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The Width:thickness Ratio of the Patella

An Aid in Knee Arthroplasty

  • Original Article
  • Knee
  • Published:
Clinical Orthopaedics and Related Research

Abstract

Establishing the appropriate size of the patellar implant-bone composite is one of the important steps ensuring functional success in arthroplasty. Conventionally, the patella is measured intraoperatively and its thickness is used to guide the depth of resection. However, in a diseased joint, this may not reflect the native patellar thickness. We studied the relationship between the patellar thickness and various patellar dimensions on three-dimensional reconstructed computed tomographic scans from 37 normal adult knees. Patellar width correlated with thickness. The average patellar width:thickness ratio was 2.0 (standard deviation, 0.106; 95% confidence interval, 1.96–2.03). The cartilage thickness was on average 2.5 mm (standard deviation, 1.0). The width:thickness ratio was similar in 79 digital radiographs taken before TKA of knees without patellofemoral disease (mean, 2.1; standard deviation, 0.28). When compared with the two other methods for calculating patellar resection described in the literature, the width:thickness ratio was more reliable. The width:thickness ratio appears anatomically constant and may be a useful guide for estimating premorbid patellar thickness.

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Acknowledgments

We thank Dr. Robin Richards for technical support and designing the three-dimensional image analysis software that was used in this study.

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Authors and Affiliations

  1. Division of Surgery, Oncology, Reproductive Biology and Anaesthetics, Imperial College London, 7th Floor, Charing Cross Hospital, Fulham Palace Road, London, W6 8RF, UK

    Farhad Iranpour MD, Azhar M. Merican MS (Orth) & Justin P. Cobb MCh, FRCS

  2. Biomechanics Division, Mechanical Engineering Department, Imperial College London, London, UK

    Andrew A. Amis DSc (Eng)

Authors
  1. Farhad Iranpour MD
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  2. Azhar M. Merican MS (Orth)
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  3. Andrew A. Amis DSc (Eng)
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  4. Justin P. Cobb MCh, FRCS
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Corresponding author

Correspondence to Farhad Iranpour MD.

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Each author certifies that he or she has no commercial associations (eg, consultancies, stock ownership, equity interest, patent/licensing arrangements, etc) that might pose a conflict of interest in connection with the submitted article.

Each author certifies that his or her institution has approved the human protocol for this investigation, that all investigations were conducted in conformity with ethical principles of research, and that informed consent for participation in the study was obtained.

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Iranpour, F., Merican, A.M., Amis, A.A. et al. The Width:thickness Ratio of the Patella. Clin Orthop Relat Res 466, 1198–1203 (2008). https://doi.org/10.1007/s11999-008-0130-x

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  • DOI: https://doi.org/10.1007/s11999-008-0130-x

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