Tarsal Coalition

1. Tarsal Coalition Derek Butterwick August 13th, 2012 CHEO Monday Rounds

2. Definition • Abnormal union between tarsal bones • Calcaneonavicular – MOST COMMON • Talocalcaneal – 2nd Most COMMON • Middle Facet - most commonly involved • Others - RARE • Talonavicular • Calcanocuboid • Cubitonavicular • Naviculocuneiform • Etiology – lack of differentiation of mesenchymal tissue

3. Definition Calcaneonavicular Talocalcaneal Commonly involves the middle facet Medial, above sustentaculum tali • Btwn anterior process of the calcaneus & most lateral aspect of navicular

4. Definition • Types of Coalitions: • Synostosis – bony bar • Synchondrosis – cartilaginous bar • Syndesmosis – fibrous coalition

5. Classification – Many

6. Stats • 1% of the population • Bilateral – about 50% • higher if calaneonavicular coalition (60%) • Autosomal Dominant Inheritance • High level of penetrance

7. Effect of Coalition of Foot Biomechanics • Restricts subtalar motion • Talocalcaneal > Calcaneonavicular • Recall Gait Talk: • Heel strike – Foot begins to unlock • Goes from rigid to flexible foot • Midstance – Foot unlocked • Flexible foot – accommodates uneven ground • Heel-off – Foot locks • Rigid foot – acts as lever arm to allow propulsion

8. Effect of Coalition • Locking and Unlocking – occurs at subtalar joint • Subtalar Pronation (Eversion) - causes the TTJ axes to become more parallel. (i.e. unlocked) • Subtalar Supination (Inversion) - causes the TTJ axes to become non-parallel (i.e. locked) Coalition - foot constantly Locked, constantly rigid

9. Effect of Coalition • So How does a Coalition make the Foot Flat? • Rigid Hindfoot – Persistently locked • Other joints must allow more motion • E.g. Talonavicular, Calcaneal Cuboid, and others • Result – Flattening of the Foot

10. - Painful, Rigid, Flatfoot - Usually present with cosmetic concerns - Usually asymptomatic, flexible, flatfoot

11. Coalition Presentation • Generally – presents when coalition begins to ossify • Calcaneonavicular – age 9-13 • Subtalar – middle or late adolescence • *Both Present earlier* – if obese, highly active patient • C/O • Flatfoot Appearance – usually parents concern • Progressive loss of arch height • hindfoot pain with activity, uneven ground • At site of coalition, sinus tarsi, tip of fibula • Symptoms precipitated by a “sprain” – that doesn’t get better

12. Physical Exam • Pes Planus • Hindfoot valgus • Midfoot abduction • Forefoot pronation • Medial Talar Head - prominent • Loss of Medial longitudinal arch height

13. Pediatric Flatfoot – ?Rigid or ?Flexible Weight Bearing - Flat medial arch Hindfoot Valgus Hindfoot Varus Non-weight bearing - Medial arch reforms Flexible Flatfoot

14. Coalition Physical Exam • Presents w/ “Peroneal Spastic Flatfoot Syndrome” • With Toe Raise – Hindfoot remains in Valgus, Medial longitudinal arch remains flat • Stiff Subtalar Joint • Maneuver – hindfoot cupped with one hand, midfoot and head of talus grasped with other, rock hindfoot into inversion/eversion • Findings: • Little ROM – use contralateral side as gauge (recall: bilateral rate) • Pain with Inversion • Sinus tarsi laterally • Posterolateral Calf – from peroneal spasm (Rarely pain here)

15. X-Rays • Standard Foot Films • *Weight Bearing* • AP • Lateral • 45 degree oblique • Harris Heel view

16. Calcaneonavicular Coalition • “Ant Eater Sign” • On lateral – long anterior process of calcaneus • Best view to see coalition • 45 degree oblique film • Synchondrosis – irregular joint surface • Synostosis – complete bar • *Change angle of beam to see perfect gap* • Talar beaking – traction on capsule • Broadening of lateral process of the talus

17. Subtalar Coalition • Difficult to see with plain films • C-Sign • Outline of talar dome, and posteroinferior outline of the sustentaculum tali

