Influence of Limb Positioning and Measurement Method on the Magnitude of the Tibial Plateau Angle

Effect of tibial plateau angle < 5° on ground reaction forces in dogs treated with tibial plateau leveling osteotomy for cranial cruciate ligament rupture up to 6 months postoperatively

Tibial plateau leveling osteotomy (TPLO) has been commonly performed in dogs with cranial cruciate ligament disease (CCLD) since the introduction by Slocum and Slocum (1993). To reduce cranial tibial thrust the TPLO technique aims for a postoperative tibial plateau angle (TPA) of 5-6.5°. In recent years studies have shown that a postoperative TPA below 5° could be beneficial regarding stifle stability or meniscal load. Dogs with CCLD that were treated with TPLO, were examined preoperatively, six weeks, three and six months postoperatively with gait analysis and grouped according to their postoperative TPA. The aims of study was (1) to evaluate if dogs with a postoperative TPA below 5° would have a faster limb function recovery up to six months postoperatively as measured objectively with ground reaction forces (GRFs) and (2) to determine whether the postoperative TPA correlates with the outcome measurements. Dogs with TPA <5° showed no faster limb function recovery postoperatively up to six months as measured with peak vertical force (PVF) or vertical impulse (VI) (p > 0.05). No correlation for the postoperative TPA <5° on GRFs was demonstrated. But the postoperative TPA showed a significant correlation with the symmetry indices of PVF (SIPVF) and VI (SIVI) for all dogs (>5° and <5° TPA together), indicating that with lower postoperative TPA dogs had a more symmetrical gait in hindlimbs SIPVF (r = 0.144, p < 0.05) and SIVI (r = 0.189, p < 0.01). The study indicates that a lower postoperative TPA could be beneficial regarding hindlimb symmetry indices of GRFs.

The effects of tibial tuberosity avulsion and repair on tibial plateau angle in dogs

AIMS

To assess whether tibial tuberosity avulsion injury and subsequent surgical repair in skeletally immature dogs are associated with changes in tibial plateau angle (TPA) at skeletal maturity.

METHODS

Skeletally mature (> 18 months of age) dogs that had previously undergone unilateral surgery when 4-8 months of age to repair tibial tuberosity avulsion were enrolled. Bilateral, mediolateral stifle radiographs were taken. TPA was measured digitally from the radiographs independently by two readers and compared between sides within dogs. As the number of dogs that would be enrolled for the main part of the study was unknown, to understand how the variation between left and right stifles within dogs would affect the power of the main study, 29 client-owned, skeletally mature dogs without stifle pathology were recruited prior to the main study for bilateral, mediolateral projection stifle radiographs. Variation in the differences in TPA between left and right stifles was used to estimate the likely power of the major part of the study for different numbers of enrolled dogs.

RESULTS

From 29 dogs enrolled in the power assessment, the SD of the differences between left and right stifles was 2.1°. With 10 dogs (20 stifles) enrolled within the main part of the study, and if the SD of the differences between operated and non-operated stifles within a dog was the same as the SD of the differences between non-operated stifles within a dog (2.1°), the study would have power ≥ 0.8 if the mean difference in TPA between operated and non-operated stifles was ≥ 2.1°.Ten dogs were enrolled in phase II of the study. In 8/10 of these dogs, the TPA in the operated stifle was less than in the non-operated stifle. The mean TPA on the operated stifle was 6.4° less than on the non-operated stifle (95% CI = 2.4-10.3° less; p = 0.002). For surgery between 4 and 8 months of age, TPA at maturity increased by 2.7° (95% CI = 1.1-4.3°; p = 0.001) for each additional month of age at surgery.

CONCLUSIONS AND CLINICAL RELEVANCE

Based on this study, surgical repair of tibial tuberosity avulsion in skeletally immature dogs is associated with a smaller TPA at skeletal maturity. However, causality cannot be established from this cross-sectional study, and this association may be because stifles with a smaller TPA are predisposed to tibial tuberosity avulsion.

Comparison and interobserver reliability of three different methods for measuring the amount of the tibial tuberosity advancement in the preoperative planning of TTAT

INTRODUCTION

The goal of preoperative planning techniques for advancement of the tibial tuberosity is to determine the amount of advancement required to achieve a postoperative patellar tendon angle of 90° and to select the optimal wedge size to achieve this target.

MATERIAL AND METHODS

Three radiographic methods for determining the advancement distance for the tibial tuberosity were evaluated for comparability and interobserver reliability. Among the methods developed, we decided to include the common tangent method, the tibial anatomy-based method, and the Bielecki method. For all techniques, radiographs were taken in mediolateral projection with the knee joint flexed at 135°. Three observers with different levels of experience independently evaluated and scored the degree of osteoarthritis for each stifle, as previously described, and performed measurements of the amount of advancement of the tibial tuberosity on 33 stifles using common tangent method, tibial anatomy-based method, and Bielecki method.

RESULTS

According to the results, the overall score for osteoarthritis in the mediolateral view was influenced by the experience of the observers, which contradicts the results from a previous study. Regarding the measurement methods used to assess advancement, poor interobserver reliability was found for common tangent method and Bielecki method, while only a slightly moderate interobserver agreement was found for tibial anatomy-based method.

DISCUSSION

These results are inconsistent with data collected by Bielecki and colleagues. Moreover, measurements from common tangent method and tibial anatomy-based method were overlapping, as confirmed previously. Conversely, Bielecki method showed no agreement with the other methods included in the present study, with a significantly higher mean rank, probably due to its correction formula. Based on the results of the present study, tibial anatomy-based method has better interobserver reliability and is easier to perform according to the observers.

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.

In Vitro and In Vivo Studies of Antibacterial Coatings on Titanium Alloy Implants for Veterinary Application

The aim of this work was the evaluation of biological properties of hybrid coatings modified with Ag, Cu, and Zn nanoparticles (NPs) applied on TPLO medical implants by the sol-gel process. The implant coatings enriched with various concentrations of metallic NPs were investigated in the in vitro bactericidal efficacy tests against Gram+ and Gram- bacteria and pathogenic yeast. Next, the designed materials were tested on human osteosarcoma cell lines. The cells adhesion, proliferation, viability, and differentiation were investigated. The cell growth wasevaluated using SEM, and the metallic ion release was measured. The results revealed that the NPs concentration in the hybrid layers decreased with the incubation time. In the last stage, the implants were tested in vivo on six canine patients. Three months after the operation, the radiological evaluation of the performed anastomosis was carried out as well as the histopathological evaluation of tissue regeneration. The strongest bactericidal efficacy was observed for the layers containing AgNPs. Along with an increased concentration of metallic additives, a growing toxic effect was clearly observed. The most pronounced toxic effect was especially evident with the AgNPs concentration exceeding 1 mol %. In all the operated patients, no deviations were found during the follow-up examinations in the postoperative period. The low dose of AgNPs in the hybrid layer facilitated the tissue healing process. It was proven that silver nanoparticles may accelerate the bone healing process. The correct tissue reparation was observed.

The Effect of Femur Positioning on Measurement of Tibial Plateau Angle: An In Vitro Study

Five canine cadaveric pelvic limbs with intact cranial cruciate ligaments were used to quantify the effect of variation in limb positioning on the radiographic measurement of the tibial plateau angle (TPA) with reference to the degree of femoral condyle superimposition. Intra-osseous pin placement and a custom jig design allowed the controlled three-dimensional manipulation of limbs. Medio-lateral digital radiographic projections were taken with perfect femoral hemicondylar superimposition to establish a "reference" TPA (difference in position = 0 mm), and subsequently in varying degrees of supination/pronation and abduction/adduction. The lack of femoral hemicondylar superimposition for each radiograph was quantified using a tangential line technique with reference to the long tibial axis. A total of 176 radiographs were each assessed by three observers. "True" TPA was measured and it ranged within 17-25° across all limbs assessed. Variation in femoral condylar positioning ranged from -13 mm to +13 mm proximo-distally, and -11 mm to +11 mm cranio-caudally. Moreover, 3 mm non-superimposition of the femoral condyles produced 90.6% of measurements with 1° difference between measured and "true" TPA, and a sensitivity of 97.9% for a 2° difference. Further reduction in femoral condylar superimposition to 4 mm reduced the frequency of 1° difference between measured and "true" TPA to 84.9%, and to 94.8% for a 2° difference. In conclusion, measurement of TPA in large breed dogs from radiographs with greater than 3 mm variation in femoral condylar superimposition should be interpreted with caution.

