Survey of Osteoarthritis of the Shoulder in Patients who Underwent Knee Arthroplasty for Knee Osteoarthritis.

The relationship between osteoarthritis (OA) of the lower extremity and shoulder OA has not been established. This study evaluated the prevalence of shoulder OA in patients with knee OA. We collected contrast-enhanced computed tomography (CECT) images of the shoulder joints of 105 patients with knee OA that were taken 1 week after they underwent primary knee arthroplasty to check for venous thromboembolism (VTE). The images were compared with CECT images of 110 control-group patients that were taken for the purpose of differentiating VTE. Shoulder OA was present in a significantly higher percentage of patients with knee arthroplasty than controls (29% versus 15%), and the difference was particularly pronounced in patients in their 70s (33%) compared to age-matched controls (11%). Patients with knee OA often use arm support to stand up or walk due to knee joint pain and muscle weakness, which places the weight-bearing shoulder at risk of developing OA.

Comparison between Cases of Total Hip Arthroplasty Followed by Colonna Capsular Arthroplasty and Lorenz Cast Reduction in Patients with Developmental Dysplasia of the Hip.

Most patients with developmental dysplasia of the hip (DDH) now receive closed-reduction treatment within 6 months after birth. The long-term outcomes of patients with late-detection DDH have remained unclear. We reviewed the clinical records of 18 patients who underwent Colonna capsular arthroplasty (n=8) or closed reduction (n=10) for developmental dysplasia of the hip as infants or young children and underwent total hip arthroplasty approximately in midlife. Both the Colonna capsular arthroplasty and closed reduction groups achieved good clinical results after total hip arthroplasty. However, the operating time was longer and the improvements of hip range of motion and clinical score were significantly worse in the Colonna capsular arthroplasty group than in the closed reduction group.

Possibility of Predicting Pelvic Inclination Following Total Hip Arthroplasty Based on the Preoperative State: Sacral Slope and Pelvic Incidence Minus Lumbar Lordosis as Predictive Factors.

Following total hip arthroplasty (THA), some patients exhibit anterior or posterior pelvic tilt (PT). This case- control study investigated whether changes to PT following THA can be preoperatively predicted. METHODS: 135 patients with hip osteoarthritis who underwent THA were assessed. The parameters measured preoperatively and one year postoperatively were lumbar lordosis (LL) based on plain X-ray and pelvic incidence (PI), PT, and sacral slope (SS), all of which were measured as pelvic morphological angles. Patients were classified into groups (A-E) based on the degree of post-THA PT, and their preoperative conditions were compared. PI minus LL was used to evaluate spinal alignment and pelvic balance. RESULTS: Overall, 33%, 30%, 21%, 13%, and 3% of the hips of patients in Groups A, B, C, D, and E were postoperatively assessed. In Groups A-E, the SS values were 34.6°±8.9°, 37.6°±8.4°, 37.9°±8.9°, 42.6°±9.5°, and 60.0°±11.1°, whereas the PI minus LL values were 2.9°±15.0°, 1.2°±13.6°, 3.6°±17.7°, 12.7°±13.1°, and -1.3°±11.7°, respectively. CONCLUSIONS: Following THA, 70% of patients experienced posterior PT. Pre-THA SS ≥45° or PI minus LL ≥15° signified marked postoperative posterior tilt and could predict postoperative PT following THA. These findings are useful for implant placement, as they can predict pelvic inclination.

Factors Associated with Surgical Field Bacterial Detection during Total Hip Arthroplasty.

