Mobility of the rotating platform in low contact stress knee arthroplasty is durable

Evaluating two implant designs in patients undergoing primary total knee arthroplasty using a novel measure of early optimal recovery: a retrospective observational study

PURPOSE

Quality of care in total knee arthroplasty (TKA) between implants was assessed using a novel composite outcome measure, early optimal recovery (EOR), to indicate ideal clinical outcomes and minimal healthcare resource utilization.

METHODS

Patients that underwent primary TKA in the study group (ATTUNE® Knee System) or control group (LCS® COMPLETE Knee System) were included in this retrospective, single-center study. EOR was defined as no complications, no readmissions, no extra outpatient visits, ≤ 48 h length of hospital stay (LOS), and restored range of motion and pain perception at 3-month follow-up. Multivariate logistic regression was used to compare EOR between the study and control groups. Results were adjusted for differences in baseline characteristics and are presented with 95% confidence intervals (CI). Data were collected from a specialized clinic for elective surgeries in the Netherlands, between January 2017 and December 2020.

RESULTS

A total of 566 patients (62.4% female, mean age 67 years) were included for analysis; 185 patients (32.7%) underwent TKA in the study group. Compared to the control group, patients in the study group had greater probability of achieving EOR (65.8% [95% CI: 55.1-75.2] vs. 38.9% [95% CI: 32.8-45.3]; p < 0.001), a LOS ≤ 48 h (77.2% [95% CI: 67.7-84.5] vs. 61.4% [95% CI: 54.7-67.7]; p < 0.05), and ideal pain perception at 3-month follow-up (93.3% [95% CI: 85.7-97.0] vs. 78.2% [95% CI: 71.0-83.9]; p < 0.05).

CONCLUSION

The study group was associated with a greater probability of achieving EOR versus the control group, suggesting improved quality of care.

Mobile medial pivot (lateral slide) type total knee arthroplasty exhibits a medial pivot pattern: three-dimensional motion analysis using cadaveric knees

PURPOSE

The purpose of this study was to analyze the dynamic kinematics of the mobile medial pivot-type total knee arthroplasty (MMPTKA) using the three-dimensional (3D)-to-2D registration technique.

METHODS

Cadaveric knees from five humans were used. Computed tomography of the lower limb and preoperative 3D planning for MMPTKA were performed. After performing TKA, passive motion of the knee was observed from a fully extended position to maximum flexion using a flat panel detector. The following parameters were determined: (1) anteroposterior (AP) translations of the medial and lateral most distal points (estimated contact point) of the femoral component, (2) rotational femoral component's X-axis (FCX) angle, and (3) rotational insert angle. Paired t-tests were used to analyze differences in the AP translation between the medial and lateral most distal points of the femoral component as well as differences in the changes in the rotational angle between the FCX and X-axis of the insert on the tibial component's axial plane.

RESULTS

The AP translations of the femoral component's medial and lateral most distal points were 8.4 ± 2.5 and 13.6 ± 3.3 mm, respectively (p = 0.001). The rotational angles of the FCX and insert were 10.7° ± 4.9° external rotation and 8.9° ± 4.1° internal rotation, respectively (p = 0.004).

CONCLUSIONS

The posterior translation of the lateral side of the femoral component was greater than that of the medial in all cases. Hence, a medial pivot pattern was identified. The femoral component exhibited external rotation throughout knee flexion in all subjects, whereas the mobile insert exhibited internal rotation (opposite pattern relative to the femoral component). This study provides valuable kinematical information of MMPTKA that has not been clear yet.

Mid-term clinical and radiological results do not differ between fixed- and mobile-bearing total knee arthroplasty using titanium-nitride-coated posterior-stabilized prostheses: a prospective randomized controlled trial

PURPOSE

This study was performed to prospectively compare the clinical and radiographic results between mobile-bearing (MB) and fixed-bearing (FB) TKAs using ceramic titanium nitride (TiN)-coated prostheses.

METHODS

Seventy MB and 70 FB TKAs using TiN-coated prostheses (ACS^®) were prospectively evaluated. There were no differences in demographic characteristics between the two groups. Clinically, the Knee Society knee and function scores, WOMAC, and range of motion (ROM) were compared. Considering the possibility of a kinematic change in the polyethylene (PE) insert and a decrease in ROM following MB TKA, serial changes in the ROM were also compared. The thickness of the PE insert was compared according to the size of the femoral component. Radiographically, the alignment and positions of the components were compared.

RESULTS

There were no differences between the two groups in clinical scores or ROM (n.s.). The maximum flexion increased from 133.5° ± 8.3° to 137.6° ± 5.5° across all time points in the MB group. The serial maximum flexion angles did not differ between the two groups over time (n.s.). The average thickness of the PE insert was greater in the MB group (12.0 ± 1.9 vs. 11.2 ± 1.6 mm, respectively, p = 0.008), especially when a large femoral component was used (12.7 ± 1.9 vs. 11.0 ± 1.5 mm, p = 0.005). The pre- and postoperative mechanical axes and positions of the components did not differ between the two groups (n.s.).

CONCLUSIONS

TiN-coated MB TKA showed no significant advantage over FB TKA. The selection of bearing design would be clinically insignificant when using the TiN-coated TKA prosthesis.

LEVEL OF EVIDENCE

II.