Aims. We evaluated the national and regional trends from 2013 to 2022, in the prevalence of Perthes’ disease among adolescent males in South Korea. Methods. This retrospective, nationwide, population-based study included a total of 3,166,669 Korean adolescent males examined at regional Military Manpower Administration (MMA) offices over ten years. Data from the MMA were retrospectively collected to measure the national and regional prevalence per 100,000 and 95% CI of Perthes’ disease according to the year (1 January 2013 to 31 December 2022) and history of pelvic and/or femoral osteotomy in South Korea. Spearman’s correlation analysis was performed to assess the relationship between the Perthes’ disease prevalence and several related factors. Results. The prevalence of Perthes’ disease showed a gradually increasing trend for a ten-year follow-up period from 2013 to 2022 with a mean of 71.17 (95% CI 61.82 to 80.52) per 100,000, ranging from 56.02 (95% CI 48.34 to 63.71) in 2013 to 77.53 (95% CI 67.94 to 87.11) in 2019. The proportion of patients with a Stulberg classification ≥ III ranged from 50.57% in 2015 to 80.08% in 2019, showing a gradually increasing trend. Following the trend for Perthes’ disease, an increase in the proportion of pelvic and/or femoral osteotomies was observed, whereas conservative treatment decreased in adolescent males. For a ten-year follow-up period, the prevalence of Perthes’ disease was highest in provinces, followed by the metropolitan area and Seoul. Conclusion. The prevalence of Perthes’ disease in adolescent males increased over time from 2013 to 2022. In particular, the trend in the prevalence of Perthes’ disease with incongruent hips was significantly associated with overweight and obesity rates among male adolescents with a very high level of correlation. Cite this article: Bone Joint J 2025;107-B(1):42–49

The purpose of this study was to determine the annual incidence of Perthes’ disease in Korea and compare this with other populations. A survey identified all newly diagnosed children with Perthes’ disease aged 14 years or younger in South Honam, Korea, between January 1999 and December 2001. A total of 84 children were included: 29 in 1999, 28 in 2000 and 27 in 2001. The mean annual incidence was 3.8 per 100 000. This is similar to that reported in other Asian countries, but higher than in black populations and lower than in Caucasians

Introduction: The incidence of Legg-Calvé-Perthes Disease (LCPD) has varied considerably both between countries and between population groups. The incidence of LCPD has not been reported in Korea. The purpose of this study was to determine the annual incidence of LCPD in Korea and to compare this to other population groups. Materials and Methods: Firstly, only LCPD children who were living in Chonnam Province, Korea, and were aged 14 years and under during the years 1999, 2000, and 2001, were reviewed to measure the annual incidence. Secondly, for a further study regarding the variables related to the epidemiological interest, 816 hips, which were treated at our hospital during the last 32 years from 1972 to 2003, were reviewed. Results: The population aged 14 years and under was 734,645 in 1999, 728,721 in 2000, and 719,504 in 2001. Among them, the number of LCPD children was 29 in 1999, 28 in 2000, and 24 in 2001. The annual incidence was 3.9 per 100, 000 in 1999, 3.8 in 2000, and 3.3 in 2001, with a mean incidence of 3.7 per 100, 000. Discussion: The annual incidence of LCPD in Korean children aged 14 years and under was 3.7 per 100,000. This Korean incidence was lower than the 5.1 to 21.1 per 100,000 incidence reported in Caucasians and higher than the 0.45/100,000 reported in blacks or mixed decent. The incidence of gender, bilaterally, age of disease onset, extent of head involvement, and other related epidemiological parameters was similar to those reported in other studies

