A potential mode of action for Anakinra in patients with arthrofibrosis following total knee arthroplasty

A Comprehensive Approach to Stiffness in Total Knee Arthroplasty

This article is a summary of a symposium on knee stiffness in primary and revision TKAs presented at the 2024 American Association of Hip and Knee Surgeons (AAHKS) annual meeting. The purpose of this paper was to provide an overview of the genetics of arthrofibrosis, preoperative and perioperative risk factors associated with arthrofibrosis, ways to optimize modifiable risk factors, and early and late treatment options for stiffness and when it fails to improve with initial interventions.

Postoperative Angiotensin Receptor Blocker Use is Associated With Decreased Rates of Manipulation Under Anesthesia, Arthroscopic Lysis of Adhesions, and Prosthesis-Related Complications in Patients Undergoing Total Knee Arthroplasty

BACKGROUND

The cellular mechanisms underlying excess scar tissue formation in arthrofibrosis following total knee arthroplasty (TKA) are well-described. Angiotensin receptor blockers (ARB), particularly losartan, is a commonly prescribed antihypertensive with demonstrated antifibrotic properties. This retrospective study aimed to assess the rates of 1- and 2-year postoperative complications in patients who filled prescriptions for ARBs during the 90 days after TKA.

METHODS

Patients undergoing primary TKA were selected from a large national insurance database, and the impact of ARB use after TKA on complications was assessed. Of the 1,299,106 patients who underwent TKA, 82,065 had filled at least a 90-day prescription of losartan, valsartan, or olmesartan immediately following their TKA. The rates of manipulation under anesthesia (MUA), arthroscopic lysis of adhesions (LOA), aseptic loosening, periprosthetic fracture, and revision at 1 and 2 years following TKA were analyzed using multivariable logistic regressions to control for various comorbidities.

RESULTS

ARB use was associated with decreased rates of MUA (odds ratio [OR] = 0.94, 95% confidence interval (CI), 0.90 to 0.99), arthroscopy/LOA (OR = 0.86, 95% CI, 0.77 to 0.95), aseptic loosening (OR = 0.71, 95% CI, 0.61 to 0.83), periprosthetic fracture (OR = 0.58, 95% CI, 0.46 to 0.71), and revision (OR = 0.79, 95% CI, 0.74 to 0.85) 2 years after TKA.

CONCLUSIONS

ARB use throughout the 90 days after TKA is associated with a decreased risk of MUA, arthroscopy/LOA, aseptic loosening, periprosthetic fracture, and revision, demonstrating the potential protective abilities of ARBs. Prospective studies evaluating the use of ARBs in patients at risk for postoperative stiffness would be beneficial to further elucidate this association.

Pharmacological Therapies for Connective Tissue Fibrosis in Orthopaedics

Fibrosis is a common and debilitating pathological process that affects many organ systems and contributes to connective tissue disorders in orthopaedics. Tendons heal after acute and chronic injury through a process of fibrovascular scar tissue formation, and soft tissue joint capsules can be affected after traumatic joint injury, leading to arthrofibrosis. Although the precise underlying mechanisms are still being elucidated, fibrosis is thought to be a consequence of dysregulated immune and cytokine signaling that leads to myofibroblast activation and proliferation and subsequent excessive collagen deposition. Current treatments for connective tissue fibrosis include physical therapy and surgery, but there are no therapies that directly target the underlying cellular and molecular mechanisms of fibrosis. Many pharmacological agents have been used to successfully target fibrosis in other tissues and organ systems and thus are a promising treatment option to fill this gap. However, limited evidence is available to guide the use of these agents in musculoskeletal connective tissues. This article provides an overview of pharmacological therapies that have potential to treat connective tissue fibrosis in patients with musculoskeletal conditions, along with the current supporting evidence and future uses of each therapy.

Understanding of arthrofibrosis: New explorative insights into extracellular matrix remodeling of synovial fibroblasts

