Clinical value of 3D printing guide plate in core decompression plus porous bioceramics rod placement for the treatment of early osteonecrosis of the femoral head

Automatic planning and geometric analysis of the drilling path in core decompression surgery for osteonecrosis of the femoral head

BACKGROUND AND OBJECTIVE

Core decompression surgery is an effective treatment method for patients with pre-collapse osteonecrosis of the femoral head (ONFH). The treatment relies on accurately predrilling the wire into the necrotic lesion. However, the surgical planning of this drilling path remains unclear. This paper aims to develop a framework to automatically plan the drilling path and analyze its geometric parameters.

METHODOLOGY

The proposed system consists of two stages. The first stage is to detect the key points. Besides the entry point and target point for the drilling path, the center of the femoral head (FH) and the boundary points of the necrotic lesion are also detected for the subsequent geometric analysis. In the second stage, the geometric parameters of the drilling path are analyzed, including the size of the necrotic lesion, the length from the entry point to the target point, the relative location between the FH center and the necrosis center, and the angular range of the drilling path in the anterior-posterior (AP) direction and superior-inferior (SI) direction.

RESULTS

All of the drilling paths designed by the proposed system were considered successful, starting from the proximal subtrochanteric region, terminating at the center of the necrotic lesion, and remaining within the femoral neck. The relative coordinates of the centers of the femoral head and necrotic lesion were (-0.89,5.14,2.63) mm for the left femurs and (1.55,5.92,2.63) mm for the right femurs, on average. The angular range of the drilling path was 39.99±29.58 degrees in the SI direction and 46.18±40.73 degrees in the AP direction.

CONCLUSION

This study develops a framework that allows for automatic planning and geometric analysis of the drilling path in core decompression surgery. The target point of the drilling path primarily resides in the lateral-anterior-superior region relative to the femoral head center. Surgeons and researchers can benefit from our unified framework while still maintaining the flexibility to adapt to variations in surgical cases.

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.

Comparison of curative effect between OBS assisted by 3D printing and PFNA in the treatment of AO/OTA type 31-A3 femoral intertrochanteric fractures in elderly patients

Objective

To compare and analyze the Ortho-Bridge System (OBS) clinical efficacy assisted by 3D printing and proximal femoral nail anti-rotation (PFNA) of AO/OTA type 31-A3 femoral intertrochanteric fractures in elderly patients.

Methods

A retrospective analysis of 25 elderly patients diagnosed with AO/OTA type 31-A3 femoral intertrochanteric fracture was conducted from January 2020 to August 2022 at Yan'an Hospital, affiliated to Kunming Medical University. The patients were divided into 10 patients in the OBS group and 15 in the PFNA group according to different surgical methods. The OBS group reconstructed the bone models and designed the guide plate by computer before the operation, imported the data of the guide plate and bone models into a stereolithography apparatus (SLA) 3D printer, and printed them using photosensitive resin, thus obtaining the physical object, then simulating the operation and finally applying the guide plate to assist OBS to complete the operation; the PFNA group was treated by proximal femoral nail anti-rotation. The operation time, the intraoperative blood loss, Harris hip score (HHS), Oxford Hip Score (OHS), and complications were compared between the two groups.

Results

The operation time and the intraoperative blood loss in the PFNA group were less than that in the OBS group, and there was a significant difference between the two groups (P < 0.05). The HHS during the 6th month using OBS was statistically higher than PFNA (P < 0.05), however, there were no significant differences in OHS during the 6th month between the OBS group and PFNA group (P > 0.05). The HHS and OHS during the 12th month in the OBS group were statistically better than in the PFNA group (P < 0.05).

Conclusion

The OBS assisted by 3D printing and PFNA are effective measures for treating intertrochanteric fractures. Prior to making any decisions regarding internal fixation, it is crucial to evaluate the distinct circumstances of each patient thoroughly.

Core decompression with β-tri-calcium phosphate grafts in combination with platelet-rich plasma for the treatment of avascular necrosis of femoral head

BACKGROUND

This study was aimed to investigate whether the application of platelet-rich plasma (PRP) combined with β-tri-calcium phosphate (β-TCP) grafts after core decompression (CD) could improve the clinical outcomes of early stage of avascular necrosis of femoral head.

