Radiological characteristics of skeletal growth in neonates and infants with achondroplasia.

Achondroplasia (ACH) is the most common form of skeletal dysplasia characterized by a rhizomelic short stature. Radiological skeletal findings in pediatric and adult patients with ACH include short long bones, a relatively longer fibula compared to the tibia, a narrow lumbar interpedicular distance, and a hypoplastic iliac wing. Nonetheless, the characteristics of skeletal growth during the neonatal and infantile periods have scarcely been explored. Therefore, this retrospective study aimed to analyze the radiological skeletal growth during the neonatal and infantile periods in 41 Japanese patients with genetically confirmed ACH. The length of long bones in the upper and lower limbs and the lumbar interpedicular distances at L1 and L4 were measured. These parameters showed significant positive correlations with age. The upper segment-to-lower segment ratio in the lower limbs resembled the data of healthy controls from previous reports. The L1/L4 and fibula/tibia ratios increased with age, suggesting that some representative skeletal phenotypes of ACH were less distinct during the neonatal and infantile periods. In conclusion, for the first time, this study radiologically characterized skeletal growth during the neonatal and infantile periods of patients with genetically confirmed ACH.

Effect of Organic Solvent on the Mass Transfer Mechanism of Coumarin 102 in a Single Octadecylsilyl Silica Gel/Organic Solvent-Water System by Laser Trapping and Fluorescence Microspectroscopy.

Understanding mass transfer kinetics within individual porous particles is crucial for theoretically explaining the retention and elution behaviors in chromatography and drug delivery. Using laser trapping and fluorescence microspectroscopy, we investigated the diffusion mechanism of coumarin 102 (C102) into single octadecylsilyl particle in acetonitrile (ACN)/water, N,N-dimethylformamide (DMF)/water, and 1-butanol (BuOH)/water solutions. The intraparticle diffusion behavior of C102 was evaluated using the spherical diffusion equation, allowing us to determine the intraparticle diffusion coefficients (Dintra): (8-10) × 10-9 cm2 s-1 for ACN, (10-16) × 10-9 cm2 s-1 for DMF, and (4-6) × 10-9 cm2 s-1 for BuOH. The obtained Dintra values were further analyzed using a pore and surface diffusion model. Thus, we revealed that the diffusion mechanism of C102 differed depending on the organic solvent: surface diffusion for ACN and DMF and pore and surface diffusions for BuOH were observed. This difference is attributed to the formation of a concentrated liquid phase of ACN and DMF at the interface of the alkyl chain and the bulk solution in the pore.

Disseminated septic arthritis caused by Ureaplasma urealyticum in an immunocompromised patient with hypogammaglobulinemia after rituximab therapy.

PURPOSE: Ureaplasma urealyticum is a rare pathogen associated with septic arthritis that predominantly affects patients with hypogammaglobulinemia. Bacterial identification of fastidious organisms is challenging because they are undetectable by routine culture testing. To the best of our knowledge, this is the first report of septic arthritis induced by U. urealyticum infection in Japan. CASE DESCRIPTION: We describe the case of a 23-year-old Japanese female with secondary hypogammaglobulinemia (serum immunoglobulin level < 500 mg/dL), identified 8 years after treatment with rituximab. The patient presented with persistent fever and polyarthritis that were unresponsive to ceftriaxone and prednisolone. Contrast-enhanced computed tomography and gallium-67 scintigraphy revealed effusion and inflammation in the left sternoclavicular, hip, wrist, knee, and ankle joints. Although Gram staining and bacterial culture of the drainage fluid from the left hip joint were negative, the condition exhibited characteristics of purulent bacterial infection. The patient underwent empirical treatment with doxycycline, and her symptoms promptly resolved. Subsequent 16S ribosomal RNA (rRNA) gene sequencing of the joint fluid confirmed the presence of U. urealyticum, leading to the diagnosis of septic arthritis. Combination therapy with doxycycline and azithromycin yielded a favorable recovery from the inflammatory status and severe arthritic pain. CONCLUSION: This case highlights U. urealyticum as a potential causative agent of disseminated septic arthritis, particularly in patients with hypogammaglobulinaemia. The 16S rRNA gene analysis proved beneficial for identifying pathogens in culture-negative specimens, such as synovial fluid, in suspected bacterial infections.

