Bone defects after trauma, infection, or tumour resection present a challenge for patients and clinicians. To date, autologous bone graft (ABG) is the gold standard for bone regeneration. To address the limitations of ABG such as limited harvest volume as well as overly fast remodelling and resorption, a new treatment strategy of scaffold-guided bone regeneration (SGBR) was developed. In a well-characterized sheep model of large to extra-large tibial segmental defects, three-dimensional (3D) printed composite scaffolds have shown clinically relevant biocompatibility and osteoconductive capacity in SGBR strategies. Here, we report four challenging clinical cases with large complex posttraumatic long bone defects using patient-specific SGBR as a successful treatment. After giving informed consent computed tomography (CT) images were used to design patient-specific biodegradable medical-grade polycaprolactone-tricalcium phosphate (mPCL-TCP, 80:20 ​wt%) scaffolds. The CT scans were segmented using Materialise Mimics to produce a defect model and the scaffold parts were designed with Autodesk Meshmixer. Scaffold prototypes were 3D-printed to validate robust clinical handling and bone defect fit. The final scaffold design was additively manufactured under Food and Drug Administration (FDA) guidelines for patient-specific and custom-made implants by Osteopore International Pte Ltd. Four patients (age: 23–42 years) with posttraumatic lower extremity large long bone defects (case 1: 4 ​cm distal femur, case 2: 10 ​cm tibia shaft, case 3: complex malunion femur, case 4: irregularly shaped defect distal tibia) are presented. After giving informed consent, the patients were treated surgically by implanting a custom-made mPCL-TCP scaffold loaded with ABG (case 2: additional application of recombinant human bone morphogenetic protein-2) harvested with the Reamer-Irrigator-Aspirator system (RIA, Synthes®). In all cases, the scaffolds matched the actual anatomical defect well and no perioperative adverse events were observed. Cases 1, 3 and 4 showed evidence of bony ingrowth into the large honeycomb pores (pores >2 ​mm) and fully interconnected scaffold architecture with indicative osseous bridges at the bony ends on the last radiographic follow-up (8–9 months after implantation). Comprehensive bone regeneration and full weight bearing were achieved in case 2 ​at follow-up 23 months after implantation. This study shows the bench to bedside translation of guided bone regeneration principles into scaffold-based bone tissue engineering. The scaffold design in SGBR should have a tissue-specific morphological signature which stimulates and directs the stages from the initial host response towards the full regeneration. Thereby, the scaffolds provide a physical niche with morphology and biomaterial properties that allow cell migration, proliferation, and formation of vascularized tissue in the first one to two months, followed by functional bone formation and the capacity for physiological bone remodelling. Great design flexibility of composite scaffolds to support the one to three-year bone regeneration was observed in four patients with complex long bone defects. This study reports on the clinical efficacy of SGBR in the treatment of long bone defects. Moreover, it presents a comprehensive narrative of the rationale of this technology, highlighting its potential for bone regeneration treatment regimens in patients with any type of large and complex osseous defects.

Bone sarcomas are rare primary malignant mesenchymal bone tumors. The three main entities are osteosarcoma, chondrosarcoma, and Ewing sarcoma. While prognosis has improved for affected patients over the past decades, bone sarcomas are still critical conditions that require an interdisciplinary diagnostic and therapeutic approach. While radiotherapy plays a role especially in Ewing sarcoma and chemotherapy in Ewing sarcoma and osteosarcoma, surgery remains the main pillar of treatment in all three entities. After complete tumor resection, the created bone defects need to be reconstructed. Possible strategies are implantation of allografts or autografts including vascularized bone grafts (e.g., of the fibula). Around the knee joint, rotationplasty can be performed or, as an alternative, the implantation of (expandable) megaprostheses can be performed. Challenges still associated with the implantation of foreign materials are aseptic loosening and infection. Future improvements may come with advances in 3D printing of individualized resection blades/implants, thus also securing safe tumor resection margins while at the same time shortening the required surgical time. Faster osseointegration and lower infection rates may possibly be achieved through more elaborate implant surface structures.

