Biochemical markers in the diagnosis of chondral defects following anterior cruciate ligament insufficiency

Biomarkers for Osteoarthritis Diseases

Growing evidence has revealed the pivotal role of inflammatory biomarkers in the pathogenesis of osteoarthritis. There is significant interest in the prognostic value of select biomarkers, given the potential for early identification and treatment of patients at risk of osteoarthritis prior to the development of irreversible clinical disease. Clinical trials of novel therapeutics that disrupt the inflammatory pathways of osteoarthritis are also ongoing. The purpose of this review is to summarize the current literature on key biomarkers within the context of osteoarthritis pathogenesis, clinical symptom development, and treatment capabilities. Multiple recent studies have established biomarkers that signal the existence of osteoarthritis pathology and the development of clinical symptomology. However, prior to implementation in clinical practice, additional research is required to precisely define the prognostic value for numerous biomarkers and standardize their measurement. Biomarker-driven investigations represent a promising avenue for the early diagnosis and treatment of osteoarthritis.

Editorial Commentary: Serum Cartilage Oligomeric Matrix Protein Appears to Be the Most Useful Biomarker for Tracking Early Osteoarthritis of the Knee in Anterior Cruciate Ligament Deficient Patients (But May Also Reflect Synovitis)

Owing to chondral or meniscal pathology sustained at the time of injury, patients who sustain anterior cruciate ligament injury are at risk of knee osteoarthritis (OA). Thus, recognition of early OA is critical. Detection of joint space narrowing on radiography has been described as outdated, and furthermore, the different descriptions of the Kellgren-Lawrence criteria have an impact on the classification of OA of the lowest grade (Kellgren-Lawrence grade ≥ 1). Serum cartilage oligomeric matrix protein (COMP) may allow detection of early OA in patients with anterior cruciate ligament deficiency because significantly higher levels have been observed in patients with early OA than in patients with non-early OA. Serum COMP appears to be the most useful of the biomarkers studied. Prior studies have shown correlations with OA in animal models and via magnetic resonance imaging evaluation. However, I would be hesitant about widespread use. It is possible that the serum COMP level reflects not only cartilage damage but also synovitis. This may be particularly misleading in patients with diagnoses of rheumatologic disorders and/or undiagnosed genetic HLA-B27 variants.

Serum Cartilage Oligomeric Matrix Protein Detects Early Osteoarthritis in Patients With Anterior Cruciate Ligament Deficiency

PURPOSE

To investigate the ability of serum cartilage oligomeric matrix protein (COMP) to detect early osteoarthritis (OA) (International Cartilage Research Society [ICRS] grade 1 or 2 cartilage lesions) in patients with anterior cruciate ligament (ACL)-deficient patients.

METHODS

Patients with an ACL injury of Kellgren-Lawrence grade 0 or 1 were enrolled. Serum samples for COMP measurement were obtained before surgery. The cartilage surfaces of 6 compartments were classified using the ICRS grading system. The patients were divided into groups with and without early OA according to the cartilage findings and diagnostic criteria for early OA.

RESULTS

In total, 98 patients (mean age 23.7 years; range 12 to 49) were included, with 30 patients (30.6%) in the early OA group and 68 (69.4%) in the no early OA group. The 2 groups significantly differed in age, body mass index, preoperative Tegner activity scale, and serum COMP level. The cutoff value of serum COMP for the presence of early OA arthroscopic cartilage lesions was 152.0 ng/mL. Multiple logistic regression analysis revealed age (odds ratio 1.09; 95% confidence interval [CI] 1.02 to 1.16; P = .01) and serum COMP (odds ratio 1.02; 95% CI 1.01 to 1.04; P < .001) to be independent factors for the presence of early OA arthroscopic cartilage findings.

CONCLUSIONS

The incidence of early OA arthroscopic cartilage findings was ∼30% in patients with ACL deficiency, and serum COMP levels were significantly higher in the early OA group than in the no early OA group. The optimum cutoff value for serum COMP was 152 ng/mL. Serum COMP can be used to detect early cartilage change in patients with ACL deficiency.

LEVEL OF EVIDENCE

Ⅲ, retrospective comparative study.

