Volume 50 | Issue 1 Article 7 1988 Stifle njurI ies in the Canine Jadid Johnson Iowa State University Robert Radasch Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/iowastate_veterinarian Part of the Veterinary Medicine Commons Recommended Citation Johnson, Jadid and Radasch, Robert (1988) "Stifle nI juries in the Canine," Iowa State University Veterinarian: Vol. 50 : Iss. 1 , Article 7. Available at: https://lib.dr.iastate.edu/iowastate_veterinarian/vol50/iss1/7 This Article is brought to you for free and open access by the Journals at Iowa State University Digital Repository. It has been accepted for inclusion in Iowa State University Veterinarian by an authorized editor of Iowa State University Digital Repository. For more information, please contact [email protected]. Stifle Injuries in the Canine Jadid Johnson, BS * Robert Radasch, DVM ** Introduction observation, palpation of the affected stifle may Stifle injuries are the most common cause for rear begin. The joint is gently flexed and extended sever­ limb lameness in the adult dog. The recognition al times with the palm ofone hand over the crani­ and treatment ofthese injuries is an imponant pan al aspect ofthe joint to detect crepitation, grating, of any small animal pra~tice. This anicle will dis­ clicking, or snapping. The areas lateral to the troch­ cuss the diagnosis and various methods for repair lear ridges are palpated for smoothness or rough­ of stifle disorders. ness. Ifthe condyles appear thick or rough, this may 4 Cruciate ligament injuries are the most common indicate the presence of osteophytes. lesion in the stifle joint of the dog. Although the Cruciate Ligament Abnormalities cranial cruciate ligament is most often injured, rup­ Drawer movement, defined as craniocaudal in­ ture of either the cranial or caudal cruciate results stability of the stifle, is indicative of cruciate in instability and predisposes the joint to degener­ ligament abnormalities. Except in young puppies, ative changes.! Meniscal injury usually occurs with there is no drawer movement in normal dogs. Even panial or complete tearing ofthe cranial or caudal the slightest amount indicates some form ofpathol­ 2 cruciates. Injuries to the collateral ligaments ofthe ogyexists.4 To palpate for drawer movement, the stifle are not common. The most common injury examiner stands caudal to the animal which is involves the medial collateral ligament and is usual­ positioned in lateral recumbency with the stifle ly seen in conjunction with cranial cruciate ligament opposite the one to be palpated closest to the table. rupture and damaged medial meniscus. This trilogy The index fmger ofone hand is placed on the prox­ of knee injuries is called the "unhappy triad".3 imal end of the patella while the thumb is placed When both collateral ligaments are ruptured, both over the lateral fabellar region. The index finger of cruciates are ruptured also and the diagnosis is one the other hand is placed on the tibial crest and the of a "total knee".3 Traumatic patellar luxation is thumb is positioned caudal to the fibular head. The a relatively rare injury and is almost always a medial leg is flexed slightly and the femur held steady while luxation.! Patellar fractures and patellar ligament the tibia is pushed cranially and caudially. Drawer ruptures are also rarely encountered in the dog. 1 motion should be tested in both extension and flex­ ion. Caudal drawer movement is often difficult to Diagnosis distinguish from cranial drawer. However, a sud­ Veterinarians often encounter patients with a his­ den cessation of cranial drawer movement occurs tory of lameness or pain of unknown origin. In a when an intact cranial cruciate becomes taut. With hospital environment, excitement and apprehen­ cranial cruciate rupture, the cessation is not abrupt.4 sion often seem to cause a chronic lameness to disappear or painful maneuvers to go unnoticed. Memscal Injury History, observation, palpation and proper radio­ graphy are all imponant in assessing the patient. Meniscal injuries are best diagnosed by direct in­ One of the first tasks is to walk and trot the spection ofthe joint. However, a pathologic menis­ animal observing any gait abnormalities. If lame­ cus may be suspected ifa meniscal click is palpated ness is not apparent, having the animal gait in tight or heard during flexion or extension and drawer circles may elucidate abnormalities. After gait manipulations of the stifle. 5 *Dr. Johnson is a 1987 graduate of the College of Veterinary Medicine at Iowa State University. Collateral Ligament Instability **Dr. Radasch is an adjunct instructor in the Department of Veterinary Clinical Sciences at Iowa State University. To test for collateral ligament insufficiency, the 16 The Veten'nary Student limb is held in extension and varus and valgus posterior displacement of the tibia on the femur stresses are applied to the joint. In the case ofmedial (posterior drawer). collateral ligament rupture, the medial aspect ofthe In general, the bulk of the cranial cruciate liga­ joint will open when a valgus stress is applied. With ment is tight in extension and loose in flexion, while lateral collateral ligament rupture, the lateral aspect the bulk of the caudal cruciate is loose in exten­ ofthe joint will open when a varus stress is applied. 