Trapezial ridge nonunion treated with excision and ligamentous tissue repair.

We describe the challenge associated with obtaining an initial correct diagnosis of trapezial ridge fracture and the importance of repairing the detached ligamentous tissue after excision of the trapezial ridge fragment to obtain a favourable postoperative outcome for this rare fracture.

Paraspinal Muscle Morphology in Proximal Cervical Spondylotic Amyotrophy.

STUDY DESIGN AND OBJECTIVE: This is a retrospective analysis of prospectively collected single-center observational data. The aim is to evaluate atrophy and fatty degeneration rates of cervical spinal muscles in proximal cervical spondylotic amyotrophy (PCSA). OVERVIEW OF LITERATURE: Proximal cervical spondylotic amyotrophy affects muscles in the upper extremities. In cases that lack improvement with conservative treatment, surgery is recommended. However, preoperative factors associated with poor outcomes remain unclear. We hypothesized that assessing fatty degeneration of the cervical spinal muscles and examining its relationship with functional impairment would help predict postoperative improvement in neurological function. METHODS: This study included 18 patients who underwent PCSA surgery. We performed selective laminoplasty and foraminotomy. Preoperative paraspinal muscle cross-sectional area and fatty degeneration were quantified and correlated with neurological function. RESULTS: Neurological improvement based on manual muscle testing was observed in 12/18 patients, comparing preoperative, perioperative, and over 12-month postoperative statuses. On the affected side, at the C4/5 level, fatty degeneration was more significant in the trapezius, whereas at the C5/6 level, fatty degeneration was more significant in the splenius capitis and trapezius. The fatty degeneration of the C4/5 and C5/6 trapezius was significantly correlated with preoperative muscle strength and postoperative muscle strength improvement. CONCLUSIONS: The degree of fat infiltration of the muscle correlated with pre- and postoperative muscle strength at the lesion level. Thus, our results suggest a relationship between cervical muscle morphology and the clinical manifestations of PCSA. The marked increase in trapezius fatty infiltration at the C4/5 and C5/6 levels may be a valuable indicator to predict poor improvements in postoperative muscle strength.

Impact of surgical treatment on patient reported outcome in patients with spinal metastases from prostate cancer.

OBJECTIVE: This study aimed to elucidate postoperative outcomes in patients with spinal metastases of prostate cancer, with a focus on patient-oriented assessments. METHODS: This was a prospective multicenter registry study involving 35 centers. A total of 413 patients enrolled in the Japanese Association for Spine Surgery and Oncology Multicenter Prospective Study of Surgery for Metastatic Spinal Tumors were evaluated for inclusion. The eligible patients were followed for at least 1 year after surgery. The Frankel Classification, Eastern Cooperative Oncology Group Performance Status, visual analog scale for pain, face scale, Barthel Index, vitality index, indications for oral pain medication, and the EQ-5D-5L questionnaire were used for evaluating functional status, activities of daily living, and patient motivation. RESULTS: Of the 413 eligible patients, 41 with primary prostate cancer were included in the study. The patient-oriented assessments indicated that the patients experienced postoperative improvements in quality of life and motivation in most items, with the improvements extending for up to 6 months. More than half of the patients with Frankel classifications B or C showed improved neurological function at 1 month after surgery, and most patients presented maintained or improved their classification at 6 months. CONCLUSION: Surgical intervention for spinal metastases of prostate cancer significantly improved neurological function, quality of life, and motivation of the patients. Consequently, our results support the validity of surgical intervention for improving the neurological function and overall well-being of patients with spinal metastases of prostate cancer.

High Tibial Osteotomy Alone Does Not Decrease Medial Meniscus Extrusion in the Setting of Medial Meniscus Posterior Root Tear: A Cadaveric Study.

