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Wheeless' Textbook of Orthopaedics

Polydactyly of Foot         



- Discussion:
    - polydactyly in the foot usually involes a single duplication (hexadactyly)
    - associated anomalies:
          - duplications occur bilaterally in about 40-50% of patients, but often the duplications are not symmetric;
          - polydactyly of hand occurs in about 1/3 of patients;
          - syndactyly of the toes occurs in about 1/5 patients;
          - Down's syndrome will be present in a minority of cases;
    - often is autosomal dominant w/ incomplete penetrance: (only about 30% of patients will have a positive family history);
    - incidence:
          - occurs in about 1 to 2 out of 1000 live births;
          - whites: occurs in 0.3 to 1.3 out of 1,000 births;
          - blacks: occurs in about 4 of 1,000 births;
          - occurs slightly more often in males;
    - in older patients, the main complaint is diffulty with shoe wear;

- Treatment of Polydactyly Subtypes:
    - the general surgical goal is to excise the toe which provides the toe with the most normal contour, inorder to facilitate shoe wear;
           - usually this involves excision of the most medial or the most lateral toe,  depending on whether the deformity is pre or post axial;
    - surgical timing: most authors recommend surgery after 1 year (to reduce anesthetic risks but prior to walking age, if possible;
           - this allows the greatest potential for remodeling;
           - often patients will be refered in at age 4-5 years because of difficulty w/ shoe wear;
    - post-axial polydacyly:
           - accounts for about 80% of foot polydacyly cases;
           - phalangeal duplication w/ block metatarsal or wide metatarsal head is the most common pattern;
                  - following in frequency are the "Y" shaped metatarsal, "T" shaped metatarsal, and finally the metatarsal duplication (complete or 
                          partial);
           - over 90% of patients should have a good to excellent surgical result;
           - surgical resection involves excision of the lateral toe in the majority of cases;
                  - if the metatarsal head is prominent, it should be trimmed flush to the metatarsal shaft (at right angles to the physis);
                        - leaving the metatarsal head prominent may cause a painful postop bunion;
                        - transecting at right angles to the physis does not cause growth deformity;
                        - the metatarsal bowing which results from excision of a "Y" metatarsal will usually remodel over several years;
                        - the joint capsule should be carefully repaired;
                  - if the inner toe is significantly hyplastic, then it should be excised instead, inorder to preserve the contour of the forefoot;
                        - as with central duplications, it is important to reapproximate the intermetarsal ligament;
           - post operative complications:
                  - the lateral digit often shows a valgus deformity at the MTP joint, but this is usually asymptomatic and does not interfere w/ shoeware;
                  - bowing of the lateral metatarsal shaft is common, but this may resolve w/ subsequent remodeling;
           - misc:
                  - floppy digit:
                        - it has become a standard practice to suture ligate supranumerary digits which are attached only by soft tissue in the hopital nursery;
                               - suture ligature of supranumerary digits w/ reidual cartilage and/or an underlying duplicated metatarsal will lead to future deformity;
                        - radiographs should always be taken to ensure that there are no underlying deformed metatarsals, in which case the
                               supra-numerary digit should be surgically excised at one year;

    - central duplication:
           - accounts for about 3-6% of foot polydacyly cases;
           - these most often occur as hypoplastic metatarsal ray duplications;
           - patients often have a widened forefoot (splayed) which is often cannot be corrected w/
                   surgical removal of the duplicated digits;
                  - this results from laxity of the intermetatarsal ligament;
           - surgery involves removing the central ray duplications w/ a racket incision at the base of the 
                  duplication;
                  - the toe is excised, and the intermetatarsal ligament is reapproximated;
                  - post operative casting may help keep the forefoot from splaying while the intermetatarsal ligament heals;
                  - note that gaps left between toes often will not narrow w/ time;
    - pre-axial polydactyly
           - accounts for about 15-17% of foot polydacyly cases;
           - msot common pattern is phalangeal duplication w/ block metatarsal;
           - note that short short "block shaped" metatarsals are most associated w/ hallux varus deformity which is associated w/ pain and 
                  difficulty w/ shoe wear;
                  - often patients w/ short metatarsals w/ have transfer metatarsalgia;
                  - these block metatarsals will alway remain abnormal;
           - excision of medial toe:
                  - disarticulation of the duplicated hallux is followed by careful reattachment of the abductor and adductor hallucis;
                        - in some cases, the abductor will have to be lengthed before reattachment;
                        - the adductor can be inserted into the great MTP capsule;
                  - pin fixation can be used to hold the phalanx in an anatomic position, inorder to avoid a postoperative hallux varus deformity;
                  - if the metatarsal head is prominent, it should be trimmed flush to the metatarsal shaft (at right angles to the physis);
                        - leaving the metatarsal head prominent may cause a painful postop bunion;
                        - transecting at right angles to the physis does not cause growth deformity;
                        - the metatarsal bowing which results from excision of a "Y" metatarsal will usually remodel over several years;
                        - the joint capsule should be carefully repaired;
           - postoperative complications:
                  - often patients are dis-satisfied following surgery because of a progressive hallux varus deformity;
                  - any amount of varus is considered abnormal, and the patient's symptoms often correlate w/ the degree of varus;
                         - patient's often note difficulty w/ shoe wear and pain;
                         - if hallux varus deformity is present, then consider an AFO which is molded to prevent forefoot varus;
           - modified farmer's procedure:
                  - indicated for a duplicated but hypoplastic second toe;
                  - involves removal of the second toe;
                  - a rectangular rotational skin flap is made in the web space;
                  - starting at the proximal aspect of the medial skin flap incision, an additional incision is made across the medial aspect of the great 
                         toe MPT joint;
                  - the great toe is then lateralized and is partially syndactylize to the third toe (note that the 2nd toe has been removed);
                         - complete syndactyly may pull the lesser toes into varus;
                  - reinsert the adductor hallucis, inorder to avoid hallux varus deformity;
                  - the rectangular skin flap is then rotated medially to cover the defect created by rotation of the great toe;
           - case examples:
                 
                 

- Anatomical of Polydactyly:
    - phalangeal duplication w/
           - block metatarsal or wide metatarsal head;
           - normal metatarsal;
           - "Y" shaped metatarsal;
           - "T" shaped metatarsal;
           - metatarsal duplication (complete or partial)



Polydactyly of the foot.

Polydactyly and Polysyndactyly of the Fifth Toe.

Treatment of Preaxial polydactyly of the Foot.

Congenital hallux varus.

Problems in polydactyly of the foot.



Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Thursday, May 24, 2012 12:54 pm