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The association of BMI and knee pain among persons with radiographic knee osteoarthritis: a cross-sectional study.

Rogers MW, Wilder FV - BMC Musculoskelet Disord (2008)

Bottom Line: Many people with radiographic knee osteoarthritis (RKOA) do not present with pain.WHO-classified BMI categories were compared by pain status.Pain subjects presented with a higher mean BMI (30.4 kg/m2) compared with No Pain subjects (27.5 kg/m2) (p < 0.0001).

View Article: PubMed Central - HTML - PubMed

Affiliation: The Arthritis Research Institute of America, 300 S, Duncan Avenue, Suite 188, Clearwater, Florida 33755, USA. mrogers@preventarthritis.org

ABSTRACT

Background: Many people with radiographic knee osteoarthritis (RKOA) do not present with pain. It is suspected that such persons tend toward lower body mass index (BMI). The purpose of the study was to explore the relationship between BMI and knee pain among persons with RKOA.

Methods: Subjects in the Clearwater Osteoarthritis Study with RKOA (N = 576) were classified as reporting knee pain (Pain) or no knee pain (No Pain). WHO-classified BMI categories were compared by pain status. Odds ratios were calculated for the four elevated BMI groups, with the normal BMI group as the reference group. Elevated BMI was the risk factor, and knee pain status was the outcome factor.

Results: Pain subjects presented with a higher mean BMI (30.4 kg/m2) compared with No Pain subjects (27.5 kg/m2) (p < 0.0001). Unadjusted and adjusted odds ratios demonstrated a positive association between BMI group and pain for each successive elevated BMI category. Adjusted odds ratios ranged from 1.6 for the Pre-obese group (p < 0.05) to 7.5 for the Obese III group (p < 0.0001).

Conclusion: Among subjects with RKOA, those presenting with an elevated BMI had a greater likelihood of knee pain compared to subjects with a normal BMI, and this chance rose with each successive elevated BMI category. As BMI is a modifiable risk factor, longitudinal research is needed to confirm these findings and elucidate the mechanisms underlying this relationship.

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Sample selection from the Clearwater Osteoarthritis Study.
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Figure 1: Sample selection from the Clearwater Osteoarthritis Study.

Mentions: Our primary hypothesis for the present study was that, among subjects with RKOA, elevated BMI is not associated with pain status. We used a cross-sectional design, and our study sample included 576 subjects. Sample selection from the COS is detailed in Figure 1. COS subjects who had undergone partial or total knee joint replacement surgery or reported a history of knee trauma were excluded from the analysis. RKOA was determined by the criteria of Kellgren & Lawrence [19] and defined as Grade 2 or higher readings in either or both knees. All radiographs were graded by a board certified radiologist. Positive history of knee injury was determined by affirmative responses to either of the following questions: "Have you ever had a fractured knee?" or, "Have you ever had a severe twisting of either knee with resultant sprain or swelling lasting more than two weeks?" Subjects with knee injury history were excluded, so our sample subjects would more closely align with the American College of Rheumatology criteria for primary knee OA [20]. Based on knee pain status, subjects were categorized as having knee pain (Pain) or no knee pain (No Pain). Subjects categorized as Pain must have presented with pain in (at least) the knee with radiographic evidence of OA. The questionnaire depicted a human figure on which subjects were asked to circle up to four noted areas of the knee(s) that were painful. Subjects that reported "No pain" or "Don't know" were included in the No Pain category. A pain rating scale was not provided.


The association of BMI and knee pain among persons with radiographic knee osteoarthritis: a cross-sectional study.

Rogers MW, Wilder FV - BMC Musculoskelet Disord (2008)

Sample selection from the Clearwater Osteoarthritis Study.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2651875&req=5

Figure 1: Sample selection from the Clearwater Osteoarthritis Study.
Mentions: Our primary hypothesis for the present study was that, among subjects with RKOA, elevated BMI is not associated with pain status. We used a cross-sectional design, and our study sample included 576 subjects. Sample selection from the COS is detailed in Figure 1. COS subjects who had undergone partial or total knee joint replacement surgery or reported a history of knee trauma were excluded from the analysis. RKOA was determined by the criteria of Kellgren & Lawrence [19] and defined as Grade 2 or higher readings in either or both knees. All radiographs were graded by a board certified radiologist. Positive history of knee injury was determined by affirmative responses to either of the following questions: "Have you ever had a fractured knee?" or, "Have you ever had a severe twisting of either knee with resultant sprain or swelling lasting more than two weeks?" Subjects with knee injury history were excluded, so our sample subjects would more closely align with the American College of Rheumatology criteria for primary knee OA [20]. Based on knee pain status, subjects were categorized as having knee pain (Pain) or no knee pain (No Pain). Subjects categorized as Pain must have presented with pain in (at least) the knee with radiographic evidence of OA. The questionnaire depicted a human figure on which subjects were asked to circle up to four noted areas of the knee(s) that were painful. Subjects that reported "No pain" or "Don't know" were included in the No Pain category. A pain rating scale was not provided.

Bottom Line: Many people with radiographic knee osteoarthritis (RKOA) do not present with pain.WHO-classified BMI categories were compared by pain status.Pain subjects presented with a higher mean BMI (30.4 kg/m2) compared with No Pain subjects (27.5 kg/m2) (p < 0.0001).

View Article: PubMed Central - HTML - PubMed

Affiliation: The Arthritis Research Institute of America, 300 S, Duncan Avenue, Suite 188, Clearwater, Florida 33755, USA. mrogers@preventarthritis.org

ABSTRACT

Background: Many people with radiographic knee osteoarthritis (RKOA) do not present with pain. It is suspected that such persons tend toward lower body mass index (BMI). The purpose of the study was to explore the relationship between BMI and knee pain among persons with RKOA.

Methods: Subjects in the Clearwater Osteoarthritis Study with RKOA (N = 576) were classified as reporting knee pain (Pain) or no knee pain (No Pain). WHO-classified BMI categories were compared by pain status. Odds ratios were calculated for the four elevated BMI groups, with the normal BMI group as the reference group. Elevated BMI was the risk factor, and knee pain status was the outcome factor.

Results: Pain subjects presented with a higher mean BMI (30.4 kg/m2) compared with No Pain subjects (27.5 kg/m2) (p < 0.0001). Unadjusted and adjusted odds ratios demonstrated a positive association between BMI group and pain for each successive elevated BMI category. Adjusted odds ratios ranged from 1.6 for the Pre-obese group (p < 0.05) to 7.5 for the Obese III group (p < 0.0001).

Conclusion: Among subjects with RKOA, those presenting with an elevated BMI had a greater likelihood of knee pain compared to subjects with a normal BMI, and this chance rose with each successive elevated BMI category. As BMI is a modifiable risk factor, longitudinal research is needed to confirm these findings and elucidate the mechanisms underlying this relationship.

Show MeSH
Related in: MedlinePlus