Studies of the vestibulo-ocular reflex and visual-vestibular interactions during active head movements

The ratio of slow phase eye speed to head speed (Gain) during voluntary sinusoidal head rotations at 0.33, 0.67 and 1.0 Hz was studied in normal subjects under various target presentations. With mental arithmetic in the dark, the mean value of the Gain was 0.8 irrespective of turning frequencies. When subjects looked at or imagined (in the dark) a spatially fixed target, the Gain was always maintained at unity. The Gain measured with a head-fixed target was 0.22, 0.33 and 0.54 at 0.33, 0.67 and 1.0 Hz, respectively. However, imagining a target in this condition failed to suppress the Gain obtained with mental arithmetic in the dark. When a target moved twice as fast as the head (pursuit of the reflected image in a head-fixed mirror), the Gain was -0.60, -0.11 and 0.38 at 0.33, 0.67 and 1.0 Hz, respectively.

Incidence of low-grade infection in aseptic loosening of total hip arthroplasty

PURPOSE

We investigated the hypothesis that many total hip arthroplasty revisions that are classified as aseptic are in fact low-grade infections missed with routine diagnostics.

METHODS

In 7 Dutch hospitals, 176 consecutive patients with the preoperative diagnosis of aseptic loosening of their total hip arthroplasty were enrolled. During surgery, between 14 and 20 tissue samples were obtained for culture, pathology, and broad-range 16S rRNA PCR with reverse line blot hybridization. Patients were classified as either not being infected, suspected of having infection, or infected according to strict, predefined criteria. Each patient had a follow-up visit after 1 year.

RESULTS

7 patients were classified as infected, 4 of whom were not identified by routine culture. 15 additional patients were suspected of having infection. 20 of these 22 patients received a cemented prosthesis, fixated with antibiotic-loaded bone cement. All 22 patients received prophylactic systemic antibiotics. 7 of them reported complaints one year after surgery, but only one showed signs of early loosening. However, additional surgery was not performed in any of the patients.

INTERPRETATION

Although the proportions were not as high as previously reported in the literature, between 4% and 13% of patients with the preoperative diagnosis of aseptic loosening were infected. However, as thorough debridement was performed during surgery and prophylactic antibiotics were used, the diagnosis of infection did not have any obvious clinical consequences, as most patients performed well at the 1-year follow-up. Whether this observation has implications for long-term implant survival remains to be seen.

Brief ultrasonication improves detection of biofilm-formative bacteria around a metal implant

Biofilms are complex microenvironments produced by microorganisms on surfaces. Ultrasonication disrupts biofilms and may make the microorganism or its DNA available for detection. We determined whether ultrasonication could affect our ability to detect bacteria adherent to a metal substrate. A biofilm-formative Staphylococcus aureus strain was used for an in vitro implant infection model (biofilm-formative condition). We used quantitative culture and real time-polymerase chain reaction to determine the influence of different durations of ultrasound on bacterial adherence and viability. Sonication for 1 minute increased the yield of bacteria. Sonication longer than 5 minutes led to fewer bacterial colonies by conventional culture but not by polymerase chain reaction. This suggests short periods of sonication help release bacteria from the metal substrate by disrupting the biofilm, but longer periods of sonication lyse bacteria prohibiting their detection in microbiologic cultures. A relatively short duration of sonication may be desirable for maximizing detection of biofilm-formative bacteria around implants by culture or polymerase chain reaction.

Pseudogout attack of the lumbar facet joint: a case report

STUDY DESIGN

A case of acute low back pain caused by pseudogout attack of the lumbar facet joint is reported.

OBJECTIVE

To report a new cause of acute low back pain previously unreported in the literature.

SUMMARY OF BACKGROUND DATA

There have been some reports of lumbar spinal stenosis caused by calcium pyrophosphate dihydrate crystal deposition. However, there are no known reports of pseudogout attack of the lumbar facet joint.

METHODS

An axial magnetic resonance imaging scan demonstrated joint effusion at the level of the bilateral L4-L5 facet joint. Aspiration of the left L4-L5 facet joint yielded 1.5 mL of pus-like synovial effusion. Multiple cultures of synovial fluid tested negative for bacteria and fungi, whereas compensated polarized light microscopy revealed monoclinic or triclinic crystals with a positive birefringence.

RESULTS

The symptoms of acute low back pain lasted for 3 days. Local and systemic inflammatory signs, as well as symptoms, gradually improved after joint aspiration. A follow-up evaluation 8 months after lumbar facet joint aspiration showed complete resolution of pain and no neurologic deficit.

