Eccentric Exercise Protocols for Patella Tendinopathy: Should we Really be Withdrawing Athletes from Sport? A Systematic Review

Patellar tendinopathy: an overview of prevalence, risk factors, screening, diagnosis, treatment and prevention

Patellar tendinopathy (PT), or jumper's knee, is an overuse injury that occurs in professional, as well as recreational, athletes. This condition is a noncontact injury, typically characterized by gradually increasing pain in the patellar tendon. It is prevalent in participants of several sports, but it occurs mostly in jumping sports. The diagnosis of PT is primarily clinical; however, imaging techniques can be useful as well. Risk factors differ between sexes, playing conditions, the kind of sport, playing level and personal characteristics. Screening is an essential tool to assess PT. This condition affects athletic performance and often persists for years. The use of preventative methods is imperative because of the persistence of this condition, especially in elite athletes who sometimes end their career after long and failed treatments. There are a wide variety of treatment and rehabilitation options available, the majority of which are non-operative, such as eccentric exercises, cryotherapy, platelet-rich plasma (PRP) injections, and anti-inflammatory strategies. If conservative treatment fails, surgery is the next most preferable step. Even though there are many surgical treatment methods, there is no clear evidence on what is the most effective approach to address PT. Taking this into consideration, as well as the extent of this clinical entity, novel therapeutic techniques, as well as screening and prevention methods, are expected to emerge in the near future.

Exercise therapy for tendinopathy: a mixed-methods evidence synthesis exploring feasibility, acceptability and effectiveness

Background

Tendinopathy is a common, painful and functionally limiting condition, primarily managed conservatively using exercise therapy.

Review questions

(i) What exercise interventions have been reported in the literature for which tendinopathies? (ii) What outcomes have been reported in studies investigating exercise interventions for tendinopathy? (iii) Which exercise interventions are most effective across all tendinopathies? (iv) Does type/location of tendinopathy or other specific covariates affect which are the most effective exercise therapies? (v) How feasible and acceptable are exercise interventions for tendinopathies?

Methods

A scoping review mapped exercise interventions for tendinopathies and outcomes reported to date (questions i and ii). Thereafter, two contingent systematic review workstreams were conducted. The first investigated a large number of studies and was split into three efficacy reviews that quantified and compared efficacy across different interventions (question iii), and investigated the influence of a range of potential moderators (question iv). The second was a convergent segregated mixed-method review (question v). Searches for studies published from 1998 were conducted in library databases (n = 9), trial registries (n = 6), grey literature databases (n = 5) and Google Scholar. Scoping review searches were completed on 28 April 2020 with efficacy and mixed-method search updates conducted on 19 January 2021 and 29 March 2021.

Results

Scoping review - 555 included studies identified a range of exercise interventions and outcomes across a range of tendinopathies, most commonly Achilles, patellar, lateral elbow and rotator cuff-related shoulder pain. Strengthening exercise was most common, with flexibility exercise used primarily in the upper limb. Disability was the most common outcome measured in Achilles, patellar and rotator cuff-related shoulder pain; physical function capacity was most common in lateral elbow tendinopathy. Efficacy reviews - 204 studies provided evidence that exercise therapy is safe and beneficial, and that patients are generally satisfied with treatment outcome and perceive the improvement to be substantial. In the context of generally low and very low-quality evidence, results identified that: (1) the shoulder may benefit more from flexibility (effect sizeResistance:Flexibility = 0.18 [95% CrI 0.07 to 0.29]) and proprioception (effect sizeResistance:Proprioception = 0.16 [95% CrI -1.8 to 0.32]); (2) when performing strengthening exercise it may be most beneficial to combine concentric and eccentric modes (effect sizeEccentricOnly:Concentric+Eccentric = 0.48 [95% CrI -0.13 to 1.1]; and (3) exercise may be most beneficial when combined with another conservative modality (e.g. injection or electro-therapy increasing effect size by ≈0.1 to 0.3). Mixed-method review - 94 studies (11 qualitative) provided evidence that exercise interventions for tendinopathy can largely be considered feasible and acceptable, and that several important factors should be considered when prescribing exercise for tendinopathy, including an awareness of potential barriers to and facilitators of engaging with exercise, patients' and providers' prior experience and beliefs, and the importance of patient education, self-management and the patient-healthcare professional relationship.

