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.

Image Guided Injection of Anterior Cruciate Ligament Tears with Autologous Bone Marrow Concentrate and Platelets: Midterm Analysis from A Randomized Controlled Trial

Background: There has been a recent emergence in the use of orthobiologics, including platelet-rich plasma (PRP) and bone marrow concentrate (BMC), in the treatment of various musculoskeletal conditions. The goal of this study was to determine if injection of BMC and platelet products into partial and full-thickness anterior cruciate ligament (ACL) tears can facilitate primary ligament healing in patients failing conservative care, resulting in improved outcomes compared to exercise therapy.Methods: Patients were randomized to either exercise therapy or percutaneous injection of autologous BMC with PRP and platelet lysate into the ACL under fluoroscopic guidance. Pain and function were assessed at baseline and at 1, 3, 6, 12, and 24 months. Baseline and 6-month post-treatment magnetic resonance imaging (MRI) were obtained to evaluate interval healing. Laxity was assessed using the Telos device.Results: There was significant improvement in functional outcomes in the BMC group, compared to base-line for LEFS at time points 3 up to 24 months s = 0.000000005), and significant improvement in pain in the BMC group at 6 (p = 0.00054), 12 (p = 0.00127), and 24 months (p = 0.002). There was no significant improvement in pain or function at any time point in the exercise therapy group. There was significant improvement in ACL MRI ImageJ quantitative assessment in the BMC group (p = 0.001) and no difference in the exercise group (p > 0.05). No serious adverse events were reported.Conclusion: Autologous BMC and platelet product injection into ACL tears improved patient function compared to exercise, observed through 24 months. Patients treated with BMC demonstrated quantitative improvements in post-treatment MRI scans suggestive of interval ligament healing.

Mesenchymal Stem Cell-Derived Extracellular Vesicles in Tendon and Ligament Repair—A Systematic Review of In Vivo Studies

Tendon and ligament injury poses an increasingly large burden to society. This systematic review explores whether mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) can facilitate tendon/ligament repair in vivo. On 26 May 2021, a systematic search was performed on PubMed, Web of Science, Cochrane Library, Embase, to identify all studies that utilised MSC-EVs for tendon/ligament healing. Studies administering EVs isolated from human or animal-derived MSCs into in vivo models of tendon/ligament injury were included. In vitro, ex vivo, and in silico studies were excluded, and studies without a control group were excluded. Out of 383 studies identified, 11 met the inclusion criteria. Data on isolation, the characterisation of MSCs and EVs, and the in vivo findings in in vivo models were extracted. All included studies reported better tendon/ligament repair following MSC-EV treatment, but not all found improvements in every parameter measured. Biomechanics, an important index for tendon/ligament repair, was reported by only eight studies, from which evidence linking biomechanical alterations to functional improvement was weak. Nevertheless, the studies in this review showcased the safety and efficacy of MSC-EV therapy for tendon/ligament healing, by attenuating the initial inflammatory response and accelerating tendon matrix regeneration, providing a basis for potential clinical use in tendon/ligament repair.

Affordance Based Assessment of Ligament Healing in the Knee Joint

There is increasing awareness of the need to include patient-reported outcome (PRO) instruments in the evaluation of ligament healing in the knee Joint. Surgical design in personalized medicine is often based on native anatomy, which may not accurately reflect the sensory function of the joint structure, including native musculoskeletal tissues and biomechanical artifacts. To overcome this problem, researchers have developed alternative approaches based on affordance-based assessment. Estimating the instantaneous knee screw (IKS) axis is crucial to implanting a prosthesis and accessing joint kinematics. The correct estimation of the patient-specific joint axis of the knee is essential for achieving a reliable assessment of musculoskeletal kinematics and dynamics. We found that active touch and posture refer to what is ordinarily called touching-variations in skin stimulation caused by surfaces are altered together by motor activity variations. This affordance of “walk-on-able” is worth noting because it is often neglected that locomotion and its surfaces form an inseparable pair. The assessment process can be viewed in terms of action possibilities provided by the active sets of organs residing that can obtain and utilize information about the tissue environments in which the grafts are to be located.

Should the Diastatic Syndesmosis be Stabilized in Advanced Pronation-External Rotation Ankle Injuries? A Retrospective Cohort Comparison

Background: Ankle injuries with the advanced pronation-external rotation (PE) type are relatively uncommon and the debate about whether the diastatic syndesmosis should be stabilized concomitantly has yet achieved a consensus. Comparison of using (Group 1) or non-using (Group 2) screw stabilization for the diastatic syndesmosis was performed retrospectively. Methods: With the 10-year period, 81 consecutive adult patients with advanced PE ankle injuries (stage 3 or 4 PE type) were treated. After malleolar fractures were internally stabilized with screws and plates, the syndesmotic stability was re-checked by external rotation and hook tests. The necessity of insertion of cortical screws to stabilize diastatic syndesmosis was decided by the individual orthopedic surgeon. The outcomes of both approaches were compared. Results: Seventy-one patients were followed for at least one year (87.7%; average, 2 years; range, 1-11 years). Group 1 had 22 patients and Group 2, 49 patients. The union rate in Group 1 was 100% (22 / 22) and in Group 2, 91.8% (45 / 49; p= 0.30). Syndesmosis re-diastasis occurred in 13.6% (3 / 22) of Group 1 and 30.6% (15 / 49) of Group 2 (p= 0.13). Satisfactory ankle function was noted in 86.4% (19 / 22) of Group 1 and 65.3% (32 / 49) of Group 2 (p= 0.07). Conclusion: Although clinical comparison cannot demonstrate statistical difference, screw stabilization of the diastatic syndesmosis may guarantee safer results. The statistical insignificance may be due to insufficient sample sizes. Clinically and theoretically, insertion of syndesmotic screws to promote ligament healing may be reasonable.