Can We Predict Sagittally Unstable Intertrochanteric Fractures That Require Direct Manipulation for the Reduction? Fracture Morphology Analysis

Purpose: Sagittally unstable intertrochanteric fracture (SUITF) is defined as posterior displacement of shaft fragment (posterior sagging) and presents a difficulty in achieving acceptable reduction in a closed manner on lateral view. Thus, this fracture pattern usually requires direct manipulation for reduction and preoperative detection is helpful for carrying out surgery. The purpose of the present study is to validate morphologic characteristics of SUITFs.

Methods: This retrospective review was performed between January 2017 and December 2020. We reviewed the data of patients with acute intertrochanteric fracture who underwent surgical treatment. A total of 382 patients were enrolled and classified into posterior sagging (PS) group and control group according to presence of posterior sagging, which was defined as posterior displacement of shaft fragment more than half of neck diameter on translateral view. We collected demographic data, fracture classification, and morphologic characteristics in plain radiographs based on previous literature (long medial beak, anterosuperior obliquity, lesser trochanter (LT) detachment, extramedullary beak, and V-shaped cortical defect). Comparison between groups and multivariable analysis was performed using multiple Firth logistic regression analysis.

Results: There was no significant difference found in the average age and laterality. The PS group presented higher proportion for female (88% vs 70%, P = 0.050) and fracture classification of AO/OTA 31-A2 than control group (92% vs 67%, P = 0.007). For all morphological characteristics, the proportion of patients was significantly higher in PS group than control group. In the multiple Firth logistic regression analysis, long medial beak distal to LT (odds ratio [OR], 7.93; 95% confidence interval [CI]: 1.72–36.59; P = 0.008), anterosuperior obliquity’ (OR, 23.87; 95% CI: 1.37–415.54; P = 0.030), LT detachment (OR, 10.15; 95% CI: 2.03–50.83; P = 0.005) and extramedullary beak (OR, 39.47; 95% CI: 2.14–727.26; P = 0.013) were significantly associated with the presence of posterior sagging.

Conclusion: Long medial beak, anterosuperior obliquity in lateral view, completely detached LT fragment, and extramedullary beak of proximal fragment were significantly associated with posterior sagging of shaft fragment.

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