Tailor-made Surgical Guide Reduces Incidence of Outliers of Cup Placement

Is AI 3D-printed PSI an accurate option for patients with developmental dysplasia of the hip undergoing THA?

BACKGROUND

In traditional surgical procedures, significant discrepancies are often observed between the pre-planned templated implant sizes and the actual sizes used, particularly in patients with congenital hip dysplasia. These discrepancies arise not only in preoperative planning but also in the precision of implant placement, especially concerning the acetabular component. Our study aims to enhance the accuracy of implant placement during Total Hip Arthroplasty (THA) by integrating AI-enhanced preoperative planning with Patient-Specific Instrumentation (PSI). We also seek to assess the accuracy and clinical outcomes of the AI-PSI (AIPSI) group in comparison to a manual control group.

METHODS

This study included 60 patients diagnosed with congenital hip dysplasia, randomly assigned to either the AIPSI or manual group, with 30 patients in each. No significant demographic differences between were noted the two groups. A direct anterior surgical approach was employed. Postoperative assessments included X-rays and CT scans to measure parameters such as the acetabular cup anteversion angle, acetabular cup inclination angle, femoral stem anteversion angle, femoral offset, and leg length discrepancy. Functional scores were recorded at 3 days, 1 week, 4 weeks, and 12 weeks post-surgery. Data analysis was conducted using SPSS version 22.0, with the significance level was set at α = 0.05.

RESULTS AND CONCLUSION

The AIPSI group demonstrated greater prosthesis placement accuracy. With the aid of PSI, AI-planned THA surgery provides surgeons with enhanced precision in prosthesis positioning. This approach potentially offers greater insights and guidelines for managing more complex anatomical variations or cases.

Using Three-Dimensional Printing Technology to Solve Complex Primary Total Hip Arthroplasty Cases: Do We Really Need Custom-Made Guides and Templates? A Critical Systematic Review on the Available Evidence

The burden of osteoarthritis (OA) is around 300 million people affected worldwide, with the hip representing a commonly affected joint. Total hip arthroplasty (THA) has been used with notable success as a definitive treatment to improve pain and function in hip OA patients. The recent advent of new technologies, such as 3D printing, has pushed the application of these new concepts toward applications for the well-known THA. Currently, the evidence on the use of 3D printing to aid complex primary THA cases is still scarce.

METHODS

An extensive literature review was conducted to retrieve all articles centered on the use of 3D printing in the setting of primary THA.

RESULTS

A total of seven studies were included in the present systematic review. Four studies investigated the use of 3D-printed surgical guides to be used during surgery. The remaining three studies investigated the benefit of the use of 3D-printed templates of the pelvis to simulate the surgery.

CONCLUSIONS

The use of 3D printing could be a promising aid to solve difficult primary total hip arthroplasty cases. However, the general enthusiasm in the field is not supported by high-quality studies, hence preventing us from currently recommending its application in everyday practice.

Patient specific instrumentation in ACL reconstruction: a proof-of-concept cadaver experiment assessing drilling accuracy when using 3D printed guides

INTRODUCTION

Accurate positioning of the femoral tunnel in ACL reconstruction is of the utmost importance to reduce the risk of graft failure. Limited visibility during arthroscopy and a wide anatomical variance attribute to femoral tunnel malposition using conventional surgical techniques. The purpose of this study was to determine whether a patient specific 3D printed surgical guide allows for in vitro femoral tunnel positioning within 2 mm of the planned tunnel position.

MATERIALS AND METHODS

A patient specific guide for femoral tunnel positioning in ACL reconstruction was created for four human cadaveric knee specimens based on routine clinical MRI data. Fitting properties were judged by two orthopedic surgeons. MRI scanning was performed both pre- and post-procedure. The planned tunnel endpoint was compared to the actual drilled femoral tunnel.

RESULTS

This patient specific 3D printed guide showed a mean deviation of 5.0 mm from the center of the planned femoral ACL origin.

CONCLUSION

In search to improve accuracy and consistency of femoral tunnel positioning in ACL reconstruction, the use of a patient specific 3D printed surgical guide is a viable option to explore further. The results are comparable to those of conventional techniques; however, further design improvements are necessary to improve accuracy and enhance reproducibility.

Artificially Intelligent Three-Dimensionally-Printed Patient-Specific Instrument Improves Total Hip Arthroplasty Accuracy

BACKGROUND

Patient-specific instrumentation (PSI) has the potential to improve the accuracy of implant positioning in total hip arthroplasty (THA). This prospective clinical study aimed to develop artificial intelligence to increase PSI production efficiency and assess accuracy, clinical outcomes, and learning curves.

METHODS

A convolutional neural network was applied to automatically process computer tomography images. PSI size and position were designed to guide the acetabular preparation and femoral neck resection. Thirty patients who underwent PSI-assisted THAs were matched to thirty patients who underwent free-hand THAs, and the component positions, as well as radiographic and clinical outcomes were analyzed.

RESULTS

PSI-assisted THA was significantly more accurate than free-hand THA at achieving the target component position. The mean absolute errors of cup inclination (P = .004) and anteversion (P < .001) were significantly smaller in the PSI group with fewer outliers. Calcar length (P = .002) and neck length (P = .026) were also more accurate in the PSI group. The leg length discrepancy was significantly lower in the PSI group (P = .002). There were no significant differences in operation time, blood loss, leg length discrepancy, or cup position among the first, second, and last 10 cases.

CONCLUSION

PSI-assisted THA offered more accurate component positions and better radiographic outcomes than free-hand THA. There was no evidence of a learning curve. Our findings suggest that PSI is a convenient and practical option to help surgeons achieve accurate surgical outcomes.

