Comparison of three-dimensional printed patient-specific guides versus freehand approach for radial osteotomies in normal dogs: Ex vivo model.

OBJECTIVE: To compare the accuracy of three-dimensional (3D) printed patient-specific guide (PSG) with a freehand (FH) approach for radial osteotomies in ex vivo normal dogs. STUDY DESIGN: Experimental study. ANIMALS: Twenty four ex vivo thoracic limb pairs from normal beagle dogs. METHODS: Computed tomography (CT) images were collected preoperatively and postoperatively. Three osteotomies tested (n = 8/group) were: (1) uniplanar 30° frontal plane wedge ostectomy, (2) oblique plane (30° frontal, 15° sagittal) wedge ostectomy, and (3) single oblique plane osteotomy (SOO, 30° frontal, 15° sagittal, and 30° external). Limb pairs were randomized to a 3D PSG or FH approach. The resultant osteotomies were compared with virtual target osteotomies by surface shape-matching postoperative to the preoperative radii. RESULTS: The mean ± standard deviation osteotomy angle deviation for all 3D PSG osteotomies (2.8 ± 2.8°, range 0.11-14.1°) was less than for the FH osteotomies (6.4 ± 6.0°, range 0.03-29.7°). No differences were found for osteotomy location in any group. In total, 84% of 3D PSG osteotomies were within 5° deviance from the target compared to 50% of freehand osteotomies. CONCLUSION: Three-dimensional PSG improved FH accuracy of osteotomy angle in select planes and the most complex osteotomy orientation in a normal ex vivo radial model. CLINICAL SIGNIFICANCE: Three-dimensional PSGs provided more consistent accuracy, which was most notable in complex radial osteotomies. Future work is needed to investigate guided osteotomies in dogs with antebrachial bone deformities.

Clinical outcomes of 20 brachycephalic dogs with thoracolumbar spinal deformities causing neurological signs treated with spinal stabilization using 3D-printed patient-specific drill guides.

OBJECTIVE: To describe the clinical outcomes for pugs and French bulldogs with congenital vertebral malformations, undergoing thoracolumbar spinal stabilization surgery using 3D-printed patient-specific drill guides. To evaluate the accuracy of pedicle screw placement in this group of dogs. STUDY DESIGN: Retrospective descriptive study. ANIMALS: Twenty dogs (12 pugs and eight French bulldogs). METHODS: Medical records searched between August 2018 and March 2021 for pugs and French bulldogs diagnosed with congenital vertebral abnormalities via magnetic resonance imaging (MRI) scan and computed tomography (CT) scan causing T3-L3 myelopathy signs that underwent spinal stabilization surgery using 3D-printed patient-specific drill guides followed by a postoperative CT scan. The short-term outcome was based on the neurological grade (modified Frankel score-MFS) on the day after surgery, day of discharge, and at the follow-up examination at 4 to 6 weeks after surgery. The mid-term outcome was obtained via an online questionnaire (or direct examination in one case). RESULTS: Twenty dogs met the inclusion criteria (19/20 grade 2 MFS, 1/20 grade 4 MFS). No complications were reported in the immediate postoperative period and optimal pedicle screw placement was obtained in 169/201 of screws. Twenty-four hours after surgery 16/20 dogs displayed an unchanged neurological grade. Short-term outcomes revealed a static (17/20) or improved (2/20) neurological grade. Ten owners participated in the online questionnaire. All patients were reported to be ambulatory; however, 7/10 dogs displayed abnormal gait. Neurological signs had remained static (6/10) or improved (3/10) in comparison with the dogs' preoperative status at a median of 883.5 days from the surgery. CONCLUSION: Dogs in this study had a favorable short-term outcome and mid-term outcome evaluation revealed a static/improved neurological status. CLINICAL SIGNIFICANCE: Thoracolumbar spinal stabilization surgery using 3D-printed patient-specific drill guides showed a favorable outcome in brachycephalic breeds affected by vertebral deformities.

3D-printed, patient-specific cutting guides improve femoral and tibial cut alignment in canine total knee replacement.

