A Novel Device for Intraoperative Measurement of Stem Anteversion Angle in Total Hip Arthroplasty.

Background: Stem anteversion plays a crucial role in mitigating postoperative complications in total hip arthroplasty (THA). The application of the combined-anteversion theory in THA necessitates the intraoperative measurement of the stem anteversion angle (SAA). However, estimating SAA intraoperatively poses challenges for surgeons lacking a computer-assisted navigation system. In this study, we assessed the precision of intraoperative SAA measurements using a recently developed device, comparing them with 3-dimensional measurements obtained from postoperative computed tomography. Methods: We examined 127 hips in 127 patients who underwent unilateral THA at our institution. Employing our newly constructed device, attachable to rasping broach handles, we measured the SAA intraoperatively. This process involved incorporating the correction angle derived from the preoperative epicondylar view. We then compared the postoperative SAA with the intraoperative measurements, both with and without the correction angle, to ascertain the device's utility. Results: The device yielded an intraoperative SAA measurement of 17.93 ± 7.53°. In contrast, the true SAA measured on postoperative computed tomography was 26.40 ± 9.73°. The discrepancy between intraoperative and true SAA was 8.94 ± 5.44° (without the correction angle) and 4.93 ± 3.85° (with the correction angle). Accuracy within a discrepancy of <5° was achieved in 77 cases (60.6%), and <10° was achieved in 113 cases (89.0%). The accuracy remained consistent regardless of the stem-placement angle (varus/valgus, or flexion/extension) or the presence of ipsilateral knee osteoarthritis. Conclusions: The SAA-measuring device, attachable to various rasping handles, proves useful for straightforward, cost-effective, and noninvasive intraoperative SAA measurement during THA.

Perioperative bleeding control in total hip arthroplasty: hemostatic powder vs. tranexamic acid-a prospective randomized controlled trial.

BACKGROUND: Perioperative bleeding in total hip arthroplasty (THA) can lead to various problems, so effective management of blood loss is needed. This prospective, single-blind, randomized controlled trial aimed to compare the efficacy of topical administration of SURGICEL® (a hemostatic agent of oxidized regenerated cellulose) powder (SP) and tranexamic acid (TXA) in controlling perioperative bleeding during THA. MATERIALS AND METHODS: In total, 114 patients undergoing THA for osteoarthritis were randomized to either group S (THA with SP) or group T (THA with TXA). Data including patient demographics, laboratory data (C-reactive protein [CRP], hemoglobin, and hematocrit), operative time, and intraoperative blood loss were analyzed. Clinical outcomes were assessed using WOMAC, JOA, FJS scores, and visual analog scale (VAS) scores. Primary outcomes were estimated total and postoperative blood loss, while secondary outcomes included hematological test results and various clinical scores. RESULTS: 57 patients were allocated to each group, with 55 in group S and 56 in group T were finally included in the analysis. There was no significant difference (p = 0.141) in estimated total blood loss between group S (788.2 ± 350.1 ml) and group T (714.1 ± 318.4 ml). Hemoglobin and hematocrit levels and WOMAC, and FJS scores were not significantly different between the two groups at any time point. CRP levels were significantly different on postoperative days 4 and 7, and JOA score was significantly different on preoperative and postoperative period. However, the differences in CRP and JOA score values themselves were relatively small and not clinically different. CONCLUSIONS: Topical administration of SP is as effective as TXA in reducing perioperative bleeding in patients undergoing THA. Additionally, no significant difference was observed in early postoperative clinical outcomes between SP and TXA. LEVEL OF EVIDENCE: Therapeutic Level I. TRIAL REGISTRATION: The University Hospital Medical Information Network (UMIN) registration number UMIN000047607.

Stem Alignment With the Tapered Wedge Cementless Stem "Accolade II" Does Not Affect Bone Mineral Density Over 5 Years After Total Hip Arthroplasty.

