Vertical Patellar Position in Small-Breed Dogs with Clinically Normal or Medially Luxated Stifle Joints
Date Issued
2011
Date
2011
Author(s)
Chang, Chia-Ming
Abstract
Patellar luxation is one of the most common orthopedic disorders in small-breed dogs. Most of the luxations are congenital, medial, and without trauma history. Affected limbs may appear partial weight bearing to carried lameness, even with skelental deformity. The exact etiology and mechanism of patellar luxation is still not fully understood, and the most popular theory starts in the hip with coax vara and decreased anteversion of the femoral head and neck. Although many surgical treatments were developed according to these proposed etiologies, patella reluxation is a still the most common post-operation complication. The proximal displacement of the patella within the femoral trochlear groove (patella alta) has been suspected to play a role in medial patellar luxation of large-breed dogs. Dogs with patella alta may have a patellofemoral articulation that moves completely proximal to the femoral trochlear groove during stifle extension, and resulting in a loss of the buttressing effects of the trochlear ridges, and increased risk of patellar luxation. To our knowledge, vertical patellar position has not been investigated in small-breed dogs with clinically normal stifles or medial patellar luxation (MPL). Our objective is to define vertical patellar position in a group of small-breed dogs with clinically normal stifles and compare it with a group of dogs with MPL, in the hope to develop a more systemic therapeutic plan for small-breed dogs.
Our study retrospectively reviewed the medical records(2009/01/01-2010/06/01) in National Taiwan University Animal Hospital (NTUAH). Inclusion criteria were small-breed dogs(<10kg) with complete medical records, fully orthopedic exam, and good quality of stifle x-ray. A total of 69 dogs were included in our study, 37 dogs fitted the MPL group (documented MPL, no other orthopedic abnormalities in stifles), 32 dogs were fit in the inclusion of clinically normal stifles (NORM).
Vertical patellar position was defined as the ratio of the patellar ligament length (PLL) to the patellar length (PL), PLL/PL. The PLL/PL value was compared between MPL group and NORM group.
As a result, no significant difference （p=0.3644 > 0.05）of PLL/PL value between MPL group（mean, 1.84） and NORM group（mean, 1.81）was revealed. This result was different from the past study of large-breed dogs, and patella alta may play different roles in MPL among large-breed and small-breed dogs was suspected. Thus, in order to obtain more accurate results and develop a more systemic therapeutic plan, the study of pathogensis of MPL in small-breed and large-breed dogs should be separated.
Subjects
patellar
luxation
dog
surgery
alta
Type
thesis
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