Knee Buckling: Prevalence, Risk Factors, and Associated Limitations in Function

16 October 2007 | Volume 147 Issue 8 | Pages 534-540

Background: Knee buckling is common in persons with advanced knee osteoarthritis and after orthopedic procedures. Its prevalence in the community is unknown.

Objective: To examine the prevalence of knee buckling in the community, its associated risk factors, and its relation to functional limitation.

Design: Cross-sectional, population-based study.

Setting: The Framingham Osteoarthritis Study.

Participants: 2351 men and women age 36 to 94 years (median, 63.5 years).

Measurements: Participants were asked whether they had experienced knee buckling or "giving way" and whether it led to falling. They were also asked about knee pain and limitations in function by using the Short Form-12 and Western Ontario and McMaster Universities Osteoarthritis Index, had isometric tests of quadriceps strength, and underwent weight-bearing radiography and magnetic resonance imaging of the knee. Radiographs were scored for osteoarthritis by using the Kellgren–Lawrence scale, and magnetic resonance images were read for anterior cruciate ligament tears. The relationship of buckling to functional limitation was examined by using logistic regression that adjusted for age, sex, body mass index, and knee pain severity.

Results: Two hundred seventy-eight participants (11.8%) experienced at least 1 episode of knee buckling within the past 3 months; of these persons, 217 (78.1%) experienced more than 1 episode and 35 (12.6%) fell during an episode. Buckling was independently associated with the presence of knee pain and with quadriceps weakness. Over half of those with buckling had no osteoarthritis on radiography. Persons with knee buckling had worse physical function than those without buckling, even after adjustment for severity of knee pain and weakness. For example, 46.9% of participants with buckling and 21.7% of those without buckling reported limitations in their work (adjusted odds ratio, 2.0 [95% CI, 1.5 to 2.7]).

Limitation: Causal inferences are limited because of the study's cross-sectional design.

Conclusion: In adults, knee buckling is common and is associated with functional loss.

Editors' Notes Context Knee buckling is the sudden loss of postural support across the knee at a time of weight bearing. Its prevalence and consequences are not clear. Contribution This study of 2351 community-dwelling, middle-age and older adults found that 278 participants (12%) reported at least 1 episode of knee buckling in the past 3 months. Of these, 13% fell during the episode. Knee pain, quadriceps weakness, and worse physical function were associated with buckling. Caution The study's cross-sectional design limits causal inferences. Implications Knee buckling occurs commonly among middle-age and older adults and is sometimes associated with functional limitations. —The Editors

 

Author and Article Information

From Boston University School of Medicine, Hebrew SeniorLife, Brigham and Women's Hospital, and Boston Medical Center, Boston, Massachusetts.

Acknowledgments: The authors thank the participants of the Framingham Osteoarthritis Study for helping them perform this study.

Grant Support: By grants AR47785 and AG18393 from the National Institutes of Health and contract N01-HC-25195 for the National Heart, Lung, and Blood Institute's Framingham Heart Study.

Potential Financial Conflicts of Interest: None disclosed.

Requests for Single Reprints: David T. Felson, MD, MPH, Clinical Epidemiology Unit, Suite 200, Boston University School of Medicine, 650 Albany Street, Boston, MA 02118; e-mail, jendez{at}bu.edu.

Current Author Addresses: Drs. Felson, Niu, Sack, Hunter, and Englund: Clinical Epidemiology Unit, Suite 200, Boston University School of Medicine, 650 Albany Street, Boston, MA 02118.

Ms. McClennan: Institute for Aging Research, Hebrew SeniorLife, 1200 Centre Street, Boston, MA 02131.

Dr. Aliabadi: Department of Radiology, Brigham and Women's Hospital, 75 Francis Street, Boston, MA 02115.

Dr. Guermazi: Department of Radiology, 818 Harrison Avenue, Boston Medical Center, Boston, MA 02118.

Author Contributions: Conception and design: D.T. Felson, M. Englund.

Analysis and interpretation of the data: D.T. Felson, J. Niu, A. Guermazi, D.J. Hunter, M. Englund.

Drafting of the article: D.T. Felson.

Critical revision of the article for important intellectual content: J. Niu, C. McClennan, B. Sack, P. Aliabadi, A. Guermazi, D.J. Hunter, M. Englund.

Final approval of the article: C. McClennan, A. Guermazi.

Provision of study materials or patients: D.T. Felson, B. Sack.

Statistical expertise: J. Niu.

Obtaining of funding: D.T. Felson.

Administrative, technical, or logistic support: D.T. Felson, J. Niu, C. McClennan.

Collection and assembly of data: D.T. Felson, J. Niu, C. McClennan, B. Sack, P. Aliabadi.

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