Outcome of surgical correction of medial patellar luxation in dogs weighing less than 10 kg.

BACKGROUND: Various trochleoplasty techniques, including trochlear wedge recession (TWR) and trochlear block recession (TBR), are used to treat dogs with medial patellar luxation (MPL). However, the objective outcomes of these surgical procedures are underreported. METHODS: Medical records were obtained for dogs weighing less than 10 kg that underwent either TWR or TBR and tibial tuberosity transposition to address grade I-III MPL. Long-term (at least 1 year after the last procedure) follow-up included orthopaedic and radiographic examinations, such as osteoarthritis score (OAS), ground reaction force (GRF) analysis and canine brief pain inventory (CBPI). RESULTS: Overall, 20 dogs (26 stifles) were followed up in the long term. Minor postoperative complications, medial patellar reluxation (MPR) and intermittent lameness occurred in 46.15%, 19.23% and 15% of the dogs, respectively. MPR occurred only in TWR-treated stifles, while mean OAS increased in all groups. Using the CBPI, the owners perceived an excellent or very good outcome in 95% of dogs. LIMITATIONS: The limitations of the study include its retrospective observational nature, a lack of randomisation and a small sample size. CONCLUSION: Surgical treatment resulted in a favourable outcome. GRF analysis could detect subtle differences in weight bearing in dogs treated for MPL, which might not be apparent clinically. There might be a higher risk for reluxation for TWR. However, a larger-scale prospective study would be required to find which treatment is superior.

Short-term outcomes of cranial cruciate ligament rupture treated surgically with tibial plateau leveling osteotomy or non-surgically in small-breed dogs weighing less than10 kg.

Cranial cruciate ligament rupture (CCLR) is a common cause of stifle joint pain in dogs. This study assessed the short-term outcomes in the management of CCLR, with or without concurrent medial patellar luxation (MPL), in small-breed dogs, comparing surgical intervention using tibial plateau leveling osteotomy (TPLO) with non-surgical approaches. Dogs weighing less than 10 kg and suffering from CCLR were divided into two groups: surgical and non-surgical (nine stifles per group). Both groups followed the same rehabilitation protocol. Measurements were taken on days 0, 14, 28, 42, 56, 70, and 84. These measurements included the mean difference in orthopedic assessment score (diffOAS) and thigh muscle circumference (TMC) assessed by veterinarians, as well as the Canine Brief Pain Inventory score (CBPI) evaluated by the owners. Six stifles had concurrent MPL in the surgical group and five in the non-surgical group. No significant differences were observed in diffOAS (P=0.685), TMC (P=0.557), CBPI pain severity score (P=0.062), and CBPI pain interference score (P=0.29) between the two groups. However, both groups showed a significant decrease (P<0.05) in diffOAS and CBPI. The TMC remained relatively stable in the non-surgical group (P>0.05), but it significantly increased in the surgical group (P<0.05). Both groups demonstrated improved clinical outcomes in the short term, with no significant differences. However, cautious consideration should be given to a conservative treatment in small-breed dogs, particularly when considering the exclusive improvement observed in TMC within the TPLO group.

Intra-articular Fibrolipoma of the Stifle in a Dog.

A 12 yr old male castrated miniature Australian shepherd dog presented for surgical consultation of historical bilateral medial patellar luxations with a 3 mo history of an acute onset of a left pelvic limb lameness. Physical examination confirmed medial patellar luxations and a mass effect of the left stifle medially. Radiographs showed medial distension of the joint capsule by a soft tissue opacity. Fine-needle aspirate of the left stifle revealed a mesenchymal cell population. Left medial parapatellar stifle arthrotomy found a fatty mass, which was excised at its base. A benign fibrolipoma was diagnosed on histopathology, and the excision was expected to be curative. The owners reported immediate improvement of perceived comfort postoperatively. At 2 and 24 wk, the dog returned to a normal level of function. Lipomas of the stifle, although rare, should be considered as a differential for intra-articular masses causing lameness.

Complications and Long-Term Outcomes after Combined Tibial Plateau Leveling Osteotomy and Tibial Tuberosity Transposition for Treatment of Concurrent Cranial Cruciate Ligament Rupture and Grade III or IV Medial Patellar Luxation.

