OBJECTIVES:
To determine whether patients with unexplained nonunions, patients with a history of multiple low-energy fractures with at least one progressing to a nonunion, and patients with a nonunion of a nondisplaced pubic rami or sacral ala fracture would have an underlying metabolic or endocrine abnormality that had not been previously diagnosed.

DESIGN:
Case series.

SETTING:
Tertiary referral center.

PATIENTS AND INTERVENTION:
From a larger series of 683 consecutive patients with nonunion seen by us between January 1998 and December 2005, 37 patients were referred to 1 of 2 clinically practicing endocrinologists to undergo an evaluation for metabolic and endocrine abnormalities. The screening criteria were: 1) an unexplained nonunion that occurred despite adequate reduction and stabilization (and debridement in initially infected cases) without obvious technical error and without any other obvious etiology; 2) a history of multiple low-energy fractures with at least one progressing to a nonunion; or 3) a nonunion of a nondisplaced pubic rami or sacral ala fracture.

RESULTS:
In all, 31 of the 37 patients (83.8%, 95% CI: 71.3% to 93.8%) who met our screening criteria had one or more new diagnoses of metabolic or endocrine abnormalities. The most common newly diagnosed abnormality was vitamin D deficiency (25 of 37 patients; 68%). Other newly diagnosed abnormalities included calcium imbalances, central hypogonadism, thyroid disorders, and parathyroid hormone disorders. All newly diagnosed abnormalities were treated medically. Eight patients who underwent no operative intervention following the diagnosis and treatment of a new metabolic or endocrine abnormality achieved bony union in an average of 7.6 months (range, 3 to 12 months) following their first visit to the endocrinologist.

CONCLUSIONS:
Although our study does not prove a causal link between metabolic and endocrine abnormalities and either the development or healing of nonunions, 84% of the patients who met our screening criteria were found to have metabolic or endocrine abnormalities, and eight of our patients achieved bony union following medical treatment alone. All patients with nonunion who meet our screening criteria should be referred to an endocrinologist for evaluation because they are likely to have undiagnosed metabolic or endocrine abnormalities that may be interfering with bone healing.



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