Arthrofibrosis following total knee arthroplasty is a fibroproliferative joint disorder marked by dysregulated biosynthesis of extracellular matrix proteins, such as collagens and proteoglycans. The underlying cellular events remain incompletely understood. Myofibroblasts are highly contractile matrix-producing cells characterized by increased alpha-smooth muscle actin expression and xylosyltransferase-I (XT-I) secretion. Human XT-I has been identified as a key mediator of arthrofibrotic remodeling. Primary fibroblasts from patients with arthrofibrosis provide a useful in vitro model to identify and characterize disease regulators and potential therapeutic targets. This study aims at characterizing primary synovial fibroblasts from arthrofibrotic tissues (AFib) regarding their molecular and cellular phenotype by utilizing myofibroblast cell culture models. Compared to synovial control fibroblasts (CF), AFib are marked by enhanced cell contractility and a higher XT secretion rate, demonstrating an increased fibroblast-to-myofibroblast transition rate during arthrofibrosis. Histochemical assays and quantitative gene expression analysis confirmed higher collagen and proteoglycan expression and accumulation in AFib compared to CF. Furthermore, fibrosis-based gene expression profiling identified novel modifier genes in the context of arthrofibrosis remodeling. In summary, this study revealed a unique profibrotic phenotype in AFib that resembles some traits of other fibroproliferative diseases and can be used for the future development of therapeutic interventions.

Biochemical markers of postsurgical knee arthrofibrosis: A systematic review

Introduction

Postsurgical knee arthrofibrosis is a common complication associated with pain and limited range of motion. Although the mechanism is unclear, many biochemical and genetic markers have been identified within arthrofibrotic knees. The purpose of this systematic review is to synthesize the many biochemical and genetic markers that have been associated with surgery-induced knee arthrofibrosis in order to better guide future therapeutic endeavors.

Methods

A thorough search of literature was conducted on April 27, 2022. Seventeen studies met inclusion criteria for this systematic review. Inclusion criteria for this study were as follows: title or abstract discussed biochemical and genetic markers associated with postoperative knee arthrofibrosis, study design included human and/or animal subjects.

Results

A wide variety of genetic biomarkers (mRNA), proteins/enzymes, and cytokines were identified in both animal models and human subjects with postsurgical knee arthrofibrosis. These included various extracellular matrix-encoding mRNA sequences, matrix metalloproteinases, proteins and mRNA sequences involved in Transforming Growth Factor-β signaling, and interleukin-family cytokines to name just a few.

Conclusion

There are many biomarkers found in postsurgical arthrofibrotic knees. TGF-β, and mRNA/proteins that participate in TGF-β signaling (i.e., LOX, SERPINE1, PAI-1/Akt/mTOR, BMP-2), appear to be particularly common. Future comparative studies should aim to determine which of these are most relevant, and therefore, worthwhile therapeutic targets.

Inflammation and Fibrosis Induced by Joint Remobilization, and Relevance to Progression of Arthrogenic Joint Contracture: A Narrative Review

Joint immobilization is frequently administered after fractures and ligament injuries and can cause joint contracture as a side effect. The structures responsible for immobilization-induced joint contracture can be roughly divided into muscular and articular. During remobilization, although myogenic contracture recovers spontaneously, arthrogenic contracture is irreversible or deteriorates further. Immediately after remobilization, an inflammatory response is observed, characterized by joint swelling, deposit formation in the joint space, edema, inflammatory cell infiltration, and the upregulation of genes encoding proinflammatory cytokines in the joint capsule. Subsequently, fibrosis in the joint capsule develops, in parallel with progressing arthrogenic contracture. The triggers of remobilization-induced joint inflammation are not fully understood, but two potential mechanisms are proposed: 1) micro-damage induced by mechanical stress in the joint capsule, and 2) nitric oxide (NO) production via NO synthase 2. Some interventions can modulate remobilization-induced inflammatory and subsequent fibrotic reactions. Anti-inflammatory treatments, such as steroidal anti-inflammatory drugs and low-level laser therapy, can attenuate joint capsule fibrosis and the progression of arthrogenic contracture in remobilized joints. Antiproliferative treatment using the cell-proliferation inhibitor mitomycin C can also attenuate joint capsule fibrosis by inhibiting fibroblast proliferation without suppressing inflammation. Conversely, aggressive exercise during the early remobilization phases is counterproductive, because it facilitates inflammatory and then fibrotic reactions in the joint. However, the adverse effects of aggressive exercise on remobilization-induced inflammation and fibrosis are offset by anti-inflammatory treatment. To prevent the progression of arthrogenic contracture during remobilization, therefore, care should be taken to control inflammatory and fibrotic reactions in the joints.

Perioperative Use of Antifibrotic Medications Associated With Lower Rate of Manipulation After Primary TKA: An Analysis of 101,366 Patients

BACKGROUND

Several commonly prescribed medications have known antifibrotic properties and have been shown to reduce postoperative scar formation in other clinical areas, but it is unknown whether the use of such medications perioperatively in patients undergoing TKA may improve rates of postoperative stiffness.