Total hip arthroplasty (THA) provides relief from hip pain and improves hip function. However, periprosthetic joint infection (PJI) remains an area of concern. We examined the detection rate of bacteria from surgical fields in wound closure, along with the relationship between bacterial detection rate and type of antiseptic, surgery time, and surgeon experience for 500 patients who underwent THA at our department. The mean age at surgery was 64.3 (± 27.3) years. The bacterial detection rate was 4.6%. None of the cases revealed PJI. No significant association between the detection rate and type of antiseptic used or surgery time was observed. However, for patients treated by surgeons with < 10 years of orthopedic experience, a detection rate of 7.3% was found, while a rate of 1.3% was observed for those treated by surgeons with ≥ 10 years of orthopedic experience. This finding indicated that orthopedic experience of less than 10 years was significantly associated with an increased bacterial detection rate (chi-square test, p=0.002). The detection rate was associated with surgeon experience but not with antiseptic type or surgery time. It is possible that intraoperative handling may increase the number of bacteria in surgical fields in wound closure.

Survey of Shoulder Osteoarthritis in Patients who Underwent Total Hip Arthroplasty for Hip Osteoarthritis.

To the best of our knowledge, no previous studies have reported a relationship between osteoarthritis (OA) of the lower limbs and OA of the shoulder joints. We evaluated the correlation between shoulder OA and hip OA. We collected contrast-enhanced computed tomography (CECT) images of the shoulder joints of 159 patients with hip OA who underwent primary total hip arthroplasty (THA). The images, taken 1 week after THA to monitor venous thromboembolism (VTE), were used to examine the prevalence of shoulder OA. They were compared with those of 103 controls who underwent CECT during the same period to monitor VTE. Shoulder OA was observed in 15% of the controls and 24% of the THA patients. Although the rate was somewhat higher in the THA group, the difference was not significant. However, in the THA group, significantly more patients with bilateral hip OA (33%) had shoulder OA than those with unilateral hip OA (17%). In summary, the prevalence of shoulder OA was significantly higher in patients with bilateral hip OA. In these patients, pain and instability in the hip joints require them to use arm support to stand up or walk, putting the weight-bearing shoulder at risk of developing OA.

Novel Technique for Removing a Well-Fixed Cemented Cup with a Dedicated Original Device during Revision Total Hip Arthroplasty: Surgical Technique.

The improved cemented cup technique has attained excellent long-term results in primary total hip arthroplasty. When cup revision surgery was performed, the cemented cup, which was loosened at the bone-cement interface, was easily removed. However, with a well-fixed bone-cement interface, it remains difficult to remove the cemented cup for a revision in the event of a recurring dislocation. In addition, protrusions in the cement can cause unpredictable bone defects. A new removal device was created and used successfully to remove a well-fixed cemented cup safely and efficiently. This report introduces the device and the technique used in cemented cup removal.

Residual Femoral Deformity and Femoroacetabular Impingement after Intertrochanteric Osteotomy for Slipped Capital Femoral Epiphysis.

We retrospectively reviewed 29 hips in which intertrochanteric osteotomies were performed for severe slipped capital femoral epiphyses. Mean age at surgery: 12.6 years. Mean follow-up period: 6 years. At the final follow-up evaluation, one patient had coxalgia, and six hips showed a limited range of motion. A pistol-grip deformity was observed in 13 hips, osteoarthritis in two hips, and a bump existed in 19 hips on the latest radiographs. Gradual remodeling of the bumps was observed post-operatively in 22 hips. The mean α and ß angles and offset α and ß improved over time. The remodeling proceeded rapidly for 1 year post-surgery. We compared hips classified as ß angles of ≥ 63° to < 63° at the final follow-up evaluation, the mean ß angle 1 year post-surgery, and the mean ratio of improvement of the ß angle per year from 1 year post-surgery to the final follow up, which differed significantly. Nearly all of the patients who underwent intertrochanteric osteotomies had residual morphologic abnormalities, but few had clinical symptoms. The ß angle 1 year post-surgery and the ratio of remodeling of the bump from 1 year post-surgery to the final follow-up can be regarded as a potential predictor of morphologic results after intertrochanteric osteotomy.

Is the timing of surgery associated with avascular necrosis after unstable slipped capital femoral epiphysis? A multicenter study.

