Ten-Year Follow-Up of High-Flexion Versus Conventional Total Knee Arthroplasty: A Matched-Control Study

A high-flexion design total knee prosthesis: a ten to twelve-year follow-up study

BACKGROUND

The purpose of this study was to investigate the clinical and radiographic outcomes and to determine the survivorship of a high-flexion design total knee arthroplasty (TKA) prosthesis, the LOSPA knee system, over a follow-up period of 10-12 years.

METHODS

The study included 386 patients (503 TKAs) who were treated with TKA from 2011 to 2013 (follow-up period 10-12 years).The patients were assessed clinically using range of motion (ROM) of the knee, the Knee Society scoring system (KSS), and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). For radiographic analysis, the positions of femoral and tibial implants as α, β, γ, and δ angles, hip knee ankle (HKA) angle, and radiolucent lines were used. Kaplan-Meier survival analysis was performed.

RESULTS

Mean ROM improved significantly from the preoperative baseline of 117.3° to 126.5° at the final follow-up (p < 0.001). The mean KSS and WOMAC scores also both showed significant improvement after surgery (all p < 0.001). A non-progressive radiolucent line less than 2 mm was observed in 23 cases (4.7%). Nine patients underwent revision surgery on the knee during the follow-up period. Revision surgery was performed on four patients due to aseptic loosening, three patients due to infection, one patient due to ankylosis, and one patient due to instability. When the endpoint of survival was the entire surgical cases, the survival rate was 96.2%. The survival rate, with revision for any reason as the endpoint, was 97.2%, and 97.8% for aseptic causes.

CONCLUSIONS

The LOSPA knee system, a high-flexion design total knee prosthesis, showed excellent long-term survivorship and improvements in clinical outcomes at 10- to 12-year follow-up.

Does mild flexion of the femoral prosthesis in total knee arthroplasty result in better early postoperative outcomes?

BACKGROUND

The purpose of this study was to measure the femoral prosthesis flexion angle (FPFA) in total knee arthroplasty (TKA) using three-dimensional reconstruction, and to assess the differences in early clinical efficacy between patients with different degrees of flexion.

METHODS

We conducted a prospective cohort study. From June 2019 to May 2021, 113 patients admitted for TKA due to osteoarthritis of the knee were selected. The patients' postoperative knee joints were reconstructed in three dimensions according to postoperative three-dimensional computed tomography (CT) scans. The FPFA was measured, and the patients were divided into 4 groups: anterior extension group (FPFA < 0°), mildly flexed group (0° ≤ FPFA < 3°), moderately flexed group (3° ≤ FPFA < 6°) and excessively flexed group (6° ≤ FPFA). The differences in the Knee Society Score (KSS), knee Range of Motion (ROM), and visual analogue scale (VAS) scores were measured and compared between the four groups at each postoperative time point.

RESULTS

Postoperative KSS, ROM, and VAS were significantly improved in all groups compared to the preoperative period. At 1 year postoperatively, the ROM was significantly greater in the mildly flexed group (123.46 ± 6.51°) than in the anterior extension group (116.93 ± 8.05°) and the excessively flexed group (118.76 ± 8.20°) (P < 0.05). The KSS was significantly higher in the mildly flexed group (162.68 ± 12.79) than in the other groups at 6 months postoperatively (P < 0.05). The higher KSS (174.17 ± 11.84) in the mildly flexed group was maintained until 1 year postoperatively, with a statistically significant difference (P < 0.05). No significant difference in VAS scores was observed between groups at each time point.

CONCLUSIONS

A femoral prosthesis flexion angle of 0-3° significantly improved postoperative knee mobility, and patients could obtain better Knee Society Scores after surgery, which facilitated the postoperative recovery of knee function.

TRIAL REGISTRATION

ChiCTR2100051502, 2021/09/24.

Ten- to 14-Year Results of a High-Flex Rotating Platform Knee Implant: A Follow-Up Report of a Prospective Cohort

BACKGROUND

High-flex posterior stabilised rotating platform (PSRP) implant was introduced to provide for deep knee flexion. Few short-term results have been reported, but there are no long-term outcomes reported.

METHODS

We prospectively followed 48 patients (53 knees) implanted with one such design. Inclusion criteria for implantation were patients with good pre-operative flexion and wishing to perform activities requiring deep knee flexion post-operatively, with femorotibial varus angle < 15° and having good flexion stability at trialling stage. Previously, we reported their outcomes at 2-6 years (FU-1). We now report their functional and radiological results at a minimum follow-up of 10 years (FU-2) in 39 patients (43 knees); 5 patients having died and 4 lost to follow-up.

RESULTS

The mean pre-operative flexion of 124° improved to 130° at FU-1 and to 134° at FU-2. Flexion of 130° or more was seen in 59.6% knees at FU-1 and 74.42% knees at FU-2. At FU-2 mean Knee score was 90.5 and Function score was 67.8. Incidence of patellofemoral symptoms increased from 7.7% at FU-1 to 11.36% at FU-2. There were no cases of bearing spin out, osteolysis or revision surgeries.

CONCLUSION

At a minimum 10-year follow-up, high-flexion PSRP design in selected patients yielded 100% survival. We recorded good knee flexion and knee society scores, with no case of spin out, implant loosening, osteolysis or revision surgery. Although deep knee flexion improved at longer follow-up, its use in ADL had reduced due to other age-related factors. There was increased incidence of patellofemoral symptoms.