Post on 25-Jun-2018
“Common” Definitions of Fracture HealingUnion
▪Bone’s mechanical stability restored to withstand normal loads ▪ Clinically: no pain at fracture site ▪ Radiographically: 3 out of 4 cortices with bridging callus
Delayed Union
▪Fx not consolidated at 3 months, but progressive callus Non Union
▪No improvement clinically or radiographically over 3 consecutive months ▪A fibrocartilaginous interface
From: OTA Resident Course – Russel, T
High Energy vs. Low Energy
“High Energy" ▪Direct axial load or bending force ▪Fall from height/Motor vehicle crash ▪Soft tissue envelope significantly damaged ▪Comminuted fracture patterns ▪Open fractures “Low Energy“ ▪Twisting mechanism or direct load on
weak bone ▪Fall from standing ▪Less soft tissue injury ▪Simple fracture pattern
“High Energy"
“Low Energy"
Fracture Patterns
Fracture patterns occur based on mode, magnitude and rate of force application to bone
▪Bending Load → transverse fx with wedge segment ▪3-point Bend →Wedge fragment ▪4-point Bend → Segmental fragment
▪Torsional Load → oblique or spiral fx ▪Axial Load → Articular impaction (Plateau, Pilon, etc.)
Fracture Patterns
Understanding these patterns and the inherent stability of each type is important in choosing the most appropriate method of fixation and surgical approach
High Rate of Healing
Spectrum of Healing
Absolute Stability =10 Bone Healing
Relative Stability =20 Bone Healing
Biology of Bone Healing
THE SIMPLE VERSION...
Fibrous Matrix > Cartilage > Calcified Cartilage > Woven Bone > Lamellar Bone
Haversian Remodeling
Minimal Callus
Callus
Biology of Bone Healing
Direct/Primary bone healing ▪Requires rigid internal fixation and
intimate cortical contact –absolute stability ▪Minimal callus formation ▪Cannot tolerate fracture gap ▪Interfragmental compression will
minimize fracture motion ▪Relies on Haversian remodeling with
bridging of small gaps by osteocytes (cutting cones)
Figure from: OTA Resident Course - Russel
Biology of Bone Healing
Indirect/Secondary Bone Healing = CALLUS
▪ Divided into stages ▪ Inflammatory Stage ▪ Repair Stage
▪Soft Callus Stage ▪Hard Callus Stage
▪ Remodeling Stage 3-24 mo
▪ Relative stability
Figures from: OTA Resident Course - Russel
Practically speaking...
Primary/Direct Bone Healing
Simple fracture patterns
See the fx during surgery and directly reduce and fix with:
▪Lag screws
▪Plates and screws
Secondary/Indirect Bone Healing
Complex fracture patterns
Don’t directly see the fracture during surgery (use fluoro)
Indirectly reduce the fx and fix with:
▪IM Rods
▪Bridge plate fixation
▪External fixation
▪Cast
Relative Stability !!!!!!!!Absolute Stability
– IM nailing – Ex fix – Bridge plating –Cast
– Lag screw/ plate
– Compression plate
Fixation Stability
Absolute
(Rigid)
Relative
(Flexible)
Spectrum of Stability
Cast
IM Nail
Compression Plating/ Lag screw
Ex Fix
Bridge Plating
Practically speaking….Most fixation probably involves components of both types of healing. Even in
situations of excellent rigid internal fixation one often sees a small degree of callus formation...
Interfragmentary Compression
▪Lag Screw Plate Functions ▪Neutralization ▪Buttress ▪Bridge ▪Tension Band ▪Compression ▪Locking
Intramedullary Nails ▪Internal splint
Bridge plate fixation ▪Internal splint
External fixation ▪External splint
Cast ▪External splint
Functions of Fixation
*Not internal fixation
Indications for Internal Fixation
Displaced intra-articular fracture Axial, angular, or rotational instability that cannot be controlled by closed methods Open fracture Polytrauma Associated neurovascular injury
MULTIPLE REASONS EXIST BEYOND THESE...
Benefits of Internal FixationEarlier functional recovery !More predictable fracture alignment !Potentially faster time to healing
Screws• Cortical screws:
–Greater number of threads –Threads spaced closer together (pitch is (smaller pitch) –Outer thread diameter to core diameter ratio is less –Better hold in cortical bone !
• Cancellous screws: – Larger thread to core diameter ratio –Threads are spaced farther apart (pitch is greater) – Lag effect with partially-threaded screws – Theoretically allows better fixation in cancellous bone
Figure from: Rockwood and Green’s, 5th ed.
