Patellar Tendinopathy Research Articles

Novel interventions for recalcitrant patella tendinopathy: Results may favour autologous blood injection (ABI) over radial-extra-corporeal shockwave therapy (r-ESWT) – A prospective cohort study

BackgroundPatella tendinopathy is a common condition in a number of sports and can have a significant impact on activity and quality of life. Whilst rehabilitation leads to improvements in the majority of cases, a number of adjunct treatments are available for resistant cases with limited evidence supporting the use of one treatment over another.Hypothesis/Purpose: To compare the outcomes for patients with chronic patella tendinopathy, following either radial-Extra-Corporeal Shockwave Therapy (r-ESWT) or Autologous Blood Injection (ABI) Study designProspective cohort study. Methods28 consecutive patients with chronic patella tendinopathy, treated with radial-ESWT (n = 14) or ABI (n = 14), with minimum three-month follow-up. Mean age 34.2 years, mean duration of symptoms 32.8 months. Patients received either three sessions of radial-Extra-Corporeal Shockwave Therapy (one session per week for 3 weeks), or two ultrasound-guided Autologous Blood Injections (2 injections performed 2–4 weeks apart). All patients received standardised after-care, including continuation of a structured home exercise programme of flexibility and progressive loading (eccentric strengthening) exercises. Main Outcome Measures were Victoria Institute of Sport – Patella questionnaire (VISA-P), plus 0–10 Visual Analogue Scale (VAS) for self-reported levels of “average pain”. ResultsThere were statistically significant improvements in self-reported measures of pain/function following either procedure at 6-weeks and at 3-months, but only in the ABI group at 6-months. At 3-months: VISA-P was improved from 32.4% ± 11.7%–60.0% ± 20.7% (p < 0.01) in the ABI group, and from 34.2% ± 14.6%–48.9% ± 17.8% (p < 0.001) in the r-ESWT group. ConclusionsPatients with chronic patella tendinopathy improved at 6-weeks and 3-months following either ABI or r-ESWT procedure, with significant benefits at 6-months seen only in the ABI group. Between group analysis demonstrated improved outcomes favouring ABI compared to r-ESWT at the 6-month timepoint using VISA-P, and at all time-points using VAS as outcome measures. The small sample sizes in this pragmatic study are however noted, which limit interpretation, and larger more robust studies are required to investigate this further. This pragmatic prospective cohort study demonstrates improvements following either r-ESWT or ABI procedures, with results potentially favouring ABI over r-ESWT for patients with chronic patella tendinopathy.

Bracing for the Patellofemoral Joint.

Patellofemoral disorders are common causes of knee pain that result in frequent visitations to musculoskeletal care clinics. Patellar tendinopathy, patellar instability and patellar maltracking, and pain are some of the most common pathologies resulting in patellofemoral dysfunction. For each of these diagnoses, there are unique orthoses and braces available, some of which are uniquely designed to address the pathology involved. While the spectrum of patellofemoral disorders is wide ranging and can often be challenging to treat, bracing frequently plays a large role in the overall treatment algorithm. In this article, we summarized the current literature and treatment recommendations related to the most common types of patellar braces. We performed a thorough review of randomized controlled trials and up to date literature to reach well-informed conclusions on current best practice regarding the uses of patellar braces for patellofemoral disorders.

Relationships between tendon structure and clinical impairments in patients with patellar tendinopathy.

