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.

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.

Design and Escherichia coli Expression of a Natively Folded Multi-Disulfide Bonded Influenza H1N1-PR8 Receptor-Binding Domain (RBD)

Refolding multi-disulfide bonded proteins expressed in E. coli into their native structure is challenging. Nevertheless, because of its cost-effectiveness, handiness, and versatility, the E. coli expression of viral envelope proteins, such as the RBD (Receptor-Binding Domain) of the influenza Hemagglutinin protein, could significantly advance research on viral infections. Here, we show that H1N1-PR8-RBD (27 kDa, containing four cysteines forming two disulfide bonds) expressed in E. coli and was purified with nickel affinity chromatography, and reversed-phase HPLC was successfully refolded into its native structure, as assessed with several biophysical and biochemical techniques. Analytical ultracentrifugation indicated that H1N1-PR8-RBD was monomeric with a hydrodynamic radius of 2.5 nm. Thermal denaturation, monitored with DSC and CD at a wavelength of 222 nm, was cooperative with a midpoint temperature around 55 °C, strongly indicating a natively folded protein. In addition, the 15N-HSQC NMR spectrum exhibited several 1H-15N resonances indicative of a beta-sheeted protein. Our results indicate that a significant amount (40 mg/L) of pure and native H1N1-PR8-RBD can be produced using an E. coli expression system with our refolding procedure, offering potential insights into the molecular characterization of influenza virus infection.

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.

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.

How Do Spinal Parameters Change in Patients Who Have Improvement of Low Back Pain After Total Hip Arthroplasty? A Propensity Score-Matched Cohort Study

BACKGROUND

Many studies have demonstrated that low back pain (LBP) improves after total hip arthroplasty (THA). However, the mechanism underlying this improvement remains unclear. We aimed to investigate changes in the spinal parameters of patients who had LBP improvement after THA to elucidate the mechanism of LBP improvement.

METHODS

We included 261 patients who underwent primary THA between December 2015 and June 2021 and had a preoperative visual analog scale score of ≥ 2 for LBP. The patients were classified into the LBP-improved or LBP-continued groups based on the visual analog scale for LBP at 1 year after THA. Preoperative and postoperative changes in the coronal and sagittal spinal parameters were compared between the 2 groups after propensity score matching for age, sex, body mass index, and preoperative spinal parameters.

RESULTS

A total of 161 patients (61.7%) were classified into the LBP-improved group. After 85 patients in both groups were matched, the LBP-improved group showed significant differences in spinal parameter changes, which were a higher lumbar lordosis (LL) (P = .04) and lower sagittal vertical axis (SVA) (P = .02) and pelvic incidence (PI) minus LL (PI-LL) (P = .01) postoperatively, whereas the LBP-continued group showed worsened changes in LL and SVA and PI-LL mismatch.

CONCLUSION

Patients who had LBP improvement after THA had significant differences in spinal parameter changes in LL, SVA, and PI-LL. These spinal parameters may be the key factors in the mechanism of LBP improvement after THA.

Reproducibility, criterion-related validity, and minimal clinically important difference of the stair negotiation test after total Hip arthroplasty

OBJECTIVE

To determine the reproducibility, criterion-related validity, and minimal clinically important difference (MCID) of the stair negotiation test (SNT) after total hip arthroplasty (THA).

METHODS

Sixty patients who underwent THA were included in this study. They performed the SNT and rated their difficulty in stair negotiation (question 7 of the Oxford Hip Score [OHSQ7]) before and 6 months after surgery. The SNT determined the time taken by a patient to ascend, turn around, and descend the stairs (15 cm × 4 steps) and was measured twice each time. As a measure of reproducibility, the intraclass correlation coefficient (ICC1,1) was calculated using the preoperative SNT. As an index of criterion-related validity, Spearman's rank correlation coefficient was used to evaluate the relationship between the better score of two trials in the preoperative SNT and the OHSQ7. The MCID of the SNT was calculated using the distribution-based method and the anchor-based method. The change in the OHSQ7 between before and after surgery was used as an anchor in the latter method.

RESULTS

The ICC1,1 of the SNT was 0.97. The SNT was significantly correlated with the OHSQ7 (r = 0.40, p < .05). Moreover, the anchor-based MCID of the SNT was 1.98 seconds.

CONCLUSION

The SNT is an objective assessable test of stair negotiation ability in post-THA patients that has good reproducibility and moderate criterion-related validity. Changes in the SNT beyond the MCID (1.98 seconds) represent clinically important changes in stair negotiation ability.

Identifying Muscle Function-based Phenotypes Associated With Radiographic Progression of Secondary Hip Osteoarthritis

OBJECTIVE

The purposes of our study were to (1) identify muscle function-based clinical phenotypes in patients with hip osteoarthritis (OA) and (2) determine the association between those phenotypes and radiographic progression of hip OA.

DESIGN

Prospective cohort study.

SETTING

Clinical biomechanics laboratory of a university.

PARTICIPANTS

Fifty women patients with mild-to-moderate secondary hip OA (N=50) were recruited from the orthopedic department of a single institution.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Two-step cluster analyses were performed to classify the patients, using hip flexion, extension, abduction, and external/internal rotation muscle strength (cluster analysis 1); relative hip muscle strength to total hip strength (ie, hip muscle strength balance; cluster analysis 2); and both hip muscle strength and muscle strength balance (cluster analysis 3) as variables. The association between the phenotype and hip OA progression over 12 months (indicated by joint space width [JSW] >0.5 mm) was investigated by logistic regression analyses. Hip joint morphology, hip pain, gait speed, physical activity, Harris hip score, and SF-36 scores were compared between the phenotypes.

RESULTS

Radiographic progression of hip OA was observed in 42% of the patients. The patients were classified into 2 phenotypes in each of the 3 cluster analyses. The solution in cluster analyses 1 and 3 was similar, and high-function and low-function phenotypes were identified; however, no association was found between the phenotypes and hip OA progression. The phenotype 2-1 (high-risk phenotype) extracted in cluster analysis 2, which had relative muscle weakness in hip flexion and internal rotation, was associated with subsequent hip OA progression, even after adjusting for age and minimum JSW at baseline (adjusted odds ratio [95% confidence interval], 3.60 [1.07-12.05]; P=.039).

CONCLUSION

As preliminary findings, the phenotype based on hip muscle strength balance, rather than hip muscle strength, may be associated with hip OA progression.

