How should a 63-year-old woman with a left superior and inferior pubic ramus fracture from a horse fall three weeks ago, now presenting with severe right buttock pain radiating to the ankle and lateral lower‑leg numbness, be evaluated and managed?

Urgent Evaluation for Sciatic Nerve Injury and Posterior Pelvic Ring Disruption

This patient requires immediate advanced imaging with CT pelvis and urgent neurosurgical/orthopedic consultation for a likely delayed sciatic nerve injury from an unstable posterior pelvic ring fracture that was missed or has progressed since the initial injury.

Critical Clinical Context

The presentation of severe right buttock pain radiating to the ankle with lateral lower leg numbness three weeks after a left pubic ramus fracture is highly concerning for:

• Sciatic nerve injury from posterior pelvic ring disruption 1
• Unstable pelvic fracture that was initially underappreciated 1, 2
• Sacroiliac joint or sacral fracture commonly associated with pubic rami fractures 1

The contralateral (right-sided) symptoms with a left-sided anterior ring fracture strongly suggests bilateral pelvic ring injury or posterior ring involvement that is causing nerve compression. 2

Immediate Diagnostic Workup

Primary Imaging - CT Pelvis with 3D Reconstruction

• CT scan with 3D bone reconstruction is mandatory to identify posterior ring injuries (sacral fractures, sacroiliac joint disruption) that may have been missed on initial radiographs [1, @36@]
• Contrast-enhanced CT helps evaluate for hematoma formation that could be compressing the sciatic nerve 1
• 68% of patients with displaced inferior pubic ramus fractures have posterior ring injuries, and 60% of these are unstable 2

Neurological Assessment Priority

• Document motor function: ankle dorsiflexion (L4-L5), great toe extension (L5), ankle plantarflexion (S1) 1
• Sensory mapping: lateral leg numbness suggests L5 or common peroneal nerve involvement 1
• Assess for foot drop or paralysis, which indicates threatened limb requiring urgent intervention 1

MRI Pelvis Consideration

• MRI is indicated if CT shows equivocal posterior ring injury or to better characterize nerve compression 1
• Superior for detecting stress fractures and soft tissue/nerve pathology that CT may miss 1

Classification and Stability Assessment

Fracture Pattern Recognition

• Unstable pelvic fractures (Tile C, Young-Burgess APC2/3, LC2/3) associating bilateral ischio-pubic rami and sacroiliac dislocation carry the greatest risk of lower urinary tract injuries and neurovascular complications 1
• Superior and inferior pubic ramus fractures together increase likelihood of posterior instability (p < 0.001) 2
• Displaced inferior ramus fractures warrant detailed posterior ring investigation 2

Management Algorithm

If Posterior Ring Injury Confirmed:

1. Immediate orthopedic/trauma surgery consultation for potential surgical stabilization 1
2. Neurosurgical evaluation if nerve compression from hematoma or bony displacement is identified 1
3. External fixation or internal fixation may be required for unstable patterns to prevent further nerve injury 1
4. Bleeding control within 60 minutes if active hemorrhage or large hematoma (≥500 cm³) is present, even without contrast extravasation 1

If Isolated Anterior Ring Fracture:

• Consider insufficiency fracture in this 63-year-old female, particularly if osteoporotic 1
• Initiate osteoporosis evaluation and treatment with bisphosphonates (alendronate/risedronate first-line) to prevent secondary fractures 1
• Pain management and protected weight-bearing until fracture union 3, 4

Critical Pitfalls to Avoid

• Do NOT assume isolated pubic ramus fractures are "benign" - they frequently indicate posterior ring injury requiring different management 2, 3
• Do NOT rely on initial radiographs alone - 11 of 63 patients (17%) with pubic ramus fractures required additional imaging for diagnosis 3
• Do NOT delay CT imaging when neurological symptoms develop, as this represents potential nerve compromise requiring urgent intervention 1
• Do NOT miss bilateral injuries - the contralateral symptoms suggest more extensive pelvic ring disruption than initially appreciated 2

Specific Concerns for This Patient

Urological Evaluation

• Perform retrograde urethrocystogram if any urinary symptoms present (inability to urinate, hematuria, blood at meatus) before catheterization 1
• Lower urinary tract injuries occur in 4-19% of pelvic fractures, particularly with bilateral rami and sacroiliac injuries 1

Fracture Healing Monitoring

• Initial displacement ≥16 mm is a risk factor for nonunion requiring active treatment 4
• Conservative treatment fails in 3.5% of pubic ramus fractures, leading to chronic pain and functional deterioration 4

Secondary Fracture Prevention

• Orthogeriatric multidisciplinary approach is warranted for this elderly patient with fragility fracture 1
• Systematic fracture risk evaluation and anti-osteoporotic therapy should be initiated regardless of DXA results in pelvic insufficiency fractures 1