The clinical relevance of altered tendon structure in patellar tendinopathy is contested since structural change persists after symptom resolution. The purpose of this study was to explore the relationships between tendon structure and clinical impairments in patellar tendinopathy. In this retrospective, secondary analysis of individuals with patellar tendinopathy (n = 41), tendon structure (thickness, cross-sectional area [CSA], shear modulus, and viscosity), symptom severity, lower extremity function (counter-movement jump [CMJ] height), and quadriceps muscle performance (knee extension force and central activation ratio [CAR]) were recorded for the symptomatic limb. Relationships among structure, symptom severity, lower extremity function, and quadriceps muscle performance were examined using sequential regression models. Adjusting for age, sex, body mass index, and pain levels, there were significant positive relationships for thickness (p < 0.001, β = 0.718) and viscosity (p = 0.006, β = 0.496) with CMJ height. There were significant negative relationships between CSA with both CMJ height (p = 0.001, β = -0.538) and CAR (p = 0.04, β = -0.517). This is the first study to demonstrate relationships between tendon structure and lower extremity function or quadriceps muscle performance in patients with patellar tendinopathy. Clinical significance: Since structural changes persist after symptom resolution, addressing these changes may assist in restoring lower extremity function and quadriceps muscle performance.

Decreasing patellar tendon stiffness during exercise therapy for patellar tendinopathy is associated with better outcome

ObjectivesTo assess the associations between: 1) baseline patellar tendon stiffness and clinical outcome after exercise therapy in athletes with patellar tendinopathy and 2) the change in patellar tendon stiffness and clinical outcome during progressive tendon-loading exercise therapy and eccentric exercise therapy. DesignRandomized controlled trial. MethodsAthletes with patellar tendinopathy aged 18-35 years, playing tendon-loading sports at least 3 times per week were randomized in a 1:1 ratio between progressive tendon-loading exercise therapy and eccentric exercise therapy for 24 weeks. Patellar tendinopathy was diagnosed clinically, and confirmed by ultrasound. Patellar tendon stiffness (kilopascal, kPa) was assessed using shear-wave elastography. Clinical outcome was assessed using the validated Victorian Institute of Sports Assessment (VISA-P; range 0-100) questionnaire. Both were assessed at baseline, 12 and 24 week follow-up. Adjusted general linear, mixed-linear models and Generalized Estimating Equations were used. ResultsWe included 76 athletes (58 men, mean age 24 ± 4 years). No association was found between baseline stiffness and VISA-P after 24 weeks (p = 0.52). Decreased stiffness (adjusted mean difference = 10 kPa (95% CI: 4-15) was significantly associated with improved clinical outcome at 12 weeks in all athletes (p = 0.02), and at both 12 and 24 weeks (p = 0.01) in athletes allocated to progressive tendon-loading exercise therapy. ConclusionsPatellar tendon stiffness, assessed with shear-wave elastography, is unsuitable to use as a single predictive measurement for clinical outcome. Decreasing stiffness during the course of exercise therapy is associated with improved clinical outcome in athletes recovering from patellar tendinopathy.

Patellar Tendon Force Differs Depending on Jump-Landing Tasks and Estimation Methods

Patellar tendinopathy is a chronic overuse injury of the patellar tendon which is prevalent in jump-landing activities. Sports activities can require jumping not only with a vertical component but also in a forward direction. It is yet unknown how jumping in the forward direction may affect patellar tendon forces. The main purpose of this study was to compare PTF between landings preceded by a vertical jump and a forward jump in volleyball players. The second purpose was to compare two different estimation methods of the patellar tendon force. Fifteen male volleyball players performed vertical and forward jump-landing tasks at a controlled jump height, while kinetics and kinematics were recorded. Patellar tendon forces were calculated through two estimation methods based on inverse dynamic and static optimization procedures, using a musculoskeletal model. Results showed that forward jump-landing generated higher patellar tendon forces compared to vertical jump-landing for both estimation methods. Surprisingly, although the static optimization method considered muscle co-contraction, the inverse kinematic method provided statistically significant higher patellar tendon force values. These findings highlight that limiting the forward velocity component of the aerial phase appears to reduce the load on the patellar tendon during landing and may help to prevent patellar tendinopathy.

Knee dynamics during take-off and landing in spike jumps performed by volleyball players with patellar tendinopathy.