Alternative bearing surfaces has been introduced to reduce wear debris-induced osteolysis after total hip arthroplasty (THA) and offered favorable results. Large population-based data for total joint surgery permit timely recognition of adverse results and prediction of events in the future. The purpose of this study was to present the epidemiology and national trends of bearing surface usage in primary total hip arthroplasty (THA) in Korea using nationwide database. A total of 30,881 THAs were analyzed using the Korean Health Insurance Review and Assessment Service database for 2007 through 2011. Bearing surfaces were sub-grouped according to device code for national health insurance claims and consisted of ceramic-on-ceramic (CoC), metal-on-polyethylene (MoP), ceramic-on-polyethylene (CoP), and metal-on-metal (MoM). The prevalence of each type of bearing surface was calculated and stratified by age, gender, hospital type, primary payer, and procedure volume of each hospital. The number of primary THAs increased by 25.2% from 5,484 in 2007 to 6,866 in 2011. The average age of the entire study population was 58.1 years, and 53.5% were male [Table 1]. CoC was the most commonly used bearing surface (76.7%), followed by MoP (11.9%), CoP (7.3%), and MoM (4.1%). The distribution of bearing surfaces was identical to that in the general population regardless of age, gender, hospital type, and primary payer [Table 2]. The mean age of patients that received hard-on-hard bearing surfaces (CoC and MoM) was significantly younger than that of patients receiving hard-on-soft bearing surfaces (CoP and MoP) (56.9 years vs. 62.6 years). During the study period, 55.1% of THAs that used a hard-on-hard bearing surface were performed in males, while 53.0% of THAs that used a hard-on-soft bearing surface were performed in females. The order of prevalence of bearing surfaces was identical in low- and medium-volume hospitals (CoC was first, MoP was second, CoP was third, and MoM was fourth). The mean hospital charges did not differ according to the bearing surface used, with the exception of CoP, which was associated with a lower mean hospital charge. There were no changes in the distribution of bearing surfaces in each year between 2007 and 2011. Overall, the percentage of THAs that used CoC bearing surfaces increased substantially from 71.6% in 2007 to 81.4% in 2011, while the percentage that used CoP, MoP, and MoM decreased significantly [Fig. 1]. One of the reasons for the dominant usage of hard-on-hard bearing surfaces may be that the principal diagnosis of primary THAs and the patient age group distribution in Korea differ from those in other countries. The most common indication for primary THA is osteonecrosis of the femoral head in Korea. In contrast, the majority of primary THAs are performed for osteoarthritis in Western countries. The choice of bearing surface may be affected by many factors, including the nation's medical delivery system, payment type, disease pattern, and age distribution of patients that undergo THA. In future, the results of a large-scale nationwide study on primary THAs using CoC bearing surfaces in Korea will be reported. For any figures or tables, please contact authors directly (see Info & Metrics tab above).

Although the clinical manifestation of ONFH is well summarized as forms of various stages, its etiology, natural history or epidemiology has not been clearly elucidated yet. With this study, we wanted to find out the estimated annual incidence, epidemiologic characteristics and the effect of known risk factors of ONFH. Therefore we can understand the disease better to provide optimal management to the patients. Among 133 189 patients who diagnosed as osteonecrosis of femoral head (ONFH) in database of national health insurance system in Korea from 2002 to 2006, three hundreds an eighty-two samples were randomly extracted with 5% error range in 95% confidence interval. With a structured worksheet, medical records and radiographs of each sample were reviewed at corresponding clinic or hospital by authors and trained orthopedic surgeons. With these data, we calculated the prevalence and associated risk factors. The mean number of annual requests was 23 466. Among 382 samples, two hundreds and seventy-four were confirmed to have ONFH. Diagnostic accuracy was 71.7 %. Diagnosis was more accurate when the patient was male or hospitalized. After the logistic regression analysis, calculated diagnostic accuracy during 2002 and 2006 was 60.3% (51 823/85 987). The annual predicted number of cases of ONFH during this period was 14 103. It corresponds to 28.91 patients per 100 000 populations. Alcohol abuse was noted in 45% and 22% was related to use of steroid. 37% showed bilateral involvement. Bone graft procedures in any kind was the most frequently performed joint preserving procedure. With this, the first epidemiologic study for ONFH in Korea, we estimated nationwide annual prevalence of ONFH as 28.91 per 100,000 populations during 2002 and 2006. There is an absolute male predominance. Alcohol abuse is the most frequent risk factors. We believe that this result can serve as a baseline data for understanding the epidemiology, clinical characteristics and treatment of ONFH

