To sacrifice or replace the posterior cruciate ligament in primary total knee arthroplasty?

Mid-Term Clinical and Radiological Results at a Tertiary Care Hospital in Türkiye: Is Residual Varus Really Important After Mechanically-Aligned Total Knee Arthroplasty?

INTRODUCTION

 Traditionally, in total knee arthroplasty (TKA), it is aimed to keep the mechanical axis of the lower extremity neutral (mechanical alignment: 3° varus-valgus in the coronal plane) to improve long-term outcomes. This study aimed to assess the mid-term radiological and clinical results of patients with postoperative residual varus (more than 3° of varus) after mechanically-aligned TKA.

METHODS

A total of 616 individuals who had undergone TKA for primary knee osteoarthritis between 2008 and 2013 in our tertiary care hospital were retrospectively examined. All TKAs were performed with the mechanical alignment strategy. For radiological evaluation, hip-knee-ankle (HKA) angle, knee alignment angle (KAA), mechanical medial proximal tibial angle (mMPTA), knee inclination (KI), joint line orientation angle relative to ground (JLOA-G), posterior tibial slope (PS), joint line convergence angle (JLCA) were measured. Besides, patients' latest radiographs were screened for any clue of aseptic loosening or mechanical failure. Knee Society Score (KSS) (knee and functional subgroups), and Lysholm, Oxford, and Tegner scores were used for clinical evaluation. In addition, knee flexion and extension limitations were assessed.

RESULTS

After applying the exclusion criteria, a minimum of five-year follow-up result of 110 patients was demonstrated. There were 101 females (92%) and nine males (8%). The mean follow-up time was 65.8 ± 6.3 months (range: 60.8-75.8 years). The mean age was 65.9 ± 7.7 years (range: 39 to 89 years). The preoperative mean mechanical axis angle of the lower extremity was 17.3° ± 7.8° (range: 13.4-43.9°), whereas it was 8.3° ± 3.6° (range: 3.2-19.8°) postoperatively. The preoperative mean flexion angle was 90.7° ± 23.8° (range: 40-130°), and the extension limitation was -2.5° ± 7.4° (range: -40-0°), whereas, postoperatively, they were 102.8° ± 15.4° (range from 40° to 150°) and -3.7° ± 7.5° (range from -40° to 0°), respectively. The latest follow-up's mean KSS knee subgroup was 67 ± 18.4 (range: 12-93), the mean KSS functional subgroup was 74 ± 23.6 (range: 20-100), the mean Lysholm score was 81.7 ± 15.7 (range:25-100), the mean Tegner score was 3.65 ± 0.99 (range: 1-5), the mean Oxford score was 37.4 ± 6.5 (range: 9-48). There was no patient with aseptic loosening or mechanical failure.

CONCLUSIONS

In the mid-term follow-up of patients with residual varus after mechanically-aligned TKA, satisfactory clinical and radiological results were obtained without aseptic loosening or implant failure.

A comparison of SanatMetal Sanat Swing and Zimmer NexGen® total knee implants: 10-year postoperative follow-up results

Objectives

In this study, we present our 10-year postoperative follow-up results of Sanat Swing® and NexGen® total knee implants.

Patients and methods

A total of 189 patients (93 males, 96 females; mean age: 68 years; range, 48 to 86 years) who underwent total knee replacement between January 2008 and September 2010 were retrospectively analyzed. A total of 105 patients (Group A) were implanted a cemented Sanat Swing knee prosthesis and 84 patients (Group B) were implanted a cemented NexGen knee prosthesis. Operation time, range of motion (ROM), pain level, Knee Society Score (KSS), distance of painless walking, and the ability to climb stairs were evaluated between the groups.

Results

The mean follow-up was 10.8 (range, 9.8 to 12.3) years. No significant difference was observed in the survival of the prostheses, ROM, pain level, KSS, walking distance, and in the ability to climb stairs between the two groups at 10 years. With an experienced team, the operation time was about 4 to 5 min shorter in the Sanat Swing implantation group. In selected cases, Sanat Swing was superior to the NexGen system; however, there was no statistically significant difference. Complication rates were also low and comparable between both groups.

Conclusion

Based on the 10 years of follow-up evaluation, Sanat Swing total knee replacement system seems to yield comparable clinical results with the NexGen. Experiences with the operative technique and comparative evaluation, the Sanat Swing system is a safe and reliable alternative for total knee replacement, providing a user-friendly operative technique and shorter operation time.