Purpose: To determine if early MRI diagnosis in the acutely injured knee affects management, use of resources and patient satisfaction compared to conventional management with physiotherapy.

Methods: Patients referred to fracture clinic with acute knee injury in whom a specific clinical diagnosis could not be made were randomised to one of two groups. The MRI group had a scan within 2 weeks and were then reassessed in clinic with management according to the results. The control group received physiotherapy and then reassessed. Patients were assessed in clinic on presentation, at 2 weeks and then by a telephone questionnaire at 3 months. Electronic medical records were also reviewed.

Results: 48 patients were recruited in total: 23 in the MRI group (78.2% male, 21.8% female) and 25 in the control group (68% male, 32% female). The mean age was similar in the two groups (29 years (range 18–61) vs. 30 years (18–50)). The MRI group had significantly less physiotherapy appointments (5 ± 3.42 vs. 2.52 ±1.93, p=0.003) on average until definitive treatment but not outpatient appointments (2.72 ± 1.1 vs. 2.43 ±0.66, p=0.27). Median time to surgery was less in the MRI group (138 (31–199) vs.180 days (33–826) vs.) but not statistically significant (p=0.19). A similar number of patients returned to work in both groups (82.6% vs. 76%) but the MRI group had less time off work (15.82 ±22.26 vs. 20.56 ±25.38 days, p=0.48) and statistically better satisfaction scores (2 ±2.68 vs. 3.5 ±2.75, p=0.048) than the control group.

Conclusion: We have shown that early MRI in acute knee injury can provide early diagnosis of internal derangement and therefore allow targeted treatment. These patients had significantly less physiotherapy appointments and less time off work which may offset the cost of the MRI. Moreover these patients were significantly more satisfied with the service.