SURGICAL
MANAGEMENT OF THE CRANIAL CRUCIATE
INSUFFICIENT DOG UTILIZING TIBIAL PLATEAU
LEVELING OSTEOTOMY (TPLO)
PAUL M.
SHEALY MS, DVM, MS, DIPLOMATE, ACVS
VETERINARY SPECIALISTS OF THE SOUTHEAST
THE ADVANCED VETERINARY DIAGNOSTIC AND TREATMENT CENTER
ANIMAL REHABILITATION CENTRAL"
The science behind the evaluation and surgery of dogs with cranial cruciate insufficiency continues to be dynamic within the field of veterinary medicine. Beginning with Paatsama in 1952, the pathogenesis of cruciate pathology in the dog was described, and surgical techniques were developed and utilized for stifle stabilization including Fascial Strip (Paatsama, 1952), Lateral Retinacular Imbrication (DeAngelis, 1970), Fibular Head Transposition (Slocum, 1971), Posterior Capsulorrhaphy (Hohn, 1973), Modified Lateral Retinacular Imbrication (Flo, 1975), Over-the-Top (Arnoczky, 1979), Ligament Transplants (Milton, 1982), Under-and-Over (Hulse, 1983), and Fibular Head Advancement (Smith, 1984). Both intra-capsular and extra-capsular techniques utilizing various modifications and materials for cruciate instability, although most often better than conservative management, have been inconsistent in returning dogs to preinjury status regardless of size, breed or activity. In 1983, Slocum described cranial tibial thrust as a primary force in the canine stifle. Subsequently in 1993, he introduced an alternative biomechanical and surgical approach to cruciate ligament insufficiency based on cranial tibial translation.(1) Tibial Plateau Leveling Osteotomy (TPLO) is a relatively new and very innovative surgical procedure for cranial cruciate insufficiency. As all new procedures, there is only early objective scientific published data.(,2,3,4,5,6,7) The intent of this presentation is to provide basic understanding of the procedure, objective data that is available, and author's experience with the clinical results of the procedure over the past 6 months. Historical and current surgical techniques are based on the traditional
or passive model of stifle joint stability, and rely on stabilizing
the stifle against cranial drawer movement. The active model expands upon the passive model to include biomechanics
of the stifle integrating the function of forces created by muscles
and weightbearing. Muscles associated with the stifle create force,
moment, and equilibrium. The forces created by muscles of stifle flexion
and extension participate in the balance of moments around the instant
center of motion of the stifle. In a recently reported study, tibial plateau angles(TPA) were compared in normal dogs with dogs with naturally occurring cranial cruciate ligament (CrCL) injuries.(4) Dogs with naturally occurring CrCL injuries (mean 23.76 degrees) had a significantly (P<.01) greater TPA than normal dogs (mean 18.10 degrees) of similar age and body weight. Additionally, the TPA of the most commonly affected breeds (Labrador Retrievers, Golden Retrievers, and Rottweilers) in this study was significantly (P<.01) greater than that of dogs of the same breed without CrCL injuries. The conclusion of the study was that greater TPA increases the stress applied to the CrCL predisposing it to injury. In an report currently in review for publication, the TPA of a clinical population of dogs with diagnosed CrCL rupture undergoing TPLO were compared to a control Greyhound population.(5) TPA angles of dogs with CrCL insufficiency ranged from 15 degrees to 42 degrees with a mean of 24.96 degrees. Comparatively, tibial plateaus of the control population ranged from 16 degrees to 25 degrees with a mean of 20.84 degrees. These angles compared favorably with the results of the aforementioned study.(4) A significant (P<0.001) difference between the TPA angles of the clinical and control groups was found supporting that the conformation of the tibial plateau plays a integral role in the pathogenesis of CrCL disease.(5) Thus decreasing the slope of the tibial plateau reduces the CTT, and incrementally increases the dependence on the caudal cruciate ligament as a passive restraint to caudal tibial subluxation.(3) The objective of traditional surgeries, based on the passive model,
is the elimination of cranial drawer sign. The objective of the tibial
plateau leveling osteotomy is neutralization of the cranial tibial thrust
and not complete elimination of the drawer sign. The stifle is
