Metacarpus/Metatarsus Conditions 2021/22 PDF

Metacarpus/metatarsus and conditions of the carpus 2021/22 Dr Peter Milner Senior Lecturer in Equine Orthopaedics BEVA 2009 Learning outcomes • To identify common pathological conditions affecting the metacarpal/metatarsal areas • To formulate diagnostic and treatment plans for common pathologica...

Metacarpus/metatarsus and conditions of the carpus 2021/22 Dr Peter Milner Senior Lecturer in Equine Orthopaedics BEVA 2009 Learning outcomes • To identify common pathological conditions affecting the metacarpal/metatarsal areas • To formulate diagnostic and treatment plans for common pathological conditions affecting the metacarpal/metatarsal areas • To describe overall prognosis for common pathological conditions affecting the metacarpal/metatarsal areas Anatomy of the metacarpal/metatarsal region Dorsal Lateral view Mc/Mt IV “splint” bone Palmar/plantar view Suspensory ligament ALDDFT DDFT SDFT SL Origin Mc/Mt III “cannon” bone Body Digital extensor tendon Branches DFTS PAL Investigation of problems of the metacarpus/metatarsus • Clinical examination – Pain/heat/soft tissue swelling – Joint/tendon sheath effusion – Crepitus/pain on percussion • Diagnostic anaesthesia – H4/H6NB – Subcarpal/subtarsal block – Lateral palmar nerve/deep branch of lateral plantar nerve (DBLPN) block • Radiography – Standard projections (DP, LM, DMPLO, DLPMO) • Ultrasonography – Esp. palmar/plantar soft tissues • Advanced imaging (e.g. nuclear scintigraphy/MRI/CT) Image from Castro et al., 2005 Conditions of the metacarpals/metatarsals • Bone conditions – Fractures of the third metacarpal/metatarsal bone – Dorsal metacarpal bone disease – Fractures of the second/fourth metacarpal/metatarsal (“splint”) bones – Exostosis of the second/fourth metacarpal/metatarsal bones (“splints”) • (Palmar) soft tissue conditions – – – – SDFT/DDFT tendinitis ALDDFT desmitis SL desmitis PAL syndrome Fractures of the third metacarpus/metatarsus • Include: Condylar fractures (lateral and medial) Diaphyseal Transverse Proximal articular • Usually single overload injury or external trauma (e.g. kick) • Condylar fractures usually fail due to repetitive strain cycles – Pre-existing changes parasagittal to the ridge Diaphyseal f# – – – – Proximal articular f# Transverse f# Condylar f# Mc/MtIII Fractures of the third metacarpus/metatarsus • Clinical presentation – – – – – Lame (moderate/severe, acute), signalment Swelling/crepitus/pain on palpation/flexion +/- joint effusion Displacement (diaphyseal) Open/closed • Radiography – Standard views plus additional to work out configuration – Do not over collimate! • Lateral tend to exit laterally above physeal scar whereas medial tend to spiral proximally • Advanced imaging – Nuclear scintigraphy, MRI Nonweight bearing Fetlock joint effusion Management options for fractures of the third metacarpus/metatarsus • First aid – Zone 2 external co-aptation • Conservative – Non-displaced, closed, transverse and some proximal articular fractures • Surgical – Condylar fractures, diaphyseal fractures • Euthanasia – Displaced, open, comminuted Conservative management of incomplete nondisplaced, proximal articular fracture of MtIII with evidence of healing 3 weeks later Lateral condylar fracture plus repair Complete displaced mid-diaphyseal fracture plus repair Dorsal metacarpal disease • Also known as “sore shins” or “bucked shin complex” in young racehorses – Excessive cyclic loading results in painful periosteitis as 2yo – Some of these horses go on to develop dorsal cortical “stress” fractures as 3yo • Present with focal pain/swelling/ reduced performance/mild lameness • Diagnostic imaging – Radiography/nuclear scintigraphy • Management – Alterations in training regime – Some refractory cases undergo shockwave or osteostixis(drilling)/screw placement Fractures of the second/fourth metacarpal/metatarsal (“splint”) bones • Common – Often lateral hind splint bone (MtIV) – Usually due to trauma (kick) but distal fractures may be secondary to abnormal stress from fetlock