Patellar Tendon Injury Research Articles

Self-assembling peptide hydrogel scaffold accelerates healing of patellar tendon injury: A histological and biomechanical study.

Although KI24RGDS peptide hydrogel that acts as a cell adhesion has been reported to repair tissue in meniscus injury, its effect on tendon injuries remains unknown. The purpose of this study was to clarify the effect of KI24RGDS for tendon repair based on histological and biomechanical evaluation. After introducing defects (length: 10mm; width: 3mm) at the centers of rabbits' patellar tendons, and the KI24RGDS group was implanted with KI24RGDS and observed for 8 weeks. KI24RGDS implantation resulted in limited tendon elongation and better histological scores with uniformed collagen fiber orientation and early vascularization. The failure load of the patellar tendon was higher in the KI24RGDS group than that in the defect group (p < 0.05) and no significant difference with the control group (intact patellar tendon) at 8weeks postoperatively. In conclusion, KI24RGDS administration might have therapeutic potential for tendon injuries by accelerating collagen remodeling.

Patellar Tendon Ruptures after Total Knee Arthroplasty.

Patellar tendon (PT) rupture following total knee arthroplasty (TKA) is a rare, but devastating complication. These injuries occur most frequently in the acute period following TKA due to trauma to the knee. PT ruptures that disrupt the extensor mechanism create a marked functional deficit, impacting every facet of daily life. In complete ruptures of the PT, repair or reconstruction is typically indicated; however, complication rates following intervention remain high. Operative intervention remains the mainstay of treatment, with only certain specific situations where nonoperative intervention is appropriate. Operative techniques are chosen based on the acuity, location of disruption, and status of the residual soft tissues. Treatment options include repair with or without augmentation or reconstruction. Augmentation does reduce the high risk of complications, bringing rates down from 63 to 25%. Augmentation options include autografts, allografts, synthetic grafts, or synthetic meshes. Despite advancements, outcomes are unpredictable and complications are common, highlighting the need for further research to improve treatment protocols. This article provides an overview of PT ruptures following TKA, the various treatment options, and the recommendations of the M.M., R.D., G.S. for each common type of PT injury encountered.

Patellar Tendon Reconstruction Using Quadriceps, Semitendinosus, and Gracilis Autografts With Ultra-high Molecular Weight Polyethylene Tape Augmentation: A Novel Technique

Background: Chronic patellar tendon ruptures are challenging injuries to treat and can be debilitating to patients. Optimal treatment of these extensor mechanism injuries occurs in the acute postinjury period. When these injuries become chronic, they are increasingly difficult to treat effectively. Purpose: We present a case of chronic patellar tendon rupture in a young athletic male who was treated with quadriceps, semitendinosus, and gracilis autograft. To our knowledge, there have been no other reports of using a quadriceps autograft with a bone plug to reconstruct a chronic patellar tendon injury. Patients and Methods: A healthy male under the age of 18 presented in a delayed manner to our clinic with complaints of left knee pain and inability to straighten the knee. His imaging and clinical exam found that he had a patellar tendon rupture, ∼15-degree extensor lag, flexion to 140 degrees, and was unable to straight leg raise or perform any active extension of the knee. He had significant atrophy of his vastus musculature at the knee. The rupture was treated with quadriceps, semitendinosus, and gracilis autograft. Results: At 6 months follow-up, our patient had achieved full extension, flexion to 135 degrees, and 4 of 5 quadriceps strength. He returned to routine physical activity and was satisfied with his results to date. At 1 year’s follow-up, the patient had full extension and flexion to 140 degrees and had resumed playing recreational soccer. Conclusion: Treating chronic patellar tendon rupture with quadriceps, semitendinosus, and gracilis autograft resulted in a positive outcome for this difficult-to-treat injury.

Sagittal Fragment Rotation and Ogden Type-I Classification Are Hallmarks of Combined Tibial Tubercle Fracture and Patellar Tendon Injury.