OBJECTIVES: The purpose of this cadaveric study was to determine whether patient-specific guides (PSGs) improve the accuracy of tibial and femoral cut alignment in canine total knee replacement (TKR), as compared with generic cutting guides. STUDY DESIGN: Original research. ANIMALS: Sixteen pelvic limbs from skeletally mature medium- to large-breed canine cadavers. METHODS: Specimens were randomly allocated to one of two groups (PSG or Generic; N = 8/group). In the Generic group, femoral and tibial ostectomies were made using the standard canine TKR femoral cutting blocks and tibial alignment guide. In the PSG group, the cuts were made using a series of custom 3D-printed cutting guides. "Planned" and "actual" tibial and femoral cut alignments were compared in the frontal and sagittal planes, and errors were calculated by subtracting actual from planned values. RESULTS: Use of 3D-printed PSGs improved tibial cut alignment in the frontal plane but not the sagittal plane. PSGs also improved the alignment of the cranial and distal femoral ostectomies but did not impact varus-valgus alignment. CONCLUSIONS: These findings support the use of PSGs for TKR in dogs. Clinical trials are now needed to determine whether the benefits of PSGs translate into measurable improvements in joint function and implant longevity. CLINICAL SIGNIFICANCE: PSGs have the potential to improve femoral and tibial component alignment in canine TKR.

Lumbosacral intervertebral disk extrusions in 13 dogs.

OBJECTIVE: To describe the clinical presentation, magnetic resonance imaging (MRI) findings, and outcome of dogs treated surgically for lumbosacral intervertebral disk extrusion (IVDE). STUDY DESIGN: Retrospective study. ANIMALS: Thirteen dogs. METHODS: Records and MRI studies of dogs with intraoperatively confirmed lumbosacral IVDE were reviewed. MRI features of thoracolumbar IVDE were applied to all cases. Postoperative outcome was subjectively assessed as excellent, good, or poor. RESULTS: All dogs had an acute or subacute onset of lumbosacral pain and nerve root signature. Seven dogs had neurological deficits. MRI revealed lateralized herniated disk material and partial to complete disk degeneration in all cases; the extradural material extended cranial and/or caudally from the disk space in 10 cases. All dogs underwent L7-S1 dorsal laminectomy and removal of extruded disk material. In six dogs, surgery was complicated by inflammatory changes, including one case of epidural steatitis. On reexamination 4-6 weeks postsurgery, outcome was judged as excellent in 11 dogs and poor in the remaining 2 due to contralateral nerve root signature in one case and nonambulatory paraparesis and urinary incontinence in the case with steatitis. CONCLUSION: Lumbosacral IVDE in dogs was characterized by acute/subacute onset of lumbosacral pain and nerve root signature and lateralized and often dispersed extradural material over a degenerated L7-S1 intervertebral disk on MRI. Early decompressive dorsal laminectomy generally resulted in excellent clinical outcome. CLINICAL SIGNIFICANCE: Observation of these clinical and imaging features in dogs should prompt clinical suspicion of lumbosacral IVDE.

Accuracy of placement of pedicle screws in the thoracolumbar spine of dogs with spinal deformities with three-dimensionally printed patient-specific drill guides.

OBJECTIVE: To determine the accuracy of pedicle screw placement in the thoracic spine of dogs with spinal deformities with three-dimensionally (3D) printed patient-specific drill guides. STUDY DESIGN: Retrospective study. SAMPLE POPULATION: Six dogs in which sixty pedicle screws were placed in the thoracolumbar spine. METHODS: Medical records were searched between June 2017 and June 2018 for dogs with clinical signs associated with a thoracolumbar vertebral malformation. Inclusion criteria included MRI and computed tomography (CT) data that were used to create 3D printed patient-specific drill guides. All dogs were stabilized dorsally with guided bicortical pedicle screws and polymethylmethacrylate. Accuracy of screw placement was assessed by immediately postoperative CT according to a modified Zdichavsky classification. RESULTS: Five pugs and one French bulldog met the inclusion criteria. Sixty bicortical pedicle screws were placed; 96.7% were graded as I (optimal placement), and 3.3% were classified as IIa (partial penetration of the medial pedicle wall) according to a modified Zdichavsky classification. CONCLUSION: Three-dimensionally printed patient-specific drill guides allowed safe and accurate placement of pedicle screws in the thoracolumbar spine in dogs with vertebral malformation. CLINICAL SIGNIFICANCE: Three-dimensionally printed patient-specific drill guides are a safe and effective method of placing pedicle screws in dogs with thoracolumbar vertebral malformations.

