- See:
Tarsal Coalition:
- Discussion:
- talocalcaneal coalitions are characteristically on medial side of
sub-talar joint;
- coalition tends to ossify between 12 and 15 years;
- although coalition between calcaneus & talus may occur in any of three facets,
middle facet is most commonly involved;
- note that the anatomy of the middle &
anterior facet may vary among individuals;
-
four patterns are recognized;
- a single, small middle facet;
- a single middle facet that extends posteriorly and is almost as large as the
posterior facet;
- middle facet that extends anteriorly
- two facets - middle &
anterior facet- in medial compartment;
-
classification of coalition:
- type I: osseous bridging of the middle facet joint;
- type II: cartilagenous coalition;
- type III: fibrous coalition;
- shows only slight narrowing of the middle facet joint;
- the coalition is located posterior to the sustentaculum tali (and in most cases standard CT scan protocols do not image this area);
- these can be difficult to detect and may require bone scan to make the dx;
- Clinical Manifestations:
- talocalcaneal coalition generally becomes symptomatic in early teenage years when the preexisting cartilagenous coalition ossifies;
- patients often note repeated ankle sprains and may not be able to participate in sports;
- contraction and spasm of the peroneal muscles w/ forced inversion may be noted;
-
subtalar motion is reduced;
- in few pts w/ large middle facet,
tarsal tunnel syndrome develops from pressure on the median plantar nerve;
- large
middle facet may also prevent full plantar flexion of the ankle, since it abuts the posterior portion of ankle joint;
- in these patients, resection will not improve subtalar motion;
- Radiographic Features:
- CT Scan:
- can be used to make the diagnosis and can also be used to judge the relative size of the coalition;
- Non Operative Rx:
- conservative treatment is usually is usually effective in only 1/3 of patients with talocalcaneal coalition;
- use of below knee, wt bearing cast for 3-6 weeks may relieve symptoms;
- there after a plastizoate insert or an AFO is prescribed;
- symptoms often abate when facet ossifies completely, particularly if heel remains in a neutral position;
- Surgical Indications:
- results of talocalcaneal resections are less predictable than talonavicular;
-
excision
- resection is treatment of choice in patients under 16 years of age if no degenerative changes are present;
- the
middle facet coalition should be less than 50%;
- persistent hindfoot valgus may be assoc w/ poor result, & some recommend medial displacement os calcis osteotomy as an adjunctive procedure;
-
fusion:
- more than 50% involvement of middle facet or greater than 16 deg of valgus are relative contra-indication to resection;
-
subtalar fusion is indicated when coalition is > 50% of
middle facet or when degenerative changes
in the tarsal joints exist (talar beaking is not considered a degenerative change);
- failed resections are salvaged by
subtalar fusion or triple arthrodesis;
-
triple arthrodesis may be indicated when symptoms are severe and degenerative changes are present;
- Operative Treatment:
- incision starts medial to the talonavicular joint and extends to a point 1 cm distal to the medial malleolus;
- surgical approach for resection of talocalcaneal coalition is just anterior to the
FHL;
- flexor hallucis longus lies just plantar to sustentaculum tali, & tendon can be used for orientation to the coalition anomaly;
- FHL tendon sheath is incised, and the tendon is retracted inferiorly;
- the sustentaculum tali and its associated coalition are identified;
- once coalition is resected, interposition of one half of the FHL tendon will decrease the chance of recurrence;
Excision of symptomatic coalition of the middle facet of the talocalcaneal joint;
Treatment of symptomatic talocalcaneal coalition.
Resection for symptomatic talocalcaneal coalition.
Osseous and non-osseous coalition of the middle facet of the talocalcaneal joint.
Surgical Management of Symptomatic Talocalcaneal Coalitions by Resection of the Sustentaculum Tali.
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