Optimizing Droplet-Based Electricity Generator via a Low Sticky Hydrophobic Droplet-Impacted Surface.

Droplet-based electricity generators (DEGs) are increasingly recognized for their potential in converting renewable energy sources. This study explores the interplay of surface hydrophobicity and stickiness in improving DEG efficiency. It find that the high-performance C-WaxDEGs leverage both these properties. Specifically, DEGs incorporating polydimethylsiloxane (PDMS) with carnauba wax (C-wax) exhibit increased output as surface stickiness decreases. Through experimental comparisons, PDMS with 1wt.% C-wax demonstrated a significant power output increase from 0.07 to 1.2 W m- 2, which attribute to the minimized adhesion between water molecules and the polymer surface, achieved by embedding C-wax into PDMS surface to form microstructures. This improvement in DEG performance is notable even among samples with similar surface potentials and contact angles, suggesting that C-wax's primary contribution is in reducing surface stickiness rather than altering other surface properties. The further investigations into the C-WaxDEG variant with 1wt.% C-wax PDMS uncover its potential as a sensor for water quality parameters such as temperature, pH, and heavy metal ion concentration. These findings open avenues for the integration of C-WaxDEGs into flexible electronic devices aimed at environmental monitoring.

Assessing lateral femoral condyle cartilage prior to medial UKA: MRI vs. Valgus stress radiograph.

BACKGROUND: The cartilage quality of the lateral compartment needs to be clarified prior to medial unicompartmental knee arthroplasty (UKA). Valgus stress radiograph has been recommended as the preferred tool. Some studies also show that magnetic resonance imaging (MRI) has a higher diagnostic value. So, we conducted this study to compare whether valgus stress radiographic lateral joint space width (LJSW) and MRI grading can accurately reflect cartilage quality and its screening value for UKA-suitable patients. METHODS: One hundred and thirty eight knees proposed for UKA were enrolled prospectively. Valgus stress radiograph was taken to measure LJSW. LJSW > 4 mm was considered normal and suitable for UKA. For weight-bearing area cartilage of lateral femoral condyle, Recht grade was assessed by MRI preoperatively. Recht grades ≤ 2 were treated as non-high-grade injuries while Recht grades > 2 were treated as high-grade injuries. Outerbridge grade was the gold standard and was assessed intraoperatively. Patients with Outerbridge grades 0-2 (non-high-grade injuries) underwent UKA, and patients with Outerbridge grades 3-4 (high-grade injuries) underwent total knee arthroplasty (TKA). The diagnostic parameters of valgus stress radiograph and MRI for the selection of UKA candidates were calculated, and receiver operating characteristic curves were drawn. P < 0.05 was considered significant. RESULTS: Of 138 knees, 120 underwent UKAs, and 18 underwent TKAs. In terms of selecting UKA candidates, the sensitivity was close between MRI (95.0%) and valgus stress radiograph (96.7%), and the specificity, accuracy, positive predictive value and negative predictive value of MRI (94.4%, 94.9%, 99.1%, 73.9%, respectively) were higher than that of valgus stress radiograph (5.9%, 85.5%, 88.0%, 20.0%, respectively). The difference in area under the curve (AUC) between MRI (0.950) and LJSW (0.602) was significant (P = 0.001). CONCLUSION: Compared with valgus stress radiograph, MRI has excellent evaluation value in diagnosing lateral weight-bearing cartilage injuries and can be used as a reliable tool for selecting suitable UKA patients.

How much the leg length has changed after the MOUKA through measurement of the full length radiographs? Beware of splicing error.