Genetic Disruption of cyp21a2 Leads to Systemic Glucocorticoid Deficiency and Tissues Hyperplasia in the Teleost Fish Medaka (Oryzias latipes).

cytochrome P-450, 21-hydroxylase (cyp21a2), encodes an enzyme required for cortisol biosynthesis, and its mutations are the major genetic cause of congenital adrenal hyperplasia (CAH) in humans. Here, we have generated a null allele for the medaka cyp21a2 with a nine base-pair insertion which led to a truncated protein. We have observed a delay in hatching and a low survival rate in homozygous mutants. The interrenal gland (adrenal counterpart in teleosts) exhibits hyperplasia and the number of pomca-expressing cells in the pituitary increases in the homozygous mutant. A mass spectrometry-based analysis of whole larvae confirmed a lack of cortisol biosynthesis, while its corresponding precursors were significantly increased, indicating a systemic glucocorticoid deficiency in our mutant model. Furthermore, these phenotypes at the larval stage are rescued by cortisol. In addition, females showed complete sterility with accumulated follicles in the ovary while male homozygous mutants were fully fertile in the adult mutants. These results demonstrate that the mutant medaka recapitulates several aspects of cyp21a2-deficiency observed in humans, making it a valuable model for studying steroidogenesis in CAH.

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

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

Expression of Acetabular Labral Vascular Endothelial Growth Factor and Nerve Growth Factor Is Directly Associated with Hip Osteoarthritis Pain: Investigation by Immunohistochemical Staining.

The acetabular labrum enhances hip joint stability and plays a key role in osteoarthritis (OA) progression. Labral nerve endings contribute to hip OA pain. Moreover, vascular endothelial growth factor (VEGF) and nerve growth factor (NGF) are associated with pain. Consequently, we analysed VEGF and NGF expression levels in the labrum and their roles in OA. Labra obtained from OA patients were stained immunohistochemically, and labral cells were cultured and subjected to a reverse transcription (RT)-polymerase chain reaction (PCR) to analyse VEGF and NGF mRNA expression. VEGF and NGF expression were compared in each region of the labrum. Correlations between VEGF and NGF expression and age, body mass index, Kellgren-Lawrence grade, Harris Hip Score, the visual analogue scale (VAS), and Krenn score were analysed, and the RT-PCR confirmed the findings. VEGF and NGF expression were high on the labral articular side, negatively correlated with the Krenn score, and positively correlated with the VAS in early OA. VEGF and NGF mRNA expression increased significantly in patients with severe pain and decreased significantly in severely degenerated labra. In early OA, VEGF and NGF expression in the acetabular labrum was associated with the occurrence of hip pain; therefore, these factors could be effective targets for pain management.

Spatiotemporal plant hormone analysis from cryosections using laser microdissection-liquid chromatography-mass spectrometry.

Laser microdissection (LMD) is used for isolating specific regions or single cells from a wide variety of tissue samples under direct microscopic observation. The LMD method enables the harvest of the cells of interest in a region or specific cells for several analyses, such as DNA/RNA analysis, proteomics, metabolomics, and other molecular analyses. Currently, LMD is used to study various biological events at the tissue or cellular level; it has been used in a wide range of research fields. In this report, we describe techniques for isolating different tissues/specific cells from cryosections of incised Arabidopsis flowering stems by LMD for spatiotemporal quantitative plant hormone analysis. The endogenous indole-3-acetic acid levels in the epidermis/cortex, vascular bundles, and pith of Arabidopsis flowering stems were approximately 19.0 pg mm-3, 33.5 pg mm-3, and 3.32 pg mm-3, respectively, and these endogenous levels were altered spatiotemporally after incision. We also analyzed jasmonic acid from LMD-isolated cells and showed that the endogenous levels increased in the range of approximately 200-3,500 pg mm-3 depending on the tissue and region at 1 h after incision and then decreased to less than 100 pg mm-3 or undetectable levels at 24 h after incision. Quantitative analyses of phytohormones, including jasmonic acid-related molecules, gibberellin, abscisic acid, and cytokinins, could also be performed using the same cell samples. These results showed that spatiotemporal changes in plant hormones could be quantitatively and simultaneously analyzed by LMD-isolated cells from cryosections with positional information. The combination of quantitative analysis by liquid chromatography-mass spectrometry (LC-MS) and sampling by the LMD method provides a comprehensive and quantitative understanding of spatiotemporal changes in plant hormones in a region- and tissue-specific manner. Therefore, LMD-LC-MS methods will contribute to our understanding of the physiological events that control the process of plant growth and development.