Determining the Relationship between Mechanical Properties and Quantitative Magnetic Resonance Imaging of Joint Soft Tissues Using Patient-Specific Templates

To determine whether the mechanical properties of joint soft tissues such as cartilage can be calculated from quantitative magnetic resonance imaging (MRI) data, we investigated whether the mechanical properties of articular cartilage and meniscus scheduled to be resected during arthroplasty are correlated with the T2 relaxation time on quantitative MRI at the same location. Six patients who had undergone knee arthroplasty and seven who had undergone hip arthroplasty were examined. For the knee joint, the articular cartilage and lateral meniscus of the distal lateral condyle of the femur and proximal lateral tibia were examined, while for the hip joint, the articular cartilage above the femoral head was studied. We investigated the relationship between T2 relaxation time by quantitative MRI and stiffness using a hand-made compression tester at 235 locations. The patient-individualized template technique was used to align the two measurement sites. The results showed a negative correlation (from -0.30 to -0.35) in the less severely damaged articular cartilage and meniscus. This indicates that tissue mechanical properties can be calculated from T2 relaxation time, suggesting that quantitative MRI is useful in determining when to start loading after interventional surgery on cartilage tissue and in managing the health of elderly patients.

The presence of 3D printing in orthopedics: A clinical and material review

The field of additive manufacturing, 3D printing (3DP), has experienced an exponential growth over the past four decades, in part due to increased accessibility. Developments including computer-aided design and manufacturing, incorporation of more versatile materials, and improved printing techniques/equipment have stimulated growth of 3DP technologies within various industries, but most specifically the medical field. Alternatives to metals including ceramics and polymers have been garnering popularity due to their resorbable properties and physiologic similarity to extracellular matrix. 3DP has the capacity to utilize an assortment of materials and printing techniques for a multitude of indications, each with their own associated benefits. Within the field of medicine, advances in medical imaging have facilitated the integration of 3DP. In particular, the field of orthopedics has been one of the earliest medical specialties to implement 3DP. Current indications include education for patients, providers, and trainees, in addition to surgical planning. Moreover, further possibilities within orthopedic surgery continue to be explored, including the development of patient-specific implants. This review aims to highlight the use of current 3DP technology and materials by the orthopedic community, and includes comments on current trends and future direction(s) within the field.

Review of Enhanced Handheld Surgical Drills

The handheld drill has been used as a conventional surgical tool for centuries. Alongside the recent successes of surgical robots, the development of new and enhanced medical drills has improved surgeon ability without requiring the high cost and consuming setup times that plague medical robot systems. This work provides an overview of enhanced handheld surgical drill research focusing on systems that include some form of image guidance and do not require additional hardware that physically supports or guides drilling. Drilling is reviewed by main contribution divided into audio-, visual-, or hardware-enhanced drills. A vision for future work to enhance handheld drilling systems is also discussed.

3D-printed patient specific instruments for corrective osteotomies of the lower extremity

3D-printing has become a promising adjunct in orthopedic surgery over the past years. A significant drop in costs and increased availability of the required hardware and software needed for using the technique, have resulted in a relatively fast adaptation of 3D-printing techniques for various indications. In this review, the role of 3D-printing for deformity corrections of the lower extremity is described.

The efficacy of patient specific instrumentation (PSI) in total hip arthroplasty (THA): A systematic review and meta-analysis

Background

Patient-specific instrumentation (PSI) has been suggested to reduce improper component positioning, though the effectiveness of PSI in total hip arthroplasty (THA) remains inconclusive. The purpose of this study was to evaluate the radiographic parameters and clinical outcomes comparing PSI and standard instrumentation (SI).

Methods

This systematic review and meta-analysis was conducted in accordance with the 2020 PRISMA statement and was registered on PROSPERO. PubMed, Embase, Scopus, Google Scholar, and ClinicalTrials.gov were searched for relevant studies pertaining to the use of PSI in THA. Inclusion criteria included PSI used in THA, PSI was directly compared to SI, and publication in English. Exclusion criteria included non-primary THA, review articles, abstracts, book chapters, and animal models.

Results

2,458 studies were initially identified, with 13 studies (677 THAs: 338 controls, 339 PSI) meeting all criteria. PSI was favored for the deviation from the preoperative plan for acetabular cup position for anteversion (p = 0.04) and inclination (p = 0.0002); risk of acetabular cup positioning outside the Lewinnek safe zone for anteversion (p = 0.005) and inclination (p < 0.0001); and postoperative Harris Hip Score (p = 0.0002). No significant differences were found for the deviation from the preoperative plan for femoral stem position for anteversion (p = 0.74) or varus/valgus (p = 0.15); intraoperative time (p = 0.55); or intraoperative blood loss (p = 0.62).

Conclusion

The use of PSI in THA is effective in improving acetabular component positioning and postoperative functional outcomes, without increasing intraoperative time or blood loss, compared to SI.

Functionally graded additive manufacturing for orthopedic applications

Background

Additive Manufacturing due to its benefits in developing parts with complex geometries and shapes, has evolved as an alternate manufacturing process to develop implants with desired properties. The structure of human bones being anisotropic in nature is biologically functionally graded i,e. The structure possesses different properties in different directions. Therefore, various orthopedic implants such as knee, hip and other bone plates, if functionally graded can perform better. In this context, the development of functionally graded (FG) parts for orthopedic application with tailored anisotropic properties has become easier through the use of additive manufacturing (AM).

Objectives

and Rationale: The current paper aims to study the various aspects of additively manufactured FG parts for orthopedic applications. It presents the details of various orthopedic implants such as knee, hip and other bone plates in a structured manner. A systematic literature review is conducted to study the various material and functional aspects of functionally graded parts for orthopedic applications. A section is also dedicated to discuss the mechanical properties of functionally graded parts.

