Acetabular fractures are complex intra-articular injuries most commonly resulting from high-energy trauma (motor vehicle collisions, falls from height) in younger patients and low-energy falls in the elderly with osteoporotic bone. [1-2] They require early orthopedic consultation, advanced imaging, and a systematic approach to avoid missed associated injuries and complications.
1. History
- Mechanism of injury: Dashboard injury (knee-to-dashboard in MVC — classic for posterior wall/column), lateral compression, fall from height, or low-energy fall in elderly [2-3]
- Direction of force: Position of the hip at impact determines fracture pattern — flexed/adducted hip → posterior wall; extended/abducted → anterior column [4]
- Pain characterization: Deep groin, hip, or buttock pain; inability to bear weight; pain with any attempted hip motion [5]
- Timing: Acute onset with trauma; delayed presentations possible in elderly with insufficiency fractures [6]
- Associated symptoms: Numbness/tingling in the sciatic nerve distribution (posterior thigh, leg, foot), inability to dorsiflex the foot, urinary retention or hematuria (associated pelvic injury)
- Important negatives: Absence of back pain (to distinguish from lumbar pathology), no prior hip symptoms, no anticoagulant use
2. Alarm Features
- Hemodynamic instability — suggests significant pelvic hemorrhage or associated intra-abdominal injury [1]
- Hip dislocation — posterior dislocation with a shortened, internally rotated, adducted limb is an orthopedic emergency requiring reduction within 6 hours to reduce risk of AVN [7-8]
- Sciatic nerve palsy — foot drop, peroneal distribution numbness (12% incidence with fracture-dislocations) [7]
- Open fracture (Morel-Lavallée lesion) — degloving injury over the greater trochanter/lateral thigh
- Associated injuries: Ipsilateral femoral head fracture, knee ligament injury (dashboard mechanism), pelvic ring disruption, abdominal/urologic injury
- Vascular injury — rare but can involve superior gluteal artery or iliac vessels, especially with anterior column fractures
3. Medications
- Acute pain management: IV opioids (morphine, hydromorphone), acetaminophen, fascia iliaca nerve block for analgesia [5]
- VTE prophylaxis: LMWH (enoxaparin 30 mg BID) is standard; the PREVENT CLOT trial demonstrated aspirin 81 mg BID was noninferior to LMWH for prevention of death after pelvic/acetabular fractures. Early initiation within 24–48 hours of injury reduces VTE and mortality [9-10]
- Heterotopic ossification (HO) prophylaxis: Indomethacin 25 mg TID for 6 weeks or single-dose radiation therapy (700 cGy) postoperatively [2][11]
- Perioperative antibiotics: Anti-staphylococcal coverage (e.g., cefazolin) 1–2 hours before surgery and for 24 hours postoperatively [5]
- Contraindicated: Avoid NSAIDs preoperatively if surgery is planned (bleeding risk); avoid frog-leg positioning for radiographs (fracture displacement risk) [12]
4. Diet
- Calcium and vitamin D supplementation in elderly patients with osteoporotic fractures
- Adequate protein intake to support fracture healing and prevent sarcopenia during immobilization
- Hydration — critical during immobilization to reduce VTE risk and prevent constipation from opioid use
- Long-term: Optimize bone health with dietary counseling if osteoporosis is identified
5. Review of Systems
- Neurologic: Numbness, tingling, weakness in the affected lower extremity (sciatic nerve)
- Urologic: Hematuria, urinary retention (associated urethral/bladder injury in pelvic fractures)
- GI: Rectal bleeding (associated rectal injury in open pelvic fractures)
- Vascular: Coolness, pallor, or absent pulses distally
- Musculoskeletal: Knee pain (ipsilateral femoral shaft fracture, patellar fracture, or ligamentous knee injury from dashboard mechanism)
- Constitutional: Fever (concern for infection if open fracture or delayed presentation)
6. Collateral History and Family History
- Pre-injury functional status — ambulatory status, use of assistive devices (critical for geriatric surgical decision-making) [1]
- Mechanism details from EMS/witnesses — speed of impact, height of fall, position at impact
- Anticoagulant/antiplatelet use — affects hemorrhage risk and surgical timing
- Family history of osteoporosis or metabolic bone disease
- Social context: Living situation, support system (impacts disposition and rehabilitation planning)
7. Risk Factors
- Young adults: High-energy trauma (MVC, motorcycle crash, fall from height) — accounts for ~66% of cases [2]
- Elderly (≥60 years): Low-energy falls with osteoporotic bone — rising incidence; anterior column-based fractures predominate [1-2][13]
- Osteoporosis — most prevalent risk factor for insufficiency fractures [6]
