Postoperative accuracy analysis of three-dimensional corrective osteotomy for cubitus varus deformity with a custom-made surgical guide based on computer simulation

Step-cut osteotomy for cubitus varus deformity with application of patient-specific instrument in children: a preliminary report

PURPOSE

The step-cut osteotomy has been recognized as a valuable approach for addressing cubitus varus deformity, albeit one that necessitates technical proficiency. This study aims to evaluate the efficacy of the modified step-cut osteotomy technique in conjunction with patient-specific instruments by clinical and radiological assessment.

METHODS

We conducted a retrospective review of patients who underwent modified step-cut osteotomy with the use of patient-specific instruments in conjunction with Kirschner wires fixation for the correction of cubitus varus deformity between April 2016 and April 2022. Follow-up was performed for a minimum of two years, during which pre-operative and post-operative clinical and radiological parameters were compared.

RESULTS

Fifteen patients were enrolled in this study. The mean pre-operative humeral-elbow-wrist (HEW) of the affected side was -21.7° (ranging from -14° to -34°), while the normal side was 9.4° (ranging from 5° to 15°). The post-operation HEW of affected side was 9° (ranging from 4° to 16°). There was no significant difference between the normal side and affected side after operation (p = 0.74). Pre-operative range of motion in the affected side was 130°, while the post-operative range of motion was 132°. Fourteen patients (93.3%) were pleased with the overall appearance of their elbow. None lazy-S deformity was observed in these cases. There were no major complications.

CONCLUSION

The modified step-cut osteotomy technique, utilizing patient-specific instrument in conjunction with Kirschner wires fixation was found to be a safe, reliable, and technically easy procedure for correcting cubitus varus deformity.

A systematic review of the operative techniques for treating cubitus varus deformity in children

A systematic review of the operative techniques for treating cubitus varus deformity in children was performed using research databases including PubMed and Embase. Outcome measurements included mean angular correction of the humerus-elbow-wrist angle, complications, revisions and outcome scores. A total of 45 papers and 911 patients were included. Lateral closing wedge osteotomy (LCWO) (427 patients) was the most common procedure and 5.56% of these patients experienced lateral condylar prominence. This technique had the highest revision rate at 3%. The step-cut osteotomy (111 patients) yielded zero postoperative infections or loss of motion. Distraction osteogenesis (92 patients) was the least common technique. Superficial pin tract infections occurred in 18% of patients and 88.04% of patients reported excellent results, the highest of any technique in this study. The infection rate of dome osteotomy (151 patients) was 9.45% and 4.72% of patients experienced loss of motion. 3D osteotomy (130 patients) had no infections, 87.78% of patients reported excellent outcomes, and 2.22% of patients reported poor outcomes, the lowest of all techniques. For unidimensional correction, LCWO provides a technically simple procedure and reasonable outcomes. Step-cut osteotomy has less lateral condylar prominence but is more complicated than LCWO. Distraction osteogenesis is a minimally invasive alternative to LCWO and step-cut osteotomy, but it has more superficial infections and can be bothersome to patients. For a multidimensional correction, 3D osteotomy is superior to dome osteotomy due to its lower infection rate and higher rate of functionally excellent outcomes.

A Modified Reverse Right-angled Triangle Osteotomy Using the Lateral Approach for the Treatment of Posttraumatic Cubitus Varus Deformity in Children

BACKGROUND

Cubitus varus deformity is a complex 3-dimensional deformity. Various osteotomies have been introduced to correct this deformity, however, there is no consensus on the best procedure to correct the deformity while avoiding complications. In this retrospective study, we used a modified inverse right-angled triangle osteotomy to treat 22 children with posttraumatic cubitus varus deformity. The primary objective was to evaluate this technique by presenting its clinical and radiologic results.

METHODS

Twenty-two consecutive patients with a cubitus varus deformity underwent a modified reverse right-angled triangle osteotomy between October 2017 and May 2020 and were then followed for a minimum of 24 months. We evaluated its clinical and radiologic results. Functional outcomes were assessed using Oppenheim criteria.

RESULTS

The average follow-up period was 34.6 months (range, 24.0 to 58.1 months). The mean range of motion was 4.32 degrees (range, 0 degrees to 15 degrees)/122.73 degrees (range, 115 degrees to 130 degrees) (hyperextension/flexion) before surgery and 2.05 degrees (range, 0 degrees to 10 degrees)/127.27 degrees (range, 120 degrees to 145 degrees) at the final follow-up. There were significant ( P < 0.05) differences between the flexion and hyperextension angles before surgery and at the final follow-up. Based on Oppenheim criteria, results were excellent for 20, good for 2, and none of the patients had poor results. The mean humerus-elbow-wrist angle improved from 18.23 degrees (range, 10 degrees to 25 degrees) varus preoperatively to 8.45 degrees (range, 5 degrees to 15 degrees) valgus postoperatively ( P < 0.05). The mean of the preoperative lateral condylar prominence index was 3.52 (range, 2.5 to 5.2) and the average postoperative lateral condylar prominence index was -3.28 (range, -1.3 to -6.0). All patients were pleased with the overall appearance of their elbows.

CONCLUSIONS

The modified reverse right-angled triangle osteotomy can precisely and stably correct the deformity in the coronal and sagittal planes, we recommend this technique as a simple, safe, and reliable correction of cubitus varus deformity.

LEVEL OF EVIDENCE

Level IV; case series; therapeutic studies-investigating the results of treatment.