BACKGROUND: An unstable slipped capital femoral epiphysis (SCFE) is associated with a high rate of avascular necrosis (AVN). The etiology of AVN seems to be multifactorial, although it is not thoroughly known. The aims of our study were to determine the rate of AVN after an unstable SCFE and to investigate the risk factors for AVN, specifically evaluating the notion of an "unsafe window", during which medical interventions would increase the risk for AVN. METHODS: This retrospective multicenter study included 60 patients with an unstable SCFE diagnosed between 1985 and 2014. Timing of surgery was evaluated for three time periods, from acute onset of symptoms to surgery: period I, <24 h; period II, between 24 h and 7 days; and period III, >7 days. Multivariate logistic regression analysis was used to identify risk factors for AVN. RESULTS: Closed reduction and pinning was performed in 43 patients and in situ pinning in 17. Among these cases, 16 patients (27%) developed AVN. The rate of AVN was significantly higher in patients treated by closed reduction and pinning (15/43, 35%) than in those treated by in situ pinning (1/17, 5.9%) (p = 0.022). In patients treated by closed reduction and pinning, the incidence of AVN was 2/11 (18%) in period I, 10/13 (77%) in period II and 3/15 (20%) in period III, showing the significantly higher rate in period II (p = 0.002). The surgery provided in period II was identified as an independent risk factor for the development of AVN. CONCLUSIONS: Our rate of AVN was 27% using two classical treatment methods. Time-to-surgery, between 24 h and 7 days, was independently associated with AVN, supporting the possible existence of an "unsafe window" in patients with unstable SCFE treated by closed reduction and pinning.

Factors Influencing Health-related Quality of Life after Total Hip Arthroplasty.

Total hip arthroplasty (THA) is an established treatment approach with which good recovery is expected in patients. However, the postoperative satisfaction of THA patients, and factors that affect their treatment outcomes are unclear. We investigated 125 Japanese patients who underwent a primary THA between January 2011 and August 2013. The posterolateral (PL) and muscle-sparing anterolateral (AL) surgical approaches were used. THA outcomes were evaluated using the Short Form-36 (SF-36) at preoperatively and 1 month, 3 months, 6 months, and 1 year postoperatively. Approach-based comparisons demonstrated a significantly higher mean score for physical functioning after 6 months, role physical at 1 year, and social functioning at 1 year in the AL group. No significant diff erence was observed for other subscale scores at any survey period. The age-based comparisonoften indicated significant increases of subscale scores in the younger patient group. Weight-based comparisons were not observed for any of the 8 subscales at any survey period. Surgical approach was not a factor aff ecting the patients' postoperative quality of life, and the AL approach was not superior to the other surgical approaches involving myotenotomy. Moreover, the THA treatment outcomes were better in the younger patients, and obesity did not affect the outcomes.

Venous thromboembolism after total hip arthroplasty diagnosed by enhanced computed tomography:comparison of selective thromboprophylaxis and no thromboprophylaxis.

Total hip arthroplasty (THA) is the most effective treatment for advanced or end-stage hip osteoarthritis. However, venous thromboembolism (VTE) remains one of its unresolved complications. We reviewed the records of 322 patients undergoing primary THA and investigated the efficacy of anticoagulant prophylaxis for VTE. Our study cohort consisted of 60 patients who received no anticoagulants, 100 patients who received a factor Xa inhibitor (fondaparinux), 100 patients who received low molecular weight heparin (enoxaparin), and 62 patients who selectively received no anticoagulant prophylaxis due to perioperative bleeding, weight, and/or hemoglobin concentration. Enhanced 64-slice multidetector row computed tomography was performed postoperatively for 7 days in all cases. The incidence of VTE in the four groups was 15%, 9.0%, 6.0%, and 6.4%, respectively. The incidence of VTE was significantly lower in the groups receiving anticoagulant prophylaxis and the group selectively receiving no anticoagulant prophylaxis than in the group receiving no anticoagulants. Complications of fondaparinux therapy included hepatic dysfunction in 4 cases (4.0%), minor bleeding in 2 cases (2.0%), persistent wound drainage in 3 cases (3.0%), and eruption in 1 case (1.0%). The complications of enoxaparin therapy were persistent wound drainage in 1 case (1.0%) and progression of anemia in 1 case (1.0%). The incidence of VTE was low in patients who selectively received no anticoagulant prophylaxis, so we conclude that anticoagulant prophylaxis should be used selectively in THA cases.