- Medications: Corticosteroids (bone loss), sedatives/hypnotics (fall risk)
- Substance use: Alcohol intoxication (fall and MVC risk)
- Prior fracture or metabolic bone disease [5]
8. Differential Diagnosis
- Femoral neck fracture — shortened, externally rotated limb; distinguished on AP pelvis radiograph [14]
- Femoral head fracture (Pipkin) — often associated with posterior hip dislocation; best seen on CT [12]
- Pelvic ring fracture — pubic rami, sacral fractures; AP pelvis radiograph and CT differentiate [15]
- Hip dislocation without fracture — pure dislocation; postreduction CT needed to exclude occult acetabular fracture [12]
- Greater trochanteric fracture — lateral hip pain, isolated finding on radiograph
- Pathologic fracture — metastatic disease (breast, prostate, lung, renal, thyroid); lytic lesion on imaging
- Labral tear or femoroacetabular impingement — more insidious onset, mechanical symptoms; no acute trauma [16]
9. Past Medical History
- Osteoporosis/osteopenia — affects fracture pattern, fixation strategy, and consideration for arthroplasty [13]
- Prior hip surgery or fracture — alters surgical approach
- Cardiac/pulmonary comorbidities — risk stratification for operative management [1]
- DVT/PE history — influences VTE prophylaxis strategy
- Diabetes, peripheral vascular disease — wound healing concerns
- Dementia/cognitive impairment — affects rehabilitation potential and surgical candidacy
10. Physical Exam
- Vital signs: Tachycardia and hypotension suggest hemorrhage (pelvic/retroperitoneal)
- Inspection: Limb shortening, rotational deformity; posterior dislocation → shortened, internally rotated, adducted; anterior dislocation → externally rotated, abducted [5]
- Palpation: Tenderness over the groin, greater trochanter, or buttock
- Range of motion: Severely limited and painful; do NOT perform frog-leg maneuver [12]
- Log roll test: Pain with gentle internal/external rotation of the hip [5]
- Neurovascular exam: Assess sciatic nerve (peroneal > tibial division) — ankle dorsiflexion, eversion, plantar flexion, sensation in the foot; distal pulses (dorsalis pedis, posterior tibial) [5]
- Skin: Assess for Morel-Lavallée lesion (fluctuant swelling over lateral thigh/trochanter), open wounds
- Secondary survey: Knee exam (ligamentous injury), ipsilateral femur, lumbar spine
11. Lab Studies
- CBC — baseline hemoglobin; serial monitoring for hemorrhage; transfusion threshold Hgb <8 g/dL in asymptomatic patients [5]
- BMP/CMP — renal function (contrast for CT, medication dosing)
- Coagulation studies (PT/INR, PTT) — especially if on anticoagulants or massive transfusion anticipated
- Type and screen/crossmatch — prepare for potential surgical blood loss
- Lactate — marker of tissue hypoperfusion in polytrauma
- Urinalysis — hematuria screening for associated urologic injury
- Pre-operative labs: Consider troponin, BNP in elderly for cardiac risk stratification [1]
12. Imaging
- First-line: AP pelvis radiograph — obtained in trauma bay; assess for fracture lines, femoral head position, and associated pelvic ring injury [12]
- Judet oblique views (obturator oblique and iliac oblique) — essential for fracture classification; evaluate anterior/posterior columns and walls [17]
- CT pelvis without contrast — gold standard for fracture characterization; 3D reconstructions significantly improve classification accuracy (κ = 0.943 vs. 0.236 for plain films); identifies marginal impaction, intra-articular fragments, femoral head injury, and quadrilateral plate involvement [4][18-19]
- MRI — reserved for occult fractures not seen on radiographs/CT, or to evaluate femoral head cartilage and labral injury [12][14]
- Postreduction CT — mandatory after hip dislocation reduction to assess joint congruence and intra-articular fragments [12]
- When imaging is unnecessary: Imaging is always indicated when acetabular fracture is suspected; physical exam alone cannot reliably exclude fracture [12]
13. Special Tests
- Roof arc measurements (Matta criteria): Medial ≥45°, anterior ≥25°, posterior ≥70° on AP and Judet views suggest intact weight-bearing dome and may support nonoperative management [20-21]
- CT subchondral arc: Intact articular surface in the superior 10 mm of the acetabulum on CT supports nonoperative treatment [22]
- Examination under anesthesia (EUA) with dynamic fluoroscopy — benchmark for assessing posterior wall fracture stability; stable fractures on EUA have excellent outcomes with nonoperative management [3][23]
- Judet and Letournel classification — 10 fracture types: 5 elementary (anterior wall, posterior wall, anterior column, posterior column, transverse) and 5 associated (transverse + posterior wall, T-shaped, both column, anterior column/wall + posterior hemitransverse, posterior column + posterior wall) [4]
