Aims. This study aimed to analyze the accuracy and errors associated with 3D-printed, patient-specific resection guides (3DP-PSRGs) used for bone tumour resection. Methods. We retrospectively reviewed 29 bone tumour resections that used 3DP-PSRGs based on 3D CT and 3D MRI. We evaluated the resection amount errors and resection margin errors relative to the preoperative plans. Guide-fitting errors and guide distortion were evaluated intraoperatively and one month postoperatively, respectively. We categorized each of these error types into three grades (grade 1, < 1 mm; grade 2, 1 to 3 mm; and grade 3, > 3 mm) to evaluate the overall accuracy. Results. The maximum resection amount error was 2 mm. Out of 29 resection amount errors, 15 (51.7%) were grade 1 errors and 14 (48.3%) were grade 2 errors. Complex resections were associated with higher-grade resection amount errors (p < 0.001). The actual resection margins correlated significantly with the planned margins; however, there were some discrepancies. The maximum guide-fitting error was 3 mm. There were 22 (75.9%), five (17.2%), and two (6.9%) grade 1, 2, and 3 guide-fitting errors, respectively. There was no significant association between complex resection and fitting error grades. The guide distortion after one month in all patients was rated as grade 1. Conclusion. In terms of the accurate resection amount according to the preoperative planning, 3DP-PSRGs can be a viable option for bone tumour resection. However, 3DP-PSRG use may be associated with resection margin length discrepancies relative to the planned margins. Such discrepancies should be considered when determining surgical margins. Therefore, a thorough evaluation of the preoperative imaging and surgical planning is still required, even if 3DP-PSRGs are to be used. Cite this article: Bone Joint J 2023;105-B(2):190–197

Aims. This study aimed to compare the performance of survival prediction models for bone metastases of the extremities (BM-E) with pathological fractures in an Asian cohort, and investigate patient characteristics associated with survival. Methods. This retrospective cohort study included 469 patients, who underwent surgery for BM-E between January 2009 and March 2022 at a tertiary hospital in South Korea. Postoperative survival was calculated using the PATHFx3.0, SPRING13, OPTIModel, SORG, and IOR models. Model performance was assessed with area under the curve (AUC), calibration curve, Brier score, and decision curve analysis. Cox regression analyses were performed to evaluate the factors contributing to survival. Results. The SORG model demonstrated the highest discriminatory accuracy with AUC (0.80 (95% confidence interval (CI) 0.76 to 0.85)) at 12 months. In calibration analysis, the PATHfx3.0 and OPTIModel models underestimated survival, while the SPRING13 and IOR models overestimated survival. The SORG model exhibited excellent calibration with intercepts of 0.10 (95% CI -0.13 to 0.33) at 12 months. The SORG model also had lower Brier scores than the null score at three and 12 months, indicating good overall performance. Decision curve analysis showed that all five survival prediction models provided greater net benefit than the default strategy of operating on either all or no patients. Rapid growth cancer and low serum albumin levels were associated with three-, six-, and 12-month survival. Conclusion. State-of-art survival prediction models for BM-E (PATHFx3.0, SPRING13, OPTIModel, SORG, and IOR models) are useful clinical tools for orthopaedic surgeons in the decision-making process for the treatment in Asian patients, with SORG models offering the best predictive performance. Rapid growth cancer and serum albumin level are independent, statistically significant factors contributing to survival following surgery of BM-E. Further refinement of survival prediction models will bring about informed and patient-specific treatment of BM-E. Cite this article: Bone Joint J 2024;106-B(2):203–211

