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To determine whether medialization of the proximal tibia due to a varus deformity is related to lateralization of the tibial tuberosity in varus knee osteoarthritis (OA)., A total of 120 knees that underwent osteotomies around the knee for varus knee OA were enrolled. Mechanical medial proximal tibial angle (mMPTA) was measured on radiographs. The angle between the mechanical and anatomical axes of the tibia (angle MA) and the distance between the centre of the tibial plateau and the anatomical axis (distance MA) were measured in the coronal plane on computed tomography images. The tibial tuberosity-posterior cruciate ligament (TT-PCL) distance, the distance between the midpoint of the tibial tuberosity and the centre of the tibial plateau (TT-centre distance), and the angle between the line through the midpoint of the tibial tuberosity and the centre of the tibial plateau and the anteroposterior axis (TT-centre angle) were measured in the axial plane. The correlations of these parameters were evaluated., mMPTA correlated negatively with angle MA (r=-0.37, P, Medialization of the proximal tibia due to a varus deformity may induce lateralization of the tibial tuberosity.

To compare the radiographic, clinical, and arthroscopic outcomes of varus osteoarthritic knees treated with an open-wedge high tibial osteotomy (OWHTO) alone or with a double-level osteotomy (DLO). It was hypothesized that treatment with DLO would maintain the joint line obliquity (JLO) and acquire better arthroscopic and clinical outcomes after surgery than OWHTO alone. Knees with predicted medial proximal tibial angle (MPTA) > 95° were treated with OWHTO alone or with DLO. Preoperatively, age, body mass index, and hip-knee-ankle angle (HKA) differed between the two groups. Therefore, after adjustment for those factors, 34 knees with OWHTO alone and 34 knees with DLO were compared. On whole-leg radiographs for a single leg, HKA, weightbearing line (WBL) ratio, lateral distal femoral angle (LDFA), MPTA, and JLO were measured before and 2 years after surgery. Clinical outcomes were evaluated by the Knee Society Score (KSS) knee, KSS function, Lysholm, and Knee injury and Osteoarthritis Outcome Score (KOOS) scores before and 2 years after surgery. Arthroscopic findings were obtained before and 1 year after surgery. Various factors were compared between the two groups. JLO increased significantly from 1.4° to 6.3° in the OWHTO group (p

Preoperative supine joint line convergence angle (JLCA) correlates with postoperative standing JLCA. Here, we compared the radiographic and clinical outcomes of knees with preoperative JLCAs of ≥ 4° and

This study investigated the relationship between femoral shaft bowing and the orientation of the surgical transepicondylar axis (TEA) in the coronal plane in varus knee osteoarthritis (OA). A total of 82 knees scheduled to undergo total knee arthroplasty (TKA) for the treatment of varus knee OA were enrolled. The hip–knee-ankle angle (HKA) was measured preoperatively on anteroposterior whole-leg standing radiographs. The lateral angle between the TEA and the mechanical axis of the femur (MA-TEA) was measured in the coronal plane from preoperative computed tomography (CT) images. Femoral shaft bowing was measured on CT images. Pearson’s correlation coefficient was used to examine the correlation of the MA-TEA with the HKA and femoral shaft bowing. The MA-TEA correlated negatively with the HKA (r = − 0.321, P

The aim of this study was to investigate whether the tibial tuberosity–trochlear groove (TT–TG) distance and lateral patellar tilt, which induce patellofemoral osteoarthritis (OA), are related to the coronal deformity of the lower limb in varus knee OA. It was hypothesized that varus inclination of the tibia was negatively correlated with the TT–TG distance and lateral patellar tilt in Japanese female patients with moderate knee OA. A total of 104 female patients (139 knees) scheduled to undergo knee osteotomy for varus knee OA were enrolled. The coronal lower limb alignment was measured on anteroposterior whole-leg radiographs. The TT–TG distance, patellar tilt angle, and the patellofemoral joint space were measured both medially and laterally on computed tomography images. The correlations between coronal lower limb alignment and the TT–TG distance or patellar tilt angle, and the correlations between the TT–TG distance or patellar tilt angle and patellofemoral joint space were evaluated. The medial proximal tibial angle was negatively correlated with the TT–TG distance (r = − 0.383, P

While Yu and Poesio (2020) have recently demonstrated the superiority of their neural multi-task learning (MTL) model to rule-based approaches for bridging anaphora resolution, there is little understanding of (1) how it is better than the rule-based approaches (e.g., are the two approaches making similar or complementary mistakes?) and (2) what should be improved. To shed light on these issues, we (1) propose a hybrid rule-based and MTL approach that would enable a better understanding of their comparative strengths and weaknesses; and (2) perform a manual analysis of the errors made by the MTL model.

BackgroundTo investigate the relationship between femoral or tibial torsion and hip-knee-ankle angle (HKA), mechanical lateral distal femoral angle (mLDFA), or mechanical medial proximal tibial angle (mMPTA) in patients with medial knee osteoarthritis (OA).MethodsA total of 75 knees were enrolled. Femoral and tibial torsions were measured by superimposing the axial planes of computed tomography images. The relationship between femoral or tibial torsion and HKA, mLDFA, or mMPTA on radiographs was examined.ResultsThe mean femoral torsion was 12.2 ± 8.5° internally; femoral internal and external torsions were observed in 70 and 5 knees, respectively. The mean tibial external torsion was 18.0 ± 7.4° externally; tibial external torsion was observed in all 75 knees. Femoral internal and tibial external torsions increased with lower mMPTA (r = 0.33,P = 0.003;r = − 0.32,P = 0.005, respectively) but were not related to HKA or mLDFA.ConclusionFemoral and tibial torsions were correlated with varus inclination of the proximal tibia in patients with medial knee OA.

