Article
Fusion and failure following anterior cervical plating with dynamic or rigid plates: 2-year results of a multi-centric, prospective, randomized, controlled study
Fusions- und Versagensquote nach ventraler zervikaler Plattenfixierung mit dynamischen und rigiden Platten: 2-Jahres Ergebnisse einer multizentrischen, randomisierten, kontrollierten Studie
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Published: | April 11, 2007 |
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Objective: Anterior cervical plate fixation is an approved technique for cervical spine stabilization in the presence of anterior cervical instability. Rigid plate designs, in which the screws are locked to the plate, are in common use and thought to provide more fixation to a treated segment than dynamic designs, in which the screws may glide when the graft is settling. Recently, mechanical studies gave evidence, that dynamic anterior plates provide more loading on the graft. This may result in a more rapid fusion and – as a consequence – lower implant complications. This, however, must not be necessarily true under in vivo conditions. Thus, the objective of the study was to analyse speed of fusion and implant complications in both type of plates.
Methods: This is a prospective, randomized, controlled multi-centric study, approved by the ethic committees of each participating country. 132 patients were included and assigned by randomisation to one of the groups in which they received a routine anterior cervical discectomy and autograft fusion with either a dynamic plate with screws locked in ap – direction (ABC, Aesculap) or a rigid plate (CSLP, Synthes). After surgery, three and six months postoperatively and after two years, we looked at segmental mobility and implant complications. All measurements were performed by an independent radiologist. Please note, that six-month results of the current study have been presented on last years meeting. We can now present the 2-year results. Six-month mobility results are available for 77 patients (43 ABC / 34 CSLP), two year results for 37 patients (22 ABC, 15 CSLP).
Results: Mean segmental mobility after surgery for the ABC-group was 1.7 mm, 1.4 mm after three months, 0.8 mm after six months, 0.5 mm after two years. For the CSLP-group these values were 1.0 mm, 1.8 mm, 1.7 mm and 0.3 mm. The difference at six months between both groups is significant (p=0.02), however is not significant after two years (p=0.91). There have been 4 patients with hardware complications within the CSLP-group and no implant complications within the ABC-group, p=0.044.
Conclusions: There is still evidence, that dynamic plate designs provide a more rapid fusion in cervical spine surgery than rigid plate designs. Moreover, the rate of implant complications tends to be lower in this group. The two-year results confirm our earlier findings.