The Tarsus 2021/22 MOD PDF

The tarsus MOD 2021/22 Dr Peter Milner Senior Lecturer in Equine Orthopaedics BEVA 2009 Learning outcomes • To identify pathological conditions relating to the equine tarsus • To discuss the diagnostic procedures involved in localising and defining conditions of the equine tarsus • To be able to...

The tarsus MOD 2021/22 Dr Peter Milner Senior Lecturer in Equine Orthopaedics BEVA 2009 Learning outcomes • To identify pathological conditions relating to the equine tarsus • To discuss the diagnostic procedures involved in localising and defining conditions of the equine tarsus • To be able to deveop a suitable treatment plan for management of conditions of the equine tarsus Introduction • A complicated structure! • BUT... • A site of common pathology in the horse! Tarsal anatomy Tendons/ligaments Peroneus tertius M Tibialis cranialis Dorsal aspect L M Medial collateral ligament Plantar aspect L Lateral collateral ligament Tendons/ligaments Gastrocnemius Superficial digital flexor tendon M L L Deep digital flexor tendon Dorsal aspect Plantar aspect Tarsal sheaths M Calcaneal bursae • Gastrocnemius bursa – Deep between gastrocnemius tendon and tuber calcis • Intertendinous bursa – Between gastrocnemius and SDFT extending distally – Communicates with gastrocnemius bursa • (Acquired) superficial bursae – Between SDFT and skin – “Capped” hock Conditions • • • • OCD/developmental (valgus/wedging) Osteoarthritis Fractures/luxations Soft tissue – Collateral ligaments – Tarsal sheath/DDFT – Calcaneal bursa/SDFT luxation Osteochondritis Dissecans • Distribution – Distal intermediate ridge of the tibia (“DIRT”) – Lateral trochlear ridge – (Medial malleolus) • Clinical signs – Usually young horse (6mo3yr) – Effusion of the tarsocrural joint – (Lameness) – Check other limb/joints! Osteochondritis Dissecans DIRT LTR Osteochondritis Dissecans • Arthroscopy – Usually wait until 11 months+ – With surgery about 75% successfully raced – And in most cases the effusion resolves Removal of fragment done arthroscopically Tarsal bone collapse • Incomplete ossification – Dysmature/premature foal – Neonatal maladjustment – Can present as angular limb deformities • Tarsal bone collapse/deviation • (ddx: septic physitis) • Supportive therapy until matures • Prognosis: poor esp if >30% collapse/fragmentation Osteoarthritis of the small tarsal joints • Common – “Bone spavin” • DIT and TMT (also PIT/TC/talocalcaneal) • Middle-aged to older horses (occ. “juvenile spavin”) • Compression and rotation of small tarsal bones when stops/jumps? • (Conformation) • (Heritable – Icelandic) Severe OA Poor conformation can lead to increased stress on the joint Palpable new bone Osteoarthritis of the small tarsal joints • Clinical examination – Palpable exostoses; squared off toes or commonly NAD! – Lameness (mild-moderate) • unilateral/bilateral • “choppy, stabby gait” • worse on inside/hard surface – Poor performance/“stiff” • “back pain” – Flexion test +ve • Not specific!!! – Tarsocrural effusion esp with Proximal intertarsal OA Osteoarthritis of the small tarsal joints • Diagnostic anaesthesia – Intra-articular versus perineural!! – TMT/DIT anaesthesia • Radiography – Four standard views • DP, LM, DMPLO, DLPMO – Poor correlation with clinical signs (Byam-Cook and Singer 2009) TMT/DIT osteoarthritis Treatment options for small tarsal OA • Systemic medication – – – – NSAID’s PSGAGs/HA Bisphosphonates Nutraceuticals • Intra-articular medication – Corticosteroids +/- HA • Farriery – Improve breakover; lateral width • Chemical arthrodesis – Ethyl alcohol • Surgical arthrodesis – Drilling • Outcome – Conservative: Approx. 60-75% – Arthrodesis: 70-80% fusion after 12 months Tarsal fractures • Malleolar – Can remove arthroscopically • Calcaneal – May be unstable and therefore euthanasia • Small tarsal bones – Conservative or internal fixation Luxations • Usually TMT or PIT -4th tarsal bone prevents DIT sublux. • Severe lameness+ swelling • Stress radiographs • Cast +/- internal fixation • Or euthanasia Soft tissue injuries of the tarsus • Collateral ligament injuries • Tarsal sheath swelling • Calcaneal bursa/lateral luxation of SDFT Collateral ligament injuries - treatment • Swelling ++/TC effusion • Rest • NSAIDs; cold hosing; bandaging • Physiotherapy • Intra-articular medication? • Monitor with ultrasound • Poor px if OA of joint develops Tarsal sheath synoviocoele – “thoroughpin” • Mild or no lameness • Large unilateral swelling in caudodistal crus – Tear in synovial wall – Valve effect • Usually no osseous pathology • Ultrasonography – Effusion+++ with fibrinous deposits – Usually no DDFT lesion • Conservative management – Drainage and corticosteroids – Tends to recur • Surgical management – enlarge communication tenoscopically Calcaneal bursa/lateral luxation of SDFT • Tend to tear medial attachment leading to lateral luxation • Often lots of swelling • Bursal effusion ++ • Horse agitated ++ – May see SDFT “sliding off” point of hock as walks • Ultrasound may visualise tear • Rest, NSAIDs • Surgery (debride tear)