Technical Pearls and Learning Curve in Cervical Disc Arthroplasty: A Single-Surgeon Experience of 52 Patients and 100 Levels

  • International Journal of Spine Surgery
  • September 2026,
  • 8960;
  • DOI: https://doi.org/10.14444/8960

Abstract

Background Although cervical disc arthroplasty (CDA) is an established motion-preserving alternative to anterior cervical discectomy and fusion (ACDF), literature describing surgical technique and the learning curve remains limited. This study describes key surgical principles refined during a single surgeon’s first 100 CDA levels and evaluates the associated learning curve.

Methods A retrospective review was performed of the first 100 CDA levels (52 patients) performed by a fellowship-trained spine surgeon between January 2024 and January 2026. Single-, double-, and triple-level CDA, as well as hybrid CDA-ACDF procedures, were included. Demographic, perioperative, radiographic, and clinical outcome data were collected. Operative duration, length of stay, and postoperative outcomes were analyzed. Risk-adjusted cumulative sum analysis was used to evaluate the surgical learning curve.

Results Operative duration increased significantly with procedural complexity (P < 0.001), while length of stay also differed according to operation type (P = 0.005). Risk-adjusted cumulative sum analysis demonstrated a learning curve with operative proficiency achieved after approximately 17 cases. Global cervical lordosis improved from 9.5° preoperatively to 15.5° postoperatively. Median modified Japanese Orthopedic Association improved from 16 to 18, Neck Disability Index decreased from 22 to 2, visual analog scale neck pain from 7 to 0, and visual analog scale upper limb pain from 4 to 0 (all P ≤ 0.002). Among patients with preoperative American Spinal Injury Association D status, 83.9% improved to American Spinal Injury Association E, with no neurological deterioration. Complications were uncommon.

Conclusions CDA can be performed safely and reproducibly with adherence to key technical principles. Progressive improvements in operative efficiency demonstrate a measurable learning curve, while favorable early radiographic and clinical outcomes support the safety and reproducibility of this technique during early adoption.

Clinical Relevance Recognition of technical pearls and the expected learning curve may facilitate safer implementation of CDA and improve operative efficiency.

Level of Evidence Level 4, Retrospective case series.

Introduction

Anterior cervical discectomy and fusion (ACDF) has been the benchmark procedure since 1958 for the surgical management of cervical degenerative disc disease.1 However, over the past decade, numerous studies have highlighted an increasing incidence of adjacent segment degeneration following ACDF.2–7 This phenomenon is thought to result from altered biomechanics and increased stress on levels adjacent to the fusion site.8

In response, cervical disc arthroplasty (CDA) has emerged as a motion-preserving alternative for treating cervical degenerative disc disease.9 Biomechanical cadaveric investigations have demonstrated that CDA maintains physiological motion at the operated level.10 A systematic review of published data further revealed a significantly lower rate of adjacent segment disease after CDA compared with ACDF, both in the short term (2 years) and medium to long term (4–7 years).11

Moreover, multiple clinical studies have reported superior or comparable outcomes with CDA relative to ACDF.12–15 Long-term follow-up from the US Food and Drug Administration Investigational Device Exemption trial for Prodisc-C confirmed noninferiority in pain, functional, and quality-of-life outcomes while demonstrating fewer secondary procedures at the index level compared with ACDF.16 Notably, the incidence of adjacent segment disease remained significantly lower for CDA up to 7 years postoperatively.17

Importantly, CDA is not simply an alternative implant choice to ACDF but a fundamentally different motion-preserving procedure with distinct biomechanical principles, technical demands, and patient selection considerations. Successful outcomes depend on meticulous surgical technique, precise implant positioning, and appropriate indication selection. Failure to adhere to these principles may predispose a patient to complications such as heterotopic ossification, suboptimal motion preservation, or, in rare cases, implant migration or dislocation.18 These considerations underscore the need for surgeons to fully appreciate the technical nuances of CDA during its adoption.

To our knowledge, only 1 study, by Federico et al, has examined the learning curve for CDA, reporting that experienced spine surgeons achieve proficiency after approximately 14 cases, with reduced operative efficiency but comparable clinical and radiographic outcomes.19 While numerous studies have compared and assessed the outcomes of CDA, relatively few reports have focused specifically on surgical technique and technical considerations, although prior studies have described practical considerations in multilevel CDA and expanded indications.20–26 Therefore, through this technical note, we aimed to characterize the learning curve of a single surgeon and to describe the key surgical principles, technical refinements, tips, and pearls developed over the surgeon’s first 100 CDA cases, supported by perioperative outcomes illustrating this experience.

Methodology

This was an Institutional Review Board-exempt retrospective cohort study conducted at a single tertiary institution (Centralised Institutional Review Board: 2024–3217). We reviewed the first 100 CDAs performed by a single fellowship-trained spine surgeon between January 2024 and January 2026. Included were patients who underwent single-, double-, or triple-level CDA, as well as hybrid procedures involving both arthroplasty and fusion. Those undergoing 3-level CDA were counseled preoperatively regarding the off-label use of the device, consistent with its use in expanded indications for CDA.20 Patients with active infection, patients with underlying malignancy, and those who underwent ACDF alone were excluded.

