Hip Pelvis.  2017 Dec;29(4):277-285. 10.5371/hp.2017.29.4.277.

Risk Factors for Neck Shortening in Patients with Valgus Impacted Femoral Neck Fractures Treated with Three Parallel Screws: Is Bone Density an Affecting Factor?

• Sung YB
• Jung EY
• Kim KI
• Kim SY

• KMID: 2424255
• DOI: http://doi.org/10.5371/hp.2017.29.4.277

Abstract

PURPOSE
The purpose of this study is to analyze the relationship between significant femoral neck shortening (SFNS) and bone density after three parallel screw fixation in valgus impacted femoral neck fracture, and to analyze the risk factors for SFNS.
MATERIALS AND METHODS
This is retrospective study of 83 patients. We performed univariate analysis for patient information, bone density, fracture configuration and screw position divided into SFNS group (n=13) and non-SFNS group (n=70) and performed multivariate analysis using logistic regression model. We also analyzed the relationship between SFNS and complications such as osteonecrosis of femoral head and nonunion.
RESULTS
There was a significant difference in age, screw non-parallelism and bone mineral density of intertrochanteric and total hip area in the univariate analysis between the two groups (P < 0.05). In multivariate analysis, old age (odds ratio [OR], 1.10; 95% confidence interval [CI], 1.03-1.21) and screw non-parallelism (OR, 2.95; 95% CI, 1.44-6.59) were significant risk factors for SFNS. The incidence of SFNS was significantly higher in the complication group (P=0.027).
CONCLUSION
Bone density did not significantly affect SFNS in valgus impacted femoral neck fractures treated with three parallel screws. The risk factors of SFNS were old age and screw non-parallelism. Therefore, we recommend using other fixation method to prevent SFNS in older ages and making the screw position as parallel as possible when performing screw fixation in valgus impacted femoral neck fracture.

Keyword

Femoral neck fractures; Valgus impacted; Neck shortening; Bone density; Risk factors

MeSH Terms

Bone Density*
Femoral Neck Fractures*
Femur Neck*
Head
Hip
Humans
Incidence
Logistic Models
Methods
Multivariate Analysis
Neck*
Osteonecrosis
Retrospective Studies
Risk Factors*

Figure

• 

  Fig. 1 The flowchart shows patient selection and exclusion criteria. BMD: bone mineral density.

• 

  Fig. 2 Anteroposterior plain radiographs show how to measure the progression of femoral neck shortening. (A) This is immediate post-operative plain radiograph of a 75 year old woman. Articulo-trochanteric distance (ATD) index is the ratio of ATD of fractured side (b) to unfractured side (a). (B) At 6 months after surgery, ATD index is the ratio of (d) to (c). Progression of femoral neck shortening is expressed as a percentage decrease of ATD index between two periods. Percentage decrease of ATD index is obtained by the following formula: Percentage decrease of ATD index (%)=[(b/a–d/c)/b/a]×100.

• 

  Fig. 3 This shows the region of interest (ROI) in bone mineral density measurement using dual energy X-ray absorptiometry. (A) ROI of total hip is the sum of ROI of neck (1), greater trochanter (2), and intertrochanter (3). (B) This shows which ROI each of the three parallel screws passes through.

• 

  Fig. 4 This figure shows the plot for odds ratio for the final model of multiple logistic regression. CI: confidence interval.

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