Background The reason why the osteotomy line in the sagittal view should be parallel to the medial tibial posterior slope in open wedge high tibial osteotomy (OWHTO) remains unclear. In addition, previous study reported that a posterolateral hinge position led to an increase in tibial posterior slope (TPS) after OWHTO. Our aims were to examine the relationships between angles among the tibial plateau and osteotomy planes or the hinge point and the change in TPS, and the location of the hinge position after OWHTO using three-dimensional computed tomography (3DCT). We hypothesized that the sagittal angle between the tibial plateau and osteotomy planes with an anterior-widening proximal tibial fragment resulted in increased TPS, and the hinge position located posterolaterally. Methods Preoperative planning anticipated a weight-bearing line ratio of 62% on the radiograph. The anterior gap was 67% of the posterior gap in OWHTO. We identified the tibial plateau and upper and lower osteotomy planes on 3DCT of 82 patients with symptomatic medial osteoarthritic knee after OWHTO. The osteotomy plane angles between the tibial plateau and upper osteotomy planes, and opening gap angles between both osteotomy planes in the coronal and sagittal views were measured. The anteroposterior (AP) and lateral hinge position was displayed as a percentage on the upper osteotomy plane. We assessed the relationships among them. Results The TPS significantly increased after OWHTO (p = 0.002). There was no significant difference between the sagittal osteotomy plane angle and the change in TPS. The sagittal opening gap angle and the AP hinge position ratio were significantly correlated with the change in the TPS (r = 0.477 p

The mobile traffic continuously grows at a rapid rate driven by the widespread use of wireless devices. Along with that, the demands for higher data rate and better coverage lead to increase in power consumption and operating cost of network infrastructure. The concept of heterogeneous networks (HetNets) has been proposed as a promising approach to provide higher coverage and capacity for cellular networks. HetNet is an advanced network consisting of multiple kinds of base stations, i.e., macro base station (MBS), and small base station (SBS). The overlay of many SBSs into the MBS coverage can provide higher network capacity and better coverage in cellular networks. However, the dense deployment of SBSs would cause an increase in the power consumption, leading to a decrease in the energy efficiency in downlink cellular networks. Another technique to improve energy efficiency while reducing power consumption in the network is to introduce sleep control for SBSs. This paper proposes cell throughput based sleep control which the cell capacity ratio for the SBSs is employed as decision criteria to put the SBSs into a sleep state. The simulation results for downlink communications demonstrate that the proposed scheme improves the energy efficiency, compared with the conventional scheme.

The carotid bulb has a high density of baroreceptors that play an important role in maintaining blood pressure. We hypothesized that atherosclerosis of the carotid bulb would reflect the severity of orthostatic hypotension more accurately than would atherosclerosis of other carotid artery segments.This cross-sectional study included 198 non-diabetic adults. We measured the cardio-vascular ankle index as an index of arterial stiffness, intima-media thickness in each carotid artery segment (internal carotid artery, carotid bulb, distal and proximal portions, respectively, of the common carotid artery) as a measure of atherosclerosis, and heart rate variability as a measure of cardiac autonomic function. The sit-to-stand test was used to assess severity of orthostatic hypotension.Intima-media thickness of the carotid bulb was correlated with orthostatic systolic blood pressure change (r = -0.218, p = 0.002), cardio-ankle vascular index (r = 0.365, p0.001) and heart rate variability parameters. Multivariate regression analysis revealed that among all of the segments, only intima-media thickness of the carotid bulb was an independent predictor of orthostatic systolic blood pressure change (p = 0.022).Atherosclerosis of the carotid bulb was associated with severity of orthostatic hypotension, arterial stiffening and cardiac autonomic dysfunction than that of other carotid artery segments.

For opening wedge high tibial osteotomy (OWHTO), it is recommended that the osteotomy line is parallel to the medial tibial posterior slope (TPS) in the sagittal view and that the alignments are simultaneously controlled in the coronal and sagittal views. Here combined computed tomography (CT)-based and image-free navigation systems were used for intraoperative reference during OWHTO. Using the CT-based navigation, 2 entry points for insertion of Kirschner wires were preoperatively set up and an accurate osteotomy plane was intraoperatively duplicated. Preoperative planning anticipated a femorotibial angle of 170°, representing a weight-bearing ratio of 62.5%, on the whole-leg radiograph. The original TPS in the sagittal view was aimed to be preserved postoperatively. The hip-knee-ankle (HKA) correction angle was preoperatively measured on the whole-leg radiograph, and the HKA angle and flexion angle were intraoperatively monitored in real time using the image-free navigation. We have introduced an operative technique for OWHTO using CT-based and image-free navigation systems. We expect that this method, with the osteotomy plane parallel to the tibial plateau plane in the sagittal view and simultaneous control of coronal and sagittal alignments, will enable actuation of accurate alignment in the 2 planes and lead to improvements in patient activity in future.

Hip arthroscopy is now a widely performed procedure. More than 30,000 procedures were performed internationally in 2008, and the expected annual increase is 15% [1]. Its advocates claim that it is less invasive than open procedures, and associated with earlier post op recovery [2e4]. More recent evidence, however, shows that the rate of complications associated with hip arthroscopy is higher than those of arthroscopic knee surgery [5e7]. Systematic review performed by Gupta et al. showed 285 complications in 6277 hip arthroscopic procedures (4.03%) [6]. These complications range from minor such as a neurapraxia to catastrophic such as a fluid extravasation into an abdominal compartment causing compartment syndrome. We report three patients who developed rapid onset osteoarthritis (OA) of the hip following hip arthroscopy who required total hip arthroplasty (THA), and discuss the importance of the soft tissue stabilizers of the hip for the prevention of the OA development after hip arthroscopy. All patients provided informed consent for the publication of this manuscript.

Background Coronal alignment is an important factor for the function and longevity of total knee arthroplasty (TKA). Coronal bowing of the lower extremity is common among Asians and it may pose a risk for malalignment of the lower leg and malposition of component. Hypothesis We hypothesized that coronal bowing itself has a risk for malalignment of the lower leg and malposition of femoral/tibial components and that navigation TKA is beneficial for patients with coronal bowing. We investigated the incidence of femoral/tibial bowing in patients treated with TKA and compared the radiographic parameters between the navigation group and the conventional group. Additionally, the influence of coronal bowing on these radiographic parameters was investigated. Materials and methods We enrolled 35 patients with knee osteoarthritis and 70 bilateral simultaneous TKAs. The patients underwent TKA with the use of a computer tomography-free navigation in one knee and conventional TKA in the contralateral knee. Preoperative coronal bowing were measured, and the subjects were divided into 2 subgroups, i.e. the bowing group and the non-bowing group. Lateral bowing was expressed as plus (+) and medial bowing was expressed as minus (−). Various radiographic parameters, including coronal bowing, lower leg alignment, component position, and outliers were compared between the navigation group and the conventional group. Results Femoral bowing varied from −7.4° to 10.9° with an average of 3.0°. Tibial bowing varied from −4.1° to 4.6° with an average of 0.4°. The femoral component was placed more properly in the navigation group. Number of outlier regarding to the coronal femoral component angle to the femoral mechanical axis was 14 cases (37.8%) in the bowing group and 6 cases (18.2%) in the non-bowing group ( P = 0.04). Discussion In conclusion, coronal femoral bowing has an important effect on femoral bone cut in TKA. The navigated TKA was more consistent than conventional TKA in aiding proper alignments of femoral component. Level of evidence Level II, comparative prospective study.

