Knee buckling: prevalence, risk factors, and associated limitations in function.
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.


METHODS
Cross-sectional, population-based study.


METHODS
The Framingham Osteoarthritis Study.


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


METHODS
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]).


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


CONCLUSIONS
In adults, knee buckling is common and is associated with functional loss.
Felson
David T
DT
Boston University School of Medicine, Hebrew SeniorLife, Brigham and Women's Hospital, and Boston Medical Center, Boston, Massachusetts 02118, USA. jendez@bu.edu
Niu
Jingbo
J
McClennan
Christine
C
Sack
Burton
B
Aliabadi
Piran
P
Hunter
David J
DJ
Guermazi
Ali
A
Englund
Martin
M
D000203:Activities of Daily Living; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018771:Arthralgia / Q000150:complications; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000150:complications / Q000453:epidemiology*; D007719:Knee Joint / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D018908:Muscle Weakness / Q000150:complications; D020370:Osteoarthritis, Knee / Q000150:complications; D011187:Posture; D015995:Prevalence; D012307:Risk Factors