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Survival in patients who have Ewing sarcoma is correlated with postchemotherapy response (tumor necrosis). This treatment response has been categorized as the response rate, similar to what has been used in osteosarcoma. There is controversy regarding whether this is appropriate or whether it should be a dichotomy of complete versus incomplete response, given how important a complete response is for in overall survival of patients with Ewing sarcoma. The purpose of this study was to evaluate the impact that the amount of chemotherapy-induced necrosis has on (1) overall survival, (2) local recurrence-free survival, (3) metastasis-free survival, and (4) event-free survival in patients with Ewing sarcoma.In total, 427 patients who had Ewing sarcoma or tumors in the Ewing sarcoma family and received treatment with preoperative chemotherapy and surgery at 10 international institutions were included. Multivariate Cox proportional-hazards analyses were used to assess the associations between tumor necrosis and all four outcomes while controlling for clinical factors identified in bivariate analysis, including age, tumor volume, location, surgical margins, metastatic disease at presentation, and preoperative radiotherapy.Patients who had a complete (100%) tumor response to chemotherapy had increased overall survival (hazard ratio [HR], 0.26; 95% CI, 0.14-0.48; p .01), recurrence-free survival (HR, 0.40; 95% CI, 0.20-0.82; p = .01), metastasis-free survival (HR, 0.27; 95% CI, 0.15-0.46; p ≤ .01), and event-free survival (HR, 0.26; 95% CI, 0.16-0.41; p ≤ .01) compared with patients who had a partial (0%-99%) response.Complete tumor necrosis should be the index parameter to grade response to treatment as satisfactory in patients with Ewing sarcoma. Any viable tumor in these patients after neoadjuvant treatment should be of oncologic concern. These findings can affect the design of new clinical trials and the risk-stratified application of conventional or novel treatments.

Lower extremity amputations are common, and postoperative neuropathic pain (phantom limb pain or symptomatic neuroma) is frequently reported. The use of active treatment of the nerve end has been shown to reduce pain but requires additional resources and should therefore be performed primarily in high-risk patients. The aim of this study was to identify the factors associated with the development of neuropathic pain following above-the-knee amputation, knee disarticulation, or below-the-knee amputation.Retrospectively, 1565 patients with an average follow-up of 4.3 years who underwent a primary above-the-knee amputation, knee disarticulation, or below-the-knee amputation were identified. Amputation levels for above-the-knee amputations and knee disarticulations were combined as proximal amputation level, with below-the-knee amputations being performed in 61 percent of patients. The primary outcome was neuropathic pain (i.e., phantom limb pain or symptomatic neuroma) based on medical chart review. Multivariable logistic regression was performed to identify independent factors associated with neuropathic pain.Postoperative neuropathic pain was present in 584 patients (37 percent), with phantom limb pain occurring in 34 percent of patients and symptomatic neuromas occurring in 3.8 percent of patients. Proximal amputation level, normal creatinine levels, and a history of psychiatric disease were associated with neuropathic pain. Diabetes, hypothyroidism, and older age were associated with lower odds of developing neuropathic pain.Neuropathic pain following lower extremity amputation is common. Factors influencing nerve regeneration, either increasing (proximal amputations and younger age) or decreasing (diabetes, hypothyroidism, and chronic kidney disease) it, play a role in the development of postamputation neuropathic pain.Risk, III.

Background Local recurrence of microinvasive sarcoma or benign aggressive pathologies can be limb- and life-threatening. Although frozen pathology is reliable, tumor microinvasion can be subtle or missed, having an impact on surgical margins and postoperative radiation planning. The authors' service has begun to temporize the tumor bed after primary tumor excision with a wound vacuum-assisted closure (VAC) pending formal margin analysis, with coverage performed in the setting of final negative margins. Methods This retrospective analysis included all patients managed at a tertiary referral cancer center with VAC temporization after soft tissue sarcoma or benign aggressive tumor excision from 1 January 2000 to 1 January 2019 and at least 2 years of oncologic follow-up evaluation. The primary outcome was local recurrence. The secondary outcomes were distant recurrence, unplanned return to the operating room for wound/infectious indications, thromboembolic events, and tumor-related deaths. Results For 62 patients, VAC temporization was performed. The mean age of the patients was 62.2 ± 22.3 years (median 66.5 years; 95% confidence interval [CI] 61.7-72.5 years), and the mean age-adjusted Charlson Comorbidity Index was 5.3 ± 1.9. The most common tumor histology was myxofibrosarcoma (51.6%, 32/62). The mean volume was 124.8 ± 324.1 cm3, and 35.5% (22/62) of the cases were subfascial. Local recurrences occurred for 8.1% (5/62) of the patients. Three of these five patients had planned positive margins, and 17.7% (11/62) of the patients had an unplanned return to the operating room. No demographic or tumor factors were associated with unplanned surgery. Conclusions The findings showed that VAC-temporized management of microinvasive sarcoma and benign aggressive pathologies yields favorable local recurrence and unplanned operating room rates suggestive of oncologic and technical safety. These findings will need validation in a future randomized controlled trial.

Introduction The aim of this study was to describe patient characteristics, treatment, and oncologic outcomes of soft-tissue sarcomas (STSs) of the hand. Methods Sixty-nine STSs of the hand in adult patients treated at a tertiary referral center were retrospectively included. We describe patient and tumor characteristics along with oncologic outcomes. Results Epithelioid sarcoma (23%) was the most common histologic subtype, followed by synovial sarcoma (15%). Of all tumors, 17 (25%) were grade I, 22 (32%) were grade II, and 30 (44%) were grade III. The 5-year disease-free survival for epithelioid sarcomas was 75% with a disease survival of 100%, along with a metastatic rate of 15%. Of the patients with a synovial sarcoma, 40% developed metastases, and the 5-year disease-free survival was 68% and the 5-year disease survival was 73%. Conclusion Hand STSs are aggressive tumors with a high metastatic potential. Even with adequate oncologic treatment, long-term clinical follow-up (10 years) in these tumors is advised. The treating surgical oncologist should not be deceived by their smaller size.