Guided Growth for the Treatment of Cubitus Varus in Children: Medium- to Long-Term Results

Correction of cubitus varus is commonly attempted through supracondylar humeral osteotomy. We hypothesized that lateral distal humeral hemiepiphysiodesis (LDHH) could be used to gradually correct this deformity in children. We conducted a retrospective study including all patients who underwent LDHH with the eight-Plate system between 2008 and 2018, with a minimum 4-year follow-up. We collected demographic, fracture-related, pre- and postoperative clinical (carrying angle (CA), ROM), and radiological data (humeral-ulnar angle (HUA), Baumann angle (BA), shaft-condylar angle (SCA), lateral capitellohumeral angle (LCHA)), as well as data on complications and satisfaction at last follow-up. Fifteen patients were included, with a median follow-up of 81 (64–103) months. All the variables had improved significantly as follows: CA −16 (−18 to −9)°, HUA −16 (−19 to −12)°, BA −11 (−17 to −7)°, SCA 7.5 (3.3 to 13.8)°, LCHA −4.8 (−6.8 to 0.6), flexion 10 (0 to 24)°, and extension 10 (0 to 10)°. The annual correction rate in terms of HUA was 2.41° (1.9 to 3.2). There were 5 cases of aseptic screw loosening, 4 of them requiring replacement, without relation to age at surgery (p = 0.324). Most patients (86.67%) were satisfied, and a relationship was found with younger age at surgery (p = 0.037). In conclusion, preliminary results show that LDHH with the eight-Plate system is an effective technique for mild to moderate cubitus varus deformity correction in children. Patients should be advised of the relatively long duration of implant retention and the possibility of reoperation for screw replacement or implant removal.

A novel method of lateral closing wedge osteotomy for cubitus varus deformity in children

BACKGROUND

Humeral osteotomy is the best method for treatment of severe cubitus varus in children. Many osteotomy methods have been developed in the past. In this study, we describe a novel corrective technique by applying the principles described by Paley involving lateral osteotomy using Kirschner wires (K-wires). Vertices of the osteotomy should be located at the center of rotation of angulation. The anatomical and mechanical axes can be corrected with precision.

PATIENTS AND METHODS

In this retrospective study, 21 patients (17 male, 4 female) who fulfilled the study criteria and underwent lateral closing osteotomy for cubitus varus deformity from July 2015 to October 2017 were included into the study. The osteotomy line of all patients was designed according to Paley's principles. An isosceles triangle template was made according to the design preoperatively. The lateral osteotomy was made with the assistance of C-arm radiographs. The osteotomy was fixed by K-wires laterally. Patients were followed up, and elbows were evaluated by radiography and using the Mayo Elbow Performance Index (MEPI) score.

RESULTS

The mean correction angle obtained was 32.33°±2.83°. According to the MEPI score assessment, 19 of the 21 patients had an excellent outcome and two had a good outcome. Two patients complained of conspicuous scars; however, no further cosmetic surgery was performed. The range of motion was 135.0° preoperatively and 133.7° postoperatively, showing no significant difference (p = 0.326). None showed evidence of neurovascular injury or complained of prominence of the lateral humerus.

CONCLUSION

Paley's principles for correcting cubitus varus deformity in children are effective and reliable for treating such a condition.

LEVEL OF EVIDENCE

Therapeutic IV.

3D accuracy and clinical outcomes of corrective osteotomies with patient-specific instruments in complex upper extremity deformities: an approach for investigation and correlation

Background

Corrective osteotomies of the upper extremities with patient-specific instruments (PSIs) are increasingly used. In this context, the concordance between planning and postoperative 3D radiographs as well as the association between 3D accuracy and clinical outcome has rarely been evaluated. In this pilot study, we aimed to investigate our clinical mid-term outcome and 3D accuracy as well as their possible correlation, including identifying aspects critical to reaching optimal correction results.

Methods

From October 2018 to January 2020, we used PSIs for 12 corrective osteotomies of the upper extremity in 11 bones of 8 patients (congenital or posttraumatic deformities in 2 elbows, 3 forearms, 3 distal radii). In follow-up examination (10–25 months postoperatively), patient satisfaction, grip strength, ROM, VAS, and DASH were evaluated. Three-dimensional radiological accuracy was determined with 3D-reconstructed postoperative CT scans. With the software tool “Part Comparison” of Mimics^® Innovation Suite Software/Materialise, surface differences of pre-planned and postoperative 3D models were compared.

Results

Compared to the preoperative situation pain and function were better at follow-up: The average VAS score significantly decreased from 6.5 ± 4.1 cm preoperatively to 2.3 ± 2.6 cm at the follow-up time point (p = 0.008). The average DASH score significantly improved, from 48.4 ± 30.9 to 27.0 ± 25.2 (p = 0.015). In the part comparison analysis “planned vs postoperative comparison”, significantly more points in percent (= 3D accuracy) were in a −3 mm to 3 mm interval than in the “preoperative vs planned comparison” (87.3 ± 13.8% vs 48.9 ± 16.6%, p = 0.004). After surgery, the maximum deviation value over all cases was 4.5 ± 1.1 mm, and the minimum deviation value was − 4.5 ± 1.2 mm vs preoperatively 12.9 ± 6.2 mm (p = 0.004) and − 7.2 ± 2.1 mm (p = 0.02), respectively. Clinically, in all cases with higher accuracy (> 90%), an improvement of either DASH or VAS or both of > 60% to the preoperative values occurred. There was a significant correlation between accuracy (%) and ΔVAS (p = 0.004). There were no method-related complications.

Conclusions

Our data after PSI-based corrective osteotomy in complex deformities of the upper extremity in a limited number of cases indicate a positive correlation between 3D accuracy and clinical outcomes. Examination of 3D accuracy to analyse sources of error in the hole procedure from initial CT scan to end of surgery even in patients with not fully satisfactory clinical results is required for further development of the method to achieve optimal correction results with nearly 100% congruence between the planned and postoperative 3D bone position.

