Introduction
Since its introduction UKA encountered severe criticisms, but also enjoyed unquestionable advantages.
Criticisms: Lower survival rate when compared to Total Knee Arthroplasty (TKA); not reproducible and not predictable results too much “surgeon-related”; Narrower indications, therefore lower cases volume Vs TKA; Longer learning curve; It’s still considered a temporary treatment.
Advantages: Minimal invasivity, therefore low morbidity; fast and easy functional recovery, with the possibility to return to sport activities (Sky, Tennis, Golf etc.) ; Easier revisions; Higher patient satisfaction Vs TKA; higher performance results.
Aim
OF THE PAPER: verify the chances to reduce UKA disadvantages, enhancing its positive features and making its survival curve similar to TKA one. In order to do so we employed an implant that followed all Dr. P. Cartier indications (Implants orthogonality; resurfacing; Cartier angle respect), together with an instrumentation able to make surgical steps reproducible and reliable.
Materials And Methods
We compared the results obtained in two studies on different implants and instrumentations, employing the Knee Society Score (KSS) and the implants survival curve.
Group 1 636 patients operated between January 1st 1997 and December 31st 2010. 364 Patients were females while 272 were men. The group received 676 implants as in 40 cases we performed bilateral implantations; average age was 70,4 years (Min. 46y; Max 91Y); 415 patients had a diagnosis of primitive gonarthrosis, 92 necrosis, 22 post-traumatic , and 111 meniscectomy outcomes. Average follow-up was 7.2 years (Min. 1y; Max 13y). Average pre-op KSS score was 84,9 (±6.9), while the average Post-op KSS score was 157.4 (±4.3). Patients were all between generally satisfied and very satisfied. Survival curve showed a revision rate of 2.5% during the first 3 years, followed by a stabilization (flat survival rate) until 10 years F.U. and then by a further decrease of 2.5%.
Group 2 102 UKA implanted on 96 patients (we performed bi-lateral surgeries in 6 cases), operated between May 1st 2010 and July 31st 2014. 49 patients were female and 46 were males. Average age was 70 years (Min. 46y; Max 91y). Follow-up ranged between 6 months and 3 years.
Results
We compared the results obtained in the two groups during the first three years Post-Op. We found that Performance results and patients satisfaction were comparable between the two groups. The learning curves however were not at all similar. Group 2 in fact did not show any survival rate decrease during the first three years.
Conclusions
UKA aims should be performance results and patient satisfaction, without having the survival curve penalized by early failures due to longer learning curve and poor surgical reproducibility.The employment of an implant design incorporating Dr. P. Cartier principles together with an instrumentation able to make surgical technique reproducible and results predictable, lead to the disappearance of the survival rate decrease seen during the first 3 years post-op keeping patient satisfaction unchanged.