Conclusion

The literature revealed that additive manufacturing can provide lot of opportunities for development of functionally graded orthopedic implants with improved properties and durability. Further, the effect of various FG parameters on the mechanical behavior of these implants needs to be studied in detail. Also, with the advent of various AM technologies, the functional grading can be achieved by various means e.g. density, porosity, microstructure, composition, etc. By varying the AM parameters. However, the current limitations of cost and material biocompatibility prevent the widespread exploitation of AM technologies for various orthopedic applications.

3D Printed Guides and Preoperative Planning for Uncemented Stem Anteversion Reconstruction during Hip Arthroplasty: A Pilot Study

Objective

To investigate if 3D printed guides and preoperative planning can accurately control femoral stem anteversion.

Methods

A prospective comparative study was carried out from 2018 to 2020, including 53 patients who underwent hip arthroplasty for femoral neck fracture. The target rotation center of the femoral head is determined by three-dimensional planning. In group A, planning was made by 2D templates. In group B, preoperative 3D planning and 3D printed osteotomy/positioning guides were performed. After the operation, 3D model registration was performed to calculate the accuracy of anteversion restoration.

Results

We screened 60 patients and randomized a total of 53 to 2 parallel study arms: 30 patients to the group A (traditional operation) and 23 patients to the group B (3D preoperative planning and 3D printed guide). There were no significant differences in demographic or perioperative data between study groups. The restoration accuracy of group A was 5.42° ± 3.65° and of group B was 2.32° ± 1.89°. The number and rate of abnormal cases was 15 (50%) and 2 (8.7%), respectively. Significant statistical differences were found in angle change, restoration accuracy, and number of abnormal cases.

Conclusion

Three-dimensional preoperative planning and 3D printed guides can improve the accuracy of the restoration of femoral anteversion during hip arthroplasty.

Improving MiniHip femoral prosthesis positioning using a cross-laser projection system in total hip arthroplasty by an anterolateral supine approach

Background

The authors developed a cross‐laser projection system (CLP) to place a femoral neck‐sparing short stem using the minimally invasive anterolateral supine approach in total hip arthroplasty. This study aimed to verify the utility of CLP.

Methods

Thirty joints were assessed with the MiniHip (Corin). The authors compared femoral component implantation with a patient‐specific femoral osteotomy guide (PSG) for the femoral neck‐cut (PSG group), with the CLP attached to the rasp handle to irradiate the cross‐laser to the target of PSG (CLP group), and without PSG or CLP (control group).

Results

In the CLP group, the positional deviation of anteversion, anterior/posterior tilt and varus/valgus placement of the stem postoperatively were 1.8° ± 0.2°, 2.0° ± 2.0° and 2.0° ± 0.1°, respectively. The positional deviation of anteversion (p < 0.001) and anterior/posterior tilt (p = 0.036) were significantly smaller than those in the other groups.

Conclusions

CLP improves the accuracy of MiniHip femoral prosthesis placement.

Application of 3D Printing in Hip and Knee Arthroplasty: A Narrative Review

INTRODUCTION

Ideal surgical positioning and placement of implants during arthroplasty are crucial for long-term survival and optimal functional outcomes. Inadequate bone stock or defects, and anatomical variations can influence the outcomes. Three-dimensional printing (3DP) is an evolving technology that could provide patient-specific instrumentation and implants for arthroplasty, taking into account anatomical variations and defects. However, its application in this field is still not adequately studied and described. The present review was conceptualised to assess the practicality, the pros and cons and the current status of usage of 3DP in the field of hip and knee arthroplasties and joint reconstruction surgeries.

METHODS

A PubMed database search was conducted and a total number of 135 hits were obtained, out of which only 30 articles were relevant. These 30 studies were assessed to obtain the qualitative evidence of the applicability and the current status of 3D printing in arthroplasty.

RESULTS

Currently, 3DP is used for preoperative planning with 3D models, to assess bone defects and anatomy, to determine the appropriate cuts and to develop patient-specific instrumentation and implants (cages, liners, tibial base plates, femoral stem). Its models can be used for teaching and training young surgeons, as well as patient education regarding the surgical complexities. The outcomes of using customised instrumentations and implants have been promising and 3D printing can evolve into routine practice in the years to come.

CONCLUSION

3D printing in arthroplasty is an evolving field with promising results; however, current evidence is insufficient to determine significant advantages that can be termed cost effective and readily available.

3D Printing Navigation Template Used in Total Hip Arthroplasty for Developmental Dysplasia of the Hip

BACKGROUND

The purpose of our study was to explore the feasibility of 3D printing navigation template used in total hip arthroplasty (THA) for adult developmental dysplasia of the hip (DDH).

MATERIALS AND METHODS

25 patients who received THA for DDH from February 2014 to May 2018 were randomized into the control or intervention group. Of these patients, 12 received THAs assisted with 3D printing navigation templates, 13 THAs underwent THAs without navigation templates. The mean follow-up was 1.6 (range, 1.2-3.8) years. Clinical scores and radiographic results were evaluated for two groups.

RESULTS

Operating time, intra- and postoperative hemorrhage and Harris Hip Score (HHS) at 6 months postoperatively in the 3D printing group were better than those for patients in the conventional hip replacement group, while infection and implant loosening were 0 in the two groups. There were no significant differences in anteversion angle, abduction angle and the distance from rotation center to the ischial tuberosity line in 3D printing group as compared to the normal side. The abduction angle and the distance from rotation center to the ischial tuberosity line were significantly different between the two sides in the traditional group.

