Ebonie Rio

The Pain of Tendinopathy: Physiological or Pathophysiological?

Tendon pain remains an enigma. Many clinical features are consistent with tissue disruption—the pain is localised, persistent and specifically associated with tendon loading, whereas others are not—investigations do not always match symptoms and painless tendons can be catastrophically degenerated. As such, the question ‘what causes a tendon to be painful?’ remains unanswered. Without a proper understanding of the mechanism behind tendon pain, it is no surprise that treatments are often ineffective. Tendon pain certainly serves to protect the area—this is a defining characteristic of pain—and there is often a plausible nociceptive contributor. However, the problem of tendon pain is that the relation between pain and evidence of tissue disruption is variable. The investigation into mechanisms for tendon pain should extend beyond local tissue changes and include peripheral and central mechanisms of nociception modulation. This review integrates recent discoveries in diverse fields such as histology, physiology and neuroscience with clinical insight to present a current state of the art in tendon pain. New hypotheses for this condition are proposed, which focus on the potential role of tenocytes, mechanosensitive and chemosensitive receptors, the role of ion channels in nociception and pain and central mechanisms associated with load and threat monitoring.

Isometric exercise induces analgesia and reduces inhibition in patellar tendinopathy

Background Few interventions reduce patellar tendinopathy (PT) pain in the short term. Eccentric exercises are painful and have limited effectiveness during the competitive season. Isometric and isotonic muscle contractions may have an immediate effect on PT pain. Methods This single-blinded, randomised cross-over study compared immediate and 45 min effects following a bout of isometric and isotonic muscle contractions. Outcome measures were PT pain during the single-leg decline squat (SLDS, 0–10), quadriceps strength on maximal voluntary isometric contraction (MVIC), and measures of corticospinal excitability and inhibition. Data were analysed using a split-plot in time-repeated measures analysis of variance (ANOVA). Results 6 volleyball players with PT participated. Condition effects were detected with greater pain relief immediately from isometric contractions: isometric contractions reduced SLDS (mean±SD) from 7.0±2.04 to 0.17±0.41, and isotonic contractions reduced SLDS (mean±SD) from 6.33±2.80 to 3.75±3.28 (p<0.001). Isometric contractions released cortical inhibition (ratio mean±SD) from 27.53%±8.30 to 54.95%±5.47, but isotonic contractions had no significant effect on inhibition (pre 30.26±3.89, post 31.92±4.67; p=0.004). Condition by time analysis showed pain reduction was sustained at 45 min postisometric but not isotonic condition (p<0.001). The mean reduction in pain scores postisometric was 6.8/10 compared with 2.6/10 postisotonic. MVIC increased significantly following the isometric condition by 18.7±7.8%, and was significantly higher than baseline (p<0.001) and isotonic condition (p<0.001), and at 45 min (p<0.001). Conclusions A single resistance training bout of isometric contractions reduced tendon pain immediately for at least 45 min postintervention and increased MVIC. The reduction in pain was paralleled by a reduction in cortical inhibition, providing insight into potential mechanisms. Isometric contractions can be completed without pain for people with PT. The clinical implications are that isometric muscle contractions may be used to reduce pain in people with PT without a reduction in muscle strength.

Revisiting the continuum model of tendon pathology: what is its merit in clinical practice and research?

The pathogenesis of tendinopathy and the primary biological change in the tendon that precipitates pathology have generated several pathoaetiological models in the literature. The continuum model of tendon pathology, proposed in 2009, synthesised clinical and laboratory-based research to guide treatment choices for the clinical presentations of tendinopathy. While the continuum has been cited extensively in the literature, its clinical utility has yet to be fully elucidated. The continuum model proposed a model for staging tendinopathy based on the changes and distribution of disorganisation within the tendon. However, classifying tendinopathy based on structure in what is primarily a pain condition has been challenged. The interplay between structure, pain and function is not yet fully understood, which has partly contributed to the complex clinical picture of tendinopathy. Here we revisit and assess the merit of the continuum model in the context of new evidence. We (1) summarise new evidence in tendinopathy research in the context of the continuum, (2) discuss tendon pain and the relevance of a model based on structure and (3) describe relevant clinical elements (pain, function and structure) to begin to build a better understanding of the condition. Our goal is that the continuum model may help guide targeted treatments and improved patient outcomes.