PURPOSE: To investigate whether inducing valgus alignment and shifting the load laterally through high tibial osteotomy (HTO) alone decreases the extent of medial meniscus extrusion (MME) in the setting of medial meniscus posterior root tear (MMPRT) using ultrasound evaluation. METHODS: Eight fresh-frozen human cadaveric knee specimens were tested using a 6-degree-of-freedom robotic testing system and ultrasound. Each specimen was tested in 5 conditions: (1) intact, (2) MMPRT, (3) medial meniscus repair (MMR), (4) combined medial open-wedge HTO + MMR, and (5) HTO + MMPRT. Measurements were obtained over the medial collateral ligament (central image) and posterior to the medial collateral ligament (posterior image) with a 250-N axial load at 0°, 30°, and 90° of knee flexion. Statistical analysis was performed using a 2-factor repeated-measures analysis of variance. RESULTS: MME was significantly greater in HTO + MMPRT (0°: 2.44 ± 0.41 mm, 30°: 2.47 ± 0.37 mm, 90°: 2.41 ± 0.28 mm) than HTO + MMR in central images (mean difference +0.83 mm, P < .001). No significant difference was found between HTO + MMPRT and MMPRT in MME. MMR had significantly less MME than MMPRT (mean difference -0.58 mm, P < .001, posterior image at 0° and central image at 90°, P = .002). HTO + MMR showed significantly less MME than MMR alone at 30° and 90° of knee flexion in the central image (30°: -0.38 ± 0.05 mm, 90°: -0.45 ± 0.06 mm, P < .001) and 90° of knee flexion in the posterior image (-0.38 ± 0.08 mm, P = .004). CONCLUSIONS: HTO alone did not decrease MME in the setting of MMPRT, while MMR alone decreased MME after MMPRT. Additionally, HTO + MMR decreased MME after MMPRT compared to MMR alone, although the clinical significance was uncertain. CLINICAL RELEVANCE: The findings of this study provide clinicians with valuable insights for improving MME. HTO alone does not decrease MME in cases of MMPRT.

Influence of different standing positions on anatomical parameters of coronal whole-leg weight-bearing radiographs in preoperative planning for high tibial osteotomy.

Purpose: The purpose of this study was to assess the differences in lower limb global alignment and anatomical parameters of coronal whole-leg radiographs, which were generally used in preoperative planning for high tibial osteotomy (HTO), according to different weight-bearing standing positions. Methods: Between April 2021 and December 2022, 176 patients (60 males and 116 females) were investigated. Full-weight-bearing coronal whole-leg radiographs were obtained with the patella centred on the femoral condyle. Patients were divided by Kellgren-Lawrence grade (KL-0, KL-I, KL-II and KL-III) and assessed in two standing positions: legs closed and legs spread. Patients with flexion contractures or those unable to stand with full weight bearing were excluded. The mechanical distal femoral angle, medial proximal tibial angle (MPTA), femorotibial angle, joint line convergence angle, percentage weight-bearing line (%WBL) and hip-knee-ankle angle (HKAA) were measured. The Student's t test was used to compare the two standing positions. A p value < 0.05 indicated a statistically significant difference. Results: The MPTAs of legs closed standing and legs spread standing were 84.9 ± 2.6° and 85.1 ± 2.4° in KL-0, 84.7 ± 2.0° and 84.9 ± 2.1° in KL-I and 85.0 ± 2.43° and 85.4 ± 2.4° in KL-II, respectively. There were statistically significant differences in the MPTA between the two standing positions in KL-0, KL-I and KL-II. In contrast, the %WBL and HKAA did not change regardless of the standing position. In the KL-III group, no statistical significance was observed for any of the anatomical parameters. Conclusion: Several anatomical parameters were changed between the legs closed standing and the legs spread standing positions. It was suggested that the standing position should be taken into consideration in the planning for HTO. Level of Evidence: Level IV, Case series with no comparison group.

The Prognostic Significance of Surgical Treatment for Excessive Elderly Soft Tissue Sarcoma Patients over 90 Years Old: A Clinicopathological Study of 16 Cases.