METHODS

Forty-five (54 hips) patients with Ficat-Arlet classification stage I-II treated by CD with β-TCP grafts with or without the application of PRP from July 2015 to October 2020 were reviewed. Group A (CD + β-TCP grafts) included 24 patients (29 hips), while group B (CD + β-TCP grafts + PRP) included 21 patients (25 hips). Visual analogue scale (VAS) score, Harris hip score (HHS), change in modified Kerboul angle and the hip joint survival were evaluated and compared between the groups. Patients had a mean follow-up period of 62.1 ± 17.2 months and 59.3 ± 14.8 months in group A and group B, respectively.

RESULTS

The mean VAS scores in group A was significantly higher than group B at the 6 months (2.9 ± 0.7 vs 1.9 ± 0.6, p < 0.01) and final follow up postoperative (2.8 ± 1.2 vs 2.2 ± 0.7, p = 0.04). The mean HHS in group A was significantly lower than group B at the 6 months (80.5 ± 13.8 vs 89.8 ± 12.8, p = 0.02). However, at the final follow up, there is no significant difference between the groups (77.0 ± 12.4 vs 83.1 ± 9.3, p = 0.07). The mean change in modified Kerboul angle was -7.4 ± 10.6 in group A and -19.9 ± 13.9 in group B which is statistically significant (p < 0.01). Survivorship from total hip arthroplasty were 86.2%/84% (p = 0.86) at the final follow up, which was not statistically significant. No serious complications were found in both groups.

CONCLUSIONS

A single dose of PRP combined with CD and β-TCP grafts provided significant pain relief, better functional outcomes, and delayed progression in the short term compared to CD combined with β-TCP grafts. However, the prognosis of the femoral head did not improve significantly in the long term. In the future, designing new implants to achieve multiple PRP injections may improve the hip preservation rate.

Towards Visualizing Early-stage Osteonecrosis using Intraoperative Imaging Modalities

Osteonecrosis of the Femoral Head (ONFH) is a progressive disease characterized by the death of bone cells due to the loss of blood supply. Early detection and treatment of this disease are vital in avoiding Total Hip Replacement. Early stages of ONFH can be diagnosed using Magnetic Resonance Imaging (MRI), commonly used intra-operative imaging modalities such as fluoroscopy frequently fail to depict the lesion. Therefore, increasing the difficulty of intra-operative localization of osteonecrosis. This work introduces a novel framework that enables the localization of necrotic lesions in Computed Tomography (CT) as a step toward localizing and visualizing necrotic lesions in intra-operative images. The proposed framework uses Deep Learning algorithms to enable automatic segmentation of femur, pelvis, and necrotic lesions in MRI. An additional step performs semi-automatic segmentation of these anatomies, excluding the necrotic lesions, in CT. A final step performs pairwise registration of the corresponding anatomies, allowing for the localization and visualization of the necrosis in CT. To investigate the feasibility of integrating the proposed framework in the surgical workflow, we conducted experiments on MRIs and CTs containing early-stage ONFH. Our results indicate that the proposed framework is able to segment the anatomical structures of interest and accurately register the femurs and pelvis of the corresponding volumes, allowing for the visualization and localization of the ONFH in CT and generated X-rays, which could enable intra-operative visualization of the necrotic lesions for surgical procedures such as core decompression of the femur.

ACR Appropriateness Criteria® Osteonecrosis: 2022 Update

Osteonecrosis is defined as bone death due to inadequate vascular supply. It is sometimes also called "avascular necrosis" and "aseptic necrosis" when involving epiphysis, or "bone infarct" when involving metadiaphysis. Common sites include femoral head, humeral head, tibial metadiaphysis, femoral metadiaphysis, scaphoid, lunate, and talus. Osteonecrosis is thought to be a common condition most commonly affecting adults in third to fifth decades of life. Risk factors for osteonecrosis are numerous and include trauma, corticosteroid therapy, alcohol use, HIV, lymphoma/leukemia, blood dyscrasias, chemotherapy, radiation therapy, Gaucher disease, and Caisson disease. Epiphyseal osteonecrosis can lead to subchondral fracture and secondary osteoarthritis whereas metadiaphyseal cases do not, likely explaining their lack of long-term sequelae. Early diagnosis of osteonecrosis is important: 1) to exclude other causes of patient's pain and 2) to allow for possible early surgical prevention to prevent articular collapse and need for joint replacements. Imaging is also important for preoperative planning. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer-reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances in which peer-reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

