A New Diagnostic Approach for Periprosthetic Acetabular Fractures Based on 3D Modeling: A Study Protocol

Quantitative Assessment of Acetabular Defects in Revision Hip Arthroplasty Based on 3D Modeling: The Area Increase Ratio (AIR) Method

The most common classifications for acetabular bone defects are based on radiographic two-dimensional imaging, with low reliability and reproducibility. With the rise of modern processing techniques based on 3D modelling, methodologies for the volumetric quantification of acetabular bone loss are available. Our study aims to describe a new methodology for the quantitative assessment of acetabular defects based on 3D modelling, focused on surface analysis of the integrity of the main anatomical structures of the acetabulum represented by four corresponding sectors (posterior, superior, anterior, and medial). The defect entity is measured as the area increase ratio (AIR) detected in all the sectors analyzed on three planes of view (frontal, sagittal, and axial) compared to healthy hemipelvises. The analysis was performed on 3D models from the CT-scan of six exemplary specimens with a unilateral pathological hemipelvis. The AIR between the native and the pathological hemipelvis was calculated for each sector, for a total of 48 analyses (range, +0.93-+171.35%). An AIR of >50% were found in 22/48 (45.8%) sectors and affected mostly the posterior, medial, and superior sectors (20/22, 90.9%). Qualitative analysis showed consistency between the data and the morphological features of the defects. Further studies with larger samples are needed to validate the methodology and potentially develop a new classification scheme.

Proximal femoral defect classifications in revision total hip arthroplasty from X-rays imaging to advanced 3D imaging: a narrative review

Background and Objective

Femoral bone defect in hip arthroplasty revision surgery represents a complex problem, and the treatment is a challenge for orthopedic surgeons called to assess the residual bone stock in an altered anatomy and obtain stability for the new implant. Classification systems available are mostly based on X-rays two-dimensional images and lack of accuracy and reproducibility and comprehensive therapeutic algorithms. However, there is no record of any classification based on computed tomography (CT)-scan images or three-dimensional (3D) modeling modern techniques. We aimed to review the current literature around femoral defect classifications (FDCs) analyzing their different rationale basis, reliability and accuracy, and their benefit in clinical practice. Moreover, we highlighted the role of CT scan-based 3D modeling techniques in the setting of femoral bone defects and revision hip arthroplasty.

Methods

A narrative review was conducted. The articles were selected from the PubMed and Scopus medical database updated to March 2023. All Level-I to IV studies in the English language were considered for inclusion. The research was performed using relevant search term items: "femoral defects", "classification", "radiographic", "revision hip arthroplasty", "CT scan" and "3D" and we included only articles that evaluated the accuracy or reliability (or both) of the different femoral bone defects classification system.

Key Content and Findings

Our search yielded 408 results, of which 17 were deemed highly relevant. We found seven X-ray-based classification systems which have been attempted to quantify the degree of bone loss with low to good reproducibility. The most used classification system for femoral bone defects were the AAOS and Paprosky classification, which also offers a clinical therapeutic algorithm. In 2021, the FDC interestingly showed a new simple classification system with sub-optimal reproducibility and a practical therapeutic algorithm. Despite the numerous classification system of femoral defects, none of them comprehends the use of CT scan and 3D imaging technologies.

Conclusions

Traditional X-rays-based classification system are still widely used event if their intra-observer and inter-observer reliability is sub-optimal. 3D modeling techniques represent an important diagnostic tool that could improve the understanding of bone defects and residual bone supportive structures, allowing to elaborate new, more precise, classification systems.

The value of digital 3D models in evaluating surgical outcomes using the uninjured contralateral acetabulum after acetabular fracture repair

BACKGROUND

Currently, assessment of acetabular fracture reduction is mainly performed by evaluating 2D slices of 3D CT scans. This subjective method can potentially be improved by using 3D models and objective analysis tools. In order to evaluate the potential value of digital 3D reconstructed models in the assessment of acetabular fracture reduction, 3D reconstructions of the fractured acetabulum were compared to the mirrored healthy contralateral side for both the pre-, and post-surgical setting.

