BlueCross and BlueShield of Montana Medical Policy/Codes
Subtalar Arthroereisis (STA)
Chapter: Surgery: Procedures
Current Effective Date: February 01, 2014
Original Effective Date: April 18, 2013
Publish Date: January 15, 2014
Revised Dates: January 15, 2014

Arthroereisis (also referred to as arthrosis) is the limitation of excessive movement across a joint. Subtalar arthroereisis (STA) or extraosseous talotarsal stabilization (EOTTS) is designed to correct the excessive talar displacement and calcaneal eversion by placing an implant in the sinus tarsi, a canal located between the talus and the calcaneus.

Flexible flatfoot is a common disorder, anatomically described as excessive or abnormal pronation during weight bearing due to anterior and medial displacement of the talus. Flexible flatfoot may be congenital in nature, a result of cerebral palsy and other neuromuscular disorders, or may be acquired in adulthood due to posterior tibial tendon dysfunction, which in turn may be caused by trauma, overuse, and inflammatory disorders, among others. Symptoms include dull, aching and throbbing cramping pain, which in children may be described as growing pains. Conservative treatments include orthotics or shoe modifications. Additional symptoms include refusal to participate in athletics or walking long distances. Surgical approaches for painful flatfoot deformities include tendon transfers, osteotomy, and arthrodesis. Arthroereisis with a variety of implant designs has also been investigated.

STA has been performed for more than 50 years, with a variety of implants, designs, and compositions. The Maxwell-Brancheau Arthroereisis® (MBA) implant is the most frequently reported , although other devices such as the HyProCure®, STA-PEG® implant device and a Kalix® are also reported in the medical literature. The MBA implant is described as a reversible and easy to insert device with the additional advantage that it does not require bone cement. In children, insertion of the MBA implant is frequently offered as a stand-alone procedure, while adults often require adjunctive surgical procedures on bone and soft tissue to correct additional deformities.

Regulatory Status:

A number of implants have received marketing clearance through the U.S. Food and Drug Administration’s (FDA) 510(k) pathway. For example, the HyProCure® Subtalar Implant System/Extra Osseos Fixation Device (GraMedica) received marketing clearance in 2004 (K042030, the SubFix™ arthroereisis implant (Memometal Technologies, Bruz, France) received FDA marketing clearance in 2010 (K093820) and the Arthrex ProStop Plus™ (Arthrex, Naples, FL) received marketing clearance in 2008 (K071456). The MBA implant (now owned by Integra LifeSciences Corp., Plainsboro, NJ) received FDA 510(k) marketing clearance in 1996, because it was substantially equivalent to products on the market prior to device regulation. According to the FDA summary, the primary indication for the subtalar MBA device is “as a spacer for stabilization of the subtalar joint. It is designed to block the anterior and inferior displacement of the talus, thus allowing normal subtalar joint motion but blocking excessive pronation and the resulting sequela”. (1) The MBA Resorb Implant® received 510(k) marketing clearance in 2005 (K051611). This implant employs the same basic mechanical features as the predicate MBA implant, but is composed of a material (poly l-lactic acid) that is resorbed by the body. Predicate devices include the Osteomed Talar-Fit™ (K031155), Nexa Orthopedics Subtalar Peg (K032902 and K033046), Arthroereisis Implant Talus of Vilex (TOV, K041289), Instrateck (K080280), and Wright Medical Smith Sta-Peg (K792670).


Each benefit plan, summary plan description or contract defines which services are covered, which services are excluded, and which services are subject to dollar caps or other limitations, conditions or exclusions. Members and their providers have the responsibility for consulting the member's benefit plan, summary plan description or contract to determine if there are any exclusions or other benefit limitations applicable to this service or supply. If there is a discrepancy between a Medical Policy and a member's benefit plan, summary plan description or contract, the benefit plan, summary plan description or contract will govern.


Subtalar arthroereisis (STA) using a subtalar implant or extraosseous talotarsal stabilization (EOTTS) is considered experimental, investigational and unproven for all indications. 

NOTE:  This policy does not address subtalar arthrodesis. See the Pricing Section for more coding information.

Policy Guidelines

Since there is no specific CPT code for subtalar arthroereisis, the following codes may be used by providers, which has been cited by the American Podiatric Medical Association, February 2010 Coding Alert:

  • CPT code 28899: unlisted procedure for foot or toes,  OR
  • HCPCS code S2117: subtalar arthroereisis.

