization techniques should aim to resolve both craniocaudal subluxation and axial rotational instability.

Reconfigurable Analog Signal Processing by Living Cells

Living cells are known for their capacity for versatile signal processing, particularly the ability to respond differently to the same stimuli using biochemical networks that integrate environmental signals and reconfigure their dynamic responses. However, the complexity of natural biological networks confounds the discovery of fundamental mechanisms behind versatile signaling. Here, we study one specific aspect of reconfigurable signal processing in which a minimal biological network integrates two signals, using one to reconfigure the network's transfer function with respect to the other, producing an emergent switch between induction and repression. In contrast to known mechanisms, the new mechanism reconfigures transfer functions through genetic networks without extensive protein-protein interactions. These results provide a novel explanation for the versatility of genetic programs, and suggest a new mechanism of signal integration that may govern flexibility and plasticity of gene expression.

Long-term outcomes following plate stabilization to address spontaneous luxation of the long digital extensor tendon of origin in 2 dogs

Two dogs with spontaneous luxation of the long digital extensor tendon of origin were managed by performing a sulcoplasty and applying a plate bridging the extensor sulcus. Lameness resolved and neither dog had recurrence of lameness 59 and 15 months following surgery.

Biomechanical comparison of a 3.5-mm conical coupling plating system and a 3.5-mm locking compression plate applied as plate-rod constructs to an experimentally created fracture gap in femurs of canine cadavers

OBJECTIVE To compare stiffness and resistance to cyclic fatigue of two 3.5-mm locking system plate-rod constructs applied to an experimentally created fracture gap in femurs of canine cadavers. SAMPLE 20 femurs from cadavers of 10 mixed-breed adult dogs. PROCEDURES 1 femur from each cadaver was stabilized with a conical coupling plating system-rod construct, and the contralateral femur was stabilized with a locking compression plate (LCP)-rod construct. An intramedullary Steinmann pin was inserted in each femur. A 40-mm gap then was created; the gap was centered beneath the central portion of each plate. Cyclic axial loading with increasing loads was performed. Specimens that did not fail during cyclic loading were subjected to an acute load to failure. RESULTS During cyclic loading, significantly more LCP constructs failed (6/10), compared with the number of conical coupling plating system constructs that failed (1/10). Mode of failure of the constructs included fracture of the medial or caudal aspect of the cortex of the proximal segment with bending of the plate and pin, bending of the plate and pin without fracture, and screw pullout. Mean stiffness, yield load, and load to failure were not significantly different between the 2 methods of stabilization. CONCLUSIONS AND CLINICAL RELEVANCE Both constructs had similar biomechanical properties, but the conical coupling plating system was less likely to fail than was the LCP system when subjected to cyclic loading. These results should be interpreted with caution because testing was limited to a single loading mode.

Intraoperative use of a transarticular circular fixator construct to facilitate reduction and stabilisation of a proximal tibial physeal fracture in a dog

CASE REPORT

A 4-month-old female intact American Pit Bull Terrier was presented for right pelvic limb lameness 1 day after the dog had been hit by an all-terrain vehicle. Orthogonal radiographs of the right stifle revealed a Salter-Harris type IV fracture through the proximal tibial physis extending caudodistally through the proximal tibial metaphysis. The distal tibia was markedly displaced cranially, laterally and proximally, resulting in complete overriding of the fracture segments. An open approach was made in order to facilitate direct reduction, but the fracture could not be sufficiently distracted and the epiphyseal segment remained fixed caudal to the remainder of the tibia. Concerns regarding possible iatrogenic trauma to the epiphysis prompted the use of a transarticular circular fixator construct to distract the fracture segments to facilitate reduction. Distraction that facilitated reduction was performed using three TrueLok Rapid Quick Adjust Struts that were positioned between the two ring components. The struts also allowed for multiplanar adjustment of alignment, which allowed the fracture to be maintained in anatomic reduction as divergent interfragmentary Kirschner wires were placed. Radiographic union was confirmed 19 days after surgery.

CONCLUSION/CLINICAL SIGNIFICANCE

Transient intraoperative application of a circular construct incorporating the TrueLok components facilitated accurate fracture reduction without inflicting further iatrogenic trauma to the epiphysis, after traditional direct reduction techniques proved ineffective, and afforded a successful clinical outcome in the dog reported here.

Retrospective evaluation of the efficacy of isolating bacteria from synovial fluid in dogs with suspected septic arthritis

OBJECTIVE

To evaluate the efficacy of synovial fluid culture in obtaining the causative organism from dogs with suspected septic arthritis.

METHODS

In this retrospective evaluation, synovial fluid cytology and microbiology submissions from dogs with suspected septic arthritis from March 2007 to August 2011 were reviewed. Synovial fluid cytology consistent with joint sepsis was identified. Cultures of synovial fluid from dogs with clinical histories and abnormalities consistent with septic arthritis were used to evaluate the efficacy of bacterial isolation.

RESULTS

In total, 36 dogs met the inclusion criteria. Initial aerobic cultures of joint fluid yielded bacterial growth in 44% of these dogs. All anaerobic cultures were negative. In 19% of the dogs with positive cultures, antibiotics had been administered prior to arthrocentesis compared with 10% of dogs with negative cultures. There was no association between culture efficacy and the administration of antimicrobial treatment prior to synovial fluid culture or recent surgery involving the affected joint (P=0.637 and P=0.106, respectively).

