Article

Exploration of the current evidence base for the incidence and prevalence of patellofemoral pain syndrome

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Abstract

Objectives: No consensus has been reached regarding the incidence and prevalence of patellofemoral pain syndrome (PFPS). This literature review aims to explore and present research conducted on the incidence and prevalence data for PFPS to date. Methods: The literature search employed databases Ovid SP, AMED, Ovid Medline (R) and EMBASE, accessed via the University of Central Lancashire Library Online service, and search terms 'adolescen*' 'anterior knee pain', 'incidence', 'outcome measure', 'patellofemoral pain', 'patellofemoral pain syndrome', 'prevalence', 'questionnaire' and 'response rate'. All articles were filtered by hand to determine relevance, as were reference lists of applicable studies/reviews to identify key articles. Pertinent journals were included as recommended by a specialist in the field. Results: Ten studies were selected for review, spanning 22 years of study that apparently focused on incidence over prevalence. Despite a lack of United Kingdom based research, this topic is of international interest. The participant groups demonstrate a large age span, comprising mainly military recruits, along with students, healthcare patients and athletes. The selection and definition of terminology differed greatly, as did methodologies, specifically the data collection tools. Despite questionnaires being well suited to incidence and prevalence data collection, none were identified as being valid and reliable. Discussion: Two major research gaps were identified: investigation into PFPS prevalence (and incidence) within athletic adolescents, and the development of a questionnaire to collect incidence and or prevalence data. Such research could facilitate clinical practice and the development of health strategies.

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... Patellofemoral pain syndrome (PFPS) is defined as pain around the patella due to activities (squats, running, climbing, etc.) that load the patellofemoral joint without pathological changes [1,2]. It is a common problem among adolescents and young adults, and the annual prevalence of patellofemoral pain in the general population was reported to be 22.7 and 28.9% in adolescents [3][4][5]. ...
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Background: Patellofemoral pain syndrome (PFPS) is defined as pain around the patella while performing activities such as squats, running, and climbing steps. One of the inherent risk factors for PFPS is an excessively pronated foot posture. The aim of this study was to investigate the effect of foot intervention, talonavicular joint mobilization (TJM) and foot core strengthening (FCS), on PFPS. Methods: Forty-eight patients with PFPS (mean age, 21.96 ± 2.34 years; BMI, 22.77 ± 2.95 kg/m2) were enrolled in the study. Participants were randomly assigned in a 1:1:1 ratio to three groups, and received 12 sessions of TJM, FCS, and blended intervention at university laboratory for 4 weeks. The primary outcomes were pain while the secondary outcomes were lower extremity function, valgus knee, foot posture, and muscle activity ratio measured at baseline, after 12 sessions, and at the 4-week follow-up. Results: The two-way repeated-measures ANOVA revealed significant interactions in all groups (p < 0.05). TJM reduced pain more than the FCS at post-test (mean difference, - 0.938; 95% Confidence interval [CI], - 1.664 to - 0.211; p < 0.05), and blended intervention improved lower extremity function (mean difference, 6.250; 95% CI, 1.265 to 11.235; p < 0.05) and valgus knee (mean difference, - 11.019; 95% CI, - 17.007 to - 5.031; p < 0.05) more than the TJM at 4 weeks follow-up. TJM was more effective in post-test (mean difference, - 1.250; 95% CI, - 2.195 to - 0.305; p < 0.05), and TJM (mean difference, - 1.563; 95% CI, - 2.640 to - 0.485; p < 0.05) and blended intervention (mean difference, - 1.500; 95% CI, - 2.578 to - 0.422; p < 0.05) were more effective in foot posture than the FCS in 4 weeks follow-up. Blended intervention displayed greater improvement in muscle activity than the TJM (mean difference, 0.284; 95% CI, 0.069 to 0.500; p < 0.05) and the FCS (mean difference, 0.265; 95% CI, 0.050 to 0.481; p < 0.05) at 4 weeks follow-up. Conclusions: Our study is a novel approach to the potential impact of foot interventions on patellofemoral pain. Foot intervention including TJM and FCS is effective for pain control and function improvement in individuals with PFPS. Trial registration: KCT0003176 , 16/08/2018 (retrospectively registered).
... Understanding the contributing factors related to PFP could be of a great value in controlling and preventing such syndrome, however, the prevalence of PFP vary greatly in literature 13 . The incidence of PFP is predominantly documented in teenagers 14 . ...