Demographic, perioperative, radiographic, and clinical data were extracted from the institutional electronic medical records. Demographic variables included age, sex, race, and body mass index (BMI). Perioperative variables comprised surgical indication, operation type, operative duration, and hospital length of stay (LOS). Clinical outcomes included the modified Japanese Orthopedic Association (mJOA) score, Neck Disability Index, American Spinal Injury Association (ASIA) Impairment Scale grade, visual analog scale (VAS) scores for neck pain and upper limb pain, and perioperative complications. Radiographic assessment included measurement of global cervical lordosis on preoperative and immediate postoperative lateral cervical radiographs.

Surgical Technique

In all patients, a right-sided skin-crease incision was used, and the disc spaces were accessed via the conventional Smith–Robinson approach.1 Discectomy, disc space releases, and implantation of CDA and ACDF prostheses were performed according to the respective surgical technique guides. Standard Prodisc C Nova chisels (Centinel Spine, LLC, West Chester, Pennsylvania) were used to create the keel cuts in all cases. Care was taken to minimize bone burring and osteophyte resection when deemed unnecessary. Drains were inserted postoperatively and removed on postoperative day 1.

Statistical Analysis

Statistical analyses were performed using SPSS Statistics version 29 (IBM Corp., Armonk, NY, USA). Continuous variables are presented as mean ± SD or median (interquartile range), as appropriate according to data distribution. Categorical variables are presented as frequencies and percentages. To compare the LOS between patients based on myelopathy status and operation type, the Mann-Whitney U test and Kruskal-Wallis test, respectively, were applied to assess the significance of each factor on LOS. Statistical significance was set at P < 0.05. Pre- and postoperative clinical outcome scores were compared using the Wilcoxon signed-rank test for paired observations, with subgroup analyses performed according to surgical indication.

A risk-adjusted cumulative sum (RA-CUSUM) analysis was performed to evaluate the surgical learning curve for operative duration. Multiple linear regression was first used to identify factors independently associated with operative duration. Variables entered into the model included procedure type, age, sex, race, BMI, and surgical indication. Variables not significantly associated with operative duration were excluded from the final model. Residuals (observed minus predicted operative duration) from the final regression model were cumulatively summed in chronological case order to construct the RA-CUSUM curve. The peak of the RA-CUSUM curve was interpreted as the estimated transition point from the learning phase to operative proficiency, consistent with previously described learning curve methodology.27

Results

A total of 52 patients undergoing CDA were included, encompassing 100 treated cervical disc levels. The mean patient age was 54.38 ± 13.27 years. Men constituted a slight majority of the cohort (61.5%). Radiculopathy was the most common surgical indication (55.8%), followed by myelopathy (26.9%) and myeloradiculopathy (15.4%). Mean symptom duration varied by indication and was longest for radiculopathy (11.56 ± 13.99 months), followed by myelopathy (9.93 ± 11.45 months) and myeloradiculopathy (9.71 ± 8.36 months). Isolated neck pain occurred in 1 patient; symptom duration was 12 months.

Regarding operative distribution, the most frequently treated levels were C5/C6 (38%), followed by C4/C5 (36%), C6/C7 (16%), and C3/C4 (10%). Single-level CDA was performed in 6 cases, 2-level CDA in 22 cases, and 3-level CDA in 9 cases. Hybrid procedures were also common, including 1-level CDA with 1-level ACDF in 6 cases and 2-level CDA with 1-level ACDF in 9 cases (Table 1). Across the 100 CDA levels, 69 spiked implants (67 Prodisc-C Vivo and 2 Simplify Disc) and 31 keeled implants (Prodisc-C Nova) were used.

View this table:
Table 1

Operation duration and LOS stratified by operation type.

Multiple linear regression was performed to identify factors associated with operative duration. Procedure type was the only independent predictor of operative duration (P < 0.001), whereas age (P = 0.587), sex (P = 0.557), race (P = 0.631), BMI (P = 0.311), and surgical indication (P = 0.795) were not significantly associated with operative duration. Consequently, procedure type was retained in the final risk-adjustment model used to construct the RA-CUSUM learning curve. Operative duration increased significantly with procedural complexity (Table 1), demonstrating a significant association with operation type (P < 0.001). Median operative duration increased from 105 (94–178) minutes for single-level CDA to 170 (140–211) minutes for 2-level CDA and 180 (165–213) minutes for 3-level CDA. Hybrid procedures required longer operative durations, with 1-level CDA plus 1-level ACDF taking 198 (175–214) minutes and 2-level CDA plus 1-level ACDF taking 240 (195–273) minutes.

The chronological distribution of operative duration is illustrated in Figure 1, demonstrating the increasing complexity of procedures performed over time and an overall trend toward shorter operative durations within procedure types with increasing surgical experience. After adjustment for procedural complexity using RA-CUSUM analysis, the learning curve demonstrated an initial upward phase followed by a sustained downward trend, with the inflection point indicating the transition toward operative proficiency (Figure 2). The RA-CUSUM curve reached its maximum at approximately case 17 before demonstrating a sustained downward trajectory, suggesting that operative proficiency was achieved after the initial 17 cases (Figure 2).

Chronological distribution of operative duration by operation type. ACDF = anterior cervical discectomy and fusion; CDA = cervical disc arthroplasty.
Figure 1

Chronological distribution of operative duration by operation type. ACDF = anterior cervical discectomy and fusion; CDA = cervical disc arthroplasty.

