Antibacterial and Biocompatible Titanium-Copper Oxide Coating May Be a Potential Strategy to Reduce Periprosthetic Infection: An In Vitro Study.

BACKGROUND: Periprosthetic infections are devastating for patients and more efficacious preventive strategies are needed. Surface-modified implants using antibacterial coatings represent an option to cope with this problem; however, manufacturing limitations and cytotoxicity have curbed clinical translation. Among metals with antibacterial properties, copper has shown superior in vitro antibacterial performance while maintaining an acceptable cytotoxicity profile. A thin film containing copper could prevent early biofilm formation to limit periprosthetic infections. This pilot study presents the in vitro antibacterial effect, cytotoxicity, and copper ion elution pattern of a thin film of titanium-copper oxide (TiCuO). QUESTIONS/PURPOSES: (1) Do titanium alloy (Ti6Al4V) discs coated with a thin film of TiCuO reduce Staphylococcus epidermidis biofilm and planktonic cell density compared with uncoated discs? (2) Do Ti6Al4V discs coated with a thin film of TiCuO affect normal human osteoblast viability compared with untreated cells? (3) Is copper ion concentration generated by coated discs lower than previously published copper ion concentrations that cause 50% toxicity in similar human cell lines in vitro (TC50)? METHODS: Ninety Ti6Al4V discs (12.5 mm diameter; 1.25 mm thick) were used in this study. Seventy-two Ti6Al4V discs were coated with a thin film of either titanium oxide (TiO) or TiCuO containing 20%, 40%, or 80% copper using high-power impulse magnetron sputtering (HiPIMS). Eighteen Ti6Al4V discs remained uncoated for control purposes. We tested antibacterial properties of S epidermidis grown on discs in wells containing growth medium. After 24 hours, planktonic bacteria as well as biofilms removed by sonication were quantitatively cultured. Annexin/Pi staining was used to quantify in vitro normal human osteoblast cell viability at 24 hours and Day 7, respectively. Copper elution was measured at Days 1, 2, 3, 7, 14, and 28 using an inductively coupled plasma mass spectrometer to analyze aliquots of culture medium. Copper ion concentration achieved at 24 hours was compared with previously published TC50 for gingival fibroblast, a phenotypically similar cell line with available data regarding copper ion exposure. RESULTS: Discs coated with TiCuO 80% copper showed greater biofilm and planktonic cell density reduction when compared with other tested compositions (analysis of variance [ANOVA]; p < 0.001). Discs coated with TiCuO 80% copper showed mean biofilm and planktonic cell density of 4.0 log10 (SD = 0.4) and 5.7 log10 (SD = 0.2). Discs coated with TiCuO 80% showed a mean difference in biofilm and planktonic cell density of 2.5 log10 (95% confidence interval [CI], 1.9-3.1 log10; p < 0.001) and 1.2 (95% CI, 0.6-1.8; p < 0.001), respectively, when compared with uncoated discs. Normal human osteoblast viability did not differ among all groups at 24 hours (ANOVA; p = 0.2) and Day 7 (ANOVA; p = 0.7). Discs coated with TiCuO 80% copper showed a mean difference (95% CI) in relative cell viability (%) at 24 hours and Day 7 of 31.1 (95% CI, -19.4 to 81.7; p = 0.4) and -5.0 (95% CI, -7.8 to 17.9; p = 0.9), respectively, when compared with untreated cells. For all TiCuO-coated discs, copper ion elution peaked at 24 hours and slowly decreased in a curvilinear fashion to nearly undetectable levels by Day 28. Discs coated with TiCuO 80% copper showed mean copper ion concentration at 24 hours of 269.4 µmol/L (SD = 25.2 µmol/L) and this concentration was lower than previously published TC50 for similar human cell lines at 24 hours (344 µmol/L, SEM = 44 µmol/L). CONCLUSIONS: This pilot study demonstrates a proof of concept that a thin-film implant coating with TiCuO can provide a potent local antibacterial environment while remaining relatively nontoxic to a human osteoblast cell line. Further research in an animal model will be necessary to establish efficacy and safety of this technique and whether it might be useful in the design of implants. CLINICAL RELEVANCE: A thin film coating with TiCuO demonstrates high antibacterial activity and low cellular cytotoxicity to human osteoblasts in vitro. Taken together, these properties represent a potential strategy for preventing periprosthetic infection if further work in animal models can confirm these results in vivo.

A Rare Pediatric Example of Subcutaneous Extraskeletal Osteosarcoma: A Case Report and Review of the Morphologic Differential Diagnosis.

