The tarsal joint, commonly referred to as the hock, is a complex structure in the hind limb of horses, comprising several bones, ligaments, and tendons. It plays a significant role in locomotion, providing stability and flexibility necessary for various movements. The tarsal joint consists of multiple articulations, including the tibiotarsal, proximal intertarsal, distal intertarsal, and tarsometatarsal joints. These components work together to facilitate movement and absorb impact during activities such as walking, trotting, and jumping. This page compiles peer-reviewed research studies and scholarly articles that explore the anatomy, biomechanics, and common disorders associated with the tarsal joint in horses.
Tulamo RM, Bramlage LR, Gabel AA.The case histories and follow-up data for 11 horses with slab fractures of the central or 3rd tarsal bones were examined for information pertaining to the diagnosis, which was difficult to identify, treatment, which was proven ineffective, and the prognosis, which was shown to be poor for return to racing. The purpose of the study was to define the results that could be obtained by nonoperative methods, in an attempt to determine whether surgical treatment was advisable. Nine of the horses were Standardbreds and 2 were Thoroughbreds; all horses were 2 to 4 years old and were being exercised at...
Dewes HF.Fractures of the central tarsal and/or third tarsal bones involving both limbs of six foals are described. Five of the subjects were born either premature or of twin pregnancies. Fractures occurred in the neonatal period and coincided with disablement. Features of behaviour, posture and gait are described, together with gross radiographic findings, bone ash determination and blood chemistry. Lesions observed on the articular faces of tarsal bones recovered from adult horses may have originated during the neonatal-period.
Jakovljevic S, Gibbs C, Yeats JJ.The clinical features, radiographic findings, management and outcome in 13 cases of traumatic fracture of the hock joint are reported. The principal fracture sites were the distal tibial malleoli (5 cases), the fibular tarsal bone (4 cases), the tibial tarsal bone (3 cases) and the proximal end of metatarsal IV (one case). An additional small chip fracture of the central tarsal was noted in 2 cases. Three horses were destroyed immediately after diagnosis, 2 failed to recover following surgical intervention and one remained lame and was destroyed after 3 months' rest. Seven horses recovered com...
Lindsay WA, McMartin RB, McClure JR.Five cases of fracture of the third tarsal bone in racehorses are reported. A method of surgical correction employing a cortical bone screw is described in 2 cases. Healing of the fractures was followed radiographically. Surgical repair permitted both horses to return to competition. The 3 cases treated conservatively suffered a prolonged healing time and excessive new bone formation. They were unable to return to training due to persistent lameness.
Sack WO, Orsini PG.One hundred three equine hocks, obtained from the postmortem room, were used to study the communication and injection of material into the distal intertarsal and tarsometatarsal joints. Excluding the hocks with fused central and 3rd tarsal bones, in 8.3% of hocks injected with low (clinical) pressure and in 23.8% injected with high pressure, the distal intertarsal and tarsometatarsal joints communicated by dissection of the material through 2 internal spaces: the tarsal canal and the space between the combined tarsal bones 1 and 2 tarsal bone 3. A "pop" sometimes felt when high pressure was us...
Gabel AA.A prospective study of the diagnostic results on 25 previously untreated, slightly lame Standardbred horses showed that manipulative tests are of some help in diagnosis. The lameness of each horse was diminished or the horse went lame on the opposite limb after being given an injection of anesthetic in the cunean bursa, and lameness improved more when local anesthetic was injected in the distal intertarsal and tarsometatarsal articulations. In four horses, lesions of the distal articulation of the hock were evident on radiography.
Edwards GB.Results of the clinical and radiographic examination of 8 lame horses with tarsal sheath distension are described. In chronic cases pathological exostoses were identified radiographically in the sustentaculum tali and were demonstrated at post mortem in 4 of the horses which were destroyed. The prognosis and the feasibility of treatment are discussed in the light of these changes and the associated damage found at post mortem in the deep flexor tendon and its sheath. Trauma to the hock was known to have occurred in half the cases and was suspected in the others.
