Tarsal coalition

Classification according to ICD-10
Q66.8	Other congenital deformities of the feet
ICD-10 online (WHO version 2019)

A tarsal coalition is a solid bridge between two or more bones of the hindfoot and metatarsus , which can be formed by connective tissue (fibrous), cartilaginous, or bony, where a flexible joint is normally created. A bony tarsal coalition is also known as a synostosis . A tarsal coalition can occur in isolation, then mostly only two bones are connected, or in a multiple coalition several bones are involved, which is more likely to be observed in the context of a malformation syndrome . There is an association with the spherical talus . The exact etiology is unknown; it is assumed that the mesoderm does not differentiate . Multiple forms are closely related to other extremity differentiation disorders. Exogenous risk factors have not yet been described.

Isolated shapes

The most common form of the tarsal coalition, the calcaneonavicular coalition in the oblique X-ray image of the foot (left, arrows) with two comparatively inconspicuous feet. The coalition is not bony, but connective tissue or cartilaginous.

The isolated forms can be an incidental finding, so they never become symptomatic. An older study on soldiers showed an unknown tarsal coalition in 1% without any complaints. The constant restriction of movement is often not noticed.

But usually stress-related pain in the rear and midfoot occur during growth on, often with a Knicksenkfußstellung and occasionally with a painful spasm of the peroneal muscles on the outer ankle side. There is seldom a full expression of a rigid, massive arched foot.

In the case of a symptomatic tarsal coalition, therapy consists of surgical resection, with or without interposition of adipose tissue. There are recurrences described in up to 10%, but the results of resection are usually good.

The different forms often become symptomatic at a different time:

• Kalkaneo-navikuläre coalition (53%) between the calcaneus and navicular often the first symptoms at the age of 8 to 12 years. Significant restriction of movement in the lower ankle joint, often with a rigid arched arched foot.
• Talokalkaneare coalition (37%) between ankle bone and heel bone. Symptoms usually only appear in adolescence or later. Also with a rigid arched arched foot and significantly restricted mobility of the lower ankle.
• Talonavicular coalition between ankle bone and scaphoid bone, sometimes symptomatic from the age of three. Usually the inside of the foot protrudes clearly, often without causing discomfort. The longitudinal vault is often preserved in this form.
• Calcaneocuboidal coalition (rare) between the calcaneus and cuboid bone
• Navikulokuneiform coalition (rare) between a scaphoid and a sphenoid bone

Multiple forms

These are often part of a syndrome with other disorders of differentiation of the extremities, such as:

• Dysmelias and longitudinal malformations
• Fibular hemimelia : In a study examining the resected tissue after amputation, 54% found a talocalcaneal coalition.
• Proximal Femoral Defect (PFFD)
• Apert syndrome
• Carpal coalition , i.e. the fixed connection between the carpal bones
• Spherical talus
• Symphalangia
• Oro-facio-digital syndrome type 10

Diagnosis

The rigidity of the hindfoot, that is, the lack of mobility in parts of the ankle, is groundbreaking for the suspected diagnosis. A coalition is not always recognizable on a standard X-ray, since the oblique and complex subtalar joint and the Chopart joint cannot be easily assessed on it. In the case of a talocalcanic coalition, there may be an overlay of the talus and calcaneus ("C sign") as well as a bone spur anterior to the neck of the talus. Special exposures are often required, such as 45 ° inclined x-rays of the rear foot or those in the "Harris View". An exact representation of the bony change is possible in thin-slice CT , while connective tissue bridges can be better detected in MRI .

therapy

Treatment usually depends on the underlying disease. If the tarsal coalition goes beyond a simple fusion of two bones, a reconstruction is usually not possible, so that more complex procedures are used to correct the deformity. The goal is a proper position of the back and midfoot without pain, whereby a movement restriction remains until stiffening.

literature

• F. Hefti: Children's orthopedics in practice. Springer-Verlag, Berlin 1998, ISBN 3-540-61480-X , Chapter 3.4.5.2 "Tarsale Coalition". P. 410 ff.

Web links

Commons : Tarsale Coalition  - Collection of images, videos and audio files

Individual evidence

1. ↑ F. Hefti: Pediatric Orthopedics in Practice. Springer 1998, ISBN 3-540-61480-X , p. 415
2. ^ WH Vaughan, G. Segal: Tarsal coalition with special reference to roentgenographic interpretation. In: Radiology. 1953; 60, pp. 855-864.
3. ^ DM Stormont, HA Peterson: The relative incidence of tarsal coalition. In: Clin. Orthop. Rel. Res. 1993; 181, pp. 28-36.
4. ↑ wheelesonline

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