Are unilateral and bilateral patellar tendinopathy distinguished by differences in anthropometry, body composition, or muscle strength in elite female basketball players?

Placebo Effect in the Treatment of Patellar Tendinopathy and Its Influencing Factors: Systematic Review With Meta-analysis and Meta Regression of Randomized Controlled Trials

Background

The effectiveness of nonsurgical treatment of patellar tendinopathy is questioned due to the conflicting results of placebo-controlled randomized controlled trials (RCTs) in which placebo arms often show impressive results.

Purpose

To quantify the magnitude of placebo effect of the different nonsurgical treatments of patellar tendinopathy. We also evaluated the influence of patients and treatments characteristics on the response to the placebo.

Study Design

Systematic review; Level of evidence, 1.

Methods

We searched PubMed, Web of Science, Embase, Scopus, Cochrane Library, and gray literature databases on May 10, 2023, with no time limitation. RCTs on nonoperative treatment of patellar tendinopathy, including a placebo control arm reporting the evolution of symptoms after placebo administration, were included. A single-arm meta-analysis was performed with the Victorian Institute of Sport Assessment-Patella (VISA-P) at mid-term follow-up (3-6 months) as the primary outcome. The VISA-P score at short-term (1-3 months) and long-term (6-12 months) follow-ups, as well as visual analog scale (VAS) for pain at all 3 time points were also analyzed. A subanalysis based on the type of placebo and a meta-regression were conducted to look for potential determinants of the placebo effect. Risk of bias and level of evidence were also analyzed using the revised tool for risk of bias in randomized trials and Grading of Recommendations Assessment, Development and Evaluation.

Results

In total, 14 studies (251 patients) were included. VISA-P score at mid-term follow-up (3-6 months) showed statistically significant improvements of 13 of 100 points (P = .001). The change at short-term follow-up (1-3 months) was not statistically significant, whereas at long-term follow-up (6-12 months) it was 27 of 100 points (P < .001). Regarding VAS, results were statistically significant only at mid-term (MD = -1.5/10; P = .02) and long-term (MD = -3.2/10; P < .001) follow-ups. The meta-regression showed positive correlations between the response to placebo and the follow-up length (P < .001) and the effect size in the experimental group (P = .006). The level of evidence was moderate for mid- and long-term results and low for short-term results.

Conclusion

The placebo effect for nonsurgical treatments of patellar tendinopathy is long-lasting (up to 12 months) and statistically and clinically significant. It has a perceived and true component and differs among treatments. The duration of follow-up and the effect size of experimental groups correlate with the magnitude of the placebo component, underlining the importance of RCTs to determine the effectiveness of new treatments of patellar tendinopathy.

Using bilateral data in controls and patients with bilateral and unilateral pathology requires increased scrutiny

In many aspects of human research, capturing multiple measures from the same participant is common due to the symmetric nature of the human body (e.g., two eyes, ten fingers, two legs, etc.). This has established a concerning paradox in biomedical and clinical research. When the same condition exist bilaterally (controls or bilateral pathology), researchers often blindly include both (or multiple) measures into the statistical analysis. This assumes that measures between the two sides are statistically independent (uncorrelated). However, there are certain inherent factors within an individual (e.g., age, sex, physical activity, gait pattern, tissue characteristics, hormonal status, pain thresholds, etc.) that would point to a statistical dependence between bilateral measures. Conversely, in unilateral pathology, it is common practice to use the contralateral side as the comparator. This assumes the exact opposite, that sans pathology, bilateral measures are perfectly correlated without bias. Both of these assumptions can lead to errors in the study conclusions. Few studies have explored the statistical dependence between multiple measures from the same participant. Thus, the purpose of this perspective is to explore the statistical considerations associated with analyzing multiple measures from the same participant and provide recommendations for navigating the use of multiple, non-temporal, data points from the same participant. To give context for these recommendations, an example dataset involving patellofemoral kinematics is provided. Due to the prevalent use of bilateral data in the current literature and the resulting potential for invalid study conclusions, we recommend that future research use caution when using multiple measures from the same participant and apply proper statistical analysis (e.g., generalized estimating equations) when these measures are not independent. If the contralateral limb is used as a comparator in unilateral pathology, strong evidence must exist that the underlying pathology has not altered the measures of interest in this contralateral limb.

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.

Association between Body Weight and Body Mass Index and Patellar Tendinopathy in Elite Basketball and Volleyball Players, a Systematic Review and Meta-Analysis

The features of Patellar-Tendinopathy are (1): pain localised to the inferior pole of the patellar; (2): the presence of load-related pain. Body-Weight and Body-Mass-Index, as two easily-measured variables, could potentially aid the prediction of PT. This review aims to establish relationships between Body-Weight and Body-Mass-Index and Patellar-Tendinopathy via synthesising the evidence from prospective-cohort and cross-sectional studies in elite basketball and volleyball players. Seven databases (PubMed, EMBASE, CINAHL, Google Scholar, Health-Management-Information-Consortium, National-Technical-Information-Service, ClinicalTrial.gov) and citation chasing were used to identify English peer-review articles from 2000 to 2022. An adapted version of the Newcastle-Ottawa scale was used for critical appraisal. Two reviewers were involved in literature searching, data extraction, and quality review. Two prospective cohort and five cross-sectional studies met the inclusion criteria, providing 849 subjects (male:female: 436:413). Five studies found BW is associated with PT. Three studies found a relationship between BMI and PT. Six out of seven studies were classified as very good studies. All studies were level IV evidence. The very low certainty evidence suggests an association between BW and PT. There is moderate certainty evidence that BMI is associated with PT. These preliminary findings should be treated cautiously due to the lack of strong evidence.

Impact of Patellar Tendinopathy on Isokinetic Knee Strength and Jumps in Professional Basketball Players

Patellar tendinopathy is characterized by tendon pain which may reduce the level of performance. This study's main aim was to compare isokinetic knee strength and jump performances at the start of the sport season between players with patellar tendinopathy and those without. Secondary aims were to assess the relationship between knee strength and jump function. Sixty-two professional basketball players were enrolled (mean age: 25.0 ± 4.0). All players performed knee isokinetic measurements, single leg countermovement jumps, and one leg hop tests. Correlations between knee strength and jump performances were examined. Twenty-four players declared a patellar tendinopathy and were compared to the 38 players without tendinopathy. The isokinetic quadriceps strength was lower in cases of patellar tendinopathy, and a camel's back curve was observed in 58% of the cases of patellar tendinopathy. However, jump performances were preserved. No link was found between quadriceps and hamstring limb symmetry indexes at 60 and 180°/s with jumps. This preseason screening enabled us to identify the absence of consequences of patellar tendinopathy in professional basketball players. Jump performances were not altered, possibly due to compensatory strategies.

Chronic hyperglycemia, hypercholesterolemia, and metabolic syndrome are associated with risk of tendon injury

Tendon injury is a considerable problem affecting both physically active and sedentary people. The aim of this study was to examine the relationship between markers for metabolic disorders (hyperglycemia, hypercholesterolemia, and metabolic syndrome) and the risk of developing tendon injuries requiring referral to a hospital. The Copenhagen City Heart Study is a prospective study of diabetic and non-diabetic individuals from the Danish general population with different physical activity levels. The cohort was followed for 3 years via national registers with respect to tendon injuries. Data from 5856 individuals (median age 62 years) were included. The overall incidence of tendon injury in both upper and lower extremities that required an out-patient or in-house visit to a hospital was ~5.7/1000 person years. Individuals with elevated HbA1c (glycated hemoglobin) even in the prediabetic range (HbA1c>5.7%) had a ~3 times higher risk of tendon injury in the lower extremities only, as compared to individuals with normal HbA1C levels. Hypercholesterolemia (total cholesterol>5 mmol/L) increased risk of tendon injury in the upper extremities by ~1.5 times, and individuals with metabolic syndrome had ~2.5 times higher risk of tendon injury in both upper and lower extremities. In conclusion, these data demonstrate for the first time in a large cohort with different physical activity levels that the indicators for metabolic syndrome are a powerful systemic determinant of tendon injury, and two of its components, hyperglycemia and hypercholesterolemia, each independently make tendons susceptible for damage and injury.

