Subtalar Arthritis

 

Aetiology

  • Post-traumatic arthritis (~67%)
    • Intra-articular talar fracture
    • Intra-articular calcaneal fracture
    • Subtalar dislocation
  • Primary osteoarthritis (~25%)
  • Acquired conditions
    • Adult acquired planovalgus deformity
    • Postpolio syndrome
  • Chronic instability secondary to ligamentous injury (CFL, deltoid)
  • Congenital conditions
    • Talocalcanal coalition
    • Neuromuscular disorders e.g. cerebral palsy
  • Chronic hindfoot malalignment (cavovarus/ planovalgus)
  • Inflammatory arthropathy
    • Rheumatoid arthritis
  • Anatomical variations of the sustentaculum tali
    • Long continuous facets and medial only facets have a higher risk of arthritis than separate anterior and medial facets (2)

May be associated with arthritis involving the neighbouring talonavicular and calcaneocuboid joints.

 

Classification

  • Stage 1 - Presence of osteophytes without joint-space narrowing
  • Stage 2 - Joint-space narrowing with or without osteophytes
  • Stage 3 - Subtotal or total disappearance or deformation of joint space

 

​Clinical Presentation

  • Posterior/ lateral foot pain, worse on weightbearing especially on uneven ground
  • May be associated with swelling
  • Tend to prefer shoes with an ankle support
  • History of trauma

 

Assessment

Clinical examination

Look:

  • Antalgic gait
  • Overall coronal lower limb alignment
  • Hindfoot alignment
    • varus/ valgus
    • stiff or flexible / correctable
    • Coleman block test to assess if hindfoot varus is forefoot or hindfoot driven
  • Any associated deformities – cavovarus/ planovalgus
  • Scars from previous surgeries

Feel:

  • Tenderness over sinus tarsi
  • Swelling

Move:

  • Subtalar ROM (cup the heel in one hand while stabilizing the talus with the other hand and assess movement and whether it elicits pain)
  • Assess ankle, TNJ and CCJs
  • Assess calf complex for tightness (Silfverskiöld test)

 

Imaging

  • Radiographs
    • Weight-bearing anteroposterior and lateral views of the ankle
    • Broden’s view: foot is internally rotated by 45° with X-ray angled 10-40° cephalad: views the posterior subtalar facet
    • Canale view: AP view of foot in 15° of pronation with X-ray aimed 75° from horizontal: views the sinus tarsi
    • Harris axial heel views
  • CT – weight-bearing if available – to assess for talocalcaneal coalition
  • MRI – helpful to determine the severity of OA, to detect subtle arthritic changes and to assess for adjacent joint arthritis

 

Non-operative management

Always offer as first line of management

  • Analgesia
  • Orthotics: primarily to address hindfoot malalignment e.g. medial or lateral post to correct hindfoot varus/valgus – only if deformity is flexible
  • Braces: restricts painful joint motion, accommodates rigid deformity)
  • Lifestyle/activity modification: avoiding uneven ground, weight loss
  • Physiotherapy (useful in chronic subtalar instability) for proprioception exercises and peroneal muscle strengthening
  • Injections: steroid or hyaluronic acid: diagnostic and/or therapeutic

 

Operative management: Subtalar joint arthrodesis

Goals:

  1. Pain relief: bony union reduces shear forces within the joint
  2. Restoration of hindfoot alignment: reduces intra-articular peak forces
  3. Restoration of stability
  4. Provides a stable, plantigrade foot to allow weightbearing
  5. Improving long-term function

Position of fusion is vital due to the role of the subtalar joint in foot and gait biomechanics: 5-10° of valgus (3)

Important to address any adjacent joint pathology e.g. double/triple fusion or ankle replacement / TTC fusion.

 

Open STJ Arthrodesis

Indications:

  • Any of the above-mentioned causes of STJ OA
  • Preferred if there is associated hindfoot deformity or malalignment which needs to be addressed, revision fusion, bone loss needing grafting, malunited calcaneal fracture needing bone block distraction arthrodesis

Contra-Indications:

  • Poor soft tissue envelope
  • Poor wound healing potential

Procedure is performed using a sinus tarsi approach, an incision from the tip of the fibula to the base of the 4thmetatarsal.