18. Subtalar Coalition • Harris view • Difficult to interpret!!! • Middle facet • Location - medial and just above sustentaculum tali • Joint surface irregular, facets angle down and medial • If > 20 degrees – coalition is probable • *If you suspect subtalar coalition (i.e. stiff painful hindfoot) & equivocal X-ray findings CT for diagnosis Abnormal a.k.a. “Drunken Waiter Sign” Normal

19. Cross sectional Imaging • CT – the Study of Choice • Calcaneonavicular coalition – not really needed • r/o double coalition – RARE (although Kontio does for all) • Use sagittal cuts • Subtalar Coalition • CT for ALL • Determine location (anterior, middle, posterior facet) • Use coronal cuts

20. W/U Negative for Coalition?? • Obtain MRI – • r/o fibrous coalitions or non-ossified coalitions, look for other causes of pain • Still Negative W/U • Dx = PERONEAL SPASTIC FLATFOOT

21. Peroneal Spastic Flatfoot • Diagnosis of exclusion • Foot painful from some underlying cause, get rigid flatfoot deformity – from spasm of extrinsic foot muscles • Body trying to prevent foot from moving • Underlying Causes: • Juvenile Rheumatoid Arthritis - Most Common • Others • Osteochondral fractures hindfoot, osteoid osteoma, neoplasms, Trevor’s Dz, idiopathic

22. Peroneal Spastic Flatfoot • w/u – find underlying cause • CBC, ESR, CRP • Treatment – TREAT THE CAUSE • Supportive Treatment – activity modifications, NSAIDS • Generally – inject subtalar joint w/ corticosteroid using fluoro • Refer to Rheumatology for w/u

23. Coalition Treatment • A-symptomatic – No Treatment • Symptomatic • Medial Heal Wedge (correct hindfoot valgus) ...or... • Weight Bearing SLC x 2-4 wks • If successful try UCBL Orthosis (University of California Biomechanical Lab) • rigid plastic orthotic used to correct hindfoot

24. Operative Treatment • In General: • Resection of coalition – with soft tissue interposition to prevent recurrence • If – failed non-operative treatment, adjacent joints not too arthritic (mild changes only) • Primary Goal – relieve pain • Secondary Goal – restore joint motion • *won’t restore arch height* • The younger the patient, higher of the chance of regaining motion

25. Calcaneonavicular Resection • Wide Resection of Coalition with interposition of soft tissue (EDB or fat graft) • Interposition required – high rate of recurrence without • Results – 80% good pain relief

26. Calcaneonavicular Resection • Oblique incision – anterolateral foot • Between extensor tendons and peroneals • Find EDB, reflect it distally • Clear out sinus tarsi • Localize coalition – use X-ray • Resection coalition – 1 cm block • Use osteotomes, often need to take more than you think • Interposition – Fat or EDB • EDB – tag with sutures, use Keith's needles to pass them out the plantar foot, tie over a felt button • SLC x 3 weeks NWB then mobilize

27. Calcaneonavicular Resection Example

28. Talocalcaneal Coalition Treatment **Usually** – resect any coalition...Poor results if > 50% facet involved, adjacent joint Degeneration

29. Surgical Technique • Supine – allow leg to ER • Incision – medial hind foot over sustentaculum • from anterior Achilles navicular • Incise flexor retinaculum • Find Abductor Hallicus – retract inferior • Find PT tendon • Find FDL tendon – just posterior • Find NV bundle – just posterior • FHL is deep to this – slings under sustentaculum • Coalition Location • Just above sustentaculm, deep to FDL tendon

30. Surgical Technique • Find coalition – work from known to unknown • Find anterior facet (deep to neck), find posterior facet (retract NV posteriorly) • Use Burr – find stripe of cartilage at coalition, keep working along until normal cartilage found • Pre-op plan based on cross sectional imaging • Create 1 cm opening • Check subtalar motion • Insert fat graft and bone wax • Donor site – retrocalcanel fat • Post-op - BKC, NWB x 3 weeks, then mobilize

31. Fusions?? • Subtalar Fusions, Triple Arthrodesis, etc • Indication: • Failed coalition resections, advanced degenerative changes at surrounding joints (CC, TN, etc), young adult > 16 yrs, Subtalar Coalitions > 50% joint involved • Result – pain relief, but risk of adjacent joint degeneration