Development of a three-dimensional computer model of the canine pelvic limb including cruciate ligaments to simulate movement.

Gait analysis as subjective visual assessment forms the foundation of the veterinarian's lameness examination. Pelvic limb lameness is frequently seen in dogs and the stifle joint with its cruciate ligaments, is a main cause of lameness due to cruciate ligament deficiency. In this study, we developed an open-source three-dimensional musculoskeletal pelvic limb model of a 30 kg Labrador Retriever including cruciate ligaments, simulating the gait cycle of the walking movement with the open-source programs NMSBuilder (Institutio Ortopedico Rizzoli, Bologna, Italy) and OpenSim (National Center for Simulation in Rehabilitation Research (NCSRR), Stanford, CA, USA). The computer model generated muscle activations based on motion data. The computed activations were similar to experimental electromyogram data. Highest joint torque was in extension/flexion in the stifle joint at 54 Nm at 14% of the gait cycle with cruciate ligaments. Highest stifle joint reaction force was 408 N at 16% of the gait cycle and was reduced after adding cruciate ligaments. Especially the cranial cruciate ligament loads up to 102 N (34% body weight). Cranial cruciate ligament forces increase with stifle extension and decrease with stifle flexion. On the contrary, the caudal cruciate ligament loads up to 27 N (9% body weight) during the swing phase with a flexed stifle joint. The model was validated with electromyogram data. The model's predictions are plausible because joint torques and forces match the applied ground reaction forces in curve progression and in timing. This model forms a basis for further investigations into stifle surgery after cruciate ligament deficiency.

Effect of Stifle Flexion Angle on the Repeatability of Real-Time Elastosonography of the Patellar Ligament in Medium- to Large-Breed Dogs.

OBJECTIVE: The aims of this study were to describe the elastosonographic findings of the patellar ligament in healthy dogs >15 kg in different positions and determine the most appropriate stifle angle to perform elastosonography of the patellar ligament. STUDY DESIGN: Eighteen clinically healthy dogs, weighing >15 kg, were prospectively recruited. B-mode ultrasound and real-time elastosonography of both patellar ligaments were performed on days 0 and 14. Elastosonography examinations were performed with the stifle in four positions: standing position, lateral recumbency with the stifle positioned at 135 degrees extension and in full passive flexion and extension. RESULTS: The percentage hardness of the patellar ligament was significantly lower when the elastosonographic examination was performed with the dog standing, compared with the other positions (p < 0.005). The variability in the elastosonography readings for each stifle position was lowest when the dog was standing (89.32%). CONCLUSION: Elastosonography is a feasible technique for evaluating the elasticity of the normal canine patellar ligament in dogs >15 kg and would be a useful technique for investigating the mechanical changes within the patellar ligament following stifle surgery. Elastosonography of the patellar ligament should be performed with the dog standing to provide the most accurate elastosonograms with lowest variability between readings.

Comparative histomorphometric analysis of cellular phenotype in canine stifle ligaments and tendon.

OBJECTIVE: To measure the density of cellular phenotypes in canine caudal cruciate ligament (CaCL), cranial cruciate ligament (CrCL), medial collateral ligament (MCL), and long digital extensor tendon (LDET). STUDY DESIGN: Ex-vivo study. METHODS: Ten CaCL, CrCL, MCL, and LDET obtained from 1 stifle of 10 dogs with no gross pathology were analyzed histologically. The density of cells with 3 nuclear phenotypes (fusiform, ovoid, and spheroid) was determined within the core region of each specimen. RESULTS: Cells with fusiform nuclei were most dense in the MCL (median [range], 319 [118-538] cells/mm2 ) and LDET (331 [61-463]), whereas cells with ovoid nuclei were most dense in the CaCL (276 [123-368]) and CrCL (212 [165-420]). The spheroid nuclear phenotype had the lowest density in all structures (31 [5-61] in CaCL, 54 [5-90] in CrCL, 2 [0-14] in MCL, and 5 [0-80] in LDET); however, the CrCL contained a denser population of spheroid cells compared with MCL and LDET (P < .05). Total cell densities did not differ among the 4 structures (P > .05). CONCLUSION: Phenotype density varied within the ligaments and tendon tested here. The cell population of CaCL and CrCL differed from that of dense collagenous tissues such as MCL and LDET. CLINICAL SIGNIFICANCE: The relatively higher density of spheroid phenotype in CrCL may reflect a distinctive native cellular population or a cellular transformation secondary to unique mechanical environment or hypoxia. This intrinsic cellular population may explain altered tissue properties prone to pathological rupture or poor healing potential of the canine CrCL.

