Posterior Component Impingement After Lumbar Total Disc Replacement

Abstract

Posterior component impingement was seen in a considerable number of implants. With regard to potential consequences like PE-wear, further studies are needed to investigate the correlation between radiographic and clinical findings.

Load‐transfer in the human vertebral body following lumbar total disc arthroplasty: Effects of implant size and stiffness in axial compression and forward flexion

“…The medium implant in our study is of particular interest because it is most representative of devices used clinically: the dimensions of the implant and dimensional mismatch between the implant and the underlying vertebra are both within the range found clinically. 49 Our results suggest that implants of this size recruit less overall cortical bone than the intact disc in compression, thereby overloading the tra- has been reported to occur in 9% to 66% of cases 34,51,52 and has been documented for nearly all major device designs (Charité, [52][53][54] ProDisc-L, 34,51,55 activL, 36,41 MobidiscL 41 ). When impingement occurs, large loads can be transmitted through the impinged region.…”

“…When impingement occurs, large loads can be transmitted through the impinged region . Both anterior and posterior impingement are possible for flexion and extension, respectively . Our data show that for anterior impingement induced by flexion, the anterior portions of the cortex and underlying trabecular bone must accommodate nearly all of the load for medium and large implants.…”

“…For a given implant size, the stress distribution was impacted much more by the boundary condition (compression vs flexion‐induced anterior impingement) than by the implant's material properties. Impingement, defined as contact between secondary, nonbearing surfaces (eg, between the rim of the articulating insert and the metallic footplate, or between two metallic footplates) has been reported to occur in 9% to 66% of cases and has been documented for nearly all major device designs (Charité, ProDisc‐L, activL, MobidiscL). When impingement occurs, large loads can be transmitted through the impinged region .…”

“…There is substantial evidence that impingement occurs in vivo in flexion/extension and lateral bending for both unconstrained (eg, Charité) and semi-constrained (eg, ProDisc-L, activL) devices. [34][35][36][37][38][39][40][41] Analysis of retrieved implants and in vitro experiments suggests that large loads are transmitted through the impinged regions during bending. 35,37,40 Therefore, flexion of an implanted segment was modeled by applying a net force of 800 N to a 2 mm thick, 90 arc of the footplate, representing load-transfer through the footplate induced by impingement ( Figure 2).…”

The Latest Lessons Learned from Retrieval Analyses of Ultra-High Molecular Weight Polyethylene, Metal-on-Metal, and Alternative Bearing Total Disc Replacements

“…In a companion HSS study 23 of 29 cervical ProDisc retrievals, also implanted for an average of one year, researchers observed impingement in 96% (28/29) of explanted devices. These short-term retrieval findings, coupled with radiographic evidence of impingement in a clinical study 25 of the lumbar ProDisc, further highlight the relevance of impingement to contemporary TDR designs in addition to the historical CHARITÉ. In our retrieval collection, we have had the opportunity to characterize 10 TDRs from conventional gamma inert-sterilized polyethylene.…”