Van Pelt RW, Langham RF, Gill HE.A 2-year-old Standardbred colt with a history of intermittent lameness of the left hindlimb had hemangiosarcomatous involvement of the tarsal synovial sheath. Tibiotarsal and proximal intertarsal synovial sacs were visibly distended and there was pronounced distension of the tarsal synovial sheath. A large, firm mass was palpable in the sheath at about the level of the tuber calcis. Three circumscribed sessile growths were surgically excised from the sheath. The growths were lobulated, moderately vascular, and of fibrotic consistency. Microscopically, the pattern of the hemangiosarcomas appear...
Van Pelt RW.Physical, biochemical, and cytologic properties of synovial fluid from normal equine tarsal joints were investigated. Tarsal synovial fluid was pale yellow, clear, free of flocculent material, and did not clot. Volume varied in direct proportion to individual tarsal joint size. Relative viscosity was related to volume, polymerization and quantity of hyaluronic acid, and protein concentration. Mucinous precipitate quality (hyaluronic acid polymerization) was uniformly high. Results of certain analyses of serum were compared with those of tarsal synovial fluid. Tarsal synovial fluid protein conc...
Compagnie E, Drumm NJ, de Heer N, ter Braake F.To describe an alternative technique and resulting outcomes for arthroscopic removal of osteochondral (OC) fragments from the proximal intertarsal joint (PIJ) using a direct approach without resection of the membrane between the tarsocrural joint (TCJ) and the PIJ. Methods: Retrospective case series. Methods: Client owned horses (n = 11) with Category 1 OC fragments in the PIJ. Methods: Arthroscopic examination of the dorsal pouch of the TCJ was performed with horses positioned in dorsal recumbency using routine portals. A hook probe placed through one of the standard portals was used to l...
Björnsdóttir S, Ekman S, Eksell P, Lord P.Osteoarthrosis (OA) in the distal tarsal joints, bone spavin, is a well known condition which is common in Icelandic horses age 6-12 years. Objective: To determine the nature, location and age of appearance of early radiographic and histological changes in the centrodistal tarsal joint (CD) of young Icelandic horses. Methods: Slab sections from the CD of young Icelandic horses were examined by high detail radiography (age 6 months to 6 years, n = 111) and histology (age 6 months to 4 years, n = 82) to detect and describe the early changes indicative of OA. Horses younger than 5 years were unri...
Dyson S.Proximal suspensory desmitis of the hindlimb was diagnosed using local analgesic techniques and ultrasonography in 42 horses. Subtarsal analgesia resulted in substantial improvement in lameness in 36 of 41 horses in which local analgesic techniques were used. In the remaining five horses lameness was improved by perineural analgesia of the tibial nerve (three) or the tibial and fibular nerves. Intra-articular analgesia of the tarso-metatarsal joint produced a similar degree of improvement in two of 24 horses in which lameness had been improved by subtarsal analgesia. Ultrasonographic abnormali...
Björnsdóttir S, Axelsson M, Eksell P, Sigurdsson H, Carlsten J.The prevalence of degenerative joint disease (DJD) in the distal tarsal joints and the relation between radiographic and clinical signs compatible with the disease were estimated in a population of Icelandic horses used for riding. The material consisted of 614 horses age 6-12 years (mean age = 7.9 years). Radiographs with 3 projections of each tarsus were made and a clinical examination, including palpation of the medial aspect of the distal tarsus and motion evaluation of the hindlimbs before and after a flexion test of the tarsus, was performed. Radiographic signs of DJD in the distal tarsa...
Stephens PR, Richardson DW, Ross MW, Ford TS.The anatomy of the dorsal pouch of the proximal intertarsal joint (PIJ) and its communication with the tarsocrural joint (TCJ) was studied in 15 pairs of hocks from young and mature horses. The mediolateral length of the TCJ-PIJ fenestration was 14 to 29 mm. The potential volume of the dorsal pouch of the PIJ was 3 to 5 ml, and a recess extended 10 to 28 mm medial to the medial commissure of the TCJ-PIJ fenestration. In a correlated clinical study, osteochondral fragments were identified radiographically within the dorsal pouch (category 1) or dorsal joint capsule (category 2) of the PIJ in 17...
