Clinical outcomes of various types of revision surgeries after unicompartmental knee arthroplasty failure.

PURPOSE: The advantages of unicompartmental knee arthroplasty (UKA) have led to the procedure being increasingly performed worldwide. However, revision surgery is required after UKA failure. According to the literature review, the choice of implant in revision surgery remains a debatable concern. This study analyzed the clinical results of different types of prostheses used in treating failed UKA. MATERIALS AND METHODS: This is a retrospective review of 33 failed medial UKAs between 2006 and 2017. Demographic data, failure reason, types of revision prostheses, and the severity of bone defects were analyzed. The patients were classified into three groups: primary prosthesis, primary prosthesis with a tibial stem, and revision prosthesis. The implant survival rate and medical cost of the procedures were compared. RESULTS: A total of 17 primary prostheses, 7 primary prostheses with tibial stems, and 9 revision prostheses were used. After a mean follow-up of 30.8 months, the survival outcomes of the three groups were 88.2%, 100%, and 88.9%, respectively (P = 0.640). The common bone defect in tibia site is Anderson Orthopedic Research Institute [AORI] grade 1 and 2a (16 versus 17). In patients with tibial bone defects AORI grade 2a, the failure rates of primary prostheses and primary prostheses with tibial stems were 25% and 0%, respectively. CONCLUSIONS: The most common cause for UKA failure was aseptic loosening. The adoption of a standardized surgical technique makes it easier to perform revision surgeries. Primary prostheses with tibial stems provided higher stability, leading to a lower failure rate due to less risk of aseptic loosening in patients with tibial AORI grade 2a. In our experience, we advise surgeons may try using primary prostheses in patients with tibial AORI grade 1 and primary prostheses with tibial stems in patients with tibial AORI grade 2a.

Effects of Cancer Cell-Derived Nanovesicle Vaccines Produced by the Oxidative Stress-Induced Expression of DAMP and Spontaneous Release/Filter Extrusion in the Interplay of Cancer Cells and Macrophages.

Photodynamic therapy (PDT)-based cancer vaccines are shown to be more effective modalities for treating cancer in animal models compared to other methods used to generate cancer cell-derived vaccines. The higher efficacy seems to stem from the generation of cell membrane nanovesicles or fragments that carry both cancer cell-specific antigens and high surface content of damage-associated molecular pattern (DAMP) molecules induced by oxidative stress. To develop more effective cancer vaccines in this direction, we explored the generation of cancer vaccines by applying different sources of oxidative stress on cancer cell cultures followed by spontaneous release or filter extrusions to produce cancer cell-derived DAMP-expressing nanovesicles. Through an in-vitro test based on the co-culture of cancer cells and macrophages, it was found that the nanovesicle vaccines generated by H2O2 are as effective as those generated by PDT in diminishing cancer cell culture masses, providing a simpler way to manufacture vaccines. In addition, the nanovesicle vaccines produced by filter extrusion are as potent as those produced by spontaneous release, rendering a more stable way for vaccine production.

Do Serum C-Reactive Protein Trends Predict Treatment Outcome in Patients with Knee Periprosthetic Joint Infection Undergoing Two-Stage Exchange Arthroplasty?

Two-stage exchange arthroplasty is the standard treatment for knee periprosthetic joint infection (PJI). This study aimed to determine whether serial changes in C-reactive protein (CRP) values can predict the prognosis in patients with knee PJI. We retrospectively enrolled 101 patients with knee PJI treated with two-stage exchange arthroplasty at our institution from 2010 to 2016. We excluded patients with spacer complications and confounding factors affecting CRP levels. We tested the association between treatment outcomes and qualitative CRP patterns or quantitative CRP levels. Of the 101 patients, 24 (23.8%) had recurrent PJI and received surgical intervention after two-stage reimplantation. Patients with a fluctuating CRP pattern were more likely to receive antibiotics for a longer period (p < 0.001). There was greater risk of treatment failure if the CRP levels were higher when antibiotics were switched from an intravenous to oral form (p = 0.023). The patients who received antibiotics for longer than six weeks (p = 0.017) were at greater risk of treatment failure after two-stage arthroplasty. Although CRP patterns cannot predict treatment outcomes, CRP fluctuation in the interim period was associated with longer antibiotic duration, which was related to a higher treatment failure rate.