CONCLUSION

Application of the 3D printing template for THA with DDH can facilitate the surgical procedure and create an ideal artificial acetabulum placement.

A single-use, size-specific, nylon arthroplasty guide: a preliminary study for hip resurfacing

INTRODUCTION

In arthroplasty surgery, positioning of the components must be accurate and reproducible to avoid complications. Conventional guides are often used to align a component, but they require surgical skill and experience, and are prone to error. To this end, a single-use, size-specific, nylon guide (single-use nylon guide) has been developed for the purpose of increasing the accuracy without adding extra cost to the operation. The effectiveness of this type of guide was evaluated in using a synthetic bone study.

METHODS

A total of 66 synthetic femurs with the same osteoarthritic morphology were prepared. 3 surgeons participated in the experiments, and each surgeon created a drill hole for the femoral component by using the single-use nylon guide or a commercially-available, conventional, metal, neck-based guide (conventional guide). Anteversion, inclination, and insertion point acquired by the guide were compared between the guides, between surgeons, and to the computer-based plan.

RESULTS

Anteversion acquired by the single-use nylon guide (6.7° [4.9-11.5°]) was significantly closer to the plan (14.6°) than that acquired by the conventional guide (4.3° [2.4-8.6°]) (p = 0.03). The insertion point was also significantly closer to the plan for the single-use nylon guide (3.8 mm ± 1.6 mm) than the conventional guide (5.7 mm ± 2.4 mm) (p < 0.001). No significant difference was found for the inclination (p = 0.76).

CONCLUSION

A single-use, size-specific nylon guide was effective in acquiring a higher accuracy and precision in anteversion and insertion point than a conventional guide in this synthetic bone, hip resurfacing arthroplasty study. The use of single-use guides in other orthopaedic procedures should be explored.

Periacetabular osteotomy using three-dimensional cutting and reposition guides: a cadaveric study

The goal of periacetabular osteotomy (PAO) is to reorient the acetabulum in a more physiological position. Its realization remains challenging regarding the final position of the acetabulum. Assistance with custom cutting- and reorientation-guides would thus be very helpful. Our purpose is to present a pilot study on such guides. Eight cadaveric hemipelvis were scanned using CT. After segmentation, 3D models of each specimen were created, a PAO was virtually performed and reorientation of the acetabula were defined. A specific guide was designed aiming to assist in iliac, posterior column and superior pubic ramus cuts as well as in acetabulum reorientation. Furthermore, the acetabular position was planned. Three-dimensional printed guides were used to perform PAO using the modified Smith-Peterson approach. The post-operative CT images and virtually planned acetabulum reorientation were compared in terms of acetabular index (AC), lateral centre edge angle (LCE), acetabular anteversion angle (AcetAV). There was no intra-articular or posterior column fracture seen. Two cadavers showed very low bone quality with insufficient stability of fixation and were excluded from further analysis. Correlation between the post-operative result and planning of the six included cadavers revealed the following mean deviations: 5° (SD ±3°) for AC angle, 6° (SD ±4°) for LCE angle and 15° (SD ±11°) for AcetAV angle. The use of 3D cutting and reorientation blocks for PAO was possible through a modified Smith-Peterson approach and revealed accurate fit to bone, accurate positioning of the osteotomies and acceptable planned corrections in cadavers with good bone quality.

Is the alignment guide technique in total hip arthroplasty sufficient for accurate cup positioning with a modified Watson Jones approach?

PURPOSE:

Cup setting with only an alignment guide has been reported to be inaccurate in the lateral decubitus position in total hip arthroplasty (THA). We assessed the accuracy of cup positioning using only the alignment guide technique via a modified Watson Jones approach in the lateral decubitus position.

METHODS:

Two hundred hips of 189 patients underwent THA from October 2014 to September 2016 via a modified Watson Jones approach. In the final sample, 181 hips of 171 patients (35 males, 136 females) were included in this investigation. The alignment of the cup was evaluated by an anteroposterior radiograph of the pelvis 1 week after surgery. Measurements were divided into safe zone determined by Callanan and Lewinnek.

RESULTS:

There were 168 (92.8%) acetabular cups that were placed within the safe zone for both inclination and anteversion based on the safe zones defined by Lewinnek, and 134 (74%) acetabular cups that were placed within the safe zone defined by Callanan. Multiple logistic analysis showed that the laterality and the addition of the confirmation method were indicators for malpositioning of combined inclination and anteversion.

CONCLUSION:

Our data suggested that even if special tools were not used in the lateral decubitus position, using only the alignment guide enabled cup positioning to be achieved with 92.8% accuracy in the Lewinnek safe zone and 74% accuracy in the Callanan safe zone. Multiple logistic analysis showed that the laterality and the addition of a confirmation alignment guide influenced the accuracy of cup positioning.

Patient-specific guides improve hip arthroplasty surgical accuracy

The role of patient-specific (PS) technology in total hip arthroplasty remains relatively unexplored. We asked whether PS guides: (1) Reduced average surgical errors? (2) Reduced outlier error frequencies? (3) Could predict the size of implants used? A single surgeon implanted femurs using either standard or PS guides and was blinded to the pre-operative plans. There were significant differences in median leg length errors between standard (3.3 mm) and PS groups (1.4 mm), U = 110, z = -2.3, p = 0.02. In contrast to the PS group, the standard group had significantly more outlier errors and frequently undersized implants. PS guides improve hip arthroplasty surgical accuracy.Abbreviations: PS: patient specific; THA: total hip arthroplasty; LLD: leg length discrepancies; HRA: hip resurfacing arthroplasty.

