40 - External Fixation - Rails Flashcards
1
Q
History of rails
A
Hoffmann (1938)
o Unilateral fixator with universal joint that allows fracture fragments to be aligned in all three planes
o Osteotaxis: To move bone into place
Ilizarov (1951)
o Father of modern external fixation
2
Q
External fixation devices
A
- Unilateral Frame (“rails”)
- Circular Frame (“rings”)
- Spatial Frame (computerized correction via minor adjustments over time)
- Hybrid Frame (not used a lot in podiatry, combines circular and unilateral principles)
- Each has advantages and disadvantages
3
Q
Notes on unilateral frame (“rails”)
A
- A rail is a unilateral straight line or bar
- Usually attached to the osseous segments with threaded pins
- Looks like a rod with threads on it that look like screws
- These insert right into the bone
- This is effective if you are trying to lengthen the bone
- They make these for any bone – they come in many shapes and sizes
- Mini-rail is available for foot and ankle surgery – this is what we will do in external fixation lab
- Some rails are straight and only move in one direction
- Some actually have joints that allow correction in multiple different planes
- When you crank the screws, the clamp with move closer together (compression) or farther apart (expansion or distraction)
4
Q
External fixation
A
- The purpose is to anchor multiple osseous fragments or segments together through the use of wires, pins and rods
5
Q
Advantages over internal fixation
A
- Decreased soft tissue dissection (no incision site)
- Immobilization of multiple regions of affected limb w/ compression/distraction at different sites
- Allow debridement or grafting around fixation
- Immediate mobilization (circular or hybrid)
- Post-op adjustment (if you put on a plate wrong, the only way to fix it is another surgery)
6
Q
Weightbearing with external fixation
A
- Patients can weight bear after external fixation, which is a major advantage
- They are able to distribute the forces of weightbearing throughout the leg, not just on the site of the break
- Good for those who hurt their only good leg, needed for transfers and to complete ADLs – prevents nursing home placement
7
Q
Principles of external skeletal fixation
A
Avoid and respect all vital anatomic structures in the area
o You do this with any surgery, but we have to do a lot of the pin insertion blindly
o We are not making incisions, just taking a pin through the skin and driving it into bone
o Need to have a very good idea of the anatomy in the area so you don’ hit vital structures
Allow access to the injured area for later fixation, bone grafting, debridement and soft tissue reconstruction
Meet the mechanical demand of both the patient and the injury
8
Q
Safe zones or corridors
A
- Corridors exist for safe wire insertion
- Corridors change as you move distally
- Understand cross-sectional anatomy
- Medial and anterior surface of tibia are safe zones
- Foot (avoid tarsal tunnel and dorsal structures) – the rest is pretty safe for pin insertion
9
Q
Unilateral fixators
A
- For use in the wrist, tibia, femur, ankle, and small bones of the hand and foot
- Systems are divided into small and mini-fixators
- Configuration includes a straight bar forms and/or articulated and rotational properties
- These fixators are capable of producing either a distraction or a compressive force
- Articulations can be added to produce triplane correction or motion once the fixator has been secured in the bone
- Straight bar is only capable of unilateral distraction or compression
- Attach to the bone through the use of multiple half pins screwed into the bone and attached to the fixator by clamps
10
Q
Indications for unilateral fixators
A
- Primary fusion of joints (if you want to fuse a joint, you take out the cartilage, clamp the bone together to allow the two bones to fuse)
- Lengthening of bone (callus distraction to get rid of the callus and create hard new bone)
- Osteomyelitis (if you had to remove bone for osteomyelitis, you have a gap, so you can allow infection to heal, pack with bone graft, put on the ex-fix device and let the bone grow in)
- Joint distraction
- Comminuted fractures (if your bone is in so many pieces that you can’t get screws in there, you can use ex-fix to maintain alignment until the pieces all heal together)
- Bone defect
- Excessive shortening trauma
- Soft tissue defects
- Osteoporotic bone (if the bone is soft, the screws will not hold, so internal fixation will not be effective)
11
Q
Materials for unilateral fixators
A
- Constructed of surgical stainless steel or titanium
- We are now seeing a lot of graphite because it is radiolucent so you do not get an artifact on radiographs
12
Q
Foot and ankle indications
A
- Transverse Plane Deformities
- Brachymetatarsia
- Fractures
- Hallux Limitus
- Joint Fusion
13
Q
Companies for external fixators
A
o Cynthies, DePuy, Orthofix = brands that carry external fixation – look up online
o If you can put one of these on, you can put any of them on – they have the same principles
14
Q
Jones fractures
A
- Jones fracture: a transverse fracture that occurs at the 5th metatarsal proximal to the diaphyseal-metaphyseal junction
- Jones fractures are associated with delayed healing due to the tenuous vascular supply at this region – “watershed area” at base of 5th metatarsal
15
Q
Treatment of Jones fractures
A
- Several fixation methods have been described: monofilament wire, k-wire pinning, plating.
