Overview
Operative management of fractures is used to achieve anatomic alignment, stable flixation, and allow early mobilization. It can be considred in fractures that are unstable, displaced, intra-articular, open, or associated with polytrauma, neurovacular compromised and failed conservative treatment. Reduction can be achived by closed or open techniques. Surgical options for holding reduction in fractures include internal fixation and external fixation.
- Absolute indications for operative management of fractures
- Open long bone fractures
- Soft-tissue injury that will cannot tolerate casting
- Closed reduction failed (difficult to control the fragments or soft-tissue between the fragments)
- Compromised to neurovascular structures (requires exploration)
- Displaced intra-articular fracture (needs accurate positioning)
- Major avulsion fractures (fragments are held apart by tension force)
- Salter Harris II-IV
- Polytrauma patients (as part of damage control orthopaedics)
- Replantation of extremities
- Relative indications for operative management of fractures
- Delayed union
- Unable to retain closed reduction
- Multiple fractures
- Pathological fractures
Internal Fixation
The main benefit of internal fixation is that it enables immediate mobilisation since it holds the fracture securely. The types of internal fixation include interfragmentary lag screws, plates and screws, intramedullary nails, and cerclage/tension band wires.
Types of internal fixation
| Type | Description |
|---|---|
| Interfragmentary lag screws | Screws are partially threaded across the fracture line to compress the fracture fragment. Provides absolute stability to the fracture site. |
| Cerclage and tension-band wires | Loops of wires are passed around two bone fragments and tightened to compress the fragments together. They essentially convert tension forces at the fracture into compressive forces. |
| Plates and screws | A combination of plates and screws are used for articular, metaphyseal and diaphyseal fractures. Techniques include neutralization, compression, buttressing, tension-band and bridging |
| Intramedullary nail | Rods inserted into the medullary canal in order to splint the fracture. Provides relative stability to the fracture |
- Indications for internal fixation
- Fractures that are not amenable to closed reduction
- Fractures that are unstable and prone to re-displacement after reduction e.g. mid-shaft fracture of the forearm and displaced ankle fractures
- Fractures that are liable to be pulled apart by muscle action e.g. transverse fracture of the patella or olecranon
- Pathological fractures
- Multiple fractures where early fixation (by internal or external fixation) reduces the risk of general complication and late multisystem organ failure
- Fractures in patients who present nursing difficulties e.g. paraplegic, head injury, neuropsychiatric conditions, multiple injuries, very elderly
- Complications of internal fixation
- Infection: iatrogenic infection is the most common cause of chronic osteomyelitis
- Non-union: bones fixed to rigidly with gap between the ends, stripping of periosteum, and damage to blood vessels intra-operatively can lead to non-union
- Implant failure
- Refracture: removing metal implants too soon may cause the bone to refracture (minimum is 12 months, 18-24 months is safer). Bone is still weak after removal and care or protection is needed
Interfragmentary Lag Screws
Lag screws are placed perpendicularly across the fracture line to compress and stabilise the fracture. Lagging is used for simple transverse or short oblique fractures and in intra-articular fractures where anatomical reduction is required.
Components of a screw
| Component | Description |
|---|---|
| Head | Top portion that engages with the screwdriver. May be flat or countersunk. |
| Shank | Portion beneath the head. may be smooth in partially threaded screws |
| Thread | Helical ridges that engage the bone. Determines the purchase and pull-out strength |
| Core diameter | Diameter of the screw shaft excluding the threads. |
| Outer (major diamter) | Diameter of the screw shaft including the threads. Defines drill hole size in the near cortex for lag screws |
| Pitch | Distance between adjacent threads. A smaller pitch = more threads pe unit length leading to better holding in cortical bone |
| Tip | The tip of the screw can be blunt or self-drilling/self-tapping. Determines the insertion method |
| Lead | Distance advanced by one revolution |
| Working distance | Length of bone traversed by the screw in one revolution |
Types of screws
| Type of screw | Description |
|---|---|
| Cortical screw | Has small thread depth, fine pitch and strong core. Used for dense cortical bone e.g. the shaft |
| Cancellous screw | Has large threads, coarse pitch and weaker core. Used for spongy metaphyseal bone |
| Partially threaded screw | Smooth shank with threaded distal portion. Used to provide a lag effect |
| Fully threaded screww | Contains threads throughout the shaft to provide non-compressive fixation or lag effect by overdrilling |
| Locking screw | Contains a threaded head that locks into the plate hole to provide stability in locking plates |
Mechanical properties of screws
| Property | Biomechanical importance |
|---|---|
| Pull-out strength | Resistance to axial displacement. Determined by thread design and bone quality |
| Bending strength | Resistance to bending forces. Determined by core diameter and material |
| Torsional strength | Resistance to twisting or shear during insertion |
| Biocompatibility | Resistance to corrosion and biological safety |
Lagging
| Term | Definition |
|---|---|
| Lagging | Placing a screw in such a way that it engages the far cortex but not the near cortex, allowing it to pull the two bone fragments together and apply compression perpendicular to the fracture plane |
| Lagging by tecnique (overdrilling using a fully threaded screw) | The near cortex is drilled to the outer diameter (gliding hole) and the far cortex is drilled to the core diameter (thread hole) so that the thread engages only the far cortex |
| Lagging by design (partially threaded screw) | The threds only engage the far cortex while the unthreaded portion acts as a gliding surface in the near cortex |
Plates and Screws
In general, plates and screws are used for articular and periarticular fractures where open anatomical reduction is required, followed by absolute stability. They can also be used for extra-articular fractures where mechanical alignment is required with relative stability. They are more effective when placed on the tension side of the bone. Plates and screws are load-bearing – they sustain most of the axial, bending and rotational forces during weight-bearing, thus may not allow for immediate load-bearing.
