Absence of signature inflammatory markers in synovial fluid for total knee arthroplasties revised for arthrofibrosis

The association between losartan potassium prescription and postoperative outcomes following total knee arthroplasty: A TriNetX analysis

BACKGROUND

Total knee arthroplasty (TKA) is a common surgical procedure performed to alleviate pain and improve functional outcomes in patients with knee osteoarthritis and rheumatoid arthritis who have failed conservative treatments. Arthrofibrosis has been extensively studied due to its negative impact on TKA outcomes. Losartan, an angiotensin receptor blocker (ARB), has the potential to improve TKA outcomes by inhibiting TGF-β and decreasing fibrosis. This study aims to analyze a large-scale, real-world healthcare database to investigate the association between losartan potassium prescription and postoperative outcomes such as readmissions, ED visits, and the need for MUA or revision TKA.

HYPOTHESIS

Based on previous literature and the nature of ARBs, it is expected that the addition of losartan will aid in better outcomes for patients following a primary TKA.

PATIENTS AND METHODS

In this retrospective observational study, the TriNetX Research Network (TriNetX) database was queried as of June 21, 2023. All patients who underwent a primary total knee arthroplasty (TKA) prior to June 21, 2022 were included. Patients were then divided into two cohorts by whether they had an active losartan potassium prescription within the year prior to their surgery to within 90days postoperatively. Patients were then propensity-matched to eliminate differences in demographics and comorbidities.

RESULTS

Losartan TKA patients were 1.18 [OR: 0.85 (95% CI: 0.79-0.90), p<0.001] times less likely to be readmitted within 90days and were 1.15 (OR: 0.87 (95% CI: 0.79-0.96); p=0.009) times less likely to undergo a manipulation under anesthesia (MUA) within the 1-year postoperative period. There were no statistically significant differences in rates of emergency department (ED) visits at 90days postoperatively or revision TKAs at 1year postoperatively.

DISCUSSION

In conclusion, patients with an active losartan prescription prior to TKA had a significantly lower likelihood of readmission within 90days and a lower likelihood of undergoing MUA within the 1-year postoperative period compared to patients not taking losartan. This presents an opportunity for further clinical investigation to explore the value of losartan in TKA.

LEVEL OF EVIDENCE

III; an observational cohort study.

Unexpected positive cultures in patients with arthrofibrosis following total hip and total knee arthroplasty

PURPOSE

It has been suggested that low-grade infections could be the cause of arthrofibrosis. However, this hypothesis has not been conclusively proven. The aim of this study is to assess the incidence of unexpected positive cultures (UPC) in patients undergoing revision total joint arthroplasty for a diagnosis of arthrofibrosis.

METHODS

A retrospective single-centre review was performed. All patients who underwent an aseptic revision due to histologically confirmed arthrofibrosis (based on the synovial-like interface membrane (SLIM) criteria) were included. The incidence of UPC was then calculated.

RESULTS

A total of 147 patients were included. Of these, 100 underwent a total knee arthroplasty (TKA) procedure and 46 a total hip arthroplasty (THA) surgery. One patient had a periprosthetic joint infection and was therefore excluded. Of the 146 included patients, 6 had confirmed UPC (4.08%). The following bacteria were identified: Anaerococcus octavius, Staphylococcus epidermidis, Enterobacter cloacae, Staphylococcus hominis, Streptococcus pluranimalium, Staphylococcus pettenkoferi.

CONCLUSIONS

Our results suggest that the incidence of UPC in patients with arthrofibrosis is low. It is lower than that of UPC in patients that undergo a revision for other causes. There is no proven relationship between histologically confirmed arthrofibrosis following total joint arthroplasty and prosthetic joint infection.

