Implant complications, fusion, loss of lordosis, and outcome after anterior cervical plating with dynamic or rigid plates: two-year results of a multi-centric, randomized, controlled study.
METHODS
Prospective, controlled, randomized, multicenter study.


OBJECTIVE
To analyze implant complications and speed.


BACKGROUND
Rigid plate designs, in which the screws are locked to the plate, are in common use and thought to provide more fixation than dynamic designs, in which the screws may glide when the graft is settling. The aim of the study is to analyze (1) implant complications, (2) speed of fusion, (3) loss of lordosis, and (4) clinical outcome in both types of plates.


METHODS
One hundred thirty-two patients were included and assigned by randomization to one of the groups in which they received a routine anterior cervical discectomy and autograft fusion with either a dynamic plate (ABC, study group) or a rigid plate (CSLP, control group). At discharge, after 3 and 6 months and finally after 2 years, implant complications, segmental mobility, absence of radiolucencies, absence of bone sclerosis, evidence of bridging trabecular bone, loss of lordosis, Visual Analog Scale (VAS) and Neck Disability Score were recorded. All radiographic measurements were performed by an independent radiologist.


RESULTS
There have been 4 patients with implant complications within the control group and no implant complications within the study group, P = 0.045. Mean segmental mobility before discharge for the study group was 1.7 mm, 1.4 mm after 3 months, 0.8 mm after 6 months, and 0.4 mm after 2 years. For the control group, these values were 1.0, 1.8, 1.6, and 0.5 mm. The difference at 6 months between both groups was significant (P = 0.024). Neither absence of radiolucencies, nor absence of sclerosis, nor evidence of bridging bone showed significant differences between the 2 groups through the postoperative follow-up (P > 0.05). The loss of segmental lordosis for the study group with respect to intraoperative radiograph was 1.3 degrees at discharge and 4.3 degrees after 2 years. For the control group, these values were 0.9 degrees , 0.7 degrees . The difference at 2 years was significant (P = 0.003). Clinical postoperative outcome (VAS and ODI) was not different between the 2 groups through the postoperative follow-up (P > 0.05).


CONCLUSIONS
Dynamic cervical plate designs provide less implant complications (no patient) compared with rigid plate designs (4 patients). Speed of fusion was faster in the presence of a dynamic plate. However, loss of segmental lordosis is significantly higher if dynamic plates are used, which did not result in differences regarding clinical outcome between dynamic and constrained plates after 2 years. Thus, dynamic plates should be considered to be the preferred treatment option because of the lower risk for implant failure-related revision surgery.
Pitzen
Tobias R
TR
SRH Waldklinikum Gera gGmbH, Strasse des Friedens 122, Gera, Germany. pitzen@t-online.de
Chrobok
Jiri
J
Stulik
Jan
J
Ruffing
Sabine
S
Drumm
Joerg
J
Sova
Laurentius
L
Kucera
Roman
R
Vyskocil
Tomas
T
Steudel
Wolf Ingo
WI
D000328:Adult; D000368:Aged; D001860:Bone Plates / Q000009:adverse effects* / Q000592:standards / Q000706:statistics & numerical data; D001863:Bone Screws / Q000009:adverse effects / Q000592:standards / Q000706:statistics & numerical data; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D017586:Diskectomy / Q000295:instrumentation / Q000379:methods; D004868:Equipment Failure / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D007405:Intervertebral Disc Displacement / Q000601:surgery; D008141:Lordosis / Q000601:surgery; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000209:etiology* / Q000473:pathology / Q000503:physiopathology; D019736:Prostheses and Implants / Q000009:adverse effects* / Q000592:standards / Q000706:statistics & numerical data; D011859:Radiography; D016059:Range of Motion, Articular / Q000502:physiology; D013123:Spinal Fusion / Q000295:instrumentation* / Q000379:methods; D055009:Spondylosis / Q000601:surgery; D016896:Treatment Outcome; D016474:Weight-Bearing / Q000502:physiology