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Review

Conservative Treatments for Patellar Tendinopathy: A Review of Recent High-Quality Evidence

by
Jerneja Čobec
1 and
Žiga Kozinc
1,2,*
1
Faculty of Health Sciences, University of Primorska, Polje 42, 6310 Izola, Slovenia
2
Andrej Marušič Institute, University of Primorska, Muzejski trg 2, 6000 Koper, Slovenia
*
Author to whom correspondence should be addressed.
BioMed 2022, 2(4), 359-375; https://doi.org/10.3390/biomed2040028
Submission received: 1 September 2022 / Revised: 26 September 2022 / Accepted: 28 September 2022 / Published: 29 September 2022
Versions Notes

Abstract

:
Patellar tendinopathy is a common injury characterized by progressive activity-related anterior knee pain. It is highly prevalent in sports which involve jumping and changing direction. The aim of this paper is to review recent high-quality evidence regarding the effectiveness of physical therapy in the treatment of patellar tendinopathy. Randomized controlled trials (n = 22) researching the effects of exercise therapy, physical agents, and soft tissue techniques were included. The results show that exercise therapy is the most effective. While eccentric exercise is commonly used, very promising progressive tendon-loading exercise therapy programs are recently emerging. Extracorporeal shock wave therapy, dry needling, and orthoses are no more effective than eccentric exercises or placebo groups. Isometric and isotonic exercise, patellar strap, sports tape, and kinesiotaping have a short-term effect on functional improvement and pain reduction, while progressive tendon-loading exercise, dry needling, platelet-rich plasma, and extracorporeal shock wave therapy have long-term effects.

1. Introduction

While all tendons in the human body are subjected to injury and overuse [1], patellar tendinopathy (PT), also known as jumper’s knee, is one of the most common lower limb tendinopathies [2]. It is an overuse injury of the patellar tendon and reflects in anterior knee pain. Pain occurs at the proximal attachment of the patellar tendon at the patellar apex. PT is very common among active young individuals aged between 15 and 30 years, often among basketball, volleyball, and soccer players [3,4]. In one study on elite athletes, point prevalence has been reported to be as high as 14.2% (87 of 613) [3]. In adolescent athletes, PT is three times more common (5.8%) than Achilles tendinopathy (1.8%) [5]. A recent study reported the prevalence ranging from 14 to 73% in different track and field athlete subgroups; however, the sample sizes were very small [6]. In addition, PT is also prevalent in the general population, with 28.3% prevalence reported within a cohort of 50–79-year-old participants with no history of knee injury [7].
Jumping, landing, cutting, and pivoting require the patellar tendon to repeatedly store and release energy [3,8,9]. Excessive repetitions of such activities or insufficient time between loadings lead to mechanical changes in the tendon, which appear to be a key driver for developing the symptoms [10,11,12,13]. An important extrinsic factor is also a change in the type of playing surface, with symptoms occurring most often among athletes playing on hard surfaces [14,15]. Van Der Worp et al. [16] reported that weight, body mass index, waist-to-hip ratio, leg-length difference, the arch height of the foot, vertical jump performance, hamstring and quadriceps flexibility, and quadriceps strength are intrinsic risk factors for PT. Patella alta and larger infrapatellar fat pad are also risk factors in men [17,18]. The incidence of PT is two to four times higher in boys and men compared to women due to the influence of estrogen [19,20].
Cook and Purdam [21] define the three stages continuum of tendon pathology. Increasing or decreasing load is the primary stimulus that defines the stage of the continuum. Reducing load may allow the tendon to return to a previous structural and capacity level within the continuum [10]. The reactive stage is a non-inflammatory response of tenocytes and matrix due to acute overload or direct blow directly to the patellar tendon [21]. The number of tenocytes and proteoglycans that bound water increases [22]. The reactive stage is a short-term adaptation of the tendon to overload [21]. If the overload is sufficiently reduced or if there is sufficient time between loading sessions, the tendon can revert to the normal stage. Clinically, it is observed as swelling and pain localized at the patellar tendon. Tendon dysrepair is an attempt at tendon healing. There is an increase in the number of cells, reulting in the increased production of proteoglycans. This causes separation of the collagen and matrix disorganization [21]. Instead of collagen type I, disorganized collagen type III is produced [23]. With load management, this stage is still reversible [24]. In the degenerative stage, cell apoptosis occurs [25]. Matrix and vascular changes are extensive, and due to that, there is little chance for reversibility of pathological changes [21]. Individuals have recurrent bouts of pain that resolve and return with load management. Extensive degenerative tendon changes or high load can lead to tendon rupture [26]. Around 97% of ruptured tendons already had previous degenerative changes [27]. A reader interested in details of PT pathogenesis is directed to other papers [28].
PT is one of many pathologies that reflects anterior knee pain [29]. Specific clinical features are pain localized to the inferior pole of the patella and load-related pain on the knee extensors [15,30]. Tendon pain occurs immediately upon loading and stops when the load is removed, very rarely in the resting state [31]. PT also has other symptoms, such as pain with prolonged sitting, squatting, and using stairs. These symptoms can also be present in other pathologies-patellofemoral pain, Osgood–Schlatter syndrome, infrapatellar fat pad syndrome, plica, infrapatellar bursitis, or Sinding-Larsen–Johansson syndrome [17,29,32,33,34].
A basic check-up requires a thorough examination of the lower limb to identify any potential deficits in the hip, knee, ankle, and foot [15]. These deficits affect the coordinated movement of the lower limb kinetic chain and prevent the optimal development of muscle strength and load bearing [30]. Reduced strength in the gluteus maximus, quadriceps, and calf is often present in PT [30,35]. It is important to quantify the patient’s level of dysfunction and pain. VISA-P score (the Victorian institute of sport assessment-patella) is a 100-point scale that assesses symptoms, simple tests of function, and the ability for sports activities [36]. Diagnostic imaging does not confirm PT, as pathological tendon changes may be present in asymptomatic individuals [12]. Symptoms often improve without corresponding structural changes on magnetic resonance or ultrasound imaging [37].
Although there is a wide range of techniques for the treatment of PT, a review of the literature reveals the inconsistency of physical therapy. Furthermore, the authors are not unanimous about the effectiveness of the individual method and the combination of several techniques. The aim of this review is to collect and analyze the latest evidence on the effectiveness of physical therapy for the treatment of PT. Studies about exercise therapy, physical agents, and soft tissue techniques were included.

