summary Terrible Triad Injury of Elbow is a traumatic injury pattern of the elbow characterized by elbow dislocation, radial head/neck fracture, and a coronoid fracture. Diagnosis can be made with plain radiographs of the elbow. CT studies are helpful for surgical planning. Treatment is generally ORIF versus radial head arthroplasty, LCL reconstruction, coronoid ORIF, and possible MCL reconstruction. Etiology Characterized by presence of elbow dislocation (often associated with posterolateral dislocation or LCL injury ) radial head or neck fracture coronoid fracture Pathophysiology mechanism fall on supinated forearm and extended arm that results in a combination of valgus, axial, and posterolateral rotatory forces produces posterolateral dislocation pathoanatomy structures of elbow fail from lateral to medial LCL disrupted first anterior capsule injured next possible MCL disruption Anatomy Radial head a primary restraint to posterolateral rotatory instability (PLRI) secondary valgus stabilizer forearm in neutral rotation, lateral portion of articular margin devoid of cartilage roughly between radial styloid and listers tubercle Coronoid process provides an anterior and varus buttress to ulnohumeral joint resists posterior subluxation beyond 30 deg of flexion fracture fragment typically has some anterior capsule attached useful in repair Medial collateral ligament three components anterior bundle most important to stability, restraint to valgus and posteromedial rotatory instability inserts on sublime tubercle (anteromedial facet of coronoid) specifically inserts 18.4mm dorsal to tip of coronoid process posterior bundle transverse ligament Lateral collateral ligament inserts on supinator crest distal to lesser sigmoid notch the primary restraint to posterolateral rotatory instability four components lateral ulnar collateral ligament (most important for stability) radial collateral ligament annular ligament accessory collateral ligament when injured is usually avulsed off of the lateral epicondyle Presentation Symptoms patients complain of pain, clicking and locking with elbow in extension Physical exam possible varus / valgus instability patterns distal radial ulnar joint must be evaluated for possible Essex-Lopresti injury Imaging Radiographs evaluate for concentricity of ulnohumeral and radiocapitellar joints line drawn through center of radial neck should intersect the center of the capitellum regardless of radiographic projection evaluate lateral radiograph for coronoid fracture need prereduction and postredcution films consider PA and lateral films of wrist and forearm when indicated CT often utilized for better evaluation of coronoid fracture 3D imaging for determining fracture line propagation Treatment Nonoperative immobilization in 90 deg of flexion for 7-10 days indications (rare) ulnohumeral and radiocapitellar joints must be concentrically reduced radial head fx must not meet surgical indications coronoid fx must be small elbow should be sufficiently stable to allow early ROM techniques one week of immobilization followed by progressive ROM active motion initiated with resting splint at 90 degrees and forearm pronation, avoiding terminal extension static progressive extension splinting at night after 4-6 weeks strengthening protocol after 6 weeks Operative ORIF versus radial head arthroplasty, LCL reconstruction, coronoid ORIF, possible MCL reconstruction indications terrible triad elbow injury that includes an unstable radial head fracture, a type III coronoid fracture, and an associated elbow dislocation coronoid fractures involving less than 10% of the coronoid do not confer elbow stability in cadaveric studies and therefore do not require repair should instability persist after addressing the radial head and the LCL complex in the presence of a small coronoid fracture, the next best step is MCL reconstruction Techniques ORIF vs replacement of radial head, coronoid ORIF, LCL reconstruction, and possible MCL reconstruction approach posterior skin incision advantageous allows access to both medial and lateral aspect of elbow lower risk of injury to cutaneous nerves more cosmetic technique radial head ORIF vs. arthroplasty radial head ORIF indicated if non comminuted fractures that involve < 40% articular surface 1.5, 2.0, or 2.4mm countersunk screws plate if necessary; 2.0 plates cause minimal loss of motion even when placed on radial neck plate position should be posterolateral safe zone: 90-110 arc from radial styloid to Lister's tubercle with arm in neutral rotation radial head arthroplasty indicated for comminuted radial head fxs (> 3 pieces) implant should articulate 2mm distal to the tip of the coronoid process radial head resection without replacement is NOT indicated in presence of Essex-Lopresti lesion or in ligamentously injured elbows if <25% head damaged or fragments not reconstructable and nonarticulating, can excise fractured portion if elbow stable (rarely indicated) coronoid ORIF can be fixed through radial head defect laterally sutures, suture anchors, screws, or rarely plate fixation. suture passed through 2 drill holes posterior to anterior lag screws if fragment large basal coronoid fxs (rare) fixed with anteromedial or medial plate on proximal ulna FCU split approach preferred for rare isolated coronoid fractures LCL repair usually avulsed from origin on lateral epicondyle reattach with suture anchors or transosseous sutures must be reattached at center of capitellar curvature on lateral epicondyle if MCL is intact, LCL is repaired with forearm in pronation if MCL injured, LCL is repaired with forearm in supination to avoid medial gapping due to overtightening repairs are performed with elbow at 90 degrees of flexion MCL repair indicated if instability on exam after LCL and fracture fixation, especially with extension beyond 30 degrees persistent posteromedial instability following radial head replacement/repair and LCL repair in the setting of a Type I/II coronoid fracture should be managed with MCL repair postoperative elbow fixators - hinged or static consider when instability is noted after complete bone and soft tissue repair immobilization can immobilize elbow in flexion with forearm pronation to provide stability against posterior subluxation if both MCL and LCL were repaired, splint in flexion and neutral rotation rehabilitation initiate active ROM exercises 48 hours after surgery to improve functional outcomes Complications Instability more common following type I or II coronoid fractures Failure of internal fixation most common following repair of radial neck fractures poor vascularity leading to osteonecrosis and nonunion Post-traumatic stiffness very common complication initiate early ROM to prevent Heterotopic ossification consider prophylaxis in pts with head injury or in setting of revision surgery Post-traumatic arthritis due to chondral damage at time of injury and/or residual instability Prognosis Historically poor outcomes secondary to persistent instability stiffness arthrosis