Association of physical activity with fatty infiltration of muscles after total hip arthroplasty.

OBJECTIVE: This study aimed to investigate the association between muscle density as an indicator of fatty infiltration of lower extremity muscles and physical activity (PA) after total hip arthroplasty (THA) and identify the patient characteristics with high postoperative PA. METHODS: This study included 62 female patients who underwent THA for unilateral hip osteoarthritis. Muscle density of the gluteus maximus, gluteus medius, iliopsoas, and quadriceps muscles was measured using computed tomography (CT). PA was assessed using University of California, Los Angeles (UCLA) activity scores. CT and UCLA activity score were obtained before and 1 year after THA. The patients were divided into two groups, sufficient (score ≥ 6) and insufficient (score < 6) activity groups, based on their level of PA as determined by their UCLA activity score 1 year after THA. The association of PA with the amount of changes in muscle density was examined with Spearman's rank correlation coefficient. Logistic regression analysis was performed to identify postoperative factors determining PA at 1 year after THA. RESULTS: Spearman's rank correlation coefficient showed a significantly positive association between recovery in PA and an increase in muscle density of the gluteus maximus, gluteus medius, iliopsoas, and quadriceps muscles. Additionally, logistic regression analysis confirmed that postoperative muscle densities of the gluteus maximus and quadriceps muscles were variables determining the PA 1 year after THA. CONCLUSION: The findings of this study indicated that the improvement of fatty infiltration in lower limb muscles, especially in the gluteus maximus and quadriceps, is likely to promote the increase in postoperative PA.

Measurement of the Acetabular Cup Orientation after Total Hip Arthroplasty Based on Three-Dimensional Reconstruction from a Single X-ray Image Using Generative Adversarial Networks.

BACKGROUND: The purpose of this study was to reconstruct three-dimensional (3D) computed tomography (CT) images from single anteroposterior (AP) postoperative total hip arthroplasty (THA) X-ray images using a deep learning algorithm known as generative adversarial networks (GANs) and to validate the accuracy of cup angle measurement on GAN-generated CT. METHODS: We used two GAN-based models, CycleGAN and X2CT-GAN, to generate 3D CT images from X-ray images of 386 patients who underwent primary THAs using a cementless cup. The training dataset consisted of 522 CT images and 2,282 X-ray images. The image quality was validated using the peak signal-to-noise ratio (PSNR) and the structural similarity index measure (SSIM). The cup anteversion and inclination measurements on the GAN-generated CT images were compared with the actual CT measurements. Statistical analyses of absolute measurement errors were performed using Mann-Whitney U tests and nonlinear regression analyses. RESULTS: The study successfully achieved 3D reconstruction from single AP postoperative THA X-ray images using GANs, exhibiting excellent PSNR (37.40) and SSIM (0.74). The median absolute difference in radiographic anteversion (RA) was 3.45° and the median absolute difference in radiographic inclination (RI) was 3.25°, respectively. Absolute measurement errors tended to be larger in cases with cup malposition than in those with optimal cup orientation. CONCLUSION: This study demonstrates the potential of GANs for 3D reconstruction from single AP postoperative THA X-ray images to evaluate cup orientation. Further investigation and refinement of this model are required to improve its performance.

What are the differences in the recovery of physical function and clinical score between patients with steroid-related osteonecrosis of the femoral head and hip osteoarthritis undergoing total hip arthroplasty? A propensity score-matched study.

PURPOSE: Steroid-related osteonecrosis of the femoral head (ONFH), arising from steroid administration for underlying diseases, represents a unique pathology for total hip arthroplasty (THA) and typically affects a younger demographic compared to osteoarthritis (OA). Given the significant age-related differences, this study aims to employ propensity score matching to align patient backgrounds between these two diseases and compare physical function. Additionally, our objective is to scrutinize the patterns of clinical score recovery over the course of one year following THA. METHODS: Using propensity score matching, 29 patients each with steroid-related ONFH and OA were selected. Muscle strength (hip abductor and knee extensor) were assessed before and after THA. Additionally, recovery of the Harris Hip Score (HHS) and Oxford Hip Score (OHS) up to one year postoperatively was analyzed. RESULTS: The steroid-related ONFH group exhibited gender bias and significantly younger age compared to the OA group. Propensity score matching achieved balanced patient backgrounds. Physical function showed trends of lower hip abduction and knee extensor strength on the operative side in the steroid-related ONFH group. Notably, nonoperative knee extensor strength decreased significantly after matching. HHS and OHS were poor in steroid-related ONFH up to three months postoperatively but recovered after six months. CONCLUSIONS: Patients with steroid-related ONFH experience positive outcomes in clinical score following THA. Propensity score matching effectively identified muscle weakness on both operative and nonoperative sides, highlighting its utility in comparative analyses.

