Intra-Articular Cytokine Levels in Adolescent Patients after Anterior Cruciate Ligament Tear

Biologic Impact of Anterior Cruciate Ligament Injury and Reconstruction

Surgical intervention after anterior cruciate ligament (ACL) tears is typically required because of the limited healing capacity of the ACL. However, mechanical factors and the inflammatory response triggered by the injury and surgery can impact patient outcomes. This review explores key aspects of ACL injury and reconstruction biology, including the inflammatory response, limited spontaneous healing, secondary inflammation after reconstruction, and graft healing processes. Understanding these biologic mechanisms is crucial for developing new treatment strategies and enhancing patient well-being. By shedding light on these aspects, clinicians and researchers can work toward improving quality of life for individuals affected by ACL tears.

Arthroscopic repair of proximal anterior cruciate ligament tears in children and adolescents: A systematic review

Purpose

Anterior cruciate ligament repair techniques are of growing interest because they allow for minimally invasive surgery that avoids harvesting of the transplant, without risking growth deficiencies in young patients. The aim of this study is to summarize the published evidence about arthroscopic repair of anterior cruciate ligament proximal tears in skeletally immature patients.

Methods

In total, four studies were included and processed for data extraction after screening for eligibility for this systematic review: one retrospective cohort study and three retrospective case series. Altogether, the four studies included in this review included 61 skeletally immature patients with a mean age of 12.1 years diagnosed with proximal anterior cruciate ligament tear who underwent arthroscopic repair with preservation of the native ligament. The mean follow-up period was 2.8 years.

Results

The most relevant and objective outcome that we considered was re-rupture rate. One study reports a cumulative incidence of graft failure in the first 3 years after surgery of 48.8% while the others report a 0%, 0% and 21.5% re-rupture rate. No growth disturbances were reported in the included studies.

Conclusion

Despite growing interest surrounding anterior cruciate ligament repair techniques, the presence of limited quality studies in the literature means repair cannot be strongly supported at present. Some encouraging data regarding the absence of growth disturbance and functional outcomes does exist, but studies with larger samples are required.

Level of evidence

level IV.

IL-6 induces periostin production in human ACL remnants: a possible mechanism causing post-traumatic osteoarthritis

OBJECTIVE

Perostin (POSTN) and IL-6 consistently elevated after ACL injury, and ACL has been proposed as the major source of POSTN. However, there is a lack of evidence whether IL-6 induces ACL remnants to produce POSTN. This study aimed to investigate the effect of IL-6 on POSTN production in ACL fibroblasts, which may help us understand more about the mechanism of PTOA after ACL injury and ACL reconstruction.

METHODS

ACL remnants were harvested from 27 patients undergoing ACL reconstruction. Quantitative real-time polymerase chain reaction (PCR) was performed to examine the POSTN gene expression of ACL fibroblasts after treatment of different concentrations of IL-6. The POSTN protein production of ACL fibroblasts was determined using western blot analysis. The blockers of possible signaling pathways, including PI3K/Akt, Ras/MAPK, and JAK/STAT pathways, were added to test whether the effect of IL-6 on ACL fibroblast could be attenuated. ACL fibroblast and chondrocyte co-culture was carried out to determine the influence of ACL and IL-6 on chondrocytes.

RESULTS

Quantitative real-time PCR showed that IL-6 time-dependently and dose-dependently increased POSTN gene expression of ACL fibroblast. Western blot analysis also revealed that IL-6 dose-dependently induced POSTN protein production. Regarding the chronicity of ACL injury, the POSTN protein production was comparable between ACL remnants which were derived within 3 months of injury and at least 6 months after injury. PI3K/Akt blockers could attenuate the effect of IL-6 on ACL remnants, whereas Ras/MAPK and JAK/STAT did not decrease POSTN production. The coexistence of ACL and IL-6 induced more MMP-13 and ADAMTS-4 by chondrocytes.