Accuracy of three-dimensional printed patient-specific drill guides for treatment of canine humeral intracondylar fissure.

OBJECTIVE: To determine the accuracy of three-dimensional printed patient-specific drill guides (3D-PDG) as treatment of humeral intracondylar fissures (HIF) in dogs. STUDY DESIGN: Retrospective consecutive case series. ANIMALS: Client-owned dogs with HIF treated with a 5-mm transcondylar screw (TCS) placed from medial to lateral with a 3D-PDG. METHODS: The proposed TCS entry point and trajectory were planned using computed tomography (CT) data and computer-aided design software (CAD), and a 3D-PDG was produced. During surgery the 3D-PDG was used to drill the pilot hole from medial to lateral; the guide was then removed, the pilot hole was overdrilled, and a 5-mm TCS was placed. Postoperative CT data were imported into CAD software, and the entry points, exit points, and trajectories were compared between the planned and actual screw locations. RESULTS: Sixteen elbows from 11 dogs were included. Mean (SD) entry point translation was 1.3 mm (0.64), with all screws entering cranial to the proposed location. Mean maximum screw angulation was 5.2° (2.10°), with most screws directed caudodistal to the desired trajectory. Mean (SD) exit point translation was 1.8 mm (0.89) from the planned location. There was no intra-articular screw placement. CONCLUSION: Use of a 3D-PDG permitted accurate placement of a mediolateral 5-mm locking TCS within the humeral condyle. CLINICAL SIGNIFICANCE: Three-dimensional printed patient-specific drill guides should be considered as accurate and consistent for placing TCS for treatment of HIF in dogs.

Long-term outcomes after pantarsal arthrodesis with medial plate fixation without external coaptation in 30 dogs.

OBJECTIVE: To report long-term outcomes of dogs treated with pantarsal arthrodesis (PTA) with medial plate fixation without external coaptation. STUDY DESIGN: Retrospective case series. ANIMALS: Client-owned dogs (n = 30). METHODS: Medical records of dogs that had undergone a PTA with a medially applied plate without adjunctive rigid external coaptation were reviewed. Data collected included signalment, complications, and assessment of function at last physical examination. Follow-up information was obtained by phone conversations with owners. Complications were classified as minor, major II, major I, and catastrophic. RESULTS: Thirty-six PTA were performed in 30 dogs. Recorded complications included eight (22.2%) minor complications, 11 (30.6%) major II complications and 11 (30.6%) major I complications. One (2.8%) dog required amputation because of catastrophic complication. Owners provided follow-up for 26 dogs at a median duration of 1215 days (range, 325-3495) after surgery. The outcome was reported as full function in 12 dogs and acceptable function in 14 dogs, with no owners reporting unacceptable function. The owner of the dog in which amputation was required was not contacted. Incorrect contact details prevented owner follow-up in the other three dogs, but all had acceptable function at last veterinary follow up. CONCLUSION: Dogs treated with PTA by medially applied plate had a high incidence of complications requiring surgical or medical management, although full or acceptable function was achieved in 29 of 30 dogs. CLINICAL SIGNIFICANCE: Pantarsal arthrodesis offers a predictably good medium to long-term outcome in spite of a high risk of complications.

Accuracy of patient-specific three-dimensional-printed osteotomy and reduction guides for distal femoral osteotomy in dogs with medial patella luxation.

