Introduction Plantar fasciitis (PF) is a frequently diagnosed condition. Lifetime incidence of PF is 10%. Operation is normally only considered in PF that is refractory for non-surgical treatment. We hypothesised that operation is useful as primary treatment of PF.

Materials and methods 30 consecutive patients (age 20–65 years) with PF for more than 3 months and ultrasound thickness above 4.0 mm were after informed consent randomised to 1) conservative treatment with training and corticosteroid injection (best conservative treatment); 2) endoscopic 2-incision technique of partial fasciotomy and heel spur removal. Patients were evaluated at entry, 3, 6, 12 and 24 months with the Foot Function Index (FFI, range 0–230) and pain during activity on a 100 mm VAS score (VAS-activity). FFI at 6 and 12 months were defined a-priory as primary endpoints.

Results We found no intergroup difference at baseline or at 3 and 6 months. Endoscopic operation were significantly better for the primary endpoint at 12 months in FFI (p=0.033) compared to non-surgical treatment, and at 24 months there were still a strong tendency in favour of operation in FFI (p=0.06). VAS-activity was without intergroup differences at 12 month, but at 24 months we found a significant intergroup difference (p=0.001) in favour of operation. Both groups improved significantly over time. No severe complications were observed in any of the groups.

Conclusions This is the first study to prove a beneficial effect of operation for plantar fasciitis after 1 and 2 years compared to best conservative practice in a randomised controlled trial.