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

BACKGROUND

The goal of stabilization of the femoral neck is to limit morbidity and mortality from fracture. Of three potential methods of fixation, (three percutaneous screws, the Synthes Femoral Neck System, and a dynamic hip screw), each requires guide wire positioning of the implant(s) in the femoral neck and head. Consistent and accurate positioning of these systems is paramount to reduce surgical times, stabilize fractures effectively, and reduce complications. To help expedite surgery and achieve ideal implant positioning in the geriatric population, we have developed and validated a surgical planning methodology using 3D modelling and printing technology.

METHODS

Using image processing software, 3D surgical models were generated placing guide wires in a virtual model of an osteoporotic proximal femur sawbone. Three unique drill guides were created to achieve the optimal position for implant placement for each of the three different implant systems, and the guides were 3D printed. Subsequently, a trauma fellowship trained orthopedic surgeon used the 3D printed guides to position 2.8 mm diameter drill bit tipped guide wires into five osteoporotic sawbones for each of the three systems (fifteen sawbones total). Computed Tomography (CT) scans were then taken of each of the sawbones with the implants in place. 3D model renderings of the CT scans were created using image processing techniques and the displacement and angular deviations at guide wire entry to the optimal sawbone model were measured.

RESULTS

Across all three percutaneous screw guide wires, the average displacement was 3.19 ± 0.12 mm and the average angular deviation was 4.10 ± 0.17^o. The Femoral Neck System guide wires had an average displacement of 1.59 ± 0.18 mm and average angular deviation of 2.81 ± 0.64^o. The Dynamic Hip Screw had an average displacement of 1.03 ± 0.19 mm and average angular deviation of 2.59 ± 0.39^o.

CONCLUSION

The use of custom 3D printed drill guides to assist with the positioning of guide wires proved to be accurate for each of the three types of surgical strategies. Guides which are used to place more than 1 guide wire may have lower positional accuracy, as the guide may shift during multiple wire insertions. We believe that personalized point of care drill guides provide an accurate intraoperative method for positioning implants into the femoral neck.

Comparison of the outcome of different bone grafts combined with modified core decompression for the treatment of ARCO II stage femoral head necrosis

PURPOSE

Treatment of ONFH at an early stage is a challenging issue. The modified minimally invasive core decompression combined with bone graft implantation remains controversial. This study aimed to compare the early-middle outcomes of four groups with different bone grafts.

METHODS

A total of 182 patients (192 hips) with ONFH at the ARCO II stage were randomly divided into four groups. The free fibular graft group (FFG), free vascularized fibular graft group (FVFG), autologous iliac bone group (ABG), and β-tricalcium bioceramics phosphate graft (β-TCPG) group. Each group was treated with the modified minimally invasive core decompression and bone graft implantation. The operation time and blood loss were recorded by the same observer. The clinical outcome was evaluated by the Harris Hip Score and VAS score (before, 14 days after surgery, and at the last follow-up). The radiographic progression of ONFH was evaluated at least 36 months of follow-up.

RESULTS

All cases were successful without any complications after the operation. The patients were followed up for 42 to 48 (44.62 ± 1.81) months. There were statistically significant differences among the four groups in operation time (F value = 1520.67; P < 0.01) and blood loss (F value = 5366.81; P < 0.01). The Harris Hip Score in each group was improved significantly from pre-operation to last follow-up (all P < 0.01). At the last follow-up, the difference in the Harris Hip Score in each group was not statistically significant (F value = 0.54; P = 0.984). The VAS scores in each group were decreased significantly from the pre-operation to14 days after surgery (all P < 0.01). At 14 days after surgery, the difference in the VAS score in each group was not statistically significant (F value = 0.64; P = 0.59). At the last follow-up, three hips collapsed on the femoral head in the FFG group, two in the FVFG group, two in the ABG group, and three in the β-TCPG group.

