Coverage Policy Manual
Policy #: 2006009
Category: Surgery
Initiated: April 2006
Last Review: August 2018
  Computer-Assisted Musculoskeletal Surgical Navigational Orthopedic Procedure

Description:
The term computer-assisted musculoskeletal surgical navigational orthopedic procedure describes navigation systems that provide additional information during a procedure that attempt to further integrate preoperative planning with intraoperative execution. Navigation involves 3 steps: data acquisition, registration, and tracking.
 
Data Acquisition
 
As described by the 3 new 2004 CPT category III codes, data can be acquired in 3 different ways, i.e. fluoroscopic, CT/MRI guided, or imageless systems. This data is then used for registration and tracking. Image-guided systems are somewhat self-explanatory. The image-less systems rely on other information such as centers of rotation of the hip, knee, or ankle or visual information like anatomical landmarks.
 
Registration
 
Registration refers to the ability of relating images (i.e. x-rays, CT, MRI or patients’ 3-D anatomy) to the anatomical position in the surgical field. Early registration techniques required the placement of pins or “fiduciary markers” in the target bone. This required an additional surgical procedure. More recently, a surface-matching technique can be used in which the shapes of the bone surface model generated from preoperative images are matched to surface data points collected during surgery.
 
Tracking
 
Tracking refers to the sensors and measurement devices that can provide feedback during surgery regarding the orientation and relative position of tools to bone anatomy. For example, optical or electromagnetic trackers can be attached to regular surgical tools, which can then provide real time information of the position and orientation of the tools’ alignment with respect to the bony anatomy of interest.
 
Regulatory Status
Since CAN is a surgical information system in which the surgeon is only acting on the information that is provided by the navigation system, surgical navigation systems generally are subject only to 510(k) clearance from the U.S. Food and Drug Administration (FDA). As such, the FDA does not require data documenting the intermediate or final health outcomes associated with CAN. (In contrast, robotic procedures, in which the actual surgery is robotically performed, are subject to the more rigorous requirement of the premarket approval application [PMA] process.)
 
A variety of surgical navigation procedures have received FDA clearance through the 510(k) process with broad labeled indications. The following is an example; “The OEC FluoroTrak 9800 Plus provides the physician with fluoroscopic imaging during diagnostic, surgical and interventional procedures. The surgical navigation feature is intended as an aid to the surgeon for locating anatomical structures anywhere on the human body during either open or percutaneous procedures. It is indicated for any medical condition that may benefit from the use of stereotactic surgery and which provides a reference to rigid anatomical structures such as sinus, skull, long bone or vertebra visible on fluoroscopic images.”
 
Several navigation systems (e.g., PiGalileo™ Computer-Assisted Orthopedic Surgery System, PLUS Orthopedics; OrthoPilot® Navigation System, Braun; Navitrack® Navigation System, ORTHOsoft) have received FDA clearance specifically for TKA. FDA-cleared indications for the PiGalileo system are representative. This system “is intended to be used in computer-assisted orthopedic surgery to aid the surgeon with bone cuts and implant positioning during joint replacement. It provides information to the surgeon that is used to place surgical instruments during surgery using anatomical landmarks and other data specifically obtained intra-operatively (e.g., ligament tension, limb alignment). Examples of some surgical procedures include but are not limited to:
 
  • Total knee replacement supporting both bone referencing and ligament balancing techniques
  • Minimally invasive total knee replacement”
 
In 2013, the VERASENSE™ Knee System from OrthoSensor™ received 510(k) clearance from the FDA.
 
 
Coding
Effective in 2009, the coding for this navigation includes one category I CPT code and two category III CPT codes (which were reinstated 1/1/09):
 
20985: Computer-assisted surgical navigational procedure for musculoskeletal procedures; image-less (List separately in addition to code for primary procedure)
 
0054T: Computer-assisted musculoskeletal surgical navigational orthopedic procedure, with image guidance based on fluoroscopic images (List separately in addition to code for primary procedure)
 
0055T: Computer-assisted musculoskeletal surgical navigational orthopedic procedure, with image guidance based on CT/MRI images (List separately in addition to code for primary procedure)
 
0396T: Intra-operative use of kinetic balance sensor for implant stability during knee replacement arthroplasty (List separately in addition to code for primary procedure)

Policy/
Coverage:
Does Not Meet Primary Coverage Criteria Or Is Investigational For Contracts Without Primary Coverage Criteria
Computer-assisted musculoskeletal surgical navigational orthopedic procedure does not meet member benefit certificate primary coverage criteria that there be scientific evidence of effectiveness.
 
For members with contracts without primary coverage criteria, computer-assisted musculoskeletal surgical navigational orthopedic procedure is considered investigational.  Investigational services are an exclusion in the member certificate of coverage.