Modified exorotation graft tension for tibial fixation in anterior cruciate ligament reconstruction: a randomized controlled trial

Background: The inability of anterior cruciate ligament reconstruction (ACLR) surgery to reduce tibial internal rotation causes many problems. A large tibial internal rotation will result in a patellofemoral pain syndrome. This study aimed to introduce a new technique of modified exorotation graft tension at tibial fixation to minimize endorotation, reduce tibial internal rotation, and prevent patellofemoral pain syndrome.Methods: This study was a randomized double-blind controlled clinical trial. ACL rupture patients underwent ACLR surgery between December 2014 and Februrary 2015. They were randomized to standard endorotation group or modified exorotation group. Hamstring autograft was used and fixed with an EndoButton® and bioabsorbable interference screw. Tibial tubercle to trochlear grove (TTTG) was used to evaluate rotation, whereas cartilage oligomeric matrix protein (COMP) was employed to analyze cartilage breakdown. The functional outcome was measured using the Kujala score to assess patellofemoral joint function. Evaluations were conducted before the surgery and at 6 months postoperation.Results: A total of 29 subjects were recruited. Sixteen subjects were allocated into the standard endorotation group, and 13 were assigned to the modified exorotation group. The exorotation group demonstrated better results than the endorotation group in all three parameters: TTTG (p=0.028), COMP (p<0.001), and Kujala score (p=0.015).Conclusion: A new technique of modified exorotation direction of graft tension for ACL reconstructive surgery at tibial fixation showed a significant reduction in tibial internal rotation and cartilage breakdown. The proposed method could significantly improve the functional outcome of those with total ACL rupture.

Chondrocyte secretome: a source of novel insights and exploratory biomarkers of osteoarthritis

The extracellular matrix (ECM) of articular cartilage is comprised of complex networks of proteins and glycoproteins, all of which are expressed by its resident cell, the chondrocyte. Cartilage is a unique tissue given its complexity and ability to resist repeated load and deformation. The mechanisms by which articular cartilage maintains its integrity throughout our lifetime is not fully understood, however there are numerous regulatory pathways known to govern ECM turnover in response to mechanical stimuli. To further our understanding of this field, we envision that proteomic analysis of the secretome will provide information on how the chondrocyte remodels the surrounding ECM in response to load, in addition to providing information on the metabolic state of the cell. In this review, we attempt to summarize the recent mass spectrometry-based proteomic discoveries in healthy and diseased cartilage and chondrocytes, to facilitate the discovery of novel biomarkers linked to degenerative pathologies, such as osteoarthritis (OA).

A Multicenter Study of Early Anti-inflammatory Treatment in Patients With Acute Anterior Cruciate Ligament Tear

BACKGROUND

It is increasingly recognized that biochemical abnormalities of the joint precede radiographic abnormalities of posttraumatic osteoarthritis (PTOA) by as much as decades. A growing body of evidence strongly suggests that the progression from anterior cruciate ligament (ACL) injury to PTOA is multifactorial, involving the interplay between biomechanical disturbances and biochemical homeostasis of articular cartilage.

PURPOSE

The purposes of this randomized study using an acute ACL injury model were to (1) evaluate the natural progression of inflammatory and chondrodegenerative biomarkers, (2) evaluate the relationship between subjective reports of pain and inflammatory and chondrodegenerative biomarkers, and (3) determine if postinjury arthrocentesis and corticosteroid injection offer the ability to alter this biochemical cascade.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 2.

METHODS

A total of 49 patients were randomized to 4 groups: group 1 (corticosteroid at 4 days after ACL injury, placebo injection of saline at 2 weeks), group 2 (placebo at 4 days after ACL injury, corticosteroid at 2 weeks), group 3 (corticosteroid at both time intervals), or a placebo group (saline injections at both time intervals). Patient-reported outcome measures and synovial biomarkers were collected at approximately 4 days, 11 days, and 5 weeks after injury. The change between the time points was assessed for all variables using Wilcoxon tests, and the relationship between changes in outcome scores and biomarkers were assessed by calculating Spearman ρ. Outcomes and biomarkers were also compared between the 4 groups using Kruskal-Wallis tests.

RESULTS

No adverse events or infections were observed in any study patients. With the exception of matrix metalloproteinase 1 (MMP-1) and tumor necrosis factor-inducible gene 6 (TSG-6), chondrodegenerative markers worsened over the first 5 weeks while all patient-reported outcomes improved during this time, regardless of treatment group. Patient-reported outcomes did not differ between patients receiving corticosteroid injections and the placebo group. However, increases in C-telopeptide of type II collagen (CTX-II), associated with collagen type II breakdown, were significantly greater in the placebo group (1.32 ± 1.10 ng/mL) than in either of the groups that received the corticosteroid injection within the first several days after injury (group 1: 0.23 ± 0.27 ng/mL [ P = .01]; group 3: 0.19 ± 0.34 ng/mL [ P = .01]).