Dimock AN, Siciliano PD, McIlwraith CW.Reactive oxygen species (ROS) are capable of degrading many components of the joint in the presence of insufficient antioxidant defences, and as a result have been implicated in the pathogenesis of joint disease in horses. However, to our knowledge, evidence of ROS occurring in diseased joints of horses has not been reported. The objective of this experiment was to compare differences in synovial fluid protein carbonyl content (as a marker of oxidative modification of synovial fluid proteins by ROS) and the antioxidant status of synovial fluid between clinically normal and diseased equine join...
Ramos S, Pinto A, Cardoso M, Alexandre N, Bettencourt E, Monteiro S, Gama LT.Radiographic prevalence and correlation of radiographic findings has not been performed in Lusitano Purebred horses. The aim of this study was to (1) evaluate the prevalence of primary osteoarthritis radiographic findings in Lusitano Purebred horses; (2) to assess correlations between radiographic findings in different joints of the same limb and different limbs; and (3) elucidate the effect of age in the radiographic findings. A radiographic protocol of the stifle, tarsi, fetlocks and distal limbs was done in 98 Lusitanos and the classification of the radiographs was performed using a 0-4 sc...
Ross MW, Orsini JA, Richardson DW, Martin BB.Infectious arthritis of the tarsocrural joint was treated in 13 horses with closed suction drainage through a flat, fenestrated, latex (Jackson-Pratt) drain, broad-spectrum antimicrobial agents, nonsteroidal anti-inflammatory drugs, and bandage immobilization. In 11 horses, arthroscopic lavage and debridement were also performed. Ingress drains were placed for lavage in six horses. Ten horses returned to their previous level of competition or were sound. One horse raced but had lameness of the affected tarsocrural joint and dropped in racing class; one horse was euthanatized because of laminit...
Raes EV, Vanderperren K, Pille F, Saunders JH.Ultrasonographic findings from 100 horses (103 joints) diagnosed with tarsal region pathology are described. Results of standard orthopaedic, radiographic and ultrasonographic examination of the tarsal region were analysed retrospectively. Periarticular swelling and/or synovial effusion was present in 100% of the joints, a wound was observed in 14.5% and 76.7% of the horses that were lame. Abnormalities were detected in 69.7% of joints using radiography and in 100% with ultrasonography. Our results show that the main disease process can affect all aspects of the tarsus. The most common ultraso...
Winberg FG, Pettersson H.Twenty horses with central and third tarsal bone slab fractures, were treated internal fixation. Eighteen of the 20 cases were Standardbred trotters, one was a Thoroughbred racehorse and one a Swedish Warmblood. The central tarsal bone (CT) was involved in 12 cases and the third tarsal bone (T3) in 8 cases. The fractures were treated by lag screw fixation with one (18 cases) or two (2 cases) 3.5 or 4.5 mm cortical screws. Horses were confined to stall rest for one month and then put on a gradually increasing exercise programme. Convalescence time was 3-8 months until the fracture had healed an...
Buchner HH, Savelberg HH, Schamhardt HC, Barneveld A.The kinematic patterns of all limbs of 11 clinically nonlame Dutch Warmblood horses were studied during induced supporting limb lameness to gain insight into the compensation mechanisms horses use to manage lameness and to test kinematic limb variables for their significance as lameness indicators. Using the locomotion analysis system CODA-3, the kinematics of the horses were recorded while walking (1.6 m/s) and trotting (3.5 m/s) on a treadmill. A transient lameness model, evoking pressure on the hoof sole, was used to induce 3 degrees of fore- and hindlimb lameness. Joint angle patterns and ...
