The Changes in Range of Motion after a Lumbar Spinal Arthroplasty with Charité™ in the Human Cadaveric Spine under Physiologic Compressive Follower Preload : A Comparative Study between Load Control Protocol and Hybrid Protocol

Abstract

Objective: To compare two testing protocols for evaluating range of motion (ROM) changes in the preloaded cadaveric spines implanted with a mobile core type Charité ™ lumbar artificial disc. Methods: Using five human cadaveric lumbosacral spines (L2-S2), baseline ROMs were measured with a bending moment of 8 Nm for all motion modes (flexion/extension, lateral bending, and axial rotation) in intact spine. The ROM was tracked using a video-based motion-capturing system. After the Charité ™ disc was implanted at the L4-L5 level, the measurement was repeated using two different methods : 1) loading up to 8 Nm with the compressive follower preload as in testing the intact spine (Load control protocol), 2) loading in displacement control until the total ROM of L2-S2 matches that when the intact spine was loaded under load control (Hybrid protocol). The comparison between the data of each protocol was performed. Results: The ROMs of the L4-L5 arthroplasty level were increased in all test modalities (p < 0.05 in bending and rotation) under both load and hybrid protocols. At the adjacent segments, the ROMs were increased in all modes except flexion under load control protocol. Under hybrid protocol, the adjacent segments demonstrated decreased ROMs in all modalities except extension at the inferior segment. Statistical significance between load and hybrid protocols was observed during bending and rotation at the operative and adjacent levels (p < 0.05). Conclusion: In hybrid protocol, the Charité ™ disc provided a relatively better restoration of ROM, than in the load control protocol, reproducing clinical observations in terms of motion following surgery.

Relevance of using a compressive preload in the cervical spine: an experimental and numerical simulating investigation

“…The mean coupled lateral bending during axial rotation reduced from 33.5°± 6°(26-43) to 24.6°± 5.9° (15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34), which represented 75.5 ± 15.9 % (51-105) and 65.7 ± 14.3 % (37-85) of the main motion, respectively, p \ 0.005, Fig. 6b.…”

“…On the contrary, when there is a risk of separation between implant and bone surfaces or between implant parts, as observed for disc prostheses or cages alone [16,33,34], segmental compressive force should be useful, thus limiting the separation of bearing surfaces or separation between implant and endplates, and the use of a follower load is therefore recommended. Nevertheless, we suggest applying follower load only in flexion-extension seeing the results mentioned in the present study.…”

The Current Testing Protocols for Biomechanical Evaluation of Lumbar Spinal Implants in Laboratory Setting: A Review of the Literature

“…Most multisegmental studies involved one [ 32 , 33 , 35 , 36 , 38 , 40 , 42 , 44 – 49 , 51 – 56 , 59 , 65 , 66 , 68 – 70 , 72 , 74 , 75 ] (60.9%) or two [ 34 , 37 , 39 , 41 , 43 , 50 , 60 , 62 , 64 , 67 , 71 , 76 ] (26.1%) operative level(s) in their testing sample. Moreover, the L3-L4 and the L4-L5 were the most frequent operative levels used in multisegmental investigations (58.7%) that included one or more spinal segment as their operative level(s).…”

“…Preload and torque combinations are summarized in Table 3 . A follower compressive preload of 400 N during FE motion was used in thirteen (13) [ 44 – 50 , 56 , 61 , 65 , 69 , 70 , 76 ] of the nineteen (19) multisegmental publications reporting the use of some preload in at least one of their flexion-extension (FE) tests. There were four (4) publications [ 52 , 53 , 59 , 60 ] that mentioned the performance of an additional test where a 400 N follower compressive load was applied through a notched belt looped oriented midsagitally over the specimen using a compression-flexion apparatus, which were not included in Table 2 under the preload classification.…”

Cervical disc prosthesis versus arthrodesis using one-level, hybrid and two-level constructs: an in vitro investigation

“…As recommended by Panjabi et al [28][29][30], to analyse and understand changes in kinematics and IDP at adjacent levels, we used the concept of displacement-control protocol to compare intact and instrumented spines (i.e. equivalent to hybrid testing protocol).…”