Weight-bearing status may influence rates of radiographic healing following reamed, intramedullary fixation of diaphyseal femur fractures

OBJECTIVE: To investigate the effect of weight-bearing status on radiographic healing of diaphyseal femur fractures. DESIGN: Retrospective 1:1 matched cohort study. SETTING: Single-level 1 trauma center. PARTICIPANTS: One-hundred forty-four (N = 154) patients matched 1:1 in non-weight bearing (NWB) and weight-bearing as tolerated (WBAT) groups. INTERVENTION: Non-weight bearing following reamed, statically locked intramedullary fixation of diaphyseal femur fracture, generally due to concurrent lower extremity fracture. MAIN OUTCOME MEASUREMENT: Postoperative radiographic healing using modified Radiographic Union Scale for Tibia fractures (mRUST) scores. RESULTS: Groups were well matched on age, sex, race, prevalence of tobacco and alcohol use, diabetes mellitus status, Injury Severity Score, fracture pattern and shaft location, vascular injury, open fracture prevalence, and operative characteristics. Radiographic follow-up was similar between groups (231 vs 228 days, P = .914). At 6 to 8 weeks status post intramedullary fixation, the median mRUST score in the NWB group (9) was lower than that of the WBAT group (10) (mean: 8.4 vs 9.7, P = .004). At 12 to 16 weeks, the median mRUST in the NWB group (10) was again lower than the WBAT group (12) (mean: 9.9 vs 11.7, P = .003). The median number of days to 3 cortices of bridging callous was 85 in the WBAT group, compared with 122 in the NWB group (P = .029). Median time to mRUST scores of 12 (111 vs 162 days, P = .008), 13 (218 vs 278 days, P = .023), and 14 (255 vs 320 days, P = .028) were all longer in the NWB group compared with the WBAT group. CONCLUSIONS: Non-weight bearing after intramedullary fixation of diaphyseal femur fractures delays radiographic healing, with median time to 3 cortices of bridging callous increased from 85 days in WBAT groups to 122 days in NWB groups. These results provide clinicians with an understanding of the expected postoperative course, as well as further support the need to expeditiously advance weight-bearing status. Level of Evidence: IV