The Role of Tibial Plateau Angle in Canine Cruciate Ligament Rupture-A Review of the Literature

Cranial cruciate ligament disease is a common pathological condition in dogs that is often presented in daily clinical practice. Different risk factors for the development of this condition include breed, sex, age, bodyweight and neuter status, as well as different biological and biomechanical mechanisms. In the literature, special attention has been paid to the role of the tibial plateau angle in damage to the cranial cruciate ligament. Although the disease was first described at the beginning of last century, and since then different surgical methods have been developed to treat it, its aetiology remains unclear. In this review, contemporary literature data related to the role of tibial plateau angle in canine cranial cruciate ligament rupture are presented.

Relationship of mRNA Expression of Selected Genes in Peripheral Blood and Synovial Fluid in Cranial Cruciate Ligament Deficient Stifles of Dogs

Simple Summary

The cranial cruciate ligament rupture is characterized by chronic inflammation, osteoarthritis of the stifle joint, and extracellular matrix degeneration of the ligament itself in dogs. Early pre-clinical cranial cruciate ligament alteration cannot be detected by clinical examination or standard radiography. Therefore, we assessed the possible relationship of inflammatory markers in peripheral blood and synovial fluid of affected stifle joints in comparison to a control. We also evaluated components of the extracellular matrix of ruptured ligaments and finally compared the tibial plateau angle and the anatomical-mechanical angle between groups. Some of the assessed inflammatory markers were significantly increased in both the peripheral blood and synovial fluid compared with the control, as were collagens. The tibial plateau angle was not significantly different; however, the anatomical-mechanical angle significantly increased in the ruptured ligaments. Our results suggest a possible positive relationship between inflammatory markers of blood and synovial fluid in cranial cruciate ligament deficient stifles compared to the control. These findings may support both local and systemic inflammation process at the same time during osteoarthritis progression. Based on this, it would be interesting to investigate the predictive osteoarthritis pathway of inflammatory cytokines, matrix metalloproteinases, and their effect on the extracellular matrix components of the cranial cruciate ligament in future studies.

Abstract

The cranial cruciate ligament rupture (CrCLR) is characterized by chronic inflammation and osteoarthritis (OA) of the stifle joint and extracellular matrix (ECM) degeneration of the ligament itself in dogs. Generally, OA may arise from chronic low-grade systemic inflammation. We assessed the possible relationship of inflammatory markers in the peripheral blood (PB) and synovial fluid (SF) of affected stifle joints in comparison to a control. Moreover, no study has shown the possible association between PB and SF levels of inflammatory markers in CrCLR stifles of dogs in veterinary medicine yet. We also evaluated components of ECM of CrCLR and finally compared the tibial plateau angle (TPA) and the anatomical-mechanical angle (AMA) between groups. Samples from PB and SF were examined for mRNA expression of interleukins, TNF-α and INF-γ. ECM components—collagen 1A1 and 3A1 and elastin—were examined for mRNA expression from SF. The level of relative expression for IL-1β, IL-8 and IFN-γ was significantly increased in both PB and SF in CrCLR stifles as compared with the control. Collagens were also significantly increased in CrCLR stifles. TPA was not significantly different; however, the AMA angle significantly increased in the CrCLR group. Our results suggest a possible relationship between PB and SF levels of inflammatory markers in CrCLR stifles of dogs.

Preoperative planning using computed tomography in tibial plateau levelling osteotomy: A comparison with conventional radiography

Background

Tibial plateau levelling osteotomy (TPLO) is currently one of the most common surgical procedures for the correction of the stifle joint with a ruptured cranial cruciate ligament. TPLO is based on the preoperative tibial plateau angle (TPA); therefore, it is essential to optimise the consistency and repeatability of TPA measurements.

Objectives

This study aims to compare computed tomography (CT) with conventional radiography in the preoperative planning of TPLO.

Methods

This prospective study included six dogs (12 hindlimbs) and 13 canine cadaveric hindlimbs. In the six beagle dogs, TPAs were measured by three radiologists using digital radiographic and CT images to evaluate the intra‐ and inter‐observer agreement. To evaluate the intra‐observer agreement of the TPA before and after surgery, and the intended angle of the postoperative TPA according to the preoperative planning method, 13 cadaveric hindlimbs were evaluated thrice at random by a single radiologist.

Results

The intra‐ and inter‐observer intraclass correlation coefficients (ICCs) of the CT method were higher than those of the radiographic method in normal beagle dogs. The intra‐observer ICC of the CT method before and after TPLO was generally higher than that of the radiographic method in the cadaver. However, no significant difference was noted in the evaluation of the intended postoperative TPA according to the preoperative planning method.

Conclusions

The intra‐ and inter‐observer ICCs allowed for easy identification of landmarks required to consistently determine the TPA in the preoperative planning of TPLO based on CT images.

Proximodistal and caudocranial position of the insertion of the patellar ligament on the tibial tuberosity and patellar ligament length of normal stifles and stifles with grade II medial patellar luxation in small-breed dogs

OBJECTIVE

To assess the role of the proximodistal and caudocranial relative position of the patellar ligament insertion on the tibia and patellar ligament length-to-patellar length ratio (PLL:PL) in small-breed dogs with and without grade II medial patellar luxation (MPL).

STUDY DESIGN

Retrospective study.

SAMPLE POPULATION

Dogs weighing ≤15 kg, including 43 stifles with MPL and 34 control stifles.

METHODS

The proximodistal and caudocranial relative position of the patellar ligament insertion was determined as a ratio using the vertical (VTT) and horizontal distance (HTT) between the tibial tuberosity insertion and the tibial plateau divided by the tibial plateau length (TPL). In addition, PLL:PL and tibial plateau angle (TPA) were determined.

RESULTS

The VTT:TPL ratio was lower in affected stifles (95% CI: 0.86-0.94) than in the control group (0.93-1.01; p = .01). No other difference was identified between affected and normal stifles.

CONCLUSION

The only difference identified in this study consisted of a more proximal position of the patellar ligament insertion in the stifles of small-breed dogs with grade II MPL.

CLINICAL SIGNIFICANCE

The more proximal position of the patellar ligament insertion will result in a more proximal position of the patella in the trochlear groove and may contribute to the development of MPL. Potentially, this will also affect the risk of recurrence of MPL after surgical treatment.

Locking compression plates versus locking plates for tibial plateau levelling osteotomy in dogs: progression of osteoarthritis, bone healing score and lameness degree

BACKGROUND

The partial or complete cranial cruciate ligament rupture is a common skeletal disease affecting the stifle joint in dogs. The tibial plateau levelling osteotomy, performed with several synthesis systems, changed the approach to its treatment in dogs. The aim of this study was to compare two types of fixation implants, locking compression system and locking system, evaluating radiographically the progression of osteoarthritis of the stifle joint in dogs with complete cranial cruciate ligament deficiency treated surgically with tibial plateau levelling osteotomy. Moreover, we evaluated bone healing and lameness scores to show biomechanical effects by the implant used. Twenty-eight dogs, who met the inclusion criteria, were divided into two groups. Group A: 14 dogs treated using locking compression plates; Group B: 14 dogs treated using locking plates. Radiographic osteoarthritis scores were evaluated up to 1 year following tibial plateau levelling osteotomy. At each visit, animals were clinically and radiographically assessed. Each dog was evaluated before (T0) and after two (T2) and twelve (T12) months after the surgery. At T2 the stage of bone healing was evaluated. The clinical follow up was performed before the surgery and at 10, 15 and 20 days after the surgery, grading the lameness at walk and trot.