METHODS

A large US employer-sponsored healthcare database (Truven Marketscan) was queried for patients who underwent elective primary TKA for primary osteoarthritis between 2015-2019. Demographic information and comorbidities were recorded, along with whether patients were prescribed one of several medications with known antifibrotic properties during the three months before or after surgery.

RESULTS

Complete data were available for 101,366 patients undergoing TKA, of which 4,536 underwent MUA (4.5%). Perioperative use of any antifibrotic medication was associated with a lower likelihood of undergoing MUA (P < .001). When controlling for age, sex, comorbidities, opioid use, length of stay, among other variables, perioperative use of specific ACE inhibitors (OR 0.91, CI 0.84-1, P = .042), COX-2 inhibitors (OR 0.88, CI 0.81-0.96, P = .002), and angiotensin II receptor blockers, specifically losartan (OR 0.80, CI 0.70-0.91, P = .007) all remained significantly associated with lower rates of MUA.

CONCLUSION

This study, spanning over a hundred thousand primary TKA procedures over a recent five-year period, demonstrates an association between perioperative use of specific medications with antifibrotic properties and a decreased rate of MUA. These data will help inform future studies aimed to prospectively evaluate the potential of antifibrotic medications in preventing postoperative stiffness in high-risk patients undergoing knee arthroplasty.

Association of circulating gene expression signatures with stiffness following total knee arthroplasty for osteoarthritis: a pilot study

A subset of patients undergoing total knee arthroplasty (TKA) for knee osteoarthritis develop debilitating knee stiffness (reduced range of motion) for poorly understood reasons. Dysregulated inflammatory and immune responses to surgery correlate with reduced surgical outcomes, but the dysregulated gene signatures in patients with stiffness after TKA are poorly defined. As a consequence, we are limited in our ability to identify patients at risk of developing poor surgical outcomes and develop preventative approaches. In this pilot study we aimed to identify perioperative blood gene signatures in patients undergoing TKA for knee osteoarthritis and its association with early surgical outcomes, specifically knee range of motion. To do this, we integrated clinical outcomes collected at 6 weeks after surgery with transcriptomics analyses in blood samples collected immediately before surgery and at 24 h after surgery. We found that patients with stiffness at 6 weeks after surgery have a more variable and attenuated circulating gene expression response immediately after surgery. Our results suggest that patients with stiffness following TKA may have distinct gene expression signatures detectable in peripheral blood in the immediate postoperative period.

Human outgrowth knee fibroblasts from patients undergoing total knee arthroplasty exhibit a unique gene expression profile and undergo myofibroblastogenesis upon TGFβ1 stimulation

Arthrofibrosis is characterized by excessive extracellular matrix (ECM) deposition that results in restricted joint motion after total knee arthroplasties (TKAs). Currently, treatment options are limited. Therefore, an in vitro model of knee-related myofibroblastogenesis is valuable to facilitate investigation of the arthrofibrotic process, diagnostic and therapeutic options. In this study, we obtained intraoperative posterior capsule (PC), quadriceps tendon (QT), and suprapatellar pouch (SP) tissues from the knees of four patients undergoing primary TKAs for osteoarthritis. From these tissues, we isolated primary cells by the outgrowth method and subsequently characterized these cells in the absence and presence of the pro-myofibroblastic cytokine, transforming growth factor beta 1 (TGFβ1). Light microscopy of knee outgrowth cells revealed spindle-shaped cells, and immunofluorescence (IF) analysis demonstrated staining for the fibroblast-specific markers TE-7 and vimentin (VIM). These knee outgrowth fibroblasts differentiated readily into myofibroblasts as reflected by enhanced α-smooth muscle actin (ACTA2) mRNA and protein expression and increased mRNA expression of collagen type 1 (COL1A1) and type 3 (COL3A1) with collagenous matrix deposition in the presence of TGFβ1. Outgrowth knee fibroblasts were more sensitive to TGFβ1-mediated myofibroblastogenesis than adipose-derived mesenchymal stromal/stem cells (MSCs). While outgrowth knee fibroblasts isolated from three anatomical regions in four patients exhibited similar gene expression, these cells are distinct from other fibroblastic cell types (i.e., Dupuytren's fibroblasts) as revealed by RNA-sequencing. In conclusion, our study provides an in vitro myofibroblastic model of outgrowth knee fibroblasts derived from patients undergoing primary TKA that can be utilized to study myofibroblastogenesis and assess therapeutic strategies for arthrofibrosis.