RA-CUSUM learning curve of operative duration over 100 CDA levels. CDA = cervical disc arthroplasty; RA-CUSUM = risk-adjusted cumulative sum.
Figure 2

RA-CUSUM learning curve of operative duration over 100 CDA levels. CDA = cervical disc arthroplasty; RA-CUSUM = risk-adjusted cumulative sum.

LOS differed significantly according to operation type (P = 0.005), increasing progressively with procedural complexity (Table 1). Median LOS increased from 2 (2–5) days for single-level CDA to 8 (4–14) days for 2-level CDA combined with 1-level ACDF. Although patients with myelopathy demonstrated a longer LOS than those without myelopathy, this difference did not reach statistical significance (P = 0.096).

Median mJOA score significantly improved from 16 (IQR 15–16) preoperatively to 18 (IQR 17–18) postoperatively (Wilcoxon signed-rank test, P < 0.001). Median Neck Disability Index significantly decreased from 22 (IQR 7–33) preoperatively to 2 (IQR 0–12) postoperatively (P < 0.001). Median VAS neck pain score significantly decreased from 7 (IQR 0–9) preoperatively to 0 (IQR 0–3) postoperatively (P < 0.001), while median VAS upper limb pain score significantly decreased from 4 (IQR 0–9) preoperatively to 0 (IQR 0–3) postoperatively (P = 0.002). Among the 31 patients with preoperative ASIA D neurological status, 26 (83.9%) improved to ASIA E postoperatively, while 5 (16.1%) remained ASIA D. No patient experienced postoperative neurological deterioration.

When stratified by surgical indication, median preoperative and postoperative mJOA scores significantly improved from 14 (IQR 13–15) to 17 (IQR 14–18; P = 0.011), respectively, among patients with myelopathy, 15 (IQR 15–015) to 18 (IQR 17–18; P = 0.041) among those with myeloradiculopathy, and 16 (IQR 16–16) to 18 (IQR 17–18; P < 0.001) among those with radiculopathy (Table 2). Among patients with preoperative ASIA D status, 8 of 9 patients (88.9%) in the myelopathy group, 3 of 4 patients (75.0%) in the myeloradiculopathy group, and 15 of 18 patients (83.3%) in the radiculopathy group improved to ASIA E postoperatively. No patients in any surgical indication group experienced postoperative neurological deterioration.

View this table:
Table 2

Clinical and neurological outcomes stratified by surgical indication.

Global cervical lordosis improved from 9.5° preoperatively to 15.5° immediately postoperatively. A weak positive correlation was observed between patient age and preoperative global cervical lordosis (r = 0.293, P = 0.039). However, no significant correlation was identified between age and postoperative global cervical lordosis (r = 0.224, P = 0.111). Complications were uncommon and included 1 case of hemiparesis owing to suspected reperfusion injury with eventual full recovery, 1 case of dysphagia, and 2 intraoperative durotomies without impact on postoperative recovery.

Technical Pearls

Preoperative Positioning

Preoperative patient positioning is a critical preparatory step (Figure 3). Proper taping and securement, with the aid of commercially available positioning devices, facilitate optimal alignment. The patient should be positioned in a neutral orientation, avoiding axial rotation, lateral flexion, and excessive flexion or extension in the sagittal plane. Accurate neutral positioning is essential, as implantation performed in a hyperextended position may result in subsequent kyphotic alignment of the prosthesis, whereas implantation in a flexed position may predispose the prosthesis to excessive lordotic alignment.

Coronal and sagittal views of preoperative patient positioning.
Figure 3

Coronal and sagittal views of preoperative patient positioning.

Caspar Pin Placement

Appropriate Caspar pin positioning is critical to the success of CDA. The Caspar distraction system, originally described by Caspar as a method of controlled cervical intervertebral distraction and stabilization during anterior cervical surgery, remains a fundamental component of modern CDA and anterior cervical discectomy procedures.28 The primary purpose of the Caspar pins is to facilitate controlled, symmetric distraction of the disc space following adequate release, rather than to serve as the primary means of achieving distraction. Ideally, the pins should be placed in the midline on the anteroposterior plane and oriented parallel to the far endplates of the involved vertebral bodies and to each other (Figures 4 and 5), consistent with the original principles described by Caspar.28 Accurate pin placement facilitates controlled, symmetric distraction along the intended axis following adequate disc space release. As distraction is applied, a modest increase in segmental lordosis is expected, with the Caspar pins accommodating this physiological angulation while maintaining symmetric distraction. In contrast, improper Caspar pin positioning may result in asymmetric distraction and introduce shear, rotational, lordotic, or kyphotic forces, resulting in suboptimal prosthesis positioning and compromised long-term alignment. Pin placement should also account for the anticipated keel trajectory, where applicable. The authors recommend preoperative measurement of the length of the Caspar pins required using x-ray imaging. In addition, Caspar pin placement should ideally be accurate on the first attempt, as repeated insertion enlarges the bony tract and may compromise secure pin fixation and vertebral body purchase.

Axial view of Caspar pin placement, parallel to each other. Blue = ideal; red = suboptimal owing to rotational stress on implants.
Figure 4

Axial view of Caspar pin placement, parallel to each other. Blue = ideal; red = suboptimal owing to rotational stress on implants.

