Background: The Skeletal Oncology Research Group machine-learning algorithms (SORG-MLAs) estimate 90-day and 1-year survival in patients with long-bone metastases undergoing surgical treatment and have demonstrated good discriminatory ability on internal validation. However, the performance of a prediction model could potentially vary by race or region, and the SORG-MLA must be externally validated in an Asian cohort. Furthermore, the authors of the original developmental study did not consider the Eastern Cooperative Oncology Group (ECOG) performance status, a survival prognosticator repeatedly validated in other studies, in their algorithms because of missing data. Questions/purposes: (1) Is the SORG-MLA generalizable to Taiwanese patients for predicting 90-day and 1-year mortality? (2) Is the ECOG score an independent factor associated with 90-day and 1-year mortality while controlling for SORG-MLA predictions? Methods: All 356 patients who underwent surgery for long-bone metastases between 2014 and 2019 at one tertiary care center in Taiwan were included. Ninety-eight percent (349 of 356) of patients were of Han Chinese descent. The median (range) patient age was 61 years (25 to 95), 52% (184 of 356) were women, and the median BMI was 23 kg/m² (13 to 39 kg/m²). The most common primary tumors were lung cancer (33% [116 of 356]) and breast cancer (16% [58 of 356]). Fifty-five percent (195 of 356) of patients presented with a complete pathologic fracture. Intramedullary nailing was the most commonly performed type of surgery (59% [210 of 356]), followed by plate screw fixation (23% [81 of 356]) and endoprosthetic reconstruction (18% [65 of 356]). Six patients were lost to follow-up within 90 days; 30 were lost to follow-up within 1 year. Eighty-five percent (301 of 356) of patients were followed until death or for at least 2 years. Survival was 82% (287 of 350) at 90 days and 49% (159 of 326) at 1 year. The model’s performance metrics included discrimination (concordance index [c-index]), calibration (intercept and slope), and Brier score. In general, a c-index of 0.5 indicates random guess and a c-index of 0.8 denotes excellent discrimination. Calibration refers to the agreement between the predicted outcomes and the actual outcomes, with a perfect calibration having an intercept of 0 and a slope of 1. The Brier score of a prediction model must be compared with and ideally should be smaller than the score of the null model. A decision curve analysis was then performed for the 90-day and 1-year prediction models to evaluate their net benefit across a range of different threshold probabilities. A multivariate logistic regression analysis was used to evaluate whether the ECOG score was an independent prognosticator while controlling for the SORG-MLA’s predictions. We did not perform retraining/recalibration because we were not trying to update the SORG-MLA algorithm in this study. Results: The SORG-MLA had good discriminatory ability at both timepoints, with a c-index of 0.80 (95% confidence interval 0.74 to 0.86) for 90-day survival prediction and a c-index of 0.84 (95% CI 0.80 to 0.89) for 1-year survival prediction. However, the calibration analysis showed that the SORG-MLAs tended to underestimate Taiwanese patients’ survival (90-day survival prediction: calibration intercept 0.78 [95% CI 0.46 to 1.10], calibration slope 0.74 [95% CI 0.53 to 0.96]; 1-year survival prediction: calibration intercept 0.75 [95% CI 0.49 to 1.00], calibration slope 1.22 [95% CI 0.95 to 1.49]). The Brier score of the 90-day and 1-year SORG-MLA prediction models was lower than their respective null model (0.12 versus 0.16 for 90-day prediction; 0.16 versus 0.25 for 1-year prediction), indicating good overall performance of SORG-MLAs at these two timepoints. Decision curve analysis showed SORG-MLAs provided net benefits when threshold probabilities ranged from 0.40 to 0.95 for 90-day survival prediction and from 0.15 to 1.0 for 1-year prediction. The ECOG score was an independent factor associated with 90-day mortality (odds ratio 1.94 [95% CI 1.01 to 3.73]) but not 1-year mortality (OR 1.07 [95% CI 0.53 to 2.17]) after controlling for SORG-MLA predictions for 90-day and 1-year survival, respectively. Conclusion: SORG-MLAs retained good discriminatory ability in Taiwanese patients with long-bone metastases, although their actual survival time was slightly underestimated. More international validation and incremental value studies that address factors such as the ECOG score are warranted to refine the algorithms, which can be freely accessed online at https://sorg-apps.shinyapps.io/extremitymetssurvival/. Level of Evidence: Level III, therapeutic study.

Aims Guided growth has been used to treat coxa valga for cerebral palsy (CP) children. However, there has been no study on the optimal position of screw application. In this paper we have investigated the influence of screw position on the outcomes of guided growth. Methods We retrospectively analyzed 61 hips in 32 CP children who underwent proximal femoral hemi epiphysiodesis between July 2012 and September 2017. The hips were divided into two groups according to the transphyseal position of the screw in the coronal plane: across medial quarter (Group 1) or middle quarter (Group 2) of the medial half of the physis. We compared pre- and postoperative radiographs in head-shaft angle (HSA), Reimer’s migration percentage (MP), acetabular index (AI), and femoral anteversion angle (FAVA), as well as incidences of the physis growing-off the screw within two years. Linear and Cox regression analysis were conducted to identify factors related to HSA correction and risk of the physis growing-off the screw. Results A total of 37 hips in Group 1 and 24 hips in Group 2 were compared. Group 1 showed a more substantial decrease in the HSA (p = 0.003) and the MP (p = 0.032). Both groups had significant and similar improvements in the AI (p = 0.809) and the FAVA (p = 0.304). Group 1 presented a higher incidence of the physis growing-off the screw (p = 0.038). Results of the regression analysis indicated that the eccentricity of screw position correlated with HSA correction and increases the risk of the physis growing-off the screw. Conclusion Guided growth is effective in improving coxa valga and excessive femoral anteversion in CP children. For younger children, despite compromised efficacy of varus correction, we recommend a more centered screw position, at least across the middle quarter of the medial physis, to avoid early revision. Cite this article: Bone Joint J 2020;102-B(9):1242–1247.

