Studies on exercise as a possible cause of knee OA, in order of quality of evidence
| STUDY | STUDY TYPE | N (FOLLOW-UP, %) | DURATION | ACTIVITY | OUTCOME ON KNEE OA | COMMENTS |
|---|---|---|---|---|---|---|
| Framingham offspring (Felson et al29) | Cohort | 1705 (75) | 9 y | Recalled level of activity | No increase in OA; obesity did not increase OA risk | History, examination, and x-ray findings Ongoing data collection reduced recall bias Reported patellofemoral disease Injury reported |
| Framingham (McAlindon et al17) | Cohort | 473 (99) | 9 y | Recalled level of activity | Increased incidence with heavy physical activity | History, examination, and x-ray findings Ongoing data collection reduced recall bias Injury reported |
| Chingford (Hart et al12 ) | Cohort | 1003 | 4 y | Walking, jogging, or sports | No increased risk with greater activity levels | X-ray findings and reported pain evaluation Women only Self-reported exercise |
| Stanford University (Fries et al,28 Chakravarty et al,30 Wang et al,31 Lane et al,32 Lane et al33) | Cohort | 113 (87) | 18 y | Running | No increase in OA; reduced disability; marked divergence in morbidities of all types compared with controls Careful evaluation of x-ray findings and symptoms | Careful evaluation of function and disability Runners were self-selected Very specific for runners of high education and socioeconomic status |
| Panush et al34,35 | Cohort | 35 (100) | 8 y | Running | No increase in OA | Diagnosis by symptoms and x-ray findings |
| Cooper Clinic (Cheng et al13) | Case control | 16 961 | 17 y | Recalled level of activity | Increase for young men exercising > 20 h/wk; increase for obese women and obese young men | No record of injury Diagnosis of OA given to patient by another physician Level of exercise by subjective recall No evaluation of function Subjects all of high socioeconomic status |
| Sohn and Micheli36 | Case control | 791 | 2–55 y | Running, swimming | Runners had no increase in lower extremity pain or arthritis surgery compared with swimmers | Compared hip or knee pain in runners and swimmers Arthritis diagnosed only by history of knee or hip surgery |
| Lane et al37 | Case control | 863 | NA | Running | Runners showed less muscle and joint disability and increased functional capacity | Study of lower extremity disability related to knees but not specific to knee OA |
| Framingham (Hannan et al38) | Case control | 1404 | NA | Level of activity | No increase in OA with increased level of activity | History, examination, and x-ray findings Data collection reduced recall bias Injury reported |
| Spector et al39 | Case control | 1058 | NA | Elite tennis players, runners | Increased OA in elite athletes, but no increase in symptoms | Women only Diagnosis based on x-ray findings only |
| Schmitt et al40 | Case control | 40 | NA | Elite marathon runners | No increase in OA | Good clinical and x-ray definition of OA |
| Kujala et al41 | Case control | 2448 | NA | Elite athletes | Athletes had slightly higher risk of hospital admission | Hospital admission for any sign of OA Examination of records only Control group was incomplete |
| Sutton et al27 | Case control | 1080 | NA | Recalled level of exercise | Increased risk only with injury | Diagnosis and level of exercise self- reported |
| Kujala et al21 | Cross sectional | 117 | NA | Sports | Increased OA in soccer players and weight lifters; increased risk with obesity, injury, and work history of heavy lifting | Diagnosis based on recorded history, physical and x-ray findings Men only |
| Konradsen et al42 | Cross sectional | 30 | NA | Running | No increase in OA | Diagnosis based on clinical and x-ray findings |
| Roos et al43 | Cross sectional | 858 | NA | Soccer | Increased OA in elite athletes only | No symptoms reported X-ray diagnosis only |
| Szoeke et al44 | Cross sectional | 224 | NA | Recalled level of exercise | Increased risk with obesity and in those very active in youth | Women only Exercise self-reported Diagnosis based on x-ray findings only |
| McDermott and Freyne22 | Cross sectional | 20 | NA | Running | Strong association of OA with trauma and genu varum | Men only |
Questionnaire, physical examination, and x-ray findings
NA—not applicable, OA—osteoarthritis.