Research Article

Variations in varus/valgus and internal/external rotational knee laxity and stiffness across the menstrual cycle

  1. Sandra J. Shultz1,*,
  2. Randy J. Schmitz1,
  3. Bruce D. Beynnon2

Article first published online: 29 SEP 2010

DOI: 10.1002/jor.21243

Issue

Journal of Orthopaedic Research

Journal of Orthopaedic Research

Volume 29, Issue 3, pages 318–325, March 2011

Additional Information

How to Cite

Shultz, S. J., Schmitz, R. J. and Beynnon, B. D. (2011), Variations in varus/valgus and internal/external rotational knee laxity and stiffness across the menstrual cycle. Journal of Orthopaedic Research, 29: 318–325. doi: 10.1002/jor.21243

Author Information

  1. 1

    Applied Neuromechanics Research Laboratory, Department of Kinesiology, University of North Carolina at Greensboro, Greensboro, North Carolina

  2. 2

    McClure Musculoskeletal Research Center, Department of Orthopaedics and Rehabilitation, University of Vermont College of Medicine, Burlington, VT

*Applied Neuromechanics Research Laboratory, Department of Kinesiology, University of North Carolina at Greensboro, Greensboro, North Carolina. T: 336-334-3027; F: 336-334-3070.

Publication History

  1. Issue published online: 24 JAN 2011
  2. Article first published online: 29 SEP 2010
  3. Manuscript Accepted: 14 JUL 2010
  4. Manuscript Received: 25 MAR 2010

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Keywords:

  • ACL injury risk;
  • knee biomechanics;
  • hormone response;
  • knee laxity;
  • menstrual cycle

Abstract

Cyclic variations in genu recurvatum (GR), general joint laxity (GJL), varus–valgus (VV), and internal–external (IER) rotational laxities and stiffnesses were examined in 64 females and 43 males at two time points during the females' menstrual cycle [days of minimum (T1) and maximum (T2) anterior knee laxity (AKL)]. Cyclic increases in AKL (9.5%), GR (37.5%), and GJL (13.6%) were observed in females but not males from T1 to T2 (p < 0.001). Cyclic increases in VV and IER laxity were negligible (1.5–3.2%, p > 0.320). Females compared to males had lower overall VV stiffness at T2 (F 37% <M) vs. T1 (F 26.9% <M; p = 0.011), but no difference across time points for IER stiffness (p = 0.452). Across both time points, females had consistently greater VV (30.2%) and IER (20%) laxity and less VV (32.5%) and IER (24.3%) incremental stiffness (p < 0.001). Low-to-moderate associations were observed between AKL, GR, and GJL with VV and IER laxities and stiffnesses in females as measured at T1 and the change in values from T1 to T2. Whether these findings reflect ligament-specific responses to hormone changes, or implicate changes in injury risk potential across the menstrual cycle requires further study. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29:318–325, 2011

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