Is compressive load a factor in the development of tendinopathy?

Elevated fluid and glycosaminoglycan content in the Achilles tendon contribute to higher intratendinous pressures: Implications for Achilles tendinopathy

BACKGROUND

Tendinopathy alters the compositional properties of the Achilles tendon by increasing fluid and glycosaminoglycan content. It has been speculated that these changes may affect intratendinous pressure, but the extent of this relationship remains unclear. Therefore, we aimed to investigate the impact of elevated fluid and glycosaminoglycan content on Achilles tendon intratendinous pressure and to determine whether hyaluronidase (HYAL) therapy can intervene in this potential relationship.

METHODS

Twenty paired fresh-frozen cadaveric Achilles tendons were mounted in a tensile-testing machine and loaded up to 5% strain. Intratendinous resting (at 0% strain) and dynamic pressure (at 5% strain) were assessed using the microcapillary infusion technique. First, intratendinous pressure was measured under native conditions before and after infusion of 2 mL physiological saline. Next, 80 mg of glycosaminoglycans were administered bilaterally to the paired tendons. The right tendons were additionally treated with 1500 units of HYAL. Finally, both groups were retested, and the glycosaminoglycan content was analyzed.

RESULTS

It was found that both elevated fluid and glycosaminoglycan content resulted in higher intratendinous resting and dynamic pressures (p < 0.001). HYAL treatment induced a 2.3-fold reduction in glycosaminoglycan content (p = 0.002) and restored intratendinous pressures.

CONCLUSION

The results of this study demonstrated that elevated fluid and glycosaminoglycan content in Achilles tendinopathy contribute to increased intratendinous resting and dynamic pressures, which can be explained by the associated increased volume and reduced permeability of the tendon matrix, respectively. HYAL degrades glycosaminoglycans sufficiently to lower intratendinous pressures and may, therefore, serve as a promising treatment.

Delivering Microrobots in the Musculoskeletal System

Disorders of the musculoskeletal system are the major contributors to the global burden of disease and current treatments show limited efficacy. Patients often suffer chronic pain and might eventually have to undergo end-stage surgery. Therefore, future treatments should focus on early detection and intervention of regional lesions. Microrobots have been gradually used in organisms due to their advantages of intelligent, precise and minimally invasive targeted delivery. Through the combination of control and imaging systems, microrobots with good biosafety can be delivered to the desired area for treatment. In the musculoskeletal system, microrobots are mainly utilized to transport stem cells/drugs or to remove hazardous substances from the body. Compared to traditional biomaterial and tissue engineering strategies, active motion improves the efficiency and penetration of local targeting of cells/drugs. This review discusses the frontier applications of microrobotic systems in different tissues of the musculoskeletal system. We summarize the challenges and barriers that hinder clinical translation by evaluating the characteristics of different microrobots and finally point out the future direction of microrobots in the musculoskeletal system.

The Micromechanical Environment of the Impinged Achilles Tendon

Although tendon predominantly experiences longitudinal tensile forces, transverse forces due to impingement from bone are implicated in both physiological and pathophysiological processes. However, prior studies have not characterized the micromechanical strain environment in the context of tendon impingement. To address this knowledge gap, mouse hindlimb explants are imaged on a multiphoton microscope, and image stacks of the same population of tendon cells are obtained in the Achilles tendon before and after dorsiflexion-induced impingement by the heel bone. Based on the acquired images, multiaxial strains are measured at the extracellular matrix (ECM), pericellular matrix (PCM), and cell scales. Impingement generated substantial transverse compression at the matrix-scale, which led to longitudinal stretching of cells, increased cell aspect ratio, and enormous volumetric compression of the PCM. These experimental results are corroborated by a finite element model, which further demonstrated that impingement produces high cell surface stresses and strains that greatly exceed those brought about by longitudinal tension. Moreover, in both experiments and simulations, impingement-generated microscale stresses and strains are highly dependent on initial cell-cell gap spacing. Identifying factors that influence the microscale strain environment generated by impingement could contribute to a more mechanistic understanding of impingement-induced tendinopathies.

Posterior Tibial Artery Blood Flow Velocity Is Increased in Patients with Plantar Heel Pain

Background/Objectives: This study aimed to investigate the relationship between posterior tibial artery blood flow velocity and plantar heel pain (PHP). Methods: The PHP group comprised patients diagnosed with plantar fasciitis with plantar heel pain during gait, and the control group comprised healthy participants without plantar heel pain. The peak systolic velocity of the posterior tibial artery was measured using ultrasonography; it was measured three times on each side, and the mean value was calculated. Receiver operating characteristic curve analysis was performed to calculate the peak systolic velocity cutoff value for plantar heel pain. Results: 23 patients (age 58.0 ± 16.5 years; 13 males and 10 females) and 23 healthy participants (age 51.3 ± 17.3 years; 10 males and 13 females) formed the PHP and control groups, respectively. Peak systolic velocity on the affected side was significantly greater in the PHP group (44.1 ± 13.1 cm/s) than in the control group (32.7 ± 5.9 cm/s). No significant difference was observed between the left and right sides in the PHP (7.1 ± 9.8 cm/s) and control (3.7 ± 3.0 cm/s) groups. A cutoff value of 38.2 cm/s was observed on the affected side. Conclusions: We quantified the increase in posterior tibial artery blood flow velocity in patients with plantar heel pain. Peak systolic velocity measurements can aid in quantitatively evaluating these patients. This study was registered as a clinical trial (UMIN000046875) on 1 October 2021.

Clinical Progression and Load Management For Proximal Hamstring Tendinopathy In A Long-Distance Runner: A Case Report

Background and Purpose

The characteristics of Proximal Hamstring Tendinopathy (PHT) include deep, localized pain in the region of the ischial tuberosity. Chronic lesions are often found in long-distance runners. Compression of the tendon and shear force at its insertion at the ischial tuberosity during hip flexion/adduction is a key etiologic factor. The aim of this case report is to analyze the effectiveness of an exercise protocol with progression of tendon loading in PHT in an amateur runner, by assessing pain and functional capacity.

Case Description

The subject was a 30-year-old male runner. After participating in a 10km race, he experienced an insidious onset of deep buttock pain in the right ischial tuberosity. His pain was aggravated by running on sloped roads and prolonged sitting on hard surfaces, particularly while driving. The visual analog scale (VAS) for pain, the Puranen-Orave test (PO), the Bent-Knee stretch test (BK stretch), the supine plank test, the Victorian Institute of Sport Assessment-proximal hamstring tendons (VISA-H) questionnaire, and the sciatic nerve mobility (via the Slump test) were assessed. The intervention involved a 12-week progressive loading exercise program divided into four phases.

Outcomes

The initial pain was reduced at 6 weeks of intervention and further decreased at 12 weeks (VAS from 7, to 5 and to 1). Function increased at 6 weeks and at 12 weeks (VISA-H from 23, to 53, to 80). Sciatic nerve mobility was normal.

Conclusion

The progression of training in a subject with PHT tendon injury based on isometric exercise, concentric/eccentric, energy storage, progressively increasing hip flexion was beneficial, increasing function and decreasing pain. Studies with a larger sample size and a more precise methodological design would be necessary to support this type of intervention in clinical practice.

Level of Evidence

5.

Extensor Carpi Ulnaris Tendinopathy in Athletes: A Review of the Conservative and Rehabilitative Options

BACKGROUND

Extensor carpi ulnaris (ECU) tendinopathy is characterized by pain along the dorsal and ulnar aspect of the wrist and distal forearm. It is common in athletes who play stick and racquet sports due to repetitive motion and axial-loading through the wrist and forearm. Conservative therapeutic options include rest, the use of anti-inflammatory medications, and various injections. Rehabilitation via occupational or physical therapy includes therapeutic exercise, splinting, activity modification, manual therapy, and modalities.

METHODS

A narrative review of the literature on ECU tendinopathy is presented, and a case study approach is used to highlight the clinical management of this condition in an elite athlete.

RESULTS

An approach of medical management and rehabilitation allowed this patient to successfully return to play.

CONCLUSIONS

A combination of conservative measures and rehabilitation can be used to treat ECU tendinopathy and permit patients to be symptom-free and return to their desired activities.