The final results up to 15 years are reported of clinical trials of the management of tuberculosis of the spine in Korea and Hong Kong. In Korea, 350 patients with active spinal tuberculosis were randomised to ambulatory chemotherapy or bed rest in hospital (in Masan) or a plaster-of-Paris jacket for nine months (in Pusan). Patients in both centres were also randomised to either PAS plus isoniazid for 18 months or to the same drugs plus streptomycin for the first three months. In Hong Kong, all 150 patients were treated with the three-drug regime and randomised to either radical excision of the spinal lesion with bone graft or open debridement. On average, the disease was more extensive in Korea, but at 15 years (or 13 or 14 years in a proportion of the patients in Korea) the great majority of patients in both countries achieved a favourable status, no evidence of CNS involvement, no radiological evidence of disease, no sinus or clinically evident abscess, and no restriction of normal physical activity. Most patients had already achieved a favourable status much earlier. The earlier results of these trials are confirmed by the long-term follow-up with no late relapse or late-onset paraplegia. The results of chemotherapy on an outpatient basis were not improved by bed rest or a plaster jacket and the only advantage of the radical operation was less late deformity compared with debridement. A second series of studies has shown that short-course regimes based on isoniazid and rifampicin are as effective as the 18-month regimes: ambulatory chemotherapy with these regimes should now be the main management of uncomplicated spinal tuberculosis

Introduction. Total knee arthroplasty (TKA) is a proven treatment method for advanced knee arthritis in terms of pain relief, function restoration, and quality-of-life improvement. The TKA use has increased significantly over the past decade and the growing rate is more prominent in Asian countries. Thus, the revision TKA may also increase in recent days, which represents a burden to the national health care system. To the best of our knowledge, little information is currently available regarding the incidence and related factors of revision TKA in Asian countries on the basis of nationwide database. This study sought to find the incidence of revision TKA and related factors in South Korea using national database from 2007 to 2012. Material and Method. Data collected by the Health Insurance Review Agency of Korea, from 260,068 TKA patients between 2007 and 2012, were used to estimate the incidence of revision TKA according to age group, gender and hospital TKA and manufacturer prosthesis volume (i.e., the number of TKA procedures carried out at a given hospital, and the number of procedures performed using a given manufacturer's prosthesis, respectively). Age group and hospital and manufacturer volumes were categorized into three groups and TKA incidence rates were computed for groups stratified according to age, gender and hospital and manufacturer volumes. Result. Incidence rates per 100,000 person-years were as follows: 1) by age: < 65 years, 447.2; 65–74 years, 363.7; ≥ 75 years, 270.9, 2) by gender: male, 537.8; female, 346.1; 3) by hospital volume (procedures/year): < 20, 536.9; 20–199, 432.3; ≥ 200, 300.1; and 4) by manufacturer volume (prostheses/year): < 1500, 772.3; 1500–3999, 453.9; ≥ 4000, 345.6. TKA incidence rate in young males was significantly higher compared to that in elderly females. The difference in cumulative incidence, between hospitals with an annual volume of < 20 procedures and those with a volume of 20–199 procedures, was reduced for manufacturers with an annual volume of ≥ 4000. Similarly, the difference in cumulative incidence between manufacturers with an annual volume of < 1500 and those with a volume of 1500–3999 was reduced in hospitals with an annual volume of ≥ 200. Conclusions. Revision TKA incidence varied according to age, gender and hospital and manufacturer volumes. This data could inform clinical decisions and healthcare strategies

