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J Knee Surg 2020; 33(05): 452-458
DOI: 10.1055/s-0039-1678524
Original Article
Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

The Effect of Implant Design on Sagittal Plane Stability: A Randomized Trial of Medial- versus Posterior-Stabilized Total Knee Arthroplasty

Adam I. Edelstein
1   Department of Orthopaedic Surgery, Medical College of Wisconsin, Milwaukee, Wisconsin
,
Surabhi Bhatt
2   Department of Orthopaedic Surgery, Northwestern University, Feinberg School of Medicine, Chicago, Illinois
,
Josh Wright-Chisem
3   Department of Orthopaedic Surgery, Hospital for Special Surgery, New York, New York
,
Ryan Sullivan
2   Department of Orthopaedic Surgery, Northwestern University, Feinberg School of Medicine, Chicago, Illinois
,
Matt Beal
2   Department of Orthopaedic Surgery, Northwestern University, Feinberg School of Medicine, Chicago, Illinois
,
David W. Manning
2   Department of Orthopaedic Surgery, Northwestern University, Feinberg School of Medicine, Chicago, Illinois
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Publikationsverlauf

24. August 2018

27. Dezember 2018

Publikationsdatum:
08. Februar 2019 (online)

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Abstract

Up to 20% of total knee arthroplasty (TKA) patients report dissatisfaction with their outcome, especially with weight-bearing in flexion (WBiF) activities. Sagittal plane instability may contribute to dissatisfaction following TKA. We assessed the impact of implant design on TKA sagittal plane stability and clinical satisfaction. We randomized patients to receive one of two TKA implant designs: medial-stabilized (MS) or posterior-stabilized (PS). Sagittal stability was assessed using a KT-1000 arthrometer. Patient-reported outcome measures, including a custom bank of questions targeting patient satisfaction (0–100%) with WBiF activities, were administered to patients 2 years following surgery. The final analysis included 50 patients (25 MS, 25 PS). The MS group had greater sagittal plane stability than the PS group at 30-degree flexion (5.6 ± 1.9 vs. 10.2 ± 2.7 mm; p < 0.0001) but not at 90-degree flexion (4.1 ± 2 vs. 5.3 ± 3 mm; p = 0.14). Range of motion was not different (111.3 ± 10.4 vs. 114.7 ± 10.7 degrees; p = 0.31). There were no differences in the PROMIS (Patient-Reported Outcomes Measurement Information System) score, Oxford Knee Score, Knee Society Score, Forgotten Joint Score, or Veterans Rand. The MS group had no difference in satisfaction for WBiF activities versus non-WBiF activities (80.5 ± 18 vs. 88.3% ± 16.4%; p = 0.13), whereas the PS group had significantly worse satisfaction for WBiF versus non-WBiF activities (71.6 ± 24.6 vs. 87.8% ± 16.6%; p = 0.019). An MS prosthetic design was more stable in the sagittal plane in midflexion compared with a PS design. There was no difference in patient-reported outcomes, although custom survey data suggest improved satisfaction with MS design during WBiF activities.

Keywords

total knee arthroplasty - medial stabilized - posterior stabilized - implant design - sagittal plane stability

Note

This work was performed at the Northwestern University Feinberg School of Medicine, Chicago, IL. Institutional Review Board approval was granted for this study at Northwestern University.