RESULTS

An increase in osteoarthritis score at T12 versus T0 in both groups was detected. A decrease of the lameness score was observed in Group A versus Group B. The healing score system at T2 showed a lower score in Group A versus Group B.

CONCLUSIONS

The osteoarthritis score following tibial plateau levelling osteotomy did not differ when comparing the two different fixation systems. The locking compression system allowed a more rapid functional recovery of the limb and a quicker bone healing than the locking system. Locking compression system should be carefully considered for dogs subjected to tibial plateau levelling osteotomy surgery, because it may reduce the recovery time.

Tibial plateau levelling osteotomy using a dome-shaped saw blade for canine cranial cruciate ligament insufficiency

BACKGROUND

Tibial plateau levelling osteotomy (TPLO) is commonly used to manage cranial cruciate ligament (CrCL) disease. The use of a spherical osteotomy blade (S-TPLO) enables correction of some tibial deformities with three rotational degrees of freedom.

METHODS

As a proof of concept, this retrospective study included 45 dogs with CrCL disease that were treated with an S-TPLO. The tibial plateau angle (TPA) was measured preoperatively, immediately after surgery (pTPA₀ ) and on postoperative days 42 (pTPA₄₂ ) and 56 (pTPA₅₆ ). Lameness and osteotomy healing were assessed until 56 days postoperatively.

RESULTS

Thirty-one dogs had complete CrCL ruptures, and 14 dogs had partial ruptures. Thirty-one dogs had medial meniscal damage. The mean TPA, pTPA₀ , pTPA₄₂ and pTPA₅₆ were 26.0°, 7.8°, 8.5° and 8.9°, respectively. The TPA from post-op to follow-up did not vary significantly (p > 1.365). Minor complications occurred in five dogs. The mean lameness score improved significantly from 3.2 preoperatively to 0.9 on day 56 (p < 0.0001). The mean healing score improved significantly from 1.6 on day 42 to 2.2 on day 56 (p < 0.001).

CONCLUSION

S-TPLO was successful in treating CrCL disease in stifle joints without tibial deformities, with results comparable to previously reported TPLO outcomes.

Geometric modelling of CORA-based levelling osteotomy in the dog

Centre of rotation of angulation (CORA)-based levelling osteotomy (CBLO) is a recent addition to surgical procedures for stabilization of the cranial cruciate ligament-deficient canine stifle joint. Careful identification of the CORA location preoperatively and use of this location intraoperatively are required to ensure accurate correction of the tibial plateau angle. Limited data are available regarding the magnitude and source of potential errors during planning and execution of CBLO. A geometric model enabling isolation of various error sources is described. Landmarks were derived from tibial radiographs (n = 50) by 5 observers and used to define proximal and distal anatomical axes for simulation of CBLO. Observer-specific CORA locations with mean landmark data were used to assess planning errors, and simulated malpositioning of the CORA at 10 mm from the ideal location was used to assess surgical errors. Planning errors result mainly from tibial plateau misidentification, with CORA locations dispersed up to ±10 mm proximodistally from ideal (95% confidence). Malpositioning of the CORA during surgery causes equal and opposite changes in tibial plateau angle (TPA) and anatomical-mechanical axis angles, and varying degrees of translation and limb length changes. The magnitude of these changes is dependent on initial TPA and limb length, with smaller dogs and steeper tibial plateaus resulting in larger errors. Optimal planning and execution are required to achieve the planned outcome of CBLO. The main source of error in our simulation is identification of the tibial plateau. While both pre- and intraoperative errors influenced TPA, based on our geometric model the effect in larger dogs may not be clinically significant. If distalisation of the CORA is required during surgery, compensation of the CORA angle to maintain the target TPA is possible.

Measurement of the tibial plateau angle of normal small-breed dogs and the application of the tibial plateau angle in cranial cruciate ligament rupture

Objective:

In Korea, small dogs are more common than large breeds. This study was performed to measure the influence of body weight, sex, breed, age, and cranial cruciate ligament rupture (RCCL) on the tibial plateau angle (TPA) in small-breed dogs.

Materials and methods:

A total of 274 dogs (221 normal dogs and 53 RCCL dogs) were selected for this study based on medical records. The TPA was measured from stifle joint radiographs. The dogs were divided according to body weight, sex (male and female; normal and neutered), age, breed, and RCCL, and the TPAs of the dogs were compared.

Results:

In general, the TPAs of male dogs were significantly (p < 0.05) higher than those of female dogs, and those of healthy neutered dogs were higher than those of healthy intact dogs. The TPA had a tendency to increase along with the animal’s age but was not significantly different among the four age groups. In general, the TPA of RCCL dogs was 27.12° ± 0.62°, which was significantly higher (p < 0.001) than that of normal dogs (20.21° ± 0.32°), indicating that an increased TPA is associated with a higher risk for RCCL. Similar results were also observed among dogs with similar body weights, breeds, and ages for male and female RCCL dogs.

Conclusion:

This study suggested that the sex and neutering status of dogs could affect the TPA. This study also confirmed the use of TPA in the veterinary clinic as a possible indicator of RCCL, as the TPA is higher in RCCL dogs than in normal dogs.

Preoperative planning for tibial plateau leveling osteotomy based on proximal tibial width

The purpose of this study was to evaluate the applicability and feasibility of a novel preoperative planning method for tibial plateau leveling osteotomy (TPLO) based on the width of the proximal tibia. All TPLO procedures were performed by the same surgeon. In preoperative planning, the width of the tibial crest to the caudal edge of the medial tibial plateau (W) was measured, and the saw blade size that was closest to the distance between the point of the cranial third W and the intercondylar tubercles was selected. The postoperative tibial plateau angle (TPA), distance of eccentricity (DOE), and minimum thickness of the tibial tuberosity remaining cranial to the osteotomy (tibial tuberosity width; TTW) were documented. Complications in the perioperative and follow-up periods were documented. Thirty-one TPLO procedures were performed in 28 dogs, including both small and large breeds. The postoperative TPA was 8.4 ± 2.0° and the DOE was 3.55 ± 2.88 mm. The ratio of the TTW to the preoperative W was 0.27 ± 0.06. There were no major complications, such as fractures of the tibial tuberosity or implant breakage. This preoperative planning method allowed appropriate planning for TPLO with a clear index that was based on the size of the tibia rather than the breed or weight of the dog. This method should be of benefit to the surgeon, whether an expert or a novice, and contribute to the success of TPLO.

Association of meniscal injury to joint space width on standard tibial plateau leveling osteotomy lateral radiographic projections of the canine stifle

Up to 70% of dogs with cranial cruciate ligament tears have concurrent meniscal injury, and these injuries can increase the risk of developing osteoarthritis and persistent lameness. Studies assessing joint space width on knee radiographs in people have indicated associations between joint space width and meniscal injuries. The aim of this prospective analytical study was to determine if there was an association between stifle joint space width on three different radiographic projections (the standard tibial plateau leveling osteotomy projections and a standing lateral projection) and meniscal injuries identified at surgery in dogs. There was a significant association between dogs with a meniscal tear and the corresponding joint space width on standard tibial plateau leveling osteotomy lateral radiographic projections (P-value = .0028). Based on receiver operator characteristic curve analysis, joint space widths measuring less than 3.43 mm may indicate a meniscal tear, with a corresponding 89.5% specificity and 40.5% sensitivity in dogs weighing 31 kg. Joint space narrowing is seen with meniscal tears in dogs, and radiography may be a noninvasive way to identify meniscal tears prior to surgery.