OBJECTIVES: The incidence of soft tissue sarcomas (STSs) among older patients is increasing. Although surgical treatment of elderly patients with STS has been reported to improve their prognosis, most of these studies included patients with STS aged <85 years. This study aimed to analyze the clinical features and prognostic factors of STS in elderly patients aged ≥90 years. SUBJECT AND METHODS: We retrospectively identified patients aged ≥90 years with STS who were treated at our two hospitals between 1994 and 2022. Data on clinical information and detailed assessments were collected. We evaluated the features and factors affecting the prognosis of patients with older-extremity STS. In addition, we compared the clinical courses and results of patients treated with surgery and radiotherapy for primary tumors. RESULTS: Among 454 patients with STS, 16 were aged ≥90 years. Kaplan-Meier curves for overall survival showed a significantly poorer prognosis in patients who did not receive surgical treatment (p = 0.0348) and those who received radiotherapy (p = 0.0070). Moreover, we investigated the difference in prognosis between surgical treatment and radiotherapy, excluding two cases with distant metastasis at initial diagnosis and one case with no treatment. Kaplan-Meier curves for overall survival showed a significantly better prognosis in patients who underwent surgical treatment (p = 0.0161). Univariate analysis revealed that only primary tumor size was a significant predictor of poor prognosis (p = 0.0426). CONCLUSION: In patients with STS aged ≥90 years old, aggressive surgical treatment may improve the prognosis more than radiotherapy.

Prospective Registration Study for Establishing Minimal Clinically Important Differences in Patients Undergoing Surgery for Spinal Metastases.

STUDY DESIGN: Multicenter, prospective registry study. OBJECTIVE: To clarify minimal clinically important differences (MCIDs) for surgical interventions for spinal metastases, thereby enhancing patient care by integrating quality of life (QoL) assessments with clinical outcomes. SUMMARY OF BACKGROUND DATA: Despite its proven usefulness in degenerative spinal diseases and deformities, the MCID remains unexplored regarding surgery for spinal metastases. METHODS: This study included 171 (out of 413) patients from the multicenter "Prospective Registration Study on Surgery for Metastatic Spinal Tumors" by the Japan Association of Spine Surgeons. These were evaluated preoperatively and at 6 months postoperatively using the Face scale, EuroQol-5 Dimensions-5 Levels (EQ-5D-5L), including the visual analog scale (VAS), and performance status. The MCIDs were calculated using an anchor-based method, classifying participants into the improved, unchanged, and deteriorated groups based on the Face scale scores. Focusing on the improved and unchanged groups, the change in the EQ-5D-5L values from before to after treatment was analyzed, and the cutoff value with the highest sensitivity and specificity was determined as the MCID through receiver operating characteristic curve analysis. The validity of the MCIDs was evaluated using a distribution-based calculation method for patient-reported outcomes. RESULTS: The improved, unchanged, and deteriorated groups comprised 121, 28, and 22 participants, respectively. The anchor-based MCIDs for the EQ-5D-5L index, EQ-VAS, and domains of mobility, self-care, usual activities, pain/discomfort, and anxiety/depression were 0.21, 15.50, 1.50, 0.50, 0.50, 0.50, and 0.50, respectively; the corresponding distribution-based MCIDs were 0.17, 15,99, 0.77, 0.80, 0.78, 0.60, and 0.70, respectively. CONCLUSION: We identified MCIDs for surgical treatment of spinal metastases, providing benchmarks for future clinical research. By retrospectively examining whether the MCIDs are achieved, factors favoring their achievement and risks affecting them can be explored. This could aid in decisions on surgical candidacy and patient counseling.

Clinical outcomes in patients with adamantinoma: Report from the bone and soft tissue tumor registry in Japan.

BACKGROUND: Adamantinomas are rare malignant bone tumors. Due to their low incidence, there are few reports on the clinical results of adamantinoma. OBJECTIVES: This study aims to clarify outcomes in patients with adamantinoma using data from the National Bone and Soft Tissue Tumor Registry. METHODS: From 2006 to 2019, 38 cases of tibial origin were included. Twenty-four were male and 14 were female, with a mean age of 37 (6-87) years and a mean follow-up of 35 (1-128) months. RESULTS: Surgery was performed in 33 cases (87%) (curettage: 4 cases, wide resection: 27 cases, amputation: 2 cases). Reconstruction was performed in 27 patients who underwent wide resection. A total of 12 additional surgeries were performed in 11 patients. The main reason for the additional surgeries was nonunion of grafting bone in 6 cases. Oncologic outcomes were DOC (death from other causes) in one case and NED (no evidence of disease) in 37 cases. CONCLUSIONS: The results of treatment of adamantinomas in Japan have been extremely favorable. This may be due in part to the large number of cases with wide resection.

Development of T cell receptor-engineered T cells targeting the sarcoma-associated antigen papillomavirus binding factor.

