Thigh Muscle Cross-Sectional Areas and Strength in Advanced Versus Early Painful Osteoarthritis: An Exploratory Between-Knee, Within-Person Comparison in Osteoarthritis Initiative Participants

Authors

  • Anja Ruhdorfer,

    Corresponding author
    • Paracelsus Medical University, Salzburg, Austria
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  • Torben Dannhauer,

    1. Paracelsus Medical University, Salzburg, Austria
    2. Chondrometrics, Ainring, Germany
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  • Wolfgang Wirth,

    1. Paracelsus Medical University, Salzburg, Austria
    2. Chondrometrics, Ainring, Germany
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    • Dr. Wirth has received consultant fees, speaking fees, and/or honoraria (less than $10,000) from Merck Sorono, and owns stock and/or stock options in Chondrometrics.

  • Wolfgang Hitzl,

    1. Paracelsus Medical University, Salzburg, Austria
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  • C. Kent Kwoh,

    1. University of Pittsburgh and VA Pittsburgh Healthcare System, Pittsburgh, Pennsylvania
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  • Ali Guermazi,

    1. Boston University School of Medicine and Boston Imaging Core Lab LLC, Boston, Massachusetts
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    • Dr. Guermazi has received consultant fees, speaking fees, and/or honoraria (less than $10,000 each) from Genzyme, Novartis, and AstraZeneca and (more than $10,000) from Merck Sorono, and owns stock and/or stock options in Boston Imaging Core Lab LLC.

  • David J. Hunter,

    1. Royal North Shore Hospital and Northern Clinical School, University of Sydney, Sydney, New South Wales, Australia
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  • Olivier Benichou,

    1. Eli Lilly, Indianapolis, Indiana
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    • Dr. Benichou owns stock and/or stock options in Eli Lilly.

  • Felix Eckstein,

    1. Paracelsus Medical University, Salzburg, Austria
    2. Chondrometrics, Ainring, Germany
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    • Dr. Eckstein has received consultant fees, speaking fees, and/or honoraria (less than $10,000 each) from Medtronic, Synthes, GSK, and Genzyme and (more than $10,000 each) from Merck Sorono, Sanofi-Aventis, Novartis, Abbott, and Pfizer, and owns stock and/or stock options in Chondrometrics.

  • For The Osteoarthritis Initiative Investigators


Institute of Anatomy, Paracelsus Medical University, Strubergasse 21, A5020 Salzburg, Austria. E-mail: anja.ruhdorfer@pmu.ac.at

Abstract

Objective

To compare cross-sectional and longitudinal side differences in thigh muscle anatomic cross-sectional areas (ACSAs), strength, and specific strength (strength/ACSA) between knees with early versus advanced painful radiographic osteoarthritis in the same person.

Methods

Forty-four of 2,678 Osteoarthritis Initiative participants (31 women and 13 men) met the inclusion criteria of bilateral frequent knee pain, medial joint space narrowing (JSN) in 1 knee, and no medial (or lateral) JSN in the contralateral knee. Thigh muscle ACSAs of the quadriceps, hamstrings, adductors, and individual quadriceps heads at consistent locations were determined using magnetic resonance imaging. Isometric muscle strength was determined in extension/flexion (Good Strength Chair). Baseline quadriceps ACSAs and strength were considered primary end points, and longitudinal changes of these factors were considered secondary end points (by paired t-tests).

Results

No significant side differences in quadriceps (or other thigh muscle) ACSAs, strength, or specific strength were observed between medial JSN knees versus knees without JSN, or between specific medial JSN knee strata and contralateral knees without JSN, either in men or women. Two-year longitudinal changes in thigh muscle ACSAs and strength were small (≤5.2%) and did not differ significantly between medial JSN knees and knees without JSN.

Conclusion

In the context of previous findings that side differences in pain are associated with side differences in quadriceps ACSAs, the current results suggest that quadriceps (and other thigh muscle) properties are not independently associated with radiographic disease status (JSN) once knees have reached frequent pain status. Further, our longitudinal findings indicate that a more advanced radiographic stage of knee osteoarthritis is not necessarily associated with a longitudinal decline in muscle function.

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