Background The coronal subluxation of the proximal tibia relative to the distal femur is a common radiological finding in patients with knee osteoarthritis. The purpose was to evaluate whether the coronal subluxation was corrected after opening wedge high tibial osteotomy (OWHTO), and whether this subluxation was one cause of inconsistency between the actual and predicted alignments (correction loss). Methods Fifty-one patients (55 knees) were treated with OWHTO. The change of location between the intersection points of the femoral and tibial axes on the tibial plateau (subluxation-C), the change of location between the lines through the most lateral points of the lateral femoral and tibial condyles (subluxation-L), and joint space angle (JSA) were compared in standing knee radiographs before and one year after OWHTO. The subluxation-C and subluxation-L were converted to a percentage of the tibial plateau width. Results The mean subluxation-C of 6.5% before OWHTO significantly increased to a mean subluxation-C of 7.3% one year after OWHTO. The mean subluxation-L of 6.3% and JSA of 4.5° before OWHTO significantly decreased to a subluxation-L of 1.8% and JSA of 3.3° one year after OWHTO. The change in subluxation-L correlated with the change in femorotibial angle and correction loss ( r =0.634, P r =0.463, P Conclusion The proximal tibia shifted medially relative to the distal femur after OWHTO. This medial shift correlated with the correction loss. The coronal subluxation might be one cause of correction loss.

A 24-year-old man with severe atopic dermatitis underwent anterior cruciate ligament (ACL) reconstruction of the right knee seven years earlier but developed a surgical site infection. The infection did not heal after removal of the metal implants, and a fistula eventually developed. This condition was left untreated for six years before he was referred to our hospital. Magnetic resonance imaging showed fluid in the tibial bone tunnel and extensive bone marrow edema surrounding the bone tunnel. Based on these findings, abscess formation within the tibial bone tunnel and osteomyelitis spreading to the proximal tibia were suspected. During the surgery, a portion of artificial ligament and non-absorbable suture were observed in the bone tunnel, and the infection healed immediately after removal of this complex. When surgical site infection occurs after ACL reconstruction, it is important to completely remove all artificial materials as early as possible.

Background The purpose of this study was to objectively investigate the initial fixation of highly porous cups in THA for femoral neck fractures. Methods THA for displaced femoral neck fractures was performed in 52 consecutive patients. We objectively measured the rotational torque for cup stability, and the primary endpoint was the success rate of press-fit fixation without screws. Results The success rate of press-fit fixation without screws was 96.1%. No specific complications were occurred. Conclusion The initial stability of highly porous cups was excellent for femoral neck fractures with a high success rate of press-fit fixation without screws.

Pre-operative templating for total hip arthroplasty (THA) remains inaccurate due to improper magnification and alignment. We aimed to describe an improved templating strategy using computed tomography (CT) to predict component sizes and offsets with greater accuracy. We analysed 184 CT images acquired for pre-operative templating of primary THA. We aimed to restore native (pre-arthritic) femoral offset and limb length, by raising the head center to the level of the templated cup center cranio-caudally, but maintaining the pathologic (pre-operative) head center medio-laterally (except in medialized hips). Acetabular offset (AO) and femoral offset (FO) were measured on pre-operative CT scans, during acetate templating, and on post-operative true antero-posterior radiographs. The post-operative offsets were within ± 5 mm from templated estimates in 174 hips (91%) for AO, in 116 hips (61%) for FO, in 111 hips (58%) for GO, and in 134 hips (70%) for neck cut level. The post-operative hip architecture reproduced the templated hip architecture within ±5 mm in 77 hips (40%). The agreement between planned and post-operative parameters was moderate for stem size (0.57), cup size (0.62), AO (0.50), but fair for FO (0.45). The AO decreased in most arthritic types, notably in lateralized hips (6.6 mm), but remained unchanged in medialized hips. The FO increased in most arthritic types (1.8–3.1 mm) but remained unchanged in medialized and lateralized hips. We described a strategy for pre-operative templating in THA. Despite the accuracy of CT, the authors found significant variations between planned and post-operative reconstructions, which suggest that pre-operative templating should only be used as an approximate guide.

Few studies evaluated clinical benefits of pre-operative templating in total hip arthroplasty (THA). We investigated whether mismatch between planned and real implant sizes and medio-lateral offsets compromises THA outcomes.We reviewed records of 184 primary THAs with pre-operative CT scans used for templating. Acetabular offset (AO), femoral offset (FO) and global offset (GO) were measured on pre-operative CT scans, during acetate templating, and post-operative antero-posterior radiographs. Multivariable analyses were performed to determine if Forgotten Joint Score (FJS) and Oxford Hip Score (OHS) at 2 years were associated with differences between post-operative and planned parameters.The FJS and OHS were not influenced by mismatch of component sizes nor of FO and GO. The FJS was better when the post-operative AO was greater than planned (p = 0.050). The FJS differed among arthritic types (p = 0.015). Multivariable analyses confirmed that older patients had better OHS (beta - 0.16; p = 0.033) and FJS (beta 0.74; p = 0.002), medialized hips had worse FJS (beta - 20.1; p = 0.041) and hips with greater AO than planned had better FJS (beta 1.71; p = 0.024) CONCLUSIONS: Implanting a component of different size than planned did not compromise THA outcomes, but medialized hips had worse scores, and conservative acetabular reaming improved scores.

Using a navigation system in open-wedge high tibial osteotomy (OWHTO) has higher accuracy than using the conventional method. However, unintentional over- and under-correction still exist. This study aimed to compare various factors related to over- and under-correction and to assess their predictive factors in the preoperative radiographs. This study involved 96 knees. The difference in the hip–knee–ankle angle (HKA) between the intraoperative navigation system and postoperative radiograph was termed navigation correction loss (NCL). Knees with absolute values of NCL (|NCL|) ≦ 1.5° and |NCL| > 1.5° were categorised into acceptable (n = 46) and outlier (n = 50) groups, respectively. The differences in joint line convergence angle (JLCA) between varus and valgus radiographs, varus JLCA, valgus JLCA, standing JLCA and standing HKA were compared between the two groups. Clinical results were evaluated using the American Knee Society (AKS) scores. The mean intraoperative HKA in the navigation system was − 3.8 ± 1.8°, and that in the postoperative standing radiograph was − 4.2 ± 2.5° (p = 0.033). Preoperative varus, valgus and standing JLCA were higher in the outlier group (p = 0.018, p = 0.020 and p = 0.001, respectively). Logistic regression analyses for preoperative factors of |NCL| ≦ 1.5° showed that standing JLCA was a determining factor, with an odds ratio of 1.334 (confidence interval was 1.087–1.637, p = 0.006). AKS score was higher in the acceptable group (p = 0.040) postoperatively. Higher preoperative standing JLCA was the predictive factor of |NCL| > 1.5°. This factor reduced the rates of under- and over-correction and resulted in better AKS score in OWHTO.