OBJECTIVES: This study aims to report complications and long-term outcomes of combined tibial plateau leveling osteotomy and tibial tuberosity transposition (TPLO-TTT) for treatment of concurrent cranial cruciate ligament rupture and medial patellar luxation (MPL). STUDY DESIGN: This is a retrospective study. Dogs that underwent TPLO-TTT for treatment of combined cranial cruciate ligament rupture and grade III or IV MPL were included. Signalment, fixation method, and complications were recorded. Long-term outcome assessment (minimum 1 year postoperatively) was performed through clinical and radiographic reexamination at the authors' institution. RESULTS: Twenty-four stifles (22 dogs) were included. Twenty-one stifles had a grade III MPL, and 3 stifles had grade IV MPL. Four major complications consisting of surgical site infection (n = 3) and recurrent grade II MPL (n = 1) were observed. Dogs with surgical site infections were successfully treated with implant removal and oral antibiotics. No additional surgery was performed for the patient with recurrent MPL as no signs of lameness were observed. Minor complications occurred in five cases. At long-term evaluation (median: 27 months; range: 12-67 months), 21/22 dogs were clinically sound and 23/24 stifles had a complete resolution of MPL. CONCLUSION: TPLO-TTT can be considered as an effective surgical option to treat patients with concurrent cranial cruciate ligament rupture and MPL with a relatively low major complication rate. Owners should be warned of the potential need for implant removal.

The epidemiology of patellar luxation in an insured Swedish dog population.

Patellar luxation (PL) is a common orthopaedic condition in dogs. This study aimed to evaluate the incidence and cause-specific mortality rate, age at diagnosis, and risk factors for medial PL (MPL), lateral PL (LPL), and bidirectional PL (BPL). Other diagnoses in dogs with PL were also explored. The study population included just over 600,000 dogs insured by Agria Pet Insurance in Sweden (2011-2016). There were 2726 dogs with PL. Medial patellar luxation affected 90 % of the dogs with PL, followed by LPL (5.9 %), BPL (2.4 %), and unspecified PL (1.6 %). The median age at first diagnosis during the study period was 2.8 years for MPL, 2.7 years for LPL, and 1.5 years for BPL. In total, 168 (6.2 %) of the dogs with PL had cruciate ligament rupture. There were substantial breed-specific differences in the risk of PL: almost all breeds at increased risk of MPL were small-sized, while several of the breeds at increased risk of LPL were large-sized. The breeds at high risk of BPL varied in size. Females had an increased risk of MPL (RR 1.2, 95 % CI: 1.1-1.3, p < 0.001) and a decreased risk of LPL (RR 0.72, 95 % CI: 0.51-1.0, p = 0.042) compared to males. In total, 116 dogs were euthanised due to PL and the breeds with the highest risk of PL-related euthanasia were the Pyrenean mountain dog, Dogue de Bordeaux, and German pinscher. The median age for PL-related euthanasia was 2.2 years.

[Comparison of the reoperation rates of three techniques for tibial tuberosity transposition in medial patellar dislocation]. / Vergleich der Reoperationsraten von drei Techniken zur Fixation der bei medialer Patellaluxation transponierten Tuberositas tibiae.

INTRODUCTION: A common technique for the treatment of medial patellar luxation is the lateral transposition of the tibial tuberosity. Two variations of a new surgical method with a retention plate and fixation with a wire or a security plate, were tested against each other and against the existing fixation with Kirschner wires and a tension band by the number of reoperations. The new method using a retention plate and security plate showed the lowest rate of reoperations (5 %), followed by the new technique using retention plate and wire (14 %) and the existing fixation with Kirschner wires and a tension band (34 %). A possible explanation for the good result of the new method can be the fixation of the implants on the medial side of the tibia and the non-use of Kirschner wires.