CONCLUSIONS

Pseudogout attack of the lumbar facet joint is rare, but this clinical entity should be added to the differential diagnosis of acute low back pain.

Perivascular and diffuse lymphocytic inflammation are not specific for failed metal-on-metal hip implants

BACKGROUND

Several studies suggest that histologic findings from tissues obtained at revision arthroplasty for failed metal-on-metal (MOM) total hip implants may reflect an immune reaction to particles or ions in some patients. However, only a limited number of cases without MOM implants were reported as controls in those studies.

QUESTIONS/PURPOSES

The purpose of this study is to better define the extent and distribution of morphologic features attributed to an immune reaction in tissues sampled at revision surgery for failed nonMOM THA.

PATIENTS AND METHODS

As part of a multicenter, prospective study, we reviewed 612 capsular and interface tissues obtained from 130 patients at revision THA. The samples were selected from periacetabular regions (154 samples from 103 patients), femoral implant/cement-bone interface (154 samples from 79 patients), and from areas of the joint capsule that had an intraoperative gross appearance suggesting the possibility of either infection or metallosis (256 samples from 129 patients). All patients had more than one sample obtained. The extent and distribution of lymphocytes and plasma cells, acute inflammation, and visible particles of debris were graded using criteria similar to those described to grade inflammation around failed MOM implants.

RESULTS

We identified perivascular lymphocytes in 111 biopsy samples taken from 65 (50%) of 130 patients, and in 87 specimens from 57 (53%) of 107 patients thought to have aseptic loosening. Diffusely distributed lymphocytes were identified in 86 (66%) of 130 patients, and in 66 (62%) of the 107 hips with aseptic loosening, although few had the highest grade of inflammation. Increasing extent of diffuse and perivascular lymphocytes correlated with increasing extent of metal particles.

CONCLUSIONS

Mild lymphocytic inflammation, diffuse and especially perivascular, is common in tissues around failed nonMOM implants. Although extensive inflammation in an inflammatory pseudotumor pattern is rare, it does occur in some cases of failed metal-polyethylene hip arthroplasties. The importance of inflammation is unknown, but the extent of diffuse inflammation shows a positive correlation with metal debris, so it could reflect a reaction to particles or ions in some patients.

Oxidative stress-induced apoptosis and matrix loss of chondrocytes is inhibited by eicosapentaenoic acid

Eicosapentaenoic acid (EPA) is an antioxidant and n-3 polyunsaturated fatty acid that reduces the production of inflammatory cytokines. We evaluated the role of EPA in chondrocyte apoptosis and degeneration. Normal human chondrocytes were treated with EPA and sodium nitroprusside (SNP). Expression of metalloproteinases (MMPs) was detected by real-time polymerase chain reaction (PCR) and that of apoptosis-related proteins was detected by western blotting. Chondrocyte apoptosis was detected by flow cytometry. C57BL/6J mice were used for the detection of MMP expression by immunohistochemistry and for investigation of chondrocyte apoptosis. EPA inhibited SNP-induced chondrocyte apoptosis, caspase 3 and poly(ADP-ribose) polymerase cleavage, phosphorylation of p38 MAPK and p53, and expression of MMP3 and MMP13. Intra-articular injection of EPA prevented the progression of osteoarthritis (OA) by inhibiting MMP13 expression and chondrocyte apoptosis. EPA treatment can control oxidative stress-induced OA progression, and thus may be a new approach for OA therapy.

Electromyographic study of the striated urethral sphincter in type 3 stress incontinence: evidence of myogenic-dominant damages

OBJECTIVES

To determine the electromyographic features of the striated urethral sphincter in patients with type 3 stress incontinence (SI) due to intrinsic sphincteric deficiency (ISD).

METHODS

We performed electromyography (EMG) of the striated urethral sphincter muscle and urodynamic studies in a total of 51 women, 41 female patients with type 3 SI and 10 women with normal urinary control (NUC). The results were analyzed in both groups, and the correlation of EMG findings with the patient characteristics and urodynamic parameters was evaluated.

RESULTS

Motor unit potentials (MUP) of SI patients showed significantly shorter duration (P = 0.0014), lower amplitude (P = 0.0008), and larger number of phases (P = 0.0022) compared with those in the NUC group. Thirty (73%) of the SI patients showed an obvious low amplitude (less than 350 microV)/short duration (less than 4.5 milliseconds)/polyphasic pattern and early recruitment of interference activity with low amplitude at voluntary contraction of the striated sphincter, both indicating existence of myogenic damages. These patients showing myogenic damages had significantly lower Valsalva leak point pressure (P = 0.002) and more leakage in the pad-weigh test (P = 0.010) compared with the SI patients without myogenic damage findings.