Control of stem cell differentiation by using extrinsic photobiomodulation in conjunction with cell adhesion pattern.

The induction and direction of stem cell differentiation into needed cell phenotypes is the central pillar of tissue engineering for repairing damaged tissues or organs. Conventionally, a special recipe of chemical factors is formulated to achieve this purpose for each specific target cell type. In this work, it is demonstrated that the combination of extrinsic photobiomodulation and collagen-covered microislands could be used to induce differentiation of Wharton's jelly mesenchymal stem cells (WJ-MSCs) with the differentiation direction dictated by the specific island topography without use of chemical factors. Both neurogenic differentiation and adipogenic differentiation could be attained with a rate surpassing that using chemical factors. Application of this method to other cell types is possible by utilizing microislands with a pattern tailored particularly for each specific cell type, rendering it a versatile modality for initiating and guiding stem cell differentiation.

Trend of serum C-reactive protein is associated with treatment outcome of hip Periprosthetic joint infection undergoing two-stage exchange arthroplasty: a case control study.

BACKGROUND: Serum C-reactive protein (CRP) trends are critical for monitoring patients' treatment response following a two-stage exchange arthroplasty for periprosthetic joint infection (PJI) of the hip. However, CRP trends are poorly described in the literature. The primary aim of this study was to identify the relationships between PJI treatment outcomes and our proposed CRP trend definitions, parameters, and microbiological data. The secondary aim was to investigate CRP trends after the occurrence of spacer-related complications. METHODS: We conducted a retrospective review of 74 patients treated with a two-stage exchange protocol for PJI in a tertiary referral joint center between 2014 and 2016. Patients with factors that may affect CRP levels (inflammatory arthritis, concomitant infections, liver and kidney diseases, and intensive care admissions) were excluded. CRP trends were categorized into five types and PJI treatment outcome was defined as "success" or "failure" according to the Delphi criteria. RESULTS: Treatment was successful in 67 patients and failed in 7 patients. Multivariate logistic regression analysis showed that type 5 CRP, defined as serum CRP fluctuation without normalization after first stage surgery (odds ratio [OR]: 17.4; 95% confidence interval [CI]: 2.3-129.7; p = 0.005), and methicillin-resistant Staphylococcus aureus (MRSA; OR: 14.5; 95% CI: 1.6-131.7; p = 0.018) were associated with treatment failure. Spacer-related complications occurred in 18 patients. Of these, 12 had elevated CRP levels at later follow-up, while six had no elevation in CRP levels. CONCLUSIONS: We found that MRSA infection and type 5 CRP were associated with PJI treatment failure.

Outcome and cost analysis of primary total knee arthroplasty in end-stage renal disease patients: A nationwide population-based study.

BACKGROUND: A number of patients with end-stage renal disease (ESRD) undergo total knee arthroplasty (TKA) due to advanced knee joint osteoarthritis. There are few studies describing the incidence, morbidities, mortality rate, and cost analysis regarding ESRD patients receiving TKA. METHODS: We retrospectively retrieved patient data from National Health Insurance Research Database in Taiwan during 2005-2011, and evaluated the outcomes of TKA in patients with (ESRD group) and without ESRD (non-ESRD group). Patients' demographic data, comorbidities, mortality, and in-hospital cost were recorded. RESULTS: A total of 578 TKAs and 110,895 TKAs were identified in the ESRD and non-ESRD group, respectively. The incidence of patients receiving TKA was higher in the ESRD than in non-ESRD group by at least 2 folds. The ESRD group showed significantly more medical complications (pneumonia, peptic ulcer disease, and acute myocardial infarction) after surgery. In prosthesis-related complications, the ESRD group also had more periprosthetic joint infections, and prosthetic loosenings by one year. The one-year mortality rate was more than 6 times higher in the ESRD than in the non-ESRD group. The ESRD group had higher in-hospital medical expense than the non-ESRD group, especially when there were complications, even when the dialysis-related costs were exempted. CONCLUSION: The complication rate, mortality rate, and cost were higher in the ESRD patients receiving TKA. When considering TKA in ESRD patients, it is crucial to weigh the risks against benefits of TKA, and have a thorough discussion with the patients.

