Thursday, March 21, 2013

More robots, more questions

A partial knee replacement is surgery to replace either the inside (medial) or outside (lateral) parts of the knee. Partial knee replacement surgery removes damaged tissue and bone in the knee joint and replaces the area with a man-made implant.  The procedure is known as unicompartmental knee arthroscopy (UKA).

What happens when a company that sells robotically-assisted UKAs makes an assertion like this?

Our comprehensive research program provides evidence of the clinical and functional value of our robotic arm system for placement of corresponding implants.

What if the company publishes a chart that compares two-year survivorship rates, with an "author conclusion" that says:

Improved accuracy of implant placement achieved with robotic arm assisted UKA leads to superior implant survivorship and patient satisfaction.

Well, if there is someone knowledgeable watching, you get an article entitled  "Cherry Picking Clinical Nuggets," disputing the finding and the evidence behind it.

Implant survivorship at two-years is essentially, if not totally, meaningless.  Moreover, the data is inconsistent with comparable data sets and reflects outcomes from the most experienced MAKOplasty surgeons in the field.

The article continues by citing a published clinical review:

The authors reviewed clinical and radiographic data for matched cohorts who received robotic-arm assisted UKA or standard instrumentation UKA.  Among the findings cited in the abstract were the following:
  • Operative time was significantly longer in the robotic group.
  • There were very few differences between groups in postoperative clinical measures.
  • A greater number of robotic group patients reported continued medial-sided knee pain.
The authors concluded that there were little to no clinical or radiographic differences between the robotic and non-robotic groups and that the data suggested that “purported benefits of robotic UKA may be obviated in the hands of a surgeon with training and experience in manual UKA implantation.”

Does this sound familiar?

What happens to a company's stock price when a report like this comes out?


Anonymous said...

Actually that article came out in December. Nice chart, though. No correlation. MAKO went down today as did tech and other robotic stocks ie ISRG and HNSN. Today actually marked a great day, data-wise, for Mako Surgical as their long awaited 90 day post op data from a study being conducted at the Glasgow Royal Infirmary and the Unviersity of Strathclyde in Scotland. The data was compelling to say the least. It helps as well when your pavilion at AAOS 2013 is packed like today.

Paul Levy said...

The article was updated today.

Anonymous said...

The data about longer surgery times in all these robot-assisted cases is important, because longer surgery times correlate with, among other things, a higher risk of surgical infection. Ironic since we now consider surgical infections a medical error.....


Anonymous said...

To Anon 10:58,

And Paul generously left out of this post a section of the article that was sent out yesterday:

"What should not be ignored is the patently deceptive direct to consumer marketing campaign that is not supported by the data."

Kevin McNamara said...

As the author of the article referenced in Mr. Levy's post, I find the comment by 'Anonymous #1' amusing. I am certain that few, other than Anonymous, were waiting on '90 day post op data'. Using the 'dog year' analogy, 90 days is equal to 1 second in orthopedic time.

Moreover, 'More accurate placement' at 90 days means nothing; the latter is not my opinion – it is a fact. The press release states that poor implant positioning in UKA is associated with suboptimal functional outcome following surgery and cites a report by Collier et al.; Factors Associated with the Loss of Thickness of Polyethylene Tibial Bearings After Knee Arthroplasty (J Bone Joint Surg Am. 2007 Jun;89(6):1306-14). The study found that wear-related loss of thickness is influenced by mainly by ‘the shelf age of the polyethylene, the age of the patient, and the postoperative angulation of the knee in the coronal plane.’ This is good to know but there is no evidence that robotic arm assisted UKA results in superior functional outcomes. Remarkably, MAKO Surgical’s press release states the following: robotic arm technology provides more accurate and minimal bone resection . . . for improved post-operative function and kinematics (emphasis added). If MAKO Surgical already knows this, why is the study being conducted?

One must also question what 'considerably lower self-reported post-operative pain levels at six weeks' means. It is notable that the press release merely says that patients had considerably less pain. The press release does not state that patients in the MAKOplasty arm had considerably less pain compared to patients in OXFORD Partial Knee arm. We are left to speculate what percentage of patients in each arm had ‘considerably lower’ pain, what the term ‘considerably’ means, and whether the difference clinically significant.

On a separate note, Anonymous is correct in stating that the article cited by Mr. Levy was published in December. However, on March 20, 2013, we published a separate article, titled RESTORIS MCK Medial Onlay Superiority Claim - Anatomy of a Deceptive Direct to Consumer Robotic Surgery Marketing Campaign, which describes our views in considerably more detail.