Lag Screw Fixation
Screw compresses both sides of fx together ▪ Best form of compression ▪ Poor shear, bending, and rotational force resistance
Partially-threaded screw (lag by design) Fully-threaded screw (lag by technique)
1
2
Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, 1987.
Lag Screws• “Lag by technique”
• Using fully-threaded screw
• Step One: Gliding hole = drill outer thread diameter of screw & perpendicular to fx !
• Step Two: Pilot hole= Guide sleeve in gliding hole & drill far cortex = to the core diameter of the screw
Lag ScrewsStep Three: counter sink near cortex so screw head will sit flush
Step Four: screw inserted and glides through the near cortex & engages the far cortex which compresses the fx when the screw head engages the near cortex
Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, 1987.
Functional Lag Screw - note the near cortex has been drilled to the outer diameter = compression
Position Screw - note the near cortex has not been drilled to the outer diameter = lack of compression & fx gap maintained
Lag Screws
Figure from: OTA Resident Course - Olsen
Lag Screws!
• Malposition of screw, or neglecting to countersink can lead to a loss of reduction
• Ideally lag screw should pass perpendicular to fx !
Neutralization Plates
Neutralizes/protects lag screws from shear, bending, and torsional forces across fx
“Protection Plate"
Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, 1987.
Buttress / Antiglide Plates
“Hold” the bone up
Resist shear forces during axial loading
▪Used in metaphyseal areas to support intra-articular fragments
Plate must match contour of bone to truly provide buttress effect
• Order of fixation: • Articular surface compressed with bone forceps
and provisionally fixed with k-wires 1. Bottom 3 cortical screws placed
• Provide buttress effect 2. Top 2 partially-threaded cancellous screws
placed • Lag articular surface together
3. Third screw placed either in lag or normal fashion since articular surface already compressed
!
Buttress Concepts
Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, 1987.
Antiglide/Buttress Concepts
Plate is secured by three black screws distal to the red fracture line
Axial loading causes proximal fragment to move distal and to the left along fracture line
Plate buttresses the proximal fragment • Prevents it from “sliding”
Buttress Plate ▪ When applied to an intra-articular fractures
Antiglide Plate ▪ When applied to diaphyseal fractures
Bridge Plates
“Bridge”/bypass comminution
Proximal & distal fixation Goal: ▪Maintain length, rotation, & axial
alignment Avoids soft tissue disruption
at fx = maintain fx blood supply
Tension Band Plates
Plate counteracts natural bending moment seen w/ physiologic loading of bone
▪Applied to tension side to prevent “gapping” ▪Plate converts bending force to compression ▪Examples: Proximal Femur &
Olecranon
JOINT SURFACE
Tension band
Tension Band Theory • The fixation on the opposite side from the articular surface provides reduction and
compressive forces at the joint by converting bending forces into compression • The fracture has tension forces applied by the muscles or load bearing
Load applied to bone
The tension band prevents distraction and the force is converted to compression at the joint
The tension band functions like a door hinge, converting displacing forces into beneficial compressive forces at the joint
JOINT SURFACE
Tension band
Load applied to bone
• Wires can be used for tension band as well • Ex: Olecranon and patella
• 2 K-wires from tip of olecranon across fx site into anterior cortex to maintain initial reduction and anchor for the tension wire !
• Tension wire brought through a drill hole in the ulna !
• Both sides of the tension wire tightened to ensure even compression !
• Bend down and impact wires
Classic Tension Band of the Olecranon
Figure from: Rockwood and Green’s, 4th ed.
Compression Plating
Reduce & Compress transverse or oblique fx’s
▪Unable to use lag screw ▪Exert compression across
fracture ▪Pre-bending plate ▪External compression devices
(tensioner) ▪Dynamic compression w/ oval
holes & eccentric screw placement in plate
Examples- 3.5 mm Plates
LC-Dynamic Compression Plate:
▪ stronger and stiffer ▪more difficult to contour. ▪ usually used in the treatment
radius and ulna fractures
Semitubular plates: ▪ very pliable ▪ limited strength ▪most often used in the treatment of
fibula fractures
Figure from: Rockwood and Green’s, 5th ed.
Figure from: Rockwood and Green’s, 5th ed.
Compression
Fundamental concept critical for primary bone healing Compressing bone fragments decreases the gap and maintains the bone position even when
physiologic loads are applied to the bone. Thus, the narrow gap and the stability assist in bone healing.
Achieved through lag screw or plating techniques.