Rationale:
This policy was created in 2006 and updated periodically using the MEDLINE database. The most recent literature update was for the period of May 2011 through May 2012. Following are key studies to date.
 
Trauma or Fracture
Computer-assisted surgery has been described as an adjunct to pelvic, acetabular, or femoral fractures. For example, fixation of these fractures typically requires percutaneous placement of screws or guidewires. Conventional fluoroscopic guidance (i.e., C-arm fluoroscopy) provides imaging in only one plane. Therefore, the surgeon must position the implant in one plane and then get additional images in other planes in a trial and error fashion to ensure that the device has been properly placed. This process adds significant time in the operating room (OR) and radiation exposure. It is hoped the computer-assisted surgery would allow for minimally invasive fixation and provide more versatile screw trajectories with less radiation exposure. Therefore, computed-assisted surgery is considered an alternative to the existing image guidance using C-arm fluoroscopy.
 
Ideally, one would like controlled trials comparing OR time, radiation exposure, and long-term outcomes of those whose surgery was conventionally guided using C-arm versus image-guided using computer-assisted surgery. While several in vitro and review studies had been published, (Hofstetter, 2000; Schep, 2003; Slomczykowski, 2001) a literature search at the time this policy was created identified only one clinical trial of computer-assisted surgery in trauma or fracture cases (Suhm, 2000). Computer-assisted navigation (CAN) for internal fixation of femoral neck fractures has been described in a retrospective analysis consisting of 2 cohorts of consecutive patients (20 each, performed from 2001 to 2003 at 2 different campuses of a medical center) who underwent internal fixation with 3 screws for a femoral neck fracture (Liebergall, 2006). Three of 5 measurements of parallelism and neck coverage were significantly improved by CAN; these included a larger relative neck area held by the screws (32% vs. 23%) and less deviation on the lateral projection for both the shaft (1.7 vs. 5.2 degrees) and the fracture (1.7 vs. 5.5 degrees, all respectively) screw angles. Slight improvements in anteroposterior screw angles (1.3 vs. 2.1 and 1.3 vs. 2.4 degrees, respectively) did not reach statistical significance. There were 2 reoperations in the CAN group and 6 in the conventional group. Complications (collapse, subtrochanteric fracture, head penetration, osteonecrosis) were lower in the CAN group (3 vs. 11, respectively). Additional controlled studies are needed.
 
Anterior Cruciate Ligament (ACL) or Posterior Cruciate Ligament (PCL) Reconstruction
A 2011 Cochrane review assessed the effects of CAN in comparison with conventional operating techniques for ACL or PCL reconstruction (Meuffels, 2011). Four randomized controlled trials (RCTs, 266 participants) on ACL reconstruction were included in the review; no studies involved PCL reconstruction. Pooled data from 2 trials showed no statistically or clinically significant differences in self-reported health outcomes (International Knee Documentation Committee [IKDC] subjective scores and Lysholm scores) at 2 years or more follow-up. A third trial included in this review found a small statistically significant difference in IKDC subjective scores. No significant differences were found for objective measures of knee function, including the IKDC examination grade and pivot shift test. Evaluation of bias and methodologic quality was limited by poor reporting of trial methods. Overall, there was insufficient evidence to advise for or against the use of CAN. Three of the 4 trials included in the Cochrane review are described below.
One of the studies randomized 60 patients to either manual or computer-assisted guidance for tunnel placement with follow-up at 1, 3, 6, 12, 18, and 24 months (Plaweski, 2006). There were no differences between the groups in measurements of laxity. However, there was less variability in side-to-side anterior laxity in the navigated group (e.g., 97% were within 2 mm of laxity in the navigated group versus 83% in the conventional group at an applied force of 150 Newtons). There was a significant difference in the sagittal position of the tibial tunnel (distance from the Blumensaat line of 0.4 vs. -1.2 mm, respectively), suggesting possible impingement in extension for the conventional group. At the final follow-up (24 months), all knees had normal function, with no differences observed between the groups. Another study randomized 53 patients to manual or computer-assisted ACL reconstruction by 3 experienced surgeons (at least 1,000 cruciate ligament operations) (Mauch, 2011). Tunnel placement and range variance were similar for the 2 groups; indicating that experienced surgeons can achieve essentially the same positioning as CAN. Hart and colleagues compared biomechanical radiographic and functional results in patients randomized to ACL reconstruction using CAN (n=40) or the standard manual targeting technique (n=40). (9) Blinded evaluation found more exact bone tunnel placement with CAN but no overall difference in biomechanical stability or function between the groups.
 