Finite Element Model of the Shoulder with Active Rotator Cuff Muscles: Application to Wheelchair Propulsion

The rotator cuff is prone to injury, remarkably so for manual wheelchair users. To understand its pathomechanisms, finite element models incorporating three-dimensional activated muscles are needed to predict soft tissue strains during given tasks. This study aimed to develop such a model to understand pathomechanisms associated with wheelchair propulsion. We developed an active muscle model associating a passive fiber-reinforced isotropic matrix with an activation law linking calcium ion concentration to tissue tension. This model was first evaluated against known physiological muscle behavior; then used to activate the rotator cuff during a wheelchair propulsion cycle. Here, experimental kinematics and electromyography data was used to drive a shoulder finite element model. Finally, we evaluated the importance of muscle activation by comparing the results of activated and non-activated rotator cuff muscles during both propulsion and isometric contractions. Qualitatively, the muscle constitutive law reasonably reproduced the classical Hill model force-length curve and the behavior of a transversally loaded muscle. During wheelchair propulsion, the deformation and fiber stretch of the supraspinatus muscle-tendon unit pointed towards the possibility for this tendon to develop tendinosis due to the multiaxial loading imposed by the kinematics of propulsion. Finally, differences in local stretch and positions of the lines of action between activated and non-activated models were only observed at activation levels higher than 30%. Our novel finite element model with active muscles is a promising tool for understanding the pathomechanisms of the rotator cuff for various dynamic tasks, especially those with high muscle activation levels.

Tendinopathic Plantaris but Normal Achilles Tendon Found in About One-Fifth of Patients Not Responding to Conservative Achilles Tendon Management - Results from a Prospective WALANT Surgical Case Series on 105 Tendons

Purpose

Midportion Achilles tendinopathy is a relatively common condition. This study aimed to investigate the presence of a normal Achilles tendon, but a tendinopathic plantaris tendon, in a large and consecutive prospective sample of patients referred to a specialised tendon clinic for midportion Achilles tendon pain not responding to non-surgical treatment.

Patients and Methods

A total of 105 consecutive tendons were operated on in 81 patients (62 males) suffering from painful midportion Achilles tendon pain. Clinical examination, ultrasound (US) and colour Doppler (CD) examination, and wide awake local anaesthetic no tourniquet (WALANT) surgery were performed in all patients.

Results

For 19/105 (18%) tendons from 14 patients, clinical examination suspected plantaris tendinopathy alone as there was a distinct tenderness on the medial side, but no thickening of the Achilles tendon. US examination followed by surgery confirmed the diagnosis.

Conclusion

Midportion Achilles tendon pain is not always related to Achilles tendinopathy since pain related to the plantaris tendon alone was found in almost every fifth patient. Consequently, there is an obvious need for proper examination to identify the pain source and establish a correct diagnosis before treatment.

Current and future advances in practice: tendinopathies of the hip

Tendinopathy describes persistent tendon pain and loss of function related to mechanical loading. Two common hip tendinopathies seen in practice are gluteal tendinopathy and proximal hamstring tendinopathy. Both conditions can be frustrating for patients and clinicians due to the delay in diagnosis, significant disability caused and lack of response to common treatments. Tendinopathy is a clinical diagnosis and can most often be made using findings from the patient interview and pain provocation tests, without the need for imaging. Specific education and progressive exercise offer a low-risk and effective option for gluteal tendinopathy and result in greater rates of treatment success than corticosteroid injection, both in the short term (8 weeks) and at 1 year. Proximal hamstring tendinopathy is a common, but less researched, and under-recognized cause of persistent ischial pain. As research on proximal hamstring tendinopathy is limited, this review summarizes the available evidence on diagnosis and treatment following similar principles to other well-researched tendinopathies.

Pathogenesis and Diagnosis of Proximal Hamstring Tendinopathies

The proximal hamstring complex is a highly vulnerable area that is especially prone to injury. Proximal hamstring tendinopathies (PHTs) remain challenging in diagnosis, treatment, rehabilitation, and prevention due to a large variety of different injuries, slow healing response, persistent symptoms, and functional impairments. PHTs are often misdiagnosed or underdiagnosed, leading to delayed treatment and therapy failure. In addition, many athletes are at a high risk of PHT recurrence, a leading cause of prolonged rehabilitation and impaired individual performance. Until now, there have been no clear criteria for the diagnosis and classification of PHT. Tendinopathies can be graded based on their symptoms and onset. Additionally, radiological characteristics exist that describe the severity of tendinopathies. The diagnosis usually includes a battery of pain provocation tests, functional tests, and imaging to ensure a proper classification. Understanding the specific tasks in the pathogenesis and diagnostic process of PHT requires knowledge of functional anatomy, injury pattern and pathophysiological mechanisms as well as examination and imaging techniques. This work provides a structured overview of the pathogenesis and diagnostic work-up of PHT, emphasizing structured examination and imaging to enable a reliable diagnosis and rapid treatment decisions.

Epidemiology of insertional and midportion Achilles tendinopathy in runners: A prospective cohort study

BACKGROUND

Achilles tendinopathy (AT) is a common problem among runners. There is only limited evidence for risk factors for AT, and most studies have not defined the AT subcategories. No study has compared the incidence and risk factors between insertional AT and midportion AT, though they are considered distinct. This study aimed to assess incidence and risk factors of AT based on data from a large prospective cohort. The secondary aim was to explore differences in risk factors between insertional and midportion AT.

METHODS

Participants were recruited from among registered runners at registration for running events. Questionnaires were completed at baseline, 1 month before the event, 1 week before the event, and 1 month after the event. Information concerning demographics, training load, registered events, and running-related injuries were collected at baseline. The follow-up questionnaires collected information about new injuries. A pain map was used to diagnose midportion and insertional AT. The primary outcome was the incidence of AT. Multivariable logistic regression analysis was applied to identify risk factors for the onset.

RESULTS

We included 3379 participants with a mean follow-up of 20.4 weeks. The incidence of AT was 4.2%. The proportion of insertional AT was 27.7% and of midportion AT was 63.8%; the remaining proportion was a combined type of insertional and midportion AT. Men had a significantly higher incidence (5%, 95% confidence interval (95%CI): 4.1%-6.0%) than women (2.8%, 95%CI: 2.0%-3.8%). AT in the past 12 months was the most predominant risk factor for new-onset AT (odds ratio (OR) = 6.47, 95%CI: 4.27 -9.81). This was similar for both subcategories of AT (insertional: OR = 5.45, 95%CI: 2.51-11.81; midportion: OR = 6.96, 95%CI: 4.24-11.40). Participants registering for an event with a distance of 10/10.55 km were less likely to develop a new-onset AT (OR = 0.59, 95%CI: 0.36-0.97) or midportion AT (OR = 0.47, 95%CI: 0.23 -0.93). Higher age had a significant negative association with insertional AT (OR = 0.97, 95%CI: 0.94-1.00).

CONCLUSION

The incidence of new-onset AT among recreational runners was 4.2%. The proportion of insertional and midportion AT was 27.7% and 63.8%, respectively. AT in the past 12 months was the predominant risk factor for the onset of AT. Risk factors varied between insertional and midportion AT, but we could not identify clinically relevant differences between the 2 subtypes.

Effects of exercise-based interventions on gluteal tendinopathy. Systematic review with meta-analysis

The objective of this review was to evaluate the effect of exercise on pain intensity, function, and quality of life in individuals with gluteal tendinopathy. Searches were carried out in PUBMED, EMBASE, CINAHL, Cochrane Library, and PEDro databases. Randomized or quasi-randomized controlled trials were included. Five studies met the eligibility criteria, comparing exercise-based interventions with minimal interventions and/or corticosteroid injections. Three studies, involving 383 participants, were included in the quantitative analysis. Meta-analyses showed that exercise is superior to minimal intervention for function in short-term [mean difference (MD) = 10.24; 95% confidence interval (95%CI) = 5.98, 14.50) and long-term (MD = 6.54; 95%CI = 1.88, 11.21]). However, no difference was observed for quality of life in the short [standardized mean difference (SMD) = 0.33; 95%CI = -0.29, 0.94] and long-term (SMD = 0.11; 95%CI = -0.16, 0.37). The effect of exercise was no different from that of corticosteroid injections for pain intensity in the short (MD = 1.25; 95%CI = -3.56, 6.05) and long-term (MD = -1.37; 95%CI = -3.72, 0.98]). In conclusion, exercise is superior to minimal interventions for function in the short- and long-term in individuals with gluteal tendinopathy. Exercise and corticosteroid injections had similar effects on pain intensity, however, exercise showed a higher treatment success rate when compared to corticosteroid injections in this population. The GRADE analysis revealed that the certainty of the evidence ranges from low to very low, therefore, large high-quality randomized controlled trials are recommended.PROSPERO registration number: CRD42021242853.

Assessing calf exercise fidelity among people with Achilles tendinopathy using videos recorded via Zoom®: an observational study

PURPOSE

Exercise fidelity is a fundamental aspect of exercise prescription by physiotherapists. Assessing exercise fidelity via telehealth (videoconference) is potentially useful but its reproducibility has not been assessed. The objective was to evaluate agreement (reproducibility) of video rating of calf exercise fidelity within (over four weeks) and between telehealth raters and compared with live rating.