Investigating sagittal spinopelvic alignment and equivalent stress on the femoral head in patients with rapidly destructive coxarthrosis.

PURPOSE: Rapidly destructive coxarthrosis (RDC) is a rare syndrome of unknown etiology. This study evaluated sagittal spinopelvic alignment (SSPA) in patients with RDC and compared it with that in patients with hip osteoarthritis (HOA). In addition, finite element analysis (FEA) was performed to investigate the distribution of stress on the femoral head in RDC versus HOA. METHODS: This retrospective study included patients who had undergone primary total hip arthroplasty for RDC (n = 33) and HOA (n = 99; age- and sex-matched to patients with RDC) at three hospitals from June 2014 to September 2020. Preoperative SSPA parameters and inflammatory blood markers were compared between the two groups. FEA on the computed tomography data was performed for four patients from each group with similar pelvic tilt (PT) and lateral center-edge angle (LCEA). The distribution of Drucker-Prager equivalent stress was assessed at the loaded area of the femoral head. RESULTS: Patients with RDC had significantly higher PT, lower sacral slope, decreased lumbar lordosis (LL), higher sagittal vertical axis, and higher pelvic incidence minus LL than patients with HOA, indicating sagittal spinal imbalance. Blood test revealed patients with RDC had higher levels of inflammation markers than patients with HOA. FEA revealed no statistically significant difference in the degree of stress concentration or the maximum equivalent stress between the two groups when PT and LCEA were comparable. CONCLUSION: Patients with RDC tend to have sagittally imbalanced spine. Decreased acetabular coverage of the femoral head may heighten mechanical load of the hip joint in patients with RDC.

Assessment of the Damage to Hip Abductor Muscles in Primary Total Hip Arthroplasty With a Minimally Invasive Anterolateral Approach With or Without Trochanteric Flip Osteotomy.

BACKGROUND: Although introduction of minimally invasive techniques via anterolateral approaches considerably decreased prolonged limp after total hip arthroplasty (THA), potential damage to the abductor muscles is still a concern. This study aimed to evaluate the residual damage after primary THA with two types of anterolateral approach by assessing fatty infiltration and atrophy of the gluteus medius (GMed) and gluteus minimus (GMin) muscles. METHODS: We retrospectively analyzed 100 primary THAs using computed tomography; surgeries were performed by detaching the anterior part of the abductor muscles with a bone fragment (anterolateral approach with trochanteric flip osteotomy) or without it (anterolateral approach without trochanteric flip osteotomy). The change in radiodensities (RDs), cross-sectional areas (CSAs), and clinical scores preoperatively and at 1 year after operation were evaluated. RESULTS: The RD and CSA of GMed increased 1 year postoperatively in 86 and 81% of patients, respectively, while RD and CSA of GMin decreased in 71 and 94%, respectively. The improvement of RD of GMed was more frequently seen in the posterior rather than the anterior part, while the GMin decreased in both parts. The RD decrease of GMin was significantly lower in the anterolateral approach with trochanteric flip osteotomy group than the anterolateral approach without trochanteric flip osteotomy group (P = .0250). However, there was no difference in the clinical scores between the two groups. The change in the RD of GMed was the only factor that correlated with clinical scores. CONCLUSION: The two anterolateral approaches both improved the RD of GMed, recovery of which was significantly associated with postoperative clinical scores. Although the two approaches showed different recovery patterns in GMin until 1 year after THA, both showed similar improvements in clinical scores.