Functional Anatomy of the Craniomedial and Caudolateral Bundles of the Cranial Cruciate Ligament in Beagle Dogs.

OBJECTIVE: The aim of this study was to investigate detailed functional anatomy of the craniomedial bundle (CrMB) and caudolateral bundle (CdLB) of cranial cruciate ligament (CrCL) for application of intra-articular anatomical reconstruction in dogs. MATERIALS AND METHODS: Twelve stifle joint of 12 Beagle cadavers were used. Anatomical characteristics of femoral attachment regions of the CrCL were determined. Then, the location and area of the footprints of the CrMB and CdLB were objectively measured. Each bundle was equally divided into four fibre bundles, and changes in the fibre arrangement were recorded during stifle range of motion. Additionally, the tension of each fibre bundle at various stifle joint angles was objectively measured. RESULTS: The attachment region of the CrCL clearly differed from that reported in humans. The centre of the CdLB attachment site was located craniodistal to that of the CrMB on the femur and slightly caudal to that of the CrMB on the tibia. The area of the CrMB on the femoral and tibial attachment sites was larger than that of the CdLB. During stifle range of motion, each divided fibre bundle in the CrMB and CdLB was twisted intricately. The tension of the CrMB was higher than that of CdLB. The central part of the CrMB was always tense during stifle range of motion. CLINICAL SIGNIFICANCE: These results may contribute to the application of anatomical reconstruction surgery for CrCL deficient stifle in dogs.

Effect of osteoarthritis on the repeatability of patella tendon angle measurement in dogs.

OBJECTIVE: To evaluate the influence of osteoarthritis on the measurement of patella tendon angle (PTA) and determine intraobserver and interobserver variability. STUDY DESIGN: Retrospective clinical study. SAMPLE POPULATION: Eighty-seven mediolateral radiographs that were obtained prior to tibial tuberosity advancement. METHODS: Radiographic osteoarthritis was scored by 2 observers using guidelines derived from the International Elbow Working Group Protocol. Patella tendon angle was measured by 3 observers on 3 occasions, with at least 7 days between measurements. The data were statistically analyzed via weighted κ and Kruskal-Wallis testing. RESULTS: A fair strength of agreement was found among observers scoring osteoarthritis, with the same grades in 48% of radiographs. The intraobserver average bias between PTA measurements 1 and 3 ranged from -0.38° to -0.94°. Interobserver bias in angle measurement ranged from -0.92° to -2.00°. Observer 1 had the narrowest range of PTA differences (12.1°), and observer 3 had the highest range of PTA differences (23.5°). Observer 2 had the lowest mean bias (-0.38°). The mean bias was lowest between observers 1 and 2 (-0.92°) and highest between observers 1 and 3 (-2.0°). The mean intraobserver standard deviation of the PTA measurement differences was 2.90°, and interobserver standard deviation of the PTA measurement differences was 2.26°. The degree of osteoarthritis did not influence PTA measurements or their variability. CONCLUSION: The current study did not find evidence of an influence of osteoarthritis on PTA or on the repeatability of measurements. CLINICAL SIGNIFICANCE: Our findings suggest that osteoarthritis should not affect the radiographic planning for tibial tuberosity advancement surgery. The high variances in PTA measurement in less experienced observers may influence the clinical outcome of surgery.

Computed Tomographic Trochlear Depth Measurement in Normal Dogs.

OBJECTIVES: The main purpose of this study was to describe the relationship between patellar maximal craniocaudal thickness and femoral trochlear groove depth in normal dogs and to valuate the intra-observer or inter-observer variability of maximal trochlear depth and maximal patellar craniocaudal thickness using computed tomography. METHODS: Trochlear groove depth and patellar maximal craniocaudal thickness of 40 limbs (20 dogs) were measured by three independent veterinarians using three-dimensional multiplanar reconstruction computed tomography images. The patellar maximal craniocaudal thickness/trochlear depth ratio was determined. RESULTS: The mean ratio of these stifles was 0.46 (range 0.24-0.70), meaning that the mean maximal depth of the trochlea was 46% of the mean maximal-patellar thickness. CLINICAL SIGNIFICANCE: A wide range of maximal-patellar-craniocaudal-thickness/maximal trochlear-depth ratio was found suggesting that breed studies should be performed to determine a breed-specific patellar-thickness/trochlear-depth ratio. To make decisions on when and where to perform a sulcoplasty during patellar luxation surgery, patella/trochlea thickness relationship should be measured for each breed with patellar tracking from stifle hyperflexion to stifle hyperextension.