Predictors for Unfavorable Early Outcomes in Elective Total Hip Arthroplasty: Does Extreme Body Mass Index Matter?

BACKGROUND: Studies of previous cohorts have demonstrated a controversial association between extreme body mass index (BMI) and complication rates following total hip arthroplasty (THA). The purpose of this study was to compare 30-day perioperative complications in underweight (BMI <18.50 kg/m2), normal-weight (BMI 18.50-24.99 kg/m2), overweight (BMI 25.00-29.99 kg/m2), class I obesity (BMI 30.00-34.99 kg/m2), and morbidly obese (BMI ≥35.00 kg/m2) groups. METHODS: We performed a cohort study including patients who underwent unilateral primary THA by a single surgeon between January 2010 and December 2015 at our institution. We assessed 30-day complications, operation time, operative blood loss, and length of hospital stay. RESULTS: We identified 1565 primary THAs that were performed in patients with varying BMI levels. Compared with the normal-weight patients, the morbidly obese group had a higher 30-day complication rate (8.9% vs. 2.4%), longer operative time (79 minutes vs. 70 minutes), and more blood loss (376 mL vs. 302 mL). Underweight patients did not present any 30-day complications, and there were no differences among underweight and normal-weight patients regarding complication rates, operative time, or blood loss. The mean length of hospital stay was comparable among the different BMI groups. In the multivariate regression model, higher BMI was not associated with a higher risk of 30-day complications. Independent risk factors for 30-day complications were advanced age, prolonged operative time, and cardiovascular comorbidities. CONCLUSION: Although increased operative time, blood loss, and perioperative complications were seen in the morbidly obese patients, BMI alone was not an independent risk factor for a higher 30-day complication rate. Therefore, our data suggest clinicians should make elderly patients aware of increased 30-day complications before the procedure, particularly those with cardiovascular comorbidities. Withholding THA solely on the basis of BMI is not justified.

Potential usefulness of 68Ga-citrate PET/CT in detecting infected lower limb prostheses.

BACKGROUND: Prosthetic joint infections may lead to failures of total joint arthroplasty. Radionuclide imaging can play a diagnostic role in identifying such infections, which require two-stage exchange arthroplasty (instead of simple revision surgery performed in non-infected cases). Although 18F-FDG PET/CT has emerged as a novel diagnostic tool in this setting, the clinical usefulness of 68Ga-citrate PET/CT has not been previously investigated. This single-center prospective study was designed to address this issue. METHODS: Between January 2016 and October 2017, we examined 34 patients with clinically proven or suspected prosthetic hip/knee joint infections scheduled to undergo surgery. All patients underwent 68Ga-citrate PET/CT scans and sequential 18F-FDG PET/CT imaging for comparative purposes. Intraoperative findings and the results of microbiological analyses of surgical specimens served as gold standard. The diagnostic results were examined according to (1) image interpretation based on radiotracer uptake patterns and (2) quantitative analysis using volumes of interest (VOIs) to calculate standard uptake values (SUVs) and metabolic volumes (MVs). RESULTS: A total of 26 (76%) patients were diagnosed as having infections. Based on radiotracer uptake pattern criteria, the sensitivity, specificity, and accuracy of 68Ga-citrate PET/CT and 18F-FDG PET/CT were 92%, 88%, and 91% and 100%, 38%, and 85%, respectively. MV was significantly higher in the infected group when 68Ga-citrate PET/CT was used (422.45 vs. 303.65 cm3, p = 0.027), whereas no significant differences were observed on 18F-FDG PET/CT. According to receiver operating characteristic (ROC) curve analysis, a cut-off value of 370.86 for MV resulted in a sensitivity of 61.5% and a specificity of 87.5% (area under curve: 0.75, 95% confidence interval: 0.57-0.88, p = 0.035). CONCLUSIONS: Subject to future confirmation, our data provide preliminary evidence that 68Ga-citrate PET/CT may have a complimentary role to 18F-FDG PET/CT in detecting prosthetic joint infections, being characterized by a higher specificity and the possibility to discriminate between an infectious condition and sterile inflammation. TRIAL REGISTRATION: This prospective study was registered at clinicaltrials.gov (registration number: NCT02855190 ).

