The Acutely Dislocated Knee: Evaluation and Management Jeffrey A. Rihn, MD, Peter S. Cha, MD, Yram J. Groff, MD, and Christopher D. Harner, MD 02/25/2021 on BhDMf5ePHKav1zEoum1tQfN4a+kJLhEZgbsIHo4XMi0hCywCX1AWnYQp/IlQrHD3i3D0OdRyi7TvSFl4Cf3VC4/OAVpDDa8KKGKV0Ymy+78= by http://journals.lww.com/jaaos from Downloaded Abstract Downloaded Acute knee dislocations are uncommon orthopaedic injuries. Because they often spon- (within 3 weeks of injury).6,8,13,14 Most taneously reduce before initial evaluation, the true incidence is unknown. Dislo- of the principles of evaluation and from http://journals.lww.com/jaaos cation involves injury to multiple ligaments of the knee, resulting in multidirec- management of the patient with an tional instability. Associated meniscal, osteochondral, and neurovascular injuries acutely dislocated knee are well es- are often present and can complicate management. The substantial risk of associ- tablished;15 recent advances have cen- ated vascular injury mandates that vascular integrity be confirmed by angiography tered on improvements in surgical in all suspected knee dislocations. Evaluation and initial management must be per- technique. by BhDMf5ePHKav1zEoum1tQfN4a+kJLhEZgbsIHo4XMi0hCywCX1AWnYQp/IlQrHD3i3D0OdRyi7TvSFl4Cf3VC4/OAVpDDa8KKGKV0Ymy+78= formed expeditiously to prevent limb-threatening complications. Definitive manage- ment of acute knee dislocation remains a matter of debate; however, surgical recon- struction or repair of all ligamentous injuries likely can help in achieving the return Classification of adequate knee function. Important considerations in surgical management in- clude surgical timing, graft selection, surgical technique, and postoperative rehabilitation. Knee dislocation is temporally clas- J Am Acad Orthop Surg 2004;12:334-346 sified as acute (<3 weeks) or chronic (≥3 weeks).16 Anatomic classification is based on the position of the dis- placed tibia (ie, anterior, posterior, Traumatic knee dislocations are un- to the collateral ligaments, menisci, medial, or lateral) on the femur.2 A common, accounting for <0.02% of all articular cartilage, and neurovascu- orthopaedic injuries.1-3 These data lar structures can complicate the eval- likely underestimate the true inci- uation and treatment of the patient dence because an unknown percent- with a traumatic knee dislocation. Dr. Rihn is Resident Physician, Department of age of knee dislocations spontaneous- Historically, traumatic dislocation Orthopaedic Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA. Dr. Groff is Clin- ly reduce and thus are not diagnosed of the knee has been managed with ical Fellow, Center for Sports Medicine, Univer- during the initial evaluation. Mis- prolonged immobilization, which has sity of Pittsburgh, Pittsburgh. Dr. Harner is Blue management of such injuries can been associated with variable out- Cross of Western Pennsylvania Professor, and Di- have devastating consequences, par- comes, including loss of motion, re- rector, Section for Sports Medicine, Department ticularly in dislocations that involve sidual instability, and poor knee of Orthopaedic Surgery, University of Pittsburgh Medical Center. Dr. Cha is Attending Surgeon, 6-8 limb-threatening vascular injuries. function. The goal of surgical man- Beacon Orthopaedics and Sports Medicine, Cin- on Therefore, despite the low reported agement of acute dislocations is an- cinnati, OH. 02/25/2021 incidence of knee dislocation, a basic atomic repair and reconstruction of knowledge of current evaluation and all associated ligamentous and menis- None of the following authors or the departments management concepts is essential. cal injuries.9-13 Surgical timing, graft with which they are affiliated has received anything of value from or owns stock in a commercial com- Knee dislocation commonly in- selection, and surgical technique re- pany or institution related directly or indirectly volves injury to most of the soft-tissue main controversial. The use of al- to the subject of this article: Dr. Rihn, Dr. Groff, stabilizing structures of the knee, re- lograft has become popular in mul- Dr. Harner, and Dr. Cha. sulting in multidirectional instabili- tiligament knee surgery because of ty.Although knee dislocation can oc- graft availability, decreased operating Reprint requests: Dr. Harner, Center for Sports Medicine, 3200 South Water Street, Pittsburgh, cur involving injury isolated to the time, and decreased donor site mor- PA 15203. anterior cruciate ligament (ACL) or bidity in an already traumatized posterior cruciate ligament (PCL), knee.9,12,13 Some advocate delayed Copyright 2004 by the American Academy of both of the cruciate ligaments are usu- surgery, but many others recommend Orthopaedic Surgeons. ally disrupted.4,5 Associated