Arthroscopic approach and anatomy of the stifle joint in the rabbit.

OBJECTIVE: To describe a technique and normal findings for arthroscopy of the stifle in rabbits. STUDY DESIGN: Cadaver study. ANIMALS: Twenty cadaveric stifles from New Zealand White rabbits were examined. METHODS: The arthroscope was placed through a medial portal, and instrument portals were created on the lateral aspect of the joint. The same portals were used for examination of the entire joint and palpation of structures with a probe. RESULTS: Structures identified in the proximal aspect of the stifle included the suprapatellar pouch, suprapatella, patella, medial and lateral proximal recesses, medial and lateral trochlear ridges, trochlear groove. Structures identified in the distal aspect of the joint included the cranial and caudal cruciate ligaments, medial and lateral menisci, medial and lateral femoral condyles, the long digital extensor tendon, and the cranial meniscal ligaments were identified. All of the proximal structures could be seen in 16/20 limbs. Distally, the cranial cruciate ligament could be identified and manipulated most often (17/20 limbs), followed by the caudal cruciate ligament (11/20), the menisci (9/20), and condyles (9/20). The average examination time was 27 minutes. There was a variably present femorotibial membrane. CONCLUSION: We conclude that the arthoscopic evaluation of the stifle in rabbits is a viable surgical approach and could be used for rabbit models or to examine clinical cases with stifle pathology. Precise portal placement and adequate infrapatellar fat pad debridement were critical for success.

Anatomia microscópica e ultraestrutura do joelho da paca (Cuniculus paca Linnaeus, 1766) / Microscopic anatomy and ultrastructure of paca stifle (Cuniculus paca Linnaeus, 1766)

A paca (Cuniculus paca), um dos maiores roedores da fauna brasileira, possui características inerentes à sua espécie que podem contribuir como uma nova opção de animal experimental; assim, considerando-se que há crescente busca por modelos experimentais apropriados para ortopedia e pesquisas cirúrgicas, foram analisados e descritos em detalhes a anatomia microscópica e ultraestrutural do joelho desse roedor. Os ligamentos colaterais são constituídos por feixes de fibras colágenas arranjadas paralelamente e com trajeto ondulado. Os fibroblastos formavam fileiras paralelas às fibras colágenas; quanto aos ligamentos colaterais, estes apresentaram citoplasma imperceptível à avaliação por microscopia de luz, entretanto, em análise ultraestrutural verificou-se vários prolongamentos citoplasmáticos. Microscopicamente, as estruturas presentes no joelho da paca assemelham-se às dos animais domésticos, roedores e lagomorfos.(AU)

Paca (Cuniculus paca), one of the largest rodent of the Brazilian fauna, has characteristics inherent to the species that can contribute as a new experimental animal; so, considering that there is a growing search for experimental models suitable for orthopedic and surgical research, it was analyzed and described in detail the microscopic and ultrastructural anatomy of the stifle in this rodent. The collateral ligaments are composed of bundles of collagen fibers arranged in parallel and in wavy path. Fibroblasts formed parallel rows to the collagen fibers; concerning the collateral ligaments, they presented imperceptible cytoplasm at light microscopy, but at ultrastructure analysis they presented several cytoplasmic processes. At the microscopic level, the stifle of paca resembles the domestic animals, rodents and lagomorphs.(AU)

Determination of reference values and frequency of occurrence of patella alta in German shepherd dogs: a retrospective study.

