6) Tarsal Coalition

Question 1

Tarsal coalition

Answer 1

• Condition in which 2 or more bones in midfoot or rearfoot are joined (complete/incomplete osseous coalition)
• Fibrous/Cartilaginous coalition
• Patients usually present in adolescence with recurrent sprains, pain in midfoot with spastic for fixed flatfoot

Question 2

Coalition proposed etiology (LeBouq)

Answer 2

• LeBouq’s theory of failure of differentiation of embryonic mesenchymal tissue
• Autosomal dominant inheritance
• First trimester insult

Question 3

Coalition proposed etiology (Pfitzner)

Answer 3

• Pfitzner theory of ossification of accessory bones into adjacent tarsal bones
• Disproved by Harris finding coalitions in fetus

Question 4

Acquired tarsal coalition etiologies

Answer 4

• Arthritis
• Infection
• Trauma
• Neoplasms

Question 5

Congenital tarsal coalition

Answer 5

• Accessory ossicle incorporation
• Genetic mutation to an autosomal gene, resulting in failure of differentiation and segmentation of primitive mesenchyme

Question 6

Coalition causes restriction or absence of

Answer 6

• Motion between two or more tarsal bones

- Can produce dramatic symptom complex, ultimately resulting in rigid peroneal spastic flatfoot

Question 7

Tarsal coalition incidence

Answer 7

• 0.04% (24 cases in 60,000 young military personnel)
• 0.9% (11 in 1,232 children clinic)
• 1.4% (28 in 2,000 army personnel)
• On average < 1% of the general population
• 50-80% Bilateral

Question 8

Tarsal coalition types/occurrence

Answer 8

• 90% Talocalcaneal (TC)
• Calcaneonavicular (CN)
• Talonavicular (3rd most common, <50 cases reported in literature)
• Calcaneocuboid
• Cubonavicular
• Naviculocuneiform

Question 9

Tarsal coalition associated abnormalities

Answer 9

• Symphalangism (hands and feet)
• Metatarsal fusions
• Vertebral fusions
• Sacroiliac fusions

Question 10

Tarsal coalition pathophysiology

Answer 10

• Normal STJ motion involves rotation and gliding

- During stance, STJ rotates from a position of 4 degrees external-valgus to 6 degrees of internal-varus

Question 11

When the internal rotation is restricted by coalition, the tarsal joints have to compensate with

Answer 11

• Flattening of the foot and loss of longitudinal arch
• Leads to an adaptive shortening of the peroneal tendons, reactive peroneal spasm, and so-called peroneal spastic flatfoot
• Prolonged restriction of motion eventually may lead to posterior facet arthrosis of the subtalar joint

Question 12

Subtalar joint gliding motion is lost during foot dorsiflexion.
Gliding motion replaced with hinge motion instead

Answer 12

• Widening at the plantar aspect of the midtarsal joints, narrowing at the dorsal surfaces, and overriding of the navicular on the talar head at maximum dorsiflexion
• Creating traction effect on the ligaments and capsule of the talonavicular joint resulting in talar beaking seen in many radiographs of tarsal coalitio

Question 13

Pain symptoms associated with tarsal coalitions

Answer 13

• May therefore be attributed to ligament sprain, peroneal muscle spasm, sinus tarsi irritation, subtalar joint irritation, and arthritic changes
• The variability of the symptoms in different patients may be due to the variability of subtalar restriction of the different coalitions

Question 14

Classification of tarsal coalition based on

Answer 14

• Etiology type
• Anatomic type
• Tissue type
• Articular involvement

Question 15

Tachdjian’s classification

Answer 15

• Descriptive classification that suggest the importance of assessing other areas of the foot and the remainder of the body

Question 16

Juvenile (osseous immaturity) articular classification system

Answer 16

- Type I - Extra-articular coalition
         A- No secondary arthritis
         B- Secondary arthritis
- Type II - Intra-articular coalition
         A- No secondary arthritis
         B- Secondary arthritis

Question 17

Adult (osseous maturity) articular classification system

Answer 17

- Type I - Extra-articular coalition
         A- No secondary arthritis
         B- Secondary arthritis
- Type II - Intra-articular coalition
          A- No secondary arthritis
          B- Secondary arthritis

Question 18

Types of coalitions (osseous vs. non)

Answer 18

• Synostosis - osseous union
• Synchondrosis - cartilaginous union
• Syndesmosis - fibrous union
• Combo

Question 19

Bars vs. bridges

Answer 19

• BARS = Extra-articular coalitions occur outside a normal joint
• BRIDGES = Intra-articular coalitions occurring at normal joint sites

Question 20

Ossification/sympotmatic presentation

Answer 20

• Talonavicular 3-5 y/o
• Calcaneonavicular 8-12 y/o
• Talocalcaneal 12-16 y/o
• Pain secondary to mechanical stress arising from periosteum