Subtalar arthroereisis should not be coded as 28725 (subtalar arthrodesis), which describes joint fusion. Other arthrodesis or arthroscopy codes that should not be used are:

  • 28585: (talotarsal joint dislocation, open treatment), OR
  • 28735: (midtarsal or tarsometatarsal treatment with flatfoot correction), OR
  • 28740: (single joint treatment of midtarsal or tarsometatarsal): OR
  • 29907: (subtalar joint arthroscopy, including arthrodesis).


A literature search of the MedLine database, focusing on subtalar arthroereisis (STA) generally and the Maxwell-Brancheau Arthroereisis (MBA®) implant specifically, identified minimal published studies, primarily consisting of single institution case series and individual case reports. The largest case series by Nelson and colleagues, in 2004, consisted of 37 patients (67 feet) who underwent the MBA implant with an average of 18.4 months of follow up. (2) While this study reported various improvements in anatomic measurements, there were no data on improvement in symptoms.

Children with cerebral palsy and other neuromuscular disorders are another population of patients with flat feet. Vedantam and colleagues reported, in 1998, on a case series of 78 children (140 feet) with neuromuscular disease who underwent STA with an STA-PEG®. (3) The stem of this implant is placed into the calcaneus with the collar abutting the inferior surface of the lateral aspect of the talus, thus limiting motion. All but five of the children had additional procedures to balance the foot. Satisfactory results were reported in 96.4% of patients, although the contribution of the STA-PEG cannot be isolated.

In summary, data in the published medical literature is inadequate to permit scientific conclusions. One limitation of the published data is the lack of long-term outcomes, particularly important since the procedure is often performed in growing children.

2007-2008 Update

A search of the MedLine database for the period of September 2005 through July 2007 found no evidence to prompt a change in the policy statement. Several retrospective case series were published. One of these reported in 2006, significant improvements in pain and function in 78% of patients (23 patients, 28 feet) with use of a subtalar implant as a component of reconstructive foot and ankle surgery. (4) However, since results were not compared with controls receiving reconstructive surgery without STA, the contribution of the implants to these outcomes is unclear. In addition, the authors reported an overall complication rate of 46% with surgical removal of 39% of the implants due to sinus tarsi pain. The authors also commented that postoperative sinus tarsi pain was unpredictable. No prospective controlled studies were identified.

Subtalar implants are not supported by evidence in the peer-reviewed medical literature that:

  • Permits conclusions on the effect of subtalar implant on long term outcomes,Demonstrates an improvement in net health outcome through use of subtalar implant,
  • Demonstrates that subtalar implant is as beneficial as established alternatives, and demonstrates that improvement attainable by subtalar implant is attainable outside investigational settings.

2010 Update

A search of peer reviewed literature through March 2010 identified several studies and reviews regarding STA procedures and implants.

In one radiographic study of bioabsorbable STA, found poor outcomes in 3 of 6 patients met the inclusion criteria and consented to additional imaging with an average follow-up of 14 months (range, 12–50 months). (5) Two patients requested implant removal; a third had persistent pain but refused explantation. Radiographic measurement using magnetic resonance imaging (MRI) or computed tomography (CT) found that these three patients had smaller tarsal canal widths than the diameter of the inserted interference screw. The authors noted that the implant length also had to be reduced prior to implantation. They concluded that the current width and length of commercially available implants may need to be modified, and that more research and long-term clinical study are needed.

Scher and colleagues described two cases of extensive implant reaction in two children two years after STA-PEG procedures and tendo-Achilles lengthening were performed for painful flatfeet. (6) The patients had minimal subtalar motion and pain at the sinus tarsi. Radiographs demonstrated surgical defects in the calcaneus. After failure of conservative management, implants were removed with good relief of pain. The authors do not recommend arthroereisis in the treatment of painful flexible flatfoot in children.

