Plastic and elastic biomechanical properties of anterior cruciate ligament autografts.

BACKGROUND: Anterior cruciate ligament (ACL) rupture is a common orthopedic injury, occurring in roughly 68.6 per 100,000 persons annually, with the primary treatment option being ACL reconstruction. However, debate remains about the appropriate graft type for restoring the native biomechanical properties of the knee. Furthermore, plastic graft elongation may promote increased knee laxity and instability without rupture. This study aims to investigate the plastic properties of common ACL-R graft options. METHODS: Patellar tendon (PT), hamstring tendon (HT), and quadriceps tendon (QT) grafts were harvested from 11 cadaveric knees (6 male and 5 female) with a mean age of 71(range 55-81). All grafts were mechanically tested under uniaxial tension until failure to determine each graft's elastic and plastic biomechanical properties. RESULTS: Mechanically, the QT graft was the weakest, exhibiting the lowest failure force and the lowest failure stress (QT < HT, p = 0.032). The PT was the stiffest of the grafts, having a significantly higher stiffness (PT > QT, p = 0.0002) and Young's modulus (PT > QT, p = 0.001; PT > HT, p = 0.041). The HT graft had the highest plastic elongation at 4.01 ± 1.32 mm (HT > PT, p = 0.002). The post-yield behavior of the HT tendon shows increased energy storage capabilities with the highest plastic energy storage (HT > QT, p = 0.012) and the highest toughness (HT > QT, p = 0.032). CONCLUSION: Our study agrees with prior studies indicating that the failure load of all grafts is above the requirements for everyday activities. However, grafts may be susceptible to yielding before failure during daily activities. This may result in the eventual loss of functionality for the neo-ACL, resulting in increased knee laxity and instability.

Editorial Commentary: Waiting at Least 1 Month After an Intra-articular Corticosteroid Injection for Performing a Knee, Shoulder, and Hip Arthroscopy Could Minimize the Risk for Postoperative Infection: Platelet-Rich Plasma Is an Alternative.

An intra-articular corticosteroid is associated with a higher risk of joint infection. Identifying the necessary time interval from the injection to the arthroscopic procedure that does not impose an additional risk of infection is critical for the safety of our patients. Increasing evidence suggests that there is a high risk of infection at the first 4 weeks after the injection, but it seems that this risk declines to normal levels after that period. Interestingly, this time interval of 4 weeks is comparable between knee, shoulder, and hip injection and subsequent arthroscopy. A delay of an arthroscopic intervention at any joint for at least 4 weeks is recommended. Finally, platelet-rich plasma (PRP) is equally effective as corticosteroids in terms of pain management and anti-inflammatory response, with the advantage of promoting healing. PRP may also be associated with a lower risk of postoperative infection in patients undergoing arthroscopy, representing a biologic alternative.

Editorial Commentary: Personalized Anterior Cruciate Ligament Reconstruction and Rehabilitation Mitigate Postoperative Arthrofibrosis: Prevention Is the Best Approach.

Arthrofibrosis after anterior cruciate ligament reconstruction can become a major complication requiring surgical intervention. The reported incidence approximates 8% but varies widely (2%-35%) and, as not all patients require surgery, may be underreported. Several risk factors are involved. Female sex, older age, surgery within the first month after injury, and meniscus repair are consistently associated with increased risk. Other factors include graft size and type, concomitant procedures, use of anticoagulants, and genetic factors. By identifying risk factors, we can modify our surgical technique and rehabilitation to meet each patient's needs with fewer complications.

Editorial Commentary: Patellofemoral Instability Results in Osteoarthritis, and Nonanatomic Surgery and Surgical Over-constraint May Also Cause Osteoarthritis.

When we are looking at the stars, we are in fact looking back in time. This is because it takes years for the light from the stars to reach us. In similar fashion, when we are evaluating data on osteoarthritis after patellofemoral surgery, we need to consider what kind of procedure was performed. Furthermore, it is extremely important to answer the question of whether the patellofemoral instability itself or the surgical procedure is causing the arthritis. Recent evidence suggests that recurrent patellofemoral instability is causing cartilage degeneration and stopping this process via surgical restoration of the anatomy and biomechanics of the patellofemoral joint may significantly reduce the risk of osteoarthritis. Shear loading of the cartilage can be detrimental. An instability event elicits inflammatory markers that are shown to induce arthritis. On the other hand, there is the argument that over-constraint may lead to arthritis owing to an increase in cartilage loading. Another argument is that surgery may not fully restore the patellofemoral anatomy. Appropriate patient selection and continuous evolution of our surgical procedures are key elements toward successful management of patellofemoral instability.

