Accuracy of guide wire placement for femoral neck stabilization using 3D printed drill guides

[3D printing/implants in traumatology]

The use of 3D printing offers numerous application possibilities in traumatology, including anatomic models, repositioning and drilling guides as well as patient-specific implants. The greatest challenge lies in the rapid availability as many procedures require an immediate intervention. Anatomic models support surgical planning by complementing visual impressions with tactile ones. Printed models not only help in the establishment of surgical strategies but also enhance patient clarification. Studies demonstrate that these models significantly reduce the operating time, duration of fluoroscopy and blood loss, particularly for joint fractures. Repositioning and drilling guides simplify complex procedures and improve outcomes; however, they require precise planning and critical evaluation by the surgeon. Intraoperative guides are helpful, for instance, in accurately placing screws, especially in difficult to access areas or in metaphyseal fractures lacking clear references. Individualized implants play a lesser role in acute care but are useful for posttraumatic defects or corrective osteotomy. In the conservative segment, such as customized splints, 3D printing is being tested but with mixed results. Key requirements for 3D printing in traumatology include high-resolution computed tomography (CT), precise data processing and swift production. Regulatory hurdles and lack of reimbursement currently limit the widespread use. An optimized collaboration between technology and medicine, along with standardized processes, are essential for effectively integrating this technology into practice.

Fabricating patient-specific 3D printed drill guides to treat femoral head avascular necrosis

BACKGROUND

Femoral head avascular necrosis (AVN), or death of femoral head tissue due to a lack of blood supply, is a leading cause of total hip replacement for non-geriatric patients. Core decompression (CD) is an effective treatment to re-establish blood flow for patients with AVN. Techniques aimed at improving its efficacy are an area of active research. We propose the use of 3D printed drill guides to accurately guide therapeutic devices for CD.

METHODS

Using femur sawbones, image processing software, and 3D modeling software, we created a custom-built device with pre-determined drill trajectories and tested the feasibility of the 3D printed drill guides for CD. A fellowship trained orthopedic surgeon used the drill guide to position an 8 ga, 230 mm long decompression device in the three synthetic femurs. CT scans were taken of the sawbones with the drill guide and decompression device. CT scans were processed in the 3D modeling software. Descriptive statistics measuring the angular and needle-tip deviation were compared to the original virtually planned model.

RESULTS

Compared to the original 3D model, the trials had a mean displacement of 1.440 ± 1.03 mm and a mean angle deviation of 1.093 ± 0.749º.

CONCLUSIONS

The drill guides were demonstrated to accurately guide the decompression device along its predetermined drill trajectory. Accuracy was assessed by comparing values to literature-reported values and considered AVN lesion size. This study demonstrates the potential use of 3D printing technology to improve the efficacy of CD techniques.

Evaluation of a 3D-Printed Reduction Guide for Minimally Invasive Plate Osteosynthesis of Short Oblique Radial Diaphyseal Fracture in Dogs: A Cadaveric Study

This study aims to evaluate the clinical application of three-dimensional (3D)-printed custom reduction guides (3DRG) for minimally invasive plate osteosynthesis (MIPO) of short oblique radial diaphyseal fractures. Canine forelimb specimens (n = 24) were prepared and a diaphyseal short oblique fracture was simulated in the distal radius and ulna. Bone fragments were stabilized with the MIPO technique using a 3DRG (Group A), open reduction (Group B), or closed reduction with circular external skeletal fixation (ESF) (Group C). The diaphyseal short oblique fractures were created in each radius at one-third of the radial length from the distal radial articular surface. Surgical stabilization of the fractures was performed in each group. Pre and postoperative radiographic images were obtained to measure frontal angulation (FA), sagittal angulation (SA), frontal joint reference line angulation (fJRLA), sagittal joint reference line angulation (sJRLA), translational malalignment and fracture gap width. Surgical time was also measured. In the homogeneity test, differences in SA, sJRLA, craniocaudal translation and fracture gap before and after surgery had no significant difference among the three groups. On the other hand, differences in FA, fJRLA, mediolateral translation and surgical time before and after surgery had significant differences among the three groups. In the post hoc test, only surgical time showed a significant difference between the three groups, and group A showed the shortest surgical time. The use of 3DRG for MIPO of short oblique radial diaphyseal fractures in dogs is reliable for the alignment and apposition of fractures and reduces surgical time.

