Faculty Profiles - TAKEGAMI Yasuhiko

Same survival but higher rate of osteolysis for metal-on-metal, ultamet versus ceramic-on-ceramic in patients undergoing primary total hip arthroplasty after 8 years of follow-up

Higuchi Y.

Revue de Chirurgie Orthopedique et Traumatologique Vol. 104 ( 8 ) 2018.12

Comparison of cementless total hip arthroplasty survivorship between metal-on-highly cross-linked polyethylene and ceramic on ceramic bearings: A case control study with a 5-9-year follow-up. Reviewed

Higuchi Y, Seki T, Hasegawa Y, Morita D, Komatsu D, Takegami Y, Ishiguro N

Orthopaedics & traumatology, surgery & research : OTSR Vol. 104 ( 5 ) page： 663 - 669 2018.9

Wnt/Beta-catenin Signaling as one of the Therapeutic Targets in Osteoarthritis Invited Reviewed

竹上靖彦

Nov Tech Arthritis Bone Res Vol. 2 page： 1 - 3 2018

A simple linear alternative to necrotic volume for predicting collapse in osteonecrosis of the femoral head Reviewed International journal

Keiji Otaka, Yusuke Osawa, Yasuhiko Takegami, Hiroto Funahashi, Hiroaki Ido, Takamune Asamoto, Shinya Tanaka, Shiro Imagama

Skeletal Radiology Vol. 55 ( 3 ) page： 515 - 523 2026.3

Language：English Publishing type：Research paper (scientific journal)

OBJECTIVE: The clinical use of magnetic resonance imaging-based volumetric measurement for osteonecrosis of the femoral head (ONFH) is restricted by its complexity. This study aimed to identify a practical computed tomography-based imaging parameter as a reliable alternative to necrotic volume and to evaluate its ability to predict femoral head collapse. MATERIALS AND METHODS: This retrospective study included 125 hips from 90 patients with ONFH and initial collapse of < 3 mm. Four-dimensional ratios were examined for their association with necrotic volume using generalized estimating equation models. The parameter showing the strongest association was determined by comparing models with the Quasi-likelihood Information Criterion (QIC). Receiver operating characteristic curve analysis was then used to establish a cutoff value for predicting a necrotic volume of ≥ 30%, the threshold defined as severe in the Steinberg classification. This prognostic value of this cutoff for collapse (> 3 mm) was tested with a robust Cox proportional hazards model. RESULTS: The coronal vertical diameter ratio (CVDR) showed the strongest association with necrotic volume, yielding the lowest QIC. A CVDR cutoff of 51% predicted a large necrotic volume (AUC 0.931). Hips with a CVDR ≥ 51% had a significantly higher risk of collapse compared with those with a CVDR < 51% (HR, 6.07; 95% CI, 3.25-11.34; P < 0.001). This predictive value was consistent across all Japanese Investigation Committee type subgroups. CONCLUSION: The CVDR represents a simple and reliable alternative to volumetric assessment. A cutoff of approximately 51% provides clinically useful risk stratification, and incorporating lesion location may further enhance predictive accuracy.

DOI： 10.1007/s00256-025-05056-4

Minimum 10-Year Outcomes of Total Hip Arthroplasty After Periacetabular Osteotomy. Reviewed International journal

Hiroshi Asai, Yusuke Osawa, Yasuhiko Takegami, Hiroto Funahashi, Shiro Imagama

The Journal of arthroplasty Vol. 41 ( 3 ) page： 639 - 645 2026.3

Language：English Publishing type：Research paper (scientific journal)

BACKGROUND: Although total hip arthroplasty (THA) post-periacetabular osteotomy (PAO) has yielded excellent short-term and mid-term outcomes, long-term implant survivorship remains unclear. This study aimed to evaluate the long-term (minimum 10 year) outcomes of THA post-PAO and assist in determining surgical indications and planning for THA post-PAO. METHODS: This study included 50 hips that underwent THA post-PAO, with a minimum follow-up of 10 years. Propensity score-matching based on age, sex, and Crowe type was used to establish the PAO and control groups. The mean age at the time of THA for the PAO and control groups was 56 (95.7% women) and 56 (91.7% women) years, respectively. There were 11 hips (22%) diagnosed with developmental dysplasia of the hip during childhood and treated conservatively. Key parameters assessed included the Harris Hip Score, complications, horizontal and vertical distances between the teardrop and femoral head center, radiolucent lines (RLLs), and loosening on radiographs. Subgroup analysis was performed to compare outcomes between the elevated and anatomical groups. RESULTS: At the latest follow-up, the PAO group exhibited significantly lower Harris Hip Score than the control group (86.7 ± 9.4 versus 90.3 ± 5.7; P = 0.021). Radiographic analysis revealed RLLs in four (8.0%) and three (6.0%) cases in the PAO and control groups, respectively, without significant differences. Loosening cases were not observed in either group. Acetabular cups were located more superiorly in the PAO group than in the control group (26.1 ± 7.3 versus 22.8 ± 6.4; P = 0.020). Subgroup analysis indicated no significant difference in RLLs between the elevated and anatomical groups (5.5 versus 9.4%; P = 0.62). CONCLUSIONS: Although the functional outcomes of THA post-PAO were inferior to those of primary THA, implant survivorship was comparable between the two groups. In cases with large preoperative bone defects, the acetabular component was placed more superiorly in the PAO group, which did not appear to affect long-term (10 year) implant survivorship.