Sagittal view of Caspar pin placement, parallel to each other. Blue = ideal; red = suboptimal owing to shear forces (left) and lordotic/kyphotic forces (right).
Figure 5

Sagittal view of Caspar pin placement, parallel to each other. Blue = ideal; red = suboptimal owing to shear forces (left) and lordotic/kyphotic forces (right).

An equally critical but often underemphasized step in CDA is achieving an adequate circumferential and symmetric release of the disc space before controlled distraction is applied. Intraoperative fluoroscopy provides a valuable real-time indicator of release adequacy, with symmetric opening of the disc space reflecting balanced decompression of the anterior annulus, uncovertebral joints, and posterior elements (Figure 6). Incomplete or asymmetric release may result in uneven endplate loading, malpositioned implants, increased risk of heterotopic ossification, suboptimal restoration of physiological motion, and, in rare cases, implant migration or dislocation.18 Meticulous attention to this step is therefore fundamental to achieving stable implant seating and durable outcomes in CDA.

Intraoperative fluoroscopy of Caspar pins with parallel distraction reflecting balanced decompression of the anterior annulus, uncovertebral joints, and posterior elements.
Figure 6

Intraoperative fluoroscopy of Caspar pins with parallel distraction reflecting balanced decompression of the anterior annulus, uncovertebral joints, and posterior elements.

Endplate Preparation

During endplate preparation, the primary objective is to optimize congruency between the prepared vertebral endplates and the selected prosthesis to achieve stable implant seating and reduce the risk of implant subsidence.29 Kerrison rongeurs, curettes, and burrs may be used as required to achieve an appropriate endplate contour. Burring should be performed judiciously and reserved for situations where necessary, such as correcting asymmetrical uncinate processes that may lead to prosthesis tilting in the anteroposterior plane. In general, exposed bony cut surfaces should be minimized to reduce the risk of heterotopic ossification.30 Copious irrigation is also recommended to remove bone debris that may further contribute to heterotopic ossification.

Implant Placement

In the coronal plane, bony landmarks such as the interpedicular midpoints and medial borders of the uncinate processes are useful landmarks to ensure proper midline positioning of the implant.24,31 When applicable, careful planning and execution of keel cuts are essential to achieve true midline implant placement. Eccentric or nonmidline placement of the prosthesis may lead to asymmetric loading and altered kinematics of the cervical motion segment, potentially resulting in abnormal motion or clinical symptoms due to uneven facet and soft-tissue forces.32

In the sagittal plane, attention must be paid to the intended postoperative alignment, particularly with respect to kyphosis or lordosis. When the patient is appropriately positioned in a neutral alignment intraoperatively, we recommend positioning the superior implant component slightly more posteriorly to achieve a mildly lordotic orientation, thereby optimizing final sagittal alignment. Figure 7A, middle CDA level C4/C5, illustrates a case in which implant positioning appeared satisfactory on intraoperative fluoroscopy but resulted in postoperative kyphotic alignment. In contrast, Figure 7B lower CDA level C5/6 demonstrates posterior positioning of the superior plate to achieve a neutral alignment on postoperative imaging.

Sagittal imaging. (A) Intra-operative image intensifier and (B) postoperative radiograph. In middle CDA level C4/5, implant position was satisfactory in image A but kyphotic in image B. In lower CDA level C5/6, superior implant component positioned posteriorly in image A, and eventual implant position satisfactory in image B.
Figure 7

Sagittal imaging. (A) Intra-operative image intensifier and (B) postoperative radiograph. In middle CDA level C4/5, implant position was satisfactory in image A but kyphotic in image B. In lower CDA level C5/6, superior implant component positioned posteriorly in image A, and eventual implant position satisfactory in image B.

Implant Options

A wide range of CDA implants is currently available. One of the key differentiating design features among these implants is the method of endplate fixation. The 2 most commonly used anchoring mechanisms are keels (or slots) and spikes. The Prodisc-C cervical disc prosthesis was first implanted in Europe in 2002 and subsequently received US Food and Drug Administration approval in 2007.33 At present, the Prodisc CDA system is unique in offering both keeled and spiked fixation options (Centinel Spine, West Chester, Pennsylvania).

The keeled variants include the original Prodisc-C and Prodisc-C SK, both of which utilize a single midline keel on the superior and inferior endplates, with the Prodisc-C SK featuring a reduced-profile keel compared with the original Prodisc-C. The Prodisc-C Nova incorporates a low-profile tri-keel configuration, consisting of a single midline keel on the superior endplate and 2 keels on the inferior endplate, a design intended to facilitate improved implant stacking in multilevel applications. In contrast, the Prodisc-C Vivo employs a spiked fixation mechanism and features a domed superior endplate.

Implantation of the Prodisc-C Nova requires the use of a keel chisel to accommodate the central keel within the adjacent vertebral bodies. The author prefers the use of a manual chisel over the airpen, as it allows greater tactile feedback and more controlled keel preparation. Vertical split fractures of the vertebral body during keel preparation have been reported in lumbar disc arthroplasty, and a similar theoretical risk may be extrapolated to the cervical spine.34 In this context, the Prodisc-C Vivo, which utilizes a spiked fixation mechanism and does not require keel preparation, represents a potential alternative that avoids this specific risk. In the context of nickel hypersensitivity, Simplify Disc is an alternative option with titanium alloy endplates and a ceramic core. In our study, across the 100 CDA levels, 67 used Prodisc-C Vivo, 31 used Prodisc-C Nova, and 2 used the Simplify Disc due to nickel allergy.

