Comparison of Hybrid Constructs with 2-Level Artificial Disc Replacement and 2-Level Anterior Cervical Discectomy and Fusion for Surgical Reconstruction of the Cervical Spine: A Kinematic Study in Whole Cadavers

Abstract

BackgroundMulti-level cervical degeneration of the spine is a common clinical pathology that is often repaired by anterior cervical discectomy and fusion (ACDF).The aim of this study was to investigate the kinematics of the cervical spine after hybrid surgery compared with 2-level ACDF.Material/MethodsFive freshly frozen, unembalmed whole human cadavers were used including 3 males and 2 females with a mean age of 51±8 years. After evaluating the intact spine for range of motion (ROM), sagittal alignment and instantaneous center of rotation (ICR), each cadaver underwent 4 consecutive surgeries: 2-level artificial disc replacement (ADR) from C4 to C6 (ADR surgery); 2-level ACDF from C4 to C6 (ACDF surgery); hybrid C4–5 ACDF and C5–6 ADR (ACDF+ADR surgery); and hybrid C4–5 ADR and C5–6 ACDF (ADR+ACDF surgery). The ROM and ICR of adjacent intact segments (C3–4; C6–7), and whole sagittal alignment were revaluated.ResultsTwo-level ACDF resulted in increased ROM at C3–4 and C6–7 compared with intact spine. ROM was significantly different to intact spine using ACDF surgery at C3–C4 and C6–C7 and ROM was increased with ACDF+ADR surgery at C6–C7 (all P<0.05). No improvement in sagittal alignment was observed with any approach. The localization of the ICR shifted upwards and anteriorly at C3–C4 after reconstruction. ICR changes at C3–C4 were greatest for ADR+ACDF surgery and were significantly different to ACDF surgery (P<0.05), but not between ADR surgery and ACDF+ADR surgery. At C6–C7, the ICR was more posterior and superior than in the intact condition. The greatest change in ICR was observed in ACDF surgery at the C6–C7 level, significantly different from the other groups (P<0.05).ConclusionsFor 2-level reconstruction, hybrid surgery and ADR did not alter ROM and minimally changed ICR at the adjacent-level. The type of surgery had a significant impact on the ICR location. This suggests that hybrid surgery may be a viable option for 2-level cervical surgery.

A Modified Laminoplasty Technique to Treat Cervical Myelopathy Secondary to Ossification of the Posterior Longitudinal Ligament (OPLL)

“…In the present study, adjacent segment disease was not compared between the modified laminoplasty and combined anterior-posterior approaches due to a short follow-up period. Although the motion-sparing nature of laminoplasty may be protective against adjacent segment disease [ 13 ], the non-fusion strategy of anterior approach, such as artificial disc replacement and hybrid surgery, could also increase adjacent motion [ 14 – 16 ].…”

Biomechanics of Artificial Disc Replacements Adjacent to a 2-Level Fusion in 4-Level Hybrid Constructs: An In Vitro Investigation

“…Faizan et al [ 24 ] revealed that the spinal stiffness after HS was far closer to intact construct in all bending motions except extension, compared to 2-level fusion. Liu et al [ 25 ] showed that 2-level hybrid surgery and ACDR did not alter ROM and minimally changed ICR at the adjacent levels compared to 2-level fusion. For 3-level cervical surgery, Ding et al [ 26 ] stated that HS may be a rational alternative to ACDF for 3-level cervical disease due to the equivalent or improved early clinical outcomes, with less impact at adjacent levels.…”

Cervical Disc Arthroplasty: A Comprehensive Review of Single-Level, Multilevel, and Hybrid Procedures

“…33 The instantaneous center of rotation (ICR) is a measure used to detect abnormal cervical spine mobility. A recent biomechanical analysis on full cadaveric specimens by Liu et al 34 showed that both hybrid surgery and CDA in 2-level reconstructions did not alter ROM and minimally changed the ICR at levels adjacent to the construct when compared with fusion alone. Both the hybrid and CDA constructs preserved not only quantitative motion but also qualitative motion by maintaining a near native ICR.…”

“…Both the hybrid and CDA constructs preserved not only quantitative motion but also qualitative motion by maintaining a near native ICR. 34 There still remains a lack of high-quality evidence in favor of arthroplasty, ACDF, or HS for the treatment of multilevel DDD.…”

“…Several concerns have been arisen with regard to multilevel CDA constructs, including: development of heterotopic ossification (HO), longer surgical times, increased blood loss, spinal unit malalignment, osteolysis, vertebral body fracture, implant displacement, metal hypersensitivity reaction, and loss of lordosis and/or disc space. 21,34 HO is a well-recognized complication following total disc replacements, with an incidence of 16% to 63% occurrence at treated levels postoperatively. 24,35 HO development has a significant impact on cervical motion especially when there is bridging ossification across the disc space.…”