INTRODUCTION: La transposition latérale de la tubérosité tibiale est une technique courante pour le traitement de la luxation rotulienne médiale. Deux variantes d'une nouvelle méthode chirurgicale avec une plaque de rétention et une fixation avec un fil métallique respectivement un étrier en titane ont été testées l'une par rapport à l'autre et par rapport à la fixation usuelle avec des broches de Kirschner et un haubanage en fonction du nombre de réopérations. La nouvelle méthode utilisant une plaque de rétention et un étrier a montré le taux le plus bas de réopérations (5 %), suivie par la nouvelle technique utilisant une plaque de rétention et une broche (14 %) et la fixation usuelle avec des broches de Kirschner et un haubanage (34 %). Le bon résultat de la nouvelle méthode peut s'expliquer par la fixation des implants sur la face médiale du tibia et la non-utilisation de broches de Kirschner.

Partial Parasagittal Patellectomy in Dogs: A Retrospective Case Series of 19 Dogs.

OBJECTIVE: The aim of this study was to describe partial parasagittal patellectomy for the surgical management of patellar luxation, including surgical technique, proposed indications, complications, and outcomes in a cohort of dogs. STUDY DESIGN: This is a single-center retrospective clinical case series. METHODS: Medical records (2019-2020) of dogs presenting for patellar luxation were reviewed. Clinical signs, luxation direction and grade, preoperative imaging and intraoperative findings, and complications were retrospectively retrieved. Owners were contacted via questionnaire for medium- and long-term follow-up. RESULTS: A total of 24 stifles in 19 dogs met the inclusion criteria. Intraoperative minor complications occurred in four stifles. A single minor complication occurred postoperatively with no major complications. Increased thickness and radiographic attenuation of the patellar ligament were noted in 14 stifles at radiographic reassessment. Re-luxation was not encountered, with long-term owner-assessed outcome as good to excellent in all cases. CONCLUSION: Partial parasagittal patellectomy, used in conjunction with block recession trochleoplasty and tibial tuberosity transposition, provided reliable resolution of patellar luxation in canine stifles with grade 2 or 3 luxation where width mismatch between the patella and the trochlea was noted intraoperatively. Long-term outcome appears to be good to excellent with a low rate of complication.

Evaluation of Surgical Technique and Clinical Results of a Procedure-Specific Fixation Method for Tibial Tuberosity Transposition in Dogs: 37 Cases.

OBJECTIVE: The aim of this study was to describe the use of a procedure-specific fixation method for tibial tuberosity transposition and report clinical outcome. STUDY DESIGN: This is a multi-institutional case series, evaluating 37 cases that were treated surgically for medial patellar luxation (MPL) and in which the tibial tuberosity transposition (TTT) was performed using the Rapid Luxation Plating System (RLPS). Surgical technique, implants, clinical outcome, and complications are reported. RESULTS: Surgery was successfully performed in dogs weighing 2.5 to 36.2 kg. Postoperative minor complications occurred in 13 cases (35%) and major complications occurred in 3 cases (8%). No implant-related complications or tibial tuberosity avulsions or fractures were seen. Outcome related to surgery was good or excellent in all cases. CONCLUSION: The RLPS for TTT provides a feasible technique in a large range of patients with MPL and lowers the occurrence of implant-related complications and tibial tuberosity avulsion or fracture.

Effect of Plate Type on Tibial Plateau Levelling and Medialization Osteotomy for Treatment of Cranial Cruciate Ligament Rupture and Concomitant Medial Patellar Luxation in Small Breed Dogs: An In Vitro Study.

OBJECTIVE: The main aim of this study was to determine the effective magnitude of proximal tibial segment medialization achievable during tibial plateau levelling and medialization osteotomy (TPLO-M) with Fixin 1.9-2.5 mm pre-contoured T plates with three different offsets. METHODS: In this in vitro study, 36 tibia bone models reconstructed using stereolithography from hindlimb CT scans of a 5 kg dog and a 10 kg dog without orthopaedic disease were used. TPLO-M was performed using plates with three different offsets (2, 4 and 6 mm). Post-osteotomy radiographic and bone models measurements were performed. RESULTS: Regardless of patient weight, the +4 mm offset plates provided a translation of 2.93mm (± 0.51) while the +6 mm offset plates provided a translation of 5.03mm (± 0.47). In the 5kg dog bone model group limited bone contact at the osteotomy site was documented when using the +6mm offset plate. CONCLUSION: The +4mm and +6mm offset Fixin plates may be considered for TPLO-M in dogs weighing between 5 and 10 kg. The +6mm offset plate should be used cautiously in dogs weighing less than 10 kg since this plate may result in insufficient postoperative bone apposition at the osteotomy site.