CONCLUSION

The four different bone graft implantation showed satisfactory early-middle outcomes. As compared to other bone grafts, the β-TCP bioceramics graft has the advantages of shorter operation time and lesser blood loss. It may be a choice as a bone graft for the treatment of ONFH at an early stage.

Aseptic Necrosis of Femoral Head - Clinical Study

Femoral head osteonecrosis is a disease characterized by the decrease of blood vascularization in the femoral head, which leads to death of the osteocytes, demineralization and resorption of bone spans, change of trabecular architecture, with the reduction of the bone mechanical resistance and collapse of the articular surface in the femoral head. Left untreated, the disease may have a rapid progression, leading to severe symptoms, with significant articular dysfunction, functional impotence and a serious impact on the patient’s quality of life. The prevalence of the disease is ever growing all over the world, affecting mainly people in their 30s, 40s or 50s. In the present study, we analyzed a number of 76 patients with femoral head osteonecrosis with severe symptoms that required a surgical treatment. There was observed that more than ¾ of the investigated patients were males, while 81.58% were younger than 60 years old. Among the identified risk factors, smoking came first, followed by alcohol intake, obesity and chronic administration of corticosteroids. A very high percentage of patients (84.21%) were diagnosed in stages III and IV of the disease.

Efficacy Evaluation of 3D Navigational Template for Salter Osteotomy of DDH in Children

Background

The aim of this study is to retrospectively evaluate the efficacy of 3D navigational template for Salter osteotomy of DDH in children.

Methods

Thirty-two consecutive patients with DDH who underwent Salter osteotomy were evaluated between July 2014 and August 2017, and they were divided into the conventional group (n = 16) and navigation template group (n = 16) according to different surgical methods. The corrective acetabular degrees, radiation exposure, and operation time were compared between the two groups.

Results

No nerve palsy or redislocation was reported in the navigation template group. Compared with the conventional group, the navigation template group had the advantages of more accurate acetabular degrees, less radiation exposure, and shorter operation time (P < 0.05). Meanwhile, the navigation template group achieved a better surgical outcome than the conventional group (McKay, P = 0.0293; Severin, P = 0.0949).

Conclusions

The 3D navigational template for Salter osteotomy of DDH is simple and effective, which could be an alternative approach to improve the Salter osteotomy accuracy and optimize the efficacy.

Endoscopic observation finding in the core decompression procedure of osteonecrosis of femoral head and effect of additional treatments

PURPOSE

To observe necrotic findings of the femoral head through the endoscopic examination when performing the decompression procedure widely used in the treatment of osteonecrosis of femoral head. To assess the efficacy of injection of bone marrow aspirated from the iliac crest and new vascularized bone graft into the core of femoral head based on the endoscopic findings.

METHODS

The first stage of osteonecrosis of femoral head based on ARCO classification includes 23, second stage 36, and third stage eight femoral heads. Bone marrow transplantations have been performed in 49 hip joints and new vascularized bone grafts in 18 hip joints.

RESULTS

The endoscopic findings of osteonecrosis of femoral heads are varied, and they can be divided into five categories. The average time in core decompression and bone marrow injection was 15 minutes, and the average time of new pedicled bone grafts was 65 minutes (45-90 minutes). The efficacy of bone marrow injection was 93.88%, and the efficacy of vascularized bone graft was 94.44% when performed based on the endoscopic findings.

CONCLUSION

It is possible to increase the treatment efficacy of the osteonecrosis of the femoral head when appropriate additional treatments are applied based on endoscopic findings in the decompression procedures of pre-collapse osteonecrosis of the femoral head.

Efficacy and safety of a novel personalized navigation template in proximal femoral corrective osteotomy for the treatment of DDH

Background

This present study is aimed to retrospectively evaluate the efficacy and safety of a novel personalized navigation template in proximal femoral corrective osteotomy for the treatment of DDH.

Methods

Twenty-nine consecutive patients with DDH who underwent proximal femoral corrective osteotomy were evaluated between August 2013 and June 2017. Based on the different surgical methods, they were divided into the conventional group (n = 14) and navigation template group (n = 15). The osteotomy degrees, radiation exposure, and operation time were compared between the two groups.