Modified Triple Tibial Osteotomy for Combined Cranial Cruciate Ligament Rupture, Tibial Deformities, or Patellar Luxation

Proximal tibial deformities or patellar luxation may occur concurrently with cranial cruciate ligament rupture. The objective of this study was to describe the management of those conditions with a modified triple tibial osteotomy (TTO) in nine dogs. Medical records of dogs who underwent a modified TTO were reviewed. The mean pre- and postoperative patellar tendon angles were 104.2° and 92.9°, respectively. The mean pre- and postoperative mechanical medial proximal tibial angles were 99.5° and 91.5°, respectively. Medial patellar luxation was present in five dogs (55.6%) and treated in all five dogs with a tibial crest transposition. Tibial torsion was grossly resolved in two dogs (22.2%). Perioperative distal tibial crest fracture was treated by pins and a figure-of-eight tension-band wire in five dogs (55.6%). One major (surgical site infection) and three minor postoperative complications were observed. At the last follow-up, seven dogs (77.8%) had no lameness, one dog (11.1%) had mild lameness, and one dog (11.1%) had moderate lameness. Radiographic evaluation showed good (2/9; 22.2%) to excellent (7/9; 77.8%) bone healing. The visual analog scale evaluation revealed good-to-excellent owner satisfaction. Cranial cruciate ligament rupture, tibial deformities, and medial patellar luxation are difficult to treat together. A modified TTO may be used to treat these conditions.

Contribution of antirotational pins and an intact fibula to the ex vivo compressive strength of four tibial plateau leveling osteotomy constructs

OBJECTIVE To assess the contribution of antirotational pins (ARPs) and an intact fibula to the compressive strength of 4 tibial plateau leveling osteotomy (TPLO) constructs (bone and implants). SAMPLE 20 hind limbs from 10 canine cadavers. PROCEDURES Each hind limb was assigned to 1 of 4 TPLO constructs (construct in which the ARP was removed, constructs in which 1 or 2 ARPs were left in place, and construct in which the ARP was removed and the fibula was cut). Following TPLO completion, all limbs underwent mechanical testing that included 10,000 cycles of cyclic axial compression followed by testing to failure at a displacement rate of 1 mm/s. Displacement during cyclic testing; load generated at 0.5, 1.0, and 3.0 mm of displacement; ultimate load; and failure type were recorded for each limb. Mean values were compared among the groups. RESULTS None of the specimens failed during cyclic testing. None of the variables assessed during mechanical testing differed significantly among the 4 groups. During testing to failure, the majority (17/20) of specimens failed as the result of a long oblique fracture through the first screw hole in the distal segment. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that the axial compressive strength and stiffness of a TPLO construct were not significantly affected by the addition of 1 or 2 ARPs or the presence of an intact fibula. These findings appear to support removal of ARPs during uncomplicated TPLOs, but further research is warranted to assess the effect of ARP removal on bone healing and complication rates.

Measurement of the patellar tendon-tibial plateau angle and tuberosity advancement in dogs with cranial cruciate ligament rupture

Objectives: To (i) compare agreement of the common tangent (CT) and tibial plateau angle (TP) methods in terms of measuring the patellar tendon angle (PTA) and required advancement and (ii) determine the intraand inter-observer reliability of observers who measured PTA and the advancement.

Methods: Six observers were divided into three groups based on their level of experience. They measured the PTA and the required advancement on 43 radiographic images of the tibiae of dogs affected by cranial cruciate ligament rupture. Each observer repeated the measurements three times with each method. The inter-technique (interT), intra-observer (intraO), and interobserver (interO) reliabilities were evaluated, assessed by calculating the intraclass correlation coefficient (ICC), and represented by Jones plots.

Results: The agreement between PTA-CT and PTA-TP was low (the ICC interT values ranged from 0.11 to 0.4). The PTA-CT was associated with moderate intra-observer reliability (ICC intraO, CT = 0.61) and poor interobserver reliability (ICC interO, CT = 0.33). The PTA-TP was associated with good intra-observer reliability (ICC intraO, TP = 0.75) and moderate interobserver reliability (ICC interO, TP = 0.59). Interobserver reliability did not depend on the level of experience. The advancement measurements were associated with reliability results similar to those obtained for PTA. Jones’ plots showed that the CT method consistently yielded lower PTA and advancement values than the TP method.

Conclusion: Given its poor reliability, the CT method is not recommended.

Estudo comparativo entre métodos manual e digital no cálculo do ângulo do platô tibial em cães

RESUMO São poucos os dados publicados sobre a aplicabilidade ou a confiabilidade dos métodos digitais para mensuração do ângulo do platô tibial (APT) em comparação à mensuração manual. O objetivo deste estudo foi comparar o APT obtido pelo cálculo manual padrão, em filmes radiográficos, com os valores obtidos por cálculos em imagens digitais, por meio do software do computador. Foram analisadas radiografias digitais do membro pélvico, direito e esquerdo, em perfil verdadeiro, de 20 cães saudáveis, com idade superior a um ano. Três observadores com graus de experiência semelhantes em cálculo do APT realizaram as mensurações em cada radiografia. Primeiramente, foram calculados os ângulos dos platôs tibiais manualmente nas películas radiográficas e, posteriormente, os cálculos foram realizados na imagem digital, por meio do software para medicina veterinária do sistema de raios X digital. Os resultados do presente estudo demonstraram diferenças significativas entre os métodos, com valor das médias do cálculo digital 20,48±3.71 e do cálculo manual 23.90±4.02. Valor de P foi < 0,01 na comparação entre médias dos dois grupos. Na avaliação interobservadores, houve diferença significativa no cálculo manual no perfil direito, o que sugere maior variação no cálculo manual quando comparado ao digital. O cálculo realizado pelo software apresentou menor variação nos valores interobservadores. Acredita-se que a menor variação obtida nos resultados aqui apresentados se dê em razão das facilidades proporcionadas pelo software. Conclui-se que houve diferença entre os valores obtidos por meio dos métodos convencional e digital no cálculo do ângulo do platô tibial, sendo os valores digitais menores entre os observadores, e que o método digital no cálculo do ângulo do platô tibial levou à menor variação quando comparado ao método manual.

Tibial plateau levelling osteotomy in 69 small breed dogs using conically coupled 1.9/2.5 mm locking plates

Objective: To report clinical experiences with the tibial plateau levelling osteotomy (TPLO) procedure in small breed dogs with cranial cruciate ligament (CCL) disease using specific, conically coupled, 1.9/2.5 mm locking plates and evaluating short-term complications and outcome.

Methods: Medical records of small breed dogs (<15 kg) that underwent TPLO using 1.9/2.5 mm locking plates were reviewed retrospectively. The preoperative, postoperative and six to eight weeks postoperative tibial plateau angle (TPA) measurements were determined from the radiographic images. Lameness evaluation was assessed subjectively preoperatively and six to eight weeks postoperatively.

Results: Sixty-nine small breed dogs (n = 79 stifles) were included in the study. Mean (± SD) preoperative TPA was 29.0 ± 3.4°, postoperative TPA was 5.8 ± 2.5°, and six to eight weeks postoperative TPA was 7.3 ± 4.1°. Sixteen complications occurred in 12 out of 79 TPLO procedures: three were intra-operative (intra-articular screw placement) and 13 were postoperative complications, of which nine were identified as minor complications not requiring surgical reintervention, and four as major complications requiring additional surgical intervention, including tibial tuberosity fracture (n = 1), osteomyelitis (n = 1), screw failure (n = 1), and plate breakage (n = 1). Lameness scores by clinical assessment reduced from a median value of 3/4 preoperatively to 1/4 at six to eight weeks postoperatively.