Background The aims of this study are to evaluate the rate of wrist joint preservation, allograft retention, factors associated with reoperation and to report the patient reported outcomes after osteoarticular allograft reconstruction of the distal radius. Methods Retrospective chart review identified 33 patients who underwent distal radius resection followed by osteoarticular allograft reconstruction, including 27 giant cell tumors and 6 primary malignancies. Ten patients with a preserved wrist joint completed the QuickDASH, PROMIS-CA physical function, and Toronto extremity salvage score (TESS) at a median of 13 years postoperatively. Results The allograft retention rate was 89%, and an allograft fracture predisposed to conversion to wrist arthrodesis. The reoperation rate was 55% and 36% underwent wrist arthrodesis at a median of 4.2 years following index surgery. The use of locking plate fixation was associated with lower reoperation and allograft fracture rates. Patients reported a median QuickDASH of 10.2 (range: 0-52.3), a mean PROMIS physical function of 57.8 (range: 38.9-64.5) and the median TESS was 95.5 (range: 67.0-98.4). Conclusion Osteoarticular allograft reconstruction results in acceptable long-term patient reported outcomes, despite a high revision rate. Allograft fixation with locking plates seems to reduce the number of reoperations and allograft fractures, along with reduction in wrist arthrodesis rates.

Purpose Giant cell tumors (GCT) of the distal radius are thought to be more aggressive than in other locations. Therefore, the aim of this study was to investigate factors associated with recurrence of GCTs in the upper extremity. Methods We retrospectively identified 82 patients who underwent primary surgical treatment for an upper extremity GCT. Tumors were located in the radius (n = 47), humerus (n = 17), ulna (n = 9), and hand (n = 9). Treatment consisted of either wide resection or amputation or intralesional resection with or without adjuvants. A multivariable logistic regression was performed including tumor grade, type of surgery, and tumor location, from which the percentage of contribution to the model of each variable was calculated. Results The recurrence rate after intralesional resection was 48%; after wide resection or amputation, it was 12%. Two patients developed a pulmonary metastasis (2.4%). In multivariable analysis, intralesional resection was independently associated with recurrence. Intralesional resection had a 77% contribution to predict recurrence and the distal radius location had a 16% contribution in the predictive model. Conclusions As expected, intralesional resection was the strongest independent predictor of recurrence after surgical treatment for GCT. The distal radius location contributed to the prediction of giant cell tumor recurrence to a lesser extent. Type of study/level of evidence Prognostic IV.

Background and objectives Mechanical augmentation with metal implants in the treatment of bone tumors limits magnetic resonance imaging and computerized tomography scan imaging due to the scattering effect. In addition, modulus of elasticity differences may cause chronic pain. We present a surgical technique in which cortical allografts are used as plates. This is a two-center experience focusing on functional and radiographic outcomes and complications. Methods Under IRB approval, we performed a retrospective patient review. Demographics, treatment indications, tumor characteristics, and complications were collected. Radiographic studies were reviewed to determine the time to osseous incorporation. The last follow-up functional evaluation included the Musculoskeletal Tumor Society (MSTS) score, the Karnofsky scale, and Eastern Cooperative Oncology Group (ECOG). Results Thirty patients, seventeen female and thirteen male, 16-year-old in average were included. The most common diagnoses were the humeral aneurysmal bone cyst and unicameral bone cyst. The Median follow-up was 6 years. Cortical allograft incorporation median time was 8.8 months whereas allograft void bone incorporation was 3 months. The average time to full weight-bearing without impact activity was 3.1 months. The most common complication was symptomatic hardware. Other complications included a superficial infection successfully treated with antibiotics, a temporary radial nerve neuropraxia, and an allograft fracture requiring revision surgery. Most patients had an MSTS score higher than 90 (excellent). Patients with malignant tumors had ECOG of 0 and a Karnofsky score of 100. Conclusion Biological osteosynthesis is a bone preserving and effective modality for mechanical augmentation with excellent functional results and low complication rates.

The use of denosumab to treat giant cell tumors of bone (GCT) and other giant cell-containing bone tumors has become more common. While the clinicopathologic features of denosumab-treated giant cell tumors of bone have been well-illustrated, descriptions of other denosumab-treated bone tumors are very limited. Surgical pathology files of two institutions and consultation files from two authors were searched for denosumab-treated aneurysmal bone cysts and denosumab-treated osteoblastomas. Clinicopathologic features were reviewed and analyzed. We identified four patients with denosumab-treated bone tumors other than GCT from our surgical pathology and consultation files, including two aneurysmal bone cysts and two osteoblastomas. All were treated with denosumab for 0.5-7.0 (median 4.5) months. Radiologically, denosumab-treated tumors showed decreased size with increased ossification and mineralization on CT and heterogeneous intermediate to hypointense signal on MRI. Histologically, denosumab-treated aneurysmal bone cyst contained thin, elongated, curvilinear, and anastomosing strands of bone with empty lacunae, while denosumab-treated osteoblastoma showed circumscribed nodules of woven bone lined by small osteoblasts. Denosumab-treated aneurysmal bone cyst and osteoblastoma showed treatment-related morphologic changes that can mimic other bone neoplasms. Their recognition requires correlation with the clinical history of denosumab use and radiologic findings.

BackgroundDesmoid tumors of the extremities often present with pain and functional limitation, but treatment can lead to morbidity and recurrence is common. The impact of treatment with respect to traditional “oncologic” metrics (such as recurrence rate) has been studied extensively, with a

