The term "computer-assisted musculoskeletal surgical navigational orthopedic procedure" describes navigation systems that provide additional information during a procedure in order to further integrate preoperative planning with intraoperative execution.

Investigational and Not Medically Necessary:

Computer-assisted musculoskeletal surgical navigation is considered investigational and not medically necessary as an adjunct to orthopedic procedures.

General Information

Computer-assisted surgery has been investigated in three general settings: 1) as an adjunct to surgery for trauma or fracture; 2) as an adjunct to knee or hip arthroplasty procedures; or 3) as an adjunct to anterior cruciate ligament reconstruction.  Each of these categories will be discussed separately, but in general, computer-assisted surgery attempts to either provide increased efficiency in the surgical procedure or improve the biomechanical alignment of joints.  Improvements in surgical efficiency can be measured in terms of operating time or radiation exposure.  Changes in alignment are considered an intermediate outcome.  The final health outcome involves consideration of how these changes will impact final functional outcomes, which can be assessed with knee or hip scores, or surgical revision rates.  The following review focuses on the results of randomized controlled trials.

Trauma or Fracture  

Computer-assisted surgery has been most frequently mentioned 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 operating room (OR) time 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, computer-assisted surgery is considered an alternative to the existing image guidance using C-arm fluoroscopy.

Ideally, one would like controlled trials comparing the OR time, the radiation exposure and long-term outcomes of individuals whose surgery was conventionally guided using C-arm versus image-guided using computer-assisted surgery.  While several in vitro and review studies have been published (Schep, 2003; Hufner, 2002; Leenders, 2002; Digioia, 2002), a literature search identified only one clinical trial of computer-assisted surgery in trauma or fracture cases.  Suhm and colleagues reported on a case series of 27 patients with femoral fractures who underwent implantation of a femoral nail (Slomczykowski, 2001).  Outcomes included precision of interlocking, exposure time and OR time.  Without a control or comparison group, it is not possible to determine the efficacy of the computer assistance.

Total Knee Arthroplasty (TKA) 

A total of 9 randomized controlled trials enrolling more than 25 patients and comparing computer-assisted with conventional TKA were identified in a literature search; two of these publications reported on long term follow-up of the same group of patients. (Chauhan 2004, Chin 2005, Decking 2005, Victor 2004, Matziolis 2007, Decking 2007, Ensini 2006, Kim 2007, Spencer 2007 Lutzner 2008).  These studies compared various measures of alignment in the two groups.  While all studies reported improvements in target alignments, only 4 of the 7 studies reported that the improvements in overall tibial/femoral alignment were statistically significant (Chauhan, Decking, Victor, Matziolis).  A key consideration is how changes in alignment relate to improvements in patient outcomes.  The largest study that reported patient outcomes was that of Ensini (2007), which reported no difference in knee scores or patient satisfaction at 2-3 year follow-up.  Other studies similarly did not report a significant improvement in functional outcome.  There were no studies that evaluated a reduction in the surgical revision rate associated with computer-assisted navigation. 

Two additional randomized studies examined the role of computer-assisted navigation in patients undergoing minimally invasive total knee arthroplasty.  Luring and colleagues (2008) randomized 60 patients to undergo minimally invasive TKA with and without computer-assisted navigation.  While the postoperative deviation in leg axis was decreased in the navigation group, there were no differences in functional outcomes at 12 months.  Similarly in a randomized study of 108 patients, Dutton and colleagues (2008) reported that while navigated minimally invasive TKA was associated with an improvement in postoperative alignment, there was no difference in functional outcomes.

In 2007, Bauwens and colleagues performed a systematic review and meta-analysis comparing navigated with conventional knee arthroplasty.  A total of 33 studies (of which 11 were randomized trials) of various methodological quality were reviewed to include a total of 3423 patients with a mean age of 67.3 ± 4.1 years.  There was no significant difference in the mechanical axes alignment between the navigated and conventional TKA procedures.  Patients who underwent the navigated procedure had a lower risk of malalignment at critical thresholds of >3° (risk ratio, 0.79; 95% confidence interval, 0.71 to 0.87) and >2° (risk ratio, 0.76; 95% confidence interval, 0.71 to 0.82).  However, as the authors point out, it is unclear if this marginal benefit will result in better long-term outcomes.  Computer-assisted navigation increased the length of the mean duration of surgery by 23%.  No solid conclusions could be drawn with regards to functional outcomes or complication rates.  The authors concluded that the clinical benefits of navigated TKA are still ambiguous and that additional research involving larger studies are needed.    

Total Hip Arthroplasty (THA)
There are fewer controlled studies examining the role of THA with computer-assisted navigation.  Two randomized studies specifically focused on placement of the acetabular component.  Parratte and Argenson (2007) reported on the results of 60 patients undergoing THA with and without computer navigation.  The primary outcome was cup anteversion and abduction angles; there were no significant differences between the two groups.  Similarly, in a randomized trial of 25 patients, Kalteis and colleagues reported improved anteversion angles in the navigated group, and that a higher percentage of patients were within the target region of acetabular placement.  No functional outcomes were reported in either of these trials.  In another small randomized trial of 36 patients undergoing femoral osteotomy for dysplastic hip, Hsieh and colleagues (2006) did not report any differences in functional outcomes at 24 months between the navigated and conventional surgical group.

