Felis ISSN 2398-2950

Patella: luxation

Contributor(s): Sorrel Langley-Hobbs, Rosanna Marsella, Susan Rackard

Introduction

  • May be medial (more commonly) or lateral (rarely).
  • Degree of patellar instability classified into 4 grades of increasing severity:
    • Grade 1: luxating patella that will not stay out of the groove. 
    • Grade 4: patella permanently luxated.
  • Cause: developmental (rare); trauma (more commonly).
  • Signs: acute/intermittent, unilateral/bilateral hindlimb lameness, usually non-painful (unless patellar cartilage damage/erosion (has caused synovitis)); may be other concurrent pelvic limb abnormalities (eg hip dysplasia).
  • Diagnosis: manipulation of limb; radiography.
  • Treatment: conservative, analgesia, surgery.
  • Prognosis: varies depending on degree of deformity and management.

Pathogenesis

Pathophysiology

Traumatic

  • Trauma causes patella to luxate.

Developmental

  • Developmental abnormality leads to patella deviating from normal plane of movement in patella groove.

Secondary

  • Can occur secondary to femoral fracture malunion with rotational deformity.

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.
  • Rutherford L, Langley-Hobbs S J, Whitelock R J et al (2015) Complications associated with corrective surgery for patellar luxation in 85 feline surgical cases. J Feline Med Surg 17 (4), 312-317 PubMed.
  • Rutherford L & Arthurs G I (2014) Partial parasagittal patellectomy: a novel method for augmenting surgical correction of patellar luxation in four cats. J Feline Med Surg 16 (8), 689-694 PubMed.
  • Loughin C A, Kerwin S C, Hosgood G et al (2006) Clinical signs and results of treatment in cats with patellar luxation: 42 cases (1992-2002). JAVMA 228 (9), 1370-1375 PubMed.
  • Smith G K, Langenbach A, Green P A et al (1999) Evaluation  of the association between medial patellar luxation and hip dysplasia in cats. JAVMA 215 (1), 40-45 PubMed.
  • Davies M & Gill I (1987) Congenital patellar luxation in the cat. Vet Rec 121 (20), 474-475 PubMed.
  • Flecknell P A (1977) Luxation of the patella in cats. Vet Rec 100 (25), 536-537 PubMed.


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