Long-term outcome of primary total hip arthroplasty with cementless bioactive glass ceramic bottom-coated implants and highly cross-linked polyethylene: A minimum 10-year analysis.

BACKGROUND: Cementless glass ceramics containing apatite and wollastonite (AW-GC) bottom-coated titanium hip implants were developed; early excellent clinical and radiographic results have been reported previously. This study aimed to investigate the long-term clinical and radiographic outcomes in detail, and the wear rate of HXLPE. METHODS: We retrospectively evaluated 99 patients (117 hips) between November 2001 and December 2007. The survival rate was estimated using the Kaplan-Meier method. Hip joint function was evaluated using the Japanese Orthopaedic Association (JOA) score. The extent of radiographic signs was determined from the radiographs performed at the last follow-up. Polyethylene wear was measured using Martell's Hip Analysis Suite. We assessed the possible factors affecting the steady-state linear wear rate. RESULTS: The mean follow-up period was 14.8 ± 2.1 (10-18.6) years. The mean JOA score improved to 88.7 ± 9.4 (59-100) at the final follow-up from 47.8 ± 12.5 (17-76) before surgery. The overall survival rate with the end point of all-cause revision and wear-related revision was 99% and 100% respectively. There was no osteolysis or loosening of either the acetabular or femoral component. All hips were classified as having bone ingrowth fixation. The mean steady-state wear rate was 0.008 ± 0.025 mm/year. We found no significant correlation between the wear rate and age, body weight, body mass index, cup inclination and femoral head size. CONCLUSION: The combination of AW-GC bottom-coated implants and HXLPE showed excellent implant survival and wear resistance for 15 years.

Preoperative Factors Associated With Low Back Pain Improvement After Total Hip Arthroplasty in a Japanese Population.

BACKGROUND: Spinal disorders and low back pain (LBP) have been associated with worse clinical outcomes of total hip arthroplasty (THA). It is essential to identify spinal factors associated with post-THA LBP improvement. Therefore, we aimed to determine the proportion of patients with improved LBP after THA and to identify the preoperative spinal factors associated with LBP improvement. METHODS: We included 151 patients who underwent primary THA between December 2015 and December 2019 and had a preoperative visual analog scale score for LBP of ≥2. The patients were classified into the LBP improved or LBP continued group based on a visual analog scale score for LBP at 1 year after THA. Preoperative spinal parameters were compared between the 2 groups. RESULTS: Ninety-five patients (62.9%) were classified into the LBP improved group. Among the coronal spinal parameters, the Cobb angle was significantly lower in the LBP improved group. Among the sagittal spinal parameters, the LBP continued group showed a significantly more posteriorly titled pelvis, lower lumbar lordosis, greater sagittal vertical axis, and greater pelvic incidence minus lumbar lordosis mismatch, indicating a sagittal spinal imbalance. Logistic regression analysis found that preoperative factors associated with LBP improvement after THA had a low Cobb angle and high anterior pelvic plane angle (anteriorly tilted pelvis). CONCLUSION: Among patients with LBP before THA, 62.9% had improved LBP. Sagittal spinal imbalance and high Cobb angle were the key spinal factors associated with persistent LBP. Our findings suggest that hip surgeons should evaluate spinal alignment before THA in patients with LBP.

Corticosteroid-associated osteonecrosis of the femoral head after orthotopic liver transplantation and the outcomes of subsequent total hip arthroplasty.