Limitations

Despite a large body of literature on exercise for tendinopathy, there are methodological and reporting limitations that influenced the recommendations that could be made.

Conclusion

The findings provide some support for the use of exercise combined with another conservative modality; flexibility and proprioception exercise for the shoulder; and a combination of eccentric and concentric strengthening exercise across tendinopathies. However, the findings must be interpreted within the context of the quality of the available evidence.

Future work

There is an urgent need for high-quality efficacy, effectiveness, cost-effectiveness and qualitative research that is adequately reported, using common terminology, definitions and outcomes.

Study registration

This project is registered as DOI: 10.11124/JBIES-20-00175 (scoping review); PROSPERO CRD 42020168187 (efficacy reviews); https://osf.io/preprints/sportrxiv/y7sk6/ (efficacy review 1); https://osf.io/preprints/sportrxiv/eyxgk/ (efficacy review 2); https://osf.io/preprints/sportrxiv/mx5pv/ (efficacy review 3); PROSPERO CRD42020164641 (mixed-method review).

Funding

This project was funded by the National Institute for Health and Care Research (NIHR) HTA programme and will be published in full in HTA Journal; Vol. 27, No. 24. See the NIHR Journals Library website for further project information.

Load progression criteria in exercise programmes in lower limb tendinopathy: a systematic review

OBJECTIVE

The objective of this study is to summarise and analyse the current literature about what progression criteria are applied in loading exercise programmes in lower limb tendinopathies and their evidence and effectiveness.

DESIGN

Systematic review.

METHODS

PubMed, Embase, Scopus and PEDro were searched from inception to 24 September 2020. The inclusion criteria were randomised controlled trials that included patients with midportion Achilles, patellar or gluteal tendinopathy; assessed function, pain or performance; included at least one group where progressive physical exercise was administered as monotherapy; included at least a control group. We excluded studies that included subjects with previous tendon surgical treatment; studies with control group that conducted a supplemented modality of the exercise performed in the intervention group. A narrative synthesis was conducted. Cohen's d and the percentage of change of main clinical and performance outcomes were obtained. Methodological quality was assessed using the PEDro scale.

RESULTS

Thirty studies that described progression criteria were included. Six types of criteria grouped in two categories were identified and included in a new classification proposal: pain as a primary criterion (evoking and avoid-pain based), and pain and symptom control as a secondary criterion (conditioning stages, fatigue-based, subjective perception and temporary linear increase). Most of the studies applied a pain-based criterion. Criteria based on conditioning stages were also commonly applied. Other criteria such as fatigue, a temporary linear increase, or the subjective perception of the patient's abilities were occasionally applied.

CONCLUSIONS

There is a predominant use of pain-based criteria, but the utilisation of these criteria is not supported by strong evidence. This review evidences the need for studies that compare the same exercise programme using different progression criteria. A new classification of the existing progression criteria is proposed based on the use of pain as the primary or secondary criterion.

PROSPERO REGISTRATION NUMBER

CRD42018110997.

Pathogenesis and Development of Patellar Tendon Fibrosis in a Rabbit Overuse Model

BACKGROUND

The pathogenesis of patellar tendon fibrosis caused by overuse remains unclear. In an effort to further investigate effective treatments for patellar tendon fibrosis attributed to overuse, it is necessary to construct a reliable animal model.