Outcomes and complications of a modified tibial tuberosity transposition technique in the treatment of medial patellar luxation in dogs.

OBJECTIVE: To report a modification of the tibial tuberosity transposition (m-TTT) technique used to treat medial patellar luxation (MPL) in dogs, and report its complications. STUDY DESIGN: Retrospective case series. SAMPLE POPULATION: Dogs (n = 235) undergoing MPL correction, using m-TTT (n = 300 stifles). METHODS: Medical records and client surveys were reviewed to determine complications associated with this technique and they were compared with previously reported complications using similar techniques. RESULTS: Short-term minor complications included low-grade reluxation (11 stifles, 3.6%), incisional seroma (nine stifles, 3%), pin-associated swelling (seven stifles, 2.3%), patellar desmitis (six stifles, 2%), superficial incisional infection (four stifles, 1.3%), pin migration (three stifles, 1%), tibial tuberosity (TT) fracture (two stifles, 0.6%), tibial tuberosity displacement and patella alta (one stifle, 0.3%), pin-associated discomfort (one stifle, 0.3%), trochlear block fracture (one stifle, 0.3%). Short-term major complications included pin migration (three stifles, 1%), incisional infection (two stifles, 0.6%), tibial tuberosity fracture (two stifles, 0.6%), and high grade reluxation (two stifles, 0.6%). Long-term follow-up examination data were available for 109/300 (36.3%) stifles. One minor complication and four major complications were documented. All long-term complications were due to pin migration. The overall major complication rate was 4.3% (13/300 stifles), with a minor complication rate of 15% (46/300 stifles). The owner survey indicated a 100% satisfaction rate. CONCLUSION: The m-TTT technique yielded acceptable complication rates, with high owner satisfaction. CLINICAL SIGNIFICANCE: The m-TTT should be considered as an alternative technique for treating dogs with MPL requiring a tibial tuberosity transposition.

Medial patellar luxation grade IV according to the Singleton system can be classified into skeletally immature and skeletally matured types.

OBJECTIVE: To determine the signalment and musculoskeletal morphology of small-breed dogs affected by medial patellar luxation (MPL) grade IV based on the age of the CT scan. ANIMALS: 40 small-breed dogs (54 limbs) with MPL grade IV. PROCEDURES: Dogs that had undergone corrective surgery for MPL grade IV and had performed CT of the hind limb before surgery were included. Signalment (age, body weight, sex, laterality, and breed) and concomitant cranial cruciate ligament rupture (CrCLR) were recorded. Femoral inclination angle, anatomical lateral distal femoral angle (aLDFA), femoral torsion angle, quadriceps muscle length to femoral length ratio (QML/FL), and patellar ligament length to patellar length were obtained by CT images. The dogs were categorized into 2 groups based on their age at the time of the CT scan, the skeletally immature group and the skeletally matured group. Signalment and group were included in the multiple regression analysis to determine the factors associated with each measurement parameter. A logistic regression analysis was conducted to determine the risk of CrCL concomitant with age. RESULTS: The multiple regression model demonstrated that the group was associated with the value of aLDFA and QML/FL. aLDFA was higher, and QML/FL was lower in group SI than in group SM. CrCLR was present in 5/54 limbs (9.2%), with a mean age of 70.8 months and it was associated with increasing age. CLINICAL RELEVANCE: In Singleton's classification, dogs classified as grade IV can be categorized into 2 groups based on musculoskeletal morphology and pathophysiology: the skeletally immature and skeletally matured types.

Examination of Proximodistal Patellar Position in Dogs with the Stifle at Full Extension.