2. Materials and Methods

A systematic search was performed in March 2022 in the PubMed database and the reference lists of relevant reviews as well as the papers already included during the process. We also performed a search in Google Scholar and ResearchGate databases. Randomized controlled trials from the last twelve years were included. The database was searched with the following combination of search keywords: (patellar tendinopathy) and (treatment OR rehabilitation). To define the research questions, the PICOS strategy was used, as shown in Table 1. Studies comparing medical and surgical treatments and studies on pathologies other than PT were excluded.

3. Results

After screening 415 hits in the PubMed database and the examination of the reference lists of the included articles and the available systematic reviews, 62 studies were initially included. After the abstract examination, we excluded 22 studies, and after the full-text examination, we excluded three studies. Two more studies were included after reviewing the reference lists of relevant reviews. From the final pool of included studies, 14 studies were used to compare the effectiveness of physical therapy. Seven studies investigated the efficacy of exercise therapy (isometric, isotonic, progressive exercise), five physical agents (extracorporeal shock wave therapy), two soft tissue techniques (dry needling), two orthoses, and other related interventions (kinesiotaping, patellar strap, sports tape), and two platelet-rich plasma. A summary of the characteristics of the selected studies is available in Table 2.

4. Discussion

PT is a common lower limb tendinopathy, but despite a wide range of methods, there is no consensus regarding physical therapy. The aim of this review was to investigate and compare the effectiveness of exercise therapy, physical agents, platelet-rich plasma (PRP), and soft tissue techniques for the treatment of PT. The results show that exercise therapy is the most effective, while other interventions may serve as useful and beneficial adjunct therapies.

4.1. Eccentric Exercise

Eccentric exercise involves active muscle lengthening and is characterized by a greater load compared to isometric and concentric exercises [54]. Eccentric exercise improves the mechanical properties of the tendon and consequently increases its load-bearing capacity [21]. van Ark et al. [43] found no tendon structural improvements with isometric and isotonic exercise after 4 weeks. Older studies suggest that the most effective exercise is the eccentric decline squat with the heels raised more than 15° [55,56]. Dimitrios et al. [2] found that eccentric exercise combined with static stretching of the quadriceps femoris and hamstring muscles at least 30 s before and after exercise had a greater pain reducing and function improving effect than eccentric exercise alone. Load management is one of the most important methods of treating PT. It affects matrix reorganization, collagen synthesis, reduced tenocyte activity, and reduced pain perception [57,58,59]. Higher knee extension load improves muscle strength and nerve activation [60]. Kongsgaard et al. [61] reported that heavy, slow resistance training from 15 to 6 repetition maximum (RM) affects the synthesis of new collagen networks and thus has a long-term impact on clinical improvement. In this systematic review, Agergaard et al. [41] found no difference between high (90% 1 RM) and moderate load magnitude (55% 1 RM) for the clinical outcome.