Anterior Knee Pain Risk Differs Between Sex and Occupation in Military Tactical Athletes

CONTEXT

Anterior knee pain (AKP) is ubiquitous in early-career military members and exacerbated during functional tasks required during military duties. Therefore, it is important to understand risk of this condition in male and female tactical athletes in diverse military occupations.

OBJECTIVE

To assess sex and occupation on AKP risk in military members.

DESIGN

Descriptive Epidemiology Study.

SETTING

United States Armed Forces. Patients All military members diagnosed with anterior or retro-patellar pain, patellar instability, knee tendinopathy on their initial encounter from 2006 to 2015.

OUTCOME MEASURES

The Defense Medical Epidemiology Database was queried for the number of individuals with AKP. Relative risk (RR) and chi-square statistics were calculated in the assessment of sex and occupational category. Regressions were calculated to determine association between service branch, sex, and AKP across time.

RESULTS

From 2006-2015, a total of 151,263 enlisted and 14,335 officer services members were diagnosed with AKP. Enlisted females had an incidence rate of 16.7 per 1000 person-years compared to the enlisted male service members with an incidence rate of 12.7 per 1000 person-years (RR: 1.32, 95%CI: 1.30-1.34, p<0.001) across all AKP diagnoses. Female officers had an incidence rate of 10.7 per 1,000 person-years compared to male officers at an incidence rate of 5.3 per 1000 person-years (RR: 2.01, 95%CI: 1.94-2.09). Differences in risk were also noted across military occupation for both enlisted and officer service members (p<.05).

CONCLUSION

Sex and military occupation were salient factors for AKP risk. Evaluation of training requirements and developing interventions programs across military occupation could serve as a focus for future research aiming to mitigate associated risk factors of AKP.

Jumper's Knee: A Prospective Evaluation of Risk Factors in Volleyball Players Using a Novel Measure of Injury

OBJECTIVES

To examine potential intrinsic risk factors that may contribute to the onset of jumper's knee in elite level-male volleyball players.

DESIGN

Prospective Cohort Study.

SETTING

Varsity and National team volleyball gymnasiums.

PARTICIPANTS

Sixty elite adult male volleyball players from Canada.

ASSESSMENT OF RISK FACTORS

Players completed a series of risk factor assessments at the commencement of their seasons, including vertical jump (cm), ankle dorsiflexion range (degrees), dynamic balance (normalized distance reached; cm), dynamic knee alignment (degrees), and landing mechanics (degrees).

MAIN OUTCOME MEASURE

Self-reported knee problems, captured via short message service.

RESULTS

Knee problem prevalence was 75% [95% confidence intervals (CIs): 62.2-84.6] and the incidence rate for substantial injuries over the study period was 30 injuries/100 players/season (95% CI: 19.5-43.1). No risk factor was found to significantly predict the future occurrence of developing jumper's knee. The odds ratios were close to unity (range: 0.94-1.07) with narrow confidence intervals and P > 0.05.

CONCLUSIONS

A more sensitive capture of overuse knee problems did not result in the identification of distinct risk factors for the development of jumper's knee. These findings highlight a lack of available methodology to accurately assess risk factors for overuse injuries.

Thirty-seven jump-landing biomechanical variables are associated with asymptomatic patellar tendon abnormality and patellar tendinopathy: A systematic review

OBJECTIVE

To identify studies that report three-dimensional (3D) biomechanical analysis of jump-landing tasks in relation to athletes with current patellar tendinopathy (PT), and/or asymptomatic with history of PT or patellar tendon abnormality (PTA) on diagnostic imaging.

METHODS

Five electronic databases were searched. Included articles were required to: (1) investigate the 3D biomechanics of a jump-landing task; (2) be cross-sectional or longitudinal in design; and (3) include participants that had symptomatic PT, were asymptomatic with a history of PT, asymptomatic with PTA on diagnostic imaging and/or asymptomatic with an unknown pathology or PT history.

RESULTS

Thirty-seven statistically significant jump-landing variables were associated with PT, history of PT and/or PTA. The only consistent variable that could be replicated between studies was knee flexion angle at initial foot-ground contact (IC) and an altered hip flexion/extension strategy during a horizontal land phase of a vertical stop-jump.

CONCLUSION

Isolated vertical landings or take-offs alone may not be sensitive enough to identify key jump-landing variables associated with PT, thus clinicians and researchers should incorporate a whole jump-landing task with a horizontal landing component. Sagital plane hip and knee kinematics in a horizontal landing phase appear to provide the most valuable information for evaluating those with PT.

High-energy dose of therapeutic ultrasound in the treatment of patellar tendinopathy: protocol of a randomized placebo-controlled clinical trial

BACKGROUND

Patellar tendinopathy is an extremely debilitating condition and its treatment usually requires a combination of clinical approaches. Therapeutic ultrasound (TUS) is one of the most available electrophysical agent in rehabilitation settings; however, there is also a lack of high-quality studies that test different dosimetric aspects of TUS. Thus, the purpose of this study is to evaluate the short-, medium-, and long-term effects of the combination of high-energy TUS with a rehabilitation program for patellar tendinopathy.

METHODS

This will be a randomized, placebo-controlled trial with blinding of patients, assessors, and therapist. The setting is an outpatient physical therapy clinic. We will recruit 66 participants (male and female) aged between 18 and 40 years and presenting with patellar tendinopathy. A treatment combining high-energy dose TUS and a rehabilitation program for patellar tendinopathy will be delivered twice a week for 8 weeks. The control group will receive the same treatment, but with a placebo TUS. The effectiveness of the intervention will be measured at the beginning (baseline), midpoint (4 weeks), and end of treatment (8 weeks), as well as at 3- and 6-months post-treatment. Primary outcomes will be pain intensity (visual analogue scale, VAS), and VISA-P questionnaire and primary time points will be baseline (T0) and the end of the program (T2). Also, IPAQ-short form questionnaire, muscle strength (manual dynamometry), 2D kinematics, pain pressure threshold (PPT) algometry, thermography, and magnetic resonance imaging (MRI) will be collected.

DISCUSSION

TUS will be applied in an attempt to enhance the results obtained with the rehabilitation program proposed in this study, as well as stimulate some repair responses in individuals undergoing treatment for patellar tendinopathy, which in turn may optimize and improve treatment programs for patellar tendinopathy as well as to establish new guidelines for the application of TUS.

TRIAL REGISTRATION

This study was prospectively registered at April-3rd-2018 and updated at September-1st-2019 in the Brazilian Registry of Clinical Trials (REBEC) under the registration number: RBR-658n6w.

Lower Limb Dominance, Morphology, and Sonographic Abnormalities of the Patellar Tendon in Elite Basketball Players: A Cross-Sectional Study

CONTEXT

Patellar tendinopathy is common in basketball players, and structural ultrasound abnormalities can be found in symptomatic and asymptomatic tendons. Lower limb dominance may also be a critical load factor, potentially leading to overloading of the patellar tendon.

OBJECTIVE

To describe and compare the prevalence by lower limb dominance of patellar tendons with structural and vascular abnormalities and to describe the morphologic measures of tendons without abnormalities among adult male elite basketball players.

DESIGN

Cross-sectional study.

SETTING

Medical center of a professional basketball team in the Spanish league.

PATIENTS OR OTHER PARTICIPANTS

A total of 73 adult male elite basketball players (146 patellar tendons; age = 26.8 ± 4.9 years, height = 198.0 ± 0.1 cm, mass = 95.4 ± 11.4 kg).