Background: This study aimed to investigate the relationship between 3-dimensional (3D) alignment and postoperative bone mineral density (BMD) changes with Accolade II tapered wedge stems, which have a different proximal shape from other tapered wedge stems, up to 5 years after primary total hip arthroplasty. Methods: We retrospectively analyzed the hips of 89 patients who underwent total hip arthroplasty using the second-generation proximally coated cementless stem (Accolade II; Stryker Orthopedics, Mahwah, NJ) at our institution from 2014 to 2018 over a 5-year follow-up. We evaluated the relationship between stem alignment, measured using 3D-templating software, and BMD changes in the 7 Gruen zones and compared the data with those from a former study using other short taper-wedge stems. Results: BMDs in zones 1 and 7 continued to decrease gradually every year after surgery, and BMD in zone 7 showed the largest decrease (21%) from baseline over 5 years. No correlation was found between stem alignment (varus/valgus, flexion/extension, and anteversion/retroversion) and changes in BMD in each zone over 5 years. Conclusions: Our data showed no correlation between 3D stem alignment and changes in BMD in each Gruen zone over 5 years. This suggests that the Accolade II stem may fit better into any shape of the proximal medullary canal because of its unique characteristics.

No Impact of Contact Between the Medial Collar of a Hydroxyapatite-Coated Triple-Tapered Stem and the Femoral Neck on Periprosthetic Bone Mineral Density.

BACKGROUND: Hydroxyapatite-coated, triple-tapered, shorter-length stems with a medial collar have been reported with good results for a few years. We investigated whether contact between the medial collar and femoral neck affects clinical outcomes and changes in bone mineral density (BMD) in patients who have this type of stem in their total hip arthroplasty construct. METHODS: This was a retrospective, single-center study involving 62 patients scheduled for unilateral total hip arthroplasty using a hydroxyapatite-coated, triple-tapered, shorter-length stem who were followed for at least 1 year postoperatively. All patients had a Dorr type B femoral canal shape. Contact between the medial collar and the femoral neck was evaluated by computed tomography at the third postoperative month, and patients were classified into 2 groups. Postoperative clinical outcomes were investigated by the Western Ontario and McMaster Universities Arthritis Index and the Japanese Orthopaedic Association scores; radiological evaluation included stem fixation, spot welds and cortical hypertrophy, postoperative 3-dimensional stem alignment, and periprosthetic BMD changes. RESULTS: There were 51 patients in the Contact + group (collar and neck contact) and 11 in the Contact-group (no contact). There were no differences between the 2 groups in the improvement of Western Ontario and McMaster Universities Arthritis Index and Japanese Orthopaedic Association scores, stem fixation, occurrence of cortical hypertrophy, or 3-dimensional stem alignment. Radiolucent lines were present in zones 3, 4, and 5 in 6 patients (12%) in the Contact + group only, who had no statistical difference between the 2 groups. Bone mineral density (BMD) decreased most in zone 7 in both groups, with no difference between the 2 groups. CONCLUSIONS: The presence or absence of contact between the medial collar and femoral neck did not affect postoperative BMD changes or radiological or clinical results. LEVEL OF EVIDENCE: Therapeutic Level III.

Stem alignment with short tapered-wedge cementless stems affects bone mineral density continuously for at least 5 years after primary total hip arthroplasty.

AIM: This study aimed to assess the relationship between the three-dimensional (3D) alignment of short tapered-wedge cementless stems and bone mineral density (BMD) changes in patients followed up for 5 years after total hip arthroplasty (THA). METHODS: We retrospectively analysed the hips of 52 patients who underwent THA using short tapered-wedge cementless stems at our institution from 2013 to 2016 with complete 5-year follow-up data. We evaluated the relationship between stem alignment, measured using a 3D-templating software, and BMD changes in the 7 Gruen zones. RESULTS: After 1 year, significant negative correlations between varus insertion and a decrease in BMD in zone 7 and between flexed insertion and decreases in BMD in zones 3 and 4 were noted. After 5 years, significant negative correlations between varus insertion and a decrease in BMD in zone 7 and between flexed insertion and decreases in BMD zones 2, 3, and 4 were observed. With increased amounts of varus/flexion stem alignment, the amount of BMD loss decreased. There was no correlation between anteverted stem insertion and changes in BMD levels. CONCLUSIONS: Our data showed that stem alignment affects BMD based on 5-year follow-up data after surgery. Careful observation is necessary, especially when using short tapered-wedge cementless stems, as stem alignment may affect changes in BMD levels more than 5 years after surgery.