Purpose:. To investigate treatment patterns and efficacy of postoperative strong opioids in patients who underwent total knee arthroplasty (TKA) in Korea. Methods:. A prospective, non-interventional study of 301 patients who underwent TKA and received strong opioids following patient controlled analgesia (PCA) was conducted by reviewing patient charts and diaries from 19 teaching hospitals. Clinical characteristics, strong opioid treatment patterns, efficacy of strong opioid on a scale of 0–10, and opioid-related adverse events (AEs) were investigated during hospitalization and at first outpatient visit. Safety analysis was conducted on 301 patients, and efficacy analysis was conducted on full analysis set (FAS) which consisted of all the patients who had at least 1 efficacy result among 301 patients. Results:. Among the FAS population of 298 patients, 86.9% were female, and mean age was 68.7 ± 7.5 years. Average duration of PCA was 4.3 ± 1.7 days, and average length of hospital stay including surgery was 16.3 ± 7.6 days. The mean duration of strong opioid prescription on a regular basis between PCA discontinuation and discharge was 10.3 ± 6.7 days. At the initial treatment with strong opioid following PCA, mean pain intensity score was 6.1 ± 2.1 upon movement and 4.2 ± 2.4 at rest. At discharge, mean pain intensity score was 4.1 ± 1.9 upon movement and 2.3 ± 1.8 at rest. Meanwhile, pain intensity score at the first outpatient visit was assessed only in 146 patients (49.0%) treated with opioid, and mean pain intensity scores upon movement and at rest were 3.5 ± 2.1 and 1.7 ± 1.8, respectively. Most frequently prescribed opioid was oral oxycodone (47.4%), followed by pethidine injection (17.2%), oral oxycodone/naloxone (12.6%), and transdermal fentanyl (12.0%). Additionally, the most frequently prescribed opioid on a regular basis was oral oxycodone (53.3%), and that on a PRN (pro re nata) basis was pethidine injection (48.4%). Among treatments, mean duration and mean daily dose of oral oxycodone during hospitalization were 6.1 ± 5.6 days and 13.9 ± 8.2 mg, 1.6 ± 1.2 days and 45.5 ± 24.5 mg for pethidine injection, 7.3 ± 5.3 days and 16.2 ± 7.3 mcg/hr for transdermal fentanyl, and 9.4 ± 8.0 days and 23.2 ± 16.8 mg/11.6 ± 8.34 mg for oral oxycodone/naloxone. At discharge, 150 patients (50.3%) were prescribed opioids. The most frequently prescribed strong opioid as discharge medications and their mean daily dose were 17.9 ± 10.5 mg of oxycodone (56.6%), 26.8 ± 17.0 mg/13.4 ± 8.5 mg of oxycodone/naloxone (17.1%), and 15.9 ± 6.1 mcg/hr of fentanyl (11.4%). Of 301 patients, 36 opioid-related AEs were reported in 26 patients (8.6%); the most frequently reported opioid-related AEs were nausea/vomiting in 13 patients (4.3%) experiencing 17 events, constipation in 10 patients (3.3%) experiencing 10 events, and sedation in 3 patients (1.0%) experiencing 3 events. Conclusion:. The first nationwide non-interventional study was conducted to investigate treatment patterns and efficacy of strong opioids in patients who underwent TKA. Among these patients, strong opioids provided favorable pain relief and were well tolerated at relatively low dose following PCA till the first outpatient visit

In two centres in Korea 350 patients with a diagnosis of tuberculosis of the thoracic and/or lumbar spine were allocated at random: in Masan to in-patient rest in bed (IP) for six months followed by out-patient treatment or to ambulatory out-patient treatment (OP) from the start; in Pusan to out-patient treatment with a plaster-of-Paris jacket (J) for nine months or to ambulatory treatment without any support (No J). All patients recieved chemotherapy with PAS with isoniazid for eighteen months, either supplemented with streptomycin for the first three months (SPH) or without this supplement (PH), by random allocation. The main analysis of this report concerns 299 patients (eighty-three IP, eighty-three OP, sixty-three J, seventy No J; 143 SPH, 156 PH). Pre-treatment factors were similar in both centres except that the patients in Pusan had, on average, less extensive lesions although in a greater proportion the disease was radiographically active. One patient (J/SPH) died with active spinal disease and three (all No J/SPH) with paraplegia. A fifth patient (IP/PH) who died from cardio respiratory failure also had pulmonary tuberculosis. Twenty-three patients required operation and/or additional chemotherapy for the spinal lesion. A sinus or clinically evident abscess was either present initially or developed during treatment in 41 per cent of patients. Residual lesions persisted in ten patients (four IP, two OP, one J, three No J; six SPH, four PH) at five years. Thirty-two patients had paraparesis on admission or developing later. Complete resolution occurred in twenty on the allocated regimen and in eight after operation or additional chemotherapy or both. Of the remaining four atients, all of whom had operation and additional chemotherapy, three died and one still had paraparesis at five years. Of 295 patients assessed at five years 89 per cent had a favourable status. The proportions of the patients responding favourably were similar in the IP (91 per cent) and OP (89 per cent) series, in the J (90 per cent) and No J (84 per cent) series and in the SPH (86 per cent) and PH (92 per cent) series

Aims

Joint arthroplasties may be associated with a blood loss, which necessitates transfusion. Especially, hip arthroplasties are highly associate with transfusion to compensate perioperative bleeding. Orthopaedic surgeons and patients have increasing concerns regarding complications of blood transfusions. Although various methods to reduce transfusions have been attempted in TJA, a high percentage of patients require a transfusion during and after the procedures. The purposes of this study were to evaluate the trends of the transfusion(transfusion rates, transfusion amounts, economic burden) in hip arthroplasties, using nationwide data from the National Health Insurance Service (NHIS).