MAIN OUTCOME MEASURE(S)

We used ultrasound to screen the patellar tendons for the presence of structural and vascular abnormalities. Tendons were categorized as abnormal if they demonstrated a focal area of hypoechogenicity, thickening, or neovascularization. We also examined the cross-sectional area and thickness of tendons without abnormalities. Prevalence and morphologic measures were compared by limb dominance.

RESULTS

A total of 35 players (48%) had bilateral abnormalities, whereas 21 (28.7%) had unilateral abnormalities. Among the 91 abnormal tendons, 90 (61.6% of 146 tendons) exhibited a focal area of hypoechogenicity, 59 (40.4% of 146 tendons) exhibited thickening, and 14 (9.6% of 146 tendons) exhibited neovascularization. No group differences were detected between the dominant and nondominant limbs. Among the 55 normal patellar tendons, 34 were bilateral (from 17 players) and 21 were unilateral. Approximately 25% (n = 14) of all 55 normal tendons had a cross-sectional area that was greater than 182.8 mm² and a thickness greater than 7.2 mm. Among the 34 bilateral normal tendons, no group differences were observed between the dominant and nondominant limbs for either cross-sectional area or thickness.

CONCLUSIONS

The prevalence of abnormal tendons was high among adult male elite basketball players, and bilateral presentations were more frequent. Structural abnormalities were most common.

Clinical Measures and Their Contribution to Dysfunction in Individuals With Patellar Tendinopathy

CONTEXT

Patellar tendinopathy (PT) is prevalent in physically active populations, and it affects their quality of living, performance of activity, and may contribute to the early cessation of their athletic careers. A number of previous studies have identified contributing factors for PT; however, their contributions to self-reported dysfunction remain unclear.

OBJECTIVE

The purpose of this investigation was to determine if strength, flexibility, and various lower-extremity static alignments contributed to self-reported function and influence the severity of PT.

DESIGN

Cross-sectional research design.

SETTING

University laboratory.

PARTICIPANTS

A total of 30 participants with PT volunteered for this study (age: 23.4 [3.6] y, height: 1.8 [0.1] m, mass: 80.0 [20.3] kg, body mass index: 25.7 [4.3]).

MAIN OUTCOME MEASURES

Participants completed 7 different patient-reported outcomes. Isometric knee extension and flexion strength, hamstring flexibility and alignment measures of rearfoot angle, navicular drop, tibial torsion, q-angle, genu recurvatum, pelvic tilt, and leg length differences were assessed. Pearson's correlation coefficients were assessed to determine significantly correlated outcome variables with each of the patient-reported outcomes. The factors with the highest correlations were used to identify factors that contribute the most to pain and dysfunction using backward selection, linear regression models.

RESULTS

Correlation analysis found significant relationships between questionnaires and body mass index (r = -.35-.46), normalized knee extension (r = .38-.50) and flexion strength (r = -.34-.50), flexibility (r = .32-.38, q-angle (r = .38-.56), and pelvic tilt (r = -.40). Regression models (R² = .22-.54) identified thigh musculature strength and supine q-angle to have greatest predictability for severity in patient-reported outcomes.

CONCLUSIONS

These findings put an emphasis of bodyweight management, improving knee extensor and flexor strength, and posterior flexibility in PT patients.

Association of Hip and Foot Factors With Patellar Tendinopathy (Jumper's Knee) in Athletes

Background Investigations on the causes of patellar tendinopathy should consider impairments at the hip and foot/ankle because they are known to influence movement patterns and affect patellar tendon loading. Objectives To investigate hip and foot/ankle impairments associated with patellar tendinopathy in volleyball and basketball athletes using classification and regression tree analysis. Methods In this clinical measurement, cross-sectional study, 192 athletes were assessed for impairments of the hip and foot/ankle, including shank-forefoot alignment, dorsiflexion range of motion (ROM), iliotibial band flexibility, passive hip internal rotation ROM, and hip external rotator and hip abductor isometric strength. Athletes with tenderness and/or pain at the inferior pole of the patella were considered to have patellar tendinopathy. Athletes with scores higher than 95 points on the Victorian Institute of Sport Assessment-patella (VISA-P), no pain during the single-leg decline squat, and no history of patellar tendon pain were considered not to have patellar tendinopathy. Classification and regression tree analyses were performed to identify interacting factors associated with patellar tendinopathy. Results Interactions among passive hip internal rotation ROM, shank-forefoot alignment, and hip external rotator and abductor strength identified athletes with and without patellar tendinopathy. The model achieved 71.2% sensitivity and 74.4% specificity. The area under the receiver operating characteristic curve was 0.77 (95% confidence interval: 0.70, 0.84; P<.001). Conclusion Impairments of the hip and foot/ankle are associated with the presence of patellar tendinopathy in volleyball and basketball athletes. Future studies should evaluate the role of these impairments in the etiology of patellar tendinopathy. J Orthop Sports Phys Ther 2018;48(9):676-684. Epub 23 May 2018. doi:10.2519/jospt.2018.7426.

Muscle Strength Variations of Knee Joint Muscles in Elite Female Handball Players after Pre-Season Conditioning

Monitoring seasonal variations in strength performance and the relative risk of injury indicators related to strength of hamstring (H) and quadriceps (Q) in female elite athletes is beneficial for the training process. The aim of this study was to examine and compare the level of muscle strength, the conventional ratio (HCONC/QCONC) as well as two functional and strength ratios reflecting the movement of knee extension (HECC/QCONC) and flexion (HCONC/QECC), and the bilateral percentage strength deficit (BSD) in elite female handball players. The concentric and eccentric isokinetic peak torque was measured at an angular velocity of 60°/s on three occasions (in-season cessation, 4 weeks of rest followed by 4 weeks of individual conditioning and 6 weeks of group conditioning) in eleven female handball players (age: 23.1 ± 3.5 years, body height: 1.73 ± 0.6 m). According to ANOVA results, the BSD of H muscles in the concentric mode decreased between the in-season cessation and the end of the pre-season, and HCONC/QCONC increased at the beginning of the pre-season and at the end of the pre-season in comparison with inseason cessation measurement. The effect size analyses showed that the off-season rest followed by 10 weeks of the conditioning programme increased Q and H strength in comparison with the previous season with a large effect. Coaches should include progressive conditioning in the pre-season phase to decrease the bilateral strength deficit and to support further conditioning development.

Non-uniformity in the healthy patellar tendon is greater in males and similar in different age groups

There is increasing evidence that tendons are heterogeneous and take advantage of structural mechanisms to enhance performance and reduce injury. Fascicle-sliding, for example, is used by energy-storing tendons to enable them to undergo large extensions while protecting the fascicles from damage. Reductions in fascicle-sliding capacity may thus predispose certain populations to tendinopathy. Evidence from the Achilles tendon of significant superficial-to-deep non-uniformity that is reduced with age supports this theory. Similar patellar tendon non-uniformity has been observed, but the effects of age and sex have yet to be assessed. Healthy adults (n = 50, 25M/25F) from a broad range of ages (23-80) were recruited and non-uniformity was quantified using ultrasound speckle-tracking during passive knee extension. Significant superficial-to-deep non-uniformity and proximal/distal variations were observed. No effect of age was found, but males exhibited significantly greater non-uniformity than females (p < 0.05). The results contrast with previous findings in the Achilles tendon; in this study, tendons and tendon regions at high risk for tendinopathy (i.e. males and proximal regions, respectively) exhibited greater non-uniformity, whereas high-risk Achilles tendons (i.e. older adults) previously showed reduced non-uniformity. This suggests that non-uniformity may be dominated by factors other than fascicle-sliding. Anatomically, the varied proximal attachment of the patellar tendon may influence non-uniformity, with quadriceps passive resistance limiting superficial tendon movement, thus linking flexibility, non-uniformity and injury risk. This study also provides evidence of a differential effect of aging on the patellar tendon compared with evidence from prior studies on other tendons necessitating further study to elucidate links between non-uniformity and injury.

