to the setting in which the patient is evaluated. Athletes are more likely. to sustain "isolated" PCL injuries as a result of a hyperflexion

Transcription

1 - -- MATTHEW D. PEPE, MD a Thomas Jefferson University, Philadelphia CHRISTOPHER D. HARNER, MD University of Pittsburgh Medical Center out by Key Wo The true incidence of posterior cruciate ligament (PCL) injuries in athletes is unknown. In the general population, the incidence was reported by Miyasaka and Daniel (1991) to be 3 %. Fanelli and Edson (1 995), in a study in the trauma population, found the incidence of PCL injury to be 37 % of all cases of knee hemarthrosis. The severity of injury and associated ligament involvement also vary according to the setting in which the patient is evaluated. Athletes are more likely. to sustain "isolated" PCL injuries as a result of a hyperflexion mechanism (Fowler & Messieh, 1987; Parolie & Berg- ysical e x i s: cruciate I.. I feld, 1986). In contrast, patients evaluated in the emergency department have most often sustain combined PCL injuries from high-energy mechanisms (Fanelli, 1993). PCL injuries can be classified according to severity and timing. Severity of the injury depends on whether the PCL injury is partial or complete and whether there are associated ligaments involved (posterolateral corner). The timing of the injury can be classified as acute (within 4-6 weeks) or chronic (more than 6 weeks). Isolated PCL injuries can be further classified as partial or complete, which can usually be determined by physical examination. Partial injuries are most often the result of a hyperflexion mechanism wherein the anterolateral bundle is ruptured but the posteromedial bundle remains intact. Clinically, a partial PCL tear is distinguished by a posterior drawer of 1 + to 2 +. In general, partial, isolated PCL injuries have a good prognosis and are amenable to nonoperative management. Complete tears of the PCL must be distinguished from combined ligament injuries because the prognosis is different for those injuries. The mechanism of injury of combined ligament injuries is most often a direct trauma (e.g., highvelocity motor-vehicle accident) or hyperextension. It is important with combined ligament injuries to rule out the possibility of a knee dislocation, which carries with it the risk of vascular injury. Wascher, Dvirnak, and DeCoster (1 997) showed that the rate of vascular injury in a population of patients with knee dislocations (diagnosed as both the anterior cruciate ligament [ACL] and PCL being torn) was 14 %, regardless of whether the knee had spontaneously reduced before examination. The evaluating physician or athletic trainer or therapist should be critically aware that despite a reduced knee on presentation, a dislocation might have occurred and vascular damage is possible (Green & Allen, 1 977; Wascher et al.) Uuman Kinetics. ATT 6(6), pp ATHLETIC THERAPY TODAY NOVEMBER

2 History A careful history should be taken in any patient being evaluated for a knee injury in which a PCL injury is suspected. Ascertaining the setting in which the injury occurred is an important first step toward making an accurate diagnosis, because an injury that occurred secondary to a high-speed trauma, as opposed to on the athletic field, carries a much higher risk of being more severe. The evaluation should start with a determination of the exact mechanism of injury, taken as a history from the patient or a witness to the incident, such as another athlete, athletic trainer or therapist. or bystander. This provides important information regarding which structures might be involved and the potential severity of the injury (Harner & Jurgen, 1998). Other information that should be elicited is the immediate response of the extremity to the injury, such as whether a pop or tear was heard or felt, the occurrence and timing of swelling of the knee, and the presence of mechanical symptoms or instability after the injury. The ability of the patient to ambulate or continue playing is important if the incident was not witnessed. A history of prior injuries to the knee should be elicited, because many athletes are able to perform on chronic partial PCL injuries. Physical Examination It is critical to develop a systematic way to evaluate PCL injuries of all grades. In a patient with an acute, swollen, painful knee, physical examination can be extremely difficult. A PCL injury in this setting should be ruled out