[Purpose] Patellar tendinopathy is a common sports injury. The risk factors for this injury can be categorized as intrinsic, extrinsic, and dynamic. We examined the dynamic factors in this study. [Participants and Methods] The participants were volleyball players who were assigned to a patient group (n=6) if they had medial patellar tendinopathy in the left knee or to a control group (n=7) otherwise. The participants performed spike jumps, and their ground reaction force and three-dimensional kinematic data were recorded. Knee angle and moment data were extracted at the peak extension moment of take-off and landing. [Results] The two groups showed no differences in knee angles. A tendency for abduction/external rotation moments at take-off and landing on both sides was observed in the control group, while the patient group showed adduction and internal rotation moments at take-off and adduction moment at landing in the left (injured) knee. [Conclusion] The observed knee joint moments in the left (injured) knee of the patient group may have been involved in the pathophysiological mechanism underlying the development of patellar tendinopathy.

Effects of β-Hydroxy β-Methylbutyric Supplementation in Combination with Conservative Non-Invasive Treatments in Athletes with Patellar Tendinopathy: A Pilot Study.

The aim of the present study was to analyze the effect of conservative non-invasive treatments based on eccentric training, stretching and extracorporeal shock wave therapy (ESWT) supplemented with β-Hydroxy β-methylbutyric (HMB) or placebo (PLAC) on body composition, pain and muscular function (jump ability, muscular power and muscular strength) in athletes with patellar tendinopathy (PT). In a double-blind randomized trial, 8 athletes (4 males and 4 females) performed a physical rehabilitation for 4 weeks. They were randomly divided into two experimental groups (two males and two females in each one) that ingested HMB (HMBG) or PLAC (PLACG). In pre- and post-intervention were assessed body composition, pain, countermovement jump (CMJ), back-squat (BS) for analyzing peak power (W) (PPPP), load (kg) associated to PPPP (PPKG) and mean velocity (m/s) (PPMV) in addition to a 5-RM leg extension tests. An interaction intervention·supplementation (p = 0.049; Ƞ2p = 0.774) was observed in the height reached in the CMJ as an intervention effect in PPPP detected for the HMBG (p = 0.049). In addition, an enhancement in PPKG (p = 0.028; Ƞ2p = 0.842) was detected in the intervention, but not in PPMV, as an increase in the intervention in the 5-RM test (p = 0.001; Ƞ2p = 0.981) was observed. No changes were noted on body composition or pain (p > 0.05). The combination of eccentric training with stretching and ESWT increased concentric muscular power and strength after 4 weeks without changes in body lean mass or pain. In addition, HMB supplementation could enhance the power muscular performance in athletes with PT, optimizing the intervention adaptions.

Laser Therapy in the Comprehensive Program of Physical Rehabilitation of Athletes with Chronic Patellar Tendinopathy

Aim: Determining the effectiveness of the developed comprehensive physical rehabilitation program for athletes with chronic patellar tendinopathy. Materials and Methods: Participants were randomly divided into the main and control groups consisting of 11 people each. The complex rehabilitation program in the main group combined laser therapy and different types of therapeutic exercises, in the control group the laser therapy was excluded. The effectiveness of the intervention was evaluated by the intensity of pain in the patella (Visual Analog Scale) and the functional ability of the knee (VISA-P scale). Results: At the end of the intervention, a significant reduction in pain was observed in both groups. The average scores on the VAS scale were reduced to 2.0 points in the main group and to 3.5 in the control one. The share of patients, whose pain was eased, was 27.27 per cent in the main group, in the control group such people were not detected. After two months of intervention according to the results of the VISA-P scale in both study groups, there was an improvement in the functional capacity of the knee joint. Thus, the average number of points increased by 30.5 points in the main group, and by 12.0 in the control one. Conclusions: The use of high-frequency laser therapy in a comprehensive program of physical rehabilitation of patients with patellar tendinopathy shows better results for reducing pain and improving the functioning of the knee joint than without it. We believe that high-frequency laser therapy can be used as an important adjunct to various types of therapeutic exercises in the comprehensive rehabilitation of patients with patellar tendinopathy.