BACKGROUND: Patella alta and patella baja are important conditions underlying a predisposition to many joint diseases, including patellar luxation and patellar chondromalacia of the articular cartilage. The frequencies of patella alta and patella baja have not yet been determined. The objectives of this study were to determine the frequency of patella alta and to determine reference values to the position of the vertical patella according to two modified techniques of the Insall-Salvati method in a group of 65 German shepherd dogs (115 stifle joints). RESULTS: The upper limits of reference values for the normal vertical position of the patella were 1.79 and 2.13, depending on the method of measurement. A high prevalence of patella alta was observed in the group of German shepherd dogs. A correlation was demonstrated between the classification of dogs' joints in the patella alta group and the multiplied risk of canine hip dysplasia (CHD) through the estimation of odds ratios. CONCLUSIONS: Dogs with patella alta were healthy dogs that did not exhibit orthopaedic problems in the stifle joints. The results revealed that the risk of CHD is twice as high in dogs with higher patellar ligament length to patella length ratio.

Systematic arthroscopic investigation of the bovine stifle joint.

The objective of the present study was to establish a protocol for arthroscopic exploration of the bovine stifle joint using craniomedial, caudolateral and caudomedial approaches. An anatomic and arthroscopic study using 26 cadaveric limbs from 13 non-lame adult dairy cows was performed. The craniomedial approach was created between the middle and medial patellar ligaments to investigate the cranial pouches of the stifle joint. The inter-condylar eminence, the proximal aspect of the medial femoral trochlear ridge and the lateral aspect of the lateral femoral condyle were used as starting points for systematic examination of the medial femorotibial, the femoropatellar and the lateral femorotibial joints, respectively. The observed structures were: the suprapatellar pouch, articular surfaces of the patella, femoral trochlear ridges, cruciate ligaments, menisci, and the meniscotibial ligaments. The arthroscopic portal for the caudomedial femorotibial pouch was about 6-8 cm caudal to the medial collateral ligament. The proximal and distal caudolateral femorotibial pouches were explored 3 cm and 1.5 cm caudal to the ipsilateral collateral ligament, respectively. The observed structures were the caudal aspect of femoral condyles, menisci, caudal cruciate ligament, popliteal tendon and the meniscofemoral ligament. Restricted joint size and risk of common peroneal nerve damage were the major limitations for exploration of the caudal femorotibial compartments. The study described the arthroscopic portals and normal intra-articular anatomy of the bovine stifle joint but further investigations are warranted to validate these techniques in clinical cases.

Comparison of the tibia plateau angle between small and large dogs with cranial cruciate ligament disease.

OBJECTIVES: To compare the conformation of the proximal tibia evaluated on a medio-lateral radiograph between small and large dogs with cranial cruciate ligament disease (CCLD). METHODS: Retrospective clinical study with dogs having radiographic evaluation and CCLD confirmed at surgery. The first group (n = 52) was comprised of dogs weighing less than 15 kg and the second group (n = 52) of dogs weighing more than 15 kg. The tibial plateau angle (TPA), the relative tibial tuberosity width (rTTW), and the Z angle were measured on preoperative radiographs with imaging measurement software. Linear mixed models were used to assess the effect of weight, age, sex, and neutered status on radiographic measurements and to estimate interobserver variabilities. RESULTS: The small dog group had a greater TPA (30.1° ± 5.3; p <0.001 with a mean difference of 4.9° [95% CI: 3.8-6.0]) and Z angle (69.9° ± 5.6; p<0.001 with a mean difference of 6.1° ([95% CI: 4.9-7.4]) than the large dog group. Sex and neutered status further influenced the TPA and Z angle values. No significant effect was observed on the rTTW values. A strong correlation was found between the TPA and the Z angle (r = 0.61, p <0.001). Variances were not significantly different between observers. Overall the interobserver variability was low suggesting that agreement was good. CLINICAL SIGNIFICANCE: Small dogs with CCLD have a steeper tibial plateau than large dogs with CCLD. Sex and neutered status also had an effect on some measured variables. This anatomical difference could influence the surgical technique, which may affect the outcome. The good interobserver agreement suggests the observer is unlikely to influence surgical planning.

Evaluation of a distractor to increase joint space of the stifle joint in dogs: a cadaveric study.

