Study Design.: A porcine cadaveric biomechanical study. Objective.: To biomechanically evaluate a novel Cable Anchor System as semi-rigid junctional fixation technique for the prevention of proximal junctional failure after adult spinal deformity surgery and to make a comparison to alternative promising prophylactic techniques. Summary of Background Data.: The abrupt change of stiffness at the proximal end of a pedicle screw construct is a major risk factor for the development of proximal junctional failure after adult spinal deformity surgery. A number of techniques that aim to provide a gradual transition zone in range of motion (ROM) at the proximal junction have previously been studied. In this study, the design of a novel Cable Anchor System, which comprises a polyethylene cable for rod fixation, is assessed. Methods.: Ten T6–T13 porcine spine segments were subjected to cyclic 4 Nm pure-moment loading. The following conditions were tested: uninstrumented, 3 level pedicle screw fixation (PSF), and PSF with supplementary Cable Anchors applied proximally at 1-level (Anchor1) or 2-levels (Anchor2), transverse process hooks (TPH), and 2-level sublaminar tapes (Tape2). The normalized segmental range of motion in the junctional zone was compared using one-way analysis of variance and linear regression. Results.: Statistical comparison at the level proximal to PSF showed significantly lower ROMs for all techniques compared to PSF fixation alone in all movement directions. Linear regression demonstrated a higher linearity for Anchor1 (0.820) and Anchor2 (0.923) in the junctional zone in comparison to PSF (1-level: 0.529 and 2-level: 0.421). This linearity was similar to the compared techniques (TPH and Tape2). Conclusion.: The Cable Anchor System presented in this study demonstrated a gradual ROM transition zone at the proximal end of a rigid pedicle screw construct similar to TPH and 2-level sublaminar tape semi-rigid junctional fixation constructs, while providing the benefit of preserving the posterior ligament complex. Level of Evidence: 5

Carbon fiber-reinforced polyetheretherketone (CFR-PEEK) as an alternative to metallics in orthopedic implants offers biomechanical and radiological advantages. However, the extent of wear particle generation and its clinical impact are unclear. This systematic review evaluates clinical evidence of wear in fracture fixation devices. A systematic search was conducted to identify clinical studies reporting wear of metallic and CFR-PEEK implants used in extremities. Nineteen studies were included: three prospective cohorts, eight retrospective cohorts, one case series, and six case reports. Among 208 fixation plates, 43 were CFR-PEEK and all 93 intramedullary nails were metallic. Risk of bias ranged from low to serious, mainly due to selection bias. Wear-related complications were reported for both materials. Metallic implants showed elevated serum ion levels, metallic debris in tissues, and, in some cases, metallosis. CFR-PEEK implants showed limited evidence of carbon fiber fragments near implants. One comparative study reported higher inflammatory responses in CFR-PEEK explants, though no direct link between debris and implant removal was found. Both metallic and CFR-PEEK fracture fixation devices generate wear particles, which may induce biological responses. However, wear-related complications appear rare, especially with validated implant designs, and clinical significance of wear debris remains limited.

Degeneration of the intervertebral discs (IVDs) causes significant biomechanical changes and structural defects, often leading to pain or disability. These defects impair both the biomechanics and physiology of the IVD, contributing to further structural failure of the IVD. Although the function and structure of the annulus fibrosus (AF) affect overall disc function, its structural change during degeneration is not fully characterized. The objective of this study was to investigate AF microdamage and mechanical function in mildly degenerated discs. Basic laboratory study using human cadaveric intervertebral discs. Microdamage and its functional implications in the AF of human IVDs with mild degeneration were assessed through a comprehensive approach focusing on biomechanical, and structural analyses. Eighteen fresh-frozen human cadaveric discs (T10-L5, n=3 spines, 43-58 years old) were analyzed from anterior, posterior, and lateral regions of the inner and outer AF. Collagen microdamage was assessed using Collagen Hybridizing Peptide (CHP), and Second Harmonic Generation (SHG) imaging to provide high-resolution insights into collagen fiber structure. Mechanical testing was performed on the same regions. Damage analyses showed no significant differences between the degenerative grades except in the posterior outer AF, where Grade 3 discs showed higher CHP and SHG signal intensity compared to Grade 2. Plus, mechanical properties did not differ significantly between the grades, although large variances were observed, particularly in the posterior outer AF. Despite limited mechanical differences, early structural damage was found in the posterior outer AF. This indicates that this part is the initial site of AF damage and biological response during IVD degeneration. These findings highlight the posterior outer AF as a potential target for early diagnostic and therapeutic interventions to mitigate further degeneration and preserve disc function.

OBJECTIVE: Complications after adult spinal deformity surgery are common, with implant-related complications occurring in up to 27.8% of cases. Sublaminar wire fixation strength is less affected by decreasing trabecular bone density in comparison to pedicle screw (PS) fixation due to the predominant cortical bone composition of the lamina. Sublaminar fixation may thus aid in decreasing implant-related complications. The goal of this study was to compare fixation characteristics of titanium sublaminar cables (SCs), ultra–high-molecular-weight polyethylene (UHMWPE) tape, PSs, and PSs augmented with UHMWPE tape in an ex vivo flexion–bending setup.METHODS: Thirty-six human cadaver vertebrae were stratified into 4 different fixation groups: UHMWPE sublaminar tape (ST), PS, metal SC, and PS augmented with ST (PS + ST). Individual vertebrae were embedded in resin, and a flexion–bending moment was applied that closely resembles the in vivo loading pattern at transitional levels of spinal instrumentation.RESULTS: The failure strength of PS + ST (4522 ± 2314 N) was significantly higher compared to the SC (2931 ± 751 N) and PS (2678 ± 827 N) groups, which had p values of 0.028 and 0.015, respectively (all values expressed as the mean ± SD). Construct stiffness was significantly higher for the PS groups compared to the stand-alone sublaminar wiring groups (p = 0.020). In contrast to SC, ST did not show any case of cortical breach.CONCLUSIONS: The higher failure strength of PS + ST compared to PS indicates that PS augmentation with ST may be an effective measure to reduce the incidence of screw pullout, even in osteoporotic vertebrae. Moreover, the lower stiffness of sublaminar fixation techniques and the absence of damage to the cortices in the ST group suggest that ST as a stand-alone fixation technique in adult spinal deformity surgery may also be clinically feasible and offer clinical benefits.