Handolin 2005a.

Study characteristics
Methods	Placebo‐controlled RCT, parallel design.
Participants	Setting: Helsinki University Central Hospital, Finland. Study dates: September 2002 to March 2003. Size: 22 participants, 11 in each arm. Baseline characteristics (intervention):  Age, years (range): 37.5 (18 to 54) years Gender, M/F: 9/2  Hospital stay, mean (range): 2.2 (2 to 3) years Operating time, mean (range): 24.2 (14 to 39) minutes Screw length, mean (range): 36.4 (35 to 40) mm US device used, mean (range): 35.6 (14 to 42) days Baseline characteristics (control): Age, years (range): 45.5 (26 to 59) years Gender, M/F: 6/5  Hospital stay, mean (range): 2.1 (2 to 3) days Operating time, mean (range): 24.3 (14 to 35) minutes Screw length, mean (range): 38.2 (35 to 45) mm US device used, mean (range): 40.2 (38 to 42) days Inclusion criteria: people aged between 18 and 65 years with displaced Weber B fractures of the lateral malleolus. Exclusion criteria: widening of the distal tibiofibular joint; open fracture; inability to co‐operate with the requirements of the trial.
Interventions	General surgical details: participants underwent open reduction and internal fixation with a 4.5 mm self‐reinforced poly‐L‐lactic acid screw. 6‐week period of immobilisation with a removable soft cast. At 2 weeks, partial weightbearing was allowed with full weightbearing at 4 weeks. Intervention details: participants self‐administered daily ultrasound treatment for 20 minutes from the third to ninth postoperative weeks directly over the fracture marked with an intra‐operatively placed marker. Appropriate contact between the probe and the skin was maintained with standard ultrasound coupling gel. The ultrasound signal was composed of a 200 µs burst of 1.5 MHz sine waves, with a repetition rate of 1 kHz and a spatial average intensity of 30 mW/cm². Control details: participants in the control group were given a similar treatment regimen but had an externally similar sham machine instead.
Outcomes	Reported outcomes and time points: Follow‐up schedule: baseline, 2, 6, 9 and 12 weeks postoperatively Primary outcome: fracture healing using line visualisation and callus formation on plain radiographs  Secondary outcomes: endosteal united fracture line. In addition, fracture healing was assessed by multiplanar CT.
Notes	Funding: no funding declared Conflicts of interest: no conflict of interest reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "prospective, randomized, double‐blind and placebo controlled study".  Comment: study authors do not report on the methods of sequence generation
Allocation concealment (selection bias)	Unclear risk	The method of allocation concealment is not reported
Blinding of participants and personnel (performance bias) Objective measures	Low risk	Quote: "The patients were randomly provided with either an active or sham ultrasound device in a double‐blind manner". Comment: likely to be the same device but placebo devices were deactivated.
Blinding of outcome assessment (detection bias) Objective measures	Low risk	Quote: "All clinical and radiographic analyses were performed by observers blinded to the ultrasound treatment; the code indicating whether it was an active or a sham device being used was broken after word"
Incomplete outcome data (attrition bias)	High risk	Some participant loss in both groups In this small study, we judged that the risk of attrition bias was high
Selective reporting (reporting bias)	Unclear risk	No protocol or clinical trials register available.
Other bias	Low risk	No additional biases identified