CONCLUSIONS

These results suggested that myogenic-dominant damages of the striated urethral sphincter may contribute to the etiology of ISD in most patients with type 3 SI.

The comparison of pyrosequencing molecular Gram stain, culture, and conventional Gram stain for diagnosing orthopaedic infections

We have developed a combined real-time PCR and pyrosequencing assay that successfully differentiated the vast majority of gram-positive and gram-negative bacteria when bacterial isolates were tested. The purpose of this study was to evaluate this assay on clinical specimens obtained from orthopedic surgeries, and to prospectively compare the results of "molecular Gram stain" with culture and conventional direct Gram stain. Forty-five surgical specimens were obtained from patients who underwent orthopedic surgery procedures. The DNA was extracted and a set of broad-range PCR primers that targeted a part of the 16S rDNA gene was used for pan-bacterial PCR. The amplicons were submitted for pyrosequencing and the resulting molecular Gram stain characteristics were recorded. Culture and direct Gram staining were performed using standard methods for all cases. Surgical specimens were reviewed histologically for all cases that had a discrepancy between culture and molecular results. There was an 86.7% (39/45) agreement between the traditional and molecular methods. In 12/14 (85.7%) culture-proven cases of bacterial infection, molecular Gram stain characteristics were in agreement with the culture results, while the conventional Gram stain result was in agreement only for five cases (35.7%). In the 31 culture negative cases, 27 cases were also PCR negative, whereas 4 were PCR positive. Three of these were characterized as gram negative and one as gram positive by this molecular method. Molecular determination of the Gram stain characteristics of bacteria that cause orthopedic infections may be achieved, in most instances, by this method. Further studies are necessary to understand the clinical importance of PCR-positive/culture-negative results.

A molecular gram stain using broad range PCR and pyrosequencing technology: a potentially useful tool for diagnosing orthopaedic infections

The bacteria associated with orthopaedic infections are usually common gram-positive and gram-negative bacteria. This fundamental grouping of bacteria is a necessary first step in the selection of appropriate antibiotics. Since polymerase chain reaction (PCR) is more rapid and may be more sensitive than culture, we developed a postamplification pyrosequencing method to subcategorize bacteria based on a few nucleotide polymorphisms in the 16S rRNA gene. We validated this method using well-characterized strains of bacteria and applied it to specimens from spinal surgery cases with suspected infections. Lysates of 114 bacteria including 75 species were created following standard cultivation to obtain DNA. The DNA was amplified by a broad-range real-time PCR. The amplicons were evaluated by pyrosequencing and were classified as gram-positive, gram-negative, or acid-fast bacilli based on the first three to five nucleotides sequenced. In addition, clinical cases of suspected infection were obtained from spinal surgery. The results of the "molecular Gram stain" were compared with the results of traditional Gram stain and culture. The lysates of 107 (93.9%) of the bacteria extracts tested were appropriately categorized as gram-positive and gram-negative or as acid-fast bacilli on the basis of this assay. The sensitivity and specificity of this assay were 100% and 97.4% for gram-positive and 88.3% and 100% for gram-negative isolates. All of the five clinical samples were appropriately categorized as containing gram-positive or gram-negative bacteria with this assay. This study demonstrates that high sensitivity and specificity of a molecular gram stain may be achieved using broad-range real-time PCR and pyrosequencing.

p21 deficiency is susceptible to osteoarthritis through STAT3 phosphorylation

Introduction

Osteoarthritis (OA) is a multifactorial disease, and recent studies have suggested that cell cycle–related proteins play a role in OA pathology. p21 was initially identified as a potent inhibitor of cell cycle progression. However, it has been proposed that p21 is a regulator of transcription factor activity. In this study, we evaluated the role of p21 in response to biomechanical stress.

Methods

Human chondrocytes were treated with p21-specific small interfering RNA (siRNA), and cyclic tensile strain was introduced in the presence or absence of a signal transducer and activator of transcription 3 (STAT3)-specific inhibitor. Further, we developed an in vivo OA model in a p21-knockout background for in vivo experiments.

Results

The expression of matrix metalloproteinase (MMP13) mRNA increased in response to cyclic tensile strain following transfection with p21 siRNA, whereas the expression of aggrecan was decreased. Phospho-STAT3 and MMP-13 protein levels increased following downregulation of p21, and this was reversed by treatment with a STAT3 inhibitor. p21-deficient mice were susceptible to OA, and this was associated with increased STAT3 phosphorylation, elevated MMP-13 expression, and elevation of synovial inflammation. The expression of p21 mRNA was decreased and phosphorylation of STAT3 was elevated in human OA chondrocytes.