After exclusions, 265 patients with tuberculosis of the thoracic and/or lumbar spine were followed for three years from the start of treatment. They were randomly allocated to four daily regimens of chemotherapy: 1) isoniazid plus rifampicin for 6 months (6HR, 65); 2) the same drugs as in 1) but for 9 months (9HR, 71); 3) isoniazid plus paraaminosalicylic acid (PAS) or ethambutol for 9 months (9P/EH, 62); or 4) the same drugs as in 3) but for 18 months (18P/EH, 67). All patients were ambulatory from the start of chemotherapy and no form of splintage or support or operation was used in any case. Over half (55%) the patients were children and one-third had sinuses or clinically evident abscesses. At three years a favourable status, defined as no sinus nor clinically evident abscess, no myelopathy with functional impairment, no surgery nor additional chemotherapy, full physical activity with disease quiescent clinically and radiographically, was achieved in 203 patients (77%) and in another 41 (15%) in all respects except radiographically. Only 20 patients (8%) had an unfavourable status the proportion being highest (19%) in the 9P/EH series. Thirteen of these were classified as unfavourable solely because they had needed additional chemotherapy; only seven still had an unfavourable status at three years. The clinical results at three years were thus excellent in all series except the 9P/EH, in which more patients had required additional chemotherapy. In the 88 patients with sinuses or abscesses on admission, the rate of resolution was similar in all the series; most lesions (83%) had resolved by 12 months.(ABSTRACT TRUNCATED AT 250 WORDS)

Two hundred and eighty-three patients with tuberculosis of the thoracic and/or lumbar spine have been followed for 10 years from the start of treatment. All patients received PAS plus isoniazid daily for 18 months, either with streptomycin for the first three months (SPH) or no streptomycin (PH), by random allocation. There was also a second random allocation for all patients: in Masan to inpatient rest in bed (IP) for six months followed by outpatient treatment or to ambulatory outpatient treatment from the start (OP), and in Pusan to outpatient treatment with a plaster-of-Paris jacket (J) for nine months or to ambulatory treatment without any support (No J). A favourable status was achieved on their allocated regimen by 88% of patients at 10 years. Some of the remaining patients also attained a favourable status after additional chemotherapy and/or operation, and if these are included the proportion achieving such a status increases to 96%. There were five patients whose deaths were attributed to their spinal disease. A sinus or clinically evident abscess was present on at least one occasion in the 10-year period in 42% of the patients. Residual sinuses persisted at 10 years in two patients, at death at seven years in a third and at default in the seventh year in a fourth. Thirty-five patients had paraparesis at some time during the 10-year period, including two who died with paraplegia before five years. Complete resolution occurred in 26 patients (in six after additional chemotherapy and/or surgery). At 10 years two patients had severe paraplegia and one a moderate paraparesis.(ABSTRACT TRUNCATED AT 250 WORDS)

It is still difficult to determine an appropriate hinge position to prevent fracture in the lateral cortex of tibia in the process of making an open wedge during biplane open wedge high tibial osteotomy. The objective of this study was to present a biomechanical basis for determining the hinge position as varus deformity. T Three-dimensional lower extremity models were constructed using Mimics. The tibial wedge started at 40 mm distal to the medial tibial plateau, and osteotomy for three hinge positions was performed toward the head of the fibula, 5 mm proximal from the head of the fibula, and 5 mm distal from the head of the fibula. The three tibial models were made with varus deformity of 5, 10, 15 degrees with heterogeneous material properties. These properties were set to heterogeneous material properties which converted from Hounsfield's unit to Young's modulus by applying empirical equation in existing studies. For a loading condition, displacement at the posterior cut plane was applied referring to Hernigou's table considering varus deformity angle. All computational analyses were performed to calculate von-mises stresses on the tibial wedges. The maximum stress increased to an average of 213±9% when the varus angle was 10 degrees compared to 5 degrees and increased to an average of 154±8.9% when the varus angle was 15 degrees compared to 10 degrees. In addition, the maximum stress of the distal position was 19 times higher than that of the mid position and 5 times higher than that of the proximal position on average. Conclusion:. For varus deformity angles, the maximum stress of the tibial wedge tended to increase as the varus deformity angle increased. For hinge position of tibial wedge, maximum stress was the lowest in the mid position, while the highest in the distal position. *This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (NRF-2022R1A2C1009995)

