Approach to Equine Bone and Joint Disease PDF

Approach to Bone and Joint Diseases in Horses Dr Alison Prutton SFHEA MRCVS Acknowledgement: Dr Elaine Horan and Dr Suzy Hall Learning Objectives Students should be able to… » Describe the different types, and the clinical findings of bone and joint pathologies seen in horses » Determine an app...

Approach to Bone and Joint Diseases in Horses Dr Alison Prutton SFHEA MRCVS Acknowledgement: Dr Elaine Horan and Dr Suzy Hall Learning Objectives Students should be able to… » Describe the different types, and the clinical findings of bone and joint pathologies seen in horses » Determine an appropriate diagnostic approach to bone and joint pathologies in horses, including imaging options, and interpret diagnostic findings » Describe how different bone and joint diseases are managed in horses and determine a prognosis 2 Bone Pathologies in horses: Categories »Developmental: »Infectious Angular Limb Deformities Osteitis and osteomyelitis Physitis (Osteochondrosis) »Metabolic »Congenital Fibrous osteodystrophy Skeletal dysplasia »Neoplasia Chondrodysplasia Keratoma »Traumatic »Other Fracture Marie’s Disease Periosteal reaction Sequestrum Subchondral bone injury - Cysts 4 Diagnosis of Bone Pathologies: History Owner observations Signalment - Age, sex, breed Lameness Duration Worsening or Improving Effect of exercise Recent trauma/ Wound Current Diet Medication Previous problems or surgery 5 Diagnosis of Bone pathologies: Observation » Obvious clinical signs https://www.kznbreeders.co.za/Guest27.html 6 Diagnosis of Bone Pathologies: Clinical Examination » Orthopaedic examination Symmetry Muscular atrophy Posture Limb palpation: Heat, pain, swelling » Gait visual Assessment – Lameness » Presence of wound or laceration Assess depth – bone palpable? Discharge – nature? Fragments of bone? Fracture palpable? » Other clinical disease 7 Approach to Diagnosis of Bone Pathologies: Radiography » Each structure should be assessed in terms of Röntgen signs: Size Shape, contour or margins Number Position Opacity (air, fat, water (soft tissue), bone and metal) » Pathology? » Feature of normal anatomy? Be aware of incidental findings: Normal variation vs abnormality » Composite shadow caused by superimposition Artefact or pathological lesion? » Soft tissue swelling can often be appreciated on radiographs » Acquire orthogonal views » Radiograph contralateral limb for comparison 8 Radiographic Findings with Bone Disease 1. Periosteal New Bone Formation Blunt trauma can lead to sub-periosteal haemorrhage Lifting of periosteum away from bone Stimulates production of periosteal new bone Initially less dense and irregular outline Becomes more radiopaque with smooth outline Splint bone exostoses, healing fractures, infection, inflammation, neoplasia, osteoarthritis 9 Radiographic Findings with Bone Disease 2. Sclerosis (Endosteal New Bone Formation) Densification Localised formation of new bone “within bone” Increased bone mass Increased radio-opacity Stress Protection of a weakened area Walling off infection 10 Radiographic Findings with Bone Disease 3. Bone Lysis Destruction of an area of bone Infection Neoplasia Keratoma 11 Radiographic Findings with Bone Disease 4. Osteophyte formation Spur of bone on a joint margin Joint instability Intra-articular disease (eg Osteoarthritis) 5. Enthesophyte formation New bone formation at attachment of tendon/ligament/joint capsule to bone Bone’s response to stress applied through these structures Soft tissue injury 12 Radiographic Findings with Bone Disease Aggressive vs Non-aggressive bone lesions: Characteristics of aggressive bone disease (e.g malignant bone tumour, bone infection…) 1. Destruction of the cortex 2. Character of the periosteal reaction Aggressive lesions have active periosteal reaction- margin of reaction is irregular and not smooth 3. Lack of distinctness of boundary between bone lesion and normal bone (Transition zone) 13 Aggressive vs Non-aggressive: Examples Periosteal reaction Transition zone Cortex destruction 14 Diagnosis of Bone Pathologies: Ultrasonography Useful to assess surface of bone But can ONLY assess bone surface Bone