Tibial tubercle fractures (TTFs) are uncommon injuries, comprising <3% of all proximal tibial fractures. These fractures occasionally occur in conjunction with a patellar tendon injury (PTI). We aimed to identify risk factors associated with combined TTF and PTI. A retrospective review was performed of patients presenting to a single, tertiary children's hospital with TTF between 2012 and 2023. Demographic data, operative details, radiographs, and injury patterns were analyzed. Radiographs were assessed for the epiphyseal union stage (EUS), Ogden classification, and fracture patterns. Multiple logistic regression models were used to assess the impact of body mass index, comminution, fracture fragment rotation, EUS, bilateral injury, and Ogden classification on injury type. We identified 262 fractures in 252 patients (mean age, 13.9 ± 1.31 years). Of the patients, 6% were female and 48% were Black. Of the 262 fractures, 228 (87%) were isolated TTFs and 34 (13%) were TTFs with PTI. Multivariable analysis demonstrated fragment rotation on lateral radiographs (p < 0.0001) and Ogden Type-I classification (p < 0.0001) to be the most predictive risk factors for a combined injury. Rotation was associated with a substantial increase in the odds of a combined injury, with an odds ratio of 22.1 (95% confidence interval [CI], 6.1 to 80.1). Ogden Type-I fracture was another significant risk factor, with an odds ratio of 10.2 (95% CI, 3.4 to 30.4). The Ogden classification and fragment rotation are the most useful features for distinguishing between isolated TTF and combined TTF with PTI. This is the first study to identify risk factors for TTF combined with PTI. Surgeons may use this information to aid in preoperative planning. Diagnostic Level III. See Instructions for Authors for a complete description of levels of evidence.

What is the Utilization and Impact of Advanced Imaging for Tibial Tubercle Fractures? An Analysis of 598 Patients From the Tibial Tubercle Study (TITUS) Group.

Given the rare nature of tibial tubercle fractures, previous studies are mostly limited to small, single-center series. This results in practice variation. Previous research has shown poor surgeon agreement on utilization of advanced imaging, but improved evidence-based indications may help balance clinical utility with resource utilization. The purpose of this study is to quantify diagnostic practices for tibial tubercle fractures in a large, multicenter cohort, with attention to the usage and impact of advanced imaging. This is a retrospective series of pediatric tibial tubercle fractures from 7 centers between 2007 and 2022. Exclusion criteria were age above 18 years, missing demographic and pretreatment data, closed proximal tibial physis and tubercle apophysis, or a proximal tibia fracture not involving the tubercle. Demographic and injury data were collected. Fracture classifications were derived from radiographic evaluation. The utilization of advanced imaging was recorded as well as the presence of findings not identified on radiographs. Standard descriptive statistics were reported, and χ2 tests were performed (means reported±SD). A total of 598 patients satisfied the inclusion criteria, of which 88.6% (530/598) were male with a mean age of 13.8±1.9 years. Internal oblique x-rays were obtained in 267 patients (44.6%), computed tomography (CT) in 158 (26.4%), and magnetic resonance imaging (MRI) in 64 (10.7%). There were significant differences in the frequency at which CT (7.2% to 79.4%, P<0.001) and MRI were obtained (1.5% to 54.8%, P<0.001). CT was obtained most frequently for Ogden type IV fractures (50/99, 50.5%), and resulted in novel findings that were not visualized on radiographs in a total of 37/158 patients (23.4%). The most common finding on CT was intra-articular fracture extension (25/37). MRI was obtained most frequently for Ogden type V fractures (13/35, 37.1%), and resulted in novel findings in a total of 31/64 patients (48.4%). The most common finding was patellar tendon injury (11/64), but only 3 of these patients required tendon repair. Substantial variation exists in the diagnostic evaluation of tibial tubercle fractures. CT was most helpful in clarifying intra-articular involvement, while MRI can identify patellar tendon injury, periosteal sleeve avulsion, or a nondisplaced fracture. This study quantifies variation in diagnostic practices for tibial tubercle fractures, highlighting the need for evidence-based indications for advanced imaging. Level III.

Decorin and/or biglycan knockdown in aged mouse patellar tendon impacts fibril morphology, scar area, and mechanical properties.