OBJECTIVE: The aim of this study was to determine the factors related to functional patella alta, with which the proximodistal patellar position exceeds the reference range of healthy small dogs proximally when the stifle is at full extension. STUDY DESIGN: Mediolateral-view radiographs of dogs weighing less than 15 kg were obtained and classified into the medial patellar luxation (MPL) and control groups. The reference range of the proximodistal patellar position was determined from the control group. In both groups, a patellar position exceeding this reference range proximally was considered functional patella alta. Multiple logistic regression analysis was performed to examine the factors related to functional patella alta. A receiver operating characteristic (ROC) curve was made for each factor. RESULTS: Overall, radiographs of 127 stifles of 75 dogs were obtained. Eleven stifles in the MPL group and one stifle in the control group were determined to be functional patella alta. The factors associated with functional patella alta included a greater full extension angle of the stifle joint, longer patellar ligament, and shorter femoral trochlear length. The full extension angle of the stifle joint had the biggest area under the ROC curve. CONCLUSION: Mediolateral radiographs of the stifle joint in full extension are clinically important in dogs with MPL because some dogs might have a proximally positioned patella that is recognizable only when the stifles are extended.

Evaluation of the quadriceps muscle length to femoral length ratio in small breed dogs with medial patellar luxation.

OBJECTIVE: To determine the quadriceps muscle length (QML) to femoral length (FL) ratio (QML/FL) and its associated factors in small breed dogs with medial patellar luxation (MPL) and to compare the differences in the QML/FL between MPL grades. STUDY DESIGN: Retrospective study. SAMPLE POPULATION: Small breed dogs (<10 kg) with MPL: 78 dogs (134 limbs). METHODS: Medical records and computed tomography (CT) images from 2008-2020 were reviewed. Furthermore, age, bodyweight, sex, laterality, MPL grade, femoral inclination angle (FIA), femoral torsion angle (FTA), anatomical lateral distal femoral angle (aLDFA), and patellar ligament length to patellar length ratio were included in the regression analysis to determine the factors associated with QML/FL. Each measurement parameter was compared among the four MPL grade groups. RESULTS: The final model demonstrated that the QML/FL increased with increasing age (p = .004) and decreased with increasing FTA and aLDFA (p = .015 and p < .001, respectively). The MPL grade IV group had a lower QML/FL than the grade I, II, and III groups (p = .002, p < .001, and p < .001, respectively). CONCLUSION: Among small breed dogs, those with MPL grade IV had a shortened QML associated with femoral deformities. CLINICAL SIGNIFICANCE: Noninvasive evaluation of the QML/FL improves our understanding of the length mismatch between the quadriceps muscle and the femur.

Preoperative and postoperative stance analysis in dogs with patellar luxation confirms lameness improvement after surgery.

OBJECTIVE: To document and compare preoperative and postoperative stance analysis measurements in animals with naturally occurring patellar luxation. ANIMALS: 131 client-owned dogs surgically treated for naturally occurring unilateral or bilateral patella luxation between March 30, 2015, and February 12, 2020. PROCEDURES: Weight bearing as a percent body weight on each limb was recorded with the use of a platform device for analyzing stance (PetSafe Stance Analyzer; LiteCure LLC, Companion Animal Health) preoperatively and postoperatively for all dogs. Signalment, limb affected, lameness grade, luxation direction, luxation grade, and surgical procedure were collected from patient records and assessed for the effects of these variables on weight bearing preoperatively or at the first or second postoperative recheck examination. RESULTS: There were 61 males and 70 females, with a mean age and body weight of 4.62 years and 13.01 kg, included in the study. As age increased, body weight decreased in these dogs (P = .025). There was a statistically significant improvement in lameness after surgery (P = .008) at the second postoperative recheck examination. Lameness significantly decreased as postoperative time increased (P < .001, r = 0.503). As age increased, lameness at the initial visit decreased compared to younger dogs but not significantly (P = .062). There was no significant effect of preoperative luxation grade, luxation direction, surgical procedure, or sex when comparing initial lameness or lameness at recheck examination. CLINICAL RELEVANCE: Surgical correction of patella luxation improves lameness as measured by postoperative stance analysis. Preoperative luxation grade or direction, surgical procedure performed, and sex of the animal did not significantly affect outcome in this group of dogs.