This study documented the healing potential of degenerated articular cartilage after opening-wedge valgus high tibial osteotomy (HTO) in patients with osteoarthritis of the knee. It was hypothesized that regeneration of articular cartilage is affected by several factors, including preoperative cartilage degeneration grade, difference between the medial femoral condyle (MFC) and the medial tibial condyle (MTC), and postoperative knee alignment. Medial opening-wedge valgus HTO was performed in 131 knees of 100 patients (mean age 66 ± 7.7 years). Initial arthroscopy was performed at the time of HTO, and a second-look arthroscopy was performed at the time of plate removal (20.8 ± 6.5 months after HTO). Status of articular cartilage was assessed according to the ICRS grade. Cartilage regeneration was also evaluated by the presence of newly formed cartilaginous tissue. All subjects were followed up postoperatively at 2 years for assessment of clinical and radiographic outcomes. The number of subjects in ICRS grade 1/2/3/4 was significantly altered from 0/11/53/67 preoperatively to 14/21/56/40 postoperatively in the MFC (P

This study aimed to investigate the incidence of venous thromboembolism (VTE) after medial opening-wedge high tibial osteotomy (OWHTO) and evaluate the efficacy and safety of edoxaban for the prevention of VTE in patients undergoing OWHTO. A total of 139 patients with osteoarthritis or osteonecrosis undergoing OWHTO were enrolled in this prospective, randomized study. Four patients were excluded because of preoperatively diagnosed VTE, and 135 patients were divided into two groups—an edoxaban group and a non-edoxaban group—and underwent computed tomography venography on day 7 to check for postoperative VTE. Blood samples were taken on the day before OWHTO and on postoperative days 1, 3, 7, and 14. Treatment with edoxaban reduced the incidence of VTE after OWHTO; however, there was no statistically significant difference between the two groups. No major bleeding was noted in the edoxaban group. There were significant differences in the D-dimer level, prothrombin time, fibrinogen level, and thrombin antithrombin complex levels between the groups. Edoxaban is an oral, once-daily, selective, direct factor Xa inhibitor that is safe and easy to handle. It may offer a new option for preventing VTE after OWHTO. I.

An encouraging result with direct anterior approach (DAA) is attractive for both patients and surgeons. However, the risks associated with beginning to use DAA require further analysis of the learning curve and better countermeasures to ensure safety. We ask whether the complication rate in the DAA by the inexperienced surgeon could be decreased with specific countermeasures. Our hypothesis was that the complication rate would be low even in early phase of the learning curve using the DAA with these particular countermeasures. We investigated a consecutive series of 120 primary THA using the DAA with four specific countermeasures; 1) defined exclusion criteria for DAA; 2) no positioning table; 3) use of fluoroscopy as much as required; and 4) having an experienced assistant for DAA (one who has performed the procedure in more than 100 cases). The operative time, the time of fluoroscopic use during the operation, intra and post-operative complications, re-operation for any reason, and cup and stem alignment were investigated. Although the operation times were similar, the duration of fluoroscopy decreased with surgeons’ experience. There were no intra-operative complications and no re-operations for any reason. One anterior dislocation was observed in one patient. The mean cup inclination and anteversion angle was 39.7° ± 7.6° and 30.3° ± 7.6°; 43.3 % of stems were positioned in flexion, 55.8 % in the neutral position on the lateral view. We demonstrated a lower complication rate during our early experience with the DAA using four countermeasures. Using these countermeasures for the first 40 cases may be useful for surgeons who are considering DAA.

Many reports outline the benefits derived from using the direct anterior approach (DAA) in primary total hip arthroplasty (THA); however, the learning curve for the DAA has not been well documented, and the complications associated with the DAA during this learning curve seem relatively high. The aim of this study was to investigate implant positioning in primary THA, when the surgeon was a novice at the DAA, and had previously used the standard posterior approach (PA).We investigated implant positioning in the first 80 consecutive THA cases performed by two senior surgeons using the DAA (with fluoroscopic assistance), and compared them to the same two surgeons' previous 80 respective THA cases performed using their previous standard posterior approach.Cup positioning accuracy was higher for the DAA (p 0.001) but greater cup anteversion (19.3° ± 11.0 using the PA vs 27.6° ± 6.3 using DAA, p 0.0001) was also demonstrated. A total of 69.3 % of cups in the DAA group were positioned with an anteversion angle greater than their target angle. In the DAA group the stem was more frequently positioned in flexion and less frequently in neutral than for the PA group.Although fluoroscopic assistance seemed to decrease complications such as femoral fracture, surgeons changing from PA to DAA for THA should consider potential excessive cup anteversion and flexion implantation of the stem in their early experience with DAA.

To assess potentially predictive factors that were evaluated 1 year after the onset of symptoms in patients with spontaneous osteonecrosis of the knee (SONK) and to determine receiver operating characteristic (ROC) curve cut-off values. Within 1 year of symptom onset, patients with SONK-selected treatment options, mainly based on severity of pain, chose either conservative treatment (n = 27 knees) or operative treatment (n = 27 knees). Knee and whole-leg radiographs, knee MRIs and bone mineral density scans of the lumbar spine, femoral neck and femoral condyles were obtained. The parameters measured were: (1) anatomical angle on whole-leg radiograph and (2) lesion size and medial meniscus extrusion on MRI. The anatomical angle and lesion size in the sagittal section (depth) on MRI were markedly larger in the operative treatment group than those in the conservative treatment group. The anatomical angle and depth on MRI of SONK at Stages 1–3 were significantly different between groups, with odds ratios (95 % confidence intervals) of 1.16 (1.18–2.34) and 1.11 (1.01–1.23). One year after symptom onset, ROC curve cut-off value for anatomical angle was 180° and depth on MRI was 20 mm. An anatomical angle >180° and depth >20 mm on MRI were predictive factors for a poorer prognosis 1 year after symptom onset in patients with SONK. Our results on radiographs and MRI provided a predictive prognosis for patients with SONK at the initial visit to their orthopaedic surgeons. III.