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

Aims. National hip fracture registries audit similar aspects of care but there is variation in the actual data collected; these differences restrict international comparison, benchmarking, and research. The Fragility Fracture Network (FFN) published a revised minimum common dataset (MCD) in 2022 to improve consistency and interoperability. Our aim was to assess compatibility of existing registries with the MCD. Methods. We compared 17 hip fracture registries covering 20 countries (Argentina; Australia and New Zealand; China; Denmark; England, Wales, and Northern Ireland; Germany; Holland; Ireland; Japan; Mexico; Norway; Pakistan; the Philippines; Scotland; South Korea; Spain; and Sweden), setting each of these against the 20 core and 12 optional fields of the MCD. Results. The highest MCD adherence was demonstrated by the most recently established registries. The first-generation registries in Scandinavia collect data for 60% of MCD fields, second-generation registries (UK, other European, and Australia and New Zealand) collect for 75%, and third-generation registries collect data for 85% of MCD fields. Five of the 20 core fields were collected by all 17 registries (age; sex; surgery date/time of operation; surgery type; and death during acute admission). Two fields were collected by most (16/17; 94%) registries (date/time of presentation and American Society of Anesthesiologists grade), and five more by the majority (15/17; 88%) registries (type, side, and pathological nature of fracture; anaesthetic modality; and discharge destination). Three core fields were each collected by only 11/17 (65%) registries: prefracture mobility/activities of daily living; cognition on admission; and bone protection medication prescription. Conclusion. There is moderate but improving compatibility between existing registries and the FFN MCD, and its introduction in 2022 was associated with an improved level of adherence among the most recently established programmes. Greater interoperability could be facilitated by improving consistency of data collection relating to prefracture function, cognition, bone protection, and follow-up duration, and this could improve international collaborative benchmarking, research, and quality improvement. Cite this article: Bone Joint J 2023;105-B(9):1013–1019

Glutamate regulates the expression of apoptosis-related genes and triggers the apoptosis of fibroblasts in rotator cuff tendons. Subacromial bursitis is always accompanied by symptomatic rotator cuff tear (RCT). However, no study has been reported on the presence of glutamate in subacromial bursa and on its involvement of shoulder pain in patients who had RCT. The purposes of this study were to determine whether the glutamate expression in subacromial bursa is associated with the presence of RCT and with the severity of shoulder pain accompanying RCT. Subacromial bursal tissues were harvested from patients who underwent arthroscopic rotator cuff tendon repair or glenoid labral repair with intact rotator cuff tendon. Glutamate tissue concentrations were measured, using a glutamate assay kit. Expressions of glutamate and its receptors in subacromial bursae were histologically determined. The sizes of RCT were determined by arthroscopic findings, using the DeOrio and Cofield classification. The severity of shoulder pain was determined, using visual analog scale (VAS). Any associations between glutamate concentrations and the size of RCT were evaluated, using logistic regression analysis. The correlation between glutamate concentrations and the severity of pain was determined, using the Pearson correlation coefficient. Differences with a probability <0.05 were considered statistically significant. Glutamate concentrations showed significant differences between the torn tendon group and the intact tendon group (P = 0.009). Concentrations of glutamate significantly increased according to increases in tear size (P < 0.001). In histological studies, the expressions of glutamate and of its ionotropic and metabotropic receptors have been confirmed in subacromial bursa. Glutamate concentrations were significantly correlated with pain on VAS (Rho=0.56 and P =0.01). The expression of glutamate in subacromial bursa is significantly associated with the presence of RCT and significantly correlated with its accompanying shoulder pain. Acknowledgements: This research was supported by the Basic Science Research Program, through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2015R1D1A3A01018955 and 2017R1D1A1B03035232)

