Functional Cast Bracing

Principle and Mechanism

• Muscle contraction forces generated during functional activity produce compressive loads across the fracture, which stimulate callus formation and secondary bone healing.
• Gravity-assisted alignment - particularly relevant for the humerus, where gravity keeps the hanging arm in distraction and corrects angulation.

"The theory behind how bracing and cast immobilization maintain tibia alignment centers around the hydraulic pressure exerted on the fracture by circumferential forces on the noncompressible fluid-based tissues of the leg." - Rockwood and Green's Fractures in Adults, 10th ed.

Construction

• Two plastic (polypropylene) shells, applied medially/laterally or anteriorly/posteriorly
• Adjustable Velcro straps that can be tightened to achieve a custom fit
• A cotton stockinette worn underneath to protect skin
• For the humerus: a collar-and-cuff sling is used alongside the brace

1. Acute phase (0-7 days): Temporary immobilization with a coaptation splint, hanging arm cast, or sling and swathe
2. Transition (day 7-10 / once swelling subsides): Switch to the functional brace
3. Rehabilitation phase: Progressive joint motion and weight bearing encouraged

Clinical Applications

1. Humeral Shaft Fractures (Most Common Use)

Patient wearing a functional humeral brace (A, B) with corresponding radiographs showing the fracture and in-brace alignment (C, D, E) - Rockwood and Green's, 10th ed.

• Nonunion rate: 2.6% overall (1.5% closed, 5.8% open fractures)
• Mean healing time: 9.5 weeks (closed), 14 weeks (open)

• 80% had <15 degrees anterior/posterior angulation

• 88.6% lost <10 degrees shoulder motion; 92% lost <10 degrees elbow motion
• Average varus angulation: 9° (transverse), 4° (oblique), 8° (comminuted)

• Varus/valgus: up to 15-20 degrees (debatable)
• Anterior/posterior: up to 20 degrees
• Malrotation: up to 30 degrees
• Shortening: up to 3 cm (with some bone contact maintained)

• Daily elbow flexion-extension to prevent stiffness
• Pendulum shoulder movements from the start
• Avoid resting the arm on a chair arm, table, or lap (causes varus angulation)
• Avoid active abduction and elevation exercises early
• Regular skin inspection and cleaning (fungal infection risk)

2. Tibial Shaft Fractures

1. Long leg cast or splint for 2-4 weeks (until swelling reduces and early callus forms)
2. Transition to short leg patellar tendon-bearing (PTB) cast or fabricated functional brace

• Nonunion rate: 1.1%
• 94% healed with ≤12 mm shortening
• 90% healed with ≤6 degrees angulation
• Mean final shortening: 4.3 mm (strongly correlated with initial shortening - suggesting that initial shortening is not improved by bracing)

• Open fractures
• Initial shortening >12 mm
• Intact fibula (risk of late angular deformity)

3. Other Applications

• Forearm (radius/ulna) fractures - less common, more challenging due to rotation
• Femoral shaft fractures - historically used, now largely replaced by intramedullary nailing
• Isolated lateral malleolar fractures (Weber A / SAD I) - functional bracing or cast with comparable outcomes

Indications

Contraindications

• Pathologic fractures
• Nonunion (pre-existing)
• Significant vascular injury
• Soft tissue injury that physically precludes brace application
• Noncompliant patient (compliance is essential)
• Ipsilateral forearm or elbow fractures (for humeral bracing)
• Initial shortening >12 mm (tibia)

Complications

• AO type A (transverse) pattern
• Proximal third location
• Large interfragmentary gap
• Absence of bridging callus at 6 weeks

When to Convert to Surgery

• Open fracture with instability or contamination
• Unstable fracture pattern (severe comminution, segmental)
• Ipsilateral forearm or elbow injury ("floating elbow")
• Polytrauma requiring early limb mobilization
• Progressive or unacceptable deformity on serial radiographs
• Persistent nonunion