Editorial Commentary: Major Technical Advances in Knee Anterior Cruciate Ligament Reconstruction Address Anatomy, Biomechanics, and Healing.

The surgical techniques in knee anterior cruciate ligament (ACL) reconstruction continue to evolve significantly. Improved understanding of the anatomy, biomechanics, and healing of the ACL has offered the foundation for several advances. The goal of these innovations is to successfully restore the native anatomy and biomechanical function of the native ligament, provide a stable and pain-free knee joint, allow return to prior level of activity, prevent rerupture, and prevent osteoarthritis. Taken in sum, these are lofty goals. The shift toward anatomic ACL reconstruction, development of diverse graft options and configurations, and the addition of reinforcement techniques, such as the anterolateral ligament reconstruction and lateral tenodesis techniques, are major advancements in ACL reconstruction.

Editorial Commentary: Addition of the Sartorius Tendon to Small-Diameter Hamstring Anterior Cruciate Ligament Autografts May Improve Outcomes in Pediatric and Revision Cases.

Graft selection in anterior cruciate ligament reconstruction can have a pivotal role in a successful outcome. One of the major concerns with hamstring autograft is the variability of the diameter of each tendon, and grafts with a diameter of less than 8 mm may result in an increased failure rate. The addition of the sartorius tendon as a fifth strand in small-diameter hamstring autografts increases graft strength and diameter. This may improve outcomes in pediatric and revision cases.

Editorial Commentary: Biologic Augmentation of Meniscus Repair Is Complex.

In the setting of biological augmentation for meniscus repair, it is extremely important to evaluate all aspects, including effectiveness, costs, potential risks, benefits, and limitations. It seems that everything matters in healing: the aspirate source of the bioactive agents, cell content, presence of stem cells and their type, growth factors, cytokines, biomechanical scaffold, and the quality of the tissue. There are several differences among mesenchymal, adipose, and peripheral blood stem cells, with the cell origin affecting the differentiation potential towards bone, cartilage and ligament. Moreover, different aspirate sources and fibrin clots have different content in cells, growth factors, and cytokines. In this equation, it is not as simple as the more the better. Different doses of growth factors may have different effects in the different cell types. And as this was not complicated enough, synergistic phenomena between cells and between growth factors can play a huge role. Add to that the role of the biomechanical environment, the proper timing of the healing phases and the inherent patient characteristics. There is very, very much to learn, and finally, we acknowledge that not all menisci repairs can always heal.

Editorial Commentary: Artificial Intelligence in Sports Medicine Diagnosis Needs to Improve.

From imaging interpretation and health monitoring to drug development, the role of artificial intelligence (AI) in medicine has increased. But AI is not ready to replace humans when it comes to the diagnosis of sports medicine conditions. Rather, in highly specialized fields such as sports medicine, when it comes to interpretation of diagnostic studies such as magnetic resonance imaging scans (that are more sophisticated than simple radiographs), experts outperform AI systems at present. Key features of clinical practice, such as the physical examination, in-person consultation, and ultimately, decision making, cannot be easily replaced. As every novel "smart" tool is incorporated into our lives, we need to be ready to embrace its use, but we also ought to be critical of its implementation and seek transparency at every step of the process. We cannot afford to see AI as an antagonistic element in our practices but rather as a valuable assistant that could someday improve diagnostic accuracy.

Editorial Commentary: Meta-analysis Shows That Platelet-Rich Plasma Is Safe and Effective for Knee Osteoarthritis: Future Randomized Controlled Trials Must Be of High Quality-Not High Quantity.

The use of platelet-rich plasma in knee osteoarthritis is still controversial, and meta-analysis shows that platelet-rich plasma can be effective and safe for nonoperative management of knee osteoarthritis. Randomized controlled trials (RCTs) are essential tools for evaluating the effectiveness and safety of new therapeutic interventions. Meta-analysis of these RCTs is critical to try to approximate the truth but also reminds us that sometimes, "value does not necessarily derive from quantity but rather from quality." Given the fact that approximately 92.8% of published abstracts of RCTs report at least 1 significant outcome (indicated as at least P < .05), there is a notion that significant outcomes are most likely to become published, suggesting a potential publication bias. Therefore, additional studies repeating the significant outcomes are sometimes necessary.

Editorial Commentary: The Posterior Cruciate Ligament Posteromedial Bundle Is Small but Vital to Posterior Cruciate Ligament Biomechanics: Don't Ignore the Underdog.

