Tarsal Coalition



Congenital fibrous, cartilaginous or bony connection of 2 or more tarsal bones

- due to failure of segmentation


Peroneal Spastic Flat Foot

- tarsal coalition

- tarsal pain

- reduced STJ motion

- rigid pes planus

- peroneal muscle spasm / tightness




Present in 6% of population

- symptomatic in 1% of population


Bilateral in 50%


20% multiple coalitions


AD with variable penetrance


Calcaneo-Navicular most common (2/3)

- talocalcaneal middle facet is next most common (1/3)

- rest uncommon




Symphalangism (congenital end to end fusion of phalanges)


Fibula hemimelia

Other gross limb anomalies




Secondary to failure of differentiation & segmentation of mesenchyme

- supported by intertarsal bridges in fetal tissue




Multiple coalitions may occur

- do 2 plane CT with fine cuts to look for other coalitions

- will get poor results if not addressed


May develop ball and socket ankle joint

- due to stiffness of STJ

- develop inversion / eversion in AKJ


Valgus deformity leads to adaptive shortening of peroneal tendons

- may cause reflex spasm of tendon




1. Location

- CN / TC / TN / CC


2. Ossification

- synostosis - completely ossified

- synchondrosis - partly cartilaginous

- syndesmosis - fibrous




Majority are asymptomatic & remain so in adulthood


If symptomatic, symptoms usually develop in adolescence when bar ossifies

- due to reduction in STJ movement & joint stress


Calcaneonavicular coalition

- 8 - 12 years of age


Talocalcaneal coalition

- 12 - 16 years of age




Present with

- recurrent ankle sprains

- pain over sinus tarsi or over sustentaculum tarsi

- vague aching pain aggravated by activity




Stiff STJ 

- especially talocalcaneal bar

- may still have movement if not ossified


Fixed Pes Planus 

- doesn't correct on heel raise or Jack's Test

- heel doesn't swing into varus

- valgus heel with talocalcaneal bar


Peroneal tendons may be shortened but rarely spastic






Oblique xray

- often diagnoses CN bar

- Anteater sign - elongated process on calcaneus or prolongation of navicular 




1.  Talar Beaking

- very suggestive of TC bar

- traction spur due to increased stress


Talar Beaking


2.  C sign

- seen on lateral xray

- continuous C shaped line

- from talus to sustenaculum tali


3.  Ball and socket ankle joint

- secondary to TC bar


4.  Harris axial view

- visualise talocalcaneal

- 40° axial view shows middle facet 

- ski jump view




May be helpful for cartilaginous or fibrous bar



CT scan


Very good for bony bars




Any condition that injures STJ

- traumatic / osteochondral fracture

- inflammatory / RA

- tumour / osteoid osteoma

- infection


Flexible flat foot








Avoid aggravating activities

Moulded longitudinal arch support

SL FWB cast for 6/52







Persistent pain

Minimal degenerative changes




Resection of bar

Isolated STJ fusion - degeneration of STJ only

Triple Arthrodesis - rigid planovalgus foot


Criteria for Resection


All relative

- young < 14 years

- absence of complete bony bar

- no degenerative changes 

- presence of talar beaking is not a contraindication

- no fixed deformity


Calcaneonavicular bar resection


NHx compared with talo-calcaneal bar

- possibly settle down long term

- better prognosis / less arthritis / present younger

- more likely amenable to resection

- most do well




Aim is 1 cm gap


Ollier approach

- 1cm distal to fibular tip

- obliquely across sinus tarsi

- to superolateral margin TNJ


Superficial Dissection

- protect superficial CPN

- EDL & P tertius anteriorly / peroneals plantarward


Deep dissection

- elevate EDB proximal to distal  

- beware of its motor branch from DPN

- show sinus tarsi / anterior process calcaneum

- expose bar

- may need to open TN and CC joints to know exact location



- resect 1cm of bone with osteotomes

- protect talus and STJ from damage

- check with on table oblique lateral II

- suture fat / EDB into defect / over button and felt pad


Post op

- 2 weeks POP

- moon boot / WBAT /ROM

- button out at 6/52




Gonzalez et al JBJS Am 1990

- 75 feet in 48 patients

- good or excellent results in 77%

- poor in 7%

- best results with cartilaginous coalition and patients < 16


Mubarak et al J Pediatr Orthop 2009

- CN resection and fat graft interposition

- 5% incidence of symptomatic regrowth requiring repeat resection

- 74% had improvement of subtalar joint motion

- 82% improvement of plantarflexion

- felt fat graft better choice than EDB as can completely fill gap


Talocalcaneal Bar




1/3 develop arthritis

- operative results not as successful as CN

- resection more difficult

- results less predictable

- tend to be more conservative with this than CN bar 





- < 16 years

- < 50% surface area of posterior facet 

- nil arthritic changes

- < 16o valgus



- > 50% of post facet 

- i.e. middle facet bar is > 50% of posterior facet

- heel valgus > 16°

- narrowing of STJ i.e. arthritic changes

- lateral talar process impinging on calcaneum





- is best option if failed non-operative

- always worth trying prior to arthrodesis

- try to return some STJ motion


Calcaneal Osteotomy

- re-centres heel

- realigns weight bearing

- not everyone uses it



- in mature foot > 12 years


Resection Technique 



- curved incision

- navicular tuberosity to medial border T Achilles

- 2cm superior to superior calcaneal tuberosity


Superficial dissection

- through flexor retinacular sheath 

- elevate T Post and FDL tendon anteriorly

- neurovascular bundle and FHL retracted plantarward

- identify posterior facet



- resection of bone until middle facet seen + mobile

- remove more bone from talus than sustentacular side 

- 2/3 of resection from talus

- key to operation is anterior process of calcaneus & follow posterior

- fat graft or silicon insertion


Post operative

- early ROM important




Very rare

- ossifies at 3-5 years

- therefore symptoms early