Arthroplasty of the Hip and Knee
For both total hip and knee arthroplasties, optimal alignment is considered an important aspect of long- term success. Malalignment of arthroplasty components is one of the leading causes of instability and reoperation. In total hip arthroplasty (THA), orientation of the acetabular component of the THA is considered critical, while for total knee arthroplasty (TKA), alignment of the femoral and tibial components and ligament balancing are considered important outcomes. The alignment of the knee prosthesis can be measured along several different axes, including the mechanical axis, and the frontal and sagittal axes of both the femur and tibia. It is proposed that computer-assisted surgery improves the alignments of the various components of THA and TKA. Ideally, one would like controlled trials comparing the long-term outcomes, including stability and reoperation rates. Intermediate outcomes include the percentage of implants that achieve a predetermined level of acceptable alignment.
 
Total Hip Arthroplasty and Periacetabular Osteotomy: Paratte and Argenson randomized patients to CAN for THA (n=30) or freehand cup positioning (n=30) by an experienced surgeon (Parratte, 2007). The mean additional time for the computer-assisted procedure was 12 minutes. There was no difference between the computer-assisted group and the freehand-placement group with regard to the mean abduction or anteversion angles measured by computed tomography (CT). A smaller variation in the positioning of the acetabular component was observed in the CAN group; 20% of cup placements were considered to be outliers in the CAN group compared with 57% in the freehand-placement group. Another study randomly assigned 36 patients with symptomatic adult dysplastic hip to either CT-based navigation or the conventional technique for periacetabular osteotomy (Hsieh, 2006). (11) An average of 0.6 intraoperative radiographs were taken in the navigated group compared with 4.4 in the conventional group, resulting in a total operative time that was 21 minutes shorter for CAN. There were no differences between the groups for correction in femoral head coverage or for functional outcomes (pain, walking, range of motion) at 24 months.
 
It has been proposed that CAN may overcome the difficulties of reduced visibility of the surgical area associated with minimally invasive procedures. A 2007 review by Ulrich and colleagues summarized studies that compared outcomes from minimally invasive THA-CAN and standard THA (Ulrich, 2007). Seventeen studies were described in this evidence-based review, including 9 prospective comparisons, 7 retrospective comparisons, and 1 large (n=100) case series. The authors concluded that alignment with minimally invasive CAN appears to be at least as good as standard THA, although the more consistent alignment must be balanced against the current expense of the computer systems and increased surgical time. Improved health outcomes have not yet been demonstrated with CAN or minimally invasive THA, either alone or in combination.
 
A 2011 study by Manzotti et al. compared leg length restoration in a matched-pair study (Manzotti, 2011). Forty-eight patients undergoing THA with CAN were compared with patients who were matched for age, sex, arthritis level, preoperative diagnosis, and preoperative leg length discrepancy and underwent conventional freehand THA using the same implant in the same period. The mean preoperative leg length discrepancy was 12.17 mm in the THA-CAN group and 11.94 in the standard THA group. Surgical time was increased by 16 minutes (89 vs. 73 min, respectively). There was a significant decrease in both the mean postoperative leg length discrepancy (5.06 vs. 7.65 mm) and in the number of cases with a leg length discrepancy of equal to or greater than 10 mm (5 vs. 13 patients – all respectively). Outcomes at 40-month follow-up (range, 7 to 77 months) were not significantly different for the Harris Hip Score (88.87 vs. 89.73) or the 100-point normalized Western Ontario and McMaster Universities (WOMAC) Arthritis Index (9.33 vs. 13.21 – all respectively; p=0.0503). Longer follow-up with a larger number of subjects is needed to determine whether THA-CAN influences clinical outcomes.
 
Total Knee Arthroplasty: A 2007 TEC Assessment evaluated CAN for TKA. Nine studies from 7 randomized controlled trials (RCTs) were reviewed. Criteria for the RCTs included having at least 25 patients per group and comparing limb alignment and surgical or functional outcomes following TKA with CAN or conventional methods. Also reviewed were cohort and case series that evaluated long-term associations between malalignment of prosthetic components and poor outcomes. In the largest of the cohort studies, which included more than 2,000 patients (3,000 knees) with an average of 5-year follow-up, 41 revisions for tibial component failure (1.3% of the cohort) were identified. The risk ratio (RR) for age was estimated at 8.3, with a greater risk observed in younger, more active patients. For malalignment (defined as >3 degrees varus or valgus), the RR was estimated to be 17.3.
 
