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Mitchell Bunion Procedure

- Discussion:
    - this a distal "Step Cut" metatarsal osteotomy that displaces metatarsal head laterally in order to correct hallux valgus deformity and 
          metatasus adductus;
    - Mitchell procedure is carried out more proximally than Chevron osteotomy, & can correct more severe deformities than Chevron;
    - this procedure is applicable to moderate to severe deformities of intermetatarsal angle and hallux valgus;

- Surgical Technique:
    - dorsomedial incision is carried down to the joint capsule;
    - dorsal and plantar skin flap is created, with care being taken to avoid the cutaneous nerves;
    - distally based flap is then created from the medial joint capsule in order to expose medial eminence;
          - medial eminence is removed in line with the medial aspect of the metatarsal shaft;
    - transverse osteotomy:
          - is performed through metatarsal neck, just proximal to level of sesamoids, however, lateral 3 mm of metatarsal cortex is left uncut;
          - lateral cortex is then cut proximal to first cut;
          - this cut creates a step off in the distal fragment;
          - distal fragment is then displaced laterally by width of step off and is placed into a slight degree of plantar flexion to accommodate 
                for the degree of shortening that has been created by removing the section of bone;
    - greater the deformity the larger the need for more lateral displacement;
    - osteotomy site is then secured, either with a suture or a pin;
    - medial joint capsule is plicated in order to align MP joint;
- Complications:
    - controlling the osteotomy site in the Mitchell procedure may be difficult and dorsal displacement may occur;
    - avascular necrosis of the metatarsal head may occur if excessive stripping of tissue has been carried out;
    - shortening of 1st metatarsal & transfer metatarsalgia to second metatarsal.
         - this is compensated for by plantar flexion of distal fragment at time of surgery

Mitchell's osteotomy using internal fixation and early mobilisation.
The risks and benefits of distal first metatarsal osteotomies.
The Mitchell Procedure for the Treatment of Adolescent Hallux Valgus. A Long-Term Study.