4.2. Other Exercise Types

Studies on isometric, isotonic, and progressive tendon-loading exercise therapy were also included. A significant progression was made in progressive tendon-loading exercise therapy, which improved the VISA-P score improved by 24 points [42]. With progressive tendon-loading exercise therapy, the tendon gradually adapts to normal functioning [62]. As described by Scott et al. [58], isometric exercise provides initial stimulation of the muscle and tendon, progressive loading adapts the tendon to the loads, and subsequent eccentric exercise is preparation for sport-specific activities [58]. Rio et al. [44] reported that isometric exercises reduce pain in the early phase of rehabilitation. Isometric exercise with short-duration loads has been shown to be more effective as it is easier to tolerate [38]. Holden et al. [39] reported that the analgesic effect is only seen 45 min after exercise. van Ark et al. [40]. Holden et al. [39] found an equivalent short-term analgesic effect of isometric and isotonic exercise.
In addition to exercise therapy, passive interventions are also used in the treatment of PT, although evidence of their effectiveness is limited [15]. Malliaras et al. [29] contend that the treatment of PT should focus on progressively developing load tolerance of the tendon with exercise and that other modalities are only beneficial as an adjunct to exercise therapy. Rutland et al. [63] agreed and stated that active rest, activity modification, and eccentric exercise are cornerstones of PT management.

4.3. Extracorporeal-Shock Wave Therapy

ESWT is based on mechanical shockwaves that travel through the affected tissue [64]. A shockwave is a special, non-linear type of pressure wave characterized by a short rise time (10 us) [65]. According to Zwerver et al. [48], ESWT is not effective as a solitary treatment during the competitive season. Although ESWT improves clinical outcomes, it is not more effective than eccentric exercise alone [45,46,66]. van der Worp et al. [45] found no difference in effectiveness between focused and radial shockwave therapy. Notable improvements in VISA-P scores were achieved in the study by Lee et al. [47] with low-intensity ESWT once a week in combination with EE. Vetrano et al. [53] showed that three sessions of ESWT were effective in facilitating long-term PT treatment; however, PRP injections were even more effective. Despite a relatively small body of evidence, ESWT is a commonly used intervention for the treatment of tendinopathies in the lower and upper extremities [66,67,68].

4.4. Platelet-Rich Plasma Injections

PRP is a concentrate of platelets and growth factors obtained by centrifugation from a sample of patient’s blood sample [69] and is believed to enhance the tissue healing process. Indeed, increased levels of macrophages and type I and III collagen in tendons treated with PRP have been shown [70]. However, only two studies involving PRP application were included in this review [52,53]. Dragoo et al. [52] found that PRP was more effective for accelerating the treatment of PT than dry needling in the short-term (12 weeks) but not long-term follow-up (26 weeks). In addition, Vetrano et al. [53] reported that PRP injection had a similar effect to ESWT therapy in the short term; however, at one-year follow-up, PRP appeared superior. The superiority of PRP over ESWT was also noted in a recent review [71]. While further high-quality studies are needed, PRP appears as an effective approach to accelerate PT treatment.

4.5. Soft Tissue Techniques

López-Royo et al. [51] also found no significant effect of dry needling compared to EE. On the contrary, dry needling accelerated the improvement of PT symptoms in individuals that did not respond to exercise alone within 6 weeks. Other commonly used soft tissue techniques are fascial manipulation and transverse friction massage [72]. Chaves et al. [73] showed that deep friction massage induces an immediate reduction in pain intensity. Similar effects were demonstrated by Pedrelli et al. [74] using fascial manipulation of the quadriceps muscle. According to their report, manual pressure raises the temperature of the ground substance and allows it to be transformed from a pathologically dense to a physiologically fluid state. The change in density allows the restoration of gliding between the connective-tissue layers and allows the free intrafascial nerve endings to slide within the fascia more freely, which explains the sudden decrease in pain [74].

