A Retrospective Comparison of a Medial Pivot and Posterior-Stabilized Total Knee Arthroplasty With Respect to Patient-Reported and Radiographic Outcomes

J Arthroplasty. 2018 May;33(5):1379-1383. doi: 10.1016/j.arth.2017.11.049. Epub 2017 Dec 7.


Background: Medial pivot (MP) type total knee arthroplasty (TKA) implants are designed with a highly congruent medial tibiofemoral articulation. Compared with the cam-and-post design of the posterior-stabilized (PS) TKA, the MP-TKA design has been hypothesized to better replicate the natural kinematics of the knee. We compared the MP-TKA and PS-TKA designs, with our primary outcome measures being range of motion (ROM) and patient-reported satisfaction.

Methods: This study was a retrospective comparison between the 2 groups (76 MP-TKA vs 88 PS-TKA). ROM was collected preoperatively, 6 weeks, 6 months, and 1 year postoperatively. The Forgotten Joint Score-12 (FJS-12) scores were collected at a minimum of 1 year postoperatively.

Results: There was no statistically significant difference in age, gender, or body mass index between the groups. We found a statistical difference in preoperative ROM (MP = 120.3°, PS = 112.8°, P = .002). There was no difference in ΔROM at 6 weeks (MP = -12.36, PS = -3.79, P = .066), 6 months (MP = -4.23, PS = 2.73, P = .182), or 1 year (MP = .17, PS = 3.31, P = .499). Patients who underwent the MP-TKA scored significantly better than the PS-TKA on the FJS-12 score (MP = 59.72, PS = 44.77, P = .007).

Conclusion: We found that patients who underwent the MP-TKA scored better on the FJS than those who underwent the PS-TKA; particularly with regard to deep knee flexion and stability of the prosthesis. The MP-TKA design may offer improved patient outcomes because of its highly congruent medial tibiofemoral articulation.

Keywords: TKA design; forgotten joint score; medial pivot; patient-reported outcome measure; posterior-stabilized primary total knee arthroplasty.

Publication types

  • Comparative Study

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Arthroplasty, Replacement, Knee / methods*
  • Biomechanical Phenomena
  • Body Mass Index
  • Female
  • Humans
  • Knee Joint / surgery*
  • Knee Prosthesis*
  • Male
  • Middle Aged
  • Patient Satisfaction
  • Postoperative Period
  • Prosthesis Design*
  • Range of Motion, Articular
  • Retrospective Studies
  • Severity of Illness Index