Patient-Specific Surgical Guide for Total Hip Arthroplasty

Three-dimensional printing technique has been adapted for orthopedic surgery, and a patient-specific surgical guide (PSG) has been introduced as a convenient surgical instrument and implicated in the ideal positioning of the components, including acetabular and femoral components in total hip arthroplasty (THA). PSG is designed and manufactured based on preoperative imaging data, mainly computed tomography (CT) data. PSGs for implantation in THA are classified into three types: PSG for guidewire insertion, PSG for bone cutting, and PSG for bone reaming and implant fixation. PSG positioning accuracy depends on the PSG design and surgical preparation in contact area on the bone surface. PSGs for the acetabular component, for the conventional femoral component, and for the resurfacing femoral component have been clinically used. To achieve precise implantation, precise PSG setting needs and careful surgical preparation of soft tissues are important.

3D-printed Patient-specific Guides for Hip Arthroplasty

Surgeons and engineers constantly search for methods to improve the surgical positioning of implants used for joint arthroplasty. Rapid prototyping is being used to develop patient-specific instrumentation (PSI) and has already been successfully translated into large-scale clinical use for knee arthroplasty. PSI has been used in shoulder arthroplasty; however, it is not yet known whether PSI provides improved accuracy and outcomes compared with conventional methods in either shoulder arthroplasty or knee arthroplasty. In the hip, PSI has been limited to the positioning of custom-manufactured implants and a small number of surgeons testing the emerging solutions from different manufacturers. Early results indicate consistent accurate positioning of implants with the use of PSI in hip arthroplasty but with added costs and uncertain effect on clinical outcomes.

Validation of patient-specific surgical guides for femoral neck cutting in total hip arthroplasty through the anterolateral approach

BACKGROUND

The aim of this study was to validate the effectiveness of neck-cut patient-specific surgical guides (PSGs) for femoral component implantation in total hip arthroplasty (THA) through the anterolateral approach compared with that without PSG.

METHODS

A total of 32 fresh cadaveric hips were included. Anatomical stem implantation with wide-base-contact PSG (AWP group) and without PSG (control group) were compared. The absolute errors between preoperative planning and PSG setting (E1), as well as those between preoperative planning and postoperative component implantation (E2) were evaluated using CT.

RESULTS

The E1/E2 values of AWP were 0.9±0.3°/0.6±0.6° in the coronal plane, and 1.7±0.8°/1.0±0.9° in the sagittal plane, and 1.0±0.6 mm/1.0±1.1 mm for the medial height. The E2 value in the sagittal plane (P=0.037) and the medial height (P=0.011) of AWP were significantly smaller than those of control group.

CONCLUSIONS

The neck-cut PSG through the anterolateral approach is effective for femoral component implantation.

3D-printed navigation template in proximal femoral osteotomy for older children with developmental dysplasia of the hip

To explore the feasibility of 3D-printed navigation template in proximal femoral varus rotation and shortening osteotomy for older children with developmental dysplasia of the hip (DDH). Between June 2014 and May 2015, navigation templates were designed and used for 12 DDH patients. Surgical information and outcomes were compared to 13 patients undergoing the same surgery but without navigation template. In template-guided patient group, operation time (21.08 min vs. 46.92 min), number of X-ray exposures (3.92 vs. 6.69), and occurrence of femoral epiphysis damage (0 vs. 0.92) were significantly decreased (P < 0.05). Furthermore, after 12–18 months follow-up, 66.7% and 16.7% of the hips in template-guided group were rated as excellent or good, respectively, according to the McKay criteria; 83.3% and 16.7% by using the Severin criteria respectively. By contrast, 46.2% and 23.1% of the hips in traditional operation group were classed as excellent or good, respectively, using the McKay criteria; 46.2% and 30.8% by using the Severin criteria respectively. The template-guided group achieved a better outcome; however, there was no significant difference. Application of the navigation template for older DDH children can reduce the operation time, radiation exposure, and epiphysis damage, which also simplifies surgery and improves precision.

Patient-Specific Orthopaedic Implants

Patient-specific orthopaedic implants are emerging as a clinically promising treatment option for a growing number of conditions to better match an individual's anatomy. Patient-specific implant (PSI) technology aims to reduce overall procedural costs, minimize surgical time, and maximize patient outcomes by achieving better biomechanical implant fit. With this commercially-available technology, computed tomography or magnetic resonance images can be used in conjunction with specialized computer programs to create preoperative patient-specific surgical plans and to develop custom cutting guides from 3-D reconstructed images of patient anatomy. Surgeons can then place these temporary guides or "jigs" during the procedure, allowing them to better recreate the exact resections of the computer-generated surgical plan. Over the past decade, patient-specific implants have seen increased use in orthopaedics and they have been widely indicated in total knee arthroplasty, total hip arthroplasty, and corrective osteotomies. Patient-specific implants have also been explored for use in total shoulder arthroplasty and spinal surgery. Despite their increasing popularity, significant support for PSI use in orthopaedics has been lacking in the literature and it is currently uncertain whether the theoretical biomechanical advantages of patient-specific orthopaedic implants carry true advantages in surgical outcomes when compared to standard procedures. The purpose of this review was to assess the current status of patient-specific orthopaedic implants, to explore their future direction, and to summarize any comparative published studies that measure definitive surgical characteristics of patient-specific orthopaedic implant use such as patient outcomes, biomechanical implant alignment, surgical cost, patient blood loss, or patient recovery.

