Biochemical markers of postsurgical knee arthrofibrosis: A systematic review

Immunophenotyping of Synovial Tissue in Adolescents Undergoing ACL Reconstruction: What Is the Role of Synovial Inflammation in Arthrofibrosis?

BACKGROUND

Loss of motion and arthrofibrosis after anterior cruciate ligament (ACL) reconstruction (ACLR) can be devastating complications for athletes. The cellular and molecular pathogenesis of arthrofibrosis is poorly understood, limiting prevention and treatment options. Synovial inflammation may contribute to post-ACLR arthrofibrosis.

HYPOTHESIS

Higher synovial immune cell infiltration and inflammatory/catabolic gene expression patterns at the time of ACLR would correlate with poorer motion-related outcomes.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Patients aged 10 to 18 years undergoing primary ACLR were enrolled in a prospective pilot study, and synovial tissue biopsy specimens were obtained during ACLR. Flow cytometry and single-cell RNA sequencing explored synovial cell types/frequencies and gene expression. Principal component analysis was performed, followed by clustering which grouped patients into distinct immunophenotypes based on their synovial cell composition. Clinical follow-up data with knee range of motion (ROM), need for lysis of adhesions, and patient-reported outcome measures were collected and compared between immunophenotypes.

RESULTS

Enrolled patients (n = 17) underwent ACLR at a median of 37 days after injury. Analysis revealed 3 distinct immunophenotypes. Type 1 consisted of patients with the longest time between injury and surgery and the lowest hematopoietic and T-cell infiltration. Types 2 and 3 had similar times between injury and surgery; type 2 had intermediate while type 3 had the highest hematopoietic and T-cell percentages. Type 3 was associated with worse ROM at 2 and 6 weeks postoperatively; T-cell prevalence and ROM were inversely correlated at those time points. The only patient requiring lysis of adhesions for arthrofibrosis had a type 3 immunophenotype.

CONCLUSION

Synovial immune infiltration after ACL injury shows variability between patients that clusters into 3 immunophenotypes correlating with early ROM and the risk of arthrofibrosis. T-cell recruitment and infiltration were the strongest factors correlated with ROM outcomes and present an exciting venue for future research on post-ACLR arthrofibrosis.

Female Sex, Older Age, Earlier Surgery, Anticoagulant Use, and Meniscal Repair Are Associated With Increased Risk of Manipulation Under Anesthesia or Lysis of Adhesions for Arthrofibrosis After Anterior Cruciate Ligament Reconstruction: A Systematic Review

PURPOSE

To determine what patient or surgical factors are associated with an increased risk of arthrofibrosis requiring manipulation under anesthesia (MUA) or lysis of adhesions (LOA) after anterior cruciate ligament reconstruction (ACLR).

METHODS

A systematic review was performed in adherence to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Cochrane, Embase, and Medline databases were searched for studies published through February 2023. Inclusion criteria were studies that identified risk factors for MUA and/or LOA after ACLR. Studies investigating arthrofibrosis after multiligamentous knee injuries or ACL repair were excluded.

RESULTS

Eleven studies including a total of 333,876 ACLRs with 4,842 subsequent MUA or LOA (1.45%) were analyzed. Increasing age was associated with an increased risk in 3 studies (P < .001, P < .05, P < .01) but was found to have no association another two. Other factors that were identified by multiple studies as risk factors for MUA/LOA were female sex (4 studies), earlier surgery (5 studies), use of anticoagulants other than aspirin (2 studies), and concomitant meniscal repair (4 studies).

CONCLUSIONS

In total, 1.45% of the patients who underwent ACLR and were included in this systematic review had to undergo a subsequent MUA/LOA to treat arthrofibrosis. Female sex, older age, earlier surgery, use of anticoagulants other than aspirin, and concomitant meniscal repair were associated with increased risk of MUA/LOA. The modifiable risks, including use of anticoagulants and time between injury and surgery, can be considered when making treatment decisions.

LEVEL OF EVIDENCE

Level IV, systematic review of Level III-IV studies.

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.