Patellar tendon buckling is altered with age

Recent evidence has revealed that the patellar tendon exhibits buckling during passive knee extension, wherein the tendon folds back onto itself. The clinical relevance of such buckling is unclear, but it has been suggested that it serves to protect the patellar tendon from rupture when subjected to a sudden extreme contraction. Although prior evidence suggests buckling occurs universally, it is poorly understood, and may be influenced by age and sex. Healthy adults (n = 41, aged 21-80 years) were recruited to assess age- and sex-based differences in patellar tendon buckling during passive knee extension. 93% of subjects exhibited buckling in extension, with buckling more prominent in the distal tendon. No age- or sex-based differences in buckling magnitude were observed, but a significant age-based difference in buckling angle was found, with the tendon unbuckling later in flexion in younger adults compared with middle-aged (p = 0.025) and older (p = 0.014) adults. Intrinsic factors were also linked with buckling; for example, smaller maximum knee extension (i.e. less flexibility) correlated with smaller buckling magnitude (p = 0.037, R² = 0.116), suggesting a link between patellar tendon buckling and joint-level mechanics. These results suggest that buckling is an inherent component of normal knee function that older adults may be failing to take advantage of, predisposing them to injury. Further study will be critical to elucidate the clinical implications of patellar tendon buckling.

Isometric strength of the hip abductors and external rotators in athletes with and without patellar tendinopathy

PURPOSE

This study aims to compare the isometric strength of hip abductors and external rotators in male athletes with and without patellar tendinopathy (PT), and to examine the correlation between hip strength, pain, and functional scores.

METHODS

Sixty male athletes (30 with PT and 30 controls) were recruited from local volleyball and basketball teams. The isometric strength of the hip abductors and external rotators was quantified using a belt-stabilized handheld dynamometer. This study used the visual analog scale (VAS) and the Victorian Institute of Sport Assessment-Patella (VISA-p) questionnaire to measure the intensity of pain and functional scores in athletes with PT, respectively.

RESULTS

The normalized isometric strength of the hip abductors and external rotators was significantly less in the PT group compared with controls. In subjects with PT, the normalized isometric strength was decreased by 22.0% (p = 0.000) in the hip abductors and by 20.0% in the hip external rotators (p = 0.004), compared with controls. Significant correlations were found between the normalized isometric strength of the hip abductors and intensity of pain (r = - 0.70; p < 0.05) and VISA-p score (r = 0.63; p < 0.05) in the affected leg in athletes with unilateral PT.

CONCLUSIONS

Athletes with PT have decreased isometric strength in their hip abductors and external rotators when compared with controls. In subjects with unilateral PT, decreased isometric strength in the hip abductors is associated with greater intensity of pain and lower functional scores. Results of this study implied that hip muscle assessment and strengthening should be included for reconditioning and rehabilitation in athletes with PT.

Proximal patellar tendon pathology can develop during adolescence in young ballet dancers-A 2-year longitudinal study

Patellar tendinopathy (tendon pain and dysfunction), or jumper's knee, is prevalent in adult jumping athletes. Pathology in the proximal patellar tendon is a key risk factor for developing patellar tendinopathy. When pathology develops in the proximal patellar tendon is not known, although it is reported to exist in adolescent athletes. The aim of this study was to follow young jumping athletes (ballet dancers) through adolescence to identify whether pathology develops and its relation to the adolescent growth spurt. Fifty-seven elite ballet students between ages 11 and 18 were monitored for 2 years. Data were collected every 6 months, including an ultrasound scan on their left tendons using ultrasound tissue characterization (UTC) to quantify intratendinous changes, anthropometric data to calculate peak height velocity (adolescent growth spurt), participant reports of any injuries or dance modifications, and a VISA-P and single leg decline squat for patellar tendon pain. Nine percentage of adolescent dancers developed pathology during this study, and development was not associated with growth spurt. Peak height velocity and dance participation/volume both at the start and throughout the study were similar in those who did develop pathology and those who did not. Only 2 of 5 participants who developed pathology reported pain associated with their tendon. Pathology in the proximal patellar tendon can develop during adolescence.

Body Mass Index as a Predictor of Injuries in Athletics

The quest to identify injury risk factors in sports has been an ongoing and well-researched field in the world of sports medicine. Knowing some of these factors helps keep sports participation safe. Both intrinsic and extrinsic factors have been studied. Body mass index (BMI) is widely known to contribute to several medical conditions. Its association with some sports injuries has been established but the information is vast, with few studies that are randomized controlled trials. It is important to analyze these studies and confirm whether BMI is a predictor of lower-extremity injuries. Such knowledge allows for better effective treatment and prevention strategies. This article will summarize current evidence of association between BMI and lower-extremity injuries in athletes and whether BMI is a predictor of lower-extremity injuries.

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.

Influence of repetitive mechanical loading on MMP2 activity in tendon fibroblasts

Matrix metalloproteinase2 has been implicated in tendon pathology caused by repetitive movements. However, its activity in the early stages of the tendon's response to overuse, and its presence in the circulation as a possible indicator of tendon degradation, remain unknown. Human tendon cells were repetitively stretched for 5 days, and the rabbit Achilles tendon complex underwent repetitive motion 3× per week for 2 weeks. Quantitative polymer chain reaction analysis was performed to detect matrix metalloproteinase2/14 and tissue inhibitor of matrix metalloproteinase2 messenger ribonucleic acid of cells and rabbit tissue, and matrix metalloproteinase2 protein levels were determined with an enzyme linked immunoassay. Matrix metalloproteinase2 activity was examined using zymography of the conditioned media, tendon and serum. Immunohistochemistry was used to localize matrix metalloproteinase2 in tendon tissue, and the density of fibrillar collagen in tendons was examined using second harmonic generation microscopy. Tendon cells stretched with high strain or high frequency demonstrated increased matrix metalloproteinase2 messenger ribonucleic acid and protein levels. Matrix metalloproteinase2 activity was increased in the rabbit Achilles tendon tissue at weeks 1 and 2; however, serum activity was only increased at week 1. After 2 weeks of exercise, the collagen density was lower in specific regions of the exercised rabbit Achilles tendon complex. Matrix metalloproteinase2 expression in exercised rabbit Achilles tendons was detected surrounding tendon fibroblasts. Repetitive mechanical stimulation of tendon cells results in a small increase in matrix metalloproteinase2 levels, but it appears unlikely that serum matrix metalloproteinase2 will be a useful indicator of tendon overuse injury. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1991-2000, 2016.

The effect of female sex hormone supplementation on tendon in pre and postmenopausal women: A systematic review

OBJECTIVES

Oestrogen deprivation has been shown to have a negative effect on connective tissue and its turnover. A link may exist between supplemental oestrogen, preservation of tendon collagen and less tendon abnormality. The aim was to determine the effects of female sex hormone supplementation (FSHS) on tendon.

METHODS

A systematic search of nine key health databases; Medline, CINAHL, EMBASE, SPORTDiscus, AUSPORT and AMI, Cochrane Library, SafetyLit and PEDro was completed (to Feb 24, 2016). The search yielded 6378 records using terms relating to hormone (oestrogen, estrogen, hormone replacement therapy, HRT, estrogen therapy, oestrogen therapy, oral contraceptive pill) and tendon. Quality assessment, data extraction and data synthesis of included papers was undertaken.

RESULTS

Low level of evidence for all outcomes; no positive or negative link between FSHS and molecular, mechanical and morphological tendon response outcomes, and the addition of exercise to FSHS, had minimal effects on tendon CSA.