BACKGROUND We developed a machine learning algorithm to predict the survival of patients with chondrosarcoma. The algorithm demonstrated excellent discrimination and calibration on internal validation in a derivation cohort based on data from the Surveillance, Epidemiology, and End Results (SEER) registry. However, the algorithm has not been validated in an independent external dataset. QUESTIONS/PURPOSES Does the Skeletal Oncology Research Group (SORG) algorithm accurately predict 5-year survival in an independent patient population surgically treated for chondrosarcoma? METHODS The SORG algorithm was developed using the SEER registry, which contains demographic data, tumor characteristics, treatment, and outcome values; and includes approximately 30% of the cancer patients in the United States. The SEER registry was ideal for creating the derivation cohort, and consequently the SORG algorithm, because of the high number of eligible patients and the availability of most (explanatory) variables of interest. Between 1992 to 2013, 326 patients were treated surgically for extracranial chondrosarcoma of the bone at two tertiary care referral centers. Of those, 179 were accounted for at a minimum of 5 years after diagnosis in a clinical note at one of the two institutions, unless they died earlier, and were included in the validation cohort. In all, 147 (45%) did not meet the minimum 5 years of followup at the institution and were not included in the validation of the SORG algorithm. The outcome (survival at 5 years) was checked for all 326 patients in the Social Security death index and were included in the supplemental validation cohort, to also ascertain validity for patients with less than 5 years of institutional followup. Variables used in the SORG algorithm to predict 5-year survival including sex, age, histologic subtype, tumor grade, tumor size, tumor extension, and tumor location were collected manually from medical records. The tumor characteristics were collected from the postoperative musculoskeletal pathology report. Predicted probabilities of 5-year survival were calculated for each patient in the validation cohort using the SORG algorithm, followed by an assessment of performance using the same metrics as used for internal validation, namely: discrimination, calibration, and overall performance. Discrimination was calculated using the concordance statistic (or the area under the Receiver Operating Characteristic (ROC) curve) to determine how well the algorithm discriminates between the outcome, which ranges from 0.5 (no better than a coin-toss) to 1.0 (perfect discrimination). Calibration was assessed using the calibration slope and intercept from a calibration plot to measure the agreement between predicted and observed outcomes. A perfect calibration plot should show a 45° upwards line. Overall performance was determined using the Brier score, ranging from 0 (excellent prediction) to 1 (worst prediction). The Brier score was compared with the null-model Brier score, which showed the performance of a model that ignored all the covariates. A Brier score lower than the null model Brier score indicated greater performance of the algorithm. For the external validation an F1-score was added to measure the overall accuracy of the algorithm, which ranges between 0 (total failure of an algorithm) and 1 (perfect algorithm).The 5-year survival was lower in the validation cohort than it was in the derivation cohort from SEER (61.5% [110 of 179] versus 76% [1131 of 1544] ; p < 0.001). This difference was driven by higher proportion of dedifferentiated chondrosarcoma in the institutional population than in the derivation cohort (27% [49 of 179] versus 9% [131 of 1544]; p < 0.001). Patients in the validation cohort also had larger tumor sizes, higher grades, and nonextremity tumor locations than did those in the derivation cohort. These differences between the study groups emphasize that the external validation is performed not only in a different patient cohort, but also in terms of disease characteristics. Five-year survival was not different for both patient groups between subpopulations of patients with conventional chondrosarcomas and those with dedifferentiated chondrosarcomas. RESULTS The concordance statistic for the validation cohort was 0.87 (95% CI, 0.80-0.91). Evaluation of the algorithm's calibration in the institutional population resulted in a calibration slope of 0.97 (95% CI, 0.68-1.3) and calibration intercept of -0.58 (95% CI, -0.20 to -0.97). Finally, on overall performance, the algorithm had a Brier score of 0.152 compared with a null-model Brier score of 0.237 for a high level of overall performance. The F1-score was 0.836. For the supplementary validation in the total of 326 patients, the SORG algorithm had a validation of 0.89 (95% CI, 0.85-0.93). The calibration slope was 1.13 (95% CI, 0.87-1.39) and the calibration intercept was -0.26 (95% CI, -0.57 to 0.06). The Brier score was 0.11, with a null-model Brier score of 0.19. The F1-score was 0.901. CONCLUSIONS On external validation, the SORG algorithm retained good discriminative ability and overall performance but overestimated 5-year survival in patients surgically treated for chondrosarcoma. This internet-based tool can help guide patient counseling and shared decision making. LEVEL OF EVIDENCE Level III, prognostic study.

Carbon fiber offers numerous material benefits including reduced wear, high strength-to-weight ratio, a similar elastic modulus to that of bone, and high biocompatibility. Carbon fiber implants are increasingly used in multiple arenas within orthopaedic surgery, including spine, trauma, arthroplasty, and oncology. In the orthopaedic oncologic population, the radiolucency of carbon fiber facilitates post-operative imaging for tumor surveillance or recurrence, the monitoring of bony healing and union, and radiation mapping and delivery.

Sarcoma diagnosis has become increasingly complex, requiring a combination of morphology, immunohistochemistry, and molecular studies to derive specific diagnoses. We evaluated the role of anchored multiplex polymerase chain reaction-based gene fusion assay in sarcoma diagnostics. Between 2015 and 2018, bone and soft tissue sarcomas with fusion assay results were compared with the histologic diagnosis. Of 143 sarcomas tested for fusions, 43 (30%) had a detectable fusion. In review, they could be classified into 2 main categories: (1) 31 tumors with concordant morphologic and fusion data; and (2) 12 tumors where the fusion panel identified an unexpected rearrangement that played a significant role in classification. The overall concordance of the fusion assay results with morphology/immunohistochemistry or alternate confirmatory molecular studies was 83%. Collectively, anchored multiplex polymerase chain reaction-based solid fusion assay represents a robust means of detecting targeted fusions with known and novel partners. The predictive value of the panel is highest in tumors that show a monomorphic cell population, round cell tumors, as well as tumors rich in inflammatory cells. However, with an increased ability to discover fusions of uncertain significance, it remains essential to emphasize that the diagnosis of bone and soft tissue neoplasms requires the integration of morphology and immunohistochemical profile with these molecular methods, for accurate diagnosis and optimal clinical management of sarcomas.

Local recurrence of microinvasive sarcoma or benign aggressive pathologies can be limb- and life-threatening. Although frozen pathology is reliable, tumor microinvasion can be subtle or missed, having an impact on surgical margins and postoperative radiation planning. The authors' service has begun to temporize the tumor bed after primary tumor excision with a wound vacuum-assisted closure (VAC) pending formal margin analysis, with coverage performed in the setting of final negative margins.This retrospective analysis included all patients managed at a tertiary referral cancer center with VAC temporization after soft tissue sarcoma or benign aggressive tumor excision from 1 January 2000 to 1 January 2019 and at least 2 years of oncologic follow-up evaluation. The primary outcome was local recurrence. The secondary outcomes were distant recurrence, unplanned return to the operating room for wound/infectious indications, thromboembolic events, and tumor-related deaths.For 62 patients, VAC temporization was performed. The mean age of the patients was 62.2 ± 22.3 years (median 66.5 years; 95% confidence interval [CI] 61.7-72.5 years), and the mean age-adjusted Charlson Comorbidity Index was 5.3 ± 1.9. The most common tumor histology was myxofibrosarcoma (51.6%, 32/62). The mean volume was 124.8 ± 324.1 cmThe findings showed that VAC-temporized management of microinvasive sarcoma and benign aggressive pathologies yields favorable local recurrence and unplanned operating room rates suggestive of oncologic and technical safety. These findings will need validation in a future randomized controlled trial.