4.6. Other Treatment Modalities

Orthoses also have an effect on short-term pain reduction. Patellar straps and sports taping also tend to show some benefits. The infrapatellar strap prevents overloading of the patellar tendon at degenerative sites by increasing the angle between the patella and the patellar tendon and decreasing patellar tendon length [75]. An additional study showed the potential of kinesiotaping to reduce pain associated with PT [49].
This systematic review shows that isometric and isotonic exercise, patellar strap, sports tape, and kinesiotaping have a short-term effect on functional improvement and pain reduction, while progressive tendon-loading exercise, PRP, dry needling, and extracorporeal shock wave therapy have potential long-term effects. As a limitation, only studies comparing the effectiveness of movement therapy and one passive method were included in this systematic review. The results show that eccentric is more effective than passive methods. A retrospective chart review by Vander Doelen and Scott [76] showed that a multimodal treatment approach of a combination of dry needling, ESWT, manual, and exercise therapy have short- and long-term effects on functional improvement and pain relief. Despite the positive effects of the combination of methods reported by Vander Doelen and Scott [76], there is no research in this systematic review to support this. The heterogeneity among the included studies is a strong limitation of this systematic review. Included physiotherapeutic methods have different outcome measures, so it was difficult to compare their effectiveness with each other. The studies also differ in terms of the duration of the method, the participants, and the conditions under which they were carried out. Some of the studies were carried out during the competition season, while some participants had to stop training and only do the prescribed therapeutic exercise. Despite the number of studies, there is still no consensus on the most effective method or rehabilitation protocol. Eccentric presents the most evidence of effectiveness, while other passive techniques still need further research.

5. Conclusions

The results of this review show that recent high-quality evidence supports exercise therapy as the most effective for treating PT, and novel progressive tendon-loading exercise therapy programs are appearing as an alternative to eccentric-exercise-only approaches. ESWT, dry needling, and orthoses are no more effective than eccentric exercises or the placebo group. Isometric and isotonic exercise, patellar strap, sports tape, and kinesiotaping have a short-term effect on functional improvement and pain reduction, while progressive tendon-loading exercise, dry needling, PRP, and extracorporeal shock wave therapy have long-term effects. Despite the number of studies, there is still no consensus regarding PT rehabilitation protocol or evidence of the effectiveness of the combination of different physical methods and techniques.

Author Contributions

Conceptualization, J.Č. and Ž.K.; methodology, J.Č.; software, J.Č.; validation, J.Č. and Ž.K.; formal analysis, J.Č.; investigation, J.Č.; resources, J.Č.; data curation, J.Č.; writing—original draft preparation, J.Č.; writing—review and editing, Ž.K.; visualization, Ž.K.; supervision, Ž.K.; project administration, Ž.K. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Not applicable.

Conflicts of Interest

The authors declare no conflict of interest.

