Prediction of outcome after humeral diaphyseal fracture

The aim of this study is to examine the demographic factors, functional outcome and radiological data to predict the outcome of humeral diaphyseal fractures.

We performed a prospective study on a consecutive series of 110 patients of 16 years or over, who had sustained a humeral diaphyseal fracture. There were 42 males and 68 females, with an average age of 59 years (range 16-93 years). A total of 72% sustained low-energy injuries, and 89 patients (81%) were primarily treated non-operatively. Shoulder function was assessed using the Neer's and Constant's scores at 8 weeks, 3 months, 6 months and 1 year after injury. Muscle strength was determined isokinetically using a Biodex System 2 dynamometer. Non-union was defined as a failure to bridge at least three cortices and persistence of tenderness or mobility at the fracture site 16 weeks after fracture.

Sixteen patients (17%) had non-union at 16 weeks, while 80 had achieved union and a further 14 were lost to follow-up. After stepwise multiple linear regression was performed to isolate independent factors affecting outcome, only the presence of a proximal diaphyseal fracture was found to predict non-union along with a poor Neer's score at 8 and 12 weeks. Poor Neer's scores could be predicted at 26 weeks by age (P<0.05), previous stroke (P<0.001) and non-union (P<0.001). At 52 weeks both age (P<0.01) and previous stroke (P<0.01) were independently predictive of poorer Neer's scores. Malunion of any degree had no detectable effect on function.

Our results indicate that non-union of humeral diaphyseal fractures can be predicted in the presence of a proximal third fracture with a Neer's score of less than 45 by 12 weeks after fracture. Early surgery improves early function, but this is not a lasting effect. Poor shoulder function is predicted by increasing age, proximal third fractures and non-union. We recommend that surgery to promote union be considered at 12 weeks after fracture in fit patients with fractures of the proximal third of the humerus, poor Neer's scores and no radiographic progression to union.