The microinvasive nature of suprafascial myxofibrosarcoma reduces the accuracy of intraoperative margin assessment, and tumor bed resections after soft-tissue reconstruction are unreliable. In 2017, we began temporizing the excised tumor bed with a wound VAC, delaying soft-tissue coverage until final negative margins were achieved. We compare the oncologic/surgical outcomes of suprafascial myxofibrosarcomas managed with VAC temporization (VT) with single-stage excision/reconstruction (SS).We retrospectively studied suprafascial myxofibrosarcomas managed from January 1, 2000 to January 1, 2019 for patients who received neoadjuvant or adjuvant radiation and had at least 2 years of oncologic follow-up at a tertiary referral cancer center. Our primary outcome was local recurrence. Comparisons were performed by using Fisher's exact test or Student's t test. A p value0.05 was considered significant.Fifty-three patients (18 VAC temporized, 35 single stage) were included. While VT patients were older (74.9 ± 10.2 vs. 63.9 ± 13.6, p = 0.003), treatment groups did not significantly differ with respect to comorbidity, tumor volume, stage and grade. VT patients had significantly fewer local recurrences (5.6% vs. 28.6% after SS, p = 0.048) and R1 resections that required an unplanned readmission for tumor bed reexcision (0% vs. 37.1% after SS, p = 0.002). VT required more total surgeries (2.8 ± 0.9 vs. 1.8 ± 0.9 for SS, p = 0.0002). Postoperative infectious and wound complications were equivalent.Our VAC temporization strategy had a significantly lower LR than SS treatment. While high quality multi-institutional validation is required, VT may represent a paradigm shift in the management of myxofibrosarcoma.

Background and objectives Malignant tumors of the calcaneus are rare but pose a treatment challenge. Aims (1) describe the demographics of calcaneal malignancies in a large cohort; (2) describe survival after amputation versus limb-salvage surgery for high-grade tumors. Methods Study group: a "pooled" cohort of patients with primary calcaneal malignancies treated at two cancer centers (1984-2015) and systematic literature review. Kaplan-Meier analyses described survival across treatment and diagnostic groups; proportional hazards modeling assessed mortality after amputation versus limb salvage. Results A total of 131 patients (11 treated at our centers and 120 patients from 53 published studies) with a median 36-month follow-up were included. Diagnoses included Ewing sarcoma (41%), osteosarcoma (30%), and chondrosarcoma (17%); 5-year survival rates were 43%, 73% (70%, high grade only), and 84% (60%, high grade only), respectively. Treatment involved amputation in 52%, limb salvage in 27%, and no surgery in 21%. There was no difference in mortality following limb salvage surgery (vs. amputation) for high-grade tumors (HR 0.38; 95% CI 0.14-1.05), after adjusting for Ewing sarcoma diagnosis (HR 5.15; 95% CI 1.55-17.14), metastatic disease at diagnosis (HR 3.88; 95% CI 1.29-11.64), and age (per-year HR 1.04; 95% CI 1.02-1.07). Conclusions Limb salvage is oncologically-feasible for calcaneal malignancies.

BACKGROUND: The benefits of surgical treatment of a metastasis of the extremities may be offset by drawbacks such as potential postoperative complications. For this group of patients, the primary goal of surgery is to improve quality of life in a palliative setting. A better comprehension of factors associated with complications and the impact of postoperative complications on mortality may prevent negative outcomes and help surgeons in surgical decision-making. QUESTIONS/PURPOSES: (1) What is the risk of 30-day postoperative complications after surgical treatment of osseous metastatic disease of the extremities? (2) What predisposing factors are associated with a higher risk of 30-day complications? (3) Are minor and major 30-day complications associated with higher mortality at 1 year? METHODS: Between 1999 and 2016, 1090 patients with osseous metastatic disease of the long bones treated surgically at our institution were retrospectively included in the study. Surgery included intramedullary nailing (58%), endoprosthetic reconstruction (22%), plate-screw fixation (14%), dynamic hip screw fixation (2%), and combined approaches (4%). Surgery was performed if patients were deemed healthy enough to proceed to surgery and wished to undergo surgery. All data were retrieved by manually reviewing patients' records. The overall frequency of complications, which were defined using the Clavien-Dindo classification system, was calculated. We did not include Grade I complications as postoperative complications and complications were divided into minor (Grade II) and major (Grades III-V) complications. A multivariate logistic regression analysis was used to identify factors associated with 30-day postoperative complications. A Cox regression analysis was used to assess the association between postoperative complications and overall survival. RESULTS: Overall, 31% of the patients (333 of 1090) had a postoperative complication within 30 days. The following factors were independently associated with 30-day postoperative complications: rapidly growing primary tumors classified according to the modified Katagiri classification (odds ratio 1.6; 95% confidence interval, 1.1-2.2; p = 0.011), multiple bone metastases (OR 1.6; 95% CI, 1.1-2.3; p = 0.008), pathologic fracture (OR 1.5; 95% CI, 1.1-2.0; p = 0.010), lower-extremity location (OR 2.2; 95% CI, 1.6-3.2; p < 0.001), hypoalbuminemia (OR 1.7; 95% CI, 1.2-2.4; p = 0.002), hyponatremia (OR 1.5; 95% CI, 1.0-2.2; p = 0.044), and elevated white blood cell count (OR 1.6; 95% CI, 1.1-2.4; p = 0.007). Minor and major postoperative complications within 30 days after surgery were both associated with greater 1-year mortality (hazard ratio 1.6; 95% CI, 1.3-1.8; p < 0.001 and HR 3.4; 95% CI, 2.8-4.2, respectively; p < 0.001). CONCLUSION: Patients with metastatic disease in the long bones are vulnerable to postoperative adverse events. When selecting patients for surgery, surgeons should carefully assess a patient's cancer status, and several preoperative laboratory values should be part of the standard work-up before surgery. Furthermore, 30-day postoperative complications decrease survival within 1 year after surgery. Therefore, patients at a high risk of having postoperative complications are less likely to profit from surgery and should be considered for nonoperative treatment or be monitored closely after surgery. LEVEL OF EVIDENCE: Level III, therapeutic study.

Primary epithelial cancers can metastasize to distant organs of the body through hematogenous or lymphatic spread. Bone is the third most common metastatic site after the lung and liver. In fact, metastatic cancer is the most common malignancy of bone overall. Of the cancers that spread to bone, approximately 80% of bone metastases are caused by either prostate, breast, kidney, lung, or thyroid cancer [1]. The pelvis is the second most common osseous metastasis site after the spine and of all pelvic metastases; the most common sites are the ilium, ischium, and pubis, in descending order of frequency [2].