Impact of microsampling on toxicological evaluation in rodent safety studies.

Recently, animal welfare has been attracting worldwide attention, and implementation of 3Rs (replacement, reduction, and refinement) is prioritized in every way possible in the drug development. Microsampling, in which small amounts of blood are collected, is attracting attention in this context. ICH S3A Q&A focused on microsampling was published in November 2017 to help accelerate the application of microsampling for toxicokinetic assessment. The increased sensitivity of drug measurement apparatuses such as mass spectrometers has made it possible to measure drug concentrations with small amounts of blood samples. In this review, we summarized the reports on toxicological influence of microsampling in rodents (rats and mice) with or without drug administration or recovery period after blood collection and influences that may arise from differences in the blood sampling site or blood sampling volume. We also summarized some perspectives on further implementation of microsampling in toxicology studies. The use of microsampling in regulatory toxicology studies has gradually increased, although at a lower rate than in discovery studies. Since more animals are used in GLP toxicology studies than in discovery studies, the effect of reducing the number of animals by microsampling is expected to be greater in the toxicology studies. This report aims to promote the application of microsampling to nonclinical studies, as it is beneficial for improving animal welfare and can contribute to the 3Rs.

Active-phase Plasma Alkaline Phosphatase Isozyme Activity Is a Sensitive Biomarker for Excessive Fructose Intake.

BACKGROUND/AIM: Excessive fructose intake reportedly leads to the development of nonalcoholic fatty liver disease (NAFLD). In our previous study, we reported that plasma activities of alkaline phosphatase (ALP) isozymes were markedly changed in rats with excessive fructose intake-induced hepatomegaly. In this study, we examined ALP isozyme activity prior to the occurrence of hepatomegaly, and investigated the effect of the timing of sample collection, to explore its potential as a biomarker. MATERIALS AND METHODS: After 1-week intake of a 63% high-fructose diet (HFrD), blood samples were collected from male rats during sleep or active phases to analyze biochemical parameters. RESULTS: Body and liver weights were similar between the HFrD and control diet groups, indicating that hepatomegaly due to excessive fructose intake had not occurred. The triglyceride levels and glutamate dehydrogenase (GLDH) activity were significantly elevated to similar degrees at both time points. HFrD intake significantly increased liver-type ALP (L-ALP) activity, stimulating it by 12.7% at the sleep phase and by 124.3% at the active phase. HFrD consumption also significantly decreased intestinal-type ALP (I-ALP) at the active phase, but only showed a decreasing trend during the sleep phase. CONCLUSION: Measurements of plasma ALP isozyme and GLDH activity, and triglyceride levels are effective early biomarkers of impending NAFLD caused by excessive fructose intake. L-ALP and I-ALP activities during the active phase are particularly sensitive for detection of excessive fructose intake before the occurrence of NAFLD.

Measurement of spinopelvic sagittal alignment in the relaxed seated position rather than in the straight seated position is suitable for assessing spinopelvic mobility in patients before total hip arthroplasty.

PURPOSE: The relationship between spinopelvic mobility and dislocation in total hip arthroplasty (THA) has recently attracted attention. This study aimed to investigate the differences in sacral slope (SS) between two types of upright seated positions and to determine which seated position was appropriate for assessing spinopelvic mobility (change in SS from standing to sitting) before THA. MATERIALS AND METHODS: This prospective cohort study included 75 hips from 75 patients who had undergone primary THA. Each patient underwent preoperative lateral spinopelvic radiography in standing (st) and two seated positions: relaxed (rs) and straight (ss). The change in SS between each position (Δ) was measured. RESULTS: Differences in all spinopelvic sagittal alignment parameters between the two seated positions were statistically significant (p < 0.001). The range, median, and mean values of ΔSSss-rs were -2.0° to 26.5°, 6.8°, and 8.3°, respectively. ΔSSss-rs was significantly correlated with SS, LLA, and PFA in the relaxed seated position (r = -0.52, -0.39, and 0.37; p < 0.001, p < 0.001, and p = 0.001, respectively), but was not correlated to these parameters in the straight seated position. Of the 52 patients with normal spinopelvic mobility in the relaxed seated position (ΔSSst-rs > 10°), 24 (46%) patients were misrepresented as having a stiff spine in the straight seated position (ΔSSst-ss < 10°). CONCLUSION: The change in SS from the straight to the relaxed seated position widely varied in patients before THA. The spinopelvic radiograph in the relaxed seated position is appropriate when evaluating spinopelvic mobility for preoperative planning.