BACKGROUND: Leg length change after knee arthroplasty is one of the most concerned problems for patients and doctors. However, as there was only one literture focused on the leg length change after unicompartmental knee arthroplasty, we aimed to clarify the leg length change after medial mobile-bearing unicompartmental knee arthroplasty (MOUKA) using a novel double calibration method. METHODS: We enrolled patients who underwent MOUKA and had taken full-length radiographs in a standing position prior to and at 3 months after the operation. We eliminated the magnification by a calibrator and corrected the longitudinal splicing error by measuring the femur and tibia lengths before and after operation. Perceived leg length change was collected 3 months after operation. Bearing thickness, preoperative joint line convergence angle, preoperative and postoperative varus angles, flexion contracture and Oxford knee score (OKS) were also collected. RESULTS: From June 2021 to February 2022, 87 patients were enrolled.76 (87.4%) of them showed an increase with an average of 0.32 cm (range from -0.30 cm to 1.05 cm) in leg length change. The lengthening was strongly correlated with the degree of varus deformity and its correction value (r = 0.81&0.92, P < 0.01). Only 4 (4.6%) patients perceived leg length lengthening after operation. There was no difference in OKS between the patients who had an increase in leg length and those who had a decrease (P = 0.99). CONCLUSIONS: Majority of patients only experienced a slight increase in leg length after MOUKA, and such an increase did not affect patients' perception and short-term function.

Using MRI to differentiate upper-lateral intracavitary pregnancy and interstitial pregnancy for the patients with pregnancies in the uterotubal junction during the first trimester.

OBJECTIVES: To retrospectively evaluate the diagnostic value of MRI for the uterotubal junctional pregnancies during the first trimester. METHODS: This retrospective study involved 59 patients (January 2016 to July 2021) with a preoperative imaging diagnosis of uterotubal junctional pregnancy. Using operative and pathological reports as the reference standard, we identified 22 patients with upper-lateral intracavitary (angular) pregnancy and 37 patients with interstitial pregnancy. Two senior radiologists, blinded to the patients' information, reviewed the MRI images and determined each MRI feature based on the original interpretation criteria. Any disagreement was resolved by discussion to achieve a consensus. The sensitivity and specificity of each MRI feature were calculated according to the reference standard. RESULTS: The endometrial thickness in the upper-lateral intracavitary pregnancy group was larger than in the interstitial group (p = 0.001). The cutoff value of the endometrial thickness was 11.5 mm with a sensitivity, specificity, and area under the curve that were 77.3%, 64.9%, and 0.743, respectively. Two key features to diagnose upper-lateral intracavitary pregnancy were "medial free edge" and "medial free edge plus above-cutoff endometrial thickness." The sensitivity and specificity of the medial free edge were 100% and 94.9%, respectively. The sensitivity and specificity of the medial free edge plus above-cutoff endometrial thickness were 77.3% and 100%, respectively. The key feature to diagnose interstitial pregnancy was an "intact lateral junctional zone," of which the sensitivity and specificity were 94.6% and 100%, respectively. CONCLUSIONS: MRI can be used to differentiate the upper-lateral intracavitary pregnancy and interstitial pregnancy during the first trimester. KEY POINTS: • We demonstrated MRI diagnostic criteria for the interstitial pregnancy and upper-lateral intracavitary pregnancy. • MRI might be used to identify the complex interstitial pregnancies, those with a gestational sac protruding into the uterine cavity.

Does diabetes mellitus increase the incidence of early thrombosis in deep vein following unicompartmental knee arthroplasty: a retrospective cohort study.

BACKGROUND: Many patients following unicompartmental knee arthroplasty (UKA) also suffer from diabetes mellitus, which may lead to an increased likelihood of postoperative deep venous thrombosis (DVT). Therefore, we evaluated whether DVT incidence would increase 3 days following UKA in diabetic patients. METHODS: Patients who underwent UKA from August 2018 to September 2021 in our hospital were retrospectively included. Age, gender, body mass index, hypertension, mode of anesthesia, surgery time, intraoperative blood loss, tourniquet pressure and time, and glycosylated hemoglobin concentration were recorded as confounders. We compared the incidence and type of DVT between non-diabetic and diabetic patients and evaluated the effect of glycosylated hemoglobin levels on DVT. RESULTS: Of all the 224 patients, 96 had diabetes and 128 did not. Within 3 days after surgery, DVT occurred in 25 cases in the diabetic group and 17 cases in the non-diabetic group (p < 0.05), and the difference mainly exists in the lower limbs on the surgical side. Logistic regression analysis demonstrated that the risk of DVT in the diabetic group was 4.50 times higher compared with the non-diabetic group. For every 1 unit increase of glycosylated hemoglobin, the incidence of DVT increased 2.35 times. Differences in age, gender, body mass index, hypertension, mode of anesthesia, surgery time, intraoperative blood loss, tourniquet pressure, and time between the two groups were not significant. CONCLUSIONS: The incidence of DVT in diabetic patients within 3 days after UKA was significantly higher than that in non-diabetic patients and was proportional to the concentration of glycosylated hemoglobin.