Three case series with small numbers of patients reported outcomes of a combination of surgical interventions, in which STA was one component; thus, the contribution of the arthroereisis is not clear. In a United States study, Adelman and colleagues reported on a retrospective analysis of ten patients. (7) The authors described this as a pilot study, and they reported on changes in seven radiographic measurements. In a study from Spain, Chicchinelli et al., also reported on radiographic outcomes in a retrospective analysis of 20 pediatric patients (28 feet) treated with STA combined with gastrocnemius (muscle) recession, or with STA combined with gastrocnemius recession and medial column reconstruction. (8) The authors reported that gastrocnemius recession had a notable effect on correction of transverse plane deformity when used as an adjunct to STA; however, medial column reconstruction had a negative impact on the degree of correction in the transverse plane when used as an adjunct to STA and gastrocnemius recession. In a European study, Lucaccini et al. analyzed clinical and radiographic results of 14 patients (16 feet) with hallux valgus in abnormal pronation syndrome treated with distal osteotomy of the first metatarsal bone and STA performed in one stage. (9) These case series do not allow comparison with nonsurgical interventions or with other surgical interventions.

Conclusion: Due to the lack of new published clinical trials showing that STA is as beneficial as established alternatives, this technology is still considered experimental, investigational and unproven.

2012 Update

Periodic literature searches of the MedLine database on STA have identified minimal published studies, primarily consisting of single institution case series and individual case reports. The most recent literature update, using the MedLine database, was performed for the period of 2010 through October 2012. Following is a summary of the key literature to date.

There are no controlled trials of subtalar arthroereisis compared to alternative treatments. The evidence base consists entirely of single-arm case series that report on success rates following this procedure. Interpretation of the current case series evidence is limited by the use of adjunctive procedures in addition to STA, creating difficulties in determining the extent to which each modality contributed to the outcomes. The evidence base is also limited by the lack of long-term follow-up, which may be particularly important for a procedure performed in children.

In 2011, Metcalfe et al. published a systematic review of the literature on STA for pediatric flexible flatfoot. (10) Seventy-six case series or case reports (no controlled trials) were identified. Ten of the studies (756 feet) provided clinician-based assessment of the surgical result graded from “excellent to poor” with follow-up between 36 and 240 months. Six studies (212 feet) included estimates of overall patient satisfaction using non-validated outcome measures, while 1 study (16 feet) found significant improvement using a validated foot-specific patient outcome measure. Data from 15 studies that reported radiographic values were combined for analysis. Although 8 of 9 radiographic parameters showed statistically significant improvements following arthroereisis procedures, the relationship between radiographic and clinical outcomes is uncertain. The procedure was associated with a number of complications including sinus tarsi pain, device extrusion, and undercorrection. Complication rates ranged from 4.8% to 18.6%, with unplanned removal rates between 7.1% and 19.3% across all device types. The influence of adjunctive procedures on outcomes was not addressed in this review.

One case series that was not confounded by adjunctive procedures and that had a relatively long follow-up was published by Graham et al. in 2012. (11) This study reported mean 51-month follow-up of talotarsal stabilization in 117 feet using the HyProCure device. Patients who received adjunctive procedures affecting the talotarsal joint were excluded from the analysis. Adult patients who met the inclusion/exclusion criteria were invited to participate in the study. Eighty-three patients gave consent to participate, and 78 completed the Maryland Foot Score Questionnaire; 5 patients who had 7 implants (6%) removed did not complete the questionnaire. There were 16 revision surgeries with HyProCure; 9 involved repositioning of a partially displaced device or a change in size of the device. Of the patients who retained the device, 52% reported complete alleviation of foot pain, 69% had no limitations on their foot functional abilities, and 80% of cases reported complete satisfaction with the appearance of their feet. This case series is notable for its assessment of functional outcomes at medium-term follow-up in patients who did not have adjunct procedures.

In a 2010 study, Scharer and colleagues conducted a retrospective radiographic evaluation of 39 patients (68 feet) who had received the MBA implant for the treatment of painful pediatric flatfoot deformities. (12) The average age of the patients at the time of surgery was 12 years (range: 6-16 years). Additional procedures included 12 (18%) gastrocnemius recessions, 6 (9%) Achilles tendon lengthening, and 4 (6%) Kidner procedures. At an average 24-month follow-up (range: 6-61 months), there had been 10 (15%) complications requiring reoperation, including implant migration, undercorrection, overcorrection, and persistent pain. The implants were exchanged for either a larger or smaller implant. These case series do not allow comparison with nonsurgical interventions or with other surgical interventions.