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

Background: Brace therapy’s influence on adolescent idiopathic scoliosis’s (AIS) natural course is inconclusive. Methods: Brace-treated AIS patients from 2016 to 2020 were examined regarding four endpoints at brace weaning: surgery need, curve progress ≥ 6° and > 45°, and curve improvement ≥ 6°. Prediction variables’ influence was computed for the all-patients group and three subgroups (Subgroup 1: fulfilling the Scoliosis Research Society’s [SRS] criteria, Subgroup 2: initial Cobb angle < 25°, Subgroup 3: initial Cobb angle > 40°). According to the data characteristics, parametric and non-parametric tests and binary logistic regression were performed. Results: The research included 69 patients. Overall, after brace weaning surgery was recommended for 20.3% of them, curve progression was ≥ 6° in 23.2%, the Cobb angle was beyond 45° in 11.6%, and the Cobb angle improved by ≥ 6° in 20.3%. Patients needing surgery had a significantly higher initial Cobb angle (38.8° ± 9.8° vs 27.8° ± 7.6°, p < 0.001), lower Risser stages (p = 0.010), and higher Nash and Moe degrees (p = 0.030). Patients with curve progress ≥ 6° were younger at first curve notification (12.4 ± 1.5 vs 13.7 ± 1.7 years, p = 0.011) and older at menarche (13.4 ± 1.1 vs 12.6 ± 1.2 years, p = 0.037). Furthermore, 21.6% of all Risser 3 and 4 patients had still curve progress ≥ 6°. In-brace correction was significantly higher in patients with curve improvement ≥ 6° vs < 6° (54.0% ± 31.2% vs 31.9% ± 30.7%; p = 0.019). Nine patients fulfilled the SRS criteria, 22 had initial Cobb angles < 25°, and 11 had > 40°. Real brace wear (RBW) in all groups had no significant effect on outcome. Two significant subgroup differences were found: Surgery recommendation and curve progression beyond 45° were significantly more frequent in the initial Cobb angle > 40° subgroup. Conclusions: Brace effectiveness can be assumed because curve improvement was achieved in nearly one-fifth with sufficient in-brace correction. However, no significant influence of RBW on the outcome endpoints was demonstrated. To clarify conflicting results, big data management, including untreated patients, must be employed to further research AIS’s multifactorial influenced aetiology and course. Meanwhile, it is worth starting bracing in AIS in practice also beyond the SRS’s criteria.

Background: The treatment results of the Ponseti method for arthrogrypotic clubfoot have been described in only a few case series. Further evaluations are necessary. Methods: Children from two German paediatric orthopaedic hospitals with arthrogryposis-associated clubfoot treated with the Ponseti method between 2004 and 2011 and who were at least five years of age at their last follow-up were retrospectively evaluated. The endpoints were the clinical foot position, necessary surgeries during the follow-up period and radiological constellations. A comprehensive literature review was conducted after a systematic literature search. Results: Seventeen patients (47% with amyoplasia [AP] and 53% with distal arthrogryposis [DA]) met the inclusion criteria. Thirty-one feet were evaluated. The period between the treatment start and the last follow-up examination covered 8.9 ± 2.5 years. After the last cast removal within the initial Ponseti cast series, 74% of the clinical results were good to excellent. However, the clinical outcomes in the patients with AP were significantly worse. Overall, in 23 feet (74%), at least one major surgery at the age of 2.9 ± 2.2 years was necessary during the clinical course. Major surgeries were much more frequent on the feet of the patients with AP than with DA. Lateral X-rays showed normal age-appropriate radiological angles in 4% of the feet, hindfoot equinus in 19%, under-corrected hindfoot in 44%, under-corrected clubfoot in 26% and rocker bottom deformity in 7%. The radiological residual deformities in AP were much more severe than in DA (p = 0.042). Most of the studies reviewed (11 case series, 144 patients) reported high initial clinical correction rates, followed by high recurrence rates and the need for further surgeries. Conclusion: About a quarter of the arthrogrypotic patients benefited from the Ponseti therapy without further major surgery. However, the clinically observed high initial correction rate after Ponseti therapy of arthrogrypotic clubfoot was not accompanied by a correction of the bony foot position in the X-rays. The feet of the patients with DA had better outcomes than those of the patients with AP. Therefore, in outcome studies, a clear distinction between patients with AP and those with DA is necessary.

Purpose: Up to 90% of nonambulatory patients with cerebral palsy (CP) experience hip displacement during their lifetime. Reconstructive surgery is recommended. Redisplacement rate is an outcome parameter. Methods: In a systematic literature review (MEDLINE, Embase and CENTRAL databases) until January 2023 we searched for reports with redisplacement rates after bony hip reconstructive surgery in nonambulatory patients. Quantitative data synthesis, subgroup analysis and meta-regression with moderators were carried out. Results: The pooled mean redisplacement rate was 16% (95% CI: 12–21%) with a prediction interval of 3–51% (Q: 149; df: 32; P < 0.001; I²: 78%; τ²: 0.67 and τ: 0.82) in 28 studies (1540 hips). Varus derotation osteotomy (VDRO) alone showed a higher redisplacement rate than VDRO + pelvic osteotomy (30% vs 12%, P < .0001). Mean age in the VDRO-alone subgroup was 7.1 years and in the combined group 9.5 years (P = .004). In meta-regression, lower redisplacement rates were observed with higher preoperative migration index (MI) (correlation coefficient: −0.0279; P = .0137), where comprehensive surgery was performed. Variance in true effects are explained by type of bone surgery (57%), preoperative MI (11%), age (5%) and MI for definition of failure (20%). No significant reduction in the redisplacement rate could be observed over the mid-years of studies (1977-2015). Conclusion: Our pooled data support the more extensive surgical approach in patients with high preoperative MI and emphasize the superiority of combined surgery. Studies should report a coordinated set of parameters and outcome classifications according to internationally accepted gradings to reduce redisplacement in future.