Hip Precautions Not Meaningful After Hemiarthroplasty Due to Hip Fracture. Cluster-randomized Study of 394 Patients Operated With Direct Anterolateral Approach.

394 participants with Garden III-IV (20) femoral neck fractures treated with hemiarthroplasty participated in a cluster-randomised study during 2010-2014 at Skane University Hospital, Malmö. Inclusion criteria was an acute displaced femoral neck fracture treated with a bipolar hemiarthroplasty inserted via a direct lateral approach in supine position. All such participants were considered potential study participants and invited to the study by an occupational therapist (OT), within the first postoperative days. If the participants was not capable of making decisions, relatives were asked. The study was approved by The Regional Ethical Review Board in Lund on condition that all participants, regardless of group, or their next-in-kin gave written consent (Dnr 2009/754).

The four wards managing hip fracture patients were assigned either to provide the standard postoperative hip precaution regime or the non-precaution regime during the entire study period. In two of the wards, the precaution group (PG) had standard postoperative hip precautions included limited flexion of the hip to 90° (avoid reaching down to toes or bringing knee up beyond 90°) and limited adduction of the hip (avoid sleeping on side and avoid crossing legs at knees or ankles). The mandatory assistive equipment to use for at least 3 months were reacher and stocking application aid. The participants were instructed only to use elevated chair, bed and toilet in order not to flex more than 90° in the hip. For the same reason a brace over the knee was prescribed for 6 weeks, particularly in participants with cognitive limitations.

The non-precaution group (NPG) consisted of participants treated in the other two wards. Participants in the NPG had no restrictions on mobility, i.e. they were encouraged to move freely during the recovery phase and assistive equipment were prescribed only if needed.

Admittance of a participant to either ward was only decided by any available bed, i.e. the health status of the participants or any other factors did not influence placement of participants. The investigators recruited 168 participants to the PG and 226 participants to the NPG.

The initial power analysis was directed towards dislocation rate as primary outcome. When designing the trial, the investigators had a dislocation rate of 0.5% at the department. The investigators calculated that, in order to detect an increase of 3.5%, i.e. a clinical relevant effect, the investigators needed 340 participants in each group (p<0.05). The original plan was to additionally monitor PROM in the first 400 participants, and then dislocation rate only in the remaining 400. In order to monitor the safety of the study, the investigators also calculated a non-inferiority model, with warning levels at which the investigatorswould discontinue the study. This model was based on 200 participants in each group. Due to recruitment difficulties, the study was closed after inclusion of approximately 400 participants.