Slight cartilage damage in weight-bearing area of lateral femoral condyle do not compromise short-term outcomes of medial unicompartmental knee arthroplasty.

INTRODUCTION: Medial unicompartmental knee arthroplasty (mUKA) requires full-thickness cartilage in the lateral compartment, but slight damage of the cartilage surface can be ignored. However, as this statement lacks literature support, we investigated whether slight cartilage damages in the weight-bearing area of the lateral femoral condyle would affect the outcome of mUKAs. MATERIALS AND METHODS: Outerbridge grading was performed on the cartilage in the weight-bearing area of the lateral femoral condyle intraoperatively. The patients, grouped as normal or as having lateral condyle cartilage of Outerbridge grade 1-2 (slight cartilage damage), underwent mUKA. Full-length lower extremity radiographs were taken and hip-knee-ankle angles (HKAAs) were measured both preoperatively and postoperatively. Using magnetic resonance imaging, the lateral meniscal extrusion distance was also measured. In addition, the Oxford Knee Score (OKS) was assessed preoperatively and at the last follow-up, in addition to the patient satisfaction assessment. RESULTS: We enrolled 152 knees of 142 patients proposed for mUKAs. The mean age of participants was 69.5 years (51-89 years) and they were followed up for a mean of 25.4 months (15-44 months). There was no significant difference in preoperative (p = 0.746) and postoperative (p = 0.202) mean OKS between the normal, Outerbridge grade 1 and Outerbridge grade 2 groups. While the normal group had a higher change in OKS than the group with cartilage damage, this difference was not significant (p = 0.910). The UKA corrected the patients' mean HKAA from 171.1° (preoperatively) to 176.1° (postoperatively). From all patients, only four had slight lateral meniscus extrusion with MEDs of ≤ 0.25 mm. With the exception of one patient with a poor outcome in normal group, the rest were satisfied with the outcome of mUKA. No patients had prosthesis-related complications or revision surgery. CONCLUSIONS: Cartilage damage of Outerbridge grade 1 and grade 2 in the weight-bearing area of the lateral femoral condyle will not compromise the short-term outcome of medial mobile-bearing UKA.

Hybrid Oxford unicompartmental knee arthroplasty has lower residual cement extrusion than cemented arthroplasty in treating end-stage unicompartmental knee osteoarthritis.

BACKGROUND: Hybrid Oxford unicompartmental knee arthroplasty (OUKA) consists of cementless femoral prostheses and cemented tibial prostheses. Although a hybrid OUKA has been used in clinical practice, the clinical outcome has not been reported. The purpose of this study was to compare the short-term clinical outcomes and rate of residual bone cement extrusion between hybrid and cemented prostheses and analyse the possible reasons for differences between outcomes. METHODS: A total of 128 knees (118 patients) with end-stage osteoarthritis were included in this study, of which underwent consecutive operations using unicondylar Oxford phase 3 implants from July 2017 and September 2019 in our centre. Follow-up was performed at 6 weeks, 3 and 6 months, 1 year and every year after operation, and complications and changes in the Oxford knee score (OKS) were recorded. The OKS of the two groups was analysed by the generalized estimating equation approach. Prosthesis-based standard fluoroscopy was performed in a timely manner after each operation, and the rate of residual cement extrusion of the two groups was estimated using T-tests and a multivariate regression analysis. RESULTS: Excluding the cases that lost follow-up, a total of 120 knees (65 in hybrid group and 55 in cemented group) were included in the analysis. There was no statistically significant difference in patient characteristics between the two groups (p > 0.05). The average follow-up time was 23.4 months (and ranged from 12 to 38 months). As of the last follow-up, there were no complications, such as dislocation, fracture, prosthesis loosening and subsidence, but one patient in the cemented group experienced symptoms caused by residual loose cement. Postoperative OKS in both groups improved significantly (p < 0.001). There was no significant difference in the OKS at any point during the follow-up or in the improvement of the OKS between the two groups (p > 0.05). Residual cement was mainly extruded behind the tibial prosthesis. The rate of hybrid periprosthetic residual cement extrusion was significantly lower in the hybrid group than in the cemented group, and the difference was statistically significant (OR = 3.38; p = 0.014). CONCLUSIONS: Hybrid OUKA is as effective as cemented OUKA in the short term after operation and can significantly reduce the residual cement extrusion rate around the tibial prosthesis.