Erratum. Venous Thromboembolism after Total Hip Arthroplasty Diagnosed by Enhanced Computed Tomography:Comparison of Selective Thromboprophylaxis and No Thromboprophylaxis.

Total hip arthroplasty (THA) is the most effective treatment for advanced or end-stage hip osteoarthritis. However, venous thromboembolism (VTE) remains one of its unresolved complications. We reviewed the records of 322 patients undergoing primary THA and investigated the efficacy of anticoagulant prophylaxis for VTE. Our study cohort consisted of 60 patients who received no anticoagulants, 100 patients who received a factor Xa inhibitor (fondaparinux), 100 patients who received low molecular weight heparin (enoxaparin), and 62 patients who selectively received no anticoagulant prophylaxis due to perioperative bleeding, weight, and/or hemoglobin concentration. Enhanced 64-slice multidetector row computed tomography was performed postoperatively for 7 days in all cases. The incidence of VTE in the four groups was 15%, 9.0%, 6.0%, and 6.4%, respectively. The incidence of VTE was significantly lower in the groups receiving anticoagulant prophylaxis and the group selectively receiving no anticoagulant prophylaxis than in the group receiving no anticoagulants. Complications of fondaparinux therapy included hepatic dysfunction in 4 cases (4.0%), minor bleeding in 2 cases (2.0%), persistent wound drainage in 3 cases (3.0%), and eruption in 1 case (1.0%). The complications of enoxaparin therapy were persistent wound drainage in 1 case (1.0%) and progression of anemia in 1 case (1.0%). The incidence of VTE was low in patients who selectively received no anticoagulant prophylaxis, so we conclude that anticoagulant prophylaxis should be used selectively in THA cases.

D-dimer testing cannot rule out thromboembolism after major lower extremity arthroplasties and thromboprophylaxis treatment.

PURPOSE: Our previous study showed, for the first time, that a guideline-recommended thromboprophylactic strategy reduced the prevalence of venous thromboembolism (VTE) including venous thromboembolism and pulmonary embolism after arthroplasties of the major lower extremities, such as total hip arthroplasty (THA) or total or partial knee arthroplasty (TPKA), to 4.4 %. In this retrospective study, we examined the diagnostic value of D-dimer for VTE and try to confirm the low prevalence of VTE after THA or TPKA. METHODS: This was a retrospective study including 380 procedures of 361 patients who underwent elective 129 TPKA or 251 THA, as well as multidetector computed tomography (MDCT) on postoperative day 7 with D-timer testing to screen for VTE. In 303 of 380 procedures, D-timer testing was performed on the same day as MDCT. The antithrombotic prophylaxes included medical and mechanical therapy and early ambulation. RESULTS: The prevalence of VTE was 4.5 % (17 cases) (95 % confidence interval 2.4-6.6 %). The D-dimer level was significantly greater in patients with VTE than in those without (13.4 ± 11.1 vs 10.1 ± 6.5 µg/mL). At the lowest cut-off value of 4.0 µg/mL, D-dimer testing ruled out VTE in only 26 of 303 cases with 1 (6 %) false negative result. CONCLUSIONS: The low incidence of postoperative VTE with the strict anticoagulation strategy was confirmed in this validation study. D-dimer testing is not useful for excluding VTE postoperatively in patients who undergo THA or TPKA.

The incidence of pulmonary embolism and deep vein thrombosis and their predictive risk factors after lower extremity arthroplasty: a retrospective analysis based on diagnosis using multidetector CT.

