From Medicine and Science in Sports and Exercise®

What is the Effect of Physical Activity on the Knee Joint?

A Systematic Review

Donna M. Urquhart; Jephtah F. L. Tobing; Fahad S. Hanna; Patricia Berry; Anita E. Wluka; Changhai Ding; Flavia M. Cicuttini

Authors and Disclosures

Posted: 03/14/2011; Medicine and Science in Sports and Exercise®. 2011;43(3):432-442. © 2011 American College of Sports Medicine

Abstract and Introduction

Abstract

Purpose: Although several studies have examined the relationship between physical activity and knee osteoarthritis, the effect of physical activity on knee joint health is unclear. The aim of this systematic review was to examine the relationships between physical activity and individual joint structures at the knee.
Methods: Computer-aided searches were conducted up until November 2008, and the reference lists of key articles were examined. The methodological quality of selected studies was assessed based on established criteria, and a best-evidence synthesis was used to summarize the results.
Results: We found that the relationships between physical activity and individual joint structures at the knee differ. There was strong evidence for a positive association between physical activity and tibiofemoral osteophytes. However, we also found strong evidence for the absence of a relationship between physical activity and joint space narrowing, a surrogate method of assessing cartilage. Moreover, there was limited evidence from magnetic resonance imaging studies for a positive relationship between physical activity and cartilage volume and strong evidence for an inverse relationship between physical activity and cartilage defects.
Conclusions: This systematic review found that knee structures are affected differently by physical activity. Although physical activity is associated with an increase in radiographic osteophytes, there was no related increase in joint space narrowing, rather emerging evidence of an associated increase in cartilage volume and decrease in cartilage defects on magnetic resonance imaging. Given that optimizing cartilage health is important in preventing osteoarthritis, these findings indicate that physical activity is beneficial, rather than detrimental, to joint health.

Introduction

The promotion of physical activity is a major public health initiative in western countries worldwide. It is well recognized that physical activity is beneficial in the management of numerous major health problems, including cardiovascular disease, mental illness, and obesity.^[31,43] However, the influence of physical activity on the development and progression of osteoarthritis (OA), particularly on weight-bearing joints such as the knee, is unclear. Given the prevalence of OA is predicted to increase in the coming decades and physical activity is being highly promoted,^[48] it is important that we understand the effect of physical activity on the health of the knee joint.

Although a large number of epidemiological studies have examined the relationship between physical activity and knee OA, the results are conflicting. Not only is there evidence to suggest that physical activity is detrimental to the knee joint^[12,40] but studies have also reported physical activity to have no effect^[17,27] and even be beneficial to joint health.^[13,36] A previous systematic review by Vignon et al.^[45] concluded that sport and recreational activities are risk factors for knee OA and that the risk correlates with the intensity and duration of exposure. Although this systematic review investigated a broad range of different types of activity, including daily life, exercises, sports, and occupational activities, only the results of six studies that examined sports activity were retained in the review after evaluation.

Moreover, although the knee joint is a complex, synovial joint consisting of a variety of different structures, and epidemiological studies have assessed the effect of physical activity on osteophytes,^[26,33] joint space width (as a surrogate measure of cartilage thickness),^[27,41,42] and subchrondral bone,^[46] no systematic review has summarized the effect of physical activity on individual joint structures. Given that previous studies have reported the development of osteophytes with physical activity, but no effect on joint space narrowing,^[40] it may be hypothesized that physical activity may have different effects on structures within the knee joint. The aim of this systematic review was to examine the effect of physical activity on the health of specific joint structures within the knee joint.

For further information: http://www.medscape.com/viewarticle/737716?sssdmh=dm1.702843&src=journalnl