CONCLUSIONS

The effect of oestrogen supplementation on tendon is contradictory and inconsistent. This review suggests there is a need for further studies to understand the effects of FSHS on tendon tissue at a mechanical, morphological and molecular level.

Asymptomatic players with a patellar tendon abnormality do not adapt their landing mechanics when fatigued

This study aimed to explore how asymptomatic athletes with a patellar tendon abnormality (PTA), who are at high risk of developing patellar tendinopathy, alter their landing technique and net patellar tendon loads generated in response to fatigue. Seven asymptomatic players with a PTA performed five successful vertical stop-jump trials before and after a fatigue protocol. Fatigue protocol involved participants repeatedly performing sets of 30 submaximal jump exercises on a sledge apparatus followed by 30 s rest until the task failure criteria were reached. Three-dimensional ground reaction forces, lower limb kinematics and net peak patellar tendon force were recorded during the stop-jump task. No significant between-fatigue condition differences in net patellar tendon loading, or most secondary outcome variables were observed. Only some fatigue changes were seen during the vertical landing phase. Asymptomatic PTA participants did not modify their landing technique or net patellar tendon loading during a stop-jump task in response to fatigue. The lack of between-fatigue condition differences displayed by the asymptomatic PTA participants during both landing phases suggest that these individuals may not be capable of sufficient movement variability in their landing strategies to adapt to fatigue.

How Obesity Affects Tendons?

Several epidemiological and clinical observations have definitely demonstrated that obesity has harmful effects on tendons. The pathogenesis of tendon damage is multi-factorial. In addition to overload, attributable to the increased body weight, which significantly affects load-bearing tendons, systemic factors play a relevant role. Several bioactive peptides (chemerin, leptin, adiponectin and others) are released by adipocytes, and influence tendon structure by means of negative activities on mesenchymal cells. The ensuing systemic state of chronic, sub-clinic, low-grade inflammation can damage tendon structure. Metabolic disorders (diabetes, impaired glucose tolerance, and dislipidemia), frequently associated with visceral adiposity, are concurrent pathogenetic factors. Indeed, high glucose levels increase the formation of Advanced Glycation End-products, which in turn form stable covalent cross-links within collagen fibers, modifying their structure and functionality.Sport activities, so useful for preventing important cardiovascular complications, may be detrimental for tendons if they are submitted to intense acute or chronic overload. Therefore, two caution rules are mandatory: first, to engage in personalized soft training program, and secondly to follow regular check-up for tendon pathology.

Lower limb strength and flexibility in athletes with and without patellar tendinopathy

OBJECTIVES

To compare the hip, knee and ankle torques, as well as knee and ankle flexibility between athletes with patellar tendinopathy and asymptomatic controls.

DESIGN

Cross-sectional study.

SETTING

Laboratory setting.

PARTICIPANTS

Fourteen male volleyball, basketball or handball athletes, divided into 2 groups, patellar tendinopathy group (TG; n = 7) and asymptomatic control group (CG; n = 7).

MAIN OUTCOME MEASURES

Hip, knee and ankle isometric torques were measured with a handheld dynamometer. Weight-bearing ankle dorsiflexion, hamstring and quadriceps flexibility were measured with a gravity inclinometer.

RESULTS

The TG had 27% lower hip extensor torque when compared to the CG (P = 0.031), with no group differences in knee and ankle torques (P > 0.05). Also, the TG had smaller weight-bearing ankle dorsiflexion (P = 0.038) and hamstring flexibility (P = 0.006) when compared to the CG. Regarding quadriceps flexibility, no group differences were found (P = 0.828).

CONCLUSIONS

Strength and flexibility deficits might contribute to a greater overload on the knee extensor mechanism, possibly contributing to the origin/perpetuation of patellar tendinopathy. Interventions aiming at increasing hip extensors strength as well as ankle and knee flexibility might be important for the rehabilitation of athletes with patellar tendinopathy.

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.

Injury risk management plan for volleyball athletes

Volleyball is an increasingly popular team sport. As with any competitive sport, there is an inherent risk of injury that must be recognized and collaboratively managed. This article provides a practical approach to the management of volleyball injuries within a team or organization. A brief review of the epidemiological data is presented which establishes (i) ankle sprain, (ii) shoulder overuse injury, (iii) patella tendinopathy, and (iv) anterior cruciate ligament injury as the primary injuries to address amongst these athletes. The interaction of modifiable and non-modifiable risk factors for these injuries are used to classify athletes into high-, medium- and low-risk groups. Targeted training interventions are suggested, based upon the risk level of the athlete, to minimize the occurrence of these injuries. Practical methods for integrating these activities into a training plan are also discussed.

Factors associated with magnetic resonance imaging defined patellar tendinopathy in community-based middle-aged women: a prospective cohort study

Background

Patellar tendinopathy identified by imaging modalities has been reported in asymptomatic athletes and associated with tendon-related symptoms. However there is little data in community-based populations. The aim of this cohort study was to examine the prevalence of magnetic resonance imaging (MRI) defined patellar tendinopathy, the factors associated with this condition, and whether it was associated with knee pain in community-based middle-aged women.

Methods

One hundred seventy six women, aged 40–67 years, with no significant knee pain or injury underwent knee MRI. Patellar tendinopathy was defined on both T1- and T2-weighted fat-saturated MRIs. The cross-sectional area of vastus medialis was measured from MRI. Height and weight were measured to calculate body mass index (BMI). Physical activity was assessed using a questionnaire. Knee pain was assessed using the Western Ontario and McMaster University Osteoarthritis Index.

Results

The prevalence of MRI defined patellar tendinopathy was 30.1 %. Higher levels of physical activity (odds ratio 1.65, 95 % CI 1.09–2.51) and greater vastus medialis cross-sectional area (odds ratio 1.22, 95 % CI 1.04–1.43) were associated with increased prevalence of patellar tendinopathy, independent of age and BMI. The persistence of patellar tendinopathy was associated with the worsening of knee pain over 2 years (odds ratio 10.65, 95 % CI 1.14–99.77).

Conclusion

In community-based middle-aged women MRI-diagnosed patellar tendinopathy is common, with higher levels of physical activity and greater vastus medialis size being risk factors suggesting a biomechanical effect. Persistent patellar tendinopathy is associated with worsening of knee pain. These findings suggest that further work is needed to determine the contribution of patellar tendinopathy on knee pain and function in older people.

Bilateral differences in muscle architecture and increased rate of injury in national basketball association players

CONTEXT

Professional basketball players have demanding schedules that, in combination with certain underlying physical characteristics and side-to-side strength and power imbalances, may make them vulnerable to lower extremity injuries.

OBJECTIVE

To examine the relationship among skeletal muscle architecture, lower body power, and games missed because of lower extremity injury (%MISS) in professional basketball players.

DESIGN

Cross-sectional study. Setting : Human Performance Laboratory.

PATIENTS OR OTHER PARTICIPANTS

Nine players under contract for Orlando Magic were assessed. We compared athletes who were injured (n = 4, height = 203.2 ± 5.5 cm, mass = 105 ± 7.5 kg, age = 25.0 ± 2.8 years) and those who remained healthy (n = 5, height = 200.2 ± 12.2 cm, mass = 100.1 ± 16.6 kg, age = 22.4 ± 1.9 years) during the season.

MAIN OUTCOME MEASURE(S)

Bilateral ultrasonographic measurements of muscle thickness, pennation angle, echo intensity, and cross-sectional area of the rectus femoris and vastus lateralis were collected before regular-season play. Subsequently, muscle thickness and pennation angle were used to compute fascicle length. Along with unilateral jumping power, inferences were made upon the magnitude of the relationship between the percentage bilateral difference in these measures and %MISS, as well as between injured and healthy athletes.