Clinical significance: 1.9/2.5 mm locking plates appear to be a valid choice of implant for the stabilization of unilateral TPLO in small breed dogs.

Effect of tibial subluxation on the measurements for tibial tuberosity advancement in dogs with cranial cruciate ligament deficiency

Objectives: The main objectives were to evaluate the impact of femorotibial subluxation on the preoperative measurements for tibial tuberosity advancement (TTA) by defining radiographic landmarks and testing the repeatability for assessing cranial tibial subluxation (CTS). Also, we aimed at developing a formula to calculate the necessary adjustment in measurement of TTA in stifles with CTS.

Methods: Forty stifles were used to examine the influence of CTS on preoperative TTA measurements before and after transection of the cranial cruciate ligament. Mediolateral radiographs were obtained and measurements performed by three investigators. The observed variabilities were assessed by interand intra-observer differences.

Results: Measurements of CTS and preoperative TTA showed a good to excellent interand intra-observer correlation. We found a significant influence of CTS on TTA measurements and developed a formula to calculate the necessary adjustment in measurement of TTA in stifles with CTS.

Conclusion: We found a correlation between the tibial subluxation and the measurements for TTA, with the latter decreasing with increasing subluxation. This has to be taken into account when measuring the advancement in stifles with complete rupture of the cranial cruciate ligament. We provided a formula to calculate the necessary addition to the measured advancement.

Accuracy of a radiographic stitching technique to measure tibial plateau angle in large and giant breed dogs

Objective: To determine if a novel radiographic stitching technique yields accurate tibial plateau angle (TPA) measurements in large and giant breed dogs.

Methods: Three medio-lateral digital radiographic projections (traditional TPLO, stiflecentred, tarsus-centred) were obtained from each of 17 pairs of pelvic limbs from skeletally mature large and giant breed dogs. Eight observers performed image stitching followed by TPA measurements on the stitched (sTPA) and traditional radiographs (tTPA). The TPA was also measured on photographs made of isolated anatomical tibial specimens (aTPA). Measurements were compared between observers and between image type using ANOVA and correlation coefficients.

Results: There was no statistically significant difference in TPA between observers for tTPA or sTPA radiographs (p >0.05); both sTPA and tTPA were highly correlated with aTPA and with each other (r = 0.88, 0.89, and 0.97 respectively).

Clinical relevance: This novel digital stitching method provides an alternative technique for accurately measuring TPA utilizing a stifle-centred radiograph that may be useful when traditional TPLO radiographs are difficult to obtain. This may be particularly useful in large and giant breed dogs because collimation to include the entire tibial length can preclude proper centring of the radiographic beam over the stifle.

Evaluation of vascular trauma after tibial plateau levelling osteotomy with or without gauze protection

Objective: To evaluate the integrity of the cranial tibial artery after performing the tibial plateau levelling osteotomy (TPLO) with or without soft tissue dissection and protection with gauze sponges.

Study design: Experimental cadaveric study.

Animals: Ten dogs weighing 28 to 35 kg.

Methods: Ten pairs of normal pelvic limbs were divided randomly into two groups in which a TPLO was performed with or without soft tissue protection with gauze sponges respectively. Angiography was used to evaluate the integrity of the cranial tibial artery after TPLO in each group. Contrast angiography was performed for each group: 1) before TPLO [Control] 2) after TPLO [Osteotomy] and 3) after intentional laceration of the cranial tibial artery [Arteriotomy]. A ‘yes or no’ was used to score contrast extravasation. The area of extravasated contrast was also calculated on the radiographs. A Mann-Whitney test and an ANOVA with repeated measures were completed to assess the score and the area, respectively, for each of the surgical treatments (Control, Osteotomy, and Arteriotomy) between the conditions of dissection with respect to the cranial tibial artery. A value of p <0.05 was considered significant.

Results: The differences between the two groups (with and without protection) for scores and areas of leakage were not significant (p >0.05). However, significant differences were noted between Control and Arteriotomy (p <0.01) and Osteotomy and Arteriotomy (p <0.01), but not between Control and Osteotomy (p >0.05).

Conclusions and clinical relevance: A TPLO without protection of the cranial tibial artery can be performed without increased risk of arterial trauma.

Comparison of radiographic measurements of the patellar tendon-tibial plateau angle with anatomical measurements in dogs

Objective: To evaluate the validity of the common tangent and conventional tibial plateau angle methods for measuring the patellar tendon angle (PTA) in dogs.

Methods: Radiographs of cadaveric stifles (n = 20) placed at 135° in true lateral position were obtained to measure the PTA with both methods. A Kirschner wire was inserted perpendicularly to the patellar tendon at its insertion on the tibia and the stifle was dissected. Two Kirschner wires were then used to identify the anatomical landmarks of the tibial plateau. A digital image was obtained of the proximal tibia in true lateral position. Six blinded observers measured each PTA digitally while the anatomical PTA was determined by an independent blinded observer from the angle between the line representing the tibial plateau and the Kirschner wire representing the perpendicular to the patellar tendon. The agreement between the methods was determined statistically from an intraclass correlation coefficient (ICC).

Results: The global ICC for the common tangent method (0.44) and for the conventional method (0.4) indicated that their overall validity is poor. The measurements obtained by common tangent method and conventional method were respectively below and above the anatomical measurements. The reproducibility of the PTA measurements based on images of the dissected stifles was very good.

Clinical significance: Both the common tangent and conventional methods show poor concordance with the anatomical measurement of PTA. Further studies are needed to determine if errors in measurements affect the clinical outcome.

Effect of stifle angle on the magnitude of the tibial plateau angle measurement in dogs with intact and transected cranial cruciate ligament

Objective: To determine the effect of stifle angle on the magnitude of the radiographic tibial plateau angle (TPA) in normal and cranial cruciate ligament (CCL) -deficient stifles.

Methods: Three pairs of canine cadaver hind-limbs from three skeletally mature dogs were positioned in a custom-made positioning device. A lateral radiograph of each specimen was obtained before and after transection of the CCL at four stifle angles (90°, 110°, 135° and 140–150° [i.e. maximum extension]), based on goniometric measurements. Four observers determined the radiographic TPA twice for each radiograph with a minimum of two days between each measurement. The radiographic TPA measurements in all specimens at different stifle angles with intact CCL and transected CCL were compared with mixed-model ANOVA. The effect of stifle angle, CCL transection, and interaction between the two on observer TPA measurement variability was also determined using the coefficient of variation.

Results: Tibial plateau angle was not statistically different in the stifle angles for either the intact or transected CCL. There was also no statistical difference for TPA between intact and transected CCL groups at each of the stifle angles. Stifle angle, CCL transection and interaction between the two did not have any significant effect for intra-observer and inter-observer variation.

Clinical significance: The angle of the stifle during radiography does not influence the magnitude of the TPA measurement as determined on true lateral radiographs of the stifle and tibia in cadaveric canine limbs.

Variation of tibial plateau geometry and cruciate ligament coordinates in six breeds of dogs

Objectives: The first aim of this study was to examine whether or not variations concerning the conformational characteristics of the proximal surface of the tibial plateau exist among six different dog breeds as well as within the same breed. The second aim of this study was to determine the coordinates of the cruciate ligaments.

Methods: One hundred and four tibias of 52 mature dogs from six different breeds were used. Photographs of the proximal surface of tibial plateau were taken, and measurements for the length, width and area of the tibial plateau, and the lateral and medial condyles were taken. In addition, the intercondylar width, height of Gerdy's tubercle, popliteal notch depth, and extensor groove depth were measured and recorded. The quotients from these measurements were calculated and compared amongst the dog breeds. The coordinates of the cruciate ligaments, according to the centre of tibial plateau, were also determined.

