Tension Band Principle

Core Concept

Understanding Eccentric Loading

• Tension side (convex): under tensile (pulling/distracting) stress - this is where fractures tend to gap open
• Compression side (concave): under compressive stress - this tends to remain intact

Diagrams

Prerequisites for the Principle to Work

1. Eccentric loading - the fracture must be subjected to bending, not pure axial load
2. Intact compression cortex - the concave (compression) side must be intact or reconstructed. If there is comminution or a gap on the compression cortex, there is no fulcrum, and the implant bears all the load - it will eventually fatigue and fail

Practical Applications

Implants Used as Tension Bands

• Cerclage wire (figure-of-8) wrapped around K-wires - classic for patella and olecranon
• Plates - applied to the tension surface (most versatile)
• Cannulated screws with wire - modified tension band for patella/olecranon
• Suture anchors / non-absorbable sutures - used in osteosuture/tension band fixation in osteoporotic bone

Key Takeaway

A tension band does not rigidly neutralize forces. Instead, it redirects them - every tensile force generated by muscle contraction or loading is redirected as compression across the fracture surface. This means that patient movement and muscle activity actually enhance fracture healing rather than disrupt it - the hallmark of this elegant biomechanical principle.

Tension Band Wiring - Indications, Contraindications & Complications

INDICATIONS

Fundamental Prerequisite

1. Eccentrically loaded bone - bending forces present at the fracture site
2. Simple (non-comminuted) transverse fracture pattern - fragments must be large enough for wire purchase
3. Intact or reconstructable compression cortex - the opposite cortex must act as a fulcrum

Specific Indications

General rule: TBW is suitable for any avulsion-type fracture where a strong muscle or ligament pulls a bony fragment away - the tension band converts that pull into interfragmentary compression.

CONTRAINDICATIONS

Absolute Contraindications

Relative Contraindications

• Very small/thin bone fragments (insufficient bone stock for wire)
• Fractures with associated ligamentous instability of the joint
• Active infection at operative site
• Severe soft tissue damage overlying the hardware site

COMPLICATIONS

Intraoperative

• Malreduction - failure to achieve anatomic articular surface alignment
• Nerve injury (ulnar/median) - if K-wires exit too far on anteromedial ulna during olecranon TBW
• Biceps tuberosity impingement - if wires exit laterally during olecranon fixation, can cause heterotopic ossification and radioulnar synostosis

Early Postoperative

• Loss of fixation / fixation failure
  • Most common in comminuted fractures (where TBW was wrongly applied)
  • K-wire backing out
  • Wire breakage
• Wound complications / infection - hardware is subcutaneous with minimal soft tissue cover (especially olecranon/patella)

Late Complications

Pitfalls and Prevention (from Rockwood & Green)

Key Clinical Points

• Hardware removal rates for olecranon TBW approach 50-70% - some surgeons now prefer plates to avoid this
• A recent prospective RCT comparing plate fixation vs TBW for olecranon fractures found similar clinical outcomes but lower hardware removal rates with plating
• Early active mobilization is not just permitted after TBW - it is essential for the principle to work, as muscle contraction drives compression across the fracture
• In osteoporotic bone, cannulated screws with suture tape (modified tension band) perform better than K-wire + stainless steel wire constructs

Cubitus Valgus Deformity - Surgical Correction

Background

• Cosmetic deformity
• Tardy ulnar nerve palsy (most feared - develops years later due to chronic stretching of ulnar nerve)
• Reduced elbow ROM
• Elbow instability (in severe cases)

Pre-operative Planning - Calculating the Correction Angle

• Measure the preoperative carrying angle on a standing AP radiograph
• Normal carrying angle = ~10-15°
• Correction needed = Preoperative angle - 10° (normal)

Types of Osteotomy

1. MILCH OSTEOTOMY (Displacement / Opening Wedge Osteotomy)

• A transverse (or slightly oblique) osteotomy is made in the distal humeral metaphysis just proximal to the condyles
• The distal fragment is displaced medially (for cubitus valgus) to restore the normal carrying angle
• The lateral cortex opens like a hinge; the medial cortex shifts to restore alignment

1. Posterior muscle-splitting approach to distal humerus; protect radial nerve proximally
2. Split triceps fibers; identify ulnar nerve (transpose anteriorly if tardy ulnar nerve palsy present)
3. Transverse osteotomy at the level of intersection of forearm axis with lateral humeral cortex
4. Notch the inferior surface of proximal fragment to receive apex of distal fragment
5. Move distal fragment medially (for valgus correction) until normal carrying angle is restored
6. Confirm correction radiographically with elbow in extension
7. Fix with two crossed K-wires or cannulated screws
8. Long arm cast for 4-6 weeks

• Technically straightforward
• Preserves bone stock (no bone removed)
• Allows correction of large deformities

• Potential lateral gap (requires bone graft in opening wedge variant)
• Risk of lateral cortex fracture
• Some rotational instability

2. DOME OSTEOTOMY (Barrel Vault / French Osteotomy)

• Instead of a flat cut, the osteotomy is made as a curved (dome-shaped) cut centered on the axis of rotation within the distal humeral metaphysis
• The dome shape allows rotation of the distal fragment in any plane without changing the overall bone length
• The cut is made like the arc of a circle; the distal fragment can be rotated under the proximal dome without creating a gap or limb shortening

1. Posterior approach to distal humerus
2. Draw the planned correction angle on the bone using a template
3. Make multiple drill holes along the planned dome (arc) at the supracondylar level
4. Connect holes with osteotome to create curved cut
5. Rotate the distal fragment until deformity is corrected
6. Fixation with crossed K-wires or plate

• No limb shortening (bone ends remain congruent after rotation)
• Stable construct - curved surface resists shortening
• Can simultaneously correct angular deformity in multiple planes (valgus + internal rotation)
• Excellent cosmetic result - no lateral condylar prominence

• Technically demanding (requires precise arc-cut planning)
• Risk of hinge fracture if curve not executed correctly
• Longer operative time

3. STEP-CUT OSTEOTOMY (DeRosa and Graziano)

• A combination of a transverse cut and a short longitudinal (step) cut
• The step configuration allows the distal fragment to both angulate (varus correction) and translate medially simultaneously
• The bone surfaces lock together (the "step") providing inherent rotational stability

1. Posterior approach to distal humerus
2. Draw the correction wedge preoperatively (apex medially, base laterally)
3. Make a transverse cut proximally, then a short longitudinal ("step") cut, then complete the wedge
4. Close the wedge laterally - angular correction + medial translation simultaneously
5. Fixation with a single cortical screw (or crossed K-wires)

• Inherent rotational stability - the step prevents rotation, so less hardware needed
• No lateral bony prominence
• Avoids shortening through step translation
• Simpler fixation (single screw may suffice)
• Good correction of both angular deformity and internal rotation component

• More complex bone cut than simple wedge
• Requires accurate preoperative templating
• Moderate learning curve

Comparison Table

Tardy Ulnar Nerve Palsy - Management

• Deformity correction alone (any osteotomy) often relieves ulnar nerve tension
• Anterior transposition of ulnar nerve is not always mandatory if the corrective osteotomy is done well - the nerve becomes lax after deformity correction
• However, anterior transposition should be added if: pre-operative TUNP is severe, nerve subluxation is present, or nerve shows no recovery post-osteotomy