Results

No major complications relating to osteotomy surgery such as redislocation or avascular necrosis occurred in the navigation template group, which had more accurate osteotomy degrees, less radiation exposure, and shorter operation time when compared with the conventional group (P < 0.05). Moreover, there was significant difference according to the McKay criteria between the two groups (P = 0.0362).

Conclusions

The novel personalized navigation template in proximal femoral corrective osteotomy is effective and safe, which could improve the femoral osteotomy accuracy, reduce radiation exposure, and shorten operation time.

A Comparative Study of Patients' Subjective Feelings Toward Total Hip Arthroplasty with Patient-Specific Instruments and Traditional Total Hip Arthroplasty

OBJECTIVE

To determine whether differences exist in patients' subjective feelings, daily life, and surgical satisfaction between those who underwent surgery for developmental dysplasia of the hip (DDH) using patient-specific instruments (PSIs) and those who underwent traditional surgical total hip arthroplasty (THA).

METHODS

We selected 30 adult patients with various types of DDH who underwent surgery during 2016-2017 at our hospital. The patients were divided into PSI surgery group and the traditional surgery group. All patients underwent follow-up, and we collected data on the Harris Hip Score, Oxford University Hip Score (OHS), Forgotten Joint Score (FJS-12), Visual Analogue Scale (VAS) score, patient satisfaction score, intraoperative surgical time, amount of bleeding and postoperative complications incidence for both groups. We then performed statistical analyses on the data.

RESULTS

The Harris Hip Score, OHS, VAS score, patient satisfaction score, and mean bleeding volume did not differ statistically significantly (t-tests, P > 0.05). No statistically significant differences were found between surgical groups in the incidence of complication and sub-trochanteric osteotomy, or in the surgical side (chi-square tests, P > 0.05). For the experimental group, the FJS-12 score was 80.0 ± 12.0, and for the control group the score was 68.5 ± 16.1. The operative time of the experimental group was 138.4 ± 32.2 min, while that of the control group was 88.9 ± 26.8 min. The values of these data differed significantly (t-tests, P < 0.05).

CONCLUSIONS

The novel PSI designed by our group has certain advantages for the short-term subjective feelings of patients after THA, but it may cause prolonged operative times.

Three-dimensional printing in orthopaedic surgery: a scoping review

Three-dimensional printing (3DP) has become more frequently used in surgical specialties in recent years. These uses include pre-operative planning, patient-specific instrumentation (PSI), and patient-specific implant production.The purpose of this review was to understand the current uses of 3DP in orthopaedic surgery, the geographical and temporal trends of its use, and its impact on peri-operative outcomesOne-hundred and eight studies (N = 2328) were included, published between 2012 and 2018, with over half based in China.The most commonly used material was titanium.Three-dimensional printing was most commonly reported in trauma (N = 41) and oncology (N = 22). Pre-operative planning was the most common use of 3DP (N = 63), followed by final implants (N = 32) and PSI (N = 22).Take-home message: Overall, 3DP is becoming more common in orthopaedic surgery, with wide range of uses, particularly in complex cases. 3DP may also confer some important peri-operative benefits. Cite this article: EFORT Open Rev 2020;5:430-441. DOI: 10.1302/2058-5241.5.190024.

Mixed Reality Combined with Three-Dimensional Printing Technology in Total Hip Arthroplasty: An Updated Review with a Preliminary Case Presentation

Three-dimensional (3D) printing technology, virtual reality, and augmented reality technology have been used to help surgeons to complete complex total hip arthroplasty, while their respective shortcomings limit their further application. With the development of technology, mixed reality (MR) technology has been applied to improve the success rate of complicated hip arthroplasty because of its unique advantages. We presented a case of a 59-year-old man with an intertrochanteric fracture in the left femur, who had received a prior left hip fusion. After admission to our hospital, a left total hip arthroplasty was performed on the patient using a combination of MR technology and 3D printing technology. Before surgery, 3D reconstruction of a certain bony landmark exposed in the surgical area was first performed. Then a veneer part was designed according to the bony landmark and connected to a reference registration landmark outside the body through a connecting rod. After that, the series of parts were made into a holistic reference registration instrument using 3D printing technology, and the patient's data for bone and surrounding tissue, along with digital 3D information of the reference registration instrument, were imported into the head-mounted display (HMD). During the operation, the disinfected reference registration instrument was installed on the selected bony landmark, and then the automatic real-time registration was realized by HMD through recognizing the registration landmark on the reference registration instrument, whereby the patient's virtual bone and other anatomical structures were quickly and accurately superimposed on the real body of the patient. To the best of our knowledge, this is the first report to use MR combined with 3D printing technology in total hip arthroplasty.