Magnetic Resonance Appearance and Clinical Significance of Anterior Suprapatellar Fat Pad in Anterior Knee Pain

Introduction: Anterior knee pain (AKP) is a very common problem in the community and negatively affects the patient’s quality of life. Many pathologies can be the cause of this problem. The principal aim of our study was to evaluate the relationship between the magnetic resonance appearance of the suprapatellar fat pad and AKP. Methods: Knee magnetic resonance imaging of patients with and without AKP was analyzed retrospectively by two independent radiologists in two groups. The morphological structure of the anterior suprapatellar fat pad and other pathologies that may cause AKP in the knee joint were evaluated. Statistical relationships of the findings were investigated. Results: Of the 395 patients who participated in the study, 195 (49.4%) were females and 200 (50.6%) were males. The median age of the patients was 43 (18–90) years. There was no significant difference in mean age between individuals with and without AKP (p=0.376). A significant difference was found between patients with and without AKP in terms of posterior contour bowing of the anterior suprapatellar fat pad, edema, and diameter increase in the fat pad, patellar tendinopathy, quadriceps tendinopathy, and medial patellar retinaculum damage (p<0.001, p<0.001, p<0.001, p=0.015, p=0.002, and p=0.032, respectively). Discussion and Conclusion: Anterior suprapatellar fat pad syndrome is one of the pathologies involved in the etiology of AKP. The close relationship between the posterior contour bowing of the anterior suprapatellar fat pad we defined and AKP should be considered in radiological reporting.

Patellar tendinopathy: diagnosis by ultrasound and magnetic resonance imaging. Conservative and surgical management alternatives

Bajo el término tendinopatía rotuliana se engloban todas las lesiones que afectan el tendón rotuliano, en sus porciones proximal, central y distal. Además, se debe discriminar entre fases agudas (tendinitis), crónicas (tendinosis) o roturas de espesor completo. La tendinopatía rotuliana es una lesión frecuente en aquellos deportistas que realizan actividades de salto o frenadas bruscas. A pesar de que afecta a un amplio número de pacientes (un 14% de la población general y hasta un 40% de los deportistas que realizan actividades de salto), su conocimiento sigue siendo escaso. Una detallada exploración clínica juntamente con una evaluación ecográfica aportará información suficiente para saber qué lesión presenta el paciente. La resonancia magnética (RM) se utilizará para evaluar las posibles lesiones asociadas, sobre todo a nivel intraarticular. El tratamiento debe ser inicialmente conservador y siempre acompañado de reducción de la carga y realización de ejercicios combinados excéntricos e isométricos. Cuando esta fase terapéutica inicial falla, se dispone de terapias mínimamente invasivas ecoguiadas que pueden promover el estado regenerativo. Cuando el tratamiento conservador falla, la cirugía debe ser minuciosa con la finalidad de incidir sobre la parte lesionada del tendón.

Primena mehaničkog udarnog talasa u lečenju kalcifikovanih tendinopatija

Tendons are the soft tissue that connects muscles to bones. They are made of collagen and elastin, they are strong and solid, and have no possibility of contraction. Their strength helps us to move. Recovery of tendon injuries is long-lasting and can take more than six months. If a tendon is shed during a time injury, calcification occurs at the site of the injury and the disease is called calcifying tendinopathy. The very existence of calcifications is an indication for treatment with a mechanical shock wave (Shock wave). Mechanical shock waves can act in focus or radially. The difference between focused and radial waves is primarily in their physical basis. Focused shock waves differ from radial shock waves in terms of therapeutic depth of penetration into the tissue. The basic biological effect of a mechanical shock wave is stimulating. The energy of the mechanical shock wave acts at the cellular level by stimulating the reduction of inflammation and pain in the tissue. Using mechanical shock wave in the treatment of calcified tendinopathies, a safe method for breaking calcifications was obtained. Shock wave can be applied to using: different frequency, different number of strokes, as well as different strength of strokes in their studies. The choice of parameters for the application depends on whether it is calcified or non-calcified tendinopathy. Indications for the use are: painful shoulder, heel spur, plantar fasciitis, tennis elbow, Achilles tendon tendinopathy, jumping knee, patellar tendinitis, myalgia, myogelosis and muscular tendon overstrain syndrome. Contraindications for the use are: the existence of prostheses, knees and hips, as well as various orthopedic material, pacemaker, as well as the presence of chronic diseases such as multiple sclerosis, amyotrophic lateral sclerosis or tumors. The application of a mechanical shock wave is new, non-invasive method, easy to apply, always reduces pain and practically without side effects. This method has a special role in the treatment of chronic inflammation of diseased tendons, with or without calcification. The only dilemma in the application of a mechanical shock wave can be in the number of applications as well as the time break between the applications of two consecutive mechanical shock waves therapy.