The combined data from the prospective RCTs showed:
 
  • A significant decrease in the percentage of limbs considered to be outliers (e.g., >3 degrees of varus or valgus from a neutral mechanical axis) with CAN. In the conventional group, 33% of patients had malalignment of the overall femoral/tibial axis. In the navigated group, 18% of patients were considered to have malalignment of the mechanical axis. For the combined data set, there was a decrease in malalignment in 15% of patients, with an estimated number needed to treat (NNT) of 6.7 to avoid 1 case of malalignment.
  • Surgical time increased by 10 to 20 minutes in all but 1 study. CAN-associated reduction in blood loss was less consistent, with only some of the studies showing a decrease in blood loss of 100 to 200 mL.
  • RCTs that assessed function (up to 2 years’ follow-up) did not find evidence of improved health outcomes. However, the studies were not adequately powered to detect functional differences, and data on long-term follow-up are not available.
 
The report concluded that no direct evidence is currently available to support an improvement in clinical outcomes with CAN for TKA. As a result of deficiencies in the available evidence (e.g., potential for bias in observational studies and lack of long-term follow-up in the RCTs), it is not possible to determine whether the degree of improvement in alignment that has been reported in the RCTs leads to meaningful improvements in clinically relevant outcomes such as pain, function, or revision surgery.
 
A meta-analysis of CAN for TKA was reported in 2007 that included 33 studies and 3,423 patients (Bauwens, 2007). The studies were of varying methodologic quality and included 11 randomized trials. Although no significant difference in mechanical axes between the navigated and conventional surgery group was found, navigated surgery was found to result in a lower risk of malalignment. It was calculated that 1 of every 5 patients would avoid unfavorable component positioning (greater than 3 degrees) with CAN. Methodologic weaknesses of the available trials limited the conclusions of the meta-analysis, and no conclusive inferences could be reached for functional outcomes or complication rates. A 2012 meta-analysis included 21 randomized trials (2,658 patients) that reported clinical outcomes with or without the use of CAN (Xie, 2012). Most of the studies included in the review had short-term follow-up. Operative time was significantly increased with CAN for TKA. There was no significant difference in total operative blood loss, the Knee Society Score (KSS), or range of motion.
 
A 2011 trial by Pang et al. evaluated the functional outcome of computer-assisted gap balancing (soft tissue balance) compared to conventional measured resection in TKA (Pang, 2011). A total of 140 patients were randomized into the 2 groups, and both patients and postoperative evaluators were blinded to treatment assignment. At 2 years, there were significantly more patients in the conventional group with flexion contracture of more than 5 degrees (7% vs. 1%). There was no significant difference between groups in hyperextension or ligament laxity. There was no significant difference between groups in the Knee score, Function Score, or Short Form (SF)-36. At the 2-year follow-up, the CAN group had better outcome in the Total Oxford Score (16.4 vs. 19.1). Interpretation of this finding is limited, since the post-operative Oxford Score did not differ from the pre-operative score with CAN (16.4 vs. 16.3), and the 2-year differences result from worsening scores in the conventional treatment group. Additional study is needed to determine with greater certainty whether flexion contracture is reduced with computer-assisted gap balancing.
 
Several non-randomized or quasi-randomized studies have examined the association between alignment and clinical outcomes at mid- to long-term follow-up. Hoffart et al. used alternate allocation of 195 patients to compare functional outcomes following CAN-assisted TKA versus conventional instrumentation (Hoffart, 2012). An independent observer performed the pre- and postoperative assessments. After 5 years, 18 patients (9.2%) were lost to follow-up and complete clinical scores were available for 121 patients (62%). There was no significant difference in the frequency of malalignment between the 2 groups. The CAN group had a better mean KSS and mean function and knee scores. Mean pain scores did not differ between the 2 groups. Limitations of this study include the high loss to follow-up and lack of subject blinding.
 
Czurda et al. compared outcomes from a consecutive series of 411 patients who underwent TKA-CAN (n=146) with the TC-PLUS SB Solution™ (Smith and Nephew) or standard TKA (n=265) with the LCS® Complete Mobile Bearing Knee System (Depuy) (Czurda, 2010). Eighty-one patients (20%) were not included in the analysis (23 in the TKA-CAN group and 58 in the standard TKA group) due to a variety of conditions that included death (n=2), infection (n=4), trauma (n=8), reoperation (n=10), or poor general condition (n=2). Fifty-five of the 81 patients (16 in the TKA-CAN and 39 in the standard TKA group) were lost to follow-up. The remaining 330 patients were interviewed by telephone by a single assessor and were classified as having painful knees if they listed pain as moderate or worse. At 11- to 41-month follow-up, median WOMAC scores were the same for both groups. Fifteen patients (12%) in the TKA-CAN group and 42 patients (20%) in the standard arm had moderate to severe pain (p=0.06). In order to further evaluate the relationship between pain and alignment, a second part of the study compared a subset of 19 patients who had painful knees with matched patients who had asymptomatic knees. Radiographic and CT analysis was performed for these 38 case-control subjects. There was no significant relationship between post-operative pain and the mechanical axis, flexion of the femoral component, or the dorsal slope. There was a trend for an association between patellar tracking and pain (odds ratio [OR]: 3.5, p=0.10) and a significant association between incorrect rotational malalignment and pain (OR: 7, p=0.033).
 