Patellar Tendinopathy: Clinical Diagnosis, Load Management, and Advice for Challenging Case Presentations

Synopsis The hallmark features of patellar tendinopathy are (1) pain localized to the inferior pole of the patella and (2) load-related pain that increases with the demand on the knee extensors, notably in activities that store and release energy in the patellar tendon. While imaging may assist in differential diagnosis, the diagnosis of patellar tendinopathy remains clinical, as asymptomatic tendon pathology may exist in people who have pain from other anterior knee sources. A thorough examination is required to diagnose patellar tendinopathy and contributing factors. Management of patellar tendinopathy should focus on progressively developing load tolerance of the tendon, the musculoskeletal unit, and the kinetic chain, as well as addressing key biomechanical and other risk factors. Rehabilitation can be slow and sometimes frustrating. This review aims to assist clinicians with key concepts related to examination, diagnosis, and management of patellar tendinopathy. Difficult clinical presentations (eg, highly irritable tendon, systemic comorbidities) as well as common pitfalls, such as unrealistic rehabilitation time frames and overreliance on passive treatments, are also discussed. J Orthop Sports Phys Ther 2015;45(11):887-898. Epub 21 Sep 2015. doi:10.2519/jospt.2015.5987.

Tendon neuroplastic training: changing the way we think about tendon rehabilitation: a narrative review

Tendinopathy can be resistant to treatment and often recurs, implying that current treatment approaches are suboptimal. Rehabilitation programmes that have been successful in terms of pain reduction and return to sport outcomes usually include strength training. Muscle activation can induce analgesia, improving self-efficacy associated with reducing ones own pain. Furthermore, strength training is beneficial for tendon matrix structure, muscle properties and limb biomechanics. However, current tendon rehabilitation may not adequately address the corticospinal control of the muscle, which may result in altered control of muscle recruitment and the consequent tendon load, and this may contribute to recalcitrance or symptom recurrence. Outcomes of interest include the effect of strength training on tendon pain, corticospinal excitability and short interval cortical inhibition. The aims of this concept paper are to: (1) review what is known about changes to the primary motor cortex and motor control in tendinopathy, (2) identify the parameters shown to induce neuroplasticity in strength training and (3) align these principles with tendon rehabilitation loading protocols to introduce a combination approach termed as tendon neuroplastic training. Strength training is a powerful modulator of the central nervous system. In particular, corticospinal inputs are essential for motor unit recruitment and activation; however, specific strength training parameters are important for neuroplasticity. Strength training that is externally paced and akin to a skilled movement task has been shown to not only reduce tendon pain, but modulate excitatory and inhibitory control of the muscle and therefore, potentially tendon load. An improved understanding of the methods that maximise the opportunity for neuroplasticity may be an important progression in how we prescribe exercise-based rehabilitation in tendinopathy for pain modulation and potentially restoration of the corticospinal control of the muscle-tendon complex.

Do isometric and isotonic exercise programs reduce pain in athletes with patellar tendinopathy in-season? A randomised clinical trial

OBJECTIVES Many athletes with patellar tendinopathy participate in sports with symptoms during or after activities. Current treatments do not decrease pain in-season; eccentric exercises in-season result in an increase in pain. This study examined if isometric and isotonic exercises relieved pain in competing athletes with patellar tendinopathy. DESIGN Randomised clinical trial. METHODS Jumping athletes with patellar tendinopathy playing at least three times per week participated in this study. Athletes were randomised into an isometric or isotonic exercise group. The exercise programs consisted of four isometric or isotonic exercise sessions per week for four weeks. Pain during a single leg decline squat (SLDS) on a Numeric Rating Scale (NRS; 0-10) was used as the main outcome measure; measurements were completed at baseline and at 4-week follow-up. RESULTS Twenty-nine athletes were included in this study. Median pain scores improved significantly over the 4-week intervention period in both the isometric group (Z=-2.527, p=0.012, r=-0.63) and isotonic group (Z=-2.952, p=0.003, r=-0.63). There was no significant difference in NRS pain score change (U=29.0, p=0.208, r=0.29) between the isometric group (median (IQR), 2.5 (1-4.5)) and isotonic group (median (IQR), 3.0 (2-6)). CONCLUSIONS This is the first study to show a decrease in patellar tendon pain without a modification of training and competition load and the first study to investigate isometric exercises in a clinical setting. Both isometric and isotonic exercise programs are easy-to-use exercises that can reduce pain from patellar tendinopathy for athletes in-season.

Does the adolescent patellar tendon respond to 5 days of cumulative load during a volleyball tournament

Patellar tendinopathy (jumpers knee) has a high prevalence in jumping athletes. Excessive load on the patellar tendon through high volumes of training and competition is an important risk factor. Structural changes in the tendon are related to a higher risk of developing patellar tendinopathy. The critical tendon load that affects tendon structure is unknown. The aim of this study was to investigate patellar tendon structure on each day of a 5‐day volleyball tournament in an adolescent population (16–18 years). The right patellar tendon of 41 players in the Australian Volleyball Schools Cup was scanned with ultrasound tissue characterization (UTC) on every day of the tournament (Monday to Friday). UTC can quantify structure of a tendon into four echo types based on the stability of the echo pattern. Generalized estimating equations (GEE) were used to test for change of echo type I and II over the tournament days. Participants played between eight and nine matches during the tournament. GEE analysis showed no significant change of echo type percentages of echo type I (Wald chi‐square = 4.603, d.f. = 4, P = 0.331) and echo type II (Wald chi‐square = 6.070, d.f. = 4, P = 0.194) over time. This study shows that patellar tendon structure of 16–18‐year‐old volleyball players is not affected during 5 days of cumulative loading during a volleyball tournament.