Trial registration This retrospective study was registered in the Center for Translational & Clinical Research Aachen (CTC-A) with the number 20-514 on November 20, 2021

Computer-Aided Planning and 3D-Printed Surgical Guide in Patients with Extreme Cubitus Varus Deformity: A Report of 2 Cases

CASE

We describe 2 patients with extreme triplanar cubitus varus deformity, treated with step-cut corrective virtually planned osteotomies and performed with custom-made surgical guides. The surgery was simulated on the patients' bone 3D-printed model to verify the effectiveness of the surgical plans. At a medium 21-month follow-up after surgery, in both patients, clinical and radiological results were fully satisfactory, and no complications have been reported.

CONCLUSION

The precision of computer-aided surgical planning and custom-made surgical guides allow to perform reproducible and relatively safe surgeries even in extreme deformities where the surgical complexity could discourage attempts at surgical correction.

A Two-Step Approach for 3D-Guided Patient-Specific Corrective Limb Osteotomies

Background: Corrective osteotomy surgery for long bone anomalies can be very challenging since deformation of the bone is often present in three dimensions. We developed a two-step approach for 3D-planned corrective osteotomies which consists of a cutting and reposition guide in combination with a conventional osteosynthesis plate. This study aimed to assess accuracy of the achieved corrections using this two-step technique. Methods: All patients (≥12 years) treated for post-traumatic malunion with a two-step 3D-planned corrective osteotomy within our center in 2021 were prospectively included. Three-dimensional virtual models of the planned outcome and the clinically achieved outcome were obtained and aligned. Postoperative evaluation of the accuracy of performed corrections was assessed by measuring the preoperative and postoperative alignment error in terms of angulation, rotation and translation. Results: A total of 10 patients were included. All corrective osteotomies were performed according to the predetermined surgical plan without any complications. The preoperative deformities ranged from 7.1 to 27.5° in terms of angulation and 5.3 to 26.1° in terms of rotation. The achieved alignment deviated on average 2.1 ± 1.0 and 3.4 ± 1.6 degrees from the planning for the angulation and rotation, respectively. Conclusions: A two-step approach for 3D-guided patient-specific corrective limb osteotomies is reliable, feasible and accurate.

Clinical applications and prospects of 3D printing guide templates in orthopaedics

Background

With increasing requirements for medical effects, and huge differences among individuals, traditional surgical instruments are difficult to meet the patients' growing medical demands. 3D printing is increasingly mature, which connects to medical services critically as well. The patient specific surgical guide plate provides the condition for precision medicine in orthopaedics.

Methods

In this paper, a systematic review of the orthopedic guide template is presented, where the history of 3D-printing-guided technology, the process of guides, and basic clinical applications of orthopedic guide templates are described. Finally, the limitations of the template and possible future directions are discussed.

Results

The technology of 3D printing surgical templates is increasingly mature, standard, and intelligent. With the help of guide templates, the surgeon can easily determine the direction and depth of the screw path, and choose the angle and range of osteotomy, increasing the precision, safety, and reliability of the procedure in various types of surgeries. It simplifies the difficult surgical steps and accelerates the growth of young and mid-career physicians. But some problems such as cost, materials, and equipment limit its development.

Conclusions

In different fields of orthopedics, the use of guide templates can significantly improve surgical accuracy, shorten the surgical time, and reduce intraoperative bleeding and radiation. With the development of 3D printing, the guide template will be standardized and simplified from design to production and use. 3D printing guides will be further sublimated in the application of orthopedics and better serve the patients.

The translational potential of this paper

Precision, intelligence, and individuation are the future development direction of orthopedics. It is more and more popular as the price of printers falls and materials are developed. In addition, the technology of meta-universe, digital twin, and artificial intelligence have made revolutionary effects on template guides. We aim to summarize recent developments and applications of 3D printing guide templates for engineers and surgeons to develop more accurate and efficient templates.

3D-printed model and osteotomy template technique compared with conventional closing-wedge osteotomy in cubitus varus deformity

Cubitus varus deformity is the most common late complication of malunited supracondylar fracture that requires corrective osteotomy and fixation. From 2009 to 2017, 40 consecutive patients with cubitus varus deformity were included. Twenty patients underwent the conventional closing-wedge osteotomy (conventional group), while the other twenty patients underwent the 3D-printed model and osteotomy template osteotomy (3D-printed template group). The functional outcome was evaluated using the Mayo Elbow Performance Index (MEPI) Score and Flynn criteria. There were no statistically significant differences were observed regarding the humerus-elbow-wrist angle and tilting angle between the two groups, both preoperatively and postoperatively at 24 months. No statistically significant differences were observed regarding the elbow ROM (127.0 ± 4.7° VS 128.9 ± 3.8°) and MEPI score (93.5 ± 3.3 VS 94.3 ± 4.1) between the groups. All patients were satisfied both cosmetically and functionally as per the Flynn criteria and MEPI score. The conventional osteotomy and 3D-printed model and osteotomy template techniques both met the treatment requirements of cubitus varus deformity. The 3D-printed template technique showed better osteotomy accuracy, but no significant advantage regarding the functional and cosmetic results than conventional osteotomy.