METHODS

Nineteen videos of participants with AT undertaking calf exercises were rated by physiotherapists in person (live) and by watching pre-recorded videos (replicating telehealth). Three forms of agreement were assessed: (i) between live assessment and recorded video (telehealth) assessment; (ii) between telehealth raters (inter-rater); (iii) agreement within telehealth raters over four weeks (intra-rater).

RESULTS

There was weak to almost perfect agreement (Kappa = 0.65 to 1.00, rater 1, Kappa = 0.57 to 1.00, rater 2) between the telehealth and live raters. There was moderate to almost perfect agreement (Kappa = 0.65 to 1.00) when assessing intra-rater reliability, aside from one of the six criteria (quality of movement).

CONCLUSION

Assessing calf exercise fidelity via videos recorded on Zoom® appears to demonstrate weak or greater agreement versus live rating and over time. Inter-rater agreement was lower, suggesting that the criteria developed may be better suited to use by individual raters over time.Implications for rehabilitationTelehealth assessment (when compared with live, in person assessment) shows a moderate or greater agreement for the majority of assessment criteria when assessing calf exercise fidelity.The calf exercise fidelity criteria developed can be used as an adjunct to assessment and management of people with Achilles Tendinopathy.Intra-rater assessment was shown to be moderately or more consistent over a four-week period when assessing calf exercise fidelity.

Trunk and glenohumeral joint adaptations to manual wheelchair propulsion over a cross-slope: An exploratory study

BACKGROUND

Cross-slopes are often encountered by manual wheelchair users propelling within an urban setting. While propulsion over cross-slopes is more difficult than on level surfaces, little is known about how the users counter the downhill turning tendency of the wheelchair over cross-slopes. This study aimed to identify the adaptations of the manual wheelchair users to the presence of cross-slopes and examine how these might impact shoulder injury.

METHODS

Nine manual wheelchair users propelled themselves across a cross-slope and over a level surface. The trunk and glenohumeral joint kinematics, as well as the handrim contact tangential force were compared between both conditions for the uphill and downhill limbs.

FINDINGS

The uphill arm technique used to counter the downhill turning tendency varied greatly in terms of potential injury risk and efficiency between participants. Trunk flexion increased the turning tendency of the manual wheelchair, yet only one participant decreased his flexion when rolling over the cross-slope. Various potential pathomecanisms related to the trunk lateral flexion and the glenohumeral kinematics over a cross-slope were identified.

INTERPRETATION

Both the uphill arm technique and trunk kinematics are important to propel over a cross-slope both efficiently and safely. Accordingly, tips about posture and kinematics are needed to teach this skill to manual wheelchair users. Additionally, as wheelchair positioning seems to influence the cross-slope skill, more research is needed to explore the impact of positioning devices (e.g., lateral supports) and wheelchair modifications (e.g., power assist wheels, handrim projections) on this skill.

Biomechanics in the onset and severity of spondyloarthritis: a force to be reckoned with

Increasing evidence suggests that there is a pivotal role for physical force (mechanotransduction) in the initiation and/or the perpetuation of spondyloarthritis; the review contained herein examines that evidence. Furthermore, we know that damage and inflammation can limit spinal mobility, but is there a cycle created by altered spinal mobility leading to additional damage and inflammation?Over the past several years, mechanotransduction, the mechanism by which mechanical perturbation influences gene expression and cellular behaviour, has recently gained popularity because of emerging data from both animal models and human studies of the pathogenesis of ankylosing spondylitis (AS). In this review, we provide evidence towards an appreciation of the unsolved paradigm of how biomechanical forces may play a role in the initiation and propagation of AS.

Gluteal Tendinopathy: Critical Analysis Review of Current Nonoperative Treatments

» Gluteal tendinopathy/greater trochanteric pain syndrome (GTPS) is the most prevalent of all lower limb tendinopathies, affecting 1 in 4 women older than 50 years and commonly individuals within their fifth and sixth decades of life regardless of activity level.» The condition is believed to originate from age-related degenerative changes about the hip abductor tendon insertions and the surrounding bursae, and is exacerbated by congenital and acquired abnormal hip biomechanics.» Treatment of gluteal tendinopathy/GTPS often begins with noninvasive nonoperative modalities such as activity modifications, nonsteroidal anti-inflammatory drugs, and physical therapy. For recalcitrant symptoms, additional nonoperative therapies have been used; however, there remains a lack of comparative efficacy between these adjunct treatments.» In this article, we examine the available literature regarding the nonoperative management of gluteal tendinopathy/GTPS and provide insight into the effectiveness of current treatment modalities.

Inflammation-related signaling pathways in tendinopathy

Tendon is a connective tissue that produces movement by transmitting the force produced by muscle contraction to the bones. Most tendinopathy is caused by prolonged overloading of the tendon, leading to degenerative disease of the tendon. When overloaded, the oxygen demand of tenocytes increases, and the tendon structure is special and lacks blood supply, which makes it easier to form an oxygen-deficient environment in tenocytes. The production of reactive oxygen species due to hypoxia causes elevation of inflammatory markers in the tendon, including PGE2, IL-1β, and TNF-α. In the process of tendon healing, inflammation is also a necessary stage. The inflammatory environment formed by cytokines and various immune cells play an important role in the clearance of necrotic material, the proliferation of tenocytes, and the production of collagen fibers. However, excessive inflammation can lead to tendon adhesions and hinder tendon healing. Some important and diverse biological functions of the body originate from intercellular signal transduction, among which cytokine mediation is an important way of signal transduction. In particular, NF-κB, NLRP3, p38/MAPK, and signal transducer and activator of transcription 3, four common signaling pathways in tendinopathy inflammatory response, play a crucial role in the regulation and transcription of inflammatory factors. Therefore, summarizing the specific mechanisms of inflammatory signaling pathways in tendinopathy is of great significance for an in-depth understanding of the inflammatory response process and exploring how to inhibit the harmful part of the inflammatory response and promote the beneficial part to improve the healing effect of the tendon.

Exploring the role of intratendinous pressure in the pathogenesis of tendon pathology: a narrative review and conceptual framework

Despite the high prevalence of tendon pathology in athletes, the underlying pathogenesis is still poorly understood. Various aetiological theories have been presented and rejected in the past, but the tendon cell response model still holds true. This model describes how the tendon cell is the key regulator of the extracellular matrix and how pathology is induced by a failed adaptation to a disturbance of tissue homeostasis. Such failure has been attributed to various kinds of stressors (eg, mechanical, thermal and ischaemic), but crucial elements seem to be missing to fully understand the pathogenesis. Importantly, a disturbance of tissue pressure homeostasis has not yet been considered a possible factor, despite it being associated with numerous pathologies. Therefore, we conducted an extensive narrative literature review on the possible role of intratendinous pressure in the pathogenesis of tendon pathology. This review explores the current understanding of pressure dynamics and the role of tissue pressure in the pathogenesis of other disorders with structural similarities to tendons. By bridging these insights with known structural changes that occur in tendon pathology, a conceptual model was constituted. This model provides an overview of the possible mechanism of how an increase in intratendinous pressure might be involved in the development and progression of tendon pathology and contribute to tendon pain. In addition, some therapies that could reduce intratendinous pressure and accelerate tendon healing are proposed. Further experimental research is encouraged to investigate our hypotheses and to initiate debate on the relevance of intratendinous pressure in tendon pathology.

Between Two Rocks and in a Hard Place: Reflecting on the Biomechanical Basis of Shoulder Occupational Musculoskeletal Disorders

OBJECTIVE

The aim was to review the biomechanical origins of occupational shoulder damage, while considering the complexity of shoulder mechanics and musculoskeletal consequences of diverse task demands.

BACKGROUND

Accessible measures of physical exposures are the primary focus of occupational shoulder assessments and analyses. This approach has led to guidelines and intervention strategies that are often inadequate for mitigating shoulder disorders amongst the complexity of modern workplace demands. Integration of complex shoulder mechanics into occupational assessments, analyses, and interventions is critical for reducing occupational shoulder injury risk.

METHOD

This narrative review describes shoulder biomechanics in the context of common injury mechanisms and consequent injuries, with a particular focus on subacromial impingement syndrome. Several modulators of shoulder injury risk are reviewed, including fatigue, overhead work, office ergonomics considerations, and pushing and pulling task configurations.

RESULTS

Relationships between work requirements, muscular demands, fatigue, and biomechanical tissue loads exist. This review highlights that consideration of specific workplace factors should be integrated with our knowledge of the intricate arrangement and interpersonal variability of the shoulder complex to proactively evaluate occupational shoulder demands and exposures.