Interleukin-1 receptor antagonist inhibits arthrofibrosis in a post-traumatic knee immobilization model

BACKGROUND

Therapies for arthrofibrosis after knee surgery are needed to prevent loss of joint function. Interleukin-1 receptor antagonists (IL-1RA) have shown promise in treating established arthrofibrosis in pilot clinical studies. The objective of this study was to evaluate the ability of intra-articular injection of IL-1RA to prevent knee joint contracture in a post-traumatic knee immobilization model.

METHODS

20 male Sprague Dawley rats were block randomized into two groups: control and IL-1RA. Rats underwent intra-articular surgical trauma of the right knee with placement of an immobilization suture, securing the knees in 150° flexion. On post-operative days 1 and 8, each group received a 0.1 ml intra-articular injection of either saline (control) or anakinra (IL-1RA:single dosage; 2.63 mg/kg). Rats were euthanized fourteen days after surgery and the immobilization femorotibial angles were measured on the operative limbs with the suture and musculature intact. Subsequently, musculature was removed and femorotibial angles were measured in the operative and non-operative limbs with a defined extension moment applied with the posterior capsule intact or cut. A contracture angle was calculated as the angular difference between the operative and non-operative limb.

RESULTS

The immobilization knee flexion angle did not differ (P = 0.761) between groups (control: 152 ± 9; IL-1RA: 150 ± 11). The joint contracture angles (smaller angle = improved outcome) were reduced by 12 degrees on average in the IL-1RA group compared to the control for both the capsule intact (P = 0.024) and cut (P = 0.019) states.

CONCLUSIONS

Intra-articular IL-1RA injection was found to diminish knee extension deficits associated with arthrofibrosis in a post-traumatic joint immobilization model.

Acquired Idiopathic Stiffness After Contemporary Total Knee Arthroplasty: Incidence, Risk Factors, and Results Over 25 Years

BACKGROUND

Acquired idiopathic stiffness (AIS) remains a common failure mode of contemporary total knee arthroplasties (TKAs). The present study investigated the incidence of AIS and manipulation under anesthesia (MUA) at a single institution over time, determined outcomes of MUAs, and identified risk factors associated with AIS and MUA.

METHODS

We identified 9771 patients (12,735 knees) who underwent primary TKAs with cemented, modular metal-backed, posterior-stabilized implants from 2000 to 2016 using our institutional total joint registry. Mean age was 68 years, 57% were female, and mean body mass index was 33 kg/m². Demographic, surgical, and comorbidity data were investigated via univariate Cox proportional hazard models and fit to an adjusted multivariate model to access risk for AIS and MUA. Mean follow-up was 7 years.

RESULTS

During the study period, 456 knees (3.6%) developed AIS and 336 knees (2.6%) underwent MUA. Range of motion (ROM) increased a mean of 34° after the MUA; however, ROM for patients treated with MUA was inferior to patients without AIS at final follow-up (102° vs 116°, P < .0001). Significant risk factors included younger age (HR 2.3, P < .001), increased tourniquet time (HR 1.01, P < .001), general anesthesia (HR 1.3, P = .007), and diabetes (HR 1.5, P = .001).

CONCLUSION

Acquired idiopathic stiffness has continued to have an important adverse impact on the outcomes of a subset of patients undergoing primary TKAs. When utilized, MUA improved mean ROM by 34°, but patients treated with MUA still had decreased ROM compared to patients without AIS. Importantly, we identified several significant risk factors associated with AIS and subsequent MUA.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Formation process of joint contracture after anterior cruciate ligament reconstruction in rats

Knee joint contracture is often induced by anterior cruciate ligament reconstruction (ACLR). However, the temporal and spatial arthrofibrotic changes following inflammatory events, which occur in parallel with the formation of joint contractures after ACLR, are unknown. This study aimed to reveal: (a) time-dependent changes in myogenic and arthrogenic contractures; and (b) the process of arthrofibrosis development after ACLR. ACLR was performed on knees of rats unilaterally. Passive ranges of motions (ROMs) before and after myotomy, as well as inflammatory and fibrotic reactions, were examined before and after the surgery at various periods up to 56 days. Both ROMs before and after myotomy exhibited their lowest value on day 7 and increased thereafter in a time-dependent manner; nevertheless, significant restrictions remained by day 56. Myotomy partially increased ROMs at all time points, indicating contribution of the myogenic component to ACLR-induced contracture. Inflammatory and fibrotic reactions peaked on day 7. Arthrofibrosis, characterized by the thickening of the joint capsule and the shortening of the synovial length, was established by day 7 and was not completely resolved by day 56. Our results indicate that: (a) both myogenic and arthrogenic contractures generated through ACLR develop maximally by day 7 after surgery and subside thereafter, but persist at least until day 56; and (b) arthrofibrosis is established by day 7 after surgery and is not completely resolved by day 56. These findings suggest that treatment and intervention for preventing joint contracture after ACLR should be performed within the first 7 days after surgery.