Biophysical and biochemical nature of amorphous protein oligomers determines the strength of immune response and the generation of T-cell memory

Here, we used domain 3 of dengue virus serotype 3 envelope protein (D3ED3), a natively folded globular low-immunogenicity protein, to ask whether the biophysical nature of amorphous oligomers can affect immunogenicity. We prepared nearly identical 30 ~ 50 nm-sized amorphous oligomers in five distinct ways and looked at any correlation between their biophysical properties and immunogenicity. One oligomer type was produced using our SCP tag (solubility controlling peptide) made of 5 isoleucines (C5I). The others were prepared by miss-shuffling the SS bonds (Ms), heating (Ht), stirring (St) and freeze-thaw (FT). Dynamic light scattering showed that all five formulations contained oligomers of approximately identical sizes with hydrodynamic radii (Rh) between 30 and 55 nm. Circular dichroism (cd) indicated that the secondary structure content of oligomers formed by stirring and freeze-thaw was essentially identical to that of the native monomeric D3ED3. The secondary structure content of the Ms showed moderate changes, whereas the C5I and heat-induced (Ht) oligomers exhibited a significant change. The Ms contained D3ED3 with intermolecular SS bonds as assessed by nonreducing size exclusion chromatography (SEC). Immunization in JcL:ICR mice showed that both C5I and Ms significantly increased the anti-D3ED3 IgG titre. Ht, St and FT were only mildly immunogenic, similar to the monomeric D3ED3. Cell surface CD marker analysis by flow cytometry confirmed that immunization with Ms generated a strong central and effector T-cell memory. Our observations indeed suggest that controlled oligomerization can provide a new, adjuvant-free method for increasing a protein's immunogenicity, yielding a potentially powerful platform for protein-based (subunit) vaccines.

E. coli production of a multi-disulfide bonded SARS-CoV-2 Omicron BA.5 RBD exhibiting native-like biochemical and biophysical properties

Low-cost bacterial production of the receptor binding domain (RBD) of the SARS-CoV-2 Omicron spike protein holds significant potential in expediting the development of therapeutics against COVID-19. However, RBD contains eight cysteines forming four disulfide bonds, and expression in E. coli using standard protocols produces insoluble RBD forming non-native disulfide bonds. Here, we expressed RBD in E. coli T7 SHuffle with high aeration, which enhanced disulfide formation in the cytoplasm and reshuffling of non-native disulfide bonds, and at a low temperature of 16°C, which stabilized the native conformation and thus the formation of the native disulfide bonds. The yield of RBD was as high as 3 mg per 200 mL culture. We analyzed the conformational and biophysical properties of our E. coli-expressed RBD. First, the RP-HPLC elution profile indicated a single peak, suggesting that RBD was folded with a single disulfide bond pairing pattern. Next, circular dichroism analysis indicated a secondary structure content very close to that computed from the crystal structure. RBD's thermal denaturation monitored by CD was cooperative, strongly indicating a well-folded protein structure. Moreover, limited proteolysis showed that RBD was nearly as stable as RNase A, and the formation of native disulfide bonds was confirmed by LC-MS analysis. Furthermore, BLI analysis indicated a strong binding of RBD with the hACE2 with a dissociation constant of 0.83 nM, confirming the folded nature of RBD. Altogether, these results demonstrate that our E. coli-expression system can provide a large amount of highly purified RBD with correct disulfide bonds and native-like biochemical and biophysical properties.

Anti-Inflammatory Actions of Expectorants in a Rat Carrageenan-Induced Footpad Edema Model

S-Carboxymethyl-L-cysteine (SCMS) exhibits sputum-regulating and anti-inflammatory actions. Previous studies reported the anti-inflammatory effects of SCMS on chronic inflammatory diseases, but no study has examined these effects on acute inflammatory diseases. In this study, we investigated the anti-inflammatory effects of SCMS in a rat carrageenan-induced footpad edema model, which is routinely used as an acute inflammation model. Expectorants were administered to rats with footpad edema induced by subcutaneously administering 1%λ-carrageenan to the footpad of the left posterior limb, and the dose dependency of the anti-inflammatory effects was evaluated. As a result, even when the dose of SCMS was increased to 400 mg/kg, there were no inhibitory effects on edema. Furthermore, we examined the inhibitory effects of other expectorants (ambroxol hydrochloride, N-acetyl-L-cysteine, L-cysteine ethylester hydrochloride, and L-cysteine methylester hydrochloride), which were reported to exhibit anti-inflammatory effects on chronic inflammation, on edema. However, none of these expectorants inhibited edema.

Closed Suction Drainage May Not be Beneficial in Revision Total Hip Arthroplasty: A Propensity Score-Matched Cohort Study

Background

Many studies on closed suction drainage (CSD) in primary total hip arthroplasty (THA) have demonstrated that it has no definite benefit. However, evidence of the clinical benefits of CSD in revision THA has not yet been established. Therefore, this retrospective study aimed to investigate the benefits of CSD in revision THA.

Materials and Methods

We reviewed 107 hips of patients who underwent revision THA between June 2014 and May 2022, excluding cases of fracture and infection. We compared perioperative blood test results, calculated total blood loss (TBL), and postoperative complications, including allogenic blood transfusion (ABT), wound complications, and deep venous thrombosis (DVT), between the groups with and without CSD. Propensity score matching was conducted to balance patients' demographics and surgical factors.

Results

ABT, wound complications, and DVT were observed in 10.3% (n = 11), 5.6% (six), and 5.6% (six) of patients, respectively. There were no significant differences in ABT, calculated TBL, wound complications, and DVT between all patients and propensity score-matched patients with or without CSD. The calculated TBL was approximately 1200 mL and showed no significant difference between the two groups in the matched cohort (p = 0.40) but tended to have a greater volume in the drain group than in the non-drain group.

Conclusion

The routine use of CSD in revision THA for aseptic loosening may not be useful in clinical practice.

Antisera Produced Using an E. coli-Expressed SARS-CoV-2 RBD and Complemented with a Minimal Dose of Mammalian-Cell-Expressed S1 Subunit of the Spike Protein Exhibits Improved Neutralization

E. coli-expressed proteins could provide a rapid, cost-effective, and safe antigen for subunit vaccines, provided we can produce them in a properly folded form inducing neutralizing antibodies. Here, we use an E. coli-expressed SARS-CoV-2 receptor-binding domain (RBD) of the spike protein as a model to examine whether it yields neutralizing antisera with effects comparable to those generated by the S1 subunit of the spike protein (S1 or S1 subunit, thereafter) expressed in mammalian cells. We immunized 5-week-old Jcl-ICR female mice by injecting RBD (30 µg) and S1 subunit (5 µg) according to four schemes: two injections 8 weeks apart with RBD (RBD/RBD), two injections with S1 (S1/S1), one injection with RBD, and the second one with S1 (RBD/S1), and vice versa (S1/RBD). Ten weeks after the first injection (two weeks after the second injection), all combinations induced a strong immune response with IgG titer > 10⁵ (S1/RBD < S1/S1 < RBD/S1 < RBD/RBD). In addition, the neutralization effect of the antisera ranked as S1/RBD~RBD/S1 (80%) > S1/S1 (56%) > RBD/RBD (42%). These results indicate that two injections with E. coli-expressed RBD, or mammalian-cell-produced spike S1 subunit alone, can provide some protection against SARS-CoV-2, but a mixed injection scheme yields significantly higher protection.