surface should appear smooth, and have uniform thickness of hyperechoic line Useful to image areas which are difficult to radiograph (such as pelvis) Presence of a fracture: Non-displaced break in normal hyperechoic bone surface Displaced fragment – visualisation of hyperechogenic bony structure distracted from underlying bone Can assess concurrent soft tissue damage which may be present Evaluate depth of any wounds present 15 Diagnosis of Bone Pathologies: Nuclear Scintigraphy Radioisotope (Technetium 99m) is injected intravenously Increased Radiopharmaceutical Uptake (IRU) in areas where there is increased osteoblastic activity High sensitivity but low specificity imaging modality » Indications Fracture suspected but no localising clinical signs and negative radiographs To assess animals with obscure lameness issues Unable to localise with diagnostic analgesia, episodic lameness Evaluate horses with poor performance Evaluate inaccessible areas e.g pelvic region in the horse » Requires very careful interpretation and knowledge of “normal” areas of increased bone turnover 16 Nuclear Scintigraphy Allows functional evaluation of bone at time of imaging Radiographs show bone activity that has occurred in the past Does not differentiate between different types of bone disease Can’t distinguish between a fracture, neoplasia, infection, etc 17 Diagosis of Bone Pathologies: Computed Tomography » A 3D image is generated from a large series of 2D radiographic images taken around a single axis of rotation » Advantage: Structures are not superimposed on top of each other Facilitates examination of complex structures e.g skull Viewing image in several planes helps to better delineate fracture orientation- useful for planning fracture repair 18 Diagnosis of Bone Pathologies: Magnetic Resonance Imaging » Allows better imaging of soft tissue structures (less detailed examination of bony structures – lower resolution compared to radiography, CT, U/S) » Dynamic imaging modality; identifies intra-osseus fluid » Only distal limb possible in horses 19 Bone Pathologies: Common conditions Treatment & Prognosis Developmental Bone Disease » Angular Limb Deformities » Physitis » (Osteochondrosis) » Cuboidal bone malformation (premature foals) » Sequelae→ predisposes animal to degenerative joint disease later in life Therefore: early intervention important to reduce long term damage to joint 21 Angular Limb Deformities Valgus » Lateral deviation of limb Varus https://www.americanfarriers.com/articles/9864-the-farriers- role-in-correcting-angular-limb-deformities?v=preview » Medial deviation of limb » Carpi & fetlocks most commonly affected » ‘Windswept foals’ Epiphyseal/Physeal dysplasia » Deviation cannot be corrected manually Ligamentous laxity » Deviation can be corrected manually 22 Angular Limb Deformities Treatment » Surgical or non-surgical? » Non-surgical Rest, splints and casts, bandages, hoof manipulation » Surgical Periosteal stripping to stimulate growth (lateral aspect if valgus deformity) Growth retardation by bridging the growth plate (medial aspect if valgus) » Anti-inflammatories » Analgesia » Nutrition Reduction of body weight Reduction of energy in diet Correct Ca:P ratio in diet » Prognosis: dependent on severity. Early intervention improves prognosis 23 Physitis »Inflammation of the growth plate » Irregularly thickened growth plate » Metaphyseal sclerosis » Periosteal new bone formation 24 Infectious causes of bone disease: Osteitis and osteomyelitis » Inflammation of bone caused by pyogenic organisms » Inflammation + necrosis + removal of bone + compensatory production of new bone » Osteitis – bone involved (eg *Pedal osteitis*) » Osteomyelitis – bone marrow and bone involved » Aetiology: Haematogenous, Penetrating trauma (puncture wound or laceration), Complication of fracture or surgery (+/- implants), Local extension from septic arthritis » Clinical signs: increase in lameness local swelling painful response on palpation discharge from wound/incision site +/- granulation tissue +/- pyrexia 25 Osteitis and Osteomyelitis Radiographic findings Soft tissue swelling New bone formation Bone resorption Possible