BACKGROUND: Corticosteroids are essential for immunosuppression after orthotopic liver transplantation (OLT), but also have many side effects. Osteonecrosis of the femoral head (ONFH) is one of the most serious complications requiring prostheses. However, few studies have investigated ONFH after OLT. The purpose of this study is to survey the incidence of corticosteroid-induced ONFH after OLT and the outcomes of total hip arthroplasty (THA). METHODS: Between January 2001 and December 2010, a series of 926 patients underwent OLT at our Hospital. A retrospective analysis was performed on a total of 738 patients who survived at least 2 years after OLT. The incidence of symptomatic ONFH, the interval from OLT to the initial diagnosis of ONFH, and the cumulative dose of corticosteroids were analyzed. The side effects related to OLT, such as other osteonecrosis lesions, osteoporotic fractures, and infection, were monitored. For patients who underwent THA, radiological findings and Japanese Orthopaedic Association (JOA) scores were evaluated. RESULTS: ONFH occurred in 10 patients (13 hips) (6 men [7 hips], 4 women [6 hips]), with an incidence of 1.36%. The average age at OLT was 51.4 years (range, 31-61 years). The average interval from OLT to ONFH was 86.7 months (range, 22-155 months). The average cumulative dose of corticosteroids was 7274 mg (range, 1342-29,514 mg). Twenty patients suffered from side effects related to OLT. Seven patients (8 hips) underwent THA. No adverse events including infection arose during the perioperative process. One hip dislocated, and one femoral stem displayed a radiolucent line. The average JOA score improved from 45.4 (range, 25-76) preoperatively to 86.9 (range, 73-99) at final follow-up. No patients required revision surgery. CONCLUSIONS: The incidence of symptomatic ONFH after OLT was 1.36%. Once the graft function becomes stable, THA can be a safe and effective treatment option for patients with ONFH after OLT.

Closed suction drainage is not beneficial in hybrid total hip arthroplasty with intra-articular administration of tranexamic acid: a propensity score-matched cohort study.

PURPOSE: This retrospective study aimed to evaluate the benefits of closed suction drainage (CSD) in hybrid total hip arthroplasty (THA) with intra-articular administration of tranexamic acid (TXA). METHODS: We included 369 hips that underwent primary hybrid THA between November 2015 and September 2020. We compared peri-operative blood test results, blood loss, and post-operative complications including transfusion, wound complications, and venous thromboembolism (VTE) with or without CSD. Propensity score matching was performed to balance baseline patient demographics. RESULTS: Transfusion, wound complications, and VTE were observed in 1.9% (seven), 2.4% (nine), and 2.2% (eight) of hips, respectively. There were no significant differences in transfusion, blood loss, wound complications, and deep venous thrombosis in both overall patients and propensity score-matched patients with or without CSD. The calculated total blood loss was approximately 600 ml and showed no significant difference between the two groups in the matched cohort (p = 0.59). CONCLUSION: CSD does not provide any benefits and is not needed in primary hybrid THA with intra-articular administration of TXA.

Investigating sagittal spinal alignment, low back pain, and clinical outcomes after total hip arthroplasty for lumbar hyperlordosis: a retrospective study.

INTRODUCTION: Hip-spine syndrome, wherein flexion deformity of the hip might exaggerate normal lumbar lordosis (LL), was first described in 1983. It could result in subluxation of the posterior facets and cause low back pain (LBP). However, the clinical outcomes of total hip arthroplasty (THA) and spinal alignment changes in patients with lumbar hyperlordosis (hyper LL) remain unknown. We aimed to clarify the proportion of patients with hyper LL before THA and compare pre- and post-operative sagittal spinal alignment, LBP, and clinical outcomes between patients with hyper LL and those with normal LL. MATERIALS AND METHODS: We investigated 278 patients who underwent primary THA between December 2015 and December 2019. Spine radiographs in the standing position were examined preoperatively and 1 year postoperatively. Patients with hyper LL were defined as having a pelvic incidence (PI) minus LL of < - 9° preoperatively. The control group included age- and sex-matched patients with normal LL, defined by a PI minus LL of - 9° to 9°. Clinical outcomes were evaluated using the visual analogue scale (VAS) for LBP, Harris hip score (HHS), Oxford hip score (OHS), and University of California, Los Angeles (UCLA) activity score. RESULTS: Thirty-eight patients (13.7%) had hyper LL, and they exhibited a lower pelvic tilt, lower sagittal vertical axis, and greater sigmoid curvature than did the controls. Evaluation of changes in the spinal alignment after surgery showed that the pelvis tilted more posteriorly, and LL decreased more in the hyper LL group than in the control group. Pre- and post-operative VAS for LBP, HHS, OHS, and UCLA activity scores were not significantly different between the two groups. CONCLUSION: Hyper LL in patients with hip osteoarthritis had no adverse effects on LBP and the clinical outcomes of THA. Hyper LL may partially result from a flexible and adaptable lumbo-pelvic structure.