Recent Evidence

• Zhou et al. 2025 (PMID 40069691) - compared cast immobilization vs. removable braces in ankle fractures
• Spaans et al. 2026 (PMID 41950582) - compared cast immobilization vs. early functional treatment after surgical fixation of ankle fractures (found early functional treatment favored for wound healing)

• Rockwood and Green's Fractures in Adults, 10th ed. 2025 - Chapters 37 (Humeral Shaft), 63 (Tibial Shaft)
• Sabiston Textbook of Surgery, Chapter 40 (Humeral shaft fractures)
• Bailey and Love's Short Practice of Surgery, 28th ed.

Böhler-Braun Splint

Eponym and History

• Lorenz Böhler (1885-1973) - Austrian trauma surgeon who added the proximal pulleys for femoral traction
• Heinrich Braun (1862-1934) - German surgeon who designed the original single-pulley frame for distal tibial/calcaneal traction

What It Is

• Hospital/ward based
• Fixed to the bed
• Designed for continuous definitive or bridging traction

1. Relaxes the iliopsoas, reducing the tendency of the proximal fragment to flex in femoral shaft fractures
2. Allows the patient to be nursed comfortably (can turn, use bedpan)
3. Provides access for wound care and dressings
4. Directs traction force along the line of the femoral shaft

Structure

Traction Application

• Steinmann pin, Denham pin, or Böhler pin (threaded centrally to resist migration)
• Attached to a stirrup/bow, connected by cord over a pulley to hanging weights

Pin Insertion Sites

Indications

With Traction

• Femoral shaft fractures - pre-operative bridging (to IM nailing within 24-48 hrs); maintains length and reduces pain
• Subtrochanteric femur fractures
• Supracondylar fractures of the femur
• Tibial shaft fractures with displacement/overlap
• Acetabular fractures - skeletal traction to maintain femoral head in socket and prevent superior migration while awaiting ORIF (typically 3-14 days post-injury)
• Paediatric femoral fractures (>10 years, >15-20 kg - when Gallows traction inappropriate)
• Hip dislocations (occasionally, post-reduction)

Without Traction

• Open/compound fractures without overlap - for wound dressing and care
• Soft tissue injuries to the leg
• Cellulitis, gangrene, amputation stump - elevation and rest
• Post-operative elevation of the limb

Advantages

• Traction unit is self-contained (mobile traction possible for transport within ward)
• Limb held in comfortable, physiological position
• Angle of traction changeable by rerouting the pulley - no need to change the entire arrangement
• Simultaneous traction through calcaneal and tibial tuberosity pins possible
• Full access for wound care, dressings, and examination
• Patient can be turned for nursing care and linen change
• Allows bedpan use

Disadvantages and Complications

Key principle: In modern practice, the Böhler-Braun is a bridge to surgery, not a definitive treatment. For femoral shaft fractures, IM nailing should proceed within 24-48 hours. Prolonged traction dramatically increases DVT, pressure sore, knee stiffness, and muscle wasting risk.

Monitoring - The 5 P's

1. Pulse / pins and needles - distal neurovascular status: sensation, pulse, capillary refill, pain on passive dorsiflexion (compartment syndrome)
2. Pressure sores - heel, ischium, other bony prominences
3. Pin tract infection - pain, swelling, redness, discharge at pin sites
4. Physiotherapy - ankle mobilization (prevent equinus/foot drop), anti-foot drop splint at night, static quadriceps, knee mobilization
5. Portable radiograph - biweekly (or as needed) in first 2 weeks, then weekly; adjust weight and traction direction accordingly

