The novel epiligament theory: differences in healing failure between the medial collateral and anterior cruciate ligaments

According to current literature, 90% of knee ligament injuries involve the medial collateral ligament or the anterior cruciate ligament. In contrast to the medial collateral ligament, which regenerates relatively well, the anterior cruciate ligament demonstrates compromised healing. In the past, there were numerous studies in animal models that examined the healing process of these ligaments, and different explanations were established. Although the healing of these ligaments has been largely investigated and different theories exist, unanswered questions persist.Therefore, the aim of this article is 1) to review the different historical aspects of healing of the medial collateral ligament and present the theories for healing failure of the anterior cruciate ligament; 2) to examine the novel epiligament theory explaining the medial collateral ligament healing process and failure of anterior cruciate ligament healing; and 3) to discuss why the enveloping tissue microstructure of the aforementioned ligaments needs to be examined in future studies.We believe that knowledge of the novel epiligament theory will lead to a better understanding of the normal healing process for implementing optimal treatments, as well as a more holistic explanation for anterior cruciate ligament healing failure.

Differences in the expression profiles of lncRNAs and mRNAs in partially injured anterior cruciate ligament and medial collateral ligament of rabbits

Long noncoding RNAs (lncRNAs), as a novel regulatory factor, are considered to play a vital role in various biological processes and diseases. However, the overall expression profile and biological functions of lncRNAs in the partially injured anterior cruciate ligament (ACL) and medial collateral ligament (MCL) have not been clearly explored. Partially injured models of ACL and MCL were established in 3-month-old healthy male New Zealand white rabbits. Expression of lncRNAs and mRNAs in the ligament tissue was detected by high-throughput sequencing technology, and biological functions of differentially expressed RNAs were evaluated by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. Validation of several differentially expressed RNAs was performed using quantitative real-time PCR (qRT-PCR). Protein-protein interaction (PPI) analysis and competitive endogenous RNA (ceRNA) prediction were used to identify interactions among hub genes and the interaction among lncRNAs, miRNAs, and mRNAs. The results showed that compared with the normal group, there were 267 mRNAs and 329 lncRNAs differentially expressed in ACL and 726 mRNAs and 609 lncRNAs in MCL in the injured group. Compared with MCL, 420 mRNAs and 470 lncRNAs were differentially expressed in ACL in the normal group; 162 mRNAs and 205 lncRNAs were differentially expressed in ACL in the injured group. Several important lncRNAs and genes were identified, namely, COL7A1, LIF, FGFR2, EPHA2, CSF1, MMP2, MMP9, SOX5, LOX, MSTRG.1737.1, MSTRG.26038.25, MSTRG.20209.5, MSTRG.22764.1, and MSTRG.18113.1, which are closely related to inflammatory response, tissue damage repair, cell proliferation, differentiation, migration, and apoptosis. Further study of the functions of these genes may help to better understand the specific molecular mechanisms underlying the occurrence of endogenous repair disorders in ACL, which may provide new ideas for further exploration of effective means to promote endogenous repair of ACL injury.

Effects of type II collagen hydrolysates on osteoarthritis through NF-ĸB, Wnt/β-catenin and MAPK pathways

Osteoarthritis (OA), a degenerative disease, has attracted extensive attention all over the world. In the study, medial meniscus resection (MMx) and anterior to medial collateral ligament (ACL) operation rat model...

Treatment of Medial Collateral Ligament Injuries of the Knee with Focused Extracorporeal Shockwave Therapy: A Case Report

Medial collateral ligament (MCL) injuries are the most frequent ligamentous injuries of the knee. Focused extracorporeal shock wave therapy (f-ESWT) is progressively expanding its field of application to many musculoskeletal pathologies. Although there is evidence surrounding the efficacy of f-ESWT in tendinopathies, no studies have described the usefulness of ultrasound (US)-guided f-ESWT in the treatment of ligament injuries. Herein, we report a case of a MCL injury treated with f-ESWT. Moreover, our case shows the importance of using ultrasonography in determining the effect of treatment. A 60-year-old man with a focal area of lesion in the deep fibers underwent 4 weekly sessions of US-guided f-ESWT to the injured ligament area. His pain decreased to a visual analog scale (VAS) of 3 at the end of the treatment and was completely resolved at the 1-month follow-up visit, with these results being maintained at 4-month follow-up. The US examination showed an initial deposition of “newly formed tissue” at the site of previous injury of the proximal MCL insertion, and a reduction in MCL thickness together with an improvement in echostructure. Based on this result, we speculate that non-surgical ligament injuries could be a new indication for f-ESWT. However, further investigation on the effects of f-ESWT for ligament injuries is needed.

The Influence of Medial Collateral Ligament and Lateral Collateral Ligament Pie Crusting in Primary Total Knee Arthroplasty on Patient Reported Outcomes

Background and Hypothesis: Pie-crusting of the collateral ligaments can help achieve balanced gaps in total knee arthroplasty (TKA) in knees with varus or valgus deformity. However, the effect of this technique on patient-reported outcome measures (PROMs) is unknown. The purpose of this study was to compare PROMs following primary TKA for patients with and without medial collateral ligament (MCL) or lateral collateral ligament (LCL) pie-crusting. Experimental Design or Project Methods: We retrospectively reviewed 1,305 primary TKAs. Intraoperative MCL or LCL pie-crusting was documented in all operative reports and recorded. Prospectively collected preoperative, 4-month postoperative, and minimum 1-year postoperative PROMs related to overall knee health, pain during functional activities, activity level, and overall satisfaction were compiled and compared between patients with and without MCL or LCL pie-crusting. Medians were evaluated with Kruskal-Wallis test adjusted for ties. Results: The cohort was 67% female with mean age 66 years and BMI 34.0 kg/m2. MCL or LCL pie-crusting was performed in 13.0% of the cohort. There were no intraoperative or postoperative ruptures of the MCL or LCL. 6.3% of conforming bearing TKAs required a collateral ligament pie crusting versus 21.5% of standard bearing TKA (p<0.001). No significant differences were found in preoperative, 4-month, minimum 1-year, or change from preoperative baseline to minimum 1-year PROMs with and without pie-crusting of the collateral ligaments (p≥0.095). However, the LCL pie-crusting group had slightly better PROMs at minimum 1-year. Conclusion and Potential Impact: These study results corroborate existing literature that pie-crusting of collateral ligaments is safe and effective to achieve a balanced TKA. Additionally, no significant outcome differences were found between groups with and without MCL or LCL pie-crusting. However, LCL pie-crusting for valgus knee correction had slightly better PROMs. Interestingly, conforming bearings may impart enhanced stability and mitigate the need for pie-crusting ligament releases in TKA.