Lee v. Lombardi Over Patient Specific Instrumentation

“The data does not support the use of patient specific instrumentation (PSI), ” says Gwo-Chin Lee. “Claims of decreased operative time and improved alignment are unfounded.” Adolph Lombardi states, “The majority of studies DO show decreased processing and sterilization time, turnover time, etc. And hey, these things could soon be delivered to your OR by drone.”

This week’s Orthopaedic Crossfire® debate was part of a landmark event, the first Brazilian CCJR meeting. The event, which took place in September 2014, was held in Iguassu Falls. This week’s Orthopaedic Crossfire® debate is “Patient Specific Cutting Blocks: Of Unproven Value.” For the proposition is Gwo-Chin Lee, M.D. of the University of Pennsylvania. Against the proposition is Adolph Lombardi, M.D. of Mt. Carmel New Albany Surgical Hospital. Moderating is Leo Whiteside, M.D. of the Missouri Bone and Joint Center.

Dr. Lee: “Patient specific instrumentation employs advanced imaging to generate patient specific cutting guides. The proposed advantages include decreased operative time, reduced operative cost, and the potential improvement of overall alignment.”

“Over the last few years there have been several studies published on this subject, with mixed results. Part of the problem has been limited sample sizes and therefore, limited power. Until recently there were no systematic reviews or meta-analyses.”

“Our goal was to look at whether these instruments restored coronal or sagittal alignment, what their influence was on operative time, blood loss, transfusion requirements, and perioperative cost. For our meta-analysis our inclusion criteria were: comparative studies on Level 1, 2, and 3 randomized controlled trials (RCTs) on outcomes such as alignment, operative time, blood loss, transfusion, and cost. So this means that review articles, technique articles, and editorials were excluded.”

“We narrowed it down to nine studies: aggregated total knees (957…428 using standard instrumentation and 529 using patient-specific guides). In terms of coronal alignment, these were analyzed based on postoperative CTs. We obtained standardized rotation with posterior augment holes of the posterior condyles to ensure that the rotation was standardized. We also measured the reported femorotibial angle and the hip-knee-ankle angle.”

“When comparing patient specific instrumentation and standard instrumentation for coronal alignment, the former was slightly more accurate at restoring the femorotibial angle. But for the hip-knee-ankle angle, patient specific instrumentation lags slightly behind standard instrumentation. When evaluating coronal alignment in terms of percentage of outliers, i.e., those outside the three degree of target, there was no significant difference between the two technologies…and no significant difference between the two technologies when you measure hip- knee-ankle radiographs.”

“Sagittal alignment: there were only two studies at the time that reported it, including one with 162 knees (no significant difference found between the two groups). On the tibial side, there were three studies that reported on alignment—again, no significant difference between the two groups.”

“Operative time…no significant difference was found between the two groups. Regarding estimated blood loss and transfusion requirements, there were no significant differences. A study from Washington University in St. Louis looked at perioperative cost and found a savings of $322 per case with patient specific instruments as a result of decreased OR time and sterilization time. But if you account for the cost of the cutting guides (around $950 per piece) and preop MRI and CT scans (from $400-$1, 200 depending on the institution), then the patient specific instrumentation is actually less expensive for the hospital, but may be more expensive for the healthcare system.”

“If you consider the aggregated results in terms of alignment…looking at coronal alignment, patient specific instrumentation was superior. Regarding coronal alignment in terms of hip-, knee-, ankle radiographs, i.e., restoring the mechanical axis, then standard instrumentation was superior. There was no difference in sagittal alignment, operative time, and estimated blood loss or transfusion requirement. PSI provided a savings if you could achieve high enough volume to accrue those savings. But for costs to the healthcare system standard instrumentation was most cost effective.”

“So the proposed advantages of PSI are decreased operative time—not found to be true…reduced perioperative costs—not found to be true…improved alignment—not true. Thus, current data does not support the routine use of PSI in primary TKA. However I do admit that there are limitations of the literature.”

Dr. Lombardi: “I do think PSI has value and here is why. It has a two decade history. It started off with Radermacher in 1994, Materialise had their Mimics and Magics software, which is used to create all the 3D images that used CT scans. It is based on rapid prototyping technology, which is used for the triflange type of acetabular reconstruction; there is ample literature showing that these do very well and can bail you out in very difficult situations.”