Aims. Dislocation of the hip remains a major complication after periacetabular tumour resection and endoprosthetic reconstruction. The position of the acetabular component is an important modifiable factor for surgeons in determining the risk of postoperative dislocation. We investigated the significance of horizontal, vertical, and sagittal displacement of the hip centre of rotation (COR) on postoperative dislocation using a CT-based 3D model, as well as other potential risk factors for dislocation. Methods. A total of 122 patients who underwent reconstruction following resection of periacetabular tumour between January 2011 and January 2020 were studied. The risk factors for dislocation were investigated with univariate and multivariate logistic regression analysis on patient-specific, resection-specific, and reconstruction-specific variables. Results. The dislocation rate was 13.9% (n = 17). The hip COR was found to be significantly shifted anteriorly and inferiorly in most patients in the dislocation group compared with the non-dislocation group. Three independent risk factors were found to be related to dislocation: resection of gluteus medius (odds ratio (OR) 3.68 (95% confidence interval (CI) 1.24 to 19.70); p = 0.039), vertical shift of COR > 18 mm (OR 24.8 (95% CI 6.23 to 128.00); p = 0.001), and sagittal shift of COR > 20 mm (OR 6.22 (95% CI 1.33 to 32.2); p = 0.026). Conclusion. Among the 17 patients who dislocated, 70.3% (n = 12) were anterior dislocations. Three independent risk factors were identified, suggesting the importance of proper restoration of the COR and the role of the gluteus medius in maintaining hip joint stability. Cite this article: Bone Joint J 2022;104-B(10):1180–1188

Aims. Surgical site infection (SSI) after soft-tissue sarcoma (STS) resection is a serious complication. The purpose of this retrospective study was to investigate the risk factors for SSI after STS resection, and to develop a nomogram that allows patient-specific risk assessment. Methods. A total of 547 patients with STS who underwent tumour resection between 2005 and 2021 were divided into a development cohort and a validation cohort. In the development cohort of 402 patients, the least absolute shrinkage and selection operator (LASSO) regression model was used to screen possible risk factors of SSI. To select risk factors and construct the prediction nomogram, multivariate logistic regression was used. The predictive power of the nomogram was evaluated by receiver operating curve (ROC) analysis in the validation cohort of 145 patients. Results. LASSO regression analysis selected possible risk factors for SSI, including age, diabetes, operating time, skin graft or flap, resected tumour size, smoking, and radiation therapy. Multivariate analysis revealed that age, diabetes, smoking during the previous year, operating time, and radiation therapy were independent risk factors for SSI. A nomogram was developed based on the results of multivariate logistic regression analysis. In the development cohort, the incidence of SSI was 4.5% in the low-risk group (risk score < 6.89) and 26.6% in the high-risk group (risk score ≥ 6.89; p < 0.001). In the validation cohort, the incidence of SSI was 2.0% in the low-risk group and 15.9% in the high-risk group (p = 0.004). Conclusion. Our nomogram will enable surgeons to assess the risk of SSI in patients with STS. In patients with high risk of SSI, frequent monitoring and aggressive interventions should be considered to prevent this. Cite this article: Bone Joint J 2024;106-B(5):492–500

Aims. There is an increased risk of dislocation of the hip after the resection of a periacetabular tumour and endoprosthetic reconstruction of the defect in the hemipelvis. The aim of this study was to determine the rate and timing of dislocation and to identify its risk factors. Methods. To determine the dislocation rate, we conducted a retrospective single-institution study of 441 patients with a periacetabular tumour who had undergone a standard modular hemipelvic endoprosthetic reconstruction between 2003 and 2019. After excluding ineligible patients, 420 patients were enrolled. Patient-specific, resection-specific, and reconstruction-specific variables were studied using univariate and multivariate analyses. Results. The dislocation rate was 9.3% (n = 41). Dislocation was most likely to occur in the first three months after surgery. Four independent risk factors were found, one of which was older age at operation (p = 0.039). The odds ratios (ORs) of those aged ≥ 60 years and 30 to 60 years were 8.50 and 4.64, respectively, compared with those aged < 30 years. The other three risk factors were resection of gluteus maximus (p = 0.010, OR = 5.8), vertical shift of the centre of rotation (COR) of the hip by ≥ 20 mm (p = 0.008, OR = 3.60), and a type I+II+III pelvic resection (p = 0.014, OR = 3.04). Conclusion. Hemipelvic endoprosthetic reconstruction after resection of a periacetabular tumour has a dislocation rate of 9.3% (n = 41). Patients are most likely to dislocate in the first three months after surgery. The risk is increased for older patients (especially those aged > 60 years) and for those with gluteus maximus resection, vertical shift of the COR ≥ 20 mm, and a type I+II+III pelvic resection. Cite this article: Bone Joint J 2021;103-B(2):382–390

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Controversy exists as to what should be considered a safe resection margin to minimize local recurrence in high-grade pelvic chondrosarcomas (CS). The aim of this study is to quantify what is a safe margin of resection for high-grade CS of the pelvis.