OBJECTIVE: To compare precorrectional and postcorrectional femoral alignment following distal femoral osteotomy using patient-specific 3-dimensional (3D)-printed osteotomy and reduction guides in vivo and ex vivo. STUDY DESIGN: Prospective study. SAMPLE POPULATION: Ten client-owned dogs and matching 3D-printed plastic bone models. METHODS: Distal femoral osteotomy was performed via a standard approach using osteotomy and reduction guides developed with computer-aided design software prior to 3D-printing. Femoral osteotomy and reduction was also performed on 3D-printed models of each femur with identical reprinted guides. Femoral varus angle (FVA) and femoral torsion angle (FTA) were measured on postoperative computed tomographic images by 3 observers. RESULTS: In vivo, the mean difference between target and achieved postoperative was 2.29° (±2.29°, P = .0076) for the FVA, and 1.67° (±2.08°, P = .300) for the FTA. Ex vivo, the mean difference between target and achieved postoperative was 0.29° (±1.50°, P = .813) for the FVA, and -2.33° (±3.21°, P = .336) for the FTA. Intraobserver intraclass correlation coefficients (ICC; 0.736-0.998) and interobserver ICC (0.829 to 0.996) were consistent with an excellent agreement. CONCLUSION: Use of 3D-printed osteotomy and reduction guides allowed accurate correction of FTA in vivo and both FVA and FTA ex vivo. CLINICAL SIGNIFICANCE: Use of 3D-printed osteotomy and reduction guides may improve the accuracy of correction of femoral alignment but warrant further evaluation of surgical time, perioperative complications, and patient outcomes compared with conventional techniques.

A 3-dimensional-printed patient-specific guide system for minimally invasive plate osteosynthesis of a comminuted mid-diaphyseal humeral fracture in a cat.

OBJECTIVE: To report the use of a 3-dimensional (3D)-printed patient-specific reduction guide system to facilitate minimally invasive plate osteosynthesis (MIPO) of a humeral fracture in a cat. STUDY DESIGN: Case report. ANIMALS: A 9-year-old male neutered domestic short hair cat weighing 4.4 kg. METHODS: A 9-year-old male domestic short hair cat was presented with a comminuted, mid-diaphyseal left humeral fracture. Computed tomographic data were processed to yield 3D mesh representations of both humeri and subsequently manipulated in computer-aided design software. The mirrored, intact humerus was used as a template for appropriate spatial orientation of the major proximal and distal fracture fragments. Patient-specific Ellis pin orientation guides and a reduction guide were designed and 3D printed. The guide system was used intraoperatively to align the major fracture fragments before application of locking internal fixation via standard MIPO surgical portals. RESULTS: Internal fixation of the fracture resulted in appropriate bone alignment. Recovery was uncomplicated, with early return to normal limb function and radiographic evidence of advanced fracture healing after 4 months. CONCLUSION: A 3D-printed patient-specific reduction guide system facilitated accurate alignment of a comminuted humeral fracture during MIPO without intraoperative imaging.

Accuracy of a patient-specific 3D printed drill guide for placement of cervical transpedicular screws.

OBJECTIVE: To develop a patient-specific 3-dimensional (3D) printed drill guide for placement of cervical transpedicular screws and to assess its accuracy. STUDY DESIGN: Prospective case-series. SAMPLE POPULATION: Thirty-two cervical pedicle screws (CPS) placed in 3 large breed dogs. METHODS: Computed tomographic (CT) data of the cervical vertebrae were exported to a medical image processing software and 3D virtual vertebral models were created for each vertebra. These models were processed in a computer aided design (CAD) software to determine the optimal trajectory and size of the CPS. Virtual drill guides were created for each patient, 3D-printed, and used intraoperatively. Locking titanium screw heads were bonded with polymethylmethacrylate cement to stabilize affected vertebral segments. Postoperative CT was used to assess the radiological accuracy of CPS placement in each dog. For each screw, CAD files were analyzed to determine a screw-diameter-to-pedicle-width-ratio (SDPWR) at the narrowest point of the pedicle. RESULTS: A total of 32 CPS were placed, measuring 3.5 mm (n = 20), 2.7 mm (n = 11), and 2.4 mm (n = 1) in diameter. The majority (29/32) of these screws were placed without evidence of vertebral canal breach (grade 0), whereas a vertebral canal breach <2 mm (grade 1) was detected in 3/32 screws. This outcome was achieved despite a mean SDPWR of 0.75 (range 0.58-0.93). CONCLUSION: The use of a 3D-printed patient-specific drill guide permitted accurate placement of 32 bicortical pedicle screws in the caudal cervical vertebrae of 3 dogs. This technique may improve clinical outcome through superior biomechanical properties of screws, reduced surgical time, and reduced morbidity. These results warrant evaluation of patient outcome in a larger population.