CONCLUSIONS

IL-6 induced ACL remnants to produce POSTN. This effect could be attenuated by the PI3K/Akt blocker. Coexistence of IL-6 and ACL remnants may accelerate post-traumatic arthritis.

Management of anterior cruciate ligament tears in Tanner stage 1 and 2 children: a narrative review and treatment algorithm guided by ACL tear location

The incidence of anterior cruciate ligament (ACL) tears in skeletally immature patients has acutely increased over the last 20 years, yet there is no consensus on a single "best treatment." Selection of an optimal treatment is critical and based on individual circumstances; consequently, we propose a treatment-selection algorithm based on skeletal development, ACL tear location, type, and quality, as well as parental perspective in order to facilitate the decision-making process. We combined our surgical group's extensive case histories of ACL tear management in Tanner Stage 1 and 2 patients with those in the literature to form a consolidated data base. For each case the diagnostic phase, communication with patient and parents, treatment choice(s), selected surgical techniques and rehabilitation schedule were critically analyzed and compared for patient outcomes. MRI-imaging and intraoperative tissue quality assessment were preeminent in importance for selection of the optimal treatment strategy. Considerations for selecting an optimal treatment included: associated lesions, the child/patient and parent(s)' well-informed and counseled consent, biological potential, and the potential for successful ACL preservative surgery. Complete ACL tears were evaluated according to tear-location. In type I and II ACL tears with remaining good tissue quality, we propose primary ACL repair. In type III and IV ACL tears we propose physeal-sparing reconstruction with an iliotibial band graft. Finally, in the case of a type V ACL tear, we propose that the best treatment be based on the Meyers-McKeever classification. We present a facile decision-making algorithm for ACL management in pediatric patients based on specific elements of tissue damage and status.

Prokineticin 2 and Cytokine Content in the Synovial Fluid of Knee Osteoarthritis and Traumatic Meniscal Tear Patients: Preliminary Results

Knee osteoarthritis (OA) is a chronic degenerative inflammatory-based condition caused by a cascade of different intra-articular molecules including several cytokines. Among the cytokines, prokineticins (PKs) have recently been identified as important mediators of inflammation and pain. This observational study examined the potential involvement of PK2 in degenerative or traumatic knee disease. Fifteen patients presenting knee osteoarthritis (OA group) and 15 patients presenting a traumatic meniscal tear (TM group) were studied. Synovial fluid samples from affected knees were assessed for PK2, IL-10, and TNF-α using the ELISA method. At a long-term follow-up (minimum 5 years, mean = 6.1 years), patients in the TM group underwent clinical re-evaluation with PROMs (Tegner Activity Scale, IKDC, Lysholm, SKV); in addition, X-ray visualization was used to assess the presence of secondary OA. PK2 was detected in synovial fluids of both TM and OA patients and the levels were comparable between the two groups, while IL-10 levels were significantly greater in the OA group than those in TM patients. PK2 levels correlated with those of IL-10. PK2 levels were greater in blood effusions compared to clear samples, did not differ significantly between sexes, nor were they related to differences in weight, height, or injury (meniscal laterality, time since dosing). No correlation was found between PROMs and radiological classifications in patients in the TM group at final follow-up. These data are the first observations of PK2 in synovial fluid following traumatic meniscus injury. These findings suggest possible further prognostic indices and therapeutic targets to limit the development of secondary OA.

Surgical techniques in the management of pediatric anterior cruciate ligament tears: Current concepts

Background

Anterior cruciate ligament injury in the child and adolescent patient remains a controversial topic when considering management, especially regarding surgical choices. Treatment variations are seen not just when comparing different countries but also within nations. This arises partly as contemporary treatment is mostly inferred from the adult population who physiologically and in terms of outcomes differ significantly from children. There is an increasing body of evidence for this cohort of patients who have specific challenges and difficulties when determining the optimum treatment.

Methods

Within this article, we will summarize the current evidence for surgical management of anterior cruciate ligament injury for the pediatric patient.