BackgroundSeveral studies have identified prognostic factors for patients with chondrosarcoma, but there are few studies investigating the accuracy of computationally intensive methods such as machine learning. Machine learning is a type of artificial intelligence that enables computers to l

Background The main reconstruction techniques for proximal humerus tumors include osteoarticular allografts (OAs), endoprostheses (EPs), or allograft prosthetic composites (APCs). A common complication is infection, and constructs involving the use of allografts are believed to be at a higher risk of infection. Literature comparing infection rates between different modalities of reconstruction is scarce and underpowered. The study purposes were (1) to determine and compare the prevalence of infection in patients who underwent reconstruction of the proximal humerus including OAs, EPs, and APCs; (2) to identify preoperative, perioperative, and postoperative predictors of infection that might be modifiable; and (3) to present our protocol of treatment in patients with superficial and deep infections. Methods We reviewed 150 patients of all ages with proximal humerus tumors treated by an OA, EP, or APC at 2 tertiary institutions. The prevalence of infection for each modality was calculated and compared between groups. We identified potential predictors of infection with stepwise backward multivariate Cox regression analysis. Results An infection developed in 19 patients (12%): 5 of 45 (11%) in the OA group, 12 of 85 (14%) in the EP group, and 2 of 20 (10%) in the APC group ( P = .740). A lower preoperative hemoglobin blood level and low preoperative albumin blood level were independently associated with infection. Conclusions We found similar infection rates compared with previously reported series. However, we did not identify a higher infection prevalence in constructs using allografts. Patients with a lower preoperative hemoglobin or albumin level are at higher risk of infection and should undergo optimization before surgery.

Background MicroRNAs are small, noncoding RNAs that regulate the expression of posttranslational genes. The presence of some specific microRNAs has been associated with increased risk of both local recurrence and metastasis and worse survival in patients with osteosarcoma. Pathologic fractures in osteosarcoma are considered to be more the manifestation of a neoplasm with a more aggressive biological behavior than the cause itself of worse prognosis. However, this has not been proved at the biological or molecular level. Currently, there has not been a microRNA profiling study of patients who have osteosarcoma with and without pathologic fractures that has described differences in terms of microRNA profiling between these two groups and their correlation with biologic behavior. Questions/purposes (1) In patients with osteosarcoma of the extremities, how do the microRNA profiles of those with and without pathologic fractures compare? (2) What relationship do microRNAs have with local recurrence, risk of metastasis, disease-specific survival, and overall survival in osteosarcoma patients with pathologic fractures? Methods Between 1994 and 2013, 217 patients were diagnosed and treated at our institution for osteosarcoma of the extremities. Patients were excluded if (1) they underwent oncologic resection of the osteosarcoma at an outside institution (two patients) or (2) they were diagnosed with an extraskeletal osteosarcoma (29 patients) or (3) they had less than 1 year of clinical follow-up and no oncologic outcome (local recurrence, metastasis, or death) (four patients). A total of 182 patients were eligible. Of those, 143 were high-grade osteosarcomas. After evaluation of tumor samples before chemotherapy treatment, a total of 80 consecutive samples were selected for sequencing. Demographic and clinical comparison between the sequenced and non-sequenced patients did not demonstrate any differences, confirming that both groups were comparable. Diagnostic samples from the extremities of 80 patients with high-grade extremity osteosarcomas who had not yet received chemotherapy underwent microRNA sequencing for an ongoing large-scale osteosarcoma genome profiling project at our institution. Six samples were removed after a second look by a musculoskeletal pathologist who verified cellularity and quality of samples to be sequenced, leaving a total of 74 patients. Of these, two samples were removed as they were confirmed to be pelvic tumors in a second check after sequencing. The final study sample was 72 patients (11 patients with pathologic fractures and 61 without). Sequencing data were correlated with fractures and local recurrence, risk of metastasis, disease-specific survival, and overall survival through Kaplan-Meier analyses. Results Several microRNAs were expressed differently between the two groups. Among the markers with the highest differential expression (edgeR and DESeq algorithms), Hsa-mIR 656-3p, hsa-miR 493-5p, and hsa-miR 381-3p were upregulated in patients with pathologic fractures, whereas hsa-miR 363, hsa-miR 885-5p, and has-miR 20b-5p were downregulated. The highest differential expression fracture and nonfracture-associated microRNA markers also distinguished groups of patients with different metastasis risk, a well as different disease-specific and overall survival. Furthermore, the profile of pathologic fractures demonstrated a higher differential expression for microRNA markers that were previously associated with a higher risk of metastasis and lower survival rates in patients with osteosarcoma. Conclusions In patients who have osteosarcoma, the microRNA profiles of those with pathologic fractures are different than of patients without pathologic fractures. The highest differential expression mircroRNA molecules in patients with pathologic fractures predict also higher risk of metastatic disease as well as worse disease-specific survival and overall survival. Furthermore, we found higher differential expression of microRNAs in the pathologic fracture group previously associated with poor prognosis. The higher risk of metastasis and poorer overall survival in patients with pathologic fractures is inherent to tumor aggressive biologic behavior. It is plausible that the fracture itself is not the direct cause of worse prognosis but another manifestation of tumor biologic aggressiveness. Identification of these molecules through liquid biopsies may help to determine which patients may benefit from surgery before fractures occur. The same technology can be applied to identify patterns of response to conventional chemotherapy, assisting in more specific and accurate systemic therapy. Level of evidence level III, prognostic study.