Novel Biomarker Establishment for Evaluation of Excessive Fructose Consumption Using a Rat Model.

BACKGROUND/AIM: The habitual consumption of excessive fructose is associated with the onset and progression of lifestyle-related diseases, such as nonalcoholic fatty liver disease (NAFLD). In this study, we investigated the physiological changes observed when consuming a diet containing excessive fructose on the viewpoints of hepatotoxicity biological markers using a rat model and explored the biomarker candidates that could detect the effects of excessive fructose intake at an early stage. MATERIALS AND METHODS: Male rats were fed 63% high fructose diet (HFrD) ad libitum and their blood samples were collected before and at 1, 2, 3, and 4 weeks after allocation. The plasma biochemical parameters, hepatotoxic enzyme activities including alkaline phosphatase (ALP) isozymes were analyzed. RESULTS: HFrD consumption for 4-weeks created NAFLD-like symptoms, including elevated plasma lipid parameters and hepatotoxicity markers, as well as fat accumulation in the liver compared with rats consuming a control diet. Alanine aminotransferase (ALT) and glutamate dehydrogenase (GLDH) were increased from the 3rd and 2nd weeks, respectively, but no changes were observed on ALP activity. However, the daily consumption of the HFrD increased the plasma activities of liver-type ALP isozyme, and decreased plasma small intestinal-type ALP isozyme soon after the start of feeding. CONCLUSION: ALP isozyme analysis in combination with GLDH and ALT activities in the plasma samples could be a useful tool to detect the physiological changes induced by excessive fructose intake at an early stage of the development of NAFLD.

Relationship between body mass index and spinal pathology in community-dwelling older adults.

PURPOSE: To clarify the relationship between body mass index (BMI) and spinal pathologies including spinal sagittal balance, back extensor strength (BES), paraspinal muscle mass, prevalent vertebral fracture, disc degeneration, Modic changes, low back pain, and quality of life (QOL) in community-dwelling older adults. METHODS: This study included 380 participants (age: ≥ 65 years, male/female: 152/228) from the Shiraniwa Study. Multivariate nonlinear regression analysis was used to investigate the relationship between BMI and sagittal vertical axis (SVA), BES, paraspinal muscle mass, visual analog scale (VAS) for low back pain, Oswestry Disability Index (ODI), and EuroQoL-5 Dimension (EQ5D) score after adjusting for sex, age, Hospital Anxiety and Depression Scale score, and Charlson Comorbidity Index. In addition, multiple logistic regression analysis was used to investigate the association between BMI and prevalent vertebral fracture, disc degeneration, and Modic changes. RESULTS: BMI was significantly correlated with SVA, BES, paraspinal muscle mass, VAS, ODI, and EQ5D score. The increase in BMI was associated with the deterioration of all outcomes, which accelerated when the BMI increased from approximately 22-23 kg/m2. Moreover, overweight/obesity was significantly correlated with disc degeneration and Modic changes. CONCLUSION: Increased BMI is significantly associated with spinal pathologies such as SVA, BES, paraspinal muscle mass, VAS, QOL, disc degeneration, and Modic changes. The findings suggest that measures for controlling overweight and obesity among older adults can play an important role in the prevention and treatment of spinal pathologies.

A comparison of accuracy and safety between stem-first and cup-first total hip arthroplasty: a prospective randomised controlled trial.

