A cranial intercondylar arthroscopic approach to the caudal medial femorotibial joint of the horse

Reason for performing study: Current noninvasive techniques for imaging the soft tissue structures of the stifle have limitations. Arthroscopy is commonly used for the investigation and treatment of stifle pain. Cranial and caudal arthroscopic approaches to the femorotibial joints are used. However, complete examination of the axial aspect of the medial femorotibial joint (MFTJ) is not possible currently. Objective: To develop a cranial approach to the caudal pouch of the MFTJ and to assess whether it would allow a more complete examination of the compartment and facilitate the caudomedial approach. Method: The regional anatomy was reviewed and the technique developed on cadavers. A series of nonrecovery surgeries were performed to evaluate the procedure, which was then used in 7 clinical cases. Advantages compared to existing techniques and complications encountered were recorded. Results: Successful entry into the caudal pouch of the MFTJ was achieved in 20 of 22 cadaver legs, 8 of 8 joints of nonrecovery surgery horses and 6 of 7 clinical cases operated. The caudal ligament of the medial meniscus could be visualised, along with other axial structures of the caudal joint pouch. The technique was used to facilitate a caudomedial approach and allowed better triangulation within the joint space. Complications were minor and included puncture of the caudal joint capsule and scoring of the axial medial femoral condyle. Conclusions and potential relevance: It is possible to access the caudal pouch of the MFTJ arthroscopically using a cranial intercondylar approach. The technique has advantages when compared to existing techniques and is associated with few significant complications. A cranial approach to the caudal pouch of the MFTJ could complement existing techniques and be useful clinically.     

Comparison of four techniques of arthrocentesis of the lateral compartment of the femorotibial joint of the horse

Reasons for performing study: Clinical experiences indicate that centesis of the lateral compartment of the femorotibial joint is often unsuccessful. Objective: To determine the accuracy of 2 published and 2 unpublished techniques of centesis of the lateral compartment of the femorotibial joint. Hypothesis: It was hypothesised that a drug can be administered into the lateral compartment of the femorotibial joint via a diverticulum of this joint that surrounds the medial aspect of the long digital extensor tendon and that this technique is more accurate than described techniques of centesis of this compartment. Methods: Twenty‐four stifles of 12 horses were divided equally into 4 groups and a radiocontrast medium injected into the lateral compartment of the femorotibial joint of each group using a hypodermic needle inserted: 1) caudal to the lateral patellar ligament and proximal to the tibial plateau, 2) caudal to the long digital extensor tendon and proximal to the tibial plateau, 3) between the long digital extensor tendon and bone of the extensor groove of the tibia or 4) directly through the long digital extensor tendon until it contacted bone. Twelve veterinary students who had no experience using any of these techniques performed the injections. Accuracy of each technique was determined by examining radiographs obtained after injecting the contrast medium. Results: The most successful technique for arthrocentesis was by inserting a needle through the long digital extensor tendon. This approach was successful in all attempted cases, whilst other techniques had lower rates of success. Conclusions: The lateral compartment of the femorotibial joint can be accessed accurately by inserting a needle through the long digital extensor tendon as it lies within the extensor groove. Other techniques may not be as accurate for clinicians inexperienced in arthrocentesis of the lateral compartment of the femorotibial joint.     

Acquired peri-articular ganglion cyst in the lateral femorotibial joint in an 18-year-old Percheron cross mare

This report describes a case of sudden lameness in an 18-year-old Percheron cross mare after presumably being kicked by another horse, and the subsequent formation of a ganglion cyst originating from the lateral femorotibial joint. Physical examination, radiographic and ultrasonographic investigation identified a soft round 5 cm diameter mass attached to the left lateral femorotibial joint. After surgical removal, histopathological examination confirmed a ganglion cyst. The horse responded well to the surgical removal of the cyst, and 4 weeks after the surgery, the mare has returned back to her same athletic performance. According to the authors’ knowledge, this is the first reported case that describes a peri-articular ganglion cyst originating from the stifle joint.     