consequence of bone infection = Sequestrum - piece of dead radiopaque bone Involucrum - surrounded by an area of lucent granulation tissue Area of sclerosis may be surrounding (to wall off the infection) Sinus - radiolucent tract between infected bone and skin 26 Sequestrum Formation 27 Osteitis and Osteomyelitis Treatment » Systemic antimicrobial therapy Must have good bone penetration, broad spectrum Long course required » Analgesia » Wound care: debridement and lavage » Curettage Debridement of bone and soft tissue to remove necrotic debris, purulent material and avascular bone » Implant removal if relevant » Bone graft? » Intravenous regional perfusion (IVRP) (Amikacin) Prognosis » Variable; depends on severity and chronicity of infection 28 Fractures » Radiolucent line +/- periosteal and endosteal new bone » Hairline fracture may not become visible for 10-14 days Osteoclastic activity breaks down bone The fracture line then becomes visible 29 Joint Disease in horses: Joint Disease in Horses » Osteoarthritis (Degenerative Joint Disease) » Septic arthritis » Osteochondrosis, Osteochondritis Dissecans (OCD) » Synovitis » Immune-mediated polyarthritis » *Definitions, pathophysiology and pathogenesis largely covered in SA lecture* 31 How do we recognise joint disease? » Clinical Findings » Imaging » Synoviocentesis » Direct Visualisation - Arthroscopy » Diagnostic analgesia may be used to localise site of pain 32 Clinical Examination Findings History & Signalment Clinical examination Observation Palpation Pain/Discomfort Soft tissue or bony swelling Joint effusion Range of movement reduced Crepitus Muscle atrophy (disuse) General Clinical Examination- pyrexia? Gait assessment - Lameness 33 Signalment, Onset & Clinical Signs » Osteoarthritis: Older animal Gradual onset Lameness mild to moderate to severe depending on stage of disease Lameness may improve with exercise Reduced ROM and bony changes may be palpable in advanced cases » Septic Arthritis: Any age **Wound near a joint Acutely and severely lame +/- pyrexia » Osteochondrosis Young animal **Joint effusion Often do not present with lameness 34 Approach to Diagnosis of Joint Disease: Imaging *Approach as described for bone pathology in terms of radiography & CT* o (periosteal new bone, sclerosis, lysis, osteophyte formation…) o See examples for specific conditions for more detail Ultrasonography: o Examination limited to peripheries of joint o Can assess degree of joint effusion o Cartilage lesions which are not visible on radiographs may be picked up by ultrasonography o E.g. Stifles – meniscal injury o Assess wounds o Follow tracts o Establish if foreign material present? o Assess associated soft tissue damage o Septic arthritis in foals/calves - Scan umbilicus to look for route of infection (systemic sepsis) 35 Other Imaging Modalities » Scintigraphy Assess areas of increased bone turnover around joint Subchondral stress related bone injury Allow early diagnosis of subchondral bone change in joint disease before pathology becomes radiographically apparent Early diagnosis of OA Will NOT differentiate between types of bone disease » Magnetic Resonance Imaging Useful to assess concurrent soft tissue damage which may be resulting in joint instability 36 Synoviocentesis Essential in diagnosis of septic arthritis Also useful to detect inflammation within the joint (synovitis) Aseptic collection NOT through contaminated skin/wound Test Cytology Culture & Sensitivity Contrast study Contrast agent injected into joint and radiographs taken Contrast agent will be visible leaking out of wound on radiographs if both communicate Pressure Test: Distend joint with sterile saline Saline will exit through the wound if joint and wound communicate 37 Synoviocentesis Normal Appearance Pale yellow/transparent, high viscosity Low in white bloods cells and total protein Abnormal appearance Serosanguinous/turbid/reduced viscosity High white blood cells and total protein >90 % Neutrophils 38 Arthroscopy Allows direct visualisation of joint Diagnostic and therapeutic (McIlwraith et al, 2015) 39 Joint Disease: Common conditions; Treatment and Prognosis Osteoarthritis (Degenerative Joint Disease) Which joints are commonly affected in horses? » Small tarsal joints (“Bone Spavin”) Tarsometatarsal joints* Distal intertarsal joints Proximal intertarsal joints » Distal interphalangeal joints » Proximal interphalangeal joint » Metacarpophalangeal joints » Carpal joints » Stifles » Cervical spine (articular facets) 47 Osteoarthritis: Radiographic Findings » New bone formation and/or periarticular osteophytes » Enthesophytes » Erosion of subchondral bone surface Subchondral sclerosis » Subchondral cyst formation » Reduced joint space/joint narrowing » Increased synovial mass (swelling of soft tissues) » Mineralisation of tissues 48 Osteoarthritis: Radiography 49 Osteoarthritis: Management Aims: 1. Provide analgesia 2. Control articular inflammation 3. Limit damage to articular tissues 4. Promote healing of damaged cartilage 50 Osteoarthritis: Management 1. Physical Therapy » Acute: rest, cold therapy, early mobilisation » Chronic: Gentle exercise, hydrotherapy 2. Anti-inflammatory/Analgesia » Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) Most commonly used treatment Concerns with toxicity- gastrointestinal, renal Topical NSAIDs? 51 Osteoarthritis: Management 3. Corticosteroids » Commonly used intra-articularly in horses (cf SA) Sport horses can compete (after withdrawal period) » Intra-articular Methylprednisolone acetate (MPA) Triamcinalone acetonide (TA) » Reduction in inflammation within the joint ~6 months (varies depending on degree of pathology) Repeated as required » Care – risk of laminitis? Avoid in ‘laminitis-prone’ individuals Avoid overdosing 52 Osteoarthritis: Management 4. Adjunctive Treatments (limited evidence basis to most) o Hyaluronic Acid - IV or IA o Important component of synovial fluid o Lubricant, Anti-inflammatory, Chondroprotective o Often administered along with corticosteroids intra-articularly o Pentosan polysulphate sodium (Cartrophen) - IM o Reduction in articular cartilage fibrillation o Once weekly for 4 weeks o Bisphosphonates - IV or IM (Tildren or Osphos) o Inhibitor of bone resorption (osteoclasts) o Slow down progression of OA o Licensed for OA of the small tarsal joints & Navicular disease 53 Osteoarthritis Management… 5. More adjunctive treatments… » Autologous conditioned serum - IA IRAP- Interleukin 1 Receptor Antagonist Protein Counteracts inflammatory protein IL-1 produced in joint synovitis Successfully used in humans to treat OA Reduces joint inflammation 3 treatments, 7-10 days apart Better for synovitis than advanced OA » Platelet Rich Plasma - IA Enrichment of platelets and degranulation to release growth factors Evidence to support use in younger patients for joint tissue healing » Bone Marrow derived Mesenchymal Stem Cells - IA Promote repair and regeneration May participate in repair of cartilage May be beneficial in cases with intra-articular soft tissue injuries to promote healing » Polyacrylamide hydrogel - IA Integrates into joint capsule and tissue via vessel in-growth Creates a cushion-like effect in the joint Preservation of joint cartilage and aid regeneration 54 Osteoarthritis: Management… » Nutraceuticals (Joint supplements) Glucosamine HA Chondroitin Sulphate » Acupuncture » Diet » Surgery- Arthrodesis/facilitated ankyloses Fusion of the joint Ethanol injection for bone spavin – Chemical fusion Ethics? 55 Septic Arthritis Contamination of a synovial cavity with bacteria » Trauma Laceration or puncture wound » Iatrogenic Intra-articular injections/surgery-arthroscopy » Haematogenous Young animals-foals/calves dog » Extension Local soft tissue infection or osteomyelitis » *See SA lecture for pathogenesis* » *True emergency in equine practice* 56 Septic Arthritis Pathogenesis » Inflammatory response Vasodilation and influx of neutrophils Release of inflammatory cytokines/enzymes » Fibrin clot traps bacteria Protect the bacteria Reduce synovial nutrient exchange » Cartilage destruction and extension to subchondral bone » Results in PAIN and swelling of the affected joint » →Ultimately can result in degenerative osteoarthritis 57 Septic Arthritis 58 Septic Arthritis: Treatment Joint lavage (ASAP!) » Remove