Trochlear Ridge Prostheses for Reshaping Femoral Trochlear Ridges in Dogs with Patellar Luxation.

OBJECTIVES: To describe the implant characteristics and surgical application of a custom-made trochlear ridge prosthesis (TRP) and to report clinical outcomes in dogs affected by patellar luxation treated with TRP. STUDY DESIGN: Dogs affected by patellar luxation underwent computed tomography. A specific canine bone anatomical replica, a cutting guide, and a TRP were designed and provided for surgery. Surgical records, clinical and radiographic reassessments, complications, pre- and postoperative lameness, type and degree of patellar luxation, and TRP and patellar position after surgery were reviewed. Clinical outcomes were defined as full, acceptable, or unacceptable function. RESULTS: The TRP was implanted in 60 femoral trochleae: 48 unilateral and 12 bilateral. Successful correction of patellar luxation was achieved in 59/60 cases. TRP was applied with other surgical techniques in 36/60 of the cases and as the only surgical procedure in 24/60 cases. Overall, three complications were observed: two minor and one major (patellar luxation recurrence). Neither implant loosening nor infection was observed. The mean radiographic follow-up was 3.8 months. At the time of the final follow-up, 57/60 cases were scored as fully functional. CONCLUSION: The TRP application either alone or in combination with other surgical techniques allowed for correction of patellar luxation and improvement in preoperative lameness with nominal complications. TRP could represent a potentially reliable alternative to trochleoplasty.

Three-dimensional volume rendering planning, surgical treatment, and clinical outcomes for femoral and tibial detorsional osteotomies in dogs.

OBJECTIVES: To describe a computed tomographic (CT) methodology for planning the correction of femoral and tibial torsion and report the clinical outcomes after femoral (FDO) and tibial (TDO) detorsional osteotomy in dogs affected by torsion malalignment and patellar luxation (PL). STUDY DESIGN: Multicenter retrospective study. ANIMALS: Eighteen client-owned dogs. METHODS: Dogs underwent CT to measure femoral (FTA) and tibial torsion angle (TTA). Abnormal femoral external torsion was defined when FTA <20°, abnormal femoral internal torsion if FTA >35°; abnormal tibial external torsion was defined when TTA < -10°, and abnormal tibial internal torsion when TTA >2°. The cortical arch length (CAL) was measured with CT and used intraoperatively to determine the magnitude of correction. The medical records and radiographs were reviewed and used to report clinical and radiographic outcomes. Radiographs were reviewed to evaluate postoperative limb alignment, patellar position, and bone healing. RESULTS: Twenty-two detorsional osteotomies were performed. Mean preoperative FTA was 14° for medial-PL and 45.2° for lateral-PL. Mean preoperative TTA was 11° for medial-PL. Physiological patellar tracking was restored in 22/22 of cases. CAL measurement allowed for correction of abnormal torsion in 19/22 of cases. Seventeen out 18 dogs had full or acceptable functional outcome. The median radiographic follow-up was 3 months. Major complications occurred in 2/22 cases, which suffered an iatrogenic abnormal femoral internal torsion and a persistent hindlimb lameness. CONCLUSIONS: CAL can be measured with CT and used intraoperatively to guide the correction of abnormal torsion in dogs. CLINICAL RELEVANCE: Abnormal femoral and tibial torsion are predisposing factors for PL. A higher complication rate is expected when FDO and TDO are performed in the same hindlimb.

Occipital cranioplasty using customized titanium prosthesis yields successful outcome in association with foramen magnum decompression in dogs suffering by Chiari-like malformation.