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Table
Table 1. PICOS criteria for inclusion and exclusion of studies.
Table 1. PICOS criteria for inclusion and exclusion of studies.
CriteriaInclusion CriteriaExclusion Criteria
PopulationRecreational and professional athletes with clinical diagnosed PTOther pathologies that occur as anterior knee pain
InterventionsExercise therapy, physical agents, and soft tissue techniquesMedical and surgical treatment
ComparatorThe effectiveness of physical therapy methods individually (comparison with control groups) and among themselves (exercise therapy, soft tissue techniques, physical agents, platelet-rich plasma)Effectiveness of physical therapy and surgical or medical treatment
OutcomesReducing pain and improving function/
Study designRandomized controlled trialsStudies that were published before 2010 and non-English studies
PT = patellar tendinopathy.
Table
Table 2. Characteristics of the selected studies.
Table 2. Characteristics of the selected studies.
StudyPurposeParticipantsOutcome MeasuresInterventionResultsConclusion
Pearson et al. (2020)
[38]		To examine the effects of long- and short-duration isometric contraction on patellar tendon pain and tendon adaptation after 4 weeksSixteen basketball and volleyball players from Australian state-level leagues with PT symptoms for at least 3 monthsBorg scale, 100 mm VAS for pain during SLDS and single-leg hop, USLoading at 30° knee flexion; five times per week for 4 weeks. Short-duration contractions: 24 sets, 10 s contractions, 20 s rest, 85% MVC. Long-duration contraction: six sets, 40 s contractions, 80 s rest, 85% MVCSignificant reduction in pain after isometric loading on SLDS by 0.61 (p < 0.01) and hop tests by 0.25 (p = 0.02) There was no significant difference between long- or short-duration isometric loading for either SLDS (p = 0.32) or hop (p = 0.6). Percentage of tendon transverse strain increased after first (p < 0.001; 14%), second (p < 0.001; 17%) and third session (p < 0.001; 22%)Long-(40 s) and short-(10 s) duration isometric contractions are equally effective for immediate relief of pain. Shorter duration loading was better tolerated. Tendon thickness was not significant, but there was an improvement of 22% in both cases
Holden et al. (2020)
[39]		Compare the acute effects of isometric and dynamic resistance exercise on painTwenty active individuals aged 18–40 years diagnosed with PTPain with NRS during SLDS, pressure pain threshold, VISA-P, USIsometric exercises: 60° knee flexion, five repetitions, 45 s contractions, 2 min rest, 70% MVC. Dynamic exercise: 90° ROM, 8 RM, tempo 303, 3 repetitions, 2 min rest In both cases, the pain score was immediately lower post-exercise for an average 0.9 (p = 0.028). There were no significant differences in pain reduction between 45 min post-exercise and baseline (p = 0.089). There was also no difference between isometric and dynamic exercise interventions immediately after the exercise (p = 0.73) or 45 min after the exercise (p = 0.16)Isometric and dynamic exercises have an immediate effect on pain reduction
van Ark et al. (2016)
[40]		To examine if isometric and isotonic exercises relieved pain in competing athletes29 basketball and volleyball players (16–32 years) with PT playing at least three times per weekPain with NRS during SLDS, VISA-P, participation exercises diaryFour exercises per week for 4 weeks. Both groups were matched for a time under tension and rest. Weight increases by 2.5% once a week. Isometric exercises: 5 × 45 s contractions, 60° knee flexion, 80% MVC. Isotonic exercises: single leg knee extension, four sets, eight repetitions, 15 s rest, tempo 304, 80% 8 RMThere was a pain reduction after 4 weeks with isometric exercises from average 6.3 to 4.0 (p = 0.003) and isotonic exercises from 5.5 to 2.0 (p = 0.012). VISA-P score also improved with isometric exercises from average 66.5 to 75.0 (p = 0.003) and isotonic from 69.5 to 79.0 (p = 0.028). There was no significant difference in pain (p = 0.208) and VISA-P (p = 0.965) score change between groupsBoth isometric and isotonic exercise programs can reduce pain and improve function during the sports season
Agergaard et al. (2021)
[41]		Investigate if the load magnitude has long- and short-term effects on clinical outcome and tendon structure44 participants with chronic PTVISA-P, pain with NRS, USMSR: 55% of 1 RM. HSR: 90% of 1 RM. Short-term effects after 12 weeks, long-term after 52 weeksVISA-P score with MSR at the baseline 58.8 ± 4.3, after 12 weeks 70.5 ± 4.4, after 52 weeks 79.7 ± 4.6; VISA-P score with HSR at the baseline 59.9 ± 2.5, after 12 weeks 72.5 ± 2.9, after 52 weeks 82.6 ± 2.5Both HSR and MSR showed equally good short- and long-term effects on tendon function, structure, and clinical outcome
Breda et al. (2021)