Current joint therapy usage in equine practice: a survey of veterinarians 2009

Reasons for performing study: Medications are frequently employed to treat intra‐articular (IA) problems in the performance horse. Actual usage of the different IA medications in horses is not available. Objectives: To determine the most common usage of these medications, members of the American Association of Equine Practitioners (AAEP) were surveyed. Methods: An email link to an online survey was electronically sent to 6305 AAEP members and the responses tabulated and analysed with a logistic regression model. Results: A total of 831 survey responses were submitted and tabulated. Eighty per cent of the respondents indicated that they see 100% equine cases in their practice. The majority of respondents (77%) use triamcinolone acetonide (TA) to treat high motion joints and 73% use methylprednisolone acetate (MPA) to treat low motion joints. Veterinarians treating the Western performance and Sport horse were significantly more likely to use TA in high motion joints compared to MPA (P = 0.0201 and P<0.0001, respectively). Triamcinolone acetonide use compared to MPA in high motion joints by racehorse veterinarians was significantly lower compared to other veterinarians (P<0.0001). Polysulphated glycosaminoglycan (Adequan) and hyaluronate sodium (Legend) were the most commonly used disease modifying products (63 and 57% of respondents, respectively). Sport horse practitioners were significantly more likely than race or show horse veterinarians to utilise IRAP products (P = 0.0035 and P = 0.04, respectively). Respondents who had been in practice for more than 10 years were significantly less likely to use antimicrobials in their joint injections compared to those in practice for less than 10 years (P<0.0001). Conclusions: Significant differences existed in usage of medications related to primary discipline treated and years practicing. Potential relevance: The results of this study aid in defining the current usage of different joint therapy medications within equine practice. This knowledge can guide further research as well as education.     

Concurrent or sequential development of medial meniscal and subchondral cystic lesions within the medial femorotibial joint in horses (1996–2006)

Reasons for performing study: Medial meniscal injuries and subchondral cystic lesions (SCL) are known to occur independently within the medial femorotibial (MFT) joint in horses. However, there are no reports of a potential clinical relationship between these 2 types of lesions. Objectives: To: 1) document the concurrent presence or sequential development of medial meniscal and SCL of the medial femoral condyle within the MFT joint; and 2) determine the prognosis with both types of lesions. Methods: Retrospective case series of horses with both a medial meniscal and SCL of the medial femoral condyle identified concurrently or sequentially by radiography, arthroscopy or post mortem examination. Case records and radiographs were reviewed, and a telephone survey of referring veterinarians, owners and trainers was conducted. Results: Twenty‐one horses (9.1% of all horses undergoing MFT joint arthroscopy) were identified to have both a medial meniscal injury and SCL of the medial femoral condyle. Thirteen horses had both abnormalities identified concurrently, 6 developed a meniscal lesion subsequent to SCL debridement, and 2 developed a SCL subsequent to a medial meniscal injury. Only 4/19 horses were classified as successful and returned to their intended use. The severity of the meniscal injury was significantly associated with the severity of lameness but not with outcome. Conclusions: A low percentage of horses may develop both a meniscal injury and SCL of the medial femoral condyle within the MFT joint and have a poor prognosis. Potential relevance: Trauma to the MFT joint may lead to both meniscal and subchondral bone damage of the medial femoral condyle that may be recognised concurrently or sequentially.     

A femorotibial joint swelling with popliteal lymph node enlargement in a Rottweiler

A 9-year-old male Rottweiler was presented to the Veterinary Medical Hospital Montenegro, Porto, Portugal with a large mass medial to the left stifle and radiographic signs of bone lysis involving the proximal tibia, fibula, and distal femur. A fine-needle aspiration was obtained from left popliteal lymph node, which was markedly enlarged. Cytologic examination revealed a highly cellular sample consisting of pleomorphic cells with marked anisocytosis and anisokaryosis and other criteria of malignancy. Some cells contained intracytoplasmic, granular, dark brown material, consistent with hemosiderin. Histologic evaluation of the surgically-excised lymph node revealed a neoplastic proliferation of histiocytic cells, with marked pleomorphism; occasional cells were erythrophagocytic. Mitotic figures were frequently observed, and many were atypical. Histologic findings were consistent with malignant histiocytosis. Necropsy examination confirmed the diagnosis of malignant histiocytosis with systemic involvement affecting most organs examined. This case of malignant histiocytosis case had an atypical clinical presentation, mimicking a musculoskeletal disorder. It underlines the importance of cytology as a simple, inexpensive, rapid and noninvasive complementary exam in routine clinical practice that can permit early diagnosis of the disease and timely selection of the most adequate therapy.     