by other diagnostic techniques (magnetic resonance imaging). Palpation for gross instability in both the medial-lateral and anterior-posterior planes must be performed. A knee that opens completely (Grade ) in full extension to varus or valgus stress has a combined ACL and PCL injury in addition to the collateral ligament and must be considered a knee dislocation and treated appropriately. The physical examination of the patient with a so-called isolated PCL injury is relatively straightfor-.ward, with the degree of injury"-being related to-the-. amount of posterior tibial subluxation at varying degrees of knee flexion (Harner & Jurgen, 1998). The cornerstone of the diagnosis and the most accurate clinical test is the posterior drawer test (Clancy et al., 1983; Covey & Sapega, 1993). This is performed by placing the knee in 80-90" of flexion, with the hip in 45" of flexion and the foot stabilized against the table. A posteriorly directed force is placed on the proximal tibia in an attempt to translate it beneath the femur, and the relationship between the medial femoral condyle and tibia is determined, as is the presence or absence of an endpoint. In the normal knee, the tibia sits 1 cm anterior to the medial femoral condyle before any force is placed on the proximal tibia, and total posterior translation is less than 5 mm with a firm endpoint. Grade-I injuries have a palpable anterior step-off of the tibia, but less than normal (0-5 mm). Grade-I1 injuries have lost the anterior step-off, and the tibia starts flush with the femur, but the tibia cannot be pushed posterior to the femur (5-10 mm). Grade-I11 injuries have an obvious posterior sag, and the tibia can be pushed posterior to the femoral condyle ( > 10 mm). Godfrey's test has also been used to evaluate posterior tibial sag (Miller, Harner, & Koshiwaguchi, 1994). In this test, the hip and knee are both flexed to 90" while the foot is supported. An asymmetric concave anterior contour of the proximal tibia and lack of prominence of the tibial tubercle are evidence of posterior subluxation of the tibia. It is extremely important in the initial examination of the high-grade PCL injury to evaluate the posterolatera1 corner complex. The posterolateral corner is the primary restraint to external rotation of the tibia at both 30 and 90" of knee flexion (Veltri, Deng, Torzilli, Warren, & Maynard, 1995). The PCL is an important secondary stabilizer of external rotation, more so at 90" than at 30" of knee flexion (Gollehon, Torzilli, & Warren, 1987; Grood, Stowers, & Noyes, 1988; Veltri et al.). The posterior sag of the knee must be reduced before testing the posterolateral corner, because this can diminish or even negate laxity of the posterolateral structures (Baker, Norwood, & Hughston, 1984; Covey, Sapega, & Sherman, 1996; Noyes & Barber-Westin, 1996; Noyes, Stowers, Grood, Cummings, & VanGinkel, 1993). Diagnosis of an injury to the posterolateral corner-is-critical; ~becamereconstr~%ctton. of - the PCL alone in light of this injury increases the risk of graft failure (Harner, Vogrin, Hoher, Ma, &Woo, 2000). The most important finding on physical examination 10 1 NOVEMBER 2001 ATHLETIC THERAPY TODAY

3 of a patient with posterolateral corner instability is increased external rotation at both 30 and 90" of knee flexion. The easiest test to show this deficiency is the Dial test, wherein the femur is stabilized and the foot externally rotated at 30 and 90" of knee flexion and compared with the normal side (Loomer, 1991; Figure 1). An increase in external rotation of more than 10" results from an injury to the posterolateral corner. The posterolateral drawer test is a means of determining the amount of posterior translation and external rotation of the tibia in relation to the femur (Hughston & Norwood, 1980). To perform this test, a posterior drawer is performed in neutral, internal, and external rotation. A positive posterior drawer in neutral and internal rotation is consistent with a PCL injury. Posterolateral corner injuries cause increased posterior translation in external rotation. The external rotation recurvatum test can also be used to assess the posterolateral structures (Hughston & Norwood; Ritchie, Miller, & Harner, 1994).This test is performed with the patient in the supine position, and the examiner elevates both extremities by the great toes. Posterolateral rotatory instability (PLRI)will cause the affected extremity to go