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Patellofemoral Pain (PFP) is frequently described as clinical knee pain influencing adolescents and physically active adults; however, prevalence and risk factors in a large-scale population is not well established. This study aimed to investigate the prevalence of PFP in Majmaah, Saudi Arabia; and to interpret the influence of factors such as age, gender and BMI on the prevalence of PFP. Two hundred and forty-eight subjects including males and females were assessed in this study. A crosssectional study was performed in Majmaah Governorate, and surrounding cities, Saudi Arabia. The prevalence of PFP was considerably high among females (72.3%), while it was 27.7% among males. Moreover, the age was a significant predictor for PFP [OR=1.04, 95% CI-1.01-1.07], while the gender and BMI were not significant predictors. Based on these results, PFP is a commonly reported knee condition among adolescents. Apart from gender factor, overweight persons appear to be more liable to develop PFP. Moreover, increasing age is strongly associated with increasing risk of PFP.
... 16 The total incidence for PFPS ranges from 8.75% to 17%; however, the incidence among females is much greater at 12.7% compared to 1.1% of males. 17 Young females who regularly participate in running and jumping activities may be particularly at risk. 2 In a clinical analysis of 40 women with PFPS, pain was associated with increased activity. Chronic overloading and overuse of the patellofemoral joint, rather than malalignment, can also contribute to patellofemoral pain. ...
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Patellofemoral pain syndrome (PFPS) is one of the most common causes of knee pain and is present in females disproportionately more relative to males. PFPS causes tend to be multifactorial in nature and are described in this review. From a review of the current literature, it is clear that there needs to be further research on PFPS in order to better understand the complex eti-ology of this disorder in both males and females. It is known that females with patellofemoral pain syndrome demonstrate a decrease in abduction, external rotation and extension strength of the affected side compared with healthy patients. Conservative management, including optimizing muscle balance between the vastus medialis and lateralis around the patella along with formal therapy should be the first line of treatment in patients presenting with PFPS. Surgery should be reserved for patients in which all conservative management options have failed. This review aims to guide physicians in accurate clinical-decision making regarding conservative and surgical treatment options when specifically faced with PFPS in a female athlete. Furthermore, we will discuss the anatomic variants, incidence and prevalence, etiology, diagnosis and treatment of PFPS.
... The prevalence of AKP may be as high as 12-16% in female athletes, 1,2 and it is the most common dysfunction in runners. 3 The risk of an ACL tear is also greater for females than males. According to a meta-analysis by Promodromos et al., 4 female basketball and soccer athletes have a 5% risk of an ACL tear annually. ...
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Background: Physical therapists commonly treat individuals with anterior knee pain (AKP) and anterior cruciate ligament (ACL) injuries. Despite the suggestion for including hip strengthening or neuromuscular control exercises in preventative programs to change knee mechanics and reduce AKP and ACL injuries and in the treatment of AKP, no previous systematic review has addressed the impact of these exercises on frontal plane knee mechanics. Objective: The purpose of this systematic review was to determine the level of evidence associated with hip strengthening or neuromuscular control exercises as an intervention to improve frontal plane knee mechanics during dynamic activity in females. Methods: Databases searched included PubMed, CINAHL Plus with full text, and SportDiscus with full text; specific search terms were used. All studies were to include females without any current knee pain or injury. Studies had to investigate the impact of a hip strengthening or a hip neuromuscular control program or a combination of strengthening and neuromuscular control. The primary outcome measure of interest was frontal plane knee mechanics. Results: A total of 414 articles were identified. Eight additional articles were identified using other sources. Fourteen studies were ultimately included in the qualitative analysis. There was support for neuromuscular control exercises as well as neuromuscular control plus strengthening exercises to improve frontal plane knee mechanics during dynamic activity in females. Strengthening alone was not supported. Conclusion: Clinically, one should consider either a neuromuscular control program or a combined neuromuscular control plus strength training program for females to improve frontal plane knee mechanics during dynamic activity. This may be particularly relevant in prevention of ACL injuries and AKP.
... Patellofemoral pain syndrome (PFPS), often described as anterior knee pain involving the patella or retinaculum, has a prevalence of 12e13% in females ages 18e35 (Roush & Curtis Bay, 2012). PFPS is the most common injury among runners, and increased physical activity is a risk factor for PFPS (Oakes, McCandless, & Selfe, 2009). Despite the high prevalence, the exact etiology is still unknown and a multifactorial clinical diagnosis is typically made as other conditions are ruled out. ...