In an uncontrolled case series, Leenders and colleagues studied the variability in placement of the acetabular component among three groups of patients: 1) those undergoing THA using free hand placement before computer-assisted surgery was available; 2) those undergoing THA with computer assistance, and 3) those undergoing free hand placement after computer assistance was available (Leenders, 2002).  While there was a reduction in variability between groups one and two, there was not a significant difference between groups two and three.  No data regarding long-term outcome was reported.  Digioia and colleagues reported on a case series of 78 patients (82 hips) who underwent THA and compared the alignment directed by a mechanical guide and computer assistance.  The authors hypothesized that the use of the mechanical guide rather than computer assistance would have resulted in an unacceptable acetabular alignment in 78% of hips (Digioia, 2002). 

More recently there appears to be growing interest in imageless navigation systems, for both arthroplasties and hip resurfacing procedures.  Numerous case series and retrospective reviews have been published that report improved alignment (Olsen 2009, Bailey 2009, Romanowski 2008, Najarian 2009, Dorr, 2007).  However, as noted above, controlled studies with functional outcomes are needed to validate that computer-assisted navigation results in improved health outcomes.

Anterior Cruciate Ligament Reconstruction
The positioning of the tibial and femoral tunnels is considered an important variable in anterior cruciate ligament (ACL) reconstructions.  Plaweski and colleagues (2006) reported the results of 60 patients randomized to undergo ACL reconstruction with and without computer-assisted navigation.  The navigated group had improved measures of laxity and other alignment variables, but there was no report in improvement in functional outcomes.  Two other smaller randomized trials also reported some improvements of tunnel placement associated with computer navigation compared to conventional treatment, but with no reported improvements in functional outcomes (Hart 2008, Mauch 2007).

Summary
While results of controlled trials suggest improvements in the intermediate biomechanical outcomes, there is inadequate data on final health outcomes, as assessed by improvements in functional outcomes or surgical revision rates.  Computer-assisted musculoskeletal navigation has been primarily investigated as an adjunct to surgery of the knee and hip.  There is only very preliminary literature regarding its use in the upper extremity (i.e. shoulder and elbow) and axial skeleton (i.e. spine).   

Computer-assisted musculoskeletal surgical navigational systems allow surgeons to perform complex, traditionally invasive trauma surgeries, such as femoral and pelvic fracture fixation, through small incisions. Using this navigational technology, surgeons may be able to reduce the amount of time a patient is in surgery, limit radiation exposure, blood loss and rehabilitation time while increasing surgical accuracy. Computer-assisted musculoskeletal surgical navigation involves three steps; data acquisition, registration and tracking.

Data Acquisition 

Data can be acquired in three different ways, i.e., fluoroscopic, CT/MRI guided or imageless systems. This data is then used for registration and tracking, described below. 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.

The most commonly performed orthopedic computer-assisted surgeries appear to be as an adjunct to fixation of pelvic, acetabular or femoral fractures, and as an adjunct to hip and knee arthroplasty procedures.

The following codes for treatments and procedures applicable to this document are included below for informational purposes.  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 services may be Investigational and Not Medically Necessary:
For the following procedure codes when used in addition to musculoskeletal procedures

Peer Reviewed Publications:

1. Bailey C, Gul R, Falworth M, Zadow S, Oakeshott R. Component alignment in hip resurfacing using computer navigation. Clin Orthop Relat Res. 2009;467(4):917-922.
2. Bauwens K, Matthes G, Wich M, et al. Navigated total knee replacement. A meta-analysis. J Bone Joint Surg Am. 2007; 89(2):261-269.
3. Chauhan SK, Scott RG, Breidahl W et al.  Computer assisted knee arthroplasty versus a conventional jig-based technique. A randomised, prospective trial.  J Bone Joint Surg 2004;86-B:372-377.
4. Chin PL, Foo LS, Yang KY, Yeo SJ, Lo NN. Randomized controlled trial comparing the radiologic outcomes of conventional and minimally invasive techniques for total knee arthroplasty. J Arthroplasty. 2007;22(6):800-806.
5. Decking R, Markmann Y, Fuchs J, et al. Leg axis after computer-navigated total knee arthroplasty. J Arthroplasty. 2005; 20(3):282-288.
6. Decking R, Markmann Y, Mattes T et al.  On the outcome of computer-assisted total knee replacement.  Acta Chir Orthop Traumatol Cech 2007;74:171-174.
7. Digioia AM, Jaramaz B, Plakseychuk AY, et al. Comparison of a mechanical acetabular alignment guide with computer placement of the socket. J Arthroplasty. 2002; 17(3):359-364.
8. Dorr LD, Malik A, Wan Z, Long WT, Harris M. Precision and bias of imageless computer navigation and surgeon estimates for acetabular component position. Clin Orthop Relat Res. 2007;465:92-99.
9. Dutton AQ, Yeo SJ, Yang KY, et al.  Computer-assisted minimally invasive total knee arthroplasty compared with standard total knee arthroplasty. A prospective, randomized study. J Bone Joint Surg 2008;90(1):2-9.
10. Ensini A, Catani F, Leardini A et al.  Alignments and clinical results in conventional and navigated total knee arthroplasty.  Clin Orthop Relat Res 2007;457:156-162.
11. Hart R, Krejzla J, Sváb P et al.  Outcomes after conventional versus computer-navigated anterior cruciate ligament reconstruction.  Arthroscopy. 2008;24:569-578.
12. Hsieh PH, Chang YH, Shih CH.  Image-guided periacetablular osteotomy: computer assisted navigation compared with the conventional technique: A randomized study of 36 patients followed for 2 years.  Acta Orthop 2006;77:591-597.
13. Hufner T, Pohlemann T, Tarte S, et al. Computer-assisted fracture reduction of pelvic ring fractures: an in vitro study. Clin Orthop Relat Res. 2002; 399:231-239.
14. Kim YH, Kim JS, Yoon SH.  Alignment and orientation of the components in total knee replacement with and without navigation support: A prospective, randomized study.  J Bone Joint Surg 2007;89-B:471-476.
15. Leenders T, Vandevelde D, Mahieu G, Nuyts R. Reduction in variability of acetabular cup abduction using computer-assisted surgery: a prospective and randomized study. Computer Aided Surg. 2002; 7(2):99-106.
16. Lüring C, Beckmann J, Haiböck P et al.  Minimal invasive and computer assisted total knee replacement compared with the conventional technique: a prospective, randomised trial.  Knee Surg Sports Traumatol Arthrosc. 2008 Oct;16(10):928-934.
17. Lützner J, Krummenauer F, Wolf C et al.  Computer-assisted and conventional total knee replacement: a comparative, prospective, randomised study with radiological and CT evaluation. J Bone Joint Surg Br. 2008 Aug;90(8):1039-1044.
18. Matziolis G, Locker D, Weiss U et al.  A prospective, randomized study of computer-assisted and conventional total knee arthroplasty. Three-dimensional evaluation of implant alignment and rotation.  J Bone Joint Surg 2007;89-A:236-243. 
19. Mauch F, Apic G, Becker U, Bauer G.  Differences in the placement of the tibial tunnel during reconstruction of the anterior cruciate ligament with and without computer-assisted navigation.  Am J Sports Med. 2007;35(11):1824-1832.
20. Najarian BC, Kilgore JE, Markel DC. Evaluation of component positioning in primary total hip arthroplasty using an imageless navigation device compared with traditional methods. J Arthroplasty. 2009;24:15-21.
21. Olsen M, Davis ET, Waddell JP, Schemitsch EH. Imageless computer navigation for placement of the femoral component in resurfacing arthroplasty of the hip. J Bone Joint Surg Br. 2009;91(3):310-315.
22. Parratte S, Argenson JN.  Validation and usefulness of a computer-assisted cup-positioning system in total hip arthroplasty. A prospective, randomized, controlled study.  J Bone Joint Surg 2007;89-A:494-499.
23. Plaweski S, Cazal J, Rosell P et al.  Anterior cruciate ligament reconstruction using navigation.  A comparative study on 60 patients.  Am J Sports Med 2006;34:542-552.
24. Romanowski JR, Swank ML. Imageless navigation in hip resurfacing: avoiding component malposition during the surgeon learning curve. J Bone Joint Surg Am. 2008;90(suppl 3):65-70.
25. Schep NW, Broeders IA, van der Werken C. Computer-assisted orthopaedic and trauma surgery. State of the art and future perspectives. Injury. 2003; 34(4):299-306.
26. Slomczykowski MA, Hofstetter R, Sati M, et al. Novel computer-assisted fluoroscopy system for intraoperative guidance: feasibility study for distal locking of femoral nails. J Orthop Trauma 2001; 15(2):122-131.
27. Spencer JM, Chauhan SK, Sloan K et al.  Computer navigation versus conventional total knee replacement.  No difference in functional results at two years.  J Bone Joint Surg 2007;89(4):477-480.
28. Suhm N, Jacob AL, Nolte LP, et al. Surgical navigation based on fluoroscopy--clinical application for computer-assisted distal locking of intramedullary implants. Comput Aided Surg 2000; 5(6):391-400.
29. Victor J, Hoste D.  Image based computer-assisted total knee arthroplasty leads to lower variability in coronal alignment.  Clin Orthop Relat Res 2004;428:131-139. 

Government Agency, Medical Society, and Other Authoritative Publications: 

1. Blue Cross Blue Shield Association. Computer-assisted navigation for total knee arthroplasty. TEC Assessment, 2008; 22(10).  Available at:  http://blueweb.bcbs.com/global_assets/special_content/tec_assessments/vol22/22_10.pdf  Accessed on July 10, 2009.
2. Hayes Inc. Hayes Medical Technology Directory. Minimally Invasive Total Hip Arthroplasty. Lansdale, PA:  Hayes, Inc.; August 2004. Search updated August 28, 2008.

Computer-Assisted Musculoskeletal Surgical Navigational Orthopedic Procedures