We previously identified papillomavirus binding factor (PBF) as an osteosarcoma antigen recognized by an autologous cytotoxic T lymphocyte clone. Vaccination with PBF-derived peptide presented by HLA-A24 (PBF peptide) elicited strong immune responses. In the present study, we generated T cell receptor-engineered T cells (TCR-T cells) directed against the PBF peptide (PBF TCR-T cells). PBF TCR was successfully transduced into T cells and detected using HLA-A*24:02/PBF peptide tetramer. PBF TCR-T cells generated from a healthy donor were highly expanded and recognized T2-A24 cells pulsed with PBF peptide, HLA-A24+ 293T cells transfected with PBF cDNA, and sarcoma cell lines. To establish an adoptive cell therapy model, we modified the PBF TCR by replacing both α and ß constant regions with those of mice (hybrid PBF TCR). Hybrid PBF TCR-T cells also showed reactivity against T2-A24 cells pulsed with PBF peptide and to HLA-A24+ 293T cells transfected with various lengths of PBF cDNA including the PBF peptide sequence. Subsequently, we generated target cell lines highly expressing PBF (MFH03-PBF [short] epitope [+]) containing PBF peptide with in vivo tumorigenicity. Hybrid PBF TCR-T cells exhibited antitumor effects compared with mock T cells in NSG mice xenografted with MFH03-PBF (short) epitope (+) cells. CD45+ T cells significantly infiltrated xenografted tumors only in the hybrid PBF TCR T cell group and most of these cells were CD8-positive. CD8+ T cells also showed Ki-67 expression and surrounded the CD8-negative tumor cells expressing Ki-67. These findings suggest that PBF TCR-T cell therapy might be a candidate immunotherapy for sarcoma highly expressing PBF.

Coefficient of variation of T2-weighted MRI may predict the prognosis of malignant peripheral nerve sheath tumor.

BACKGROUND: We investigated whether non-enhancement MRI features, including measurement of the heterogeneity of the tumor with MR T2 imaging by calculating coefficient of variation (CV) values, were associated with the prognosis of non-metastatic malignant peripheral nerve sheath tumors (MPNST). METHODS: This retrospective study included 42 patients with MPNST who had undergone surgical resection (mean age, 50 years ± 21; 20 male participants). Non-enhancement MR images were evaluated for signal intensity heterogeneity on T1- and T2-weighted imaging, tumor margin definition on T1- and T2-weighted imaging, peritumoral edema on T2-weight imaging, and CV. We measured the signal intensities of MR T2-weighted images and calculated the corresponding CV values. CV is defined as the ratio of the standard deviation to the mean. The associations between factors and overall survival (OS) were investigated via the Kaplan-Meier method with log-rank tests and the Cox proportional hazards model. RESULTS: The mean CV value of MR T2 images was 0.2299 ± 0.1339 (standard deviation) (range, 0.0381-0.8053). Applying receiver operating characteristics analysis, the optimal cut-off level for CV value was 0.137. This cut-off CV value was used for its stratification into high and low CV values. At multivariate survival analysis, a high CV value (hazard ratio = 3.63; 95% confidence interval = 1.16-16.0; p = 0.047) was identified as an independent predictor of OS. CONCLUSION: The CV value of the signal intensity of heterogenous MPNSTs MR T2-weighted images is an independent predictor of patients' OS.

Remission of hypersensitivity by simple weight load stimuli in a complex regional pain syndrome mouse model.

Painful sensitivity of the hand or foot are the most common and debilitating symptoms of complex regional pain syndrome (CRPS). Physical therapy is standard treatment for CRPS, but evidence supporting its efficacy is minimal and it can be essentially impossible for CRPS patients to actively exercise the painful limb. Using the well-characterized distal tibial fracture CRPS mouse model, we compared the therapeutic effects of several weeks of daily hindlimb loading versus rotarod walking exercise. The effects of loading and exercise were evaluated by weekly testing of hind-paw withdrawal thresholds to von Frey fibers and radiant heat, as well as measurements of paw and ankle edema. At 6 weeks after fracture, the mice were killed and the ipsilateral femur, spinal cord and L4/5 dorsal root ganglia, and hind-paw skin collected for PCR assays and paw skin Immunohistochemistry evaluation. Hindlimb loading reduced hind-paw von Frey allodynia and heat hyperalgesia and edema within a week and these effects persisted for at least a week after discontinuing treatment. These therapeutic effects of loading exceeded the beneficial effects observed with rotarod walking exercise in fracture mice. Levels of nerve growth factor and transient receptor potential vanilloid 1 (TRPV1) immunostaining in the hind-paw skin were increased at 6 weeks after fracture, and both loading and exercise treatment reduced increases. Collectively, these results suggest that loading may be an effective and possibly curative treatment in CRPS patients with sensitivity in the affected limb.