PURPOSE: The true incidence of venous thromboembolism (VTE), including deep vein thrombosis (DVT) and pulmonary embolism (PE) events, and the predictive risk factors are not well-defined in patients who undergo major lower extremity arthroplasty such as total hip arthroplasty (THA) or total or partial knee arthroplasty (TPKA). Using multidetector computed tomography (MDCT), pulmonary angiography (CTA), and MDCT venography (CTV), we investigated the prevalence of VTE and its predictive risk factors in patients for whom the guideline recommends prophylaxis. METHODS: The electronic records of patients who underwent elective THA or TPKA at our institution from April 2010 through July 2013 were surveyed. We examined a total of 1,163 patient records for 986 patients who had undergone MDCT seven days after THA or TPKA. RESULTS: No PE-related deaths occurred in this study, though arterial embolization was needed for major bleeding in two cases. CTA-CTV revealed VTE in 51 (4.4 %) patients, PE in 20 (1.7 %), and DVT in 43 (3.3 %). Five of 51 patients had symptoms suggestive of DVT. In the logistic regression model, the type of surgery (TPKA > THA), patient age, and body mass index (BMI) were identified as predictive risk factors for VTE. CONCLUSIONS: This observational study showed that the overall incidence of VTE after THA and TPKA is 4.4 % in patients receiving recommended antithrombotic prophylaxis. TPKA is associated with a higher incidence of VTE than of THA, and greater BMI and older patient age are also independent risk factors.

Two-directional arthrographic assessment for treating bilateral development dislocation of the hips in children after walking age.

We reviewed the treatment outcome in 14 hips of 7 patients who were diagnosed as having bilateral developmental dislocation of the hip (DDH) after walking age and could be followed up until they were at least 14 years of age. Based on the results of two-directional arthrography of the hip, closed reduction was performed in 2 hips, and open reduction was performed without osteotomy in 12 hips. The final radiographic evaluations were made according to the Kalamchi and MacEwen classification and Severin classification. The mean age at the initial visit was 1 year and 9 months (range, 1 year and 5 months to 3 years). The outcome was satisfactory for one hip in Group Ⅰ and 2 hips in Group Ⅱ according to the Kalamchi and MacEwen classification, and in 83% of the Severin Class Ⅰ and Ⅱ hips. Arthrography was useful for identifying asymmetry, demonstrating the usefulness of a treatment strategy based on arthrography of the hip.

Pediatric Traumatic Cervical Distraction Injury: A Case Report.

Spinal cord injury due to trauma is rare in children. We report our experience with the surgical treatment of a cervical spinal cord injury in a one-year-old child with quadriplegia due to traffic trauma. The patient was a girl aged one year and five months. Physical examination findings were quadriplegia and loss of consciousness. Plain computed tomography (CT) of the cervical spine showed a vertical distraction injury of C6/7, and magnetic resonance imaging (MRI) showed spinal cord injuries of C1/2 and C6/7. Based on these findings, a diagnosis of C1/2 and C6/7 spinal cord injury (Frankel A) was made. The patient's state of consciousness did not change during the first week after injury; she was managed systemically with a ventilator. On the 10th day after the injury, her consciousness improved, and she was placed in a pediatric halo vest for weaning. However, as the alignment worsened, we operated. A 5 cm posterior incision was made at the median of C5/6/7. Only the spinous process was deployed, a Nespron tape (Alfresa Pharma Corporation, Osaka, Japan) was wrapped between C5/6 and C6/7, and an autologous iliac bone graft was placed at the C6/7 bilateral facet joint. Six months after surgery, bone fusion was complete. At one year and six months postoperatively, tetraplegia had not improved. Radiographs showed no growth disturbances despite residual alignment abnormalities.

Alexis® Orthopedic Protector Provides Wound Protection and Aids in Hypertrophic Scar Prevention in Total Hip Arthroplasty.