It is known that the gait dynamics of elderly substantially differs from that of young people. However, it has not been well studied how this age-related gait dynamics affects the knee biomechanics, e.g., cartilage mechanical response. In this study, we investigated how aging affects knee biomechanics in a female population using subject-specific computational models. Two female subjects (ages of 23 and 69) with no musculoskeletal disorders were recruited. Korea National Institute for Bioethics Policy Review Board approved the study. Participants walked at a self-selected speed (SWS), 110% of SWS, and 120% of SWS on 10 m flat ground. Three-dimensional marker trajectories and ground reaction forces (Motion Analysis, USA), and lower limbs’ muscle activities were measured (EMG, Noraxon USA). Knee cartilage and menisci geometries were obtained from subjects’ magnetic resonance images (3T, GE Health Care). An EMG-assisted musculoskeletal finite element modeling workflow was used to estimate knee cartilage tissue mechanics in walking trials. Knee cartilage and menisci were modeled using a transversely isotropic poroviscoelastic material model. Walking speed in SWS, 110%, and 120% of SWS were 1.38 m/s, 1.51 m/s, and 1.65 m/s for the young, and 1.21 m/s, 1.34 m/s and 1.46 m/s for the elderly, respectively. The maximum tensile stress in the elderly tibial cartilage was ~25%, ~33%, and ~32% lower than the young at SWS, 110%, and 120% of SWS, respectively. These preliminary results suggest that the cartilage in the elderly may not have enough stimulation even at 20% increases in walking speed, which may be one reason for tissue degeneration. To enhance these findings, further study with more subjects and different genders will investigate how age-related gait dynamics affects knee biomechanics. Acknowledgments: Australian NHMRC Ideas Grant (APP2001734), KITECH (JE220006)

Aims. Hospital case volume is shown to be associated with postoperative outcomes in various types of surgery. However, conflicting results of volume-outcome relationship have been reported in hip fracture surgery. This retrospective cohort study aimed to evaluate the association between hospital case volume and postoperative outcomes in patients who had hip fracture surgery. We hypothesized that higher case volume would be associated with lower risk of in-hospital and one-year mortality after hip fracture surgery. Methods. Data for all patients who underwent surgery for hip fracture from January 2008 to December 2016 were extracted from the Korean National Healthcare Insurance Service database. According to mean annual case volume of surgery for hip fracture, hospitals were classified into very low (< 30 cases/year), low (30 to 50 cases/year), intermediate (50 to 100 cases/year), high (100 to 150 cases/year), or very high (> 150 cases/year) groups. The association between hospital case volume and in-hospital mortality or one-year mortality was assessed using the logistic regression model to adjust for age, sex, type of fracture, type of anaesthesia, transfusion, comorbidities, and year of surgery. Results. Between January 2008 and December 2016, 269,535 patients underwent hip fracture surgery in 1,567 hospitals in Korea. Compared to hospitals with very high volume, in-hospital mortality rates were significantly higher in those with high volume (odds ratio (OR) 1.10, 95% confidence interval ((CI) 1.02 to 1.17, p = 0.011), low volume (OR 1.22, 95% CI 1.14 to 1.32, p < 0.001), and very low volume (OR 1.25, 95% CI 1.16 to 1.34, p < 0.001). Similarly, hospitals with lower case volume showed higher one-year mortality rates compared to hospitals with very high case volume (low volume group, OR 1.15, 95% CI 1.11 to 1.19, p < 0.001; very low volume group, OR 1.10, 95% CI 1.07 to 1.14, p < 0.001). Conclusion. Higher hospital case volume of hip fracture surgery was associated with lower in-hospital mortality and one-year mortality in a dose-response fashion. Cite this article: Bone Joint J 2020;102-B(10):1384–1391

Purpose. The purpose of this study is to report the results of the first 1000 cases hip arthroplasty using the Bencox. ®. hip stem, the first hip prosthesis developed and manufactured in Korea. Material & Method. This study reviewed 1000 cases retrospectively who underwent arthroplasty using Bencox. ®. hip system. The Bencox. ®. hip stem is the first hip prosthesis developed and manufactured in Korea. This stem have a double-tapered, wedge shape figure with a rectangular-shaped cross-section and specially designed neck shape, which is design to achieve normal stress pattern of the proximal femur and to increase initial stability and to increase range of motion. Surface is treated with MAO (Micro Arc Oxidation) coating. From the first arthroplasty with this system in September 2006, sequentially 1000 arthroplasties were performed by single surgeon until the July 2014. This material included 439 men and 561 female. Average age of patients was 65 year old. Follow up period was average 72.1 month (minimum 34 months to maximum 120 months). 1000 cases consisted of 569 hips in patients with femoral neck or intertrochanteric fracture or subtrochanteric fracture (fracture group), 155 hips in osteoarthritis, 192 hips in patients with osteonecrosis of the femoral head (arthritis group), 84 hips in revision surgery (revision group). Revision cases consisted of 58 hips with aseptic loosening and 26 hips with loosening due to infection sequelae. They were underwent hip arthroplasty using a Bencox. ®. hip stem in combination with Bencox. ®. bipolar cup and Bencox. ®. acetabular cup. Patients in the fracture group usually underwent bipolar hip arthroplasty, and those in the arthritis group and revision group underwent total hip arthroplasty. They were reviewed by medical records, clinically and radiologically. Results. During the follow-up period, there were no cases of revision of the femoral stem. Radiographically, there were no cases of radiolucent line except very proximal part of the stem endosteal bone ongrowth was found in most cases. Postoperative complications such as stem loosening, infection, dislocation, and ceramic breakage were not noted. But periprosthetic fracture was encountered in 7 hips due to slip down. They were treated by open reduction and internal fixation with plate and cables. There were no cases of failure of these treatments. Conclusion. Clinical and radiographic evaluations of hip arthroplasty using the Bencox. ®. hip system showed excellent outcomes with average 72.1 month follow-up in 1000 case

