Megaprosthesis Versus Allograft Prosthesis Composite for the Management of Massive Skeletal Defects: A Meta-Analysis of Comparative Studies

Femoral alloprosthesis in bone defect of 30 cm as extremity salvage

Defects in femoral bone segments represent a reconstructive challenge; they are caused secondary to multiple and extensive debridement in cases of patients with infections, tumors or high-energy trauma. Different treatments have been proposed to address this problem, however, these are limited when it comes to large defects that generate instability of the implants in the native bone as well as loss of functionality and length of the extremities. In the proximal femur, allograft prosthesis composites have been described in the management of extensive tumor resections, but they are not yet widely used in the management of bone defects due to osteomyelitis. The case of a 51-year-old male patient with post-traumatic pan-osteomyelitis of the femur Cierny-Mader IV with a 30-centimeter defect in whom limb salvage was achieved through the application of a femoral alloprosthesis is presented, exhibiting this surgical technique as an alternative in ample resections secondary to infectious processes in young patients, furthermore, offering a solution to the shortage of some prosthetic components in our surrounding.

Dual Mobility for Oncological Hip Reconstruction: Significantly Reduced Dislocation Rates at 5 years

BACKGROUND

Although dual mobility total hip arthroplasty has become increasingly common in recent years, limited remains known on dual mobility in surgical oncology. This university-based investigation compared dislocation and revision rates of DMs, conventional total hip arthroplasty (THA), and hemiarthroplasties (HAs) for oncological hip reconstruction.

METHODS

An institutional tumor registry was used to identify 221 patients undergoing 45 DMs, 67 conventional THAs, and 109 HAs, performed for 17 primary hip tumors and 204 hip metastases between 2010 and 2020. The median age at surgery was 65 years, and 52% were female. The mean follow-up was 2.5 years. Kaplan-Meier survivorship curves and log-rank tests were done to compare dislocation and revision rates among all 221 patients, after a one-to-one propensity match, based on age, sex, tumor type (metastasis, primary tumor), and tumor localization (femur, acetabulum).

RESULTS

The 5-year survivorship free of dislocation was 98% in DMs, 66% in conventional THAs ( P = 0.03; all P values compared with DMs), and 97% among HAs ( P = 0.48). The 5-year survivorship free of revision was 69% in DMs, 62% in conventional THAs ( P = 0.68), and 92% in HAs ( P = 0.06). After propensity matching, the 5-year survivorship free of dislocation was 42% in 45 conventional THAs ( P = 0.027; compared with all 45 DMs) and 89% in 16 matched HAs ( P = 0.19; compared with 16 DMs with femoral involvement only). The 5-year survivorship free of revision was 40% in matched conventional THAs ( P = 0.91) and 100% in matched HAs ( P = 0.19).

CONCLUSIONS

DMs showed markedly lower rates of dislocation than conventional THAs, with overall revision rates remaining comparable among different designs. DMs should be considered the option of choice for oncological hip reconstruction if compared with conventional THAs. HAs are a feasible alternative when encountering femoral disease involvement only.

LEVEL OF EVIDENCE

III.

Biological Prosthesis (Hollow 3D-Printed Titanium Custom-Made Prosthesis and Bone Graft) for Humeral Reconstruction in Pediatric Oncologic Patients: Surgical Indications and Results

This study presents the mid-term outcomes of a novel "biological prosthesis" for pediatric humerus reconstruction after major bone tumor removal. This approach involves a hollow 3D-printed titanium custom-made prosthesis combined with bone grafting. The primary aim was to preserve and revitalize the unaffected autologous proximal or distal humeral stump. Between 2017 and 2021, we treated five pediatric patients (mean age 11.2 years; range 7-17) with humeral bone sarcomas. A one-stage surgical procedure involved tumor resection and implanting a hollow 3D-printed custom-made prosthesis. In two cases, we preserved the proximal humerus; in two, the distal part; and in one, both. Graft materials included homologous bone chips in three cases and free vascularized fibular grafts in two cases. All patients were clinically and radiographically assessed after a mean follow-up of 32.2 months (range of 14-68). No significant complications were observed, and no implant revisions were needed. Osseointegration was evident in all cases within eight months post-surgery; vascular support for the remaining autologous stump was demonstrated in all cases. Our hollow 3D-printed custom-made prosthesis and bone grafting offer the potential for partial or complete articular surface preservation. This approach encourages revascularization of the epiphysis, leading to satisfactory outcomes in humerus reconstruction within the pediatric population.

Silver-Coated Distal Femur Megaprosthesis in Chronic Infections with Severe Bone Loss: A Multicentre Case Series

Periprosthetic joint infections (PJI) and fracture-related infections (FRI) of the distal femur (DF) may result in massive bone defects. Treatment options include articulated silver-coated (SC) megaprosthesis (MP) in the context of a two-stage protocol. However, there is limited evidence in the literature on this topic. A retrospective review of the prospectively maintained databases of three Institutions was performed. Forty-five patients were included. The mean follow-up time was 43 ± 17.1 months. Eight (17.8%) patients had a recurrent infection. The estimated recurrence-free survival rate was 91.1% (93.5% PJI vs. 85.7% FRI) 2 years following MP implantation, and 75.7% (83.2% PJI vs. 64.3% FRI; p = 0.253) after 5 years. No statistically relevant difference was found according to the initial diagnosis (PJI vs. FRI). Among possible risk factors, only resection length was found to significantly worsen the outcomes in terms of infection control (p = 0.031). A total of eight complications not related to infection were found after reimplantation, but only five of them required further surgery. Above-the-knee amputation was performed in two cases (4.4%), both for reinfection. Articulated DF SC MP in a two-stage protocol is a safe and effective treatment for chronic knee infection with severe bone loss.

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.

Bone Bricks: The Effect of Architecture and Material Composition on the Mechanical and Biological Performance of Bone Scaffolds

Large bone loss injuries require high-performance scaffolds with an architecture and material composition resembling native bone. However, most bone scaffold studies focus on three-dimensional (3D) structures with simple rectangular or circular geometries and uniform pores, not able to recapitulate the geometric characteristics of the native tissue. This paper addresses this limitation by proposing novel anatomically designed scaffolds (bone bricks) with nonuniform pore dimensions (pore size gradients) designed based on new lay-dawn pattern strategies. The gradient design allows one to tailor the properties of the bricks and together with the incorporation of ceramic materials allows one to obtain structures with high mechanical properties (higher than reported in the literature for the same material composition) and improved biological characteristics.