Application of Patient-Specific Instrumentation in a Dog Model with Antebrachial Growth Deformity Using a 3-D Phantom Bone Model

One of the most frequent bone deformities in dogs is antebrachial growth deformity (AGD), which results from malunion of the distal growth plates. The objective of the present study was to re-align the limbs, which can correct the length mismatch and reset the coherence of the joint with the aid of a 3-D phantom model for surgical preplanning. A 14-month-old, intact female Golden Retriever with an angular deformity of the left radius and ulna was selected for the study. The diagnosis was confirmed by orthogonal radiographs. Moreover, computed tomography (CT) scans revealed a multiplane deformity with valgus, procurator, and external rotation of the left radius. The pre-surgical planning started with the quantification of the angular deformity, followed by a simulated virtual osteotomy, and concluded with an in vitro rehearsal surgery on 3-D printed phantom bone models. In the operating room, prefabricated patient-specific instrumentation (PSI) was attached at the planned site of the radial bone surface for a precise closing wedge osteotomy. Then two locking plates were fixed routinely. Post-operative radiographs showed accurate correction of the deformity as we had planned. At 12 weeks post-operatively, the follow-up surveys revealed improved gait, weight-bearing, and progression of bone healing. Our PSI design, based on novel surgical planning, was steady yet straightforward during the osteotomy. The osteotomy was performed without difficulty since the PSI that pre-determined the sites and angles let the surgeon perform the antebrachial malformation surgery. This method of operation reduces stress on the operator and helps to improve accuracy, repeatability, and surgery time.

Comparison in clinical performance of surgical guides for mandibular surgery and temporomandibular joint implants fabricated by additive manufacturing techniques

Additive manufacturing (AM) offers great design freedom that enables objects with desired unique and complex geometry and topology to be readily and cost-effectively fabricated. The overall benefits of AM are well known, such as increased material and resource efficiency, enhanced design and production flexibility, the ability to create porous structures and on-demand manufacturing. When AM is applied to medical devices, these benefits are naturally assumed. However, hard clinical evidence collected from clinical trials and studies seems to be lacking and, as a result, systematic assessment is yet difficult. In the present work, we have reviewed 23 studies on the clinical use of AM patient-specific surgical guides (PSGs) for the mandible surgeries (n = 17) and temporomandibular joint (TMJ) patient-specific implants (PSIs) (n = 6) with respect to expected clinical outcomes. It is concluded that the data published on these AM medical devices are often lacking in comprehensive evaluation of clinical outcomes. A complete set of clinical data, including those on time management, costs, clinical outcomes, range of motion, accuracy of the placement with respect to the pre-operative planning, and extra complications, as well as manufacturing data are needed to demonstrate the real benefits gained from applying AM to these medical devices and to satisfy regulatory requirements.

Inter-rater variability of three-dimensional fracture reduction planning according to the educational background

Background

Computer-assisted three-dimensional (3D) planning is increasingly delegated to biomedical engineers. So far, the described fracture reduction approaches rely strongly on the performance of the users. The goal of our study was to analyze the influence of the two different professional backgrounds (technical and medical) and skill levels regarding the reliability of the proposed planning method. Finally, a new fragment displacement measurement method was introduced due to the lack of consistent methods in the literature.

Methods

3D bone models of 20 distal radius fractures were presented to nine raters with different educational backgrounds (medical and technical) and various levels of experience in 3D operation planning (0 to 10 years) and clinical experience (1.5 to 24 years). Each rater was asked to perform the fracture reduction on 3D planning software.

Results

No difference was demonstrated in reduction accuracy regarding rotational (p = 1.000) and translational (p = 0.263) misalignment of the fragments between biomedical engineers and senior orthopedic residents. However, a significantly more accurate planning was performed in these two groups compared with junior orthopedic residents with less clinical experience and no 3D planning experience (p < 0.05).

Conclusion

Experience in 3D operation planning and clinical experience are relevant factors to plan an intra-articular fragment reduction of the distal radius. However, no difference was observed regarding the educational background (medical vs. technical) between biomedical engineers and senior orthopedic residents. Therefore, our results support the further development of computer-assisted surgery planning by biomedical engineers. Additionally, the introduced fragment displacement measure proves to be a feasible and reliable method.

Level of Evidence

Diagnostic Level II

Corrective Osteotomy of Upper Extremity Malunions Using Three-Dimensional Planning and Patient-Specific Surgical Guides: Recent Advances and Perspectives

Malunions of the upper extremity can result in severe functional problems and increase the risk of osteoarthritis. The surgical reconstruction of complex malunions can be technically challenging. Recent advances in computer-assisted orthopedic surgery provide an innovative solution for complex three-dimensional (3-D) reconstructions. This study aims to evaluate the clinical applicability of 3-D computer-assisted planning and surgery for upper extremity malunions. Hence, we provide a summary of evidence on this topic and highlight recent advances in this field. Further, we provide a practical implementation of this therapeutic approach based on three cases of malunited forearm fractures treated with corrective osteotomy using preoperative three-dimensional simulation and patient-specific surgical guides. All three cases, one female (56 years old) and two males (18 and 26 years old), had painful restrictions in range of motion (ROM) due to forearm malunions and took part in clinical and radiologic assessments. Postoperative evaluation of patient outcomes showed a substantial increase in range of motion, reduction of preoperatively reported pain, and an overall improvement of patients' satisfaction. The therapeutic approach used in these cases resulted in an excellent anatomical and functional reconstruction and was assessed as precise, safe, and reliable. Based on current evidence and our results, the 3-D preoperative planning technique could be the new gold standard in the treatment of complex upper extremity malunions in the future.

A modified rotating isosceles triangle osteotomy using a 3D-printed patient-specific guide for the treatment of cubitus varus in children: a case report and literature review

After corrective osteotomy of cubitus varus, the lateral condylar prominence is a common problem, which is believed to be due to the unequal relative cuts of the lateral base wedge osteotomy. Therefore, several related solutions have been proposed, such as dome osteotomy and step-cut osteotomies, which solve the above problems to a certain extent. This study aimed to: (I) use a modified corpectomy to correct the deformity, and (II) present a new corpectomy method that uses a 3D-printed specific guide with an isosceles triangle osteotomy. A 12-year-old male presented with a -30-degree cubitus varus deformity 5 years after a supracondylar fracture of the right humerus. The degree of correction was determined from the varus angle and the normal carrying angle on the normal side. A rotating isosceles triangle osteotomy was determined by using Mimics software. The accuracy of the osteotomy angle was confirmed by postoperative radiography. The mean postoperative carrying angle was found to be preserved at the 10-month follow-up, with no complications. A rotating isosceles triangle osteotomy with a 3D-printed patient-specific guide may be providing a relative accurate result. However, in order to obtain more rigorous research conclusions, more cases should be added to examine this methodology for bone deformity surgery in the near future.