Implant selection should take into account endplate characteristics of levels to be treated. We recommend using prostheses that allow the biggest endplate footprint, while avoiding overstuffing in terms of prosthesis height to ensure appropriate mobility. All implants were 5 mm height, with only 1 level utilizing a 6 mm height implant. In the sagittal plane, the morphology of the inferior vertebral endplate should guide prosthesis selection. The authors recommend using a domed prosthesis for a concave inferior vertebral endplate and a flat prosthesis for a flat inferior vertebral endplate. This can be assessed by measuring the endplate concavity depth (ECD; Figure 8). In our practice, domed, spiked implants are preferentially used for disc spaces with an ECD greater than 2 mm, whereas flat, keeled implants are selected for discs with an ECD less than 2 mm. An example of ECD-guided implant selection is shown in Figure 9. This tailored approach, together with meticulous endplate preparation, aims to optimize implant-endplate congruency, thereby potentially reducing implant-related complications and improving clinical outcomes. Nevertheless, further outcome-based studies are required to validate this strategy.

Endplate concavity depth represented by ‘f’.
Figure 8

Endplate concavity depth represented by ‘f’.

Representative pre- and postoperative radiographs demonstrating endplate concavity depth (ECD)-guided implant selection. The C5/6 level exhibits a flatter ECD and was treated with a flat keeled implant, whereas the C4/5 and C6/7 levels demonstrate more curved endplates and were treated with domed spiked implants to optimize endplate congruency.
Figure 9

Representative pre- and postoperative radiographs demonstrating endplate concavity depth (ECD)-guided implant selection. The C5/6 level exhibits a flatter ECD and was treated with a flat keeled implant, whereas the C4/5 and C6/7 levels demonstrate more curved endplates and were treated with domed spiked implants to optimize endplate congruency.

Discussion

This technical note describes a series of practical surgical principles for CDA refined over the first 52 patients of 100 levels by a single surgeon, supported by perioperative, radiographic, and early clinical outcomes that illustrate both a learning curve and the clinical relevance of meticulous surgical technique. While this study was not designed to evaluate long-term clinical efficacy, the observed trends in operative efficiency, maintenance of sagittal alignment, and low complication rates provide reassurance regarding the reproducibility and safety of the described approach.

Global cervical lordosis improved following CDA, reflecting restoration of sagittal alignment. Unlike the large magnetic resonance imaging–based morphological study by Guvercin et al, who reported a reduction in cervical lordosis with increasing age in patients presenting with neck pain,35 our cohort demonstrated only a weak positive correlation between age and preoperative cervical lordosis, with no significant association observed postoperatively. These differences likely reflect the distinct characteristics of our study population, which comprised carefully selected patients undergoing CDA rather than an unselected cohort with degenerative cervical disease. Furthermore, postoperative cervical alignment is influenced not only by baseline morphology but also by surgical restoration of disc height, implant positioning, and overall sagittal alignment.

Although the present study was not designed to evaluate long-term clinical efficacy, patients demonstrated significant early improvements in neurological function, disability, and pain scores following surgery. These findings are consistent with the established literature supporting the effectiveness of CDA and provide reassurance that the technical principles described can be implemented safely during the learning phase.

Our data demonstrate a clear and graded relationship between procedural complexity and perioperative metrics, with both operative duration and LOS increasing stepwise as the number of treated levels increased and with the addition of hybrid constructs. Supporting this observation, large retrospective analyses have identified longer operative duration as an independent predictor of prolonged LOS following CDA.36 This finding is expected given the greater exposure, preparation, and instrumentation demands of multilevel and combined procedures.37 Additionally, meta-analytic data suggest that CDA is frequently associated with longer operative times than ACDF, despite comparable or favorable clinical outcomes and safety profiles.38 Our experience mirrors this pattern, with operative duration increasing with procedural complexity but demonstrating a progressive reduction over time, consistent with a learning curve effect.19 The RA-CUSUM analysis further demonstrated an inflection point at approximately case 17, suggesting transition from the learning phase to operative proficiency after adjustment for procedural complexity. Operative duration may be conceptualized as comprising both fixed and variable components. Fixed components, such as surgical exposure and wound closure, are largely independent of the number of treated levels, whereas variable components increase with procedural complexity owing to additional discectomy, endplate preparation, and implant insertion. This likely explains why operative duration did not increase proportionally with each additional CDA level. Although patients with myelopathy demonstrated a trend toward longer LOS, this association did not reach statistical significance, suggesting that procedural complexity may have been a more important determinant of hospitalization duration in this cohort. This finding underscores that CDA is a technique-dependent procedure rather than a direct analog of ACDF.