RESULTS

The data indicated likely relationships between %MISS and age (r = 0.772), and between %MISS and bilateral differences in rectus femoris cross-sectional area (7.8% ± 6.4%; r = 0.657) and vastus lateralis cross-sectional area (6.2% ± 4.8%; r = 0.521), as well as a possible relationship with vastus lateralis muscle thickness (7.9% ± 8.9%; r = 0.444). Echo-intensity differences in the vastus lateralis were greater in injured (8.0% ± 2.4%) versus healthy athletes (3.2% ± 2.0%). Although a 2-fold difference in mean jumping power was observed between injured (26.3 ± 14.9 W) and healthy athletes (13.6 ± 8.7 W), these differences were not statistically significant (P = .20).

CONCLUSIONS

In the present sample, lower extremity side-to-side differences may be related to an increased risk for lower extremity injury. Future researchers using larger sample sizes need to identify normal versus at-risk ranges for bilateral differences in muscle structure and power of the lower extremities of professional basketball players and athletes in other sports.

No difference in effectiveness between focused and radial shockwave therapy for treating patellar tendinopathy: a randomized controlled trial

PURPOSE

The aim of the study was to compare the effectiveness of focused shockwave therapy (FSWT) and radial shockwave therapy (RSWT) for treating patellar tendinopathy.

METHODS

Patients were randomized into two groups. One group received three sessions of FSWT, and the other group received three sessions of RSWT. Both groups also received an eccentric training programme. Follow-up measurements took place 1, 4, 7 and 14 weeks after the final shockwave treatment. The primary outcome measure was the Victorian Institute of Sport Assessment-Patella (VISA-P) questionnaire. Secondary outcome measures were pain during ADL, sports activities and the decline squat.

RESULTS

Forty-three subjects (57 tendons) were included in the study. Twenty-one subjects (31 tendons) received FSWT, and 22 subjects (26 tendons) received RSWT. Both groups improved significantly on the VISA-P score, but there were no differences in improvement between the FSWT group (15 points on the VISA-P) and the RSWT group (9.6 points, n.s.). This was also the case for the secondary outcome measures.

CONCLUSION

There were no statistically significant differences in effectiveness between FSWT and RSWT. It is therefore not possible to recommend one treatment over the other on grounds of outcome. Both groups improved significantly, although it is questionable whether this difference is clinically relevant.

LEVEL OF EVIDENCE

II.

Association between obesity and magnetic resonance imaging defined patellar tendinopathy in community-based adults: a cross-sectional study

Background

Patellar tendinopathy is a common cause of activity-related anterior knee pain. Evidence is conflicting as to whether obesity is a risk factor for this condition. The aim of this study was to determine the relationship between obesity and prevalence of magnetic resonance imaging (MRI) defined patellar tendinopathy in community-based adults.

Methods

297 participants aged 50–79 years with no history of knee pain or injury were recruited from an existing community-based cohort. Measures of obesity included measured weight and body mass index (BMI), self-reported weight at age of 18–21 years and heaviest lifetime weight. Fat-free mass and fat mass were measured using bioelectrical impedance. Participants underwent MRI of the dominant knee. Patellar tendinopathy was defined on both T1- and T2-weighted images.

Results

The prevalence of MRI defined patellar tendinopathy was 28.3%. Current weight (OR per kg = 1.04, 95% CI 1.01-1.06, P = 0.002), BMI (OR per kg/m² = 1.10, 95% CI 1.04-1.17, P = 0.002), heaviest lifetime weight (OR per kg = 1.03, 95% CI 1.01-1.05, P = 0.007) and weight at age of 18–21 years (OR per kg = 1.03, 95% CI 1.00-1.07, P = 0.05) were all positively associated with the prevalence of patellar tendinopathy. Neither fat mass nor fat-free mass was associated with patellar tendinopathy.

Conclusion

MRI defined patellar tendinopathy is common in community-based adults and is associated with current and past history of obesity assessed by BMI or body weight, but not fat mass. The findings suggest a mechanical pathogenesis of patellar tendinopathy and patellar tendinopathy may be one mechanism for obesity related anterior knee pain.

Risk factors for patellar tendinopathy in volleyball and basketball players: A survey-based prospective cohort study

Patellar tendinopathy (PT) is a common overuse injury of the patellar tendon in jumping athletes. In a recent large cross-sectional study from 2008 several factors were identified that may be associated with the etiology of PT. However, because of the study design no conclusions could be drawn about causal relations. The primary aim of the current study is to investigate whether the factors identified in the previous 2008 study can also be prospectively recognized as predictors of symptomatic PT in 2011. Nine hundred twenty-six Dutch elite and non-elite basketball and volleyball players from the previous study were invited again to complete an online survey about knee complaints and risk factors for PT in 2011. The logistic regression included 385 athletes of which 51 (13%) developed PT since 2008. Male gender [odds ratio (OR) 2.0, 95% confidence interval (CI) 1.1-3.5] was found to be a risk factor for developing PT. No sports-related variables could be identified to increase the risk of developing PT, but some evidence was found for performing heavy physically demanding work, like being a nurse or a physical education teacher (OR 2.3, 95% CI 0.9-6.3). These findings indicate that, when considering preventive measures, it is important to take into account the total tendon load.

Surgery for unilateral and bilateral patellar tendinopathy: a seven year comparative study

PURPOSE

Open surgery for patellar tendinopathy allows patients with unilateral and bilateral tendinopathy to return to high levels of physical activity.

MATERIALS

Two groups of 23 athletes each underwent open surgical exploration for management of patellar tendinopathy. One group suffered from unilateral patellar tendinopathy (unilateral group), and the other group had bilateral (bilateral group) patellar tendinopathy. Maximum voluntary isometric contraction and anthropometric measures were assessed pre-operatively and at an average follow-up of seven years. The Victorian Institute of Sport Assessment (VISA)-P scoring system was also administered; functional outcomes were classified from excellent to poor according to a modification of Kelly's criteria.

RESULTS

At the final follow-up, in both groups, VISA-P scores were significantly improved compared with preoperative values, with no intergroup differences. Clinical results were excellent or good in 21 patients in the unilateral and 19 in the bilateral group. Twenty of 23 patients in the unilateral group and 17 of 23 in the bilateral group were still active in sports (p = 0.2). In the unilateral group, at the last follow-up, thigh volume and strength were significantly improved compared with baseline, with significant difference between operated and nonoperated limbs. In the bilateral group, there were no significant differences in thigh volume and strength between the dominant and nondominant limbs both before and after the index procedure.

CONCLUSIONS

This procedure is not technically demanding and provides a high rate of good and excellent outcomes in the long term.

Platelet-rich plasma for the treatment of patellar tendinopathy: clinical and imaging findings at medium-term follow-up

PURPOSE

The purpose of this study was to evaluate the efficacy of multiple platelet-rich plasma (PRP) injections on the healing of chronic refractory patellar tendinopathy, and report the quality and duration of the clinical improvement up to a medium-term follow-up.

METHODS

Forty-three patients (mean age, 30.6 years; mean BMI, 24.7; 42 men, one woman) affected by chronic patellar proximal tendinopathy were enrolled in this trial. Eleven patients were affected by bilateral tendinopathy. They underwent three ultrasound guided intra-tendinous injections of five millilitres PRP, two weeks apart from each other. Patients were prospectively evaluated initially, then after two, six, and up to mean 48.6 ± 8.1 months of follow-up (minimum evaluation at 36 months). The following evaluation tools were used: Blanzina, VISA-P, EQ-VAS for general health, and Tegner scores. Patients' overall satisfaction and time to return to sport were also reported.

RESULTS

Good and stable results were documented over time, with the VISA-P score increasing from 44.1 ± 15.6 at baseline to 61.4 ± 22.2 at two months, 76.6 ± 25.4 at six months, and 84.3 ± 21.6 at four years' follow-up. The same trend was confirmed by the other scores used, and 80 % of the patients were satisfied and returned to previous sports activities. Significantly poorer results were obtained in patients with a longer history of symptoms, and poor results were also observed in bilateral lesions. No correlation between ultrasonographic and clinical findings could be found.