CONCLUSION

A standard method for evaluating shoulder muscle exposures during workplace tasks does not exist. An integrated approach is critical for improved work design and prevention of shoulder tissue damage and accompanying disability.

APPLICATION

This review is particularly relevant for researchers and practitioners, providing guidance for work design and evaluation for shoulder injury prevention by understanding the importance of the unique and complex mechanics of the shoulder.

Mitochondrial transfer from bone mesenchymal stem cells protects against tendinopathy both in vitro and in vivo

BACKGROUND

Although mesenchymal stem cells (MSCs) have been effective in tendinopathy, the mechanisms by which MSCs promote tendon healing have not been fully elucidated. In this study, we tested the hypothesis that MSCs transfer mitochondria to injured tenocytes in vitro and in vivo to protect against Achilles tendinopathy (AT).

METHODS

Bone marrow MSCs and H₂O₂-injured tenocytes were co-cultured, and mitochondrial transfer was visualized by MitoTracker dye staining. Mitochondrial function, including mitochondrial membrane potential, oxygen consumption rate, and adenosine triphosphate content, was quantified in sorted tenocytes. Tenocyte proliferation, apoptosis, oxidative stress, and inflammation were analyzed. Furthermore, a collagenase type I-induced rat AT model was used to detect mitochondrial transfer in tissues and evaluate Achilles tendon healing.

RESULTS

MSCs successfully donated healthy mitochondria to in vitro and in vivo damaged tenocytes. Interestingly, mitochondrial transfer was almost completely blocked by co-treatment with cytochalasin B. Transfer of MSC-derived mitochondria decreased apoptosis, promoted proliferation, and restored mitochondrial function in H₂O₂-induced tenocytes. A decrease in reactive oxygen species and pro-inflammatory cytokine levels (interleukin-6 and -1β) was observed. In vivo, mitochondrial transfer from MSCs improved the expression of tendon-specific markers (scleraxis, tenascin C, and tenomodulin) and decreased the infiltration of inflammatory cells into the tendon. In addition, the fibers of the tendon tissue were neatly arranged and the structure of the tendon was remodeled. Inhibition of mitochondrial transfer by cytochalasin B abrogated the therapeutic efficacy of MSCs in tenocytes and tendon tissues.

CONCLUSIONS

MSCs rescued distressed tenocytes from apoptosis by transferring mitochondria. This provides evidence that mitochondrial transfer is one mechanism by which MSCs exert their therapeutic effects on damaged tenocytes.

Biomechanics and lower limb function are altered in athletes and runners with achilles tendinopathy compared with healthy controls: A systematic review

Achilles tendinopathy (AT) is a debilitating injury in athletes, especially for those engaged in repetitive stretch-shortening cycle activities. Clinical risk factors are numerous, but it has been suggested that altered biomechanics might be associated with AT. No systematic review has been conducted investigating these biomechanical alterations in specifically athletic populations. Therefore, the aim of this systematic review was to compare the lower-limb biomechanics of athletes with AT to athletically matched asymptomatic controls. Databases were searched for relevant studies investigating biomechanics during gait activities and other motor tasks such as hopping, isolated strength tasks, and reflex responses. Inclusion criteria for studies were an AT diagnosis in at least one group, cross-sectional or prospective data, at least one outcome comparing biomechanical data between an AT and healthy group, and athletic populations. Studies were excluded if patients had Achilles tendon rupture/surgery, participants reported injuries other than AT, and when only within-subject data was available.. Effect sizes (Cohen's d) with 95% confidence intervals were calculated for relevant outcomes. The initial search yielded 4,442 studies. After screening, twenty studies (775 total participants) were synthesised, reporting on a wide range of biomechanical outcomes. Females were under-represented and patients in the AT group were three years older on average. Biomechanical alterations were identified in some studies during running, hopping, jumping, strength tasks and reflex activity. Equally, several biomechanical variables studied were not associated with AT in included studies, indicating a conflicting picture. Kinematics in AT patients appeared to be altered in the lower limb, potentially indicating a pattern of "medial collapse". Muscular activity of the calf and hips was different between groups, whereby AT patients exhibited greater calf electromyographic amplitudes despite lower plantar flexor strength. Overall, dynamic maximal strength of the plantar flexors, and isometric strength of the hips might be reduced in the AT group. This systematic review reports on several biomechanical alterations in athletes with AT. With further research, these factors could potentially form treatment targets for clinicians, although clinical approaches should take other contributing health factors into account. The studies included were of low quality, and currently no solid conclusions can be drawn.

Intratendinous pressure changes in the Achilles tendon during stretching and eccentric loading: Implications for Achilles tendinopathy

Mechanical overload is considered the main cause of Achilles tendinopathy. In addition to tensile loads, it is believed that the Achilles tendon may also be exposed to compressive loads. However, data on intratendinous pressures are lacking, and consequently, their role in the pathophysiology of tendinopathy is still under debate. Therefore, we aimed to evaluate the intratendinous pressure changes in the Achilles tendon during stretching and eccentric loading. Twelve pairs of human cadaveric legs were mounted in a testing rig, and a miniature pressure catheter was placed through ultrasound-guided insertion in four different regions of the Achilles tendon: the insertion (superficial and deep layers), mid-portion, and proximal portion. Intratendinous pressure was measured during three simulated loading conditions: a bent-knee calf stretch, a straight-knee calf stretch, and an eccentric heel-drop. It was found that the intratendinous pressure increased exponentially in both the insertion and mid-portion regions of the Achilles tendon during each loading condition (p < 0.001). The highest pressures were consistently found in the deep insertion region (p < 0.001) and during the eccentric heel-drop (p < 0.001). Pressures in the mid-portion were also significantly higher than in the proximal portion (p < 0.001). These observations offer novel insights and support a role for compression in the pathophysiology of Achilles tendinopathy by demonstrating high intratendinous pressures at regions where Achilles tendinopathy typically occurs. To what extent managing intratendinous pressure might be successful in patients with Achilles tendinopathy by, for example, avoiding excessive stretching, modifying exercise therapy, and offering heel lifts requires further investigation.

Hamstring Injuries: Critical Analysis Review of Current Nonoperative Treatments

➢

Hamstring injuries are common among active and athletic individuals, especially those involved in high-speed running, distance running, or sports requiring sudden directional changes. Acute hamstring strains often occur as an eccentric strain during running or a stretch-type injury caused by simultaneous hip flexion and knee extension. Proximal hamstring tendinopathy is an overuse injury of the hamstring tendon as a result of chronic cicatrization of the musculotendinous unit.

➢

Repeated stress to the hamstring tendon leads to increased cellularity of tendon fibers, disruption of collagen, and subsequent microinjury of the tissue that attaches the tendon to bone.

➢

Management of hamstring injuries generally begins with nonoperative modalities consisting of eccentric rehabilitative exercise programs. Although various other treatment modalities are available, the comparative efficacy of these supportive measures is not well differentiated at this time.

➢

In this article, we review the current literature with regard to the nonoperative treatment of hamstring injuries, specifically focusing on acute hamstring muscle strains and proximal hamstring tendinopathy in order to provide supplementary insight on the effectiveness of current modalities.

Advances toward transformative therapies for tendon diseases

Approved therapies for tendon diseases have not yet changed the clinical practice of symptomatic pain treatment and physiotherapy. This review article summarizes advances in the development of novel drugs, biologic products, and biomaterial therapies for tendon diseases with perspectives for translation of integrated therapies. Shifting from targeting symptom relief toward disease modification and prevention of disease progression may open new avenues for therapies. Deep evidence-based clinical, cellular, and molecular characterization of the underlying pathology of tendon diseases, as well as therapeutic delivery optimization and establishment of multidiscipline interorganizational collaboration platforms, may accelerate the discovery and translation of transformative therapies for tendon diseases.

Unilateral symptomatic Achilles tendinopathy has limited effects on bilateral lower limb ground reaction force asymmetries and muscular synergy attributes when walking at natural and fast speeds

BACKGROUND

Achilles tendinopathy (AT) may affect ground reaction force (GRF) and muscle synergy (MS) during walking due to pain, biological integrity changes in the tendon and neuroplastic adaptations. The objective of this study was to compare GRF asymmetries and MS attributes between symptomatic and asymptomatic lower limbs (LL) during walking at natural and fast speeds in adults with unilateral AT.

METHODS

A convenience sample consisting of twenty-eight participants walked on an instrumented treadmill at natural (1.3 m/s) and fast (1.6 m/s) speeds. Peak GRF were measured in mediolateral, anteroposterior and vertical directions. Individualized electromyography (EMG) activation profiles were time- and amplitude-normalized for three consecutive gait cycles and MS were extracted using non-negative matrix factorization algorithms. MS were characterized by the number, composition (i.e., weighting of each muscle) and temporal profiles (i.e., duration and amplitude) of the MS extracted during walking. Paired Student's t-tests assessed peak GRF and MS muscle weighting differences between sides whereas Pearson correlation coefficients characterized the similarities of the individualized EMG and MS activation temporal profiles within sides.

