Comparative evaluation of 2.0-mm locking plate system vs2.0-mm nonlocking plate system for mandibular fracture: a prospective randomized study

Abstract

This study evaluated the efficacy of a 2.0-mm locking plate/screw system compared with a 2.0-mm non-locking plate/screw system in mandibular fractures. A prospective randomized clinical trial was conducted. Patients were randomly assigned to receive 2.0-mm locking plates (group A) or 2.0-mm nonlocking plates (group B). All patients were followed up for 12 weeks postoperatively. Complications were analysed according to the type of plate used and the site of fracture. Fifty patients with 76 fractures met the inclusion criteria. Thirty-six fracture sites were treated with 2.0-mm locking plates and 40 with 2.0-mm nonlocking plates. The number of patients requiring postoperative maxillomandibular fixation was significantly higher in group B ( p < 0.01); seven complications occurred representing 9% of the total. Two complications occurred in the locking group and five in the nonlocking group with complication rates equalling 6% and 13%, respectively. When comparing the overall complication rates according to plates used, the χ 2 test showed no statistically significant difference between the locking and nonlocking plates ( p > 0.05). In conclusion, mandible fractures treated with 2.0-mm locking plates and 2.0-mm nonlocking plates present similar short-term complication rates.

Over the last 15 years, the use of internal rigid fixation in oral and maxillofacial surgery has become widely utilized. Miniplate osteosynthesis is a standard method for the surgical treatment of mandibular fractures . Miniplates provide functionally stable fixation unlike rigid fixation that prevents micromotion of the bony fragments under function. Functionally stable fixation applies to internal fixators that allow bone alignment and permit healing during function .

The loosening of one or more screws during the convalescent period following miniplate osteosynthesis is a problem especially in mandibular fracture osteosynthesis where loosening of screws requires removal of the fixation appliance. As a rule this does not compromise the result as the fracture or osteotomy has healed underneath , but it leads to a second minor operative procedure. This problem has been overcome by the development of the locking plate/screw system, which offers advantages over other plating systems . Locking 2.0 miniplates utilize double threaded screws, which lock to the bone and the plate, creating a mini-internal fixator. This results in a more rigid construction with less distortion of the fracture or osteotomy, less screw loosening and less interference with bone circulation since the plate is not too tightly pressed against the bone .

The locking screw plate system also reduces compressive forces between the undersurface of the plate and lateral bony cortex compared with a conventional mandibular plate. In a locking screw plate system, forces are generated between the threaded portion of the plate and the screw. This limits stress shielding and creates a more stable fixation over time . Theoretical advantages proposed include: less precision required in plate adaptation because of the internal/external fixator; less alteration in osseous or occlusal relationship on screw tightening; greater stability across the fracture site; and less screw loosening .

H erford and E llis concluded that the use of a locking plate/screw system was simple, and it offers advantages over conventional bone plates by not requiring the plate to be compressed to the bone to provide stability. In 1999, G utwald performed the first biomechanical comparison of locking plates applied to the mandible. They concluded that higher stability was achieved with the locking plates. H aug et al. performed a study with intentional maladaptation of the plates. They concluded that the degree of adaptation affected the mechanical behaviour of nonlocking systems, but it did not affect the locking system.

The biomechanical and technical advantages of locking miniplate systems over conventional miniplate systems prompted the current study. The purpose of this prospective randomized study was to evaluate the efficacy of 2.0-mm locking miniplate/screw systems compared with 2.0-mm nonlocking miniplate/screw systems in mandibular fractures.

Materials and methods

A prospective randomized clinical trial was conducted for 18 months, from November 2007 to June 2009. Fifty patients ( Tables 1 and 2 ) with isolated mandibular fracture (single or multiple) without pre-existing infection and comminution were selected. Excluded were patients in whom a brief period of maxillomandibular fixation (MMF) was medically contraindicated (epilepsy, severe asthma, psychiatric condition, and smoker, alcohol or drug abuse). Patients were randomly divided according to a computer generated randomizer into two equal groups of 25 patients each. Group A patients underwent osteosynthesis using 2.0 mm locking miniplates while group B patients underwent osteosynthesis using 2.0 mm non-locking miniplates. They were informed of the need for 3 month follow-up. The patients had to give informed consent to participate in the study. The patient information was documented in a consent form. The study design had been approved by the local ethics committee.