Knee Movement Characteristics of Basketball Players in Landing Tasks Before Onset of Patellar Tendinopathy: A Prospective Study

Knee Movement Characteristics of Basketball Players in Landing Tasks Before Onset of Patellar Tendinopathy: A Prospective Study

Arthroscopic Patellar Tendon Debridement and Distal Pole Osteoplasty for Recalcitrant Patellar Tendinopathy

Background: Chronic patellar tendinosis is an overuse injury of the patellar tendon that commonly afflicts jumping athletes. Indications: For patients with refractory symptoms that do not respond to extensive physical therapy and rest, surgical management may be considered. Although both open and arthroscopic treatments have been described, arthroscopic treatment allows for more direct access to the diseased dorsal portion of the tendon and allows for faster return to activities and sport. Technique Description: Arthroscopic treatment involves debridement of the diseased portion of the patella tendon and osteoplasty of the distal pole of the patella. The infrapatellar fat pad is first debrided using an arthroscopic shaver and radiofrequency ablation device to the level of the dorsal surface of the patellar tendon. Under direct arthroscopic visualization and corresponding to the location of edema noted on the magnetic resonance image, the diseased portion of the patellar tendon is gently debrided with an arthroscopic shaver. Next, an osteoplasty of the distal pole of the patella is performed to facilitate bleeding and healing of the diseased tendon as well as eliminate any mechanical impingement. Any calcifications within the enthesis can be removed using an arthroscopic biter and resector. An arthroscopic resector is then used to decorticate and smoothen the distal pole of the patella to the level of healthy, bleeding cancellous bone. Results: Significant improvements in pain and function have been reported with arthroscopic treatment for chronic patellar tendinosis. Patients can expect a 90% return to sport rate following the procedure, with return to preinjury function as soon as 3 to 5 months. This procedure is well tolerated with minimal complications reported. Discussion: Arthroscopic patellar tendon debridement and distal pole osteoplasty can be used to treat chronic patellar tendinosis refractory to nonoperative treatment. Improvements in pain and function have been reported with this technique, along with a faster return to sport compared with traditional open techniques.

Persons with Patellar Tendinopathy Exhibit Anatomical Features that Alter Knee Extensor Mechanics: A Comparison of Persons with and Without Symptoms

Persons with Patellar Tendinopathy Exhibit Anatomical Features that Alter Knee Extensor Mechanics: A Comparison of Persons with and Without Symptoms

On-site Ultrasound Screens out Asymptomatic Knee Lesions in Elite Adolescent Male Basketball Players.

Basketball is a popular sport worldwide with a high injury risk. In this study, we conducted survey composed of clinical symptom reporting scale, physical examination and meticulous portable musculoskeletal ultrasound to 19 elite male high school basketball players and 15 regular male high school students. Our study showed the incidence of ultrasonographic findings of any lesion, suprapatellar effusion and proximal patellar tendinopathy is significantly higher in player group, and the incidence of asymptomatic ultrasonographic lesion is also higher in player group. Screening for asymptomatic lesions bares clinical relevance and plays a role in prevention of symptom development. With the concise and easy-to-perform ultrasonography protocol we performed and being interpreted by sports team physician, the protocol can offer precise diagnosis of common injury and screening for asymptomatic lesion potentially progressive.