Comparison: Böhler-Braun vs Thomas Splint

Nursing Care Summary

1. Ensure weights hang freely at all times (not touching bed or floor)
2. Cord must run freely over pulleys without kinking
3. Slings should support but not constrict; reposition slings regularly
4. Heel must NOT rest on the frame - use gel heel protector
5. Turn patient toward the splint for back care and linen changes (split sheet technique - two folded sheets, one proximal and one distal to the splint)
6. Apply anti-embolism stocking to the unaffected leg
7. Passive patellar mobilization to prevent patellofemoral adhesions
8. Chest physiotherapy to prevent pulmonary complications
9. In supracondylar femoral fractures: pad the fracture site to prevent angulation; avoid padding at the knee joint (which can cause angulation)

Thomas Splint

History and Original Design

Parts of the Thomas Splint

Thomas splint applied with skin traction - Pye's Surgical Handicraft, 22nd ed.

Sizing the Splint

1. Ring size - Measure the oblique circumference of the thigh immediately below the gluteal fold and ischial tuberosity. This equals the internal circumference of the padded ring. If oedema is present, add 2 inches to the measured value.
2. Length - Measure distance from the crotch (ischial tuberosity) to the heel, then add 6-9 inches (15-23 cm). This gives the length of the inner side bar. The distal end must protrude beyond the foot to allow traction to be applied, and must end at least 2.5 inches (6 cm) above the heel to avoid pressure on the Achilles tendon.

Indications

• Femoral shaft fractures - primary indication (emergency and ward use)
• Subtrochanteric fractures (with modification)
• Distal femoral / supracondylar fractures (with pin through upper tibia)
• Septic arthritis of the knee (original use - rest and immobilization)
• Emergency field immobilization and transport of any lower limb fracture (first aid)

• Neck of femur or pelvic fractures (ring cannot be fitted correctly)
• Supracondylar femoral fracture or fractures involving the knee joint (ring position interferes)
• Fractures of the ankle or foot
• Large wounds in the buttock/thigh that would prevent fitting the ring
• Partial amputation with only marginal tissue connecting the distal limb (skin traction contraindicated)
• Patient refusal

Preparation of the Splint

1. Under the thigh
2. Under the knee (with a small pad allowing ~5° knee flexion)
3. Just above the tendo calcaneus (heel must NOT rest on the sling - leaves it free)

Application Technique

1. Apply skin traction extensions (Elastoplast/adhesive foam strapping, 7.5-10 cm wide) to each side of the limb - the outer strip placed slightly posteriorly, the inner strip slightly anteriorly. This arrangement counteracts the tendency for external rotation at the fracture site.
2. Secure extensions with circumferential crepe bandages ending just above the malleoli. Orthopaedic felt pads hold the extension tapes away from the malleoli to prevent pressure sores.
3. One person maintains manual longitudinal traction while the splint is passed over the foot and slid up the limb.
4. Push the splint gently up to the ischial tuberosity. Maintain a 1-finger gap around the entire circumference of the padded ring (too tight = pressure necrosis; too loose = no countertraction).
5. Pass the outer traction tape over the lateral bar and the inner tape under the medial bar (further resisting external rotation tendency).
6. Tie tapes over the distal W-piece. If more traction is needed, a wooden bar may be used as a windlass (Spanish windlass technique) to increase tension.
7. Adjust slings to support the limb comfortably, with the knee in slight flexion.

Types of Traction with the Thomas Splint

Fixed Traction (Thomas's Original Method)

• Traction force generated by tying the skin extension tapes to the distal end of the splint - force is contained within the splint itself
• Countertraction comes from ring pressure on the ischial tuberosity
• Self-contained system - portable, ideal for field/transport use
• The traction and counterforce are within a closed system
• Used to maintain reduction once achieved

Sliding (Dynamic/Balanced) Traction

• Tapes/cords connect the traction pin to hanging weights over a pulley at the foot of the bed
• Countertraction provided by patient's own body weight - the foot end of the bed is elevated so the upward component of body weight acts as counter-traction
• Amount of bed elevation is proportional to the traction weight used
• Allows physiological muscle activity and more comfortable nursing
• Used in ward setting for prolonged traction