- Percutaneous screw fixation is popular. It avoids unnecessary dissection but does not allow for compression and the optimal screw size continues to be debated (4.5, 5.5, 6.5)
- Lombardi et al found the average healing time with external rail fixation to be 5.7 weeks
- Sometimes Jones fractures can take up to 18 weeks to heal, so this is a major improvement
- Easily preformed, allows for minimal dissection and allows for significant compression to be applied across the fracture site – creates compression at the fracture site
16
Q
Hallux limitus
A
- A condition involving the first metatarsal-phalangeal joint in which there is LIMITED motion and joint jamming
- This is different from hallux rigidus, which is an ABSENCE of motion
17
Q
1st MTPJ arthrodiastasis for hallux limitus
A
- Talarico and Vito et al JAPMA (2005) 95(2) described the joint preserving and joint restoring procedure
- The studied 133 patients with excellent long term results
- Distraction of the joint allows for relief of abnormal joint pressures, forces, and muscular imbalances that cause the destructive jamming of the joint
- Constant distraction results in microangiogenesis that results in an increased reparative process and nutrition in the articular cartilage
- 119 patients (89%) maintained a two fold increase in joint dorsiflexion over a 12 month follow up period from 31 degrees preoperatively to 69 degrees postoperatively
- Study never identifies whether it was prospective or retrospective and results reported in aggregate
18
Q
Arthrodiastasis protocol
A
- The external fixation is used to distract the proximal phalanx and the 1st metatarsal and re-establish joint space
- An articulated uni-lateral fixator is applied across the joint of the foot and maintained for
6 weeks, followed by a period of physical therapy - During the distraction period, the patient is full weight bearing as tolerated
19
Q
Benefits of arthrodiastasis
A
- Allows for immediate weight bearing
- Allows for early range of motion
- Preserves cartilage
- Minimally Invasive procedure
- Does not eliminate any further treatment options
20
Q
Disadvantages of arthrodiastasis
A
- Pin tract infection and importance of compliance
- Limited results for severe cartilaginous pathology
- Little research has been published
21
Q
Review of literature for arthrodiastasis
A
- Nogarin & De Bastiani (1983) Foot Surg
- Magnan & Bragantini (1984): Modified Stone with distraction for a minimum of 60 days
- DeHeer (2003):distraction for approximately 42 days
22
Q
CASE STUDY I: Arthrodiastasis
A
- 43 y/o male presents with progressive pain and limitation of motion at the 1st MPJ of left foot
- PMH: HTN, hypercholestrolemia
- Meds: Metroprolol, Lipitor
- NKDA
- Truck driver
- Neurovascular status intact
- Limited ROM with pain at the 1st MPJ
Post-Operative Course o Day 1-5: rigid o Day 3: distracted 5mm o Day +5: loose device and conduct ROM exercises bid o Removal of device at 18 days
23
Q
CASE STUDY II: Arthrodiastasis
A
- Using the Straight MiniRail Lengtheners
- Courtsey of Edgardo R. Rodriguez, DPM (Chicago)
24
Q
Arthrodesis of the 1st MPJ
A
- Can used as sole fixation or in combination with internal fixation
- Typical joint resection
- Application of dorsal or medial device
- Position of fixation paramount concern
25
Brachymetatarsia
- Congenital shortening of the metatarsal (most commonly the 4th metatarsal)
- Premature fusion of metatarsal physis, unknown etiology
- Can be due to trauma (growth plate damage as child) - a common use of external fixation
26
Surgical goals of brachymetatarsia
- Alleviate Pain
- Establish a cosmetically acceptable foot
- Restore a functional metatarsal parabola
27
Osteotomy versus Corticotomy
Notes:
o Ostotomy: you actually
cut through bone – there is a fear that the heat from the saw will kill some of the osteophytes that you are trying to get to regenerate
o Corticotomy: if you are afraid of osteophyte death from an osteotomy, you can do a corticotomy where you will drill a bunch of holes around the metatarsal then knock the holes with an osteotome and a mallet, so you don’t heat up the bone as much
From the slides:
- Corticotomy- Circumferential drill holes around cortex, preserving the endosteum.