METHODS

Thirteen patients with one-sided acetabular fractures were included in the study. All patients received a pre-, and postoperative CT scan. The similarity between the healthy acetabulum and the contralateral fractured acetabulum was determined by two observers for both the pre-, and postoperative setting by completing the following four steps; (1) mirroring of the fractured acetabulum, (2) initial manual alignment of this mirrored 3D model to the contralateral version, (3) surface-based matching (iterative closest point registration) using the acetabular cartilage surface, and (4) calculating the surface distances between affected and healthy acetabular 3D models. Descriptive statistics showed the surface distance between pre-, and post-surgical reduction, as well as the interobserver variability.

RESULTS

A total of 13 patients with an acetabular fracture were included; 11 males and 2 females with a mean ± SD age of 55.6 ± 14.7 years. Digital mirroring of the fractured acetabula to the healthy acetabula was successful for both preoperative and postoperative situations in all patients. The median distance between both fractured and mirrored healthy contralateral acetabula was significantly larger (p<0.01) for the preoperative group (2.21 mm (interquartile range (IQR): 1.30 mm)) compared to the postoperative group (0.93 mm (IQR: 0.59 mm)). The median distance deviation was not significantly different (p = 0.96) between observers.

CONCLUSIONS

The results of comparing 3D model of fractured acetabula with the contra-lateral healthy acetabula before, and after surgical repair indicate that this method can be a suitable tool to objectively assess acetabular fracture reduction. Further research is needed to confirm the usefulness to predict future arthrosis after surgical repair.

Evaluation of the clinical efficacy of 3D Printing technology assisted surgery combined with early postoperative comprehensive rehabilitation in the treatment of Senile Intertrochanteric Fractures

Objectives

To observe the clinical value of 3D printing technology assisted surgery combined with early postoperative comprehensive rehabilitation in elderly patients with intertrochanteric fractures.

Methods

Sixty elderly patients with intertrochanteric fractures of the femur who were treated in our hospital from January 2018 to January 2020 were selected and randomly divided into two groups. In the experimental group, 3D printing technology assisted surgery combined with early postoperative comprehensive rehabilitation was used for treatment. While in the control group, traditional open reduction and dynamic hip screw internal fixation combined with postoperative conventional treatment was utilized. The duration of surgery, intraoperative blood loss, postoperative hospital stay, weight bearing time, fracture healing time and other surgical indicators were recorded respectively, and hip joint function recovery was evaluated prior to and 2 weeks after surgery. All patients were followed up for six months to observe the occurrence of complications within half a year, including deep vein thrombosis, incision infection, avascular necrosis of femoral head, hip joint stiffness, delayed fracture healing, etc. Subsequently, the differences in postoperative complications between the two groups were compared and analyzed.

Results

The operation time, blood loss, postoperative hospital stay, weight bearing time and fracture healing time of the experimental group were better than those of the control group, and the difference was statistically significant (p<0.05). After treatment, the hip joint function of the experimental group was significantly improved compared with the control group, with a statistically significant difference(p=0.03). The incidence of operative complications in the experimental group was 10% (3/30) within six months postoperatively, significantly lower than the 33% (10/30) in the control group, with statistical significance (p=0.03).

Conclusion

3D printing with early rehab proved to be effective treatment in our study. Such a combined treatment has the advantages of precise operative reduction, fast postoperative recovery, and certain safety and effectiveness.

