Foal Orthopaedics Past Paper PDF, BEVA 2009

Equine Orthopaedics – 13th January 2022 Foal Orthopaedics Matthew Cullen BSc(Hons) BVSc CertAVP MRCVS Lecturer in Equine Surgery BEVA 2009 Abbreviations • DOD = Developmental orthopaedics diseases • ALD = angular limb deformity (frontal plane deformity) • FLD = flexural limb deformity (sagittal...

Equine Orthopaedics – 13th January 2022 Foal Orthopaedics Matthew Cullen BSc(Hons) BVSc CertAVP MRCVS Lecturer in Equine Surgery BEVA 2009 Abbreviations • DOD = Developmental orthopaedics diseases • ALD = angular limb deformity (frontal plane deformity) • FLD = flexural limb deformity (sagittal plane deformity) Learning Objectives • To recognise clinical signs of orthopaedic infection, ALD and FLD – Understand the importance of carefully examining and radiographing foals – Identify those foals requiring immediate intervention • To establish appropriate diagnostic plan for lame foals or those with ALD or FLD • To develop awareness of most appropriate treatment(s) and timing of treatment Foal orthopaedics • DOD: group of diseases of the musculoskeletal system that occur during the growth phase or development – – – – Angular limb deformities ALD Flexural limb deformities FLD Physitis (non-septic) (Osteochondrosis) • Orthopaedic infections – Synovial sepsis/septic physitis ALD BEVA 2009 ALD – Diagnosis • Must ascertain the following – Congenital = born with ALD • pregnancy problems, premature/dysmature – Acquired = normal at birth; ALD acquired later • age, duration, uni- or bilateral, nutrition – Which joint? – Which direction? – How much deviation? – Bone or joint centred? ALD - Diagnosis • The sooner the better!!! • Clinical Examination – Assessment from distance (standing and dynamic) • Which joint(s)? Which direction? • How much deviation? – Palpate and manipulate • Can you correct the deviation? – Bone or joint centred? • Radiography – Injury (fracture), incomplete ossification of cuboidal bones Angular limb deformities VALGUS – lateral deviation VARUS –medial deviation Angular limb deformity Check each single joint separately Angular limb deformity Origin of deformity • Bone – Physis – Epiphysis – Cuboidal bones • carpus • tarsus – Diaphysis (rare) • Soft tissue laxity ALD – manipulation • Neonatal foal – Can’t straighten limb manually • Bone – Can straighten limb manually • Dysmature • Peri-articular laxity ALD – radiography • Long cassettes • Centred over deviation site • Views: – Dorsopalmar (carpus, fetlock) – Lateromedial (tarsus) ALD – radiography • Plumb lines • Angulation • Intersection = site of deformity • Are joints and physes parallel? Ossification in the neonate Incomplete ossification: High risk of crushing injury to cuboidal bones Complete ossification Ossification in the neonate (Auer & Stick 2011) Incomplete (Auer & Stick 2011) Complete ALD – Case 1 • One-day-old foal • Carpal valgus (10 degrees) • Positive manipulation – i.e. can straighten limb with manual pressure Incomplete ossification of carpal bones • High risk of crushing injury to cuboidal bones • Restricted exercise • Bandage with splint – Light – Digit not within the splint • Repeat radiographs every ~2w • Balanced nutrition • Usually improves unless systemic involvement ALD – Case 2 • 1-day-old foal • Carpal valgus (10 degrees) • Positive manipulation Peri-articular laxity • Controlled exercise to strengthen peri-articular soft tissues • Careful with bandaging • Usually resolves unless other systemic problems Peri-articular laxity 3 days 2 weeks 4 months Acquired ALD • Imbalanced nutrition – Excessive Energy (grain, concentrates) – Mineral imbalance (lack of Cu, excessive Zn) • Genetics (rapid growth) • Trauma – Damage to growth cartilage  abnormal/asymmetric growth (e.g. Salter Harris fracture) – Overload opposite limb ALD – Treatment • Treatment choice depends on: – Aetiology of ALD – Age • Remaining growth potential – Joint involved – ALD severity – Concomitant problems ALD – Treatment • Conservative – Limited exercise – Bandages, splints – Corrective