Table 1
Patient details for group A.
Sr. No. Age/sex Aetiology Time lapse (days) Site distribution MMF if required (5 days) Pain third month Morbidity Treatment
1 22 M RTA 6 Body + angle 5 None
2 24 M RTA 7 Body alone 5 None
3 26 M RTA 3 Parasymphysis + angle Required 0 None
4 42 M RTA 6 Angle alone 4 None
5 26 F Assault 4 Angle alone 3 None
6 19 F RTA 4 Body + U/L condyle Required 4 None
7 25 M RTA 6 Body + parasymphysis Required 3 None
8 22 M RTA 13 Parasymphysis alone 4 Infection Local Curettage
9 52 M Assault 6 Angle alone 0 None
10 33 M RTA 5 Body alone Required 8 Infection Incision and drainage with plate removal
11 30 M RTA 7 Angle alone 1 None
12 17 M Fall 8 Body + angle 4 None
13 24 M RTA 6 Body alone 0 None
14 32 M RTA 7 Angle alone 3 None
15 33 M Assault 15 Parasymphysis alone 0 None
16 30 M RTA 8 Angle alone 0 None
17 34 M RTA 4 Body + U/L condyle Required 6 None
18 24 M RTA 9 Parasymphysis + angle 1 None
19 26 M Fall 5 Body + angle 1 None
20 45 M RTA 6 Body alone 0 None
21 28 M RTA 4 Angle alone 2 None
22 29 M RTA 9 Angle + body + U/L condyle Required 1 None
23 47 M RTA 3 Body alone 2 None
24 30 M RTA 7 Parasymphysis + U/L condyle Required 0 None
25 32 M RTA 7 Body alone 1 None

Table 2
Patient details for group B.
Sr. No. Age/sex Aetiology Time lapse (days) Site distribution MMF if required (5 days) Pain third month Complication Treatment
1 26 M RTA 6 Angle alone 0 None
2 24 M RTA 6 Body alone 6 None
3 23 M RTA 7 Parasymphysis + angle Required 0 None
4 16 M Assault 3 Parasymphysis alone Required 0 None
5 32 M RTA 7 Angle alone Required 3 Infection Local curettage
6 42 M RTA 6 Body + angle Required 2
7 33 M Fall 7 Parasymphysis 2 Infection Local curettage
8 18 F RTA 4 Parasymphysis + angle Required 0 None
9 34 M Assault 8 Body alone Required 2 None
10 46 M RTA 6 B/L Body Required 6 None
11 28 M RTA 14 Body + angle Required 3 None
12 20 M Fall 3 B/L Body Required 4 None
13 30 F Assault 7 Angle alone 3 Infection Incision and drainage; plate removal
14 26 M RTA 6 Parasymphysis + angle 2 None
15 40 M RTA 4 Parasymphysis alone 0 None
16 48 M RTA 8 Parasymphysis + angle Required 0 None
17 29 M Assault 7 Body + angle Required 4 None
18 34 M RTA 6 B/L Body Required 0 None
19 36 M RTA 5 Body + angle Required 2 None
20 32 M RTA 8 Angle alone 3 Occlusal disturbance Occlusal grinding
21 30 M Assault 7 Body + angle Required 7 None
22 19 M RTA 5 Parasymphysis Required 2 Infection Local curettage
23 52 M RTA 6 Parasymphysis + B/L condyle Required 0 None
24 27 M RTA 6 B/L Body Required 4 None
25 25 M RTA 4 Parasymphysis alone 0 None
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Feb 7, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Comparative evaluation of 2.0-mm locking plate system vs2.0-mm nonlocking plate system for mandibular fracture: a prospective randomized study

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