|Policy #:||SURG.00104||Current Effective Date:||07/09/2013|
|Status:||Reviewed||Last Review Date:||05/09/2013|
This document addresses the use of subtalar arthroereisis, a surgical procedure typically performed to correct excessive talar displacement and calcaneal eversion due to pes planus (flatfoot) by placement of an implant in the sinus tarsi. Subtalar arthroereisis may be performed alone or in combination with other comprehensive surgical procedures for ankle and foot conditions.
Investigational and Not Medically Necessary:
Subtalar arthroereisis is considered investigational and not medically necessary for all indications, including but not limited to the treatment of flatfoot conditions, symptomatic flexible flatfoot deformity, and posterior tibial tendon dysfunction (PTTD).
Subtalar arthroereisis has been suggested as an isolated procedure in a subset of individuals with symptomatic, recalcitrant adult and pediatric flexible flatfoot deformity and as a component of a more comprehensive surgical procedure, such as 1) posterior tibial tendon advancement, repair, or augmentation; 2) gastrocnemius or Achilles tendon lengthening; 3) medial displacement calcaneal osteotomy, midfoot osteotomies or fusion; or 4) tarsal coalition excision. Schon (2007) suggests that subtalar arthroereisis as an adjunct procedure may hold promise for individuals with mild and more severe variants of PTTD. However, the biomechanics of the implant function have not been fully explained and questions remain about the best clinical indications for use of the implant device. Schon concludes that "in the near future, better studies will help define the best results and outcomes [for the indications and use of specific arthroereisis implants]." As an isolated procedure, key outcomes of subtalar arthroereisis include both short and long term improvement in symptoms and other functional outcomes (i.e. walking), in addition to durability and other safety measures of the implant. When used as a component of a more comprehensive surgical procedure, controlled studies are needed to isolate the contribution of the arthroereisis to the overall treatment effect.
Subtalar Arthroereisis for Adult Flatfoot Conditions
The peer-reviewed published literature includes few studies focusing on subtalar arthroereisis and the surgical placement of subtalar implants for the treatment of flatfoot deformity. Brancheau and colleagues (2012) conducted a retrospective study of 35 individuals (60 feet) treated with the Maxwell-Brancheau Arthroereisis (MBA) implant (Subtalar MBA® Implant System; Integra LifeSciences Corporation, Plainsboro, NJ) in adults (and children) with flexible flatfoot. The mean age of the study cohort at the time of surgery was 14.3 (range 5 to 46) years. Adjunct procedures were performed in 48 (80%) of the 60 cases based on the participants presenting complaints, diagnostic and intraoperative findings. Pre- and postoperative anteroposterior and lateral foot radiographs were compared at a mean of 36 months postoperatively. The mean changes were reported as statistically significant (p<.00001) differences in five different talar/calcaneal/intermetararsal angles. It was noted, however, that correction of radiographic parameters is not always a reliable predictor of satisfaction with the surgical outcome. A subgroup of 24 (68.6%) participants responded to a subjective questionnaire at a mean of 33 months postoperatively. The presenting chief complaints were resolved in 23 of 24 individuals (95.8%) and 21 of 24 individuals (87.5%) returned postoperatively to either the same or a greater activity level in sports. When asked to rate their pain, the subgroup reported that 24 of 40 feet (60%) were considered free of pain postoperatively, 13 of 40 feet (32.5%) experienced mild pain, and 3 of 40 feet (7.5%) were moderately painful. Seventeen (71%) of the subgroup could stand for long periods of time without pain, however, seven of the subgroup (29%) could not. A substantial number of participants (11.9%) experienced complications including pain and restricted motion of the subtalar joint, the most common complaint requiring implant removal. The study outcomes are limited in drawing conclusions as to the safety and effectiveness of the MBA implant due to the number of participants lost to follow-up, heterogeneity of the participants based on age (participants of all ages were included), the arthroereisis and adjunct procedure decisions were determined by unblinded assessors, and the lack of statistical analysis to describe associations between variables and any particular outcome.
