An interventional study of Anterior Cervical Discectomy and Fusion in Cervical Vertebral Disc Degeneration and Intervertebral Disc Displacement, sponsored by University of Ljubljana. Recruiting at 1 site in Slovenia. Open to participants aged 18 Years to 65 Years. Per ClinicalTrials.gov, last updated 2026-02-23.
Sponsored by University of Ljubljana · Not applicable, Interventional, and Treatment
Degenerative cervical disc disease can cause neck pain, nerve symptoms, dizziness, and problems with balance and head movement control. The neck contains many sensory receptors that provide information about head position and movement to the brain. When cervical discs degenerate or compress nearby structures, this sensory communication may be disrupted. As a result, patients may experience reduced accuracy and coordination of head movements.
Anterior cervical discectomy and fusion (ACDF) is a standard surgical procedure used to relieve nerve or spinal cord compression caused by cervical disc disease. The procedure is effective in reducing pain and neurological symptoms. However, it is not well understood whether ACDF also improves the way the neck and nervous system work together to control head movement.
The purpose of this study is to evaluate early changes in cervical movement control after ACDF. Patients scheduled for ACDF will be assessed before surgery and again one week after surgery. A group of healthy participants without neck pain will be assessed at the same time interval for comparison.
Cervical movement control will be measured using a computer-based head-tracking task. During this task, participants follow a moving target on a screen using controlled head movements. The system records measures of tracking accuracy and timing.
The primary research question is whether ACDF results in measurable short-term improvements in objective cervical movement control compared with healthy individuals over the same time period.
It is hypothesized that patients undergoing ACDF will demonstrate improvement in specific movement-control measures after surgery. However, broader patterns of movement-control impairment may not fully normalize in the early postoperative period.
The results of this study may improve understanding of how cervical spine surgery affects sensorimotor function and may help inform postoperative rehabilitation strategies.
Detailed Description Degenerative cervical disc disease is commonly associated with neck pain and neurological symptoms. In addition to these clinical manifestations, increasing evidence indicates that cervical spine pathology may impair cervical sensorimotor control. The cervical spine contains a high density of muscle spindles and joint mechanoreceptors that provide afferent information about head position and movement. This sensory input is integrated with visual and vestibular systems to regulate head-neck coordination and postural stability. Structural degeneration or neural compression may disrupt afferent signaling and alter this integration, potentially contributing to impaired movement accuracy, dizziness, or imbalance.
Anterior cervical discectomy and fusion (ACDF) is a standard surgical procedure used to relieve nerve root or spinal cord compression caused by cervical disc herniation when conservative treatment fails. While ACDF has demonstrated effectiveness in reducing pain and neurological deficits, its effects on objective cervical movement-control measures remain insufficiently characterized.
The RECAL-ACDF study is a prospective controlled longitudinal investigation designed to evaluate early changes in dynamic cervical movement control following ACDF. The study compares patients undergoing ACDF with time-matched healthy control participants assessed over the same time interval.
Study Design
Participants in the surgical group will be assessed at two time points:
The study uses a parallel-group, non-randomized design. The primary purpose is mechanistic evaluation of sensorimotor function.
Assessment of Cervical Movement Control Cervical movement control will be assessed using a validated dynamic head-tracking task (Butterfly test) implemented through the NeckSmart system (NeckCare™, Reykjavik, Iceland). The system uses a head-mounted inertial measurement unit (IMU) to record head movements while participants track an unpredictably moving visual target displayed on a computer screen.
The task includes three predefined difficulty levels (easy, medium, difficult), characterized by increasing target velocity and trajectory complexity. For each difficulty level, three trials will be performed.
The following outcome measures will be derived:
Mean values across repetitions will be used for statistical analyses.
Primary Objective To determine whether ACDF results in short-term improvements in dynamic cervical movement control compared with healthy controls over the same time period.
The primary outcome measure is the change in time-on-target at medium difficulty (ToT_m) from baseline to one week postoperatively.
Secondary Objectives
Cluster allocation (severity levels 1-4) will be determined using a previously established multidimensional classification framework based on standardized movement-control parameters.
Hypothesis It is hypothesized that patients undergoing ACDF will demonstrate measurable improvement in selected dynamic movement-control parameters one week after surgery. However, categorical redistribution across multidimensional impairment clusters may not occur in the early postoperative period.
This study conceptualizes postoperative recovery as an early sensorimotor recalibration process rather than immediate normalization of movement-control phenotype.
Statistical Approach The primary analysis will compare change scores (postoperative minus preoperative values) between the surgical and control groups. Appropriate parametric or nonparametric statistical tests will be applied depending on data distribution. Multiple comparisons will be controlled using the Holm-Bonferroni procedure.
Cluster allocation (ordinal severity levels 1-4) will be analyzed using proportional odds regression models with subject-level clustering to account for repeated measurements.