Conclusions

The lack of p21 has catabolic effects by regulation of aggrecan and MMP-13 expression through STAT3 phosphorylation in the cartilage tissue. p21 may function as a regulator of transcriptional factors other than the inhibitor of cell cycle progression in the cartilage tissue. Thus, the regulation of p21 may be a therapeutic strategy for the treatment of OA.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-015-0828-6) contains supplementary material, which is available to authorized users.

Inflammation and Degeneration in Cartilage Samples from Patients with Femoroacetabular Impingement

BACKGROUND

Femoroacetabular impingement (FAI) has been reported as a cause of hip pain in young patients and is suggested as the trigger for hip osteoarthritis (OA). The goal of this study was to quantify the metabolic profiles of articular tissues (cartilage, synovium, and labrum) harvested from patients with FAI and with end-stage OA. In addition, we sought to investigate the development of secondary OA in hips with FAI.

METHODS

Tissue samples were obtained from thirty hips undergoing arthroscopic surgery for FAI with or without labral tear and thirty hips undergoing total hip arthroplasty for OA. Quantitative real-time polymerase chain reaction (PCR) was performed to determine the gene expression of inflammatory cytokines and metabolic (anabolic and catabolic) enzymes. The differences in gene expression in articular tissues from the patients with FAI were also evaluated on the basis of clinical parameters (age range and alpha angle).

RESULTS

The messenger RNA (mRNA) expression of the inflammatory cytokines interleukin-1 beta (IL-1β) and IL-8 and of matrix metalloproteinase (MMP)-3 (a catabolic gene) in both the synovium and the labrum, and the expression of collagen type I alpha 1 (an anabolic gene) in the labrum, was higher in the samples from hips with OA than in those from hips with FAI (p < 0.05). In cartilage, however, the mRNA expression of the inflammatory cytokines and the catabolic genes MMP-13 and ADAMTS-4 (a disintegrin and metalloproteinase with thrombospondin motifs-4) was higher in the FAI samples compared with the OA samples (p < 0.01). When the expression of inflammatory cytokines was evaluated among the three types of tissues within each disease group, the expression levels were the highest in cartilage within the FAI samples (p < 0.01). In FAI cartilage, we found higher gene expression of aggrecan (ACAN) and ADAMTS-4 in the samples from patients with larger alpha angles (≥60°) (p < 0.01).

CONCLUSIONS

Our results indicate that the metabolic conditions of articular cartilage in FAI and OA are different and that the expression of genes associated with inflammation is greater in the articular cartilage of patients with FAI compared with the synovium and the labrum. The metabolic changes were heightened by mechanical impingement.

CLINICAL RELEVANCE

The articular cartilage from the impingement lesion in patients with FAI showed biologically higher inflammation and degeneration, supporting the concept that FAI may be a trigger for joint degeneration.

Reconstruction of the iliofemoral ligament with an artificial ligament for recurrent anterior dislocation of total hip arthroplasty

An 86-year-old woman underwent 4 revisions of hip arthroplasty and showed good position of both acetabular and femoral components. This was confirmed by roentgenographic measurements in the prone position. However, poor anterior acetabular covering after posterior inclination of the pelvis associated with lumbar kyphosis was observed in the standing position. Therefore, we reconstructed the iliofemoral ligament using a Leeds-Keio ligament to prevent anterior dislocation. At the 12-month follow-up evaluation, hip stability was confirmed, and the hip showed no further dislocation.

PTEN regulates matrix synthesis in adult human chondrocytes under oxidative stress

Phosphatase and tensin homologue deleted on chromosome 10 (PTEN) was identified as an important tumor suppressor gene. PTEN functions as a negative regulator of phosphoinositol-3-kinase (PI3K)-Akt and MEK/ERK signaling. The PI3K-Akt pathway is critical for cell survival, differentiation, and matrix synthesis. Oxidative stress is considered a critical factor in the onset and progression of osteoarthritis (OA). Therefore, we investigated the function of PTEN in OA chondrocytes under oxidative stress. Chondrocytes were treated with insulin-like growth factor-1 (IGF-1) and/or tert-butyl hydroperoxide (tBHP), which causes oxidative stress. The expression levels of type2 collagen (Col2a1) and aggrecan were analyzed by real-time PCR, and phosphorylation of Akt and ERK1/2 was analyzed by Western blotting. Chondrocytes were treated with PTEN-specific small interfering RNA (siRNA), as well as IGF-1 and/or tBHP. PTEN and IGF-1 expressions in OA chondrocytes were increased. The downregulation of PTEN expression increased the expression levels of Col2a1 and aggrecan, and increased proteoglycan synthesis under oxidative stress. Oxidative stress decreased the phosphorylation of Akt and increased that of ERK1/2. The downregulation of PTEN expression increased Akt phosphorylation, but did not increase that of ERK 1/2. Our results suggest that PTEN regulates matrix synthesis via the PI3K-Akt pathway under oxidative stress.