One- and two-stage surgical revision of peri-prosthetic joint infection of the hip: a pooled individual participant data analysis of 44 cohort studies.

One-stage and two-stage revision strategies are the two main options for treating established chronic peri-prosthetic joint infection (PJI) of the hip; however, there is uncertainty regarding which is the best treatment option. We aimed to compare the risk of re-infection between the two revision strategies using pooled individual participant data (IPD). Observational cohort studies with PJI of the hip treated exclusively by one- or two-stage revision and reporting re-infection outcomes were retrieved by searching MEDLINE, EMBASE, Web of Science, The Cochrane Library, and the WHO International Clinical Trials Registry Platform; as well as email contact with investigators. We analysed IPD of 1856 participants with PJI of the hip from 44 cohorts across four continents. The primary outcome was re-infection (recurrence of infection by the same organism(s) and/or re-infection with a new organism(s)). Hazard ratios (HRs) for re-infection were calculated using Cox proportional frailty hazards models. After a median follow-up of 3.7 years, 222 re-infections were recorded. Re-infection rates per 1000 person-years of follow-up were 16.8 (95% CI 13.6-20.7) and 32.3 (95% CI 27.3-38.3) for one-stage and two-stage strategies respectively. The age- and sex-adjusted HR of re-infection for two-stage revision was 1.70 (0.58-5.00) when compared with one-stage revision. The association remained consistently absent after further adjustment for potential confounders. The HRs did not vary importantly in clinically relevant subgroups. Analysis of pooled individual patient data suggest that a one-stage revision strategy may be as effective as a two-stage revision strategy in treating PJI of the hip.

Nasal colonization and bacterial contamination of mobile phones carried by medical staff in the operating room.

BACKGROUND: Mobile phones (MPs) have been an essential part of the lives of healthcare professionals and have improved communication, collaboration, and sharing of information. Nonetheless, the widespread use of MPs in hospitals has raised concerns of nosocomial infections, especially in areas requiring the highest hygienic standards such as operating rooms (ORs). This study evaluated the incidence of bacterial contamination of the MPs carried by medical staff working in the OR and determined its association with bacterial colonization of this personnel. METHODS: This is an observational cohort study. Medical staffs working in the OR were asked to take bacterial cultures from their MPs, anterior nares, and dominant hands. To identify the relation between MP contamination and bacterial colonization of the medical staff, genotyping of Staphylococcus aureus (SA) was done via Staphylococcus protein A gene (spa) typing and pulsed-field gel electrophoresis (PFGE). RESULTS: A total of 216 swab samples taken from 72 medical-staff members were analyzed. The culture-positive rate was 98.1% (212/216). In 59 (27.3%) samples, the bacteria were possible clinical pathogens. The anterior nares were the most common site of colonization by clinical pathogens (58.3%, 42/72), followed by MPs (13.9%, 10/72) and the dominant hand (9.7%, 7/72). SA was the most commonly isolated clinical pathogen and was found in 43 (19.9%) samples. In 66 (94.3%) of the 70 staff members for whom bacteria were detected on their MPs, the same bacteria were detected in nares or hand. Among 31 medical staff who were carriers of SA in the anterior nares or dominant hand, 8 (25.8%) were found to have SA on their MPs, and genotyping confirmed the same SA strain in 7 (87.5%) of them. CONCLUSION: A high rate of bacterial nasal colonization and MPs contamination were found among the OR medical staff. An MP may be a reservoir for pathogen contamination in the OR.

Superior Survivorship of Cementless vs Cemented Diaphyseal Fixed Modular Rotating-Hinged Knee Megaprosthesis at 7 Years' Follow-Up.