The effect of regenerative therapy in functional outcome in the treatment of patellar and Achilles tendinopathy: A Meta-analysis of Randomized Controlled Clinical Trials

Background: Achilles and patellar tendinopathy are the most common musculoskeletal disorders in lower extremities, with numerous therapeutic modalities for treatment and management. Nowadays, cell-based therapies like stem cells (SC) and platelet-rich plasma (PRP) have satisfactory clinical outcomes. Aim: To perform a meta-analysis of randomized controlled clinical trials to determine the functional efficacy of cell therapy (SC or PRP) in patellar (PT) and Achilles tendinopathy (AT). Study Design: Meta-analysis. Methods: PubMed, Cochrane Library, Google Scholar, SciELO, International Clinical Trials Registry, Clinical Trials.gov, and Lilacs were searched from January 2010 to May 2021. Reference lists were manually checked. Randomized controlled trials (RCTs) using SC and PRP to treat tendinopathy using the Victorian Institute of Sport Assessment (VISA) for patellar (VISA-P) and Achilles (VISA-A) tendinopathy were included. Published RCTs using other treatment modalities, non-tendon condition, non-per-protocol analysis, and other studies designs were excluded. Study quality was assessed using the CONSORT 2010 checklist for reporting a randomized trial. The Cochrane Collaboration risk of bias tool for randomized trials was used, and two review authors assessed their quality. The effect size was reported as a standardized mean difference (SMD) in a random effect model. The sensitivity analysis for publication bias was evaluated. A funnel plot was used, and Egger´s regression test was performed for asymmetry evaluation. Results: A total of eight RCTs with cell therapy were considered. The studies included a total of 318 patients with PT and AT with a mean follow-up of 28.75 (+-11.82) weeks. There was no significant difference between the two groups in the random-effects model (SMD=0.43, 95%CI (-0.52, 1.37), t=1.07, p=0.32). No significant difference between subgroups analysis considered the type of regenerative therapy (Q=3.49, df=2, p=0.17), and injection site (Q=0.36, df=1, p=0.55) were detected. Conclusion: This meta-analysis does not provide enough evidence to support the use of cell therapy (SC and PRP) to manage PT and AT. Keywords: Achilles, Patellar, Platelet-rich plasma, Tendinopathy, VISA.

Latest Trends in Physical Therapy: Extracorporeal Shockwave Therapy

Extracorporeal Shockwave therapy is a scientifically-based therapeutic modality used for treating variety of musculoskeletal disorders. This medical tool is gradually paving its way among the armamentarium of interventions for musculoskeletal conditions, along with its pros and cons. As mirrored by the valuable evidence from the contemporary studies, pending queries await to be resolved related to the mechanism of action of this treatment, the optimal therapy protocol, frequency of sessions, amount of energy applied. For satisfactory and effective alleviation of symptoms, there is need for such type of differential treatment which may contribute to make patient’s condition better.&#x0D; Shockwave therapy is found to be effective for the treatment of tendinopathies, as it may elicit an anti-inflammatory and analgesic response, thus helps in regenerating tissue. Shockwaves are high-pressure acoustic waves that can minimize the enthesopathic pain and increase functionality of patients. This intervention is used as alternative therapy for calcified and non-calcified rotator cuff tendinopathy, Achilles or patellar tendinopathy thus it reduces the need for surgery. These are considered as common medical conditions and the physical therapy rehabilitation plays a significantly important role to recover these patients. The rehabilitation program of patients having tendinopathy creates an immense challenge for rehabilitation specialists and therapists.

Association of Ankle Dorsiflexion and Landing Forces in Jumping Athletes.