BACKGROUND: The combined anteversion theory to prevent impingement in total hip arthroplasty (THA) has been proposed. However, because stem-anteversion is influenced by the native femoral anteversion and the stem flexion/extension angle, it is often difficult to adjust stem anteversion during surgery. Therefore, the stem-first (combined anteversion) technique may be useful to adjust and achieve appropriate cup anteversion during surgery with respect to the implanted stem anteversion angle. However, the technique may adversely affect cup or stem angle accuracy and result in intra-operative bleeding, post-operative adverse events, and prolonged operative time. It is inconclusive whether either the stem-first or cup-first technique is safe or accurate. Therefore, this study assessed the accuracy and safety of stem-first THA compared to those of cup-first THA. MATERIALS AND METHODS: This prospective randomised controlled trial analysed 114 patients who were randomly divided into 2 groups (stem-first group: n = 57, cup-first group (control group): n = 57). Primary outcomes included cup and stem angle, the discrepancies from the targeted angle and combined anteversion (evaluated via CT at 3 months postoperatively). Secondary outcomes included intraoperative blood loss, operative time, WOMAC, and adverse events. RESULTS: There were no significant differences in age, gender, BMI or in the primary and secondary outcomes between the 2 groups. CONCLUSIONS: Performing stem-first in THA did not adversely affect cup and stem angle accuracy, or result in intraoperative bleeding, prolongation of operative time, or postoperative adverse events. Thus, performing stem-first may be advantageous for achieving combined anteversion theory. TRIAL REGISTRATION: University Hospital Medical Information Network (UMIN) registration number UMIN000025189.

Building kidney organoids from pluripotent stem cells.

PURPOSE OF REVIEW: During embryogenesis, the kidney is mainly generated from three progenitor cells; nephron progenitors, ureteric bud progenitors and stromal progenitors. Mutual interactions of the all three progenitor populations are essential to form a functional kidney with the higher-order structure. Pluripotent stem cells have potential to differentiate into all cell types of the animal body, including the kidney. In this review, we will summarize recent advances in reconstructing kidney organoids from pluripotent stem cells. RECENT FINDINGS: In the past years, major advances were reported to induce nephron and ureteric bud progenitors from pluripotent stem cells in mice and humans, and to create kidney organoids of nephron and/or ureteric bud-derived collecting duct tissues in vitro. These kidney organoid technologies were applied to high-throughput genetic screenings and small chemical screenings to identify key factors for kidney development and disease. Furthermore, a novel method was established to induce stromal progenitors from pluripotent stem cells, leading to creation of kidney organoids with the higher-order structures completely derived from pluripotent stem cells. SUMMARY: These advances in kidney organoids from pluripotent stem cells should lay a foundation to establish a novel therapy for kidney disease, which ultimately eliminate the need of dialysis and kidney transplantation for patients with kidney disease in the future.

Mice Lacking Wnt9a or Wnt4 Are Prone to Develop Spontaneous Osteoarthritis With Age and Display Alteration in Either the Trabecular or Cortical Bone Compartment.

Osteoarthritis (OA) is a common degenerative disease of the joint, with a complex multifactorial not yet fully understood etiology. Over the past years, the Wnt signaling pathway has been implicated in osteoarthritis. In a recent genomewide association study (GWAS), the chromosomal location on chromosome 1, linked to the Wnt3a-Wnt9a gene locus, was identified as the most significant locus associated with a thumb osteoarthritis endophenotype. Previously, it was shown that WNT9a is involved in maintaining synovial cell identity in the elbow joint during embryogenesis. Here, we report that the conditional loss of Wnt9a in the Prx1-Cre expressing limb mesenchyme or Prg4-CreER expressing cells predispositions the mice to develop spontaneous OA-like changes with age. In addition, the trabecular bone volume is altered in these mice. Similarly, mice with a conditional loss of Wnt4 in the limb mesenchyme are also more prone to develop spontaneously OA-like joint alterations with age. These mice display additional alterations in their cortical bone. The combined loss of Wnt9a and Wnt4 increased the likelihood of the mice developing osteoarthritis-like changes and enhanced disease severity in the affected mice. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Phosphatidylcholine (18:0/20:4), a potential biomarker to predict ethionamide-induced hepatic steatosis in rats.