PURPOSE

A rabbit patellar tendon fibrosis model was developed with the use of electrical stimulation to induce jumping. The pathogenesis and development of patellar tendon fibrosis were subsequently investigated with this model.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 32 New Zealand White rabbits were randomly divided into a jumping group and a control group. Rabbits in the control group did not receive any treatment, while those in the jumping group jumped 150 times daily, 5 days per week. At 2, 4, 6, and 8 weeks after the initiation of treatment, the patellar tendons of 4 rabbits from each group were harvested and subjected to hematoxylin and eosin staining, immunohistochemical staining, and real-time polymerase chain reaction. The influence of jumping training on the expressions of histology- and fibrosis-related factors in the patellar tendon was assessed.

RESULTS

The histological changes of patellar tendon fibrosis in the jumping group were most pronounced at 4 weeks. When compared with the control group at corresponding time points, the mRNA and protein expressions of TGF-β1, CTGF, COL-I, and COL-III were upregulated significantly in the patellar tendon after jumping training for 4 weeks (P < .05). Intragroup comparison at different time points indicated that the mRNA and protein expressions of TGF-β1, COL-I, and COL-III were the highest at 4 weeks in the jumping group (P < .01).

CONCLUSION

It was found that patellar tendon fibrosis occurred because of overuse and the peak changes occurred at 4 weeks. Jumping load increased the secretions of TGF-β1 and Smad3 in the patellar tendon, with CTGF upregulation and higher synthesis of COL-I and COL-III, which were considered the pathogenesis of fibrosis.

CLINICAL RELEVANCE

This study simulated the effects of jumping load on tendon fibrosis at different time points. Moreover, the time course relationship between jumping training and patellar tendon fibrosis in the rabbit model was determined, which provided a new animal model for the study of patellar tendon fibrosis.

Proposing a Patellar Tendinopathy Screening tool following a systematic review

BACKGROUND

Patellar tendinopathy (PT) is an overuse injury of the knee. The mechanism of injury is associated with repetitive stress on the patellar tendon of the knee as a result of explosive movement. Patellar tendinopathy is prevalent in all populations and is associated with intrinsic and extrinsic risk factors.

OBJECTIVES

Primarily, the objective was to report on the intrinsic and extrinsic risk factors for PT, entailing a systematic review of the literature; the secondary objective was to use these risk factors to compile a proposed PT screening tool from the review and standard outcome measures.

METHOD

A systematic review was undertaken according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Elimination criteria of the articles included duplicates, titles, abstracts and methodological quality. The evidence was collected, characterised with regard to the intrinsic and extrinsic risk factors and summarised descriptively.

RESULTS

The search yielded 157 feasible articles prior to commencement of article elimination. Six articles were included with a mean methodological quality score of 69%. Eight intrinsic and five extrinsic risk factors were identified. These identified risk factors are all relevant to the pathology and formed the basis for a proposed PT screening tool. The Victorian Institute of Sports Assessment for Patellar Tendinopathy Questionnaire, Visual Analog Scale and the Pain Provocation Test are also included in the proposed test.

CONCLUSION

Intrinsic and extrinsic risk factors for PT were identified, and consequently, the proposed PT screening tool was formulated for possible future testing in appropriate studies.

CLINICAL IMPLICATIONS

Prevention of PT through intrinsic and extrinsic risk factor identification, and implementation in the clinical setup as a possible outcome measurement tool with which to verify functional improvement in PT rehabilitation.

Mechanical loading modulates heterotopic ossification in calcific tendinopathy through the mTORC1 signaling pathway