[42]		Compare the effectiveness of PTLE with EE in patients with PT76 active individuals and athletes (18–35 years) with clinically diagnosed PT for more than 2 years. Participants are active at least 3 times per weekVISA-P, return to sports rate, subjective participant satisfaction and exercise adherence, pain with VAS during SLDSDuration of 24 weeks; progression to the next stage when VAS score was <3. Experimental group: PTLE; stage 1 (isometric exercises—single leg press or leg extension; 5 × 45 s, 60° knee flexion, 70% MVC, everyday), stage 2 (every first-day isometric exercises from stage 1, every second-day isotonic exercises- single leg press or leg extension, gradually to four sets, six repetitions, full extension and 90° flexion), stage 3 (plyometrics and running-jump squats, box jumps and cutting manoeuvres, gradually to 6 sets, 10 repetitions, single leg performance, every third-day, every first-day isometric, every second-day isotonic exercises), stage 4 (sport-specific exercises, every 2–3 days, 2× per week exercises from stage 1 and 2). Control group: EE; stage 1 (SLDS, 12 weeks, 2× per day, eccentric phase unilateral, concentric bilateral), stage 2 (sport-specific exercises, 2× week exercise from stage 1)After 24 weeks VISA-P score increased by 28 points in PTLE and by 18 points in EE (p = 0.023). With PTLE (43%) participants returned to sport faster than with EE (27%) (p = 0.13). The subjective participant satisfaction (p = 0.54) and exercise adherence (p = 0.33) were not significantly different between groupsPTLE resulted in a significantly better clinical outcome after 24 weeks than EE
van Ark et al. (2018)
[43]		Investigate the effects of a 4-week isometric or isotonic exercises program on tendon structure as quantified by US tissue characterization 29 volleyball and basketball players (16–31 years) with PT playing at least three times per weekUS tissue characterization, pain with NRS during SLDS, VISA-P Four exercises per week for 4 weeks. Both groups were matched for a time under tension and rest. Weight increases by 2.5% once a week. Isometric exercises: 5 × 45 s contractions, 60° knee flexion, 80% MVC, 1 min rest. Isotonic exercises: four sets, eight repetitions, 1 min rest, tempo 304, 80% 8 RM, pain-free ROM between 10–90° knee flexionNo significant change in tendon structure, disorganized structure (p = 0.711), and cross-sectional area of fibrillar structure (p = 0.679) Isometric and isotonic exercise program improve PT symptoms, but the tendon structure did not change after the 4-week exercise program
Rio et al. (2017)
[44]		Compare the immediate analgesic effect of isometric and isotonic exercises in in-season athletes with PT20 volleyball and basketball players over 16 years with PT, playing at least three times per weekPain with NRS during SLDS, VISA-P, a questionnaire about tendon pain and function, participation exercises diaryFour exercises per week for 4 weeks. Both groups were matched for time under tension and rest. Weight increases by 2.5% once a week. Isometric exercises: 5 × 45 s contractions, 1 min rest, 60° knee flexion, 80% MVC. Isotonic exercises: single leg knee extension, four sets, eight repetitions, 1 min rest, tempo 304, 80% 8 RMPain reduction with isometric exercises by 1.8 ± 0.39 and isotonic by 0.9 ± 0.25. The immediate reduction in pain was greater for the isometric group (p < 0.002). Both exercise protocols improved VISA-P score, but there were no significant differences between groups (p = 0.99). The isotonic group score change was 10.5 points, and the isometric group change was 11.5 pointsBoth protocols appear efficacious for in-season athletes to reduce pain. However, isometric contractions demonstrated significantly greater immediate analgesia throughout the 4-week trial. Greater analgesia may increase the ability to load or perform
van der Worp et al. (2014)
[45]		Compare the effectiveness of focused ESWT and radial ESWT for treating PT43 participants (18–50 years) with PT for over 3 months, VISA-P score < 80VISA-P, pain with VAS during SLDS, sports and daily living activities, subjective rating of improvement, participation exercises diaryThree sessions with a 1-week interval for 14 weeks. Both ESWT therapies were performed in the last two weeks in combination with an eccentric SLDS (3 sets, 15 repetitions, 5× per week, pain < 4), ESWT was performed in the most painful area. Focused ESWT: frequency 4 Hz, 2000 pulses, an energy density level 0.12 mJ/mm2 or 2.4 bar. Radial ESWT: same as focused group, frequency 8 HzThe VISA-P score improved significantly with both therapies (p < 0.01), with focused ESWT by 15 points and with radial by 9.6 points. There was no difference between radial and focused ESWT treatments in improvement on the VISA-P questionnaire and pain reduction during SLDS, sports, and daily living activitiesNo statistically significant differences in effectiveness between focused and radial ESWT in combination with EE. However, both groups improved after 14 weeks
Thijs et al. (2017)
