Osteoarthritis (OA) is a leading cause of pain, disability and leads to reduced quality of life. Approximately 25% of adults aged over 55 report at least one episode of knee pain each year which is likely to reflect underlying OA. This highlights the need for awareness of the various risk factors so prevention techniques can be addressed.
The aim of this review was to determine the current evidence on risk factors for onset of knee OA in those aged 50 years and over. Items of interest were non-clinical factors such as BMI and age.
Here’s what they did
The authors searched several databases published between the start of each database and December 2012. Databases included MEDLINE, EMBASE, CINAHL and AMED. All papers searched for were in the English language.
Cohort studies were included if they had the outcome of onset of knee pain / OA described symptomatically or radiographically. A systematic review and meta-analysis was conducted of cohort studies for risk factors for the onset of knee pain. Where possible, pooled odds ratios (OR) were calculated via random effects meta-analysis and population attributable fractions (PAFs) derived.
Inclusion criteria included mean age of participants 50 or over. Risk factors assessed were demographic, socio-economic, co-morbidity, weight, age, gender and previous knee injury. Exclusion criteria included total knee replacement or other surgical interventions, along with inflammatory arthritis such as rheumatoid arthritis.
Here’s what they found
46 papers were included in this review with 34 included within a meta-analysis. The meta-analysis was performed for five risk factors including BMI, female gender, smoking, previous knee injury and the presence of hand OA/Heberdens nodes. Within the review, overweight was defined as BMI between 25-30 and obesity as BMI over 30.
23 cohort studies reported on being overweight and showed a pooled OR 1.98 (95% CI 1.57 – 2.20). The studies consistently demonstrated being overweight was a risk factor for the onset of knee OA.
When considering obesity, the pooled OR of 22 cohort studies was 2.66 (95% CI 2.15 – 3.28). This demonstrated that obesity had a slightly larger effect on onset of knee OA than being overweight.
Previous Knee Injury
12 cohort studies showed increased risk of knee OA with a prior injury with the pooled OR being 2.38 (95% CI 1.91 – 4.19)
There was consistent evidence that females were at higher risk of knee OA with pooled OR of 1.68 (95% CI 1.37 – 2.07)
The pooled OR of 1.30 (95% CI 0.90 – 1.87) indicated that hand OA may potentially be a risk factor for knee OA.
Smoking was found not to be statistically significant. Creating a pooled OR was not possible for age as the studies used a range of different age categorisations. However, studies were generally in agreement that increasing age was a significant risk factor for onset of knee OA.
The authors concluded
This review identified several risk factors for the development of knee pain and knee OA in older adults. The results of this review can be used clinically to help healthcare professionals identify and manage patients at risk.
The Musculoskeletal Elf’s view
Since the publication of the author’s last review in January 2008, there has been further evidence to support the effect of previously known risk factors of increased BMI, previous knee injury, being female and hand OA. These findings agree with those found within the 2014 update to the NICE guidelines for management of OA in adults.
As supported by the NICE guidelines, advice should be offered on activity, exercise and interventions to achieve weight loss. Exercise should be considered a core treatment irrespective of age, co-morbidity, pain severity or disability and should include local muscle strengthening and general aerobic fitness.
What do you think?
- What are the various risk factors you as a therapist are aware of when treating OA knee patients?
- How do you approach the topic of weight loss with patients?