Results: Based on the calculated quotients, variations in the geometry of the tibial plateau geometry were common among the breeds. Within the same breed, on the other hand, length and width measurements of the tibial plateau were the least variable parameters among the other parameters examined. The cranial cruciate ligament was located in front of the surface centre of tibial plateau in all breeds. The position of cranial cruciate ligament was more variable in the craniocaudal direction than that observed in the mediolateral direction; this was the exact opposite of caudal cruciate ligament.

Clinical significance: The inter-breed variations of the quotients determined in the present study may facilitate attempts aimed to assess the risk factors of stifle joint injury and to design total knee prostheses.

Modification of the cranial closing wedge ostectomy technique for the treatment of canine cruciate disease

Objective: To describe a modification of the cranial closing wedge ostectomy (CCWO) technique and to compare its efficacy to the standard technique on cadaveric specimens.

Methods: The standard and modified CCWO technique were applied to eight pairs of cadaveric tibiae. The following parameters were compared following the ostectomy: degrees of plateau levelling achieved (degrees), tibial long axis shift (degrees), reduction in tibial length (mm), area of bone wedge removed (cm2), and the area of proximal fragment (cm2).

Results: The size of the removed wedge of bone and the reduction in tibial length were significantly less with the modified CCWO technique.

Clinical significance: The modified CCWO has two main advantages. Firstly a smaller wedge is removed, allowing a greater preservation of bone stock in the proximal tibia, which is advantageous for implant placement. Secondly, the tibia is shortened to a lesser degree, which might reduce the risk of recurvatum, fibular fracture and patella desmitis. These factors are particularly propitious for the application of this technique to Terrier breeds with excessive tibial plateau angle, where large angular corrections are required. The modified CCWO is equally effective for plateau levelling and results in an equivalent tibial long-axis shift. A disadvantage with the modified technique is that not all of the cross sectional area of the distal fragment contributes to load sharing at the osteotomy.

Influência do posicionamento radiográfico no cálculo interobservador do ângulo do platô tibial em cães

RESUMO O objetivo deste trabalho foi demonstrar que o posicionamento radiográfico inadequado do membro pélvico de cães (imagens obliquadas) afeta a mensuração do ângulo do platô tibial (APT), levando à maior variação entre observadores. Foram realizadas duas projeções radiográficas nos membros pélvicos direito e esquerdo, uma em perfil verdadeiro e a outra com o membro obliquado em 21 cães provenientes do atendimento clínico cirúrgico do Hospital Veterinário da Universidade de Cuiabá, em Cuiabá-MT. Os critérios de inclusão foram cães livres de histórico ou afecção ortopédica nos membros pélvicos, pesando entre 15 e 40 quilos, sem predileção por raça ou sexo, entre dois e sete anos de idade. Foram obtidas 42 imagens radiográficas em perfil verdadeiro e 42 imagens radiográficas obliquadas. Três observadores com experiência em cálculo do APT fizeram as mensurações. Nos cálculos das imagens em perfil verdadeiro, o observador 1 obteve uma média de 23,35º ± 2,82; o observador 2, média de 23,88º ± 4,83; e o observador 3, média de 24,54º ± 4,01, não sendo encontrada diferença significativa entre o cálculo dos três avaliadores, P=0,944 (P > 0,05), nas imagens em perfil verdadeiro. Nos cálculos das imagens obliquadas, o observador 1 obteve uma média de 21,69º ± 4,22; o observador 2, média de 19,42º ± 5,92; e o observador 3, média de 22,64º ± 5,23, e foi encontrada diferença significativa entre o cálculo dos três observadores, P=0,016 (P < 0,05). Com esses dados, pôde-se demonstrar que a imagem radiográfica obliquada compromete o valor final do cálculo do ângulo do platô tibial em cães, levando à variação numérica estatisticamente significativa entre observadores. Conclui-se, assim, que um posicionamento correto do membro pélvico, em perfil verdadeiro, deve ser sempre utilizado para a obtenção de imagens, com o objetivo de mensurar o valor do APT.

A novel jig arm to measure tibial plateau angle during tibial plateau leveling osteotomy

OBJECTIVE

To determine the ability of a novel device attached to the proximal tibial plateau leveling osteotomy (TPLO) jig pin to accurately predict intraoperative change in tibial plateau angle (TPA).

STUDY DESIGN

In vitro cadaveric study.

SAMPLE POPULATION

Left hindlimbs of adult dogs (n = 9).

METHODS

A modified Slocum tibial plateau leveling (TPL) jig with the Rotational Osteotomy Measuring Arm (ROMA) was placed on the tibia and a radial TPLO osteotomy was performed. Based on preoperative radiographic TPA measurements, the proximal segment was rotated using the traditional method of marking points on the osteotomy a specified distance apart. After rotation, the predicted TPA was recorded based on the ROMA. Postoperative TPA was measured on radiographs. The ability of the ROMA to predict postoperative TPA was compared to that of the traditional method.

RESULTS

The average final TPA achieved with the traditional method was 6.4° (range, 3.0-10.0°). The ROMA predicted a final TPA of 5.8° (range, 3.8-10.1°). No significant difference was found between the TPA predicted based on the traditional method and ROMA method.

CONCLUSION

The ROMA may be an alternative to the traditional method of measuring proximal segment rotation during TPLO procedure.

CLINICAL RELEVANCE

Performing a TPLO with the ROMA may accurately predict the postoperative TPA while eliminating the need for measuring chord length, making reference marks, or referencing TPA charts for various osteotomy blade sizes.

Factors contributing to the variability of a predictive score for cranial cruciate ligament deficiency in Labrador Retrievers

Background

We recently reported that a conformation score derived from the tibial plateau angle (TPA) and the femoral anteversion angle (FAA), best discriminates limbs predisposed to, or affected by cranial cruciate ligament disease (CCLD), from those that are at low risk for CCLD. The specificity and sensitivity of this score were high enough to support further investigations toward its use for large-scale screening of dogs by veterinarians. The next step, which is the objective of the current study, is to determine inter-observer variability of that CCLD score in a large population of Labrador Retrievers. A total of 167 Labradors were enrolled in this cross-sectional study. Limbs of normal dogs over 6 years of age with no history of CCLD were considered at low risk for CCLD. Limbs of dogs with CCLD were considered at high risk for CCLD. Tibial plateau and femoral anteversion angles were measured independently by two investigators to calculate a CCLD score for each limb. Kappa statistics were used to determine the extent of agreement between investigators. Pearson’s correlation and intraclass coefficients were calculated to evaluate the correlation between investigators and the relative contribution of each measurement to the variability of the CCLD score.

Results

The correlation between CCLD scores calculated by investigators was good (correlation coefficient = 0.68 p < 0.0001). However, interobserver agreement with regards to the predicted status of limbs was fair (kappa value = 0.28), with 37% of limbs being assigned divergent classifications. Variations in CCLD scores correlated best with those of TPA, which was the least consistent parameter between investigators. Absolute interobserver differences were two times greater for FAAs (4.19° ± 3.15) than TPAs (2.23° ± 1.91).

Conclusions

The reproducibility of the CCLD score between investigators is fair, justifying caution when interpreting individual scores. Future studies should focus on improving the reproducibility of TPA and FAA measurements, as strategies to improve the agreement between CCLD scores.