The original version of this article unfortunately contained a mistake. The spelling of the Geert Pagenstert name was incorrect.

Background The association of glycated albumin (GA) with mortality is unclear in chronic hemodialysis patients with diabetes. We investigated the usefulness of GA by comparing it with hemoglobin A1c (HbA1c) in this patient population. Research design and methods This was a multi-center, prospective cohort study of 841 Japanese chronic hemodialysis patients with diabetes. There were 235 women and 606 men included, with a mean age of 64 years. The primary and secondary endpoints were the incidence of all-cause and cause-specific mortality, respectively. The hazard ratios of GA and HbA1c for the endpoints were estimated using the values at baseline and during the study period. Results During the mean follow-up period of 3.1 years, there were 184 deceased cases, in which 30 and 154 resulted from atherosclerotic cardiovascular disease (ASCVD) and non-ASCVD, respectively. The hazard ratio for a 1% increase in GA was 1.033 (95% confidence interval 1.006–1.060, p = 0.017) for all-cause mortality with a statistical significance when GA was treated as a time dependent variable, but not when the baseline levels or the mean levels during the follow-up period were used in the analysis (p = 0.815 and 0.517, respectively). GA was a significant predictor for ASCVD-related mortality in the above 3 models, but was not for non-ASCVD mortality. Higher levels of HbA1c were only associated with ASCVD-related mortality when HbA1c was treated as a time-dependent variable. Conclusions GA may be useful compared to HbA1c for predicting all-cause and ASCVD-related mortality in Japanese patients with diabetes undergoing chronic hemodialysis.

Purpose: The purpose of this study was to investigate the surgical outcomes of total hip arthroplasty (THA) through direct anterior approach (DAA) performed by beginners by comparing the outcomes after the introduction of DAA-THA between using a normal operating table and a traction table. Methods: The total subjects were 200 patients, there were 120 cases from the introduction of three surgeons using a normal table and 80 cases from two surgeons using a traction table. The surgical procedure was standardized, and a surgeon skilled in DAA entered the operating room and instructed the novice surgeons of DAA in all cases. Results: The mean operative time was no significant difference between the two groups ( p = 0.093). The difference in slope of the operative time was no significant difference between the two groups ( p value = 0.089). The mean fluoroscopy time and the mean blood loss were significant difference between the two groups ( p < 0.05). The difference in slope of the fluoroscopy time and blood loss were significant difference between the two groups ( p < 0.05). There were no intraoperative complications and no reoperations for any reason. Conclusions: At the facility with a surgeon skilled in DAA, the use of a traction table in DAA did not increase the complication rate compared with the use of a normal operating table when the exclusion criteria for DAA were set and surgery was performed using intraoperative fluoroscopy under supervision by a skilled surgeon.

We evaluated the influence of settings on an ultrasound machine on the configuration of a single B-line in a healthy model and analyzed the frequency spectrum. We also devised simple experimental models that generated B-line-like artifacts and evaluated the influence of the machine settings on the configuration. Visualization of B-lines was affected by the spatial compound imaging, the focal zone and the frequency. The spectra of both the B-line and non-B-line region at the same depth had the same center frequency and bandwidth. B-line-like artifact was generated by a spindle-shaped juice sac of a mandarin orange, an edible string-shaped glucomannan gel, glass beads and glass plates. Visualization of B-line-like artifacts was also affected by these machine settings. Our study indicated that the physical basis of some B-lines is multiple reverberations. B-line-like artifacts provide clues for solving key issues, such as the physical basis of B-lines, the sonographic-pathologic correlation in B-lines and the effects of machine settings.

Background: Although surgical shoulder stabilization by coracoid transfer is effective for collision athletes and has a low reinjury rate, no reports have described the midterm results of this procedure in specific patient cohorts of sufficient number or provided subjective assessments of these patients. Purpose: To evaluate midterm results after treatment of shoulder instability with the Bristow procedure in a large cohort of rugby players. Study Design: Case series; Level of evidence, 4. Methods: This study included 176 shoulders of 152 competitive rugby players who underwent shoulder stabilization surgery (Bristow procedure with Bankart repair) with a mean follow-up of 4 years (minimum of 2 years) in our institute. The primary outcome measure was the difference in the presurgical and postsurgical functional Rowe score and Western Ontario Shoulder Instability index (WOSI) score and factors affecting these scores. Complication rates and associated factors were also investigated. Results: In total, 176 shoulders of 152 patients underwent the Bristow procedure with Bankart repair, and 93.2% of the players returned to their preinjury competition level at a mean of 6.3 months postoperatively. All Rowe and WOSI scores were significantly improved after surgery. The numbers of shoulders with functional failure as indicated by the Rowe score, WOSI score, and inability to return to the previous level of play were 28 (15.9%), 54 (30.7%), and 12 (6.8%), respectively. Multiple logistic regression analyses demonstrated that reinjury after surgery (odds ratio [OR] = 35.1) and the number of shoulder dislocations (OR = 11.2-11.4) negatively affected the competition level after return to play, while reinjury (OR = 11.1-17.8), the number of shoulder subluxations (OR = 1.1-2.9), injury in the dominant shoulder (OR = 1.2-2.2), and large bone defects (OR = 1.1-11.5) negatively affected functional scores. Reinjury after shoulder stabilization occurred in 6 of 176 shoulders (3.4%). Multiple logistic regression analysis demonstrated that reinjury after surgery occurred more frequently in players at lower versus higher grade levels of competition (OR = 21.0). Although differences were not significant, a trend was noted toward higher postoperative reinjury rates in forward players, those in the upper categories (professional and college), and those with injury in the nondominant shoulder. Conclusion: The Bristow procedure provides good midterm outcomes for competitive collision athletes, while postsurgical reinjury, the number of preoperative dislocations and subluxations, and large bone defects negatively affect postsurgical shoulder function. This information may be useful for treatment of shoulder dislocations in collision athletes.