Plate biomechanics
| Biomechanics | Description |
|---|---|
| Absolute stability (2% strain) | Constructs healing with primary (haversian) healing e.g. compression plating and lag screw + neutralization plate |
| Relative stability (2 – 10% strain) | Constructs healing with endochondral healing (callous formaiton) e.g. bridge plating. Strain must be < 10% or fibrous union will predominate. |
Plate Techniques
| Technique | Description |
|---|---|
| Neutralization (protection) | An interfragmentary lag screw is placed across the fracture line for compression then a plate is applied to resist torque and shortening in order to supplement the effect of lag screws. |
| Buttressing | The plate and screws resist compression of the fracture due to axial forces by applying force against the axis of deformity i.e. by holding the fracture up |
| Bridge plating | Fixation is away from the main zone of injury at the ends of the plate i.e. the plate acts like a bridge between simple or multi-fragmentary fractures. This provides relative stability at the fracture site and restores correct length, axis and rotation, with minimal soft tissue stripping hence avoiding injury at the main zone |
| Compression plating | A cortical screw is placed eccentrically into an oval hole in the plate to compresses the fracture segments (Dynamic compression plating – DCP). This provides absoulte stability to achieve primary bone healing, especially for metaphyseal and diaphyseal fractures |
| Tension-band | A (concave) plate is placed on the tensile surface of the bone to convert the tension force into compression force. Useful for transverse fractures |
| Locking | Placing locking screws into plate forming an internal fixator providing angular stability. E.g. volar plate in distal radial fracture |
- Advantages of plates and screws
- Used for anatomic reduction
- Allows early mobilisation
- Can provide either absolute or relative stability
- Disadvantages of plates and screws
- Can cause further injury or interfere with the fracture site
- Causes periosteal and soft-tissue damage
- Does not normally allows for immediate load bearing
- Potential for infection
- Implant failure
- Need for plate removal
Intramedullary Nails
Intramedullary nails are primarily used for diaphyseal fractures (tibia and femur) where mechanical aligmnet is required with relative stability of the fracture sites to allow for endochondral healing. Current nails incorporate locking screws which are placed proximally and distally to provide rotational stability and maintain length and alignment.
Historically, Kuntscher nails were used by a Nazi surgeon in world war II to fix fractures in prisoners of war. They have a clover-lead cross section and provided fixation at 3 points (proximal, midhsaft and distal). Rotational stability was achieved by a tight canal fit. Current intramedullary nails have locking screws which are placed proximally and distally to provide rotational stability and maintain length and alignment.
The nails can be placed in an antegrade or retrograde fashion.
Properties of intramedullary nails
| Property | Description |
|---|---|
| Reaming | Surgical enlargment of the medullary canal using a powered reamer of a long bone to accomodate a large-diameter IM nail. Reamed nails have a higher rate of union than non-reamed nails |
| Radius of curvature | How much the nail is curved, representing the arc radius of the nail’s sagittal bow. A smaller radius of curvature gives a more Curved nail. IM nails can be pre-contoured with a certain ROC to match the femurs, which has a natural anterior bow. A nail that is too straight can perforate the anterior cortex distally |
| Interlocking | Interlocking screws are placed at the ends of the intramedullary nail to resist rotational forces. Interlocking can be dynamic or static |
| Static interlocking | Prevents rotation and axial motion in sunstable fracture sites by providing a more rigid fixation |
| Dynamic interlocking | Allows controlled compression at fracture sites by using an elongated screw hole (dynamic slot). Used for transverse fractures (axially and rotationally stable) |
Reamed vs unreamed intramedullary nail
| Reamed | Unreamed | |
|---|---|---|
| Time to insert | Longer | Faster |
| Time to union | Shorter | Longer |
| Size of implant | Larger | Smaller |
| Reduction of distal fracture | Easier | More difficult |
| Strength fo construct | More | Less |
Placement of intramedullary nails
| Direction of entry | Entry point |
|---|---|
| Antegrade nail | Placed on the proximal bone towards the distal bone e.g. piriformis or greater trochanter for femoral shaft fracture |
| Retrograde nail | Placed on the distal bone towards the proximal bone e.g. femoral condyles for femoral shaft fracture |
- Advantages of intramedullary nails
- Minimally invasive
- Enable early weight-bearing
- Less periosteal damage than ORIF
- Disadvantages of intramedullary nails
- Increased fat emboli and chest complications
- Infections of IM nails are difficult to treat
- Difficult to remove when broken
Tension Band Wiring
Tension band wiring converts tensile forces into compressive forces at the fracture site during dynamic loading (during joint movement. They involve 2 K-wires placed across the fracture for axial alignment and to prevent rotational displacement, and a figure-of-eight wire loop tightened around the K-wires to compress the fracture. They are commonly used for olecranon fractures and transverse patella fractures.
