Tourniquet does not affect intraoperative kinematics during total knee arthroplasty: Results of a prospective study using a robotic assistance system.

PURPOSE: Tourniquet use during total knee arthroplasty (TKA) remains controversial. There are limited data demonstrating the effect of tourniquet use on flexion and extension gaps. The use of a tourniquet can theoretically affect the kinematics of the knee joint, specifically the extension and flexion gaps and the laxity, by mechanically compressing the soft tissues including the muscles above the knee joint. Therefore, this study was designed to prospectively evaluate changes in flexion and extension gaps with and without the use of a tourniquet. METHODS: The following prospective study included 50 consecutive patients who underwent TKA using a surgical robot. The inclusion criteria were advanced osteoarthritis (OA) and varus-alignment or valgus-alignment <3° (hip-knee-ankle angle, standing long-leg X-ray), and the exclusion criteria were BMI >35 kg/m2 and mechanical axis in >3° valgus. A CR-TKA was performed, and the medial and lateral gaps (in mm) throughout the full range of motion in 10° increments were recorded. The procedure was conducted both with and without an applied tourniquet (350 mmHg). RESULTS: No significant differences were observed in the medial joint space. By contrast, the lateral gap showed significant differences in 10-20° of flexion (with a tourniquet 1.9 mm vs. without a tourniquet 2.1 mm, p = 0.018), 20-30° (1.6 vs. 1.8 mm, p = 0.02), 100-110° (0.9 vs. 1.1 mm, p = 0.021), and 110-120° (0.8 vs. 1 mm, p = 0.038). Thus, at the above degrees of flexion on the lateral side, there was a decrease in the mean of 0.2 mm with the use of a tourniquet. CONCLUSION: Although the use of a tourniquet showed a detectable change in the lateral gap in four 10° segments of flexion, clinical relevance with an average difference of 0.2 mm is not achieved. Thus, the use of a tourniquet in TKA can still be advocated based on the presented data. LEVEL OF EVIDENCE: Level I.

Which Knee Phenotypes Exhibit the Strongest Correlation With Cartilage Degeneration?

BACKGROUND: Although articular wear has been thoroughly investigated, the effects of abnormal limb alignment on cartilage degeneration over time remain poorly understood. An exact assessment of the correlation between lower limb alignment abnormalities and MRI-observed articular degradation may be helpful for understanding the progression of osteoarthritis and planning future treatment. QUESTION/PURPOSE: In patients with moderate to advanced osteoarthritis, (1) is there a correlation between overall alignment of the knee and the location of cartilage degradation over time, as measured by cartilage metrics on MRI? (2) Is there a correlation between tibial alignment and the location of cartilage degradation over time, as measured by cartilage metrics on MRI? (3) Is there a correlation between femoral alignment and the location of cartilage degradation over time, as measured by cartilage metrics on MRI? METHODS: Between April 2020 and September 2022, we retrospectively evaluated 3106 patients aged 45 to 79 years who were at risk of experiencing knee osteoarthritis. Of those, we considered as potentially eligible 600 symptomatic index knees with radiographic evidence of osteoarthritis-Kellgren-Lawrence Grades 2 or 3-at the baseline visit. Of those, 22% (134 of 600) were excluded because of a lack of proper alignment measurements, leaving 466 knees with measurements of radiologic alignment angles and quantitative MRI cartilage measurements of 16 subregions of the femorotibial compartment at baseline and 12 and 24 months, and 64 knees at the 48-month visit for investigation in the current study. Data regarding cartilage measurements of the patellofemoral compartment were not available for analysis. The knees were categorized into one of the possible 25 different phenotypes of the lower extremity established by previous research, based on the neutral, valgus, or varus distal mechanical angle of the femur and proximal tibial mechanical angle on full-limb radiographs. We applied ANOVA to estimate the effect size of the overall, femoral, and tibial alignments on the location of cartilage degradation over time, as measured by cartilage metrics on MRI. RESULTS: We found that the overall combinations of a valgus femur with valgus tibia or a valgus femur with varus tibia were associated with the highest loss of cartilage in the internal medial tibial subregion and anterior lateral tibial subregion (η 2 p = 0.39 and 0.17, respectively). For the tibia, we found that the combination of a valgus femur with valgus tibia was associated with an increase in the area of subchondral bone denuded of cartilage in the central lateral tibial subregion (η 2 p = 0.2). For the femur, we found that the combination of a valgus femur with valgus tibia was associated with loss of cartilage thickness in the central weightbearing lateral femorotibial compartment (η 2 p = 0.15). CONCLUSION: We found that certain alignment patterns are associated with rapid deterioration of cartilage and exposure of subchondral bone, even over short time periods. In particular, the valgus femur with valgus tibia and valgus femur with varus tibia phenotypes deserve special attention, because they exhibited a strong, atypical correlation with the internal medial tibial subregion and anterior lateral tibial subregion, respectively. This is important because valgus and varus malalignment cause isolated lateral and medial compartment disease, respectively. Therefore, these findings suggest that a more individualized approach for limb axis deformities is valuable, and hint at a more meticulous radiologic and clinical investigation, perhaps using different imaging modalities, especially when assessing the exact cartilage state and planning an intervention. Future studies, ideally biomechanical, might help in assessing the long-term effects of the various phenotypes on cartilage degradation and their relevance in reconstructive surgery. LEVEL OF EVIDENCE: Level II, prognostic study.