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Our aim was to develop and validate nomograms that would predict the cumulative incidence of sarcoma-specific death (CISSD) and disease progression (CIDP) in patients with localized high-grade primary central and dedifferentiated chondrosarcoma.

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Iliac wing (Type I) and iliosacral (Type I/IV) pelvic resections for a primary bone tumour create a large segmental defect in the pelvic ring. The management of this defect is controversial as the surgeon may choose to reconstruct it or not. When no reconstruction is undertaken, the residual ilium collapses back onto the remaining sacrum forming an iliosacral pseudarthrosis. The aim of this study was to evaluate the long-term oncological outcome, complications, and functional outcome after pelvic resection without reconstruction.

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Accurate estimations of the risk of fracture due to metastatic bone disease in the femur is essential in order to avoid both under-treatment and over-treatment of patients with an impending pathological fracture. The purpose of the current retrospective in vivo study was to use CT-based finite element analyses (CTFEA) to identify a clear quantitative differentiating factor between patients who are at imminent risk of fracturing their femur and those who are not, and to identify the exact location of maximal weakness where the fracture is most likely to occur.

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The aim of this paper was to investigate the prognostic factors for local recurrence in patients with pathological fracture through giant cell tumours of bone (GCTB).

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We present a retrospective review of patients treated with extracorporeally irradiated allografts for primary and secondary bone tumours with the mid- and long-term survivorship and the functional and radiographic outcomes.

Previously, we showed that case-specific non-linear finite element (FE) models are better at predicting the load to failure of metastatic femora than experienced clinicians. In this study we improved our FE modelling and increased the number of femora and characteristics of the lesions. We retested the robustness of the FE predictions and assessed why clinicians have difficulty in estimating the load to failure of metastatic femora. A total of 20 femora with and without artificial metastases were mechanically loaded until failure. These experiments were simulated using case-specific FE models. Six clinicians ranked the femora on load to failure and reported their ranking strategies. The experimental load to failure for intact and metastatic femora was well predicted by the FE models (R² = 0.90 and R² = 0.93, respectively). Ranking metastatic femora on load to failure was well performed by the FE models (τ = 0.87), but not by the clinicians (0.11 < τ < 0.42). Both the FE models and the clinicians allowed for the characteristics of the lesions, but only the FE models incorporated the initial bone strength, which is essential for accurately predicting the risk of fracture. Accurate prediction of the risk of fracture should be made possible for clinicians by further developing FE models.

We report our experience of using a computer navigation system to aid resection of malignant musculoskeletal tumours of the pelvis and limbs and, where appropriate, their subsequent reconstruction. We also highlight circumstances in which navigation should be used with caution.

We resected a musculoskeletal tumour from 18 patients (15 male, three female, mean age of 30 years (13 to 75) using commercially available computer navigation software (Orthomap 3D) and assessed its impact on the accuracy of our surgery. Of nine pelvic tumours, three had a biological reconstruction with extracorporeal irradiation, four underwent endoprosthetic replacement (EPR) and two required no bony reconstruction. There were eight tumours of the bones of the limbs. Four diaphyseal tumours underwent biological reconstruction. Two patients with a sarcoma of the proximal femur and two with a sarcoma of the proximal humerus underwent extra-articular resection and, where appropriate, EPR. One soft-tissue sarcoma of the adductor compartment which involved the femur was resected and reconstructed using an EPR. Computer navigation was used to aid reconstruction in eight patients.

Histological examination of the resected specimens revealed tumour-free margins in all patients. Post-operative radiographs and CT showed that the resection and reconstruction had been carried out as planned in all patients where navigation was used. In two patients, computer navigation had to be abandoned and the operation was completed under CT and radiological control.

The use of computer navigation in musculoskeletal oncology allows accurate identification of the local anatomy and can define the extent of the tumour and proposed resection margins. Furthermore, it helps in reconstruction of limb length, rotation and overall alignment after resection of an appendicular tumour.

Cite this article: Bone Joint J 2015;97-B:258–64.