Accuracy of cup orientation and learning curve of the accelerometer-based portable navigation system for total hip arthroplasty in the supine position

PURPOSE

To assess the accuracy of cup orientation and learning curve of the disposable accelerometer-based portable navigation system for total hip arthroplasty (THA) in the supine position.

METHODS

A total of 75 patients who underwent THA through the anterolateral supine approach (ALS) with an accelerometer-based portable navigation system for the supine position (HipAlign^®) between July 2017 and October 2018 were analyzed in this study. We compared the intraoperative cup angles using navigation records with the postoperative angles using postoperative computed tomography (CT) data. All patients were categorized into the following groups according to the course of three discrete, sequential operative time periods: 1-25 (initial group), 26-50 (intermediate group), and 51-75 (recent group). We compared the accuracy of cup inclination and anteversion among the three groups. The time required for navigation and the operative time of all patients were measured.

RESULTS

The average absolute error in measurement (postoperative CT-navigation record) was 2.6° ± 2.7° (inclination) and 2.8° ± 2.7° (anteversion). There were no significant differences among the three groups. The average time required for navigation and the operative time were 365.1 ± 90.3 s and 76.1 ± 1.6 min, respectively. The required time for HipAlign^® navigation and operative time were constant in most patients, except for those of the initial five cases.

CONCLUSION

The accelerometer-based portable navigation system provides good accuracy of cup orientation, has a short learning curve, and requires a minimal surgical time for THA in supine position.

P21 deficiency delays regeneration of skeletal muscular tissue

The potential relationship between cell cycle checkpoint control and tissue regeneration has been indicated. Despite considerable research being focused on the relationship between p21 and myogenesis, p21 function in skeletal muscle regeneration remains unclear. To clarify this, muscle injury model was recreated by intramuscular injection of bupivacaine hydrochloride in the soleus of p21 knockout (KO) mice and wild type (WT) mice. The mice were sacrificed at 3, 14, and 28 days post-operation. The results of hematoxylin-eosin staining and immunofluorescence of muscle membrane indicated that muscle regeneration was delayed in p21 KO mice. Cyclin D1 mRNA expression and both Ki-67 and PCNA immunohistochemistry suggested that p21 deficiency increased cell cycle and muscle cell proliferation. F4/80 immunohistochemistry also suggested the increase of immune response in p21 KO mice. On the other hand, both the mRNA expression and western blot analysis of MyoD, myogenin, and Pax7 indicated that muscular differentiation was delayed in p21KO mice. Considering these results, we confirmed that muscle injury causes an increase in cell proliferation. However, muscle differentiation in p21 KO mice was inhibited due to the low expression of muscular synthesis genes, leading to a delay in the muscular regeneration. Thus, we conclude that p21 plays an important role in the in vivo healing process in muscular injury.

Effect of cyclic mechanical stretch and titanium particles on prostaglandin E2 production by human macrophages in vitro

Early implant instability has been proposed as a critical factor in the onset and progression of aseptic loosening and periprosthetic osteolysis in total joint arthroplasties. Previous in vitro studies have reported that macrophages stimulated with cyclic mechanical strain release inflammatory mediators. Little is known, however, about the response of these cells to mechanical strain with particles, which is often a component of the physical environment of the cell. We therefore studied the production of prostaglandin E(2) (PGE(2)), an important mediator in aseptic loosening and periprosthetic osteolysis in total joint arthroplasties, for human macrophages treated with mechanical stretch alone, titanium particles alone, and mechanical stretch and particles combined. A combination of mechanical stretch and titanium particles resulted in a statistically synergistic elevation of levels of PGE(2) compared with the levels found with either stretch or particles alone. Exposure of human macrophages to mechanical stretch with particles upregulated the expression of cyclooxygenase (COX)-2 mRNA but not COX-1 mRNA, this expression resulting in a 97-fold increase in PGE(2) production compared to the nonstimulated cells. The current study is the first to investigate the effects of mechanical stretch with particles on cultured macrophages and include an investigation of the time course of PGE(2) production and COX-2 mRNA expression. Our results suggest that, while mechanical strain may be one of the primary factors responsible for macrophage activation and periprosthetic osteolysis, mechanical strain with particles load may contribute significantly to the osteolytic potential of macrophages in vitro. The synergistic effect observed between mechanical stretch and particles could accelerate implant loosening and implies that reduction in either cyclic mechanical strain or wear debris load would lead to a reduction of osteolysis.