3 sion and tight in flexion. 6 Because the cranial cru­ ciate ligament is tight in extension it is the primary The Cruciate Ligaments check against hyperextension of the stifle. As stated previously, cruciate ligament injuries are the most common lesion in the stifle joint of Mechanism Of Injury the dog. The cruciate ligaments play an imponant As mentioned, the cranial cruciate ligament pre­ role in maintaining the stability ofthe stifle through vents anterior displacement of the tibia on the the functional range ofmotion. Rupture ofone or femur, limits internal rotation of the tibia on the both cruciates results in severe instability and pre­ femur, and prevents hyperextension of the stifle. disposes the joint to degenerative changes. The The most common mechanism of injury of the cruciate ligaments are dynamic structures and their cranial cruciate ligament is sudden rotation of the anatomy and spatial relationship are directly relat­ stifle with the joint in 20 to 50 degrees offlexion. l ed to their function as constraints ofjoint motion. 1 As the cranial cruciate ligament tries to limit In order to understand the mechanism of injury internal rotation of the tibia, it becomes wound and rationale behind repair techniques, it is neces­ excessively tight and is subject to trauma from the sary to understand their anatomy and function in lateral femoral condyle. Clinically, this injury occurs relation to joint motion. when an animal makes a sudden turn on the weight-bearing rear limb. Anatomy and Function With hyperextension ofthe stifle, the cranial cru­ The cranial cruciate ligament is attached to a fossa ciate ligament is the first structure subject to injury. on the posterior aspect of the medial side of the This type ofinjury occurs when an animal steps into lateral femoral condyle. It courses cranially, medi­ a hole while running. Extreme hyperextension of ally and distally across the intercondylar fossa and the stifle damages the caudal cruciate only secondary attaches to the cranial intercondyloid area of the to rupture of the cranial cruciate ligament. tibia. The caudal cruciate ligament is attached to Rupture ofthe caudal cruciate ligament alone is a fossa on the ventral aspect of the lateral side of rare and is usually associated with severe trauma or the medial femoral condyle. It passes caudodistally dislocation ofthe stifle. 1 Direct trauma ofthe tibia to the medial aspect of the popliteal notch of the is an anteroposterior direction may cause the caudal tibia. The caudal cruciate ligament lies medial to cruciate ligament to rupture. Also, persistant stifle and crosses the cranial cruciate ligament. During instability due to other ligament damage may lead flexion, the ligaments twist on each other. rupture of the caudal cruciate ligament. As the stifle is flexed, the femoral and fibular attachments ofthe lateral collateral ligaments move closer together and the ligament begins to relax. Cruciate Ligament Repair This allows posterior displacement of the lateral It has been established that rupture of either femoral condyle on the tibial plateau and results cruciate ligament results in joint instability which in internal rotation of the tibia on the femur. 1 leads to progressive degenerative changes within the Conversely, as the knee is extended the lateral col­ joint. It is for this reason that cruciate ligament lateral ligament tightens and the lateral femoral injuries should be repaired. Through the years there condyle moves anteriorly causing external rotation have been many developments in the surgical repair ofthe tibia. 1 The twisting ofthe cruciate ligaments ofthe cruciate ligaments. Although there are many during flexion limits the amount of internal rota­ repair techniques currently in use, the method tion of the tibia. If either cruciate ligament chosen depends on surgeon preference and techni­ ruptures, there will be an abnormal increase in the cal ability. Surgical techniques can be divided into amount of internal rotation. two basic categories; intraarticular and extraarticular The primary function of the cruciate ligaments procedures. Intraanicular techniques utilize either is to maintain anteroposterior stability ofthe stifle. autogenous or synthetic graft material to replace the The cranial cruciate ligament limits forward dis­ cruciate ligament. Extraanicular techniques stabi­ placement of the tibia on the femur (anterior lize the joint by tightening extraarticular structures. drawer) while the caudal cruciate ligament limits Regardless ofthe method chosen, the joint should Vol. 50, No. 1 17 be opened so that the torn ends of the ligament suture is pre-placed around the fabella and through can be removed and the menisci examined. In all a hole in the tibial crest.