Accuracy of Conventional Triplane Measures Compared to 3-D Analysis for Assessment of Cubitus Varus Deformities in Adults

Purpose

Cubitus varus is a common triplane deformity in adults associated with supracondylar humeral fractures experienced as a child and consists of varus, extension, and internal rotation components. When corrective osteotomy is indicated, these three components should be measured precisely. This study aimed to evaluate the accuracy of radiographic and physical measurements of cubitus varus deformities in adults compared to values measured on three-dimensional (3-D) bone surface models of the adult bilateral humerus.

Methods

Three-dimensional bilateral humerus models were developed using bilateral humerus CT images of 20 adult patients with cubitus varus. The varus, internal rotation, and extension components of the deformity were assessed by superimposing the 3-D bone model onto a mirror-image model of the contralateral normal humerus. Values obtained from the radiographic and physical measurements were compared with those from the 3D model. The reliability of each measurement was assessed by calculating correlation coefficients (CCs).

Results

Radiographic measurements of the varus and extension components showed good reliability (CC = 0.796 and 0.791, respectively). Physical measurement of the varus component, however, showed only moderate reliability (CC= 0.539), while physical measurement of the extension and internal rotation components exhibited poor reliability (CC = 0.164 and 0.466, respectively).

Conclusion

Varus and extension components of cubitus varus in adults can be reliably measured using conventional methods, whereas the internal rotation component cannot. Thus, 3-D methods with which to quantify the rotational component preoperatively might be needed when the correction of a rotational deformity is considered.

Comparison of internal fixation vs. external fixation after corrective osteotomy in children with cubitus varus

BACKGROUND

Cubitus varus deformity is a well-known late complication of supracondylar fractures in children. In this retrospective study, the primary objective was to compare clinical and radiologic outcomes of lateral closing-wedge osteotomy with either internal fixation or external fixation in pediatric patients with cubitus varus deformities.

MATERIALS AND METHODS

From 2010 to 2017, 35 consecutive patients with cubitus varus deformities secondary to supracondylar fractures were included in this study. After corrective osteotomy was performed via a limited lateral approach, the method of definitive fixation was chosen between internal and external. Retrospectively, patients who underwent external fixation on the lateral aspect of the elbow were defined as group I (n = 16) whereas patients with unilateral single-plate fixation were defined as group II (n = 19). The functional outcome was evaluated using the Mayo Elbow Performance Score and Flynn criteria.

RESULTS

No significant difference in age was found between the 2 groups (P = .15). Significantly lower costs, a shorter operation duration, smaller scars, and a shorter time for plaster cast use postoperatively were found in group I (P < .001). No nonunion or failure of fixation was found. No significant difference was noted in postoperative elbow range of motion or Mayo Elbow Performance Score (P = .64). Both groups achieved satisfactory functional and cosmetic results.

CONCLUSIONS

In pediatric patients with cubitus varus, both methods of fixation after lateral closing-wedge corrective osteotomy are reliable, with a low rate of complications and satisfactory functional results. External fixation is more advantageous in terms of easier preoperative planning, shorter operative times, lower costs, and easier postoperative fixation removal.

Clinical application of individualized 3D-printed navigation template to children with cubitus varus deformity

Background

Cubitus varus deformity is a common sequela of elbow fractures in children. Cubitus varus deformity treatment is tending toward 3D correction, which is challenging for orthopedic surgeons. This study aims to explore whether individualized 3D-printed navigation templates can assist with accurate and effective corrective treatment of children with cubitus varus deformity.

Methods

Thirty-five patients were treated for cubitus varus deformity from June 2015 to April 2017, including 21 boys and 14 girls, aged 4.6–13.2 years (average, 7.5 years). Of these cases, 17 deformities were on the left side and 18 were on the right side. All were treated with wedge osteotomy of the lateral distal humerus. 3D-printed navigation templates were used in 16 cases, while traditional surgery was used in 19 cases. All patients underwent computed tomography scans before surgery. Computer software was used to analyze the measurements and design and print individualized navigation templates. The navigation templates were matched, and surgery was initially simulated. Intraoperative individualized navigation templates were used to assist with accurate osteotomy and Kirschner wire fixation. Operation times were recorded in all cases, the carrying angles before and after surgery were assessed by computer, and postoperative elbow joint function was evaluated using Bellemore criteria. All measurement data were presented as means ± SD, and Student’s t test was used to examine differences between groups. All count data between both groups were compared using the chi-square test or Fisher’s exact test analysis.

Results

All individualized navigation templates matched well with the corresponding anatomical markers and were consistent with preoperative planning, simulated surgery, and intraoperative procedures. Average operation times from clear exposure to fixed Kirschner wire were 11.69 min (9.6–13.5 min) for the individualized navigation template group and 22.89 min (17.7–26.8 min) for the traditional operation group (p < 0.001). Average differences in postoperation carrying angles between affected and healthy sides were 1.13° (0–2.0°) and 4.21° (0–7.5°), respectively (p < 0.001). Follow-up 6–12 months postoperation showed that elbow function did not differ significantly between groups using the Bellemore criteria (p > 0.05).

Conclusions

Individualized navigation templates simplify procedures, reduce operation time, and improve accuracy when used in orthopedic surgery to treat children with cubitus varus deformity.

