A novel, multi-level approach to assess allograft incorporation in revision total hip arthroplasty

Histomorphometric Assessment of Non-Decalcified Plastic-Embedded Specimens for Evaluation of Bone Regeneration Using Bone Substitute Materials-A Systematic Review

With the implementation of bone substitute materials, regeneration strategies have inevitably evolved over the years. Histomorphometry is the optimal means of quantitative evaluation of bone structure and morphology. This systematic review focuses on determining study models, staining methods and histomorphometric parameters used for bone regeneration research on non-decalcified plastic-embedded specimens over the last 10 years. After being subjected to the inclusion and exclusion criteria, 118 studies were included in this review. The results establish the most commonly selected animal model is rat, followed by rabbit, sheep and dog. Strong preference for staining samples with toluidine blue was noted. With regard to histomorphometric parameters, terms related to bone were most frequently assessed, amounting to almost half of recorded parameters. New bone formation was the main descriptor of this category. Residual bone graft and non-bone tissue parameters were also often evaluated. With regard to dynamic histomorphometry, mineral apposition rate (MAR) was the parameter of choice for most researchers, with calcein green being the preferred dye for fluorochrome labelling. An overview of the contemporary literature, as well as weaknesses in the current research protocols have been discussed.

Effectiveness of Virtual Surgical Planning and Three-Dimensional Anatomical Models in Radiological Reconstruction of Center of Rotation and Pelvic Brim in Patients with Anterior Column Defects Requiring Revision Hip Arthroplasty

Background: The aim of this study was to show that virtual surgical planning (VSP) and printed anatomical models support the reconstruction of the center of rotation (COR) and pelvic BRIM during revision hip surgery using a dual-mobility revision cup system in patients with anterior pelvic column damage and soft tissue envelope deficiency. Methods: Patients with anterior pelvic column damage and soft tissue envelope deficiency underwent revision hip arthroplasty. Virtual planning included assessment of bone segmentation, positioning of the cementless revision cup while maintaining the COR, and the assumed inclination and anteversion angles. Results: The diameter of the planned revision cups was 65.5 ± 2.1 mm, and the diameter of the revision cups used was 65.3 ± 2.1 mm. The difference in COR position in the horizontal axis was 7.8 ± 9.3 mm, in the vertical axis was 4.3 ± 5.9 mm, and in the axial plane was 1.6 ± 3.3 mm. The differences in inclination angle and in the anteversion angle were 12.4° and 8.7°, respectively. Conclusions: The use of VSP and 3D models supports the process of performing RHA surgery in patients with damage to the anterior pelvic column and soft tissue envelope deficiency.

Acetabular Reconstruction Using Multiple Porous Tantalum Augments: Three-Quarter Football Augment

Reconstruction of a large acetabular bone defect is a complex problem in revision hip arthroplasty. The authors report a novel method of reconstructing an uncontained acetabular defect (Paprosky type IIIb) using multiple tantalum augments. A 73-year-old female patient presented to our institution with a chronically dislocated primary left total hip arthroplasty with radiographs demonstrating migration of acetabular component and formation of pseudoarthrosis within the left ilium. Extensive arthrolysis and anatomic reconstruction of the acetabular bone defect were performed using the novel method of multiple tantalum augments. Postoperatively, recovery was initially complicated by multiple dislocations requiring an exchange to an elevated liner, however subsequently achieved good function.

Allograft Chip Incorporation in Acetabular Reconstruction: Multiscale Characterization Revealing Osteoconductive Capacity

BACKGROUND

Impacted bone-grafting with morselized allograft chips is commonly used to reconstruct acetabular bone defects in revision total hip arthroplasty (THA). While the overall clinical outcome of this procedure is described to be excellent, the microstructural basis and histological determinants of allograft incorporation remained to be further elucidated.

METHODS

The acetabula of 23 individuals with documented previous use of allograft chips during revision THA were explanted post mortem. The time that the allografts were in situ averaged 10.3 ± 4.5 years (range, 1.2 to 19.8 years). The host bone (HB)-allograft bone (AB) interface was characterized using a suite of high-resolution (HR) imaging techniques including HR-peripheral quantitative computed tomography (HR-pQCT), histological analysis, cellular histomorphometry, and scanning electron microscopy.

RESULTS

AB could be identified in 16 of the 23 cases. The HB and AB showed overlap (i.e., ingrowth) in 91.3% of the total interface. The mean ingrowth was 2.2 ± 1.0 mm with a maximum of 4.7 ± 2.1 mm. The periphery of the AB showed a tight interconnection with the HB associated with increased bone remodeling indices and increased trabecular thickness. While no association between the time in situ and the ingrowth was observed, the bone defect area was positively associated with the thickness of a fibrosis layer separating the ingrowth zone from the AB.

CONCLUSIONS

Allograft chips in revision THA form an adequate osseous foundation with successful incorporation through ingrowth of the HB (i.e., osteoconduction). While complete remodeling was not observed, larger defects were associated with fibrosis formation, which may compromise stability.

CLINICAL RELEVANCE

Our study provides the first systematic, multiscale long-term evaluation of chip allograft incorporation in revision THA to underscore its successful clinical use. As larger defects were associated with fibrous ingrowth, structural allografts may be superior for larger defects in terms of long-term outcomes.