Total hip arthroplasty in patients with vertebral compression fracture is associated with poor clinical outcomes - retrospective analysis on 453 cases

PURPOSE

Total hip arthroplasty (THA) is increasingly performed in older adults, and the prevalence of vertebral compression fracture (VCF) increases with age. We aimed to investigate the clinical outcomes of THA in patients with VCF.

METHODS

We reviewed the records of 453 patients who underwent THA at our institution between 2015 and 2021. We classified patients into those with and without VCF. VCF was identified using preoperative upright whole-spine radiographs. Spinal parameters, preoperative and 1-year postoperative clinical outcomes of the Harris hip score (HHS), Oxford hip score (OHS), and visual analog scale (VAS) for low back pain (LBP) were assessed. Furthermore, propensity score-matched cohorts for age, sex, body mass index, and spinal parameters were created, and the clinical outcomes were compared between the two groups.

RESULTS

Among the 453 patients, 51 (11.3%) with VCF and 402 without VCF were identified. Before matching, patients with VCF were older (p < 0.01), had sagittal spinal imbalance (p < 0.01), and had worse clinical outcomes pre- and postoperatively. After matching 47 patients in both groups, patients with VCF had worse HHS (p < 0.05), especially regarding support and distance walked, and worse VAS scores for LBP (p < 0.05) pre- and postoperatively. However, the improvements in scores were not significantly different between the groups.

CONCLUSIONS

HHS, especially regarding support and distance walked, and VAS scores for LBP were poorer in patients with VCF preoperatively and 1-year postoperatively. Our findings suggest that hip surgeons should evaluate not only spinal alignment but also the presence of VCF before performing THA.

LEVEL OF EVIDENCE

Level III, Retrospective cohort study.

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 antero-lateral 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 antero-lateral 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 (ALF) or without it (ALNF). 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 GMin decreased in both parts. The RD decrease of GMin was significantly lower in the ALF group than the ALNF 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 antero-lateral 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.

Evaluating the contribution of fat infiltration in anterior gluteus minimus muscle to walking ability in female with unilateral hip osteoarthritis and candidates for total hip arthroplasty

BACKGROUND

The purpose of this study is to investigate the relationship between gait and fat infiltration in anterior and posterior gluteus minimus in the patients with hip osteoarthritis.

METHODS

Ninety-one female patients who were diagnosed as the unilateral hip osteoarthritis, classified into Kellgren-Lawrence global scoring system grades 3 or 4, and candidate for total hip arthroplasty were retrospectively reviewed. The horizontally cross-sectional regions of interest for the gluteus medius and anterior and posterior gluteus minimus were manually circumscribed in a single transaxial computed tomography image and muscle density of those regions were obtained. The gait was assessed as the step and speed with the 10-Meter Walk Test. The multiple regression analysis was used to compare the step and speed with age, height, range of motion in flexion, the muscle density of anterior gluteus minimus in the affected side, and that of gluteus medius muscle in both affected and unaffected sides.

FINDINGS

Multiple regression analysis for step revealed that the muscle density of anterior gluteus minimus in the affected side and height were the independent predictors for step (R² = 0.389, p < 0.001). That for speed identified the muscle density of anterior gluteus minimus in the affected side as the only factor determining speed (R² = 0.287, p < 0.001).

INTERPRETATION

The fatty infiltration of anterior gluteus minimus muscle in affected side can be a predictor for the gait in in female with unilateral hip osteoarthritis and candidates for total hip arthroplasty.

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.

Association between Reduction of Muscle Mass and Faster Declines in Global Cognition among Older People: A 4-Year Prospective Cohort Study

OBJECTIVES

A few studies reported that both decrease and increase in body mass index (BMI) were associated with the development of dementia in later life. However, it is unclear what changes in body composition are associated with cognitive decline. This study investigated the longitudinal influences of changes in body composition on cognitive function among community-dwelling adults.

DESIGN, SETTING AND PARTICIPANTS

This longitudinal study included older adults aged ≥60 years without cognitive impairment who participated in National Institute for Longevity Sciences - Longitudinal Study of Aging.

MEASUREMENTS

Cognitive function was assessed using the MMSE. Body composition was measured by a dual-energy X-ray absorptiometry system. Then, BMI, fat mass index (FMI), fat-free mass index (FFMI), and muscle mass index (MMI) were calculated. The changes in body composition over 6 years (second wave to fifth wave) were calculated, and three groups were created: decreased group, decrease of >5%; stable group, change within 5%, and increased group, increase of >5%. In statistical analysis, a linear mixed model was applied by sex to investigate the influences of body composition changes on cognitive function over 4 years (fifth wave to seventh wave).

RESULTS

This study analyzed 515 participants (mean age, 67.05 years; 53.4% men). Men with decreased group in FFMI and MMI exhibited faster declines in MMSE scores than those with stable group (β [95% CI]: FFMI, -0.293 [-0.719 to -0.020]; MMI, -0.472 [-0.884 to -0.059]). In women, there was no significant association between body composition changes and cognitive functions.

CONCLUSIONS

Decrease in fat-free mass and muscle mass is associated with faster cognitive declines in men. These results suggest the importance of continuous monitoring of muscle mass to prevent cognitive decline in later life.

Reflecting on mutational and biophysical analysis of Gaussia princeps Luciferase from a structural perspective: a unique bioluminescent enzyme

Gaussia princeps luciferase (GLuc 18.2 kDa; 168 residues) is a marine copepod luciferase that emits a bright blue light when oxidizing coelenterazine (CTZ). GLuc is a small luciferase, attracting much attention as a potential reporter protein. However, compared to firefly and Renilla luciferases, which have been thoroughly characterized and are used in a wide range of applications, structural and biophysical studies of GLuc have been slow to appear. Here, we review the biophysical and mutational studies of GLuc's bioluminescence from a structural viewpoint, particularly in view of its recent NMR solution structure, where two homologous sequential repeats form two anti-parallel bundles, each made of four helices, grabbing a short N-terminal helix. Additionally, a long loop classified as an intrinsically disordered region separates the two bundles forming one side of a hydrophobic pocket that is most likely the binding/catalytic site. We compare the NMR-determined structure with a recent AlphaFold2 prediction. Overall, the AlphaFold2 structure was in line with the solution structure; however, it surprisingly revealed a possible, alternative conformation, where the N-terminal helix is replaced by a newly formed α helix in the C-terminal tail that is unfolded in the NMR structure. In addition, we discuss the results of previous mutational analysis focusing on a putative catalytic core identified by chemical shift perturbation analysis and molecular dynamics simulations performed using both the NMR and the AlphaFold2 structures. In particular, we discuss the role of the possible conformational change and the hydrophobic pocket in GLuc's activity. Overall, the discussion points toward GLuc's unexpected and unusual characteristics that appear to be much more flexible than traditional enzymes, resulting in a unique mode of catalysis to achieve CTZ oxidative decarboxylation.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12551-022-01025-6.