RESULTS

AT had limited effects on peak GRF asymmetries and the number, composition and temporal profiles of MS between symptomatic and asymptomatic LL while walking on a level treadmill at natural and fast speeds. In most participants, four MS with a specific set of predominantly activated muscles were extracted across natural (71 and 61%) and fast (54 and 50%) walking speeds for the symptomatic and asymptomatic side respectively. Individualized EMG activation profiles were relatively similar between sides (r = 0.970 to 0.999). As for MS attributes, relatively similar temporal activation profiles (r = 0.988 to 0.998) and muscle weightings (p < 0.05) were found between sides for all four MS and the most solicited muscles. Although the faster walking speed increased the number of merged MS for both sides, it did not significantly alter MS symmetry.

CONCLUSION

Faster walking speed increased peak GRF values but had limited effects on GRF symmetries and MS attribute differences between the LL. Corticospinal neuroplastic adaptations associated with chronic unilateral AT may explain the preserved quasi-symmetric LL motor control strategy observed during natural and fast walking among adults with chronic unilateral AT.

Modelling and in vivo evaluation of tendon forces and strain in dynamic rehabilitation exercises: a scoping review

OBJECTIVES

Although exercise is considered the preferred approach for tendinopathies, the actual load that acts on the tendon in loading programmes is usually unknown. The objective of this study was to review the techniques that have been applied in vivo to estimate the forces and strain that act on the human tendon in dynamic exercises used during rehabilitation.

DESIGN

Scoping review.

DATA SOURCES

Embase, PubMed, Web of Science and Google Scholar were searched from database inception to February 2021.

ELIGIBILITY CRITERIA

Cross-sectional studies available in English or Spanish language were included if they focused on evaluating the forces or strain of human tendons in vivo during dynamic exercises. Studies were excluded if they did not evaluate tendon forces or strain; if they evaluated running, walking, jumping, landing or no dynamic exercise at all; and if they were conference proceedings or book chapters.

DATA EXTRACTION AND SYNTHESIS

Data extracted included year of publication, study setting, study population characteristics, technique used and exercises evaluated. The studies were grouped by the types of techniques and the tendon location.

RESULTS

Twenty-one studies were included. Fourteen studies used an indirect methodology based on inverse dynamics, nine of them in the Achilles and five in the patellar tendon. Six studies implemented force transducers for measuring tendon forces in open carpal tunnel release surgery patients. One study applied an optic fibre technique to detect forces in the patellar tendon. Four studies measured strain using ultrasound-based techniques.

CONCLUSIONS

There is a predominant use of inverse dynamics, but force transducers, optic fibre and estimations from strain data are also used. Although these tools may be used to make general estimates of tendon forces and strains, the invasiveness of some methods and the loss of immediacy of others make it difficult to provide immediate feedback to the individuals.

Subscapularis tendinopathy is highly prevalent in elite swimmer's shoulders: an MRI study

OBJECTIVES

The aim of this study is to determine the prevalence of abnormal anatomical change present on MRI in elite swimmers' shoulders compared to age-matched controls.

DESIGN

Descriptive epidemiological study.

METHODS

Sixty (aged 16-36 years) elite Australian swimmers and 22 healthy active, age and gender matched controls (aged 16-34 years). All participants completed a demographic, and training load and shoulder pain questionnaire and underwent shoulder MRI. Tests for differences in the population proportion was used for comparison between swimmers dominant and non-dominant shoulders and those of the controls.

RESULTS

Subscapularis and supraspinatus tendinopathy was the most common tendon abnormality identified in swimming participants, being reported in at least one shoulder in 48/60 (73 %) and 46/60 (70 %) swimmers, respectively. There was no significant difference between dominant and non-dominant shoulders for either tendinopathy, however, grade 3 tendinopathy was significantly more prevalent in subscapularis than in supraspinatus (P < 0.01). Compared with controls, significantly more abnormalities were reported in swimmers' shoulders in both subscapularis and supraspinatus tendons along with the labrum and acromioclavicular joint. Pathology was not a predictor of current pain.

CONCLUSIONS

This data confirms that tendon abnormality is the most common finding in elite swimmers' shoulders. Furthermore, that subscapularis tendinopathy is not only as common as supraspinatus but has a greater prevalence of grade 3 tendinopathy. With significant varied abnormalities including tendinopathy being so common in both symptomatic and asymptomatic shoulders of swimming athletes', clinicians should consider imaging findings alongside patient history, symptom presentation and clinical examination in determining their relevance in the presenting condition.

Impingement in Insertional Achilles Tendinopathy Occurs Across a Larger Range of Ankle Angles and Is Associated With Increased Tendon Thickness

BACKGROUND

Insertional Achilles tendinopathy (IAT) is characterized by tendon degeneration and thickening near the tendon-bone insertion.¹¹ Calcaneal impingement is believed to contribute to the pathogenesis of IAT.⁵ However, it is unclear how increased tendon thickness in individuals with IAT influences impingement. This study aimed to compare Achilles tendon impingement in individuals with and without IAT.

METHODS

Eight healthy adults and 12 adults with clinically diagnosed symptomatic IAT performed a passive flexion exercise during which ankle flexion angle, anterior-posterior (A-P) thickness, and an ultrasonographic image sequence of the Achilles tendon insertion were acquired. The angle of ankle plantarflexion at which the calcaneus first impinges the Achilles tendon, defined as the impingement onset angle, was identified by (1) a anonymized observer (visual inspection method) and (2) a computational image deformation-based approach (curvature method).

RESULTS

Although the 2 methods provided different impingement onset angles, the measurements were strongly correlated (R² = 0.751, P < .05). The impingement onset angle and the thickness of the Achilles tendon insertion were greater in subjects with clinically diagnosed IAT (P = .0048, P = .0047). Furthermore, impingement onset angle proved to have a moderate correlation with anterior-posterior thickness (R² = 0.454, P < .05).

CONCLUSION

Our findings demonstrated that increased tendon thickness in IAT patients is associated with larger impingement onset angles, raising the range of ankle angles over which the tendon is exposed to impingement.

CLINICAL RELEVANCE

Increased susceptibility to impingement may exacerbate or perpetuate the pathology, highlighting the need for clinical strategies to reduce impingement in IAT patients.

Antioxidant effect of nicotinamide mononucleotide in tendinopathy

Background

A link between tendinopathy and oxidative stress has been recently reported. Nicotinamide mononucleotide (NMN) is a precursor of nicotinamide adenine dinucleotide, which plays an important role in cell redox homeostasis. The aim of this study was to evaluate the antioxidant effect of NMN on tendinopathy in vitro and in vivo.

Methods

Tenocytes from healthy Sprague-Dawley rats were cultured in regular glucose (RG) and high-glucose (HG) conditions with or without NMN, and were divided into four groups: RG NMN(−), RG NMN(+), HG NMN(−), and HG NMN(+). Cell viability, reactive oxygen species (ROS) accumulation, apoptotic rate, and mRNA expression of nicotinamide adenine dinucleotide phosphate oxidase (NOX)1, NOX4, interleukin (IL)6, sirtuin (SIRT)1, and SIRT6 were investigated. In addition, rats with collagenase-induced tendinopathy were treated with or without NMN. Immunostaining of NOX1 and NOX4; mRNA expression of SIRT1, SIRT6, and IL6; and superoxide dismutase (SOD) activity measurements in the Achilles tendon were performed.

Results

NMN increased the expression of SIRT1 and SIRT6 in rat tenocytes, but decreased the levels of NOX1, NOX4, IL6, ROS, and apoptosis. In Achilles tendons with collagenase-induced tendinopathy, NMN increased the mRNA expression of SIRT1 and SIRT6, as well as SOD activity; while suppressing protein expression of NOX1 and NOX4, and mRNA expression of IL6.

Conclusion

The in vitro and in vivo results of this study show that NMN exerts an antioxidant effect on tendinopathy by promoting the expression of SIRT while inhibiting that of NOX.

Does Menopausal Hormone Therapy, Exercise, or Both Improve Pain and Function in Postmenopausal Women With Greater Trochanteric Pain Syndrome? A 2 × 2 Factorial Randomized Clinical Trial

BACKGROUND

Greater trochanteric pain syndrome (GTPS) is a debilitating chronic condition, most prevalent in postmenopausal women. A positive association between high estrogen levels and tendon health may exist, and postmenopausal women have reduced estrogen. Menopausal hormone therapy (MHT) may reduce the incidence of tendon abnormality, particularly when combined with exercise.