Highly Comminuted, Articular Fractures of the Distal Antebrachium Managed by Pancarpal Arthrodesis in 8 Dogs.

OBJECTIVE: To describe the surgical management by pancarpal arthrodesis for highly comminuted articular fractures of the distal antebrachium in 8 dogs. STUDY DESIGN: Retrospective clinical case series. ANIMALS: Eight dogs. METHODS: Medical records (2001-2014) of dogs with antebrachial fractures were reviewed and dogs with highly comminuted distal antebrachial fractures were identified. The nature of the injury, surgical management by pancarpal arthrodesis, outcome, and complications were recorded. RESULTS: Nine fractures occurred in 8 dogs. Seven dogs were ex-racing greyhounds (8 fractures) and of these, 6/7 dogs had fractures of the right thoracic limb. Compared with the hospital population of dogs with antebrachial fractures, greyhounds were over-represented for the antebrachial injury (odds ratio 117, 95% confidence interval 13-1022). Five dogs sustained injury during exertional exercise or with relatively minor trauma. Submitted bone samples (n = 4) showed no evidence of underlying neoplasia. Mean followup was 15.5 months with 11 complications recorded in 7/8 dogs, including 1 catastrophic, 5 major, and 5 minor complications. Pancarpal arthrodesis allowed a full functional outcome in 3 dogs and an acceptable outcome in 3. CONCLUSION: Comminuted articular fractures of the distal radius and ulna are complex injuries and have a similar presentation to pathologic fractures. Surgical management by pancarpal arthrodesis is associated with a high risk of complication and a guarded prognosis for a full functional outcome.

Accuracy of correction of a hexapod frame, patient-specific osteotomy and reduction guides, and hinged circular external fixation in a 3D-printed canine antebrachial deformity model.

Objectives: This study aimed to objectively define whether human hexapod fixation (Maxframe), with or without the use of 3D-printed positioning guides, can correct a canine antebrachial deformity with greater accuracy than the clinically established techniques of 3D patient-specific osteotomy and reduction guides (3D-PSORG) or hinged circular external skeletal fixation (CESF). Methods: CT of a canine antebrachium was manipulated to induce distal radial deformity of the valgus, external torsion, and procurvatum, each of magnitude 20o. Five experiments were performed to correct the deformity via a distal radial and ulna opening osteotomy using: (1) A 3D-PSORG with the application of a locking plate, (2) hinged CESF, (3) Maxframe standard protocol, (4) Maxframe applied with patient-specific positioning guides (PSPGs), and (5) Maxframe with frame adjustment calculated from post-application CT. Following correction, all constructs were optically scanned, and objective measurement of the correction achieved was performed. Results: No construct returned the distal bone segment to its preoperative position in all planes. Translational malalignment in the sagittal plane had the highest magnitude of error for all constructs, with the Maxframe standard protocol showing the greatest error. Maxframe (PSPGs) showed the minimum error of all constructs in the frontal and sagittal planes. Clinical significance: In this 3D-printed model of antebrachial deformity correction, the hexapod frame with the use of PSPGs achieved better accuracy than 3D-PSORG and hinged CESF and may be a technique of future interest and development in the management of canine antebrachial limb deformity.

Precision of a novel computed tomographic method for quantification of femoral varus in dogs and an assessment of the effect of femoral malpositioning.