Although injury of the lateral femoral cutaneous nerve (LFCN) is a known complication after total hip arthroplasty (THA) via the direct anterior approach (DAA), the impact of this complication on postoperative quality of life (QOL) is unclear. This study aims to investigate the incidence of LFCN injury after DAA for THA, and to determine the impact of LFCN injury on QOL and hip function.We prospectively investigated 122 hips operated upon using the DAA regarding the incidence of LFCN injury using self-reported questionnaires, hip functional scores such as the Harris Hip Score (HHS) and the Japanese Orthopaedic Association (JOA) score, and patient-reported outcomes such as the Western Ontario and McMaster Universities Osteoarthritis Index, the Japanese Orthopaedic Association Hip disease Evaluation Questionnaire (JHEQ), and the Forgotten Joint Score-12 (FJS).LFCN injury was seen in 39 hips (31.9 %). In affected hips, the leading symptom was hypo-aesthesia (46.2 %), followed by tingling or jolt-like sensation (28.2 %). There was no difference in the HHS and JOA score between those with LFCN injury and those without. There was a significant difference in the FJS-12 between the two groups (50.9 ± 25.3 for hips with LFCN injury vs 64.3 ± 25.7 without, p = 0.01). There was a non-significant tendency for patients with LFCN injury to have a lower JHEQ than those without (63.6 ± 19.6 for hips with LFCN injury vs 70.8 ± 22.9 without, p = 0.13).The incidence of LFCN injury decreased QOL but not hip function after DAA for THA.

The Forgotten Joint Score-12 (FJS-12) is for patients to forget their artificial joint and is reportedly a useful patient-reported outcome tool for artificial joints. The purpose of this study was to determine whether the FJS-12 is as useful as the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) or the Japanese Orthopaedic Association Hip Disease Evaluation Questionnaire (JHEQ) in Japan. All patients who visited our hospital’s hip joint specialists following unilateral THA from August 2013 to July 2014 were evaluated. Medical staff members other than physicians administered three questionnaires. Items evaluated were (1) the reliability of the FJS-12 and (2) correlations between the FJS-12 and the total and subscale scores of the WOMAC or JHEQ. Of 130 patients, 22 were excluded. Cronbach’s α coefficient was 0.97 for the FJS-12. The FJS-12 showed a significantly lower score than the WOMAC or JHEQ (p

The relationship between the surgical epicondylar axis (SEA) and the rotational axis of the distal femur remains unclear. We investigated the relationship between the SEA and the distal femur and whether the SEA can be used as the rotational axis of the knee. Angular and linear measurements of 70 femora at 0°, 30°, 60°, 90°, and 120° of flexion were recorded. Results showed that the SEA was a logical and appropriate parameter as a principal axis for knee flexion at least between 0° and 60° of flexion. The study has important implications for the design and positioning of femoral components in total knee arthroplasty.

Background Scapular dyskinesis is observed in subjects with pathologic conditions of the shoulder; however, there is limited information about the factors related to scapular dyskinesis among participants in rugby. The purpose of this study was to investigate the incidence, reliability, and relationships between scapular dyskinesis and variables related to the shoulder in high-school rugby players. Methods A total of 164 Japanese high-school rugby players were evaluated with questionnaires, physical examinations, and a video analysis during their preseason. After evaluation of the inter-rater reliability of a classification of scapular dyskinesis, the outcomes were analyzed to assess the relationships between scapular dyskinesis and other variables during the preseason. The data were assessed with a logistic regression analysis calculating the odds ratios (OR). Results The inter-rater reliability among 3 blinded observers based on the Fleiss κ value and percentage agreement was .52 and 79.0%, respectively, which indicates that the method is moderately reliable. Scapular dyskinesis was identified in 16 (10.1%) shoulders among 159 players, with type I being prominent. A multivariate logistic regression analysis revealed that a type I dyskinesis was significantly associated with a past history of stingers with projected pain to the affected side of the shoulder (OR, 3.7) and the player's competitive grade at the time of the survey (OR, 3.9). Conclusions Scapular dyskinesis is significantly associated with a past history of stingers. This suggests that stingers are a causative factor of scapular dyskinesis in the rugby population. Our method of evaluating scapular dyskinesis in collision athletes exhibits moderate reliability.

ObjectiveAlthough positive pleural lavage cytology (PLC) has been demonstrated to be closely associated with a poor prognosis for patients with lung cancer, it has not been incorporated into the TNM staging system of the Union for International Cancer Control. The aim of our study was to retrospectively examine the clinical significance of PLC status and illustrate the recommendations of the International Pleural Lavage Cytology Collaborators (IPLCC) in a large national database.MethodsThe Japanese Joint Committee of Lung Cancer Registry database included 11,073 patients with non–small cell lung cancer who underwent resections in 2004. We extracted the clinicopathologic data for 4171 patients (37.3%) who underwent PLC. These patients were staged according to the seventh edition of the Union for International Cancer Control TNM classification and by recommendations of the IPLCC, in which T was singly upgraded up to a maximum of T4 for those who were PLC-positive. Prognoses based on these 2 systems were compared.ResultsA total of 217 patients (5.2%) were PLC-positive, which was significantly associated with a higher incidence of adenocarcinoma and advanced disease. The 5-year survival for patients with positive and negative PLC results were 44.5% and 72.8%, respectively, and this difference in survival was statistically significant (P

Introduction It is essential to understand rotational alignment of the distal femur when performing total knee arthroplasty (TKA). Several rotational landmarks including condylar twist angle (CTA) are used for preoperative planning and during TKA. Axial radiography of the distal femur is used for measuring the CTA, and assessing rotational alignment in TKA. The aim of this study was to investigate the reliability and the reproducibility of the CTA using two different methods and evaluate if CTA differed between varus and valgus knees and between normal and osteoarthritic knees. Materials and methods CTA were obtained from 144 knees (77 patients) having total knee or hip arthroplasty using computed tomography (CT) and axial radiography. Subjects were divided into five groups based on femorotibial angle (FTA) and into four groups based on the severity of knee osteoarthritis. The intra-observer and inter-observer reliabilities of these methods and inter-method differences were evaluated. Results The mean CTA was 7.02° with axial radiography, and 6.87° with CT images. There were no significant differences among the five FTA groups and among the four osteoarthritis groups. In total, intra-/inter-observer, and inter-method intraclass correlation coefficients were substantial or almost perfect in the scoring system of Landis et al. However, discrepancies ≥ 2° between the two methods were observed in more than 20% of knees. Conclusion The CTA should be reassessed by more than two observers or two methods for precise preoperative TKA planning in cases where it is difficult to identify the bony landmarks for CTA measurements. Level of evidence Level III.