Several retrospective case series have been published in adults, one study reporting significant improvements in pain and function in 78% of participants (23 participants, 28 feet) with use of a subtalar implant as a component of reconstructive foot and ankle surgery (Needleman, 2006). A major limitation of this study was the small size of the sample population as well as the multiple etiologies of the flexible flatfoot deformity in these subjects (13 feet had congenital etiologies and 15 feet had acquired etiologies). In addition, since results were not compared with controls receiving reconstructive surgery without subtalar arthroereisis, the contribution of the implants to these outcomes is unclear. Finally, 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.
Two small case series reported outcomes of a combination of surgical interventions in which subtalar arthroereisis was one component; thus, the contribution of the arthroereisis is not clear. In a retrospective pilot study, Adelman and colleagues (2008) reported on pre- and postoperative radiographic changes in ten individuals with surgical correction of stage II PTTD. Lucaccini and colleagues (2008) analyzed clinical and radiographic results of 14 individuals (16 feet) with hallux valgus in abnormal pronation syndrome treated with distal osteotomy of the first metatarsal bone with subtalar arthroereisis performed in one stage. These case series are limited in drawing conclusions due to their small size and lack of comparison with nonsurgical or other surgical interventions.
Subtalar Arthroereisis for Pediatric Flatfoot and Other Conditions
Children with cerebral palsy and other neuromuscular disorders are another population who experience flatfoot deformity. Nelson and colleagues (2004) reported on a case series of 37 children (67 feet) who underwent a MBA implant as an isolated procedure. The average follow-up was 18.4 months. While this study reported various improvements in anatomic measurements, there was no data reported on improvement in symptoms or other functional outcomes from flatfoot deformity. Vedantam and colleagues (1998) reported on a case series of 78 children (140 feet) with neuromuscular disease who underwent subtalar arthroereisis with a Smith Subtalar Arthroereisis implant (STA-Peg) (Wright Medical Technology, Inc., Arlington, TN). The stem of this implant was 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 the children, although the contribution of the STA-Peg cannot be isolated as the implantation was combined with satisfactory muscle-balancing procedures.
Cicchinelli and colleagues (2008) reported on radiographic outcomes in a retrospective analysis of 28 feet in 20 children treated with subtalar arthroereisis combined with gastrocnemius recession or with subtalar arthroereisis combined with gastrocnemius recession and medial column reconstruction. The authors report that gastrocnemius recession had a notable effect on correction of transverse plane deformity when used as an adjunct to subtalar arthroereisis and gastrocnemius recession.
Scher and colleagues (2007) described two cases of extensive implant reaction in two children two years after STA-peg procedures and tendo-Achilles lengthening when performed for bilateral painful flatfoot deformities. The children 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 stated that "complications reported in the literature are common and wide ranging. The most commonly seen complication is continued severe postoperative pain with failure to reconstitute the longitudinal arch on weight bearing and a residual flatfoot deformity." Therefore, they do not recommend subtalar arthroereisis in the treatment of painful flexible flatfoot in children.
Subsequent published studies have reported on participant satisfaction, clinical and radiologic results, and complications after subtalar arthroereisis for pediatric flexible flatfoot. The first study by Koning and colleagues (2009) described the surgical technique involved with implantation of a custom-built cone-shaped implant; the secondary aim was to retrospectively evaluate satisfaction, clinical and radiologic results, and complications with a minimal follow-up of five years. Between January 1992 and June 2002, 40 children (80 feet) with a mean age of eight years (range, 4-11) underwent subtalar arthroereisis for flexible pes planovalgus. After temporary sinus tarsi tenderness (12 feet), implant dislocation (two feet) was the most common complication. Questionnaires from 27 participants (54 feet) were analyzed and clinical and radiographic results were evaluated for 44 feet. Thirteen children were lost to follow-up. The mean follow-up was 12.6 years (range, 5.9-16.1). Eighty-one percent of the responders reported satisfaction with the results. Clinically, normal alignment was present in 14 feet, and mild deformities remained in 26 feet. The average foot angle measurements were radiographically normal. The authors concluded that subtalar arthroereisis is a simple, minimally invasive operative option with satisfactory subjective and clinical results after mid- to long-term follow-up for children with flexible flatfoot. Several limitations of this study were acknowledged by the authors. In addition to its retrospective design, they were unable to compare the postoperative results to the preoperative situation as subjective (validated questionnaires) and radiologic data were unavailable. Secondly, "mild deformities remained in 26 feet. However, arbitrary cut-off points were used, which meant that feet with only a minor degree of planus, valgus, or both were also classified as having mild deformities."
