Summary Acetabulum fractures are pelvis fractures that involve the articular surface of the hip joint and may involve one or two columns, one or two walls, or the roof within the pelvis. Diagnosis can be made radiographically with dedicated pelvis radiographs (including Judet views) but frequently require CT pelvis for surgical planning. Treatment can be nonoperative for non-displaced fractures but displaced injuries require anatomic open reduction and internal fixation to minimize development of post-traumatic osteoarthritis. Epidemiology Incidence ~ 4 per 100,000 per year Demographics fractures occur in a bimodal distribution high energy trauma in younger patients (e.g., motor vehicle accidents) low energy trauma in elderly patients (e.g., fall from standing height) Etiology Pathoanatomy fracture pattern predominately determined by force vector position of femoral head at time of injury bone quality (e.g., age) Associated conditions orthopaedic manifestations lower extremity injury (36%) nerve palsy (13%) login to view 2 more bullets spine injury (4%) systemic injuries head injury (19%) chest injury (18%) abdominal injury (8%) genitourinary injury (6%) Anatomy Osteology acetabular inclination & anteversion mean lateral inclination of 40 to 48 degrees anteversion of 18 to 21 degrees column theory acetabulum is supported by two columns of bone form an "inverted Y" connected to sacrum through sciatic buttress login to view 12 more bullets Vascular corona mortis anastomosis of external iliac (epigastric) and internal iliac (obturator) vessels at risk with lateral dissection over superior pubic ramus Letournel and Judet Classification Letournel and Judet most common referenced classification system classifed as 5 elementary and 5 associated fracture patterns most common fracture patterns younger login to view 6 more bullets elderly login to view 4 more bullets Elementary patterns <i>Illustration</i> AP Obturator ob. Iliac ob. CT Comments Posterior wall Most common Check for injury to superior gluteal NV bundle Posterior column Check for injury to superior gluteal NV bundle Anterior wall Very rare Geriatric fracture pattern Anterior column Transverse Axial CT demonstrates anterior to posterior fx line Only elementary fx to involve both columns Associated patterns <i>Illustration</i> AP Obturator ob. Iliac ob. CT Comments Associated Both Column Characterized by dissociation of the articular surface from the axial skeleton "spur sign" on obturator oblique (constant fragment) Transverse + Post. Wall Most common associated fx Associated with the highest incidence of nerve injury T-type transverse fracture pattern involving the obturator ring Anterior column posterior. hemitransverse Most common in elderly patients Post. column + Post. wall Only associated fracture that does not involve both columns Imaging Radiographs recommended views AP judet login to view 6 more bullets optional views inlet/outlet if concerned for pelvic ring involvement examination under anesthesia (EUA) login to view 4 more bullets findings radiographic landmarks of the acetabulum login to view 8 more bullets roof arc angle login to view 5 more bullets gull sign login to view 3 more bullets spur sign login to view 3 more bullets CT scan indications now considered a gold standard in management findings fracture pattern orientation define fragment size and orientation identify marginal impaction identify loose bodies (e.g., post-reduction) look for articular gap or step-off views 3D reconstruction often helpful for surgical planning. roof-arc measurements findings login to view 3 more bullets Duplex doppler ultrasound indications delayed presentation to treating hospital rule out DVT Treatment Nonoperative protected weight bearing for 6-8 weeks indications login to view 13 more bullets techniques login to view 7 more bullets Operative open reduction and internal fixation (ORIF) indications login to view 12 more bullets outcomes login to view 12 more bullets total hip arthroplasty indications login to view 4 more bullets timing login to view 9 more bullets techniques login to view 2 more bullets outcomes login to view 2 more bullets Techniques Closed reduction percutaneous screws (CRPP) approach anterograde (from iliac wing to ramus) retrograde (from ramus to iliac wing) posterior column screws imaging obturator outlet best view to rule out joint penetration iliac inlet view best to determine anteroposterior position of screw within the pubic ramus obturator inlet view best to determine position of a supraacetabular screw within tables of the ilium Open reduction internal fixation (ORIF) approaches approach depends on fracture pattern two approaches can be combined approaches include login to view 8 more bullets Approaches Indications Risks Anterior Approach (Ilioinguinal) Anterior wall and anterior column Both column fracture Posterior hemitransverse Femoral nerve injury LFCN injury Thrombosis of femoral vessels Laceration of corona mortis in 10-15%. Posterior Approach (Kocher-Langenbach) Posterior wall and posterior column fx Most transverse and T-shaped Combination of above Increased HO risk compared with anterior approach Sciatic nerve injury (2-10%) Damage to blood supply of femoral head (medial femoral circumflex) Extensile Approach (extended iliofemoral) Only single approach that allows direct visualization of both columns Associated fracture pattern 21 days after injury Some transverse fxs and T types Some both column fxs (if posterior comminution is present) Massive heterotopic ossification posterior gluteal muscle necrosis Modified Stoppa Approach Access to quadrilateral plate to buttress comminuted medial wall fractures Corona mortis must be exposed and ligated in this approach Complications Post-traumatic DJD most common complication 80% survival noted at 20 years for patients s/p ORIF risk factors for DJD include age >40 associated fracture patterns, particularly transverse-posterior wall and T-type concomitant femoral head injury treat with hip fusion or THA Heterotopic ossification highest incidence with extensile approach treat with login to view 3 more bullets lowest incidence with anterior ilioinguinal approach Osteonecrosis 6-7% of all acetabular fractures 18% of posterior fracture patterns DVT and PE Infection Bleeding Neurovascular injury risk factor highest incidence with transverse + posterior wall fractures Intraarticular hardware placement Abductor muscle weakness Prognosis Poor outcomes are associated with: multi-system trauma increasing age poor articular congruency marginal impaction associated femoral head articular injury post-traumatic arthritis