Beyond these supporting outcomes, the central message of this article is that CDA is not simply an alternative implant choice to ACDF, but a fundamentally different motion-preserving procedure with distinct biomechanical goals and technical demands. Previous studies of multilevel cervical arthroplasty have similarly demonstrated the feasibility of multilevel CDA, with clinical and radiological outcomes supporting its use in appropriately selected patients.24 Errors in positioning, release, endplate preparation, or implant placement may compromise motion preservation and predispose to complications such as heterotopic ossification, malalignment, or, in rare cases, implant migration or dislocation.18 Accordingly, the technical steps outlined, including neutral patient positioning, precise and parallel Caspar pin placement, adequate circumferential and symmetric release, judicious endplate preparation, and accurate midline implant positioning in both coronal and sagittal planes, are not merely procedural preferences but critical determinants of successful arthroplasty.

Finally, thoughtful implant selection based on endplate morphology represents an additional layer of technical refinement that may improve implant-bone congruency and stability, particularly in multilevel constructs. While the proposed use of ECD as a guide is pragmatic and intuitive, further studies are needed to validate this strategy against long-term clinical and radiographic outcomes.

Limitations

This study has several limitations. First, it represents the experience of a single surgeon at a single institution, which may limit the generalizability of the technical recommendations. Second, the study focuses on early perioperative outcomes and was not designed to evaluate long-term clinical or radiographic outcomes. Finally, LOS should be interpreted within the context of local clinical practice. At our institution, CDA is routinely performed as an inpatient procedure, whereas in some healthcare systems, selected patients may undergo CDA on an outpatient or same-day discharge basis. Consequently, the LOS reported in this study may not be directly generalizable to institutions with different perioperative care pathways.

Conclusion

Successful CDA requires meticulous attention to surgical technique, beginning with accurate preoperative positioning and extending through Caspar pin placement, endplate preparation, implant positioning, and implant selection. Neutral patient alignment, parallel distraction, and precise midline implant placement in both the coronal and sagittal planes are essential to achieving optimal prosthesis alignment and preserving physiological cervical motion. Judicious endplate preparation and thoughtful consideration of implant anchoring mechanisms further help minimize complications such as implant malalignment, subsidence, and heterotopic ossification. Tailoring implant choice to individual disc morphology may enhance implant-endplate congruency and surgical outcomes. Collectively, adherence to these technical principles provides a practical framework for safe and efficient CDA, supporting reproducibility during early adoption and learning.

Footnotes

  • Funding This publication was supported by the SingHealth Fund under its “SHF - Changi General Hospital Fund”.

  • Declaration of Conflicting Interests The authors report no conflicts of interest in this work.

  • Ethics Approval SingHealth CIRB Reference: 2024–3217.