The biology and treatment of acute long-bones diaphyseal fractures: Overview of the current options for bone healing enhancement

Diaphyseal fractures represent a complex biological entity that could often end into impaired bone-healing, with delayed union and non-union occurring up to 10% of cases. The role of the modern orthopaedic surgeon is to optimize the fracture healing environment, recognize and eliminate possible interfering factors, and choose the best suited surgical fixation technique. The impaired reparative process after surgical intervention can be modulated with different surgical techniques, such as dynamization or exchange nailing after failed intramedullary nailing. Moreover, the mechanical stability of a nail can be improved through augmentation plating, bone grafting or external fixation techniques with satisfactory results. According to the "diamond concept", local therapies, such as osteoconductive scaffolds, bone growth factors, and osteogenic cells can be successfully applied in "polytherapy" for the enhancement of delayed union and non-union of long bones diaphyseal fractures. Moreover, systemic anti-osteoporosis anabolic drugs, such as teriparatide, have been proposed as off-label treatment for bone healing enhancement both in fresh complex shaft fractures and impaired unions, especially for fragility fractures. The article aims to review the biological and mechanical principles of failed reparative osteogenesis of diaphyseal fractures after surgical treatment. Moreover, the evidence about the modern non-surgical and pharmacological options for bone healing enhancement will discussed.

Accuracy Assessment of Molded, Patient-Specific Polymethylmethacrylate Craniofacial Implants Compared to Their 3D Printed Originals

The use of patient-specific implants (PSIs) in craniofacial surgery is often limited due to a lack of expertise and/or production costs. Therefore, a simple and cost-efficient template-based fabrication workflow has been developed to overcome these disadvantages. The aim of this study is to assess the accuracy of PSIs made from their original templates. For a representative cranial defect (CRD) and a temporo-orbital defect (TOD), ten PSIs were made from polymethylmethacrylate (PMMA) using computer-aided design (CAD) and three-dimensional (3D) printing technology. These customized implants were measured and compared with their original 3D printed templates. The implants for the CRD revealed a root mean square (RMS) value ranging from 1.128 to 0.469 mm with a median RMS (Q1 to Q3) of 0.574 (0.528 to 0.701) mm. Those for the TOD revealed an RMS value ranging from 1.079 to 0.630 mm with a median RMS (Q1 to Q3) of 0.843 (0.635 to 0.943) mm. This study demonstrates that a highly precise duplication of PSIs can be achieved using this template-molding workflow. Thus, virtually planned implants can be accurately transferred into haptic PSIs. This workflow appears to offer a sophisticated solution for craniofacial reconstruction and continues to prove itself in daily clinical practice.

Strategies of management of traumatic periprosthetic acetabular fractures around a pre-existing total hip arthroplasty

INTRODUCTION

and aim: Traumatic peri-prosthetic fractures are relatively rare fractures that pose a significant surgical challenge. They have a fracture pattern that is different from its iatrogenic counterpart. This study aimed at reviewing the modalities of treatment of such injuries, proposing a treatment algorithm and reporting the outcomes of these injuries.

PATIENTS AND METHODS

We propose an algorithm for management of traumatic peri-prosthetic acetabular fractures which depends on fracture displacement, implant stability and associated bone loss.Twelve patients with traumatic peri-prosthetic acetabular fractures were treated between January 2012 and December 2018. All patients were treated surgically. Patients were allowed immediate weight bearing as pain allowed. Assessment was carried out using the Oxford Hip Score (OHS) and the Merle D'aubigné score (MDP).

RESULTS

Mean patient age 71 (range: 59-80). 8 patients underwent implant removal, fracture fixation and re-implantation of revision acetabular cup (displaced fracture, unstable implant, adequate bone stock). Three patients required acetabular reconstruction (inadequate bone stock). One patient underwent revision acetabular component. One patient suffered from recurrent dislocation that required surgical intervention. Mean follow up was 27 Months (range 12-48). Mean OHS was 36 (range 10-47). Mean MDP was 12 (range 9-18) with 80% excellent and good results.

CONCLUSION

Surgical management of peri-prosthetic acetabular fractures can produce good to excellent results provided adequate assessment and surgical planning have been carried out. Fracture displacement, implant stability and bone stock should be carefully assessed.