Ishida et al. compared 30 patients who had TKA-CAN with 30 matched patients who had the same implant type by the same surgeon during the same period of time using the standard manual approach (Ishida, 2011). Three patients from each group were lost to follow-up, leaving 27 patients in each group. At 5 to 7 year follow-up, the accuracy of the implantations, evaluated by 2 investigators who were blinded to clinical information, was significantly better in the TKA-CAN group for both the mechanical axis (18.5% vs. 33.3% outliers) and femoral rotational alignment (2 vs. 4 degrees twist angle – both respectively). Clinical assessment by an independent observer found superior range of motion (120 vs. 105 degrees) and Knee Society Scores (94 vs. 84 points – both respectively) in the TKA-CAN group. However, there was no difference between groups in pain (50 vs. 50 points) or Knee Society Functional scores (80 vs. 80 points – both respectively) at final follow-up.
 
A retrospective study by Parratte et al. assessed the influence of mechanical axis alignment on 15-year survival in 280 patients who received a standard cemented TKA between 1985 and 1990 (Parratte, 2010). A total of 106 out of 398 TKAs were found to have a postoperative mechanical axis of greater than 3 degrees. At the latest follow-up, there was a lower proportion of revisions in the outlier group than in the aligned group (13% vs. 15.4%, respectively). When comparing revisions due to aseptic loosening mechanical failure, wear, or patellar problems, 7.5% of the outlier group were revised compared with 9.2% of the aligned group. Thus, a postoperative mechanical axis of 0 + 3 degrees did not improve the 15-year survival rate following modern TKA.
 
Carter et al. compared outcomes from TKA in consecutive patients prior to and after acquisition of a CAN system in a community hospital (Carter, 2008). Of 310 consecutive surgeries, 200 patients (100 CAN and 100 conventional) consented to follow-up with a CT scan. Results were considered good if alignment was 3 degrees or less from the surgical goal, fair if between 4 and 6 degrees, poor if between 7 and 9 degrees, and extremely poor if greater than 9 degrees from the surgical goal. Blinded evaluation rated sagittal alignment as good in 78% of CAN and 47% of conventional knees for the femoral component and in 93% of CAN and 64% of conventional knees for the tibial component. Thirteen knees had poor or extremely poor sagittal-tibial alignment in the conventional group. Coronal alignment was not significantly different between the groups, although variance was greater in the conventional group. Tibial rotation was inconsistent in both groups. No learning curve was observed for the accuracy of alignment, although the initial cases required 12 to 20 minutes in additional time. By the end of the series, the highest volume surgeon required less time for CAN than for the conventional approach. Learning curves were also addressed in a prospective controlled observational study from 13 European orthopedic centers (Jenny, 2008). Five of the centers were experienced CAN users and 8 started using CAN for the study. The first 30 consecutive cases from each center were evaluated in an intention-to-treat manner, totaling 150 patients in the control group and 218 in the study group. The operations initially took 10 to 20 minutes longer in the study group, but after 30 procedures, the mean difference was 7 minutes (overall average of 118 minutes vs. 107 minutes operating time for the conventional group). The 3-month follow-up indicated that alignment for the experienced and novice centers was similar, and no differences were found in functional outcomes at a mean 24-month follow-up (9 to 37 months range). One complication was reported for the study group, consisting of a femoral fracture through the hole of the reference screw. In a comparative study of 160 bilateral TKAs performed by experienced surgeons in Asia, differences in measures of alignment between the conventionally prepared knee and the knee prepared with CAN-assistance were minimal (Kim, 2009).
 
Computer-Assisted Minimally Invasive TKA: It has been proposed that CAN may overcome the difficulties of reduced visibility associated with minimally invasive procedures. In one study, 108 consecutive patients were randomized to computer-assisted “minimally invasive” TKA or conventional TKA with standardized perioperative pain management for both groups (Dutton, 2008). An independent physical therapist performed the preoperative and postoperative patient assessments. Operative time was found to increase by an average of 24 minutes with minimally invasive CAN, with a difference in incision length of 4 cm (9 cm vs. 13 cm). Alignment was at 3 degrees or less from target in 92% of patients for the coronal tibiofemoral angle, 90% for the sagittal tibial component angle. This compared with 68% and 61%, respectively, for patients in the conventional TKA group. Three other measured angles were not significantly different. There was no difference in postoperative pain between the groups. Hospital stay, based on standardized functional criteria for discharge, was an average 1.2 days shorter (3.3 vs. 4.5 days). Functional improvement was noted at 1 month postoperatively for the number of patients who could walk independently for 30 minutes (details not reported). At 6 months, functional outcomes were similar for the 2 groups.
 
