Navigation systems that increase alignment accuracies of the lower limbs have been applied widely in total knee arthroplasty and are currently being adopted for minimally invasive UKA (MIS UKA) with good alignment results. There is little debate that when compared with total knee arthroplasty (TKA), UKA is less invasive, causes less morbidity, better reproduces kinematics, and therefore offers quicker recovery, better range of movement and more physiologic function. However, despite improved alignment accuracies, advantages of use of navigation system in UKA in clinical outcomes and survivals are still debatable. To the best of our knowledge, no reports are available on the long-term results after UKA performing using a navigation system. The purpose of this prospective study was to compare the radiological, clinical, and survival outcomes of UKA that performed using the navigation system and using the conventional technique at average 8 years follows up.

Between January 2003 and December 2005, Total of 98 UKAs were enrolled for this study, 56 UKAs in the navigation group and 42 UKAs in conventional group were included in this study after a average 8 years follow-up. At the final follow up, the radiological measurements with regard to the mechanical axis, the inclination of the femoral and tibial components, and radiolucent line or loosening were evaluated and compared between two groups. The clinical evaluations were performed using range of motion, Western Ontario and McMaster Arthritis index (WOMAC) scores and Knee Society (KS) score.

Of the 98 patients (98 UNI knees), 2 (2.0%) had died at a mean 5.8years after surgery because of cardiovascular disease, 3 (3.1%) underwent revision surgery that 1 cases of periprosthetic stress fractures in medial tibial plateaus in the navigation group and a case of tibial component loosening and polyethylene wear in conventional groups were observed. At a final follow up, the mean of mechanical axis was statistically different between two groups (2.7 vs. 3.9 of varus). And there were significant difference between 2 groups in terms of the mean values (p=0.042) for the tibial component coronal alignment, mean coronal alignments of tibial components were 89.1 ± 2.4° in the NA-MIS and 87.6 ± 1.8° in the MIS group, however outlier result were similar in the 2 group (5 and 5 knees, respectively, p=0.673). Sagittal alignments of femoral and tibial component were similar in the two groups (p>0.05) Significant differences were found in WOMAC or HSS knee scores, in which, stiffness did not show any difference between two groups, but pain and function showed difference at the last follow-up. The mean knee flexion has improved from 135.0 ± 14.8° and 135.0 ± 14.1° preoperatively to 137.1 ± 6.5° and 136.5 ± 7.2° in the NA-MIS and MIS groups on the latest follow-up, which was not significant different (p=0.883). The navigation system in UKA can provide improved alignment accuracy. And better clinical outcomes in pain and HSS score compared with conventional technique after a average of 8 year follow-up.

We undertook this study to compare the flexion stabilities, the clinical outcomes, and complications in cases of TKA using either the robotic technique (ROB-TKA) or navigation-assisted technique (NA-TKA).

Robot group (53 knees) and navigation group (56 knees) that underwent TKA for osteoarthritis were assessed for varus and valgus laxity at 90° of knee flexion after a minimum three-year follow-up. These evaluations included KS, WOMAC scores, and ROM. To evaluate flexion stability, varus and valgus laxities at 90° of knee flexion were measured using stress radiographs.

KS and WOMAC scores were significantly improved at last follow-up. However, no significant difference was found between the ROB-TKA and NA-TKA groups for any clinical outcome parameter. No significant intergroup differences were found in mechanical axis or coronal alignments and the mean varus laxities. No significant difference was found for varus-valgus imbalance at 90° of knee flexion. Complications differed in the two groups but none of the cases were severe enough to warrant a revision.

Both robotic and navigation assisted TKAs were found to restore good coronal leg and prosthesis alignments and good flexion stabilities. However, clinical knee scores and flexion stabilities were no better in short term for robot assisted TKA than for navigation assisted TKA.

The purpose of this study was to compare the laxity, radiological and clinical outcomes of TKA that performed using the navigation system and using the conventional technique at least 10-year follow-up.

47 navigational TKAs and 45 conventional TKAs were included for this study. Varus-valgus laxities were measured on the stress radiographs. The radiological measurements with regard to the mechanical axis, the inclination of the femoral and tibial components, femoral posterior condylar off-set difference and radiolucency were compared. The clinical evaluations were performed using ROM, WOMAC and KS score.

There was no significant difference in the total laxity. However, more than 10° of total laxity was significantly reduced in the navigation group (1 knee in the navigation group and 6 knees in the conventional group). The mean of mechanical axis was not statistically different between two groups. But, the outlier numbers of mechanical axis in the two groups was significantly different. The difference in ROM was not observed between the two groups. HSS, WOMAC, KS scores were significantly better in the navigation group.

The navigation system can provide good stability, improved alignment accuracy of the lower extremity and better clinical results compared with conventional technique.

The purpose of this study was to compare intraoperative varus-valgus laxities in total knee arthroplasty [TKA] using either a single-radius femoral design or multi-radius femoral design.

56 TKAs were performed by using a single radius femoral design (Scorpio NRG, SR group) and 59 TKAs were performed by using a multi-radius femoral design (Zimmer NexGen, MR group), both with a minimum of 1-year follow-up. We compared intra-operative varus-valgus laxities at 0°, 30°, 60°, 90° of flexion using the navigation system (Orthopilot, Aesculap, Tuttlingen, Germany). A series of clinical outcomes were evaluated at the time of the latest follow-up including HSS, WOMAC, VAS score during stair climbing.

At 30°, 60° of flexion, the mean total varus-valgus laxities in SR group (6.2 ± 3.5° at 30° of flexion and 6.8 ± 1.5° at 60° of flexion) were significant less than those in MR group (9.2 ± 4.3° at 30° of flexion and 8.3 ± 3.8° at 60° of flexion) (p=0.027 and p=0.042, respectively). In the clinical results, there was not significant difference.

The single-radius femoral designs for TKA showed evidently less intra-operative mid-flexion stability compared with the multi-radius femoral design. However clinical outcomes revealed no other significant dissimilarity on HSS, WOMAC and VAS scores during stair climbing.

We hypothesised that the excellent alignments achieved in UKA using a navigation system(NA-MIS UKA) would improve mid-term clinical results versus UKA without a navigation system(MIS-UKA). The clinical results and the component alignment accuracies of NA-MIS UKA and MIS UKA were compared after a minimum follow-up of five years.

56 UKAs in the navigation group and 42 UKAs in conventional group were included. The radiological measurements with regard to the mechanical axis, the inclination of the femoral and tibial components, and radiolucent line or loosening were evaluated and compared between two groups. The clinical evaluations were performed using ROM, WOMAC, HSS and pain score.

A significant inter-group difference was found in terms of WOMAC or HSS, pain scores. In the sagittal inclination of the femoral and tibial components, radiolucent line, there were no statistical differences between two groups. However, the outlier numbers at mechanical axis, the mean of coronal inclination of the femoral and tibial component in the two groups was significantly different.

The navigation system in UKA can provide improved alignment accuracy of the lower extremity, also there were significant differences in functional outcomes after 5 year-follow-up.