Posterior cruciate ligament (PCL) reconstruction leads to outcomes less favorable than those of anterior cruciate ligament reconstruction. In recent years, we have seen a surge of publications regarding PCL anatomy, isometry, and reconstruction techniques. PCL reconstruction has been revolutionized with lessons learned from analysis of PCL behavior, such as the distinct role of the posteromedial bundle (PMB) in the biomechanics of the knee at different flexion angles, as well as its co-dominant role with its counterpart, the anterolateral bundle. With the knee in extension, the PMB serves to restrict posterior translation, whereas in knee flexion, the PMB restricts internal rotation. It is rather too early to know whether the biomechanical advantage of double-bundle reconstruction will result in better clinical outcomes in the long term; however, the increased interest and the refinement of both single- and double-bundle reconstruction techniques will certainly advance our knowledge, ultimately translating into better patient outcomes.

Editorial Commentary: Tissue Engineering of the Meniscus: Are We at the Point That if Something Looks Like a Meniscus, We Can Call It a Meniscus?

It was thought that the meniscus together with articular cartilage would be among the first tissues to successfully engineer. However, despite extensive research in the field, this path was proven not to be easy. Tissue engineering of musculoskeletal tissues remains promising, and several advancements have further identified the role of biological treatments in meniscus repair and regeneration. To move forward, and advance from being promising to being forthcoming, an important step would be to improve the quality of presented studies. This editorial commentary proposes a checklist of necessary reported data for tissue engineering studies: macroscopic and histologic appearance, tissue composition, mechanical properties, and translational data.

Editorial Commentary: Exosomes-A New Word in the Orthopaedic Vocabulary?

As our vocabulary grows to include exotic terms promising treatment options for osteoarthritis and cartilage treatment, our adherence to the scientific method and quest for unbiased data remain critical. Only by following this path will biologics like exosomes remain more than theoretical comets of hope. Exosomes are extracellular vesicles that are released from all body cells. In orthopaedics, exosomes may be part of cell-to-cell communication systems mediating osteoarthritis, fracture healing, and cartilage repair. Recent research has combined mesenchymal stem cell exosomes and hyaluronic acid in a rabbit cartilage repair model. Currently, there are limitations in the translation of these methods into human trials.

Facet Joints of the Spine: Structure-Function Relationships, Problems and Treatments, and the Potential for Regeneration.

The zygapophysial joint, a diarthrodial joint commonly referred to as the facet joint, plays a pivotal role in back pain, a condition that has been a leading cause of global disability since 1990. Along with the intervertebral disc, the facet joint supports spinal motion and aids in spinal stability. Highly susceptible to early development of osteoarthritis, the facet is responsible for a significant amount of pain in the low-back, mid-back, and neck regions. Current noninvasive treatments cannot offer long-term pain relief, while invasive treatments can relieve pain but fail to preserve joint functionality. This review presents an overview of the facet in terms of its anatomy, functional properties, problems, and current management strategies. Furthermore, this review introduces the potential for regeneration of the facet and particular engineering strategies that could be employed as a long-term treatment.

Editorial Commentary: Now Is the Time to Discover How and Why Platelet-Rich Plasma Works in Cartilage.

From the initial overenthusiasm for platelet-rich plasma (PRP) that considered it a panacea for all orthopaedic conditions to the other extreme that heavily criticized it as having a placebo effect, we are now entering a period in which significant evidence suggests that application of PRP provides clinical benefit for various indications. And although high-quality studies exist to show clinical improvement for cartilage pathologic conditions, there is not sufficient support from basic science research to explain PRP's mechanism of action or adequate characterization of its properties and behavior.

Editorial Commentary: Could Biological Treatments Be the Game-Changing Factor for Osteoarthritis?

The realization of the presence of an inflammatory component in cartilage degeneration together with the promising application of platelet-rich plasma and amnion as "healing agents" opened a new window of opportunity for biological treatments in osteoarthritis. If the goal is to delay or even cease the degenerative process, then treating the cause rather than the symptom is a key factor for this biological intervention to be successful. As new biological agents arise, there are 3 crucial milestones that need to be met in laboratory and clinical studies: safety, reasonable cost, and improved effectiveness in comparison with alternatives.

Methods to Improve Arthroscopic and Orthopaedic Biomechanical Investigations: A Few of Our Favorite Things.

Controlled biomechanical studies, generally in vitro (and often ex vivo), may represent a first step in evaluation of a new arthroscopic or orthopedic implant or technique. The purpose and methods of biomechanical studies must be thoughtfully considered to achieve results translatable to a clinically relevant conclusion. A limitation is that with the exception of animal studies or rare human investigations, most biomechanical studies actually only investigate mechanics and do not study biological healing. We review tips and pearls for performing quality biomechanical investigations.