A retrospective study by Scharer and colleagues (2010) evaluated the radiographic improvement of children who received an MBA subtalar implant for the treatment of painful pediatric flatfoot deformities. In this study, 39 children (mean age, 12 years) underwent surgical procedures including 68 MBA implants and were followed for a range of 6-61 months (mean, 24 months). Statistical evaluation was performed on all radiographic measurements. Radiographic evaluation demonstrated a significant improvement in three of three variables measured on the lateral and anterior-posterior radiographs. Statistically significant improvements were also seen between pre- and postoperative values for each measure, stratified by foot. Additional surgical procedures (i.e., 12 gastrocnemius recessions, six Achilles tendon lengthenings, and four Kidner posterior tibial tendon advancements) were performed in 22 of 68 feet. There were 10 (15%) complications, which consisted of 10 reoperations in 10 feet. Implants were exchanged in nine feet because of implant migration, overcorrection, and undercorrection. There was one reoperation (in one foot) for implant removal because of persistent sinus tarsi pain. This case series does not allow comparison with nonsurgical interventions or with other surgical interventions. The authors (Scharer, 2010) concluded that the MBA implant may be effective for the correction of painful, flexible flatfoot deformity in children in short-term follow-up, however
Significantly more study, both prospective and retrospective, is needed on subtalar arthroereisis. Our results were limited because there was no pre- or postoperative pain and functional health measurement used. Additional studies should be performed in the future to evaluate long-term follow-up in pediatric patients to access the longevity of correction and need for future treatment if needed.
In addition to the previously discussed study by Brancheau and colleagues (2012), Kellermann and colleagues (2011) evaluated pedographic outcomes of percutaneous arthroereisis using a screw through the sinus tarsi into the talus of 25 children with flexible flatfoot (43 calcaneo-stop procedures; 18 bilateral, seven unilateral). In this small prospective study, the mean age at surgery was 10 years of age and the mean follow-up time was 9.7 months (range, 3-19 months). A standard visual analog scale was used for rating participant satisfaction. Measurements of Meary's talus-first metatarsal angle with lateral radiograms were performed along with a dynamic pedographic assessment preoperatively and three to five months postoperatively. Participant satisfaction was rated as "excellent" for 33 feet of 19 children, "good" for eight feet of five children, and "poor" for either feet of one child. There were no complications during or following the surgery. By pedographic analysis, the area and the pressure-time integral (load amount, PTI) values increased on the lateral regions of the sole (except for the lesser toes) and decreased on the medial areas (except for the hallux). The relative contact time in the lateral midfoot increased from 63.8% (39.6-78.4%) to 75.1% (50-86.1%), and that in the lateral forefoot region from 81.2% (60.4-89.2%) to 86.8% (78.1-97.1%).The authors stated the short-term results following the anterograde screw implantation into the talus correlated well with the results of similar or different arthroereisis methods. Limitations of this study include the small population of participants and the lack of measurements of long-term outcomes. Further investigation is required to evaluate the long-term outcomes of this calcaneo-stop procedure for pediatric flexible flatfoot.
