The effect of comorbidity and duration of nonunion on outcome after surgical treatment for nonunion of the humerus.

The purpose of our study was to assess the effect of comorbidity and duration of nonunion on the general health status and joint-specific outcome of a group of patients treated for nonunion of the humeral shaft. We identified 25 consecutive patients with nonunion of the humeral shaft, all treated with compression plating and bone grafting. Twenty-one patients returned for a comprehensive assessment including completion of the SF 36 Health Status Survey and determination of the Constant shoulder and Morrey elbow scores. Thirteen patients had > or = 1 comorbid conditions. Eleven patients had a nonunion of > 8 months' duration, and 10 had a nonunion of < 8 months' duration. Follow-up at a mean of 42 months (range 12 to 99 months) revealed that all nonunions united an average of 5 months after surgery. The mean Morrey elbow score was 94, Constant shoulder score 82, and "global" SF 36 score 59.4. The physical portion of the SF 36 score correlated well with the Constant and Morrey scores (p = 0.047 and p = 0.027, respectively). The presence of comorbid factors had a significant negative effect on the SF 36 scores (p = 0.001) but no effect on joint-specific Morrey or Constant scores. The duration of nonunion had no effect on SF 36 or joint-specific scores. Although the reliability of the SF 36 is illustrated by the close correlation between its "physical function" portion and standard (joint-specific) outcome measures, comorbidity has a significant negative effect on overall scores. This must be considered when such tools are used for assessment of orthopaedic intervention.