Ethionamide (ETH), a second-line drug for multidrug-resistant tuberculosis, is known to cause hepatic steatosis in rats and humans. To investigate predictive biomarkers for ETH-induced steatosis, we performed lipidomics analysis using plasma and liver samples collected from rats treated orally with ETH at 30 and 100 mg/kg for 14 days. The ETH-treated rats developed hepatic steatosis with Oil Red O staining-positive vacuolation in the centrilobular hepatocytes accompanied by increased hepatic contents of triglycerides (TG) and decreased plasma TG and total cholesterol levels. A multivariate analysis for lipid profiles revealed differences in each of the 35 lipid species in the plasma and liver between the control and the ETH-treated rats. Of those lipids, phosphatidylcholine (PC) (18:0/20:4) decreased dose-dependently in both the plasma and liver. Moreover, serum TG-rich very low-density lipoprotein (VLDL) levels, especially the large particle fraction of VLDL composed of PC containing arachidonic acid (20:4) involved in hepatic secretion of TG, were decreased dose-dependently. In conclusion, the decreased PC (18:0/20:4) in the liver, possibly leading to suppression of hepatic TG secretion, was considered to be involved in the pathogenesis of the ETH-induced hepatic steatosis. Therefore, plasma PC (18:0/20:4) levels are proposed as mechanism-related biomarkers for ETH-induced hepatic steatosis.

Generation of the organotypic kidney structure by integrating pluripotent stem cell-derived renal stroma.

Organs consist of the parenchyma and stroma, the latter of which coordinates the generation of organotypic structures. Despite recent advances in organoid technology, induction of organ-specific stroma and recapitulation of complex organ configurations from pluripotent stem cells (PSCs) have remained challenging. By elucidating the in vivo molecular features of the renal stromal lineage at a single-cell resolution level, we herein establish an in vitro induction protocol for stromal progenitors (SPs) from mouse PSCs. When the induced SPs are assembled with two differentially induced parenchymal progenitors (nephron progenitors and ureteric buds), the completely PSC-derived organoids reproduce the complex kidney structure, with multiple types of stromal cells distributed along differentiating nephrons and branching ureteric buds. Thus, integration of PSC-derived lineage-specific stroma into parenchymal organoids will pave the way toward recapitulation of the organotypic architecture and functions.

Medial peg position of cementless porous tantalum tibial component affects bone mineral density around the prosthesis after total knee arthroplasty: 2-year follow-up study.

BACKGROUND: Use of a porous tantalum tibial component for total knee arthroplasty (TKA) was reported to have beneficial effects on periprosthetic bone mineral density (BMD). In some cases, hexagonal peg is placed close to or in contact with the tibial cortex, which may result in stress-shielding around the peg. However, no studies have analyzed the relationship between peg position and BMD. The aim of this study was to compare the peg position and BMD around the peg in a porous tantalum tibial component after TKA. METHODS: Twenty-seven patients (27 knees) who underwent primary TKA with a cementless porous tantalum tibial component were investigated. BMD was measured by dual-energy X-ray absorptiometry for 2 years after the operation. The distance between the peg and the tibial cortex (peg distance) was measured on the medial and lateral sides. RESULTS: BMD was decreased in the medial region after the operation (p < 0.01). Relative change in BMD was lower in the medial region than in the central and lateral regions (p < 0.01). Multiple regression analysis showed that medial peg distance was negatively correlated with relative change of BMD in the medial part of the tibia (p = 0.04, R = 0.402). CONCLUSIONS: The medial peg position affected the postoperative relative change of BMD in the medial part of the tibia, but did not affect the longevity of the implant. As the tibial medial peg became closer to the medial tibial cortex, the BMD loss became larger in the medial part of the tibia at 2 years postoperatively.

A cemented mobile-bearing total knee prosthesis prevents peri-prosthetic bone mineral density loss around the femoral component: a consecutive follow-up at a mean of 11 years.