Dorsiflexion range of motion restriction has been associated with patellar tendinopathy, but the mechanisms of how dorsiflexion restriction could contribute to knee overload remain unknown. Peak ankle dorsiflexion and ankle dorsiflexion excursion are negatively associated with peak vertical ground-reaction force (vGRF) and loading rate, and with peak patellar tendon force and loading rate, and positively associated with peak ankle plantar flexor moment. Cross-sectional study. Level 4. Kinematic and kinetic data of 26 healthy recreational jumping athletes were measured during a single-leg drop vertical jump. Pearson's correlation coefficients were calculated to establish the association between peak ankle dorsiflexion and ankle dorsiflexion excursion with peak vGRF and vGRF loading rate, with peak patellar tendon force and patellar tendon force loading rate, and with peak ankle plantar flexor moment. Ankle dorsiflexion excursion negatively correlated with peak vGRF loading rate (r = -0.49; P = 0.011) and positively correlated with peak ankle flexor plantar moment (r = 0.52; P = 0.006). In addition, there was a positive correlation between peak ankle dorsiflexion and peak vGRF (r = 0.39; P = 0.05). Ankle kinematics are associated with vGRF loading rate, ankle flexor plantar moment and peak vGRF influencing knee loads, but no association was observed between ankle kinematics and patellar tendon loads. These results suggest that increasing ankle dorsiflexion excursion may be an important strategy to reduce lower limb loads during landings but should not be viewed as the main factor for reducing patellar tendon force.

Collagenase-Induced Patellar Tendinopathy with Neovascularization: First Results towards a Piglet Model of Musculoskeletal Embolization

Background: Therapeutic strategies targeting neovessels responsible for musculoskeletal chronic pain have emerged, including neovessels embolization. Our study aimed to develop a large animal model of patellar tendinopathy with neovascularization. Methods: Nine 3-month-old male piglets (18 patellar tendons) received percutaneous injections of increasing doses of collagenase (0 to 50 mg) at day 0 (D0). Tendinopathy was evaluated by ultrasound (D7 and D14). Neovascularization was evaluated visually and on angiographies. Bonar score was used for histological analysis (D14). Correlations were evaluated using Spearman’s rank (Rs) test. Results: Research protocol was well tolerated. All tendons were enlarged with a median increase of 31.58% [25–40.28] at D7 (p = 0.244) at D7 and 57.52% [48.41–91.45] at D14 (p = 0.065). Tendons with collagenase injection had more hypoechoic changes, with one tendon rupture (p = 0.012). Neovascularization was reported above 5 mg collagenase (p < 0.01) at D7 and D14 with dose-related neovessels induction (Rs = 0.8, p < 0.001). The Bonar score increased above 5 mg collagenase, correlated with the dose (Rs = 0.666, p = 0.003). Conclusions: The study shows the feasibility, safety and reproducibility of this new large animal model of patellar tendinopathy with neovascularization after collagenase injection. It will allow studying new treatments on direct embolization of neovessels by endovascular approach.

Electromyographic activity of quadriceps muscles during eccentric squat exercises: implications for exercise selection in patellar tendinopathy

ABSTRACT This study investigated the quadriceps muscle activity during eccentric squat exercises (ESE) with different decline angles and arcs of motion regarding the proper exercise selection for patellar tendinopathy management. Electromyographic activity of the rectus femoris, vastus lateralis, and vastus medialis obliquus (VMO) muscles was measured during ESE on 0°, 5°, 10°, 15°, and 20° decline in 20 recreationally active participants. The eccentric phase was divided into 0–30°, 30–60°, 60–90°, 0–60°, 30–90°, and 0–90° of knee flexion simultaneously via motion-analysis system. The analyses showed that there was a significant decline angle × arc interaction effect on electromyographic activity of all muscles during knee flexion movement. The main effect was found for the arc of motion of knee flexion, and the main effect for the decline angle also was present for each muscle, except for VMO. This study demonstrated that most selective quadriceps eccentric activation occurred during ESE performed on 20° decline throughout 60–90° of knee flexion.