LMNA::NTRK1 Fusion-positive Leiomyosarcoma: Discrepancy between DNA-based Comprehensive Genomic Profiling and RNA Sequencing.

A 26-year-old man presented with a tumor in the left soleus muscle. The tumor was diagnosed as a locally advanced leiomyosarcoma. The patient was treated with irradiation followed by wide resection. One year after surgery, the patient presented with multiple lung metastases. Despite aggressive sequential chemotherapy, systemic metastatic tumors continued to develop. To explore therapeutic options for the patient, we performed DNA-based CGP with FoundationOne® CDx (F1). F1 identified an out-of-strand rearrangement of the NOS1AP::NTRK1 gene, which has not been previously reported. In contrast, RNA sequencing revealed an in-frame LMNA::NTRK1 gene, which is an oncogenic fusion gene.

Thumb pronation efficacy of Camitz tendon transfer with insertion on the ulnar capsule of the metacarpophalangeal joint: a cadaver study.

Several studies have indicated that Camitz transfer for severe carpal tunnel does not adequately restore thumb opposition. The aim of this study was to determine whether modification of the distal insertion of the transferred palmaris longus tendon could provide more effective opposition. We used 12 fresh-frozen upper extremity specimens. For spatial analysis, we used a three-dimensional motion-tracking device. At 0 N and 5 N of traction force, the pronation angle was significantly larger for the modified procedure than for the conventional procedure. There was no significant difference in the palmar abduction angle between the two groups. The modified palmaris longus tendon insertion on the ulnar side of the thumb metacarpophalangeal joint provides more effective thumb pronation than conventional Camitz opponensplasty in a cadaver model. .

Safety and Efficacy of NY-ESO-1 Antigen-Specific T-Cell Receptor Gene-Transduced T Lymphocytes in Patients with Synovial Sarcoma: A Phase I/II Clinical Trial.

PURPOSE: To determine, for patients with advanced or recurrent synovial sarcoma (SS) not suitable for surgical resection and resistant to anthracycline, the safety and efficacy of the infusion of autologous T lymphocytes expressing NY-ESO-1 antigen-specific T-cell receptor (TCR) gene and siRNA to inhibit the expression of endogenous TCR (product code: TBI-1301). PATIENTS AND METHODS: Eligible Japanese patients (HLA-A*02:01 or *02:06, NY-ESO-1-positive tumor expression) received cyclophosphamide 750 mg/m2 on days -3 and -2 (induction period) followed by a single dose of 5×109 (±30%) TBI-1301 cells as a divided infusion on days 0 and 1 (treatment period). Primary endpoints were safety-related (phase I) and efficacy-related [objective response rate (ORR) by RECIST v1.1/immune-related RECIST (irRECIST); phase II]. Safety- and efficacy-related secondary endpoints were considered in both phase I/II parts. RESULTS: For the full analysis set (N = 8; phase I, n = 3; phase II, n = 5), the ORR was 50.0% (95% confidence interval, 15.7-84.3) with best overall partial response in four of eight patients according to RECIST v1.1/irRECIST. All patients experienced adverse events and seven of eight patients (87.5%) had adverse drug reactions, but no deaths were attributed to adverse events. Cytokine release syndrome occurred in four of eight patients (50.0%), but all cases recovered with prespecified treatment. Immune effector cell-associated neurotoxicity syndrome, replication-competent retrovirus, and lymphocyte clonality were absent. CONCLUSIONS: Adoptive immunotherapy with TBI-1301 to selectively target NY-ESO-1-positive tumor cells appears to be a promising strategy for the treatment of advanced or recurrent SS with acceptable toxicity.

Osteophyte Bridge Formation Correlates with Vascular Calcification and Cardiovascular Disease in Diffuse Idiopathic Skeletal Hyperostosis.