In 2008, Luring and colleagues published results from a 3-arm randomized trial (30 patients per group) that compared minimally-invasive TKA, with or without CAN, and conventional TKA (Luring, 2008). In this study, the mini-incision averaged 13 cm (range: 10–14 cm), while the conventional midline incision averaged 17 cm (range: 15–19 cm); both were performed with a medial parapatellar approach. In addition, with the minimally-invasive procedure, there was subluxation rather than eversion of the patella and no tibio-femoral dislocation. Postoperative rehabilitation and hospital stay were not described. On average, the surgical procedure took longer in the computer-assisted minimally invasive surgery group (58 min) compared to the conventional (44 min) and freehand minimally invasive surgery (MIS) group (40 min) and was associated with greater blood loss. Independent evaluation of postoperative radiographs showed reduced deviation in mechanical axis alignment in the CAN group (1.0 degree) compared to both the freehand minimally-invasive group (1.8 degrees) and the conventional TKA group (2.1 degrees). Compared to 3 outliers in the freehand minimally-invasive group and 2 outliers in the conventional TKA group, no outliers greater than 3 degrees were observed in the computer-assisted minimally invasive group. Follow-up (100%) with the Knee Society Score (KSS) and Western Ontario and McMaster Universities Arthritis Index (WOMAC) at 1, 6, and 12 weeks revealed no differences between the 3 groups. Since there was no statistically significant clinical difference at 6 or 12 weeks, the planned 6- and 12-month follow-up was stopped. According to patient satisfaction (WOMAC) and clinical outcome (KSS), the minimally invasive approach in TKA is still not proven.
 
High Tibial Osteotomy
Bae and colleagues compared the accuracy of closed-wedge high tibial osteotomy using CAN for medial compartment osteoarthritis of the knee and genu varum (n=50) with historical controls (n=50) that had undergone high tibial osteotomy using the conventional technique (Bae, 2009). The navigation system provided information about the deformity, level of osteotomy, correction angle and wedge size. In the conventional group, correction angle and wedge size were determined from a preoperative radiological plan and intra-operative measurement with the help of a cable. All of the cases had good quality preoperative and follow-up radiographs, and measurements were assessed by 2 independent investigators. The preoperative mechanical axis in the navigation group was varus 8.2 degrees with the navigation system and 7.3 degrees on radiographs. The mean postoperative mechanical axis was valgus 3.6 degrees with the navigation system and valgus 2.1 degrees with radiographs. The mean difference in the postoperative mechanical axis for the 2 measurements was 1.5 degrees. Compared with the conventional group, the variability of postoperative mechanical axis was significantly lower (2.3 degrees vs. 3.7 degrees, respectively). There were 19 cases of a mechanical axis between 2 degrees and 6 degrees in the conventional group compared with 2 cases in the navigated group. This study did not evaluate if the decrease in variability in the navigated group improved clinical outcomes.
 
Pelvic Tumor Resection
A 2009 review of the literature on computer-assisted pelvic tumor resection suggests that predefined osteotomy planes can be successfully identified during the operation and that planned surgical margins can be achieved (Fehlberg, 2009). The number of cases is small, and no controlled studies were identified that compared outcomes with conventional surgical approaches. However, inadequate (contaminated or intralesional) surgical margins have been reported in 12% to 75% of conventional cases. The authors note that the preoperative process for CAN is time-consuming, due to the lack of commercially available navigation platforms for pelvic applications.
 
Summary
Overall, the literature supports a decrease in variability of alignment with CAN, particularly with respect to the number of outliers. Although some observational data suggest that malalignment may increase the probability of early failure, recent RCTs with short- to mid-term follow-up have not shown improved health outcomes with CAN. Given the low short-term revision rates associated with conventional procedures and the inadequate power of available studies to detect changes in function, studies that assess health outcomes in a larger number of subjects with longer follow-up are needed. Potential uses of this procedure may be in gap balancing and the ability to decrease incision length without loss of accuracy in component alignment. Another area of potential benefit is pelvic tumor resection. Although evidence at this time has not adequately demonstrated improved health outcomes with this more resource-intensive combination, continued technology development in this area is expected.
 
 2013 Update
A literature search conducted using the MEDLINE database through July 2013. There was no new information identified that would prompt a change in the coverage statement. The key identified literature is summarized below.
 