into relative hyperextension, with the tibia moving laterally and externally rotating. The reverse pivot shift has been described in many ways but most commonly begins with the knee flexed to 90" (Jakob, Hassler, & Staeubli, 1981). A valgus force is placed on the knee, with an axial load and external rotation to the foot as the extremity is brought into extension. In a knee with PLRI, the lateral tibia1 plateau will start posteriorly subluxed and reduce at 20-30" with the pull of the iliotibial band. Evaluation of the neurovascular structures is mandatory, because % of patients with PLRI have a peroneal nerve injury (Baker, Norwood, & Hughston, 1983; Veltri et al., 1995). Furthermore, a complete knee examination covering all remaining aspects of alignment and stability is mandatory. Radiographic [valuation Routine radiographs should be obtained in every patient with a suspected PCL tear. In our institution, Figure 1 The Dial test performed at 90" of knee flexion. This test should be performed at both 30 and 90" of flexion. A positive test, as shown on the left side, is caused by posterolateral rotatory instability in which there is an increase in external rotation of greater than 10' compared with the normal knee ATHLETIC THERAPY TODAY NOVEMBER ZOO 1 I 1 1

4 this consists of a posterior-anterior, 45"-flexion, weight-bearing view; a lateral view of the affected extremity; and patellofemoral views of both knees. Typically, radiographs are normal in athletes with isolated PCL injuries. An avulsion fracture of the ACL or PCL insertion might be present, and repair of these yields excellent results if performed early. The examiner should check for fibular-head fractures or avulsion of the lateral collateral ligament, because early repair yields better results than chronic reconstruction does. The role of magnetic resonance imaging (MRI) in the PCL-deficient knee has been increasing, and its accuracy ranges from 96 % to 100 %. MRI might change the approach to treatment by identifying the exact location of t h e tear (femoral, midsubstance, or tibial; Figures 2a and 2b). In addition, femoral-insertion "peel-off" lesions might be identified (Figure 3), in which the bulk of the ligament is intact and avulsed from the femoral condyle. This lesion is amenable to early surgical repair. The typical appearance of a normal PCL on MRI is of homogeneous low-signal intensity on the TI- and T2weighted images (Figure 4). The normal ligament Figure 2a MRI demonstrating a partial midsubstance PCL tear. The normal homogeneous low-signal intensity of the PCL is disrupted in the midportion NOVEMBER appears lax on MRI taken in extension, because the anterolateral bundle is normally tensioned in flexion. The bone scan is a helpful test in patients with chronic PCL injuries who are experiencing pain or instability. Increased uptake in either the medial or the patellofemoral compartment signifies early articular-cartilage damage and is an indication for reconstruction or osteotomy to restore normal knee laxity or unload the medial compartment. In general, the approach to surgical treatment of PCL injuries depends on two factors-the timing and severity of the injury. See Figures 5 and 6 for our general algorithm of treatment. For the most part, isolated PCL injuries can be treated nonoperatively because of the integrity of the secondary restraints, but combined injuries have better outcomes when intervention occurs within the first 2 weeks. The PCL is different from the ACL in that it is often subject to partial tears. It is extremely important for the clinician to distinguish the grade of the PCL tear. Grade-I11 injuries have Figure Zb MRI demonstrating a complete midsubstance PCL tear. ATHLETIC THERAPY TODAY

5 Figure 3 MRI demonstrating a femoral peel-off lesion in a 19year-old female softball player. A primary repair to the femur was performed acutely. Figure 4 MRI demonstrating a normal PCL. There is homogeneous low-signal intensity throughout the entire ligament. The ligament appears loose because the MRI is obtained in extension, when the antero~ateralbundle is lax. ATHLETIC THERAPY TODAY a higher likelihood of causing recurrent pain and instability, in addition to having a greater chance of being accompanied by a significant posterolateral corner injury. Combined PCL injuries most often involve the posterolateral corner but can also involve the lateral collateral ligament, medial collateral ligament, and the