Against the Norm: Do Not Rely on Serum C-Reactive Protein and White Blood Cell Count Only When Assessing Eradication of Periprosthetic Joint Infection.

Introduction: Periprosthetic joint infections (PJI) following primary arthroplasty continue to be a serious complication, despite advances in diagnostics and treatment. Two-stage revision arthroplasty has been commonly used as the gold standard for the treatment of PJI. However, much discussion persists regarding the interim of the two-stage procedure and the optimal timing of reimplantation. Serology markers have been proposed as defining parameters for a successful reimplantation. The objective of this matched-pair analysis was to assess the role of serum C-reactive protein (CRP) and white blood cell count (WBC) in determining infection eradication and proper timing of reimplantation. We investigated the delta (∆) change in CRP and WBC values prior to both stages of two-stage revision arthroplasty as a useful marker of infection eradication. Methods: We analyzed 39 patients and 39 controls, matched by propensity score matching (BMI, age, ASA-classification), with a minimum follow-up of 24 months and treated with a two-stage revision THA or TKA in our institution. Data of serum CRP and WBC values were gathered at two selected time points: prior to the explantation of the implant (preexplantation) and following the completion of antibiotic treatment regimen, both systemic and with a drug-eluting cement spacer (prereimplantation). Patient records were reviewed electronically for preexisting comorbidities, overall health status, synovial fluid cultures, inflammatory serologies, revision surgeries, and recurrent or persistent infection based on the modified Musculoskeletal Infection Society criteria. Patient demographics, ∆CRP, ∆WBC, and time interval to reimplantation were statistically analyzed using receiver operator curves (ROC), Pearson's correlation coefficient, Levene's test, and Student's t-test. Results: Infection-free patients exhibited higher mean CRP and WBC than did patients who were reinfected at both time points. When comparing preexplantation with prereimplantation values, the median ∆CRP was 9.48 mg/L (interquartile range (IQR) 2.3−36.6 mg/L) for patients who did not develop a reinfection versus 2.74 mg/L (IQR 1.4−14.2 mg/L) for patients who developed reinfection (p = 0.069). The median ∆WBC was 1.5 × 109/L (IQR 0.6−4.0 × 109/L) for patients who remained infection-free versus 1.2 × 109/L (IQR 0.8−2.2 109/L) for patients who developed reinfection (p = 0.072). Analysis of areas under the curve (AUC) using ROC demonstrated poor prediction of persistent infection by ∆CRP (AUC = 0.654) and ∆WBC (AUC = 0.573). Although a highly significant correlation was found between the interim interval and infection persistence (r = 0.655, p < 0.01), analysis using ROC failed to result in a specific threshold time to reimplantation above which patients are at significantly higher risk for reinfection (AUC = 0.507). Conclusion: No association could be determined between the delta change in serum CRP and WBC before and after two-stage revision arthroplasty for PJI and reinfection risk. Even though inflammatory serologies demonstrate a downtrending pattern prior to reimplantation, the role of CRP and WBC in determining the optimal timing of reimplantation seems to be dispensable. Planning a second-stage reimplantation requires assessing multiple variables rather than relying on specific numeric changes in these inflammatory marker values.

A comparison between Austin-Moore and Corail prosthesis regarding intraoperative periprosthetic femur fractures in hip hemiarthroplasty.

Hip hemiarthroplasty is considered the treatment of choice for displaced femoral neck fractures in elderly less active patients. One important complication of this procedure is an intraoperative periprosthetic femur fracture (IPF), which may lead to poor functional outcome and may increase morbidity and mortality. Our primary aim in this study is to compare between Austin-Moore and Corail prosthesis regarding IPFs. Our secondary aim is to assess patient and surgical technique related risk factors for the development of this complication. Inclusion criteria included patients older than 65 years of age who had a displaced femoral neck fracture and were operated for hip hemiarthroplasty between the years 2014-2018. Patient-specific data was collected retrospectively including age, gender, comorbidities, pre-injury ambulatory status, duration of surgery, surgical approach, use of Austin-Moore or Corail prosthesis, surgeon's experience and type of anesthesia applied. In addition, radiographs were reviewed for measurement of calcar to canal ratio (CDR) and classification of Dorr canal type. 257 patients with an average age of 83.7 years were enrolled in the study. 118 patients (46%) were treated with an Austin-Moore prosthesis, while 139 (54%) were treated with a Corail prosthesis. A total of 22 patients (8.6%) had intraoperative fractures. Fracture prevalence was significantly higher in the Corail group compared with the Austin-Moore group (12.2% vs. 4.2%, p = 0.025). The majority of patients had a Dorr A type femoral canal, while the rest had Dorr B type canal (70% vs. 30%). There was no difference in fracture prevalence between Dorr A and B canal type patients. We didn't find any significant risk factor for developing an IPF, neither patient wise (age, gender, and comorbidities) nor surgical technique related (surgical approach, type of anesthesia, and surgeon's experience). Intraoperative periprosthetic fracture prevalence was significantly higher in the Corail patient group compared with the Austin-Moore group. This may be an important advantage of the Austin-Moore prosthesis over the Corail prosthesis.