Hip Arthroplasty
 
Total Hip Resurfacing (THR) with CAN. In 2013, Stiehler et al. reported short-term radiographic and functional outcomes from a randomized comparative trial of CAN-THR in 75 patients (Stiehler, 2013). For most of the radiographic measures, there was no significant difference between the CAN and conventional THR groups. There were fewer outliers (5 degrees or more) for the femoral component with CAN (11%) compared with conventional placement (32%). At 6 months’ follow-up, there were no differences between groups in the final WOMAC or Harris Hip Score. The CAN group did show a greater percentage improvement in the WOMAC and Harris Hip Score due to differences between the groups at baseline.
 
Total Knee Arthroplasty
 
Effect of CAN on Mid- to Long-term Outcomes. Most studies comparing outcomes between CAN and conventional TKA at mid- to long-term are non-randomized. These studies generally show a reduction in the number of outliers with CAN, but little to no functional difference between the 2 groups.
 
In a 2009 comparative study of 160 bilateral TKAs performed by experienced surgeons in Asia, differences in measures of alignment between the conventionally prepared knee and the knee prepared with CAN-assistance were minimal (Kim, 2009). In 2012, this group reported longer-term follow-up (mean of 10.8 years) on 520 patients who underwent CAN for one knee and conventional TKA for the other knee (randomized) (Kim, 2012). There were no significant differences between the groups for knee function or pain measures. Kaplan-Meier survivorship at 10.8 years was 98.8% in the CAN knee and 99.2% for the conventional knee. Two additional non-randomized comparative studies from 2012 found an improvement in alignment with CAN, but no difference in clinical or functional outcomes at 5-year follow-up when compared with conventional TKA. (Hoppe, 2012; Yaffe, 2013).
 
Ishida et al. compared 30 patients who had TKA-CAN with 30 matched patients who had the same implant type by the same surgeon during the same period of time using the standard manual approach (Ishida, 2011). At 5- to 7-year follow-up, the accuracy of the implantations, evaluated by 2 investigators who were blinded to clinical information, was significantly better in the TKA-CAN group for both the mechanical axis (18.5% vs. 33.3% outliers) and femoral rotational alignment (2 vs. 4 degrees twist angle – both respectively). Clinical assessment by an independent observer found superior range of motion (120 vs. 105 degrees) and Knee Society Scores (94 vs. 84 points – both respectively) in the TKA-CAN group. However, there was no difference between groups in pain (50 vs. 50 points) or Knee Society Functional scores (80 vs. 80 points – both respectively) at final follow-up.
 
Hoffart et al. used alternate allocation of 195 patients to compare functional outcomes following CAN-assisted TKA versus conventional instrumentation (Hoffart, 2012).  An independent observer performed the pre- and postoperative assessments. After 5 years, 18 patients (9.2%) were lost to follow-up and complete clinical scores were available for 121 patients (62%). There was no significant difference in the frequency of malalignment between the 2 groups. The CAN group had a better mean KSS and mean function and knee scores. Mean pain scores did not differ between the 2 groups. Limitations of this study include the high loss to follow-up and lack of subject blinding.
 
Effect of Alignment on Mid- to Long-term Outcomes. In 2012, Huang et al. reported 5-year follow-up of a 2009 randomized trial (Huang, 2012; Choong, 2009). In the initial report, a greater accuracy in implant alignment was associated with better knee function and quality of life. Of the original 115 patients, 90 (78%) were available for follow-up at 5 years. Of these, coronal alignment was within 3 degrees of neutral in 69 patients (91% of CAN patients vs. 61% of conventional) and greater than 3 degrees in 21 patients (9% of CAN patients vs. 39% of conventional). Patients with coronal alignment within 3 degrees of normal scored significantly higher on the KSS at 2 years (median of 162 vs. 131) and 5 years (142 vs. 129). This study is unusual in that the investigators compared outcomes based on alignment, rather than comparing outcomes from the CAN and conventional TKA groups.
 
2014 Update
 
A literature search conducted through July 2014 did not reveal any new information that would prompt a change in the coverage statement. The key identified literature is summarized below.
 
In a randomized trial of 125 patients, Lass et al compared the acetabular component position between CAN vs the conventional freehand technique (Lass, 2014). CT scans identified higher accuracy for acetabular component anteversion, deviation from the target position for anteversion, and in outliers from the target for inclination and anteversion. The operation time was 18 minutes longer for CAN. Functional outcomes were not assessed.
 
Rebal et al conducted a 2014 meta-analysis of 20 RCTs (1,713 knees) that compared imageless navigation technology with conventional manual guides (Rebal, 2014). Nine studies were considered to have a low risk of bias due to the blinding of the patient or surgical personnel. Fifteen studies were considered to have a low risk of bias due to evaluator blinding. The improvement in KSS was statistically superior in the CAN group at 3 months (4 studies, 68.5 vs. 58.1, p =.03) and at 12-32 months (5 studies, 53.1 vs. 45.8, p <.01); the minimal clinically significant difference was defined as a change of 34.5 points.
 
