Disorders of the Tarsus and Stifle in Equine PDF

Conditions of the Equine Hock and Stifle Britta Leise, DVM, PhD, DACVS-LA Associate Professor, Equine Surgery & Lameness Louisiana State University VMED5268 Musculoskeletal [email protected] Forelimb vs. Hindlimb Lameness ~80% of hindlimb lameness associated from the fetlock or...

Conditions of the Equine Hock and Stifle Britta Leise, DVM, PhD, DACVS-LA Associate Professor, Equine Surgery & Lameness Louisiana State University VMED5268 Musculoskeletal [email protected] Forelimb vs. Hindlimb Lameness ~80% of hindlimb lameness associated from the fetlock or below Forelimb vs. Hindlimb Lameness ~70% of hindlimb lameness associated from the hock region or above History Occupation of horse Level of work Known history of trauma Duration of lameness Progression of lameness Severity of lameness Conformation Conformation can affect how weight is distributed across the joint Cow hocked = more weight medial aspect of tarsus Base narrow = more weight lateral aspect of tarsus/stifle Sickle hock = more weight plantar aspect of tarsus Post legged = increased stress overall tarsus and stifle Hind Limb Lameness Evaluation Orthopedic examination Hoof testing Baseline lameness evaluation AAEP grading scale Flexion Test Distal limb flexion Full limb flexion (spavin test) Caudal extension/stifle flexion Full-limb flexion Stifle flexion Diagnostic Approach Anesthetic blocks Perineural Intra-articular Radiographs Ultrasound Important additional diagnostic particularly when lameness has been localized to the stifle Nuclear Scintigraphy Better for bone lesions Stifle has poor sensitivity and specificity CT/MRI MRI not an option for stifle Diagnostic arthroscopy Stifle and TC joints only THE TARSUS Anatomy of the Tarsus: Joints Anatomy of the Tarsus: Joints Tarsal Sheath DDFT Calcaneal Structures Calcaneal bursa SDFT Gastrocnemius Associated Ligaments & Tendons Collateral ligaments Cunean tendon Medial view Distal attachment of peroneus tertiu Reciprocal Apparatus Hock must extend with stifle Quadriceps SDF originates on femur and insertion on the calcaneus Gastronemius Stifle flexion results in hock flexion Peroneus tertius originates from extensor process of femur and inserts on the 3rd tarsal bone/MT3 Weight bearing without muscular effort due to medial patellar ligament hooking over medial femoral trochlea Orthopedic Exam: Synovial Effusion Joint Sheat Bursa h Orthopedic Exam Flexion of limb ”Churchill” test Enlargements/periarticular thickening ”Boxy hock” = thickening surrounding medial aspect of distal tarsal joints ”Capped hock” = point of hock/calcaneal thickening Flexion range of motion  TC joint Diagnostic Anesthesia Intra-synovial anesthesia** Tarsocrural joint Proximal intertarsal Talocalcaneal TMT Distal intertarsal joint joint Tarsometatarsal joint Tarsal sheath Perineural/regional Peroneal and tibial Bog Spavin Layman’s term for effusion of the tarsocrural joint Clinical sign NOT a diagnosis Differentiate from periarticular edema/swelling of the tarsus in general Causes of bog spavin OCD Trauma Idiopathic Bog Spavin: Diagnostics Assess degree of lameness AAEP 4 or 5 = fracture Radiographs Arthrocentesis ± anesthesia Viscosity Hemarthrosis Sepsis CT/MRI Diagnostic arthroscopy Osteochondrosis Disease of YOUNG horses Can be bilateral CLINICAL SIGNS: TC joint effusion Mild lameness (grade 1-2) Positive to spavin flexion test DIAGNOSTICS : Radiographs Intra-articular anesthesia (TC joint) Osteochondrosis OCD = most common manifestation Distal Intermediate Ridge of the DIRT TIBIA Lateral Trochlear Ridge of the TALUS Medial Trochlear Ridge of the Talus Medial and Lateral Malleolus Subchondral cystic lesions Distal tibia Proximal MT3 Talus Calcaneus LTR OCD Bone Spavin: Distal Tarsal Joint OA Involves the TMT and DIT joints Typically disease of OLDER horses Juvenile presentation is possible Uni- or bi-lateral Predisposing Factors: Repetitive trauma/use Poor conformation Incomplete ossification at birth Bone Spavin: Distal Tarsal Joint OA Spavin test History: Gradual onset of lameness May “warm out” of lameness Reluctant to perform Clinical Signs: Mild to moderate lameness (grade 1-3) Positive spavin flexion test Positive Churchill test “boxy” appearance to medial aspect of hock Bone Spavin: Diagnostics TMT/DIT intra-articular joint anesthesia Radiographs Nuclear scintigraphy Bone Spavin: Radiographic Findings Bone lysis and subchondral bone sclerosis Bone Spavin: Radiographic Findings Periarticular Osteophytes Bone Spavin: Radiographic Findings Joint space narrowing Curb Desmitis of the plantar ligament nt me Plantar aspect of the proximal l i ga calcaneus to proximal MT4 tar Plan Predisposing Factors: Trauma Kicking walls Poor conformation Sickle hocked Curb Clinical Findings: Swelling or thickening of the plantar lateral aspect of the tarsus Acute = mild grade 1 lameness Chronic = just a blemish Diagnosis Clinical Appearance ** Ultrasound Thoroughpin Tenosynovitis of the tarsal sheath Encloses the DDFT nt me Effusion proximal to calcaneus l i ga Can push side to side tar Plan Often considered a blemish Lameness is associated with DDFT lesions (grade 2-3) Sepsis (grade 4-5) Capped Hock Swelling/periarticular thickening of the calcaneal bursa nt No lameness = blemish secondary to me l i ga blunt trauma Lameness = septic calcaneal bursitis tar Plan Gastrocnemius Subcutaneou bursa s calcaneal