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. 2022:8:36.
doi: 10.1051/sicotj/2022037. Epub 2022 Aug 23.

Evaluation of patella height in native knees and arthroplasty: an instructional review

Christian Konrads  1 , Anna J Schreiner  2 , Simone Cober  1 , Daniel Schüll  1 , Sufian S Ahmad  3 , Mohammad A Alshrouf  4
Affiliations

Evaluation of patella height in native knees and arthroplasty: an instructional review

Christian Konrads et al. SICOT J. 2022.

Abstract

Total knee arthroplasty (TKA) is the gold standard for treating advanced knee osteoarthritis. Among the postoperative complications of TKA are true patella infera (TPI) and pseudo patella infera (PPI), which should be differentiated since TPI exhibits significantly worse clinical outcomes. Multiple radiological patella height indices (PHI) exist; some were modified or originally designed for knees with implanted endoprostheses. However, there is no consensus on measuring and comparing patella height. Due to the lack of established, simple, reliable, and reproducible concepts for assessing patella height for arthroplasty, measuring patella height and the change of patella height by or after TKA have been challenging tasks for clinicians and researchers. This is a review of the current literature on methods for measuring patella height, with special attention to the ability to differentiate between the TPI and PPI after TKA. All literature on the topic was retrieved, and references from relevant articles were investigated until the end of April 2022.

Keywords: Caton-Deschamps; Insall-Salvati; Patella height; Patella infera; Reliability; TKA.

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Figures

Figure 1
Figure 1
Indices for patella height measuring. (a) Blackburne-Peel index for native knee and modified Blackburne-Peel index for arthroplasty. (b) Modified Insall-Salvati index. (c) Caton-Deschamps index for native knee and derived Caton-Deschamps index for arthroplasty. (d) Modified Caton Deschamps index. Index value = A:B.
Figure 2
Figure 2
Knee arthroplasty before and after isolated tibial insert exchange to a thicker one due to preoperative instability. (a) Before insert exchange. (b) After insert exchange. Pseudo patella infera is created.
Figure 3
Figure 3
Definitions, reasons, and modalities of assessment of true and pseudo patella infera. CDI, Caton-Deschamps index; dCDI, derived Caton-Deschamps index; mISI, modified Insall-Salvati index.
Figure 4
Figure 4
Concept of patella height assessment. Full patella height (CDI for knees without arthroplasty and dCDI for knees with arthroplasty implanted) and the amount of true patella height (mISI for all knees) are determined. CDI, Caton-Deschamps index; dCDI, derived Caton-Deschamps index; mISI, modified Insall-Salvati index.
See this image and copyright information in PMC

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