External tibia fixation Return to basics
Dr. Patrick HERARD
Bone callus formation Periosteal, cortical, medullary and fracture hematoma will participate in different ways •Periosteal: • • •
callus bridging bone defects builds quickly BUT requires integrity of soft surrounding tissues stimulated by micro-movements in fracture site (inhibited by stabilization) duration 6 weeks
•Cortical: ‘Per primam’ consolidation may occur if close bony contact is respected. Inhibited by mobility. (AO principles). •Medullary: Infiltration of cells between cortical fragments starting at 6 weeks inhibited by mobility. •Fracture haematoma: mitogenic immunostimulating substances are liberated during the first 2 days. BMP, TGF,…
Only open fractures are treated with Exfix (MSF protocol) Periosteum is badly damaged A good debridement necessitates proper curettage of medullary cavity Fracture hematoma no longer exists
Conclusion : STABILITY is the major factor. Fixations should be rigid.
Stability factors
Pin insertion and positioning
Frame configuration
How to make rigid assembly ?
Charge
Distance os //frame portedistance fiche Bone 3
F = 1/3
P x L E x I
MobilitĂŠ Fracture site mobility du foyer Young module Material
I = 0,05 x d 4 PinDiamètre diameterfiche
Distance Bone – Fixation
Basic physics: 1. Increase of d decreases stability 2. Increase of D increases stability 3. More pins, more stability
Pin positioning
Minimum distance: 3 cm from fracture in undamaged tissue
Pin Insertion • Make skin insertion in the direction in which the skin will move during mobilisation • Make sure there is no skin tension around the pin • Use pin insertion guide or pin clamp for correct distance and angles
Pin Insertion • Don’t hammer on pin or drill bit: Can cause micro fractures leading to pin loosening or complete fractures of the bone • To start off, drill in reverse for 1-2 turns • First pin inserted should be the most difficult and closest to fracture site
Pin Insertion • Travel longest distance possible through the bone • Bi-cortical hold • Avoid soft tissue damage • Consider patient comfort and possible flap coverage
Pin Insertion Pay attention to where pins are placed – Joints – Fracture – Soft tissues • Peroneal nerve • Don’t transfix muscles
Standard fixation Antero-medial
If assembly unstable 2 planes between 60 and 90째
External fixator The only fixation device available in most fields Efficient: neutralization, compression, distraction Associated advantages (bone grafts, flaps,‌) Patient comfort and mobility BUT
Follow-up is compulsory: Medical: pin care Mechanical: loosening of pins or frame Radiological
Pin infections
Pin infection • Initial daily dressing • Rest if inflammation present • Inflammation and oozing: X-ray, rest, ATB • Inflammation, oozing and mobile: removal
Thank You