Ultrasound diagnosis of injuries of the cranial meniscotibial ligament of the medial meniscus

Ultrasonographic examination of the femorotibial joint is now commonly performed for investigating hindlimb lamenesses. Different types of meniscal injuries have been described using this technique. In our practice, the cranial meniscotibial ligament of the medial meniscus (CrMTL‐MM) is the most frequently affected soft tissue structure of the stifle. This article describes the technique to image this ligament, normal images and the ultrasonographic manifestations of desmopathies and enthesopathies of the CrMTL‐MM.     

Ultrasonographic guided injection of the scapulohumeral joint in horses

Intra‐articular injections of the scapulohumeral joint (SHJ) in horses are difficult to perform because of the thick muscles covering the area and a reduced articular space. Ultrasonographic guidance was demonstrated to be helpful to perform intra‐articular injections. This technique applied to the SHJ can be performed in the field with a portable machine. The joint space is firstly imaged in transverse and proximodistal scans. After aseptic preparation of the shoulder area, the probe is placed to image the SHJ space in transverse section and the needle is inserted cranially in the ultrasound beam. The progression of the needle is followed towards the SHJ space, limiting joint injuries and side effects.     

Ruptured capsule of the elbow joint of a draught horse

A cyst filled with fluid was found to be the cause of an enlarged antebrachium in a horse. Communication between the cyst and the elbow joint was demonstrated by: 1) finding, during radiographic examination of the elbow, radiopaque contrast solution instilled into elbow joint within the cyst; 2) finding cytological values in fluid aspirated from the cyst that were similar to those in fluid aspirated from the elbow joint; and 3) finding hyperechoic foci, assumed to be air bubbles, during ultrasonographic examination of the cyst after administration of air into the elbow joint. Communication of the cyst with the elbow joint was confirmed during post mortem examination of the affected limb.     

Multi‐modality diagnostic imaging of a cervical articular process fracture in a Thoroughbred horse including a novel C‐Arm imaging technique

Interpretation of cervical radiographs can be challenging due to the complex anatomy and superimposition of osseous structures on either side of the vertebrae. This report describes the investigation of neck pain in a Thoroughbred gelding following a traumatic fall. Several imaging modalities were used to demonstrate the presence of a fracture of the left cranial articular process of the fourth cervical vertebra (C4), including nuclear scintigraphy, ultrasonography, oblique radiographic projections and a novel cineradiographic technique. Oblique radiographs were superior to standard lateral‐lateral radiographs in both the diagnosis and for monitoring the progression of healing of the articular process fracture in this case.     

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.     

Stifle extension results in differential tensile forces developing between abaxial and axial components of the cranial meniscotibial ligament of the equine medial meniscus: a mechanistic explanation for meniscal tear patterns

Reason for performing the study: To identify potential functional‐anatomical characteristics of the cranial horn attachment of the medial meniscus (MM) that may help explain the pathogenesis of the common tear patterns that have been reported. Hypothesis: Full extension of the stifle generates a significant increase in tensile forces within the cranial meniscotibial ligament (CrMTL) of the MM, which may predispose this structure to injury. Methods: The effect of femorotibial angle (160°, 150°, 140° and 130°) on tensile forces in the axial and abaxial components of the CrMTL was examined in 6 mature cadaver stifles using an implantable force probe. Three additional specimens were used to examine the histological structure of the CrMTL and its connection to the cranial horn of the MM. Results: Full extension of the stifle (160°) resulted in a significantly greater tensile force in the abaxial component of the CrMTL when compared with the axial component (P = 0.001). The tensile force in the abaxial component of the CrMTL increased significantly between 150° and 160° of stifle extension (P = 0.011). The CrMTL appears to be comprised of 2 functional components, which become more visually distinct as the stifle is extended. Histologically, these components are separated by a cleft of highly vascularised, less organised connective tissue, which becomes less prominent at the junction of the ligament and the cranial horn of the MM. Conclusion: A 4‐fold difference in the tensile forces in the 2 functional components of the CrMTL of the MM was observed with full extension of the stifle. Potential relevance: The functional anatomy of the CrMTL may place this region at greater risk of injury during hyperextension of the stifle and, therefore, may provide a mechanistic rationale for the commonly reported meniscal tear patterns in the horse.     

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.