Homoharringtonine inhibits fibroblasts proliferation, extracellular matrix production and reduces surgery-induced knee arthrofibrosis via PI3K/AKT/mTOR pathway-mediated apoptosis

Background

The prevention of surgery-induced intraarticular fibrosis remains a challenge following orthopedic surgery. Homoharringtonine (HHT) has been reported to have positive effects in preventing various kinds of fibrosis. However, little is known regarding its effect as well as the potential mechanism of HHT in preventing surgery-induced intraarticular fibrosis.

Methods

Various concentrations of HHTs were locally applied in vivo to reduce knee intraarticular fibrosis in rabbits. Histological macroscopic assessments such as hematoxylin and eosin (HE) staining, Masson’s trichrome staining, and Picric-sirius red polarized light were used to evaluate the effect of HHT in reducing intraarticular fibrosis. CCK-8, cell cycle assay, and EdU incorporation assay were used in vitro to detect HHT’s effect on inhibiting fibroblast viability and proliferation. The effect of HHT on fibroblast differentiation, extracellular matrix production, and apoptosis were evaluated by western blot, flow cytometry, immunofluorescent staining, and TUNEL analysis. Moreover, the expressions of PI3K/AKT/mTOR signaling pathway were detected.

Results

The results demonstrated that HHT could reduce the formation of intraarticular fibrosis. HHT was also found to induce fibroblast apoptotic cell death in a dose- and time-dependent manner in vitro. Moreover, HHT could effectively inhibit the production of the extracellular matrix secreted by fibroblasts and inhibited the expression of p-PI3K, p-AKT, and p-mTOR in a dose-dependent manner. After treating with insulin-like growth factor-1 (IGF-1), an activator of the PI3K/AKT axis, the expressions of pro-apoptosis-related proteins were decreased, and the fibroblast apoptosis rate was also inhibited.

Conclusions

In conclusion, this study demonstrated that HHT could reduce the formation of intraarticular fibrosis through the inhibition of fibroblast proliferation, extracellular matrix production, and the induction of fibroblast apoptotic cell death. Furthermore, its potential mechanism may be through the suppression of the PI3K/AKT/mTOR signaling pathway.

Literature review of the causes of pain following total knee replacement surgery: prosthesis, inflammation and arthrofibrosis

Adverse knee pain occurs in 10–34% of all total knee replacements (TKR), and 20% of TKR patients experience more pain post-operatively than pre-operatively. Knee pain is amongst the top five reasons for knee replacement revision in the United Kingdom. The number of TKRs is predicted to continue increasing due to the ageing population.

A narrative literature review was performed on the different causes of pain following TKR. A database search on Scopus, PubMed, and Google Scholar was conducted to look for articles related to TKR, pain, and cause. Articles were selected based on relevance, publication date, quality of research and validation. Relevant sections were added to the review.

One hundred and fourteen articles were identified and potential causes of TKR pain included: arthrofibrosis, aseptic loosening, avascular necrosis, central sensitization, component malpositioning, infection, instability, nerve damage, overstuffing, patellar maltracking, polyethylene wear, psychological factors and unresurfaced patella.

It is important to tailor our approach to address the individual causes of pain. Certain controllable risk factors can be managed pre-operatively to minimize post-operative pain. Risk factors help to predict adverse pain outcomes and identify specific causes.

There are multiple causes of pain following TKR. Some factors will require further extensive studies, and as pain is a commonly attributed reason for TKR revision, its underlying aetiologies should be explored. Understanding these factors helps to develop effective methods for diagnosis, prevention and management of TKR pain, which help to improve patient outcomes.

Cite this article: EFORT Open Rev 2020;5:534-543. DOI: 10.1302/2058-5241.5.200031

Postoperative Serum Cytokine Levels Are Associated With Early Stiffness After Total Knee Arthroplasty: A Prospective Cohort Study

BACKGROUND

Inflammatory cytokines have been implicated in organ fibrosis; however, their role in the development of arthrofibrosis after total knee arthroplasty (TKA) has not been well explored. The purpose of this study is to assess whether perioperative synovial fluid or blood plasma cytokine levels are associated with reduced early post-TKA range of motion.

