Long-term impact of acute knee injury with hemarthrosis: Osteoarthritis incidence and patient-reported outcomes in a large consecutive cohort over 12 years.

OBJECTIVE

To estimate the 12-year risk of radiographic and/or symptomatic knee osteoarthritis following different MRI-confirmed soft-tissue knee injuries.

DESIGN

Prospective cohort study including 814 (70 ​%) of 1129 consecutive patients after acute knee trauma with hemarthrosis in a single hospital. Injuries were classified by sub-acute knee MRI. Follow-up comprised bilateral knee radiography and Knee injury and Osteoarthritis Outcome Score. The main outcomes were radiographic and symptomatic knee osteoarthritis. We estimated differences between injury types and injured versus contralateral knees.

RESULTS

The incidence proportion of radiographic knee osteoarthritis was 34 ​% (95 ​% confidence interval 30 to 37) in injured knees and 18 ​% (15, 20) in contralateral knees. Knees with hemarthrosis but no structural injury developed radiographic osteoarthritis and symptomatic osteoarthritis in 6 ​% and 4 ​%, respectively, as compared to 36 ​% and 21 ​% of those with structural injury, with risk ratios (95 ​% confidence interval) of 8 (3, 21) for radiographic osteoarthritis and 6 (2, 20) for symptomatic osteoarthritis. The risk ratio of tibiofemoral osteoarthritis in the injured knee compared to the contralateral knee was 2.2 (1.7, 2.8), with the highest ratio of 3.1 (2.1, 4.6) observed after combined anterior cruciate ligament (ACL) and meniscus injury. Overall, 81 ​% (78, 84) reported satisfaction with their knee function, though satisfaction was lower following patellar dislocation.

CONCLUSIONS

Structural soft-tissue knee injury doubled the risk of radiographic and symptomatic knee osteoarthritis versus the contralateral knee over 12 years with significant variation based on injury type. ACL rupture combined with meniscus tear conferred the highest risk while hemarthrosis alone the lowest.