Small leucine-rich proteoglycans, such as decorin and biglycan, play pivotal roles in collagen fibrillogenesis during development, healing, and aging in tendon. Previous work has shown that the absence of decorin and biglycan affects fibril shape and mechanical properties during tendon healing. However, the roles of decorin and biglycan in the healing process of aged tendons are unclear. Therefore the objective of this study was to evaluate the differential roles of decorin and biglycan during healing of patellar tendon injury in aged mice. Aged (300 days old) female Dcn+/+/Bgn+/+ control (WT, n = 52), Dcnflox/flox (I-Dcn-/-, n = 36), Bgnflox/flox (I-Bgn-/-, n = 36), and compound Dcnflox/flox/Bgnflox/flox (I-Dcn-/-/Bgn-/-, n = 36) mice with a tamoxifen-inducible Cre were utilized. Targeted gene expression, collagen fibril diameter distributions, mechanical properties, and histological assays were employed to assess the effects of knockdown of decorin and/or biglycan at the time of injury. Knockdown resulted in alterations in fibril diameter distribution and scar area, but surprisingly did not lead to many differences in mechanical properties. Biglycan played a larger role in early healing stages, while decorin is more significant in later stages, particularly in scar remodeling. This study highlights some of the differential roles of biglycan and decorin in the regulation of fibril structure and scar area, as well as influencing gene expression during healing in aged mice.

Surgical approach on combined chronic patellar tendon and bicruciate knee ligament injury

A combined injury of the patellar tendon and both the anterior and posterior cruciate ligaments is disabling. It directly affects knee kinematics and biomechanics, presenting a considerable surgical challenge. In this complex and uncommon injury, decision-making should take into account the surgeon’s experience and consider one- or two-stage surgery, tendon graft, graft fixation, and rehabilitation protocol. This manuscript discusses the surgical approach based on a comprehensive understanding of the patellar tendon and bicruciate biomechanics to guide which structures should be reconstructed first, especially when a two-stage procedure is chosen.

Establishment of a Mouse Degenerative Model of Patellar Tendinopathy with Upregulation of Inflammation.

There is no mouse model of patellar tendinopathy. This study aimed to establish a mouse inflammatory and degenerative patellar tendon injury model, which will facilitate research on patellar tendinopathy using advanced molecular tools including transgenic models. Collagenase at different doses (low dose (LD), medium dose (MD), high dose (HD)) or saline was injected over the mouse patellar tendon. At weeks 1, 2, 4, and 8 post-injection, the tendons were harvested for histology and further examined by micro-computed tomography (microCT) imaging at week 8. The optimal dose group and the saline group were further evaluated by immunohistochemical staining, gait pattern, and biomechanical properties. The histopathological score increased dose-dependently post-collagenase injection. Ectopic mineralization was observed and increased with collagenase dose. The LD group was selected for further analysis. The expression of IL-10, TNF-α, and MMP-1 significantly increased post-injection. The changes of limb idleness index (ΔLII) compared to preinjury state were significantly higher, while the ultimate load, stiffness, ultimate stress, and maximum Young's modulus were significantly lower in the LD group compared to the saline group. A mouse inflammatory degenerative model of patellar tendon injury resembling tendinopathy was established as indicated by the dose-dependent increase in tendon histopathology, ectopic calcification, decrease in biomechanical properties, and pain-associated gait changes.