OBJECTIVE: To evaluate the technical feasibility and efficacy of a joint distraction technique to increase the stifle joint space and assess potential soft tissue damage due to the distraction. METHODS: Twenty stifle joints of twelve canine cadavers without evidence of disease were radiographically evaluated by medio-lateral, cranio-caudal and varus-valgus stressed projections. Joint distraction was applied with loads from 40 N up to 200 N, and the joint space achieved was measured on radiographic images. Distraction plus distension with saline was subsequently applied and measured. Varus-valgus stressed projections were repeated after distraction to evaluate a potential increase in joint laxity. RESULTS: Distraction produced a significant increase of the joint space for most of the evaluated loads. Distraction plus distension produced a significant increase for most of the loads compared to the distraction alone. No ensuing joint laxity could be inferred from the post-distraction radiographic evaluation. CLINICAL SIGNIFICANCE: Stifle distraction produces an increase of the joint space, which is wider when intra-articular saline is injected. This may be potentially useful for improving joint structure visualization and facilitating arthroscopic procedures, thus reducing the potential for iatrogenic damage to intra-articular structures. No soft tissue damage could be inferred by radiographic pre- and post-procedure comparison. Further clinical studies are required to evaluate potential neurovascular complications.

Anterior cruciate ligament: an anatomical exploration in humans and in a selection of animal species.

PURPOSE: Many anatomical anterior cruciate ligament (ACL) studies have indicated that the human ACL is composed of two functional bundles: the antero-medial (AM) and postero-lateral (PL). The purpose of this study is to compare the ACL anatomy among human and assorted animal species. METHODS: Twenty fresh-frozen knees specimen were used: five humans, ten porcine, one goat, one Kodiak bear, one African lion, one Diana monkey and one Gazelle antelope. All the specimens were dissected to expose the ACL and to visualize the number of bundles and attachment patterns on the tibia and femur. Following the fibre orientation of the individual bundles, a wire loop was used to bluntly separate the bundles starting from the tibial insertion site to the femoral insertion site. In the human and porcine ACL, each bundle was separated into approximately 2 mm diameter segments and then tracked in order to establish the individual bundle's specific pattern of insertion on the femur and tibia. RESULTS: It appeared that all human and animal knee specimens had three bundles that made up their ACL. In addition, it was noted that among the various specimens species, all viewed with an anterior view, and at 90° knee flexion, the ACL bony insertion sites had similar attachment patterns. CONCLUSION: In all the specimens, including human, the ACL had three distinct bundles: AM, intermediate (IM) and PL. The bundles were composed of multiple fascicles arranged in a definite order and similar among the different species.

Radiographic localization and isometry of the origin and insertion of the canine cranial cruciate ligament.

OBJECTIVE: To radiographically define the anatomic origin and insertion of the cranial cruciate ligament translated to the lateral radiographic projection of the stifle (CrCL-Lo and CrCL-Li, respectively), to correlate these landmarks for identification of the CrCL-Lo intraoperatively, and to compare the isometry of the CrCL-Lo to the lateral fabella. STUDY DESIGN: Experimental study. SAMPLE POPULATION: Pelvic limbs (n = 12) from dogs weighing 13-26 kg. METHODS: A radiographic quadrant method was used to localize the CrCL-Lo. Mediolateral radiographic projections of each stifle were taken through a range of motion. Maximum percent change in length between each tibial marker and femoral marker during range of motion determined isometry. RESULTS: The CrCL-Lo is located at the caudal 33% and distal 50% of the lateral femoral condyle using Blumensaat's line or a line from the origin of the long digital extensor (LDE) to the lateral fabella, with no significant difference (P = .766) between the 2 reference lines. The CrCL-Li is located at the proximal 20% of the tibial plateau. No significant difference (P < .05) in isometry was found between the CrCL-Lo and lateral fabella. CONCLUSION: The CrCL-Lo is located at the caudal 1/3 and distal ½ of the lateral femoral condyle. The CrCL-Lo and lateral fabella are not significantly different in isometry when used as a proximal anchor point in extracapsular stifle stabilization.

Medial femoral condyle morphometrics and subchondral bone density patterns in Thoroughbred racehorses.

OBJECTIVE: To characterize medial femoral condyle (MFC) morphometrics and subchondral bone density patterns in Thoroughbred racehorses and to determine whether these variables differ between left and right limbs. SAMPLE: Stifle joints harvested from 6 Thoroughbred racehorses euthanized for reasons other than hind limb lameness. PROCEDURES: The distal portion of the left and right femurs of each cadaver was scanned via CT. Hounsfield units were converted to dipotassium phosphate equivalent densities through use of a phantom on each specimen. Medial femoral condyle width, length, height, and curvature; subchondral bone plate densities; and subchondral trabecular bone densities were analyzed in multiple sections in 5 frontal planes and 3 sagittal planes and were compared between left and right MFCs. RESULTS: MFC width, length, and height did not differ between left and right limbs. Regions of interest in the right caudoaxial subchondral bone plate and subchondral trabecular bone were significantly denser than their corresponding left regions of interest in the frontal and sagittal planes. A concavity in the otherwise convex articular surface of the cranial aspect of the MFC was identified in 11 of 12 specimens. CONCLUSIONS AND CLINICAL RELEVANCE: A disparity was identified between left and right subchondral bone density patterns at the caudoaxial aspect of the MFC, which could be attributable to the repetitive asymmetric cyclic loading that North American Thoroughbred racehorses undergo as they race in a counterclockwise direction. The uneven region at the cranial aspect of the MFC could be associated with the development of subchondral bone cysts in horses.

