The Significance of Evaluating the Femoral Head Blood Supply after Femoral Neck Fracture: A New Classification for Femoral Neck Fractures

Abstract

Objective: To compare a new classification with the Garden classification by exploring their relationships with vascular injury.

Methods: This retrospective study enrolled 73 patients with subcapital femoral neck fracture from July 2015 to November 2018, including 32 males and 41 females with an average age of 47.2 years. All patients were classified by the Garden classification using anteroposterior X-ray imaging and by a new classification system based on three-dimensional CT imaging. The blood supply of the affected femoral head in these patients was evaluated based on DSA images. Correlations between the two classifications and the degree of vascular injury were assessed.

Results: The results of the DSA examination indicated that eight patients had no retinacular vessel injury, 20 patients had one retinacular vessel injury, 35 patients had two retinacular vessel injuries, and 10 patients had three retinacular vessel injuries. The degree of vascular injury was used to match the two fracture classifications. Forty-nine Garden classifications (Type I-IV: 8, 12, 23, 6, respectively, 67.12%) and 66 new classifications (Type I-IV: 8, 20, 32, 6, respectively, 90.41%) corresponded to the degree of vascular injury (p < 0.05). The Garden classification showed moderate reliability, and the new classification showed near perfect agreement (Interobserver agreement of k = 0.564 [0.01] in Garden classification vs. Garden classification k = 0.902 [0.01] for the five observers).

Conclusions: The new classification system can accurately describe the degree of fracture displacement and judge the extent of vascular injury.

Keywords: classification; digital substraction angiography; femeral neck fracture; retinacular vessel; three-dimensional CT.

Fig. 1

(A–F) correspond to the new classification types I, IIa, IIb, IIIa, IIIb, and IV, respectively. (A) Type I, complete fracture without displacement. (B) Type IIa: A well‐aligned fracture on anteroposterior X‐ray imaging but with significant anterior tilting angular displacement on transverse CT imaging. (C) Type IIb: A well‐aligned fracture on anteroposterior X‐ray imaging but with significant posterior tilting angular displacement on transverse CT imaging. This type was rare in the present study. (D) Type IIIa: Significant displacement on anteroposterior X‐ray imaging, usually accompanied by angular deformity and rotational displacement on transverse CT imaging. Type IIIa: The proximal femur is displaced upward with femoral head abduction. (E) Type IIIb: Significant displacement on anteroposterior X‐ray imaging, usually accompanied by angular deformity and rotational displacement on transverse CT imaging. The upper end of the femoral head/neck is inserted with femoral head adduction. This type was rare in the present study. (F) Type IV: Complete displacement on anteroposterior X‐ray imaging (floating femoral head), accompanied by angular deformity and rotational displacement on transverse CT imaging.

Fig. 2

(A–F) correspond to CT and DSA images of new classifications I, IIa, IIb, IIIa, IIIb, and IV, respectively. (A) A Type I fracture case. The CT scan showed a complete fracture without displacement, and no obvious displacement or rotation on transverse CT imaging could be observed. All three groups of retinacular arteries (the superior retinacular artery (SRA, blue arrow), the inferior retinacular artery (IRA, red arrow), and the anterior retinacular artery (ARA, green arrow) were well‐developed on DSA imaging. (B) A Type IIa fracture case. Significant anterior tilting angular displacement could be observed on transverse CT imaging. The superior (blue arrow) and inferior (red arrow) retinacular arteries from MFCA are well‐developed on DSA imaging, while the anterior retinacular arteries from LFCA are affected (green star). (C) A Type IIb fracture case in which significant posterior tilting angular displacement could be observed on transverse CT imaging. The inferior (red arrow) and anterior (green arrow) retinacular arteries are well‐developed, while the superior retinacular arteries (blue star) are affected on DSA imaging. (D) A Type IIIa fracture case in which significant anterior tilting angular displacement could be observed on transverse CT imaging. The inferior retinacular arteries (red arrow) are well‐developed, while the superior (blue star) and anterior (green star) retinacular arteries are affected on DSA imaging. (E) A Type IIIa fracture case in which significant anterior tilting angular and rotation displacement could be observed on transverse CT imaging. The superior retinacular arteries (blue arrow) from the MFCA are well‐developed, while the inferior (red star) and anterior (green star) retinacular arteries are affected on DSA imaging. (F) A Type IV fracture case in which significant anterior tilting angular displacement could be observed on transverse CT imaging. The superior (blue star), inferior (red star), and anterior (green star) retinacular arteries are all affected on DSA imaging.

Fig. 3

Treatment outcomes for FNF cases in this study. A flowchart depicting the treatment outcomes for femoral neck fracture. FNF, femoral neck fracture; CRIF, closed reduction and internal fixation; ORIF, open reduction and internal fixation; THA, total hip arthroplasty. Forty‐nine patients were followed up for more than 2 years (average 2.43 years), and eight patients developed nonunion or osteonecrosis during the follow‐up period.

Fig. 4

(A,B) A 53‐year‐old male patient was diagnosed as Type IIIb femoral neck fracture, and the probability of femoral head necrosis was high before operation, but the patient refused to undergo THA. (C) The patient was treated with ORIF, which is an immediate image after surgery. (D) After 16 months of follow‐up, necrosis and collapse occurred in the femoral head of the affected side.