[46]		Evaluate the effectiveness of combined treatment of focused ESWT and EE compared with placebo ESWT and EE after 24 weeks52 physically active participants with clinically diagnosed PTVISA-P, pain with Likert scoreFocused ESWT: three sessions at 1-week intervals, frequency 4 Hz, 1000 pulses, an energy density level 0.2 mJ/mm2, which was gradually increased during sessions. EV: 2× per day, three sets, 15 repetitions, pain < 4 VISA-P score increased from 54.5 ± 15.4 to 70.9 ± 17.8 for the ESWT group and from 58.9 ± 14.6 to 78.2 ± 15.8 for the placebo groupThe combination of focused ESWT and EE has not been shown to be more effective than EE alone
Lee et al. (2020)
[47]		Investigate the change of mechanical properties and clinical outcome after 12-week SLDS with and without ESWT28 volleyball, basketball, and handball players in-season with PT for over 3 months US, dynamometry, VISA-P, pain with VAS Exercise group: 12-week SLDS performance (squatting down in 2 s, concentric phase was performed bilaterally; pain < 5; 3 sets, 15 repetitions, 2× per day). Combined group: same 12-week SLDS performance, ESWT therapy was delivered once a week for 6 weeks (30° knee flexion, frequency 4 Hz, 1500 impulses, an energy density level 0.08 mJ/mm2)The tendon stiffness reduction for the exercise group from 3544 ± 1820 N/mm to 3108 ± 2031 N/mm and for combined group from 3342 ± 1836 N/mm to 2363 ± 1402 N/mm. Both groups reduce pain after 7 days in the exercise group from 6.6 ± 2.0 to 3.2 ± 2.5 and combined group from 6.7 ± 1.9 to 3.9 ± 1.9. VISA-P score increased from 57.4 ± 8.3 to 77.3 ± 12.6 in the exercise group and from 55.1 ± 12.9 to 72.9 ± 14.3 in the combined group. 12-week EE reduce tendon stiffness, pain, dysfunction, and increase patellar tendon strain. The combination of ESWT and EE was not shown to be more effective than EE alone
Zwerver et al. (2011)
[48]		Determine the effectiveness of ESWT on pain, symptoms, and function in athletes with early symptomatic patellar tendinopathy who are still in training and competition62 volleyball, basketball, and handball players with PT for 3 to 12 monthsVISA-P, pain with VAS during sports, daily living activities, and after SLDS, subjective rating of improvementESWT: three sessions at 1-week intervals for 22 weeks, frequency 4 Hz, 2000 impulses, an energy density level gradually from 0.1 to 0.58 mJ/mm2 according to individual pain tolerance Placebo: same ESWT treatment procedure, an energy density level < 0.03 mJ/mm2, transmission gel was not applied between applicator and tissueVISA-P score improved for the ESWT group from 59.4 ± 11.7 to 11.1 ± 18.6, for placebo group from 62.4 ± 13.4 to 10.4 ± 15.5. No significant differences were found between the ESWT and placebo groups for pain reduction during sports, daily living activities, and after SLDSESWT as a solitary treatment has no benefit over placebo treatment in-season for athletes with symptoms for less than 12 months
Tamura et al. (2020)
[49]		To examine the effects of KT on pain modulation for active individuals with PT during functional activitiesSeven students with PT active at least three times per weekPain with NRS during SLDS, maximal vertical jump test, and isometric knee extensionTests: SLDS (two sets, five repetitions), maximal vertical jump (three repetitions) and submaximal isometric knee extension (3 s). Each test was completed under three conditions: KT (Y strip at 30° knee flexion-I tail stretched to 75–100% tension over the patellar tendon, Y tail with 25–35% tension on the medial thigh), sham KT and no KT. Each season was separated from 3 to 7 daysPain was significantly reduced during the maximum vertical jump test with KT to 3. 38 ± 1.26 compared to no KT to 4. 54 ± 2. 22 (p = 0. 05). There was no difference between the sham and no KT condition (p = 0.392). No significant difference was found between conditions for pain decrease during the single-leg squat test (p = 0.67) or the knee extensor strength test (p = 0.34). Lower jump heights were found under KT condition during the maximum vertical jump test compared to the sham KT (p = 0.000) and no KT conditions (p = 0.008) KT with a tendon corrective strip and muscle facilitative strip was effective for decreasing pain during jump landing but led to decreased maximum jump height
de Vries et al. (2016)
[50]		Investigate the short-term effect of orthosis on patellar tendon pain97 athletes (18–50 years) with PT for over 3 months, VISA-P score < 80Pain with VAS during SLDS, vertical jump and triple hop test, VISA-PDuring the first week, participants were not using orthoses during sports. In the second week were participant divided into four groups: patellar strap, sports tape, placebo, and no orthosisThe pain was reduced by 14 mm with patellar strap and by 11.5 mm with sports tape during SLDS compared to no orthosis condition. The pain score during sports was significantly lower in both weeks. Pain with patellar strap was lower by 7 mm, placebo 66 mm, and sports tape by 5 mm. 80% of participants with patellar strap reported pain decrease, 72% with sports tape, and 56 with placebo. No significant group differences were found in the pain score the next morningPatellar strap and sports tape reduce pain in the short-term but are no more effective than placebo
