Knee Osteoarthritis Cohort Research Articles

The relationship between knee pain characteristics and symptom state acceptability in people with knee osteoarthritis

To examine the association between osteoarthritis (OA) pain characteristics and symptom acceptability. Using a cross-sectional study design in a knee OA cohort we assessed socio-demographics, knee pain characteristics (Intermittent and Constant Osteoarthritis Pain(ICOAP); higher scores worse), frequency of intermittent pain 'without warning' (unpredictable) or 'after a trigger' (predictable) (never to very often) and the acceptability of knee pain symptoms (yes/no). Using logistic regression, we examined the relationship between pain characteristics and symptom acceptability. 136 cohort members' participated (mean age 74 years, SD 9.5; 54% female). Most (97%) reported intermittent pain (mean ICOAP intermittent score 36.8, SD 19.7) and 62 (46%) reported constant pain (mean ICOAP constant score 46.7, SD 20.2). Of those with intermittent pain, 42% reported frequent (often/very often) predictable pain and 27% frequent unpredictable pain. 35% reported "unacceptable" knee symptoms. In multivariable analysis, the odds of reporting an unacceptable symptom state increased with increasing intermittent knee pain scores and the effect was greater for those with vs without frequent unpredictable intermittent pain (adjusted OR per 10-point increase in ICOAP intermittent score 3.31, 95% confidence interval (CI) 1.38-7.97 vs 1.23, 95%CI 0.88-1.74, respectively; P value for the interaction=0.03). In a community cohort with symptomatic knee OA, both the severity and predictability of intermittent knee pain contributed to symptom state acceptability. Unpredictable intermittent knee pain was more likely to be associated with an unacceptable symptom state than predictable intermittent pain. Research is warranted to elucidate potentially modifiable determinants of unpredictable intermittent pain in people with knee OA.

High prevalence of contralateral ankle abnormalities in association with knee osteoarthritis and malalignment

To evaluate ankle joint abnormalities in a knee osteoarthritis (OA) cohort. Participants (n=159) with symptomatic and radiographic OA in at least one knee underwent technetium-99m methylene diphosphonate bone scan (scored 0-3) of the ankles and forefeet. Knee radiographs were graded for OA features of joint space narrowing (JSN) and osteophyte (OST). Ankle symptoms and history of ankle injury were assessed by self-report. Knee alignment was measured from a long-limb radiograph. Ankle radiographs were obtained on those who returned for follow-up (n=138) and were graded for ankle tibiotalar JSN and OST. Ankle scintigraphic abnormalities were frequent (31% of individuals, one-third bilateral). Ankle symptoms were reported by 23% of individuals and history of ankle injury by 24%. Controlling for gender, age, body mass index (BMI), and contralateral predictor, ankle scintigraphic abnormalities were associated with: ipsilateral ankle symptoms (P=0.005); contralateral knee JSN (P=0.001), knee OST (P=0.006) and knee malalignment (P=0.08); and history of ankle injury or surgery of either ankle (P<0.0001). At follow-up, scintigraphic abnormalities of the ankle were strongly associated with presence of tibiotalar radiographic OA (P<0.0001). Although considered rare, we observed a high prevalence of radiographic features of ankle OA in this knee OA cohort. History of overt ankle injury did not appear to account for the majority of ankle abnormalities. These results are consistent with a probable kinematic association of knee OA pathology and contralateral ankle abnormalities and suggest that interventions targeting mechanical factors may be needed to prevent ankle OA in the setting of knee OA.