Excessive mechanical loading is a major factor affecting heterotopic ossification (HO), which is a major pathological alteration in calcific tendinopathy. However, physical therapies with mechanical loading as the functional element have exhibited promising results in the treatment of calcific tendinopathy. The dual effects that mechanical loading may have on the pathogenesis and rehabilitation of calcified tendinopathy remain unclear. The present study was designed to investigate the effects of mechanical loading on HO in calcific tendinopathy. In the present study, a tendon cell in vitro stretch model and an Achilles tenotomy rat model were used to simulate different elongation mechanical loading scenarios in order to investigate the effects of mechanical loading on HO of the tendon. In addition, rapamycin, a selective mammalian target of rapamycin complex-1 (mTORC1) signaling pathway inhibitor, was employed to determine whether mechanical loading modulates heterotopic ossification in calcific tendinopathy through the mTORC1 signaling pathway. The data indicate that mechanical loading modulated HO of the tendon through the mTORC1 signaling pathway, and that low elongation mechanical loading attenuated HO, while high elongation mechanical loading accelerated HO in vivo. This study may improve the understanding of the effect of physical therapies used to treat calcific tendinopathy, so as to guide clinical treatment more effectively. Furthermore, rapamycin may be a potential drug for the treatment of calcific tendinopathy.

CURRENT CONCEPTS IN THE TREATMENT OF PATELLAR TENDINOPATHY

Patellar tendon pain is a significant problem in athletes who participate in jumping and running sports and can interfere with athletic participation. This clinical commentary reviews patellar tendon anatomy and histopathology, the language used to describe patellar tendon pathology, risk factors for patellar tendinopathy and common interventions used to address patellar tendon pain. Evidence is presented to guide clinicians in their decision-making regarding the treatment of athletes with patellar tendon pain.

LEVEL OF EVIDENCE

5.

Physical therapists' role in prevention and management of patellar tendinopathy injuries in youth, collegiate, and middle-aged indoor volleyball athletes

Patellar tendinopathy is highly prevalent in all ages and skill levels of volleyball athletes. To illustrate this, we discuss the clinical, biomechanical, and ultrasound imaging presentation and the intervention strategies of three volleyball athletes at different stages of their athletic career: youth, middle-aged, and collegiate. We present our examination strategies and interpret the data collected, including visual movement analysis and dynamics, relating these findings to the probable causes of their pain and dysfunction. Using the framework of the EdUReP concept, incorporating Education, Unloading, Reloading, and Prevention, we propose intervention strategies that target each athlete's specific issues in terms of education, rehabilitation, training, and return to sport. This framework can be generalized to manage patellar tendinopathy in other sports requiring jumping, from youth to middle age, and from recreational to elite competitive levels.

Region-specific tendon properties and patellar tendinopathy: a wider understanding

Patellar tendinopathy is a common painful musculoskeletal disorder with a very high prevalence in the athletic population that can severely limit or even end an athletic career. To date, the underlying pathophysiology leading to the condition remains poorly understood, although reports suggesting that patellar tendinopathy most frequently concerns the proximal posterior region of the tendon has prompted some researchers to examine region-specific tendon properties for a better understanding of the etiology and potential risk factors associated with the condition. However, to date, research concerning the in vivo region-specific tendon properties in relation to patellar tendinopathy is very scarce, perhaps due to the lack of validated techniques that can determine such properties in vivo. In recent years, a technique has been developed involving an automated tendon-tracking program that appears to be very useful in the determination of region-specific tendon properties in vivo. In terms of regional variations in tendon properties, previous research has demonstrated differences in structural, mechanical, and biochemical properties between the discrete regions of the patellar tendon, but the extent to which these regional variations contribute to patellar tendinopathy remains elusive. In addition, with respect to treatment strategies for patellar tendinopathy, previous research has utilized a wide range of interventions, but the use of eccentric exercise (EE) and/or heavy-slow resistance (HSR) training appear to be most promising. However, the optimal program design variables of EE and HSR training that induce the most favorable effects are yet to be determined. This review article provides a detailed discussion of all of the above to allow a better understanding of the etiology and potential risk factors associated with the condition as well as the most effective treatment strategies. First, a comprehensive literature review is provided with respect to region-specific structural, mechanical, and biochemical properties, in association with patellar tendinopathy. Second, the automated tendon-tracking methodology is outlined to assist future researchers in the determination of region-specific tendon properties. Finally, potential treatment strategies are discussed, particularly with regards to the use of EE and HSR training for the management of patellar tendinopathy.