OBJECTIVE: To describe the use of a customized 3-D-printed titanium prosthesis as adjunctive treatment for foramen magnum decompression (FMD) in dogs with Chiari-like malformation (CM) and syringomyelia (SM). ANIMALS: 8 dogs with clinical signs and MRI findings of CM-SM. PROCEDURES: 3-D reconstruction of CT images of the head was used to simulate an occipital craniectomy and design the prosthesis. FMD was performed, and the prosthesis was implanted. Follow-up was performed 1, 6, and 12 months later, and clinical status was scored. Repeated MRI images were compared to identify changes involving the neural structures, particularly the syrinx. RESULTS: All prostheses were easily positioned based on the preoperative 3-D models, with no complications. At 12 months after surgery, 3 dogs were free of previous medications, 4 were still receiving steroid medications but at lower doses, and 1 was occasionally receiving acupuncture. MRI of 5 dogs 6 to 20 months after surgery revealed resolution of SM (n = 1), reduced size of SM (3), or worse SM (1). All dogs showed an increase in size of the caudal cranial fossa. Dogs with a longer presurgical duration of the clinical signs and wider syrinx generally had worse outcomes than other dogs. CLINICAL RELEVANCE: Findings suggested that use of customized 3-D-printed titanium prosthesis and associated FMD can represent an adjunctive option to medically treated dogs with CM-SM. Although the small number of cases precludes definitive conclusions, early surgical treatment, particularly in dogs with a small syrinx, could ensure better long-term outcomes, as previously suggested.

Tarsometatarsal stabilization after metatarsal bone amputation for treatment of an aneurysmal bone cyst in a cat.

CASE DESCRIPTION: A 5-year-old 4.0-kg (8.8-lb) castrated male domestic shorthair cat was referred because of grade 4/5 left hind limb lameness and swelling in the region of the second metatarsal bone of that limb. CLINICAL FINDINGS: Computed tomography revealed an expansile osteolytic lesion of the second metatarsal bone associated with a periosteal reaction on the third metatarsal bone. There was no evidence of metastases. TREATMENT AND OUTCOME: Amputation of the second and third metatarsal bones was performed but resulted in medial instability of the remaining metatarsal bones. The instability was treated by placing a loop of 2-0 monofilament, nonabsorbable suture from a screw placed in the distal row of the tarsal bones to a tunnel in the proximal metaphysis of the fourth metatarsal bone. Clinical reevaluation of the cat 7, 15, 30, 60, 90, and 210 days after surgery and radiographic reevaluation 90 and 210 days after surgery showed complete recovery of the cat. The implants were removed at the time of the 7-month reevaluation. Clinical evaluation 18 months after implant removal showed the treated joint to be stable. CLINICAL RELEVANCE: The surgical stabilization technique described here provided medial stability of the tarsometatarsal joint after amputation of the second and third metatarsal bones. This method may be an alternative to arthrodesis while maintaining articular function in cats.

A three-dimensional computed tomographic volume rendering methodology to measure the tibial torsion angle in dogs.

OBJECTIVE: To describe a three-dimensional (3D) computed tomographic (CT) methodology to measure the tibial torsion angle (TTa) and to evaluate intrarater and interrater agreements and accuracy through comparison with anatomic measurements. STUDY DESIGN: Ex vivo cadaveric study. SAMPLE POPULATION: Thirty-six tibiae from 18 dogs. METHODS: Tibial torsion angle of each tibia was measured by using two CT techniques (axial and 3D volume rendering) by three raters who blindly measured TTa in duplicate. A semitransparent bone filter was used to enhance the visibility of the target anatomical landmarks for the 3D volume rendering CT technique. Tibial torsion angle was also quantitated in tibial specimens. Intrarater and interrater agreements were analyzed by using intraclass coefficients (ICC). Accuracy was evaluated by using adjusted R2 coefficients (R2 > 80% was considered acceptable). RESULTS: The 3D volume rendering CT technique had excellent intrarater and interrater agreements (ICC > 0.94) and an R2 value of 97%. The axial CT technique had good to excellent intrarater and interrater agreements (0.8 < ICC < 0.95) and an R2 of 86%. No difference was found between axial and 3D CT techniques. A mean internal TT angle of approximately -6° was found with CT and anatomic measurements. CONCLUSION: The 3D volume rendering and axial CT techniques were precise and accurate for measuring TTa in dogs unaffected by patellar luxation. CLINICAL RELEVANCE: Combining 3D bone manipulation with application of a semitransparent filter allows simultaneous visualization of anatomic landmarks, which may facilitate the evaluation of complex bone deformations. Internal tibial torsion may be present in nonchondrodystrophic dogs without patella luxation.

Computed tomographic localization of the deepest portion of the femoral trochlear groove in healthy dogs.

