When looking at the Total Knee Function score, which is one of the more sophisticated knee scores, the medial pivot knee data suggests better function in that group.
And if you look at the Forgotten Knee, which is what we’re really aiming for in our knee replacement patients, we’re seeing more forgotten knees in the medial pivot knees in this Level 1 prospective randomized study than we are in the standard knees.
We’ve learned something. They both do well. Let’s not say that the standard knees do badly. They both do extremely well. But the reality is we’ve seen some advantage in the medial pivot group.
I want to share with you some interesting data from Bill Walter who’s looked at another standard, very popular knee design (Triathlon CR) and compared it to a medial pivot design (SAIPH). He picked his best knees.
These are the ones that were really happy and then tried to look at their sagittal stability. The population numbers between the two groups are pretty similar. They’ve got good range of motion and good stability in terms of coronal alignment. And there’s much better sagittal stability both in the Lachman Test and in the Anterior Drawer for the medial pivot knee.
I think there are important conclusions to make here. The contributions that Chit has made to knee surgery have been immense and we got to a stage where we’ve got knee replacements working relatively well for the majority, but we probably didn’t set the bar high enough.
There are some patients who probably need to achieve more and want to achieve more, and that’s where sagittal stability through knee conformity might come in. It can give us the potential for better motion and better tracking and, hopefully, better function and higher satisfaction.
Dr. Ranawat: I’m going to show you where we are with the implants that we use. I’m going to present long-term results for the PFC Sigma Rotating Platform Posterior Stabilized (RPPS) total knee in young, active patients with no less than a 10-year follow-up.
The RPPS design was brought to the marketplace almost 15 years ago as an alternative to the LCS Meniscal Bearing knee design. It increased range of motion while also reducing polyethylene wear and, therefore, offering a potential for increased survivorship.
The objective of this presentation is to investigate long-term clinical and radiographic results and survivorship of the RPPS knee in young, active patients.
In 2000, I did 43 consecutive, cemented RPPS knees in 33 patients (21 males, 12 females). And followed them a minimum of 10 years; age between 35 to 65 with a mean of 59 years, and the functional criteria that we used was UCLA activity score. All patellae were resurfaced. Mean pre-operative UCLA score was 5.3. Mean pre-operative range of motion was 109 degrees. Clinical results were analyzed according to the Knee Society Score, range of motion, WOMAC and a patient-admission questionnaire (PAQ) which I designed and published in JOA in 2012.
Radiographic analysis was performed for loosening, osteolysis, and Kaplan-Meier survivorship—failure for all causes and failure for mechanical reasons.
At a mean follow-up of 11 years, the mean post-operative range of motion was 117 degrees. Knee Society and WOMAC mean scores improved dramatically to 94.1 and 32.9, respectively.
Ninety percent (30 patients) had good to excellent results. Ninety three percent (21 patients) were satisfied with a mean PAQ satisfaction score of 8.6 out of 10.
At 10 years, radiographic analysis showed there were no failures. One hundred percent survivorship for mechanical failure; and 98% survivorship for all causes as 2 patients required scar excisions.
So, we’re reporting 10-year results in young, active patients with a high quality of function including sporting activities. We attribute this to design features of the RPPS knee.
In conclusion, results appear to support RPPS TKA in the young, active patient. Many have almost 20-year follow-up; 90% good to excellent results; no osteolysis; 100% survivorship.
My point here is that new innovation is good. But the medial pivot design has been tried since the time of Michael Freeman, which goes back almost 30 years.