Kirschner wires (K-wires)
Kirchner wires (K-wires) are smooth, non-threaded, thin, flexible wires (0.9 – 2.5 mm in diameter) that are used to hold small fracture fragments in place. They are often used for temporary or definitive fixation of fractures, as part of tension band wiring, and to guide cannulated screws or reamers. They can also be used to supplement plaster casts. K-wires for definitive fixation are used for supracondylar fractures, distal radius fractures and phalangeal and metacarpal fractures.
- Indications for K-wires
- Temporary fixation
- Definitive fixation of small fracture fragments of the wrist and hand
- Tension band wiring for patella and olecranon fractures
- Temporary immobilisation of small joints
External Fixation
External fixation involves stabilizing fractures by applying a metallic frame external to the body, connected to bone by percutaneous metallic rods or wires proximal and distal to the fracture.
Types of external fixators
| Classification | Type |
|---|---|
| Uniplanar (Monolateral) fixator | Pins are placed in a single plane, on one side of the body. Used for temporary stabilization since it is easire to apply |
| Biplanar or multiplanar fixator | Pins are placed in more than one frame e.g. in an orthogonal configuration. Has increased stability and rotational control |
| Circular fixator (llizarov frame) | Uses tensioned wires fixed to the rings. Allows for precise correction of deformity, bone transport, and compression/distraction. Indicated in limb-lengthening, deformity correction and infected non-union. |
| Hybrid circular/tubular fixator | Combines circular rings and half-pins e.g. for periarticular fractures. Offer flexibility and are less bulky than llizarov frames. |
| Taylor spatial frame | A sophisticated external circular fixator that uses 6 adjustable struts (hexapod sytem) between two rings to allow controlled, gradual 3D bone movement. It is an evolution of the llizarov frame. |
Parts of an external fixator
| Part | Description |
|---|---|
| Schanz screw (pin) or tensioned wires | Transfix the bones above and below the fractures and are connected to each other by bars or circular frame. Can be either half pins (unicortical) or transfixing wires |
| Clamps | Connects the pins/wires to rods or rings |
| Rods (bars) | Tubular frames placed externally that bridges the fracture |
| Rings | Circular ring construction placed externally that are used in fixators like llizarov |
- Temporary indications for external fixation (damage controle orthopaedics)
- Severe soft tissue damage e.g. burns, crush and degloving injuries (allows repeated access for wound assessment, dressing and reconstruction)
- Open fractures Gustilo type II and III
- Polytrauma patients as part of damage control orthopaedics (DCO) to limit operative time and blood loss
- Peri-articular fractures with severe soft-tissue oedema e..g tibia plafond fracture
- Stabilization of pelvic fractures with severe bleeding
- Compartment syndrome post-fasciotomy
- Osteomyelitis
- Neurovascular injury requiring access for repair e.g. stabilizing dislocated knee joint after reduction while vascular surgeon repairs arterial injury
- Definitive indications for external fixation
- Severely comminuted or segmental fractures unsuitable for internal fixation
- Septic (infected) non-union (to alllow debridement and bone transport)
- Limb-lengthening procedures (llizarov tecnique)
- Arthrodesis
- Pelvic ring injuries (anterior ring stabilization)
- Factors that increase the stability of external fixators
- Larger diameter of pins
- Fracture reduction
- Additional pins
- Decreased bone to rod distance
- Increasing space between the pins
- Advantages of an external fixation
- Does not interfere with the fracture site
- Can be adjusted after application without surgery
- Minimal damage to blood vessels
- Minimal interference with soft tissue coverage
- Soft tissue is accessible for plastic surgery
- Allows rapid stabilisation of fractures
- Easy to remove
- Good option when there is significant risk of infection
- Disadvantages of an external fixator
- Damages soft-tissue structures
- Overdistraction can lead to non-union
- Pin-site infection
- Interferes with plastic surgical procedures
- Soft-tissue tethering
- Cumbersome for patients