An elderly female with adult-onset Still's disease initially misdiagnosed as prosthetic joint infection after total knee arthroplasty: lessons in differential diagnosis and treatment.

BACKGROUND: High fever, knee swelling and pain after knee arthroplasty are often considered as symptoms of acute prosthetic joint infection. However, similar symptoms can also present as primary manifestations of adult-onset Still's disease, which creates some interference in differential diagnosis. To our knowledge, this is the first published case of misdiagnosis of adult Still's disease after total knee arthroplasty, who was initially misdiagnosed as an prosthetic joint infection due to the above-mentioned symptoms. The symptoms of the knee infection was not relieve after several revisions and continous antibiotic treatment. Finally, after several consultations and repeated evaluation it was diagnosed as adult-onset Still's disease. CASE PRESENTATION: A 77-year-old female who underwent bilateral total knee arthroplasty 6 years ago was admitted to our hospital with high fever, right knee effusion and painful knee. Based on the results of joint fluid aspiration and culture, we treated the right knee as acute hematogenous prosthetic joint infection. After three debridement and revision surgeries, the patient's symptoms continued to persist. Subsequent manifestations of other symptoms such as typical rash and sore throat and laboratory examination suggested the possibility of adult-onset Still's disease. So she underwent diagnostic steroid hormone therapy at the recommendation of a rheumatologist, and a final revision was performed after symptom was controlled. At the one-year follow-up, the patient's symptoms completely resolved and the knee revision was functioning well. CONCLUSIONS: When joint swelling and pain occurs after knee arthroplasty, the possibility of joint infection should not only be considered, but rheumatic autoimmune diseases should also be differentiated. Because the manifestations of joint infection and rheumatic immune disease sometimes overlap highly, when reasonable treatment over a period of time fails to relieve symptoms and signs, we should notice subtle differences in symptoms and laborotary tests and look for other diagnostic possibilities in time.

In Vitro Application of a Wireless Sensor in Flexion-Extension Gap Balance of Unicompartmental Knee Arthroplasty.

Unicompartmental knee arthroplasty (UKA) is an effective treatment for end-stage anteromedial osteoarthritis (AMOA). The key to UKA is the flexion-extension gap balance, which is closely related to postoperative complications such as bearing dislocation, bearing wear, and arthritis progression. The traditional gap balance assessment is performed by indirectly sensing the tension of the medial collateral ligament by a gap gauge. It relies on the surgeon's feel and experience, which is imprecise and difficult for beginners. To accurately assess the flexion-extension gap balance of UKA, we developed a wireless sensor combination consisting of a metal base, a pressure sensor, and a cushion block. After osteotomy, the insertion of a wireless sensor combination allows the real-time measurement of intra-articular pressure. It accurately quantifies the flexion-extension gap balance parameters to guide further femur grinding and tibia osteotomy, to improve the accuracy of gap balance. We conducted an in vitro experiment with the wireless sensor combination. the results showed that there was a difference of 11.3 N after applying the traditional method of flexion-extension gap balance performed by an experienced expert.

Valgus Stress Radiograph Can Predict Alignment Change of Medial Mobile-Bearing Unicompartmental Knee Arthroplasty.