Comparison of tibial anatomical-mechanical axis angle between predisposed dogs and dogs at low risk for cranial cruciate ligament rupture

The purpose of this prospective, radiographic, descriptive study was to compare measurements of tibial anatomical-mechanical axis angle (AMA-angle), tibial plateau angle (TPA), relative tibial tuberosity width (rTTW) and Z-angle from mediolateral radiographs of the tibia between two canine breeds (72 dogs) not predisposed to cranial cruciate ligament rupture (CCLR) and those from a consecutive series of 185 large dogs and 17 West Highland white terriers (WHWT) diagnosed with unilateral, surgically confirmed CCLR. Correlations among these measurements were determined, and levels of inter- and intra-observer variability among and within three observers for each measurement were established using Kendall's coefficient of concordance. Breed had a significant effect on AMA-angle. The median AMA-angle of the subject population of large dogs affected by CCLR was 2.80° (range 1.09°-5.21°); for the WHWT, it was 6.34° (range 5.68°-8.88°); and for the clinically normal dogs, it was 0.74° (range 0.00°-5.40°). In the CCLR group, AMA-angle and TPA were strongly correlated (r=0.745; p<0.0001). A receiver operating characteristic (ROC) curve analysis showed that an AMA-angle higher than 1.87° had a sensitivity of 0.941 (95% confidence interval [CI]: 0.898-0.966) and a specificity of 0.965 (95% CI: 0.919-0.987) for predicting CCLR and was more accurate than TPA, rTTW and Z-angle at predicting CCLR (p<0.0001). Good inter- and intra-observer agreement was found for all measurements. The highly significant difference in AMA-angle found between clinically normal dogs and dogs with CCL injury suggests that AMA-angle magnitude may be a clinically relevant predisposing factor for the development of canine CCLR.

Evaluation of a new method to determine the tibial tuberosity advancement distance required to reduce the patellar tendon-tibial plateau angle to 90° with the modified Maquet technique in dogs

OBJECTIVE To assess use of a new radiographic method to determine the distance by which the tibial tuberosity should be advanced to reduce the patellar tendon-tibial plateau angle (PTA) to 90° by means of the modified Maquet technique (MMT) in dogs. SAMPLE 24 pelvic limbs from 12 adult medium-sized to large-breed canine cadavers. PROCEDURES Radiographs of stifle joints at 135° extension in true lateral position were used to determine tibial tuberosity advancement distances for use in the MMT. A method was devised to incorporate the planned osteotomy axis; distal patellar translations of 0, 3, 5, or 10 mm; and advancement cage implant application level along the osteotomy site in advancement planning measurements. Concordance correlation coefficients (CCCs) were calculated to compare these adjusted advancement measurements with true advancement measurements obtained for the same joints in another study after treatment by MMT. Intraobserver, interobserver, and total agreement for selected measurements were determined by assessment of CCCs for results obtained by 3 blinded observers. RESULTS Agreement between true advancement measurements and measurements obtained with osteotomy axis and cage position method calculations that incorporated a 5-mm distal patellar translation distance was excellent (CCC, 0.96). Intraobserver and interobserver agreements for the planning measurements evaluated were good to excellent (CCC, 0.83 to 0.96). CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that the osteotomy axis and cage position method incorporating a 5-mm distal patellar translation distance has the potential to improve success rates for achieving a PTA of 90° in medium-sized to large-breed dogs undergoing MMT for treatment of cranial cruciate ligament rupture. Further research is warranted.

Effect of proximal translation of the osteotomized tibial tuberosity during tibial tuberosity advancement on patellar position and patellar ligament angle

Background

Cranial cruciate ligament insufficiency is a common orthopaedic problem in canine patients. This cadaveric and radiographic study was performed with the aim of determining the effect of proximal translation of the tibial tuberosity during tibial tuberosity advancement (TTA) on patellar position (PP) and patellar ligament angle (PLA).

Results

Disarticulated left hind limb specimens harvested from medium to large breed canine cadavers (n = 6) were used for this study. Limbs were mounted to Plexiglass sheets with the stifle joint fixed in 135° of extension. The quadriceps mechanism was mimicked using an elastic band. Medio-lateral radiographs were obtained pre-osteotomy, after performing TTA without proximal translation of the tibial tuberosity, and after proximal translation of the tibial tuberosity by 3mm and 6mm. Radiographs were blinded to the observer for distance of tibial tuberosity proximalization following radiograph acquisition. Three independent observers recorded PP and PLA (tibial plateau method and common tangent method). Comparisons were made between the stages of proximalization using repeated measures ANOVA. Patellar position was found to be significantly more distal than pre-osteotomy, if the tibial tuberosity was not translated proximally (P = 0.001) and if it was translated proximally by 3mm (P = 0.005). The difference between pre-osteotomy PP and 6mm proximalization was not significant. The PLA was significantly larger if the tibial tuberosity was not translated proximally compared to tibial tuberosity proximalization of 6mm using the tibial plateau and the common tangent methods (P = 0.006 and P = 0.015 respectively).

Conclusions

Proximalizing the tibial tuberosity during TTA helps in maintaining vertical position of the patella in the patellar groove. Proximalization of the tibial tuberosity reduces PLA when compared to TTA without tibial tuberosity proximalization.

Evaluation of a scoring system based on conformation factors to predict cranial cruciate ligament disease in Labrador Retrievers

OBJECTIVE

To determine the association of a radiographic score derived from tibial plateau angle (TPA) and femoral anteversion (FAA) with an outcome of cranial cruciate ligament deficiency (CCLD) in large dogs.

STUDY DESIGN

Cross-sectional study.

ANIMALS

167 Labrador Retrievers.

METHODS

Hind limbs of sound Labrador Retrievers over 6 years of age were considered at low risk for CCLD. Limbs were considered high risk for CCLD if they were affected or predisposed (sound contralateral limb in dogs with unilateral CCLD). The radiographic CCLD score was calculated for each limb. The TPA, FAA, and CCLD scores were compared between limbs of the same dog and between risk categories. A contingency table was used to evaluate the association of the CCLD score with the CCLD status of limbs.

RESULTS

TPA, FAA, and CCLD scores were greater in limbs categorized as high risk for CCLD than in normal limbs. The sensitivity and specificity of the CCLD score was 87% and 79%, respectively. The positive predictive value was 69% and the negative predictive value was 92%. Scores were similar between paired right and left limbs, but did not agree for predicted status in 14/106 dogs.

DISCUSSION

Our study supports an association between TPA, FAA, and CCLD in Labrador Retrievers. The negative predictive value of the CCLD score supports its application for screening dogs considered at low risk for CCLD. Positive CCLD scores should be interpreted with caution and the status of a dog may be undetermined if scores obtained on each limb disagree.

Comparison of desired radiographic advancement distance and true advancement distance required for patellar tendon-tibial plateau angle reduction to the ideal 90° in dogs by use of the modified Maquet technique

OBJECTIVE To evaluate the validity of 2 radiographic methods for measurement of the tibial tuberosity advancement distance required to achieve a reduction in patellar tendon-tibial plateau angle (PTA) to the ideal 90° in dogs by use of the modified Maquet technique (MMT). SAMPLE 24 stifle joints harvested from 12 canine cadavers. PROCEDURES Radiographs of stifle joints placed at 135° in the true lateral position were used to measure the required tibial tuberosity advancement distance with the conventional (A^M) and correction (A^E) methods. The MMT was used to successively advance the tibial crest to A^M and A^E. Postoperative PTA was measured on a mediolateral radiograph for each advancement measurement method. If none of the measurements were close to 90°, the advancement distance was modified until the PTA was equal to 90° within 0.1°, and the true advancement distance (TA) was measured. Results were used to determine the optimal commercially available size of cage implant that would be used in a clinical situation. RESULTS Median A^M and A^E were 10.6 mm and 11.5 mm, respectively. Mean PTAs for the conventional and correction methods were 93.4° and 92.3°, respectively, and differed significantly from 90°. Median TA was 13.5 mm. The A^M and A^E led to the same cage size recommendations as for TA for only 1 and 4 stifle joints, respectively. CONCLUSIONS AND CLINICAL RELEVANCE Both radiographic methods of measuring the distance required to advance the tibial tuberosity in dogs led to an under-reduction in postoperative PTA when the MMT was used. A new, more accurate radiographic method needs to be developed.