Vachon A, McIlwraith CW, Trotter GW, Norrdin RW, Powers BE.Periosteal autografts were obtained from the medial aspect of the proximal portion of the tibia, and perichondrial autografts were obtained from the sternum. Using arthroscopic visualization, each autograft was placed as a loose body into 1 tarsocrural joint in 6 young horses (2 to 4 years old). Horses were hand-walked daily, starting the day after surgery, for a total of 6 h/wk for 8 weeks. Eight weeks after autograft implantation, radiographs were taken of each tarsocrural joint and were interpreted with regard to mineralization in the transplanted autografts. Autografts were then surgically...
Adkins AR, Yovich JV, Steel CM.To evaluate the outcome of 17 horses that underwent surgical arthrodesis of the tarsometatarsal and distal intertarsal joints for treatment of lameness due to osteoarthritis. Methods: Retrospective clinical study using client-owned animals. Methods: Horses with hindlimb lameness were diagnosed with osteoarthritis of the distal tarsal joints following relief of lameness after intra-articular anaesthesia or intra-articular corticosteroid injection. Surgery to stimulate ankylosis was performed on 27 hocks by placing 3 diverging 3.2 mm drill holes approximately 3 cm through the tarsometatarsal and...
Simpson CM, Lumsden JM.A 2-year-old Thoroughbred gelding was evaluated for a grade 3 out of 5 unilateral hind limb lameness. Flexion of the right hock and stifle joints (spavin test) exacerbated the lameness. Response to intra-articular and perineural anaesthesia isolated the source of lameness to the tarsocrural area, despite an absence of tarsocrural joint effusion. Routine radiographic examination of the hock did not reveal any significant abnormalities. Skeletal nuclear scintigraphic evaluation revealed a focal region of increased bone activity in the proximal medial trochlear ridge of the talus. Flexed laterome...
Ley CJ, Ekman S, Dahlberg LE, Björnsdóttir S, Hansson K.To evaluate the use of CT and MRI for guidance of osteochondral sample collection for histologic detection of early osteoarthritic lesions in centrodistal (distal intertarsal) joints of horses. Methods: Right tarsal joints from the cadavers of 24 Icelandic horses aged 29 to 31 months. Methods: CT and MRI were used to evaluate the extent of suspected osteoarthritic changes in centrodistal joints, which were graded with a semiquantitative system. The anatomic regions with the highest grade of change were identified, and osteochondral samples were obtained from these regions. Samples were also ob...
Espinosa-Mur P, Spriet M, Manso-Diaz G, Arndt S, Perez-Nogues M, Roman JL, Garcia-Mata R, Katzman SA, Galuppo LD.To assess the value of 18F-sodium fluoride (18F-NaF) positron emission tomography (PET) for imaging the tarsus and proximal metatarsus and compare it with CT and lameness evaluation. Methods: 25 horses with lameness localized to the tarsal and proximal metatarsal regions that underwent 18F-NaF PET/CT between 2016 and 2021. Methods: 18F-NaF PET and CT images were retrospectively independently evaluated by 3 observers. Standardized uptake values (SUV) were used to characterize 18F-NaF uptake. Correlation between PET and CT findings with subjective and objective maximum (Max-D) and minimum pelvic...
Nocera I, Puccinelli C, Sgorbini M, Bagnoli E, Citi S.In adult horses, specific ultrasound (US) features and reference values have been reported for the appearance of the joint cartilage and thickness according to the type of joint, such as femoropatellar and tarsocrural. The US appearance of the fetlock has been described in several diseases. The present research evaluates the US features of the metacarpal/tarsal-phalangeal joints in healthy racehorses according to age and breed, since no information is available in the literature. Seventy-one fetlocks in 28 healthy horses (15/28 thoroughbreds and 13/28 standardbreds) were assessed. The horses w...
Kraus-Hansen AE, Jann HW, Kerr DV, Fackelman GE.The intra-articular anatomy of 103 equine tarsi was studied by contrast radiography with image intensification and computerized tomography. There was communication between the tarsometatarsal and distal intertarsal joints in 21 of 55 (38%) interpretable tarsometatarsal arthrograms, and in 11 of 48 (23%) interpretable distal intertarsal arthrograms. The difference was not significant. The volume of contrast agent and the pressure of injection did not correlate with communication. Forced injection caused subcutaneous leakage of contrast medium but not communication. Communication occurred via th...
