summary Capitellum Fractures are traumatic intra-articular elbow injuries involving the distal humerus at the capitellum. Diagnosis is made using plain radiographs of the elbow. Treatment may be nonoperative for nondisplaced fractures but any displacement generally requires anatomic open reduction and internal fixation. Epidemiology Incidence 1% of elbow fractures 6% of all distal humerus fractures Etiology Pathophysiology mechanism of injury typically, low-energy fall on outstretched hand direct, axial compression with the elbow in a semi-flexed position creates shear forces pathoanatomy radiocapitellar joint is an important static stabilizer of the elbow capitellar fracture can cause potential block to motion and instability due to loss of the radiocapitellar articulation Associated conditions concomitant injuries to radial head and/or LUCL can occur up to 60% of the time Anatomy Radiocapitellar articulation essential to longitudinal and valgus stability of the elbow can also lead to coronal plane instability with capitellar excision if medial structures are not intact integral relationship with the posterolateral ligamentous complex of the elbow (i.e. LUCL) Classification Bryan and Morrey Classification (with McKee modification) Type I Large osseous piece of the capitellum involved Can involve trochlea Type II Kocher-Lorenz fracture Shear fracture of articular cartilage Articular cartilage separation with very little subchondral bone attached Type III Broberg-Morrey fracture Severely comminuted Multifragmentary Type IV McKee modification Coronal shear fracture that includes the capitellum and trochlea Presentation History fall on outstretched arm (typically fall from standing) typically, elbow is in semi-flexed elbow position Symptoms elbow pain, deformity swelling wrist pain may also occur Physical exam inspection and palpation ecchymosis, swelling diffuse tenderness range of motion & instability may have mechanical block to flexion/extension and/or rotation neurovascular exam Imaging Radiographs recommended AP and lateral of the elbow best demonstrated on lateral radiograph "double arc" sign created from subchondral bone of capitellum and lateral part of trochlea CT delineates fracture anatomy and classification Treatment Nonoperative posterior splint immobilization for < 3 weeks indications nondisplaced Type I fractures (<2 mm displacement) nondisplaced Type II fractures (<2 mm displacement) Operative open reduction and internal fixation indications displaced Type I fractures (>2 mm displacement) Type IV fractures technique ORIF with lateral column approach indications isolated capitellar fractures type IV fractures that can have trochlear involvement ORIF with posterior approach with or without olecranon osteotomy indications capitellar fractures with associated fractures/injuries to distal humuers/olecranon and/or medial side of the elbow arthroscopic-assisted ORIF indications isolated type I fractures with good bone stock fragment excision indications displaced Type II fractures (>2 mm displacement) displaced Type III fractures (>2 mm displacement) total elbow arthroplasty indications unreconstructable capitellar fractures in elderly patients with associated medial column instability Technique ORIF with lateral column approach approach lateral approach recommended for isolated Type I and Type IV fx supine positioning lateral skin incision centered over the lateral epicondyle extending to 2cm distal to the radial head technique headless screw fixation minifragment screw using posterior to anterior fixation counter sink screw using anterior to posterior fixation mini-fragment or capitellar plates can be used to capture fractures with proximal extension avoid disruption of the blood supply that comes from the posterolateral aspect of the elbow do not destabilize LUCL ORIF with posterior approach with or without olecranon osteotomy approach indicated when more extensive articular work is needed can also be used when concomitant medial sided injuries and/or distal humeral fractures require more fixation lateral decubitus positioning long-posterior based incision along the elbow radial and ulnar based flaps allow access to both medial and lateral sides of elbow technique fracture-pattern specific independent headless compression/cannulated screws for capitellar component supplemental fixation for concomitant pathology parallel or orthoogonal distal humerus plates radial head arthroplasty/ORIF LUCL/UCL repair via bone tunnels or suture anchors Arthroscopic-assisted ORIF approach definitive indications not fully known experienced arthroscopists, indicated for isolated capitellar fractures supine or lateral positioning (dependent on desire for anterior or posterior access) 70 degree scope can be helpful in gaining access can be combined with limited open technique for fracture manipulation technique standard portals (anteromedial, anterolateral, posterolateral) proximal anterolateral portal established under fluoroscopic guidance to place trocar to allow for reduction of fracture fragment extend elbow and push fragment with trocar for reduction flex radial head past 90 to lock reduction anteromedial and posterolateral portals allow for fracture debridement freer elevator can help maintain reduction while cannulated/headless compression screws are placed under fluoroscopic guidance (typically posterior to anterior in direction) Complications Elbow contracture/stiffness (most common) Nonunion (1-11% with ORIF) Ulnar nerve injury Heterotopic ossification (4% with ORIF) AVN of capitellum Nonunion of olecranon osteotomy Instability Post-traumatic arthritis Cubital valgus Tardy ulnar nerve palsy Infection Prognosis Most patients will gain functional range of motion but have residual stiffness Surgical treatment results are generally favorable reoperation rates as high as 48% (mostly due to stiffness)