Parameters Governing the Fate of Fracture Fixation With Proximal Femoral Nailing (PFN) for Intertrochanteric Femur Fractures

Abstract

Introduction: A high mortality rate is associated with hip fractures in the elderly. This is because their bones are osteoporotic with implants having less hold and there are more co-morbidities associated with the elderly. Osteosynthesis with the proximal femoral nail (PFN) features the advantages of high rotational stability of the head-neck fragment. However, the use of the nail is technically ambitious and is accompanied by some risks of error, which can lead to failure. This study aims to understand the technical difficulties related to PFN and methods to mitigate them and radiological indicators for successful outcomes of PFN.

Methods: Our study aims to analyze the radiological parameters as indicators for the successful outcome of intertrochanteric fractures fixed using PFN and also the factors responsible for intraoperative conversion to dynamic hip screw (DHS). This is a prospective, observational study conducted from January 2020 to December 2020, on all the patients with intertrochanteric fractures who were planned to be treated by PFN and consented to be part of the study group at our institute. This study includes 99 cases of intertrochanteric fractures classified according to AO (Arbeitsgemeinschaft für Osteosynthesefragen)/Association of the Study of Internal Fixation (ASIF) and Evan's classification systems and followed postoperatively at regular intervals up to one year. Different methods of fracture reduction, intraoperative radiological parameters, and postoperative radiological parameters dictating the fate of PFN along with factors responsible for the intraoperative conversion to DHS were analyzed and discussed.

Results: Out of 99 patients planned for PFN, four were converted to DHS intraoperatively and 15 patients expired within the follow-up period of one year, leaving only 80 patients in the study group. Of them, seven patients (11.4%) had implant-related complications. According to Chang's reduction quality criteria (CRQC), two cases have CRQC 1 (poor reduction), 11 cases have CRQC 2 (acceptable reduction), 39 cases have CRQC 3 (acceptable reduction), and 28 cases have CRQC 4 (excellent reduction).

Conclusions: Though PFN is technically challenging, with proper guidelines and technique, it gives excellent results. Most importantly, a nonvarus reduction, proper nail insertion and accurate placement of lag screws are the crucial factors for a successful outcome. Biomechanically stable reduction, by closed, percutaneous, or open means, is the key to treating unstable intertrochanteric fracture successfully.

Keywords: chang’s reduction quality criteria; greater trochanter orthogonal line; hip offset; intertrochanteric fractures; intertrochanteric translation; parameters of pfn; parker's ratio; proximal femoral nail.

Figure 1. Postoperative analysis of radiographs using Surgimap software*

(a) Horizontal offset = 44mm, Vertical offset = 47mm, Neck length = 59mm; (b) Parker's ratio = 11/30=0.34, CalTad = 5mm;  (c) GTOL (red line) passing through second quadrant of femoral head. V: vertical; H: horizontal; CalTAD: calcar referenced tip-apex distance; GTOL: greater trochanter orthogonal line; IM: intramedullary *Nemaris, Inc., New York, United States

Figure 2. Percutaneous reduction and provisional fixation.

(a) Intussusception of proximal medial beak into distal canal; (b) Lifting the sag with K-wire maintaining anterior cortical continuity; (c) Lifting force pushing the medial beak more medial; (d) Bone hook used to align the medial cortical continuity; (e) Clinical picture of percutaneous reduction; (f) Postoperative radiograph, AP; (g) Postoperative radiograph, lateral K-wire: Kirschner wire

Figure 3. Piriformis entry after percutaneous reduction

(a) Unstable trochanteric fracture, AP; (b) Unstable trochanteric fracture, Lateral; (c) Percutaneous reduction, anterior cortical alignment; (d) Piriformis entry, AP; (e) Piriformis entry, Lateral; (f) Postoperative radiograph, AP AP: anteroposterior

Figure 4. Variance: (a) Neutral, (b) Positive, (c) Negative

R: right

Figure 5. Reverse epsilon fracture with single screw

(a) Reverse epsilon fracture; (b) Single screw fixation with vertical offset = 28 mm, horizontal offset = 49 mm, neck length = 58 mm, CalTAD = 18 mm, NSA = 120 degrees; (c) Screw cut out and varus collapse. H: horizontal; V: vertical; R: right; NSA: neck shaft angle; CalTAD: calcar referenced tip-apex distance

Figure 6. Intra-operative conversion from PFN to DHS

(a and b) AP and lateral radiographs of unstable trochanteric fracture; (c) Percutaneous reduction and provisional fixation; (d) Entry through pyriformis; (e) Intertrochanteric translation after traction release; (f) Open reduction and DHS done; (g and h) Postoperative DHS fixation PFN: proximal femoral nail; DHS: dynamic hip screw; AP: anteroposterior

Figure 7. Neck length and horizontal offset

(a) Immediate postoperative: Neck length (line 3) = 55 mm, Horizontal offset (line 4) = 42 mm; (b) Post weight bearing: Neck length (line 3) = 52 mm, Horizontal offset (line 4)= 40 mm H: horizontal; R: right