To assess whether the increased inclination of the tibial plateau on the coronal view after opening-wedge high tibial osteotomy affects radiographic coronal alignment, clinical outcomes, and cartilage findings.After adjustment for the preoperative medial proximal tibial angle (MPTA), patients who underwent opening-wedge high tibial osteotomy were retrospectively divided into those with postoperative MPTA values of 95° or less (normal group) and greater than 95° (increased group), with each group containing 43 knees. The 2 groups were compared regarding their arthroscopic cartilage findings at 1 year postoperatively and radiographic coronal alignment and clinical outcomes at 2 years postoperatively. Cartilage regeneration in the medial condyles and cartilage deterioration in the lateral condyles were evaluated at the time of second-look arthroscopy. Clinical outcomes were evaluated by the American Knee Society knee and function scores, Lysholm knee scoring scale, and Knee Injury and Osteoarthritis Outcome Score (KOOS).The postoperative anatomic femorotibial angle in the increased group was lower than that in the normal group (P.001), and the amount of overcorrection in the increased group was higher than that in the normal group (P.001). The postoperative joint line obliquity in the increased group was higher than that in the normal group (P.001). Cartilage regeneration in the medial condyles and deterioration in the lateral condyles did not differ significantly on the femoral and tibial sides between the groups. The postoperative American Knee Society knee score and KOOS sports and recreational function subscale score in the normal group were higher than those in the increased group (both P.001).There were no significant differences in the changes in the appearance of the articular surfaces between the 2 groups at 1 year postoperatively. Patients with a postoperative MPTA greater than 95° had more valgus alignment and higher joint line obliquity and had a lower KOOS sports and recreational function subscale score than patients with a postoperative MPTA of 95° or less at 2 years postoperatively.Level III, retrospective comparative study.

In 2005, the Japanese government issued the technical standard (the General High-Pressure Gas Safety Ordinance, hereinafter referred to as the General Ordinance) for hydrogen refueling stations (HRSs) that provide fuel to fuel cell vehicles (FCVs) equipped with a 35MPa hydrogen container on board[1]. Then, the maximum storage pressure of container on board increased from 35MPa to 70MPa. Along with this, the maximum storage pressure of facilities of HRSs also increased from 40MPa to 82MPa[2]. In Japan, many HRSs are being built to realize hydrogen society. For this purpose, it is urgent to select materials to be used in a high pressure hydrogen environment and to establish a range of use.

Recently, the concept of heterogeneous networks (HetNets) has been proposed as an alternative solution to provide higher coverage and capacity for cellular networks. In HetNets concept, many of small base stations (SBSs) are employed in the existing cell of macro base stations (MBSs) to increase the coverage and system capacity. However, the employment of many SBSs in the existing macro cells would causes the increase in power consumption with decreasing the energy efficiency in downlink cellular networks. To solve this problem, this paper proposes a cell throughput based sleep control scheme for the SBSs in HetNets. In the proposed scheme, the cell capacity ratio for the SBSs is employed as decision criteria to put the SBSs into sleep state. From various simulation results, the proposed scheme can achieve better energy efficiency and better system throughput than the conventional schemes.

This paper proposes a channel estimation and equalization methods for a transmit diversity system of using time domain training sequence inserted orthogonal frequency division multiplexing (TS-OFDM) signal in higher time-varying fading channels. The salient feature of the proposed channel impulse response (CIR) estimation method for the transmit diversity system with a space frequency block coding is to employ a new design of training sequence (TS) signal which can reduce the leakage of power spectrum density (PSD) and keep higher CIR estimation accuracy. In the proposed equalization method, the estimated CIR at every sampling time and the known TS signals are employed at the receiver for removing the inter-symbol interference (ISI) caused in higher time-varying fading channels so as to employ the overlap and add (OLA) operation. This paper presents various simulation results to demonstrate the effectiveness of the proposed transmit diversity system as comparing with the conventional methods.

Background We evaluated bone union and remodelling in patients undergoing opening-wedge high tibial osteotomy (OWHTO) with bone gaps filled with beta-tricalcium phosphate. We examined the effectiveness of radiography and computed tomography (CT) for the evaluation of bone union and remodelling, and investigated whether lateral hinge fractures affected bone union. Methods Sixty-six cases underwent OWHTO with a combination of a TomoFix plate and a bone substitute. Bone union and remodelling were assessed using the rating system for OWHTO at three and six months, postoperatively. Results Radiographic evaluation showed that bone union of the lateral hinge was 85% and 100% at three and six months, respectively. Based on CT evaluation, bone union of the lateral hinge and the flange was achieved in all cases at six months, and the bone union of the posterior cortex reached Zone 3 in 83% at six months. Based on radiographic evaluation, bone remodelling phases of bone substitute had progressed in each zone in six months compared with three months. Radiographic and CT analyses identified a Takeuchi type I hinge fracture in fourteen (21.2%) and five (7.6%) knees at two weeks postoperatively, respectively. There were no differences in bone union with and without the lateral hinge fracture. Conclusions The use of CT enabled us to evaluate the bone union of the flange and the extent of the bone union of the posterior cortex. Plain radiographs are useful to evaluate bone union of the lateral hinge similar to CT analysis. The presence of a Takeuchi type I hinge fracture did not affect bone union.

Introduction: Although total hip arthroplasty (THA) is superior to bipolar hemiarthroplasty (BHA) for displaced femoral neck fracture in terms of hip pain, function and reoperation rate, THA has a higher rate of dislocation. The direct anterior approach (DAA) and a dual mobility cup (DMC) are associated with lower rates of dislocation. The aim of this study was to investigate the outcomes of THA compared with BHA, and in those patients who had a THA we investigated those with a DMC (DMC-THA) and compared them with those had a single conventional cup (Single cup-THA). Materials: A total of 89 patients living independently were included between 2009 and 2015. We assessed patient characteristics, peri- and post-operative outcomes, walking ability and one-year mortality. Adjusted odds ratios (Adjusted ORs) were estimated for decrease of walking ability and one-year mortality using a logistic regression model with adjustment for potential confounders such as age, neuromuscular diseases with weakness, duration of surgery, perioperative blood loss and preoperative walking ability. Results: BHA (20 patients) versus THA (69 patients): There was no significant difference in the walking ability in either group. Multivariable logistic regression analysis demonstrated a significant association with one-year mortality in both groups [THA Adjusted ORs 0.088 (95% CI 0.0007–0.69); p = 0.020]. Single cup-THA (36 patients) versus DMC-THA (33 patients): The DMC-THA group had significantly greater age and more patients with neuromuscular diseases with weakness compared with the Single cup-THA group. Multivariable logistic regression analysis demonstrated no significant difference in the decrease of walking ability and in the one-year mortality between the groups. There were no post operative dislocations in any group. Discussion: THA via the DAA is one of the best treatments for displaced femoral neck fracture with a low risk of dislocation. THA via the DAA with a DMC is a safe and effective treatment for the patients with a high risk of dislocation.

