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Limb Lengthening w/ Ring Fixators



- Theoretical Considerations:
    - Discussion of Limb Lengthening:
    - Distraction Histiogenesis: (osteoclasis):
    - Ilizarov Menu

- Technique:
    - ring characteristics:
            - w/ the original Ilizarov technique, only two rings (each with drop wires) were used;
                  - soft tissue tension from the limb distraction provided additional corticotomy stability;
            - generally two rings will be inserted above the corticotomy and two rings are inserted below the corticomy;
    - wire insertion technique:
    - half pin insertion techniques:
    - bone transport:
            - use of oblique pulling wires decrease scarring of soft tissues;
            - transverse wires may be more useful for closing soft tissue defects;
            - bone may be transported over an IM nail which ensures proper direction of the transport and optimizes stability;
            - healing at the docking site may be facilitated by application of bone graft;
    - bone is lengthened at a rate of 1.0 to 1.5 mm per day.
    - gradual distraction allows the neurovascular bundle and muscles to lengthen safely;
    - note tethering effect of muscles:
            - lateral leg muscles tend to pull the distal fragment laterally, where as the posterior will tend to drag the distal fragment posteriorly;
            - to compensate, tilt the proximal ring in 5 deg of varus and in 5 deg of recurvatum;
    - tethering effect of skin:
           - when the fixator has been placed for limb lengthening, consider incising the skin in front of the path that the pin will take during the lengthening;
                 - make a larger incision for the pins closer to the osteotomy site;
                 - the incision will create a weak spot (even after the incision has healed) which will allow the half pins to cut through the skin 
                        without creating excessive skin tension;
    - osteotomy is performed at lower metaphyseal level for enhanced bone healing;
    - an insightful limb lengthening apparatus has been described by Brutscher, et al.
            - only two rings (or points of fixation are required), one at each end of the bone;
            - at one side of the bone a metaphyseal corticotomy (or osteotomy) is made;
            - 3.5 mm cortical screws are inserted on opposite sides of the bone segment which is nearer the diaphysis;
            - two modified screws which contain a 1 mm hole thru the head are inserted thru opposite sides of the bone segment closer to the metaphyseal side;
            - two 0.5 mm wire are attached to the paired 3.5 mm cortical screws and are then passed through the holes in the modified 3.5 mm screws, is passed out of the skin and is attached to a ratchet which is mounted on the external fixator;
                   - the rachets allow controlled lengthening of 1 mm per day;
            - advantages:
                   - this configuration allows an inexpensive fixator to be placed, with minimal need for transfixation wires;
    - references:
            Lengthening of the forearm by the Ilizarov technique.
            Limb lengthening in children using the Ilizarov method.
            Modern Techniques in Limb Lengthening--Symposium: Lengthening of the Forearm by the Ilizarov Technique.
            Problems, obstacles, and complications of limb lengthening by the Ilizarov technique.
            Force and stiffness changes during Ilizarov leg lengthening.
            Lengthening of the humerus using the Ilizarov technique. Description of the method and report of 43 cases.
            Local Bone Transportation for Treatment of Intercalary Defects by the Ilizarov Technique: Biomechanical and Clinical Considerations.  
            The tension-stress effect on the genesis and growth of tissues: Part II. The influence of the rate and frequency of distraction.
            The use of the Ilizarov technique in the correction of limb deformities associated with skeletal dysplasia.  
            Results of tibial lengthening with Ilizarov technique.  
            Cavitary osteomyelitis treated by fragmentary cortical bone transportation
            Temporal and spatial increases in blood flow during distraction osteogenesis
            Treatment of infected nonunions and segmental defects of the tibia by the method of Ilizarov
            Large experimental segmental bone defects treated by bone transportation with monolateral external fixators
            Biomechanical factors in the metaphyseal- and diaphyseal-lengthening osteotomy. An experimental and theoretic analysis in the ovine tibia.
            A review of 240 patients undergoing distraction osteogenesis for congenital post-traumatic or postinfective lower limb length discrepancy.        
            Treatment of large bone defects with the Ilizarov technique.

- Complications:
    - complications associated with bone transport docking:
            - delayed healing (managed with open debridement of bone end and with bone grafting);
    - soft tissue contractures:
            - knee flexion contractures are associated with large proximal to distal transport;
            - equinovarus contractures of the foot are associated with large distal to proximal transfers (in these patients consider prophylactic inclusion of the foot with the external fixation device)



The Role of Corticotomy and Osteotomy in the Treatment of Bone Defects Using the Ilizarov Technique.  

Complications of limb lengthening. A learning curve.

Factors affecting callus distraction in limb lengthening.

Mechanical evaluation of external fixators used in limb lengthening.

Current Techniques of Limb Lengthening.  

Limb Lengthening and Correction of Angulation Deformity: Immediate Correction by Using a Unilateral Fixator.

Technique: Metaphyseal distraction for lower limb lengthening and correction of axial deformities