Gothesen et al reported 1 year follow-up from a double-blinded trial of 192 patients randomized to CAN or conventional TKA (Gothesen, 2014).. CAN took 20 minutes longer than conventional surgery, and led to significantly fewer outliers in frontal alignment and tibial slope. Statistically significant improvements with CAN were found on the Knee Injury and Osteoarthritis Outcome Score (KOOS) sports (mean difference 11.0, p = .007) and KOOS symptoms (mean difference 6.7, p = .035), but not for KOOS pain, KOOS quality of life, VAS or KSS. Only the KOOS subscale for sports and recreational activities exceeded the predefined minimal important change.
 
Effect of CAN on Mid- to Long-term Outcomes. Most studies comparing outcomes between CAN and conventional TKA at mid- to long-term are generally show a reduction in the number of outliers with CAN, but little to no functional difference between the 2 groups.  
 
Follow-up from 2 randomized studies were published in 2013/2014 that assessed mid-term functional outcomes following CAN for TKA. Blakeney et al reported 46 month follow-up of 107 patients from a randomized trial of CAN vs conventional surgery (Blakeney, 2014). There was a trend towards higher scores on the Oxford Knee questionnaire with CAN, with a mean score of 40.6 for the CAN group compared to 37.6 and 36.8 in extramedullary and intramedullary control groups. There was no significant difference in the SF-12 physical component or mental component scores. The study was underpowered, and the clinical significance of this trend for the Oxford Knee questionnaire is unclear. Lutzner et al reported 5-year follow-up in 67 of 80 patients randomized to CAN or conventional TKA (Lutzner, 2013). There was a significant decrease in the number of outliers with CAN (3 vs 9, P=.048), but no significant differences between the groups on the KSS or Euroquol questionnaire for quality of life.
 
2015 Update
A literature search using the MEDLINE database conducted through July 2015 did not identify any new information that would prompt a change in the coverage statement.
 
2017 Update
A literature search conducted through July 2017 did not reveal any new information that would prompt a change in the coverage statement. The key identified literature is summarized below.
 
Lutzner and colleagues reported 5-year follow-up for 67 of 80 patients randomized to CAN or conventional TKA (Lutzner, 2013). There was a significant decrease in the number of outliers with CAN (3 vs 9, p=0.048), but no significant differences between groups on the KSS or EuroQoL questionnaire for quality of life. Cip and colleagues found a significant decrease in malalignment with CAN, but no significant differences in implant survival or consistent differences clinical outcome measures between the navigated (n=100) and conventional (n=100) TKA groups at minimum 5-year follow-up (Cip, 2014). Song and colleagues also reported a reduction in the number of outliers with CAN (7.3% vs 20%, p=0.006), with no significant differences in clinical outcomes at 8-year follow-up (Song, 2016). The trial which, assessed 80 patients (88 knees), was powered to detect a 3-point difference in KSS results.
 
In 2016, Dyrhovden and colleagues compared survivorship and the relative risk of revision at 8-year follow-up for 23,684 cases from the Norwegian Arthroplasty Register (Dyrhovden, 2016). Overall prosthesis survival and risk of revision were similar for the 2 groups, although revisions due to malalignment were reduced with CAN (RR=0.5; 95% CI, 0.3 to 0.9; p=0.02). There were no significant differences between the groups for other reasons for revision (eg, aseptic loosening, instability, periprosthetic fracture, decreased range of motion). At 8 years, the survival rate was 94.8% (95% CI, 93.8% to 95.8%) in the CAN group and 94.9% (95% CI, 94.5% to 95.3%) for conventional surgery.
 
2018 Update
Annual policy review completed with a literature search using the MEDLINE database through July 2018. No new literature was identified that would prompt a change in the coverage statement.

CPT/HCPCS:
0054TComputer-assisted musculoskeletal surgical navigational orthopedic procedure, with image-guidance based on fluoroscopic images (List separately in addition to code for primary procedure)
0055TComputer-assisted musculoskeletal surgical navigational orthopedic procedure, with image-guidance based on CT/MRI images (List separately in addition to code for primary procedure)
0396TIntra-operative use of kinetic balance sensor for implant stability during knee replacement arthroplasty (List separately in addition to code for primary procedure)
20985Computer-assisted surgical navigational procedure for musculoskeletal procedures, image-less (List separately in addition to code for primary procedure)

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Group specific policy will supersede this policy when applicable. This policy does not apply to the Wal-Mart Associates Group Health Plan participants or to the Tyson Group Health Plan participants.
CPT Codes Copyright © 2019 American Medical Association.