- Technically difficult and found to be of little clinical significance.
- Osteotomy - Technically easier requiring less dissection.
28
Other considerations in distraction
- Level of Osteotomies (Want to stay out of the shaft or diaphysis because it is all cortical bone)
- Latency Period
- Rate and Frequency of Distraction
- Ossification Period
- Postop Management
- Complications
29
Level of osteotomy
***********************
***Diaphyseal Osteotomy***
o Pin placement is relatively easier and a periosteal sleeve can be created and resutured following osteotomy.
o Less metabolically active bone.
***Metaphyseal Osteotomy***
o Greater diameter, increased osteogenic potential and greater amount of soft tissue coverage.
o Difficult manipulation and pin placement.
30
Latency period
*************
- ***Literature supports 5 days to 2 weeks latency period before callous distraction begins***
- White and Kenwright found that a delay in distraction allowed for an increased volume of callus as a result of increased vascularity in the area of the corticotomy
EXAMPLE: 4 met, 2 cm short (20 mm)
o Surgery
o 14 days – START TURNING
o 21 days
31
Rate and frequency of distraction
| *************
***Current recommendation of 0.25 mm every 6 hours (1mm/day) until radiographic findings are sufficient***
Example: say you want to distract a bone 2 cm (20 mm)
o Insert ex-fix device, wait 2 weeks until begin turning screws
o If you do 20 mm at 1 mm/day, it will take 20 days (2.5 weeks)
o Then, however long it took you to achieve that length (20 days in our case), you leave the device on for that much time (an extra 2.5 weeks without turning screws)
Should be modified if medical conditions exist that would impede osteogenesis. Small bones of foot may do well with less distraction per day.
Caution with slowing too much or with latency periods which could freeze bone in length.
32
Ossification period rule of thumb
*************
- ***Rule of thumb is 1:1 ratio with the time required to lengthen***
33
Post op management and ambulation
- Some propose limited weight bearing until full consolidation has been obtained
- Some propose full weight bearing once skin coaptation has been obtained
- Risk is relative to the strength of the external fixation construct, patient compliance and patient weight
34
Complications
- Loss of joint motion (minimized if lengthened
35
CASE PRESENTATION III
- CB is a 10 year old female who presented with bilateral brachymetatarsia of the 4th metatarsals. Patient reports moderate pain to 3rd and 5th toes and social anxiety regarding short toes.
- No significant medical history.
- Surgery was performed 10-24-02 with callus distraction with mini-rail fixator.
36
Corticotomy for brachymetatarsia and Evans calcaneal osteotomy
- Evans lateral column lengthening
37
Pilon fracture (for your reference)
- Fracture of the Tibial Plafond – Convoluted fracture of the distal tibia
- External fixator can be used to maintain length and provide alignment of fracture fragments
38
Metatarsal fracture (for your reference)
- Help to maintain length
- Provide compression
- Minimal dissection
39
Open fractures (for your reference)
- Provides alignment of fractures
- Maintains adequate soft tissue length
- Allows for continued debridement of wound
- Can be used even if the foot is currently infected or becomes infected