An Escherichia coli Expressed Multi-Disulfide Bonded SARS-CoV-2 RBD Shows Native-like Biophysical Properties and Elicits Neutralizing Antisera in a Mouse Model

A large-scale Escherichia coli (E. coli) production of the receptor-binding domain (RBD) of the SARS-CoV-2 could yield a versatile and low-cost antigen for a subunit vaccine. Appropriately folded antigens can potentially elicit the production of neutralizing antisera providing immune protection against the virus. However, E. coli expression using a standard protocol produces RBDs with aberrant disulfide bonds among the RBD's eight cysteines resulting in the expression of insoluble and non-native RBDs. Here, we evaluate whether E. coli expressing RBD can be used as an antigen candidate for a subunit vaccine. The expressed RBD exhibited native-like structural and biophysical properties as demonstrated by analytical RP-HPLC, circular dichroism, fluorescence, and light scattering. In addition, our E. coli expressed RBD binds to hACE2, the host cell's receptor, with a binding constant of 7.9 × 10-9 M, as indicated by biolayer interferometry analysis. Our E. coli-produced RBD elicited a high IgG titer in Jcl:ICR mice, and the RBD antisera inhibited viral growth, as demonstrated by a pseudovirus-based neutralization assay. Moreover, the increased antibody level was sustained for over 15 weeks after immunization, and a high percentage of effector and central memory T cells were generated. Overall, these results show that E. coli-expressed RBDs can elicit the production of neutralizing antisera and could potentially serve as an antigen for developing an anti-SARS-CoV-2 subunit vaccine.

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.

Biophysical analysis of Gaussia Luciferase bioluminescence mechanisms using a non-oxidizable coelenterazine

Gaussia luciferase (GLuc 18.2kDa; 168 residues) is a marine copepod luciferase that emits a bright blue light when oxidizing coelenterazine (CTZ). It is a helical protein where two homologous sequential repeats form two anti-parallel bundles, each made of four helices. We previously identified a hydrophobic cavity as a prime candidate for the catalytic site, but GLuc's fast bioluminescence reaction hampered a detailed analysis. Here, we used azacoelenterazine (Aza-CTZ), a non-oxidizable coelenterazine (CTZ) analog, as a probe to investigate its binding mode to GLuc. While analysing GLuc's activity, we unexpectedly found that salt and monovalent anions are absolutely required for Gluc's bioluminescence, which retrospectively appears reasonable for a sea-dwelling organism. The NMR-based investigation, using chemical shift perturbations monitored by ¹⁵N-¹H HSQC, suggested that Aza-CTZ (and thus unoxidized CTZ) binds to residues in or near the hydrophobic cavity. These NMR data are in line with a recent structural prediction of GLuc, hypothesizing that large structural changes occur in regions remote from the hydrophobic cavity upon the addition of CTZ. Interestingly, these results point toward a unique mode of catalysis to achieve CTZ oxidative decarboxylation.

Biophysical studies of amorphous protein aggregation and in vivo immunogenicity

Amorphous protein aggregates are oligomers that lack specific, high-order structures. Soluble amorphous aggregates are smaller than ~1 µm. Despite their lack of high-order structure, amorphous protein aggregates exhibit specific biophysical properties such as reversibility of formation, density, conformation, and biochemical stability. Our mutational analysis using a Solubility Controlling Peptide (SCP) tag strongly suggests that amorphous aggregation of small globular proteins can significantly increase in vivo immune response and that the magnitude of enhanced immune responses depends on the aggregates' biophysical and biochemical properties. We propose that SCP tags might help develop subunit (protein) adjuvant-free (immunostimulant-free) vaccines by controlling the aggregation propensity of target proteins.

Bisphosphonate use is associated with a decreased joint narrowing rate in the non-arthritic hip

Aims

The preventive effects of bisphosphonates on articular cartilage in non-arthritic joints are unclear. This study aimed to investigate the effects of oral bisphosphonates on the rate of joint space narrowing in the non-arthritic hip.

Methods

We retrospectively reviewed standing whole-leg radiographs from patients who underwent knee arthroplasties from 2012 to 2020 at our institute. Patients with previous hip surgery, Kellgren–Lawrence grade ≥ II hip osteoarthritis, hip dysplasia, or rheumatoid arthritis were excluded. The rate of hip joint space narrowing was measured in 398 patients (796 hips), and the effects of the use of bisphosphonates were examined using the multivariate regression model and the propensity score matching (1:2) model.

Results

A total of 45 of 398 (11.3%) eligible patients were taking an oral bisphosphonate at the time of knee surgery, with a mean age of 75.8 years (SD 6.2) in bisphosphonate users and 75.7 years (SD 6.8) in non-users. The mean joint space narrowing rate was 0.04 mm/year (SD 0.11) in bisphosphonate users and 0.12 mm/year (SD 0.25) in non-users (p < 0.001). In the multivariate model, age (standardized coefficient = 0.0867, p = 0.016) and the use of a bisphosphonate (standardized coefficient = −0.182, p < 0.001) were associated with the joint space narrowing rate. After successfully matching 43 bisphosphonate users and 86 non-users, the joint narrowing rate was smaller in bisphosphonate users (p < 0.001).

Conclusion

The use of bisphosphonates is associated with decreased joint degeneration in non-arthritic hips after knee arthroplasty. Bisphosphonates slow joint degeneration, thus maintaining the thickness of joint cartilage in the normal joint or during the early phase of osteoarthritis. Cite this article: Bone Joint Res 2022;11(11):826–834.

Direct Analysis of Mitochondrial Damage Caused by Misfolded/Destabilized Proteins

Protein quality control is essential for cellular homeostasis. In this study, we examined the effect of improperly folded proteins that do not form amyloid fibrils on mitochondria, which play important roles in ATP production and cell death. First, we prepared domain 3 of the dengue envelope protein in wild type and four mutants with widely different biophysical properties in misfolded/aggregated or destabilized states. The effects of the different proteins were detected using fluorescence microscopy and Western blotting, which revealed that three of the five proteins disrupted both inner and outer membrane integrity, while the other two proteins, including the wild type, did not. Next, we examined the common characteristics of the proteins that displayed toxicity against mitochondria by measuring oligomer size, molten globule-like properties, and thermal stability. The common feature of all three toxic proteins was thermal instability. Therefore, our data strongly suggest that thermally unstable proteins generated in the cytosol can cause cellular damage by coming into direct contact with mitochondria. More importantly, we revealed that this damage is not amyloid-specific.