Three-dimensional-printing Technology in Hip and Pelvic Surgery: Current Landscape

The use of three-dimensional (3D) printing is becoming more common, including in the field of orthopaedic surgery. There are currently four primary clinical applications for 3D-printing in hip and pelvic surgeries: (i) 3D-printed anatomical models for planning and surgery simulation, (ii) patient-specific instruments (PSI), (iii) generation of prostheses with 3D-additive manufacturing, and (iv) custom 3D-printed prostheses. Simulation surgery using a 3D-printed bone model allows surgeons to develop better surgical approaches, test the feasibility of procedures and determine optimal location and size for a prosthesis. PSI will help inform accurate bone cuts and prosthesis placement during surgery. Using 3D-additive manufacturing, especially with a trabecular pattern, is possible to produce a prosthesis mechanically stable and biocompatible prosthesis capable of promoting osseointergration. Custom implants are useful in patients with massive acetabular bone loss or periacetabular malignant bone tumors as they may improve the fit between implants and patient-specific anatomy. 3D-printing technology can improve surgical efficiency, shorten operation times and reduce exposure to radiation. This technology also offers new potential for treating complex hip joint diseases. Orthopaedic surgeons should develop guidelines to outline the most effective uses of 3D-printing technology to maximize patient benefits.

Efficacy evaluation of three-dimensional printing assisted osteotomy guide plate in accurate osteotomy of adolescent cubitus varus deformity

BACKGROUND

This present study is aimed to retrospectively assess the efficacy of three-dimensional (3D) printing assisted osteotomy guide plate in accurate osteotomy of adolescent cubitus varus deformity.

MATERIAL AND METHODS

Twenty-five patients (15 males and 10 females) with the cubitus varus deformity from June 2014 to December 2017 were included in this study and were enrolled into the conventional group (n = 11) and 3D printing group (n = 14) according to the different surgical approaches. The operation time, intraoperative blood loss, osteotomy degrees, osteotomy end union time, and postoperative complications between the two groups were observed and recorded.

RESULTS

Compared with the conventional group, the 3D printing group has the advantages of shorter operation time, less intraoperative blood loss, higher rate of excellent correction, and higher rate of the parents' excellent satisfaction with appearance after deformity correction (P < 0.001, P < 0.001, P = 0.019, P = 0.023). Nevertheless, no significant difference was presented in postoperative carrying angle of the deformed side and total complication rate between the two groups (P = 0.626, P = 0.371).

CONCLUSIONS

The operation assisted by 3D printing osteotomy guide plate to correct the adolescent cubitus varus deformity is feasible and effective, which might be an optional approach to promote the accurate osteotomy and optimize the efficacy.

Clinical Applications of 3-Dimensional Printing Technology in Hip Joint

Three‐dimensional (3D) printing is a digital rapid prototyping technology based on a discrete and heap‐forming principle. We identified 53 articles from PubMed by searching “Hip” and “Printing, Three‐Dimensional”; 52 of the articles were published from 2015 onwards and were, therefore, initially considered and discussed. Clinical application of the 3D printing technique in the hip joint mainly includes three aspects: a 3D‐printed bony 1:1 scale model, a custom prosthesis, and patient‐specific instruments (PSI). Compared with 2‐dimensional image, the shape of bone can be obtained more directly from a 1:1 scale model, which may be beneficial for preoperative evaluation and surgical planning. Custom prostheses can be devised on the basis of radiological images, to not only eliminate the fissure between the prosthesis and the patient's bone but also potentially resulting in the 3D‐printed prosthesis functioning better. As an alternative support to intraoperative computer navigation, PSI can anchor to a specially appointed position on the patient's bone to make accurate bone cuts during surgery following a precise design preoperatively. The 3D printing technique could improve the surgeon's efficiency in the operating room, shorten operative times, and reduce exposure to radiation. Well known for its customization, 3D printing technology presents new potential for treating complex hip joint disease.

