Summary
Objective: To determine the incidence and potential risk factors of femoral implant loosening
in the canine Helica® total hip replacement (THR) system.
Method: Sixteen dogs with a Helica THR were included. Medical records were reviewed for signalment
and size of implants. Stem angle, stem collar to lateral cortex distance, tip to cortex
distance, stem collar to lateral cortex distance at a stem angle of 150°, lever arm
distance, and the distance on the diaphysis measurements were calculated from the
one year postoperative radiographs. Three ratios were determined from these measurements
to take into account the size of the femur in relation to the size of the implant.
Femoral implant loosening was identified by radiographic and clinical signs, and confirmed
at the time of surgical explantation. Differences in the successful and fe-moral stem
failure groups were compared using either a students t-test or a Mann Whitney test.
Significance was set at p <0.003.
Results: Six of the 16 dogs had loosening of the femoral prostheses within one year post-implantation.
One dog had evidence of a septic cause for loosening. No significant risk factors
could be identified in this group of dogs with Helica stem loosening.
Clinical significance: Helica femoral stem loosening was a common complication within one year post-implantation
in this group of dogs. No risk factors were identified to potentially decrease the
incidence of loosening. Therefore, due to this unacceptably high complication rate,
the authors do not recommend this model of the Helica THR.
Keywords
Helica - total hip replacement - canine - hip - osteoarthritis