PRCT multicenter study to evaluate non-operative treatment protocols for treating ER-stress negative unimalleolar Weber-B type fibular fractures. Groups are: 1. 3 weeks in a removable splint 2. 3 weeks in a cast and 3. 6 weeks in a cast. Follow-up visits at 3, 6 and 12 weeks and after 1 and 2 years after injury. In each time X-rays laterally and mortise projections. Ankle functional outcome questionnaires: Olerud-Molander score, FAOS RAND-36 and VAS in follow up-visits 6 and 12 weeks and 1 and 2 year.

Prospective randomized controlled multicenter study to evaluate non-operative treatment protocols for treating ER-stress negative unimalleolar Weber-B type fibular fractures. Groups are: 1. 3 weeks in a removable splint 2. 3 weeks in a cast and 3. 6 weeks in a cast. Follow-up visits at 3, 6 and 12 weeks and after 1 and 2 years after injury. In each time X-rays laterally and mortise projections. Ankle functional outcome questionnaires: Olerud-Molander score, FAOS RAND-36 and VAS in follow up-visits 6 and 12 weeks and 1 and 2 year.

Inclusion Criteria:

• Stable Weber-B type fibula fracture
• ER-stress negative
• 16 or over years old
• Willingness to participate on study proved by a signature and date
• Walking without aid before accident
• Treatment started within 7 days from injury

Exclusion Criteria:

• Prior ankle fracture or significant fracture in the area of ankle or leg
• Bilateral ankle fracture
• Pathological fracture
• Diabetes mellitus or an other significant periferial neuropathy
• municipality of Residence in some else catchment area than Oulu university hospital or Tampere university hospital
• Patient's understanding or co-operation inadequate