Extended lateral calcaneal incision if removing previous metalwork (e.g. calcaneal fracture fixation)

 

Arthroscopic STJ Arthrodesis

Indications:

  • Same as for open arthrodesis
  • Poor soft tissue envelope
  • Poor wound healing potential
  • Previous open surgery in area of interest

Contra-Indications:

  • Severe hindfoot deformity or malalignment
  • Revision surgery
  • Large bone loss requiring bone graft

Advantages of arthroscopic arthrodesis:

  • Smaller incisions therefore less damage to soft tissue envelope
  • Theoretically preserves the calcaneal and talar blood supply
  • Less perioperative morbidity

Portals: lateral and/or posterior

Lateral portals

  • Patient positioned supine or lateral
  • Central, anterolateral, posterolateral portals are most commonly used but accessory anterolateral and accessory posterolateral portals are also described
  • 90% of the posterior facet can be resected using the central and anterolateral portals (4)
  • Structures at risk: sural nerve and short saphenous vein injury with the posterolateral portal

Posterior portals

  • Patient positioned prone
  • Posteromedial and posterolateral portals (on either side of the Achilles tendon)
  • Provides better visualization of the coronal alignment of the subtalar joint
  • Avoids damage to the sinus tarsi vessels
  • Structures at risk:
    • posterolateral portal: peroneal tendons and sural nerve
    • posteromedial portal: posterior tibial neurovascular bundle and medial calcaneal nerve (1)

Fixation methods:

  • Single or double screw fixation
    • Biomechanical studies show that double diverging screws provide the highest compression, greatest torsional stiffness and least rotation
    • Placement of the screw tip into the talar neck or lateral talar dome should be avoided in single screw fixation (5)
  • Staples
    • Fusion rate is similar to screw fixation, but functional outcomes are better with screw fixation (6)

 

Complications

  • Infection
  • Non-union (smokers, alcoholics, diabetics, prior ankle fusion, revision fusion) (7)
  • Mal-union
  • Neurovascular injury
  • Complex regional pain syndrome
  • Adjacent joint arthritis
  • Hardware prominence
  • Failure requiring revision / secondary procedures

 

Outcomes (8,9)

  • Both open and arthroscopic STJ arthrodesis result in significant improvement in pain relief and return to function, have similar union rates (~90%) and complication rates
  • Arthroscopic subtalar fusion has a shorter time to union, faster recovery and faster return to work

 

References

  1. Roster, B., Kreulen, C., & Giza, E. (2015). Subtalar Joint Arthrodesis. Foot and Ankle Clinics, 20(2), 319–334. doi:10.1016/j.fcl.2015.02.003
  2. Drayer-Verhagen F. Arthritis of the subtalar joint associated with sustentaculum tali facet configuration. J Anat. 1993 Dec;183 ( Pt 3)(Pt 3):631-4. PMID: 8300440; PMCID: PMC1259889
  3. Jastifer JR, Gustafson PA, Gorman RR. Subtalar arthrodesis alignment: the effect on ankle biomechanics. Foot Ankle Int. 2013 Feb;34(2):244-50. doi: 10.1177/1071100712464214. Epub 2013 Jan 10. PMID: 23413065
  4. Lintz F et al. Safety and efficiency of a 2-portal lateral approach to arthroscopic subtalar arthrodesis: a cadaveric study. Arthroscopy. 2013 Jul;29(7):1217-23. doi: 10.1016/j.arthro.2013.04.016. PMID: 23809457
  5. Chuckpaiwong B, Easley ME, Glisson RR. Screw placement in subtalar arthrodesis: a biomechanical study. Foot Ankle Int. 2009 Feb;30(2):133-41. doi: 10.3113/FAI-2009-0133. PMID: 19254508
  6. Barg A, Herrera-Pérez M. Response to "Letter Regarding: Comparison of Cannulated Screws Versus Compression Staples for Subtalar Arthrodesis Fixation". Foot Ankle Int. 2015 Oct;36(10):1254. doi: 10.1177/1071100715606897. PMID: 26429901
  7. Ziegler P, Friederichs J, Hungerer S. Fusion of the subtalar joint for post-traumatic arthrosis: a study of functional outcomes and non-unions. Int Orthop. 2017 Jul;41(7):1387-1393. doi: 10.1007/s00264-017-3493-3. Epub 2017 May 8. PMID: 28484796
  8. Rungprai C et al. Outcomes and Complications After Open Versus Posterior Arthroscopic Subtalar Arthrodesis in 121 Patients. J Bone Joint Surg Am. 2016 Apr 20;98(8):636-46. doi: 10.2106/JBJS.15.00702. PMID: 27098322
  9. Rungprai C et al. Outcomes and Complications of Open vs Posterior Arthroscopic Subtalar Arthrodesis: A Prospective Randomized Controlled Multicenter Study. Foot Ankle Int. 2021 Nov;42(11):1371-1383. doi: 10.1177/10711007211047239. Epub 2021 Sep 28. PMID: 34581196