To evaluate the incidence of femoral neck fracture (FNF) after removal of a compression hip screw (CHS) without trauma and to determine the risk factors for this type of fracture.
Retrospective study of consecutive patient series.
University teaching hospital.
Sixty-seven patients with a mean age of 65.3 years (45 women and 22 men).
A total of 67 implants were removed in the presence of bony consolidation of the fracture site; most of them were due to hardware pain.
MAIN OUTCOME MEASURES
The incidence of FNF after a CHS removal, clinical parameters (age, gender, bone mineral density, body mass index, and fracture stability), and radiologic parameters (the femoral neck-shaft angle, femoral neck width, distance between thread of lag screw, and neck cortex). Univariate analysis was performed for those parameters of the fracture group and the nonfracture group. To assess which variables were associated with FNF, a multiple logistic regression was used.
Six (9.0%) FNFs occurred within 1 month after a CHS removal. The mean anterior and lateral neck widths were significantly smaller, and the mean anterior and inferior thread-to-cortex distances were significantly shorter in the fracture group compared with the nonfracture group. The risk factor significantly associated with FNF was the inferior thread-to-cortex distance (odds ratio, 0.462; 95% confidence interval, 0.217-0.988).
CHS should not be removed routinely due to the risk of FNF. Furthermore, attention should be paid to at-risk patients with a hip screw positioned close to the inferior femoral neck cortex.
LEVEL OF EVIDENCE
Prognostic level II.
8 Figures and Tables
FIGURE 1. Radiologic parameters measured on the AP radiograph. (a) Distance of thread-to-superior cortex, (b) distance of thread-to-inferior cortex, (c) anterior neck width, and (d) the outer diameter of the barrel of a CHS system is 12.5 mm.
TABLE 1. Demographic and Clinical Characteristics
FIGURE 2. Radiologic parameters measured on the lateral radiograph. (a) Distance of thread-to-anterior cortex, (b) distance of thread-to-posterior cortex, (c) lateral neck width, and (d) the outer diameter of the barrel of a CHS system is 12.5 mm.
TABLE 2. Multiple Logistic Regression Results (P , 0.15, Stepwise Selection)
FIGURE 3. Radiograph made after a CHS removal (A). Radiograph made at 9 days postoperatively, showing a displaced FNF (B).
TABLE 3. Demographic and Clinical Characteristics (Subgroup = Female)
FIGURE 4. Radiograph made after a CHS removal (A). Radiograph made at 7 days postoperatively, showing an incomplete FNF (B).
TABLE 4. Multiple Logistic Regression Results in the Female Group (P , 0.15, Stepwise Selection, AIC = 29.212)
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