Primary extraskeletal osteosarcoma is an exceedingly rare malignant neoplasm that accounts for approximately 1% of soft tissue sarcomas and most often occurs in the deep soft tissues of adults. Extraskeletal osteosarcoma is characterized by the production of osteoid, bone, and/or chondroid matrix. The diagnosis of extraskeletal osteosarcoma requires careful radiologic and clinical correlation to ensure that the patient does not have an underlying bone primary. This is a case report of primary subcutaneous extraskeletal osteosarcoma arising in the thigh of a 15-year-old girl with a complex karyotype, and the morphologic differential diagnosis is reviewed.

Adipose-derived Mesenchymal Stem Cells Are Phenotypically Superior for Regeneration in the Setting of Osteonecrosis of the Femoral Head.

BACKGROUND: Bone marrow-derived mesenchymal stem cells (bmMSCs) have been used as a cellular therapeutic option for treatment of osteonecrosis of the femoral head. However, use of bmMSCs as a treatment adjuvant for orthopaedic disorders in general has achieved limited success. Adipose-derived MSCs (aMSCs) may be a more-efficient regenerative cell source given their greater quantity and protection from physiologic stress. QUESTIONS/PURPOSES: We asked the following questions in a paired analysis of MSCs from patients with osteonecrosis: (1) Is there a difference in proliferation potential between aMSCs and bmMSCs? (2) Is there a difference in osteogenic differentiation potential between aMSCs and bmMSCs? (3) Are genetic pathways differentially expressed between aMSCs and bmMSCs that may govern functional phenotypic discrepancies? METHODS: Periarticular samples of adipose tissue and bone marrow from the femoral canal were obtained from 15 patients undergoing hip replacement for late-stage (Steinberg Stages III-VI) osteonecrosis. MSCs were isolated from both tissue sources and taken through a standardized 20-day cell division protocol to establish cumulative cell count. They also were grown in osteogenic differentiation media for 14 days with subsequent measurement of alkaline phosphatase in units of optical density. RNA was isolated from aMSCs and bmMSCs in five patients to assess differentially expressed genetic pathways using the Affymetrix GeneChip Human Transcriptome Array 2.0 platform. RESULTS: Proliferation capacity was increased by fourfold in aMSCs compared with bmMSCs after 20 days in culture. The mean difference in cumulative cell count was 3.99 × 10(8) cells (SD = 1.67 × 10(8) cells; 95% CI, 3.07 × 10(8)-4.92 × 10(8) cells; p < 0.001). Bone differentiation efficiency as measured by optical density was increased by 2.25-fold in aMSCs compared with bmMSCs. The mean difference in optical density was 1.27 (SD = 0.34; 95% CI, 1.08-1.46; p < 0.001). RNA transcriptome analysis showed 284 genes that met statistical (p < 0.05) and biological (fold change > 1.5) significance cutoffs for differential expression between cell populations. Subsequent network topology of differentially expressed genes showed alterations in pathways critical for musculoskeletal tissue development in addition to many nonspecific findings. CONCLUSIONS: aMSCs outperform bmMSCs in growth rate and bone differentiation potential in the setting of osteonecrosis, suggesting they may provide a more-potent regenerative therapeutic strategy in this population. Differential expression of genes and cellular pathways highlighted in this study may provide therapeutic targets for cellular optimization or acellular treatment strategies. CLINICAL RELEVANCE: aMSCs may provide a more robust cellular therapeutic than bmMSCs for treatment of osteonecrosis. Ideally, a well-designed prospective study will be able to evaluate the efficacy of these cellular therapies side-by-side in patients with bilateral early stage disease.

Mesenchymal stem cells in osteoarticular pediatric diseases: an update.

Cellular therapy has gained an increasing popularity in recent years. Mesenchymal stem cells (MSCs) have the potential to differentiate into bone, cartilage, or fat tissue. In recent studies, these cells have also shown healing capability by improving angiogenesis and preventing fibrosis, which could have a role in tissue repair and tissue regeneration. Preclinical and clinical orthopedic studies conducted in the adult population support the use of MSCs for bone-healing problems, early stages of osteonecrosis, and local bone defects. Only a few published studies support the use of MSCs in pediatric osteoarticular disorders, probably due to the unknown long-term results of cellular therapy. The purpose of this review is to explain the mechanism by which MSCs could exhibit a therapeutic role in pediatric osteoarticular disorders.

Effect of dislocation timing following primary total hip arthroplasty on the risk of redislocation and revision.