METHODS

A total of 179 patients with end-stage idiopathic osteoarthritis undergoing TKA were enrolled in this prospective cohort study. Synovial fluid and blood plasma were collected prearthrotomy and plasma was collected longitudinally in the postacute care unit and on postoperative days (PODs) 1 and 2. Stiffness was defined as ≤95° range of motion measured with a goniometer at 6 weeks (±2 weeks).

RESULTS

Thirty-two of 162 (19.8%) patients analyzed were stiff at 6 weeks postoperatively. Postoperative plasma levels of 9 cytokines (Eotaxin3, IL-5, IL12_23p40, IP10, VEGF, IL-7, IL-12p70, IL-16, IL-17a) were significantly different between stiff and nonstiff patients on POD1 and/or POD2. An association between preoperative plasma and synovial fluid cytokine levels and the development of postoperative stiffness was not detected.

CONCLUSION

The results of this study suggest that there is a distinct acute postoperative cytokine response profile in patients who develop stiffness 6 weeks after TKA. This profile was characterized by significant differences in levels of 9 cytokines over the first 2 postoperative days. These results identify cytokines that are potential biomarkers for risk of early stiffness after TKA and may play a role in the pathophysiology of this outcome.

Chronic, Active Inflammation in Patients With Failed Total Knee Replacements Undergoing Revision Surgery

Chronic pain and restricted knee motion is a significant problem following the total knee arthroplasty (TKA). The molecular pathogenesis of pain post-TKA is not known and no targeted therapeutic intervention is available. The aim of this study was to investigate whether pro-inflammatory mediators are elevated in revision knee patients, indicating an active, ongoing inflammatory process that may contribute to pain. Twelve key markers (pro-inflammatory cytokines granulocyte-macrophage colony-stimulating factor [GM-CSF], interleukin 5 [IL-5], IL-8 and IL-10, chemokines CCL2, CCL3, CCL4, and CCL13, mediators of angiogenesis Flt-1, vascular endothelial growth factor, and cell migration vascular cell adhesion molecule 1 and intercellular adhesion molecule 1) were measured in knee tissue and synovial fluid (SF) from primary TKA (n = 29) and revision patients (n = 32). Indications for surgery were osteoarthritis (OA) for primary TKA, and component loosening (n = 11), stiffness (n = 11), laxity pattern (n = 8), or progression of OA in patella resurfacing (n = 3) for revision surgery. Pain levels (WOMAC score) were higher in revision than primary patients (p ≤ 0.05). Time from primary to revision ranged from 8 months to 30 years (median 10 years). All markers were elevated in revision TKA; there was no trend toward decreasing levels with greater time from primary surgery for any marker studied in SF. Similar results were seen in knee tissue. We found no differences comparing indications for revision surgery (p ≥ 0.05). The elevation of inflammatory mediators in painful post-TKA knees requiring revision suggests active, chronic inflammation. Characterization of upregulated markers provides rationale for targeted therapy, even many years from the primary surgery. © 2019 The Authors. Journal of Orthopaedic Research^® published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 37:2316-2324, 2019.

Arthrofibrosis After Total Knee Arthroplasty: Pathophysiology, Diagnosis, and Management

Arthrofibrosis is the pathologic stiffening of a joint caused by an exaggerated inflammatory response. As a common complication following total knee arthroplasty (TKA), this benign-appearing connective tissue hyperplasia can cause significant disability among patients because the concomitant knee pain and restricted range of motion severely hinder postoperative rehabilitation, clinical outcomes, and basic activities of daily living. The most effective management for arthrofibrosis in the setting of TKA is prevention, including preoperative patient education programs, aggressive postoperative physical therapy regimens, and anti-inflammatory medications. Operative treatments include manipulation under anesthesia, arthroscopic debridement, and quadricepsplasty.

Are we aiming to miss in translational autoimmunity treatments?

Autoimmunity treatments, fruitfully pioneered in mouse models, can be disappointing or result in immunosuppression and opportunistic infections in translational trials. Many possible reasons exist, but one major, overlooked reason may be the treatment timing in relation to circadian oscillations of the immune system. Mice and humans both have immunological circadian clocks and experience the same circulatory oscillations of immune cells with regards to their sleep/wake phases, but have opposite sleep/wake phases with regard to the daylight cycle. Therefore, researchers mainly study mice and potential autoimmunity treatments during the murine sleep/rest phase, which is when pro-inflammatory mediators and more adaptive immune cells are prevalent in the circulation. In translational trials, however, treatment administration happens primarily during a patient's wake/activity phase, during the daytime, which is when more local and acute immune responses are active in the circulation. Therefore, we believe that the most opportune window for autoimmunity treatment may be missed in translational trials. Shifting the timing, and adjusting dosing to target only immune cells that are active at that time, may result in higher success with minimized immunosuppression or toxicities.