Plate Pre-Bending Compression
Prebent plate ▪A small angle is bent into the plate centered at the fracture ▪The plate is applied ▪As the prebent plate compresses to the bone, the plate wants to
straighten and forces opposite cortex into compression ▪Near cortex is compressed via standard
methods ▪External devices as shown ▪Plate hole design
Screw Driven Compression Device
Requires a separate drill/screw hole beyond the plate
Concept of anatomic reduction with added stability by compression to promote primary bone healing has not changed
Currently, more commonly used with indirect fracture reduction techniques
Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, 1987.
Dynamic Compression Plates
• Note the screw holes in the plate have a slope built into one side. !• The drill hole can be purposely
placed eccentrically so that when the head of the screw engages the plate, the screw and the bone beneath are driven or compressed towards the fracture site one millimeter.
!
This maneuver can be performed twice before compression is maximized.
Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, 1987.
Dynamic Compression Plating
Compression applied via oval holes and eccentric drilling
▪Plate forces bone to move as screw tightened = compression
Lag screw placement through the plate
Compression can be achieved and rigidity obtained all with one construct
Compression plate first
Then lag screw placed through plate if fx allows
Figure from: Rockwood and Green’s, 5th ed.
Locking Plates
Screw head has threads that lock into threaded hole in the plate
Creates a “fixed angle” at each hole
Theoretically eliminates individual screw failure
Plate-bone contact not critical
Courtesy AO Archives
Locking PlatesMust have reduction and compression done prior to using locking screws ▪ CANNOT PUT CORTICAL SCREW OR LAG SCREW AFTER LOCKING
SCREW
Increased axial stability
It is much less likely that an individual screw will fail
▪But, plates can still break
Locking Plates
Locking Plates
Indications: ▪ Osteopenic bone ▪ Metaphyseal fractures with short articular
block ▪ Bridge plating
Intramedullary Nails
Relative stability Intramedullary splint Less likely to break with
repetitive loading than plate
More likely to be load sharing (i.e. allow axial loading of fracture with weight bearing).
Secondary bone healing Diaphyseal and some
metaphyseal fractures
Intramedullary FixationGenerally utilizes closed/indirect or minimally open reduction techniques Greater preservation of soft tissues as compared to ORIF IM reaming has been shown to stimulate fracture healing Expanded indications i.e. Reamed IM nail is acceptable in many open fractures
Rotational and axial stability provided by interlocking bolts
Reduction can be technically difficult in segmental and comminuted fractures
Maintaining reduction of fractures in close proximity to metaphyseal flare may be difficult
Intramedullary Fixation
• Open segmental tibia fracture treated with a reamed, locked IM Nail.
• Note the use of multiple
proximal interlocks where angular control is more difficult to maintain due to the metaphyseal
flare.
• Intertrochanteric/ Subtrochanteric fracture treated
with closed IM Nail !
• The goal: • Restore length, alignment,
and rotation • NOT anatomic reduction
• Without extensive exposure this fracture formed
abundant callus by 6 weeks
Valgus is restored...
Reduction Techniques…some of the options
Indirect Methods
Traction-assistant, fx table, intraop skeletal traction
Direct external force i.e. push on it
Percutaneous clamps Percutaneous K wires/
Schantz pins—”Joysticks”
External fixator or distractor
Direct Methods
Incision with direct fracture exposure and reduction with reduction forceps
Reduction TechniquesOver the last 25 years the biggest change regarding ORIF of fractures has probably
been the increased respect for soft tissues. Whatever reduction or fixation technique is chosen, the surgeon must minimize
periosteal stripping and soft tissue damage. ▪ EXAMPLE: supraperiosteal plating techniques
• Pointed reduction clamps used to reduce a complex distal femur fracture • Open surgical approach • Excellent access to the fracture to place lag screws with the clamp in place • Remember, displaced articular fractures require direct exposure and reduction
because anatomic reduction is essential
Direct Reduction Technique
• Place clamp over bone and the plate • Maintain fracture reduction • Ensure appropriate plate position proximally and distally with respect to the bone, adjacent joints, and neurovascular structures • Ensure that the clamp does not scratch the plate, otherwise the created stress riser will weaken the plate
Reduction Technique - Clamp and Plate
Figure from: Rockwood and Green’s, 5th ed.
Percutaneous Plating
Plating through modified incisions
▪Indirect reduction techniques ▪Limited incision for: ▪Passing and positioning the
plate ▪ Individual screw placement
▪Soft tissue “friendly”
•Classic example of inadequate fixation & stability !
•Narrow, weak plate that is too short
•Insufficient cortices engaged with screws through plate
•Gaps left at the fx site !
Unavoidable result = Nonunion
Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, 1987.
Failure to Apply Concepts