In a recent meta-analysis, Metcalfe and colleagues (2012) evaluated the available literature regarding arthroereisis in children for pediatric flexible flatfoot. The literature consists primarily of ad hoc case reports and retrospective case series (Level III and IV evidence). Methodological variations include device type, inclusion criteria, surgical technique, application of adjunctive procedures and outcome measures. Few studies applied validated clinical or participant reported outcome measures. While several studies demonstrated significant improvements in radiographic parameters including increased arch height and improved joint congruency following arthroereisis, the precise mechanism by which arthroereisis improves foot alignment remains to be explained. Calcaneal inclination angle demonstrated the least change with only small increases following arthroereisis. The procedure remains associated with a number of complications including sinus tarsi pain, device extrusion, and under-correction. Complication rates were reported to range between 4.8% and 18.6%, with unplanned removal rates between 7.1% and 19.3% across all device types. Despite the literature suggesting satisfaction rates of between 79% to 100%, additional qualitative outcome data based on disease specific, validated tools may improve current evidence and permit comparison of future study data.
Subtalar Arthroereisis for Other Conditions
There are currently no randomized, prospective controlled studies that evaluate the safety and efficacy of subtalar arthroereisis in combination with other surgical procedures such as posterior tibial tendon advancement, augmentation, or repair for PTTD, tendon lengthening, reconstruction, repair or transfer procedures for gastrocnemius or Achilles tendon/tendonitis-related conditions, or calcaneal osteotomies (e.g. medial displacement), midfoot osteotomies or fusion (e.g. hindfoot arthrodesis) or tarsal coalition excision for adult or pediatric flatfoot conditions including symptomatic flexible flatfoot deformity. The available peer-reviewed literature consists of small retrospective case series, some that address specific surgical techniques and others that address procedures performed on cadavers or involve biomedical modeling and analysis.
In a recent retrospective study conducted by the inventor of the HyProCure® (GraMedica®, Macomb, MI) extraosseous talotarsal stabilization (EOTTS) device, Graham and colleagues (2012), evaluated the long-term functional outcomes and device tolerance achieved in adults (n=83) treated for symptoms associated with hyperpronation caused by partial talotarsal joint dislocation or talotarsal joint instability. Data on subjective outcomes of post-operative device performance was collected from a mailed questionnaire to participants. At a mean follow-up period of 51 months, 52% (41 of 78) of responders reported complete alleviation of foot pain and 69% (54 of 78) had no limitations on their foot functional capabilities. The implant was permanently removed from seven out of the 117 treated feet (6% removal rate) due to prolonged pain of the anterior talofibular ligament (four cases), psychogenic reaction (two cases), and postoperative infection (one case). Excluding these explantations, an additional 16 participants underwent revision surgeries. Satisfaction with the appearance of their feet was reported in 80% (62 of 78) of cases. This study is limited in drawing conclusions as to the efficacy of the HyProCuredevice as a standalone procedure since 32% of the cases (35 of 110 feet in whom the implants were not removed) were performed with adjunctive procedures to achieve the desired amount of correction. In addition, the authors were not able to quantify the improvement in terms of preoperative subjection participant satisfaction scores.
Cook and colleagues (2011) reported a retrospective case-control study to identify factors that may contribute to failure (explantation) of titanium arthroereisis implants. All subjects who required removal of a self-locking wedge-type subtalar arthroereisis (n=22) were compared in a 1:2 ratio (n=44) to subjects with nonexplanted arthroereises 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, length of follow-up, implant position, surgeon experience, or concomitant procedures. Subjects 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.
The American College of Foot and Ankle Surgeons (ACFAS) has published two practice guidelines for the diagnosis and treatment of adult and pediatric flatfoot (Harris, 2004; Lee, 2005). In adults, the guideline states:
…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 (Lee, 2005).
In the pediatric population,
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 (Harris, 2004).
The American Association of Orthopaedic Surgeons has not taken a formal position with regard to the use of surgically placed implants as a treatment option for adult (acquired) flatfoot, flexible flatfoot in children, or in combination with other comprehensive surgical procedures for ankle and foot conditions.
In summary, the evidence in the peer-reviewed published literature is insufficient to draw conclusions as to the safety and effectiveness of subtalar arthroereisis with a surgically placed implant for the treatment of flatfoot deformity and other adult and pediatric ankle and foot conditions. Further research is required in the form of prospective controlled studies with long-term follow-up of functional improvement. This is particularly important given that the procedure is often performed in growing children.