A Narrative Review Current Physical Therapy Management for Patellar Tendinopathy

Patellar tendinopathy, or jumper’s knee, is a common chronic musculoskeletal disease in the tendon that occurs in lower-extremities injuries. It is common in athletes, particularly sports that integrate frequent jumping and landing, such as volleyball (45%), basketball (32%), and distance running (14%), Patellar tendinopathy is usually difficult for such athletes to manage during the active sports season. This review article is recommended for physical therapists for the conservative treatment in competition season and post-operative rehabilitation of patellar tendon injuries. This review article discusses a new intervention for physiotherapy treatment for Patellar tendinopathy that can support a significant improvement in performance in sport and functional daily activity. The ultimate aim is to develop a clinical practice recommendation for physical therapists for the conservative treatment and post-operative rehabilitation of patellar tendon injuries. This review article found that physical therapy is popularly used to treat Patellar tendinopathy and effective interventions consist of exercise, extracorporeal shockwave therapy, high-energy laser therapy, elastic therapeutic taping, and education for prevention of issues. The post-operative rehabilitation protocol for patella tendon injuries aims to decrease pain, improve the range of motion, and ensure early ambulation and a quick return to sport, though in a time period that is decided on a case-by-case basis depending on the person and the sport. Post-operative rehabilitation is highly important for ensuring a safe return to sport and good quality of life.

The alteration of the structure and macroscopic mechanical response of porcine patellar tendon by elastase digestion.

Background: The treatment of patellar tendon injury has always been an unsolved problem, and mechanical characterization is very important for its repair and reconstruction. Elastin is a contributor to mechanics, but it is not clear how it affects the elasticity, viscoelastic properties, and structure of patellar tendon. Methods: The patellar tendons from six fresh adult experimental pigs were used in this study and they were made into 77 samples. The patellar tendon was specifically degraded by elastase, and the regional mechanical response and structural changes were investigated by: (1) Based on the previous study of elastase treatment conditions, the biochemical quantification of collagen, glycosaminoglycan and total protein was carried out; (2) The patellar tendon was divided into the proximal, central, and distal regions, and then the axial tensile test and stress relaxation test were performed before and after phosphate-buffered saline (PBS) or elastase treatment; (3) The dynamic constitutive model was established by the obtained mechanical data; (4) The structural relationship between elastin and collagen fibers was analyzed by two-photon microscopy and histology. Results: There was no statistical difference in mechanics between patellar tendon regions. Compared with those before elastase treatment, the low tensile modulus decreased by 75%-80%, the high tensile modulus decreased by 38%-47%, and the transition strain was prolonged after treatment. For viscoelastic behavior, the stress relaxation increased, the initial slope increased by 55%, the saturation slope increased by 44%, and the transition time increased by 25% after enzyme treatment. Elastin degradation made the collagen fibers of patellar tendon become disordered and looser, and the fiber wavelength increased significantly. Conclusion: The results of this study show that elastin plays an important role in the mechanical properties and fiber structure stability of patellar tendon, which supplements the structure-function relationship information of patellar tendon. The established constitutive model is of great significance to the prediction, repair and replacement of patellar tendon injury. In addition, human patellar tendon has a higher elastin content, so the results of this study can provide supporting information on the natural properties of tendon elastin degradation and guide the development of artificial patellar tendon biomaterials.

A Novel Patellar Tendon Reconstruction Technique Using Semitendinosus Allograft

A Novel Patellar Tendon Reconstruction Technique Using Semitendinosus Allograft

Advanced MRI Approaches for Evaluating Common Lower Extremity Injuries in Basketball Players: Current and Emerging Techniques.

Magnetic resonance imaging (MRI) can provide accurate and non-invasive diagnoses of lower extremity injuries in athletes. Sport-related injuries commonly occur in and around the knee and can affect the articular cartilage, patellar tendon, hamstring muscles, and bone. Sports medicine physicians utilize MRI to evaluate and diagnose injury, track recovery, estimate return to sport timelines, and assess the risk of recurrent injury. This article reviews the current literature and describes novel developments of quantitative MRI tools that can further advance our understanding of sports injury diagnosis, prevention, and treatment while minimizing injury risk and rehabilitation time. Innovative approaches for enhancing the early diagnosis and treatment of musculoskeletal injuries in basketball players span a spectrum of techniques. These encompass the utilization of T2, T1ρ, and T2* quantitative MRI, along with dGEMRIC and Na-MRI to assess articular cartilage injuries, 3D-Ultrashort echo time MRI for patellar tendon injuries, diffusion tensor imaging for acute myotendinous injuries, and sagittal short tau inversion recovery and axial long-axis T1-weighted, and 3D Cube sequences for bone stress imaging. Future studies should further refine and validate these MR-based quantitative techniques while exploring the lifelong cumulative impact of basketball on players' knees. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY: Stage 2.

