Femoral neck fracture osteosynthesis by the biplane double-supported screw fixation method (BDSF) reduces the risk of fixation failure: clinical outcomes in 207 patients

Abstract

Introduction: Osteosynthesis of femoral neck fractures is related up to 46% rate of complications. The novel method of biplane double-supported screw fixation (BDSF; Filipov's method) offers better stability using three medially diverging cannulated screws with two of them buttressed on the calcar. Biomechanically, the most effective component is the distal screw placed at steeper angle and supported on a large area along the distal and posterior cortex of the femoral neck following its spiral anterior curve. Thereby, BDSF achieves the strongest possible distal-posterior cortical support for the fixation construct, which allows for immediate full weight-bearing. The aim of this study was to evaluate the outcomes from the first 5-year period of BDSF clinical application.

Materials and methods: Subject of this retrospective study were 207 patients with displaced Garden III-IV femoral neck fractures treated with BDSF. Three 7.3-mm cannulated screws were laid in two medially diverging oblique planes. The distal and the middle screws were supported on the calcar. The distal screw had additional support on the posterior neck cortex.

Results: The outcomes in 207 patients were analysed in 29.6 ± 16.8 months follow-up. Bone union occurred in 96.6% of the cases (males 97.6%, females 96.4%, P = 0.99). Rate of nonunion was 3.4%, including fixation failure (2.4%), pseudoarthrosis (0.5%) and nonunion with AVN (0.5%). Rate of AVN was 12.1% (males 4.8%, females 13.9%, P = 0.12). Modified Harris hip score was 86.2 ± 18.9 (range 10-100), with no significant difference between genders, P = 0.07. Older patients were admitted with significantly more comorbidities (P = 0.001), and on follow-up they were significantly less mobile (P = 0.005) and had significantly more difficulties to put socks and shoes on (P < 0.001).

Conclusions: By providing additional cortical support, the novel BDSF method enhances femoral neck fracture fixation strength.

Keywords: BDSF; Biplane; Femoral neck fracture; Fixation; Hip fractures; Osteosynthesis.

Fig. 1

Schematic representation of the BDSF method. The distal screw (red) is placed in the dorsal oblique plane, whereas the middle (blue) and proximal screw (grey) are oriented in the anterior oblique plane. The distal and the middle screws are calcar-buttressed with coronal inclinations of 150°–165° and 130°–140°, respectively. Each of these screws is placed with the following two supporting points (pivots) in the distal fragment: the medial supporting point on the distal femoral neck cortex and the lateral supporting point at the screw-entry point into the lateral diaphyseal cortex. The distal screw has an additional third medial supporting point on the posterior femoral neck cortex. The three medial supporting points are indicated with triangles

Fig. 2

Exemplified X-rays of a 51 yo female patient with bone union (successful healing with fracture consolidation) after BDSF treatment: AP view diagnostics (a), postoperative AP view (b), postoperative lateral view (c), AP view 6-month follow-up (d) and AP view 55-month follow-up (e)

Fig. 3

Exemplified X-rays of a 74 yo female patient with complete fixation failure (fragment redislocation) after BDSF treatment: AP view diagnostics (a), postoperative AP view (b), postoperative lateral view (c) and AP view 2-month follow-up (d). Lack of posterior cortical support and malreduction are seen on the postoperative X-rays (b, c)

Fig. 4

Exemplified X-rays of a 73 yo female patient with incomplete fixation failure and fragment impaction as a result of extreme loading after BDSF treatment: AP view diagnostics (a), postoperative AP view (b), postoperative lateral view (c), AP view 20-day follow-up with incomplete fixation failure and excessive fragment impaction, the latter denoted by black arrows (d). This patient died of acute renal insufficiency. Although severe traumatic agent caused partial displacement, the proper positioning of the screws prevents total displacement and transforms the shearing forces into compressive, causing further impaction

Fig. 5

Exemplified X-rays of a 79 yo female patient with late AVN post bone union after BDSF treatment: AP view diagnostics (a), postoperative AP view (b), postoperative lateral view (c), AP view 10-month follow-up with bone union (d) and 24-month follow-up with late AVN (e)