ACL alone or in combination in the presence of a knee dislocation. Nonoperative treatment of these injuries in general does not lead to good outcomes or restore translational and rotational stability. Acute isolated PCL injuries usually respond to nonoperative management. Grade-I injuries are treated with rest, a quadriceps rehabilitation program, and avoidance of athletic actiyities for 2-4 weeks. Acute Grade-I1 and -111 injuries are braced for 4 weeks in full extension to prevent posterior and posterolateral tibial subluxation and to allow any remaining attenuated fibers of the ligament to heal. During this time an isometric quadriceps rehabilitation program is performed. Acute single-bundle surgical reconstruction of the ligament is recommended in young athletes with Grade-111 injuries. Femoral peel-off lesions are also repaired acutely, because the outcome of surgical treatment in general has been better than that of nonsurgical treatment. All combined PCL injuries, whether involving the lateral side, ACL, or medial collateral ligament, must be treated surgically within 2 weeks with an examination under anesthesia, singlebundle PCL reconstruction, and repair of the coexisting injury. The outcome of acute surgical treatment in general is better than the outcome of chronic or nonoperative management. Chronic Grade-I and -11 injuries with pain or instability most often respond to quadriceps rehabilitation. There are patients, however, with Grade-I1 injuries who continue to have difficulty despite undergoing an adequate regimen of physical therapy and activity modification. In these patients, we obtain a bone scan with pinhole views of both knees to assess the patellofemoral and medial compartments. A positive bone scan indicates early articular-surface damage and is an indication for biplanar tibial osteotomy in patients with pain. We do not recommend PCL reconstruction in patients with chronic Grade-I1 injuries, because it is our experience that with the Current techniques, stability cannot be reliably restored, we believe that an anteromedial-opening wedge osteotomy to increase NOVEMBER

6 PCL/MCL PCLJACUmedial or lateral corner/ 4 weeks braced in prevent posterior and posterolateral subluxation Peel-off lesion Within 2 weeks: Multiple ligament/knee dislocationsingle bundle Peel-off Athlete--single bundle Figure 5 Treatment algorithm for acute tears of the PCL. EUA = examination under anesthesia; PLC = posterolateral corner. Chronic PCL Injury PCL/MCL PCLJACUmedial Failed Grade II-Grade I11 Surgery Biplanar tibia1 Double-bundle- Double-bundleosteotomy reconstruction reconstruction PCL Grade I1 or PCL figure 6 Treatment algorithm for chronic tears of the PCL. PLC = posterolateral corner NOVEMBER 2001 ATHLETIC THERAPY TODAY

7 valgus alignment and tibial slope unloads the medial compartment and increases posterior stability. We also recommend a biplanar tibial osteotomy in patients with pain and an isolated Grade-111 PCL injury with a positive bone scan who have failed physical therapy. There is usually some degree of involvement of the posterolateral structures in these cases, and the osteotomy serves to decrease stress on the lateral structures, in addition to adding posterior stability and unloading the medial compartment. Patients with persistent symptoms of instability but without pain in the presence of a chronic, isolated Grade-I11 injury should undergo double-bundle PCL reconstruction with a posterolateral corner reconstruction. The double-bundle PCL reconstruction has been shown in a biomechanical model to more closely restore knee kinematics than do single-bundle techniques (Harner, Janaushek, et al., 2000). The type of posterolateral corner reconstruction we prefer is a popliteus advancement, as well as a popliteofibular ligament reconstruction, in any patient with a more than Grade-I + PLRI. Any chronic combined ligament injuries should be treated with PCL reconstruction and repair or reconstruction of the injured structures. I References Baker, C.L., Norwood, L.A., & Hughston, J.C. (1 983). Acute posterolateral rotatory instability of the knee. Journal of Bone andjoint Surgery, 65A, Baker, C.L., Norwood, L.A., & Hughston, J.C. (1 984). Acute combined posterior cruciate and posterolateral instability of the knee. American Journal of Sports Medicine, 12, Clancy, W.G., Jr., Shelbourne, K.D., Zoellner, G., Keene, J.S., Reider, B., & Rosenberg, T.D. (1 983). Treatment of knee