Sacroiliac joint degeneration is common in patients with end-stage hip osteoarthritis secondary to unilateral developmental dysplasia of the hip: Factors associated with its severity and laterality.

BACKGROUND: The etiology of sacroiliac joint (SIJ) degeneration has not been fully elucidated, and there has been almost no report on the relevance between SIJ degeneration and hip osteoarthritis secondary to developmental dysplasia of the hip (DDH). We investigated factors associated with SIJ degeneration, specifically its laterality in patients with end-stage hip osteoarthritis secondary to unilateral DDH. METHODS: We included 152 patients with end-stage unilateral hip osteoarthritis secondary to DDH who underwent primary THA between January 2008 and November 2015. SIJ degeneration was classified (type 0, no degenerative change, to type 3, ankyloses) using preoperative axial computed tomography. SIJ degeneration of the DDH (shorter leg) and contralateral (longer leg) sides was compared; differences in patient demographics and radiological parameters between SIJ degeneration of type 0 or 1 versus type 2 or 3 for the shorter and longer leg sides were analyzed. RESULTS: SIJ on the longer leg side showed more degenerative changes (p < 0.001). Substantial SIJ degeneration or ankylosis (type 2 or 3) was observed on 62.5% of longer leg sides and 33.6% of shorter leg sides. Factors significantly associated with SIJ degeneration severity were percent hip subluxation and leg length discrepancy for the longer leg side and body weight and body mass index (BMI) for the shorter leg side. Patients with worse degeneration on the shorter leg side (9.9%) had significantly larger BMI and longer sagittal vertical axis, whereas patients with worse degeneration on the longer leg side (46.7%) had significantly longer leg length discrepancy. CONCLUSION: Severe SIJ degeneration was common in patients with end-stage hip osteoarthritis secondary to unilateral DDH. Patients with worse SIJ degeneration on the longer leg side had more hip subluxation, whereas patients with worse SIJ degeneration on the shorter leg (DDH) side tended to have sagittal spinal imbalance and greater body weight with larger BMI.

Long-term outcome of cemented total hip arthroplasty with the Charnley-type femoral stem made of titanium alloy.

BACKGROUND: Total hip arthroplasty is a successful treatment for hip diseases including osteoarthritis, osteonecrosis of the femoral head, and rheumatoid arthritis. Various designs of cemented femoral stems made of stainless steel and titanium alloy have been used. Among them, Charnley-type femoral stems made of stainless steel have often been reported to have good long-term outcome. However, the long-term outcome of the Charnley-type femoral stem made of Ti alloy is yet to be reported. We conducted a retrospective study to assess the long-term outcome of cemented primary total hip arthroplasty with the Charnley-type femoral stem made of Ti alloy. METHODS: Between October 1988 and February 1997, 341 cemented primary total hip arthroplasties with the Charnley-type femoral stem made of Ti alloy were consecutively performed in our hospital. Among these, 164 patients (211 hips) who underwent this procedure were followed up for more than 12 years, and the surgical hips were analysed clinically and radiologically. The mean follow-up period was 20.6 years. Kaplan-Meier survival analyses were performed to assess femoral component survival. Factors affecting stem revision for aseptic loosening were also investigated using log-rank tests. RESULTS: In the functional assessment, the preoperative Japanese Orthopaedic Association score significantly improved from 47.2 points preoperatively to 79.0 points at the final follow-up. Eventually, 33 femoral stems were revised, of which 12 were revised for aseptic loosening. In the Kaplan-Meier survival analysis, the 20-year survival rates with stem revision for aseptic loosening and radiological stem loosening at the end points were 95.9% and 97.1%, respectively. Original diagnosis (non-osteoarthritis) was the only significant factor for aseptic loosening of the femoral stem. CONCLUSIONS: Cemented primary total hip arthroplasty with the Charnley-type femoral stem made of Ti alloy showed excellent outcomes for more than 20 years.

Clinical and radiographic evaluation of cemented socket fixation concomitant to acetabular bone grafting fixed with absorbable hydroxyapatite-poly-l-lactide composite screws.