The Impact of Spinopelvic Parameters on Hip Degeneration After Spinal Fusion

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

This study aimed to investigate the effects of spinopelvic alignment parameters after spinal fusion on the rate of joint space narrowing in nonarthritic hips.

SUMMARY OF BACKGROUND DATA

Spinal fusion affects the forces on the adjacent hip joint. Therefore, hip joint narrowing may be increased after spinal fusion surgery. However, the relationship between spinal alignment and hip degeneration remains unclarified.

METHODS

We retrospectively reviewed data from patients who underwent lumbar spinal fusion from 2011 to 2018 at our institute. Patients with hip osteoarthritis (Kellgren-Lawrence grade ≥II) or hip dysplasia were excluded. The rate of hip joint space narrowing after spinal fusion was measured in 191 patients (382 hips). We assessed the effects of the following spinopelvic alignment parameters on the joint narrowing rate: pelvic tilt, sacral slope (SS), pelvic incidence (PI), lumbar lordosis (LL), PI-LL, sagittal vertical axis, and distance between the C7 plumb line, and the central sacral vertical line (C7-CSVL).

RESULTS

The hip joint narrowing rate was greater when four or more levels were fused compared with single-level fusion. After adjusting for the effects of patient-related factors, the alignment parameters significantly associated with the hip joint narrowing rate were the PI ( P = 0.0002), SS ( P = 0.047), and PI-LL ( P = 0.0022). A subgroup analysis of patients who underwent long fusion (four or more levels combined with iliac screws) also indicated that the PI ( P = 0.013), SS ( P = 0.0054), and PI-LL ( P = 0.046) were associated with the hip joint narrowing rate.

CONCLUSION

The PI, SS, and PI-LL were associated with the progression of hip joint narrowing after spinal fusion, especially after fusion of four or more levels. Surgeons need to be aware of the risk of increased hip joint narrowing in patients with a large PI, SS, and PI-LL after fusion surgery.

Estimation of Minimum Biofilm Eradication Concentration (MBEC) on In Vivo Biofilm on Orthopedic Implants in a Rodent Femoral Infection Model

The formation of a biofilm on the implant surface is a major cause of intractable implant-associated infection. To investigate the antibiotic concentration needed to eradicate the bacteria inside a biofilm, the minimum biofilm eradication concentration (MBEC) has been used, mostly against in vitro biofilms on plastic surfaces. To produce a more clinically relevant environment, an MBEC assay against biofilms on stainless-steel implants formed in a rat femoral infection model was developed. The rats were implanted with stainless steel screws contaminated by two Staphylococcus aureus strains (UAMS-1, methicillin-sensitive Staphylococcus aureus; USA300LAC, methicillin-resistant Staphylococcus aureus) and euthanized on days 3 and 14. Implants were harvested, washed, and incubated with various concentrations (64–4096 μg/mL) of gentamicin (GM), vancomycin (VA), or cefazolin (CZ) with or without an accompanying systemic treatment dose of VA (20 μg/mL) or rifampicin (RF) (1.5 μg/mL) for 24 h. The implant was vortexed and sonicated, the biofilm was removed, and the implant was re-incubated to determine bacterial recovery. MBEC on the removed biofilm and implant was defined as in vivo MBEC and in vivo implant MBEC, respectively, and the concentrations of 100% and 60% eradication were defined as MBEC₁₀₀ and MBEC₆₀, respectively. As for in vivo MBEC, MBEC₁₀₀ of GM was 256–1024 μg/mL, but that of VA and CZ ranged from 2048–4096 μg/mL. Surprisingly, the in vivo implant MBEC was much higher, ranging from 2048 μg/mL to more than 4096 μg/mL. The addition of RF, not VA, as a secondary antibiotic was effective, and MBEC₆₀ on day 3 USA300LAC biofilm was reduced from 1024 μg/mL with GM alone to 128 μg/mL in combination with RF and the MBEC₆₀ on day 14 USA300LAC biofilm was reduced from 2048 μg/mL in GM alone to 256 μg/mL in combination with RF. In conclusion, a novel MBEC assay for in vivo biofilms on orthopedic implants was developed. GM was the most effective against both methicillin-sensitive and methicillin-resistant Staphylococcus aureus, in in vivo biofilms, and the addition of a systemic concentration of RF reduced MBEC of GM. Early initiation of treatment is desired because the required concentration of antibiotics increases with biofilm maturation.

Development of a clinical prediction rule to identify physical activity after total hip arthroplasty

OBJECTIVE

To develop clinical prediction rule (CPR) of physical activity at 1-year after total hip arthroplasty (THA).

DESIGN

Retrospective cohort study.

SETTING

University hospital with orthopedic surgery.

PARTICIPANTS

The study group included 321 patients (56 men) who underwent primary THA.

INTERVENTION

Not applicable.

MAIN OUTCOMES MEASURES

The data collected included age, body mass index, clinical score from the questionnaires, hip pain, range of motion, muscle strength, and Physical functions (10-Meter Walk Test, Timed Up and Go test and Sit-to-stand). Patients were classified into sufficient and insufficient activity groups based on their University of California, Los Angeles (UCLA) activity score 1 year after THA. Variables measured preoperatively and at 3 weeks postoperatively were analyzed using univariate and multivariate methods to derive CPR for physical activity.

RESULTS

A CPR was developed using the following five factors and cut-offs: age, ≤70.5 years; preoperative UCLA activity score, ≥3.5; preoperative hip abduction strength, ≥0.54 Nm/kg; preoperative knee extension strength, ≥1.04 Nm/kg; and 10-Meter Walk Test, ≤8.49 s at 3 weeks after surgery. The presence of four of the five factors predicted a sufficient physical activity level at 1-year, with a positive likelihood ratio of 5.94 and probability of 85.4%. The presence of five predictor variables increased the probability of sufficient physical activity after THA to 94.7%.

CONCLUSION

This study developed a CPR for physical activity at 1-year after THA. Having four or more of the five measurements were useful indicators for predicting of physical activity at 1 year postoperatively.

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.

Radiodensity measurement is feasible for evaluating fatty infiltration in hip abductors

OBJECTIVE

This retrospective study aimed to compare radiodensity measurements and Goutallier grading systems for the evaluation of fatty infiltration in hip abductors.

METHODS

The radiodensity of the gluteus minimus and medius muscles was measured in 80 hips of 40 patients. These muscles were graded for fatty infiltration using three five-grade classification systems: the original Goutallier classification on both computed tomography (CT) and magnetic resonance imaging (MRI), and a new objective classification based on the percentage of the functional muscle area (defined as 30-100 Hounsfield units). After measuring and grading the abductors, correlation coefficients between them were analyzed.