Elevated Expression of CCN3 in Articular Cartilage Induces Osteoarthritis in Hip Joints Irrespective of Age and Weight Bearing.

Osteoarthritis (OA) occurs not only in the knee but also in peripheral joints throughout the whole body. Previously, we have shown that the expression of cellular communication network factor 3 (CCN3), a matricellular protein, increases with age in knee articular cartilage, and the misexpression of CCN3 in cartilage induces senescence-associated secretory phenotype (SASP) factors, indicating that CCN3 promotes cartilage senescence. Here, we investigated the correlation between CCN3 expression and OA degenerative changes, principally in human femoral head cartilage. Human femoral heads obtained from patients who received total hip arthroplasty were categorized into OA and femoral neck fracture (normal) groups without significant age differences. Gene expression analysis of RNA obtained from femoral head cartilage revealed that CCN3 and MMP-13 expression in the non-weight-bearing part was significantly higher in the OA group than in the normal group, whereas the weight-bearing OA parts and normal cartilage showed no significant differences in the expression of these genes. The expression of COL10A1, however, was significantly higher in weight-bearing OA parts compared with normal weight-bearing parts, and was also higher in weight-bearing parts compared with non-weight-bearing parts in the OA group. In contrast, OA primary chondrocytes from weight-bearing parts showed higher expression of CCN3, p16, ADAMTS4, and IL-1ß than chondrocytes from the corresponding normal group, and higher ADAMTS4 and IL-1ß in the non-weight-bearing part compared with the corresponding normal group. Acan expression was significantly lower in the non-weight-bearing group in OA primary chondrocytes than in the corresponding normal chondrocytes. The expression level of CCN3 did not show significant differences between the weight-bearing part and non-weight-bearing part in both OA and normal primary chondrocytes. Immunohistochemical analysis showed accumulated CCN3 and aggrecan neoepitope staining in both the weight-bearing part and non-weight-bearing part in the OA group compared with the normal group. The CCN3 expression level in cartilage had a positive correlation with the Mankin score. X-ray analysis of cartilage-specific CCN3 overexpression mice (Tg) revealed deformation of the femoral and humeral head in the early stage, and immunohistochemical analysis showed accumulated aggrecan neoepitope staining as well as CCN3 staining and the roughening of the joint surface in Tg femoral and humeral heads. Primary chondrocytes from the Tg femoral head showed enhanced expression of Ccn3, Adamts5, p16, Il-6, and Tnfα, and decreased expression of Col2a1 and -an. These findings indicate a correlation between OA degenerative changes and the expression of CCN3, irrespective of age and mechanical loading. Furthermore, the Mankin score indicates that the expression level of Ccn3 correlates with the progression of OA.

Germ cells in the teleost fish medaka have an inherent feminizing effect.

AUTHOR SUMMARY: Germ cells are the only cells that can transfer genetic materials to the next generation via the sperm or egg. However, recent analyses in teleosts revealed another essential role of germ cells: feminizing the gonads. In our study, medaka mutants in which gametogenesis was blocked at specific stages provides the novel view that the feminizing effect of germ cells occurs in parallel with other reproductive elements, such as meiosis, the sexual fate decision of germ cells, and gametogenesis. Germ cells in medaka may have a potential to feminize gonads at the moment they have developed.

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

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

Bipolar Hip Arthroplasty Using a Conjoined Tendon-preserving Posterior Approach in Geriatric Patients.