CONCLUSION

Culture of synovial fluid from dogs with suspected septic arthritis has a low yield, necessitating a more effective means of identifying bacteria from suspected septic joints in dogs.

Comparison of synovial fluid culture and 16S rRNA PCR in dogs with suspected septic arthritis

OBJECTIVE

To prospectively compare the sensitivity and specificity of 16S rRNA PCR with culture for identifying the causative organism in synovial fluid obtained from dogs with suspected septic arthritis.

METHODS

Synovial fluid cytology, PCR analysis and aerobic, anaerobic and Mycoplasma culture of samples from the affected joints of 18 dogs presenting with suspected septic arthritis were performed. Synovial fluid samples from the corresponding contralateral joints of 7 dogs were also analysed as negative controls.

RESULTS

There was no significant difference between the sensitivity of bacterial detection via culture (63.2%) versus PCR (73.7%) of synovial fluid (P=0.728) or between culture and combined PCR and culture (89.5%) of synovial fluid (P=0.124). The specificity of PCR (42.9%) was significantly lower than culture specificity (100%) (P=0.07).

CONCLUSION

Although 16S PCR may hold potential as an ancillary diagnostic test for identifying the causative organism in dogs with septic arthritis, our study failed to demonstrate improved accuracy compared with traditional synovial fluid culture.

Mechanics of Supplemental Drop Wire and Half-Pin Fixation Elements in Single Ring Circular External Fixator Constructs

OBJECTIVE

Evaluate the effects of supplemental fixation elements on the mechanical properties of a single ring circular fixator construct.

STUDY DESIGN

In vitro mechanical testing.

SAMPLE POPULATION

Five construct configurations (six replicates of each configuration) were used to stabilize a 1.6 cm diameter Delrin rod bone model.

METHODS

Constructs were assembled using 66 mm complete rings, 1.6 mm olive wires, and 3.2 mm diameter half-pins. Construct configurations tested were a base single ring construct, constructs with 1 supplemental drop wire or constructs with 1, 2, or 3 supplemental half-pins. Constructs were loaded in axial compression, caudocranial and mediolateral bending, and torsion. Strain was measured in individual fixation elements during axial loading.

RESULTS

A supplemental drop wire or half-pin significantly increased bending and torsional stiffness. The supplemental half-pin increased caudocranial stiffness significantly more than placing a drop wire. Placing a 2nd or 3rd pin afforded significantly greater increases in construct stiffness in all modes of loading, with 3 half-pin constructs having significantly greater axial and caudocranial stiffness than 2 half-pin constructs. Placing a single supplemental pin induced cantilever bending resulting in angular displacement of the Delrin rod during axial loading and high strain in both the fixation wire secured distal to the ring and the pin. Supplemental half-pins incrementally reduced strain in all fixation elements and resulted in linear displacement of the Delrin rod during axial loading.

CONCLUSION

If using supplemental half-pins as fixation elements, insertion of 2 or 3 pins is preferred over a single pin.

In-vivo three-dimensional knee kinematics during daily activities in dogs

The canine knee is morphologically similar to the human knee and thus dogs have been used in experimental models to study human knee pathology. To date, there is limited data of normal canine 3D knee kinematics during daily activities. The objective of this study was to characterize 3D in-vivo femorotibial kinematics in normal dogs during commonly performed daily activities. Using single-plane fluoroscopy, six normal dogs were imaged performing walk, trot, sit, and stair ascent activities. CT-generated bone models were used for kinematic measurement using a 3D-to-2D model registration technique. Increasing knee flexion angle was typically associated with increasing tibial internal rotation, abduction and anterior translation during all four activities. The precise relationship between flexion angle and these movements varied both within and between activities. Significant differences in axial rotation and coronal angulation were found at the same flexion angle during different phases of the walk and trot. This was also found with anterior tibial translation during the trot only. Normal canine knees accommodate motion in all planes; precise kinematics within this envelope of motion are activity dependent. This data establishes the characteristics of normal 3D femorotibial joint kinematics in dogs that can be used as a comparison for future studies.

Clinical outcomes associated with the initial use of the Canine Unicompartmental Elbow (CUE) Arthroplasty System(®)

We evaluated mid- to long-term outcomes with respect to function and complications in dogs undergoing canine unicompartmental elbow (CUE) arthroplasty for treatment of medial compartment disease of the elbow. This prospective multicenter case series is the first group of clinical cases to receive CUE arthroplasty. Cases (each elbow that underwent CUE performed by a participating surgeon) were enrolled into an electronic database and prospectively followed to determine and record all associated complications, as well as functional outcomes. There were 103 cases from 18 surgeons. Final follow-up time ranged from 6 to 47 mo with a mean and median of 10 mo. Canine unicompartmental elbow was associated with 1 catastrophic (1%), 11 major (10.7%), and 28 minor (27.2%) complications. Outcomes following CUE were reported as full function in 49 cases (47.6%), acceptable function in 45 cases (43.7%), and unacceptable function in 9 cases (8.7%). We conclude that CUE arthroplasty is an appropriate consideration for treatment of medial compartment disease of the elbow in dogs.