BACKGROUND: The durability of uncalcined and unsintered hydroxyapatite-poly-l-lactide composite screws is unclear when used for the fixation of acetabular bone graft in total hip arthroplasty under full-weight conditions. We have used this type of screw for the fixation of acetabular bone graft in cemented or reverse-hybrid total hip arthroplasty since 2003. Hence, we conducted a follow-up study to assess the safety and efficacy of these screws when used for cemented socket fixation. METHODS: In this study, 98 patients (106 cases) who underwent fixation of acetabular bone graft in cemented or reverse-hybrid total hip arthroplasty using hydroxyapatite-poly-l-lactide composite screws were followed up for over 5 years and evaluated clinically and radiographically. The patient population comprised 10 men and 88 women with a mean age of 60.3 years (range, 41-81 years) at the time of surgery. The original diagnosis for primary total hip arthroplasty was secondary osteoarthritis in 97 cases and high hip dislocation in nine cases. RESULTS: The mean follow-up period was 7.6 years (range, 5-11 years). No patient in this series required revision surgery, and no radiographical loosening occurred during the follow-up period. The mean Japanese Orthopaedic Association score improved from 48 (range, 7-73) preoperatively to 87 (range, 50-100) at the final follow-up. Radiographically bone graft consolidation was confirmed in all cases, and no apparent osteolysis around the cemented socket or composite screws was detected. Kaplan-Meier survival analyses with socket revision surgery for any reason, socket loosening, and appearance of a radiolucent line >1 mm in any zone as the endpoints yielded survival rates of 100%, 100%, and 86.8% at 5 years, and 100%, 100%, and 81.0% at 10 years, respectively. CONCLUSION: This absorbable screw seems to have no negative effects on the mid-term clinical results of cemented socket fixation.

Mid- and long-term results of femoral component revision using the cement-in-cement technique: Average 10.8-year follow-up study.

BACKGROUND: Few reports are available on the long-term outcomes of femoral component revision by using the cement-in-cement technique. We report the mid- and long-term results of femoral component revision in total hip arthroplasty using the cement-in-cement technique. METHODS: Between April 1996 and June 2009, 62 consecutive total hip arthroplasties with femoral component revision were performed in 57 patients by using the cement-in-cement technique. We retrospectively reviewed the cases with a follow-up period of at least five years. Three patients died, and two were lost to follow-up. Thus, 52 patients (57 hips), comprising 51 women and one man, were followed for average 10.8 years. RESULTS: The mean Japanese Orthopaedic Association hip score improved from 57.6 points (range, 28-95 points) preoperatively to 79.8 points (range, 52-98 points) at one year postoperatively and to 77.4 points (range, 59-96 points) at the final follow up. Three revisions of the femoral component were necessary. One of the causes for the revision was a periprosthetic infection that occurred 20 months postoperatively. Another was aseptic loosening that occurred 99 months postoperatively and required revision of the acetabular component. The well-fixed femoral component was revised using the cement-in-cement technique at time of the acetabular revision. The third case was aseptic loosening of the femoral component that occurred 84 months postoperatively. The five-, 10-, and 15-year survival rates for the femoral re-revision due to any reason were 98.4%, 94.0%, and 94.0%, respectively. CONCLUSION: Use of the cement-in-cement technique for revision total hip arthroplasty resulted in good mid- and long-term radiological and clinical outcomes.

Investigational regenerative medicine for non-traumatic osteonecrosis of the femoral head: a survey of registered clinical trials.