DOI： 10.1016/j.arth.2025.07.063

Ipsilateral Lower-Limb Alignment after Total Hip Arthroplasty for Dysplastic Hip Osteoarthritis. Reviewed International journal

Shinya Tanaka, Yusuke Osawa, Yasuhiko Takegami, Hiroto Funahashi, Shiro Imagama

The Journal of arthroplasty Vol. 41 ( 3 ) page： 797 - 804 2026.3

Language：English Publishing type：Research paper (scientific journal)

BACKGROUND: Total hip arthroplasty (THA) is an effective treatment for dysplastic hip osteoarthritis (DHOA); however, factors associated with lower limb alignment changes after THA remain unclear. This study investigated factors associated with these changes in patients undergoing THA for DHOA. METHODS: We analyzed 121 patients undergoing THA for unilateral DHOA between 2018 and 2022. Based on the hip-knee-ankle angle (HKAA) changes, patients were divided into neutral (HKAA change <3°), varus (HKAA change ≥3° varus), and valgus (HKAA change ≥3° valgus) change groups. We compared their backgrounds, pelvic and femoral morphology, spinal alignment, and functional outcomes. RESULTS: The neutral, varus, and valgus groups included 88, 18, and 15 patients, with mean ages of 64 ± 9.9, 60 ± 7.5, and 69 ± 7.6 years, respectively. Patients in the valgus group were significantly older than those in the neutral group (P = 0.018). Preoperative femoral offset was significantly smaller in the varus group (neutral, 29.6 ± 6.3; varus, 23.9 ± 6.1; valgus, 30.7 ± 4.3 mm; P < 0.001). The ΔFemoral length was significantly larger in the valgus group (neutral, 8.1 ± 6.9; varus, 6.3 ± 7.1; valgus, 13.1 ± 6.9 mm; P = 0.014). The ΔFemoral offset was significantly larger in the varus group (neutral, 4.1 ± 5.4; varus, 10.2 ± 5.6; valgus, 1.9 ± 4.0 mm; P < 0.001). Multivariate analysis found that ΔFemoral offset is associated with varus change (odds ratio [OR], 1.25; P = 0.005). Age (OR, 1.10; P = 0.037), ΔFemoral length (OR, 1.15; P = 0.005), and ΔFemoral offset (OR, 0.84; P = 0.043) were associated with valgus change. CONCLUSIONS: In unilateral DHOA, an increase in femoral offset was associated with varus changes in lower limb alignment after THA. Conversely, valgus changes were associated with older age, reduced femoral offset, and increased femoral length.

DOI： 10.1016/j.arth.2025.07.068

Functional outcomes and survival rates of patients with fragility fractures of the pelvis: A multicenter retrospective analysis of 588 patients

Yasuhiko Takegami, Yusuke Osawa, Hiroto Funahashi, Hiroaki Ido, Takamune Asamoto, Shinya Tanaka, Keiji Otaka, Shiro Imagama

Journal of Orthopaedic Science 2026.1

Risk factors for delayed pubic union after eccentric rotational acetabular osteotomy. Reviewed International journal

Shinya Tanaka, Yusuke Osawa, Yasuhiko Takegami, Hiroto Funahashi, Hiroaki Ido, Takamune Asamoto, Shiro Imagama

International orthopaedics Vol. 50 ( 1 ) page： 57 - 65 2026.1

Language：English Publishing type：Research paper (scientific journal)

