Ultrasonographic Changes of the Knee Joint Reflect Symptoms of Early Knee Osteoarthritis in General Population; The Nagahama Study.

OBJECTIVE: Radiographic changes in knee osteoarthritis (OA) are not always associated with symptoms, especially in its early stages. Ultrasonography (US) can detect early changes in the knee joint, but the changes that reflect symptoms have not been fully elucidated. This study aimed to identify US-detectable changes in the knee that are often associated with knee symptoms and demonstrate the feasibility of early diagnosis in symptomatic knee OA using US. DESIGN: In this cross-sectional community-based study, 1,667 participants aged ≥60 years (1,103 women [66%]) were included. All participants concurrently underwent US and radiography of the knee and completed the Knee Society Knee Scoring System (KSS) questionnaire. Simple and multiple regression analyses were used to examine the associations between US findings and KSS symptom subscales. RESULTS: Among all participants, medial meniscus protrusion and medial osteophytes, age, and body mass index showed significant associations with KSS symptom scores. Among 894 participants with Kellgren-Lawrence (KL) grade ≤1, medial osteophytes and age were significantly associated with KSS symptom score. US measures were more related to KSS symptoms than KL grades. CONCLUSIONS: Among the knee US-detectable changes, medial osteophytes were strongly associated with knee symptoms. Osteophytes are reliable predictors of symptomatic early knee OA, even in participants with few radiographic OA changes.

Tenderness of the knee is associated with thinning of the articular cartilage evaluated with ultrasonography in a community-based cohort: The Nagahama study.

OBJECTIVES: This study aimed to elucidate the association between joint line tenderness (JLT) of the knee and knee joint structural changes evaluated with ultrasonography (US) for the early diagnosis of knee osteoarthritis (KOA). METHODS: This cross-sectional study included 121 participants (age 71.7 ± 5.8 years, 75 women) from a community-based population. Bilateral structural changes in the knee joint were evaluated with US, and the presence or absence of JLT was evaluated using a pressure algometer. Logistic regression analysis was performed to evaluate the odds ratios (ORs) of US findings for the presence of JLT. Moreover, when the analysis was limited to knees with pre-/early radiographic KOA, the ORs were also calculated using logistic regression analysis. RESULTS: Among the 242 knees, 38 had medial JLT, which was significantly associated with female sex (OR 11.87) and loss of cartilage thickness of the distal medial femoral condyle (CTh-MFC) (OR 0.12). Among 96 knees with Kellgren-Lawrence grade ≤ 2, 18 knees had medial JLT, which was also significantly associated with loss of CTh-MFC (OR 0.07) and medial osteophytes (OR 2.01). CONCLUSIONS: JLT is significantly associated with thinning of the femoral cartilage and larger osteophytes in elderly patients, even in those with pre-/early radiographic KOA.

Differential Contribution of the Medial and the Lateral Side of the Joint to Symptoms in Knee Osteoarthritis: A Radiographic and Laboratory Analysis in the Nagahama Study.

OBJECTIVE: This cross-sectional study aimed to explore the differences of the medial and lateral sides of the knee joint and precise radiographic abnormalities in contribution to the knee pain and clinical outcomes. DESIGN: Participants 60 years or older who underwent radiographic evaluation were included. Knee radiography was assessed using grading systems of the Osteoarthritis Research Society International (OARSI) atlas. The Japanese Knee Osteoarthritis Measure (JKOM) was evaluated as clinical outcomes. Serum high-sensitivity C-reactive protein (hsCRP) was used to evaluate systemic inflammation. We divided the participants into normal, medial-, lateral-, and medial & lateral-OA types and compared their JKOM using an analysis of covariance. Furthermore, we analyzed the relationship between the knee pain and stiffness of JKOM and the grading of each radiographic feature using a multiple regression model. RESULTS: Lateral- and medial & lateral-OA groups had a significantly worse symptoms in the total and the pain score, especially in movement subscales, in JKOM score. Lateral-OA groups had higher hsCRP than medial-OA group. Multivariate analysis showed that medial joint space narrowing (JSN), and lateral femoral and tibial osteophytes significantly affected knee pain (adjusted odds ratios: 1.73, 1.28, and 1.55, respectively). The radiographic changes are associated with pain more in JSN in the medial side and osteophytes in the lateral side. CONCLUSION: Lateral- and medial & lateral-OA groups showed worth symptom. In addition, medial JSN and lateral osteophytes have potent effects on the knee pain.