Article
Objective The purpose of this study was to examine the relationship between frontal plane kinematics of the single leg squat and strength of the trunk and hip in females. Participants Forty healthy females participated in this study. Methods An isometric “make” test using a dynamometer was used to assess peak force normalized to body weight for hip abduction, hip extension, hip external rotation, and a sidelying plank test. Two-dimensional software was used to analyze the frontal plane projection angle (FPPA) and pelvic angle during a single leg squat to 60°. Results All 4 strength factors were significantly correlated with the FPPA, ranging from r=0.396 to r=0.466. During multiple regression analysis, hip abduction strength was the greatest predictor of the variation in FPPA at r2=0.22, p =0.002. Thus, hip abduction strength accounted for 22% of the variation in the FPPA during the single leg squat. The only strength factor demonstrating a significant correlation with the pelvic angle was hip extension strength (r=0.550, p<0.001). Conclusion Clinicians should consider the role of the hip abductors, hip external rotators, hip extensors and core musculature on the impact on the FPPA during a single squat, with focus on the hip abductors.
Article
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Patellofemoral pain (PFP) is a common musculoskeletal-related condition that is characterized by insidious onset of poorly defined pain, localized to the anterior retropatellar and/or peripatellar region of the knee. The onset of symptoms can be slow or acutely develop with a worsening of pain accompanying lower-limb loading activities (eg, squatting, prolonged sitting, ascending/descending stairs, jumping, or running). Symptoms can restrict participation in physical activity, sports, and work, as well as recur and persist for years. This clinical practice guideline will allow physical therapists and other rehabilitation specialists to stay up to date with evolving PFP knowledge and practices, and help them to make evidence-based treatment decisions. J Orthop Sports Phys Ther. 2019;49(9):CPG1-CPG95. doi:10.2519/jospt.2019.0302.
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Among 7,785 patients examined with knee problems, 370 were diagnosed with patellofemoral pain syndromes. Examination and treatment were performed using a systematic approach. The patients were placed on a conservative program consisting of a four-stage progression, with the goal of relieving symptoms and returning to full activity. The results of this approach showed that 77% recovered. to a satisfactory level and 23% were unsatisfactory and underwent surgical procedures. J Orthop Sports Phys Ther 1981;2(3):108-116.
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In order to investigate the strength of any relationship between knee pain and disability, a postal questionnaire was sent to 2102 men and women aged over 55 registered at a general practice in Bristol. A response rate of 80.6% was achieved at second reminder. Knee pain was common particularly in women (27.6% overall). Disability was also more frequently reported in women (P less than 0.05) and rose with increasing age. Respondents with knee pain had significantly more disability relating to upper as well as lower limb activities (P less than 0.05).
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Mechanical abnormalities of the patellofemoral joint are among the many causes that have been suggested for adolescent knee pain. This study seeks to identify these factors. Measurements of joint mobility and lower limb morphology were made on 446 pupils at a comprehensive school, 136 of whom had suffered knee pain in the previous year. The pupils with symptoms enjoyed sporting activities significantly more than their symptom-free contemporaries. Joint mobility, the Q-angle, genu valgum and anteversion of the femoral neck were not significantly different between those pupils with and those without anterior knee pain. Data on lower limb morphology of normal adolescents are presented. Examination of 52 hospital outpatients aged 13 to 36 years with anterior knee pain produced results comparable with those for the pupils. It is concluded that chronic overloading, rather than faulty mechanics, is the dominant factor in the genesis of anterior knee pain in adolescent patients.
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In a prospective clinical examination of 78 knees in 60 young patients with patellofemoral pain, pain occurred frequently in the lateral peripatellar retinaculum, sometimes in association with milder, less well defined medial patellar discomfort. Patellofemoral pain in the young person is frequently a soft tissue problem initially, but aberrant mechanics (particularly lateral tracking) that cause this retinacular overuse and pain may eventually lead to synovial irritation and chondromalacia. Chondromalacia, however, may not be the primary cause of patellofemoral pain in many young people.