OBJECTIVE: To assess the precision of a novel protocol for determination of femoral varus angle (FVA) using computed tomography (CT) in dogs, and to quantify the effect of femoral rotational and sagittal plane malpositioning on measured FVA. STUDY DESIGN: Cross-sectional study. SAMPLE POPULATION: Femora (n = 66) from dogs that had pelvic limb CT examination for patellar instability (26) or other reasons (10). METHODS: Three observers measured FVA of each of 66 femora on three separate occasions. Standardized orientation of a volume rendered image was achieved by superimposition of the caudal and distal aspects of the femoral condyles on a lateral projection, definition of a sagittal plane axis, and finally rotation through 90° to yield a cranial projection. Intra- and inter-observer variability were estimated using the intra-class correlation coefficient. The effect of variation in rotational and sagittal plane orientation on measured FVA was subsequently quantified using 6 femora with FVAs between -0.4° and 19°. RESULTS: Intra-class correlation coefficients for the 3 observers, indicating intra-observer variation, were 0.982, 0.937, and 0.974. The intra-class correlation coefficient of the means of the results from each observer, indicating inter-observer variation, was 0.976. Consistent linear variations in measured FVA occurred as a result of rotational malpositioning in all 6 tested femora, and as a result of sagittal plane malpositioning in femora with FVAs ≥ 7.9°. CONCLUSIONS: The reported protocol for the measurement of FVA in dogs is repeatable and reproducible. Small variations in femoral orientation, as might be expected with conventional radiography, lead to clinically significant alterations in measured FVA.

Comparison of complication rates and clinical outcome between tibial plateau leveling osteotomy and a modified cranial closing wedge osteotomy for treatment of cranial cruciate ligament disease in dogs.

OBJECTIVE: To report complication rates and clinical outcomes after tibial plateau leveling osteotomy (TPLO) and a modified cranial closing wedge osteotomy (mCCWO) for treatment of cranial cruciate ligament disease in dogs. STUDY DESIGN: Prospective cohort study. ANIMALS: Dogs weighing 20-60 kg with unilateral cranial cruciate ligament disease treated by either TPLO (n = 97) or mCCWO (n = 74). METHODS: Clinical and radiographic assessments including lameness score, morphometric measurements and tibial plateau angle (TPA) were made before surgery and 8 weeks after either TPLO or mCCWO. Long-term outcome assessment by owner questionnaire or interview was undertaken at ≥6 months postoperatively. RESULTS: Significant differences in lameness scores between groups were not identified at short- or long-term follow-up. Major complication and reoperation rates did not differ significantly between groups (TPLO 7.2% and 6.1%; mCCWO 9.5% and 5.4%). Median postoperative TPA did not differ significantly between groups (TPLO group 5.5°; mCCWO group 6.5°). At >6 months owner assessed lameness, disability, quality of life and satisfaction were not different between groups and were good in 90-97% of dogs. CONCLUSIONS: In dogs weighing 20-60 kg, TPLO and mCCWO are associated with similar complication rates and clinical outcomes when performed by surgeons experienced with the surgical techniques.

Thoracolumbar Spinal Stabilization with Three Dimensional-Printed Drill Guides and Pre-Contoured Polyaxial Bone Plates.

OBJECTIVE: The aim of this study was to report new preoperative and intraoperative techniques performed for canine thoracic or lumbar spine kyphosis stabilization using three-dimensional-printed patient-specific drill guides, polyaxial titanium bone plates and drill stops, and to determine the accuracy of screw placement using these techniques. STUDY DESIGN: Retrospective study, five client-owned dogs. RESULTS: Three-dimensional-printed patient-specific drill guides and drill stops allowed safe drilling and screw placement in all of the cases, with (i) 84% of the screws graded as I (ideal placement) and 16% as IIa, IIIa or IIIb according to the modified Zdichavsky classification (partial penetration of medial pedicle wall, partial penetration of lateral pedicle wall and full penetration of lateral pedicle wall respectively), (ii) mean mediolateral deviation of ± 4.06 degrees (standard deviation: 8.21 degrees) compared to planned trajectories and (iii) variation in screw depth of ± 2.29mm (standard deviation: 3.07mm) compared to planned depth. CONCLUSION: We believe that the techniques presented here for thoracic spinal stabilization in dogs show promise; they allowed safe placement of screws along planned trajectories and depth; they also removed the need to use polymethylmethacrylate, while the use of titanium offers the possibility to repeat magnetic resonance imaging in these cases with chronic spinal conditions.