Patellar Tendon Load Progression during Rehabilitation Exercises: Implications for the Treatment of Patellar Tendon Injuries.

This study aimed to evaluate patellar tendon loading profiles (loading index, based on loading peak, loading impulse, and loading rate) of rehabilitation exercises to develop clinical guidelines to incrementally increase the rate and magnitude of patellar tendon loading during rehabilitation. Twenty healthy adults (10 females/10 males, 25.9 ± 5.7 yr) performed 35 rehabilitation exercises, including different variations of squats, lunge, jumps, hops, landings, running, and sports specific tasks. Kinematic and kinetic data were collected, and a patellar tendon loading index was determined for each exercise using a weighted sum of loading peak, loading rate, and cumulative loading impulse. Then the exercises were ranked, according to the loading index, into tier 1 (loading index ≤0.33), tier 2 (0.33 < loading index <0.66), and tier 3 (loading index ≥0.66). The single-leg decline squat showed the highest loading index (0.747). Other tier 3 exercises included single-leg forward hop (0.666), single-leg countermovement jump (0.711), and running cut (0.725). The Spanish squat was categorized as a tier 2 exercise (0.563), as was running (0.612), double-leg countermovement jump (0.610), single-leg drop vertical jump (0.599), single-leg full squat (0.580), double-leg drop vertical jump (0.563), lunge (0.471), double-leg full squat (0.428), single-leg 60° squat (0.411), and Bulgarian squat (0.406). Tier 1 exercises included 20 cm step up (0.187), 20 cm step down (0.288), 30 cm step up (0.321), and double-leg 60° squat (0.224). Three patellar tendon loading tiers were established based on a combination of loading peak, loading impulse, and loading rate. Clinicians may use these loading tiers as a guide to progressively increase patellar tendon loading during the rehabilitation of patients with patellar tendon disorders and after anterior cruciate ligament reconstruction using the bone-patellar tendon-bone graft.

Musculoskeletal Ultrasound: An Essential Tool in Diagnosing Patellar Tendon Injuries.

Musculoskeletal (MSK) ultrasound has emerged as a vital tool in diagnosing patellar tendon injuries. Traditional imaging techniques, such as X-rays and Magnetic Resonance Imaging, have certain limitations in assessing soft tissue structures or may not be easily accessible. MSK ultrasound, with its high-resolution, real-time imaging capabilities, offers a cost-effective, safe, and patient-friendly alternative. It allows for accurate visualization of the patellar tendon's structure and function, thereby facilitating the identification of pathological changes such as thickening, thinning, or disruption which aids in diagnosing conditions such as tendonitis, partial tears, and ruptures. Furthermore, MSK ultrasound serves as an invaluable tool for guiding interventions like injections, as it provides real-time imaging. This article explores the role and benefits of MSK ultrasound in diagnosing patellar tendon injuries, highlighting its cost-effectiveness, accessibility, real-time assessment capabilities, and reduced patient burden compared to other imaging modalities. Despite its numerous benefits, the need for ongoing research to enhance its utility is highlighted. As technology advances, MSK ultrasound is set to revolutionize the early detection and management of patellar tendon injuries.

Bibliometric Analysis of the Top 50 Most Influential Studies on Patellar Tendon Injury

