Trauma Principles (Complete) Flashcards
What are the principles of external fixation?
•Two general types:
- Monolateral/unilateral external fixation– frames are positioned on one side of the limb
- Circular external fixation
•Monolateral/Unilateral External Fixation
- Components = pins, clamps, connecting rods
- Stability is increased by:
- Larger diameter half pins (most important)
- Increasing the number of pins
- Increasing pin spread in each fragment
- Minimize the pin-fracture site distance
- Minimize the bone-connecting rod distance
- Place pins out of plane to one another
- Adding an additional connecting bar in parallel (‘double stacking’)
- Increase the stiffness of the connecting rod (increase diameter, carbon fibre > stainless > titanium)
- Add a second unilateral fixator for multiplanar fixation
- Pin mechanics
- Pin stiffness increases with increasing diameter
- Too large = increases risk of fracture (pin >30% of bone diameter substantially increases the risk of pin site fracture)
- Too small = increases micromotion at pin-bone interface (leading to failure)
- Pin diameter guidelines:
- Femur – 5 or 6 mm
- Tibia – 5 or 6 mm
- Humerus – 5 mm
- Forearm – 4 mm
- Hand, Foot – 3 mm
- Half pin vs. transfixion (full) pins
- Half pin protrudes from bone/skin from one side, has bicortical fixation
- Transfixation pins protrudes from bone/skin on two sides, has bicortical fixations, has higher risk of neurovascular injury
- Principles of insertion
- Avoid heat necrosis (sharp drill bits, frequent pauses, clear flutes, etc)
- Protect soft tissues
- Avoid neurovascular structures and joints
- Pin stiffness increases with increasing diameter
What are the pin placement locations in respective bones for external fixation?
[J Am Acad Orthop Surg 2015;23:683-690]
oHumerus = 5mm pins placed anterolaterally (avoid axillary n, radial n, and olecranon fossa)
oUlna = 4mm pin proximally and 3mm pin distally along subcutaneous border (preferred over radius)
oRadius = 4mm pin along radial border (posterior to radial artery and superficial radial n)
o2nd metacarpal = 3mm pin entering radial border of 2nd MC base
- Flex fingers at time of pin insertion, avoids entrapment of extensor tendon which would prevent finger flexion
oFemur = 5mm pins placed anterolaterally or direct lateral
oTibia = 5mm pins placed anteromedial
oCalcaneus = 5mm pin placed medial to lateral in safe zone (posterior to the halfway point from the posteroinferior calcaneus to the inferior medial malleolus and posterior to the one-third mark from the posteroinferior calcaneus to the navicular tuberosity)
- Structures at risk = calcaneal nerve (medial), sural nerve (lateral)
oFoot = medially into the talar neck, cuneiforms, or first metatarsal base, or laterally into the cuboid or fifth metatarsal base. For cuneiform pin placement, the pin should enter the dorsal half of the medial cuneiform
What are 2 types of traction?
[J Am Acad Orthop Surg 2016;24:600-606]
- Skin traction - pulling force is applied to the skin and soft tissue of the limb using adhesive traction tape, halters, belts, or boots
- Skeletal traction involves a more invasive and direct pull on a bone through surgically placed pins, wires, or tongs
What are the 3 most common sites for lower extremity skeletal traction?
[J Am Acad Orthop Surg 2016;24:600-606]
- Distal femur
- Indications
- Acetabular fractures not involving the weightbearing dome
- Pelvic fractures with a displaced hemipelvis
- Adult proximal third femur fracture
- Pediatric femoral shaft fracture (90/90 traction)
- Any contraindication to a proximal tibia pin
- Pin location
- Placed from medial to lateral
- >0.7 cm proximal to the adductor tubercle near the metaphyseal flare
- Avoids joint and femoral artery in the adductor hiatus
- Proximal tibia
- Indications
- Femoral fractures located in the distal 2/3 of the shaft
- Contraindications
- Ligamentous knee injuries
- Tibial plateau fractures
- TKA with a long stemmed implant
- Pin location
- Placed from lateral to medial
- 2.5cm posterior and 2.5cm distal to the tibial tubercle parallel to the joint
- Calcaneus
- Indications
- Tibial shaft fractures
- Distal tibia fractures
- Subtalar dislocation
- Intra-op distraction during ankle arthroscopy
- Pin location
- Placed medial to lateral
- Safe zone is 3.1cm radius around the posterior inferior calcaneus
- Calcaneal nerve (medial) and sural nerve (lateral) at risk
Described the general technique for application of skeletal traction
[J Am Acad Orthop Surg 2016;24:600-606]
- Local anaesthetic infiltrated into skin, soft tissues, and periosteum of both entry and exit sites
- Sharp incision of skin at entry site
- Blunt dissection of underlying soft tissue with blunt snap
- Insert either K-wire (smooth) or Steinmann pin (threaded)
- Pin diameter should be <30% of the bone diameter
- Pass pin through near and far cortex until tenting of the soft tissue at the exit site
- Incise the skin then advance the pin to final position.
- Apply traction bow with padding to adjacent skin.