PURPOSE

To determine the effect of MHT and exercise on tendon pain and function in postmenopausal women with GTPS.

STUDY DESIGN

Randomized controlled clinical trial; Level of evidence, 1.

METHODS

Postmenopausal women (N = 132; n = 12, lost to follow-up) with GTPS were randomized into MHT and placebo transdermal cream groups combined with tendon-specific or sham exercise. All groups received education about avoiding gluteal tendon compression and load management throughout 12 weeks of intervention. The primary outcome was the Victorian Institute of Sport Assessment for gluteal tendinopathy (VISA-G), and secondary outcomes were measured at baseline and at 12 and 52 weeks. The Global Rating of Change was assessed at 12 and 52 weeks. A linear mixed-effects model was used to assess differences. Body mass index (BMI) was included as a covariate.

RESULTS

All participant groups improved over time (baseline vs 12 weeks, P < .001; baseline vs 52 weeks, P < .001). There was no difference among exercise groups measured by all outcomes (VISA-G: baseline, P = .97, mean difference [MD] = 0.10; 12 weeks, P = .49, MD = 2.15; 52 weeks, P = .32, MD = -3.08). There was a significant interaction effect between cream and BMI; therefore, the population was stratified by BMI levels (<25, <30, ≥30). The MHT groups (with exercise and education) had significantly better VISA-G outcomes (baseline, P = .04, MD = -11.20, 95% CI = -21.70 to -0.70; 12 weeks, P < .001, MD = -20.72, 95% CI = -31.22 to -10.22; 52 weeks, P = .002, MD = -16.71, 95% CI = -27.21 to -6.22) and secondary measure scores as compared with placebo at all time points when BMI was <25.

CONCLUSION

MHT or placebo combined with tendon-specific or sham exercise plus education reduced pain and increased function for this population. For women with a BMI <25, MHT with any exercise plus education was better than placebo. A targeted exercise or sham exercise strategy is effective when prescribed with education about avoiding gluteal tendon compression and load management.

REGISTRATION

ACTRN12614001157662 (Australian New Zealand Clinical Trials Registry).

Ultrasound strain mapping of the mouse Achilles tendon during passive dorsiflexion

Immediately prior to inserting into bone, many healthy tendons experience impingement from nearby bony structures. However, super-physiological levels of impingement are implicated in insertional tendinopathies. Unfortunately, the mechanisms underlying the connection between impingement and tendon pathology remain poorly understood, in part due to the shortage of well-characterized animal models of impingement at clinically relevant sites. As a first step towards developing a model of excessive tendon impingement, the objective of this study was to characterize the mechanical strain environment in the mouse Achilles tendon insertion under passive dorsiflexion and confirm that - like humans - mice experience impingement of the tendon insertion from the calcaneus (heel bone) in dorsiflexed ankle positions. Based on previous work in humans, we hypothesized that during dorsiflexion, the mouse Achilles tendon insertion would experience high levels of transverse compressive strain due to calcaneal impingement. A custom-built loading platform was used to apply passive dorsiflexion, while an ultrasound transducer positioned over the Achilles tendon captured radiofrequency images. A non-rigid image registration algorithm was then used to map the transverse compressive strain based on the acquired ultrasound image sequences. Our results demonstrate that during passive dorsiflexion, transverse compressive strains were produced throughout the Achilles tendon, with significantly larger strain magnitudes at the tendon insertion than at the midsubstance. Furthermore, there was increasing transverse compressive strain observed within the Achilles tendon as a function of increasing dorsiflexion angle. This study enhances our understanding of the unique mechanical loading environment of the Achilles tendon under physiologically relevant conditions.

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

BACKGROUND

Patella 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 DESIGN

Prospective cohort study.

METHODS

28 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".

RESULTS

There 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.

CONCLUSIONS

Patients 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.

Current understanding of the diagnosis and management of the tendinopathy: An update from the lab to the clinical practice

Tendinopathy is labeled by many authors as a troublesome, common pathology, present in up to 30% medical care consultations involving musculoskeletal conditions. Despite the lasting interest for addressing tendon pathology, current researchers agree that even the exact definition of the term tendinopathy is unclear. Tendinopathy is currently diagnosed as a clinical hypothesis based on the patient symptoms and physical context. One of the main goals of current clinical management is to personalize treatment approaches to adapt them to the many different needs of the population. Tendons are complex structures that unite muscles and bones with two main objectives: to transmit forces and storage and release energy. Regarding the tensile properties of the tendons, several authors argued that tendons have higher tensile strength compared with muscles, however, are considered less flexible. Tendinopathy is an accepted term which is used to indicated a variety of tissue conditions that appear in injured tendons and describes a non-rupture damage in the tendon or paratendon, which is intensified with mechanical loading Even when the pathoetiology of tendinopathy is unclear, there is a wide array of treatments available to treat and manage tendinopathy. Although tendinitis usually debuts with an inflammatory response, the majority of chronic tendinopathies do not present inflammation and so the choosing of treatment should vary depending on severity, compliance, pain and duration of symptoms. The purpose of this article is to review and provide an overview about the currently research of the tendon diagnosis, management and etiology.

Rehabilitation After Gluteus Medius and Minimus Treatment

We reviewed the current literature regarding rehabilitation after gluteus medius and minimus tears as part of a conservative management or postoperative protocol. The greater trochanteric pain syndrome includes a constellation of pathologies that generate pain in the greater trochanteric region and may be accompanied by varying degrees of hip abductor disfunction. It may be related to tendinitis of the gluteus medius and minimus, greater trochanteric bursitis, or even formal tears of the hip abductor tendons. The initial management strategy of the hip abductor tears is conservative, including different anti-inflammatory therapies such as physical therapy and cortisone and platelet-rich plasma injections. The clearest indication for surgical management is failure of conservative management and loss of abductor muscle power. Surgical management has been performed both open and endoscopic with good reported clinical results. More severe tears typically require a more rigid and complex type of fixation. Exorcise intervention seem to improve symptoms after 4 months to a year of therapy therefore a very close supervision of the rehabilitation protocol is mandatory. Gluteus medius and minimus tears are frequent and may be not diagnosed timely. Treatment of these of lesions is based on the knowledge of pathomechanics involved and the extent of injury to the tendon and muscle tissue. Conservative management is based on protecting the hip abductor tendons from excessive tensile and compression stresses while applying progressive load in conjunction with physical and medical anti-inflammatory measures. Surgical treatment is indicated when conservative management fails or an abductor power deficit is associated with pain. Similar physical therapy protocols to those used in conservative management are used postoperatively.

Level of Evidence

Level V, expert opinion.

Management of Patellar Tendinopathy Through Monitoring, Load Control, and Therapeutic Exercise: A Systematic Review

CONTEXT

Patellar tendinopathy presents with persistent tendon pain located in the lower pole of the patella and loss of function related to mechanical load. Although its pathogenesis is not completely clear, conservative treatment including exercise is the main intervention of patellar tendinopathy treatment.

OBJECTIVE

To describe the efficacy of patellar tendinopathy management through therapeutic exercise, and control and monitoring of loads.

EVIDENCE ACQUISITION

MEDLINE, WoS, Cochrane Plus, PEDro, and the gray literature were searched from inception to July 2021. Based on the PICO strategy, the inclusion criteria were clinical trials published in English or Spanish; outcomes of function, pain, and strength; patients with patellar tendinopathy with no age or gender limitations; using an active intervention; and at least a methodological quality equal to or greater than 3 points on the Jadad scale. All data were analyzed by 2 independent reviewers (P.N.-M. and D.H.-G.). Studies were qualitatively synthesized using a descriptive synthesis. The methodological quality and risk of bias assessment were performed with the PEDro and Jadad scale, respectively.

EVIDENCE SYNTHESIS

A total of 136 articles were identified, of which 12 met the eligibility criteria. All of them were regarded as presenting a moderate risk of bias and their methodological quality was considered acceptable to good. Recovering patellar tendinopathy with therapeutic exercise seems to significantly improve function, pain, and strength after intervention and even lasted over time.

CONCLUSION

A treatment based on load monitoring and physical exercise has proven to be effective in rehabilitating patellar tendinopathy, with positive results in the short and medium term.