We present a case of successful and uncomplicated total hip arthroplasty with an acetabular reinforcement device in an elderly patient with hip osteoarthritis already diagnosed with factor XI deficiency, which is a very rare bleeding disorder and at high risk of post-operative haemorrhage, and it poses a substantial challenge to surgeons as a consequence of the specific risks of infection and fixation failure. Moreover, bone fragility in elderly patient increases potential risk of adverse event. Fresh frozen plasma was used to supplement factor XI activity. Importantly, transfusion-transmitted disease such as having factor XI inhibitor was promptly surveyed prior to the supplement since the patient had previous history of the administration of fresh frozen plasma. Under prompt and effective peri-operative haemostasis, rigid implant fixation and rigorous attention to the prevention of infection seem to achieve the best possible outcomes for elderly patients with a bleeding disorder undergoing total hip arthroplasty.

To assess which tibial slope measurements on knee, whole leg radiographs and three-dimensional reconstructed computed tomography (CT) were useful in clinical practice before and after opening wedge high tibial osteotomy. Medial and lateral tibial slopes on knee, whole leg radiographs and three-dimensional reconstructed CT were measured in 50 patients with knee osteoarthritis. To investigate the intraobserver reproducibility and interobserver reliability for each medial and lateral tibial slope on knee, whole leg radiographs and CT, the measurements were repeated twice by two observers. The statistical differences between the medial and lateral tibial slopes obtained by the three methods, and the differences and correlation coefficients for the medial and lateral tibial slopes between knee or whole leg radiographs and CT were calculated. The reproducibility and reliability of medial and lateral tibial slopes on CT were superior to those on whole leg or knee radiographs. The medial and lateral tibial slopes on whole leg radiographs had better reproducibility and reliability than those on knee radiographs. The mean medial tibial slopes on knee, whole leg radiographs and CT were 9.3 ± 3.4°, 12.3 ± 4.3° and 11.0 ± 3.9°, respectively. The mean lateral tibial slopes were 7.9 ± 3.1°, 9.6 ± 3.6° and 9.3 ± 2.9°, respectively. The medial tibial slopes on knee, whole leg radiographs and CT were significantly higher than the lateral tibial slopes (p

Introduction Indications for surgical resection for small cell lung cancer (SCLC) have been very limited. Because early-stage SCLC is a rare presentation of lung cancer, studies comparing surgical resection among a large number of patients are unlikely to be conducted. This study reports the most recent surgical outcomes of a large number of SCLC patients who underwent surgery in 2004. Methods: In 2010, the Japanese Joint Committee of Lung Cancer Registry performed a nationwide retrospective registry study regarding the prognosis and clinicopathologic profiles of 11,663 patients who underwent resection for primary lung cancer in 2004. Of the 11,663 patients, 243 patients with SCLC (2.1%) were included in this study. The registry data of the patients with SCLC were analyzed, and the clinicopathologic profiles and surgical outcomes of the patients were evaluated. Results: The 5-year survival rate for all cases ( n = 243, 213 males, mean age 68.2 years) was 52.6%. The 5-year survival rates by c-stage and p-stage were as follows: IA, 64.3% ( n = 132) and 72.3% ( n = 93); IB, 45.7% ( n = 36) and 61.1% ( n = 51); IIA, 50.5% ( n =25); and 44.8% ( n = 27); IIB, 33.3% ( n = 10) and 40.3% ( n = 17); IIIA, 30.5% ( n = 30) and 23.4% ( n = 45); and IV, 0% ( n = 7) and 0% ( n = 9), respectively. A multivariate analysis showed that the significant prognostic factors were age, gender, c-stage, and surgical curability. A kappa value was moderate conformity between c-stage and p-stage in all cases. Conclusions: Surgical resection in selected patients with early-stage SCLC, especially stage I, had favorable results.

Between 2003 and 2007, 99 knees in 77 patients underwent opening wedge high tibial osteotomy. We evaluated the effect of initial stable fixation combined with an artificial bone substitute on the mid- to long-term outcome after medial opening-wedge high tibial osteotomy (HTO) for medial compartmental osteoarthritis or spontaneous osteonecrosis of the knee in 78 knees in 64 patients available for review at a minimum of five years (mean age 68 years; 49 to 82). The mean follow-up was 6.5 years (5 to 10). The mean Knee Society knee score and function score improved from 49.6 (sd 11.4, 26 to 72) and 56.6 (sd 15.6, 5 to 100) before surgery to 88.1 (sd 12.5, 14 to 100) and 89.4 (sd 15.6, 5 to 100) at final follow-up (p < 0.001) respectively. There were no significant differences between patients aged ≥ 70 and < 70 years. The mean standing femorotibial angle was corrected significantly from 181.7° (sd 2.7°, 175° to 185°) pre-operatively to 169.7° (sd 2.4°, 164° to 175°) at one year’s follow-up (p < 0.001) and 169.6° (sd 3.0°, 157° to 179°) at the final follow-up (p = 0.69 vs one year).Opening-wedge HTO using a stable plate fixation system combined with a bone substitute is a reliable procedure that provides excellent results. Although this treatment might seem challenging for older patients, our results strongly suggest that the results are equally good.Cite this article: Bone Joint J 2014;96-B:339–44.

Rapidly destructive coxarthrosis (RDC) is rare and develops unusual clinical course. Recent studies suggest multiple possible mechanisms of the development of RDC. However the exact mechanism of RDC is still not clear. The difficulty of the study on RDC is attributed to its rareness and the fact that the data before the onset of RDC is normally unavailable. In this report, we presented the patient having the radiographic data before the onset who had rapid osteoarthritis (OA) development after contralateral THA, which meets the current criteria of RDC. We thought that the increased posterior tilt of the pelvis after THA reinforced the stress concentration at pre-existed anterior acetabular cyst, thereby the destruction of the cyst was occurred. As a result the rapid OA was developed. We think that there is the case of rapid osteoarthritis developing due to alternating load concentration by posterior pelvic tilt on preexisting anterior acetabular cyst such as our patient among the cases diagnosed as RDC without any identifiable etiology. The recognition of sagittal alignment changes and anterior acetabular cyst may play important role in prediction and prevention of the rapid hip osteoarthritis development similar to RDC.