CONCLUSIONS

Multiple injections of PRP provided a good clinical outcome for the treatment of chronic recalcitrant patellar tendinopathy with stable results up to medium-term follow-up. Patients affected by bilateral pathology and presenting a long history of pain obtained significantly poorer results.

An exercise-based physical therapy program for patients with patellar tendinopathy after platelet-rich plasma injection

OBJECTIVES

To describe a post platelet-rich plasma (PRP) injection, exercise-based physical therapy program, investigate feasibility and report the first results of patellar tendinopathy patients treated with PRP injection combined with the physical therapy program.

STUDY DESIGN

Case-series.

SETTING

A PRP injection followed by a physical therapy program seems promising for the treatment of patellar tendinopathy. However, descriptions of physical therapy programs are often limited and incomplete.

PARTICIPANTS

Five patellar tendinopathy patients (six tendons) in the degenerative phase.

MAIN OUTCOME MEASURE

VISA-P score.

RESULTS

Muscle strength, endurance, power and retraining sport-specific function form the basis for the physical therapy program aiming to improve the load capacity of the knee. The program is characterised by gradually increasing intensity and difficulty of exercises. Five of the six tendons showed an improvement of at least 30 points on the VISA-P after 26 weeks.

CONCLUSIONS

This study extensively describes, based on current knowledge, a physical therapy program after PRP injection for patellar tendinopathy patients. The combination treatment reported in this study is feasible and seems to be promising for patients in the late/degenerative phase of patellar tendinopathy.

Training volume and body composition as risk factors for developing jumper's knee among young elite volleyball players

Training volume and body composition have been suggested as risk factors for jumper's knee among athletic youth, but research is lacking. The aim of this 4-year prospective cohort study was to examine the relationship between training and competition load, body composition, and risk for developing jumper's knee. Participants are elite volleyball players, aged 16-18 years. Training and competition load was recorded continuously and body composition semiannually. Jumper's knee was diagnosed on a standardized clinical examination. We recruited 141 healthy students (69 males and 72 females), and 28 developed jumper's knee (22 boys and six girls). In a multivariate analyses, boys had three to four times higher risk compared with girls. Volleyball training had an odds ratio (OR) 1.72 (1.18-2.53) for every extra hour trained, and match exposure was the strongest sports-related predictor for developing jumper's knee with an OR of 3.88 (1.80-8.40) for every extra set played per week. We did not detect any significant differences between the groups in body composition at the time of inclusion or in the change of body composition during the study period. Conclusion, male gender, a high volume of volleyball training and match exposure were risk factors for developing jumper's knee.

Low range of ankle dorsiflexion predisposes for patellar tendinopathy in junior elite basketball players: a 1-year prospective study

BACKGROUND

Patellar tendinopathy (PT) is one of the most common reasons for sport-induced pain of the knee. Low ankle dorsiflexion range might predispose for PT because of load-bearing compensation in the patellar tendon.

PURPOSE

The purpose of this 1-year prospective study was to analyze if a low ankle dorsiflexion range increases the risk of developing PT for basketball players.

STUDY DESIGN

Cohort study (prognosis); Level of evidence, 2.

METHODS

Ninety junior elite basketball players were examined for different characteristics and potential risk factors for PT, including ankle dorsiflexion range in the dominant and nondominant leg. Data were collected over a 1-year period and follow-up, including reexamination, was made at the end of the year.

RESULTS

Seventy-five players met the inclusion criteria. At the follow-up, 12 players (16.0%) had developed unilateral PT. These players were found to have had a significantly lower mean ankle dorsiflexion range at baseline than the healthy players, with a mean difference of -4.7° (P = .038) for the dominant limb and -5.1° (P = .024) for the nondominant limb. Complementary statistical analysis showed that players with dorsiflexion range less than 36.5° had a risk of 18.5% to 29.4% of developing PT within a year, as compared with 1.8% to 2.1% for players with dorsiflexion range greater than 36.5°. Limbs with a history of 2 or more ankle sprains had a slightly less mean ankle dorsiflexion range compared to those with 0 or 1 sprain (mean difference, -1.5° to -2.5°), although this was only statistically significant for nondominant legs.

CONCLUSION

This study clearly shows that low ankle dorsiflexion range is a risk factor for developing PT in basketball players. In the studied material, an ankle dorsiflexion range of 36.5° was found to be the most appropriate cutoff point for prognostic screening. This might be useful information in identifying at-risk individuals in basketball teams and enabling preventive actions. A history of ankle sprains might contribute to reduced ankle dorsiflexion range.

The effect of mild symptomatic patellar tendinopathy on the quadriceps contractions and the Fente motion in elite fencers

To investigate how mild symptomatic patellar tendinopathy (PT) affects quadriceps contractions and the Fente motion, this case-control study examined elite fencers who continue to train and play fully with mild tendon pains. Twenty-four elite fencers (10 women) with mild symptomatic PT and 24 controls (10 women) participated in the study. Concentric/eccentric isokinetic strength of the quadriceps was tested, and peak torque and total work were recorded. Kinematic data from the knee during the Fente motion were collected. The first analysis period (P1) was after heel contact to the maximal flexion of the knee, and the second (P2) was right after P1 to heel-off. Normalized peak torque and work of concentric/eccentric contractions were not significantly different. Affected fencers demonstrated significantly reduced angular velocities at P2 (p = 0.042). The male fencers did not demonstrate any differences. The affected female fencers demonstrated significantly weaker concentric peak torque at 60°·s(-1) (p = 0. 009) and 180°·s(-1) (p = 0.047) and less concentric work at 60°·s(-1) (p = 0.020). They also demonstrated significantly reduced average angular velocities at P2 (p = 0.001). Therefore, mild symptomatic PT seems to have an effect on the isokinetic concentric contraction of the quadriceps and the angular velocity of the knee during the backward Fente motion in elite female fencers who are participating fully in training and competition. Key pointsIt is likely that even mild symptomatic patellar tendinopathy could affect the athletic performances in elite fencers.Elite female fencers are more likely to be affected substantially by symptomatic patellar tendinopathy in their sporting ability than male fencers.Because weak concentric knee extensors may affect the performance in fencing, not only eccentric training for symptomatic patellar tendinopathy but also proper concentric training of the quadriceps may be helpful in a rehabilitation program of elite female fencers who are participating fully in their training and competition.

Prevalence of Jumper's knee among nonelite athletes from different sports: a cross-sectional survey

BACKGROUND

The prevalence of jumper's knee among nonelite athletes from different sports is unknown.

PURPOSE

This study was undertaken to determine the prevalence of jumper's knee in nonelite athletes from different sports and to determine potential risk factors for jumper's knee.

DESIGN

Cohort study (prevalence); Level of evidence, 2.

METHODS

The authors interviewed 891 male and female nonelite athletes from 7 popular sports in The Netherlands: basketball, volleyball, handball, korfball, soccer, field hockey, and track and field. Using a specially developed questionnaire, information was obtained about individual characteristics (age, height, and weight), training background, previous and actual knee problems, and the VISA-P (Victorian Institute of Sport Assessment-Patella) score.

RESULTS

The overall prevalence of current jumper's knee was 8.5% (78 of 891 athletes), showing a significant difference between sports with different loading characteristics. Prevalence was highest among volleyball players (14.4%) and lowest among soccer players (2.5%); it was significantly higher among male athletes (51 of 502 [10.2%]) than female athletes (25 of 389 [6.4%]) (χ(2) = 3.91, P = .048). The mean duration of symptoms was 18.9 months (standard deviation [SD], 21.6; median value, 12.0; range, 2.0-59.8). The mean VISA-P score of the athletes with jumper's knee was 71.4 (SD, 13.8). Athletes with jumper's knee were significantly younger, taller, and heavier than those without jumper's knee.