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Many variables have retrospectively been associated with the presence of anterior knee pain. Very few prospective data exist, however, to determine which of these variables will lead to the development of anterior knee pain. It was our purpose in this study to determine the intrinsic risk factors for the development of anterior knee pain in an athletic population over a 2-year period. Before the start of training, 282 male and female students enrolled in physical education classes were evaluated for anthropometric variables, motor performance, general joint laxity, lower leg alignment characteristics, muscle length and strength, static and dynamic patellofemoral characteristics, and psychological parameters. During this 2-year follow-up study, 24 of the 282 students developed patellofemoral pain. Statistical analyses revealed a significant difference between those subjects who developed patellofemoral pain and those who did not concerning quadriceps and gastrocnemius muscle flexibility, explosive strength, thumb-forearm mobility, reflex response time of the vastus medialis obliquus and vastus lateralis muscles, and the psychological parameter of seeking social support. However, only a shortened quadriceps muscle, an altered vastus medialis obliquus muscle reflex response time, a decreased explosive strength, and a hypermobile patella had a significant correlation with the incidence of patellofemoral pain. We concluded that the latter four parameters play a dominant role in the genesis of anterior knee pain and we therefore deem them to be risk factors for this syndrome.
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Article
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Patellofemoral pain syndrome can be a difficult condition to manage effectively. The success rate of most treatment regimes has been poor and in the long term the condition frequently recurs. The author has developed a treatment programme which has a ninety-six percent success rate. Long term follow up of patients, after twelve months demonstrated that all patients reviewed have remained pain free. The programme involves two major components: a thorough understanding of the mechanics of the patellofemoral joint so that an adequate assessment of the patient's lower limb can be made, and context specific training of certain muscles which contribute to patellar alignment. This training must be relatively pain free so that muscle control can be enhanced.
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Patellofemoral pain has been considered a difficult condition to manage effectively. Clinical trials of the McConnell programme have demonstrated excellent results from this approach. The programme aims to identify and treat the biomechanical factors which may be adversely effecting patellar tracking.
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Background and purpose: The aims of this paper were to investigate the cited incidence, and to establish the source data for quoted figures, ratios, prevalence or incidence of patellofemoral pain syndrome (PFPS) for the British general adult population. Method: A literature search of all English language peer reviewed publications from January 2000 to December 2005 with the search terms 'patellofemoral pain', 'patellofemoral pain syndrome' and 'anterior knee pain'. Results: Of the papers retrieved, 40 cited some sort of percentage figure or a ratio for the incidence or prevalence of PFPS. An incidence rate for PFPS of 25% (or 1:4) was cited in 13/40 papers, but other incidence rates cited ranged from 3% to 40%. There seemed to be 4 key references that other authors used to substantiate their cited values for PFPS prevalence or incidence or rate. There were no epidemiological papers studying the incidence or prevalence of PFPS in the United Kingdom. Conclusion: The evidence for the cited incidence of PFPS or anterior knee pain in the adult general population is taken almost entirely from source data in the sports medicine or the military settings. Of these, only one was set in the United Kingdom. We conclude that the prevalence of PFPS in the United Kingdom has not been properly evaluated and consequently there is clearly a need for a study on the incidence rates of PFPS in this country's general population.
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A review of the clinical records of two sports physicians identified 1,819 injuries in 1,650 running patients during a two-year period. Men comprised 59.8% of the total patients, and women under age 30 appeared to have the greatest risk of overuse running injuries. The knee was the most common site of complaint, accounting for 41.7% of all injuries. The least frequently involved areas were the lower back (3.7%) and upper leg (3.6% of total injuries). All anatomical regions were equally susceptible to injury in both sexes. Patellofemoral pain syndrome was the most frequent disorder, accounting for 25.8% of all injuries. Most patients had moderate to severe varus alignment and subsequent functional overpronation. Certain injuries were more frequent in one sex or the other, so we believe that our results should prompt other authors to differentiate incidence of injuries by sex in the future.
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Patellofemoral disorders continue to present as some of the most common and challenging pathologic conditions of the orthopedic and sports medicine community. Numerous surgical and rehabilitative approaches have been suggested to treat patients with such conditions, but no single approach has been shown to be the most beneficial because of the numerous etiologic factors associated with patellofemoral pain. Rehabilitation programs should be implemented based on a thorough clinical evaluation and continuously modified based on the unique and specific presentation of each patient. Early emphasis is placed on eliminating pain and inflammation. In addition, reestablishing soft tissue and muscular balance is an essential component to patellofemoral rehabilitation programs. As the patient improves, the rehabilitation program is advanced in a progressive and sequential manner to ensure that adequate stress is applied to the injured tissues to facilitate healing while minimizing detrimental loads. This article outlines specific treatment principles commonly associated with nonoperative and postoperative patellofemoral management to restore function as quickly and safely as possible.