Arthrofibrosis and large joint scarring

Large joint arthrofibrosis and scarring, involving the shoulder, elbow, hip, and knee, can result in the loss of function and immobility. The pathway of joint contracture formation is still being elucidated and is due to aberrations in collagen synthesis and misorientation of collagen fibrils. Novel antibodies are being developed to prevent arthrofibrosis, and current treatment methods for arthrofibrosis include medical, physical, and surgical treatments. This article describes the biology of joint contracture formation, along with current and future pharmacologic, biologic, and medical interventions.

Synovectomy during total knee arthroplasty: a pilot single-centre randomised controlled trial

Background

Total knee arthroplasty (TKA) is an effective procedure for late-stage osteoarthritis (OA) of the knee; however, up to 20% of patients remain dissatisfied. In some patients, this may be due to residual inflammation of the synovium. Our aim was to perform the first randomised controlled trial (RCT) of synovectomy during TKA for patients with macroscopically inflamed synovium. The main objectives were to assess recruitment rates, protocol adherence and outcomes relating to safety such as haemoglobin decrease and adverse events. We also collected data on patient-reported outcomes.

Methods

We performed a single-centre pilot RCT. Patients with a macroscopically inflamed synovium were randomised to receive synovectomy versus a control group that did not undergo synovectomy. We determined feasibility by measuring patient enrolment, completeness of follow-up, and safety via haemoglobin decrease and documentation of adverse events.

Results

We screened 360 patients with 260 deemed ineligible or could not be recruited. From the 100 eligible patients, 54 were enrolled and 40 progressed through to randomisation. All made it to the 12-month follow-up, indicating good protocol adherence. There were no major differences in adverse events or haemoglobin decrease demonstrating acceptable safety. Outcomes relating to satisfaction were reliably obtained.

Conclusions

Patients with macroscopically inflamed synovium of the knee who are due to undergo TKA can be reliably recruited to a randomised trial and synovectomy can be performed safely. A large number is needed to be screened to identify eligible participants, and therefore, a multi-centre trial would be required to assess whether routine synovectomy would improve outcomes in these patients.

Trial registration

ISRCTN, ISRCTN31010214. Registered 6 October 2016—retrospectively registered

Electronic supplementary material

The online version of this article (10.1186/s40814-018-0336-y) contains supplementary material, which is available to authorized users.

Active exercise on immobilization-induced contractured rat knees develops arthrogenic joint contracture with pathological changes

This study investigated the effects of treadmill walking during remobilization on range of motion (ROM) and histopathology in rat knee joints, which were immobilized for 3 wk in a flexed position. After fixator removal, rats were divided into a no-intervention (RM) group and a group forced to walk on a treadmill daily at 12 m/min for 60 min (WALK group). Passive knee extension ROMs were measured before (m-ROM) and after (a-ROM) knee flexor myotomy on the first and last day of a 7-day remobilization period, with m-ROM mainly reflecting myogenic factors and a-ROM reflecting arthrogenic factors. Knee joints were histologically analyzed and gene expression of inflammatory or fibrosis-related mediators in the posterior joint capsule were examined. m-ROM and a-ROM restrictions were established after immobilization. m-ROM significantly increased following the remobilization period both in RM and WALK groups compared with that of immobilized (IM) group. Conversely, a-ROM decreased following the remobilization period in both RM and WALK groups compared with that of IM group. Importantly, a-ROM was smaller in the WALK group than the RM group. Remobilization without intervention induced inflammatory and fibrotic reactions in the posterior joint capsule after 1 and 7 days. Treadmill walking promoted these reactions and also increased the expression of fibrosis-related TGF-β1 and collagen type I and III genes. While free movement after immobilization improved myogenic contracture, arthrogenic contracture worsened. Treadmill walking further aggravated arthrogenic contracture through amplified inflammatory and fibrotic reactions. Thus active exercise immediately after immobilization may not improve immobilization-induced joint contracture.

NEW & NOTEWORTHY In clinical practice, it is widely accepted that facilitation of joint movements is effective in improving immobilization-induced joint contracture. However, whether active exercises improve arthrogenic contracture is not known. In this study, we revealed that treadmill walking further promoted remobilization-induced progression of arthrogenic contracture. To our knowledge, this is the first study demonstrating no favorable effect of active exercise on immobilization-induced arthrogenic contracture.

