equis - Articles
Patella: fracture
Introduction
- Cause: direct trauma - kick, hitting fence while jumping.
- Signs: acute moderate → severe hindlimb lameness Musculoskeletal: gait evaluation, stifle effusion, crepitus, soft tissue injury and swelling.
- Diagnosis: radiography Hindlimb: radiography, intrasynovial anesthesia Hindlimb: joint anesthesia, arthroscopy Joint: arthroscopy - overview, ultrasonography Ultrasonography: musculoskeletal.
- Treatment: conservative, surgery - partial patellectomy or reduction and screw fixation.
- Prognosis: good for conservative management of non-displaced fractures or surgical management; poor if conservative management of displaced fractures or where concurrent degenerative joint disease Musculoskeletal: osteoarthritis (joint disease).
Presenting signs
- Hindlimb lameness, usually unilateral and acute onset.
- Evidence of trauma in stifle region and possible soft tissue injuries.
- Swelling of stifle region and/or femoropatellar joint.
Acute presentation
- Acute onset, hindlimb lameness, usually unilateral and severe.
Breed/Species predisposition
- Thoroughbred Thoroughbred - hunters, showjumpers.
- Quarterhorse Quarterhorse.
Cost considerations
- Costs of diagnosis and treatment.
- Costs of loss of use.
Pathogenesis
Etiology
- Usually, the consequence of direct trauma including kicks or impact from hitting a hard object during jumping.
Predisposing factors
General
- Eventing.
- Hunting.
Specific
- Direct trauma to cranial stifle region.
Pathophysiology
- Jumping fence → stifle fully flexed, patella held against femoral trochlea → direct trauma, eg stifle strikes fence → fracture of patella Musculoskeletal: fracture.
- Most common fracture after this incident is a parasagittal fracture of the medial part of the patella. Possibly related to the more prominent medial trochlear ridge of the distal femur cleaving off the medial side of the patella. The fracture line may occur anywhere from the midline medially, but smaller more medial fragments are the most common.
- Transverse fractures are much less common and arise from direct trauma plus increased tension through the quadriceps apparatus at the time of impact – stifle partially flexed. They are usually horizontal and in the middle of the patella. These fractures are more likely to distract.
- Chip fractures are also uncommon but are usually due to direct trauma. They can be medial, lateral, or proximal.
- Distal osteochondral patellar fragmentation may be a degenerative disorder rather than a direct fracture and has been most regularly recognized as a consequence of medial patellar desmotomy Medial patellar ligament: desmotomy.
- All fractures can trigger off osteoarthritis of the femoropatellar joint if inadequately treated Musculoskeletal: osteoarthritis (joint disease).
Timecourse
- Acute - for direct trauma.
- Chronic - for degenerative joint disease post-undiagnosed or untreated fracture.
Diagnosis
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Treatment
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Prevention
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Outcomes
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Further Reading
Publications
Refereed papers
- Recent references from PubMed and VetMedResource.
- Vautravers G et al (2018) Articular sagittal and medial parasagittal patellar fracture repair using lag screws in two adult horses. Equine Vet. Educ. 30 (1), 31-36 WileyOnline.
- McLellan J, Plevin S & Taylor E (2012) Concurrent patellar fracture and lateral collateral ligament avulsion as a result of trauma in three horses. JAVMA 240 (10), 1218-1222 PubMed.
- Marble G P & Sullins K E (2000) Arthroscopic removal of patellar fracture fragents in horses - five cases (1989-1998). JAVMA 216 (11), 1799-1801 PubMed.
- Dyson S et al (1992) Clinical and radiographic features, treatment and outcome in 15 horses with fracture of the medial aspect of the patella. Equine Vet J 24 (4), 264-268 PubMed.
- McIlwraith C W (1990) Osteochondral fragmentation of the distal aspect of the patella in horses. Equine Vet J 22, 157-163 PubMed.
- Parks A H & Wyn-Jones G (1988) Traumatic injuries of the patella in five horses. Equine Vet J 20, 25-28 PubMed.
Other sources of information
- McIlwraith C W, Nixon A J & Wright I M (2015) Diagnostic and Surgical Arthroscopy in the Horse. 4th edn. Mosby Elsevier, USA.
- Fowlie J G, Stick J A & Nickels F A (2012) Patellar Fractures. In: Equine Surgery. 4th edn. Eds: Auer J A & Stick J A. Elsevier Saunders, USA. pp 1434-1436.