Arthroscopic surgical approach and intra-articular anatomy of the equine suprapatellar pouch

Objective— To describe a direct arthroscopic approach to the suprapatellar pouch (SPP), its intra-articular anatomy, and report our clinical experience with SPP arthroscopy.
Study Design— (1) Experimental study and (2) retrospective clinical study.
Animals— (1) Cadaveric equine hind limbs (n=24; 14 horses) and (2) 5 horses.
Methods— Four femoropatellar joints (FPJ) were dissected or injected with latex to document surface landmarks and topographic anatomy. (1) Arthroscopic exploration of 20 SPP (10 equine cadavers) was performed and described, followed by dissection. (2) Medical records of horses that had FPJ arthroscopy were reviewed for cases where SPP portals were required.
Results— (1) The optimal arthroscopic portal was located ∼10 cm lateral to the longitudinal patellar axis and 2 cm proximal to the patellar base in the intermuscular septum between the biceps femoris and vastus lateralis muscles. This approach allowed arthroscopic observation of the proximal aspect of the lateral and medial femoral trochlear ridges, the intertrochlear groove, the patellar base, and the synovial recess of the SPP. (2) Additional arthroscopic and instrument suprapatellar portals were used in 5 of 25 horses to complete lavage/debridement in osteochondritis dissecans (OCD) and septic arthritis.
Conclusion— Suprapatellar arthroscopy improved arthroscopic observation of structures located proximally in the FPJ and facilitated surgical access to the SPP.
Clinical Relevance— SPP arthroscopy is a safe and complementary approach to traditional distal FPJ arthroscopy that could be helpful for inspection and removal of free fragments/debris/fibrin located in the SPP, for OCD lesions extending proximally, and fracture(s) involving the proximal aspect of the patella.     

Arthroscopic treatment of temporomandibular joint sepsis in a horse

OBJECTIVE: To report arthroscopic debridement and lavage of a septic temporomandibular joint (TMJ) in a horse. DESIGN: Clinical case report. ANIMALS: A 12-year-old Thoroughbred mare. METHODS: Arthroscopic investigation of the dorsal joint pouch of the right TMJ was made through a stab incision into the dorsocaudal compartment. Mechanized resection of synovium and fibrinous debris combined with copious lavage, and intra-articular and systemic antibiotic administration was used to treat the septic TMJ. RESULTS: Arthroscopic debridement and lavage of the TMJ, in combination with intra-articular and systemic antimicrobials resulted in resolution of sepsis. Eight months post-operatively, there was no clinical evidence of degenerative joint disease or ankylosis of the TMJ. CONCLUSION: TMJ sepsis is rare in horses, however, standard arthroscopic equipment can be used in the management of this condition with minimal complications. CLINICAL RELEVANCE: Arthroscopic debridement and lavage should be considered for evaluation and initial treatment of TMJ sepsis in horses.     

Evaluation of computed tomographic anatomy of the equine metacarpophalangeal joint

OBJECTIVE: To determine the detailed computed tomography (CT) anatomy of the metacarpophalangeal (MCP) joint in healthy horses. SAMPLE POPULATION: 10 cadaveric forelimbs from 10 adult horses without orthopedic disease. PROCEDURES: CT of the MCP joint was performed on 4 forelimbs. In 1 of the limbs, CT was also performed after intra-articular injection of 30 mL of contrast medium (40 mg of iodine/mL). Transverse slices 1-mm thick were obtained, and sagittal and dorsal planes were reformatted with a slice thickness of 2 mm. The CT images were matched with corresponding anatomic slices from 6 additional forelimbs. RESULTS: The third metacarpal bone, proximal sesamoid bones, and proximal phalanx could be clearly visualized. Common digital extensor tendon; accessory digital extensor tendon; lateral digital extensor tendon; superficial digital flexor tendon (including manica flexoria); deep digital flexor tendon; branches of the suspensory ligament (including its attachment); extensor branches of the suspensory ligament; collateral ligaments; straight, oblique, and cruciate distal sesamoidean ligaments; intersesamoidean ligament; annular ligament; and joint capsule could be seen. Collateral sesamoidean ligaments and short distal sesamoidean ligaments could be localized but not at all times clearly identified, whereas the metacarpointersesamoidean ligament could not be identified. The cartilage of the MCP joint could be assessed on the postcontrast sequence. CONCLUSIONS AND CLINICAL RELEVANCE: CT of the equine MCP joint can be of great value when results of radiography and ultrasonography are inconclusive. Images obtained in this study may serve as reference for CT of the equine MCP joint.     