The feasibility of a novel 3D-Printed patient specific cutting guide for extended trochanteric osteotomies

BACKGROUND

The extended trochanteric osteotomy (ETO) is a surgical technique utilized to expose the intramedullary canal of the proximal femur, protect the soft tissues and promote reliable healing. However, imprecise execution of the osteotomy can lead to fracture, soft tissue injury, non-union, and unnecessary morbidity. We developed a technique to create patient specific, 3D-printed cutting guides to aid in accurate positioning of the ETO and improve osteotomy quality and outcomes.

METHODS

Patient specific cutting guides were created based on CT scans using Synopysis Simpleware ScanIP and Solidworks. Custom 3D printed cutting guides were tested on synthetic femurs with foam cortical shells and on cadaveric femurs. To confirm accuracy of the osteotomies, dimensions of the performed osteotomies were compared to the virtually planned osteotomies.

RESULTS

Use of the patient specific ETO cutting guides resulted in successful osteotomies, exposing the femoral canal and the femoral stem both in synthetic sawbone and cadaveric testing. In cadaveric testing, the guides allowed for osteotomies without fracture and cuts made using the guide were accurate within 6 percent error from the virtually planned osteotomy.

CONCLUSION

The 3D-printed patient specific cutting guides used to aid in ETOs proved to be accurate. Through the iterative development of cutting guides, we found that a simple design was key to a reliable and accurate guide. While future clinical trials in human subjects are needed, we believe our custom 3D printed cutting guide design to be effective at aiding in performing ETOs for revision total hip arthroplasty surgeries.

Fabricating Patient-Specific 3D Printed Drill Guides to Treat Femoral Head Avascular Necrosis

Background

Femoral head avascular necrosis (AVN), or death of femoral head tissue due to a lack of blood supply, is a leading cause of total hip replacement for non-geriatric patients. Core decompression (CD) is an effective treatment to re-establish blood flow for patients with AVN. Techniques aimed at improving its efficacy are an area of active research. We propose the use of 3D printed drill guides to accurately guide therapeutic devices for CD.

Methods

Using femur sawbones, image processing software, and 3D modeling software, we created a custom-built device with pre-determined drill trajectories and tested the feasibility of the 3D printed drill guides for CD. A fellowship trained orthopedic surgeon used the drill guide to position an 8 ga, 230 mm long decompression device in the three synthetic femurs. CT scans were taken of the sawbones with the drill guide and decompression device. CT scans were processed in the 3D modeling software. Descriptive statistics measuring the angular and needle-tip deviation were compared to the original virtually planned model.

Results

Compared to the original 3D model, the trials had a mean displacement of 1.440±1.03 mm and a mean angle deviation of 1.093±0.749°.

Conclusions

The drill guides were demonstrated to accurately guide the decompression device along its predetermined drill trajectory. Accuracy was assessed by comparing values to literature-reported values and considered AVN lesion size. This study demonstrates the potential use of 3D printing technology to improve the efficacy of CD techniques.

Medical 3D Printing Using Desktop Inverted Vat Photopolymerization: Background, Clinical Applications, and Challenges

Medical 3D printing is a complex, highly interdisciplinary, and revolutionary technology that is positively transforming the care of patients. The technology is being increasingly adopted at the Point of Care (PoC) as a consequence of the strong value offered to medical practitioners. One of the key technologies within the medical 3D printing portfolio enabling this transition is desktop inverted Vat Photopolymerization (VP) owing to its accessibility, high quality, and versatility of materials. Several reports in the peer-reviewed literature have detailed the medical impact of 3D printing technologies as a whole. This review focuses on the multitude of clinical applications of desktop inverted VP 3D printing which have grown substantially in the last decade. The principles, advantages, and challenges of this technology are reviewed from a medical standpoint. This review serves as a primer for the continually growing exciting applications of desktop-inverted VP 3D printing in healthcare.