A personalized preoperative modeling system for internal fixation plates in long bone fracture surgery-A straightforward way from CT images to plate model

BACKGROUND

Long bone fractures are a type of physical damage with high incidence rates that have serious impacts on the normal lives of humans.

AIMS

How to obtain a preoperative internal fixation plate model before cutting muscle has become a critical issue.

MATERIALS AND METHODS

In this paper, we present a new personalized modeling system for internal fixation plates in long bone fracture surgery. This system can achieve straight semi-automatic processing from CT images to 3D models. First, broken bones are separated in CT images. Second, the axes of long broken bones are extracted using 3D models. Third, the vertices on the broken bone cross-sections are segmented. Fourth, rough alignment and fine registration are implemented.

RESULTS

An internal fixation plate is reconstructed for a long bone fracture.

DISCUSSION

Three validations indicate that this method framework is reasonable and feasible.

CONCLUSION

This system can provide technical support for the personalized, minimally invasive and accurate operation on long bone fractures.

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.

Normal value and range of the humerus-elbow-wrist angle in a sample of healthy children with even distributions of age, sex, and laterality

This study was performed to evaluate the normal value of the humerus-elbow-wrist angle (HEWA) in a sample of healthy children with even distributions of age, sex, and laterality. A total of 168 radiographs of the elbows of healthy children with even distributions of age, sex, and laterality were reviewed. The mean HEWA was 12.1° (range: 5°-20°). The value of HEWA was significantly associated with increasing age. Neither sex nor side showed significant differences for the HEWA. The data should be useful for postoperative radiographic assessment of cubitus varus or valgus deformities.

Corrective Osteotomies of Phalangeal and Metacarpal Malunions Using Patient-Specific Guides: CT-Based Evaluation of the Reduction Accuracy

BACKGROUND

Surgical planning of corrective osteotomies is traditionally based on conventional radiographs and clinical findings. In the past 10 years, 3-dimensional (3D) preoperative planning approaches with patient-specific guides have been developed. However, the application of this technology to posttraumatic deformities of the metacarpals and phalangeal bones has not yet been investigated. Our goal was to evaluate the feasibility of the surgical application to the latter and to evaluate the extent and precision of correction.

METHODS

We present results of 6 patients (8 osteotomies) treated with phalangeal or metacarpal corrective osteotomy. Deformities were located in the third ray in 1, fourth ray in 3, and fifth ray in 4 cases. Six malunited metacarpal bones (1 intra-articular) and 2 deformed proximal phalanges were treated. Computer-based 3D preoperative planning using the contralateral hand as a template allowed the production of 3D-printed patient-specific guides that were used intraoperatively for navigation. The precision of the reduction was assessed using pre- and postoperative computed tomography by comparing the postoperative bone model with the preoperatively simulated osteotomy. Range of motion and grip strength were documented pre- and postoperatively.

RESULTS

The mean follow-up time was 6 months (range: 5-11 months). Rotational deformity was reduced from a mean of 10.0° (range: 7.2°-19.3°) preoperatively to 2.3° (range: 0.7°-3.7°) postoperatively, and translational incongruency decreased from a mean of 1.4 mm (range: 0.7-2.8 mm) to 0.4 mm (range: 0.1-0.9 mm).

CONCLUSION

Preliminary results indicate that a precise reduction for corrective osteotomies of metacarpal and phalangeal bones can be achieved by using 3D planning and patient-specific guides.

Morphology and kinematics studies of the upper extremity and its clinical application in deformity correction

Morphological and kinetic studies using computer-generated bone models are helpful for determining normal articular movements and various pathological conditions of the wrist joints, forearms, and elbow joints. Previous studies consisted of kinetic analyses that were carried out by superimposing three-dimensional bone models created on a computer on the basis of CT data obtained by scanning the limbs in several different positions. We applied the techniques used in such studies and have discovered a method for carrying out surgical procedure simulations aimed at correcting upper limb deformities. In addition, we have developed a system aimed at assisting surgical procedures conducted in accordance with simulations by using patient-matched guides (patient-matched instruments, PMI) and custom-made osteosynthesis plates. Our system has allowed for accurate anatomical corrections to be carried out three-dimensionally during a simple surgical procedure. The system was clinically used in the treatment of cubitus varus as well as malunited distal radial fractures and forearm fractures. As a result, accurate correction and favorable clinical outcomes have been achieved. Together with the development of therapeutic techniques, we have also simultaneously developed the related technological system, which consists of imaging protocols aimed at reducing the amount of radiation exposure and creating statistical shape models, as well as web-based tools for communication between physicians and engineers.

A Novel Method for the Approximation of Humeral Head Retrotorsion Based on Three-Dimensional Registration of the Bicipital Groove

BACKGROUND

The accurate restoration of premorbid anatomy is key for the success of reconstructive surgeries of the proximal part of the humerus. The bicipital groove has been proposed as a landmark for the prediction of humeral head retrotorsion. We hypothesized that a novel method based on bilateral registration of the bicipital groove yields an accurate approximation of the premorbid anatomy of the proximal part of the humerus.

METHODS

Three-dimensional (3D) triangular surface models were created from computed tomographic data of 100 paired humeri (50 cadavers). Segments of the distal part of the humerus and the humeral shaft of prespecified lengths were defined. A surface registration algorithm was applied to superimpose the models onto the mirrored contralateral humeral model based on the defined segments. We evaluated the 3D proximal humeral contralateral registration (p-HCR) errors, defined as the difference in 3D rotation of the humeral head between the models when superimposed. For comparison, we quantified the landmark-based retrotorsion (LBR) error, defined as the intra-individual difference in retrotorsion, measured with a landmark-based 3D method.