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Background and Purpose This work represents part of a PhD project investigating outcome measures for patellofemoral joint problems – critical angle and angular velocity as measured by video analysis of an eccentric step test, a treadmill test and a Modified Functional Index Questionnaire (MFIQ). This paper describes the development of the outcome measures and provides experimental data to support their validity. Methods A controlled repeated measures study was carried out in the physiotherapy department at Burnley General Hospital, where 88 patients were considered for inclusion. Comparing experimental data collected from the patients with those previously published provided estimates of the validity of the outcome measures. Results Mean critical angle was 57.8° and mean angular velocity was 93°/sec. The eccentric step test was found painful by 74% of patients. Data from the treadmill test were right censored with 49% of patients completing 300 seconds without pain. Cronbach's alpha for the MFIQ was 0.83. Conclusion When comparing video data from this patient group to a previous study of 100 healthy subjects the patients demonstrate an earlier critical angle and faster angular velocity. These data suggest that the measurements of critical angle and angular velocity through video analysis of an eccentric step test are valid measures of patellofemoral joint dysfunction. As treadmill test data are right censored it suggests that the test in the form used in this study is valid for only about 50% of the patients. The high value recorded for Cronbach's alpha suggests that the MFIQ is internally consistent, which in turn suggests it is also a valid measure of patellofemoral dysfunction.
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This study determined gender differences in voluntary reporting of lower extremity musculoskeletal injuries among U.S, Marine Corps (USMC) recruits, and it examined the association between these differences and the higher injury rates typically found among women trainees. Subjects were 176 male and 241 female enlisted USMC recruits who were followed prospectively through 11 wk (men) and 12 wk (women) of boot camp training. Reported injuries were measured by medical record reviews. Unreported injuries were determined by a questionnaire and a medical examination administered at the completion of training. Among female recruits the most commonly reported injuries were patellofemoral syndrome (10.0% of subjects), ankle sprain (9.1%), and iliotibial band syndrome (5.8%); the most common unreported injuries were patellofemoral syndrome (2.1%), metatarsalgia (1.7%), and unspecified knee pain (1.7%). Among male recruits iliotibial band syndrome (4.0% of subjects), ankle sprain (2.8%), and Achilles tendinitis/bursitis (2.8%) were the most frequently reported injuries; shin splints (4.6%), iliotibial band syndrome (4.0%), and ankle sprain (2.8%) were the most common unreported diagnoses. Female recruits were more likely to have a reported injury than male recruits (44.0% vs 25.6%, relative risk (RR) = 1.72, 95% confidence interval (CI) 1.29-2.30), but they were less likely to have an unreported injury (11.6% vs 23.9%, RR = 0.49, 95% CI 0.31-0.75). When both reported and unreported injuries were measured, total injury rates were high for both sexes (53.5% women, 45.5% men, RR = 1.18, 95% CI 0.96-1.44), but the difference between the rates was not statistically significant. Our results indicate that the higher injury rates often found in female military trainees may be explained by gender differences in symptom reporting.
Article
This work represents part of a PhD project investigating outcome measures for patellofemoral joint problems – critical angle and angular velocity as measured by video analysis of an eccentric step test, a treadmill test and a Modified Functional Index Questionnaire (MFIQ). This paper presents the results of a clinical trial that investigated the issues of reliability, clinical sensitivity and agreement between the outcome measures.
Article
The causes of women's sports injuries are currently a topic of vigorous speculation in sports medicine. Research has yet to clearly link gender to any injury etiology. Meanwhile, physicians are analyzing gender differences to find ways that women can better condition themselves for sports, avoid injuries, and recover quickly from the injuries that do occur. An analysis of the most common problems active women face (anterior cruciate ligament, patellofemoral, shoulder, and foot injuries) suggests effective strategies for diagnosis, treatment, rehabilitation, and prevention.