Magnetic resonance imaging (MRI) anatomy of the ovine stifle.

OBJECTIVE: To describe magnetic resonance imaging (MRI) anatomy of the ovine stifle and investigate meniscotibial and cruciate ligaments anatomy. STUDY DESIGN: Descriptive ex vivo study. ANIMALS: Pelvic limbs (n = 44) from 22 adult Texel ewes. METHODS: Forty limbs (n = 40) were scanned using 3 Tesla MRI before gross anatomic dissection. Two other limb pairs were frozen and transected to obtain sections that were compared with MRI images for identification of anatomic structures. RESULTS: In all stifles, the craniomedial bundle of the cranial cruciate ligament inserted caudally to the cranial attachment of the medial meniscus. No transverse intermeniscal ligament was identified in 80% of stifles, whereas a few small ligamentous fibers were seen crossing from 1 cranial horn to the other in 20% of stifles. There was good differentiation of menisci, ligaments, and synovial cavities on MRI images. Two bundles were identified in all cranial cruciate ligaments on MRI. Sensitivity and specificity of 3T MRI for detection of transverse intermeniscal ligament were 42% and 84%, respectively. CONCLUSION: 3T MRI provided well defined reference images for menisci, synovial cavities, and most ligaments.

Measurement of femoral and tibial joint reference angles and pelvic limb alignment in cats.

OBJECTIVE: To report pelvic limb joint reference angles, limb alignment, and mechanical axis deviation for the feline pelvic limb. STUDY DESIGN: Cadaveric radiographic anatomic study. ANIMALS: Skeletally mature, mixed breed cats (n = 50). METHODS: Extended pelvic limb radiography was performed and images analyzed to determine femoral anatomic joint reference angles, femoral and tibial mechanical joint reference angles, tibiofemoral angle, metatarsotibial angle, mechanical axis-femur and mechanical axis-metatarsus angles, and mechanical axis deviation of the stifle and tarsus. Mean ± SD and 95% confidence intervals (95% CI) were calculated. RESULTS: Mean ± SD angles and 95% CI were: anatomic lateral proximal femoral (103.9° ± 3.8°; 103.1° - 104.6°), anatomic lateral distal femoral (93.8° ± 2.5°; 93.3° - 94.3°), mechanical lateral proximal femoral (100.5° ± 3.7°; 99.8° - 101.2°), mechanical lateral distal femoral (97.2° ± 2.2°; 96.7° - 97.6°), mechanical medial proximal tibial (88.0° ± 3.2°; 87.3° - 88.6°), mechanical medial distal tibial (107.6° ± 4.8°; 106.6° - 108.5°), mechanical tibiofemoral (7.4° varus ± 2.5°; 6.9° - 7.9°), mechanical metatarsotibial (6.0° valgus ± 3.5°; 5.3° - 6.7°); mechanical axis-femur (3.2° ± 1.4°; 2.9° - 3.5°) and mechanical axis-metatarsus (2.4° ± 2.0°; 1.7° - 2.1°). Mechanical axis deviation of the stifle and of the tarsus were 2.0% ± 0.9% (95% CI: 1.9-2.2) and 0.8% ± 1.0% (95% CI: 0.7-1.0), respectively. CONCLUSIONS: Mean pelvic limb joint reference and limb alignment angles can be used for diagnosing angular limb deformities of the feline pelvic limb and for planning corrective osteotomies in affected cats.

Arthroscopic approach to the subextensorius recess of the lateral femorotibial joint of the foal.

