Leukocyte Esterase Strip Quantitative Detection Based on RGB Photometry is a Probable Method to Diagnose Periprosthetic Joint Infection: An Exploratory Study.

OBJECTIVE: Leucocyte esterase (LE) strip test is the most rapid, convenient, and cheap method to diagnose chronic periprosthesis joint infection (PJI). However, the determination of LE strip mainly relies on colorimetric method with strong subjectivity, which leads to low diagnostic accuracy. Therefore, we try to convert LE strip images into digital data through the RGB photometric system to achieve objective diagnosis. This method will greatly improve the accuracy of LE strip detection and diagnosis of PJI. METHODS: From January 2021 to September 2021, 46 patients with suspected PJI after total hip and knee arthroplasty underwent diagnostic joint puncture. After effective joint fluid samples were harvested, they were divided into original fluid and centrifuged fluid for LE strip detection. Real-time images of LE strip were taken at 90 s, 3 min, 5 min, 10 min, and 15 min after sampling, and their brightness (Y) was obtained after they were input into an RGB photometric system. Grouping was based on centrifugation, infection, and time points, and then the differences in brightness among groups were compared. The correlation between LE strip image brightness and WBC count was evaluated. Student t-test was used for the parametric data and chi-square test for qualitative data. Simple linear regression was utilized to analyze the correlation between brightness and WBC count in each group. RESULTS: Included were 19 cases of PJI and 27 Non-PJI subjects diagnosed against ICM2018 diagnostic criteria. The brightness was lower in the PJI group than in Non-PJI group (p < 0.05). The brightness of the uncentrifuged group was lower than that of the centrifuged group (p < 0.05). Irrespective of centrifugation or infection, the brightness of LE strip decreased with the exposure time after sampling. The brightness of LE strip was correlated with WBC count at different time points, with the correlation being strongest 5 min after sampling (R2 (5 min) = 0.86, p < 0.0001). The correlation between LE strip brightness and WBC count was also found in the centrifugation group, with the correlation being most robust 15 min after sampling (R2 (15 min) = 0.73, p < 0.0001). CONCLUSION: A remarkable correlation was found between LE strip brightness and the WBC count. It is feasible to directly quantify LE strip image on a RGB photometer to achieve quantitative detection of LE strip to diagnose PJI.

Posteromedial Corner Release with the Knee in Figure-of-Four Position vs Conventional Position for Varus Knee Arthroplasty.

OBJECTIVE: To introduce posteromedial corner release with the knee in the figure-of-four position versus the conventional position for varus knee arthroplasty. METHODS: This is a retrospective study. From March 2015 to September 2019, a series of 123 patients (139 knees) with varus knee were randomly and blindly allocated to experimental group (60 patients; 68 knees) and control group (57 patients; 65 knees). Patients in experimental group underwent posteromedial corner release with the knee in the figure-of-four position; and patients in control group with the knee in the conventional position. If soft tissue balance was not completely achieved or the medial gap was still tight, an additional loosening technique were used to achieve symmetric medial and lateral space in both groups. Time for soft tissue balancing was defined as the time from the start of the spacer test to the end of the balance test. Length of release was defined as the distance from the osteotomy surface of the tibial plateau to the farthest structures released. The rating system of Hospital for Special Surgery (HSS) knee score was used to evaluate the clinical results. Quantitative variables were described as mean and standard deviation, and compared by one-way analysis of variance. RESULTS: The mean age of experimental group and control group was 70.2 ± 8.7 years and 68.7 ± 6.2 years, respectively (P > 0.05). Preoperatively, the mean HSS score of the groups was 38.2 ± 11.3 and 39.1 ± 10.7, respectively (P > 0.05). The mean varus knee angle was 19.7° ± 9.3° and 19.3° ± 10.7°, respectively (P > 0.05). The mean time for soft tissue balancing was 8.4 ± 3.3 min and 11.3 ± 6.9 min in experimental and control group, respectively (P < 0.05). The mean length of releasing posteromedial corner structures was 35.5 ± 13.4 mm and 27.3 ± 9.7 mm in experimental and control group, respectively (P < 0.05). Additional special loosening techniques were performed in eight knees in experimental group and seven knees in control group. The HSS scores 5 years after surgery were 95.1 ± 16.9 and 94.8 ± 17.2 respectively (P > 0.05). No complications were found during the follow-up time, and the clinical symptoms were observed to be significantly improved in the patients. CONCLUSION: The posteromedial corner can be released more extensively and thoroughly when the knee is placed in the figure-of-four position during varus knee arthroplasty.

Single-stage total knee arthroplasty and femoral osteotomy for osteoarthritis with severe supracondylar deformity.

BACKGROUND: Knee osteoarthritis associated with extra-articular deformity (EAD) can confront the arthroplasty surgeons with challenges of bone resection and soft tissue balancing. The aim of this study was to describe a single-stage procedure associating corrective osteotomy with total knee arthroplasty (TKA), and to determine the outcome at mid- to long-term follow-up. METHODS: A total of seven patients (seven knees) with knee osteoarthritis and supracondylar deformity were included in this study. Six patients were female, and one was male, with the median age of 62 years (range, 37-76 years). All patients were treated with single-stage TKA and femoral osteotomy. Osteotomy was fixed with long cemented stem. Hospital of Special Surgery (HSS) scores, collateral ligament laxity, and range of motion (ROM) were clinically evaluated preoperatively and at each follow-up. Radiographic parameters including the mechanical axis deviation (MAD), mechanical lateral distal femoral angle (mLDFA), mechanical proximal tibial angle (mMPTA), and joint line congruence angle (JLCA) were also measured. The occurrence of perioperative complications was recorded. RESULTS: The median follow-up time was 91 months (range, 38-104 months). At the last follow-up, all components were stable and no patients required revision. Nonunion of the osteotomy occurred in one patient. In all patients, the lower limb mechanical alignment improved greatly. The mean angle of MAD was restored from 10.49±6.05 cm preoperatively to 1.11±4.97 cm postoperatively. The 90° mLDFA was almost acquired in all cases, with the postoperative value of 90.79±2.40°. After operation, the mMPTA improved from 84.18±6.13° to 91.33±3.13°. The JLCA changed from 2.94±1.61° to -0.71±3.50°. The median HSS score improved from 45 (range, 34-56) preoperatively to 90 (range, 82-97) postoperatively, with the outcome of all patients rated good to excellent. The median ROM improved from 70° (range 0-110°) preoperatively to 105° (range 90-125°) postoperatively. No instability of knee joint was observed. Complications included an intraoperative split fracture of distal femur and one case of wound exudation resulting from fat liquefaction. CONCLUSIONS: For knee osteoarthritis with femoral supracondylar deformity, single-stage TKA and corrective osteotomy was feasible but technically demanding. The use of long cemented stem for osteotomy fixation can provide reliable rotational control of the bone segments.