Thomas Splint with Pearson Knee Attachment

• Allows the knee to be held in flexion (more comfortable and reduces proximal fragment flexion deformity)
• The angle of knee flexion can be adjusted by varying the two splint components
• A balanced traction cord connects over the Steinmann pin stirrup
• Traction weight: no more than 10 lb (4.5 kg) - over-distraction is harmful; reduce to 5 lb after 2-3 weeks

Thomas splint with Pearson attachment and skeletal traction - Pye's Surgical Handicraft

Steinmann Pin Insertion Sites

Manipulation of Fracture on Thomas Splint

Complications and Aftercare

Pressure Sores

• Proximal: perineum, groin, ischial tuberosity - from ring pressure. Relieved by increasing traction tension.
• Distal: Achilles tendon, over malleoli, under the heel - from sling/tape pressure. Prevented by adequate padding and ensuring heel is free.

Neurovascular

• Common peroneal nerve palsy - compression at fibular neck by slings or bandages
• Compartment syndrome - pain on passive dorsiflexion is a warning sign
• Distal pulse and capillary refill checked regularly

Other Complications

• Pin site infection (with skeletal traction) - Staphylococcus aureus; daily pin care
• Joint stiffness (knee, ankle) - physiotherapy essential
• DVT / pulmonary embolism - anticoagulation; anti-embolism stockings on unaffected limb
• Over-distraction - too much traction weight; non-union risk
• Malrotation - inadequate correction of external rotation tendency
• Hypostatic pneumonia - chest physio required

Comparison: Fixed vs Sliding Traction

Key Facts Summary

• Originally designed for TB knee (ambulant use) - repurposed for femoral shaft fractures in WWI
• Ring is oval, at 120° to the inner side bar, outer bar protrudes 2 cm to clear the greater trochanter
• 1 finger gap around ring at ischial tuberosity
• Distal end must be 2.5 inches above the heel
• Outer tape over lateral bar, inner tape under medial bar - to prevent external rotation
• Pearson attachment + skeletal pin needed for muscular young patients
• Maximum traction weight with skeletal pin: ~10 lb; reduce to 5 lb after 2-3 weeks
• Unlike the Böhler-Braun: Thomas splint is portable and suitable for pre-hospital transport; Böhler-Braun is hospital-fixed with a superior pulley system for prolonged ward traction

Skeletal Traction

Definition

"Traction is defined as a stretching force on a limb to pull a fracture straight." - Bailey and Love's Short Practice of Surgery, 28th ed.

Principles of Traction

1. The traction force - applied to the limb (via pin/skin)
2. The countertraction force - resists the traction to prevent the patient sliding

• The patient's own body weight (in sliding/balanced traction, bed tilted)
• A fixed point on the patient's body (e.g., ring of Thomas splint on ischial tuberosity - fixed traction)

Skeletal vs Skin Traction

"Skeletal traction is generally more effective and a safer option for patients in which the traction is intended to remain in place for a longer period of time (i.e., polytrauma patients who may not be cleared for surgery)." - Sabiston Textbook of Surgery

Types of Traction

1. Fixed Traction

• Force and countertraction are self-contained within the splint
• Best example: Thomas splint - cord tightened to splint end (windlass), ring bears on ischial tuberosity
• Portable - patient can be transported
• Used for: acute field immobilization, emergency transport

2. Sliding (Balanced/Dynamic) Traction

• Traction force: hanging weights over a pulley at the foot of the bed
• Countertraction: patient's own body weight (foot of bed elevated)
• Patient confined to bed but joint motion possible if system is carefully arranged
• Used for: prolonged ward traction (on Thomas splint with Pearson attachment, or Böhler-Braun frame)

3. 90-90 Skeletal Traction (Paediatric)