BACKGROUND: Total knee arthroplasty in the presence of a huge bone and soft-tissue defect is always a challenge. A rotating-hinged (RH) megaprosthesis is indicated for extensive soft-tissue loss with a huge bone defect such as a primary or metastatic neoplasm of the bone, repeat periprosthetic joint infection, or extensive trauma of the knee. However, the reported survivorship of RH megaprostheses is unsatisfactory. The aim of this study was to evaluate the survivorship of megaprostheses and the factors that contribute to implant survival. METHODS: A total of 103 RH knee megaprostheses were implanted in 85 patients between January 2001 and June 2013. Each prosthesis was a modular custom-made (CM) cemented or cementless fixed total knee system (United USTAR system). Clinical results and prosthesis survivorship were evaluated between the 2 groups. RESULTS: The overall survivorship of this CM knee megaprosthesis was 91% at 2 years, 83% at 5 years, and 68% at 10 years. The cumulative component survivorship was 87% in the cemented group and 96% in the cementless group at 2 years compared with 75% in the cemented group and 94% in the cementless group at 5 years. The failure mechanism included loosening in 5 and breakage in 6 patients in the cemented stem group. The survivorship of the cementless fixed component was significantly superior to that of the cemented fixed component. CONCLUSION: Our data suggest that modular RHCM knee megaprosthesis provides an acceptable clinical result. A diaphyseal long stem with cementless fixation was more reliable and durable than its cemented counterpart.

Elution and Mechanical Strength of Vancomycin-Loaded Bone Cement: In Vitro Study of the Influence of Brand Combination.

Antibiotic-loaded bone cement (ALBC) is widely used in orthopaedic surgery for both prevention and treatment of infection. Little is known about the effect of different brand combinations of antibiotic and bone cement on the elution profile and mechanical strength of ALBC. Standardized specimens that consisted of one of the 4 brands of bone cement and one of the 3 brands of vancomycin were fashioned, producing 12 combinations of ALBC. Two dosages of vancomycin in 40g bone cement were used to represent the high (4g vancomycin) and low (1g vancomycin) dose groups. Concentrations of vancomycin elution from ALBC was measured for up to 336 hours. The ultimate compression strength was tested at axial compression using a material testing machine before and after elution. In both high-dose and low-dose groups, Lyo-Vancin in PALACOS bone cement resulted in the highest cumulative elution and Vanco in Simplex P bone cement resulted in the lowest elution (458% and 65% higher in high- and low-dose groups, respectively). The mechanical strength was not significantly compromised in all groups with low dose vancomycin (range: 70.31 ± 2.74 MPa to 87.28 ± 8.26MPa after elution). However, with the addition of high dose vancomycin, there was a mixed amount of reduction in the ultimate compression strength after cement aging, ranging from 5% (Vanco in Simplex P, 81.10 ± 0.48 MPa after elution) to 38% (Sterile vancomycin in CMW, 60.94 ± 5.74 MPa after elution). We concluded that the selection of brands of vancomycin and bone cement has a great impact on the release efficacy and mechanical strength of ALBC.

Metal ion concentrations and semen quality in patients undergoing hip arthroplasty: A prospective comparison between metal-on-metal and metal-on-polyethylene implants.

PURPOSE: The widespread usage of metal-on-metal (MoM) articulations in total hip arthroplasty (THA) has been tempered by concerns of increased metal ion production. The purpose of the study is to evaluate the influence of metal ion exposure on semen quality in young male patients undergoing THA. METHODS: Male patients who were scheduled for unilateral THA and aged between 20 and 45 years were prospectively enrolled. Patients were sorted into MoM and metal-on-polyethylene (MoP) groups with equal case number. Semen and blood metal ion levels were measured and sperm analysis was performed before, 6 months after, and 1 year after surgery. RESULTS: Compared to preoperative baseline, patients (n = 50) in both groups had increased cobalt (Co) and chromium (Cr) concentrations in blood and seminal fluid after surgery. Between-group comparisons at 6 months and 1 year after surgery showed that patients in the MoM group both had a greater Co concentration in blood and semen and a greater Cr concentration in blood and semen. Patients receiving MoM prosthesis had a reduced percentage of morphologically normal sperm, and decreases from the preoperative level (44.7%) were significant at 6 months (36.8%, p = 0.03) and 1 year (33.8%, p = 0.004). CONCLUSIONS: Our data shows a significantly greater concentration of metal ion in blood and semen in patients with MoM prosthesis with a reduced percentage of morphologically normal sperm. Despite small effects on sperm quality, some concerns remain. Further studies are necessary to determine sources of metal ion and to investigate effects on male fertility.