What tendon pathology is seen on imaging in people who have taken fluoroquinolones? A systematic review

Fluoroquinolones (FQs) are highly effective broad‐spectrum antibiotics. Clinical data reveal an increased incidence of tendon pain and rupture in those taking FQs, yet little is known about tendon structural changes. This review synthesises published data on tendon structural changes in people who have taken FQs. Eight databases were searched for potentially relevant articles (Medline, CINAHL, Biological Abstracts, AMED, Web of Knowledge, SCOPUS, SportDiscus and EMBASE) using MeSH and free‐text searches. Inclusion and exclusion criteria determined which articles were used for this review. Twenty‐six papers met the eligibility criteria. The Achilles tendon was most commonly affected, and ciprofloxacin and levofloxacin were the most commonly implicated FQs. Mean time to onset of symptoms was 16 days following first FQ dose. Imaging modalities used included magnetic resonance imaging (MRI), B‐mode ultrasound (US) and computed tomography (CT). Tendon measurements were rarely reported, and intratendinous imaging findings were not reported in a consistent manner. Few studies imaged tendons bilaterally, and only two studies were longitudinal in design. Future studies should report imaging measures such as thickness and cross‐sectional area and use consistent descriptions of intratendinous changes during and post‐FQ treatment.

Isometric Contractions Are More Analgesic Than Isotonic Contractions for Patellar Tendon Pain: An In-Season Randomized Clinical Trial

Objective: This study aimed to compare the immediate analgesic effects of 2 resistance programs in in-season athletes with patellar tendinopathy (PT). Resistance training is noninvasive, a principle stimulus for corticospinal and neuromuscular adaptation, and may be analgesic. Design: Within-season randomized clinical trial. Data analysis was conducted blinded to group. Setting: Subelite volleyball and basketball competitions. Participants: Twenty jumping athletes aged more than 16 years, participating in games/trainings 3 times per week with clinically diagnosed PT. Interventions: Two quadriceps resistance protocols were compared; (1) isometric leg extension holds at 60 degrees knee flexion (80% of their maximal voluntary isometric contraction) or (2) isotonic leg extension (at 80% of their 8 repetition maximum) 4 times per week for 4 weeks. Time under load and rest between sets was matched between groups. Main Outcome Measures: (1) Pain (0-10 numerical rating score) during single leg decline squat (SLDS), measured preintervention and postintervention sessions. (2) VISA-P, a questionnaire about tendon pain and function, completed at baseline and after 4 weeks. Results: Twenty athletes with PT (18 men, mean 22.5 ± 4.7 years) participated (isotonic n = 10, isometric n = 10). Baseline median SLDS pain was 5/10 for both groups (isotonic range 1-8, isometric range 2-8). Isometric contractions produced significantly greater immediate analgesia (P < 0.002). Week one analgesic response positively correlated with improvements in VISA-P at 4 weeks (r2 = 0.64). Conclusions: Both 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.

Elevated corticospinal excitability in patellar tendinopathy compared with other anterior knee pain or no pain.

Anterior knee pain (AKP) is a frequent clinical presentation in jumping athletes and may be aggravated by sustained sitting, stair use, and loading of the quadriceps. Corticospinal activation of the quadriceps in athletes with AKP has not yet been investigated, but is important in guiding efficacious treatment. This cross‐sectional study assessed corticospinal excitability (CSE) of the quadriceps in jumping athletes using transcranial magnetic stimulation (TMS). Groups consisted of Control (no knee pain); patellar tendinopathy (PT) [localized inferior pole pain on single‐leg decline squat (SLDS)]; and other AKP (nonlocalized pain around the patella). SLDS (numerical score of pain 0–10), Victorian Institute of Sport Assessment Patellar tendon (VISA‐P), maximal voluntary isometric contraction (MVIC), active motor threshold (AMT), CSE, and Mmax were tested. Twenty nine athletes participated; control n = 8, PT n = 11, AKP n = 10. There were no group differences in age (P = 0.23), body mass index (P = 0.16), MVIC (P = 0.38) or weekly activity (P = 0.22). PT had elevated CSE compared with controls and other AKP (P < 0.001), but no differences were detected between AKP and controls (P = 0.47). CSE appears to be greater in PT than controls and other AKP. An improved understanding of the corticospinal responses in different sources of knee pain may direct better treatment approaches.