- The weights are determined by the age, bone quality, and body habitus of the patient as well as the traction placement
* Bowline, cow-hitch and slipknot are most effective knots for suspending weights - Recommend post reduction xrays 6-12 hours after application to allow muscles to relax.
What are the advantages and disadvantages of using a threaded pin/wire (vs smooth) for skeletal traction?
[J Am Acad Orthop Surg 2016;24:600-606]
Advantages:
- Less likely to loosen
- Easier to advance through bone
Disadvantages:
- More likely to bend
- More traumatic to soft tissues at entry/exit sites
***A centrally threaded pin may be allow for easier advancement with less trauma to soft tissues
What are the risks of a transcortical (i.e. unicortical) traction pin?
[J Am Acad Orthop Surg 2016;24:600-606]
- Generate heat (thermal injury)
- Loosen
- Prone to infection
What are the indications for skeletal traction in acetabular and pelvic fractures?
[J Am Acad Orthop Surg 2016;24:600-606]
- Mainly a temporizing measure until definitive surgery
- Immediate treatment of acetabular fractures with:
- Incarcerated intra-articular fragments
- Persistent subluxation of the femoral head
- ***Injuries often associated with posterior wall fractures
- Medialization of the femoral head secondary to quadrilateral plate disruption
- Traction pin should be placed in distal femur
- Only use trochanteric pins intraop, due to increased infection risk with prolonged use
- Pelvic ring injuries with complete disruption of the posterior sacroiliac complex, as seen in vertical shear injuries, may require skeletal traction to help reduce the displaced hemipelvis.
- Traction may also be an adjunct for a combined acetabular and pelvic ring injury that has been temporarily stabilized with an external fixator.
What are the contraindications to skeletal traction in acetabular and pelvic fractures?
[J Am Acad Orthop Surg 2016;24:600-606]
- Nondisplaced acetabular fractures that are stable at fluoroscopic stress examination
- Acetabular fractures through the weightbearing dome (irreducible with traction)
What are the indications for skeletal traction in femoral neck and hip dislocations?
[J Am Acad Orthop Surg 2016;24:600-606]
None
- No improvements in pain or intra-op reduction
- A prospective pilot study used digital subtraction
angiography to assess the blood supply to the femoral head before and after traction.- The application of 3-5 kg of traction significantly diminished the flow within the retinacular vessels that supply the femoral head
- Authors concluded that traction is a possible risk factor for the development of AVN
What are the definitions of nonunion and delayed union?
[Rockwood and Green 8th ed. 2015]
- Nonunion = fracture has failed to heal in the expected time and is not likely to heal without new intervention
- Delayed union = fracture has failed to heal in the expected time but still has the potential to heal without further intervention
When is a fracture of a long bone considered nonunion?
[JAAOS 2013;21:538-547]
- Lack of healing 6-9 months following injury
* Delayed union after 4 months - No interval healing on two consecutive radiographs 6-8 weeks apart
What are factors that contribute to nonunion?
[Rockwood and Green 8th ed. 2015]
1.Fracture factors
- A. Fracture location
- Anatomic sites with limited or watershed vascular supply (eg. diaphysis of long bones, talar neck, scaphoid waist, femoral neck, proximal meta-diaphysis of 5th MT)
- B. High-energy fractures
- Comminution
- Bone loss
- Periosteal stripping
- Soft tissue stripping
- C. Open fracture
2. Host factors - Smoking and nicotine products
- Diabetes
- Peripheral vascular disease
- Medications – steroids, NSAIDs, chemotherapy, bisphosphonates
- Poor nutrition – protein, calcium, Vit D
- Osteoporosis
- Advanced age
- Immunosuppression
- Radiation exposure
3. Surgeon factors - Inadequate fixation stability
- Soft tissue disruption
4.Infection
How are nonunions classified?
[Rockwood and Green 8th ed. 2015]
- Septic nonunion
- Atrophic nonunion (poor stability, poor biology)
- A. Radiographic features – absence of any bony reaction
- B. Fracture has inadequate healing response (due to above factors)
- C. Treatment requires biologic stimulus – bone autograft, BMP, debridement of nonviable bone ends to bleeding bone
- Hypertrophic nonunion (poor stability, good biology)
- A. Radiographic features – abundant callus formation with a dark line
- B. Fracture has adequate healing response but inadequate stability
- C. Treatment requires rigid stabilization
4.Oligotrophic nonunion (poor reduction)
- A. Radiographic features – minimal callus formation
- B. Fracture healing has reduced healing response
- C.Treatment requires mechanical compression or bone grafting of defects
5.Pseudoarthrosis
- A. Fracture site has excessive motion resulting in formation of a pseudocapsule containing fluid
- B. Treatment requires stabilization and usually biological stimulus
What are the treatment options for non-union?