Diffuse idiopathic skeletal hyperostosis (DISH) is a noninflammatory spondyloarthropathy characterized by ectopic calcification of spinal cord tissue. Its etiology is possibly polygenic. However, its pathogenesis and systemic effects remain unclear. Recent studies have reported a high prevalence of DISH in heart failure patients. The authors investigated how the incidence and severity of DISH are associated with vascular calcification and the occurrence of cardiovascular events. In this retrospective chart review study, 500 patients with cardiovascular disease who underwent surgery (cardiovascular events group) and 500 patients with non-cardiovascular disease who underwent computed tomography scans (non-cardiovascular events group) were randomly selected to investigate the degree of ossification of the anterior longitudinal ligament and the incidence of DISH. We found that the incidence of DISH was higher in patients with cardiovascular events and that patients with DISH had more calcification of the coronary arteries and aorta. Next, we examined the relationship between the degree of coronary and aortic calcification, the incidence of DISH, and the degree of ossification of the anterior longitudinal ligament in the non-cardiovascular event group. The prevalence of DISH in the cardiovascular and non-cardiovascular groups was 31.4% and 16.5%, respectively (p = 0.007). Aortic calcification and a predominant degree of vascular calcification with a certain level of ossification of the anterior longitudinal ligament suggest some correlation between DISH and cardiovascular events. This study is important in understanding the pathophysiology and pathogenesis of DISH.

Static stretching of the ankle prevents cold hypersensitivity associated with limb immobilization in model mice.

BACKGROUND: Limb immobilization is considered to contribute to limb pain including hyperalgesia. Approximately 50% of patients with such chronic limb pain complain that their abnormal pain worsens after exposure to cold. However, there have been few studies on the relationship between limb immobilization and cold hypersensitivity. The aim of this study was to examine whether limb immobilization induces cold hypersensitivity, and whether physical exercise such as ankle stretching prevents its induction in model mice. METHOD: We used forty-four 8-week-old male C57Bl/6J mice, consisting of 32 immobilized mice and 12 control mice. The bilateral hind limbs of the mice were immobilized by a thermoplastic cast. After limb-immobilization for 1 week, changes in mechanical, thermal and cold hypersensitivity, and the expression levels of TRPV1, TRPA1, TRPM8, IL-1ß, IL-6, and TNFα in the spinal cord, dorsal root ganglia and the affected hind paw were evaluated in comparison with those in the control mice. In addition, we examined the effect of ankle stretching on the hypersensitivity and expression levels in the limb-immobilized mice. RESULTS: Mechanical, thermal and cold hypersensitivity were significantly increased in the limb-immobilized mice. In addition, ankle stretching during the immobilization period significantly prevented the increases in those hypersensitivities. There were no significant differences in the expression levels of TRPV1, TRPA1 and TRPM8 among the control, and limb-immobilized mice with and without ankle stretching. The expression levels of IL-1 and IL-6 were significantly increased in the immobilized hind limb paw. Furthermore, ankle stretching significantly prevented the increases in their expression levels. CONCLUSION: Limb-immobilization induced cold hypersensitivity as well as mechanical and thermal hypersensitivity, and ankle stretching significantly prevented the hypersensitivity induction in the model mice. It would be of great interest to clarify whether a patient with limb-immobilization experiences cold hypersensitivity and whether ankle stretching might prevent hypersensitivity induction in the future.

Establishment and characterization of a novel dedifferentiated chondrosarcoma cell line, SMU-DDCS, harboring an IDH1 mutation.

Dedifferentiated chondrosarcoma (DDCS) is a high-grade subtype with a bi-morphic histological appearance of a conventional chondrosarcoma component and it can abruptly transition to a high-grade non-cartilaginous sarcoma. To better understand the biological features of DDCSs and to help develop new therapies, a novel DDCS cell line, SMU-DDCS, was established. Tissue from an open biopsy of a tumor resected from a 75-year-old patient was subjected to primary culture. The cell line was established and authenticated by assessing DNA microsatellite short tandem repeats. The cells maintained in monolayer cultures exhibited constant growth, spheroid formation, and high invasive capacity. Out of the four mice inoculated with SMU-DDCS cells, tumors developed in three mice after 2 weeks. R132C mutation was found in the IDH1 but not the IDH2 genomic DNA sequence of SMU-DDCS cells. SMU-DDCS cells exhibited low chemosensitivity to doxorubicin, methotrexate, and cisplatin. This SMU-DDCS cell line harboring an IDH1 mutation will be a useful tool for investigating DDCS development and for evaluating novel therapeutic agents against it.