The Evolution of Computer-Assisted Total Hip Arthroplasty and Relevant Applications

In total hip arthroplasty (THA), the accurate positioning of implants is the key to achieve a good clinical outcome. Computer-assisted orthopaedic surgery (CAOS) has been developed for more accurate positioning of implants during the THA. There are passive, semi-active, and active systems in CAOS for THA. Navigation is a passive system that only provides information and guidance to the surgeon. There are 3 types of navigation: imageless navigation, computed tomography (CT)-based navigation, and fluoroscopy-based navigation. In imageless navigation system, a new method of registration without the need to register the anterior pelvic plane was introduced. CT-based navigation can be efficiently used for pelvic plane reference, the functional pelvic plane in supine which adjusts anterior pelvic plane sagittal tilt for targeting the cup orientation. Robot-assisted system can be either active or semi-active. The active robotic system performs the preparation for implant positioning as programmed preoperatively. It has been used for only femoral implant cavity preparation. Recently, program for cup positioning was additionally developed. Alternatively, for ease of surgeon acceptance, semi-active robot systems are developed. It was initially applied only for cup positioning. However, with the development of enhanced femoral workflows, this system can now be used to position both cup and stem. Though there have been substantial advancements in computer-assisted THA, its use can still be controversial at present due to the steep learning curve, intraoperative technical issues, high cost and etc. However, in the future, CAOS will certainly enable the surgeon to operate more accurately and lead to improved outcomes in THA as the technology continues to evolve rapidly.

A Patient-Specific Instrument for Femoral Stem Placement During Total Hip Arthroplasty

To ensure that the femoral stem is placed in the proper position during total hip arthroplasty, the authors developed a patient-specific instrument. A total of 10 total hip arthroplasties were performed with the assistance of the patient-specific instrument during this study. The mean accuracy of stem tilt, varus/valgus, and anteversion was 2.1°±4.1°, 1.0°±0.7°, and 4.7°±1.2°, respectively. No complications were observed and no reoperations were required for any of the patients who underwent surgery included in this study. The results support the feasibility of this patient-specific instrument for use during stem placement in total hip arthroplasty. [Orthopedics. 2017; 40(2):e374-e377.].

Application of computer-aided design and 3D-printed navigation template in Locking Compression Pediatric Hip PlateΤΜ placement for pediatric hip disease

BACKGROUND

To investigate the feasibility and accuracy of a drill template based on computer-aided design (CAD) and 3D printing technology for the placement of screws in Locking Compression Pediatric Hip Plate (LCP-PHP).

METHODS

LCP-PHP was used in 11 children [5 with femoral neck fracture and 6 with development dysplasia of hip (DDH)]. Using the CT data, the proximal femur model was created by a 3D printer. Fracture reduction and the placement of the screw in the femoral neck and the LCP-PHP were simulated by the computer. The navigation template was designed by the software to match the proximal femur. After the feasibility of the 3D model operation was demonstrated before the operation, the guide pins and the screws were inserted with the help of the navigate template in the operation.

RESULTS

During surgery, the navigation template for each case was matched to the bony markers of the proximal femur. With the help of the template, in femoral neck fracture cases, three screws could be accurately inserted into the femoral neck to implant the LCP-PHP and stabilize the fracture. The template for DDH includes all operation parameters and steps for proximal femoral varus rotation and shortening osteotomy, which made the surgery much easier to perform. Radiographs taken after surgery showed that the postoperative results closely corresponded to the preoperative computer simulation. The average time taken for LCP-PHP placement was 26.5 min; radiography was used during surgery only for an average of 6.0 times. Postoperative radiographs showed good results.

CONCLUSION

With the use of CAD and 3D printing technology, accurate placement of individualized navigation template of LCP-PHP can be achieved. This technology can reduce intraoperative damage to the femoral neck epiphysis, decrease operation time, reduce intraoperative hemorrhage, and decrease radiation exposure to patients and personnel during the surgery.

3D-printed patient-specific applications in orthopedics

With advances in both medical imaging and computer programming, two-dimensional axial images can be processed into other reformatted views (sagittal and coronal) and three-dimensional (3D) virtual models that represent a patients’ own anatomy. This processed digital information can be analyzed in detail by orthopedic surgeons to perform patient-specific orthopedic procedures. The use of 3D printing is rising and has become more prevalent in medical applications over the last decade as surgeons and researchers are increasingly utilizing the technology’s flexibility in manufacturing objects. 3D printing is a type of manufacturing process in which materials such as plastic or metal are deposited in layers to create a 3D object from a digital model. This additive manufacturing method has the advantage of fabricating objects with complex freeform geometry, which is impossible using traditional subtractive manufacturing methods. Specifically in surgical applications, the 3D printing techniques can not only generate models that give a better understanding of the complex anatomy and pathology of the patients and aid in education and surgical training, but can also produce patient-specific surgical guides or even custom implants that are tailor-made to the surgical requirements. As the clinical workflow of the 3D printing technology continues to evolve, orthopedic surgeons should embrace the latest knowledge of the technology and incorporate it into their clinical practice for patient-specific orthopedic applications. This paper is written to help orthopedic surgeons stay up-to-date on the emerging 3D technology, starting from the acquisition of clinical imaging to 3D printing for patient-specific applications in orthopedics. It 1) presents the necessary steps to prepare the medical images that are required for 3D printing, 2) reviews the current applications of 3D printing in patient-specific orthopedic procedures, 3) discusses the potential advantages and limitations of 3D-printed custom orthopedic implants, and 4) suggests the directions for future development. The 3D printing technology has been reported to be beneficial in patient-specific orthopedics, such as in the creation of anatomic models for surgical planning, education and surgical training, patient-specific instruments, and 3D-printed custom implants. Besides being anatomically conformed to a patient’s surgical requirement, 3D-printed implants can be fabricated with scaffold lattices that may facilitate osteointegration and reduce implant stiffness. However, limitations including high cost of the implants, the lead time in manufacturing, and lack of intraoperative flexibility need to be addressed. New biomimetic materials have been investigated for use in 3D printing. To increase utilization of 3D printing technology in orthopedics, an all-in-one computer platform should be developed for easy planning and seamless communications among different care providers. Further studies are needed to investigate the real clinical efficacy of 3D printings in orthopedic applications.