Background: To describe the rate and predictors of pathologic fractures in benign neoplasms of the finger, as variables from prediction models for pathologic fractures of the long bones of the extremities are not necessarily applicable to the bones of the hand. Methods: In this retrospective chart review, 69 histologically confirmed neoplasms affecting the bones of the fingers, 49 phalanges and 20 metacarpals, were identified in patients presenting at 2 urban hospitals over a 24-year period. Different variables were studied as possible predictors of pathologic fractures. Results: Forty-nine percent of the tumors presented as a pathologic fracture. The small finger was independently associated with pathologic fractures compared to the other fingers. Tumors of the metacarpal bones were the least likely to fracture compared to other bones. Conclusions: Almost half of neoplasms affecting the bones of the fingers presented initially with a pathologic fracture, most commonly the small finger. Therefore, a lower threshold for surgical treatment of a bone neoplasm affecting the small finger may be reasonable.

e23505 Background: Chordomas are malignant tumors arising from remnant notochordal tissue. Despite improved local control with preoperative/postoperative RT, progression-free survival and OS remain poor in patients (pts) with high-risk features. Chordoma has been identified to express and activate platelet-derived growth factor receptor signaling. We conducted a phase 1 trial to identify the maximum tolerated dose (MTD), safety, and feasibility of nilotinib with RT as either preoperative or definitive treatment for patients with high-risk chordoma. Enclosed is an updated report on LC, MFS, and OS. Methods: We recruited 23 pts with nonmetastatic chordoma to the phase I and dose expansion arms of the study. High-risk was defined as the presence of any of the following: local recurrence after surgery, previous intralesional resection, unplanned incomplete resection, unresectable/marginally resectable disease, or declining surgery due to excessive morbidity. Pts were treated with nilotinib and concurrent RT to 50.4 Gy relative biological effectiveness (RBE) followed by surgery and postoperative RT to a cumulative dose up to 70.2 Gy RBE or definitively up to 77.4 Gy RBE without surgery. On completion of RT, pts were eligible to continue nilotinib until disease progression. Results: The dose escalation arm of the study identified nilotinib 200 mg daily as the maximum tolerated dose (MTD). Eighteen evaluable pts were treated with nilotinib plus RT at the MTD. The objective best response rate was 6% (1 of 18 pts). The 4 and 5-year LC rates were 94.3% (95% CI 83.2-100) and 70.7% (95% CI 20.8-100), respectively. The MFS rate was 74.3 at 4 and 5 years (95% CI 51.8-96.7). The 4 and 5-year OS rates were 70.2% (95% CI 44.4-95.9) and 54.6% (95% CI 20.5-88.6). Conclusions: In updated data from a cohort of high-risk chordoma pts nilotinib 200 mg/d with RT +/- surgery, with long-term follow-up, local control and distant metastasis free survival remains favorable. Clinical trial information: NCT01407198 . [Table: see text]

The megaprosthesis is designed to reproduce the form and function of a removed or lost large segment of bone and accompanying soft tissues. Slow but substantial improvements in the design and surgical implementation of these devices have advanced the capacity to restore patients' functional abilities. The essential challenges include identifying the ideal materials, bonding these materials to bone and soft tissues, reproducing functional anatomy, and adapting to the growing skeleton. Failure of these devices can result from soft-tissue insufficiency, aseptic loosening, structural failures, infection, and tumor recurrence. The history of the use of megaprostheses in the pelvis, proximal femur, distal femur, total femur, and proximal tibia has shown that each anatomic area presents unique challenges. Improvements that have been made over the years will guide the development of the next generation of devices. Despite early high complication rates, these devices are a reasonable choice in the right patient.

Advanced imaging has demonstrated that musculoskeletal manifestations of systemic sarcoidosis are more common than previously thought. A definitive strategy for the management of osseous sarcoidosis has not been defined. Some lesions resolve spontaneously, and no systemic medication for sarcoidosis consistently resolves lesions. The orthopaedic surgeon treating patients with musculoskeletal sarcoidosis must make an appropriate diagnosis of bony lesions, seek multidisciplinary input from specialists in pulmonology and rheumatology regarding systemic treatment, and decide when surgery is necessary to prevent dysfunction.

Background and objectives Synovial sarcoma is a rare soft tissue sarcoma with poor long-term prognosis due to late recurrence and metastasis. Synovial sarcoma arises in less than 6% from the shoulder. As a result, there is limited information in the literature about synovial sarcoma of the shoulder (SSS). Methods We included all patients treated for SSS at our institution between 1985 and 2013. Medical charts were retrospectively reviewed to collect demographics, information about the clinical course, and outcome. This subgroup was compared to our institution's entire synovial sarcoma patient cohort and the data in the published literature. Results SSS Patients presented most commonly with pain and a growing mass; the majority of tumors were grade 2 and measured greater than 5 cm. 43% (7) of SSS patients developed metastatic disease and 36% (5) had died at a median follow-up of 64 months (36-127); SSS 5-year survival (83.3%) was higher in our series than in the general literature (57-75%). Conclusions We found better prognosis in patients with synovial sarcoma of the shoulder than expected based on the current literature. The clinical behavior of synovial sarcoma in the shoulder is closer to that of synovial sarcoma in the extremities than the trunk. Level of evidence Level IV, Case Series.

To assess, (i) the degree to which the: PROMIS Physical Function Cancer, PROMIS Neuro-QoL Mobility, Toronto Extremity Salvage Score (TESS), Lower Extremity Function Score (LEFS), and Musculoskeletal Tumor Society score (MSTS), measure physical function; (ii) differences in coverage and reliability; and (iii) difference in completion time.One hundred of 115 (87%) patients with lower extremity metastases participated in this prospective study. We used exploratory factor analysis-correlating questionnaires with an underlying trait-to assess if questionnaires measure the same. Coverage was assessed by floor and ceiling effect and reliability by the standard error of measurement (SEM). Completion time was compared using the Friedman test.All questionnaires measured the same concept; demonstrated by high correlations (0.7). Floor effect was absent, while ceiling effect was present in all, but highest for the PROMIS Neuro-QoL Mobility (7%). The SEM was below the threshold-indicating reliability-over a wide range of ability levels for the PROMIS-Physical Function, TESS, and LEFS. Completion time differed between questionnaires (P 0.001) and was shortest for the PROMIS questionnaires.The PROMIS Physical Function is the most useful questionnaire. This is due to its reliability over a wide range of ability levels, validity, brevity, and good coverage. J. Surg. Oncol. 2016;114:691-696. © 2016 Wiley Periodicals, Inc.