[Rockwood and Green 8th ed. 2015]
Nonoperative:
- Indirect intervention
- Smoking cessation
- Nutrition optimization
- Discontinue offending medications
- Optimize endocrine and metobolic disorders
- Direct intervention
- Weight bearing
- Cast or orthosis
- Electromagnetic stimulation
- Ultrasound stimulation (LIPUS – low intensity pulsed ultrasound) – better evidence
- Parathyroid hormone (PTH)
Operative:
- Plate and screw fixation
- Reamed exchange nailing
- Nail dynamization
- Circular ring external fixator
- Arthroplasty for periarticular nonunions in the elderly
- Amputation
- Arthrodesis
- Fragment excision in certain locations (eg. ulnar styloid, olecranon)
- Resection arthroplasty (eg. radial head nonunion, proximal pole of scaphoid)
What are the autograft options for nonunion treatment?
[J Orthop Trauma 2018;32:S52–S57)]
- ICBG (iliac crest bone graft)
* Yield = 30cc - RIA (reamer-irrigator-aspirator)
* Yield = up to 60cc
What is the management of an infected nonunion?
[J Orthop Trauma 2018;32:S7–S11)]
- Diagnosis -.WBC, ESR, CRP (most accurate predictor)
- Initial surgical stage
- A. Removal of all loose or chronically infected hardware
- B. Debridement of all infected or nonviable bone or soft tissue
- C. Minimum 3-5 deep tissue biopsies for culture and sensitivity
- D. Revision of fracture fixation
- Temporary fixation – ex-fix, casting, antibiotic nail
- Permanent fixation – plate fixation, IM nail, locked antibiotic nail
- E. Placement of local antibiotic
- Antibiotic nail, antibiotic impregnated osteoconductive pellets (eg. Osteoset T), antibiotic powder, antibiotic cement beads, antibiotic cement spacers (combined with induced membrane)
- Interim culture specific antibiotics and monitoring clinically and serologically for resolution of infection
- Second surgical stage
- Antibiotic nail, antibiotic impregnated osteoconductive pellets (eg. Osteoset T), antibiotic powder, antibiotic cement beads, antibiotic cement spacers (combined with induced membrane)
- A. Definitive fracture fixation (if temporary fixation was used)
- B. Reconstruction of the bone defect
What is the definition of critical bone defect?
[J Orthop Trauma 2018;32:S7–S11)]
- Defect that will not heal spontaneously despite surgical stabilization
- Requires surgical intervention
What is the difference between a nonunion and critical bone defect?
[J Orthop Trauma 2018;32:S7–S11)]
- Nonunion has impaired biology and/or inadequate stability
- Critical bone defect has adequate biology and stability but an inability to replace the substantial bone loss
What is the critical size for a bone defect?
[J Orthop Trauma 2018;32:S7–S11)]
Circumferential loss >50% or length >2cm
- Variable depending on:
- Location
- Soft tissue involvement
- Patient age
- Comorbidities
What are the surgical options to manage critical segmental bone defects and what size defects are the options amenable to?
[JAAOS 2015;23:143-153] [J Orthop Trauma 2018;32:S7–S11)]
- Induced membrane technique (Masquelet) >10cm (5-24)
- Distraction osteogenesis 5-10cm
- Acute limb shortening 1-3cm
- Vascularized fibula transfer 10-20cm
- Amputation
What are the 3 main benefits of the Masquelet technique?
[JAAOS 2015;23:143-153]
- “Priviledged compartment” limits autograft resorption
- Maintains the defect space for delayed bone grafting
- Induced membrane is rich in growth factors which improve graft consolidation
What is the function of the PMMA spacer in Masquelet Technique?
[J Orthop Trauma 2018;32:S7–S11)]
- Induces formation of biologically active pseudomembrane
- Maintains space for bone graft
- Delivers antibiotics
What is the function of the induced membrane in Masquelet Technique?
[J Orthop Trauma 2018;32:S7–S11)]
- Provides vascularization of bone graft
- Prevents graft resorption
- Provides growth factors which promote graft consolidation
Describe the Masquelet technique
[J Orthop Trauma 2018;32:S7–S11)]
Two stage procedure
- Stage 1
- Debridement of bone and soft tissue
- Stabilization with external or internal fixation
- Placement of PMMA spacer (with or without antibiotics)
- Stage 2
- 6-8 weeks later the membrane is incised
- The PMMA spacer is removed and the preserved defect is bone grafted
- Autograft is gold standard
- RIA +/- allograft or bone substitute (do not exceed 3:1 ratio of allograft to autograft)
- Autograft is gold standard
What are the two strategies for distraction osteogenesis?
[JAAOS 2015;23:143-153] [J Orthop Trauma 2018;32:S7–S11)]
- Acute or gradual shortening and compression at the defect site
* Followed by corticotomy and lengthening at a separate metaphyseal location - Bone transport
- Performed by applying a frame, making a corticotomy and transporting a segment across the defect at a rate of 1mm per day until it reaches the docking site and is compressed
- A secondary autografting at the docking site may be necessary if consolidation is incomplete
What is the main limiting factor in acute limb shortening?
Vessel kinking with shortening beyond 3-5cm
What is heterotopic ossification?
[JBJS 2015;97:1101-11]
Formation of ectopic lamellar bone in soft tissues