hyperextension • Proximal, mid or distal; open/closed – Proximal f# may communicate with CMC/TMT (joint sepsis) • Radiographic diagnosis • Management – Conservative • Rest; NSAIDs, AB’s; remove small loose fragments; wound debridement • Watch out for sequestration! – Surgical • Partial ostectomy; internal fixation (proximal articular) Exostosis of the second/fourth metacarpal/metatarsal bones (“splints”) • Due to trauma resulting in periosteal bleed then bone formation – Often seen in horses that that “dish” in front – Usually cosmetic but can cause lameness whilst forming or if interfere with SL • Clinical signs – Acute phase: pain, heat, swelling – Chronic phase: bony swelling • Diagnosis – Clinical examination – Radiography (ultrasonography) • Management – Conservative: rest, cold therapy, NSAIDs, local c/s – Surgical: if recurrent or severe (otherwise avoid sx!) SDFT tendonitis • History – Acute lameness; age/discipline Focal anechoic lesions in the SDFT • Clinical examination – Swelling/pain/loss of normal borders – Fetlock sinking – (Carpal sheath/DFTS effusion) • Ultrasound – Core lesion versus generalised changes Generalised SDFT tendonitis SDFT tendonitis - treatment 1. Acute (hours-days) – Limit inflammation • Cold hosing/NSAIDs – Protect limb/reduce further damage • Supporting dressing/box rest 2. Reparative/proliferative phase (days-weeks) – Promote angiogenesis • Tendon splitting, stem cells, PRP, ultrasound – Minimise formation of excessive scar tissue • PRP, stem cells, ultrasound therapy – Early exercise • Positive effect on Type III to type I collagen 3. Chronic modelling (weeks-months) – Controlled exercise programme Monitor progress by repeat ultrasound exam Needle injecting stem cells into the tendon Other tendon/ligament injuries in the distal limb of the horse • DDFT tendonitis – Less common c.f. SDFT/SL – Seen in digital flexor tendon sheath or digit – Also seen in carpal and tarsal sheath Markedly enlarged DDFT in the tarsus on the right • ALDDFT desmitis – Swelling in the proximal palmar metacarpus deeper to SDFT – Tx: rest, cold therapy; NSAIDs – Px: guarded; heals poorly; contractures Enlarged ALDDFT with reduced echogenicity Note that the enlarged ALDDFT is pushing the tendons round to the medial side Suspensory ligament desmitis • Can occur at origin (proximal), body or branch level • Acute: swelling, heat, pain • Chronic: lameness; poor performance (esp. HL) • Dx: palpation; local analgesia (e.g. lateral palmar n.; deep branch of the lateral plantar n.); ultrasound Red circle shows swelling of the medial branch of the suspensory ligament in the hindlimb Ultrasound shows ligament enlargement with poor fibre pattern (dotted line) Treatment – desmitis of the suspensory ligament • Conservative – Cold hosing (acute); rest; NSAIDs – 3-6 months rest – Monitor healing with ultrasound • Surgery – Mainly for chronic desmitis of the proximal portion in the hindlimb • Compartment syndrome alleviated by DBLPN neurectomy and fasciotomy • 60-80% return to function Conditions of the digital flexor tendon sheath and palmar/plantar annular ligament in the horse • Causes – DFTS tenosynovitis – SDFT tear • Manica flexoria – – – – DDFT tear PAL desmitis Combination (sepsis) PAL syndrome in the horse • Clinical signs – DFTS effusion (often marked) – Notching of limb PAL constriction • PAL constriction – Lameness (mild-moderate) – Pain on flexion – +ve response to DFTS analgesia or perineural analgesia (L4NB) • Diagnostic imaging – Ultrasound – Assess tendons/PAL thickness (1-2mm) Reduced echogenicity of the PAL Increased PAL thickness SDFT DDFT Lateral and medial proximal sesamoid bones Treatment – PAL syndrome in the horse • Conservative – Cold hosing/Rest/controlled exercise – Anti-inflammatories • Systemic NSAIDs • Local corticosteroids/HA into sheath Edge of SDFT showing a loose, torn manica flexoria DDFT • Surgical (tenoscopy) – Assess tendons for damage/tears • Remove damaged portions – PAL desmotomy • Relieve compression Cutting the annular ligament from inside the tendon sheath