INTRODUCTION: There is little data regarding timing of index dislocation in patients who undergo primary total hip arthroplasty (THA) and subsequent risk of redislocation and revision. METHODS: Between 1992 and 2013, 21,490 primary THAs were performed at a single institution. 189 patients (190 hips) had a first episode of dislocation within one year of index surgery (0.9 %). 32 patients (32 hips) were excluded for the following reasons: complex THA secondary to fracture malunion, Crowe III/IV developmental hip dysplasia, periprosthetic fracture, prior hip surgery, incomplete information, and hip abductor avulsion. The final cohort consisted of 157 patients (158 hips) who experienced dislocation within 1 year of primary non-complex THA. 88 patients were female (56%), mean age was 61 years (SD = 14), and mean follow-up was 76 months (range 0-229). Multivariable Cox proportional-hazards regression models with fractional polynomial models were used to estimate the association between timing of index dislocation and subsequent redislocation and revision surgery. RESULTS: 69 patients (44%) redislocated at final follow-up. Revision for any cause occurred in 26 out of 157 hips (17%). Time lapse from index THA to first dislocation was significantly associated with the risk of redislocation (p = 0.004) and with the risk of revision (p = 0.04). For every additional 7 days from surgery, risk of redislocation increased by a factor of 1.1 and risk of revision was increased by a factor of 1.13. CONCLUSION: This study demonstrates there is a lower risk of redislocation and revision in patients who have a first episode of dislocation closer to primary THA.

Cam Deformities and Limited Hip Range of Motion Are Associated With Early Osteoarthritic Changes in Adolescent Athletes: A Prospective Matched Cohort Study.

BACKGROUND: The natural history of femoroacetabular impingement (FAI) remains incompletely understood. In particular, there is limited documentation of joint damage in adolescent patients with limited range of motion (LROM) of the hip, which is commonly associated with FAI. PURPOSE: To evaluate changes in magnetic resonance imaging (MRI), radiographs, and clinical examinations over 5 years in a group of athletes from a wide variety of sports with asymptomatic LROM of the hip compared with matched controls. STUDY DESIGN: Cohort study (prognosis); Level of evidence, 2. METHODS: The authors screened 226 male and female athletes aged 12 to 18 years presenting for preparticipation sports physical examinations. Using a goniometer, we identified 13 participants with at least one hip having internal rotation <10° with the hip flexed to 90°. Overall, 21 of 26 hips (81%) had internal rotation <10°. These participants were age- and sex-matched to 13 controls with internal rotation >10°. At the time of enrollment, all participants were asymptomatic and underwent a complete hip examination and radiographic imaging with radiographs (anteroposterior [AP] and von Rosen views) and non-arthrogram MRI. Participants returned at 5-year follow-up and underwent repeat hip examinations, imaging (AP and lateral radiographs and non-arthrogram MRI), and hip function questionnaires. MRI scans were classified as "normal" versus "abnormal" based on the presence of any of 13 scored chondral, labral, or osseous abnormalities. Comparisons between the LROM group and control group were performed using generalized linear models (either linear, logistic, or log-binomial regression as appropriate for the outcome) with generalized estimating equations to account for the within-participant correlation due to patients having both hips included. Relative risk (RR) estimates are reported with 95% CIs. RESULTS: At the time of study enrollment, 16 of 26 hips (62%) in the LROM group had abnormal MRI findings within the acetabular labrum or cartilage compared with 8 of 26 hips (31%) in the control group (RR, 2.0; 95% CI, 0.95-4.2; P = .067). The mean alpha angle measured from radial MRI sequences was 58° in the LROM group versus 44° in the control group ( P < .0001). In the LROM group, 13 of 26 hips (50%) had a positive anterior impingement sign, whereas 0 of 26 hips (0%) had a positive anterior impingement sign in the control group. At 5-year follow-up, 18 of 19 hips (95%) in the LROM group had abnormal MRI findings compared with 14 of 26 hips (54%) in the control group (RR, 1.7; 95% CI, 1.1-2.7; P = .014). New or progressive findings were documented on MRI in 15 of 20 hips in the LROM group compared with 8 of 26 hips in the control group (RR, 2.4; 95% CI, 1.2-4.8; P = .011). Six of 22 hips (27%) in the LROM group progressed from Tönnis grade 0 to Tönnis grade 1 in degenerative changes, whereas all 26 hips in the control group remained at Tönnis grade 0 on hip radiographs. In the LROM group, 11 of 22 hips (50%) had a positive anterior impingement sign, whereas 1 of 26 hips (4%) had a positive anterior impingement sign in the control group. A cam deformity (alpha angle >55° on lateral radiographs) was present in 20 of 22 hips (91%) in the LROM group and 12 of 26 hips (46%) in the control group ( P = .0165). The following variables at baseline were associated with an increased risk of degenerative changes at 5-year follow-up for the entire cohort: decreased hip internal rotation, positive anterior impingement sign, decreased hip flexion, increased alpha angle, and presence of a cam lesion. CONCLUSION: At 5 years, young athletes with LROM of the hip showed increased progressive degenerative changes on MRI and radiographs compared with matched controls. Although the majority of these participants remained asymptomatic, those with features of FAI had radiographic findings consistent with early osteoarthritis. These outcomes suggest that more aggressive screening and counseling of young active patients may be helpful to prevent hip osteoarthritis in those with FAI.