Clinical Relevance This study aims to clarify whether structural decompression of the cervical spine is associated with early recalibration of cervical sensorimotor control. Improved understanding of postoperative sensorimotor changes may inform development of targeted rehabilitation strategies following ACDF.
477 studies on the registry are indexed under Intervertebral Disc Displacement; 103 are open to participants now.
This study's planned enrollment of 30 is below the median of 63 across 344 interventional studies indexed under Intervertebral Disc Displacement.
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Surgical group:
Non-Surgical neck pain group:
Exclusion Criteria:
Participants diagnosed with cervical disc pathology and scheduled to undergo anterior cervical discectomy and fusion (ACDF) as part of standard clinical care. Cervical movement control will be assessed within one week prior to surgery and again one week after surgery using a standardized dynamic head-tracking task. Changes in movement-control parameters will be analyzed to evaluate early postoperative sensorimotor changes.
Procedure: Anterior Cervical Discectomy and Fusion
Participants diagnosed with neck pain who are not undergoing surgical treatment will serve as the comparison group. These participants will be assessed at two time points separated by a comparable interval to the surgical group. Cervical movement control will be evaluated using the same standardized dynamic head-tracking task. No surgical intervention will be performed during the study period.
Anterior cervical discectomy and fusion (ACDF) is a surgical procedure performed under general anesthesia to treat cervical disc herniation or degenerative disc disease causing nerve root or spinal cord compression. The procedure involves an anterior approach to the cervical spine, removal of the affected intervertebral disc (discectomy), decompression of neural structures, and placement of an interbody graft or cage with or without anterior plate fixation to achieve segmental fusion. The specific surgical technique and implant selection are determined by the treating spine surgeon according to standard clinical practice.
Change From Baseline in Time-on-Target at Medium Difficulty During Dynamic Cervical Head Tracking at 1 Week
Time-on-target is defined as the percentage of total trial time during which the head-controlled cursor remains within a predefined target zone while following an unpredictably moving visual target on a computer screen. Head motion is recorded using a head-mounted inertial measurement unit during a standardized dynamic tracking task. The medium difficulty level involves predefined target speed and trajectory complexity. Values range from 0% to 100%, with higher percentages indicating better tracking accuracy and movement control. Change from baseline to one week postoperatively will be calculated for analysis.
Time frame: Baseline (within 1 week prior to surgery) and 1 week after surgery
Change From Baseline in Amplitude Accuracy During Dynamic Cervical Head Tracking at 1 Week
Amplitude accuracy is defined as the mean spatial deviation, expressed in millimeters (mm), between a moving visual target and the head-controlled cursor during a standardized dynamic head-tracking task. Head motion is recorded using a head-mounted inertial measurement unit. Values are continuous and expressed in millimeters, with lower values indicating better tracking precision and movement control. Change from baseline to one week postoperatively will be calculated for analysis.
Time frame: Baseline (within 1 week prior to surgery) and 1 week after surgery
Change From Baseline in Undershoot During Dynamic Cervical Head Tracking at 1 Week
Undershoot is defined as the percentage of total trial time during which the head-controlled cursor remains behind the moving visual target while performing a standardized dynamic head-tracking task. Head motion is recorded using a head-mounted inertial measurement unit. Values range from 0% to 100%, with lower percentages indicating better tracking performance and improved temporal control. Change from baseline to one week postoperatively will be calculated for analysis.
Time frame: Baseline (within 1 week prior to surgery) and 1 week after surgery
Change From Baseline in Overshoot During Dynamic Cervical Head Tracking at 1 Week
Overshoot is defined as the percentage of total trial time during which the head-controlled cursor moves ahead of the moving visual target during a standardized dynamic head-tracking task. Head motion is recorded using a head-mounted inertial measurement unit. Values range from 0% to 100%, with lower percentages indicating better tracking precision and movement regulation. Change from baseline to one week postoperatively will be calculated for analysis.
Time frame: Baseline (within 1 week prior to surgery) and 1 week after surgery
Change From Baseline in Movement-Control Impairment Cluster Classification at 1 Week
Cluster classification represents an ordinal movement-control impairment category derived from multiple dynamic head-tracking parameters. Participants are assigned to one of four predefined severity levels (Cluster 1-4) using a standardized multidimensional classification framework based on tracking accuracy and timing variables. Cluster 1 indicates least impairment and Cluster 4 indicates greatest impairment. Change from baseline to one week postoperatively will be evaluated to determine whether participants shift to a lower or higher impairment category.
Time frame: Baseline (within 1 week prior to surgery) and 1 week after surgery
Plan to share: No — Individual participant data collected in this study will not be made publicly available. The sample size is relatively small and includes patients treated at a single clinical center, which may increase the risk of indirect participant identification despite de-identification procedures. Additionally, the dataset includes detailed movement-control performance variables and clinical characteristics that could potentially allow re-identification when combined with other publicly available information. Data were collected under informed consent and ethics approval that did not include provisions for public sharing of individual-level data. Aggregate results will be reported in scientific publications to ensure transparency while maintaining participant confidentiality.
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