• Hip and knee each held at 90° flexion
• Pin in distal femur or proximal tibia
• Used in children: proximal femoral fractures, paediatric femur fractures (>2 years, too large for Gallows traction)
• Pins must be placed parallel to the axis of the knee joint (oblique pins cause varus or valgus deformity)
• Avoid short-leg cast for traction application - risk of compartment syndrome from compression when femur shortens after anaesthesia

4. Hamilton-Russell Traction

• A pulley system designed so the resultant pull acts in line with the femur regardless of limb position
• Used for: fractures of the upper femur and hip conditions
• Can be applied via skin extensions or a tibial pin

5. Gallows (Bryant's) Traction

• Both legs suspended vertically by skin traction, buttocks just lifted off bed
• Used in: children under 2 years with femoral shaft fractures
• Contraindicated in children >2 years or >15-20 kg (risk of vascular complications from elevation)

6. Skull Tong / Halo Traction

• For cervical spine fractures and dislocations
• Gardner-Wells tongs or halo device inserted through skull outer table
• Still used acutely for cervical spine management

Indications for Skeletal Traction

Note: In modern practice, skeletal traction has been largely replaced by IM nailing and ORIF. It is now primarily a bridging measure to surgery (within 24-48 hours), not a definitive treatment for most fractures.

Pin Types

Steinmann Pin

• Solid, smooth, non-threaded metal pin
• Inserted using a hand chuck or power drill
• Disadvantage: can rotate in bone if stirrup is not free-moving → causes bone erosion and sepsis

Denham Pin (Threaded)

• Has a central threaded section that engages cortical bone
• Resists axial migration more reliably than Steinmann pin
• Preferred when prolonged traction is anticipated

Kirschner Wire (K-wire)

• Thin flexible wire (0.9-2.5 mm)
• Used for lighter traction loads (metacarpal traction, paediatric patients)
• 5/64-inch Steinmann pin equivalent used in children for 90-90 traction

Pin Insertion Sites and Technique

Distal femur skeletal traction pin - frontal and lateral radiographic views (Sabiston Textbook of Surgery)

General Insertion Technique

1. Full aseptic precautions (gown, gloves, sterile drape) - preferably in theatre
2. Local anaesthesia to skin and periosteum on both sides (entry and exit points)
3. Small stab incision on entry side (lateral for most lower limb pins)
4. Blunt dissection down to bone with artery forceps
5. Pin advanced perpendicular to bone long axis, in the coronal plane, with limb in neutral
6. When skin tents on far side, make second stab incision before pin exits
7. Pin confirmed on fluoroscopy to ensure correct position and not intra-articular
8. Stirrup/bow applied - must move freely on pin (if the stirrup grips, the pin rotates → osteomyelitis)
9. Wounds covered with benzoin tincture or dry dressings
10. Post-procedure radiograph to confirm alignment and weight adjusted

"It is important that the stirrup through which the traction is applied should move freely on the pin, otherwise the pin rotates in the bone and sepsis and loosening follow." - Pye's Surgical Handicraft, 22nd ed.

Traction Weights

Monitoring - "Safe Zones" Checklist

1. Pulse / Pins and needles - distal NV status, pain on passive stretch (compartment syndrome)
2. Pressure sores - heel, sacrum, elbows
3. Pin tract - infection signs: redness, swelling, discharge, loosening
4. Physiotherapy - ankle pumps, static quadriceps, joint mobilization
5. Portable radiographs - biweekly in first 2 weeks; adjust weights as needed

Complications

Pin-Related

Traction-Related

Advantages and Disadvantages Summary

Modern Role of Skeletal Traction

• A bridging measure to definitive surgery (IM nail, ORIF) within 24-48 hours
• Used in resource-limited settings where fixation is unavailable
• Still first-line for cervical spine fracture-dislocations
• Pre-operative traction for acetabular fractures (maintains femoral head position)
• Paediatric 90-90 traction for specific age groups
• Still relevant for open/infected fractures where implants are contraindicated