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. 2017 Aug 2;1(4):e020.
doi: 10.5435/JAAOSGlobal-D-17-00020. eCollection 2017 Jul.

Malpositioning of Prosthesis: Patient-specific Total Knee Arthroplasty Versus Standard Off-the-Shelf Total Knee Arthroplasty

Kyoung-Tak Kang  1 , Juhyun Son  1 , Oh-Ryong Kwon  1 , Yong-Gon Koh  1
Affiliations

Malpositioning of Prosthesis: Patient-specific Total Knee Arthroplasty Versus Standard Off-the-Shelf Total Knee Arthroplasty

Kyoung-Tak Kang et al. J Am Acad Orthop Surg Glob Res Rev. .

Abstract

Introduction: A recent study has challenged the premise that a patient-specific (PS)-designed total knee arthroplasty (TKA) component has better clinical survival than an off-the-shelf (OTS) prosthesis.

Methods: We developed the finite element models for PS TKA and OTS TKA with 5° varus and valgus malalignment and 5° internal and external malrotations.

Results: Contact stress on the medial side of the insert increased with internal femoral malrotation and varus tibial malalignment, but it decreased with external femoral malrotation and varus tibial malalignment in both PS TKA and OTS TKA. An increase in ligament force occurred in valgus malalignment and external malrotation, and in particular, the force exerted on the medial collateral ligament increased. However, PS TKA provided better biomechanical effects than did the standard OTS TKA with malpositioning in TKA.

Discussion: These results emphasize the importance of precise surgical preservation in regard to the TKA position.

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Conflict of interest statement

The authors have no conflicts of interest to disclose. Dr. Kang and Mr. Son contributed equally to this work and should be considered co-first authors. Dr. Kwon and Dr. Koh contributed equally to this work and should be considered co-corresponding authors.

Figures

Figure 1
Figure 1
Development process for the final element (FE) model. CAD = computer-aided design, OTS = off the shelf, PS = patient-specific, TKA = total knee arthroplasty
Figure 2
Figure 2
A, Surface geometry used in the PS TKA design. B, PS femoral component. C, PS PE insert with respect to the patient's bone geometry. PE = polyethylene, PS = patient-specific, TKA = total knee arthroplasty.
Figure 3
Figure 3
Finite element (FE) models used in this study. OTS = off the shelf, PS = patient-specific, TKA = total knee arthroplasty
Figure 4
Figure 4
Comparison of maximum contact stress on the (A) medial surface and (B) lateral surface of the polyethylene (PE) insert with respect to malpositioning in total knee arthroplasty (TKA) during the gait cycle. OTS = off the shelf, PS = patient-specific
Figure 5
Figure 5
Comparison of maximum contact stress on the (A) medial surface and (B) lateral surface of the polyethylene (PE) insert with respect to malpositioning in total knee arthroplasty (TKA) during the deep knee bend cycle. OTS = off the shelf, PS = patient-specific
Figure 6
Figure 6
Comparison of ligament forces on the (A) MCL, (B) LCL, (C) PFL, and (D) ALS with respect to malpositioning in TKA during the gait cycle. ALS = anterior lateral structure, LCL = lateral collateral ligament, MCL = medial collateral ligament, OTS = off the shelf, PFL = popliteofibular ligament, PS = patient-specific, TKA = total knee arthroplasty
Figure 7
Figure 7
Comparison of ligament forces on the (A) MCL, (B) LCL, (C) PFL, and (D) ALS with respect to malpositioning in TKA during the deep knee bend cycle. ALS = anterior lateral structure, LCL = lateral collateral ligament, MCL = medial collateral ligament, OTS = off the shelf, PFL = popliteofibular ligament, PS = patient-specific, TKA = total knee arthroplasty
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