hoof trimming • Medial-lateral foot balance • Glue-on shoes – Limit mare & foal nutrition • Surgery – Growth acceleration – Growth retardation – (Oste-otomy/-ctomy) ALD – Treatment Hoof balance • Valgus Lower lateral • Varus Lower medial ALD – Treatment Hoof balance • Valgus • Varus Medial extension Lateral extension ALD – Treatment Hoof balance • Every 2-3 weeks • Lightly rasp concave side • Avoid drastic changes >> joint problems • Mild cases – as only treatment • Moderate-to-severe cases – combine with surgery ALD – Surgery • Always combined with conservative: – Hoof balance, restrict diet, rest • Stimulate growth (concave side) – Elevate periosteum • Retard growth (convex side) – Bridge the physis ALD - growth acceleration • Periosteal elevation – Perform early during rapid growth – Surgical site • • • • Concave Just proximal to physis Elevate periosteum Does not over-correct ALD – Growth retardation • Moderate & severe cases • Less severe not responsive • Surgery: – Bridge the physis on convex side – Risk of over-correction!! – remove implants once straightened!! ALD – Timing • Each physis has different – period of rapid growth – time of radiographic closure Witte and Hunt, 2009 ALD Prognosis • Good – Early treatment – Physis or epiphysis • Fair to poor – Diaphyseal – Crushed cuboidal bones – Severe angulation – Secondary DJD Flexural Limb Deformity BEVA 2009 Relevant anatomy - SDFT • Superficial digital flexor tendon – origin • distal humerus • proximal radius – insertion • accessory ligament - distopalmar radius (AL-SDFT) • distal PI • proximal PII • Flexion of MCP/MTP joint Relevant anatomy - DDFT • Deep digital flexor tendon – origin • humeral epicondyle • medial olecranon • proximal radius – insertion • palmar PIII – accessory ligament - palmar carpus (ALDDFT) • Flexion of DIP joint Digital hyperextension (tendon laxity) • • • • Neonates Relatively common Laxity of flexor tendons Mild – moderate – With exercise laxity reduces – Corrects in 1-2 weeks • Severe: – Protect heel bulbs/palmar fetlocks Digital hyperextension (tendon laxity) • Usually not associated with bone/tendon pathology • Exercise to strengthen muscletendon unit (swimming) • Moderate/severe: – Palmar/plantar extensions • Bandages: avoid if possible – Light bandages – NO splints… FLDs – Diagnosis • Congenital = born with FLD – Is there a malformation? • Bad prognosis – Radiographs • Acquired = normal at birth, FLD developed later – – – – Age Fast growth Uni- or bilateral Pain? FLD – Aetiology FLDs – Diagnosis • Inspection – Lying down and standing • Palpation & manipulation: – Can it be straightened? – Palpate each one of flexor tendons to check which one/s most affected FLDs Treatment – Conservative • • • • Farriery Physiotherapy Splints Medication – Surgical – depends on • Location • Response to conservative therapy FLD – Conservative treatment • Can foal stand? • Force-extend affected joint – Splints (cast) – Causes pain • Analgesia: very important!! – NSAIDs (risks: GIT ulcers, kidney – GIT protectants, hydration) FLD – Conservative treatment • Oxytetracycline – 3g in 500 ml LRS IV – If needed, can be repeated in 2-3 days – IMPORTANT: hydration (nephrotoxic!!!) – How does it work? • Not via calcium chelation! Oxytetracycline induced a dose-dependent inhibition of collagen gel contraction by equine myofibroblasts AND inhibits tractional structuring of collagen fibrils by equine myofibroblasts through an MMP-1–mediated mechanism. FLDs – Diagnosis DIPJ MC/TPJ Carpus FLD – DIP joint • Conservative treatment – Farriery • lower heel • extended toe shoe – Acrylic – Decrease nutrition – Increase exercise • unless concurrent contraindication – ANALGESIA FLD – DIP joint • Surgical treatment – Desmotomy of AL-DDFT (distal check ligament) • Combine with conservative tx • Prognosis: – good to excellent for grade 1 (< 900) – fair to guarded for grade 2 (> 900) FLD – Fetlock/carpal joint • Palmar/plantar splint – Mould to limb – Change frequently – Careful pressure sores!! • Oxytetracycline • ANALGESIA FLD – Fetlock Surgical treatment: • Palpate which tendon/s most affected when extension is forced: – If SDFT >> AL-SDFT desmotomy – If DDFT >> AL-DDFT desmotomy +/- AL-SDFT desmotomy • Severe cases: – Both Septic Synovitis & Physitis BEVA 2009 Septic arthritis Aetiology •Routes of bacteria access to joint: – Haematogenous – Traumatic – Iatrogenic Aetiology in foals • Systemic disease • Impaired defences • Failure of passive transfer IgG • Sub-infective dose of bacteria Clinical signs • Foals – May be reluctant to stand – Joint effusion • single or multiple – Peri-articular swelling – Lameness • Often progressively increasing • Not always lame initially • Filling of mare’s udder Septic synovitis - Diagnosis • Full history (very important in foals) • Complete physical exam – Other joints – Umbilicus (patent urachus, omphalitis…) • Radiography – Bone involvement (fracture, osteomyelitis) – Radiographs lag behind pathologic changes in bone • Ultrasonography – Umbilicus – Affected joint • Synoviocentesis Septic physitis - Diagnosis • Radiography – Irregular/widened physis – Radiolucency – Soft tissue swelling • Blood culture – Septicaemia – Check other physes/synovial structures Images from Hardy 2006, Clin Tech Equine Pract 5:309-317 Septic synovitis - Diagnosis • Synoviocentesis – Aseptically – Away from wound if present – Collection tubes: • EDTA – Total & differential nucleated cell count • Plain/with culture media – Culture & sensitivity – Total protein • Ideally straight, EDTA can affect reading Septic synovitis - Diagnosis • Usually, septic synovitis when: – – – – Turbid, serosanguineous, reduced viscosity > 20x109 nucleated cell/L > 80% neutrophils Total protein >30-35g/L • Not always • Culture + only ~40% cases & takes ~3 days (Auer & Stick Equine Surgery 2006. p 1051) Treatment • Tx underlying causes – Failure of passive transfer – Umbilical infection • Other infections? – Diarrhoea, respiratory • Lavage of synovial structure • Aggressive antimicrobial therapy • NSAIDs – limited and judicious use Prognosis Depends on systemic involvement • Fair to good – – – – Rapid treatment Single joint No bone involvement Systemically well • Guarded to grave – Long time between dx and tx – >1 joint involved – Bone involvement • epiphyseal or physeal – Concurrent systemic illness • FPT • Neonatal hypoxia • Immune deficiency Prognosis Survival (i.e. discharged from hospital): – Adults: 85% (Schneider et al 1992) – Foals: 45-84% (Schneider et al 1992, Smith et al 2004) Return to athletic function: – Adults: 57% returned to racing (Schneider et al 1992) – Foals: 32-48% raced (septic arthritis, Steel et al 1999, Smith et al 2004) Take home messages • ALD – Classification • • • • – – – – Congenital or acquired Mild, moderate or severe Bone versus soft tissue Valgus versus varus Bone centered – disparity in growth rates across physis Joint centered – dysmature or periarticular laxity Importance of radiographing Slow the fast side (convex); speed up the slow side (concave) – Carpal valgus foot straight ahead • Will result in a fetlock varus – Fetlock ALD • Must act fast – – – Farriery Periosteal elevation Trnasphyseal bridge Take home messages • FLD – Laxity – no bandage – Flexed joint • Splints and bandages • Farriery • Analgesia and oxytetracycline – Can foal do its own physiotherapy? • If so, some exercise is good Take home messages • Synovial sepsis/septic physitis • Different to adults • Identify and address underlying causes – Failure of passive transfer – Omphalophlebitis – Pneumonia – Diarrhoea • Aggressive medical/surgical treatment of the the infected structure Further reading • General – Auer, J.A. and Stick, J.A., 2019. Equine Surgery, 5th edn. Elsevier, St.Louis, Missouri. • ALD – Bramlage, L.R. and Auer, J.A., 2006. Diagnosis, assessment, and treatment strategies for angular limb deformities in the foal. Clinical Techniques in Equine Practice, 5(4), pp.259-269. – Witte, S. and Hunt, R., 2009. A review of angular limb deformities. Equine Veterinary Education, 21(7), pp.378-387.