Objective:

The purpose of this study is to report the union rate and time to union for acute non-displaced scaphoid waist fractures treated with a short arm thumb spica cast.

Methods:

A database was searched (2006-2013) to identify acute undisplaced scaphoid waist fractures. Cases that were not given a trial of casting were excluded (n= 33). X-rays, CT scans and health records for each patient were reviewed to extract data.

Results:

172 patients met inclusion criteria. There were 138 males, 34 females, the mean age was 30±16 years. The union rate was 99.4%(1 nonunion/172 subjects). The mean time to union was approximately 7.5 weeks (53±37 days). Energy of injury, age or gender did not affect union rates or time to union. Cysts did not affect the union rate (p= 0.73) but patients with cystic resorption along the fracture line required approximately 10 weeks for union (69±60 days) compared to 7 weeks (51±34 days) for those without cysts (p= 0.05). Diabetes did not affect the union rate (p= 0.81) but was found to increase the risk of delayed union (p= 0.05). There was a weak, but statistically significant correlation between the number of days before the fracture was casted and the length of time needed to achieve union (r= 0.27, p= 0.001).

Conclusion:

Non-displaced scaphoid waist fractures have a high healing rate with appropriate identification and immobilization. Follow-up CT scans to assess healing can identify union within a shorter time frame (~ 7 weeks) than previously reported in the literature.