Fibroblasts Promote Inflammation and Pain via IL-1α Induction of the Monocyte Chemoattractant Chemokine (C-C Motif) Ligand 2

Fibroblasts persist within fibrotic scar tissue and exhibit considerable phenotypic and functional plasticity. Herein, we hypothesized that scar-associated fibroblasts may be a source of stress-induced inflammatory exacerbations and pain. To test this idea, we used a human model of surgery-induced fibrosis, total knee arthroplasty (TKA). Using a combination of tissue protein expression profiling and bioinformatics, we discovered that many months after TKA, the fibrotic joint exists in a state of unresolved chronic inflammation. Moreover, the infrapatellar fat pad, a soft tissue that becomes highly fibrotic in the post-TKA joint, expresses multiple inflammatory mediators, including the monocyte chemoattractant, chemokine (C-C motif) ligand (CCL) 2, and the innate immune trigger, IL-1α. Fibroblasts isolated from the post-TKA fibrotic infrapatellar fat pad express the IL-1 receptor and on exposure to IL-1α polarize to a highly inflammatory state that enables them to stimulate the recruitment of monocytes. Blockade of fibroblast CCL2 or its transcriptional regulator NF-κB prevented IL-1α-induced monocyte recruitment. Clinical investigations discovered that levels of patient-reported pain in the post-TKA joint correlated with concentrations of CCL2 in the joint tissue, such that the chemokine is effectively a pain biomarker in the TKA patient. We propose that an IL-1α-NF-κB-CCL2 signaling pathway, operating within scar-associated fibroblasts, may be therapeutically manipulated for alleviating inflammation and pain in fibrotic joints and other tissues.

Arthrofibrosis Associated With Total Knee Arthroplasty

BACKGROUND

Arthrofibrosis is a debilitating postoperative complication of total knee arthroplasty (TKA). It is one of the leading causes of hospital readmission and a predominant reason for TKA failure. The prevalence of arthrofibrosis will increase as the annual incidence of TKA in the United States rises into the millions.

METHODS

In a narrative review of the literature, the etiology, economic burden, treatment strategies, and future research directions of arthrofibrosis after TKA are examined.

RESULTS

Characterized by excessive proliferation of scar tissue during an impaired wound healing response, arthrofibrotic stiffness causes functional deficits in activities of daily living. Postoperative, supervised physiotherapy remains the first line of defense against the development of arthrofibrosis. Also, adjuncts to traditional physiotherapy such as splinting and augmented soft tissue mobilization can be beneficial. The effectiveness of rehabilitation on functional outcomes depends on the appropriate timing, intensity, and progression of the program, accounting for the patient's ability and level of pain. Invasive treatments such as manipulation under anesthesia, debridement, and revision arthroplasty improve range of motion, but can be traumatic and costly. Future studies investigating novel treatments, early diagnosis, and potential preoperative screening for risk of arthrofibrosis will help target those patients who will need additional attention and tailored rehabilitation to improve TKA outcomes.

CONCLUSION

Arthrofibrosis is a multi-faceted complication of TKA, and is difficult to treat without an early, tailored, comprehensive rehabilitation program. Understanding the risk factors for its development and the benefits and shortcomings of various interventions are essential to best restore mobility and function.

International consensus on the definition and classification of fibrosis of the knee joint

AIMS

The aim of this consensus was to develop a definition of post-operative fibrosis of the knee.

PATIENTS AND METHODS

An international panel of experts took part in a formal consensus process composed of a discussion phase and three Delphi rounds.

RESULTS

Post-operative fibrosis of the knee was defined as a limited range of movement (ROM) in flexion and/or extension, that is not attributable to an osseous or prosthetic block to movement from malaligned, malpositioned or incorrectly sized components, metal hardware, ligament reconstruction, infection (septic arthritis), pain, chronic regional pain syndrome (CRPS) or other specific causes, but due to soft-tissue fibrosis that was not present pre-operatively. Limitation of movement was graded as mild, moderate or severe according to the range of flexion (90° to 100°, 70° to 89°, < 70°) or extension deficit (5° to 10°, 11° to 20°, > 20°). Recommended investigations to support the diagnosis and a strategy for its management were also agreed.

CONCLUSION

The development of standardised, accepted criteria for the diagnosis, classification and grading of the severity of post-operative fibrosis of the knee will facilitate the identification of patients for inclusion in clinical trials, the development of clinical guidelines, and eventually help to inform the management of this difficult condition. Cite this article: Bone Joint J 2016;98-B:1479-88.