Background: There is a wide range of literature on patellar tendon injury, making it increasingly difficult to stay informed on the most influential studies in this field. It is essential to be familiar with the foundational articles of patellar tendon injury research to understand the current state of the literature and deliver high quality care. Purpose: To objectively identify the 50 most influential articles relating to patellar tendon injury and conduct a bibliometric analysis to identify key features of these articles. Study Design: Cross-sectional study. Methods: The Clarivate Analytics Web of Knowledge database was utilized to gather metrics on the 50 most cited articles on patellar tendon injury on June 27, 2022. The information extracted from each article included publication year, number of citations, author information, article type, level of evidence, country of origin, journal name, study focus, and industry influence. Results: The top 50 studies were cited a total of 8543 times and published between 1977 and 2015. The majority of articles were published after 2003, and the majority of citations were accrued after 2011. The most prevalent article types were cohort studies (n = 23), and the majority of studies were of evidence level 2 (n = 14) or 4 (n = 13). Australia and the United States (US) each published the most studies (n = 11). Only 4 (8%) studies focused on patellar tendon rupture, and 12 (24%) of the top 50 studies were associated with industry. Conclusion: The majority of the top 50 most influential articles in patellar tendon injury were published and accumulated citations in the past 10 to 20 years. Non-US countries, institutions, and journals published many of the top 50 studies, reflecting a global interest and commitment to research in this field. Patellar tendon rupture and surgical repair represents a minority of research in the top 50 studies and could be a point of growth in the future.

AGES effect on the biomechanics of the knee tendon

Aging and diabetes, and some other diseases that are associated with a remarkable growth of non-enzymatical cross-links (advanced glycation end-products AGEs) were considered important contributors to increasing patellar tendon injury susceptibility and low healing capacity. While a clear coupling between this collagen structural alteration (AGEs) and tendon mechanics still needs further investigation. In this study, a multiscale fibril-reinforced hyper-elastoplastic model was employed to elucidate the effect of the AGEs density alteration on the aggregate mechanics of the tendons' behavior. Our results showed a clear decrease in tendon stiffness at the pre-yielding stage associated with a higher stress concentration in the normal case. In contrast, a higher tendon stiffness and more brutal reaction were computed after the normal post-yield stage with unbalanced growth of the AGEs. This prediction has potentially important implications for understanding the tissue damage mechanism associated with collagen microstructural alteration.

Patellar tendon mid-substance tear after total knee arthroplasty: a case report

Extensor mechanism of knee plays important role in successful long term functional outcome after total knee arthroplasty (TKA). Any injury to extensor mechanism during or after surgery can cause functional disability which can be devastating for patients. Patellar tendon injuries are not very common after TKA. The author reported a rare case of patellar tendon mid-substance tear after TKA, which was successfully managed by reconstruction using grafts without any implant.

The impact of mild hypercholesterolemia on injury repair in the rat patellar tendon.

Hypercholesterolemia is associated with tendon pathology and injury prevalence. Lipids can accumulate in the tendon's extracellular spaces, which may disrupt its hierarchical structure and the tenocytes physicochemical environment. We hypothesized that the tendon's ability to repair after injury would be attenuated with elevated cholesterol levels, leading to inferior mechanical properties. Fifty wild-type (sSD) and 50 apolipoprotein E knock-out rats (ApoE-/ - ) were given a unilateral patellar tendon (PT) injury at 12 weeks old; the uninjured limb served as a control. Animals were euthanized at 3-, 14,- or 42-days postinjury and PT healing was investigated. ApoE-/ - serum cholesterol was double that of SD rats (mean: 2.12 vs. 0.99 mg/mL, p < 0.001) and cholesterol level was related to the expression of several genes after injury; notably rats with higher cholesterol demonstrated a blunted inflammatory response. There was little physical evidence of tendon lipid content or differences in injury repair between groups, therefore we were not surprised that tendon mechanical or material properties did not differ between strains. The young age and the mild phenotype of our ApoE-/ - rats might explain these findings. Hydroxyproline content was positively related to total blood cholesterol, but this result did not translate to observable biomechanical differences, perhaps due to the narrow range of cholesterol levels observed. Tendon inflammatory and healing activity is modulated at the mRNA level even with a mild hypercholesterolemia. These important initial impacts need to be investigated as they may contribute to the known consequences of cholesterol on tendons in humans.

