Interesting Doctor Experience Medical Study

[Pat Walter]

Optimal acetabular cup positioning is attained in less than 50% of cases, study reports


This is an older study from 2010, but it points out the importance of using an experienced surgeon for both hip resurfacing and THR.

Link on Surface Hippy http://www.surfacehippy.info/experienced-vs-less-cup-placement-study.php



March 9, 2010

NEW ORLEANS - High-volume surgeons are more likely than low-volume surgeons to attain optimal cup positioning for total hip arthroplasty, but both groups still attain optimal cup positioning less than half of the time, according to a study presented here.

The findings were presented by Bryan Jarrett, BS, at the 56th Annual Meeting of the Orthopaedic Research Society.

Jarrett said the purpose of the study was to attempt to correlate the influence of various patient factors - body mass index (BMI), age, gender and primary diagnosis for the total hip arthroplasty (THA) - with the positioning of the acetabular cup.

"Cup positioning and implant positioning are extremely important to attain long-term success," he noted.

Methods and measurements

The researchers compiled data from 2,063 patients who underwent a primary THA, revision THA or Birmingham hip resurfacing from 2004 through 2008.
Postoperative anteroposterior (AP) pelvis and cross table lateral digital radiographs were obtained for each patient, and the AP radiographs were measured to calculate cup inclination and version angles. Version direction was determined through the lateral radiographs.

Acceptable angle ranges were defined as 30° to 45° for abduction and 5° to 25° for version.

Study results

There were 1,954 qualifying patients, with 1,218 (62%) acetabular cups falling within the optimal abduction range and 1,576 (87%) in the optimal version range. There were 921 (47%) patients with both inclination and version angles within the optimal ranges.

In the combined analysis, low-volume surgeons showed a 2-fold increase in risk for cup malpositioning compared with high-volume surgeons. Minimally-invasive surgery, as an approach, showed a 6-fold increase in risk for cup malpositioning when compared to the posterolateral approach. Obesity, defined as a BMI greater than 30, showed a 1.3-fold increase in risk.

Less than half

With patient influences taken into account, the high-volume surgeons outperformed their low-volume counterparts, but both still attained optimal ranges in less than 50% of patients.

"When we just looked at high-volume surgeons, 38% of the patients fell within the optimal ranges," Jarrett said. "When we just looked at low-volume surgeons, we saw that 26% of the patients were within the optimal ranges."

•Reference:
Callanan M, Bragdon CR, Zurakowski D, Rubash H. An analysis of cup positioning in total hip arthroplasty: quality improvement by use of a local joint registry. Paper 362. Presented at the 56th Annual Meeting of the Orthopaedic Research Society. March 6-9, 2010. New Orleans.

[Boomer]

Pat,

Thanks for posting the article.

The good resurfacing surgeons are using interoperative x-rays and even lasers to ensure they get the devices positioned almost perfectly. Plus, they have a Smith and Nephew guy in the room to help. There is no excuse for installing the devices at anything less than optimal angles or at worst, within an acceptable range. The top surgeons will show you afterward on the x-rays what the angles are. I just don't understand how a good surgeon who has been properly trained can miss the target half the time. I also don't understand why any patient would ever go to a surgeon who does not have a long and verifiable record of success with resurfacing.

You have done a wonderful job of educating the Newbies, but I still see a lot of them heading to inexperienced and relatively unknown resurfacing surgeons. We have a lot more work to do.

Thanks for hosting the site Pat.

Boomer

[Pat Walter]

I have watched them place the acetabular cups in both in videos and live surgery.  You can see if they just move a little bit off their target angle, they can miss the optimum angles.  Dr. Kusuma has his helper hold the tool while he taps with the hammer so he doesn't move the jig while using the hammer.  I have seen many other surgeons hold their own as they tap. Each has their own method to place the cup properly.  So it is definitely a process that takes skill and experience.  I can see why a less experienced surgeon can miss the optimum angle.

Many of these topics we talk about seem simple to us, but in reality they are very complex.  We have human surgeons needing to be on top of their game working on humans of which none are built exactly the same.  To me, it is amazing that they can end up with the excellent results that many do.

The message is still the same to all patients - no matter hip resurfacing or THR, you need to use a surgeon that does them all the time. Doing a few now and then does not keep them on top of their game. 

Pat

[ScubaDuck]

Interesting study but I don't get the math involved.

There were 47% of the patients that had both angles in optimal ranges.
38% of the patients operated on by high-volume surgeons had optimal ranges.
26% of the patients operated on by low-volume surgeons had optimal ranges.

Assuming that the study only had two classes of surgeons, low-volume and high-volume, then those numbers can't add up.

I am assuming they excluded some population of the patients when taking into account "patient influences."  So my assumption is that the 38% and 26% referred to a less than optimal subset of patients.

I find this synopsis very confusing and misleading.  Sensational headlines start by quoting study summaries such as this.  I wonder if I can find the full study somewhere.

Dan

[Pat Walter]

Original Link

http://www.orthosupersite.com/view.aspx?rid=61685

The reason I posted it was to help support the suggestion I make to use the most experienced hip surgeons you can, both in THR and Hip Resurfacing.

Pat

[Jimt]

Pat,

Hospital for special surgery posted a nice story on the history of bhr.   I am not sure how to Piet on here but thought you would be he one to do it, if it could be done.

Jim