CONCLUSION

Prevalence of jumper's knee is high among nonelite athletes and varies between 14.4% and 2.5% for different sports. Jumper's knee is almost twice as common among male nonelite athletes compared with female athletes. Different sport-specific loading characteristics of the knee extensor apparatus, a younger age, a taller body stature, and higher body weight seem to be risk factors associated with patellar tendinopathy.

Arthroscopic management of chronic patellar tendinopathy

BACKGROUND

In patients with patellar tendinopathy in whom nonoperative management is unsuccessful, surgery is an option to return to high levels of physical activity. Although open surgery is traditionally advocated, an arthroscopic approach may be safe and effective.

PURPOSE

This study was undertaken to analyze medium- and long-term outcome of 64 patients undergoing arthroscopic surgery for the management of patellar tendinopathy after failing nonoperative treatment.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A total of 64 patients (73 knees), 27 of whom were professional athletes, with patellar tendinopathy refractory to nonoperative management underwent arthroscopic debridement of the adipose tissue of the Hoffa's body posterior to the patellar tendon, debridement of abnormal patellar tendon, and excision of the lower pole of the patella. Preoperative and postoperative evaluation was undertaken using the International Knee Documentation Committee (IKDC), Lysholm knee scale, and Victorian Institute of Sport Assessment-Patella (VISA-P) scores for all patients at 1 and 3 years. No patients were lost to follow-up. Forty-three and 29 patients were similarly assessed at 5 and 10 years, respectively, after surgery. Return to sports and rehabilitation was also assessed.

RESULTS

The IKDC, Lysholm, and VISA-P scores all significantly improved at 1 and 3 years' follow-up. The average preoperative IKDC score of 51.6 improved to 86.4 at both the 1- and 3-year stage. The average preoperative Lysholm score of 52.3 improved to 94.7 at 1-year follow-up and was 95.5 at 3-year follow-up. The average preoperative VISA-P score of 35.3 improved to 69.8 at the 1-year stage and was 70.7 at the 3-year follow-up. These scores remained significantly better for the patients assessed at 5 and 10 years' follow-up. There were no postoperative complications. Nineteen of the 27 professional athletes returned to sports at the same level. Seven patients developed pain after sports within 3 years after the operation, a failure rate of 7 of 73 knees (9.6%). All patients were able to return to sports by 3 months.

CONCLUSION

Arthroscopic surgery for patients with patellar tendinopathy, refractory to nonoperative management, appears to provide significant improvements in symptoms and function, with improvements maintained for at least 3 years. These results suggest that some patients may not be able to achieve their presymptom sporting level; or if they do, they may participate in sports with some degree of residual symptoms. Limited data show that these improvements are maintained for up to 10 years. Early return to sports may also be achieved.

Epidemiology of patellar tendinopathy in elite male soccer players

BACKGROUND

Patellar tendinopathy is common among athletes in jumping sports and in sports with prolonged repetitive stress of the knee extensor apparatus. The epidemiology in soccer is not well described.

PURPOSE

This study was undertaken to investigate and describe the epidemiology of patellar tendinopathy in elite male soccer players and evaluate potential risk factors.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Between 2001 and 2009, the authors followed 51 European elite soccer clubs (2229 players) from 3 different cohorts: the Swedish First League cohort (SWE) and Union of European Football Associations (UEFA) Champions League cohort (UCL), both playing on natural grass; and the Artifical Turf cohort (ART), playing on third-generation artificial turf. Individual player exposure in training and matches and time-loss injuries were recorded.

RESULTS

In total, 137 patellar tendinopathies were recorded, comprising 1.5% of all injuries and corresponding to an incidence of 0.12 injuries/1000 hours. Each season, 2.4% of players were affected, with most injuries (61%) resulting in absence up to 1 week or less. Twenty percent of tendinopathies were recurrent complaints. No significant difference in season prevalence (odds ratio [OR], 0.93; 95% confidence interval [CI], 0.60-1.44; P = .74) or incidence (rate ratio [RR] 1.20; 95% CI, 0.82-1.75; P = .36) was observed between teams playing on artificial turf and natural grass, respectively. Multivariate logistic regression showed that a high total exposure hours (OR, 1.02 per 10-hour increase; 95% CI, 1.00-1.04; P = .033) was a significant risk factor for patellar tendinopathy, and increased body mass was borderline significant (OR, 1.15 per 5-kg increase; 95% CI, 1.00-1.33; P = .055). In addition, 2 acute partial tendon ruptures were recorded, but no total rupture.

CONCLUSION

Although mainly mild in nature, patellar tendinopathy is a fairly common condition in elite soccer and the recurrence rate is high. Exposure to artificial turf did not increase the prevalence or incidence of injury. High total amount of exposure was identified as a risk factor for patellar tendinopathy.

Tendinopathy in athletes

Overuse related tendon pain is a significant problem in sport and can interfere with and, in some instances, end an athletic career. This article includes a consideration of the biology of tendon pain including a review of tendon anatomy and histopathology, risk factors for tendon pain, semantics of tendon pathology, and the pathogenesis of tendon pain. Evidence is presented to guide the physical therapist in clinical decision-making regarding the examination of and intervention strategies for athletes with tendon pain.

What are the validated animal models for tendinopathy?

Chronic tendinopathy refers to a broad spectrum of pathological conditions in tendons and their insertion, with symptoms including activity-related chronic pain. To study the pathogenesis and management strategies of chronic tendinopathy, studies in animal models are essential. The different animal models in the literature present advantages and limitations, and there is no consensus regarding the criteria of a universal tendinopathy animal model. Based on the review of literature and the discussion in the International Symposium on Ligaments and Tendons-X, we concluded that established clinical, histopathological and functional characteristics of human tendinopathy were all important and relevant criteria to be met, if possible, by animal models. As tendinopathy is a progressive, multifactorial tendon disorder affecting different anatomical structures, it may not be realistic to expect a single animal model to study all aspects of tendinopathy. Staging of tendinopathy over time and clearer definition of tendinopathies in relation to severity and type would enable realistic targets with any animal model. The existing animal models can be used for answering specific questions (horses for courses) but should not be used to conclude the general aspects of tendinopathy neither in animals nor in human.

Landing strategies of athletes with an asymptomatic patellar tendon abnormality

PURPOSE

Risk factors associated with a clinical presentation of patellar tendinopathy are patellar tendon ultrasonographic abnormality (PTA) and excessive loading. It remains unknown whether characteristics of an athlete's landing technique contribute to this excessive patellar tendon loading. This study investigated whether asymptomatic athletes with and without PTA had different landing strategies and hypothesized that asymptomatic athletes with a PTA would create higher patellar tendon loading and a different lower-limb landing strategy compared with athletes with normal patellar tendons.

METHODS

Seven athletes with no previous history or clinical signs of patellar tendon injury with a PTA were matched to athletes with normal patellar tendons (controls). Participants performed five successful trials of a stop-jump task, which involved a simultaneous two-foot horizontal and then vertical landing. During each trial, the participants' ground reaction forces and lower-limb electromyographic data were recorded, the three-dimensional kinematics measured, and the peak patellar tendon force calculated by dividing the net knee joint moment by the patellar tendon moment arm.

RESULTS

Significant between-group differences in landing technique were mostly observed during the horizontal landing phase. Participants with a PTA created similar patellar tendon loading to the controls, but with altered sequencing, by landing with significantly greater knee flexion and extending their hips while the controls flexed their hips as they landed, reflecting a different muscle recruitment order compared with the PTA group.

CONCLUSIONS

The crucial part in the development of PTA and, in turn, patellar tendinopathy may not be the magnitude of the patellar tendon load but rather the loading patterns. This research provides clinicians with important landing assessment criteria against which to identify athletes at risk of developing patellar tendinopathy.