Akt phosphorylation in human chondrocytes is regulated by p53R2 in response to mechanical stress

OBJECTIVE

The p53 tumor-suppressor protein p53R2 is activated in response to various stressors that act on cell signaling. When DNA is damaged, phosphorylation of p53 at its Ser 15 residue induces p53R2 production. The role of p53R2 in chondrocytes remains poorly understood. In this study, we evaluated in chondrocytes, p53R2 expression and its regulation in response to mechanical stress. Furthermore, we investigated the function of p53R2 in relation to mechanotransduction.

METHODS

Osteoarthritis (OA) cartilage obtained from total knee replacements and normal cartilage obtained from femoral neck fractures was used to measure p53R2 expression by using immunohistochemistry, western blotting, and real-time polymerase chain reaction (PCR). The OA chondrocytes were subjected to a high magnitude of cyclical tensile strain by using an FX-2000 Flexercell system. Next, sulfated glycosaminoglycan (sGAG) production was quantified in these cells. Protein expression of p53R2, and phosphorylation of Akt, p38MAPK, ERK1/2, and JNK was also detected using western blotting. Moreover, Akt phosphorylation was detected after transfecting the cells with p53R2-specific small interfering RNA (siRNA).

RESULTS

Expression of p53R2 was significantly increased in OA chondrocytes and in chondrocytes after applying 5% tensile strain to the cells. However, Akt phosphorylation was down-regulated in OA chondrocytes after the strain, and was up-regulated after transfection of p53R2. sGAG protein as well as collagen type II and aggrecan mRNA was increased following transfection of p53R2-specific siRNA after 5% tensile strain.

CONCLUSIONS

p53R2 could regulate matrix synthesis via Akt phosphorylation during chondrocyte mechanotransduction. Down-regulation of p53R2 may be a new therapeutic approach in OA therapy.

Influence of tibial component rotation on short-term clinical outcomes in Oxford mobile-bearing unicompartmental knee arthroplasty

BACKGROUND

Malposition of tibial components is an important factor for complications in unicompartmental knee arthroplasty (UKA), but the direct relationship between clinical outcomes and position of tibial component remains unknown. We aimed to investigate whether tibial component rotation in the axial plane could affect clinical outcomes after UKA.

METHODS

A total of 50 patients with anteromedial osteoarthritis of the knee underwent Oxford mobile-bearing UKA in this study. Patient-derived clinical scores using the Oxford Knee Score (OKS) and the functional activities of Knee Society Score (KSSF) were assessed preoperatively, and then after one year and two years following surgery. Postoperative tibial component rotation angles using two reference lines in the axial plane were assessed using three-dimensional computed tomography two weeks postoperatively. External rotation of the tibial component relative to each reference line was considered a positive value. We analysed the sequential change of the OKS and KSSF using repeated measures analysis of variance (P < 0.05). The effects of tibial component rotation on the OKS and KSSF were analysed using linear regression analysis.

RESULTS

OKS and KSSF showed significant recovery between the preoperative and one-year postoperative period. Rotation angles of tibial components had significant negative correlations with the recovery of the OKS in the two years following UKA.

CONCLUSIONS

Tibial component rotation played an important role in improving clinical outcomes during the two years following Oxford mobile-bearing UKA. A trend towards poor outcome was observed when the tibial component was placed at a higher angle of external rotation.

LEVEL OF EVIDENCE

III.

Augmented reality: The use of the PicoLinker smart glasses improves wire insertion under fluoroscopy

AIM

To demonstrate the feasibility of the wearable smart glasses, PicoLinker, in guide wire insertion under fluoroscopic guidance.

METHODS

Under a fluoroscope, a surgeon inserted 3 mm guide wires into plastic femurs from the lateral cortex to the femoral head center while the surgeon did or did not wear PicoLinker, which are wearable smart glasses where the fluoroscopic video was displayed (10 guide wires each).

RESULTS

The tip apex distance, radiation exposure time and total insertion time were significantly shorter while wearing the PicoLinker smart glasses.

CONCLUSION

This study indicated that the PicoLinker smart glasses can improve accuracy, reduce radiation exposure time, and reduce total insertion time. This is due to the fact that the PicoLinker smart glasses enable surgeons to keep their eyes on the operation field.