RESULTS

Spearman's rank correlation coefficients (ρ) between radiodensity measurements of abductors and the Goutallier classification on CT and MRI were -0.701 and -0.552 for the gluteus minimus and -0.832 and -0.740 for the gluteus medius, respectively. Our new classification had correlation coefficients of -0.844 and -0.926 for the gluteus minimus and gluteus medius, respectively.

CONCLUSIONS

Radiodensity measurements showed a strong correlation with the grading systems, particularly with the new classification based on the percentage of the functional muscle area. Considering the subjective nature of the original Goutallier grading systems, we conclude that radiodensity assessment is feasible and more objective for evaluating fatty infiltration in hip abductors.

The superior accuracy of a novel method in total hip wear calculations following radiographic measurement

Background

Polyethylene wear is one of the major concerns of orthopedic surgeons. However, there is no standardized calculation method for the wear rate following radiographic measurement. The purpose of this study was to propose a novel method of wear calculation and to compare its accuracy with a representative conventional method.

Methods

Relative position of the center of the femoral head to that of the cup progresses in one direction following arthroplasty surgery because of bedding-in and wear. We predetermined the amount of bedding-in, wear rate, and random error in measuring the head center position in a 2-dimensional plane. We calculated the wear rate using the head center coordinates over a certain number of measurement periods using a representative conventional method and our novel method. The conventional method consisted of transforming vector data into scalars and conducting a least-squares method. The least-squares method was directly applied to each component of the vector in the novel method. We evaluated the accuracy of these methods by comparing the expected value for the wear rate with their predetermined true values.

Results

If the error were limited to being random, the novel method could provide the predetermined wear rate as the calculation result. However, the conventional method could not.

Conclusion

We recommend using the novel method for the wear calculation rather than the conventional method because of its mathematical accuracy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04964-5.

Wear resistance of first-generation highly cross-linked annealed polyethylene in cementless total hip arthroplasty is maintained 20 years after surgery

AIMS

The aim of this study was to evaluate the performance of first-generation annealed highly cross-linked polyethylene (HXLPE) in cementless total hip arthroplasty (THA).

METHODS

We retrospectively evaluated 29 patients (35 hips) who underwent THA between December 2000 and February 2002. The survival rate was estimated using the Kaplan-Meier method. Hip joint function was evaluated using the Japanese Orthopaedic Association (JOA) score. Two-dimensional polyethylene wear was estimated using Martell's Hip Analysis Suite. We calculated the wear rates between years 1 and 5, 5 and 10, 10 and 15, and 15 and final follow-up.

RESULTS

The mean follow-up period was 19.1 years (SD 0.6; 17.3 to 20.1). The 19-year overall survival rate with the end point of all-cause revision was 97.0% (95% confidence interval (CI) 91 to 100). The mean JOA score improved from 43.2 (SD 10.6; 30 to 76) before surgery to 90.2 (SD 6.4; 76 to 98) at the final follow-up (p < 0.001). There was no osteolysis or loosening of the acetabular or femoral components. The overall steady-state wear rate was 0.013 mm/year (SD 0.012). There was no hip with a steady-state wear rate of > 0.1 mm/year. There was no significant difference in wear rates for each period. We found no significant correlation between the wear rate and age, body weight, BMI, or cup inclination.

CONCLUSION

First-generation annealed HXLPE shows excellent wear resistance and no acceleration of wear for approximately 20 years, with low all-cause revision rates. Cite this article: Bone Joint J 2022;104-B(2):200-205.

Discrepancy in the Responsiveness to Hip Range of Motion Between Harris and Oxford Hip Scores

Background

The primary objectives of total hip arthroplasty (THA) include mobility improvement and pain relief; however, the correlation between hip range of motion (ROM) and function remains unclear. We aimed to explore how ROM affects hip functions after THA and compare the responsiveness of each component of the modified Harris Hip Score (mHHS) and Oxford Hip Score (OHS) to preoperative and postoperative ROM.

Methods

This prospective observational study involved 120 patients who underwent unilateral THA. Univariate regression analyses were performed using the University of California Los Angeles activity score and mHHS and OHS to determine the effects of preoperative and postoperative flex ROM on clinical scores at 12 months. Multivariate regressions were performed to adjust for the confounding effects of patient factors: age, sex, body mass index, and diagnosis.

Results

A larger preoperative flexion ROM was associated with a higher score in the mHHS socks component (standardized coefficient [SC] = 0.26, P = .0041) at 12 months; the effect on the OHS socks component was not significant (P = .34). A larger flexion ROM at 12 months was associated with higher scores in the mHHS support (SC = 0.21, P = .026), stairs (SC = 0.35, P = .0002), and socks (SC = 0.32, P = .0007) components but had no significant effect on any OHS component. The effects of ROM on University of California Los Angeles activity score were limited.

Conclusions

A discrepancy was noted in the responsiveness to ROM between the two major measurement tools; this difference might be because mHHS and OHS are surgeon- and patient-administered questionnaires, respectively. This discrepancy also suggests that the patients have higher satisfaction than that assumed by the surgeons.

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.

Blocking PSD95-PDZ3's amyloidogenesis through point mutations that inhibit high-temperature reversible oligomerization (RO)

The third PDZ domain of postsynaptic density protein 95 (PSD95-PDZ3; 11 kDa, 103 residues) has a propensity to form amyloid fibrils at high temperatures. At neutral pH, wild type PDZ3 is natively folded, but it exhibits a peculiar three-state thermal unfolding with a reversible oligomerization (RO) equilibrium at high temperatures, which is uncharacteristic in the unfolding of small globular protein as PDZ3 is. Here, we examined RO's role in PDZ3's amyloidogenesis at high-temperature using two variants (F340A and L342A) that suppress the high-temperature RO and five single-alanine-mutated variants, where we mutated surface-exposed hydrophobic residues to alanine. Circular Dichroism (CD), Analytical Ultracentrifuge (AUC), and other spectroscopic measurements confirmed the retention of the native structure at ambient temperature. Differential Scanning Calorimetry (DSC) was used to assess the presence or absence of the high-temperature RO, and the amyloidogenicity of the variants was measured by Thioflavin T (ThT) fluorescence and Transmission Electron Microscopy (TEM). By comparing the fraction of RO and the ThT signal, we found that mutations that suppressed the high-temperature RO strongly inhibited amyloidogenesis. On the other hand, all variants forming RO also formed amyloids under the same conditions as the wild type PDZ3.