INTRODUCTION: Osteonecrosis of the femoral head (ONFH) is a refractory disease requiring joint replacement in young patients. Regenerative therapies have been developed. AREAS COVERED: This study surveyed clinical trials on regenerative medicine for ONFH. We extracted clinical trials on non-traumatic ONFH from the websites of five publicly available major registries (EuropeanUnion Clinical Trials Register ([EU-CTR],ClinicalTrials.gov, Chinese ClinicalTrial Registry [ChiCTR], University Hospital Medical InformationNetwork - Clinical Trial Registry [UMIN-CTR] and Australian New Zealand Clinical Trials Registry [ANZCTR]).The trials were classified into six categories based on purpose: surgical treatment, non-drug conservative treatment, conservative drug treatment, therapeutic strategy, diagnosis and pathogenesis, and regenerative therapy.) We extracted 169 clinical trials on ONFH. Of these, 37 were on regenerative medicine, including 29 on cell therapy. Surgical treatment was the most common treatment, followed by regenerative therapy.There were 9 clinical trials registered in the EU-CTR, with 5 on regenerative medicine; 79 trials registered on ClinicalTrials.gov, with 24 on regenerativemedicine; 54 trials registered in the ChiCTR, with 6 on regenerative medicine. EXPERT OPINION: The focus of the joint-preserving surgery has shifted to regenerative therapy based on using cell therapy in early-stage ONFH. The global standardisation of regenerative therapy is still ongoing.

Morphological Changes and Concentricity of the Hip Joint During Gradual Reduction in Infants with Late-Detected Developmental Dysplasia of the Hip: A Retrospective Study.

Background: The relationship between hip morphological changes and joint concentricity in infants with late-detected developmental dysplasia of the hip (DDH) treated with gradual reduction remains unclear. Therefore, we investigated hip morphological changes and concentricity in infants with late-detected unilateral DDH using magnetic resonance imaging (MRI) during gradual reduction. Methods: We enrolled 20 infants aged ≥ 12 months with unilateral DDH. Treatment comprised continuous traction, a hip-spica cast, and an abduction brace. MRI was performed before treatment, immediately after hip-spica cast placement, after cast removal, and at the end of the brace. We evaluated the acetabulum and femoral head morphology and joint concentricity. Results: The mean age was 25 months, and female sex and the left side were predominant. Before treatment, the acetabulum was small and shallow and the femoral head was spherically flat on the affected side. Immediately after the continuous traction, the affected acetabulum and femoral head were still smaller than the healthy/contralateral one. However, they improved to a deeper acetabulum and round femoral head. Intra-articular soft tissue (IAST) and femoral-acetabular distance (FAD) continuously decreased, indicating gradual improvement in joint concentricity. Deeper formation of the acetabulum and round shaping of the femoral head had occurred even in non-concentric reduction. Conclusion: The shape and concentricity of the hip joint improved after treatment; however, the acetabulum and femoral head remained small. The deeper acetabulum and round femoral head were observed the non-concentric reduction before the concentric reduction was achieved. The continuous decrease in IAST and FAD indicates effective post-traction therapy.

Mechanical, bioactive, and long-lasting antibacterial properties of a Ti scaffold with gradient pores releasing iodine ions.

The ideal bone implant would effectively prevent aseptic as well as septic loosening by minimizing stress shielding, maximizing bone ingrowth, and preventing implant-associated infections. Here, a novel gradient-pore-size titanium scaffold was designed and manufactured to address these requirements. The scaffold features a larger pore size (900 µm) on the top surface, gradually decreasing to small sizes (600 µm to 300 µm) towards the center, creating a gradient structure. To enhance its functionality, the additively manufactured scaffolds were biofunctionalized using simple chemical and heat treatments so as to incorporate calcium and iodine ions throughout the surface. This unique combination of varying pore sizes with a biofunctional surface provides highly desirable mechanical properties, bioactivity, and notably, long-lasting antibacterial activity. The target mechanical aspects, including low elastic modulus, high compression, compression-shear, and fatigue strength, were effectively achieved. Furthermore, the biofunctional surface exhibits remarkable in vitro bioactivity and potent antibacterial activity, even under conditions specifically altered to be favorable for bacterial growth. More importantly, the integration of small pores alongside larger ones ensures a sustained high release of iodine, resulting in antimicrobial activity that persisted for over three months, with full eradication of the bacteria. Taken together, this gradient structure exhibits obvious superiority in combining most of the desired properties, making it an ideal candidate for orthopedic and dental implant applications.

Strontium-loaded 3D intramedullary nail titanium implant for critical-sized femoral defect in rabbits.

