Yesterday I looked at a systematic review of biodegradable plates for orthognathic surgery. One of the trials included in the review (Buijs et al) had reported outcomes at 8 weeks. Recently the authors of that study have reported 2-year results (van Bakelen et al). The original aim of the study was to compare the clinical performance between the biodegradable and the titanium fixation systems after 24 months of follow-up regarding fixation of mandibular, Le Fort-I, and zygomatic fractures, and bilateral sagittal split osteotomies (BSSO) and/or Le Fort-I osteotomies.
Patients scheduled for treatment of Le Fort-I fracture, and/or a solitary or multiple (maximum 2) mandibular fracture(s), and/or a zygoma fracture or Le Fort-I osteotomy and/or a bi-lateral sagittal split osteotomy (BSSO) were included. Patients were randomised to either titanium or biodegradable plate systems. All plates were applied according to the manufacturers instructions. Patients were not informed of the type of system that was used. The main outcome was the removal of the plates/screws (yes/no) within the first 2 post- operative years after treatment. Other outcome include occlusion, infection radiographic position and patient related outcomes eg pain and function.
- 117 patients were randomised to the biodegradable group and 113 to the titanium group. 25 patients from the biodegradable group were switched to the titanium group at operation.
- At one year 124 patients with titanium plates and 75 with biodegradable plates were reviewed.
- At two years 93 patients with titanium plates and 56 with biodegradable plates were reviewed.
- 16 of the 134 patients (11.9%) who received titanium and 21 of the 87 patients (24.1%) who received the biodegradable system needed a second operation to remove the plates/screws.
- Abscess formation was the main reason for plate/screw removal in both groups: 12 of the 21 removals (57.1%) in the biodegradable group, and 10 of the 16 removals (62.5%) in the titanium group.
The authors concluded that the performance of the biodegradable system was inferior to titanium system.
It is interesting to look at this study after the systematic review from yesterday. The fact that a large proportion (21%) of the patients randomised to the biodegradable group did not receive that treatment has a significant impact on interpreting the findings. The aim of randomisation is to reduce the possibility of selection biases and ensure that the groups have similar characteristics at baseline. The number of crossovers between the groups in this case is likely to produce a clear bias. In addition at two years there is a more than 30% drop out in both the biodegradable and titanium groups. Because of these issues it is impossible to identify what was the real difference between the two groups.
van Bakelen NB, Buijs GJ, Jansma J, de Visscher JG, Hoppenreijs TJ, Bergsma JE, Stegenga B, Bos RR. Comparison of Biodegradable and Titanium Fixation Systems in Maxillofacial Surgery: A Two-year Multi-center Randomized Controlled Trial. J Dent Res. 2013 Oct 15. [Epub ahead of print] PubMed PMID: 24130219.
Buijs GJ, van Bakelen NB, Jansma J, de Visscher JG, Hoppenreijs TJ, Bergsma JE, Stegenga B, Bos RR. A randomized clinical trial of biodegradable and titanium fixation systems in maxillofacial surgery. J Dent Res. 2012 Mar;91(3):299-304. doi: 10.1177/0022034511434353. Epub 2012 Jan 23. PubMed PMID: 22269272.