Combined Reconstruction of the Medial Patellofemoral Ligament (MPFL) and Medial Quadriceps Tendon-Femoral Ligament (MQTFL) for Patellar Instability in Children and Adolescents: Surgical Technique and Outcomes.

OBJECTIVES: A variety of surgical options exist to treat the challenging problem of recurrent patellar instability in children and adolescents. The goal of the current study is to describe a novel combined reconstruction technique of both the medial patellofemoral ligament (MPFL) and the medial quadriceps tendon-femoral ligament (MQTFL) and report patient outcomes of a single-surgeon series. METHODS: All patients studied underwent simultaneous MPFL and MQTFL reconstruction for patellar instability using gracilis allograft. Demographic, clinical, and radiographic data were collected. Subjective outcomes were assessed for a minimum of 1 year postoperatively. RESULTS: Twenty-five patients (27 knees), including 15 female and 10 male individuals with an average age of 15.0±2.2 years (range, 10.3 to 18.9), were included. Prior ipsilateral patellofemoral surgery had been performed in 6 of 25 (24%) patients. Simultaneous hemiepiphysiodesis for valgus deformity at the time of combined reconstruction was performed in 5 of 25 (20%) patients. Preoperative imaging showed a mean tibial tubercle-trochlear groove of 17.2±3.8, Caton-Deschamps Index (CDI) of 1.13±0.16, and trochlear dysplasia Dejour A/B [22/26 (85%)] or Dejour C/D [4/26 (15%)]. A total of 18 patients (19 knees, 72%) returned outcomes questionnaires at a mean 2.0±0.5 years after surgery. Mean Kujala, Pedi-IKDC, and Lysholm scores were 85.9±13.9, 81.5±15.2, and 84.3±13.5, respectively. Later revision procedure (tibial tubercle osteotomy) for recurrent patellar instability was required in 2 of 25 patients (8%) patients, and another patient reported persistent instability not requiring revision. Return to sports was possible in 10 of 13 self-reported athletes (77%) at a mean of 5.8±3.9 months (range, 2 to 15). CONCLUSIONS: The present study describes a combined MPFL-MQTFL reconstruction technique with favorable short-term results. Although particularly useful in the skeletally immature patient where tibial tubercle osteotomy should be avoided and patellar fixation minimized, combined reconstruction may potentially be appropriate for older patients with patellofemoral instability as well. This technique more closely recreates the native anatomy of both the MPFL and MQTFL, may decrease the risk of patellar fracture, and can be useful in the revision setting. LEVEL OF EVIDENCE: Level IV.

Editorial Commentary: Could Time From Injury to Surgery Affect Decision Making for Posterior Cruciate Ligament Reconstruction?

How long should a trial of conservative treatment of posterior cruciate ligament injuries continue before surgical intervention? A recent study demonstrates that time from injury to surgery could be negatively correlated with graft maturation and remnant preservation. Considering the improvements in arthroscopic posterior cruciate ligament reconstruction outcomes, early intervention could be considered in high functional demand patients with high grades of instability. Yet it remains to be seen whether graft maturation and remnant preservation result in improved clinical outcomes regardless of the time to surgical intervention.

Editorial Commentary: Not All Bone Marrow Aspirate Concentrates Are the Same: The Necessity of Detailed Reporting and Other Lessons Learned From Cell-based Treatments in Orthopaedics.

Bone marrow aspirate concentrates have become a popular therapeutic approach for several musculoskeletal conditions. A plethora of different preparations exist that make difficult to evaluate their clinical outcome and, thus, to make safe conclusions for their effectiveness. The first step for this assessment is comprehensive and reliable reporting of all the important variables that would allow characterization of their content and properties. This is critical for the understanding of their mechanism of action and the identification of the proper indications based on patient and disorder characteristics that could potentially lead to their effective application in clinical scenarios.

Alternatives to Reverse Total Shoulder Arthroplasty for Management of Massive Rotator Cuff Tears.

Multiple alternatives to reverse total shoulder arthroplasty exist for the management of massive rotator cuff tears. Surgeons should understand the current indications for and outcomes of alternatives to reverse total shoulder arthroplasty for the management of massive rotator cuff tears. Successful rotator cuff repair involves two major challenges: the creation of forceful mechanical integrity of the repair and the creation of a biologic environment that enhances tissue healing. Given the latest advancements in grafts and biologic enhancement, arthroscopic repair appears to be an effective and reasonable alternative for the management of massive rotator cuff tears.