The treatment of critical-sized bone defects has long been a major problem for surgeons. In this study, an intramedullary nail shaped three-dimensional (3D)-printed porous titanium implant that is capable of releasing strontium ions was developed through a simple and cost-effective surface modification technique. The feasibility of this implant as a stand-alone solution was evaluated using a rabbit's segmental diaphyseal as a defect model. The strontium-loaded implant exhibited a favorable environment for cell adhesion, and mechanical properties that were commensurate with those of a rabbit's cortical bone. Radiographic, biomechanical, and histological analyses revealed a significantly higher amount of bone ingrowth and superior bone-bonding strength in the strontium-loaded implant when compared to an untreated porous titanium implant. Furthermore, one-year histological observations revealed that the strontium-loaded implant preserved the native-like diaphyseal bone structure without failure. These findings suggest that strontium-releasing 3D-printed titanium implants have the clinical potential to induce the early and efficient repair of critical-sized, load-bearing bone defects.

Bone ingrowth into a porous structure is achieved by preceding fibrogenesis and vascularization.

Porous structures are frequently used in surgical implants to strengthen the interlocking power produced by bone ingrowth. Therefore, we aimed to elucidate the mechanism underlying bone ingrowth into a porous structure accompanied by vascularization. A nonbioactive polyetheretherketone implant with a 3D-printed porous structure was prepared and implanted in a bone hole created in the tibias of rabbits. We observed bone ingrowth in the same individual specimens immediately and at 2, 4, 8, and 12 weeks post-implantation using in-vivo computed tomography (CT). Furthermore, a detailed evaluation with blood vessels of each specimen at 2, 4, and 12 weeks was performed with ex-vivo CT and histological specimen. Additional histological evaluation was performed using thin sections of an implant made with thermoplastic polyurethane having the same structure. As a result, the bone invasion began after four weeks, when the construction of fibrous tissue and the spread of new blood vessels within the voids matured. As the bone matured in the load-bearing area, new blood vessels outside the bone matrix regressed. This longitudinal evaluation study suggests that preceding fibrogenesis and vascularization may be key in developing bone ingrowth. STATEMENT OF SIGNIFICANCE: A porous structure is an essential structure for dental and orthopedic implants because it provides strong fixation through bone invasion. Although it was known that vascularization was involved in this, the details were not known. This in vivo study revealed that in order for bone ingrowth to begin, a preparatory period of approximately 4 weeks was required to establish blood flow inside and outside the implant. Furthermore, it was confirmed that by spreading the fibrous structure in advance, it has an advantageous effect on the migration of cells involved in the formation of bones and blood vessels. We pointed out that it is necessary to consider fibrogenesis and vascularization when creating future implants.

Effect of high disease activity on spinal sagittal malalignment in patients with rheumatoid arthritis.

OBJECTIVE: Atlantoaxial subluxation is a well-known serious complication encountered in patients with rheumatoid arthritis (RA). However, it is unknown whether RA affects global spinal alignment. The aim of this study was to investigate whether high disease activity in patients with RA exacerbates spinal sagittal malalignment. METHODS: The authors included 197 patients with RA who were followed up for > 2 years; standing spinal radiographs were obtained in all patients. Patients were divided into persistent moderate disease activity/high disease activity (pMDA/HDA; n = 64) and non-pMDA/HDA (n = 133) groups based on the disease activity at follow-up visits. Radiographic parameters assessed included pelvic incidence, pelvic tilt (PT), lumbar lordosis (LL), thoracic kyphosis (TK), and C7 sagittal vertical axis (SVA). RESULTS: Over an average 5-year follow-up, increases in SVA, PT, and TK and a decrease in LL were observed. The pMDA/HDA group had a larger increase in PT and a higher incidence of vertebral fractures than the non-pMDA/HDA group. After adjusting variables using propensity score matching, the authors still found a higher rate of increase in PT (0.79°/year vs 0.01°/year, p = 0.001) in the pMDA/HDA group than in the non-pMDA/HDA group. This trend remained consistent even when patients who developed vertebral fractures were excluded. CONCLUSIONS: Spinal sagittal alignment deteriorates over time in patients with RA. High disease activity in RA exacerbates spinal deformity.