Evaluation of the accuracy of acetabular cup orientation using the accelerometer-based portable navigation system

BACKGROUND

Accurate orientation of acetabular and femoral components is important during total hip arthroplasty (THA). In recent years, several navigation systems have been developed. However, these navigation systems for THA are unpopular worldwide because of their high cost. We assessed the orientation accuracy of cups inserted using a disposable accelerometer-based portable navigation system for THAs.

METHODS

This was a prospective cohort study. We analyzed 63 hips with navigation prospectively and 30 hips without navigation retrospectively as historical control. The patients underwent THA via the mini anterolateral approach in the supine position using an accelerometer-based portable navigation system. We compared the preoperative target angles, intraoperative cup angles using navigation records, postoperative angles using postoperative CT data, measurement errors of cup angles, and clinical parameters such as sex, treated side, age at surgery, and body mass index (BMI).

RESULTS

The average absolute error (postoperative CT-navigation record) was 2.7 ± 2.1° (inclination) and 2.7 ± 1.8° (anteversion), and the absolute error (postoperative CT-preoperative target angle) was 2.6 ± 1.9° (inclination) and 2.7 ± 2.2° (anteversion). The absolute error between postoperative CT and target angle with navigation was significantly lower than the error without navigation (inclination; p = 0.025, anteversion; p = 0.005). Cup malalignment (absolute difference of inclination or anteversion between postoperative CT and preoperative target angle of over 5°) was significantly associated with BMI value (OR: 1.3, 95% CI: 1.1-1.7). The absolute measurement error of cup inclination and anteversion was significantly correlated with patients' BMI (inclination error: correlation coefficient = 0.53, p < 0.001, anteversion error: correlation coefficient = 0.58, p < 0.001).

CONCLUSIONS

The clinical accuracy of accelerometer-based portable navigation is precise for the orientation of cup placement, although accurate cup placement was affected by high BMI. This is the first study to report the accuracy of accelerometer-based portable navigation for THA in the supine position.

Histological evaluation of an impacted bone graft substitute composed of a combination of mineralized and demineralized allograft in a sheep vertebral bone defect

Demineralized bone matrix (DBMs) preparations are a potential alternative or supplement to autogenous bone graft, but many DBMs have not been adequately tested in clinically relevant animal models. The aim of current study was to compare the efficacy of a new bone graft substitute composed of a combination of mineralized and demineralized allograft, along with hyaluronic acid (AFT Bone Void Filler) with several other bone graft materials in a sheep vertebral bone void model. A drilled defect in the sheep vertebral body was filled with either the new DBM preparation, calcium sulfate (OsteoSet), autologous bone graft, or left empty. The sheep were euthanized after 6 or 12 weeks, and the defects were examined by histology and quantitative histomorphometry. The morphometry data were analyzed by one-way analysis of variance with the post hoc Tukey-Kramer test or the Student's t-test. All of the bone defects in the AFT DBM preparation group showed good new bone formation with variable amounts of residual DBM and mineralized bone graft. The DBM preparation group at 12 weeks contained significantly more new bone than the defects treated with calcium sulfate or left empty (respectively, p < 0.05, p < 0.01). There was no significant difference between the DBM and autograft groups. No adverse inflammatory reactions were associated with any of the three graft materials. The AFT preparation of a mixture of mineralized and demineralized allograft appears to be an effective autograft substitute as tested in this sheep vertebral bone void model.

Long-term evaluation of a calcium phosphate bone cement with carboxymethyl cellulose in a vertebral defect model

We investigated histological and compressive properties of a calcium phosphate bone cement (BoneSource (CPC); Stryker Orthopaedics, Mahwah, New Jersey) plus carboxymethyl cellulose (CMC) using a sheep vertebral bone void model. Bone voids were surgically created in L3 and L5 in each of 40 sheep, and the voids were filled with the cement. Histological and radiographic evaluations were performed on one vertebral body from each animal at either: 0, 3, 6, 12, 24, or 36 months after surgery; mechanical testing was performed on operated and non-operated vertebral bodies from 35 sheep. Undecalcified sections were digitized, and the area of the original defect, new bone formation, empty space, fibrous tissue, and residual cement were quantified with histomorphometry. Decalcified sections were evaluated qualitatively. The cement was biocompatible, extremely osteoconductive and underwent steady resorption and replacement by bone and bone marrow. Histomorphometry showed variations in the rate of cement remodeling among animals in each time group, but on average, at 36 months the original defect area was occupied by approximately 14% bone, 82% cement, and 4% bone marrow. Even in animals that had greater resorption of cement, there was good bone ingrowth with no fibrous tissue. Compressive testing did not reveal a significant difference in the mechanical properties between vertebral bodies augmented with cement and non-augmented controls, irrespective of the postoperative time. BoneSource mixed with CMC had adequate osteoconductivity, biocompatibility, and adequate compressive strength. There was variability among animals, but histology suggests that considerable cement was still present in most samples after 36 months.