Early Breakage of All Proximal Locking Compression Screws under Non-weight-bearing Conditions after Derotational Femoral Osteotomy in a Child with Cerebral Palsy: A Case Report

INTRODUCTION

The locking compression plate (LCP) system for pediatric hips has improved fixation and angular stability. Herein, we report a rare case in which all proximal locking compression screws were broken before weight bearing in the early post-operative period after derotational femoral osteotomy in a child with spastic cerebral palsy (CP).

CASE REPORT

Derotational femoral osteotomy was performed using a LCP system for a 9-year-old boy with spastic CP to correct excessive femoral anteversion, causing unstable toe-in gait. Proximal screw breakage was found 2 weeks postoperatively during hip-spica casting under non-weight-bearing conditions. Implant breakage was considered a result of the excessive spasticity of the lower limb. At the time of reoperation, shortening and varus correction of the femur and muscle tendon release were performed in addition to the refixation of the osteotomy. Intensive pain control was ensured, and anti-spastic medication and botulinum toxin injection were administered. Complete bone healing was successfully achieved 6 months after the second surgery.

CONCLUSION

Surgeons need to consider the spasticity of the lower limb as a cause of implant failure. Management to reduce spasticity and mechanical load to the implant is important for preventing implant failures in patients with spastic CP.

Functional characteristics associated with hip abductor torque in severe hip osteoarthritis

BACKGROUND

Hip abductor weakness due to the progression of hip osteoarthritis (OA) commonly causes poor functional mobility. The hip abductor strength has also been identified as a clinically relevant factor for successful functional outcomes after total hip arthroplasty.

OBJECTIVES

This study aimed to examine the functional characteristics related to hip abductor torque in patients with hip OA.

DESIGN

A cross-sectional survey study.

METHODS

One hundred and eight female patients with severe unilateral hip OA participated in this study. Hip abductor torque and pain were measured. The muscle cross-sectional area (CSA) and skeletal muscle density (SMD) of the gluteal muscles were also measured using computed tomography. To identify the hip parameters associated with hip abductor torque, multiple regression analysis was performed. The healthy model included the CSA and SMD of gluteus maximus, gluteus medius, and gluteus minimus; range of motion in hip abduction; age; and body mass index. The affected model included hip pain in addition to the healthy model.

RESULTS

In the affected limb, multiple regression analysis identified pain and angle of hip abduction as factors that determine hip abductor torque (Adjusted R² = 0.39). In contrast, our analysis identified CSA and SMD of the gluteus medius and SMD of the gluteus minimus as the significant variables related to hip abductor torque in the healthy limb (Adjusted R² = 0.40).

CONCLUSION

The findings of this study indicated that it is necessary to consider that hip pain may inhibit muscle exertion and contraction while training to improve the hip abductor torque in the affected limb.

Radiolucent lines do not affect the longevity of highly cross-linked polyethylene cemented components in total hip arthroplasty

AIMS

We aimed to evaluate the long-term outcome of highly cross-linked polyethylene (HXLPE) cemented acetabular components and assess whether any radiolucent lines (RLLs) which arose were progressive.

METHODS

We retrospectively reviewed 170 patients who underwent 187 total hip arthroplasties at two hospitals with a minimum follow-up of ten years. All interventions were performed using the same combination of HXLPE cemented acetabular components with femoral stems made of titanium alloy. Kaplan-Meier survival analysis was performed for the primary endpoint of acetabular component revision surgery for any reason and secondary endpoint of the appearance of RLLs. RLLs that had appeared once were observed over time. We statistically assessed potential relationships between RLLs and a number of factors, including the technique of femoral head autografting and the Japanese Orthopaedic Association score.

RESULTS

The mean follow-up period was 13.0 years (10.0 to 16.3). Femoral head autografting was performed on 135 hips (72.2%). One acetabular component was retrieved because of deep infection. No revision was performed for the aseptic acetabular loosening. The Kaplan-Meier survival curve for the primary and secondary endpoints were 98.2% (95% confidence interval (CI) 88.6% to 99.8%) and 79.3% (95% CI 72.8% to 84.6%), respectively. RLLs were detected in 38 hips (21.2%), at a mean of 1.7 years (1 month to 6 years) postoperatively. None of the RLLs were progressive, and the presence of RLLs did not show a significant association with the survival and clinical score. RLLs were more frequently observed in hips without femoral head autografts than in those with autografts.

CONCLUSION

The use of HXLPE cemented acetabular components in total hip arthroplasty demonstrated excellent clinical outcomes after ten years, and no RLLs were progressive, and their presence did not affect the outcome. Femoral head autografting did not negatively impact the acetabular component survival or the appearance of RLLs. Cite this article: Bone Joint J 2021;103-B(10):1604-1610.

Assessment of prediction methods for protein structures determined by NMR in CASP14: Impact of AlphaFold2

NMR studies can provide unique information about protein conformations in solution. In CASP14, three reference structures provided by solution NMR methods were available (T1027, T1029, and T1055), as well as a fourth data set of NMR‐derived contacts for an integral membrane protein (T1088). For the three targets with NMR‐based structures, the best prediction results ranged from very good (GDT_TS = 0.90, for T1055) to poor (GDT_TS = 0.47, for T1029). We explored the basis of these results by comparing all CASP14 prediction models against experimental NMR data. For T1027, NMR data reveal extensive internal dynamics, presenting a unique challenge for protein structure prediction methods. The analysis of T1029 motivated exploration of a novel method of “inverse structure determination,” in which an AlphaFold2 model was used to guide NMR data analysis. NMR data provided to CASP predictor groups for target T1088, a 238‐residue integral membrane porin, was also used to assess several NMR‐assisted prediction methods. Most groups involved in this exercise generated similar beta‐barrel models, with good agreement with the experimental data. However, as was also observed in CASP13, some pure prediction groups that did not use any NMR data generated models for T1088 that better fit the NMR data than the models generated using these experimental data. These results demonstrate the remarkable power of modern methods to predict structures of proteins with accuracies rivaling solution NMR structures, and that it is now possible to reliably use prediction models to guide and complement experimental NMR data analysis.

Femoral head collapse rate among Japanese patients with pre-collapse osteonecrosis of the femoral head

Objective

In this study, we aimed to elucidate the relationship between the duration from diagnosis to femoral head collapse and the collapse rate among patients with pre-collapse osteonecrosis of the femoral head (ONFH).

Methods

In this retrospective, observational, multicenter study, we analyzed 268 patients diagnosed with ONFH and classified them using the Japanese Investigation Committee classification. The primary endpoint was duration from the time of diagnosis to femoral head collapse for each type of ONFH.

Results

The 12-, 24-, and 36-month collapse rates among participants were 0%, 0%, and 0% for type A, respectively; 0%, 2.0%, and 10.8% for type B, respectively; 25.5%, 40.8%, and 48.5% for type C-1, respectively; and 57.4%, 70.3%, and 76.7% for type C-2 ONFH, respectively. A comparison of unilateral and bilateral ONFH, using Kaplan–Meier survival curves demonstrated similar collapse rates.