bacteria/debris/inflammatory mediators » Large volume sterile polyionic solution – dilution effect » Arthroscopic debridement and lavage = “Gold Standard” Superior visualisation Remove debris/foreign material and adhesions Synovial biopsy for culture/sensitivity £££ » “Through and through needle lavage” Basic treatment – may not resolve infection but may be only option if finances limited » More than one joint lavage may be required 59 Septic Arthritis: Treatment *In addition to joint lavage: » Systemic Antibiotics Broad spectrum – PPG & Gentamicin initially Ideally based on culture and sensitivity » Intra-articular Antibiotics High concentration of local antibiotics » Intravenous Regional Perfusion - IVRP » Analgesics NSAIDs to reduce swelling and inflammation May mask signs of lameness so close monitoring required 60 Septic Arthritis: Prognosis » Early diagnosis and aggressive management achieve best outcome » Affected by concurrent damage > worsens prognosis Osteomyelitis Soft tissue damage (tendon/ligament) or infection » Care – Most present NWB lame, but *may present sound or with only low- grade lameness if joint is open and draining* » If left untreated- severe chronic lameness and DJD → Euthanasia 61  Osteochondrosis/OCD Developmental disorder Osteochondrosis: Defect or failure in endochondral ossification > Focal ischaemic necrosis of cartilage initiated by necrosis of cartilage canal blood vessels Osteochondritis Dissecans (OCD): Fragment separates from adjacent subchondral bone Osseus cyst-like lesions (OCLLs) Retention of a focal area of degenerate cartilage within the subchondral bone (subchondral bone cyst) Long term: Leads to OA *See SA lecture for predisposing factors* All relevant, but trauma perhaps more important in horses cf SA Wright and Minshall 2005 62 Osteochondrosis and OCD: Pathogenesis Trauma Body size and growth rate Nutrition Multifactorial High plane of nutrition Calcium and phosphorous ratio OCD associated with high phosphorous in diet Copper deficiency Gender More common in males? Genetic Environment Important Predisposition Exercise Cartilage canals Ischaemic necrosis of vessels providing nutrition to cartilage Toxins Zinc and Cadmium 64 Osteochondrosis & OCD: Radiographic Findings » Flattening of joint surface » Mineralised cartilage flap seen within subchondral bone defect ‘Joint mice’ (OCD) » OCLL/Subchondral Bone Cysts » Joint Effusion » Know the predilection sites 65 Osteochondrosis & OCD: Ultrasonography 66 Osteochondrosis & OCD Management » Long term consequences- predisposes joint to development of osteoarthritis Free floating fragments can result in extensive cartilage damage OCD fragments may become lodged in synovial membrane Conservative: » Dietary modification - reduction in dietary energy intake Reduce growth rate Reduce body weight » Rest » Analgesia » Intra-articular medication with chondroprotectants +/- corticosteroids Surgery: » Arthroscopic debridement of lesions and removal of cartilage flaps » Dependent on: Age: lesions may heal in younger animals Frequency and severity of lameness: if there are clinical signs of lameness surgery is often indicated Radiographic appearance of lesion: Appearance of large defects or joint mice require surgery » Prognosis dependent on site and severity of lesion and presence of secondary degenerative joint disease 67 Useful resources » Butler, J.A., Colles, C.M., Dyson, S.J., Kold, S.E. and Poulos, P.W., 2017. Clinical Radiology of the Horse. John Wiley & Sons. » Nedergaard, A., Carlsson, L.E. and Lindegaard, C., 2024. Evidence of the clinical effect of commonly used intra‐articular treatments of equine osteoarthritis. Equine Veterinary Education. » Ludwig, E.K. and van Harreveld, P.D., 2018. Equine wounds over synovial structures. Veterinary Clinics: Equine Practice, 34(3), pp.575-590. » Ross, M.W. and Dyson, S.J., 2010. Diagnosis and Management of Lameness in the Horse. Elsevier Health Sciences. » Witte, S. and Hunt, R., 2009. A review of angular limb deformities. Equine Veterinary Education, 21(7), pp.378-387. » Wright, I. and Minshall, G., 2005. Diagnosis and Treatment of Equine Osteochondrosis. In Practice, 27(6), pp.302-309. 68