Abstract

Background: Several fixation devices have been developed to overcome the difficulties encountered in the management of the unstable trochanteric fractures. PFN in unstable fracture patterns is progressively becoming standard method of fixation in view of its superior biomechanics and prevention of varus collapse in comparison to extramedullary devices. However, evolution of PFN is also not free from complications and may comprise complications associated with the migration of the interlocking head screws (Z-effect and reverse Z-effect), varus collapse, screw cutout, peri-implant fracture, non-union, delayed union, shortening and infection.
Aims & Objectives: The objective of the paper is to describe the technical hitches, errors and modes of failure of PFN in unstable trochanteric fractures with their literature-based explanations and the recommendations to avoid such complications.
Materials and methods: The current study is a critical appraisal of the technical hitches, errors and modes of failure of PFN in the course of its evolution in treatment of unstable trochanteric fractures. All patients with unstable trochanteric fractures from July 2013 to June 2015, treated with PFN were included in the study. The technical complications involved with surgical procedure and techniques adapted to overcome such complications were noted. All patients were followed up for a period of 2 years and final outcome assessment comprised the post-operative complications, mobility status, shortening and Harris hip score.
Results: Forty five patients with unstable trochanteric fractures were treated with PFN during the study period. Forty two patients were available for final follow up at 2 years. Technical difficulties with the implantation of the PFN were documented in a total of 16 patients (35.55%) which included failed closed reduction in 8, entry point issues in 7, guide wire breakage in 3, fracture at nail tip in 1, difficulty in proximal locking due to Jig mismatch in 4. Post-operative complications included varus mal-reduction in 4, lag screw cut-out leading to non-union in 2, differential migration of screws in 3, locking bolt missing the nail hole in 1 and peri-implant fracture in 1. All fractures went into union, except two with mean shortening of 0.5 cms. Mean neck shaft angle achieved post reduction was 130.5 degrees (range from 125-137) and at final follow up was 129.8 degrees.
Conclusion: Even though intramedullary fixation is an established method of treatment of unstable trochanteric fractures, the evolution of the procedure is not free from complications. Surgery is technically demanding. However with proper execution, good outcome can be achieved with acceptable rates of complications even in unstable trochanteric fractures. Concerning the techniques making proper entry point, adequate reaming of proximal femur, passing the nail to avoid varus & distraction at fracture site and placing the lag screw in the inferior part of neck in anterior posterior projection and central in lateral projection reduces risk of fixation failure.

Keywords

Unstable trochanteric fractures, PFN, Z-effect, Reverse Z-effect, Varus collapse, Cut-out