OBJECTIVE: To (1) develop an arthroscopic approach to the subextensorius recess of the lateral femorotibial (LFT) joint in foals and (2) report its use in foals with LFT joint sepsis. STUDY DESIGN: (1) Anatomic study and (2) retrospective case series. SAMPLE POPULATION: (1) Cadaveric hind limbs (n = 32 foals) to delineate the anatomy of the subextensorius recess; 13 foal limbs for cadaver surgery to assess the approach to the subextensorius recess; and (2) foals (n = 8) with LFT joint sepsis. METHODS: (1) The LFT joint was distended and examined ultrasonographically. Dissection was used to document periarticular landmarks, potential distal arthroscopic portals, and assess iatrogenic damage after cadaveric surgery. (2) Retrieval of data from 8 foals with LFT joint sepsis treated using the arthroscopic approach. RESULTS: (1) The optimal arthroscopic approach to the distal subextensorius recess is craniolaterally, 8-10 cm distal to the tibial plateau, immediately caudal to the peroneus tertius muscle, through the long digital extensor muscle belly, entering the distal extent of the subextensorius recess. Thirteen limbs dissected after cadaver surgery had no iatrogenic damage to the peroneus tertius muscle or peroneal nerve. (2) Two foals were euthanized. Resolution of sepsis occurred in 6 foals, and all were sound at follow-up >9 months after surgery. CONCLUSION: The subextensorius recess may be safely accessed arthroscopically in foals.

Arthroscopic approach and intraarticular anatomy of the stifle in South American camelids.

OBJECTIVE: To describe a cranial arthroscopic approach to the stifle of South American camelids and to report our clinical experience with camelid stifle arthroscopy. STUDY DESIGN: Experimental study and retrospective case series. ANIMALS: (1) Cadaveric alpaca hindlimbs (n = 18; 9 alpacas); (2) 1 alpaca and 1 llama METHODS: Polymethylmethacrylate joint casts (n = 2) were made to define stifle joint dimensions. Cadaveric stifle joints (n = 16) were evaluated arthroscopically to determine arthroscopic portal locations, describe the intraarticular anatomy, and report potential complications. An alpaca and a llama with stifle joint disease had diagnostic arthroscopy. RESULTS: Successful entry into the stifle joint was achieved in 16 cadaver limbs. Observed structures were: the suprapatellar pouch, articular surface of the patella, femoral trochlear ridges and groove, cranial aspect of the femoral condyles (n = 16); distal aspect of the cranial and proximal aspect of the caudal cruciate ligaments (14); and cranial aspects of the medial and lateral menisci (11), and cranial meniscotibial and intermeniscal ligaments (8). Stifle arthroscopy allowed for joint evaluation and removal of osteochondral fragments in 1 alpaca and 1 llama with naturally occurring stifle disease. Complications of cadaver or live procedures included minor cartilage scoring (3 stifles) and subcutaneous periarticular fluid accumulation (8 stifles). CONCLUSIONS: Arthroscopy provides a safe approach for diagnosis and treatment of stifle lesions in South American camelids.

The arthroscopic and ultrasonographic boundaries of the equine femorotibial joints.

REASONS FOR PERFORMING STUDY: While descriptions of the visible soft tissues of the femorotibial joints exist for both arthroscopy and ultrasonography, there are few examples in the literature that discuss in detail the combined findings of these modalities. OBJECTIVES: To further elucidate the ultrasonographic and arthroscopic boundaries of the normal equine femorotibial joints and improve the understanding of the benefits and limitations of each individual modality. METHODS: Simultaneous arthroscopy and ultrasonography were performed in 10 equine cadaver stifles as well as bilateral stifles on a horse that underwent nonrecovery surgery. The arthroscopic probe was visualised ultrasonographically and concurrent video and still images acquired. RESULTS: Arthroscopy provided good visualisation of the cranial meniscal ligaments, the distal portion of the cranial cruciate ligament, proximal portion of the medial collateral ligament within the fibrous tissue of the joint capsule and a limited view of the abaxial border of meniscus. Ultrasonography allowed for almost complete visualisation of the menisci, collateral ligaments and cranial meniscal ligaments and a portion of the cranial cruciate ligament. CONCLUSIONS: By comparing the ultrasonographically and arthroscopically visible structures, this study allowed for a more complete understanding of the advantages and limitations of each modality. The ability of ultrasonography to resolve mild pathological changes should be further explored. POTENTIAL RELEVANCE: When used together, these modalities can provide a more global image of the femorotibial joints.