Why is tension band wiring (TBW) preferred over screw fixation for medial malleolus fractures?

Tension Band Wiring vs Screw Fixation for Medial Malleolus Fractures

Tension band wiring (TBW) is not definitively superior to screw fixation for medial malleolus fractures—both methods produce equivalent clinical and radiological outcomes, and the choice should be based on specific fracture characteristics: TBW for small avulsion fragments, osteoporotic bone, or when cost-effectiveness is prioritized; screw fixation for larger fragments requiring rigid compression. 1

Evidence Quality and Strength

The most recent and highest-quality evidence comes from a 2023 systematic review and meta-analysis that directly compared TBW versus screw fixation across 512 medial malleolus fracture cases 1. This study found:

• No significant difference in fracture union time (mean difference of -0.59 weeks favoring TBW, but not statistically significant, p=0.35) 1
• No difference in functional outcomes based on Olerud and Molander Ankle scores (OR 1.46, p=0.47) 1
• Equivalent complication rates including delayed union (OR 0.94, p=0.91), superficial infection (OR 1.19, p=0.79), and fixation failure (OR 0.53, p=0.29) 1

An earlier 2016 comparative study suggested TBW may achieve faster union (9.4 vs 11.8 weeks, p=0.03) and better functional scores (90% vs 80% excellent/good results, p=0.049), but this involved only 20 patients and conflicts with the larger meta-analysis 2.

When TBW May Be Preferred

Small avulsion-type fractures: The AO group specifically recommends tension-band fixation for small avulsion fractures of the medial malleolus that are unsuitable for screw fixation 3. These fragments lack sufficient bone stock for adequate screw purchase.

Osteoporotic bone: TBW provides surgeon-controlled compression without relying on thread purchase in poor-quality bone, making it more suitable for elderly patients with osteoporosis 4. Screw fixation in osteoporotic bone risks pullout from tension, compression, and rotational forces 3.

Cost-effectiveness: TBW is technically straightforward and more cost-effective than screw fixation, particularly relevant in resource-limited settings 4.

Nonunion cases: In a neglected 6-month-old medial malleolus nonunion, TBW achieved union within 12 weeks without damaging the inlay bone graft, as the compression is distributed rather than concentrated at screw threads 4.

When Screw Fixation May Be Preferred

Biomechanical superiority under tension: Bicortical screw fixation demonstrates significantly greater stiffness under tension loading compared to TBW—in fact, unicortical screws showed only 10% of the stiffness of bicortical screws 3. However, traditional TBW with stainless steel wire showed comparable pull-out strength (871.33N) to handmade bent pinning (840.25N) in biomechanical testing 5.

Larger fracture fragments: When adequate bone stock exists for bicortical screw purchase, this provides the most rigid fixation construct 3.

Avoiding hardware prominence: While TBW historically required secondary surgery for symptomatic implant removal, this complication can be mitigated by proper technique 3. Screw fixation avoids prominent K-wires entirely.

Critical Technical Considerations

Fracture stability assessment is paramount: Weight-bearing radiographs with medial clear space <4 mm confirm stability 6. Displaced unstable fractures (>2 mm displacement) with medial tenderness, bruising, swelling, or high-energy mechanism require surgical fixation 6.

Standard radiographic protocol: Obtain anteroposterior, lateral, and mortise views to properly assess the fracture 6. MRI without IV contrast is valuable when radiographs are inconclusive for assessing bone marrow contusions and soft-tissue abnormalities 6.

Common Pitfalls to Avoid

• Do not assume one technique is universally superior—the 2023 meta-analysis definitively shows equivalence in outcomes 1
• Do not use unicortical screws when bicortical purchase is achievable—this reduces stiffness by 90% 3
• Do not overlook fractures on routine radiographs—special attention to areas of tenderness is essential as fractures may be radiographically occult 6
• Do not undertreated displaced fractures—this leads to functional limitations and post-traumatic arthritis 6

Practical Algorithm

1. Assess fracture size and bone quality:

   • Small avulsion fragment or osteoporotic bone → TBW 3, 4
   • Large fragment with good bone stock → Bicortical screw fixation 3

2. Consider cost and resource availability:

   • Limited resources or cost constraints → TBW 4
   • Standard resources available → Either technique acceptable 1

3. Evaluate for nonunion:

   • Neglected nonunion with bone graft needed → TBW (avoids graft damage) 4
   • Fresh fracture → Either technique acceptable 1