PURPOSE: Eccentric rotational acetabular osteotomy (ERAO) is an effective treatment for acetabular dysplasia, but delayed union of the superior pubic ramus is a concern. This study identified risk factors for delayed pubic union post-ERAO and evaluated its clinical impact. METHODS: This retrospective study included 101 patients who underwent ERAO during 2014-2022, grouped according to one year pubic union status: union (n = 78) and delayed union (n = 23). We compared demographics, pre-and postoperative radiographic parameters (including lateral, anterior, and posterior centre-edge angles; acetabular sector angles; acetabular anteversion; pubic osteotomy site; and femoral head centre lateralisation), and clinical outcomes. RESULTS: Multivariate logistic regression identified older age (odds ratio [OR], 1.07; 95% CI, 1.00-1.13), a more medial pubic osteotomy site relative to the iliopectineal eminence (OR, 1.28; 95% CI, 1.10-1.49), and insufficient femoral head centre medialisation (OR, 1.40; 95% CI 1.12-1.74) as independent risk factors for delayed union. The pubic osteotomy site cutoff was 12.0 mm medial to the iliopectineal eminence (AUC 0.759). The delayed union group exhibited significantly higher rates of inferior pubic ramus stress fractures (17.4% vs. 1.3%, p = 0.009), although two year JOA scores were similar between groups. CONCLUSION: Older age, pubic osteotomy more medial to the iliopectineal eminence, and insufficient femoral head medialisation are key risk factors for delayed pubic union after ERAO. While these factors did not directly affect hip function at two years postoperatively, they significantly increased the risk of inferior pubic ramus stress fractures. Therefore, accurate pubic osteotomy and careful avoidance of femoral head lateralisation are essential.

DOI： 10.1007/s00264-025-06676-0

Femoral Morphology and Range of Motion After Eccentric Rotational Acetabular Osteotomy in Males with Hip Dysplasia. Reviewed International journal

Hiroto Funahashi, Yusuke Osawa, Yasuhiko Takegami, Hiroaki Ido, Takamune Asamoto, Shiro Imagama

Orthopaedics & traumatology, surgery & research : OTSR page： 104568 - 104568 2025.12

Language：English Publishing type：Research paper (scientific journal)

BACKGROUND: Eccentric rotational acetabular osteotomy (ERAO) enhances acetabular coverage and optimizes joint contact pressure in patients with hip dysplasia (HD); however, postoperative range of motion (ROM) may be restricted due to bony impingement. The impact of this procedure on anterior ROM in males remains unknown. ROM depends on both acetabular morphology and femoral neck anteversion (FNA); hence, this study aimed to address the following questions: (1)Does sex affect the achievement of functional ROM (flexion ≥105 ° and internal rotation ≥20 ° at 90 ° flexion) after virtual ERAO standardized to lateral center-edge angle (LCEA) 30 ° and anterior center-edge angle (ACEA) 55°? (2)Is FNA lower in males compared to females with hip dysplasia? (3)Does FNA correlate with post-ERAO ROM in males with hip dysplasia? (4)What is the threshold value of FNA below which males are at risk of inadequate ROM after ERAO? HYPOTHESIS: We hypothesized that males, who generally exhibit lower FNA, would demonstrate reduced anterior hip ROM even after ERAO despite achieving comparable acetabular coverage. PATIENTS AND METHODS: A total of 24 male and 98 female hips with HD treated between 2016 and 2018 were analyzed. Virtual ERAO was performed on preoperative CT models, targeting an LCEA of 30 ° and an ACEA of 55 °. Postoperative acetabular coverage, FNA, and neck-shaft angle (NSA) were measured. ROM simulations were used to quantify the maximum flexion and internal rotation at 90 ° flexion. Sex-related differences and correlations were assessed, and receiver operating characteristic (ROC) analysis was performed to determine the FNA threshold for failure to achieve functional ROM. ROM estimation was based on CT-derived bony contact; soft tissue constraints were not modeled. RESULTS: After standardized virtual ERAO, males demonstrated higher failure rates in achieving functional ROM than females, with flexion <105 ° observed in 8 of 24 hips (33.3%) compared with 11 of 98 hips (11.2%) (p = 0.012), and internal rotation <20 ° in 8 of 24 hips (33.3%) compared with 13 of 98 hips (13.6%). Postoperative acetabular coverage and NSA did not differ significantly between sexes, whereas FNA was significantly lower in males (13.7 ± 14.0 °) than in females (21.5 ± 13.1 °). FNA correlated with flexion (r = 0.69) and internal rotation (r = 0.52). An FNA of ≤0.0 ° was predictive of failure to achieve functional ROM, with an AUC of 0.78, a sensitivity of 0.57, and a specificity of 0.94. DISCUSSION: Low FNA, which was more prevalent in males with hip dysplasia, was associated with reduced anterior ROM following virtual ERAO, and males also exhibited higher failure rates in achieving functional ROM. These findings suggest that femoral morphology-particularly FNA-should be considered during ERAO planning in male patients. However, given the limited sensitivity of the FNA ≤0 ° threshold and the exploratory nature of this virtual simulation analysis, these results should be regarded as hypothesis generating and validated in clinical ERAO cohorts before clinical application. LEVEL OF EVIDENCE: III; case-control study.

DOI： 10.1016/j.otsr.2025.104568