Arthrofibrosis After Total Knee Arthroplasty: A Critical Analysis Review

» Arthrofibrosis after total knee arthroplasty (TKA) is the new formation of excessive scar tissue that results in limited ROM, pain, and functional deficits.» The diagnosis of arthrofibrosis is based on the patient's history, clinical examination, absence of alternative diagnoses from diagnostic testing, and operative findings. Imaging is helpful in ruling out specific causes of stiffness after TKA. A biopsy is not indicated, and no biomarkers of arthrofibrosis exist.» Arthrofibrosis pathophysiology is multifactorial and related to aberrant activation and proliferation of myofibroblasts that primarily deposit type I collagen in response to a proinflammatory environment. Transforming growth factor-beta signaling is the best established pathway involved in arthrofibrosis after TKA.» Management includes both nonoperative and operative modalities. Physical therapy is most used while revision arthroplasty is typically reserved as a last resort. Additional investigation into specific pathophysiologic mechanisms can better inform targeted therapeutics.

[Histopathological diagnostics of arthrofibrosis]

Joint surgery is one of the most important and successful disciplines in surgery; nevertheless, complications still occur, especially in total knee arthroplasty and surgery of the anterior cruciate ligament. A significant disease in this context is arthrofibrosis. This review article presents the cellular and molecular pathogenetic concept of arthrofibrosis, the spectrum of histopathological diagnostics and differential diagnostics and a classification into joint endoprosthesis-associated and non-joint endoprosthesis-associated arthrofibrosis is proposed. The basis of the histopathological diagnostics is the standardized tissue removal with subsequent fixation in formalin. In the case of joint implant failure and the problem of endoprosthesis-associated arthrofibrosis, the histopathological diagnostics can be carried out according to the consensus classification of synovia-like interface membrane (SLIM). Arthrofibrosis is characterized by fibrosis, a high fibroblast cellularity with immunohistochemical detection of cytoplasmic beta catenin expression. The presence of endoprosthesis-associated arthrofibrosis is probable above a threshold of 20 beta catenin positive fibroblasts per high-power field (HPF). The diagnosis of a non-endoprosthesis-associated arthrofibrosis can be classified according to the joint pathology algorithm. Diffuse non-endoprosthesis-associated arthrofibrosis is characterized by generalized proliferation of connective tissue in the whole joint and localized circumscribed arthrofibrosis is characterized by a nodose cyclops-like fibrosis. The clarification of the cause of arthrofibrosis is based on an interdisciplinary cooperation. In addition to the histopathological diagnostics, this includes clinical, surgical, biomechanical, arthroscopic, microbiological, laboratory parameter and radiological findings.

Adaptive immune responses in patients requiring revision after total knee arthroplasty

Dissatisfaction occurs in nearly 20% of patients after total knee arthroplasty (TKA); however, there remains only limited understanding of the biologic mechanisms that may contribute to suboptimal postoperative outcomes requiring revision surgery. Expansion of effector T and B cells, could promote an abnormal healing response via local or peripheral immune system mechanisms and contribute to inferior outcomes necessitating revision TKA. In this pilot study, we hypothesized that patients suffering from complications of arthrofibrosis or instability may exhibit differences in adaptive immune function. Patients (n = 31) undergoing revision TKA for an indication of arthrofibrosis or instability were prospectively enrolled. Whole blood and synovial fluid (SF) from the operative knee were collected at time of surgery. Peripheral blood mononuclear cells were isolated and analyzed by flow cytometry. Serum and SF were assessed for immunoglobulin levels by Luminex and antiphospholipid antibodies by enzyme-linked immunoassay. No significant differences were observed in peripheral blood T/B cell populations or serum immunoglobulins levels between groups. SF analysis demonstrated significant differences between the two groups, with higher levels of immunoglobulin G1 (IgG1) (p = 0.0184), IgG3 (p = 0.0084) and antiphosphatidyl serine IgG (p = 0.034) in arthrofibrosis relative to instability patients. Increased levels of both IgG subclasses and antiphospholipid antibodies in the SF suggest that intra-articular T-B cell interactions, potentially triggered by exposure to apoptotic components generated during post-op healing, could be functioning as a source of immune complexes that fuel fibrous tissue growth in arthrofibrotic patients.