The value of routine radiographic follow up in the postoperative management of canine medial patellar luxation.

OBJECTIVE: To determine the influence of radiographic examination on the recommendations made at the time of planned re-evaluation of dogs after medial patellar luxation (MPL) surgery. STUDY DESIGN: Retrospective multi-institutional case series. ANIMALS: Client-owned dogs (N = 825) that underwent MPL surgery. METHODS: Records of 10 referral institutions were searched for dogs that had been treated surgically for unilateral MPL and underwent a planned follow-up visit, including radiographs. The frequency of, and reasons for, changes in further recovery recommendations were investigated. RESULTS: Follow up was performed at a median of 6 (range, 4-20) weeks postoperatively. Isolated radiographic abnormalities were identified in 3.3% (27/825) of dogs following MPL surgery and led to a change in recommendations in 3% (13/432) of dogs that were presented without owner or clinician concerns. Lameness, administration of analgesia at follow up, and history of unplanned visits prior to routine re-examination were associated with a change in postoperative plan (P < .001). In the absence of owner and clinician concerns, the odds of having a change in convalescence plans were not different, whether or not isolated radiographic abnormalities were present (P = .641). CONCLUSION: Routine radiographs at follow up did not influence postoperative management of most dogs after MPL surgery in the absence of abnormalities on clinical history or orthopedic examination. CLINICAL SIGNIFICANCE: Dogs that were presented for routine follow up after unilateral MPL surgery without owner concerns, lameness, analgesic treatment or a history of unplanned visits, and for which examination by a surgical specialist was unremarkable, were unlikely to benefit from radiographs.

Patellar Proximo-Distal Displacement following Modified Maquet Technique Is Not Predictive of Patellar Luxation.

OBJECTIVE: The aim of this study was to test the low sensitivity of the Allberg and Miles index to the stifle opening angle, evaluate the displacement of the patella after a Modified Maquet Technique using this index and assess the incidence of patellar luxation post-Modified Maquet Technique in dogs. STUDY DESIGN: Medical records were reviewed from 2012 to 2017. Allberg Miles index were determined for each stifle pre- and postoperatively, as well as the stifle joint opening of each case. Occurrence of patellar luxation was recorded. RESULTS: 137 stifles on 116 dogs were reviewed. The stifle opening angle did not influence the Allberg Miles index. Pre- and postoperative index showed a distal displacement of the patella after a Modified Maquet Procedure, especially at 135° of stifle opening angle. Only 1/137 cases demonstrated patellar luxation after the surgery. CONCLUSION: Based on our statistical analysis, we were able to conclude that within the maximum stifle opening angle range recorded in our series of cases; the Allberg Miles index variation was not significant. While patellar baja is clearly induced by the Modified Maquet Technique, the latter did not seem to predispose patients to post-operative patellar luxation in our study population.

Ideal Anchor Points for Patellar Anti-rotational Sutures for Management of Medial Patellar Luxation in Dogs: A Radiographic Survey.

OBJECTIVE: The aim of this study was to identify the ideal anchor point for patellar anti-rotational sutures for adjunctive stabilization of medial patellar luxation in both small and large breed dogs. STUDY DESIGN: Retrospective radiographic survey was performed on 110 stifles from 101 dogs. Radiographs were grouped based on patient weight (≤15 kg; >15 kg) and diagnosis (medial patellar luxation, cranial cruciate ligament rupture, and normal joints). Radiographic measurements included: the proximal, middle, and distal points of the trochlear ridge, the caudal aspect of Blumensaat's line (roof of the intercondylar notch), the centre of the lateral fabella, as well as the "best-fit" centre of a circle overlying the trochlea. These landmark coordinates were used to calculate radii for comparison, and for scaling between joints. RESULTS: Use of the fabellar centre resulted in larger radii (corrected p <0.001) than those from the best-fit circle centre for all but one combination of patient group and trochlear end point locations. Using the best-fit circle centre, radius variation was less marked than with the fabellar centre. Significant differences in location for centres of the best-fit circle and fabella were seen across all patient categories (Pillai's trace p <0.001). CONCLUSION: The fabella is unlikely to be the best choice for anchoring a patellar anti-rotational suture. Use of the best-fit circle centre to place a suture anchor should be preferred to maximise suture isometry during joint flexion and extension in large and small breed dogs.