CONCLUSION

PTOA begins at the time of injury and results early on in dramatic matrix changes in the knee. However, it is encouraging that early intervention with an anti-inflammatory agent was able to affect biomarkers of chondral degeneration. Should early intervention lead to meaningful changes in either the onset or severity of symptomatic PTOA, the current treatment paradigm for patients with ACL injury may have to be restructured to include early aspiration and intra-articular intervention.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT01692756.

Imaging following acute knee trauma

Joint injury has been recognized as a potent risk factor for the onset of osteoarthritis. The vast majority of studies using imaging technology for longitudinal assessment of patients following joint injury have focused on the injured knee joint, specifically in patients with anterior cruciate ligament injury and meniscus tears where a high risk for rapid onset of post-traumatic osteoarthritis is well known. Although there are many imaging modalities under constant development, magnetic resonance (MR) imaging is the most important instrument for longitudinal monitoring after joint injury. MR imaging is sensitive for detecting early cartilage degeneration and can evaluate other joint structures including the menisci, bone marrow, tendons, and ligaments which can be sources of pain following acute injury. In this review, focusing on imaging following acute knee trauma, several studies were identified with promising short-term results of osseous and soft tissue changes after joint injury. However, studies connecting these promising short-term results to the development of osteoarthritis were limited which is likely due to the long follow-up periods needed to document the radiographic and clinical onset of the disease. Thus, it is recommended that additional high quality longitudinal studies with extended follow-up periods be performed to further investigate the long-term consequences of the early osseous and soft tissue changes identified on MR imaging after acute knee trauma.

Osteoarthritis year 2012 in review: biomarkers

PURPOSE

Biomarkers provide useful diagnostic information by detecting cartilage degradation in osteoarthritis (OA), reflecting disease-relevant biological activity and predicting the course of disease progression. They also serve as surrogate endpoints in the drug discovery process. The aim of this narrative review was to focus on OA biomarker-related papers published between the osteoarthritis research society international (OARSI) 2011 meeting in San Diego and the OARSI 2012 meeting in Barcelona.

METHODS

The PubMed/MEDLINE and SciVerse Scopus bibliographic databases were searched using the keywords: 'biomarker' and 'osteoarthritis' and/or 'biomarker' and 'proteomics'.

RESULTS

Ninety-eight papers were found with the keywords 'biomarker' and 'osteoarthritis'. Fifteen papers were found with the keywords 'biomarker' and 'proteomics'. Review articles were also included. The most relevant published studies focused on extracellular matrix (ECM) molecules in body fluids. Enrichment of the deamidated epitope of cartilage oligomeric matrix protein (D-COMP) suggests that OA disease progression is associated with post-translational modifications that may show specificity for particular joint sites. Fibulin-3 peptides (Fib3-1 and Fib3-2) have been proposed as potential biomarkers of OA along with follistatin-like protein 1 (FSTL1), a new serum biomarker with the capacity to reflect the severity of joint damage. The 'membrane attack complex' (MAC) component of complement has also been implicated in OA.

CONCLUSION

Novel OA biomarkers are needed for sub-clinical disease diagnosis. Proteomic techniques are beginning to yield useful data and deliver new OA biomarkers in serum and urine. Combining biochemical markers with tissue and cell imaging techniques and bioinformatics (i.e., machine learning, clustering, data visualization) may facilitate the development of biomarker combinations enabling earlier detection of OA.

Anterior cruciate ligament deficiency leads to early instability of scaffold for cartilage regeneration: a controlled laboratory ex-vivo study

PURPOSE

The affect of anterior cruciate ligament (ACL) integrity on the early postoperative stability of a collagen type-I gel scaffold was investigated. The value of fibrin glue for graft fixation in ACL deficient porcine knees over a simulated early postoperative period was also studied.

METHODS

Full-thickness articular cartilage defects (11 × 6 mm) were created on the medial femoral condyle of 80 porcine knees. The ACL was left intact or completely transected in each of 40 knees. Gel plugs were tested in each group: press-fitting only in 20 specimens and press-fitting plus fibrin glue in 20 specimens. Each knee underwent 2,000 cycles in a validated ex-vivo continuous passive motion model.

RESULTS

Press-fit-only fixation grafts in knee specimens with an intact ACL showed significantly superior stability than that in ACL deficient knees (p = 0.01). In ACL deficient knees, grafts fixed with press-fitting plus fibrin glue showed significantly superior stability than those using press-fit only fixation (p = 0.01). Press-fitting plus fibrin glue fixation showed no significant differences in worn surface area between knee specimens with intact and deficient ACL.

CONCLUSIONS

ACL deficiency led to early scaffold instability in an ex-vivo porcine knee model. Fibrin glue in ACL deficient knees led to additional graft stability. These findings indicated that cartilage regenerative techniques may give optimum results in ACL intact knees.