CurrentAetnaPolicy 0669

Subtalar Implant for Foot Deformity

This policy governs Aetna's coverage stance for subtalar implants (arthroereisis) used to treat foot deformities (e.g., flatfoot, talotarsal instability) and applies to providers submitting claims to Aetna.

Policy Summary

PayerAetna

PolicySubtalar Implant for Foot Deformity

Policy CodePolicy 0669

Change TypeNo material changes

Effective DateAug 22, 2003

Next Review DateJul 25, 2024

Key ActionObtain and document prior authorization with clear clinical justification including failed conservative therapy, specific indication, planned implant type and adjunct procedures.

SourceLink

POLICY UPDATE CHANGES

No material clinical or coverage changes in this revision.

30+Named devices

5 codesDiscussed codes

13%Sinus tarsi pain

29%Removal rate (example)

0-33%Removal/pain range

Coverage Determination and Rationale

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Experimental/Investigational — general stance

Covered when ALL of the following are met

Policy stance: Aetna considers subtalar implants experimental and investigational because effectiveness has not been established for the listed indications and devices.

Policy declares subtalar implants experimental and investigational

Coverage considerations

Evidence-based considerations and use-contexts described in the cited studies:

General considerations: Surgical subtalar arthroereisis is considered for symptomatic flexible or acquired flatfoot refractory to conservative management; patient selection should be individualized based on symptoms, radiographic deformity, and counseling about risks and uncertain long‑term benefit.documentation of failed conservative therapy

Derived from multiple cohort and systematic review summaries

Expected outcomes: Studies report improvements in patient‑reported outcome scores (e.g., AOFAS, VAS, MFS) and radiographic angles (talar‑1st metatarsal, calcaneal pitch, talonavicular coverage) at short- to mid-term follow-up.short- to mid-term follow-up reported

See prospective and retrospective series (e.g., Junxian, Bistolfi, pooled review)

Risks and device issues: Reported device-related complications include sinus tarsi pain and implant removal; reported incidence varies by implant and series (e.g., 13% sinus tarsi pain with Talar‑Fit; implant removal rates up to ~29% in some reports), and implant position/size influence pain risk.variable complication/removal rates reported

See chunk 33 and comparative series

Evidence quality: Available evidence is largely retrospective, heterogeneous, and predominantly level IV; systematic reviews pool low-level studies and long‑term, high‑quality comparative data are limited, which constrains conclusions about effectiveness.predominantly level IV evidence

See systematic review and study-level evidence summaries

Evidence-based coverage considerations

Coverage considerations based on cited literature and reported indications

Pediatric symptomatic flexible flatfoot: Studies report subtalar arthroereisis may improve radiographic and clinical parameters in children with symptomatic flexible flatfoot refractory to conservative management; however evidence is low-quality (level IV) and longer-term data on definitive bony correction are limited.failed conservative care documented; evidence level IV; follow-up variable

Systematic review and pediatric cohorts summarized concerns about study quality and heterogeneity

Adult-acquired flatfoot (stage IIb AAFD): Retrospective cohort data indicate STA used as an adjunct to reconstruction (e.g., medializing calcaneal osteotomy, FDL transfer, spring‑ligament repair, ± Cotton osteotomy) can improve radiographic correction of forefoot abduction, but some series report high STA‑related complication/removal rates (up to ~33%) and careful documentation of planned adjunct procedures and informed consent regarding implant-related pain/removal is advised.document planned adjunct procedures and informed consent regarding risk of pain/removal

See Bernasconi, Junxian, and related cohort studies

Use of any of the subtalar implants listed in this policy (examples include Angled Subtalar Implant (ASI), Arthrex ProStop/ProStop Plus, HyProCure, Maxwell‑Brancheau (MBA) implant, Kalix II, OsteoMed Talar‑Fit, Solana Gaitway, Trilliant Twist, and many others) is addressed explicitly. The policy identifies these named devices as examples of implants considered when evaluating procedures for talotarsal stabilization or subtalar arthroereisis and cites them as part of the devices for which effectiveness has not been established.