Patient-Specific Guides for Accurate and Precise Positioning of Osseointegrated Implants in Transfemoral Amputations: A Proof-of-Concept In Vitro Study

Background and Objectives: The treatment of transfemoral amputees using osseointegrated implants for prosthetic anchorage requires accurate implant positioning when using threaded bone-anchoring implants due to the curvature of the femur and the risk of cortical penetration in misaligned implants. This study investigated the accuracy and precision in implant positioning using additively manufactured case-specific positioning guides. Materials and Methods: The geometry and density distribution of twenty anatomic specimens of human femora were assessed in quantitative computed tomography (QCT) scanning. The imaging series were used to create digital 3D specimen models, preoperatively plan the optimal implant position and manufacture specimen-specific positioning guides. Following the surgical bone preparation and insertion of the fixture (threaded bone-anchoring element) (OPRA; Integrum AB, Mölndal, Sweden), a second QCT imaging series and 3D model design were conducted to assess the operatively achieved implant position. The 3D models were registered and the deviations of the intraoperatively achieved implant position from the preoperatively planned implant position were analyzed as follows. The achieved, compared to the planned implant position, was presented as resulting mean hip abduction or adduction (A/A) and extension or flexion (E/F) and mean implant axis offset in medial or lateral (M/L) and anterior or posterior (A/P) direction measured at the most distal implant axis point. Results: The achieved implant position deviated from the preoperative plan by 0.33 ± 0.33° (A/A) and 0.68 ± 0.66° (E/F) and 0.62 ± 0.55 mm (M/L) and 0.68 ± 0.56 mm (A/P), respectively. Conclusions: Using case-specific guides, it was feasible to achieve not only accurate but also precise positioning of the implants compared to the preoperative plan. Thus, their design and application in the clinical routine should be considered, especially in absence of viable alternatives.

Simulating Prophylactic Fixation Methods for Osteoporotic Femoral Neck Fracture Prevention

INTRODUCTION

Geriatric patients who suffer femoral neck fractures have high morbidity and mortality. Prophylactic fixation of the femoral neck is a potential avenue to reduce the incidence of femoral neck fractures. We studied 3 different implants traditionally used to stabilize the femoral neck: 6.5 mm cannulated screws (CANN), the femoral neck system (FNS) (Depuy Synthes), and the dynamic hip screw (DHS) (Depuy Synthes).

MATERIALS AND METHODS

Five osteoporotic Sawbone femurs were used for each model and a control group. Two scenarios were investigated: single leg stance to measure construct stiffness and lateral impact to measure construct stiffness, energy to fracture, and qualitative examination of fracture patterns. Stiffness for each femur and energy to fracture for the lateral impact scenario were calculated and compared between groups using one-way ANOVA.

RESULTS

DHS showed significantly higher stiffness than the other 2 implants and the control in single leg stance. In the lateral impact scenario, the DHS and CANN were significantly stiffer FNS and the control. Femurs implanted with CANN tended to fracture at the greater trochanter while FNS fractured in a transverse subtrochanteric pattern, and DHS fractured obliquely in the subtrochanteric region.

DISCUSSION

FNS and DHS experienced fracture patterns less amenable to surgical correction. CANN and DHS proved better able to resist external forces in the lateral fall scenario. CANN also proved better able to resist external forces in the single leg stance scenario and experienced a more amenable fracture pattern in the lateral fall scenario.

CONCLUSIONS

FNS was less able to resist external forces compared with the other implants. This work informs the potential implications between the choice of implants that, although historically have not been used prophylactically, may be considered in the future for prophylactic stabilization of the femoral neck. Cadaveric study and clinical trials are recommended for further study.

Correction: Accuracy of guide wire placement for femoral neck stabilization using 3D printed drill guides

An amendment to this paper has been published and can be accessed via the original article.