An example of a case series with longer follow-up is a 2012 retrospective study by Brancheau et al., which reported mean 36-month follow-up (range 18 to 48 months) in 35 patients (60 feet) after use of the MBA implant with adjunct procedures. (13) The mean age of the patients was 14.3 years (range, 5 to 46 years). Significant changes were observed in radiographic measures (talocalcaneal angle, calcaneocuboid angle, first to second intermetatarsal angle, calcaneal inclination angle, and talar declination angle). Seventeen percent of patients reported that 9 implants (15%) were removed after the initial surgery. Of the 24 patients (68.6%) who answered a subjective questionnaire (in person or by telephone at a mean of 33 months postoperatively), 95.8% reported resolution of the chief presenting complaint, and 79.2% said they were 100% satisfied with their surgical outcome. The contribution of the MBA implant to these results cannot be determined by this study design.

Cook et al. conducted a retrospective case-control study to identify factors that may contribute to failure (explantation) of titanium arthroereisis implants. (14) All patients who required removal of a self-locking wedge-type subtalar arthroereisis (n=22) were compared in a 1:2 ratio (n=44) to patients with non-explanted arthroereisis who were treated during the same time period. Subjects were matched for preoperative radiographic measurements, age, gender, presenting diagnosis, and length of follow-up. Multivariate logistic regression showed no significant effect of age, gender, implant size, shape, and length of follow-up, implant position, surgeon experience, or concomitant procedures. Patients who required explantation had slightly greater odds of radiographic undercorrection (odds ratio [OR]: 1.175) or residual transverse plane-dominant deformities (OR: 1.096). The percentage of explantations in this retrospective analysis was not described.

Practice Guidelines and Position Statements

2009 Guidance from the United Kingdom’s National Institute for Clinical Excellence (NICE) concluded that current evidence on the safety and efficacy of sinus tarsi implant insertion for mobile flatfoot is inadequate in quality and quantity. (15) Therefore this procedure should only be used with special arrangements for clinical governance, consent and audit, or research.

The American College of Foot and Ankle Surgeons (ACFAS) published practice guidelines for the diagnosis and treatment of adult and pediatric flatfoot in 2004 and 2005. (16, 17)

The ACFAS guideline on adult flatfoot states: “In the adult, arthroereisis is seldom implemented as an isolated procedure. Because of the long-term compensation and adaptation of the foot and adjunctive structures for flatfoot function, other ancillary procedures are usually used for appropriate stabilization. Long-term results of arthroereisis in the adult flexible flatfoot patient have not been established. Some surgeons advise against the subtalar arthroereisis procedure because of the risks associated with implantation of a foreign material, the potential need for further surgery to remove the implant, and the limited capacity of the implant to stabilize the medial column sag directly.”

The ACFAS guideline on pediatric flatfoot states: “proponents of this procedure (arthroereisis) argue that it is a minimally invasive technique that does not distort the normal anatomy of the foot. Others have expressed concern about placing a permanent foreign body into a mobile segment of a child’s foot. The indication for this procedure remains controversial in the surgical community.”


The evidence in the published medical literature on STA is inadequate to permit scientific conclusions. The main limitation is the lack of controlled studies comparing use of the implants with other surgical procedures, alone or in combination. Other limitations of the published data is the lack of long-term outcomes, particularly important since the procedure is often performed in growing children, and the difficulty in separating the effect of this procedure from that of other adjunctive treatments. Therefore, STA is considered experimental, investigational and unproven.


Disclaimer for coding information on Medical Policies

Procedure and diagnosis codes on Medical Policy documents are included only as a general reference tool for each policy. They may not be all-inclusive.

The presence or absence of procedure, service, supply, device or diagnosis codes in a Medical Policy document has no relevance for determination of benefit coverage for members or reimbursement for providers. Only the written coverage position in a medical policy should be used for such determinations.

Benefit coverage determinations based on written Medical Policy coverage positions must include review of the member’s benefit contract or Summary Plan Description (SPD) for defined coverage vs. non-coverage, benefit exclusions, and benefit limitations such as dollar or duration caps.  