Long-term follow-up of custom cross-pin fixation of 56 tumour endoprosthesis stems: a single-institution experience

AIMS

Aseptic loosening is a major cause of failure in cemented endoprosthetic reconstructions. This paper presents the long-term outcomes of a custom-designed cross-pin fixation construct designed to minimize rotational stress and subsequent aseptic loosening in selected patients. The paper will also examine the long-term survivorship and modes of failure when using this technique.

PATIENTS AND METHODS

A review of 658 consecutive, prospectively collected cemented endoprosthetic reconstructions for oncological diagnoses at a single centre between 1980 and 2017 was performed. A total of 51 patients were identified with 56 endoprosthetic implants with cross-pin fixation, 21 of which were implanted following primary resection of tumour. Locations included distal femoral (n = 36), proximal femoral (n = 7), intercalary (n = 6), proximal humeral (n = 3), proximal tibial (n = 3), and distal humeral (n = 1).

RESULTS

The median follow-up was 132 months (interquartile range (IQR) 44 to 189). In all, 20 stems required revision: eight for infection, five for structural failure, five for aseptic loosening, and two for tumour progression. Mechanical survivorship at five, ten, and 15 years was 84%, 78%, and 78%, respectively. Mechanical failure rate varied by location, with no mechanical failures of proximal femoral constructs and distal femoral survivorship of 82%, 77%, and 77% at five, ten, and 15 years. The survivorship of primary constructs at five years was 74%, with no failure after 40 months, while the survivorship for revision constructs was 89%, 80%, and 80% at five, ten, and 15 years.

CONCLUSION

The rate of mechanical survivorship in our series is similar to those reported for other methods of reconstruction for short diaphyseal segments, such as compressive osseointegration. The mechanical failure rate differed by location, while there was no substantial difference in long-term survival between primary and revision reconstructions. Overall, custom cross-pin fixation is a viable option for endoprosthetic reconstruction of short metaphyseal segments with an acceptable rate of mechanical failure. Cite this article: Bone Joint J 2019;101-B:724-731.

Modified trapdoor procedures by surgical dislocation approach to treat chondroblastoma of the femoral head

AIMS

The aim of this study was to evaluate the efficacy of the surgical dislocation approach and modified trapdoor procedure for the treatment of chondroblastoma of the femoral head.

PATIENTS AND METHODS

A total of 17 patients (ten boys, seven girls; mean age 16.4 years (11 to 26)) diagnosed with chondroblastoma of the femoral head who underwent surgical dislocation of the hip joint, modified trapdoor procedure, curettage, and bone grafting were enrolled in this study and were followed-up for a mean of 35.9 months (12 to 76). Healing and any local recurrence were assessed via clinical and radiological tests. Functional outcome was evaluated using the Musculoskeletal Tumour Society scoring system (MSTS). Patterns of bone destruction were evaluated using the Lodwick classification. Secondary osteoarthritis was classified via radiological analysis following the Kellgren-Lawrence grading system. Steinberg classification was used to evaluate osteonecrosis of the femoral head.

RESULTS

The epiphyseal plate was open, closing, and closed in five, five, and seven patients, respectively. In total, eight, six, and three patients were classified as having Lodwick classification IA, IB, and IC, respectively. Allogeneic and autogenous bone grafting was used in 13 and four patients, respectively. All patients had good bone healing and no local recurrence was observed. One patient developed osteonecrosis of the femoral head (Steinberg IA) and one developed secondary osteoarthritis of the hip joint (Kellgren-Lawrence Grade II). The mean postoperative MSTS functional score was 27.7 (24 to 30).

CONCLUSION

Surgical dislocation and modified trapdoor procedures are safe and effective techniques for treating chondroblastoma in the femoral head. Cite this article: Bone Joint J 2019;101-B:732-738.