Titania-Containing Bone Cement Shows Excellent Osteoconductivity in a Synovial Fluid Environment and Bone-Bonding Strength in Osteoporosis.

Titania bone cement (TBC) reportedly has excellent in vivo bioactivity, yet its osteoconductivity in synovial fluid environments and bone-bonding ability in osteoporosis have not previously been investigated. We aimed to compare the osteoconductivity of two types of cement in a synovial fluid environment and determine their bone-bonding ability in osteoporosis. We implanted TBC and commercial polymethylmethacrylate bone cement (PBC) into rabbit femoral condyles and exposed them to synovial fluid pressure. Rabbits were then euthanized at 6, 12, and 26 weeks, and affinity indices were measured to evaluate osteoconductivity. We generated a rabbit model of osteoporosis through bilateral ovariectomy (OVX) and an 8-week treatment with methylprednisolone sodium succinate (PSL). Pre-hardened TBC and PBC were implanted into the femoral diaphysis of the rabbits in the sham control and OVX + PSL groups. Affinity indices were significantly higher for TBC than for PBC at 12 weeks (40.9 ± 16.8% versus 24.5 ± 9.02%) and 26 weeks (40.2 ± 12.7% versus 21.2 ± 14.2%). The interfacial shear strength was significantly higher for TBC than for PBC at 6 weeks (3.69 ± 1.89 N/mm2 versus 1.71 ± 1.23 N/mm2) in the OVX + PSL group. These results indicate that TBC is a promising bioactive bone cement for prosthesis fixation in total knee arthroplasty, especially for osteoporosis patients.

In vitro study of antibacterial and osteogenic activity of titanium metal releasing strontium and silver ions.

Peri-prosthetic infection and loosening of implants are major problems in orthopaedic and dental surgery. To address these issues, surface treatment methods for titanium implants have been improved by modifying the alkali and heat treatment. We have previously fabricated calcium-treated Ti metal that releases Sr ions (CaSr-Ti), which resulted in a higher in vitro osteogenic response and early in vivo bone bonding.Further, we developed a Ti metal that released both Sr and Ag ions (CaSrAg-Ti). In this study, we evaluated the antibacterial ability and osteogenic cellular response of CaSrAg-Ti and CaSr-Ti in vitro using rat bone marrow stromal cells (BMSCs) cultured on implant samples and extract mediums (EMs) made by immersing the implant samples in the medium. CaSrAg-Ti did not show cytotoxicity and was associated with a slightly higher osteogenic response when compared to CaSr-Ti, without inhibiting the effect of Sr. The osteogenic response was also observed in the cells cultured with the CaSrAg-Ti EM; however, the response was not as high as that of the cells on the CaSrAg-Ti implant sample. Significantly higher antibacterial activity was observed along with an antibacterial efficacy of more than 95% against methicillin-susceptible Staphylococcus aureus and Escherichia coli. The main advantages of our surface treatment are its simplicity and low cost. Therefore, our treatment is promising for clinical applications in orthopaedic or dental Ti-based implants with antibacterial and early bone-bonding abilities.

Bioactivity and antibacterial activity of strontium and silver ion releasing titanium.