Effects of coordinate-system construction methods on postoperative computed tomography evaluation of implant orientation after total hip arthroplasty

OBJECTIVE

In total hip arthroplasty, it is important to assess postoperative implant orientation. The computed tomography-based (CT-based) three-dimensional (3D) templating method using 3D preoperative planning software is generally recommended. In this method, postoperative implant orientation within a bony coordinate system can be measured by overlaying a 3D computerized model of the implant on a real postoperative CT image of the implant. The bony coordinate system consists of several reference points (RPs) marked on a CT image of the bone surface. Therefore, preoperative and postoperative coordinate systems do not always match. We investigated how the difference between coordinate systems constructed from RPs chosen by manual methods (M1 and M2) and those constructed by the computer matching method influences the results of measurement validation.

METHODS

In M1, postoperative RPs were chosen without a specific tool in a single planning module. In M2, postoperative RPs were chosen with as little deviation as possible from preoperative RPs, verifying preoperative RPs on another monitor.

RESULTS

M1 and M2 produced mean errors in acetabular cup inclination of 0.7° ± 0.5° and 0.5° ± 0.3°, respectively, and mean errors in cup anteversion of 1.3° ± 1.2° and 0.5° ± 0.4°, respectively, which were statistically significant differences. M1 and M2 produced mean errors in femoral stem anteversion of 2.4° ± 2.0° and 2.7° ± 2.1°, respectively, not a significant difference, but these errors were larger than errors in cup orientation.

DISCUSSION

We recommend referring to preoperative RPs when choosing postoperative RPs. Surgeons must be aware that for evaluation of postoperative stem anteversion, manual methods may produce considerable error.

Accuracy of an adjustable patient-specific guide for acetabular alignment in hip replacement surgery (Optihip)

Implant malalignment in hip arthroplasty increases the risk of revision surgery due to problems such as hip instability, wear, and impingement. Traditional instrumentation lacks accuracy and does not individualize the goal. Computer-assisted surgery (CAS) and patient-specific solutions improve accuracy but add considerably to the cost, amongst other drawbacks. We developed an adjustable mechanical device, called Optihip, which is set to a patient-specific goal preoperatively and is independent of pelvis position intraoperatively. The purpose of the present study was to evaluate Optihip's accuracy ex vivo. Acetabular components were implanted into six cadaveric specimens, 12 hips, by two surgeons, with the device individually adjusted according to preoperative templating on computed tomography (CT) images relative to defined acetabular rim landmarks; options also exist for templating on single or biplanar X-rays. Intraoperatively, the device was positioned on the corresponding anatomical landmarks allowing the insertion of a guide pin, which then defined the desired orientation of the acetabular cup during impaction. Mean absolute difference between the preoperatively planned cup alignment and final acetabular cup orientation, measured from postoperative CT images, was 2.5±1.2° for inclination and 2.5±2.2° for version with maximum values of 4.7° and 6.8°, respectively. Compared with previous in vivo reports, Optihip guided the acetabular cup orientation more accurately than conventional hip arthroplasty, and comparably to CAS or patient-specific systems, while fitting into the normal surgical workflow. Although clinical testing is required to confirm these experimental results, the positive ex vivo accuracy suggests good potential for improving revision rates and patient functional outcome.

Three-dimensional imaging and templating improve glenoid implant positioning

BACKGROUND

Preoperative quantitative assessment of glenoid bone loss, selection of the glenoid component, and definition of its desired location can be challenging. Placement of the glenoid component in the desired location at the time of surgery is difficult, especially with severe glenoid pathological conditions.

METHODS

Forty-six patients were randomly assigned to three-dimensional computed tomographic preoperative templating with either standard instrumentation or with patient-specific instrumentation and were compared with a nonrandomized group of seventeen patients with two-dimensional imaging and standard instrumentation used as historical controls. All patients had postoperative three-dimensional computed tomographic metal artifact reduction imaging to measure and to compare implant position with the preoperative plan.

RESULTS

Using three-dimensional imaging and templating with or without patient-specific instrumentation, there was a significant improvement achieving the desired implant position within 5° of inclination or 10° of version when compared with two-dimensional imaging and standard instrumentation.

CONCLUSION

Three-dimensional assessment of glenoid anatomy and implant templating and the use of these images at the time of surgery improve the surgeon's ability to place the glenoid implant in the desired location.

Validation of patient specific surgical guides in total hip arthroplasty

BACKGROUND

The validation of patient-specific surgical guides (PSGs) by their design and the comparison of planned and actual PSG setting in total hip arthroplasty (THA) have not previously been reported.

METHODS

The errors between preoperative planning and computed tomography (CT)-based PSG setting (E1), and between preoperative planning and implantation (E2) were evaluated using CT in 16 fresh cadaveric hips.

RESULTS

E2 was significantly smaller with the wide-base-contact resurfacing-THA PSG than with the narrow-base-contact type (P<0.05). E1/E2 of the wide-base-contact neck-cut PSG was 1.6±0.7°/2.4±1.1° for the coronal plane and 1.2±0.8 mm/0.7±0.5mm for the medial neck-cut height. E1/E2 of the wide-base-contact cup-impaction PSG was 1.0±0.9°/3.4±1.9° for inclination and 1.7±1.1°/6.6±4.4° for anteversion.