“All major orthopedic (and other) companies are selling these guides. They are either based on CT or MRI—or you can marry an MRI and a long alignment film. Some are cut through guides, while others are positioning guides.”

“It facilitates your preoperative planning; you can choose sizes, rotation…you can actually do the operation before you get to the operating room. For the less experienced surgeon it makes you think about what you’re going to do. There isn’t a considerable learning curve.”

“The majority of time studies show that there’s decreased operative time, decreased processing and sterilization time, turnover time, OR time, number of trays used, and ultimately, reduced hospital stay. It requires less instrumentation, resulting in less OR setup and breakdown, and a decrease in the number of the instruments required to be processed in a sterile fashion.”

“PSI doesn’t violate the intramedullary canal and doesn’t require the use of pins. And it is very useful in patients with extra articular deformity or retained hardware. And patients like that you’re going to get a preop CT or MRI, look at their anatomy, and make a jig that is going to fit them.”

“It definitely offers an advantage to lower volume surgeons. A paper by Johnson said that the primary drivers of increased surgical time for lower volume surgeons is a significant number of steps…and that when you use these jigs it eliminates as many as 80 instruments. In addition, it has been associated with significant improvement in Knee Society Functional Scores in some short term follow up studies.”

“If you perform three TKAs in a day and you save approximately 20 minutes per case (which is what those papers say you can save) then what is the value of one hour of your time? Also, it is being increasingly used around the world. An article by Thienpont shows that global utilization of PSI has increased from 2011 to 2012 for all manufacturers.”

“Right now we have all these people involved: the distributor, the rep, the sub-rep, etc. Mont did a study showing that there was a significant decrease in this preop work when you have these prepackaged devices. So I think these single use cutting blocks—along with the patient specific guides and implants—will be delivered to your OR by drone.”

Moderator Whiteside: “Gwo, your rebuttal?”

Dr. Lee: “I don’t put in glenoids nor total ankles, so these instruments aren’t useful for me. These should only be looked at as instruments and not a way of performing a total knee. And yes, a computer can hit the target a bit more accurately than a human being with a jig and conventional instrumentation. But we don’t know what the optimum target is for anybody. Are we ready for that technology at this point?”

Moderator Whiteside: “Have you seen any significant clinical downside of using patient specific instrumentation?”

Dr. Lombardi: “I tell everybody that this is a jig and it adds to your armamentarium. No matter which jig I’m given I have to make sure that it’s consistent with what I am seeing on the X-ray and what I’m seeing clinically. I have changed rotation intraoperatively where I didn’t agree with where the jig was putting me, but I’m not sure I was right. I haven’t done these sophisticated studies with a postop CT on these patients and see what the rotation is. There are two studies out there looking at postoperative rotational alignment. If you agree that the transepicondylar is the correct rotational alignment and they’ve shown that indeed, patient specific guides are accurate.”

Moderator Whiteside: “What percentage of the time have you actually jettisoned the gear and gotten out your old instruments?”

Dr. Lombardi: “When I first started doing them I did them both with intramedullary (IM) rod and these jigs because I wasn’t sure. After I got comfortable—which was after about 20 of them—I’ve not used an IM jig since then. The technology was brand new and I wasn’t sure that it was accurate. I wanted to make sure that I was getting the alignment consistent with my jigs.”

Dr. Lee: “The handful of times that I’ve used it have been in cases where the patient had retained hardware or the IM canal was obliterated from previous trauma. In those cases these jigs have served as a very expensive distal femoral cutting guide and proximal tibial cutting guide. I don’t think that they’re accurate in terms of rotation.”

Moderator Whiteside: “In what percentage of the cases in your institution do they abort use of these custom guides?”

Dr. Lee: “Our institution never really embraced these instruments, but Chris Peters has a good study showing that he overrode in over 50% of the time.”

Moderator Whiteside: “Adolph, it sounds like a significant loss of time and money.”

Dr. Lombardi: “If we look at Chris’ study, the most significant change he made was to downsize the femoral component. So he was accepting the plan with a larger femoral component and then putting a jig on and cutting with that. I don’t see that as an issue. It takes one second to take the cutting block off and put the smaller one on. You’ve got to look at the plan preop.”

Moderator Whiteside: “Thank you, gentlemen.”

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