The value of ultrasound-assisted pinned resorbable osteosynthesis for cranial vault remodelling in craniosynostosis

Abstract

Resorbable osteosynthesis is a widespread tool in craniofacial surgery, however only a limited number of studies have focused on ultrasound-assisted pinned resorbable systems in the treatment of craniosynostosis.

Thirty-eight children with various types of craniosynostosis including scaphocephaly, trigonocephaly, anterior and posterior plagiocephaly were treated using the Sonic Welding resorbable osteosynthesis system. All patients were evaluated for operation time, stability of the surgical results, rate of local infections and visibility or palpability of the osteosynthesis material in the follow-up ranging from 15 to 21 month.

Mean operation time was not significantly higher compared to conventional osteosynthesis material and all remodelled cranial vaults showed immediate stability. Only one patient showed signs of an inflammatory skin reaction, which recovered spontaneously. The number of palpable or visible plates, respectively, increased during the first months with a maximum at 12 months (34 (89%) plates palpable, 26 (68%) plates visible). After this time point, the number decreased continuously until the end of the follow-up period at 21 months when 3 (20%) plates were palpable, 0 (0%) plates were visible).

Ultrasound-assisted pinned resorbable systems seem to be a promising tool in craniofacial surgery providing a timesaving and stable osteosynthesis. An initial swelling of the plates during the first 12 months before the complete degradation might result in a palpable and visible bulge.

Introduction

In the surgical correction of craniosynostosis, bone fixation using osteosynthesis is an element step (Arnaud and Renier, 2009). Historically, various techniques have been used for rigid fixation including simple metallic wires, metallic plates and screws or titanium meshes (Arnaud and Renier, 2009). The most common problems of metallic osteosynthesis are the temperature-induced pain, interference with imaging modalities, the risk of intracranial migration into the growing skull and the disadvantage of removing the material in a second surgical procedure. To avoid this second operation, biodegradable osteosynthesis materials have been introduced and their use has been well documented over the past 10–20 years in the maxillo-facial literature (Becker et al., 1999, Eckelt et al., 2007, Imola et al., 2001, Obwegeser, 1998). Some disadvantages of biodegradable osteosynthesis materials have been published, varying from less stabilisation to more difficult handling (Landes and Kriener, 2003, Maurer et al., 2002, Yerit et al., 2002). In particular there are reports of, an increase in operation time due to the extra need for tapping the screw hole and an increased risk of screw fractures, when the screws are not applied accurately in an orthograde direction (Eckelt et al., 2007).

A promising approach in the field of biodegradable osteosynthesis materials has been introduced with the Sonic Welding System developed by KLS Martin/Germany, which is based on ultrasound-assisted pinned resorbable systems. The pins (Resorb-X, KLS Martin, Tuttlingen, Germany) are made of poly d-lactide (50%) and l-lactide acid (50%) (PDLLA) and are inserted after conventional hole drilling with the aid of ultrasound to weld with the bone in order to fix plate or mesh. Typical thread cutting becomes redundant which results in reduction of operation time and minimizes the risk of a possible screw head fracture (Eckelt et al., 2007).

The aim of the present study was to evaluate the use of the Sonic Welding System in the surgical treatment of various types of craniosynostosis with respect to operation time, stability of the surgical results, rate of local infections and visibility or palpability of the osteosynthesis material in the follow-up.