What are the next steps for a patient, approximately 6 weeks after outpatient treatment for a proximal tibial shaft fracture, with a relatively stable medical history?

Management of Proximal Tibial Shaft Fracture at 6 Weeks Post-Treatment

At 6 weeks post-injury for a proximal tibial shaft fracture treated as an outpatient, the critical next step is radiographic assessment using the RUST (Radiographic Union Score for Tibial Fractures) scoring system to determine healing trajectory and identify patients at risk for nonunion who may require early intervention. 1

Immediate Assessment Required

Radiographic Evaluation

• Obtain standard AP and lateral radiographs to calculate the RUST score, which evaluates cortical bridging and callus formation across four cortices 1
• Patients with RUST ≥10 at 6 weeks have excellent prognosis and will achieve union with continued conservative management 1
• Patients with RUST 6-9 require close monitoring, as 25% with additional risk factors (NURD score ≥7) will develop nonunion 1
• Patients with RUST <6 at 6 weeks are at high risk, with 69% developing nonunion if NURD score ≥7 1

Clinical Assessment

• Evaluate for infection, as infection within 6 weeks of treatment is a statistically significant predictor of nonunion 1
• Assess alignment on radiographs: acceptable parameters are <5 degrees of angular deformity in all planes 2
• Document weight-bearing status and pain levels to guide progression of rehabilitation 3

Risk Stratification for Nonunion

High-Risk Features Requiring Intervention

• Fracture gaps ≥3mm visible on radiographs 1
• Open fracture mechanism (relative risk of nonunion = 8.2) 4
• High-energy trauma mechanism (relative risk of nonunion = 2.9) 4
• Comminuted fracture pattern 4
• Any signs of infection 1

The NURD Score Components

The Nonunion Risk Determination score includes commonly collected clinical variables that, when combined with RUST, predict nonunion risk 1. If your patient has RUST <6 or infection, and NURD score ≥7, there is a 69% chance of nonunion requiring intervention 1.

Treatment Algorithm Based on 6-Week Assessment

For RUST ≥10 (Low Risk)

• Continue protected weight-bearing progression 3
• Advance to full weight-bearing as tolerated 3
• Follow-up radiographs at 12 weeks to confirm continued healing 3
• Expected union time: average 4.3 months for uncomplicated proximal third fractures 3

For RUST 6-9 (Intermediate Risk)

• Increase monitoring frequency with radiographs every 2-3 weeks 1
• Consider early bone stimulation if NURD score ≥7 1
• Plan for potential bone grafting at 3-4 months if no progression 3
• Three patients in one series required open bone grafting at average 6.3 months for delayed union 3

For RUST <6 or Infection Present (High Risk)

• Strongly consider early surgical intervention rather than waiting for established nonunion 1
• If infection present, address with debridement and antibiotics before definitive fixation 1
• Plan for bone grafting or exchange nailing if no improvement by 3 months 3
• One patient with delayed union experienced nail breakage at 8 months and required reamed exchange nailing 3

Alignment Verification

Critical Measurements

• Valgus/varus angulation: must be <5 degrees 2
• Anterior/posterior angulation: must be <5 degrees 2
• Proximal third fractures are particularly prone to malalignment (15.56% malunion rate in one series) 3

Common Pitfall

Proximal tibiofibular joint (PTFJ) dislocation can be easily overlooked and occurs in approximately 1% of tibial shaft fractures 5. Review the proximal fibula position on all radiographs, as missed PTFJ dislocation leads to chronic instability, pain, and potential peroneal nerve palsy 5.

Rehabilitation Progression at 6 Weeks

Weight-Bearing Advancement

• If RUST ≥10 and no pain, advance to full weight-bearing 3
• If RUST 6-9, continue protected weight-bearing with assistive device 3
• If RUST <6, maintain touch-down weight-bearing only until improvement documented 1

Functional Goals

• Average time to knee mobilization should be 3.2 days post-treatment 3
• By 6 weeks, patients should have near-full knee range of motion 3
• Expected lower extremity functional score at final follow-up: 96% for uncomplicated cases 3

Red Flags Requiring Urgent Intervention

• Increasing pain at fracture site (suggests nonunion or hardware failure) 3
• Loss of alignment on serial radiographs (>5 degrees change) 2
• Signs of infection (erythema, drainage, fever) 1
• Persistent fracture gap ≥3mm with no callus formation 1
• Hardware failure (nail breakage typically occurs at dynamic screw hole around 8 months) 3

Expected Healing Timeline

Normal Healing

• Average union time: 17 weeks for uncomplicated fractures 4
• Average union time: 4.3 months specifically for proximal third fractures 3

Delayed Union

• Average healing time: 35 weeks when delayed union occurs 4
• Consider intervention at 3-4 months if no radiographic progression 3

Nonunion

• Average time to diagnosis: 69 weeks if nonunion develops 4
• Early identification at 6 weeks allows intervention before this prolonged timeline 1