Effect of cranial cruciate ligament deficiency, tibial plateau leveling osteotomy, and tibial tuberosity advancement on contact mechanics and alignment of the stifle in flexion.
OBJECTIVE
To assess contact mechanics and 3-dimensional (3-D) joint alignment in cranial cruciate ligament (CCL)-deficient stifles before and after tibial plateau leveling osteotomy (TPLO) and tibial tuberosity advancement (TTA) with the stifle in 90 degrees of flexion.


METHODS
In vitro biomechanical study.


METHODS
Cadaveric pelvic limb pairs (n=8) from dogs weighing 28-35 kg.


METHODS
Contralateral limbs were assigned to receive TPLO or TTA. Digital pressure sensors were used to measure femorotibial contact area, peak and mean contact pressure, and peak pressure location with the limb under a load of 30% body weight and stifle flexion angle of 90 degrees . 3-D poses were obtained using a Microscribe digitizer. Specimens were tested under normal, CCL deficient, and treatment conditions.


RESULTS
Significant disturbances in alignment were not observed after CCL transection, although medial contact area was 10% smaller than normal (P=.003). There were no significant differences in contact mechanics or alignment between normal and TTA conditions; TPLO induced 6 degrees varus angulation (P<.001), 26% decrease in lateral peak pressure (P=.027), and 18% increase in medial mean pressure (P=.008) when compared with normal.


CONCLUSIONS
Cranial tibial subluxation is nominal in CCL-deficient stifles loaded in flexion. Stifle alignment and contact mechanics are not altered by TTA, whereas TPLO causes mild varus and a subsequent increase in medial compartment loading.


CONCLUSIONS
Cranial tibial subluxation of CCL-deficient stifles may not occur during postures that load the stifle in flexion. The significance of minor changes in loading patterns after TPLO is unknown.
Comparative Orthopaedics Biomechanics Laboratory, University of Florida, Gainesville, FL 32610, USA.
Stanley E
SE
Kim
Antonio
A
Pozzi
Scott A
SA
Banks
Bryan P
BP
Conrad
Daniel D
DD
Lewis
D000818:Animals; D016118:Anterior Cruciate Ligament / Q000503:physiopathology / Q000601:surgery*; D001696:Biomechanical Phenomena / Q000502:physiology; D004283:Dog Diseases / Q000503:physiopathology / Q000601:surgery*; D004285:Dogs / Q000502:physiology / Q000601:surgery; D010027:Osteotomy / Q000379:methods / Q000662:veterinary*; D016059:Range of Motion, Articular / Q000502:physiology; D013264:Stifle / Q000503:physiopathology / Q000601:surgery*; D013977:Tibia / Q000601:surgery*; D016474:Weight-Bearing / Q000502:physiology