The aim of the study is to evaluate the specificity and sensibility of leukocyte esterase for the diagnosis of periposthetic joint infection (PJI). Between October 2016 and April 2017 we enrolled 65 patients underwent to hip and knee revision arthroplasty due to uncertain joint infection. Synovial fluid was obtained from 64 joints that underwent revision arthroplasty. Each patient was evaluated in the preoperative time with CRP, ESR and leukoscan, in the intraoperative time with frozen section and leukocyte esterase strip and post-operative with sonication fluid culture, periprosthetic tissues cultures and histological examination. Results of all of these exams were compared to assess the specificity, the sensibility, the positive and negative predicting values of leukocyte esterase for the diagnosis of PJI.Aim
Method
The purpose of this study was to evaluate the accuracy of the sonication fluid cultures (SFC) for the diagnosis of prosthetic joint infection and compare it with frozen section and periprosthetic tissue cultures. 108 patients underwent revision or explantation procedure for any reason. Frozen sections of intraoperative specimen were analized and multiple periprosthetic samples (at least 5) were collected and cultured. All explanted prosthesis components were subject to sonication and cultured. All cultures were incubated for 14 days. PJI was diagnosed in 52 patients (48%). Sonication achieved the highest sensivity with 95% and specificity of 98%. Frozen section showed low sensivity (44%) and specificity (80%) and periprosthetic tissue cultures showed sensivity of 75% and specificity of 98%. Sonication fluid culture is a cheap, easy, accurate and sensitive diagnostic method and helps to detect about 30% more PJI compared to frozen section and 16% more compared to periprosthetic tissue cultures. It also detect about 25% more pathogens than periprosthetic tissue cultures
The clinical success and long-term outcomes of total knee arthroplasty (TKA) depend not only on the accuracy of femoral and tibial components positioning, but also on the restoration of a proper mechanical axis (MA). Coronal and rotational mal-alignment may affect significantly the final result of a knee replacement. Patient specific cutting guides and intra-operative Computer-Assisted Surgery (CAS) have recently been introduced as options to improve implant alignment during TKA. The purpose of this study was to compare the alignment accuracy and implant positioning of Patient Matched technique to CAS system in patients with primary TKA. A cohort of 68 consecutive patients who underwent TKA was enrolled for this study: 34 patients received a TKA using CAS system while 34 patients received a TKA using a MRI-based Patient Matched system. Mechanical axis and kinematics were digitally measured pre- and post-operatively in all knees using the intra-operative navigation system but data were blinded for the operating surgeon in the Patient Matched group. A post-operative CT-scan evaluation was performed in all patients to analyse the prosthetic components alignment (coronal, sagittal and axial alignment according to Perth Protocol from CT-scan). CT-scan measurements were used as landmarks as this tool is considered the gold standard. MA, posterior tibial slope (PTS) and femoral component rotation (FCR) in CAS group were compared to data of Patient Matched group. All patients also underwent a clinical evaluation with Knee Society Score (KSS) and Knee injury and Osteoarthritis Outcome Score (KOOS) at 6 and 12 months of follow up. KSS, KOOS and range of motion were comparable in the two groups after surgery. Operative time was significantly shorter in the Patient Matched group. No differences were found regarding complications rate. Mean angles, respectively for CAS and Patient Matched groups, were the following: MA was 1,7° (SD 0,9°) vs 0.8° (SD 2.1°); PTS was 3.1° (SD 0.9°) vs 3.4° (SD 2.1°); FCR was 1.5° (SD 2.2°) vs 1.36° (DS 1.2°). The outcomes of the CT scan evaluation were the following: MA was 1.5° (SD 0.8°) vs 1.0° (DS 1.5°); PTS was 2.3° (SD 0.8°) vs 3.0° (SD 2.6°); FCR was 0.4° (SD 0.8°) vs 0.2° (SD 0.3°). MA was within 3° of neutral alignment in 94% of patients for CAS group and in 97% of knees for Patient Matched group. After a short follow up, there weren't statistically significant differences between CAS and Patient Matched techniques as regards clinical and functional scores. Both the systems achieved the goal of neutral alignment within 3° of varus and valgus. We only observed greater precision for Patient Matched technique in optimizing femoral component rotation. Actually it is unpredictable if this difference may determine long term effects. Patient Matched technique and CAS for TKA surgery will certainly continue to have an impact in the future. Studies are needed to define which technique is better, in terms of long term results, failure rate and cost-effectiveness.