14. ECG
- Indicated in: Elderly patients, those with cardiac history, or polytrauma patients for preoperative cardiac risk assessment
- Look for: Arrhythmias, ischemic changes, right heart strain (PE if delayed presentation)
- Not routinely needed in young, healthy trauma patients with isolated injury
15. Assessment
Acetabular fractures are high-acuity injuries requiring a systematic, multidisciplinary approach. Key assessment points:
- Bimodal distribution: Young patients with high-energy trauma vs. elderly with low-energy falls [2]
- Posterior wall fractures are the most common type overall; anterior column-based fractures are increasingly common in the elderly [2]
- Severity stratification depends on: displacement (>2 mm), weight-bearing dome involvement, hip stability, associated dislocation, femoral head damage, and marginal impaction [24-25]
- Complications: Posttraumatic osteoarthritis (16.9% at ~44 months), heterotopic ossification, sciatic nerve injury (up to 20%), AVN of the femoral head (11% with dislocation), VTE [2-3][7][26]
- Fracture step-off ≥2 mm on obturator oblique view is a strong predictor of poor long-term outcome [27]
16. Treatment Plan
Initial stabilization (ED)
- ABCs, ATLS protocol for polytrauma
- Hemodynamic resuscitation; pelvic binder if concurrent pelvic ring instability
- Emergent closed reduction if hip is dislocated — ideally within 6 hours [8]
- Skeletal traction (distal femoral pin) for fractures with subluxation or while awaiting surgery
- Fascia iliaca block or IV analgesia
- Early VTE prophylaxis (LMWH or aspirin) within 24–48 hours [9-10]
Nonoperative management — indicated when: [22][24]
- Congruent hip joint on AP and Judet views
- Intact weight-bearing dome (roof arc angles: medial ≥45°, anterior ≥25°, posterior ≥70°; intact superior 10 mm on CT)
- Stable hip joint
- Both-column fractures with "secondary congruence"
- Non-ambulatory or medically unfit patients
- Treatment: Toe-touch or non-weight-bearing for 6–12 weeks with serial radiographs
Operative management — the default for displaced fractures: [24]
- ORIF (open reduction internal fixation) — standard for displaced fractures in medically fit patients; ideally within 3–10 days of injury [8]
- Surgical approaches: Kocher-Langenbeck (posterior), ilioinguinal (anterior), anterior intrapelvic (Stoppa), or combined approaches depending on fracture pattern [2]
- Percutaneous fixation — option for minimally displaced fractures in elderly patients who cannot mobilize due to pain [1]
- Acute THA ± fixation — for elderly patients with poor bone quality, femoral head damage, or pre-existing arthritis [1][13]
- Delayed THA — for posttraumatic arthritis, failed nonoperative management, or AVN [1]
Postoperative
- HO prophylaxis with indomethacin or radiation [11]
- VTE prophylaxis for up to 4–6 weeks [28]
- Early mobilization within 24 hours postoperatively [5]
17. Disposition
- All acetabular fractures require admission — for pain control, traction, VTE prophylaxis, and orthopedic management [1]
- ICU/trauma service: Polytrauma patients, hemodynamically unstable, or associated injuries
- Orthopedic surgery consultation: Mandatory for all acetabular fractures; transfer to a Level I trauma center with acetabular surgery expertise if not available locally [1]
- Observation: Minimally displaced fractures being considered for nonoperative management still require inpatient monitoring
- Specialist consultation triggers: Sciatic nerve palsy (neurosurgery), hematuria (urology), vascular compromise (vascular surgery), geriatric co-management for elderly patients [1]
18. Follow Up / Return Precautions
- Follow-up timing: Orthopedic follow-up at 2 weeks (wound check, radiographs), then at 6 weeks, 3 months, 6 months, 1 year, and annually thereafter [27]
- Serial radiographs: AP pelvis and Judet views to monitor for displacement (nonoperative) or loss of fixation (operative)
- Weight-bearing progression: Typically toe-touch or non-weight-bearing for 6–12 weeks, then progressive weight-bearing based on radiographic healing
- Return precautions — seek immediate care for:
- New or worsening numbness/weakness in the leg or foot
- Increasing pain, swelling, or inability to bear weight as expected
- Signs of DVT/PE: calf swelling, chest pain, shortness of breath
- Fever, wound drainage, or redness (infection)
- Expected recovery: 76–89% achieve good-to-excellent functional outcomes with appropriate treatment; posttraumatic arthritis may develop in ~17% and may require THA [2][11][25][27]
- Long-term: Bone density screening and osteoporosis treatment in elderly; fall prevention strategies; physical therapy for hip strengthening and gait training
References
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