PURPOSE: Research has shown that a cemented mobile-bearing component has a favorable effect on the bone mineral density (BMD) of the distal femur at 2 years after total knee arthroplasty (TKA). This study was performed to determine whether the advantage on BMD of a cemented mobile-bearing TKA over a conventional cemented fixed-bearing TKA changes with time. This report is an update of a matched cohort study initiated in 2004 and for which the 2-year results have been published. METHODS: Twenty-eight knees that were treated with a fixed-bearing posterior stabilized (PS) prosthesis and 28 matched knees from a database of 76 knees that were treated with a mobile-bearing PS prosthesis in the same period were investigated. All knees underwent dual-energy X-ray absorptiometry (DEXA) scans around the femoral component preoperatively, 2 weeks postoperatively, 5 years postoperatively, and annually thereafter. Eighteen knees with a cemented mobile-bearing PS prosthesis and 20 knees with a cemented fixed-bearing PS prosthesis were investigated for more than 6 years. The mean follow-up period was 11 years. RESULTS: The range of motion, Knee Society Score, BMD of the lumbar spine, and follow-up period were not significantly different preoperatively and postoperatively in the two groups. In the fixed-bearing group, the BMD of the anterior part of the femoral condyle decreased postoperatively. In the mobile-bearing group, the BMD of the posterior part of the femoral condyle increased postoperatively. The postoperative change in the BMD at 5 years and the latest follow-up period was statistically significant in the two groups. CONCLUSIONS: This DEXA study revealed that a cemented mobile-bearing component had a favorable effect on the BMD of the distal femur after TKA even at a mean of 11 years postoperatively. LEVEL OF EVIDENCE: Therapeutic study, level II, prospective comparative study.

Is medial pivot total knee arthroplasty suitable for patients with valgus knee osteoarthritis?

PURPOSE: Medial pivot total knee arthroplasty (MP-TKA) is characterized by the ball-in-socket medial tibiofemoral articulation to achieve low wear and to reproduce the medial pivot motion similar to that in the normal knee, and there have been reports of favorable long-term postsurgical outcomes. However, most of these cases concerned varus knees, and the outcomes of MP-TKA in valgus knees are unknown. The objective of this study was to investigate the postoperative outcomes in end-stage valgus knee OA patients who underwent MP-TKA, through comparisons with those who underwent TKA using the same prosthesis for varus deformity. METHODS: This retrospective, single-center, cohort study analyzed 171 knees of 121 patients who were divided into two groups (valgus knee group: 15 knees (13 patients), varus knee group: 156 knees (109 patients)). Primary outcome measures included the knee joint range of motion (evaluated preoperatively and at every year postoperatively). Secondary outcomes included operative time, laboratory data, estimated blood loss, clinical outcome measures and adverse events. RESULTS: There were no significant differences in age, sex and body mass index, as well as in the postoperative primary and secondary outcome measures between the two groups. CONCLUSION: The use of MP-TKA featuring ball-in-socket medial tibiofemoral articulation in patients with valgus knee OA showed equally favorable clinical outcomes more than 2 years after surgery, compared to patients with varus knees who received MP-TKA.

Trunk Muscle Mass Measured by Bioelectrical Impedance Analysis Reflecting the Cross-Sectional Area of the Paravertebral Muscles and Back Muscle Strength: A Cross-Sectional Analysis of a Prospective Cohort Study of Elderly Population.

Trunk muscles play an important role in supporting the spinal column. A decline in trunk muscle mass, as measured by bioelectrical impedance analysis (TMM-BIA), is associated with low back pain and poor quality of life. The purpose of this study was to determine whether TMM-BIA correlates with quantitative and functional assessments traditionally used for the trunk muscles. We included 380 participants (aged ≥ 65 years; 152 males, 228 females) from the Shiraniwa Elderly Cohort (Shiraniwa) study, for whom the following data were available: TMM-BIA, lumbar magnetic resonance imaging (MRI), and back muscle strength (BMS). We measured the cross-sectional area (CSA) and fat-free CSA of the paravertebral muscles (PVM), including the erector spinae (ES), multifidus (MF), and psoas major (PM), on an axial lumbar MRI at L3/4. The correlation between TMM-BIA and the CSA of PVM, fat-free CSA of PVM, and BMS was investigated. TMM-BIA correlated with the CSA of total PVM and each individual PVM. A stronger correlation between TMM-BIA and fat-free CSA of PVM was observed. The TMM-BIA also strongly correlated with BMS. TMM-BIA is an easy and reliable way to evaluate the trunk muscle mass in a clinical setting.