Outcomes and second-look arthroscopic evaluation after combined arthroscopic treatment of tibial plateau and tibial eminence avulsion fractures: a 5-year minimal follow-up.

BACKGROUND: Tibial eminence avulsion fracture often co-occurs with tibial plateau fracture, which leads to difficult concomitant management. The value of simultaneous arthroscopy-assisted treatment continues to be debated despite its theoretical advantages. We describe a simple arthroscopic suture fixation technique and hypothesize that simultaneous treatment is beneficial. METHODS: Patients with a tibial eminence avulsion fracture and a concurrent tibial plateau fracture who underwent simultaneous arthroscopically assisted treatment between 2005 and 2008 were enrolled in this retrospective study. Second-look arthroscopic evaluation and Rasmussen scores of clinical and radiographic parameters were used to assess simultaneous treatment. RESULTS: Forty-one patients (41 knees) met the inclusion criteria. All 41 fractures were successfully united. All patients had side-to-side differences of less than 3 mm and negative findings in Lachman and pivot-shift tests at their final follow-up. The mean postoperative Rasmussen clinical score was 27.3 (range: 19-30), and the mean radiologic score was 16.5 (range: 12-18). Clinical and radiographic outcomes in 98 % of the patients were good or excellent. There were no complications directly associated with arthroscopy in any patient. CONCLUSIONS: Simultaneous arthroscopic suture fixation of associated tibial eminence avulsion fracture did not interfere with the plates and screws used to stabilize the tibial plateau fracture. It gave the knee joint adequate stability, minimal surgical morbidity, and satisfactory radiographic and clinical outcomes in a minimum follow-up of 5 years and in the arthroscopic second-look assessments.

Two-Stage Revision Arthroplasty for Periprosthetic Hip Infection: Mean Follow-Up of Ten Years.

BACKGROUND: Two-stage revision hip arthroplasty is the gold standard for treatment of patients with chronic periprosthetic joint infection (PJI), but few studies have reported outcomes beyond short-term follow-up. METHODS: A total of 155 patients who underwent two-stage revision arthroplasty for chronic PJI in 157 hips were retrospectively enrolled in this study between January 2001 and December 2010. The mean patient age was 57.5 years, the mean prosthetic age was 3.6 years, and the interim interval was 17.8 weeks. These patients were followed up for an average of 9.7 years. RESULTS: At the latest follow-up, 91.7% of the patients were free of infection. The mean Harris hip score improved significantly from 28.3 points before operation to 85.7 points at the latest follow-up. Radiographically, there was aseptic loosening of the stem or acetabular components in 4 patients. In the multivariate survival analysis using a Cox regression model, repeated debridement before final reconstruction, an inadequate interim period, bacteriuria or pyuria, and cirrhosis were found to be the independent risk factors for treatment failure. CONCLUSION: Our data show that two-stage revision hip arthroplasty provides reliable eradication of infection and durable reconstruction of the joint in patients with PJI caused by a variety of pathogens.

Results of instrumented posterolateral fusion in treatment of lumbar spondylolisthesis with and without segmental kyphosis: A retrospective investigation.

