Medial-pivot design total knee arthroplasty provides higher post-operative patient satisfaction than posterior-stabilized design under mechanical alignment

Sho Masuda; Yukihide Minoda; Hideki Ueyama; Yohei Ohyama; Ryo Sugama; Hidetomi Terai

doi:10.1002/ksa.70111

Medial-pivot design total knee arthroplasty provides higher post-operative patient satisfaction than posterior-stabilized design under mechanical alignment

Knee Surg Sports Traumatol Arthrosc. 2025 Oct 27. doi: 10.1002/ksa.70111. Online ahead of print.

Authors

Sho Masuda¹, Yukihide Minoda¹, Hideki Ueyama¹, Yohei Ohyama², Ryo Sugama¹, Hidetomi Terai¹

Affiliations

¹ Department of Orthopaedic Surgery, Osaka Metropolitan University Graduate School of Medicine, Osaka-city, Japan.
² Department of Orthopaedic Surgery, Osaka Rosai Hospital, Sakai-city, Japan.

PMID: 41144735
DOI: 10.1002/ksa.70111

Abstract

Purpose: Numerous studies have compared post-operative patient-reported outcome measures (PROMs) between medial-pivot design total knee arthroplasty (MP-TKA) and posterior-stabilized design TKA (PS-TKA); however, whether MP-TKA demonstrates superior outcomes remains controversial. This study aimed to compare post-operative PROMs between MP-TKA and PS-TKA under mechanical alignment, using implants from the same manufacturer to eliminate the influence of shape, thereby focusing solely on the differences in articular surface design.

Methods: A total of 141 TKAs from the same manufacturer were retrospectively assessed, comprising 71 MP-TKAs and 70 PS-TKAs. Knee range of motion and PROMs, including the Knee Society Score-2011 (KSS-2011) and Forgotten Joint Score-12 (FJS-12), were evaluated at 3, 6 and 12 months post-operatively and annually thereafter, and compared between the MP-TKA and PS-TKA groups. The mean follow-up period was 51 ± 13 and 50 ± 17 months in the MP-TKA and PS-TKA groups, respectively (p = 0.535).

Results: The post-operative knee flexion angle was smaller in the MP-TKA group than in the PS-TKA group (124 ± 13 vs. 132 ± 13, p < 0.001). However, the change in knee flexion angle from the preoperative values between the two groups (5 ± 15 vs. 6 ± 15, p = 0.752) showed no difference. Compared with the PS-TKA group, the MP-TKA group showed higher KSS-2011 scores for symptoms (22 ± 3 vs. 19 ± 6, p = 0.002), satisfaction (32 ± 8 vs. 28 ± 10, p = 0.020) and functional activities (79 ± 16 vs. 71 ± 22, p = 0.041). The MP-TKA group had a higher FJS-12 total score than did the PS-TKA group (73 ± 24 vs. 64 ± 27, p = 0.025).

Conclusions: MP-TKA demonstrated better PROMs than did PS-TKA under mechanical alignment. Implant design with greater antero-posterior stability could improve post-operative outcomes after TKA.

Level of evidence: Level III.

Keywords: mechanical alignment; medial‐pivot; patient‐reported outcome measures; posterior‐stabilized; total knee arthroplasty.