CONCLUSIONS

The wide-base-contact PSG in resurfacing-THA and the PSG for neck-cut in THA could be applied clinically. Although cup-impaction PSG setting was acceptable, errors were made due to the impaction process during cup implantation.

Comparison of acetabular shell position using patient specific instruments vs. standard surgical instruments: a randomized clinical trial

Total hip arthroplasty (THA) survivorship relies largely upon appropriate acetabular cup placement. The purpose of this prospective randomized controlled trial was to determine whether the use of a preoperative 3D planning software in combination with patient specific instrumentation (PSI) results in improved cup placement compared with traditional techniques. Thirty-six THA patients were randomized into standard (STD) or PSI technique. Standard approach was completed using traditional techniques, while PSI cases were planned and customized surgical instruments were manufactured. Postoperative CT scans were used to compare planned to actual results. Differences found between planned and actual anteversion were -0.2° ± 6.9° (PSI) and -6.9°±8.9° (STD) (P = 0.018). Use of 3D preoperative planning along with PSIs resulted in significantly greater anteversion accuracy than traditional planning and instrumentation.

Evaluation of a patient specific femoral alignment guide for hip resurfacing

A novel alternative to conventional instrumentation for femoral component insertion in hip resurfacing is a patient specific, computed tomography based femoral alignment guide. A benchside study using cadaveric femora was performed comparing a custom alignment guide to conventional instrumentation and computer navigation. A clinical series of twenty-five hip resurfacings utilizing a custom alignment guide was conducted by three surgeons experienced in hip resurfacing. Using cadaveric femora, the custom guide was comparable to conventional instrumentation with computer navigation proving superior to both. Clinical femoral component alignment accuracy was 3.7° and measured within ± 5° of plan in 20 of 24 cases. Patient specific femoral alignment guides provide a satisfactory level of accuracy and may be a better alternative to conventional instrumentation for initial femoral guidewire placement in hip resurfacing.

Computer-assisted orthopaedic surgery and robotic surgery in total hip arthroplasty

Various systems of computer-assisted orthopaedic surgery (CAOS) in total hip arthroplasty (THA) were reviewed. The first clinically applied system was an active robotic system (ROBODOC), which performed femoral implant cavity preparation as programmed preoperatively. Several reports on cementless THA with ROBODOC showed better stem alignment and less variance in limb-length inequality on radiographic evaluation, less incidence of pulmonary embolic events on transesophageal cardioechogram, and less stress shielding on the dual energy X-ray absorptiometry analysis than conventional manual methods. On the other hand, some studies raise issues with active systems, including a steep learning curve, muscle and nerve damage, and technical complications, such as a procedure stop due to a bone motion during cutting, requiring re-registration and registration failure. Semi-active robotic systems, such as Acrobot and Rio, were developed for ease of surgeon acceptance. The drill bit at the tip of the robotic arm is moved by a surgeon's hand, but it does not move outside of a milling path boundary, which is defined according to three-dimensional (3D) image-based preoperative planning. However, there are still few reports on THA with these semi-active systems. Thanks to the advancements in 3D sensor technology, navigation systems were developed. Navigation is a passive system, which does not perform any actions on patients. It only provides information and guidance to the surgeon who still uses conventional tools to perform the surgery. There are three types of navigation: computed tomography (CT)-based navigation, imageless navigation, and fluoro-navigation. CT-based navigation is the most accurate, but the preoperative planning on CT images takes time that increases cost and radiation exposure. Imageless navigation does not use CT images, but its accuracy depends on the technique of landmark pointing, and it does not take into account the individual uniqueness of the anatomy. Fluoroscopic navigation is good for trauma and spine surgeries, but its benefits are limited in the hip and knee reconstruction surgeries. Several studies have shown that the cup alignment with navigation is more precise than that of the conventional mechanical instruments, and that it is useful for optimizing limb length, range of motion, and stability. Recently, patient specific templates, based on CT images, have attracted attention and some early reports on cup placement, and resurfacing showed improved accuracy of the procedures. These various CAOS systems have pros and cons. Nonetheless, CAOS is a useful tool to help surgeons perform accurately what surgeons want to do in order to better achieve their clinical objectives. Thus, it is important that the surgeon fully understands what he or she should be trying to achieve in THA for each patient.

Aprotinin and classic wound drainage are unnecessary in total hip replacement - a prospective randomized trial

BACKGROUND

Classic wound drainage is still common in hip replacement but its benefit is doubtful. The role of systemic administration of proteinase inhibitors like aprotinin to avoid perioperative blood loss is still unclear.

PATIENTS AND METHODS

In a prospective randomized trial, the perioperative blood loss in alloplastic hip replacement under the influence of proteinase inhibitor (aprotinin, Trasylol®) using wound drainage as well as compression treatment alone were compared. 80 patients were prospectively randomized in 4 arms. Patients received either aprotinin or placebo during surgery as well as drainage or targeted external wound compression.

RESULTS

Observing the "drug therapy" aprotinin had no effect on the intra- or postoperative blood loss (p>0.05), a trend to lower postoperative hemoglobin decline was found, but without significance. Thrombosis occurred in neither the aprotinin nor in the placebo group. Two patients had a severe allergic drug reaction and were excluded from the study. Under "non drug therapy" with compression therapy and wound drainage a significant difference in blood loss was found (p<0.001). The blood loss was higher under the wound drainage. There was no influence on the infection rate. Yet we could observe increased bruising under the sole external compression treatment.

CONCLUSION

The administration of aprotinin did not achieve the desired reduction of perioperative blood loss. Hence, costs and two severe allergic drug reactions in our study represent arguments against its use in regular treatment. Furthermore, it seems that wound drainage is neglectable in hip replacement and can be substituted by a sole compression treatment.