Background: Ankle arthroscopy has evolved as a diagnostic and therapeutic tool. Traditionally, it is performed with traction because of the tight ankle joint space. Original traction techniques were invasive but have progressed to the commonly used noninvasive modalities. Recent reports have suggested traction may be unnecessary. The purpose of this study was to compare prospectively ankle arthroscopy with and without traction in terms of ease of visualization of anatomic structures according to the Ferkel's ankle arthroscopy criteria. Methods: Under Institutional Review Board approval, 103 patients received ankle arthroscopies, first with noninvasive traction and subsequently without traction. An independent observer scored each arthroscopy based on the 21-point Ferkel's criteria. For each structure adequately visualized, one point was given. Inadequate visualization was defined as excessive force or as visible cartilage scuffing. The maximum possible score was 21 points and the lowest was zero. Fifty-five females and 48 males, average age 35 (range, 16 to 71) years, participated in the study. Results: Noninvasive traction facilitated visualization of all structures of the anterior ankle in more than 90% of cases except for the anterior compartment and lateral gutters, which were better visualized without traction with the ankle in dorsiflexion. No difference was seen when visualizing the talus. Traction arthroscopy performed better when evaluating the central and posterior ankle. The mean score difference was statistically significant, 11.2 versus 18.5 points, favoring noninvasive traction arthroscopy. The complication rate was 4%. Conclusion: Noninvasive traction facilitated complete ankle arthroscopy. Dorsiflexion improved visualization of the anterior compartment and lateral ankle gutter. The authors recommend noninvasive traction when performing ankle arthroscopy. Level of Evidence: II, Diagnostic, Prospective Study

Upper extremity specific disability as measured with the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire varies more than expected based upon variations in objective impairment influenced by depression. We tested the hypothesis that adjusting for depression can reduce the mean and variance of DASH scores. Five hundred and sixteen patients (352 men, 164 women) with an average of 58 years of age (range, 18–100) were asked to simultaneously complete the DASH and Center for Epidemiologic Studies Depression Scale (CES-D) scores at their initial visit to a hand surgeon. Pearson's correlations between each of the DASH items and the CES-D score were obtained. The DASH score was then adjusted for the influence of Depression for women and men using ordinary least-squares regression and subtracting the product of the regression coefficient and the CES-D score from the raw DASH score. The average DASH score was 24 points (SD, 19; range, 0–91), and the average CES-D score was 10 points (SD, 8; range, 0–42). Fourteen of the 30 items of the DASH demonstrated correlation greater than r=0.20. Adjustment of these DASH items for the depression effect led to significant reductions in the mean (5.5 points; p

Purpose To test the null hypothesis that depression does not correlate with patient satisfaction after open release of electrodiagnostically confirmed carpal tunnel syndrome when controlling for other demographic, disease-related, and psychosocial factors. Methods Eighty-two survey respondents who had recovered (minimum 2 years after surgery) from a limited incision open carpal tunnel release completed measures of satisfaction, perceived disability, depression, pain catastrophizing, and pain anxiety. Univariate and multivariate analyses sought predictors of satisfaction and perceived disability from among demographic, disease related, and psychological factors. Results The average satisfaction score was 8 points (range, 0–10) and the average Disabilities of the Arm, Shoulder, and Hand score was 13 points (range, 0–76). Predictors of greater dissatisfaction included greater depression and the categorical electrophysiologic test rating. Predictors of perceived disability included depression, pain catastrophizing, and static numbness. Depression was the dominant predictor of both satisfaction and perceived disability. Conclusions Dissatisfaction and perceived disability after limited open carpal tunnel release for electrodiagnostically confirmed idiopathic carpal tunnel syndrome is predicted primarily by depression and ineffective coping skills and to a lesser degree by clinical or electrophysiologic evidence of advanced nerve damage. Type of study/level of evidence Prognostic II.

Reconstruction of the proximal tibia after wide resection of malignant tumors in the pediatric population is very challenging. Advocates of allograft reconstruction argue as advantages bone preservation, biological reconstruction that facilitates reattachment of the extensor mechanism and other soft-tissue structures, delay of metallic prosthesis use and preservation of the distal femoral growth plate. However, complications are significant, infection being very common.Under IRB-approved protocol, 32 patients (17 males, 15 females), 13 years old in average (2-20), who underwent 33 allograft reconstructions of the proximal tibia, were evaluated for the occurrence of soft-tissue complications and/or deep infection (infection affecting the allograft). Potential predictors of soft-tissue complications and deep infection, categorized as pre- and perioperative variables, were analyzed in relation to the risk for developing a soft-tissue complication or a deep infection.The prevalence of soft-tissue complications was 48% (16/33). However, we were not able to identify any significant predictors. The prevalence of deep (allograft) infection was 15% (5/33). Multivariate logistic regression determined higher BMI at the index surgical procedure and lower pre-operative WBC to be independent predictors of deep infection. For each unit of increase in BMI, the odds of deep infection increased by 40% (OR = 1.40; CI = 1.07-3.06; P 0.05). For each one unit (1,000) of increase in the pre-operative white cell-count, the odds of deep infection decreased by 70% (OR = 0.30; 95%CI = 0.01-0.89; P 0.05). Four of the five deep infections were in patients with soft-tissue complications, mainly wound dehiscence. However, wound dehiscence or soft-tissue complications were not predictive of deep infection.Soft-tissue complications are prevalent in allograft reconstruction of the proximal tibia. Prevention is important as these may progress to deep infection. Careful attention to nutritional (BMI) and immunological status may help in patient selection for allograft reconstruction. If allograft reconstruction is opted for, efforts should focus on optimization of these factors as they proved to be independent predictors of subsequent deep infection. J. Surg. Oncol. 2016;113:811-817. © 2016 Wiley Periodicals, Inc.

This article was updated on January, 13, 2016, because of a previous error. The first author's last name was misspelled. Specifically, “Santiago A. Lozano Calderone” should have read “Santiago A. Lozano Calderon.” An erratum has been published: J Bone Joint Surg Am. 2016 Feb 17;98(4):e17. ### Ewing Sarcoma Ewing sarcoma is associated with balanced translocations of the EWS and ETS genes that produce a fusion protein that binds DNA affecting transcription. Two new studies identified targets of the EWS/FLI1 fusion protein. One study showed preferential binding for a DNA region that induced early growth response 2 (EGR2) expression. EGR2 stimulates proliferation, differentiation, and survival of neural crest-derived cells, from which Ewing sarcoma cells are thought to originate. An EGR2 gene knockdown halted Ewing sarcoma cell growth in vitro and in a xenograft model, demonstrating that the EWS/FLI1 fusion protein works through EGR21. A second study showed that ESW/FLI1 targets SLFN11, which is highly expressed in some Ewing sarcomas. Ewing tumors expressing SLFN11 were susceptible to topoisomerase inhibitor treatment2. In a separate genetic study, 116 patient samples of Ewing sarcoma were used to identify somatic mutations. The gene for fibroblast growth factor receptor 1, FGFR1, was noted to have a gain in copy number in 31.7% of primary tumors. Furthermore, RNA interference of FGFR1 expression halted the growth of Ewing sarcoma cells in a xenograft model. The study concluded with a patient example in which treatment with a tyrosine-kinase inhibitor against FGFR1 reduced 18-FDG-PET (18F-deoxyglucose positron emission tomography) activity3. Margulies et al. developed an animal model for Ewing sarcoma treated with radiation therapy. Increased osteoclastic activity without detection of RANKL (receptor activator of nuclear factor κ ligand) in bone affected by the tumor was identified. MCSF (macrophage colony stimulating factor) rather than RANK ligand mediated osteoclastic activity …