ICD-9 Codes
81.18, 81.99, 716.17, 734, 754.61
ICD-10 Codes
M21.40-M21.42, 0SUH0JZ, 0SUJ0JZ, 0SUH3JZ, 0SUJ3JZ, 0SUH4JZ, 0SUJ4JZ
Procedural Codes: 28899, 0335T, S2117
  1. U. S. Food and Drug Administration. Summary for Kinetikos Medical Incorporated (KMI) Subtalar MBA System™. Available at (accessed - 2005 August 12, last accessed 2012 July).
  2. Nelson, S.C., and D.M. Haycock. Flexible flatfoot treatment with arthroereisis: radiographic improvement and child health survey analysis. Journal of Foot and Ankle Surgery (2004) 43(3):144-55.
  3. Vedantam, R., and A.M. Capelli. Subtalar arthroereisis for the correction of planovalgus foot in children with neuromuscular disorders. Journal of Pediatric Orthopaedics (1998) 18(3):294-8.
  4. Needleman, R.L. A surgical approach for flexible flatfeet in adults including a subtalar arthroereisis with the MBA sinus tarsi implant. Foot and Ankle International (2006) 27(1):9-18.
  5. Saxena, A., and A. Nguyen. Preliminary radiographic findings and sizing implications on patients undergoing bioabsorbable subtalar arthroereisis. Journal of Foot and Ankle Surgery (2007 May-June) 46(3):175-80.
  6. Scher, D.M., Bansal, M., et al. Extensive implant reaction in failed subtalar joint arthroereisis: report of two cases. HSS Journal – The Musculoskeletal Journal for Hospital for Special Surgery (2007 September) 3(2):177-81.
  7. Adelman, V.R., Szczepanski, J.A., et al. Radiographic evaluation of endoscopic gastrocnemius recession, subtalar joint arthroereisis, and flexor tendon transfer for surgical correction of stage II posterior tibial tendon dysfunction: a pilot study. Journal of Foot and Ankle Surgery (2008 September-October) 47(5):400-8.
  8. Cicchinelli, L.D., Pascual Huerta, J., et al. Analysis of gastrocnemius recession and medial column procedures as adjuncts in arthroereisis for the correction of pediatric pes planovalgus: a radiographic retrospective study. Journal of Foot and Ankle Surgery (2008 September-October) 47(5):385-91.
  9. Lucaccini, C., Zambianchi, N., et al. Distal osteotomy of the first metatarsal bone in association with sub-talar arthroereisis, for hallux valgus correction in abnormal pronation syndrome. Chirurgia Degli Organi Di Movimento (2008 December) 92(3):145-8.
  10. Metcalfe SA, Bowling FL, Reeves ND. Subtalar joint arthroereisis in the management of pediatric flexible flatfoot: a critical review of the literature. Foot Ankle Int 2011; 32(12):1127-39.
  11. Graham ME, Jawrani NT, Chikka A. Extraosseous talotarsal stabilization using HyProCure® in adults: a 5-year retrospective follow-up. J Foot Ankle Surg 2012; 51(1):23-9.
  12. Scharer BM, Black BE, Sockrider N. Treatment of painful pediatric flatfoot with Maxwell-Brancheau subtalar arthroereisis implant a retrospective radiographic review. Foot Ankle Spec 2010; 3(2):67-72.
  13. Brancheau SP, Walker KM, Northcutt DR. An analysis of outcomes after use of the Maxwell-Brancheau Arthroereisis implant. J Foot Ankle Surg 2012; 51(1):3-8.
  14. Cook EA, Cook JJ, Basile P. Identifying risk factors in subtalar arthroereisis explantation: a propensity-matched analysis. J Foot Ankle Surg 2011; 50(4):395-401.
  15. National Institute for Clinical Excellence (NICE). Sinus Tarsi Implant Insertion for Mobile Flatfoot: Interventional Procedure Guidance 305 (2009). Available at (accessed 2012 July).
  16. Harris EJ, Vanore JV, Thomas JL et al. Clinical Practice Guideline Pediatric Flatfoot Panel: American College of Foot and Ankle Surgeons (ACFAS). Diagnosis and treatment of pediatric flatfoot. J Foot Ankle Surg 2004; 43(6):341-73.
  17. Lee MS, Vanore JV, Thomas JL et al. Clinical Practice Guideline Adult Flatfoot Panel: American College of Foot and Ankle Surgeons (ACFAS). Diagnosis and treatment of adult flatfoot. J Foot Ankle Surg 2005; 44(2):78-113.
  18. Subtalar Arthroereisis. Chicago, Illinois: Blue Cross Blue Shield Association Medical Policy Manual. (2012 September) Surgery 7.01.104.
January 2013  New 2013 BCBSMT medical policy.  considered investigational.
February 2014 CPT/HCPCS code(s) updated.
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Subtalar Arthroereisis (STA)