Computed tomographic anatomy of the temporomandibular joint in the young horse

Reasons for performing study: The equine temporomandibular joint (TMJ) and its surrounding structures can be difficult to investigate in cases with a clinical problem related to the region. Little previous attention has been given either to a computed tomographic (CT) imaging protocol for the joint or an interpretation of the structures displayed in CT images of the normal joint. Objectives: To provide a CT atlas of the normal cross‐sectional anatomy of the equine TMJ using frozen and plastinated sections as anatomical reference. Methods: Eight TMJs from 4 immature pure‐bred Spanish horses were examined by helical CT. Scans were processed with a detailed algorithm to enhance bony and soft tissue. Transverse CT images were reformatted into sagittal and dorsal planes. Transverse, sagittal and dorsal cryosections were then obtained, photographed and plastinated. Relevant anatomic structures were identified in the CT images and corresponding anatomical sections. Results: In the CT images, a bone window provided excellent bone detail, however, the soft tissue components of the TMJ were not as well visualised using a soft tissue window. The articular cartilage was observed as a hyperattenuating stripe over the low attenuated subchondral bone and good delineation was obtained between cortex and medulla. The tympanic and petrous part of the temporal bone (middle and inner ear) and the temporohyoid joint were seen in close proximity to the TMJ. Conclusions: Helical CT provided excellent images of the TMJ bone components to characterise the CT anatomy of the normal joint. Potential relevance: Detailed information is provided that may be used as a reference by equine veterinarians for the CT investigation of the equine TMJ and serve to assist them in the diagnosis of disorders of the TMJ and related structures (middle and inner ear). The study was performed at an immature stage and further studies of mature individuals are required in order to confirm that the clinical interpretation is not affected by changes occurring with age.     

Arthroscopic landmarks of the equine carpus

The radiocarpal and middle carpal joints of 4 clinically normal horses and 24 necropsy specimens were examined with an arthroscope to describe the topographic anatomy of these joints. The carpal bones of the radiocarpal joint had congruent articular surfaces in extension, but carpal flexion resulted in a stairstep between the radial and intermediate carpal bones. The variable surface anatomy, as well as the restricted synovial space and the technical limitations of the arthroscope, contributed to the need for more than one arthroscopic approach to the radiocarpal joint to ensure a thorough examination. The middle carpal joint's hinge-like biomechanics resulted in a spacious synovial cavity that was more amenable to arthroscopic examination. Careful planning was necessary to ensure that areas of interest were distant from the arthroscope-insertion site to allow the best perspective possible. The lateral approach to the middle carpal joint provided the best viewing of both facets of the intermediate and third carpal bones as well as the dorsal rim of the radial carpal bone. The medial approach did not allow complete inspection of these areas.     

Anatomy of the equine temporomandibular joint: study by gross dissection, vascular injection and section

REASONS FOR PERFORMING STUDY: The minute anatomy of the temporomandibular joint (TMJ) in horses is poorly documented in the literature. OBJECTIVES: To examine in detail the anatomy of the normal equine TMJ and the relationship of the joint to adjacent structures. METHODS: The anatomy of the TMJ was examined in 12 equidae using dissections, synovial and vascular injections and frozen and plastinated sections. Relevant structures were photographed. RESULTS: Rostral and caudal compartments were identified in the dorsal and ventral synovial pouches of the TMJ. Lateral and caudal ligaments were identified and attachments of the masticatory muscles over the TMJ were documented. Direct relationships between the TMJ and components of the ear were found, and the vascular supply described. CONCLUSIONS: This joint is related to some components of the ear as in man, and has its own peripheral vascular supply. Potential relevance: A knowledge of the detailed anatomy of the equine TMJ is a prerequisite to interpreting the imaging techniques, and will enable improved diagnosis of TMJ pathologies.