RMS Foundation

Background/Objectives: Managing acetabular fractures remains a surgical challenge, particularly in cases involving traumatic pelvic discontinuity (PD). The optimal method for achieving primary stability is unclear, and biomechanical evidence comparing established techniques is limited. The goal of this biomechanical study is to evaluate if a Ganz reinforcement ring with the addition of a posterior-column plate and anterior-column screw (GRP) provides stability comparable to a Burch-Schneider reinforcement ring (BSR) with an additional anterior- and posterior-column screws construct. Methods: The primary biomechanical stability of two acetabular "fix-and-replace" techniques-BSR versus GRP-using standardized 4th-generation Sawbones® hemipelvis models with T-type fractures (PD) was compared. Relative 3D micromotions at the fracture site (Zone 1: Posterior-column; Zone 2: Anterior-column; Zone 3: Oblique to transverse fracture, and Zone 4: Ischiopubic ramus) were measured under increasing cyclic loading (100 cycles per load level) at 200 N, 400 N, 800 N, and 1200 N using an optical motion tracking system. A detected fracture gap of 1000 µm or more during/after the cyclic load was defined as fixation failure. Results: Fixation failure was not observed in any of the six artificial hemipelves with treated (3 BSR, 3 GRP) T-type acetabular fractures. Under cyclic, increasing load (200-1200 N), the mean fracture gap remained small at 200 N and 400 N with no significant differences between techniques. At 800 N, GRP fixation showed a non-significant increase in micromotion. At 1200 N, significantly greater displacements were observed in Zones 2-4 with GRP compared to BSR (p < 0.005), whereas no difference was found in Zone 1 (p = 0.424). Modelled slope and intercept comparisons confirmed a significantly steeper increase in fracture gap with GRP in zones 2-4 at higher loads (≥800 N, p < 0.01) while remaining under 1000 µm. Conclusions: Both fixation methods demonstrated sufficient construct stability without catastrophic failure, with minimal displacement (<1 mm) and with no significant difference in stability at the posterior column.

The first workshop on the "latest advances in biomedical applications of octacalcium phosphate (OCP)" was organized as a satellite symposium to the Bioceramics33 conference in Solothurn, Switzerland, in October 2023. The event brought together leading researchers and industry representatives to present and discuss their latest groundbreaking research aimed at developing and commercializing advanced OCP-based biomaterials for bone regeneration. The topics presented by the six invited speakers ranged from a fundamental understanding of the OCP crystal chemistry to advanced processing and characterization methods, functionalization, biomineralization, and commercialization. With this summary report, we are laying the foundation for a continuation of a series of workshops on the subject of OCP biomaterials in order to promote the exchange between researchers and industry representatives and to drive forward the development and commercialization of new improved synthetic bone substitute materials.

Bisphosphonates (BP) are anti-resorptive drugs that are widely used to prevent bone loss in osteoporosis. Since inhibition of bone resorption will cause a decrease in bone formation through a process called coupling, it is hypothesized that extended treatment protocols may impair bone healing. In this study, β-tri‑calcium-phosphate (βTCP) ceramics were inserted into critical-size long bone defects in estrogen-deficient mice under BP therapy. The study assessed the benefits of coating the ceramics with Bone Morphogenetic Protein-2 (BMP2) and an engineered BMP2 analogue (L51P) that inactivates BMP antagonists on the healing process, implant resorption, and bone formation.Female NMRI mice (11–12 weeks of age) were ovariectomized (OVX) or sham operated. Eight weeks later, after the manifestation of ovariectomy-induced osteoporotic bone changes, BP therapy with Alendronate (ALN) was commenced. After another five weeks, a femoral critical-size defect was generated, rigidly fixed, and βTCP-cylinders loaded with 0.25 μg or 2.5 μg BMP2, 2.5 μg L51P, and 0.25 μg BMP2/2.5 μg L51P, respectively, were inserted. Unloaded βTCP-cylinders were used as controls. Femora were collected six and twelve weeks post-implantation.Histological and micro-computer tomography (MicroCT) evaluation revealed that insertion of cylinders coated with 2.5 μg BMP2 accelerated fracture repair and induced significant bone formation compared to controls (unloaded cylinders or coated with 2.5 μg L51P, 0.25 μg BMP2) already six weeks post-implantation, independent of estrogen-deficiency and BP therapy. The simultaneous administration of BMP2 and L51P (0.25 μg BMP2/2.5 μg L51P) did not promote fracture healing six and twelve weeks post-implantation. Moreover, new bone formation within the critical-size defect was directly linked to the removal of the βTCP-implant in all experimental groups. No evidence was found that long-term therapy with ALN impaired the resorption of the implanted graft. However, osteoclast transcriptome signature was elevated in sham and OVX animals upon treatment with BP, with transcript levels being higher at six weeks than at twelve weeks post-surgery. Furthermore, the transcriptome profile of the developing repair tissue confirmed an accelerated repair process in animals treated with 2.5 μg BMP2 implants. L51P did not increase the bioefficacy of BMP2 in the applied defect model.The present study provides evidence that continuous administration of BP does not inhibit implant resorption and does not alter the kinetics of the healing process of critical-size long bone defects. Furthermore, the BMP2 variant L51P did not enhance the bioefficacy of BMP2 when applied simultaneously to the femoral critical-size defect in sham and OVX mice.

Since the middle of the 20th century, total hip arthroplasty has become a very successful treatment for all end-stage diseases of the hip joint. Charnley solved with his low frictional torque arthroplasty the problem of wear and friction with the introduction of a new bearing couple and the reduction of the head size, which set the prerequisite for the further development of stem design.This narrative review presents the major developments of regular straight stems in hip arthroplasty. It does not only provide an overview of the history but also assembles the generally scarce documentation available regarding the rationale of developments and illustrates often-unsuspected links.Charnley's success is based on successfully solving the issue of fixation of the prosthetic components to the bone, using bone cement made of polymethyl-methacrylate. In the field of cemented anchorage of the stem, two principles showing good long-term revision rates emerged over the years: the force-closed and the shape-closed principles.The non-cemented anchorage bases on prosthesis models ensure enough primary stability for osteointegration of the implant to occur. For bone to grow onto the surface, not only sufficient primary stability is required but also a suitable surface structure together with a biocompatible prosthetic material is also necessary.