Estimating the Burden of Total Knee Replacement in the United States

In the last decade, the number of total knee replacements performed annually in the United States has doubled, with disproportionate increases among younger adults. While total knee replacement is a highly effective treatment for end-stage knee osteoarthritis, total knee replacement recipients can experience persistent pain and severe complications. We are aware of no current estimates of the prevalence of total knee replacement among adults in the U.S. We used the Osteoarthritis Policy Model, a validated computer simulation model of knee osteoarthritis, and data on annual total knee replacement utilization to estimate the prevalence of primary and revision total knee replacement among adults fifty years of age or older in the U.S. We combined these prevalence estimates with U.S. Census data to estimate the number of adults in the U.S. currently living with total knee replacement. The annual incidence of total knee replacement was derived from two longitudinal knee osteoarthritis cohorts and ranged from 1.6% to 11.9% in males and from 2.0% to 10.9% in females. We estimated that 4.0 million (95% confidence interval [CI]: 3.6 million to 4.4 million) adults in the U.S. currently live with a total knee replacement, representing 4.2% (95% CI: 3.7% to 4.6%) of the population fifty years of age or older. The prevalence was higher among females (4.8%) than among males (3.4%) and increased with age. The lifetime risk of primary total knee replacement from the age of twenty-five years was 7.0% (95% CI: 6.1% to 7.8%) for males and 9.5% (95% CI: 8.5% to 10.5%) for females. Over half of adults in the U.S. diagnosed with knee osteoarthritis will undergo a total knee replacement. Among older adults in the U.S., total knee replacement is considerably more prevalent than rheumatoid arthritis and nearly as prevalent as congestive heart failure. Nearly 1.5 million of those with a primary total knee replacement are fifty to sixty-nine years old, indicating that a large population is at risk for costly revision surgery as well as possible long-term complications of total knee replacement.

Neuropathic pain symptoms in a community knee OA cohort

A neuropathic pain (NP) questionnaire may facilitate the identification of a neuropathic component to osteoarthritis (OA) pain. An existing questionnaire, the painDETECT, was modified for use in knee OA and administered to measure the prevalence and correlates of NP symptoms among adults with this condition. Sensibility of the modified painDETECT (mPD-Q) was assessed in 20 OA subjects followed by mail administration in an established knee OA cohort. NP symptoms were defined using a previously established, painDETECT cut-point. Correlates of NP symptoms, including OA severity (Western Ontario and McMaster Universities Osteoarthritis Index, Von Korff Chronic Pain Grade pain subscale score), psychological factors (Centre for Epidemiological Studies Depression Scale, Pain Catastrophizing Scale), and concomitant medical conditions, were evaluated using logistic regression. Construct validity of the mPD-Q was evaluated through co-administration with another NP questionnaire (S-LANSS). The mPD-Q had face and content validity. Of 259 eligible cohort members, 171 (66%) completed the questionnaire; 28% had NP symptoms on the mPD-Q (19% among those without neurological conditions). Independent correlates of NP symptoms were: pain intensity (adjusted odds ratio [OR]=2.1 per 10 unit increase, P<0.0001), the presence of referred back/hip pain (adjusted OR=2.9, P=0.024), number of painful joints (OR=1.2, P=0.20) and one or more self-reported neurological condition (OR=3.0, P=0.026). Among older adults with chronic symptomatic knee OA, over one-quarter had NP symptoms localized to their knees using the mPD-Q. The mPD-Q may facilitate the identification of a neuropathic component to pain in adults with knee OA who may benefit from further evaluation and/or treatment for NP.

Impact of Knee Osteoarthritis on Health Care Resource Utilization in a US Population-Based National Sample

We sought to estimate the impact of knee osteoarthritis (OA) on health care utilization. Using the 2003 Medicare Current Beneficiary Survey, a population-based survey of Medicare beneficiaries linked to Medicare claims, we selected a national cohort of community-dwelling persons aged 65 and older with knee OA and a sex- and age-matched comparison cohort without any form of OA. We distinguished following 4 components of health care utilization: physician (MD) office visits, non-MD office visits, inpatient hospital stays, and emergency department visits. We built multiple regression models to determine whether knee OA affects utilization, controlling for comorbidity count, obesity, functional limitation, education, race, and working status. A total of 545 Medicare Current Beneficiary Survey participants with knee OA were matched with 1090 OA-free individuals. Mean age in both cohorts was 76 years; approximately 70% were female. Knee OA and OA-free subjects differed significantly in obesity (Knee OA: 37%, OA-free: 20%), % with >or=2 comorbidities (Knee OA: 69%, OA-free: 43%), and functional limitation (Knee OA: 42%, OA-free: 26%). In multivariable regression models, the knee OA cohort had on average 6.0 more annual MD visits (95% confidence interval [CI]: 4.7, 7.4) and 3.8 more non-MD visits (95% CI: 2.8, 4.7) than the OA-free cohort. The knee OA cohort also had 28% more hospital stays (odds ratio [OR] = 1.3, 95% CI: 1.0, 1.6), a difference attributable to total joint replacements. This first national, population-based study of health care utilization in persons with knee OA documents considerable excess utilization attributable to knee OA, independent of comorbidity, and other patient characteristics.