Question 21

Biomoechanical findings

Answer 21

• Middle facet talocalcaneal coalitions are associated with the greatest loss of subtalar motion and are the most likely to generate valgus

Question 22

Heel-tip test

Answer 22

• Examiner supinates the foot of a standing patient by raising the medial border of the forefoot and keeping the heel and lateral border in contact with the floor
• In patients with limited or decreased subtalar motion, compensatory external tibial rotation is decreased, and the patella is not observed to rotate outward as in a person without tarsal coalition

Question 23

Jack’s test

Answer 23

• Demonstrate the fixed nature of the pes planus and the loss of hindfoot inversion
• Also used for PTTD

Question 24

Clinical findings

Answer 24

• Incidental finding on routine radiographs
• Onset of pain insidious, developing after trauma or unusual activity
• Pain aggravated by activity and relieved with rest
• Limitation of motion (subtalar and midtarsal), and muscle spasm
• Recurrent ankle sprains
• Sinus tarsi syndrome

Question 25

Tonic muscle spasm (clinical finding)

Answer 25

- Rigid peroneal spastic flatfoot - Biomechanical “splinting” of STJ - Peroneus brevis attempting to restrict painful subtalar joint motion - subconscious effort - NO neurological pathology (clonic spasticity)

Question 26

Causes of peroneal spastic flatfoot

Answer 26

- Tarsal coalition - Arthropathies - Inflammation - Infection - Subchondral fractures

Question 27

Conservative treatment

Answer 27

- Restriction of subtalar and midtarsal joint motion - shoe modifications, orthoses, padding, casting - PT, NSAIDs, local steroid injections, prn

Question 28

Surgical treatment

Answer 28

- Resection or fusion

Question 29

Radiographic evaluation

Answer 29

- TALOCALCANEAL (middle facet) -LAT - ”C” Signs – formed from the medial talar dome and posteroinferior border of the sustentaculum tali - Bony bridge between the talar dome and sustentaculum tali, in combination with a prominent inferior border of the sustentaculum tali

Question 30

Halo sign

Answer 30

- Middle facet coalition demonstrating radiographic sclerosis of the subtalar joint and the ‘‘halo’’ effect of spherical diffusion of ankle and hindfoot forces

Question 31

Arthritic changes noted on radiographic evaluation

Answer 31

- Secondary arthritic or adaptive changes | - Functions of supination and pronation assumed by other joint, ie. Ball-and-socket ankle joint in talocalcaneal

Question 32

Cross-sectional imaging

Answer 32

- CT - MRI - Reserved for cases in which radiographs are inconclusive

Question 33

Talocalcaneal coalition

Answer 33

- Intra-articular coalitions traditionally considered indication for fusion - Juvenile IIA, if small enough or if incomplete, may consider resection arthroplasty - Wilde et al found that a valgus greater than 16º and a coalition surface area greater than 50% of the posterior facet on CT were predictors of poor results after resection - Future arthrodesis may be indicated

Question 34

Talocalcaenal coalition middle facet arthroplasty

Answer 34

- Linear incision from posterior-inferior medial malleolus to plantar-medial aspect of first cuneiform - Incision carried deeply between FDL tendon and NV bundle (Tib. Post. and FDL retracted dorsally and NV bundle retracted plantarly) - Middle facet coalition identified and resected (4-7mm) - Arthroereisis?

Question 35

Calcaneonavicular coalition radiographic evaluation

Answer 35

- CALCANEONAVICULAR - MO - “comma sign” - protrusion of calcaneus toward navicular - “anteater nose sign”

Question 36

Calcaneonavicular coalition characteristics

Answer 36

- Extra-articular coalition | - In younger pt. with minimal secondary arthritic changes, resection arthroplasty is procedure of choice - (Juvenile-IA)

Question 37

Calcaneonavicular coalition surgical treatment

Answer 37

- Lateral curvilinear or Ollier type of incision - EDB origin reflected off calcaneus, retracted distally - Must preserve the TN and CC joint ligaments - Bar is generously resected (1 to 1.5cm) - EDB muscle belly may be sutured into defect?

Question 38

Calcaneonavicular coalition post-op

Answer 38

- NWB, below the knee cast for 3-4 weeks - Cast may be bi-valved and subtalar and midtarsal joint ROM exercises begun - Begin WB after 4-6 weeks - Most freq. Post-op complication is recurrent bone growth - Must consider triple arthrodesis with failure or severe secondary arthritic changes

Question 39

Talonavicular coalition characteristics

Answer 39

- Intra-articular coalition - Frequently asymptomatic - If symptomatic, resection then fusion, as well as fusion of TC and CC joints recommended

Question 40

Calcaneocuboid coalition

Answer 40

- Rare, intra-articular coalition - Double arthrodesis of TN and TC joint may indicated - Extra-articular coalition - Similar to calcaneonavicular coalition