joint instability secondary to rupture of the posterior cruciate ligament. Report of a new procedure. Journal of Bone and Joint Surgery, 65A, Covey, D.C., & Sapega, A.A. (1993). Injuries of the posterior cruciate ligament. Journal of Bone andjoint Surgery, 75A, Covey, D.C., Sapega, A.A., &Sherman, G.M. (1996). Testing for isometry during reconstruction of the posterior cruciate ligament. American Journal of Sports Medicine, 24, Fanelli, G.C. (1 993). Posterior cruciate ligament injuries in trauma patients. Arthroscopy, 9, Fanelli, G.C., & Edson, C.J. (1995). Posterior cruciate ligament injuries in trauma patients: Part 11. Arthroscopy, 11, Fowler, P.J., & Messieh, S.S. (1987). Isolated posterior cruciate ligament injuries in athletes. American Journal of Sports Medicine, 15, Gollehon, D.L., Torzilli, P.A., &Warren, R.F. (1 987). The role of the posterolateral and cruciate ligaments in the stability of the human knee. A biomechanical study. Journal of Bone andjoint Surgery, 69A, Green, N.E., & Allen, B.L. (1977). Vascular injuries associated with dislocation of the knee. Journal ofbone andjoint Surgery, 59A Grood, E.S., Stowers, S.F., & Noyes, F.R. (1988). Limits of movement in the human knee. Effect of sectioning the posterior cruciate ligament and posterolateral structures. Journal of Bone and Joint Surgery, 70A, Harner. C.D., Janaushek, M.A., Kanamori, A., Yagi, M., Vogrin, T.M., & Woo, S.L.-(2000). Biomechanical analysis of a double-bundle posterior cruciate ligament reconstruction. AmericanJournal of Sports Medicine, 28, Harner, C.D., 6. Jurgen, H. (1998). Evaluation and treatment of posterior cruciate ligament injuries. American Journal of Sports Medicine, 26, Harner, C.D., Vogrin, T.M., Hoher, J., Ma, C.B., &Woo, S.L. (2000). Biomechanical analysis of a posterior cruciate ligament reconstruction. Deficiency of the posterolateral structures as a source of graft failure. American Journal of Sports Medicine, 28, Hughston, J.C., & Norwood, L.A. (1980). The posterolateral drawer test and external rotation recurvatum test for posterolateral rotatory instability of the knee. Clinical Orthopaedics, 147, Jakob, R.P., Hassler, H., & Staeubli, H.U. (1981). Observations on rotatory instability of the lateral compartment of the knee. Experimental studies on the functional anatomy and the pathomechanism of the true and reversed pivot shift sign. Acta OrthopaedicaScandinavica, 191 (suppl.), Loomer, R.L. (1 991). A test for knee posterolateral rotatory instability. Clinical Orthopaedics, 264, Miller, M.D., Harner, C.D., & Koshiwaguchi, S. (1 994). Acute posterior cruciate ligament injuries: Vol. 1. Knee surgery. Baltimore: Williams & Wilkins. Miyasaka, K.C., &Daniel, D.M. (1 991). The incidence of knee ligament injuries in the general population. AmericanJournal of Knee Surgery, 4, 4-8. Noyes, F.R., & Barber-Westin, S.D. (1 996). Treatment of complex injuries involving the posterior cruciate and posterolateral ligaments of the knee. American Journal of Knee Surgery, 9, Noyes, F.R., Stowers, S.F., Grood, E.S., Cummings, J., & VanGinkel, L.A. (1 993). Posterior subluxations of the medial and lateral tibiofemoral compartments. An in vitro ligament sectioning study in cadaveric knees. American Journal of Sports Medicine, 21, Parolie, J.M., & Bergfeld, J.A. (1986). Long term results of nonoperative treatment of isolated posterior cruciate ligament injuries in the athlete. American Journal of Sports Medicine, 14, Ritchie, J.R., Miller, M.D., &Harner, C.D. (1994). History andphysical evaluation: Vol. I. Knee surgery. Baltimore: Williams & Wilkins. Veltri, D.M., Deng, X-H., Torzilli, P.A., Warren, R.F., &Maynard, M.J. (1 995). The role of the cruciate and posterolateral ligaments in stability of the knee. A biomechanical study. American Journal of Sports Medicine, 23, Wascher, D.C., Dvirnak, P.C., & DeCoster, T.A. (1997). Knee dislocation: Initial assessment and implications for treatment. Journal of Orthopaedic Pauma, 11, Matthew Pepe finished his fellowship in sports medicine at the University of Pittsburgh in July He is currently an assistant professor of orthopedic surgery at Thomas Jefferson University in Philadelphia and in practice in Egg Harbor Township, NJ. Christopher Harner is a professor of orthopedic surgery at The University of Pittsburgh Medical Center. He has authored numerous articles on the anatomy, biomechanics, and clinical treatment of PCL injuries. ATHLETIC THERAPY TODAY NOVEMBER