McCoy AM, Ralston SL, McCue ME.Osteochondrosis (OC) is commonly diagnosed in young Standardbred racehorses but its effect on performance when surgically treated at a young age is still incompletely understood. This is especially true for Standardbred pacers, which are underrepresented in the existing literature. Objective: To characterise the short- (2-year-old) and long-term (through 5-year-old) racing performance in Standardbred pacers and trotters after early surgical intervention (<17 months of age) for tarsal OC. Methods: Retrospective clinical study. Methods: The study population consisted of related, age-matched Stan...
Casillas JM, Jacobs CC, Manfredi JM.To identify radiographic locations of soft tissue attachments in the tarsal region of horses and describe any variability in the gross anatomy of those attachments. Methods: 15 cadaveric limbs from 8 adult horses. Methods: 8 limbs were used for dissection and radiography of soft tissue structures, with metallic markers used to identify radiographic locations of soft tissue attachments. The remaining 7 limbs were used to evaluate anatomic variations in the insertion of the tendon of the fibularis tertius muscle. A consensus list of preferred radiographic views for evaluating each soft tissue at...
Goodman NL, Baker BK.Lameness problems constitute a major part of racing Quarter Horse practice. This article considers the diagnosis, prognosis, and treatment of the frequently encountered lamenesses. The main conditions included are synovitis, intra-articular fractures, osteochondritis dissecans, and degenerative joint disease as they relate to the coffin, fetlock, carpal, and tarsal joints. Intra-articular injection techniques and medications are discussed because of the frequency of joint disease. Bucked shins and stress fractures are also reviewed.
Brink P, Smith RK, Tverdal A, Dolvik NI.To quantify concentrations of cartilage oligomeric matrix protein (COMP) and fibromodulin in synovial fluid from the tarsocrural joints (TCJs) of horses with osteochondritis dissecans (OCD) of the distal intermediate ridge of the tibia and determine whether concentrations would change following arthroscopic removal of osteochondral fragments. Methods: 115 client-owned horses with OCD of the TCJ and 29 control horses euthanized for unrelated reasons. Methods: COMP and fibromodulin concentrations were measured in synovial fluid from the TCJs of the affected horses before and after osteochondral ...
Coomer RPC, Terschuur JA, Pressanto MC, Walker I.To assess the efficacy of commercial intra-articular blood-derived allogeneic-induced mesenchymal stem cells (CIMSCs) to treat tarsometatarsal lameness in horses. Methods: This was a retrospective cohort study. Methods: Records from 167 adult light breed horses with bilateral tarsometatarsal lameness. Methods: Horses with tarsometatarsal lameness were retrospectively selected from medical records. Diagnosis followed subjective graded lameness assessment before and after intra-articular analgesia, with graded radiographic tarsal examination. Horses were excluded if they were diagnosed or treate...
Minshall GJ, Wright IM.To describe the presentation, clinical, ultrasonographic and endoscopic features associated with a defect in the tarsal sheath wall, to define the cavity created and to describe a method of treatment. Objective: So called 'false thoroughpins' can be caused by defects in the tarsal sheath wall creating a one way valve effect, removal of which could be therapeutic. Methods: Case records and diagnostic images of horses with synoviocoeles associated with the tarsal sheath were reviewed retrospectively and follow-up information obtained. Results: Synoviocoeles were diagnosed in 15 horses. All were ...
Skelly-Smith E, Ireland J, Dyson S.There have been no detailed descriptions of the radiological appearance of the centrodistal joint interosseous ligament region in horses with and without distal tarsal joint pain. Objective: To describe the normal radiological appearance of the centrodistal joint interosseous ligament region; to determine the prevalence of mineralisation or ossification of the interosseous ligament; and to describe radiological abnormalities surrounding the interosseous space and concurrent radiological abnormalities in the tarsus. The association between interosseous ligament region abnormalities and radiolog...