Effect of etidronate on COX-2 expression and PGE(2) production in macrophage-like RAW 264.7 cells stimulated by titanium particles

BACKGROUND

The most common failure of total joint replacement is aseptic loosening in association with osteolysis. Previous reports have shown that prostaglandin E(2) (PGE(2)) secreted from macrophages that phagocytosed wear debris induced periprosthetic osteolysis. Many clinical studies have reported that bisphosphonate therapy reduced periprosthetic bone loss and loosening of the implants after total joint replacements. Bisphosphonates are synthetic compounds with the ability to decrease bone resorption. In addition, some bisphosphonates have been reported to have anti-inflammatory effects by reducing the secretion of pro-inflammatory cytokines. However, the mechanism of bisphosphonates that reduces periprosthetic bone resorption remains unclear. The purpose of this study was to investigate one of the mechanisms by which etidronate (EHDP) inhibits periprosthetic bone resorption.

METHODS

Macrophage-like RAW 264.7 cells were treated with EHDP at concentrations of 0.001, 0.01, 0.1, 1, 10, and 100 microM together with the titanium particles at a concentration of 1 mg/ml. After a 24-h culture period, total mRNA was isolated and reverse transcription-polymerase chain reaction (RT-PCR) was done to examine the expression of cyclooxygenase-2 (COX-2). The supernatants were also collected and production of PGE(2), interleukin-1beta (IL-1beta), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-alpha) were quantified using an enzyme-linked immunosorbent assay (ELISA).

RESULTS

Analyses showed that COX-2 expression and PGE(2) production were suppressed by EHDP in a dose-dependent manner. By 100 microM of EHDP, PGE(2) production of the cells was suppressed approximately to the level of the nonstimulated cells. Production of IL-1beta, IL-6, and TNF-alpha in the supernatant was also suppressed by EHDP.

CONCLUSIONS

The blockage effect of pro-inflammatory cytokines is a possible etidronate mechanism that reduces bone resorption around implants.

DcR3 induces cell proliferation through MAPK signaling in chondrocytes of osteoarthritis

INTRODUCTION

Decoy receptor 3 (DcR3), a soluble receptor belonging to the tumor necrosis factor (TNF) receptor superfamily, competitively binds and inhibits the TNF family including Fas-ligand (Fas-L), lymphotoxin-like inducible protein that competes with glycoprotein D for binding herpesvirus entry mediator on T-cells (LIGHT) and TNF-like ligand 1A (TL1A). In this study, we investigated the functions of DcR3 on osteoarthritis (OA) chondrocytes.

METHODS

Expressions of DcR3 in chondrocytes were measured by realtime Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR). Expression of DcR3 in sera and joint fluids was measured by enzyme-linked immunosorbent assay (ELISA). Chondrocytes were incubated with DcR3-Fc chimera protein (DcR3-Fc) before induction of apoptosis by Fas-L and apoptosis was detected with terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labelling labeling (TUNEL) staining and Western blotting of caspase 8 and poly (ADP-ribose) polymerase (PARP). Chondrocytes were incubated with DcR3-Fc and the proliferation was analyzed by 4-[3-(4-iodophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1,3-benzene disulfonate (WST) assay. Phosphorylation of Extracellular Signal-Regulated Kinase (ERK), P38 mitogen-activated protein kinase (MAPK) and Jun N-terminal Kinase (JNK) in chondrocytes was measured by Western blotting after incubation with DcR3-Fc, Mitogen-activated protein kinase kinase (MEK1/2) inhibitor, or P38 MAPK inhibitor. Chondrocytes were treated with DcR3-Fc after pre-incubation with blocking antibody of Fas-L, LIGHT and TL1A, and proliferation or phosphorylation of ERK was analyzed.

RESULTS

DcR3 was expressed in OA and normal chondrocytes. DcR3-Fc protects chondrocytes from Fas-induced apoptosis. DcR3-Fc increased chondrocytes proliferation and induced the phosphorylation of ERK specifically. DcR3-induced chondrocytes proliferation was inhibited by pre-incubation of PD098059 or blocking Fas-L antibody. DcR3 increased chondrocytes proliferation in OA chondrocytes, but did not in normal.

CONCLUSION

DcR3 regulates the proliferation of OA chondrocytes via ERK signaling and Fas-induced apoptosis.