References

  1. 1.
    ↵
    Smith GW , Robinson RA . The treatment of certain cervical-spine disorders by anterior removal of the intervertebral disc and interbody fusion. J Bone Joint Surg Am. 1958;40(3):607–624. 10.2106/00004623-195840030-00009
    Google ScholarOpenURLCrossRefFull TextPubMed
  2. 2.
    ↵
    Bydon M , Xu R , Macki M , et al . Adjacent segment disease after anterior cervical discectomy and fusion in a large series. Neurosurgery. 2014;74(2):139–146. 10.1227/NEU.0000000000000204
    Google ScholarOpenURLCrossRef
  3. 3.
    ↵
    Nunley PD , Kerr EJ , Cavanaugh DA , et al . Adjacent segment pathology after treatment with cervical disc arthroplasty or anterior cervical discectomy and fusion, part 1: radiographic results at 7-year follow-up. Int J Spine Surg. 2020;14(3):269–277. 10.14444/7036
    Google ScholarOpenURLCrossRefAbstract/Full TextPubMed
  4. 4.
    ↵
    Hilibrand AS , Carlson GD , Palumbo MA , Jones PK , Bohlman HH . Radiculopathy and myelopathy at segments adjacent to the site of a previous anterior cervical arthrodesis. J Bone Joint Surg Am. 1999;81(4):519–528. 10.2106/00004623-199904000-00009
    Google ScholarOpenURLCrossRefAbstract/Full TextPubMed
  5. 5.
    ↵
    Ishihara H , Kanamori M , Kawaguchi Y , Nakamura H , Kimura T . Adjacent segment disease after anterior cervical interbody fusion. Spine J. 2004;4(6):624–628. 10.1016/j.spinee.2004.04.011
    Google ScholarOpenURLCrossRefPubMed
  6. 6.
    ↵
    Robertson JT , Papadopoulos SM , Traynelis VC . Assessment of adjacent-segment disease in patients treated with cervical fusion or arthroplasty: a prospective 2-year study. J Neurosurg Spine. 2005;3(6):417–423. 10.3171/spi.2005.3.6.0417
    Google ScholarOpenURLCrossRefPubMedWeb of Science
  7. 7.
    ↵
    Yue W-M , Brodner W , Highland TR . Long-term results after anterior cervical discectomy and fusion with allograft and plating: a 5- to 11-year radiologic and clinical follow-up study. Spine. 2005;30(19):2138–2144. 10.1097/01.brs.0000180479.63092.17
    Google ScholarOpenURLCrossRefPubMed
  8. 8.
    ↵
    Matsunaga S , Kabayama S , Yamamoto T , Yone K , Sakou T , Nakanishi K . Strain on intervertebral discs after anterior cervical decompression and fusion. Spine. 1999;24(7):670–675. 10.1097/00007632-199904010-00011
    Google ScholarOpenURLCrossRefPubMedWeb of Science
  9. 9.
    ↵
    Niedzielak TR , Ameri BJ , Emerson B , Vakharia RM , Roche MW , Malloy JP . Trends in cervical disc arthroplasty and revisions in the medicare database. J Spine Surg. 2018;4(3):522–528. 10.21037/jss.2018.09.04
    Google ScholarOpenURLCrossRef
  10. 10.
    ↵
    Puttlitz CM , Rousseau MA , Xu Z , Hu S , Tay BK-B , Lotz JC . Intervertebral disc replacement maintains cervical spine kinetics. Spine. 2004;29(24):2809–2814. 10.1097/01.brs.0000147739.42354.a9
    Google ScholarOpenURLCrossRefPubMedWeb of Science
  11. 11.
    ↵
    Findlay C , Ayis S , Demetriades AK . Total disc replacement versus anterior cervical discectomy and fusion: a systematic review with meta-analysis of data from a total of 3160 patients across 14 randomized controlled trials with both short- and medium- to long-term outcomes. Bone Joint J. 2018;100-B(8):991–1001. 10.1302/0301-620X.100B8.BJJ-2018-0120.R1
    Google ScholarOpenURLCrossRef
  12. 12.
    ↵
    Almasi A , Jafari S , Solouki L , Darvishi N . The best surgical treatment for cervical radiculopathy: a systematic review and network meta-analysis. Adv Biomed Res. 2023;12(1):191. 10.4103/abr.abr_251_22
    Google ScholarOpenURLCrossRef
  13. 13.
    ↵
    Gornet MF , Lanman TH , Burkus JK , et al . Two-level cervical disc arthroplasty versus anterior cervical discectomy and fusion: 10-year outcomes of a prospective, randomized investigational device exemption clinical trial. J Neurosurg Spine. 2019;31(4):508–518. 10.3171/2019.4.SPINE19157
    Google ScholarOpenURLCrossRef
  14. 14.
    ↵
    Yao Q , Liang F , Xia Y , Jia C . A meta-analysis comparing total disc arthroplasty with anterior cervical discectomy and fusion for the treatment of cervical degenerative diseases. Arch Orthop Trauma Surg. 2016;136(3):297–304. 10.1007/s00402-015-2337-0
    Google ScholarOpenURLCrossRef
  15. 15.
    ↵
    Zou S , Gao J , Xu B , Lu X , Han Y , Meng H . Anterior cervical discectomy and fusion (ACDF) versus cervical disc arthroplasty (CDA) for two contiguous levels cervical disc degenerative disease: a meta-analysis of randomized controlled trials. Eur Spine J. 2017;26(4):985–997. 10.1007/s00586-016-4655-5
    Google ScholarOpenURLCrossRef
  16. 16.
    ↵
    Janssen ME , Zigler JE , Spivak JM , Delamarter RB , Darden BV , Kopjar B . ProDisc-C total disc replacement versus anterior cervical discectomy and fusion for single-level symptomatic cervical disc disease: seven-year follow-up of the prospective randomized US Food and Drug Administration Investigational Device Exemption study. J Bone Joint Surg Am. 2015;97(21):1738–1747. 10.2106/JBJS.N.01186
    Google ScholarOpenURLCrossRefAbstract/Full TextPubMed
  17. 17.
    ↵
    Spivak JM , Zigler JE , Philipp T , Janssen M , Darden B , Radcliff K . Segmental motion of cervical arthroplasty leads to decreased adjacent-level degeneration: analysis of the 7-year postoperative results of a multicenter randomized controlled trial. Int J Spine Surg. 2022;16(1):186–193. 10.14444/8187
    Google ScholarOpenURLCrossRefAbstract/Full TextPubMed
  18. 18.
    ↵