To overcome problems associated with loosening of orthopedic implants and surgical site infections, we developed a novel, titanium (Ti)-based material that releases both strontium and silver ions (CaSrAg-Ti) based on alkali-and-heat treatment. The results of commercially pure Ti (cp-Ti), Ti that releases Sr ions only (CaSr-Ti), and the novel CaSrAg-Ti material were compared. Mechanical tests were performed to evaluate the in vivo bonding properties of CaSrAg-Ti and the bone-implant contact (BIC) ratio in histological specimens was determined at 4 and 8 weeks after implantation in a rat femur. Also, the in vitro antibacterial activities of this material against methicillin-susceptible Staphylococcus aureus (MSSA) were evaluated after a 24 h incubation period by assaying colony-forming units. In addition, antibacterial activities were evaluated in vivo at 7 days after implantation in a rat subcutaneous pocket model. There was direct contact between the bone and CaSrAg-Ti in histological specimens and no apparent signs of argyrosis in any rat. The bone-bonding strength and the BIC ratio were increased by 2.7- and 2.3-fold for CaSrAg-Ti vs. cp-Ti at 4 weeks and 2.2- and 2.0-fold at 8 weeks, respectively. As compared with cp-Ti, the number of viable MSSA remaining on CaSrAg-Ti was reduced by 100 ± 0% in vitro and 94.2 ± 6.9% in vivo. Ti that releases Sr and Ag ions is a promising material that exhibits both bone-bonding properties and anti-MSSA activities.

Obesity with radiological changes or depression was associated with worse knee outcome in general population: a cluster analysis in the Nagahama study.

BACKGROUND: In knee osteoarthritis (OA), pain is the most frequent and dominant symptom. However, which factors other than radiological changes contribute to the symptoms is unresolved. The aims of this study were to identify factors affecting knee pain from various variables with radiological changes taken into count and exploratively examine what subgroups or phenotype could be identified by cluster analysis using the identified knee pain factors. METHODS: Patients 60 years or older who underwent radiographic evaluation were included in this cross-sectional study, and those subjects who completed a questionnaire about knee symptoms without missing data were eligible for analysis. Multiple regression analysis was used to examine the associations between selected variables and The Japanese Knee Osteoarthritis Measure (JKOM) pain score. We grouped the subjects by cluster analysis using identified variables. RESULTS: Two thousand five hundred forty-two subjects were included in the full set of analyses. Age, body mass index (BMI), radiological grade, bone mineral density (BMD), and high-sensitivity C-reactive protein (hs-CRP) showed a statistically significant correlation with radiological showing the strongest value. For dichotomous variable, presence of depression showed a statistically significant result. We used BMI, radiological grade, BMD, hs-CRP, and presence of depression as a variable for cluster analysis and identified six subgroups: (1) minimal joint disease subgroup, (2) male and high BMD subgroup, (3) high CRP subgroup, (4) severe radiological OA subgroup, (5) depressive subgroup, and (6) moderate radiological OA with high BMI subgroup, showing the worst knee outcome. CONCLUSION: This study identified the factors affecting knee pain other than radiological changes and identified six subgroups of knee outcome in the general population. The results showed that obesity with radiological changes or depression was associated with worse knee outcome.

Bioactive effects of strontium loading on micro/nano surface Ti6Al4V components fabricated by selective laser melting.

Selective laser melting (SLM) titanium alloys require surface modification to achieve early bone-bonding. This study investigated the effects of solution and heat treatment to induce the sustained release of strontium (Sr) ions from SLM Ti6Al4V implants (Sr-S64). The results were compared with a control group comprising an untreated surface [SLM pure titanium (STi) and SLM Ti6Al4V (S64)] and a treated surface to induce the release of calcium (Ca) ions from SLM Ti6Al4V (Ca-S64). The surface-treated materials showed homogenous nanoscale network formation on the original micro-topographical surface and formed bone-like apatite on the surface in a simulated body fluid within 3 days. In vitro evaluation using MC3T3-E1 cells showed that the cells were viable on Sr-S64 surface, and Sr-S64 enhanced cell adhesion-related and osteogenic differentiation-related genes expression. In vivo rabbit tibia model, Sr-S64 provided significantly greater bone-bonding strength and bone-implant contact area than those in controls (STi and S64) in the early phase (2-4 weeks) after implantation; however, there was no statistical difference between Ca-S64 and controls. In conclusion, Sr solution and heat treatment was a safe and effective method to enhance early bone-bonding ability of S-64 by improving the surface characteristics and sustained delivery for Sr.

