PARTIAL ACL TEARS : TO DEBRIDE OR LEAVE THE LIGAMENT? PARTIAL ACL S TEARS FUNCTIONS OF THE CRUCIATE LIGAMENTS JOINT STABILIZER. Dr.

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1 PARTIAL ACL TEARS : TO DEBRIDE OR LEAVE THE LIGAMENT? Dr. Rico Vannini DCVS PARTIAL ACL S TEARS why to leave the ligament in place? TPLO extra-articular procedure ligament removal requires exposure of joint longer surgery time more post op pain higher morbidity some functions of the ligament can be preserved FUNCTIONS OF THE CRUCIATE LIGAMENTS Stabilizes Joint Controls Joints Kinematics Proprioceptive Function JOINT STABILIZER Cranial Cruciate Ligament (CrCL) Limits internal rotation Limits cranial displacement of the tibia relative to the femur (cranial drawer/tibial thrust) Limits hyperextension Caudal Cruciate Ligament (CdCL) Limits internal rotation Limits caudal displacement of the tibia relative to the femur (caudal drawer) Internal rotation is limited by the twisting of the ligaments. This occurs during flexion. During extension, the ligaments untwist and have no effect in limiting external rotation

2 KINEMATICS Ligaments control roll gliding motion of stifle joint PROPRIOCEPTION Nerve fibers in ligaments control loading of joint Sensory Nerve Endings Sensory nerve endings in the anterior cruciate ligament (lig. cruciatum anterius) of sheep. Halata Z, Wagner C, Baumann KI. Anat Rec 254 (1); 13-21, PARTIAL ACL S TEARS Why to resect the remaining ligament ligament may be ongoing source of irritation, inflammation and pain con t tearing ineffective healing incompetent joint stabilizer obscures visibility of menisci The partially torn ligament Nidus of chronic inflammation & degredative enzymes Injuries results in an increase of inflammatory mediators Results in a hostile environment for ligament and joint

3 Ethiopathogenesis of Ligament Failure Humans: traumatic Dogs: degenerative Dogs: degenerative Degerative Etiopathogenesis Multiple Central Blood Vessels in Juvenile Dog Single Central Blood Vessel by 1 year Absent in some specimens Ligamentocytes nourished by joint fluid and capillaries in subintimal layer of synovium and at bone attachments Central ligamentocytes are hypoxic Degeneration and necrosis or metaplasia to anaerobic chondrocytes Collagen fibrils breakdown, fragment and dissolve into tropocollagen molecules Fascicles lose tensile strength Roy Pool personal communication Correlative biomechanical and histologic study of the cranial cruciate ligament in dogs. Vasser PB, Pool RR, Arnosky SP, Lau RE. AJVR 46 (9); , 1985 Histologic changes in the human anterior cruciate ligament after rupture. Murray MM, Martin SD, Martin TL, Spector M. J Bone Joint Surg A. 82-A (10); , 2000 Degenerative Etiopathogenesis Ineffective Healing Cranial cruciate ligaments removed from dogs after ligament failure not only had degenerative disease, but had also undergone unsuccessful attempts at repair. Vasseur & Pool et al AJVR 1985 Courtesy Roy Pool Correlative biomechanical and histologic study of the cranial cruciate ligament in dogs. Vasser PB, Pool RR, Arnosky SP, Lau RE. AJVR 46 (9); , 1985 continuing tearing of the ligament can t be stopped in spite of joint stabilization procedures In spite of stabilizing surgery, ACL remains primary stabilizer of joint, thus it will remain fully loaded until completely torn Key question : does TPLO unload ligament sufficiently so that progressive tearing can be stopped?

4 Prof. Dr. Don Hulse, Texas ARTHROSCOPIC FINDINGS 6 dogs w/ partial stable ACL: 5 months to 4 years post op 6 dogs w/partial stable ACL 5 months to 4 years post op normal appearance synovial lining normal appearance of anterior capsule/fat pad normal appearance ACL / PCL normal lateral & medial meniscus minimal to no articular cartilage changes Partial stable ACL Partial stable ACL

5 TO DEBRIDE OR LEAVE THE PARTIALLY TORN LIGAMENT? Conclusion : If there is really no progression of ligament failure we probably should leave it! but : is there really no progression? HOW ABOUT THE MENSICUS ACL limits exposure and obscures full visibility of the joint missed subsequent or latent tears as high as 22% ACL protects mensicus rate of menisceal tears in dogs with partial ACL s? Duke, GSH, m 5J. police dog Severe impingement of ACL

6 Filou Dt. Drahthaar m. 5rs Indi, GSH, m. 5yrs

7 PARTIAL ACL TEARS : TO DEBRIDE OR LEAVE THE LIGAMENT? (TPLO) we need to define criteria to select those patients which would profit from a resection of the remaining ACL if we don t have such, it is probably wise to leave the ligament in place