Computer Assisted Surgery (CAS)

Computer Assisted Surgery (CAS)

2012 AAOS Balancing the Hype

Do You Really Need Computer Navigation for TKR: "My Perspective"
Author: Ranawat

Computer assisted surgery (CAS) was introduced in TKR 10 years ago to achieve mechanical alignment within 3 degrees. Based on claims and supporting data, to date, CAS has not been able to show the improved quality of results and durability. It is certainly not cost effective.

At the present, surgeons and hospitals are using navigation system for marketing – to make money and to increase the market share.

CAS has not established its superiority based on quality results and durability.

Computer Navigated TKR: OK (Though not required) For Routine Use
Author: Pagnano

Computer navigation remains a cumbersome, time consuming and expensive tool with relatively little proven clinical benefit in improving function or durability if TKR. ... we are now entering the second decade of clinical use with navigation systems and still we can find no major evidence of a clinical benefit. For a small subgroup of surgeons, those benefits remain enough to outweigh the negatives of contemporary navigation systems.

What has also been demonstrated with the computer, however, are a number of things that are not as favorable; it increases surgical times, increases the cost of surgery and increases the prevalence of specific complications. But the specific support for that contention (better component alignment) remains surprisingly weak.

Before asking hospitals and payers to absorb these substantial time costs and financial costs associated with contemporary navigation symptoms, advocates of computer navigation should prove the fundamental premise that correction of the mechanical access will substantially improve implant durability or clinical function.

A recent review by Desai et al. nicely summarizes the current status of navigation in TKR. They concluded that "there is no convincing evidence that demonstrates improved clinical outcomes with CAS in Total Knee Arthroplasty ... the majority of studies show that navigated TKR decreases the malalignment of the mechanical limb access compared with conventional TKR. It is not very clear whether this marginal benefit makes much difference in long term outcome of the patient."

Pros and Cons of CAS ( Computer Assisted Surgery ) in TKR
Author: Hozack

Computer assisted surgery: CONS:

  • Need larger incision if CAS trackers inside the incision.
  • CAS trackers outside the incision are placed in cortical bone and can lead to bone fractures.
  • Extra time is required to do the operation.
  • Accuracy of information input – registration errors.

CAS VS Manual TKR: No Difference in Clinical or Radiographic Outcomes at 5 Years
Author: Yaffe et al.

There is no statistically significant difference between 5 year post-operative pain scores, Range Of Motion, or UCLA activity scores. Mechanical axis as measured on plain radiographs did not reveal a significant difference between manual and CAS at one month or 5 years post-operative.

The study found similar clinical, functional and radiographic outcomes at 5 year followup between manual( not computer assisted) and CAS TKA.

Computer Navigated TKA; RCT MIS vs Conventional Incision Technique
Author: Arts et al.

The hypothesis that patients benefit from the MIS (Minimal Incision Surgery) technique is by shorter recovery periods following surgery, less blood loss, faster wound healing and better mobility in early post-op rehabilitation was not confirmed by the results of this study. The MIS surgery technique also FAILED to generate clear advantages in terms of function, pain, ROM, KSS, WOMAC, radiological evaluation, or clinical or functional outcomes that persisted over time.

2012 American Academy of Orthopedic Surgeons (AAOS) Meeting - San Francisco: Selected excerpts

-JGM