Radiographic Comparison of Virtual Surgical Corrective Options for Excessive Tibial Plateau Angle in the Dog.

OBJECTIVE: The main aim of this study is to compare the impact of six proximal tibial osteotomies on the geometry and alignment of tibias with and without excessive tibial plateau angle (TPA). STUDY DESIGN: Mediolateral radiographs of 30 canine tibias were divided into three groups (n = 10/group): moderate TPA (≤34 degrees), severe TPA (34.1-44 degrees) and extreme TPA (>44 degrees). Six proximal tibial osteotomies were simulated on each tibia using orthopaedic planning software: cranial closing wedge ostectomy (CCWO), modified CCWO (mCCWO), isosceles CCWO (iCCWO), neutral isosceles CCWO (niCCWO), tibial plateau levelling osteotomy with CCWO (TPLO/CCWO) and coplanar centre of rotation of angulation-based levelling osteotomy (coCBLO). All tibias were reduced to a standard target TPA. Pre- and postoperative measurements were obtained for each virtual correction. Compared outcome measures included tibial long axis shift (TLAS), cranial tibial tuberosity shift (cTTS), distal tibial tuberosity shift (dTTS), tibial shortening and osteotomy overlap. RESULTS: Across all TPA groups, TPLO/CCWO had the lowest mean TLAS (1.4 mm) and dTTS (6.8 mm); coCBLO had the largest TLAS (6.5 mm) and cTTS (13.1 mm); CCWO had the largest dTTS (29.5 mm). CCWO had the largest degree of tibial shortening of 6.5 mm, while mCCWO, niCCWO and coCBLO resulted in minimal tibial lengthening (1.8-3.0 mm). These trends were generally conserved across different TPA groups. All findings had a p-value less than 0.05. CONCLUSION: mCCWO balances moderate alterations to tibial geometry while preserving osteotomy overlap. The TPLO/CCWO has the least effect on tibial morphology alteration, whereas the coCBLO results in the largest alteration.

A 3-Dimensional Printed Patient-Specific Surgical Guide to Facilitate Transsphenoidal Hypophysectomy in Dogs.

Objective: Hypophysectomy in dogs is a difficult surgery that requires specific learning and training. We aimed to evaluate the accuracy of a 3-dimensional printed patient-specific surgical guide to facilitate choosing the entry point in the basisphenoid bone before approaching the sella turcica during transsphenoidal hypophysectomy in dogs. Methods: Two canine cadavers and 8 dogs undergoing transsphenoidal hypophysectomy for Cushing's disease treatment, involving design and fabrication of a 3-dimensional printed guide. The ideal entry point in the basisphenoid bone outer cortical layer was determined in each dog pre-operatively; its anatomical location was described with a set of measurements then compared to post-operative computed tomography measures describing the location of the outer cortical window created in the basisphenoid bone. Results: Several guide designs were proposed, and a consensus reached based on surgeons' experience performing hypophysectomy. The device chosen could be applied to the size and shape of skulls encountered in this case series. The pre-planned measurements were comparable to post-operative measurement (there was also no statistical difference), with median of differences <0.1 mm, which we judged as clinically acceptable. Clinical Significance: Hypophysectomy in dogs is a challenging procedure that has a learning curve and needs to be performed by specialist neurosurgeons. We propose that a low-profile 3-dimensional printed surgical guide can aid the specialist neurosurgeon to locate the burring site of the outer cortical layer of the basisphenoid bone at a pre-defined location and with good accuracy. It does not alleviate the need to understand the anatomy of the region and to know how to create a slot within the basisphenoid bone, which remains essential to enter the sella turcica. This device could help specialist veterinary neurosurgeons wishing to be trained to perform hypophysectomy.

Hybrid cemented/cementless total hip replacement in dogs: seventy-eight consecutive joint replacements.