The policy states an explicit exclusionary stance: subtalar implants for the indications listed are considered experimental and investigational because effectiveness has not been established, and procedures using these devices are therefore subject to noncoverage decisions. The exclusions section lists treatment of subtalar instability, talipes equinovarus, foot drop, congenital and acquired flatfoot (including posterior tibial tendon dysfunction), and other conditions as examples of indications considered investigational when treated with these implants.

Biomechanical modeling of posterior tibial tendon dysfunction indicates that subtalar joint arthroereisis (STA) may not restore normal mid‑foot load transfer and, in some simulations, increased stress was observed in metatarsal and mid‑foot joints. The policy cites this work to caution that STA alone may be biomechanically insufficient as a salvage for PTTD and that adjunctive measures (for example, orthotic interventions or additional procedures) may be necessary.

Overall, the policy considers subtalar implants experimental and investigational for the listed indications due to insufficient evidence of effectiveness. Systematic review and cohort evidence is mostly low quality (predominantly level IV), heterogeneous, and limited in long‑term bony correction data; therefore, the policy summarizes these procedures as investigational pending more robust comparative or randomized data.

For pediatric flexible flatfoot, the policy emphasizes that many cases are asymptomatic and that surgery is generally reserved for children with symptomatic flexible flatfoot refractory to conservative management. Available studies report radiographic and clinical improvements in selected symptomatic pediatric cohorts, but the evidence is low quality and long‑term outcomes remain incompletely characterized; thus surgical arthroereisis should be considered only after documented failure of conservative therapy and with appropriate counseling about limited evidence and potential need for implant removal.

Use of subtalar implants in indications or populations lacking adequate evidence (for example, non‑refractory deformities, unselected patient groups, or indications for which high‑quality comparative data are absent) may be considered investigational or not medically necessary. The policy highlights the low level and heterogeneity of available studies and notes that coverage decisions may require additional clinical justification when evidence is limited.

Prior Authorization, Documentation, and Billing Guidance

Prior Authorization

Prior Authorization Required — clinical justification

Prior authorization is required. Requests must include a clinical justification that documents the indication for subtalar implant and why nonoperative management is not appropriate for this patient.

Prior authorization should specify the exact indication (e.g., symptomatic flexible or acquired flatfoot, stage of deformity) and any adjunct procedures planned (for example, medializing calcaneal osteotomy, tendon transfer, Cotton osteotomy).
Include prior conservative therapy documentation (see documentation callout) and relevant imaging/measurements.
If prior authorization is not obtained or clinical justification is insufficient, the service may be denied.

Denial Risk

Denial Risk for Listed Devices

Subtalar implants listed in the policy are considered experimental and investigational; claims for these devices are at high risk of denial.

Devices listed as investigational (examples include, but are not limited to: HyProCure, Arthrex ProStop/ProStop Plus, BioArch, Kalix, Maxwell‑Brancheau MBA, SubFix, Talar‑Fit, Solana Gaitway, Trilliant Twist) are subject to denial.
HCPCS code S2117 (arthroereisis, subtalar) and CPT 0335T (extra‑osseous subtalar joint implant for talotarsal stabilization) are identified in the policy and may be denied when used for investigational indications.

Denial Risk

Denial Risk Triggers

Denial risk is increased when evidence shows high implant removal or complication rates, lack of long‑term high‑quality evidence, or when study limitations reduce confidence in effectiveness.

High explantation/removal rates reported in the literature (examples: 22% removal after adult acquired flatfoot procedures; reported removal rates up to 29% for some implants) are a trigger for denial review.
Lack of randomized controlled trials, predominance of retrospective cohort and case‑series designs (many level IV studies), small sample sizes, and inconsistent or short follow‑up increase the likelihood of additional review or denial.
Inadequate reporting of pre‑operative neutral radiographs, inconsistent radiographic/functional outcome measures, or missing patient‑reported outcomes may result in denial or request for further documentation.

Denial Risk

Low‑quality evidence may trigger further review

Because many published studies are retrospective, small, or of low methodological quality, cases with limited or low‑quality supporting evidence may prompt additional medical review.

Policies note that low level evidence (predominantly level III–IV, retrospective case series) may lead to requests for supplemental data or denial.
If submitted studies lack validated patient‑reported outcomes, standardized radiographic measures, or sufficient follow‑up, provide additional justification or request peer review.