Conclusions

The lowest collapse rate was observed for ONFH type A, followed by types B, C-1, and C-2. Additionally, a direct association was observed between the collapse rate and location of the osteonecrotic lesion on the weight-bearing surface.

Combined landscape of single-nucleotide variants and copy number alterations in clonal hematopoiesis

Clonal hematopoiesis (CH) in apparently healthy individuals is implicated in the development of hematological malignancies (HM) and cardiovascular diseases. Previous studies of CH analyzed either single-nucleotide variants and indels (SNVs/indels) or copy number alterations (CNAs), but not both. Here, using a combination of targeted sequencing of 23 CH-related genes and array-based CNA detection of blood-derived DNA, we have delineated the landscape of CH-related SNVs/indels and CNAs in 11,234 individuals without HM from the BioBank Japan cohort, including 672 individuals with subsequent HM development, and studied the effects of these somatic alterations on mortality from HM and cardiovascular disease, as well as on hematological and cardiovascular phenotypes. The total number of both types of CH-related lesions and their clone size positively correlated with blood count abnormalities and mortality from HM. CH-related SNVs/indels and CNAs exhibited statistically significant co-occurrence in the same individuals. In particular, co-occurrence of SNVs/indels and CNAs affecting DNMT3A, TET2, JAK2 and TP53 resulted in biallelic alterations of these genes and was associated with higher HM mortality. Co-occurrence of SNVs/indels and CNAs also modulated risks for cardiovascular mortality. These findings highlight the importance of detecting both SNVs/indels and CNAs in the evaluation of CH.

Similarity in Sequential Bilateral Transient Osteoporosis of the Hip: A Report of 3 Cases

CASE

Three middle-aged men with habitual drinking developed unilateral hip pain and were referred for osteonecrosis of the femoral head (ONFH). Radiographs showed osteopenia, and magnetic resonance imaging (MRI) showed diffuse bone marrow edema (BME). After several months, the patients' symptoms resolved and radiographic images normalized. More than 6 months later, the contralateral side showed the same clinical course.

CONCLUSION

Transient osteoporosis of the hip (TOH) resembles ONFH but heals spontaneously. We report 3 rare cases of sequential TOH, similar in that they occurred in middle-aged male habitual drinkers at risk for ONFH, characterized by diffuse BME on MRI and radiographic resolution.

Solubility Controlling Peptide Tags of Opposite Charges Generate a Bivalent Immune Response Against Dengue ED3 Serotypes 3 and 4

We previously demonstrated that a protein’s immunogenicity could be substantially increased by attaching a hydrophobic solubility controlling peptide tag (SCP-tag) producing small sub-visible aggregates. Here, we report the oligomerization of Dengue envelop protein domain 3 (ED3), and consequently, its immunogenicity increase by mixing ED3s attached with SCP-tags of opposite charges at equimolar concentration. We used ED3 of serotype 3 (D3ED3) and serotype 4 (D4ED3), which are, respectively, moderately and poorly immunogenic, and their SCP tagged variants constructed by attaching either a C-termini 5-Aspartic acid (C5D) or a 5-Lysine (C5K) tag. Light scattering indicated that the isolated tagged ED3s remained monomeric, but mixing the C5D and C5K tagged ED3s at equimolar concentration generated sub-visible aggregates or oligomers of ~500 nm through electrostatic interaction. In addition, the oligomerized ED3s remained in a native-like state, as assessed by fluorescence spectroscopy and circular dichroism. The in vivo immunogenicity of the D3ED3 and D4ED3 oligomers generated by the charged tags increased by 5 and 16 fold, respectively. Furthermore, injection of heterotypic ED3 oligomers (D3C5D+D4C5K) induced an immune response against both D3ED3 and D4ED3 in 3 of 4 responsive mice, and the IgG titer of the bivalent anti-D3C5D-D4C5K sera was over 100 times higher than that generated by co-injecting the untagged D3ED3 and D4ED3 (D3+D4). Altogether, these observations suggest that SCP-tags could be used as a platform for producing a long-sought tetravalent dengue vaccine.

Development of an application tool to support returnees in Fukushima

To promote radiation protection and health promotion among returning residents (returnees) in coastal areas of Fukushima, eHealth principles were used to develop a new application tool (app) that can record radiation exposure and health status while providing comprehensive support to returnees. Intended users are returnees and health and welfare workers. After assessing their needs, a flowchart and prototype for operational logic were created using commercially available software tools. Professional developers will focus on improving the user interface and ensuring data security. The finished app will be compatible with mobile telephones and tablets. Utility and ease of use are paramount to serve returnees of all ages effectively.

Number of Levels of Spinal Fusion Associated with the Rate of Joint-Space Narrowing in the Hip

BACKGROUND

Fusion of a joint reportedly increases force in the adjacent joints and leads to progression of arthritis. Whether lumbar spinal fusion increases force in the hip joint and promotes wear of the joint space is unclear. The purpose of this study was to evaluate the rate of joint-space narrowing in the hip following spinal fusion and to examine the effects of the number of levels fused on the joint-narrowing rate.

METHODS

We retrospectively reviewed data for patients who underwent lumbar spinal fusion from 2011 to 2018 at our institute. Patients with a previous hip surgery, Kellgren-Lawrence grade ≥II hip osteoarthritis, hip dysplasia, and rheumatoid arthritis were excluded. The rate of joint-space narrowing in the hip was measured in 205 eligible patients (410 hips) following spinal fusion, and the effects of sex, age, body mass index, indication for spinal fusion, laterality, sacral fixation, and number of levels fused on the narrowing rate were examined.

RESULTS

The rate of joint-space narrowing for all patients was 0.114 ± 0.168 mm/year. The narrowing rate for single-level fusion was 0.062 ± 0.087 mm/year, whereas that for fusion of ≥7 levels was 0.307 ± 0.254 mm/year. In the multivariate regression analysis, only the length of fusion (standardized coefficient [SC] = 0.374, p < 0.0001) was associated with an increased narrowing rate. When the narrowing rate was normalized by height, female sex was another risk factor for increased narrowing (SC = 0.109, p = 0.023). Secondary regression modeling performed with patients who underwent spinal fusion for degenerative disc disease showed that the length of fusion (SC = 0.454, p < 0.0001) and female sex (SC = 0.138, p = 0.033) were associated with increased joint-space narrowing.

CONCLUSIONS

Longer spinal fusion was associated with the progression of hip joint narrowing following spinal fusion. Surgeons should be aware of the possible increased risk of hip degeneration following spinal fusion and should inform patients of this risk.

LEVEL OF EVIDENCE

Level III. See Instructions for Authors for a complete description of levels of evidence.