P2 porous titanium implants improve tendon healing in an acute rat supraspinatus repair model

Strategies for promoting tendon-bone healing: Current status and prospects

Tendon-bone insertion (TBI) injuries are common, primarily involving the rotator cuff (RC) and anterior cruciate ligament (ACL). At present, repair surgery and reconstructive surgery are the main treatments, and the main factor determining the curative effect of surgery is postoperative tendon-bone healing, which requires the stable combination of the transplanted tendon and the bone tunnel to ensure the stability of the joint. Fibrocartilage and bone formation are the main physiological processes in the bone marrow tract. Therefore, therapeutic measures conducive to these processes are likely to be applied clinically to promote tendon-bone healing. In recent years, biomaterials and compounds, stem cells, cell factors, platelet-rich plasma, exosomes, physical therapy, and other technologies have been widely used in the study of promoting tendon-bone healing. This review provides a comprehensive summary of strategies used to promote tendon-bone healing and analyses relevant preclinical and clinical studies. The potential application value of these strategies in promoting tendon-bone healing was also discussed.

Effect of Pore Size of Porous-Structured Titanium Implants on Tendon Ingrowth

Purpose

The reconstruction of a tendon insertion on metal prostheses is a challenge in orthopedics. Of the available metal prostheses, porous metal prostheses have been shown to have better biocompatibility for tissue integration. Therefore, this study is aimed at identifying an appropriate porous structure for the reconstruction of a tendon insertion on metal prostheses.

Methods

Ti6Al4V specimens with a diamond-like porous structure with triply periodic minimal surface pore sizes of 300, 500, and 700 μm and a porosity of 58% (designated Ti300, Ti500, and Ti700, respectively) were manufactured by selective laser melting and were characterized with micro-CT and scanning electron microscopy for their porosity, pore size, and surface topography. The porous specimens were implanted into the patellar tendon of rabbits. Tendon integration was evaluated after implantation into the tendon at 4, 8, and 12 weeks by histology, and the fixation strength was evaluated with a pull-out test at week 12.

Results

The average pore sizes of the Ti300, Ti500, and Ti700 implants were 261, 480, and 668 μm, respectively. The Ti500 and Ti700 implants demonstrated better tissue growth than the Ti300 implant at weeks 4, 8, and 12. At week 12, the histological score of the Ti500 implant was 13.67 ± 0.58, and it had an area percentage of type I collagen of 63.90% ± 3.41%; both of these results were significantly higher than those for the Ti300 and Ti700 implants. The pull-out load at week 12 was also the highest in the Ti500 group.

Conclusion

Ti6Al4V implants with a diamond-like porous structure with triply periodic minimal surface pore size of 500 μm are suitable for tendon integration.

Flexor Pollicis Longus Tendon Wear Associated With Volar Plating: A Cadaveric Study

PURPOSE

This study examined the effect of low-profile volar rim plates (VR), proximally placed standard variable-angle locking plates (pVA-LCP), and distally placed standard variable-angle locking plates (dVA-LCP) on the flexor pollicis longus (FPL) tendon in a cadaver model. We hypothesized that tendons from the VR and pVA-LCP groups would exhibit similar contact pressures, wear patterns, and post-fatigue testing mechanical properties, whereas dVA-LCP tendons would exhibit higher contact pressures, increased tendon wear patterns, and decreased mechanical properties.

METHODS

Nine matched pairs of cadaveric specimens were used in this study. Thin-film pressure sensors were used to measure the initial contact loads between plates and FPL tendons. Specimens were cyclically loaded for 10,000 cycles by actuating the FPL tendon. Cycled tendons were harvested, photographed with a stereomicroscope, and graded for wear on a Likert scale by 5 observers who were blinded to the study protocol. Uniaxial tensile testing measured mechanical properties of the tendon: ultimate failure load, ultimate stress, percent stress relaxation, elastic modulus, and stiffness.

RESULTS

With regard to the cadaveric FPL tendon, VR and dVA-LCP had increased contact pressure and tendon wear compared with pVA-LCP. There were no significant differences in contact pressure or tendon wear between dVA-LCP and VR. There was no major difference in the tested mechanical properties of the FPL tendon among any of the groups.

CONCLUSIONS

Plates placed directly on or beyond the volar rim demonstrate increased contact pressures and increased tendon wear in a cadaveric model.

CLINICAL RELEVANCE

Although low-profile plates allow for fixation of smaller volar fragments in the distal radius, they cause substantial contact with the FPL tendon, which may rupture if the plate is not removed.

Reconstructive Science in Orthopedic Oncology

Limb salvage is widely practiced as standard of care in most cases of extremity bone sarcoma. Allograft and endoprosthesis reconstructions are the most widely utilized modalities for the reconstruction of large segment defects, however complication rates remain high. Aseptic loosening and infection remain the most common modes of failure. Implant integration, soft-tissue function, and infection prevention are crucial for implant longevity and function. Macro and micro alterations in implant design are reviewed in this manuscript. Tissue engineering principles using nanoparticles, cell-based, and biological augments have been utilized to develop implant coatings that improve osseointegration and decrease infection. Similar techniques have been used to improve the interaction between soft tissues and implants. Tissue engineered constructs (TEC) used in combination with, or in place of, traditional reconstructive techniques may represent the next major advancement in orthopaedic oncology reconstructive science, although preclinical results have yet to achieve durable translation to the bedside.