Validation of joint space narrowing on plain radiographs and its relevance to partial knee arthroplasty.

AIMS: To explore the clinical relevance of joint space width (JSW) narrowing on standardized-flexion (SF) radiographs in the assessment of cartilage degeneration in specific subregions seen on MRI sequences in knee osteoarthritis (OA) with neutral, valgus, and varus alignments, and potential planning of partial knee arthroplasty. METHODS: We retrospectively reviewed 639 subjects, aged 45 to 79 years, in the Osteoarthritis Initiative (OAI) study, who had symptomatic knees with Kellgren and Lawrence grade 2 to 4. Knees were categorized as neutral, valgus, and varus knees by measuring hip-knee-angles on hip-knee-ankle radiographs. Femorotibial JSW was measured on posteroanterior SF radiographs using a special software. The femorotibial compartment was divided into 16 subregions, and MR-tomographic measurements of cartilage volume, thickness, and subchondral bone area were documented. Linear regression with adjustment for age, sex, body mass index, and Kellgren and Lawrence grade was used. RESULTS: We studied 345 neutral, 87 valgus, and 207 varus knees. Radiological JSW narrowing was significantly (p < 0.01) associated with cartilage volume and thickness in medial femorotibial compartment in neutral (r = 0.78, odds ratio (OR) 2.33) and varus knees (r = 0.86, OR 1.92), and in lateral tibial subregions in valgus knees (r = 0.87, OR 3.71). A significant negative correlation was found between JSW narrowing and area of subchondral bone in external lateral tibial subregion in valgus knees (r = -0.65, p < 0.01) and in external medial tibial subregion in varus knees (r = -0.77, p < 0.01). No statistically significant correlation was found in anterior and posterior subregions. CONCLUSION: SF radiographs can be potentially used for initial detection of cartilage degeneration as assessed by MRI in medial and lateral but not in anterior or posterior subregions. Cite this article: Bone Joint Res 2021;10(3):173-187.

Can we define reliable risk factors for anastomotic strictures following radical prostatectomy?

BACKGROUND: To identify risk factors for anastomotic strictures in patients after radical prostatectomy. METHODS: In all, 140 prostate cancer patients with one or more postoperative anastomotic strictures after radical prostatectomy were included. All patients underwent transurethral anastomotic resection at the University Hospital of Munich between January 2009 and May 2016. Clinical data and follow-up information were retrieved from patients' records. Statistical analysis was done using Kaplan-Meier curves and log rank-test with time to first transurethral anastomotic resection as endpoint, Chi-square-test, and Mann-Whitney-U test. RESULTS: In all, 140 patients with a median age of 67 years (IQR: 61-71 years) underwent radical prostatectomy. Median age at time of transurethral anastomotic resection was 68 years (IQR: 62-72). Patients needed 2 surgical interventions in median (range: 1-15). Median time from radical prostatectomy to transurethral anastomotic resection was 6 months (IQR: 3.9-17.4). Median duration of catheterization after radical prostatectomy was 10 days (IQR: 8-13). In all, 26% (36/140) received additional radiotherapy. Regarding time to first transurethral anastomotic resection, age and longer duration of catheterization after radical prostatectomy with a cutoff of 7 days showed no statistically significant differences (p = 0.392 and p = 0.141, respectively). Tumor stage was no predictor for development of anastomotic strictures (p = 0.892), and neither was prior adjuvant radiation (p = 0.162). Potential risk factors were compared between patients with up to 2 strictures (low-risk) and patients developing > 2 strictures (high-risk): high-risk patients had more often injection of cortisone during surgery (14% vs 0%, p < 0.001) and more frequently advanced tumor stage pT > 2 (54% vs 38%, p = 0.055), respectively. Other risk factors did not show any significant difference compared to number of prior transurethral anastomotic strictures. CONCLUSIONS: We could not identify a reliable risk factor to predict development of anastomotic strictures following radical prostatectomy.