OBJECTIVE: To validate a computed tomographic (CT) method to measure the femoral trochlear groove depth (FTGD). STUDY DESIGN: Cadaveric study. SAMPLE POPULATION: Fifteen dogs, 26 femoral trochleae. METHODS: Five points were identified from proximal to distal (proximal point [PP], P25, P50, P75, and distal point [DP]) along the trochlea via three-dimensional volume-rendering function on the sagittal plane and measured on multiplanar reconstruction images. Each rater repeated measurements in duplicate, unaware of the identity of the joint. The FTGD was quantitated on the anatomical specimens and statistically compared with CT measurements. Intrarater and interrater agreements were analyzed by using intraclass coefficients. Accuracy was evaluated by using either adjusted R2 coefficients (R2 > 80% was considered acceptable) or Student's t test. The ratio of the patellar and the trochlear width and the ratio of the patellar craniocaudal thickness inside the trochlear groove were calculated at three different patellar locations. RESULTS: Good to excellent intrarater and interrater agreements were observed in four of five trochlear points (P25, P50, P75, and DP), and accuracy was acceptable for these points (R2 > 80%). Computed tomographic measurements differed from the mean anatomical measurements at three of five points (PP, P50, and P75; P < .01), overestimating the FTGD by an overall mean of 0.18 mm (range, 0.02-0.3). P25 and P50 were the deepest points measured. CONCLUSION: Computed tomography allowed precise measurements of trochlear groove depth except for the most proximal point. The deepest trochlear points were P25 and P50. P25 was the most precise and accurate point measured, while PP was the least consistent. CLINICAL SIGNIFICANCE: The deepest portion of the trochlea groove may be located between P25 and P50. Evaluation of this CT method in dogs with patellar luxation is recommended.

Supercutaneous Plating for the Treatment of Traumatic Injuries of the Appendicular Skeleton in Dogs.

OBJECTIVES: The purpose of this study was to report the clinical outcomes of traumatic appendicular bone injuries treated with supercutaneous plating. METHODS: We conducted a retrospective case series of medical records following fracture fixation using locking implants with a supercutaneous plating technique. Inclusion criteria comprised a complete clinical and radiographical follow-up until implant removal. Patient history and signalment as well as fracture configuration were recorded. RESULTS: Five appendicular long bone fractures (3 radii, 2 tibiae) were included in the study and they were all treated using conical coupling locking plates. The patient mean age was 2.3 years (range: 0.3-5.8 years) and the mean body weight 16.5 kg (range: 3-27 kg).One major (implant failure) and minor complications (delayed bone union and iatrogenic recurvatum deformity) were detected. The removal of the plates was quick and did not require general anaesthesia. All five fractures treated healed and patients were sound at final follow-up. Neither discomfort nor pain were noticed during the postoperative patient management. CLINICAL SIGNIFICANCE: The advantages related to the minimally invasive approach and implant removal could make the supercutaneous plating (SCP) an alternative to the traditional external skeletal fixation.Further clinical investigations are required before definitive treatment recommendations using this technique can be made. In consideration of some of the complications detected, the use of fluoroscopy is recommended to support the surgeon at the beginning of their SCP learning curve.

Supracutaneous plating using a locking plate for the treatment of a tibial fracture in a cat.

Radiographs revealed a slightly displaced long oblique diaphyseal tibial fracture with bone fissures running distally in a 2-year-old, 4.5 kg cat that had been hit by a car. An angle stable implant was applied in a supracutaneous fashion. The patient tolerated the external implant and had a satisfactory functional recovery. Radiographic follow-up after 60 days revealed sign of osseous union; therefore, the plate was removed.

Plaque supracutanée à l'aide d'une plaque de fixation pour le traitement d'une fracture tibiale chez un chat. Des radiographies ont révélé une fracture tibiale diaphyséale longue et oblique légèrement déplacée avec des os fissurés distalement chez un chat de 4,5 kg âgé de 2 ans qui avait été heurté par une automobile. Un implant à angle stable a été appliqué d'une manière supracutanée. Le patient a toléré l'implant externe et a connu un rétablissement fonctionnel satisfaisant. Un suivi radiographique après 60 jours a révélé des signes d'union osseuse. Par conséquent, la plaque a été retirée.(Traduit par Isabelle Vallières).