Billing Rule

Coding Documentation — CPT/HCPCS/ICD‑10

Coding related to subtalar implants must be documented and billed using the appropriate codes; note that some codes are specifically identified as not covered for indications in this policy.

CPT 0335T — Extra‑osseous subtalar joint implant for talotarsal stabilization (listed in policy).
CPT 0510T, 0511T — Removal and removal/reinsertion of sinus tarsi implant (listed).
CPT 28735; 29907 — Other related procedures that may be billed when applicable (arthrodesis, arthroscopy with arthrodesis).
HCPCS S2117 — Arthroereisis, subtalar (listed as not covered for indications in the policy).
ICD‑10 diagnosis codes called out as not covered for indications in the policy include examples such as: E64.3; M21.071‑M21.079; M21.371‑M21.379; M21.6x1‑M21.6x9; M21.40‑M21.42; M21.541‑M21.549; M24.871‑M24.876; M25.271‑M25.279; M25.371‑M25.376; Q66.0; Q66.50‑Q66.52; Q66.6; Q66.80‑Q66.89.

Documentation Required

Required Clinical Documentation

Provide complete clinical documentation demonstrating a history of symptoms, prior conservative management, and objective outcome measures.

History and physical exam notes describing symptoms, functional limitations, and duration of symptoms.
Documentation of failed conservative therapy (see conservative therapy callout) including type, timeframe, and response.
Patient‑reported outcomes (for example: VAS pain scores, AOFAS, Maryland Foot Score, SF‑36) with pre‑ and post‑treatment values when available.
Operative indications, planned adjunct procedures, and informed consent discussing risks including potential implant removal.

Documentation Required

Required Clinical and Radiographic Documentation — operative details and follow‑up

Include pre‑ and post‑operative radiographs and measurements, detailed operative reports, and follow‑up documentation showing outcomes and any complications or implant removals.

Pre‑operative imaging including lateral radiographs in talotarsal joint neutral position when possible.
Radiographic measurements: Meary's angle (talar‑1st metatarsal), talonavicular coverage angle (TNCA), talocalcaneal angles, calcaneal pitch, AP T2MT angle, and other angles reported in the literature.
Post‑operative radiographs with the same measurements and comparative change from baseline.
Operative report documenting implant type, size, implant position (e.g., relation of tail end to lateral calcaneal wall), and any concurrent procedures (MCO, FDL transfer, spring ligament repair, Cotton osteotomy).
Follow‑up notes documenting recovery, patient‑reported outcomes, complications (including sinus tarsi pain), and any implant removals and reasons for removal.

Note

Conservative Therapy Context

Conservative therapy should be attempted and documented prior to considering subtalar implant procedures.

Conservative treatments may include orthotics, physical therapy and stretching exercises, activity modification, NSAIDs or other medications, and consideration of corticosteroid injections where appropriate.
Document duration and modalities used and patient's response; state why conservative care was insufficient to manage symptoms.
If adjunct surgical procedures are planned, document rationale for combining with a subtalar implant.

Documentation Required

Prior Conservative Therapy — documentation that nonoperative options were tried/failed

Prior conservative therapy must be documented showing nonoperative options were tried and failed before authorization or coverage is considered.

Specify types of nonoperative care attempted (orthotics/arch supports, PT, stretching, NSAIDs, activity modification) and dates/duration of each therapy.
Include documentation of inadequate symptom relief or intolerance to conservative care.
If no trial of conservative therapy occurred, provide clinical rationale (for example, acute or severe pathology where conservative care is contraindicated) to support the request.

Procedure and Device Definitions

Subtalar arthroereisis — definition of the procedure

DefinitionSurgical procedure placing an implant (typically a threaded cylinder) into the sinus tarsi between the talus and calcaneus to stabilize the subtalar joint and limit excessive pronation.

Primary purposeProvide indirect medial column support and block anterior/inferior displacement of the talus to restore the medial longitudinal arch.

Patient populationsPerformed in children and adults for congenital and adult-onset flatfoot (pes planus, pes planovalgus, pes valgus) and related talotarsal instability.

Technique notesImplant is inserted into the sinus tarsi and may act as an ‘internal orthotic’; some surgeons use bone blocks or endoprosthetic devices to limit pronation.