Results and Conclusions

There remain many controversies and gaps inthe treatment of Paediatric Anterior cruciate ligament reconstruction and this high risk cohort continues to cause difficulty in identifying the best mode of surgical management.

Level of evidence

level IV.

Osteochondritis dissecans of the knee: Imaging, instability concept, and criteria

Osteochondritis dissecans of the knee is an idiopathic, focal, subchondral-bone abnormality that can cause instability or detachment of a bone fragment and overlying articular cartilage, with subsequent progression to osteoarthritis. The degree of lesion instability is best assessed by magnetic resonance imaging. Unstable lesions require operative management with fragment fixation. Level of evidence: V.

Osteochondritis dissecans of the knee: Epidemiology, etiology, and natural history

Osteochondritis dissecans of the knee is a disease that typically affects skeletally immature patients. Clinically manifested with knee pain, limping, and joint disfunction, this condition has remained misunderstood and undervalued for a long period. Although being a rare condition, its awareness is of utmost clinical interest because of the possible severe consequences it can bring when misrecognized or inadequately treated. Its etiology remains unclear and is still debated. Many theories have been proposed, including inflammation, local ischemia, subchondral ossification abnormalities, genetic factors, and repetitive mechanical microtrauma, with a likely interplay of the same. This review article aims to deliver and discuss current and up-to-date concepts on epidemiology, etiology, and natural history of this pediatric condition. Level of evidence: level V.

Pediatric anterior cruciate ligament tears and associated lesions: Epidemiology, diagnostic process, and imaging

The incidence of anterior cruciate ligament injuries in skeletally immature patients has increased in recent years. The gold standard treatment of this type of trauma in children is not yet established. Conservative management may underestimate the risk of new meniscal and chondral tears; on the other hand, a more interventional approach may expose the patient to iatrogenic damage to the growth plate. A correct approach to the skeletally immature patient with knee trauma is therefore essential to guide the decision-making process. This review article aims to present an update on the epidemiology and diagnostic process of pediatric patients with anterior cruciate ligament tears and possible associated injuries. Level of Evidence: V.

Characterization of microRNA Levels in Synovial Fluid from Knee Osteoarthritis and Anterior Cruciate Ligament Tears

This study investigated modifications of microRNA expression profiles in knee synovial fluid of patients with osteoarthritis (OA) and rupture of the anterior cruciate ligament (ACL). Twelve microRNAs (26a-5p, 27a-3p, let7a-5p, 140-5p, 146-5p, 155-5p, 16-5p,186-5p, 199a-3p, 210-3p, 205-5p, and 30b-5p) were measured by real-time quantitative polymerase chain reaction (RT-qPCR) in synovial fluids obtained from 30 patients with ACL tear and 18 patients with knee OA. These 12 miRNAs were chosen on the basis of their involvement in pathological processes of bone and cartilage. Our results show that miR-26a-5p, miR-186-5p, and miR-30b-5p were expressed in the majority of OA and ACL tear samples, whereas miR-199a-3p, miR-210-3p, and miR-205-5p were detectable only in a few samples. Interestingly, miR-140-5p was expressed in only one sample of thirty in the ACL tear group. miR-140-5p has been proposed to modulate two genes (BGN and COL5A1100) that are involved in ligamentous homeostasis; their altered expression could be linked with ACL rupture susceptibility. The expression of miR-30b-5p was higher in OA and chronic ACL groups compared to acute ACL samples. We provide evidence that specific miRNAs could be detected not only in synovial fluid of patients with OA, but also in post-traumatic ACL tears.

