Posterior Reduction and Temporary Fixation for Odontoid Fractures: An Intermuscular Dissection Approach versus A Midline Standard Muscle Stripping Approach.

Background Context: Both the intermuscular dissection approach and the midline, standard muscle stripping approach in posterior reduction and temporary fixation (PRTF) technique can effectively avoid the loss of atlantoaxial motion function caused by posterior atlantoaxial fusion. The intermuscular dissection approach demonstrates superior paravertebral muscles integrity preservation. Therefore, we hypothesize that: the range of motion (ROM) in rotation of C1-C2 after instrumentation removal would be superior in patients undergoing PRTF through the intermuscular dissection approach compared to the muscle stripping approach.

Purpose: The primary objective of this study was to evaluate the treatment efficacy of PRTF for odontoid fractures, with a secondary comparative analysis of the intermuscular dissection approach versus the muscle stripping approach.

Study Design: A retrospective study.

Patient Samples: From January 2020 to June 2022, clinical data of 58 patients with acute odontoid fractures who underwent PRTF technique were retrospectively reviewed from the hospital's internal database. The cohort comprised two matched groups: 29 patients treated with the intermuscular dissection approach PRTF technique and 29 patients treated with the muscle stripping approach PRTF technique.

Outcome Measures: The degree of paravertebral tissue edema in the short term postoperatively was assessed using the edema coefficient. The operative time, intraoperative blood loss, postoperative paravertebral tissue edema, pain, and supplementary use of narcotics were recorded and compared between the two groups. Fracture healing was evaluated using computed tomography (CT) and three-dimensional reconstruction. Instrumentation was removed after fracture healing, and the outcome assessments included American Spinal Injury Association (ASIA) scoring grade, Visual Analog Scale Score for Neck Pain (VASSNP) and Neck Disability Index (NDI). Dynamic rotational CT examination of the C1-C2 was performed to compare the ROM in rotation of C1-C2 between the two groups at 3 months after instrumentation removal.

Methods: A total of 58 cases with odontoid fractures who underwent PRTF technique were reviewed. The patients' general information, clinical outcomes, and radiographic outcomes were collected. Subsequently, to test our hypothesis, the patients were divided into two groups based on the different techniques of surgical exposure. Clinical data were analyzed between the two groups for differences.

Results: A total of 58 patients were included in the study, with a mean age of 46.9±12.0 years old. Fracture healing was achieved in all patients in this study, and all patients in this study chose to remove the instrumentation after fracture healing. All patients returned to their preoperative work. There were no significant differences between the two groups in ASIA scoring grade and NDI, fracture healing rate or time. Compared to the muscle stripping approach group, the intermuscular dissection approach group had a longer operative time but less intraoperative blood loss, lower short-term postoperative pain, less need for supplementary narcotics, and lower postoperative paravertebral tissue edema. The VASSNP in the intermuscular dissection approach group were lower than those in the muscle stripping approach group, but the difference was not statistically significant after instrumentation removal. After the removal of instrumentation, the ROM in C1-C2 rotation in the intermuscular dissection approach group was superior to that in the muscle stripping approach group.

Conclusions: The PRTF technique represents a clinically safe and feasible treatment option for odontoid fractures with an intact transverse ligament. Compared with the muscle stripping approach, the PRTF technique through intermuscular dissection approach provides a greater ROM in C1-C2 rotation after the removal of instrumentation.