MBA implant — device definition / description

Device nameMaxwell-Brancheau Arthroereisis (MBA) implant — an internal orthotic cleared by FDA via 510(k).

Material and designSoft-threaded titanium device available in five diameters (6, 8, 9, 10, 12 mm) inserted into the sinus tarsi.

Indications describedDesigned for correction of pediatric pes valgus and adult posterior tibial dysfunction deformity; may be used with ancillary procedures in adults.

Postoperative careAmbulation day after surgery in a Cam Walker for ~3 weeks, then regular shoes with an ankle brace for an additional 2–3 weeks.

Sinus tarsi pain — definition and relevance

DefinitionLocalized postoperative pain in the sinus tarsi region commonly associated with subtalar arthroereisis and frequently prompting implant removal.

Association with implant positionRisk of sinus tarsi pain correlates with implant position (e.g., longer distance from implant tail end to lateral calcaneal wall increases odds of pain).

Reported incidenceIncidence reported in studies (e.g., Talar‑Fit series) around 13%; some series report higher rates and pain often resolves after implant removal.

Flexible flatfoot (FFF) / Acquired flatfoot (AAFD) — definition

DefinitionDeformity characterized by collapse of the medial longitudinal arch with forefoot abduction (flexible flatfoot) that may be symptomatic and impair quality of life.

Indication for surgerySurgical arthroereisis is considered when noninvasive options (orthotics, stretching, NSAIDs) fail to provide sufficient pain relief and functional improvement.

PopulationsCommon in pediatric patients; can be acquired in adults (AAFD) often related to posterior tibial tendon dysfunction and staged presentations (e.g., stage IIb).

Subtalar arthroereisis (STA) — alternate definition / details

Alternate descriptionInsertion of an implant into the sinus tarsi or subtalar region to limit excessive pronation and provide indirect medial column support, either alone or as an adjunct to reconstructive procedures.

Adjunct usesOften used with medializing calcaneal osteotomy (MCO), flexor digitorum longus (FDL) transfer, spring ligament repair, or Cotton osteotomy in adult AAFD.

Clinical outcomesStudies report improvements in radiographic angles and patient‑reported scores at short- to mid-term follow-up, but evidence is heterogeneous and largely level IV.

Flexible (pediatric) flatfoot / adult-acquired flatfoot deformity (AAFD) — definition

DefinitionCollapsible medial longitudinal arch deformity that can be symptomatic and refractory to conservative treatment; in adults this presents as AAFD and may be staged (e.g., stage IIb).

Conservative careInitial management includes orthotics, stretching, NSAIDs, and occasionally injections; surgery is reserved for symptomatic, refractory cases.

Special considerationsBiomechanical analyses suggest STA may not fully restore mid-foot load transfer in PTTD and may require adjunctive procedures or orthotic intervention.

E64.3	Sequela of rickets.
M21.071 - M21.079	Other acquired deformities of ankle and foot [foot drop].
M21.371 - M21.379	Other acquired deformities of ankle and foot [foot drop].
M21.6x1 - M21.6x9	Other acquired deformities of ankle and foot [foot drop].
M21.40 - M21.42	Flat foot [pes planus] (acquired).
M21.541 - M21.549	Acquired clubfoot.
M24.871 - M24.876	Other joint derangement/instability involving ankle and foot [subtalar instability].
M25.271 - M25.279	Other joint derangement/instability involving ankle and foot [subtalar instability].
M25.371 - M25.376	Other joint derangement/instability involving ankle and foot [subtalar instability].
Q66.0	Congenital talipes equinovarus.

OpenPayer

Subtalar Implant for Foot Deformity

Coverage Determination and Rationale

Procedure and Diagnosis Codes

Prior Authorization, Documentation, and Billing Guidance

Clinical Context and Scope

Procedure and Device Definitions

0335T	Extra-osseous subtalar joint implant for talotarsal stabilization.
0510T	Removal of sinus tarsi implant.
0511T	Removal and re-insertion of sinus tarsi implant.
28735	Arthrodesis, midtarsal or tarsometatarsal, multiple or transverse; with osteotomy (e.g., flatfoot correction).
29907	Arthroscopy, subtalar joint, surgical; with subtalar arthrodesis.