The role of eccentric exercise in sport injuries rehabilitation

INTRODUCTION

Sports injuries frequently involve tendons, muscles and ligaments. The variable outcome of surgery and medical treatment support early functional treatments. Eccentric exercise (EE) showed effectiveness in the management of Achilles tendinopathy (AT), patellar tendinopathy (PT) and lateral epicondyle tendinopathy (LET). Preliminary results of EE in other tendinopathies and sports injuries suggest its wide prescription in the sport rehabilitation field.

SOURCES OF DATA

A comprehensive search of PubMed, Web of Science, the Cochrane Collaboration Database, Physiotherapy Evidence Database (PEDro), Evidence Based Medicine (EBM) Search review, National Guidelines, Scopus and Google Scholar was performed using keywords such as 'eccentric exercise', 'sports injuries rehabilitation', 'tendinopathy', 'hamstrings strain' 'adductor injuries' and 'ACL reconstruction rehabilitation'.

AREAS OF AGREEMENT

EE, alone or associated with other therapies, represents a feasible, cost-effective and successful tool in the treatment of well-known targets and might be promising in shoulder tendinopathy, adductor-related groin pain, hamstring strains, and ACL rehabilitation.

AREA OF CONTROVERSY

The lack of standardization of protocols, the variable amount, quality and follow-up of studies, the different anatomy and pathophysiology of the therapeutic targets limit the evidence of applicability of EE to sports injuries.

GROWING POINTS

The role of pathology and biomechanics in the response to EE should be further investigated.

AREAS TIMELY FOR DEVELOPING RESEARCH

New randomized controlled trials should test the effectiveness of standardized EE regimens to various sites of sports injuries.

A multidisciplinary approach including the use of platelet-rich plasma to treat an elite athlete with patellar tendinopathy - a case report

OBJECTIVE

Patellar tendinopathy affects a substantial proportion of athletes involved in jumping or kicking activities. Platelet rich plasma (PRP) injections may be a promising treatment used in conjunction with common traditional therapies.

CLINICAL FEATURES

Patellar tendinopathy is often the result of repetitive or excessive overload on the patellar tendon. Activity modification, cryotherapy, eccentric exercises, shockwave therapy, and PRP have been indicated as treatment options during various stages of this condition.

INTERVENTION AND OUTCOME

A 23 year old female, elite track and field athlete was managed for patellar tendinopathy with a combination of traditional therapeutic interventions as well as a PRP injection. This athlete returned to pre-injury level of competition six months post-injection.

CONCLUSION

Emerging literature on PRP appears to be promising for patellar tendinopathy, however, it remains unclear which patients may benefit most and whether the stage of the disorder has an impact on the clinical outcome.

Rehabilitation of tendopathies in human athletes

Tendinopathies, chronic tendon disorders characterized by pain and functional impairment, are a common problem particularly in elite and recreational athletes. There is a high prevalence of Achilles tendinopathy in runners, while patellar tendinopathies, also referred to as jumpers knee, are very common amongst volleyball and basketball players. However, tendinopathies also occur in the sedentary population. The syndrome is associated with a variety of morphological, histopathological, biochemical and molecular changes, such as an increase in tendon cross sectional area, loss of fibre organization and infiltration of blood vessels. It has been shown that exercise or mechanical loading plays a role, which is why overuse is suspected to initiate tendinopathies. The exact mechanisms are still poorly understood, which makes the treatment problematic. A variety of treatment options are available, ranging from non-invasive procedures such as exercise treatment, topical nitroglycerin patches or shock wave therapy, over injections of various substances, such as corticosteroids, platelet-rich plasma or sclerosing agents, to surgical debridement. However, most of the treatment options focus solely on symptom relief, and the evidence for their effectiveness is often poor. The effectiveness of a treatment is furthermore likely to depend on the stage of the tendinapathy. In contrast to many therapies, exercise treatment has been relatively well investigated, has been shown to work in the majority of cases and is considered the gold standard.