Cast immobilization in bayonet position versus reduction and pin fixation of overriding distal metaphyseal radius fractures in children under ten years of age: a case control study

Abstract

Purpose: Completely displaced distal radius fractures in children have been traditionally reduced and immobilized with a cast or pin fixed. Cast immobilization leaving the fracture displaced in the bayonet position has been recently suggested as a non-invasive and effective treatment alternative. This is a pilot comparative study between reduction and no reduction.

Methods: We assessed subjective, functional and radiographic outcome after a minimum 2.5-year follow-up in 12 children under ten years of age who had sustained a completely displaced metaphyseal radius fracture, which had been immobilized leaving the fracture in an overriding position (shortening 3 mm to 9 mm). A total of 12 age-matched patients, whose similar fractures were reduced and pin fixed, were chosen for controls.

Results: At follow-up none of the 24 patients had visible forearm deformity and the maximal angulation in radiographs was 5° Forearm and wrist movement was restored (< 10° of discrepancy) in all 24 patients. Grip strength ratio was normal in all but three surgically treated patients. All patients had returned to their previous activities. One operatively treated boy who was re-operated on reported of pain (visual analogue scale 2).

Conclusion: The results of this study do not demonstrate the superiority of reduction and pin fixation over cast immobilization in the bayonet position of closed overriding distal metaphyseal radius fractures in children under ten years with normal neurovascular findings.

Level of evidence: III.

Keywords: bayonet position; cast immobilization; children’s fracture; distal metaphyseal radius fracture; overriding fracture; pin fixation.

Copyright © 2021, The author(s).

Figures

Fig 1.

a) Distal forearm fracture in a five-year-old girl (Table 1, case 3), which was immobilized with synthetic splints (above elbow dorsal and a below elbow volar) applied in finger trap traction leaving the radius in bayonet position. Immobilization was discontinued at four weeks. Complete radiographic remodelling is evident 43 months later; b) a similar distal forearm fracture in another five-year-old boy (Table 1, case 14), which was treated by reduction and pin fixation under general anaesthesia. Synthetic splints and both pins were removed four weeks after surgery. Radiographic result 43 months later.

Fig 2.

Angulation was measured in frontal and sagittal planes by measuring the angle between the longitudinal axes (red lines that bisect the width of radius at two reference points) of the radius proximal and distal to the fracture. Shortening was measured from the best available location.

Fig 3.

This nine-year-old girl sustained an overriding distal metaphyseal fracture of her left radius and an associated greenstick type fracture of her left ulna at five years of age (Table 1, case 3). Her fractures were treated with synthetic splints (above elbow dorsal and below elbow volar) leaving the radius fracture displaced in an overriding position: a) forearms, anterior view; b) forearms, dorsal view; c) forearms, ulnar view; d) passive wrist flexion; e) passive wrist extension; f) active pronation; g) active supination; h) active ulnar deviation; i) active radial deviation.

Fig 4.

The two patients’ (Table 1, cases 12 and 23) with the most pronounced radiographic deformity of radius in both treatment groups with 5° of apex volar angulation of the radius (a, b – cast immobilization in bayonet position, c, d – reduction and pin fixation). Both children reported normal pain free upper limb functions at follow-up (three years and 4.4 years, respectively).