Purpose To report our experience with intralesional curettage (resection with positive margins) and amputation (resection with negative margins) of low-grade chondrosarcomas (LCS) of the hand. Materials and methods Skeletally mature patients treated surgically for LCS of the hand at our institutions were reviewed. Demographics and oncological history were collected. Results of the entire cohort and by treatment modality were analyzed radiographically, functionally (strength, Disabilities of the Arm, Shoulder, and Hand measure), cosmetically, and oncologically (recurrence, Musculoskeletal Tumor Society score, metastasis, and mortality rates). Results Seventeen cases in 16 patients were identified. Nine patients were women. Average age at surgery was 43 years (range, 20–80 years). Mean follow-up was 18 years (range, 9–23 years). Six of the 17 lesions treated at different institutions with intralesional procedures presented as recurrent disease. We treated 3 with a repeat intralesional procedure and the remaining with wide resection. Recurrence incidence was the same in both groups. The remaining 11 new-onset cases were treated with intralesional procedures (6) or wide resections (5). One of the 6 tumors treated with an intralesional procedure recurred. None treated with wide resection recurred. Recurrence incidence combining new- onset and recurrent disease after intralesional procedures was 22% versus 13% for wide resections. Average grip strength was 37 kg (range, 21–55 kg), and pinch strength was 7.6 kg (range, 4.5–12.5 kg). Mean Disabilities of the Arm, Shoulder, and Hand score was 2 (range, 0–10). There were no wound complications, and appearance was satisfactory in most cases (visual analog scale score, > 8). Average Musculoskeletal Tumor Society score was 29 points (range, 21–30 points). No patients presented with metastatic disease or died because of LCS. Conclusions Intralesional resections aiming to preserve function are safe, recognizing that more than 1 procedure may be required. Amputation also plays a role with excellent functional outcome in cases in which severe joint deformity or involvement of soft tissues and neurovascular structures interferes with function. Type of study/level of evidence Therapeutic IV.

Total knee arthroplasty is a safe last-resort treatment for osteoarthritis that has excellent results in low-function-demand elderly patients. Current implants offer the same results in high-function-demand patients. However, supportive data do not exist. One-year Krackow Activity Scores (KAS) of 552 patients from 2 prospective studies were used to retrospectively determine low- and high-function-demand populations. Low function demand was defined as a KAS between 1 and 9 points, and high function demand was defined as a KAS between 10 and 18 points. Patients were assessed preoperatively and at 6 weeks, 3 months, and 1 and 2 years postoperatively per the Knee Society Score-function domain, KAS, SF-36, range of motion, and pain. Comparability between groups was tested for demographics and comorbidities. Both groups showed significant improvement in function, range of motion, and pain 2 years postoperatively. High-function-demand patients had comparable improvement in function compared with low-function-demand patients. Excellent function can be achieved in high-function-demand patients.

Despite clinical success, it is unclear which one, posterior-substituting (PS) or cruciate-retaining (CR) insert, has superior functional outcomes or longevity. We compared the collected results from 2 institutional review board-approved, multicenter, prospective observational studies following CR (412) and PS inserts (328). Participants were evaluated preoperatively, at 6 weeks, at 3 months, and at 1 and 2 years regarding pain, motion, function (Knee Society Score, Krackow Activity Score, Short Form-36), and procedure variables such as anesthesia and preoperative/perioperative/postoperative complications. Implant longevity was recorded at the 2-year follow-up. Improvement was observed within each group; however, there was no difference between groups in terms of pain, motion, or function at any end point. Two-year survival rate was higher than 95%. A higher incidence of wound hematoma was observed in the PS group. Both inserts can be used expecting satisfactory outcomes and high survival rates at 2 years.

Wide resection and reconstruction of tumors of the proximal tibia in the pediatric population are challenging procedures. The use of hinged, expandable prostheses may cause early closure of the distal femoral growth plate, which may increase the risk of limb discrepancy already present in this population. Between 1991 and 2001, 2 girls and 1 boy, aged 6, 6, and 4 years, respectively, were diagnosed with osteosarcoma of the proximal tibia and treated with wide resection and reconstruction with a condylar unipolar expandable tibial prosthesis. A press-fitted technique was used for component insertion. All patients received neoadjuvant and adjuvant chemotherapy. Radiographic and functional follow-up took place at least once a year for a minimum of 4 years. Adequate pain control, limb-length equality, and acceptable function were obtained in all patients. One patient presented with significant range of motion reduction (0°– 30°) in the affected knee. Limb lengthening was performed as needed to maintain balanced limb length. All patients had a good Musculoskeletal Tumor Society category score. No complications occurred in terms of component loosening or infection. One patient died shortly after 4-year follow-up because of doxorubicin-induced leukemia. Currently used hinged, expandable prostheses can jeopardize the unaffected distal femoral growth plate. This article describes a technique of reconstruction that spares the distal femoral growth plate. Adequate limb length can be expected with acceptable functional outcome. However, it is imperative to keep in perspective the expectations of the physician, the physician’s team, the patient, and the patient’s family.

Proper acetabular cup orientation is essential in total hip arthroplasty. The purpose of this study was to evaluate the accuracy of a particular imageless computer navigation system in determining cup position. Thirty-nine computer-navigated total hip arthroplasty intraoperative measurements of cup abduction and anteversion were compared with those from follow-up radiographs. Sensitivity, specificity, accuracy, prevalence-adjusted positive value (PPV), and negative predictive value were calculated for both navigation and radiographs. Navigation measurements had high specificity and PPV when assessing cup abduction and anteversion (specificity >90%, PPV >94%). In contrast, the system was not very effective in detecting suboptimal cup position (sensitivity abduction, 50%; anteversion, 33%). Intraoperative navigation readings in the safe zone have high probability of indicating correct placement. However, confirmation of suboptimal cup position intraoperatively requires additional diagnostic methods.