Tibial anatomy in normal small breed dogs including anisometry of various extracapsular stabilizing suture attachment sites

OBJECTIVES

To investigate proximal tibial anatomy and its influence on anisometry of extracapsular stabilizing sutures in small dog breeds.

MATERIALS AND METHODS

Mediolateral radiographs of the femora, stifles, and tibiae of 12 small breed dogs were acquired with the stifles positioned at various angles. Measurements taken included tibial plateau angle (TPA), diaphyseal: proximal tibial angle (DPA), patellar tendon angle (PTA), Z-angle, relative tibial tuberosity width (rTTW), and the distance between six combinations of two femoral and three tibial extra-capsular stabilizing suture (ECS) attachment sites. Theoretical strain through stifle range-of-motion was recorded.

RESULTS

The TPA (32° ± 5.8°), DPA (10.2° ± 7.3°), PTA (103.7° ± 6.2°), and Z-angle (70.4° ± 9.0°) were positively correlated with one another (R >0.7), but none were correlated with rTTW (0.93 ± 0.10). The F2-T1 combination of ECS attachment sites had lowest strain for nine stifles. The shortest attachment site separation was at a stifle flexion of 50° for nine stifles. Proximal tibial anatomy measurements could not predict optimal attachment site combination, optimal stifle angle for suture placement, or ECS strain.

CLINICAL SIGNIFICANCE

There is individual variation in the optimal attachment site combination and stifle angle for suture placement, which may influence consistency of outcomes with ECS.

Preactivation of the quadriceps muscle could limit cranial tibial translation in a cranial cruciate ligament deficient canine stifle

Cranial cruciate ligament (CrCL) deficiency is the leading cause of lameness of the canine stifle. Application of tension in the quadriceps muscle could trigger cranial tibial translation in case of CrCL rupture. We replaced the quadriceps muscle and the gastrocnemius muscle by load cells and turn-buckles. First, eight canine limbs were placed in a servo-hydraulic testing machine, which applied 50% of body weight (BW). In a second phase, the CrCL was transected, and the limbs were tested in a similar manner. In a third phase, a quadriceps pretension of 15% BW was applied and limbs were again tested in a similar manner. Cranial tibial translation was significantly decreased in CrCL deficient stifles (p < 0.05) when quadriceps pretension was applied. These findings indicate that quadriceps pretension could play a role in the stability of a CrCL deficient stifle and should then be considered in rehabilitation programs and conservative treatment of CrCL rupture in dogs.

Short-Term Complications Associated With TPLO in Dogs Using 2.0 and 2.7 mm Plates

The purpose of this study was to evaluate short-term complications associated with the tibial plateau leveling osteotomy (TPLO) procedure in dogs of small and medium sizes. These study findings could then be compared with similar studies in dogs of all sizes. Ninety-eight procedures (82 dogs) using 2 or 2.7 mm TPLO plates were included spanning a 6 yr period with a minimum of an 8 wk follow-up period. The overall complication rate was 36%. Complications were grouped into three categories: intraoperative (2%), those occurring up to 2 wk postoperatively (11%), and those occurring &gt;2 wk postoperatively (30%). Radiographic evidence of delayed healing of the TPLO osteotomy site was the most common complication in the dogs (9%), none of which had clinical signs attributed to delayed healing. Other common complications included patellar tendon thickening (8%) and tibial tuberosity fracture (6%). Seven percent of the complications were considered major (requiring additional surgical intervention). Fifty-two percent of complications did not require treatment. Short-term complications should not dissuade an experienced surgeon from performing the TPLO procedure in small- and medium-sized dogs.

Assessment of the medial collateral ligament as an intra-operative anatomical landmark for tibial plateau levelling osteotomy

OBJECTIVES

To determine whether the medial collateral ligament can be a reliable intra-operative anatomical landmark for rotation of the tibial plateau in the tibial plateau levelling osteotomy (TPLO) procedure, thus providing a tibial plateau rotation equal to that obtained using standard preoperative measurements.

METHODS

Tibial plateau levelling osteotomy procedures were performed on pelvic limbs (n = 42) from canine cadavers with or without a history of cranial cruciate ligament deficiency. The rotation of the proximal fragment was performed such that the orientation of the fibres of the medial collateral ligament were aligned parallel to the caudal tibial cortex at the location of the osteotomy. Statistical analysis was performed to evaluate the difference between calculated rotation to achieve a postoperative tibial plateau angle of five degrees and the actual rotation achieved by aligning the medial collateral ligament and caudal tibial cortex.

RESULTS

The rotation performed by alignment of the medial collateral ligament fibres with the caudal tibial cortex resulted in a significantly greater rotation than the calculated movement required to achieve a postoperative angle of five degrees. The mean over-rotation was 2.1 ± 1.73 mm.

CLINICAL SIGNIFICANCE

Use of the medial collateral ligament alignment with the caudal tibial cortex will reliably result in over-rotation of the tibial plateau and should not be used as an intra-operative guideline for tibial plateau rotation during TPLO procedures.

Lateral and medial tibial plateau angles in normal dogs. An osteological study

OBJECTIVES

To measure lateral and medial tibial plateau angle values in isolated canine tibiae and to compare lateral and medial tibial plateau angle values between dogs based on sex and breed.

METHODS

Tibiae of 90 dogs from 24 different breeds were used. Photographs were taken of the medial and lateral aspects of the tibiae for measurement of the medial and lateral tibial plateau angles. Additionally, the medial tibial plateau angle was measured from radiographs of the tibiae. Two-way analysis of variance was used to test the effects of side, sex and breed on the medial and lateral tibial plateau angles as measured from photographs as well as the medial tibial plateal angles as measured from radiographs. The photographic and radiographic medial tibial plateau angles were compared by paired t-test, whereas the medial and lateral photographic tibial plateau angles were compared by t-test.

RESULTS

When all dogs were included in the analysis, the difference between the mean medial tibial plateau angle (24.0 ± 3.19°) and the mean lateral tibial plateau angle (25.5 ± 3.84°) as measured from photographs was significant (p <0.05). The difference in the photographic medial tibial plateau angle between male and female dogs was significant (p <0.05), whereas the difference in the photographic lateral tibial plateau angle between sexes was not significant. There was a significant difference between the medial and lateral tibial plateau angles as measured from photographs in male dogs (p <0.05) but not in female dogs. Breed comparisons also showed significant differences for the photographic lateral tibial plateau angle (p <0.05).

CLINICAL SIGNIFICANCE

The axial rotation of the femoral condyles on the tibial plateau is probably affected by the discrepancy between the medial and lateral tibial plateau angles, and this difference in certain breeds might influence the prevalence of cranial cruciate ligament disease.

Effect of anatomic variation in caudal tibial plateau on the tibial plateau angle in dogs: a cadaveric study

OBJECTIVES

To determine the effect of using two different landmarks to identify the caudal point on the joint orientation line in the sagittal plane in tibial plateau angle measurement in dogs: the caudal margin of the medial condyle as the anatomic tibial plateau angle and the tibial insertion of the caudal cruciate ligament as the conventional tibial plateau angle.

METHODS

A total of 170 tibiae from 85 mid- and large-breed dogs were used. The two joint orientation lines were drawn on photographic images of the bones. The angles between the line perpendicular to the tibial axis and the two lines were then measured as the anatomic and conventional tibial plateau angle.

RESULTS

The mean conventional tibial plateau angle (25·2 ±2·60°) and anatomic tibial plateau angle (23·5 ±2·59°) differed significantly (P<0·001), and the degree of this difference varied significantly among seven breeds (P<0·01).

CLINICAL SIGNIFICANCE

The results of this study suggest that the locations of the caudal margin of the medial condyle and the tibial insertion of the caudal cruciate ligament differed, leading to inconsistent identification of the joint orientation line depending on the landmark used.