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

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

Low back pain precedes the development of new knee pain in the elderly population; a novel predictive score from a longitudinal cohort study.

BACKGROUND: To investigate the association between knee pain and risk factors including low back pain and to develop a score to predict new knee pain in an older population, using population-based longitudinal cohort data. METHODS: We collected a questionnaire on self-reported knee pain and demographic data in a systematic manner from community residents aged ≥ 50 years twice, at baseline, and after 5 years. Multivariate logistic regression analyses were performed to investigate the association between knee pain and risk factors and to build a predictive model that would enable calculation of the risk of the development of knee pain within 5 years. The model is presented in the form of score charts. RESULTS: A total of 5932 residents aged ≥ 50 years from the cohort of 9764 that completed the first questionnaire were enrolled in the second survey. After exclusions, paired data for the two time points an average of 5.4 years apart were analyzed for 4638 participants. Multivariate analyses showed older age, female sex, higher BMI, weight increase, lower mental health score, and higher back pain/disability score were independent risk factors for knee pain. The predictive score comprised six factors: age, sex, BMI, weight increase, mental health, and low back pain/disability. The risk of developing knee pain ranged from 11.0 to 63.2% depending on the total score. CONCLUSION: This study demonstrated a significant association between knee and low back pain/disability along with other risk factors. The score we developed can be used to identify a population without any imaging modality who are at high risk of developing knee pain.

In vivo and in vitro bioactivity of a "precursor of apatite" treatment on polyetheretherketone.

We recently developed a surface treatment, "precursor of apatite" (PrA), for polyetheretherketone (PrA-PEEK) via a simple, low-temperature process aiming to achieve stronger and faster adhesion to bone. The treatment involves three steps: H2SO4 immersion, exposure to O2 plasma discharge, and alkaline simulated body fluid (alkaline SBF) treatment. This method produces homogeneous fine particles of amorphous calcium phosphate on the PEEK, and we confirmed that PrA-PEEK had excellent apatite formation ability in an SBF immersion test. In the present study using PEEK implants in rabbit tibia, mechanical tests, and histological and radiological analyses revealed that PrA provided the PEEK substrate with excellent bone-bonding properties and osteo-conductivity at early stages (4 and 8 weeks), extending to 16 weeks. In vitro study using MC3T3-E1 cells revealed via XTT assay that PrA on the PEEK substrate resulted in no cytotoxicity, though PrA treatment seemed to suppress gene expression of integrin ß-1 and Alp after 7-day incubation as shown by real-time PCR. On the whole, PrA treatment succeeded in giving in vivo bone-bonding properties to the PEEK substrate, and the treatment is a safe and promising method that can be applied in clinical settings. There was an inconsistency between in vivo and in vitro bioactivity, and this discrepancy indicated that apatite formation does not always need activation of osteoblasts at very early stage and that optimal conditions at cell and organism level may be different. STATEMENT OF SIGNIFICANCE: Polyetheretherketone (PEEK) is an attractive engineering polymer used for spine and dental surgery. To further improve clinical outcome of PEEK-based materials, we developed "Precursor of apatite" (PrA) treatment on the PEEK surface to confer bone-bonding properties. The advantages of this treatment are that it does not require high-temperature processing or special chemicals, and it is inexpensive. The present study clarified excellent in vivo bone-bonding property of PrA treatment. In addition, the results revealed important insights indicating that optimal conditions, especially wettability and crystallinity in calcium phosphate, differ at cell and organism levels. Moreover, our results indicated that prediction of in vivo bioactivity should be done in combination with multiple in vitro tests.

Titania-containing bioactive bone cement for total hip arthroplasty in dogs.

