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Effect of Tibial Plateau Leveling on Cranial and Caudal Tibial Thrusts in Canine Cranial Cruciate–Deficient Stifles: An In Vitro Experimental Study

Authors

  • Christine C. Warzee DVM,

    1. From the Laboratory for Comparative Orthopaedic Research, College of Veterinary Medicine, Michigan State University, East Lansing, MI.
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  • Loïc M. Dejardin DVM, MS, Diplomate ACVS,

    1. From the Laboratory for Comparative Orthopaedic Research, College of Veterinary Medicine, Michigan State University, East Lansing, MI.
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  • Steven P. Arnoczky DVM, Diplomate ACVS,

    1. From the Laboratory for Comparative Orthopaedic Research, College of Veterinary Medicine, Michigan State University, East Lansing, MI.
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  • Ruby L. Perry DVM, MS, Diplomate ACVR

    1. From the Laboratory for Comparative Orthopaedic Research, College of Veterinary Medicine, Michigan State University, East Lansing, MI.
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  • Presented at the 9th American College of Veterinary Surgeons Symposium, San Francisco, CA, September 30-October 3, 1999; and the 27th Veterinary Orthopedic Society annual conference, Val d'Isère, France, March 5–10, 2000.

  • Supported by the MSU Companion Animal Fund.

  • Address reprint requests to Steven P. Arnoczky, DVM, Diplomate ACVS, Director, Laboratory for Comparative Orthopaedic Research, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824–1314.

Abstract

Objectives— To investigate the effect of tibial plateau leveling (TPL) on tibial subluxation and tibial axial rotation; to determine the minimal tibial plateau rotation (MinTPR) angle that provides stifle stability; and to evaluate caudal cruciate ligament (CaCL) strain following tibial plateau rotation in cranial cruciate ligament (CrCL)-deficient stifles.

Animals— Fifteen canine cadaver hind limbs.

Methods— Tibial subluxation was measured from lateral radiographs in intact, loaded stifles and after sequential CrCL transection, MinTPR, TPL, and CaCL transection. The MinTPR angle was determined using a custom-made hinge plate and compared with the TPL angle. Tibial axial rotation was evaluated in CrCL-deficient stifles before and after TPL. Finally, CaCL strain was recorded in intact, loaded stifles, and following MinTPR, TPL, and tibial plateau over-rotation (MaxTPR) using a force probe.

Results— Cranial tibial subluxation in CrCL-deficient stifles was eliminated with TPL. Tibial plateau rotation, however, induced caudal tibial subluxation, which significantly increased from MinTPR to TPL before and after CaCL transection. The MinTPR angle was 6.5°± 0.9° less than the TPL angle (P < .05). Tibial internal rotation decreased significantly after TPL in CrCL-deficient stifles. Finally, CaCL strain increased with increasing tibial plateau rotation.

Conclusions— This study suggests that, during stance phase, TPL transforms cranial tibial thrust into caudal tibial thrust, thereby stabilizing the stifle in the cranio-caudal plane via the constraint of the CaCL. The increase in CaCL stress, which results from tibial plateau rotation, could predispose the CaCL to fatigue failure and therefore would caution against tibial plateau over-rotation.

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