Computer manufactured Patient-specific Auto-reducible plate versus standard Trapezoid plate in Unilateral Subcondylar fractures

Abstract

Purpose: Subcondylar fractures account for a high incidence of mandibular fracturesrepresenting a frustrating clinical dysfunction and serious complications when maltreated. Thisstudy aimed to compare the computer designed and manufactured patient-specific auto-reducibleplate to the standard trapezoid plate in attempt to reach the optimal geometrical design forsubcondylar fracture plate fixation.Patients and methods: A total of sixteen patients suffering from unilateral subcondylar fracturewere included in this study from the outpatient clinic of the department of oral and maxillofacialsurgery, faculty of Dentistry, Cairo University. All patients were subjected to preoperative clinicalevaluation and 3-D CT examination to assess the degree of fracture displacement and condylarlocation. The selected patients were divided into two groups, eight patients each. In group A patients,virtual fracture reduction through mirroring of the unaffected intact side was performed, which wasthen used as a template for designing and processing of the titanium patient-specific condylar platevia direct metal laser sintering. While in group B patients, the unilateral sub-condylar fractures weremanually reduced into position and fixed in place by the standard trapezoidal mini-plate. Fixationof the plates in both groups was then performed using 2.0 mini-screws. Postoperative clinicalassessment of the occlusion, Maximum inter-incisal opening (MIO) and mandibular deviation wasdone at one week, 1 month & 3 months. Immediate postoperative radiographic assessment wasperformed through the superimposition of the postoperative CT data of the fixed fracture on thepreoperative virtually reduced mandibular model as a reference CT data to validate and comparethe accuracy of the achieved postoperative fixation in both groups.Results: The surgeries in all cases proceeded without any complications. Surgical siteexamination was normal with no signs of infection. The occlusion was satisfactory at the end of thestudy interval despite the initial slight immediate postoperative occlusal discrepancy found in bothgroups. Deviation was not completely absent in both groups at the end of the follow-up period. TheMIO ranged from 39-47 mm at the end of the study with no significant difference between bothgroups. The CT scan revealed the almost precise adaptation of both plates in place with no significantdifference, however, with the advantageous fracture auto-reduction, intra-operative time saving andease of application recorded with the use of the PS-condylar plate in group A patients. The meanoperating time for reduction and fixation using the PS-condylar plate was 90 minutes comparedto a mean of 88 minutes using the standard reduction and trapezoid plate fixation technique.Conclusion: Despite of the approaching accuracy of both plates, preoperative digital virtualplanning and PS-plate processing were highly beneficial in the auto-reduction of the fracturedsegments. The intra-operative time saving and ease of application with less obtained surgical errorsdue to the planned surgery and the perfect fit of the prosthesis were found very valuable. Therefore,accommodating with the continuous technological updates, the integration of computer programsin surgery planning and plate designing and manufacturing in subcondylar fractures is highlydesirable due to its great benefits.