injuries early surgical repair or reconstruction 334 Journal of the American Academy of Orthopaedic Surgeons Jeffrey A. Rihn, MD, et al rotatory knee dislocation involves a with knee dislocation until it is proved looked when evaluating a multiply combination of these tibial displace- otherwise by angiography. traumatized patient. Thus, even with ment positions. Knee dislocations that Neurologic damage, ranging from normal-appearing radiographs, a spontaneously reduce before evalu- a stretching of the nerve (neurapraxia) complete physical examination of the ation are classified according to the to complete transection (neuronotme- knee, including thorough neurovas- direction of instability. sis), occurs in 16% to 40% of all knee cular assessment, is essential for all Anterior dislocations are the most dislocations; it is most common after victims of high-energy trauma. When common, accounting for approximate- posterolateral dislocations.6,20 The pe- substantial laxity of two or more of ly 40% of all knee dislocations.17 Hy- roneal nerve is more often injured than the major ligaments of the knee is perextension is typically the mecha- the tibial nerve.21 Careful neurologic found, a presumptive diagnosis of nism of injury. Posterior dislocations examination before any manipulation knee dislocation should be made. represent 33% of all knee dislocations.17 of the knee is mandatory, although it The vascular examination includes The mechanism is usually high energy, is often difficult to obtain, particular- manual palpation of the dorsalis pe- such as the so-called dashboard in- ly in a trauma patient. dis and posterior tibialis pulses and jury sustained during a motor vehi- comparison with the uninvolved side. cle accident. Lateral and medial dis- The ankle-brachial indices (ABI) de- locations are less common, estimated Evaluation termined with ultrasound is a more at 18% and 4% incidence, respective- sensitive study that can help confirm ly.17 The mechanism involves a vio- Initial assessment of the patient be- the vascular status of the extremity. lent varus or valgus load. Associated gins with a brief history that reviews An abnormal result from any of these fractures are not uncommon. Rotatory the mechanism of injury and a direct- tests should prompt a vascular sur- knee dislocations, caused by a twist- ed physical examination that includes gery consultation. However, a normal ing force to the knee, are the least com- a thorough neurovascular evaluation result from any of these tests does not mon type. Posterolateral dislocations, of the injured extremity. The patient exclude arterial injury. Normal puls- the most common type of rotatory knee with a dislocated knee usually has a es, a warm foot, and brisk capillary dislocation, have a high incidence of tremendous amount of pain, a large refill can be present with arterial in- irreducibility, in which case the me- knee effusion, and overall swelling of jury. Therefore, any patient with a dial femoral condyle buttonholes the extremity. A spontaneously re- high suspicion of knee dislocation through the medial soft-tissue struc- duced knee dislocation can appear should undergo arteriography of the tures.18 deceptively benign and can be over- lower extremity (Fig. 1). The routine Associated Neurovascular Injuries Injuries to the popliteal artery can make knee dislocation a limb-threat- ening emergency. The reported inci- dence of associated popliteal artery injury is between 32%17 and 45%,19 with severity ranging from an intimal tear to complete transection. Because amputation rates vary in direct rela- tion to the length of time to revascu- larization, immediate recognition of arterial vascular compromise is cru- cial. An amputation rate of 86% after a delay in revascularization of 6 to 8 hours has been reported.17 Damage to the intimal portion of the artery can be more insidious, with delayed vas- cular compromise presenting sever- Figure 1 Anteroposterior arteriograms of an intact popliteal artery (A) and an injured popliteal al days after the injury. Vascular in- artery (B) after acute knee dislocation and subsequent reduction. The artery shown in panel B was found to be transected at exploration. jury must be assumed in all patients Vol 12, No 5, September/October 2004 335 The Acutely Dislocated Knee: Evaluation and Management use of arteriography in this setting is justified by the relatively low morbid- ity of the test, the high incidence of popliteal artery injury, and the poten- tially devastating consequences of de- lay in diagnosis.20,22-24 A complete neurologic examina- tion also must be performed, includ- ing an evaluation of motor and sen- sory function in the distribution of the tibial and peroneal nerves. The por- tions of the examination requiring