Flatfoot (also known as pes planus) is a common but often complex congenital or acquired condition, with diverse symptoms and varying degrees of deformity and disability, with the common characteristic of partial or total collapse of the arch of the foot. Flexible flatfoot (i.e. the foot is flat when standing or weight-bearing and the arch returns when not standing) is one of the most common types, anatomically described as excessive pronation during weight bearing due to anterior and medial displacement of the talus. Flatfoot disorder is usually diagnosed in children as flexible flatfoot, paralytic flatfoot, or flatfoot associated with generalized ligamentous laxity, as seen in Marfan disease, Ehlers-Danlos Syndrome (EDS), Downs syndrome, cerebral palsy, myelomeningocele, developmental delay, and other syndromes. Flexible flatfoot in adults may be congenital or acquired due to PTTD, which in turn may be caused by trauma, overuse, and inflammatory disorders (such as rheumatoid arthritis), among others. Symptoms include pain, with or without a dull aching, throbbing or cramping sensation which in children may be described as "growing pains." In addition, flatfoot may contribute to symptoms of low back pain.
Conservative management of flexible flatfoot deformity includes orthotic therapy or shoe modifications, passive stretching exercises and medications such as nonsteroidal anti-inflammatory drugs. For an individual with more severe flatfoot deformity or ligamentous laxity in which ankle instability, PTTD, or early arthrosis has developed, an ankle-foot orthosis (AFO) or a more proximal device may be more appropriate. A skeletally mature adolescent may benefit from these types of orthoses as a last line of nonsurgical treatment. Various surgical procedures including hind-, mid-, and forefoot osteotomies, soft tissue medial column reconstruction, and subtalar joint arthrodesis have been used in the treatment of individuals who have failed conservative treatment (Blitz, 2010).
Arthroereisis, also referred to as arthroisis, is the limitation of excessive movement across the joint. Subtalar arthroereisis is a surgical procedure 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. Subtalar arthroereisis has been performed alone or in combination with other surgical procedures of the ankle and foot.
Subtalar arthroereisis has been performed for over 40 years, with a variety of implant designs and compositions. The Maxwell Brancheau Arthroereisis (MBA) implant involves a simple and reversible implantation procedure, compared to other devices such as the STA-Peg and Kalix® II device (newdeal® SAS, Integra™, Intergra LifeSciences Corp., Plainsboro, NJ). The device received U.S. Food and Drug Administration (FDA) 510(k) marketing clearance in 1996 because it was substantially equivalent to products on the market prior to device regulation. The implant is described as an "internal orthotic" designed for correction of pediatric pes valgus and adult posterior tibial dysfunction deformity. 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." The implant consists of a soft-threaded titanium device that is inserted into the sinus tarsi and does not require bone cement. The aim of the procedure is to restore the arch by blocking the anterior and inferior displacement of the talus and by preventing the foot from pronating, thus allowing normal subtalar joint motion. Tissue grows normally around the implant and aids in holding it in place. The individual can ambulate the day after surgery in a Cam walker for approximately three weeks. Thereafter, regular shoes can be worn with an ankle brace for an additional two to three weeks. 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. The MBA Resorb Implant received 510(k) marketing clearance in 2005. 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 reabsorbed by the body.
Numerous implant systems have received approval through the FDA's 510(k) process. A complete listing of subtalar implant devices that have received FDA approval are posted on the FDA's Center for Devices and Radiologic Health (CDRH) website (FDA, 2013).
Acquired flatfoot: Flatfoot occurring as a result of fracture or dislocation, tendon disruption, tarsal ligament disruption, tarsal coalition, arthritis, neuroarthropathy, neurologic weakness, or other causes.
Arthroereisis: The limitation of movement across a joint; also referred to as arthroisis.
Calcaneus: The heel bone.
Flexible flatfoot: A complex genetic or environmentally influenced condition where the medial longitudinal arch of the foot lowers and flattens out upon standing but reappears on toe rise.