Combined extracorporeal shockwave therapy and exercise for the treatment of tendinopathy: A narrative review

Tendinopathy is a chronic degenerative musculoskeletal disorder that is common in both athletes and the general population. Exercise and extracorporeal shockwave therapy (ESWT) is among the most common treatments used to mediate tendon healing and regeneration. The review presents the current understanding of mechanisms of action of ESWT and exercise in isolation and briefly synthesises evidence of their effectiveness for various tendinopathies. The central purpose of the review is to synthesize research findings investigating the combination of ESWT and exercise for five common tendinopathies (plantar heel pain, rotator cuff, lateral elbow, Achilles, and patellar tendinopathy) and provide recommendations on clinical applicability. Collectively, the available evidence indicates that ESWT combined with exercise in the form of eccentric training, tissue-specific stretching, or heavy slow resistance training are effective for specific tendinopathies and can therefore be recommended in treatment. Whilst there are at present a limited number of studies investigating combined EWST and exercise approaches, there is evidence to suggest that the combination improves outcomes in the treatment of plantar heel pain, Achilles, lateral elbow, and rotator cuff tendinopathy. However, despite overall positive outcomes in patellar tendinopathy, the combined treatment has not been shown at present to offer additional benefit over eccentric exercise alone.

Tendinopathy and tendon material response to load: What we can learn from small animal studies

Tendinopathy is a debilitating disease that causes as much as 30% of all musculoskeletal consultations. Existing treatments for tendinopathy have variable efficacy, possibly due to incomplete characterization of the underlying pathophysiology. Mechanical load can have both beneficial and detrimental effects on tendon, as the overall tendon response depends on the degree, frequency, timing, and magnitude of the load. The clinical continuum model of tendinopathy offers insight into the late stages of tendinopathy, but it does not capture the subclinical tendinopathic changes that begin before pain or loss of function. Small animal models that use high tendon loading to mimic human tendinopathy may be able to fill this knowledge gap. The goal of this review is to summarize the insights from in-vivo animal studies of mechanically-induced tendinopathy and higher loading regimens into the mechanical, microstructural, and biological features that help characterize the continuum between normal tendon and tendinopathy. STATEMENT OF SIGNIFICANCE: This review summarizes the insights gained from in-vivo animal studies of mechanically-induced tendinopathy by evaluating the effect high loading regimens have on the mechanical, structural, and biological features of tendinopathy. A better understanding of the interplay between these realms could lead to improved patient management, especially in the presence of painful tendon.

Effect of a common exercise programme with an individualised progression criterion based on the measurement of neuromuscular capacity versus current best practice for lower limb tendinopathies (MaLaGa trial): a protocol for a randomised clinical trial

INTRODUCTION

High-load resistance training has shown positive effects in pain and function in lower limb tendinopathies. However, some authors suggest that current exercise programmes produce an increase in tolerance to load and exercise in general but without fixing some existing issues in tendinopathy. This may indicate the need to include training aspects not currently taken into account in the current programmes. The main objective of this study will be to compare the effect of a common exercise protocol for the three predominant lower limb tendinopathies (Achilles, patellar and gluteal), based on an individualised control of the dose and training of specific aspects of the neuromuscular system versus the current best practice for each location.

METHODS AND ANALYSIS

This study will be conducted among people with mid-portion Achilles, patellar or gluteal tendinopathy. The participants allocated to the experimental group will perform a 14-week innovative common therapeutic exercise programme. Participants allocated to the control group will carry out a 14-week exercise programme based on the best current practice for each of the studied locations. The Victorian Institute of Sports Assessment questionnaire will be considered the primary outcome. Pain, central sensitisation, fear avoidance behaviour, quality of life, treatment satisfaction, lower-limb strength and function, and high-density electromyography profile will be evaluated as secondary outcomes. Outcomes will be assessed at baseline, 7 weeks, after the intervention (week 14), 26 weeks and 52 weeks.

ETHICS AND DISSEMINATION

The study has been approved by the Portal de Ética de la Investigación Biomédica de Andalucía Ethics Committee (1221-N-19). All participants will be informed about the purpose and content of the study and written informed consent will be completed. The results of this study will be published in a peer-reviewed journal and will be disseminated electronically and in print.

TRIAL REGISTRATION NUMBER

NCT03853122; Pre-results.

Non-surgical treatment as the first step to manage peritrochanteric space disorders

PURPOSE

Greater trochanter pain syndrome (GTPS) or lateral hip pain terms include external snapping hip, trochanteric bursitis and gluteus medius or minimus pathology. The aim of this review is to update the most recent knowledge about non-surgical management of peritrochanteric disorders.

METHODS

A literature review was performed including articles most relevant in the last years that were focused in non-surgical treatment of peritrochanteric disorders.

RESULTS

Conservative treatment still has a place and includes activity modification, NSAIDs, analgesics, physiotherapy, home training, local corticosteroid injection (CSI) and shock wave therapy (SWT). These non-surgical alternatives have demonstrated good clinical results with low rate of complications.

CONCLUSION

Most patients tend to resolve GTPS or lateral hip pain with non-surgical management in the mid-term but when everything failed, surgical options should be evaluated. The next frontier that will be a game changer is to determine an individualized treatment plan based on the exact pathology.

LEVEL OF EVIDENCE

V.

Distal semimembranosus tendinopathy: A narrative review

Distal semimembranosus tendinopathy is a relatively uncommon diagnosis that can be responsible for medial knee pain. The semimembranosus tendon inserts on the posteromedial knee and is surrounded by the semimembranosus bursa, with both the bursa and tendon potential sources of pain. Similar to other tendinopathies, semimembranosus tendinopathy often occurs with overuse of the musculotendinous unit and is commonly seen in runners. Diagnosis can be made clinically and may be substantiated with use of ultrasound or magnetic resonance imaging. Scant literature exists evaluating the efficacy of treatments for this condition. Consequently, best practice for treatment is inferred from other similar tendinopathies, clinical expertise, and smaller studies on semimembranosus tendinopathy. Extrapolating from other tendinopathies, rehabilitation should be the cornerstone of initial treatment, with focus on kinetic chain and gait abnormalities, hamstring strength and neuromuscular control, and progressive tendon loading. Recalcitrant cases with a coexisting bursopathy can be treated with an ultrasound-guided bursal corticosteroid injection. Future studies may help delineate the optimal treatment regimen for this relatively uncommon diagnosis.

Clinical Tests of Tibialis Posterior Tendinopathy: Are They Reliable, and How Well Are They Reflected in Structural Changes on Imaging?

OBJECTIVE

To determine the reliability of common clinical tests for tibialis posterior tendinopathy (TPT) and to investigate their relationship with grayscale ultrasound findings in individuals who have medial foot/ankle pain.

DESIGN

Prospective cohort.

METHODS

Fifty-two individuals reporting medial foot/ankle pain were clinically examined by 2 physical therapists using 4 clinical tests for TPT: pain on tendon palpation, swelling around the tendon, pain/weakness with tibialis posterior contraction, and pain during or inability to perform a single-leg heel raise (SLHR). Individuals also underwent an ultrasound examination by a sonographer. Physical therapists and the sonographer were blind to each other's findings. Positive ultrasound examination included at least 1 of the following grayscale changes: hypoechogenicity, fibrillar disruption, or thickening of the tendon. For reliability between the 2 physical therapists, we calculated kappa coefficients and 95% confidence intervals (CIs). To assess relationships between clinical and imaging findings, we calculated odds ratios and 95% CIs.

RESULTS

The SLHR was the most reliable test, with substantial agreement between physical therapists (κ = 0.74; 95% CI: 0.54, 0.93), while the other tests had moderate levels of reliability. Of all clinical tests, the SLHR was most related to grayscale findings on ultrasound (odds ratio = 5.8), but was imprecisely so, with a 95% CI of 1.7 to 20.4.

CONCLUSION

Of all tests, the SLHR was the most reliable between clinicians and best related to imaging findings in individuals presenting with TPT, aligning with contemporary thinking of tendinopathy as a load-related clinical presentation. There was a disconnect between clinical findings and ultrasound grayscale changes in the tibialis posterior tendon in individuals with TPT. J Orthop Sports Phys Ther 2021;51(5):253-260. Epub 28 Mar 2021. doi:10.2519/jospt.2021.9707.

Differences in Biomechanical Loading Magnitude During a Landing Task in Male Athletes with and without Patellar Tendinopathy

CONTEXT

Prior research has not established if overloading or underloading movement profiles are present in symptomatic and asymptomatic athletes with patellar tendon structural abnormality (PTA) compared to healthy athletes.

OBJECTIVE

The purpose was to compare involved limb landing biomechanics between male athletes with and without patellar tendinopathy.

DESIGN

Cross-sectional study Setting: Laboratory Patients or Other Participants: 43 males were grouped based on patellar tendon pain & ultrasound imaging of the proximal patellar tendon: symptomatic with PTA (SYM-PTA; n=13; 20±2yrs; 1.8±0.1m; 84±5kg), asymptomatic with PTA (ASYM-PTA; n=15; 21±2yrs; 1.8±0.1m; 82±13kg), and healthy control (CON; n=15; 20±2yrs; 1.8±0.1m; 79±12kg).