We developed a composite cement containing low-content bioactive titania fillers dispersed among specific polymethylmethacrylate (PMMA) polymers and investigated the mechanical properties and bioactivity of this titania bone cement (TBC) under load-bearing conditions in cemented total hip arthroplasty (THA) in adult female beagles. TBC and PMMA bone cement (PBC) were compared using custom-made prostheses. The dogs were killed 1, 3, 6, and 12 months postoperatively. The acetabulum was harvested to evaluate the osteoconductivity of the cement, whereas the femur was harvested for the push-out test and histological analyses. The compressive strength of TBC was significantly higher than that of PBC (p < 0.001), whereas the flexural and tensile strengths, as well as fracture toughness, were equivalent. The bonding strength values for TBC and PBC were 72.9 and 58.0 N/mm at 1 month, 69.4 and 57.2 N/mm at 3 months, 106.1 and 85.0 N/mm at 6 months, and 114.3 and 100.7 N/mm at 12 months, respectively. Histologically, TBC was in direct contact with bone without intervening with fibrous tissue over larger areas and newly formed bone was observed along the cement. The excellent mechanical properties and apparent bioactivity of this novel bone cement indicate its potential utility in clinical practice. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1238-1245, 2019.

A long-term comparative study between two different designs of cemented stems: Distal-cylindrical versus distal-taper.

INTRODUCTION: The aim of this study was to calculate the wear rate of highly cross-linked polyethylene (HXLPE) and investigate long-term clinical and radiographic outcomes related to two femoral stem designs, the distal-cylindrical (DC) and distal-taper (DT) stems. MATERIALS AND METHODS: Outcomes for the DC and DT stems were evaluated in 110 patients, who underwent total hip arthroplasty using an HXLPE socket, over a 5-year follow-up period. There were 56 hips (53 patients) in the DC group and 60 hips (57 patients) in the DT group. Clinical outcomes were measured using the Japanese Orthopaedic Association (JOA) score and radiographic changes. Polyethylene wear rate was calculated using a computer software. RESULTS: The mean follow-up period was 135.7 and 124.0 months for the DC and DT groups, respectively. Both stem designs improved hip function. On radiographic assessment, osteolysis around the tip of the stem was more frequent in the DC than in the DT group. Three cases of aseptic loosening of the stem were identified in the DC group, and no cases were identified in the DT group. The 10-year stem survival, using aseptic loosening as the primary endpoint, was 94.1% and 100% for the DC and DT groups, respectively (p = 0.06). The polyethylene wear rate was comparable for both stem groups. CONCLUSION: Better clinical outcomes were obtained with the DT stem than with the DC stem regardless of the equivalent polyethylene wear rate for the two designs. The DC shape of the stem may increase the risk of aseptic loosening.

Occipital and external acoustic meatus to axis angle as a predictor of the oropharyngeal space in healthy volunteers: a novel parameter for craniocervical junction alignment.

BACKGROUND CONTEXT: The occipito-C2 angle (O-C2a) influences the oropharyngeal space. However, O-C2a has several limitations. There is no normal value of O-C2a because of the wide individual variations, and O-C2a does not reflect translation of the cranium to the axis, another factor influencing the oropharyngeal space in patients with atlantoaxial subluxation. PURPOSE: The objective of this study was to propose a novel parameter that accounts for craniocervical junction alignment (CJA) and the oropharyngeal space. STUDY DESIGN: This is a post hoc analysis of craniocervical radiological parameters from another study. PATIENT SAMPLE: Forty healthy volunteers were included in the study. OUTCOME MEASURES: Craniocervical measurement parameters included the occipital and external acoustic meatus to axis angle (O-EAa), the C2 tilting angle (C2Ta), O-C2a, and the anterior-posterior distance of the narrowest oropharyngeal airway space (nPAS). MATERIALS AND METHODS: We collected 40 healthy volunteers' lateral cervical radiographs in neutral, flexion, extension, protrusion, and retraction positions. We measured O-C2a, C2Ta (formed by the inferior end plate of C2 and a line connecting the external acoustic meatus and the midpoint of the inferior end plate of C2 [EA-line]), O-EAa (formed by the McGregor line and the EA-line), and nPAS. We evaluated the inter-rater and intrarater reliability of O-EAa and C2Ta, and the associations between each of the measured parameters. RESULTS: The inter-rater and intrarater reliabilities of measuring O-EAa and C2Ta were excellent. The neutral position O-EAa values remained in a narrower range (mean±standard deviation, 90.0°±5.0°) than O-C2a (15.6°±6.7°) (Levene test of equality of variances, p=.044). In the linear mixed-effects models, sex, O-C2a, C2Ta, and O-EAa were significantly associated with nPAS. The marginal R2 values for the mixed-effect models, which express the variance explained by fixed effects, were 0.605 and 0.632 for the O-C2a and O-EAa models, respectively. In all models, the subaxial alignment (C2-C6a) had no significant association with nPAS. CONCLUSIONS: The O-EAa may be a useful parameter of CJA with several advantages over O-C2a, including less individual variation, easier visual recognition during surgery, and improved prediction of postoperative nPAS after occipitocervical fusion.

