The Effect of Hypovitaminosis D and Vitamin D Supplementation on Fracture Nonunion Rates (VitD)

• Healed fracture [ Time Frame: up to 15 months post-surgery ] [ Designated as safety issue: No ]
  A fracture will be considered healed if (1) the patient follows-up at any time prior to 15 months post-surgery (post-injury for nonoperatively treated patients), (2) the patient has no tenderness to palpation at the fracture site, AND (3) a group of 3 independent reviewing orthopaedic surgeons agree that it is healed based on the most recent radiographs and any other available imaging studies.
  
  

• Nonunion [ Time Frame: 6-15 months post-injury ] [ Designated as safety issue: No ]

  A fracture will be considered to result in nonunion when:

  1. A group of 3 independent reviewing orthopaedic surgeons agree that a nonunion has resulted based on the earliest 9 to 15-month follow-up radiographs and other prior imaging studies.
  2. At a follow-up of >6 months, a group of 3 independent reviewing orthopaedic surgeons agree that there has been regression or no progression of healing on serial radiographs for at least 3 months. (11) OR
  3. The patient is taken to the operating room to undergo a procedure based on a diagnosis of nonunion. No independent radiograph review is necessary. This does not include delayed operative intervention based on a trial of nonoperative treatment with patient dissatisfaction (e.g. due to continued pain or malalignment). Such patients will be analyzed with their follow-up time from the time of operation.
  
  

• Lost to Follow-Up [ Time Frame: up to 15 months post-surgery ] [ Designated as safety issue: No ]
  Patients will be deemed lost-to-follow-up if they have not yet met the criteria for healed fracture or nonunion and their last follow-up visit is <9 months and >15 months post-surgery (or post-injury for nonoperatively treated patients). This gives them a 6 month window for a final follow-up appointment and 9 months to attempt to heal the fracture. (If indefinite follow-up were allowed, then patients earlier in the study would have more time for follow-up, which may confound the data.) Data from patients who are lost-to-follow-up will be excluded from the final analysis. Patients who follow-up between 9 and 15 months will be included in the analysis regardless of prior compliance with follow-up.
  
  

Vitamin D plays an important role in maintaining calcium and phosphate balance in the body and is important for maintenance of bone formation, remodeling, and healing. An extensive literature search indicates that although there is evidence that vitamin D deficiency is associated with fracture risk, there is no evidence of the role of vitamin D deficiency in subsequent failure to heal. This study aims to determine whether the relationship of vitamin D deficiency to nonunion is clinically relevant by showing whether its treatment can decrease the risk of nonunion. We will determine the incidence of nonunion in patients with untreated hypovitaminosis D and calculate the relative and absolute risk reductions for nonunion with normal vitamin D levels compared to untreated hypovitaminosis D. We will also calculate the relative and absolute risk reductions for nonunion with hypovitaminosis D treated with vitamin D supplementation compared to placebo.