PURPOSE: Total hip arthroplasty (THA) is one of the most widely performed orthopedic surgeries. Techniques for small skin incisions and preservation of muscles and tendons have been developed. However, avoiding skin complications and muscle damage due to forced deployment and surgical manipulation is challenging. This study aimed to investigate whether the use of Alexis® Orthopedic Protector (Applied Medical Resources Corp., Rancho Santa Margarita, CA, USA) affects postoperative outcomes. METHODS: This was a retrospective cohort study including 118 patients who underwent primary THA by the same surgeon at our single institution between March 2021 and March 2023. Protectors were used alternately for each operation. Fifty-nine patients were in the protector-using group (P group), and 59 were in the nonprotector-using group (N group), with comparisons made between groups. Protectors were placed under the fascia in all patients. RESULTS: Preoperative blood tests showed no difference in renal and hepatic function between the two groups. No differences in postoperative C-reactive protein (CRP) and creatine kinase (CK) values or in the Japanese Orthopedic Association Hip Disease Evaluation Questionnaire (JHEQ) and Numerical Rating Scale (NRS) scores were observed. Postoperative redness was significantly higher in the N group than in the P group (49.2% vs. 7%). The percentage of hypertrophic scars at three months postoperatively was 18.6% in the N group and 7% in the P group. Furthermore, the Japan Scar Workshop Scar Scale (JSS) indicated that hypertrophic scars were significantly worse in the N group than in the P group (p = 0.0012). CONCLUSION: Alexis® Orthopedic Protectors can not only provide short-term wound protection but also reduce the rate and degree of hypertrophic scarring.

Minimally Invasive Trans-sacral Canal Plasty for Lumbar Canal Stenosis.

Objective The elderly population is increasing in Japan. Along with the increase in the elderly population, the number of patients with lumbar degenerative diseases is also on the rise. In general, elderly patients tend to have more complications and are at higher risk for surgery. Many elderly people suffer from lumbar degenerative disease. We reviewed our initial experience with trans-sacral canal plasty (TSCP) for patients with lumbar spinal canal stenosis and examined the pertinent literature for this report. Methods An analytical observational study was performed on 120 patients with lumbar spinal canal stenosis who underwent TSCP at our single institution from March 2019 to October 2021. These patients had leg pain and/or lower back pain due to degenerative lumbar disease. Patients who had coagulation abnormality, pregnancy, contrast allergy, pyogenic spondylitis, or spinal metastasis were excluded. Results Immediately after TSCP, the average Visual Analog Scale (VAS) score for back pain improved from 58.2 to 29.3, and for leg pain from 72.0 to 31.3. Two years after TSCP, the average VAS score for back pain increased slightly and the average score for leg pain remained almost the same. Additional surgery was performed in 37 of 120 (31%) patients who underwent TSCP. The additional surgery group had significantly worse back pain at one and three months postoperatively than the conservative treatment group. The additional surgery group had significantly worse leg pain immediately after TSCP and at one and three months postoperatively than the conservative treatment group. Logistic regression analysis demonstrated that a decreased spinal canal area (OR 0.986, p = 0.039) was associated with additional surgery. Conclusions We reviewed the outcomes of TSCP at our hospital. The average VAS score for back pain and leg pain improved. However, 31% of patients who underwent TSCP required additional surgery. It was found that the spinal canal area was a major factor in the need for additional surgery.

Efficiency of Long Lateral Mass Screw in Posterior Cervical Fusion.