Polyethylene and highly cross-linked polyethylene for cemented total hip arthroplasty: A comparison of over ten-year clinical and radiographic results.

INTRODUCTION: We investigated the long-term tribological outcomes of conventional polyethylene (CPE) and highly cross-linked polyethylene (HXLPE). METHODS: Ninety-four consecutive primary cemented THAs were performed using either HXLPE or CPE at our hospital. CPE sockets were used in 26 hips, and HXLPE sockets were implanted in 68 hips. RESULTS: A 10-year follow-up was completed for 69 cases. Linear wear rates of 0.138 ± 0.074 mm/year for CPE and 0.011 ± 0.020 mm/year for HXLPE were calculated. Osteolysis was identified in 10 cases (CPE group, 7; HXLPE group, 3). CONCLUSION: HXLPE had significantly less wear than CPE, and polyethylene wear was associated with osteolysis.

The Relationship Between Subluxation Percentage of the Femoroacetabular Joint and Acetabular Width in Asian Women with Developmental Dysplasia of the Hip.

BACKGROUND: Implantation of the acetabular cup insert in the "true" location of the acetabulum is a fundamental principle of total hip arthroplasty for the treatment of secondary osteoarthritis due to developmental dysplasia of the hip (DDH). As knowledge of the morphology of the acetabulum is required for accurate placement, we investigated the relationship between acetabular width and the Crowe classification of subluxation percentage of the hip. We also analyzed factors associated with the acetabular width ratio (AWR), defined as the acetabular width of the dysplastic hip divided by that of the unaffected, contralateral hip. METHODS: We completed a retrospective review of the preoperative standard anteroposterior radiographs and computed tomography (CT) scans of 207 female patients who underwent primary total hip arthroplasty for unilateral DDH. The "true" acetabular plane was defined on each CT reconstruction as a plane perpendicular to the anterior pelvic plane, parallel to the teardrop line, and passing through the center of the femoral head on the unaffected, contralateral side. The acetabular width was measured for both the affected hip and the contralateral, reference hip on the true acetabular plane, with the acetabular width defined as the distance between the edges of the anterior and posterior walls of the acetabulum. All hips were classified according to the Crowe groupings on the basis of the subluxation percentage of the dysplastic hip; the subluxation percentage increased from groups I to IV, with group IVb showing joint dislocation. RESULTS: The acetabular width decreased from Crowe groups I to IVb, with a negative correlation found between the AWR and the subluxation percentage (Spearman correlation coefficient, ρ = -0.404; p < 0.001). Multivariate regression analysis identified subluxation percentage and femoral neck-shaft angle as independent factors associated with the AWR. CONCLUSIONS: Characterization of factors associated with the AWR, namely subluxation percentage and femoral neck-shaft angle, will guide surgeons in correctly implanting the acetabular cup insert during total hip arthroplasty in patients with DDH.