A Study to Compare Two Different Managements After Ankle Surgery: Immediate and Delayed Weight-bearing.

The study population corresponds to the patients who may benefit from a post-operative rehabilitation protocol with immediate weight-bearing. Eligible lateral malleolar fractures are limited to Weber A and Weber B fractures, since they have a higher stability, after open reduction and internal fixation, compared to Weber C and Maisonneuve fractures. This higher stability gives the possibility to evaluate the benefit of the immediate weight-bearing protocol without safety concerns.

A power analysis was performed to estimate the required sample size to detect a significant difference in the OMAS score at 6 weeks between groups: the number of patients needed is 42 patients per group (84 patients overall) but, considering the risk of drop-outs, the investigators plan to enroll 20% more patients for a total of 100 patients.

The surgical operation will be carried out following the AO Foundation general and specific rules concerning the surgical treatment of malleolar fractures . In particular,an anatomical open reduction and internal fixation with one or two compression screws sustained by a neutralization third-tubular plate for simple fractures or a bridging third-tubular locking compression plate for multi-fragmentary fractures will be performed.

Postoperatively, patients who still meet the eligibility criteria will be randomized in 2 groups: immediate post-operative complete weight-bearing and complete weight-bearing delayed for 6 weeks.Immediate complete weight-bearing consists in the possibility to undergo all the everyday activities without limiting weight-bearing and without the use of walking aids (patients will wear an ankle brace, this will ensure the safety of the early recovery phases, protecting from dangerous movements while allowing the mobilization in the healthy range of movement). Delayed weight-bearing consists in the limitation of the weight-bearing to 20-30% of patient's total weight using crutches for the first 6 weeks after surgery (also patients of the control group will wear the ankle brace).

Subsequent follow-up visits are scheduled at 2, 6, 12 and 24 weeks after surgery. Patients with a fracture non-union radiologically confirmed at week 24 will be followed up until 48 weeks after surgery. Clinical assessments will be performed using subjective, objective and radiological evaluations. Safety will be monitored throughout the study.

Overall study duration will be 2 years and 6 months (2 years to reach the expected sample size and 6 months to complete the follow-up):

• change in subjective functional ankle recovery on the Olerud-Molander Ankle Score during the first 24 weeks after surgery [Time frame: baseline, week2, week 12 and week 24]
• Change form day of surgery in functional ankle disability on the Foot and Ankle Disability Index (FADI) during the first 24 weeks after surgery [Time frame: baseline, 2, 6, 12 and 24 weeks]
• Change form baseline in pain on the Numerical Rating Scale (NRS) [Time frame: baseline, 12 and 24 weeks]
• Daily pain and function [Time frame: 12 weeks]
• change in quality of life on the 36-Item Short Form Health Survey (SF-36 questionnaire). [Time frame: baseline, 2, 6,12 and 24 weeks]
• Return to previous daily activities on the Tegner activity level scale [Time frame: week 12 and week 24]
• Objective ankle functional recovery [Time frame: 6, 12, 24 weeks]
• Ankle joint flexibility [Time frame: 6, 12, 24 weeks]
• Objective activity level [Time frame: 24 weeks]
• Radiological assessment [Time frame: 24 weeks]
• Pain drug consumption [Time frame: 24 weeks]
• Patient satisfaction on the satisfaction Numerical Rating Scale (NRS scale) [Time frame: day of surgery, week 6, 12 and 24]