Lateral Unicompartmental Knee Arthroplasty in Structure of Modern Knee Replacement: Is It «Woe From Wit» or a Viable Go-To Method?

Background. Results of numerous contemporary studies indicate that medial and lateral unicompartmental knee arthroplasty (UKA) are almost equally effective both in clinical and functional aspects with no statistically significant difference in most cases. Furthermore, both operations tend to reach the effectiveness of total knee arthroplasty (TKA), despite the common opinion that any UKA is a more complex and skill challenging surgery with a less predictable outcome. The purpose — to asses if UKA in the patients with end-stage lateral unicompartmental osteoarthritis is an effective surgical intervention that may allow obtaining good and excellent medium-term functional results, that are comparable to the results of the medial unicompartmental arthroplasty, and to see if there are any benefits in comparison to the total knee arthroplasty (TKA). Materials and Methods. 140 middle-aged and elderly adults with end-stage osteoarthritis underwent knee arthroplasty at Vreden National Medical Research Center of Traumatology and Cheboksary Federal Center of Traumatology, Orthopedics and Arthroplasty. Group I (lateral UKA) (the main ) consisted of 15 patients with knee arthritis and type I Krakow valgus knee deformity, who underwent the lateral UKA with a fixed all-polyethylene tibial component. Group II (medial UKA) included 58 patients with end-stage medial unicompartmental osteoarthritis, who underwent the medial UKA using an endoprosthesis of a similar design. Group III (TKA) was represented by 67 patients with gonarthrosis accompanied by type II Krackow valgus knee deformity, who underwent the total knee arthroplasty with cruciate retaining (CR) prosthesis. The comparison between the groups was carried out regarding the achieved range of motion, functional result (using Oxford Knee Score and Forgotten Joint Score), as well as the rate of different types of complications. Results. During the study, two main objectives were set. The first was to compare the outcomes of the lateral and medial UKA. It was revealed that the lateral UKA allowed the patients to obtain good function of the operated knee, with the best results among the compared groups on the Forgotten Joint Score. The second objective was to compare the results of the lateral UKA and TKA in the patients with type II Krackow knee valgus deformity. Here, our study revealed that the group of UKA (group I) compared to the TKA had better results according to Forgotten Joint Score (71.5±5.3 vs 65.2±7; p = 0.9) and had a slightly lower range of motion according to Oxford Knee Score (34.6±2.3 versus 35.9±2.2; p = 0.7). It is worth noting that in both cases the difference was not statistically significant. Conclusion. Despite the fact that the lateral UKA made it possible to achieve a good functional outcome, the integral score was the same as in the groups with the medial UKA and the total knee arthroplasty. The older patients were more satisfied with the results of the partial arthroplasty than with the results of the total.