How Much Experience is Required to Acquire the Skills to Independently Perform Spine Surgery? What Milestones are Needed for Successful Surgery?

Purpose: To assess the number of surgeries needed to acquire the necessary skills to perform spine surgery independently. Patients and Methods: A questionnaire on 12 different spinal procedures was sent to orthopedic surgeons affiliated with the spine teams of orthopedic departments at either the Akita University or Sapporo Medical University. Participants were asked to identify whether they (A) could independently perform each procedure, (B) could perform each procedure with the assistance of a senior doctor, or (C) were unable to perform each procedure. Those whose response was (A) were asked how many surgeries were required to acquire the necessary skills. Those who responded to (B) or (C) were asked how many surgeries they believed were required to acquire the skills necessary to operate independently. Participants also responded to 10 questions on surgical training techniques and rated the usefulness of each method. Results: A total of 55 spine surgeons responded to the questionnaire. Group A required significantly fewer surgeries in the following categories to become independent than required Group C: upper cervical spine surgery (7.3/19.3), anterior cervical decompression/fusion (6.7/28.8), posterior cervical decompression/fusion (9.5/27.3), lumbar discectomy (12.6/26.7), endoscopic lumbar discectomy (10.2/24.2), spinal tumor resection (6.5/37.2), and spinal kyphosis surgery (10.3/32.3). Over 80% of participants responded that the following were effective methods: "surgeries where a senior doctor is the main surgeon, and the respondent is the assistant and observer"; "surgeries where the respondent is the main surgeon, and a senior doctor is an assistant"; "self-study using surgery manuals, articles, and textbooks"; and "training through video surgery sessions". Conclusion: Surgeons who do not perform specific procedures independently require more surgical experience than those who operate independently. Our results may help develop more efficient training methods for spine surgeons.

What Are the Complications, Function, and Survival of Tumor-devitalized Autografts Used in Patients With Limb-sparing Surgery for Bone and Soft Tissue Tumors? A Japanese Musculoskeletal Oncology Group Multi-institutional Study.