In bipolar hemiarthroplasty (BHA), it is important to preserve soft tissue to reduce the risk of postoperative dislocation. A variety of surgical approaches for BHA are available, but extra care is needed with muscle- and tendon-preserving approaches in geriatric patients. We investigated the usefulness of BHA using a conjoined tendon-preserving posterior (CPP) approach, in which only the external obturator muscle is dissected, in geri-atric patients. We retrospectively analyzed the cases of 40 femoral neck fracture patients (10 men, 30 women) aged ≥ 80 years who underwent BHA using the CPP approach. The patients' average age was 85.8 years (80-94 years). We examined the operation time, bleeding, preservation of short external rotator muscles, complica-tions, and stem alignment and subsidence from postoperative radiographs. Although gemellus inferior muscle injury was detected in 4 patients (10%), the hip joint stability was very excellent in all cases. There was no intraoperative fracture or postoperative dislocation. On postoperative radiographs, all femoral stems were in a neutral position. There was no stem subsidence in all 40 patients. BHA using the CPP approach appeared to be useful even in geriatric patients.

The Thickness of the Medial Wall of the Acetabulum Prevents Acetabular Fracture during the Insertion of a Cementless Cup in Total Hip Arthroplasty: A Biomechanical Study.

Intra-operative acetabular fracture is a total hip arthroplasty complication that can occur during cementless cup insertion, especially in osteoporotic patients. We conducted this biomechanical study to investigate the impact resistance of the acetabulum with simulated bones of different density by drop-weight impact testing. Low- and high-density polyurethane foam blocks were used as osteoporotic and healthy bone models, respectively. Polyurethane blocks were used as the acetabular cancellous bone. Composite sheets were used as the acetabu-lum's medial cortex. The testing revealed that the osteoporotic bone model's impact resistance was significantly lower than that the healthy bone model'. In the healthy bone model, even thin acetabular cancellous bone with ≥ 1 mm acetabulum medial cortex was less likely to fracture. In the osteoporotic bone model, fracture was pos-sible without ≥ 1 mm medial cortex of the acetabulum and thick acetabular cancellous bone. Although impac-tion resistance differs due to bone quality, the impaction resistance in this osteoporotic bone model was equiv-alent to that healthy bone model's when a thick medial wall was present. To avoid intra-operative acetabulum fracture, surgeons should consider both the bone quality and the thicknesses of the medial cortex and acetabu-lar cancellous bone.

Osteosynthesis for Geriatric Acetabular Fractures: An Epidemiological and Clinico-Radiological Study Related to Marginal or Roof Impaction.

This retrospective study sought to elucidate the incidence rates of roof impaction (RI) and marginal impaction (MI) and radiological and clinical outcomes of open reduction and internal fixation (ORIF) for RI and MI in geriatric acetabular fractures. The cases of 68 patients aged ≥ 65 years (mean 71 years) treated with ORIF were analyzed. MI was present in 12 fractures (67%) and an RI of the weight-bearing surface was present in 24 (46%) of the potential fracture types. Regarding the reduction quality, 54% of the reductions were graded as anatomical, 37% as imperfect, and 9% as poor. In the clinical evaluations of the 45 patients who had > 1-year follow-up (follow-up rate: 66.2%), 18% were graded as excellent, 53% as good, 16% as fair, and 13% as poor. An anatomic reduction was strongly associated with good or excellent clinical and radiological outcomes. CT was superior to radiographs for detecting the residual displacement postoperatively. Postoperative deep infection occurred in four patients. Three patients (6.7%) underwent a total hip arthroplasty conversion due to secondary osteoarthritis of the hip. We recommend ORIF as the preferred surgical treatment option for displaced acetabular fractures in elderly patients.

Ten-Year Outcomes of Total Hip Arthroplasty Using Fit-and-Fill Type Cementless Collared Straight Stem Implants: Relationship between the Initial Contact Status and Stress Shielding.

We investigated the relationship between the initial contact status and stress shielding in total hip arthroplasty (THA) using fit-and-fill type straight-stem implants. In addition we evaluated the clinical and radiographic outcomes. Subjects were 100 hips of 94 patients who underwent THA and were followed-up for ≥10 years. Contact areas with the femoral cortical bone were investigated according to the zonal distribution of Gruen using postoperative CT images. Depending on the number of contact areas, the patients were classified into high contact [HC], medium contact [MC], and low contact [LC] groups. Radiographic and clinical outcomes were evaluated. In the HC group (20 hips), severe stress shielding was observed in 12 hips, which was statistically significant (p=0.008). In the LC group (29 hips), mild stress shielding was observed in 27 hips which was statistically significant (p<0.001). No significant differences were observed among the 3 groups in clinical outcomes, Harris hip score (p=0.719) or Japanese Orthopedic Association (JOA) score (p=0.301). In insertion of cementless collared fit-and-fill type straight-stem implants, severe late stress shielding of the femoral bone may occur if high contact of the femoral component is achieved. However, the degree of stress shielding does not result in adverse clinical outcomes.