RESULTS

The mean 3D p-HCR error using the most proximal humeral shaft (bicipital groove) segment for the registration was 2.8° (standard deviation [SD], 1.5°; range, 0.6° to 7.4°). The mean LBR error of the reference method was 6.4° (SD, 5.9°; range, 0.5° to 24.0°).

CONCLUSIONS

Bilateral 3D registration of the bicipital groove is a reliable method for approximating the premorbid anatomy of the proximal part of the humerus.

CLINICAL RELEVANCE

The accurate approximation of the premorbid anatomy is a key for the successful restoration of the premorbid anatomy of the proximal part of the humerus.

Restoration of the Patient-Specific Anatomy of the Proximal and Distal Parts of the Humerus: Statistical Shape Modeling Versus Contralateral Registration Method

BACKGROUND

In computer-assisted reconstructive surgeries, the contralateral anatomy is established as the best available reconstruction template. However, existing intra-individual bilateral differences or a pathological, contralateral humerus may limit the applicability of the method. The aim of the study was to evaluate whether a statistical shape model (SSM) has the potential to predict accurately the pretraumatic anatomy of the humerus from the posttraumatic condition.

METHODS

Three-dimensional (3D) triangular surface models were extracted from the computed tomographic data of 100 paired cadaveric humeri without a pathological condition. An SSM was constructed, encoding the characteristic shape variations among the individuals. To predict the patient-specific anatomy of the proximal (or distal) part of the humerus with the SSM, we generated segments of the humerus of predefined length excluding the part to predict. The proximal and distal humeral prediction (p-HP and d-HP) errors, defined as the deviation of the predicted (bone) model from the original (bone) model, were evaluated. For comparison with the state-of-the-art technique, i.e., the contralateral registration method, we used the same segments of the humerus to evaluate whether the SSM or the contralateral anatomy yields a more accurate reconstruction template.

RESULTS

The p-HP error (mean and standard deviation, 3.8° ± 1.9°) using 85% of the distal end of the humerus to predict the proximal humeral anatomy was significantly smaller (p = 0.001) compared with the contralateral registration method. The difference between the d-HP error (mean, 5.5° ± 2.9°), using 85% of the proximal part of the humerus to predict the distal humeral anatomy, and the contralateral registration method was not significant (p = 0.61). The restoration of the humeral length was not significantly different between the SSM and the contralateral registration method.

CONCLUSIONS

SSMs accurately predict the patient-specific anatomy of the proximal and distal aspects of the humerus. The prediction errors of the SSM depend on the size of the healthy part of the humerus.

CLINICAL RELEVANCE

The prediction of the patient-specific anatomy of the humerus is of fundamental importance for computer-assisted reconstructive surgeries.

Altered bone density and stress distribution patterns in long-standing cubitus varus deformity and their effect during early osteoarthritis of the elbow

OBJECTIVE

To quantify the bone density and stress distribution patterns in long-standing cubitus varus and clarify the effects of the deformity on bone density.

DESIGN

We created three-dimensional computed tomography (CT) elbow models from 21 patients with long-standing cubitus varus deformities without advanced osteoarthritis (OA) and assessed the deformity by superimposing the affected humerus onto a mirror-image of the contralateral normal. Elbows were divided into 13 regions before measuring the bone density of each region and comparing the percentage of high-density volume (%HDV) between affected and normal sides. We constructed finite element models and quantitatively analyzed stress distribution.

RESULTS

Average degrees of deformities were 20.1° of varus, 6.4° of extension, and 12.7° of internal rotation. The medial side of the affected humerus and ulna, Anteromedial trochlea (P < 0.001), Medial coronoid (P = 0.004), and Medial olecranon (P = 0.049) had significantly higher %HDVs than their normal counterparts. Conversely, %HDVs on the affected lateral side, Capitellum (P < 0.001), Anterolateral trochlea (P = 0.010), Posterolateral trochlea (P < 0.001), Lateral coronoid (P = 0.007), and Lateral olecranon (P < 0.001) were significantly lower than the normal side. The affected radial head %HDVs at Anterolateral and Posteromedial quadrants were high (P = 0.007) and low (P = 0.007), respectively. The bone density distribution coincided with stress distribution patterns revealed by finite element analysis (FEA), except in the lateral region influenced by forearm rotation.

CONCLUSIONS

Repetitive stress on the medial elbow may alter bone density distribution patterns, probably presenting from early stage of OA.

Physeal bar resection using a patient-specific guide with intramedullary endoscopic assistance for partial physeal arrest of the distal radius

The partial physeal arrest of the distal radius could result in progressive deformities and functional problems of the wrist. Despite being the most preferred surgical intervention, physeal bar resection (Langenskiöld procedure) is technically demanding. This manuscript aims to illustrate the technical tricks and present an illustrative case of premature physeal arrest of the distal radius managed with a novel method for the Langenskiöld procedure, involving complete removal of the bar using a patient-specific guide in combination with an intramedullary endoscopy technique that facilitated direct observation.

A Novel Registration-Based Approach for 3D Assessment of Posttraumatic Distal Humeral Deformities

BACKGROUND

With current 3-dimensional (3D) computer-based methods for the assessment of deformities, a surface registration method is applied to superimpose a computer model of the pathological bone onto a mirrored computer model of the contralateral side. However, because of bilateral differences, especially in humeral torsion, such template-based approaches may introduce bias in the assessment of a distal humeral deformity. We hypothesized that a novel registration approach might prove superior to the current approach in reducing such bias, thus yielding improved accuracy of 3D assessment of distal humeral deformities.