INTRODUCTION: Long lateral mass screw (LLMS) technique for posterior cervical fusion has been performed in our hospital since 2019. In this study, the LLMS insertion technique, deviation rate, and insertion torque have been described. Moreover, several major concerns associated with LLMS have been adequately addressed. METHODS: This study included 58 patients (43 men and 15 women) who had undergone LLMS surgery at our hospital during the four-year period from December 2019 to December 2023, and were evaluated using postoperative CT. The evaluation parameters included the screw length at each vertebral segment, screw angle in the sagittal section, distance between the screw heads, and complications. RESULTS: The median screw length at C3 was 23.0 mm (22.0-24.0 mm), the screw angle was 36.1° (31.6-41.8°), and the distance between screw heads was 13.8 mm (11.6-17.2 mm). The median screw length at C4 was 22.0 mm (21.0-24.0 mm), the screw angle was 36.2° (28.7-40.7°), and the distance between screw heads was 15.9 mm (13.0-19.0 mm). The median screw length at C5 was 21.0 mm (20.0-22.0 mm), the screw angle was 35.6° (28.0-39.7°), and the distance between screw heads was 17.6 mm (15.1-20.4 mm). The median screw length for C6 was 20.0 mm (19.0-22.0 mm), the screw angle was 29.2° (25.2-36.8°), and the distance between screw heads was 20.4 mm (16.1-24.4 mm). CONCLUSION: The major limitations of the LLMS technique were inadequate screw angle, difficulty inserting long screws, inadequate decompression, and the inability to perform cervical laminoplasty. However, these limitations did not substantially affect the efficiency of LLMS. LLMS has fewer complications and can insert longer screws than LMS.

Debridement, Antibiotics, and Implant Retention for a Rare Serratia marcescens Infection after Total Knee Arthroplasty: A Case Report.

Introduction: Recently, Serratia marcescens was reported to cause nosocomial infections. Case Report: In this study, we report a case of S. marcescens infection occurring after total knee arthroplasty (TKA) in a 72-year-old woman. The patient had undergone TKA for knee osteoarthritis. She had a past medical history of diabetes mellitus, for which she was receiving cefazolin sodium. Six days after surgery, redness and effusion were observed in the wound, and post-operative infection was suspected. Thus, the patient was treated with linezolid, clindamycin, and tazobactam/piperacillin hydrate post-operatively. Twelve days after TKA, reinfection was suspected; hence, washing and debridement were repeated. Conclusion: In this case, remission of S. marcescens infection was achieved without the need to remove the implant by cleaning, debridement, and the use of sensitive antimicrobial agents.

Predicting Skeletal-related Events Using SINS.

STUDY DESIGN: Predictive study utilized retrospectively collected data. OBJECTIVE: The primary objective was to evaluate the predictive association between the Spine Instability Neoplastic Score (SINS) and Skeletal-related events (SREs). Secondary objectives included examining characteristics of cases with SINS < 6 among those who developed SRE, and evaluating the impact of additional predictors on prediction accuracy. SUMMARY OF BACKGROUND DATA: Advances in cancer treatment have prolonged the lives of cancer patients, emphasizing the importance of maintaining quality of life. Skeletal-related events from metastatic spinal tumors significantly impact quality of life. However, currently, there is no scientifically established method to predict the occurrence of SRE. SINS, developed by the Spine Oncology Study Group, assesses spinal instability using six categories. Therefore, the predictive performance of SINS for SRE occurrence is of considerable interest to clinicians. METHODS: This predictive study utilized retrospectively collected data from a single-center registry comprising over 1,000 patients with metastatic spinal tumors. SINS and clinical data were collected. Logistic regression was used to create a prediction equation for SRE using SINS. Additional analyses explored factors associated with SRE in patients with SINS < 6. RESULTS: The study included 1,041 patients with metastatic spinal tumors. SRE occurred in 121 cases (12%). The prediction model for SRE using SINS demonstrated an area under the curve (AUC) of 0.832. Characteristics associated with SRE included lower female prevalence, surgeries to primary sites, bone metastases to non-spinal sites, and metastases to other organs. A post hoc analysis incorporating additional predictors improved the AUC to 0.865. CONCLUSION: The SINS demonstrated reasonable predictive performance for SRE within one month of the initial visit. Incorporating additional factors improved prediction accuracy. The study emphasizes the need for a comprehensive clinical prediction model for SRE in metastatic spinal tumors.