Comparative study of intertrochanteric fracture fixation using proximal femoral nail with and without distal interlocking screws

Abstract

Background: Intertrochanteric (IT) fracture is one of the most common fractures seen in an orthopaedic practice. Proximal femoral nailing (PFN) is a common modality of fixing IT femur fracture. We retrospectively studied whether a PFN with two proximal lag screws can be done without distal interlocking screws in the 31-A1 and 31-A2 fracture patterns according to the Arbeitsgemeinschaft für Osteosynthesefragen/Orthopaedic Trauma Association (AO/OTA) guidelines for IT femur fractures.

Aim: To compare the outcomes of IT fractures (AO/OTA 31-A1 and 31-A2) treated by PFN with and without distal interlocking screws.

Methods: We carried out a retrospective study of 140 patients in a tertiary care centre who had AO/OTA type 31-A1 and 31-A2 IT fractures. We divided the patients into two groups, in which one of the groups received distal interlocking screws (group 1) and the other group did not (group 2). The subjects were followed up for a mean period of 14 mo and assessed for radiological union time, fracture site collapse, mechanical stability of implant, and complications associated with the PFN with distal interlocking and without distal interlocking. Then, the results were compared.

Results: PFN without distal interlocking screws has several advantages and gives better results over PFN with distal interlocking screws in the AO/OTA 31-A2 fracture pattern. However, similar results were observed in both groups with the fracture pattern AO/OTA 31-A1. In patients with fracture pattern AO/OTA 31-A2 treated by PFN without distal interlocking screws, there were minimal proximal lock-related complications and no risk of distal interlock-related complications. The operative time, IITV radiation time and time to radiological union were reduced. These patients also had better rotational alignment of the proximal femur, and the anatomy of the proximal femur was well maintained. It was also noted that in the cases where distal interlocking was performed, there was a gradual decrease in neck shaft angle, which led to varus collapse and failure of bone-implant construct in 21.40%.

Conclusion: In fracture pattern AO/OTA 31-A2, PFN without distal interlocking had better results and less complications than PFN with distal interlocking.

Keywords: Arbeitsgemeinschaft für Osteosynthesefra-gen/Orthopaedic Trauma Association 31-A1 and 31-A2; Distal interlocking screws; Intertrochanteric fracture; Outcome; Proximal femoral nail; Without distal interlocking screws.

Figure 1

Arbeitsgemeinschaft für Osteosynthesefragen/Orthopaedic Trauma Association classification of 31-A fractures. Arbeitsgemeinschaft für Osteosynthesefragen/Orthopaedic Trauma Association classification as follows: (1) A1: Simple two part, lateral cortex remains intact; (2) A2: Comminuted withpostero-medial fragment,lateral cortex remains intact; and (3) A3: line extend acrossboth medial and lateralcortices,include reverseobliques.

Figure 2

Proximal lock-related complications. A: Proximal screw cut-out; B: Z-effect; C: Proximal screw back-out; D: Proximal screw breakage.

Figure 3

Distal screw breakage.

Figure 4

Typical case presentation of a patient treated with proximal femoral nail with distal interlocking screw. A: Immediate postoperative period; B: Downward migration of the nail because of distal locking; C: Windshield wiper effect around the purchase area of the screw in the head; D: Screw cut-through from the femoral head; E: Z-effect. PFN: Proximal femoral nailing; Post-OP: Postoperative period.

Figure 5

Typical case presentation of a patient treated with proximal femoral nail without distal interlocking screw. A: Immediate post-OP; B: After fracture union. PFN: Proximal femoral nailing; Post-OP: Postoperative period.

Figure 6

Case of a 68-year-old female with right intertrochanteric fracture pattern Arbeitsgemeinschaft für Osteosynthesefra-gen/Orthopaedic Trauma Association 31-A2. A: Preoperative X-ray; B: Immediate postoperative X-ray; C: After union.