Clinical efficacy of repeated intra-articular pulsed radiofrequency for the treatment of knee joint pain and its effects on inflammatory cytokines in synovial fluid of patients

The application value of repeated intra-articular pulsed radiofrequency for the treatment of knee joint pain has remained to be determined. To investigate this, a total of 64 patients with chronic knee joint pain admitted to Caoxian People's Hospital (Caoxian, Chine) between October 2016 and May 2018 were enrolled in the present study and analyzed prospectively. The patients were randomly divided into a control group, receiving treatment with a single intra-articular pulsed radiofrequency through the knee joint (n=32), and an experimental group, receiving multiple intra-articular pulsed radiofrequency treatments through the knee joint (n=32). The visual analog scale score (VAS), clinical efficacy and adverse reactions prior to and after treatment were compared between the two treatments. Synovial fluid cytokines were measured using ELISA prior to and after treatment. After the treatment, the control group and the experimental group both had a lower VAS (P<0.001) and the control group had a higher VAS and lower pain relief than the experimental group (P<0.001). The control group had a total effectiveness rate of 78.13%, with 13 patients experiencing complete relief (40.63%), 12 patients exhibiting a marked improvement (37.5%) and 7 patients reporting no effects (21.87%). The experimental group had a total effectiveness rate of 90.63%, with 18 patients (56.25%) being cured, 11 patients having a marked effect (34.37%) and 3 patients reporting no effects (9.38%). The experimental group had a higher incidence of adverse reactions than the control group (P<0.05). After treatment, the two groups had decreased IL-6, IL-10 and TNF-α levels in the knee joint synovial fluid (P<0.05), with the experimental group having lower cytokine levels than the control group (P<0.05). These results indicated that repeated intra-articular pulsed radiofrequency is an effective method for the treatment of knee joint pain and may be used in clinical practice.

Resolvin E1 and Cytokines Environment in Skeletally Immature and Adult ACL Tears

The intra-articular synovial fluid environment in skeletally immature patients following an ACL tear is complex and remains undefined. Levels of inflammatory and anti-inflammatory cytokines change significantly in response to trauma and collectively define the inflammatory environment. Of these factors the resolvins, with their inherent anti-inflammatory, reparative, and analgesic properties, have become prominent. This study examined the levels of resolvins and other cytokines after ACL tears in skeletally immature and adult patients in order to determine if skeletal maturity affects the inflammatory pattern. Skeletally immature and adult patients with an anterior cruciate ligament injury and meniscal tears were prospectively enrolled over a 5-month period. Synovial fluid samples were obtained before surgery quantifying Resolvin E1, IL-1β, TNF-α, and IL-10 by ELISA. Comparisons between skeletally immature patients and adults, the influence of meniscal tear, growth plate maturity and time from trauma were analyzed. Skeletally immature patients had significantly greater levels of Resolvin E1 and IL-10 compared with adults with an isolated anterior cruciate ligament lesion. Among the injured skeletally immature patients Resolvin E1 levels were greater in the open growth plate group compared with those with closing growth plates. Moreover, levels of Resolvin E1 and IL-10 appeared to decrease with time. Our results suggest that skeletally immature patients have a stronger activation of the Resolvin pattern compared to adult patients and that synovial fluid Resolvins could play an antinflammatory role in the knee after anterior cruciate ligament lesion and that its activity may be synergistic with that of IL-10.

Characterization of Synovial Cytokine Patterns in Bucket-Handle and Posterior Horn Meniscal Tears

The specific etiology of meniscal tears, including the mechanism of lesion, location, and orientation, is considered for its contribution to subsequent joint cytokine responsiveness, healing outcomes, and by extension, appropriate lesion-specific surgical remediation. Meniscal repair is desirable to reduce the probability of development of posttraumatic osteoarthritis (PTOA) which is strongly influenced by the coordinate generation of pro- and anti-inflammatory cytokines by the injured cartilage. We now present biochemical data on variation in cytokine levels arising from two particular meniscal tears: bucket-handle (BH) and posterior horn (PH) isolated meniscal tears. We selected these two groups due to the different clinical presentations. We measured the concentrations of TNF-α, IL-1β, IL-6, IL-8, and IL-10 in knee synovial fluid of 45 patients with isolated meniscal lesions (BH tear, n = 12; PH tear, n = 33). TNF-α levels were significantly (p < 0.05) greater in the BH group compared with the PH group, whereas IL-1β levels were significantly greater (p < 0.05) in the PH group compared with the BH group. Both BH and PH groups were consistent in presenting a positive correlation between concentrations of IL-6 and IL-1β. A fundamental difference in IL-10 responsiveness between the two groups was noted; specifically, levels of IL-10 were positively correlated with IL-6 in the BH group, whereas in the PH group, levels of IL-10 were positively correlated with IL-1β. Collectively, our data suggest a possible influence of the meniscal tear pattern to the articular cytokine responsiveness. This differential expression of inflammatory cytokines may influence the risk of developing PTOA in the long term.

