| Summary: | Abstract Background Zones 2 and 3 fifth metatarsal fractures are often treated with intramedullary fixation due to an increased risk of nonunion. A previous 3-dimensional (3D) computerized tomography (CT) imaging study by our group determined that the screw should stop short of the bow of the metatarsal and be larger than the commonly used 4.5 millimeter (mm) screw. This study determines how these guidelines translate to operative outcomes, measured using Patient-Reported Outcomes Measurement Information System (PROMIS) Physical Function (PF) and Pain Interference (PI) surveys. Radiographic variables measuring the height of the medial longitudinal arch and degree of metatarsus adductus were also obtained to determine if these measurements had any effect on outcomes. And lastly, this study aimed to determine if morphologic differences between males and females affected surgical outcomes. Methods We retrospectively identified 23 patients (14 male, 9 female) who met inclusion criteria. Eighteen patients completed PROMIS surveys. Preoperative PROMIS surveys were completed prior to surgery, rather than retroactively. Weightbearing radiographs were also obtained preoperatively to assist with surgical planning and postoperatively to assess interval healing. Correlation coefficients were calculated between PROMIS scores and repair characteristics (hardware characteristics [screw length and diameter] and radiographic measurements of specific morphometric features). T tests determined the relationship between repair characteristics, PROMIS scores, and incidence of operative complications. PROMIS scores and correlation coefficients were also stratified by gender. Results The average screw length and diameter adhered to guidelines from our previous study. Preoperatively, mean PROMIS PI = 57.26±11.03 and PROMIS PF = 42.27±15.45 after injury. Postoperatively, PROMIS PI = 44.15±7.36 and PROMIS PF = 57.22±10.93. Patients with complications had significantly worse postoperative PROMIS PF scores (p=0.0151) and PROMIS PI scores (p=0.003) compared to patients without complications. Females had non-significantly worse preoperative and postoperative PROMIS scores compared to males and had a higher complication rate (33 percent versus 21 percent, respectively). Metatarsus adductus angle was shown to exhibit a significant moderate inverse relationship with postoperative PROMIS PF scores in the overall cohort (r=−0.478; p=0.045). Metatarsus adductus angle (r=−0.606; p=0.008), lateral talo-1st metatarsal angle (r=−0.592; p=0.01), and medial cuneiform height (r=−0.529; p=0.024) demonstrated significant inverse relationships with change in PROMIS PF scores for the overall cohort. Within the male subcohort, significant relationships were found between the change in PROMIS PF and metatarsus adductus angle (r=−0.7526; p=0.005), lateral talo-1st metatarsal angle (r=−0.7539; p=0.005), and medial cuneiform height (r=−0.627; p=0.029). Conclusion Patients treated according to guidelines from our prior study achieved satisfactory patient reported and radiographic outcomes. Screws larger than 4.5mm did not lead to hardware complications, including screw failure, iatrogenic fractures, or cortical blowouts. Females had non-significantly lower preoperative and postoperative PROMIS scores and were more likely to suffer complications compared to males. Patients with complications, higher arched feet, or greater metatarsus adductus angles had worse functional outcomes. Future studies should better characterize whether patients with excessive lateral column loading benefit from an off-loading cavus orthotic or plantar-lateral plating.
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