Idiopathic Chondrolysis of the Hip Treated by Immunosuppressive Therapy and Arthroscopic Intervention.

Idiopathic chondrolysis of the hip (ICH), a very rare disorder of unknown etiology, occurs mainly in female adolescents. Characterized by pain, limp, stiffness and radiological narrowing joint space from the rapid destruction of the articular cartilage, ICH sometimes results in ankyloses. We present the case of a 10-year-old girl diagnosed with ICH based on arthroscopic inspection and synovium biopsy. The femoral deformity appeared gradually, like a cam-type femoroacetabular impingement. She was treated with intensive rehabilitation and immunosuppressive drug. We later performed an arthroscopic bumpectomy for residual symptoms. She achieved a favorable outcome as a 15-year-old at the latest follow-up.

Effects of transcutaneous electrical nerve stimulation and visuotactile synchrony on the embodiment of an artificial hand.

The rubber hand illusion (RHI) is an experimental paradigm known to produce a bodily illusion. Transcutaneous electrical nerve stimulation (TENS) combined with the RHI induces a stronger illusion than the RHI alone. Visuotactile stimulus synchrony is an important aspect of the RHI. However, the effect of TENS and visuotactile stimulus synchrony in TENS combined with the RHI remains unknown. The purpose of this study was to investigate the effects of TENS and visuotactile stimulus synchrony on the embodiment of an artificial hand when using TENS combined with the RHI. The participants underwent four experimental conditions in random order: TENS/noTENS × Synchronous/Asynchronous. TENS was set at an intensity such that it generated a feeling of electrical paresthesia in the radial nerve area of the hand but did not cause pain, i.e., 100-Hz pulse frequency, 80-µs pulse duration, and a constant pulse pattern. A visuotactile stimulus, either temporally synchronous or asynchronous, was generated using paintbrush strokes. To evaluate the outcome measures, the participants completed a questionnaire report and proprioceptive drift assessments (motor response and perceptual response). There were significant main effects of TENS and visuotactile synchrony, but no interaction between these factors, on the results of the questionnaire and the perceptual response. In contrast, there was no significant effect on the result of the motor response. These findings indicate that TENS and visuotactile synchrony might affect differently the embodiment of an artificial hand when using TENS combined with the RHI.

Avulsion fracture of the ischial tuberosity treated with the suture bridge technique: a case report.

BACKGROUND: In cases of avulsion fracture of the ischial tuberosity in which the bone fragments are substantially displaced, nonunion may cause pain in the ischial area. Various surgical procedures have been reported, but achieving sufficient fixation strength is difficult. CASE PRESENTATION: We treated a 12-year-old male track-and-field athlete with avulsion fracture of the ischial tuberosity by suture anchor fixation using the suture bridge technique. The boy felt pain in the left gluteal area while running. Radiography showed a left avulsion fracture of the ischial tuberosity with approximately 20-mm displacement. Union was not achieved by conservative non-weight-bearing therapy, and muscle weakness persisted; therefore, surgery was performed. A subgluteal approach was taken via a longitudinal incision in the buttocks, and the avulsed fragment was fixed with five biodegradable suture anchors using the suture bridge technique. CONCLUSIONS: Although the majority of avulsion fractures of the ischial tuberosity can be treated conservatively, patients with excessive displacement require surgical treatment. The suture bridge technique provided secure fixation and enabled an early return to sports activities.

Predicting acetabular growth in developmental dysplasia of the hip following open reduction after walking age.