Total Hip Arthroplasty (THA) has been more frequently performed for relatively young patients with osteonecrosis of the femoral head in Korea. Moreover, squatting and sitting with crossed legs are more common in Asian cultures than in Western cultures. Wear debris generated by conventional metal-on-PE articulations has been giving rise to extensive osteolysis. Due to these characteristics, higher incidence of pelvic osteolysis was observed after THA in Korea. As a result, interest in alternative bearings such as ceramic-on-ceramic bearing has been increased. Furthermore, the patients who require revision THA are still young in Korea. With this point of view, an application of ceramic-on-ceramic bearing throughout revision THA seems to be reasonable. The clinical and radiographical outcomes after revision THA with use of third generation ceramic-on-ceramic bearing in Korean patients were evaluated. Materials and Methods: We have analyzed 42 hips (37 patients; 17 men and 20 women), in whom revision THAs were performed using cementless cups with ceramic-on-ceramic bearing (Biolox Forte; CeramTec, Plochingen, Germany). They underwent THA at a single institution between February 2000 and December 2004, and were consecutively enrolled in this study. Their mean age was 48.8 years (32 – 59 years), and their mean weight was 61.5 ± 5.8 kg (50 – 72 kg) and BMI was 23.8. The mean interval from primary to revision THA was 9.5 ± 3.2 years (3.3 – 16.1 years). The preoperative diagnoses for primary THA were osteonecrosis of the femoral head in 31 hips, neglected femoral neck fracture in 3, rheumatoid arthritis in 2, degenerative osteoarthritis in 2, pyogenic arthritis in 2, tuberculosis arthritis in 1, and fused hip in 1. Dissociation of PE liner was observed in 21 hips (50%). For acetabular cup revision, Trilogy ceramic acetabular cups (Zimmer, Warsaw, IN) were used in 22 hips, EP-FIT plus cups (Plus Orthopedics, Rotkreuz, Switzerland) in 14 hips, and Duraloc Option Ceramic cups (DePuy, Warsaw, IN) in 6 hips. Stems were revised in all hips. The follow-up protocol included radiographic and clinical evaluations, and the mean duration of follow-up monitoring after revision THA was 5.4 ± 1.7 years (3.2 – 8.0 years). At final follow-up examination, clinical outcomes including Harris Hip Score and complications were assessed. All changes in inclination were documented radiographically. The presence of radiolucent lines, vertical or horizontal migration of acetabular cup (> 2 mm), and osteolysis were also evaluated. Results: At final follow-up evaluation after revision, the average Harris Hip Score was 91.3. There were no revised hips during follow-up period. In 6 hips (14.3%), minor complications were observed: 3 heterotopic ossifications, 2 dislocations, 1 infection. No revision was necessary for the treatment of these complications. There were no hips with radiolucent lines, vertical or horizontal acetabular cup migration or osteolysis during the follow-up period. In 21 hips with bone graft, incorporation of bone graft was observed radiographically at final follow-up examination. Conclusions: Our data showed that clinical and radiographical outcomes after revision THA using third generation ceramic-on-ceramic bearing were favorable. Revision THA with the use of ceramic-on-ceramic bearing surfaces can be preferentially considered especially in young patients. Further studies with long-term follow-up data are warranted