OBJECTIVE: Finding reliable tools to predict alignment change after medial mobile-bearing unicompartmental knee arthroplasty (UKA) can help surgeons avoid under- or over-correction. This prospective study aimed to investigate whether the parameters related to medial collateral ligament tension on valgus stress radiograph can predict the alignment change of medial mobile-bearing UKA and establish a prediction model. METHODS: This study prospectively included the patients undergoing medial mobile-bearing UKA for knee osteoarthritis from November 2018 and April 2021. Patients took valgus stress radiograph and MRI preoperatively and took full-length weight-bearing anterior-posterior radiograph of the lower extremity preoperatively and postoperatively. The medial joint space width (MJSW) on valgus stress radiograph, area of femoral and tibial osteophyte on MRI, medial extrusion distance (MED) of the meniscus on MRI, and the change in hip-knee-ankle angle (∆HKAA) were measured. Factors influencing ∆HKAA were analyzed by correlation analysis. Univariable and multivariable linear regression analysis was performed to establish a prediction model of ∆HKAA. RESULTS: One hundred and seven knees were included. On average, the preoperative HKAA was 170.84° ± 3.73°, and UKA corrected the alignment to 175.16° ± 3.21° postoperatively (p < 0.001), with ∆HKAA of 4.33° ± 1.93°. Correlation analysis showed that ∆HKAA correlated with MJSW (r = 0.628, p < 0.001), MED (r = 0.262, p < 0.001), and tibial osteophyte area (r = 0.235, p < 0.001). The prediction model for ∆HKAA was obtained by multivariable linear regression: ∆HKAA = -2.003 + 0.947 × MJSW(mm) + 1.838 × total osteophyte area(cm2 ). CONCLUSION: Valgus stress radiographic MJSW and osteophyte area are correlated to the alignment change of medial mobile-bearing UKA. The prediction model for HKAA change is: ∆HKAA = -2.003 + 0.947 × MJSW(mm) + 1.838 × total osteophyte area(cm2 ).

Staged open reduction and internal fixation with double-locking plates to treat bilateral distal femur periprosthetic fractures after total knee arthroplasty: A case report.

Background: The incidence of periprosthetic fractures after total knee arthroplasty (TKA) increases in parallel with the number of procedures. Comminuted fractures along the primary fracture line extending to the edge of the prosthesis are challenging, and bilateral fractures are rarely reported, especially with open injuries. Case presentation: A 65-year-old female had undergone bilateral TKA in our hospital 5 years before admission. She was admitted with a traumatic bilateral Rorabeck type II B distal femur periprosthetic fracture (closed right, open left, Gustilo II) and was treated with bilateral staged open reduction and internal fixation (ORIF) with double-locking plates. The patient experienced a prolonged delayed fracture union and finally healed around 21 months postoperatively. The function was satisfactory after 4 years of follow-up. Conclusion: ORIF with double-locking plates can be used to treat Rorabeck II B periprosthetic fracture where the primary fracture line extends beyond the edge of the prosthesis; however, there may be delayed healing or nonunion. Patients need to undergo long-term rehabilitation and endure long disability times and require good rehabilitation nursing care. Once they achieve bone healing, the treatment achieves bone preservation and substantial prosthesis survival.

Does the correction angle affect hidden blood loss in HTO?

BACKGROUND: High tibial osteotomy (HTO) has a history of nearly 60 years and has been widely used in clinical practice. Biplanar open wedge high tibial osteotomy (BOWHTO), which evolved from HTO, is an important therapy for the knee osteoarthritis. In our previous research, we found that the decrease of hemoglobin levels after high tibial osteotomy ranges from between 17 to 41 g/L, but this is highly inconsistent with the intraoperative bleeding and postoperative drainage observed in clinical practice. The purpose of this study was to investigate the perioperative hidden blood loss (HBL) after biplanar open wedge high tibial osteotomy (BOWHTO), as well as to study the effect of the actual correction angle on blood loss. METHODS: A retrospective analysis was performed on 21 patients who underwent BOWHTO for osteoarthritis of the knee due to proximal tibia deformity. Gross equation was used to calculate the perioperative total blood loss (TBL) and HBL. The actual correction angle was measured by postoperative anteroposterior radiograph. The correlation between HBL and correction angle was determined through correlation analysis. RESULTS: The TBL was 823.5 ± 348.7 mL and the HBL was 601.6 ± 297.3 mL, total hemoglobin loss was 25.0 ± 10.7 g/L, and the mean HBL/patient's blood volume (H/P) was 13.19 ± 5.56% for 21 patients. The correlation coefficient of correction angle and H/P is statistically significant (|r| = 0.678, P = 0.001). CONCLUSIONS: The actual total blood loss after BOWHTO was significantly higher than the observed, and the HBL was objective existent after BOWHTO. The proportion of H/P is positively correlated with the correction angle.