Effects of Macrophage Polarization Induced by Mesoporous Silicon-Based Curcumin-siRNA Nanoparticles on the Proliferation of Tendon Stem Cells

Studies have shown that curcumin (CUR)-siRNA can improve excessive fibrosis in the repair of patellar tendon (PT) injury. First, mesoporous silicon nanoparticles (NPs) (MES-SiN) were prepared by a sol–gel method. The small molecule CUR was adsorbed in the internal pore canal of MES-Sin, and the cationic high molecular polyethyleneimine (PP) was adsorbed on the outer layer, which combined with negatively charged siRNA to form CUR@MES-SiN-PP/siRNA NPs. The preparation of NPs was observed by transmission electron microscopy (TEM). RAW264.7 macrophages were treated with different concentrations of NPs, and cell viability was determined by methyl tetrazolium (MTT) assay. The NPs were prepared by siRNA labeled with the fluorescent dye 6-carboxyfluorescein (FAM) and transfected into cells. The cellular uptake of the NPs was observed by confocal laser scanning microscopy (CLSM) and TEM. A total of 80 SPF SD rats (10 weeks of age) were randomly assigned into two groups to establish a PT injury model. The rats in experimental (Exp) group were injected with CUR@MES-SiN-PP/siRNA NP solution (2 μg/g) in the abdomen for 14 d, and those in control (Ctrl) group were injected with an equal dose of 1% dimethyl sulfoxide (DMSO). The rectus femoris of 24 rats were taken from each group 12 h and 1 d, 3 d, 5 d, 7 d, and 14 d after injury. Masson and hematoxylineosin were used to observe the degree of fibrosis of the PT tissue. The differentiation of macrophages was observed by flow cytometry, and the proliferation of tendon stem cells was observed by immunofluorescence approaches such as Pax7. The results suggested that CUR@MES-SiN-PP/siRNA NPs were successfully fabricated. The NPs showed dose-dependent cytotoxicity, the cell viability remained above 90% at concentrations below 10 μg/mL, and the NPs were ingested by higher cells. After injury, the fibrotic area of Exp group was drastically decreased (P &lt;0.05), and the regenerated muscle fiber area was increased (P &lt;0.05). The number of M2-type macrophages increased markedly 3 d, 5 d, 7 d, and 14 d after injury (P &lt;0.05). Immunofluorescence showed that the proliferation of fluorescent cells 3 d after surgery was superior to that of Ctrl group (P &lt;0.05).

Management of Chronic Patellar Tendon Rupture Left Knee Joint with Primary Repair Using Fiber Wire and Endo Button As A Cost-Effective and Simple Anatomical Reconstruction Without Grafts: A Case Report

Patellar tendon ruptures mostly occur in persons under 40 years of age, typically during sports activities. Neglected ruptures of the patellar tendon, defined as ruptures presenting after six weeks, are often difficult to repair, and different techniques have been described for reconstruction of this uncommon problem including the use of auto-grafts, allografts, and synthetic materials. We hereby describe a cost-effective and simple anatomical reconstruction without the requirement for grafts for chronic patellar tendon injuries. This is a retrospective study of a 29-year-old man who came to the orthopaedic clinic with the chief complaint of pain in the left knee. Pain has been felt since 2 years ago after the patient falls when were playing football. After the incident, the patient was taken to alternative therapy, but still felt the pain and difficulty moving the left knee. From the physical examination, the patient presented elevation of left patella height, localized tenderness, palpable gap below the inferior pole of the patella, and limited range of movement on the left knee. There was also a straight leg raise provocative test positive. The x-ray results were obtained patella alta with Insall-Salvatti Index was 1.6. An MRI examination was also performed, showing patella contusion and marrow edema, suspicious of soft tissue rupture, with intact ACL/PCL. The patient was diagnosed with chronic patellar tendon rupture of the left knee. At the time of surgery, it was found that the patellar tendon ruptured with remnants still on the distal part, and the cartilage was still in good condition. The next step is to perform a primary repair of the patellar tendon using fiber wire and endo button at the tibial part. Postoperative rehabilitation was carried out by starting limited ROM exercise of the left knee on day 4. Six weeks after surgery, there was an improvement in left knee ROM and improvement in walking ability. In this case, primary repair of patellar tendon using fiber wire and endo button provides good results and can be used as a costeffective and simple anatomical reconstruction without the requirement for grafts.