OBJECTIVE: To evaluate the use of hybrid total hip replacement (THR), using a cementless acetabular component and a cemented femoral component. STUDY DESIGN: Prospective case series. SAMPLE POPULATION: Client-owned dogs (n = 71). MATERIALS AND METHODS: Consecutive clinical cases that had hybrid THR were studied. Radiographic features, pain scores, and lameness scores were recorded pre- and postoperatively. Longer term outcome was assessed by owner questionnaire. RESULTS: Hybrid THRs (n = 78) were performed in 71 dogs. Four cases (5%) had major postoperative complications; 3 were resolved after revision surgery, and 1 owner requested an explantation. No other major complications were identified on follow-up radiographs (67 THR) at 12 weeks. On clinical follow up (77 THR) at 4 weeks, lameness had improved in 68, was unchanged in 8, and was worse in 1. Pain had decreased in 72, was unchanged in 4, and was worse in 1. At 12 weeks (69 THR) compared with preoperative status, lameness had improved in 67 and was unchanged in 2. Pain had improved in 68 and was unchanged in 1. Longer term follow-up (mean, 16 months) was available for all hips. No further complications were reported. Owner satisfaction was good for 76 THRs and reasonable for 2. CONCLUSIONS: Hybrid THR can be performed successfully with a low complication rate and represents an alternative to either entirely cemented or cementless implantation.

Accuracy of Placement of Pedicle Screws in the Lumbosacral Region of Dogs Using 3D-Printed Patient-Specific Drill Guides.

OBJECTIVE: The aim of this study was to report the accuracy of pedicle screw placement using three-dimensional (3D)-printed, patient-specific drill guides in the lumbosacral region of dogs. STUDY DESIGN: This was a retrospective study. Thirty-two pedicle screws were placed in five dogs. Medical records were reviewed between November 2015 and November 2018 for dogs showing clinical signs associated with cauda equina syndrome. Inclusion criteria included preoperative magnetic resonance imaging, pre- and postoperative computed tomography (CT) and dorsal stabilization, with pedicle screws placed using 3D-printed, patient-specific drill guides and polymethylmethacrylate. Screw placement was evaluated for medial or lateral breaching on postoperative CT. RESULTS: Five dogs met the inclusion criteria. Four had degenerative lumbosacral stenosis and one had discospondylitis. All dogs had failed medical management prior to surgery. Of 32 bicortical pedicle screws placed, 30 were fully contained inside the pedicle and 2 were partially breaching the vertebral canal (less than one-third of the screw diameter). Postoperative CT revealed good alignment of L7-S1 in all planes. CONCLUSION: This technique enabled an accurate and safe placement of pedicle screws in the lumbosacral region of dogs with lumbosacral disease. Three-dimensional, printed patient-specific drill guides are a safe and effective method of placing pedicle screws in dogs with lumbosacral disease.

Medial Bone Plating for Management of Type V Central Tarsal Bone Fractures in Six Dogs.

OBJECTIVE: The aim of this study was to report the surgical technique and outcomes of dogs with type V central tarsal bone (CTB) fractures stabilized with a bone plate applied to the medial aspect of the tarsus and metatarsus. STUDY DESIGN: This study was a retrospective review of dogs with type V CTB fractures diagnosed with computed tomography and stabilized using a medial bone plate. Follow-up included clinical examination and radiography 8 to 10 weeks postoperatively and/or a long-term owner questionnaire. RESULTS: Six dogs were identified. All fractures occurred during exercise without external trauma and all dogs had additional tarsal fractures. Five dogs returned for clinical follow-up; all had no or mild lameness and evidence of fracture healing on radiography. A suspected surgical site infection occurred in one dog and resolved with medical management. Suspected contact between the plate and medial malleolus in one dog, and loosening of a talar screw in another, were identified, though not treated. Five owners completed the questionnaire, a median of 88 months postoperatively. No further complications were reported, limb function was reportedly acceptable, and all owners were very satisfied with the surgery. CONCLUSION: Medial bone plate stabilization of highly comminuted CTB fractures resulted in evidence of fracture healing, and a low incidence of complications in six non-racing dogs.