Tibial plateau leveling osteotomy (TPLO) is a popular method for treating the CCLD (CCL Deficient) stifle joint in the dog. Recent studies have shown significant joint mechanical alteration which may be contributory to articular cartilage lesions. One explanation for reported abnormal joint mechanics is that the standard Slocum osteotomy is not based on the mechanical or anatomic CORA. As such, the Axis of Correction (ACA) is not aligned with the CORA resulting in mal-alignment of the anatomic/mechanical axis and secondary translation. The result is caudal displacement of the weight-bearing axis and a focal increase in joint force. Further, TPLO creates a caudal thrust. The long-term effect of caudal thrust is loss of compliance of cranial supporting structures such as the fat pad and joint capsule. Encroachment of the cranial supporting structures (joint capsule) on the cranial articular surface of the medial/lateral femoral Condyles can result in abrasion of the articular cartilage.
Goals of the technique include:
1. Preservation of the proximal tibial epiphysis which allows for application of ancillary stabilizing procedures. The location of the anatomic CORA is such that an osteotomy can be performed which preserves the anatomy of the proximal tibial epiphysis.
2. Alignment of the proximal and distal segment anatomic/mechanical axis and maintaining approximately 30 % of the normal cranial thrust. CORA based osteotomy aligns the anatomic/mechanical axis following rotation. The femoral condyles appear “centered” on the tibial plateau following rotation. The hypothesis is that this will maintain normal stress distribution and kinematics of the stifle.
3. Establish 90 degree plateau/patella tendon angle. An additional advantage of CBLO is that the technique appears to simulate a TTA in that post operatively the patella tendon (PTA) / tibial plateau slope (TPA) angle is approximately 90 degrees. Recommended rotation of the TPA is to 12-14 degrees rather than 5 degrees as with the standard TPLO. This helps preserve the integrity of the stabilizing procedure maintaining long term stability. Additionally, rotation to 12-14 degrees does not generate a caudal thrust as seen with a standard TPLO. The hypothesis is that by eliminating posterior thrust, one will eliminate the cranial abrasion lesions seen with TPLO.
CORA based leveling osteotomy is a unique procedure which combines the advantages of Tibial Plateau Leveling Osteotomy and Tibial Tuberoisty Advancement. The osteotomy is centered on the CORA which achieve alignment of the proximal anatomic axis and distal anatomic axis in contrast to a TPLO which results in caudal shift of the proximal anatomic axis and secondary translation. The TPA/PTA angle lies between 88 degrees and 90 degrees. The osteotomy is stabilized with a TraumaVet specially designed locking plate. Additional advantages of the CBLO include: ease of surgical planning and technique, excellent long term functional results, normal long term appearance of articular cartilage, rapid healing of the osteotomy (6-7 weeks), ability to apply osteotomy in juvenile patients, and application in cases with excessive slope. The course will detail surgical planning, application in simulated bone and cadaver bone, management of complications, and long term outcome.