López-Royo et al. (2021)
[51]		Determine the effect of dry needling or percutaneous needle electrolysis combined with EE and determine which is the most effective for PT48 participants (18–45 years) with PT for at least 3 monthsVISA-P, pain with VAS, US, Short form 36 to measure the quality of lifeDuration 22 weeks. Three groups: dry needling and EE (20° knee flexion, four sessions every 2 weeks over 8 weeks, needle 0.25 × 0.25, 3 needle insertions for 3 s, SLDS 3 sets, 15 repetitions, 2× per day, pain < 5), percutaneous needle electrolysis and EE (same as dry needling, intensity 3 mA) and EE with sham needle There were no significant differences in the VISA-p score among the three groups; however, a total of 66.67% of participants obtained VISA-P score of <15 points. VAS score decreased after 10 weeks with EE (p = 0.01) and percutaneous needle electrolysis (p = 0.02); after 22 weeks, there were no significant differences in mean VAS score between groups (p < 0.05). Dry needling and percutaneous needle electrolysis were not shown to be more effective than EE alone after 10 and 22 weeks
Dragoo et al. (2014) [52]To compare clinical outcomes in PT after a single ultrasound-guided, PRP injection versus DN23 participants (age 35 ± 13 years) with persistent PT symptoms after 6 weeks of eccentric exercise physical therapyVISA-P, pain with VAS, Tegner activity scale, Lysholm knee scoring scale, health-related quality of life (SF-36)Duration 26 weeks. Patients were blinded and received either a single DN or PRP (6 mL) procedure, according to their assigned treatment group. They also followed an eccentric exercise programVISA-P improved more with PRP (p = 0.01) at 12 weeks, but not 26 weeks, while Lysholm score only improved with dry needling. No differences in Tenger activity scores were noted. Both interventions decreased pain (VAS) after 26 weeks to a similar extent (2.4–2.6 points)DN and PRP are both effective in accelerating the treatment of PT. While the latter appears to have a better short-term effect, after 26 weeks, there were no major differences between the treatments
Vetrano et al., 2013 [53]To compare the effectiveness and safety of PRP injections and ESWT in athletes with PT46 participants (18 to 50 years), PT for at least six, and failure of nonoperative treatmentVISA-P, pain with VAS, Jumper’s knee Blazina scoreThe study included 2-, 6-, and 12-month follow-ups. PRP group received 2 autologous PRP injections (6–7 mL) over 2 weeks (1 injection per week for 2 weeks) under ultrasound guidance. ESWT group received three sessions, wherein 2.400 impulses were administered with an energy flux density of 0.17 to 0.25 mJ/mmVISA-P score was similar in both groups at baseline and after two months but showed larger improvements for PRP after 6 and 12 months (p = 0.014–0.026). The same pattern was observed for VAS, as PRP injection group showed better results than ESWT group at 6-month (mean 2.4 vs. 3.9; p = 0.028) and 12-month (mean 1.5 vs 3.2; p = 0.009). PRP also showed better treatment success and satisfaction at 12-month follow-upBoth PRP injections and ESWT are effective treatments for athletes with PT. While they show comparable effects in the short term, the PRP group improved more at 6 and 12 months of follow-up
Legend: MVC = maximum voluntary contraction; VAS = visual analogue scale; SLDS = single-leg decline squat; US = ultrasound; ROM = range of motion; RM = repetition maximum; ESWT = extracorporeal shock wave therapy; VISA-P = the victorian institute of sport assessment-patella; PT = patellar tendinopathy; NRS = numeric rating scale; KT = kinesio tape; EE = eccentric exercise; HSR = heavy slow resistance (90% of 1 RM); MSR = moderate slow resistance (55% of 1 RM), PTLE = progressive tendon loading exercise; DN = dry needling; PRP = platelet-rich plasma.
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Čobec, J.; Kozinc, Ž. Conservative Treatments for Patellar Tendinopathy: A Review of Recent High-Quality Evidence. BioMed 2022, 2, 359-375. https://doi.org/10.3390/biomed2040028

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Čobec J, Kozinc Ž. Conservative Treatments for Patellar Tendinopathy: A Review of Recent High-Quality Evidence. BioMed. 2022; 2(4):359-375. https://doi.org/10.3390/biomed2040028

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Čobec, Jerneja, and Žiga Kozinc. 2022. "Conservative Treatments for Patellar Tendinopathy: A Review of Recent High-Quality Evidence" BioMed 2, no. 4: 359-375. https://doi.org/10.3390/biomed2040028

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