踝关节钝性损伤的影像学诊断

Jack Casey, HMS III Gillian Lieberman, MD Page 1 Jack Casey, HMS IV Gillian Lieberman, MD Radiographic Evaluation of Blunt Ankle Trauma Jack Casey, HMS III Gillian Lieberman, MD Page 2 Overview • Importance of ankle injuries • Imaging– when, how, and what to look for • Anatomy review • Common ankle injuries – Patient cases to illustrate mechanisms of injury and radiologic classification Focus on radiology Jack Casey, HMS III Gillian Lieberman, MD Page 3 Historical Context Jack Casey, HMS III Gillian Lieberman, MD Page 4 Blunt Ankle Trauma – Still A Major Problem • Most common MSK injury • Less that 15% of patients have clinically significant fractures • Ankle films are 3rd most common radiologic study ordered in many hospitals • > $500 million spent annually on ankle radiographs in North America • Clinical guidelines can help guide management Steill et al. JAMA, 1993. Jack Casey, HMS III Gillian Lieberman, MD Page 5 Indications for Imaging The Ottawa Ankle Rules • Set of clinical guidelines, designed to have sensitivity of 100% for detecting fractures s/p blunt ankle trauma. – willing to accept trade-off of lower specificity • Expected benefits: Limit radiation exposure, health care costs, ED waiting time. • Designed to be easy to use Jack Casey, HMS III Gillian Lieberman, MD Page 6 Ottawa Ankle Rules - The basics Ankle x-ray series is only necessary if there is pain near the malleoli and any of these findings: 1. Inability to bear weight both immediately and in the ED (four steps) 2. Bone tenderness at posterior edge or tip of medial or lateral malleoli. www.aafp.org/afp/20020901/785.html Jack Casey, HMS III Gillian Lieberman, MD Page 7 Ottawa Ankle Rules - The basics Foot x-ray series is only necessary if there is pain in the mid-foot and any of these findings: • Inability to bear weight both immediately and in the ED (four steps) 2. Bone tenderness at base of fifth metatarsal or the navicular. www.aafp.org/afp/20020901/785.html Jack Casey, HMS III Gillian Lieberman, MD Page 8 Ottawa Ankle Rules - How good are they? • Systemic review of 27 studies (15,581 patients) – Sensitivity 96.4 - 99.6 % – Specificity varied widely (10-79%) – Less than 2% of patients who were negative for fx according to ankle rules actually had a fracture. – Missed fractures were almost always minor, did not affect long term outcomes. • 28% reduction in use of ankle radiography • No decrease in patient satisfaction Bachmann et al. BMJ, 2003. Steill et al. JAMA, 1993. Jack Casey, HMS III Gillian Lieberman, MD Page 9 Ottawa Ankle Rules - A few limitations • Not applicable to: – <18 y/o – Altered mental status – Multi-system trauma – Chronic/ subacute injuries • Always trust clinical judgment Jack Casey, HMS III Gillian Lieberman, MD Page 10 Implementing the OAR • Thorough (but brief) H+P ¾Evaluate skin/ soft tissue. Assess for open fx. ¾Check and document neurovascular status ¾Palpate entire distal 6 cm of both malleoli before asking patient to bear weight ¾Palpate over 5th metatarsal and navicular for tenderness ¾Palpate for tenderness over proximal fibula to exclude potential Maisonneuve fracture • Think about underlying anatomy and mechanism of injury Jack Casey, HMS III Gillian Lieberman, MD Page 11 Basic Anatomy 1- Bones Interactive Foot and Ankle. Primal Pictures, Ltc. Anterior Process of Calcaneus Jack Casey, HMS III Gillian Lieberman, MD Page 12 Basic Anatomy 2- Ligaments Greenspan, Orthopedic Radiology THREE principal sets of ligaments support the ankle, all of which are essential to its stability. Jack Casey, HMS III Gillian Lieberman, MD Page 13 Basic Anatomy 3- Tendons Greenspan, Orthopedic Radiology Jack Casey, HMS III Gillian Lieberman, MD Page 14 Anatomy- Putting it All Together Bones and connective tissue give rise to ring- like structure surrounding the talus. Rosen’s Emergency Medicine: Concepts and Clinical Practice. Jack Casey, HMS III Gillian Lieberman, MD Page 15 Ankle Injuries-Inversion Greenspan, Orthopedic Radiology Remember Ring- Like Structure in Conceptualizing Injury. www.emedicinehealth.com Jack Casey, HMS III Gillian Lieberman, MD Page 16 Ankle Injuries- Eversion Greenspan, Orthopedic Radiology Remember Ring- Like Structure in Conceptualizing Injury. www.x-strap.com Jack Casey, HMS III Gillian Lieberman, MD Page 17 Appropriate Views • Must always include: 1) AP 2) Mortise (ankle in 10 - 25 degrees of internal rotation) 3) Lateral • May add additional views in questionable cases (i.e. stress views, comparison views with uninjured ankle) Jack Casey, HMS III Gillian Lieberman, MD Page 18 Regions of Interest • Bones of ankle joint • The fifth metatarsal tuberosity should be seen in at least one projection. • Important to visualize anterior process of the calcaneus. Jack Casey, HMS III Gillian Lieberman, MD Page 19 Normal AP Radiograph www.rad.washington.edu Jack Casey, HMS III Gillian Lieberman, MD Page 20 Normal Mortise Radiograph www.rad.washington.edu Foot internally rotated 10- 35 degrees to allow for improved visualization of the mortise. Jack Casey, HMS III Gillian Lieberman, MD Page 21 AP vs. Mortise Views AP Mortise Images from Greenspan, Orthopedic Radiology Jack Casey, HMS III Gillian Lieberman, MD Page 22 Normal Lateral Radiograph Note: ROI not fully included (5th metatarsal absent) www.rad.washington.edu Jack Casey, HMS III Gillian Lieberman, MD Page 23 Classifying Fractures • Anatomic • Weber (AO) • Other Jack Casey, HMS III Gillian Lieberman, MD Page 24 Anatomic Classification of Fx Identifying additional sites of fracture is not just an academic exercise– as bi/tri malleolar fx usually require othopedics eval, surgical management. Greenspan, Orthopedic Radiology Jack Casey, HMS III Gillian Lieberman, MD Page 25 Unimalleolar Fx Patient 1– s/p eversion injury, fall from 10 feet Small fx, medial malleolus Also note dislocation talus Image from BIDMC PACS Jack Casey, HMS III Gillian Lieberman, MD Page 26 Bimalleolar Fx Patient 2- “Fall with ankle inversion. Please r/o fracture” Images from BIDMC PACS Mortise View AP view Jack Casey, HMS III Gillian Lieberman, MD Page 27 Trimalleolar Fx Patient 3- “Eversion injury. r/o fx” (ED films) Images from BIDMC PACS Jack Casey, HMS III Gillian Lieberman, MD Page 28 Trimalleolar Fx ORIF Images from BIDMC PACS Patient 3 (Intra-op) Jack Casey, HMS III Gillian Lieberman, MD Page 29 Weber Classification of Fx • Based on the level of fibular fracture • Used to determine extent of syndesmotic injury. A