redesigned The success of the TPLO procedure has been based on the return of full flexion of the stifle, muscle mass and limb function, and the apparent lack of joint inflammation or progressive degenerative joint disease within the joint. The persistence of cranial drawer after a TPLO is not a valid test for stifle stability and is not a SIGN OF FAILURE. The procedure has provided performance dogs the ability to return to normal function handling the highly competitive demands of their sport or work. Thus, the family pet is even better able to participate in normal daily activities without restriction of activities or residual lameness as often experienced with traditional surgical procedures. The procedure involves specific radiographic positioning prior to surgery
for critical calculations In a recent report of 125 TPLO procedures on 112 dogs, the mean preoperative tibial plateau slope was 25.1 degrees (range 15-33).(7) The mean postoperative tibial plateau slope was 7 degrees (range 1-14) with a mean change in slope of 18.1 degrees (range 9.5-29). Major complications occurred in 4% of the cases. Four of the five complications developed in the first 37 procedures performed. These complications included tibial crest fracture (n=3) and osteomyelitis (n=2). Potential risk factors for the development of postoperative complications included surgeon inexperience, technical errors, small tibia size relative to blade size, bilateral pelvic limb pathology, and inadequate protection of the surgical wound from the patient during wound healing.(7)
In our first 40 cases, there have been no major postoperative complications. It is our belief that attention to technical detail and established postoperative physical therapy protocols have resulted in excellent clinical results devoid of reported complications. One patient developed wound dehiscence 3 weeks postopeatively. Culture and sensitivity revealed no pathologic organisms. Surgical reconstruction of the wound resulted in complete healing. Patients are typically weight bearing the day after surgery and are very sound by 4 weeks. Lameness is not apparent by 4 -12 weeks, and patients are back to normal activity within 16 weeks. Previously operated stifles in which traditional methods of stabilization were used have undergone TPLO with results similar to those having TPLO performed initially. Although the procedure is more involved and requires a significant investment in time training, equipment and supplies, the cost is not significantly more in our practice than traditional surgery and physical therapy because the cost is fixed to include evaluation, all preoperative and postoperative radiographs, surgery, hospitalization (24-hour care), medications, necessary follow-up through 16 weeks, and physical therapy. Considering the cost and the rehabilitation, the results certainly justify the additional expense for the procedure. Client satisfaction remains extremely high, and client awareness of and demand for the procedure are increasing. Currently dogs 45 - 50 lb. and over are potential candidates for TPLO. However, instrumentation for smaller dogs will eventually be available. The TPLO is an extremely detailed and technical procedure requiring exceptional surgical expertise, obligatory training, and a substantial orthopedic caseload for proficiency. In our practice the procedure has rapidly become the standard of care for CrCL insufficiency and is currently the ideal treatment of choice for medium - large, large, and giant breeds. References 1.Slocum B, Slocum TD. Tibial Plateau Leveling Osteotomy for Repair of Cranial Cruciate Liagament Rupture in the Canine. Vet Clin N Amer: Smal Anim Pract. 2000,23(4):777-795. 2. Schwarz PD. Tibial Plateau Leveling Osteotomy (TPLO): A Prospective Clinical Comparative Study. Proc Ninth Annual Amer Coll Vet Surg Symposium, 1999, 379-80. 3. Warzee CC, Dejardin LM, Arnoscky SP, et al. Effect of Tibial Plateau Leveling Osteotomy on cranial and caudal tibial thrust in canine cranial cruciate deficient stifles: an in-vitro analysis. Vet Surg (abstr) 1999: 28:407. 4. Morris EH, Lipowitz AJ. Comparison of Tibial Plateau Angles in Dogs With and Without Cranial Cruciate Ligament Injuries. Abstr Proc Tenth Annual Amer Coll Vet Surg Symposium, 2000, 15. 5. Wheeler J, Taylor RA, Steinheimer DN. Evaluation of the Tibial Plateau Angle as a Predisposing Factor for Cranial Cruciate Rupture in the Dog. Unpub. 6 Hulse DA, Hauptman JG. Effect of Tibial Plateau Leveling Osteotomy on Joint Stability in the Canine Cranial Cruciate Deficient Stifle Under Axial Tibial Load: An In Vitro Study. Abstr Proc Tenth Annual Amer Coll Vet Surg Symposium, 2000, 18. 7. Palmer RS. Tibial Plateau Leveling Osteotomy. Proc Tenth Annual Amer Coll Vet Surg Symposium, 2000, 271-275. |