Pes planus: A complex genetic or environmentally influenced condition with the common characteristic of partial or total flattening of the arch or instep of the foot; also referred to as flatfoot, fallen arches, pes planovalgus, over-pronation or pronation of feet.
Posterior tibial tendon dysfunction (PTTD): A progressive, painful collapse of the medial longitudinal arch of the foot as a result of degenerative or inflammatory processes, overstretching, or traumatic injury to the posterior tibial tendon; the most common cause of adult-acquired flatfoot.
Talus: One of the foot and ankle bones, located just above the calcaneus.
The following codes for treatments and procedures applicable to this document are included below for informational purposes. A draft of future ICD-10 Coding (effective 10/01/2014) related to this document, as it might look today, is included below for your reference. Inclusion or exclusion of a procedure, diagnosis or device code(s) does not constitute or imply member coverage or provider reimbursement policy. Please refer to the member's contract benefits in effect at the time of service to determine coverage or non-coverage of these services as it applies to an individual member.
When services are Investigational and Not Medically Necessary:
When the code describes a procedure indicated in the Position Statement section as investigational and not medically necessary.
|28899||Unlisted procedure, foot or toes [when specified as subtalar arthroereisis]|
|81.18||Subtalar joint arthroereisis|
|ICD-10 Procedure||ICD-10-PCS draft codes; effective 10/01/2014:|
|0SUH0JZ||Supplement right tarsal joint with synthetic substitute, open approach|
|0SUH3JZ||Supplement right tarsal joint with synthetic substitute, percutaneous approach|
|0SUH4JZ||Supplement right tarsal joint with synthetic substitute, percutaneous endoscopic approach|
|0SUJ0JZ||Supplement left tarsal joint with synthetic substitute, open approach|
|0SUJ3JZ||Supplement left tarsal joint with synthetic substitute, percutaneous approach|
|0SUJ4JZ||Supplement left tarsal joint with synthetic substitute, percutaneous endoscopic approach|
|ICD-10 Diagnosis||ICD-10-CM draft codes; effective 10/01/2014:|
Peer Reviewed Publications:
Government Agency, Medical Society, and Other Authoritative Publications:
|Web Sites for Additional Information|
Angled Subtalar Implant (ASI)
Arthrex ProStop Plus™ Subtalar Implant
Bioarch® Subtalar Arthroereisis Implant
bioBLOCK® Resorbable Subtalar Implant
BiPro® Horizon Subtalar Implant
Conical Subtalar Implant (CSI)
HyProCure Subtalar Implant System
Lundeen Subtalar Implant (L.S.I.)
Maxwell-Brancheau Arthroereisis (MBA) Implant
MBA Resorb Implant
MetaSurg BioArch Subtalar Implant System
OsteoMed Talar-Fit™ Subtalar Implant System
Posterior Tibial Tendon Dysfunction
Sub-Talar Lok™ Arthroereisis Implant System
Subtalar MBA Implant System
Subtalar Peg Implant
Talar-Fit Subtalar Arthroereisis Implant System
Trilliant Surgical (Twist) Subtalar Implant
The use of specific product names is illustrative only. It is not intended to be a recommendation of one product over another, and is not intended to represent a complete listing of all products available.
|Reviewed||05/09/2013||Medical Policy & Technology Assessment Committee (MPTAC) review. Minor format changes. Updated Background, References, and Web Sites.|
|Reviewed||05/10/2012||MPTAC review. Updated Rationale, Definitions, and References.|
|Revised||02/16/2012||MPTAC review. Combined investigational and not medically necessary statements into a single statement. Updated Rationale, Background, References, Web Sites for Additional Information and Index.|
|Reviewed||08/18/2011||MPTAC review. Updated References and Index.|
|Reviewed||08/19/2010||MPTAC review. Updated Rationale, Background, Coding, and References. Added Web Sites for Additional Information.|
|Reviewed||08/27/2009||MPTAC review. Updated Rationale, Background, References, and Index.|
|New||08/28/2008||MPTAC review. Initial document development.|