BACKGROUND: Acetabular dysplasia of the hip following open reduction can complicate the treatment of developmental dysplasia of the hip (DDH). The purposes of this retrospective study were to investigate the long-term results of open reduction performed via an extensive anterolateral approach for DDH after walking age and to predict acetabular development using postoperative radiographs and arthrograms. METHODS: From 1973 to 2001, we performed open reduction for 131 hips in 119 pediatric patients with DDH after failed closed reduction. Of these, 85 hips of 73 patients who underwent arthrography at 5 years old were followed-up radiologically until skeletal maturity. Mean age at the time of surgery was 17 ± 4.6 months (range, 10-33 months), and mean age at final survey was 19 ± 5.7 years (range, 14-33 years). Mean follow-up time was 17.7 ± 5.8 years (range, 13-32 years). Groups with satisfactory outcomes (66 hips) and unsatisfactory outcomes (19 hips) according to the Severin classification were compared. Factors predicting acetabular development were identified using univariate and multiple logistic analyses. RESULTS: Univariate analysis showed a significant between-group difference in acetabular index (AI) at 2 months postoperatively, and in center-edge (CE) angle, cartilaginous AI (CAI), and cartilaginous CE angle at 5 years old (p < 0.05 each). In multiple logistic regression analysis, CAI at 5 years old represented a predictor of acetabular development after open reduction for DDH (odds ratio, 1.81; 95% confidence interval (CI), 1.04-3.13; p < 0.05). Area under the receiver operating characteristic curve for CAI at 5 years old was 0.93 (95%CI, 0.85-1.0), and the optimal cut-off was 10° (81.8% sensitivity, 92% specificity). CONCLUSIONS: A CAI ≥10° on hip arthrograms at 5 years old may offer a useful indicator of the need for corrective surgery following open reduction after walking age.

Enhancement of natural killer activity and IFN-γ production in an IL-12-dependent manner by a Brassica rapa L.

Certain food components possess immunomodulatory effects. The aim of this study was to elucidate the mechanism of the immunostimulatory activity of Brassica rapa L. We demonstrated an enhancement of natural killer (NK) activity and interferon (IFN)-γ production in mice that were orally administered an insoluble fraction of B. rapa L. The insoluble fraction of B. rapa L. significantly induced IFN-γ production in mouse spleen cells in an interleukin (IL)-12-dependent manner, and NK1.1+ cells were the main cells responsible for producing IFN-γ. Additionally, the results suggested that the active compounds in the insoluble fraction were recognized by Toll-like receptor (TLR) 2, TLR4, and C-type lectin receptors on dendritic cells, and they activated signaling cascades such as MAPK, NF-κB, and Syk. These findings suggest that B. rapa L. is a potentially promising immuno-improving material, and it might be useful for preventing immunological disorders such as infections and cancers by activating innate immunity.

Accuracy of Cup Positioning With the Computed Tomography-Based Two-dimensional to Three-Dimensional Matched Navigation System: A Prospective, Randomized Controlled Study.

BACKGROUND: The accuracy of various navigation systems used for total hip arthroplasty has been described, but no publications reported the accuracy of cup orientation in computed tomography (CT)-based 2D-3D (two-dimensional to three-dimensional) matched navigation. METHODS: In a prospective, randomized controlled study, 80 hips including 44 with developmental dysplasia of the hips were divided into a CT-based 2D-3D matched navigation group (2D-3D group) and a paired-point matched navigation group (PPM group). The accuracy of cup orientation (absolute difference between the intraoperative record and the postoperative measurement) was compared between groups. Additionally, multiple logistic regression analysis was performed to evaluate patient factors affecting the accuracy of cup orientation in each navigation. RESULTS: The accuracy of cup inclination was 2.5° ± 2.2° in the 2D-3D group and 4.6° ± 3.3° in the PPM group (P = .0016). The accuracy of cup anteversion was 2.3° ± 1.7° in the 2D-3D group and 4.4° ± 3.3° in the PPM group (P = .0009). In the PPM group, the presence of roof osteophytes decreased the accuracy of cup inclination (odds ratio 8.27, P = .0140) and the absolute value of pelvic tilt had a negative influence on the accuracy of cup anteversion (odds ratio 1.27, P = .0222). In the 2D-3D group, patient factors had no effect on the accuracy of cup orientation. CONCLUSION: The accuracy of cup positioning in CT-based 2D-3D matched navigation was better than in paired-point matched navigation, and was not affected by patient factors. It is a useful system for even severely deformed pelvises such as developmental dysplasia of the hips.