We analysed the functional outcome of 27 humeral shaft fractures treated non-operatively in our unit between 1999 and 2000.

The mean age of the 20 men and seven women was 37.9 years (20 to 65). Ten fractures occurred in motor vehicle accidents, eight in falls and three in assaults. The remaining six were gunshot injuries. There were 18 closed fractures and nine grade-I compound fractures. Nine fractures were oblique, eight transverse, eight comminuted and two spiral. There was radial nerve palsy in 12 patients, and one poly-trauma patient had a concomitant brachial artery injury. All patients were treated initially by closed reduction and U-slab immobilisation.

Radiological union was achieved in 12 patients (44.4%) at a mean of 11 weeks. Fixation by compression plating was necessary in 51.9%, treating delayed union in eight patients, radial nerve palsy in three, nonunion in one, a brachial plexus injury in one and polytrauma in one. One patient (3,7%) developed a pseudarthrosis and refused surgery.

We assessed pain, range of movement of adjacent joints, ability to perform activities of daily living and work. In patients treated by U-slab immobilisation, the mean time to full functional recovery was 18 weeks. Those who underwent surgery achieved full functional recovery a mean of eight weeks later.

Transverse and short oblique fractures are prone to delayed union and we recommend they be treated by primary internal fixation.