Computed tomographic measurements of the femoral trochlea in dogs with and without medial patellar luxation.

OBJECTIVES: To determine cutoff values in small (SB) and medium/large (MLB) breed dogs with and without medial patellar luxation (MPL) for identifying abnormal femoral trochlea morphology. STUDY DESIGN: Original research. ANIMALS: A total of 80 computed tomographic (CT) scans from client-owned dogs METHODS: Four groups of 20 dogs were created: (1) control SB, (2) control MLB, (3) MPL-SB, and (4) MPL-MLB. Two authors measured the femoral trochlear groove angle (FTGA), femoral trochlear angle (FTA), and femoral trochlear ridge inclination angle (FTRIA) in two points with CT. ANOVA and ROC-analysis were tested to the control and MPL groups to assess sensitivity, specificity, and cutoff values. Statistical significance was set to p < .05. Intraclass correlation coefficients evaluated the inter-rater agreement. RESULTS: FTGA (± SD) in control SB (128.8° ± 4.7°) and control MLB (119.2° ± 5.6°), was smaller (p < .0001) than in MPL-SB (139.4° ± 4.4°) and MPL-MLB (133.7° ± 5.1°). FTA and FTRIA were decreased (p = .12, p = .23) in MPL-SB (2.1° ± 6.8; -0.3° ± 3.3°) and MPL-MLB (3.8° ± 5.6°; 1.7° ± 4.5°) compared to control SB (0.2° ±4.1; -0.1° ± 2.6°) and control MLB (5.3° ± 2.8°; 3.1° ± 1.3°). Cutoff values for FTGA, FTA, and FTRIA were > 134°, < -5.9°, < -2 ° (SB), and > 128.3°, < -0.4°, < -0.4° (MLB). Sensitivity, specificity, and inter-rater agreement were superior for FTGA than FTA and FTRIA. CONCLUSIONS: Dogs without MPL had a deeper femoral trochlear groove than MPL dogs. SB had a shallower groove than MLB. The measurement of FTA and FTRIA was not reliable. CLINICAL RELEVANCE: A FTGA <134° (SB) and < 128° (MLB) may be considered as a cutoff for trochleoplasty decision-making.

Comparison of Hindlimb Conformation in Cats with and without Medial Patellar Luxation.

OBJECTIVES: Medial patellar luxation (MPL) is the most common developmental cause of hindlimb lameness in cats. The association between femoral and tibial conformation and MPL measured on computed tomography (CT) has not been reported in cats. The aims were to report femoral and tibial conformation in cats with and without MPL and to report normal femoral and tibial angles. METHODS: Angle of inclination of femoral neck (AI), anatomical lateral distal femoral angle (aLDFA), femoral trochanteric angle (FCT), angle of anteversion of femoral neck (AA), distal and proximal anteversion angle (DAA/PAA), overall tibial valgus (TV), tibial torsion (TT), tibial tuberosity displacement (TTD) and trochlear depth:patellar thickness ratio (T:P) were measured by three observers on CT of cats with and without MPL. Comparisons were made between groups. Inter-observer intraclass correlation coefficient (ICC) was calculated. RESULTS: Sixteen cats were recruited: eight control and eight with MPL. The aLDFA, PAA, TT, TTD and T:P were significantly less in cats with high-grade MPL. The AI, FCT, AA, DAA and TV were not significantly different. A high correlation was shown with inter-observer ICC in 33.33% and good correlation in 26.67% when comparing measurements between observers. CLINICAL SIGNIFICANCE: This study suggests that cats with high-grade MPL have decreased TT, TTD and T:P and may require tibial tuberosity transposition and femoral trochleoplasty. The PAA, TT and aLDFA were decreased, although clinical significance may vary and these cats may not require correctional osteotomies. Results should be interpreted with caution as high/good levels of inter-observer ICC occurred in less than two-thirds of cases between observers.

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.