A B bursa Intertendonou s calcaneal C bursa A= Gastrocnemius B= Superficial digital flexor From Post et al, 2008 EVJ C= Plantar ligament Capped Hock vs. Septic Calcaneus Bursitis Clinical Findings: Thickened point of hock nt me Septic calcaneal bursa l i ga Puncture wound tar Lameness grade 4-5 lameness Plan Diagnosis Clinical Appearance ** Radiographs Ultrasound Synovial fluid analysis/culture Stringhalt Involuntary hyperflexion of the hock Bilateral or unilateral nt Can be intermittent me l i ga tar Plan Stringhalt Diagnosis = clinical appearance Exaggerated flexion of the hock nt during the CR stride sometimes me hitting the ventral abdomen as the l i ga horse walks tar CAUSES Plan Idiopathic Nerve axonopathy Neurotoxin Catsear, flatweed, dandelion Post-extensor injury Peroneus Tertius Rupture Results from overextension of the tarsus Limb entrapped Rapid overextension – jumping or fast start CLINICAL SIGNS Inability to FLEX the hock Stifle flexes with hock extended Dimpling of the achilles tendon Horse can bear weight but the lower limb may appear “limp” THE STIFLE Anatomy of the Stifle: Joints Femoropatellar (FP) Joint Communicates with MFT ~80% Medial Femorotibial (MFT) Joint Communicates with FP ~80% No communication with LFTJ Lateral Femorotibial (LFT) Joint No communication with FP or MFT  Medial Trochlea of the femur Lateral Trochlea of the femur Patella Medial patellar ligament Lateral patellar ligament Middle patellar ligament Medial collateral ligament Lateral collateral ligament Medial meniscus Fibula Lateral meniscus Tibia Orthopedic Exam Effusion within one or more joints Gait deficits FP joint effusion Lameness can be variable Carriage of stifle slightly abducted Reduced CR phase of stride May dislike traveling downhill Flexion test Positive to caudal extension/stifle flexion Diagnostic analgesia Intra-articular block (3 joints) MFT joint effusion Looking for ~50% or more Synovitis or OA of the Stifle Synovitis =YOUNG horses OA = OLDER horses Secondary to repetitive trauma/use or soft tissue instability CLINICAL SIGNS: Variable lameness (grade 2-3) Joint effusion Stifle flexion positive MFT joint over-represented Synovitis or OA of the Stifle DIAGNOSIS: Intra-articular anesthesia Radiographs Synovitis only = WNL OA Osteophytes / Enthesiophytes Narrowing of the joint space Ultrasound Effusion ± soft tissue injury Diagnostic arthroscopy  Meniscal & Ligamentous Injuries of the Stifle MFC Caudal cruciate Medial Lateral collateral collateral Cranial tibial ligament ligament meniscal ligament X Media meniscus Lateral meniscus Cranial cruciate Cranial tibial meniscal ligament Meniscal & Ligamentous Injuries of the Stifle Clinical signs Moderate to severe lameness Joint effusion Positive to stifle flexion Diagnostics Intra-articular anesthesia Radiographs Ultrasound Diagnostic arthroscopy  Meniscal & Ligamentous Injuries of the Stifle L Normal Affected MC MCL MM MM MFT J MFT J Patellar ligament Desmitis Uncommon cause of lameness Jumping horses over-represented Middle patellar ligament most commonly injured Clinical signs Variable lameness Severe if acute, milder if chronic Periligamentous thickening and pain on palpation Positive to stifle flexion Diagnostics Intra-articular anesthesia Often no significant improvement in the lameness Ultrasound Osteochondrosis SBC OCD Age = young Age = young But non-OC cyst can also been seen with severe OA Lameness = grade 2-3 Lameness = grade 1-2 Positive to stifle flexion Positive to stifle flexion Minimal effusion MFT Moderate/severe FP effusion  Osteochondrosis Subchondral bone cyst Medial femoral condyle DIRT Proximal tibia OCD Lateral trochlear ridge of femur Medial trochlear ridge of femur 🐎 Stifle OC patella Distal has a greater effect on performance than 59% with Cyst vs. 74% controls Case Example Chiquita 2 year-old Miniature Horse 3-week history of stiff gait and occasionally unwilling to move Upward Fixation of the Patella Patella Age More common in younger Medial Patellar horses Ligament MTR Breed Ponies over-represented Predisposing factors Post legged conformation Poor muscular conditioning Upward Fixation of the Patella Patella Clinical signs Variable severity and frequency Severe MTR Stifle locks and limb cannot advance Limb drags the ground with passive flexion Stifle locked Mild to moderate Enhanced by walking down-hill or when transitioning gaits Transition from extension my be Toe drag delayed resulting in a “popping” or sudden release Patella Luxation Patella Patella is luxated out the trochlear groove of the femur Lateral luxation predominates MTR Overall rare condition in horses Severely Can be affected bilateralfoals cannot extend the stifle and will have a characteristic crouching stance Less severe foals will have stiff gait and reluctance to flex the stifle Patella Luxation Patella Age = YOUNG horses Breed = Miniature horses over- represented MTR Predisposing factor = Hypoplasia of the lateral trochlear ridge of the femur DIAGNOSIS Clinical appearance – severe Media Palpation l Hypoplastic Radiographs Ridge Lateral Ridge Media Later l al Ridge Ridge Fibrotic Myopathy Slapping down of the limb at the walk in a CR to CA direction nt me “Limb Due to is thepulled to action limiting the ground” l i ga of the semitendinosus/ tar semimembranous Plan Mechanical lameness Usually presents a chronic condition Diagnosis made on clinical appearance Questions?