Introduction: Unidirectional porous β-tricalcium phosphate (UDPTCP) consists of a novel porous artificial bone that is structurally different from conventional artificial bone comprised of spherical porous β-tricalcium phosphate (SPTCP).Case presentation: We present our first four clinical cases of opening-wedge high tibial osteotomy (OWHTO) using UDPTCP and SPTCP together. The patients’ mean age was 54.5 ± 5.9 years, and the mean observation period was 20.8 ± 2.8 months. In OWHTO, two wedge shaped pieces of UDPTCP and SPTCP were cut to fit the gap and implanted parallel to each other in the anterior and posterior parts, respectively. We evaluated the correction loss and bone remodeling for UDPTCP and SPTCP over time using radiography and computed tomography, and evaluated the clinical outcomes.Conclusion: There was no correction loss reported in any case, and early bone remodeling was observed with UDPTCP. All patients achieved satisfactory clinical results with no adverse events.

Objective: This study aimed to examine differences in platelet-rich plasma (PRP) soak-loaded volumes of β-tricalcium phosphate (β-TCP) with or without a unidirectional porous structure.Materials and Methods: Leukocyte-rich PRP was extracted from 15 healthy volunteers by centrifugation. Two types of artificial bones were soaked for either ten seconds or ten minutes. The volume ratios of PRP soak-loaded onto the artificial bone and soaked area ratios were evaluated. Statistical analyses were performed using the Tukey-Kramer HSD test and the Games-Howell method. A P-value of <0.05 was considered statistically significant.Results: Regardless of the soaking time, the PRP soak-loaded volume ratio and soaked area ratio were significantly higher in the unidirectional porous β-TCP (UDPTCP) group than in the spherical porous β-TCP (SPTCP) group.Conclusion: PRP can be soak-loaded faster and in larger amounts onto UDPTCP compared to SPTCP. Understanding the basic biology of β-TCP soak-loaded with PRP can help develop more novel and effective β-TCP treatments for orthopedic surgery.

Objectives: To evaluate the feasibility and efficacy of treatment for the recovery of knee joint function after total knee arthroplasty (TKA) using a robotic suit.Patients and Methods: Knee joint extension exercise sessions were started with a robotic suit (single-joint hybrid assistive limb [HAL-SJ, Cyberdyne, Inc., Tsukuba, Japan]) in one group of patients after TKA. Patients who underwent standard rehabilitation were enrolled in the control group. To evaluate feasibility and safety, we assessed the adverse events, the number of training sessions, and training time. We compared the changes in knee joint pain and extension lag (°) between the groups.Results: The average age was 71.3 ± 6.2 years in the HAL-SJ group and 74.9 ± 8.7 years in the control group. There were no severe adverse events. In the HAL-SJ group, training was performed 2.9 times, on average, and lasted 18.8 min. In the HAL-SJ group, there was a reduction in the visual analog scale (VAS) for pain after training, which was not significant. In the control group, the VAS score worsened after the sessions. The extension lag significantly improved in the HAL-SJ group after the 2nd and 3rd sessions, and this was more due to improvements in their active extension range of motion than their passive extension range of motion.Conclusions: HAL-SJ-based training is safe and effective, and leads to instantaneous improvement of extension lag, without worsening knee joint pain. HAL-SJ-based knee extension training could represent a viable novel post-TKA rehabilitation modality.

Objective: To compare the outcomes of steroid-associated osteonecrosis of the femoral head in patients with systemic lupus erythematosus who underwent conservative treatment and concentrated autologous bone marrow aspirate transplantationMethods: Osteonecrosis of the femoral head was classified according to the Japanese Investigation Committee system. Concentrated autologous bone marrow aspirate transplantation was performed by aspirating the bone marrow from both iliac crests and then transplanting it to the necrotic area after the core decompression. Patients with >2-year follow-up after the concentrated autologous bone marrow aspirate transplantation in our institution (Group I) and those with >2-year follow-up after the first hospital visit in a cooperative institution (Group II) were included in this study. After a randomized matching based on age, sex, type, stage, and etiology, the collapse rate in pre-collapsed stages and total hip arthroplasty conversion rate in all stages were compared between the two groups.Results: After the matching adjustment, 33 pairs of hips were included. Preoperatively, 1, 2, 16, and 14 hips were classified as types A, B, C1, and C2, respectively, and 15, 13, 2, and 3 hips were classified as stages 1, 2, 3A, and 3B, respectively. The collapse rates in the pre-collapsed stages were 68% and 39% in Groups I and II, respectively. Total hip arthroplasty conversion rates were 33% and 45% in Groups I and II, respectively. However, Group I had significantly higher and lower conversion rates in stages 1 and 3, respectively (both P<0.05).Conclusion: Conservative treatment may be preferable in stage 1 hips. In addition, concentrated autologous bone marrow aspirate transplantation may prevent further collapse in stage 3.