Implant extrusion in subtalar arthroereisis is a common complication for pediatric flexible flatfoot. However, there were a limited number of articles addressing the body weight effects on implant extrusion after the procedure. We conducted a 24-month follow-up assessment after subtalar arthroereisis. Surgical patients who underwent the Vulpius procedure were retrospectively collected from May 2010 to January 2017, including 59 cases of both feet having implants in situ and 43 cases of both feet having implant extrusion. The average age of 102 patients was 9 years old. The mean body mass index (BMI) of the implant in situ group was 19.5, whilst the extrusion group was 21.2 (p = 0.035). The inter-observer correlation was excellent. There were 11 cases (39.3%) of bilateral extrusion in the overweight group (BMI ≥ 24) and 13 cases (23.2%) in the low body weight group (BMI ≤ 18.5) (p < 0.0004). Postoperative radiographic angles were corrected in both the implant in situ group and the extrusion group. Nonetheless, the implant in situ group revealed better postoperative outcomes of Meary’s angle and the talonavicular angle from an anterior-posterior view, and the talar inclination angle from a lateral view. We conclude that a higher BMI is related to implant extrusion and worse results after subtalar arthroereisis. Further prospective study to investigate whether preoperative weight loss results in improved surgical outcomes is warranted in the future.

Ulnar lengthening has gained popularity in treating forearm deformity due to hereditary multiple exostoses (HME). Whether a simultaneous radius angular correction is necessary for bowing deformity remains debatable. We aimed to evaluate effectiveness and safety of ulnar lengthening alone in HME children. HME patients with forearm deformity who underwent ulnar lengthening between 2011 and 2016 were included. Patients were divided into two groups: eight juniors (age ≤ 10 years) and six seniors (>10 years). The mean age of two groups was 8.1 ± 2.5 and 16.7 ± 4.4 years, respectively. The juniors underwent ulnar lengthening alone, and the seniors received an additional radial corrective osteotomy. Pre-operative and post-operative parameters of supination, pronation, ulnar variance (UV), radial articular angles (RAA), and carpal slip (CS) were assessed. The juniors rather the seniors had an improvement in supination (p < 0.05 and p = 0.109, respectively). The juniors and seniors improved in pronation (p < 0.05). UV, RAA, and CS were corrected in the seniors (p < 0.05). In the juniors, parameters improved in UV, RAA, and CS (p < 0.05). For HME children, ulnar lengthening alone can restore radiologic anatomy and functions, providing comparable surgical outcomes in cosmetic results and clinical parameters.

Previous epidemiological researchers have used various algorithms to identify a second hip fracture; however, there has been no validation of these algorithms to date. This study aimed to verify existing algorithms for identifying second hip fracture under the International Classification of Diseases diagnostic coding systems. Furthermore, we examined the validity of two newly proposed algorithms that integrated the concept of periprosthetic fractures and laterality of the ICD-10 coding system. Claims data of patients hospitalized for hip fracture from National Taiwan University Hospitals between 2007 and 2020 were retrieved. Hip fracture was confirmed by 2 orthopaedic surgeons with medical records and imaging data as gold standards. The validity of 9 existing and 2 newly proposed algorithms for identifying second hip fracture was evaluated. The positive predictive value (PPV) range between 84% and 90% in existing algorithms for identifying second hip fractures. Noteworthy, the longer time interval for discrimination resulted in slightly increased PPV (from 87% to 90%), while decreased sensitivity noticeably (from 87% to 72%). When considering the information about periprosthetic fracture, the PPV increased to 91% without diminished sensitivity. The PPV of the newly proposed ICD-10-specific algorithm was 100%. Algorithms integrated clinical insights of periprosthetic fractures and laterality concept of ICD-10 coding system provided satisfactory validity and help precisely define second hip fracture in future database research.

For pediatric flexible flatfoot, the subtalar extra-articular screw arthroereisis (SESA) and endosinotarsal device are the most popular techniques in current practice. Nevertheless, scarce literature is available comparing the outcomes between these two techniques. Thus, we aimed to provide a meta-analysis for the radiographic and clinical outcomes, respectively. A systemic search for correction of pediatric flexible flatfoot using subtalar arthroereisis was conducted mainly in Pubmed and Scopus, and the search was completed on 31 Dec., 2019. The standardized mean differences (SMD) of postoperative versus preoperative calcaneal pitch and Meary’s angle were defined as the primary outcomes, whereas the preoperative versus posteoperative AOFAS (American Orthopaedic Foot and Ankle Society) as the secondary outcome. The meta-analysis included 12 comparative studies comprising 2063 feet in total. The quantitative analysis showed a marked improvement in Meary’s angle of endosinotarsal cone implant group (SMD: 4.298; 95% CI 2.706–5.889) than exosinotarsal screw group (SMD: 1.264; 95% CI 0.650–1.877). But no significant difference was noted between both groups in calcaneal pitch and AOFAS. The exosinotarsal screw and endosinotarsal device are both effective arthroereisis implant for pediatric flexible flatfoot. While considering the correction of Meary’s angle, the endosinotarsal device is better than exosinotarsal screw.