MAIN OUTCOME MEASURES

3D biomechanics were collected during double-limb jump-landing. Kinematic (knee flexion angle (KF)) and kinetic (vertical ground reaction force (VGRF); internal knee extension moment (KEM); patellar tendon force (FPT)) variables were analyzed as continuous waveforms during the stance phase for the involved limb. Mean values were calculated for each 1% of stance, normalized over 202 data points (0-100%), and plotted with 95% confidence intervals. Statistical significance was defined as a lack of 95% CI overlap for ≥ 6 consecutive data points.

RESULTS

SYM-PTA had lesser KF than CON throughout the stance phase. ASYM-PTA had lesser KF than CON in the early and late stance phase. SYM-PTA group had lesser KEM and FPT than CON in early stance, as well as ASYM-PTA in mid-stance.

CONCLUSIONS

Male athletes with SYM-PTA demonstrated a patellar tendon load-avoidance profile compared to ASYM-PTA and CON athletes. ASYM-PTA did not show evidence of overloading compared to CON. Our findings support the need for individualized treatments for athletes with tendinopathy to maximize load-capacity.

TRIAL REGISTRY

ClinicalTrials.gov (#XXX).

Proximal Hamstring Tendinopathy: A Systematic Review of Interventions

BACKGROUND

Proximal hamstring tendinopathy affects athletic and non-athletic populations and is associated with longstanding buttock pain. The condition is common in track and field, long distance running and field-based sports. Management options need to be evaluated to direct appropriate clinical management.

PURPOSE/HYPOTHESIS

To evaluate surgical and non-surgical interventions used in managing proximal hamstring tendinopathy.

STUDY DESIGN

Systematic review.

METHODS

Electronic databases were searched to January 2019. Studies (all designs) investigating interventions for people with proximal hamstring tendinopathy were eligible. Outcomes included symptoms, physical function, quality of life and adverse events. Studies were screened for risk of bias. Reporting quality was assessed using the Cochrane Risk of Bias Tool (Randomized Controlled Trials [RCT]) and the Joanna Briggs Institute Checklist (Case Series). Effect sizes (Standard mean difference or Standard paired difference) of 0.2, 0.5 and 0.8 were considered as small, medium and large respectively. Overall quality of evidence was rated according to GRADE guidelines.

RESULTS

Twelve studies (2 RCTs and 10 case series) were included (n=424; males 229). RCTs examined the following interventions: platelet-rich plasma injection (n=1), autologous whole-blood injection (n=1), shockwave therapy (n=1) and multi-modal intervention (n=1). Case series included evaluation of the following interventions: platelet-rich plasma injection (n=3), surgery (n=4), corticosteroid injection (n=2), multi-modal intervention + platelet-rich plasma injection (n=1). Very low-level evidence found shockwave therapy was more effective than a multi-modal intervention, by a large effect on improving symptoms (-3.22 SMD; 95% CI -4.28, -2.16) and physical function (-2.42 SMD; 95% CI-3.33, -1.50) in the long-term. There was very low-level evidence of no difference between autologous whole-blood injection and platelet-rich plasma injection on physical function (0.17 SMD; 95% CI -0.86, 1.21) to (0.24 SMD; 95% CI -0.76, 1.24) and quality of life (-0.04 SMD; 95%CI -1.05, 0.97) in the medium-term. There was very low-quality evidence that surgery resulted in a large reduction in symptoms (-1.89 SPD; 95% CI -2.36, -1.41) to (-6.02 SPD; 95% CI -8.10, -3.94) and physical function (-4.08 SPD; 95%CI -5.53, -2.63) in the long-term.

CONCLUSIONS

There is insufficient evidence to recommend any one intervention over another. A pragmatic approach would be to initially trial approaches proven successful in other tendinopathies.

LEVEL OF EVIDENCE

Level 2a.

Contralateral mechanical hyperalgesia and altered pain modulation in men who have unilateral insertional Achilles tendinopathy: A cross-sectional study

OBJECTIVE

The primary aim was to assess whether men who have insertional Achilles tendinopathy (IAT) have altered endogenous modulation of painful stimuli, and secondarily if they exhibit unaffected-side pressure hyperalgesia.

METHODS

Using a cross-sectional design, we recruited men with unilateral IAT and asymptomatic men as controls matched for age, body mass index (BMI) and activity history (participation in running, lower limb loading sport or sedentary). We collected pressure pain threshold (PPT) at the asymptomatic side Achilles tendon insertion for cases, and dominant side Achilles tendon insertion for controls. We compared PPT between groups before and after immersion of the hand in painful cold water.

RESULTS

Twenty men with unilateral IAT (45.4 years [SD 10.02], BMI 29.09 [SD 4.61], 60% sedentary) and 34 men without symptoms (43.2 years [SD 8.78], BMI 27.59 [SD 3.18], 50% sedentary) participated. An interaction effect was found for group x time (F (1,50) = 7.67, p = 0.008), with PPT increase after cold water immersion being 1.20 (95%CI 0.25 to 2.15) Kg greater in the control group (1.44 Kg [SD 1.79]) compared to IAT unaffected side (0.24 Kg [SD 1.47]). Before cold water immersion, PPT was 4.77 (CI 3.22 to 6.31; p < 0.001) Kg greater in the control group.

DISCUSSION

This study provides evidence men with IAT have altered endogenous modulation of a painful stimulus, and display pressure hyperalgesia at their unaffected side compared to men without symptoms. These findings infer alterations to pain processing in men with IAT, suggesting nociplastic mechanism(s) may contribute to pain.

Autoregulated and individualised resistance training versus predetermined and standardised resistance training in tendinopathy: A systematic review protocol

REVIEW OBJECTIVE

To synthesise the best available evidence on the effectiveness of interventions that have used autoregulated and individualised resistance training versus predetermined and standardised resistance training in treating any tendinopathy.

INTRODUCTION

Recent evidence suggests that individualised exercise may be more effective than standardised exercise for musculoskeletal disorders such as tendinopathy. However, no systematic reviews have been conducted on the topic and optimal treatment protocols and clinical recommendations are lacking.

INCLUSION CRITERIA

Randomised controlled trials assessing the effectiveness of autoregulated and individualised resistance training versus predetermined and standardised resistance training for tendinopathy in adults will be included.

METHODS

The authors will search for a wide range of sources to find both published and unpublished studies via EBSCOhost, including, but not limited to, MEDLINE, SPORTDiscus, CINAHL, Cochrane Central Register of Controlled Trials and Allied and Complementary Medicine Database. Studies published in a language other than English will only be considered if a translation is available. The Joanna Briggs Institute systematic review methodology will be followed when conducting the review. Data synthesis will be conducted using meta-analysis or narrative synthesis, where appropriate.

Assessment of Mitochondrial Dysfunction in a Murine Model of Supraspinatus Tendinopathy

BACKGROUND

The purpose of this study was to assess mitochondrial dysfunction in a murine model of supraspinatus tendinopathy.

METHODS

Eighty-four mice (168 limbs) were included in the study. Supraspinatus tendinopathy was induced by inserting a microsurgical clip in the subacromial space of 63 mice bilaterally (126 limbs). Forty-two of these limbs were harvested at 4 weeks postoperatively, 42 underwent clip removal at 4 weeks after the initial procedure and were harvested at 2 weeks, and 42 underwent clip removal at 4 weeks and were harvested at 4 weeks. Forty-two limbs in the remaining 21 mice did not undergo surgical intervention and were utilized as the control group. Outcomes included biomechanical, histological, gene expression, superoxide dismutase (SOD) activity, and transmission electron microscopy (TEM) analyses.

RESULTS

Radiographs confirmed stable clip position in the subacromial space at 4 weeks. Biomechanical testing demonstrated a 60% decrease in failure force of the supraspinatus tendons at 4 weeks compared with the control group. The failure force gradually increased at 2 and 4 weeks after clip removal. Histological analysis demonstrated inflammation surrounding the tendon with higher modified Bonar scores at 4 weeks after clip placement followed by gradual improvement following clip removal. The expression of mitochondrial-related genes was decreased at 4 weeks after clip placement and then significantly increased after clip removal. SOD activity decreased significantly at 4 weeks after clip placement but increased following clip removal. TEM images demonstrated alterations in morphology and the number of mitochondria and cristae at 4 weeks after clip placement with improvement after clip removal.

CONCLUSIONS

Mitochondrial dysfunction appears to be associated with the development of tendinopathy.

CLINICAL RELEVANCE

Mitochondrial protection may offer a potential strategy for delaying the development of tendinopathy and promoting tendon healing.