BACKGROUND: Tumor-devitalized autografts treated with deep freezing, pasteurization, and irradiation are biological reconstruction methods after tumor excision for aggressive or malignant bone or soft tissue tumors that involve a major long bone. Tumor-devitalized autografts do not require a bone bank, they carry no risk of viral or bacterial disease transmission, they are associated with a smaller immunologic response, and they have a better shape and size match to the site in which they are implanted. However, they are associated with disadvantages as well; it is not possible to assess margins and tumor necrosis, the devitalized bone is not normal and has limited healing potential, and the biomechanical strength is decreased owing to processing and tumor-related bone loss. Because this technique is not used in many countries, there are few reports on the results of this procedure such as complications, graft survival, and limb function. QUESTIONS/PURPOSES: (1) What was the rate of complications such as fracture, nonunion, infection, or recurrence in a tumor-devitalized autograft treated with deep freezing, pasteurization, and irradiation, and what factors were associated with the complication? (2) What were the 5-year and 10-year grafted bone survival (free from graft bone removal) of the three methods used to devitalize a tumor-containing autograft, and what factors were associated with grafted bone survival? (3) What was the proportion of patients with union of the tumor-devitalized autograft and what factors were associated with union of the graft-host bone junction? (4) What was the limb function after the tumor-devitalized autograft, and what factors were related to favorable limb function? METHODS: This was a retrospective, multicenter, observational study that included data from 26 tertiary sarcoma centers affiliated with the Japanese Musculoskeletal Oncology Group. From January 1993 to December 2018, 494 patients with benign or malignant tumors of the long bones were treated with tumor-devitalized autografts (using deep freezing, pasteurization, or irradiation techniques). Patients who were treated with intercalary or composite (an osteoarticular autograft with a total joint arthroplasty) tumor-devitalized autografts and followed for at least 2 years were considered eligible for inclusion. Accordingly, 7% (37 of 494) of the patients were excluded because they died within 2 years; in 19% (96), an osteoarticular graft was used, and another 10% (51) were lost to follow-up or had incomplete datasets. We did not collect information on those who died or were lost to follow-up. Considering this, 63% of the patients (310 of 494) were included in the analysis. The median follow-up was 92 months (range 24 to 348 months), the median age was 27 years (range 4 to 84), and 48% (148 of 310) were female; freezing was performed for 47% (147) of patients, pasteurization for 29% (89), and irradiation for 24% (74). The primary endpoints of this study were the cumulative incidence rate of complications and the cumulative survival of grafted bone, assessed by the Kaplan-Meier method. We used the classification of complications and graft failures proposed by the International Society of Limb Salvage. Factors relating to complications and grafted autograft removal were analyzed. The secondary endpoints were the proportion of bony union and better limb function, evaluated by the Musculoskeletal Tumor Society score. Factors relating to bony union and limb function were also analyzed. Data were investigated in each center by a record review and transferred to Kanazawa University. RESULTS: The cumulative incidence rate of any complication was 42% at 5 years and 51% at 10 years. The most frequent complications were nonunion in 36 patients and infection in 34 patients. Long resection (≥ 15 cm) was associated with an increased risk of any complication based on the multivariate analyses (RR 1.8 [95% CI 1.3 to 2.5]; p < 0.01). There was no difference in the rate of complications among the three devitalizing methods. The cumulative graft survival rates were 87% at 5 years and 81% at 10 years. After controlling for potential confounding variables including sex, resection length, reconstruction type, procedure type, and chemotherapy, we found that long resection (≥ 15 cm) and composite reconstruction were associated with an increased risk of grafted autograft removal (RR 2.5 [95% CI 1.4 to 4.5]; p < 0.01 and RR 2.3 [95% CI 1.3 to 4.1]; p < 0.01). The pedicle freezing procedure showed better graft survival than the extracorporeal devitalizing procedures (94% versus 85% in 5 years; RR 3.1 [95% CI 1.1 to 9.0]; p = 0.03). No difference was observed in graft survival among the three devitalizing methods. Further, 78% (156 of 200 patients) of patients in the intercalary group and 87% (39 of 45 patients) of those in the composite group achieved primary union within 2 years. Male sex and the use of nonvascularized grafts were associated with an increased risk of nonunion (RR 2.8 [95% CI 1.3 to 6.1]; p < 0.01 and 0.28 [95% CI 0.1 to 1.0]; p = 0.04, respectively) in the intercalary group after controlling for confounding variables, including sex, site, chemotherapy, resection length, graft type, operation time, and fixation type. The median Musculoskeletal Tumor Society score was 83% (range 12% to 100%). After controlling for confounding variables including age, site, resection length, event occurrence, and graft removal, age younger than 40 years (RR 2.0 [95% CI 1.1 to 3.7]; p = 0.03), tibia (RR 6.9 [95% CI 2.7 to 17.5]; p < 0.01), femur (RR 4.8 [95% CI 1.9 to 11.7]; p < 0.01), no event (RR 2.2 [95% CI 1.1 to 4.5]; p = 0.03), and no graft removal (RR 2.9 [95% CI 1.2 to 7.3]; p = 0.03) were associated with an increased limb function. The composite graft was associated with decreased limb function (RR 0.4 [95% CI 0.2 to 0.7]; p < 0.01). CONCLUSION: This multicenter study revealed that frozen, irradiated, and pasteurized tumor-bearing autografts had similar rates of complications and graft survival and all resulted in similar limb function. The recurrence rate was 10%; however, no tumor recurred with the devitalized autograft. The pedicle freezing procedure reduces the osteotomy site, which may contribute to better graft survival. Furthermore, tumor-devitalized autografts had reasonable survival and favorable limb function, which are comparable to findings reported for bone allografts. Overall, tumor-devitalized autografts are a useful option for biological reconstruction and are suitable for osteoblastic tumors or osteolytic tumors without severe loss of mechanical bone strength. Tumor-devitalized autografts could be considered when obtaining allografts is difficult and when a patient is unwilling to have a tumor prosthesis and allograft for various reasons such as cost or socioreligious reasons. LEVEL OF EVIDENCE: Level III, therapeutic study.