BACKGROUND: Treatment by posterolateral fusion (PLF) with pedicle-screw instrumentation can be unsuccessful in one-segment and low-grade lumbar spondylolisthesis. Segmental kyphosis, either rigid or dynamic, was hypothesized to be one of the factors interfering with the fusion results. METHODS: From 2004 to 2005, 239 patients with single-segment and low-grade spondylolisthesis were recruited and divided into two groups: Group 1 consisting of 129 patients without segmental kyphosis and group 2 consisting of 110 patients with segmental kyphosis. All patients underwent instrumented PLF at the same medical institute, and the average follow-up period was 31 ± 19 months. We obtained plain radiographs of the lumbosacral spine with the anteroposterior view, the lateral view, and the dynamic flexion-extension views before the operation and during the follow-ups. The results of PLF in the two groups were then compared. RESULTS: There was no significant difference in the demographic data of the two groups, except for gender distribution. The osseous fusion rates were 90.7% in group 1 and 68.2% in group 2 (p < 0.001). CONCLUSION: Instrumented PLF resulted in significantly higher osseous fusion rate in patients without segmental kyphosis than in the patients with segmental kyphosis. For the patients with sagittal imbalance, such as rigid or dynamic kyphosis, pedicle-screw fixation cannot ensure successful PLF. Interbody fusion by the posterior lumbar interbody fusion or transforaminal lumbar interbody fusion technique might help overcome this problem.

Arthroscopic suture fixation for avulsion fractures in the tibial attachment of the posterior cruciate ligament.

PURPOSE: The purpose of the study was to highlight our surgical technique of arthroscopic suture fixation for acute tibial eminence posterior cruciate ligament (PCL) avulsion fractures, clinical and radiographic outcomes, and complication rates. METHODS: This prospective study enrolled patients who had undergone arthroscopic reduction and suture fixation by use of 4 No. 5 Ethibond sutures (Ethicon, Somerville, NJ) for image-proven displaced PCL attachment fractures of the tibial eminence with posterior knee instability of grade II or higher. The mean follow-up period was 36 months (range, 24 to 45 months). Follow-up assessment included 3 different functional scores, KT-1000 arthrometry (MEDmetric, San Diego, CA), and radiographic evaluation. RESULTS: The mean preoperative Lysholm score in the 36 patients was 35 (range, 26 to 55); the mean postoperative Lysholm score was 95 (range, 80 to 100). The mean preinjury and preoperative Tegner scores in the 36 patients were 7.4 ± 1.6 (range, 5 to 9) and 3.2 ± 1.5 (range, 2 to 5), respectively. The mean postoperative Tegner score was 7.0 ± 1.8 (range, 5 to 9). At the final follow-up, the International Knee Documentation Committee scores were observed to be normal (grade A) or nearly normal (grade B) in 33 patients (91.7%) and abnormal (grade C) in 3 patients (8.3%). All 36 fractures achieved union within 3 months. No significant complications such as arthrofibrosis, loss of initial fixation, or wound infection were noted. CONCLUSIONS: Treatment of tibial PCL avulsion fractures by arthroscopic suture fixation is a successful technique to restore tibial avulsion injuries of the PCL with well-documented radiographic healing, good clinical outcomes, and low complication rates. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Seeding of a soft-x-ray laser in a plasma waveguide by high harmonic generation.

A strongly saturated waveguide-based optical-field-ionization soft-x-ray laser seeded by high harmonic generation was demonstrated for Ni-like Kr lasing at 32.8 nm. Compared with the same laser seeded only with spontaneous emission, seeding with high harmonics yields much smaller divergence, enhanced spatial coherence, and controlled polarization. The integration of high harmonic seeding, optically preformed plasma waveguide, and optical-field-ionization pumping forms one of the optimal archetypes of an ultrashort-pulse soft-x-ray laser.

Single-shot soft-x-ray digital holographic microscopy with an adjustable field of view and magnification.

Single-shot digital holographic microscopy with an adjustable field of view and magnification was demonstrated by using a tabletop 32.8 nm soft-x-ray laser. The holographic images were reconstructed with a two-dimensional fast-Fourier-transform algorithm, and a new configuration of imaging was developed to overcome the pixel-size limit of the recording device without reducing the effective NA. The image of an atomic-force-microscope cantilever was reconstructed with a lateral resolution of 480 nm, and the phase contrast image of a 20 nm carbon mesh foil demonstrated that profiles of sample thickness can be reconstructed with few-nanometers uncertainty. The ultrashort x-ray pulse duration combined with single-shot capability offers great advantage for flash imaging of delicate samples.