    Aurangzeb A , Dinesh SK , Leong D , Teo HLT , Janssen ME , Chew Z . Cervical disc arthroplasty implant migration and dislocation: a systematic review of patterns, risk factors, and surgical outcomes. Global Spine J. 2026;16(5):2416–2423. 10.1177/21925682251409659
    Google ScholarOpenURLCrossRef
  19. 19.
    ↵
    Federico VP , Nie JW , Hartman TJ , et al . The surgical learning curve for cervical disk replacement. Clin Spine Surg. 2024;37(2):E82–E88. 10.1097/BSD.0000000000001530
    Google ScholarOpenURLCrossRef
  20. 20.
    ↵
    Alves ÓL . Cervical total disc replacement: expanded indications. Neurosurg Clin N Am. 2021;32(4):437–448. 10.1016/j.nec.2021.05.002
    Google ScholarOpenURLCrossRef
  21. 21.
    ↵
    LeRoy TE , Aidlen JP . Cervical disc arthroplasty: tips and tricks. Oper Tech Orthop. 2024;34(1):101093. 10.1016/j.oto.2024.101093
    Google ScholarOpenURLCrossRef
  22. 22.
    ↵
    Leven D , Meaike J , Radcliff K , Qureshi S . Cervical disc replacement surgery: indications, technique, and technical pearls. Curr Rev Musculoskelet Med. 2017;10(2):160–169. 10.1007/s12178-017-9398-3
    Google ScholarOpenURLCrossRef
  23. 23.
    ↵
    Nunley P , Schouwen KFV , Stone M . Cervical total disc replacement: indications and technique. Neurosurg Clin N Am. 2021;32(4):419–424. 10.1016/j.nec.2021.05.001
    Google ScholarOpenURLCrossRef
  24. 24.
    ↵
    Reinas R , Kitumba D , Pereira L , Baptista AM , Alves ÓL . Multilevel cervical arthroplasty-clinical and radiological outcomes. J Spine Surg. 2020;6(1):233–242. 10.21037/jss.2020.01.09
    Google ScholarOpenURLCrossRef
  25. 25.
    ↵
    Sekhon LHS , Ball JR . Artificial cervical disc replacement: principles, types and techniques. Neurol India. 2005;53(4):445–450. 10.4103/0028-3886.22611
    Google ScholarOpenURLCrossRefPubMed
  26. 26.
    ↵
    Smucker JD , Sasso RC . Anterior cervical disc replacement: indications, techniques, and outcomes. Semin Spine Surg. 2016;28(2):97–106. 10.1053/j.semss.2015.11.005
    Google ScholarOpenURLCrossRef
  27. 27.
    ↵
    McNamee C , Keraidi S , McDonnell J , et al . Learning curve analyses in spine surgery: a systematic simulation-based critique of methodologies. Spine J. 2024;24(10):1789–1810. 10.1016/j.spinee.2024.05.014
    Google ScholarOpenURLCrossRef
  28. 28.
    ↵
    Caspar W . CASPAR evolution-system: anterior cervical plating. Aesculap AG. 1984. https://uhlmedical.com/wp-content/uploads/2023/05/CASPARTECH.pdf.
    Google Scholar
  29. 29.
    ↵
    Cheng C-C , Ordway NR , Zhang X , Lu Y-M , Fang H , Fayyazi AH . Loss of cervical endplate integrity following minimal surface preparation. Spine. 2007;32(17):1852–1855. 10.1097/BRS.0b013e31811ece5a
    Google ScholarOpenURLCrossRefPubMed
  30. 30.
    ↵
    Sheng X-Q , Wu T-K , Liu H , Meng Y . Incidence of heterotopic ossification at 10 years after cervical disk replacement: a systematic review and meta-analysis. Spine. 2023;48(13):E203–E215. 10.1097/BRS.0000000000004674
    Google ScholarOpenURLCrossRef
  31. 31.
    ↵
    Derman PB , Waldorff E , Zhang N , Haddas R . Accuracy of various fluoroscopic landmarks for determination of midline implant placement within the cervical disc space. Eur Spine J. 2021;30(2):554–559. 10.1007/s00586-020-06638-7
    Google ScholarOpenURLCrossRef
  32. 32.
    ↵
    McAfee P , Gloystein D , Cunningham B . Failed disc replacement. Rothman-Simeonethe Spine, Vol II. Elsevier, Philadelphia; 2011:1825–1839. 10.1016/B978-1-4160-6726-9.00100-0
    Google ScholarOpenURLCrossRef
  33. 33.
    ↵
    Murrey D , Janssen M , Delamarter R , et al . Results of the prospective, randomized, controlled multicenter food and drug administration investigational device exemption study of the prodisc-c total disc replacement versus anterior discectomy and fusion for the treatment of 1-level symptomatic cervical disc disease. Spine J. 2009;9(4):275–286. 10.1016/j.spinee.2008.05.006
    Google ScholarOpenURLCrossRefPubMedWeb of Science
  34. 34.
    ↵
    Shim CS , Lee S , Maeng DH , Lee S-H . Vertical split fracture of the vertebral body following total disc replacement using prodisc. Clin Spine Surg. 2005;18(5):465–469. 10.1097/01.bsd.0000159035.35365.df
    Google ScholarOpenURLCrossRef
  35. 35.
    ↵
    Guvercin AR , Arslan E , Hacifazlioglu C , Kanat A , Arslan EA , Yazar U . Age- and gender-related radiological changes of the cervical spine: a study with largest magnetic resonance imaging database of 5672 consecutive patients. J Craniovertebr Junction Spine. 2023;14(1):84–92. 10.4103/jcvjs.jcvjs_9_23
    Google ScholarOpenURLCrossRef
  36. 36.
    ↵
    Zeidan M , Goz V , Lakomkin N , Spina N , Brodke DS , Spiker WR . Predictors of readmission and prolonged length of stay after cervical disc arthroplasty. Spine. 2021;46(8):487–491. 10.1097/BRS.0000000000003839
    Google ScholarOpenURLCrossRef
  37. 37.
    ↵
    Katz AD , Song J , Bowles D , et al . What is a better value for your time? anterior cervical discectomy and fusion versus cervical disc arthroplasty. J Craniovertebr Junction Spine. 2022;13(3):331–338. 10.4103/jcvjs.jcvjs_69_22
    Google ScholarOpenURLCrossRef
  38. 38.
    ↵
    Xie L , Liu M , Ding F , Li P , Ma D . Cervical disc arthroplasty (CDA) versus anterior cervical discectomy and fusion (ACDF) in symptomatic cervical degenerative disc diseases (CDDDs): an updated meta-analysis of prospective randomized controlled trials (RCTs). Springerplus. 2016;5(1):1188. 10.1186/s40064-016-2851-8
    Google ScholarOpenURLCrossRef
View Abstract
Loading
Loading
PDF