METHODS

Three-dimensional triangular surface models were generated from computed tomographic (CT) data of 100 paired humeri without a pathological condition. Humeral segments of varying, predetermined lengths, excluding the distal part of the humerus, were defined. A surface registration algorithm was applied to superimpose the humeral models of both sides based on each selected segment. Humeral contralateral registration (HCR) errors, defined as the residual differences in apparent 3D orientation between the distal parts, were evaluated.

RESULTS

The mean HCR error (and standard deviation) using the distal-most humeral shaft segment to assess the angular orientation was 2.3° ± 1.1 (range, 0.5° to 5.8°). Including the humeral head in the surface registration algorithm, however, as is done currently, resulted in a higher HCR error (p < 0.001). The HCR error using the proximal-most segment was >10° in 20% of the cases and between 5° and 10° in an additional 50% of the cases. By comparison, using the proposed distal-most humeral shaft segment, the HCR error was between 5° and 10° in only 2% of cases, and was never >10°. The proximal segments are nevertheless used in the proposed method for registering humeral length.

CONCLUSIONS

The proposed new approach yields a deformity assessment that is less prone to bias arising from inherent bilateral differences and therefore is more accurate than current surface registration approaches.

CLINICAL RELEVANCE

Accurate 3D assessment is of fundamental importance if computer-based methods are applied in the correction of posttraumatic deformities.

Accuracy assessment of surgical planning and three-dimensional-printed patient-specific guides for orthopaedic osteotomies

This study analyses the accuracy of three-dimensional pre-operative planning and patient-specific guides for orthopaedic osteotomies. To this end, patient-specific guides were compared to the classical freehand method in an experimental setup with saw bones in two phases. In the first phase, the effect of guide design and oscillating versus reciprocating saws was analysed. The difference between target and performed cuts was quantified by the average distance deviation and average angular deviations in the sagittal and coronal planes for the different osteotomies. The results indicated that for one model osteotomy, the use of guides resulted in a more accurate cut when compared to the freehand technique. Reciprocating saws and slot guides improved accuracy in all planes, while oscillating saws and open guides lead to larger deviations from the planned cut. In the second phase, the accuracy of transfer of the planning to the surgical field with slot guides and a reciprocating saw was assessed and compared to the classical planning and freehand cutting method. The pre-operative plan was transferred with high accuracy. Three-dimensional-printed patient-specific guides improve the accuracy of osteotomies and bony resections in an experimental setup compared to conventional freehand methods. The improved accuracy is related to (1) a detailed and qualitative pre-operative plan and (2) an accurate transfer of the planning to the operation room with patient-specific guides by an accurate guidance of the surgical tools to perform the desired cuts.

Reliability and Validity of Radiographic Measurement of the Humerus-Elbow-Wrist Angle in Healthy Children

This article was updated on May 4, 2017, because of a previous error. The proximal line drawn in Figure 1 was different from the line described in the Materials and Methods section, which reads “The proximal line was drawn at the level of the radial tuberosity, and the distal line was made at the level of the top of the radial bowing (Fig. 1).” The correct figure is presented in this version of the article.

An erratum has been published: JBJS Open Access. 2017 May 26;2(2):e0012ER.

Three-dimensional corrective osteotomies of complex malunited humeral fractures using patient-specific guides

BACKGROUND

Corrective osteotomies of malunited fractures of the proximal and distal humerus are among the most demanding orthopedic procedures. Whereas the restoration of the normal humeral anatomy is the ultimate goal, the quantification of the deformity as well as the transfer of the preoperative plan is challenging. The purpose of this study was to provide a guideline for 3-dimensional (3D) corrective osteotomies of malunited intra-articular fractures of the humerus and a detailed overview of existing and novel instruments to enlarge the toolkit for 3D preoperative planning and intraoperative realization using patient-specific guides.

METHODS

We describe the preoperative 3D deformity analysis, relevant considerations for the preoperative plan, design of the patient-specific guides, and surgical technique of corrective osteotomies of the humerus.

RESULTS

The presented technique demonstrates the benefit of computer-assisted surgery for complex osteotomies of the humerus from a preoperative deformity analysis to the creation of feasible surgical procedures and the generation of patient-specific guides.

CONCLUSIONS

A 3D analysis of a post-traumatic deformity of the humerus, 3D preoperative planning, and use of patient-specific guides facilitate corrective osteotomies of complex malunited humeral fractures.

Rapid prototyping for patient-specific surgical orthopaedics guides: A systematic literature review

There has been a lot of hype surrounding the advantages to be gained from rapid prototyping processes in a number of fields, including medicine. Our literature review aims objectively to assess how effective patient-specific surgical guides manufactured using rapid prototyping are in a number of orthopaedic surgical applications. To this end, we carried out a systematic review to identify and analyse clinical and experimental literature studies in which rapid prototyping patient-specific surgical guides are used, focusing especially on those that entail quantifiable outcomes and, at the same time, providing details on the guides’ design and type of manufacturing process. Here, it should be mentioned that in this field there are not yet medium- or long-term data, and no information on revisions. In the reviewed studies, the reported positive opinions on the use of rapid prototyping patient-specific surgical guides relate to the following main advantages: reduction in operating times, low costs and improvements in the accuracy of surgical interventions thanks to guides’ personalisation. However, disadvantages and sources of errors which can cause patient-specific surgical guide failures are as well discussed by authors. Stereolithography is the main rapid prototyping process employed in these applications although fused deposition modelling or selective laser sintering processes can also satisfy the requirements of these applications in terms of material properties, manufacturing accuracy and construction time. Another of our findings was that individualised drill guides for spinal surgery are currently the favourite candidates for manufacture using rapid prototyping. Other emerging applications relate to complex orthopaedic surgery of the extremities: the forearm and foot. Several procedures such as osteotomies for radius malunions or tarsal coalition could become standard, thanks to the significant assistance provided by rapid prototyping patient-specific surgical guides in planning and performing such operations.