Dr. Bose Discusses Computer Assisted Surgery for Hip Resurfacing

[Pat Walter]

Hi Pat,

Thanks for the mail.

Congratulation on the excellent work that you are doing.

Using computer navigation in  joint surgery is a double edged weapon. While potentially it can reduce the number of outliers,  it can also cause tremendous deviations and absurd placements which would never be done with conventional jigs. I have seen many examples of this done elsewhere and referred to me for revision surgery.

Generally the input to the computer is made by a technique known as bone morphing where the surgeon uses pointer probes to point out the various bony landmarks to the computer. If the surgeon makes an error in this step then it obviously carries on in all further steps leading to a faulty placement. To argue that it removes human  error is most irrational.

We have the brainlab navigation ( market leader in navigation)  in our unit since 2007 and I did a series of cases at that time ( about 80 cases) . I have to say that the femoral cap placement was inferior to my placement with traditional jigs. However I found it useful when one had distorted anatomy as in previous prox. femoral osteotomy. I still use it for such cases.

There are many reasons in my opinion by which the conventional jig is far superior to the navigation in hip resurfacing.

1. bone morphing with the pointer probes damages the neck capsule which I protect passionately during hip resurfacing surgery and which I am sure is one of the key elements for my success rate.

2. I  use navigation routinely  during my Total knee replacements as the aim of the TKR surgery is to allign the components to the hip and ankle which are not visible in the surgical wound. In contrast in hip surgery the goal is not to align hip component to the spine , pelvis or knee/ ankle. The aim is to align components to local landmarks in the surgical wound, the location of which is given to the computer by the surgeon.  Then the computer gives back the same information which the surgeon offered in the first place. ( this is unlike the TKR where the computer picks up the hip on merely moving the hip and not morphing). Arguments that the computer increases accuracy in hip surgery is frankly absurd and have to be dismissed as marketing techniques.

3. The concept of incorporating the  combined anterversion is now the key in operating on FAI ( Femoro- acetabular impingement) which is the pathology in over 95 % of male patients having primary osteoarthritis. This is a dynamic assessment and can be done only with a jig using a lat cortex pin and cannot be done with navigation.

Having said all of the above  one must make a distinction between what Prof. Cobb uses and what others use.

Prof . Cobb is the  only one to my knowledge who uses a CT based navigation. The CT gives information which the surgeon cannot access unlike imageless navigation with all other surgeons which depends on surgeon's input based on bone morphing that  defeats the whole purpose of navigation.

In conclusion I would like to say that imageless navigation has very limited role in hip arthroplasty ( eg previosely operated cases) and is an excellent tool in Knee arthroplasty.
CT based navigation for hips which is still not available commercially ( which prof. Cobb uses) may have a significant role in hip arthroplasty. This has to be balanced with the radiation dose for routine CT to be applied universally( approx 30 -50 conventional x-ray dose )

wishing you the very best

with best regards
vijay bose
chennai

[LOGAN13]

What Dr Bose writes hits the nail on the head. In a previous post of mine entitled Surgical alignment guide(Nov 30), I shared my dilemma. My surgeon is doing a study in which I have been asked to join...CT assisted surgery. The mention of the possibility of Cancer due to the level of radiation in which I would be exposed to from the CT scan concerns me.

I am pleased to read that Dr Bose suggests Ct assisted hip surgery in which Prof Cobb uses may have a significant role. The radiation still concerns me though. I will be discussing my concern with my surgeon at my pre-op appointment.

I hope that Ct assisted surgery passes with flying colours....this could be the link to having surgeons here in Ontario Canada close the gap of inexperience that exists today compared to the top surgeons around the world.

I hope to read more posts concerning Ct assisted surgery.

If you read this Toby...How is your recovery going?