COMP in the Infrapatellar Fat Pad-Results of a Prospective Histological, Immunohistological, and Biochemical Case-Control Study

Knee osteoarthritis (OA) involves several structures and molecules in the joint, which interact in a pathophysiological process. One of these molecules is the cartilage oligomeric matrix protein (COMP). Elevated COMP levels in the synovial fluid as well as in the serum have been described in OA patients. However, this has not been described in the infrapatellar fat pad (IPFP) tissue before. In this prospective trial, we collected 14 IPFPs from patients with high-grade OA (mean age 63.8 ± 17.6 years) who underwent total knee replacement (OA group) and from 11 healthy patients (mean age 33.7 ± 14.8 years) who underwent anterior cruciate ligament reconstruction (control group). The presence of macrophages (CD68 and CD206) and proinflammatory cytokines (interleukin 1β [IL-1β] and IL-6) was analyzed. Histological and immunohistological examinations as well as immunoblotting analysis for COMP, leptin, and matrix-metalloproteinase-3 were performed. The IPFPs of both the OA and control group consisted of adipose tissue and fibrous tissue, and the fibrous tissue showed higher score values than the adipose tissue for COMP staining (intensity as well as stained area) in both groups. Although COMP could be detected in most samples, leptin expression was found only in single specimens. COMP could be detected mostly in the fibrous tissue portion of the IPFP. We speculate that it is involved in a remodeling process taking place in the IPFP during OA. Presence of leptin was irregular in immunohistology, and the control group showed higher scores in case of presence. Interestingly, immunoblotting could detect leptin in all analyzed samples. © 2019 The Authors. Journal of Orthopaedic Research® published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society J Orthop Res 38:747-758, 2020.

Association of chemokine expression in anterior cruciate ligament deficient knee with patient characteristics: Implications for post-traumatic osteoarthritis

BACKGROUND

Stromal cell-derived factor-1a (SDF-1α) and high mobility group box chromosomal protein 1 (HMGB1) are chemokines that can drive post-traumatic osteoarthritis (PTOA) induced by anterior cruciate ligament (ACL) injury. However, the influence of patient characteristics on expression of those chemokines remains unclear. Our aim was to determine the relationship between chemokine expression in synovial fluid (SF) of the ACL-deficient (ACL-D) knee and patient characteristics including time from injury, sex, and age.

METHODS

SF samples were collected immediately prior to the first-time ACL reconstruction (ACLR) from 82 patients. Expression of SDF-1α and HMGB1 was measured with human-specific solid phase sandwich enzyme-linked immunosorbent assays. The expression levels between groups divided by time from injury, or age, or sex was compared using Student's t-test. The association of SDF-1α or HMGB1 levels with those variables was determined using regression analysis and Pearson product-moment correlation coefficient.

RESULTS

Regression and correlation analysis indicated significant correlation between SDF-1α expression and time from injury in the cohort (r = -0.266, P = 0.016, n = 82) and in females (r = -0.386, P = 0.024, n = 34). Significant correlation was also observed between SDF-1α expression and age in the cohort (r = -0.224, P = 0.043, n = 82) and in males (r = -0.289, P = 0.046, n = 48). No significant correlation between HMGB1 expression and patient characteristics was detected.

CONCLUSIONS

SDF-1α rather than HMGB1 might serve as a protein marker for monitoring the development of PTOA in the ACL-D knee, especially in female patients.