Article
This project was supported by a grant from the Physiotherapy Foundation of Canada. The purpose of this study was to determine the reliability and validity of the following outcome measures in a group of 18 patients with patellofemoral pain syndrome: the visual analog pain scale (VAS), a functional index questionnaire (FIQ), selected temporal components of gait on level walking and ascending stairs, knee joint angle on downhill walking, and electromyographic activity of the quadriceps during stair climbing. Subjects were tested at initial assessment (time 0), after 24 hours (time 1), and after clinically significant improvement, following a course of treatment (time 2). Using the intraclass correlation coefficient (r1), the VAS (r1 = 0.603) and FIQ (r1 = 0.483) exhibited poor day-to-day reliability (time 0 versus time 1). However an ANOVA between time 0 and time 2 showed them to be valid measures for detection of clinical change (p < 0.01). No differences in the gait variables were observed from time 0 to time 1 or time 2, suggesting that gait analysis may not be sensitive enough to detect changes in pain and function in this patient population. J Orthop Sports Phys Ther 1989;10(8):302-308.
Article
A prospective study of 390 infantry recruits revealed that the medial tibial intercondylar distance and that the isometric strength of the quadriceps, tested at 85 degrees of flexion of the knee, had a statistically significant correlation with the incidence of patellofemoral pain caused by overactivity. Increased medial tibial intercondylar distance and increased strength of the quadriceps were therefore deemed to be risk factors for this syndrome.
Article
Injuries treated at the University of Rochester Section of Sports Medicine over a 7 year period were surveyed. Patients were drawn from professional, intercollegiate (Division III), high school, intramural, and unorganized athletics at the University and the surrounding community. Data on injury diagnosis was available for 4,551 cases, with data on age, gender, and sport of injury available for 3,431 of the cases. The average patient age was 21.6 years, with a peak in the 16 to 19 age group. Patients with fractures had an average age below the overall mean, while those with internal derangement of the knee, patellofemoral pain syndrome, and inflammatory injuries were significantly older than average. Males accounted for 80.3% of all injuries. For both sexes the most common areas injured were the knee and ankle, with sprains/strains the most common injuries. Injuries involving the patellofemoral articulation were significantly more frequent among females. The most common sport of injury was football, with greater than 12 times the number of injuries seen in the next most common sport.
Article
At the Tampere Research Station of Sports Medicine (TRSSM) a continuous coding system of patient visits was started on March 1, 1985. The registration form contained 25 variables including all essential informa tion about the patient's identification, sports, time of and reason for the visit, physician, examinations, diag nosis, treatment, and possible further measures. To classify and number the diagnosis, a specific classifi cation of sports injuries and diseases was drawn up. The data were stored and analyzed using a DEC-2060 computer at the University of Tampere. During 6 months a total of 814 visits were recorded. The three most common sports were soccer, long- distance running, and orienteering. Competitive ath letes totalled 337 (62%); 43 of these were top-ranking athletes. The most common reasons for visits were problems of the knee (266 visits, 33%), ankle (80, 10%), and low back (71, 9%). Knee sprains accounted for 10% of all visits. Problems related to the musculoskeletal system were the reason for 751 (92%) of all visits. Operative treatment was needed by 49 patients (6%). The continuous coding system of patient visits at an outpatient sports clinic showed great advantages as a basic data bank for scientific research, annual statistics, and patient identification and filing. The system de scribed has been adopted as part of the daily routine at the TRSSM.
Article
This prospective study examined running history as a risk factor for subsequent overuse injury in Navy Sea, Air, and Land (SEAL) recruits. Recruits preparing to be Navy SEALs undergo 6 months of rigorous physical training programs, which place these recruits at high risk for developing an overuse injury. We assessed the independent variables of age; prior running frequency, duration, and pace; and training surface. Univariate and multivariate estimates of risk were determined for each variable. We observed an incidence of 3.4 overuse injuries per 1000 recruit-days. Assessing the physical activity of the recruits in the 6 months before entrance into basic train ing, we found that the recruits who ran at a pace slower than 8 minutes per mile and on softer training surfaces were more likely to sustain an overuse injury during ba sic training, in both univariate and multivariate esti mates of risk. Recruits who ran fewer weekly miles and for shorter durations before basic training were also more likely to sustain an overuse injury according to univariate estimates of risk. Our findings suggest that risk of overuse injuries can be reduced by adjusting exercise routines before train ing. Running on different type surfaces with a gradual increase in speed, duration, and weekly mileage in the period preceding basic training may reduce risk of overuse injury.
Article
A study was undertaken to document the incidence of overuse injuries sustained during basic military training. The injuries in military recruits (N = 1,261) undergoing basic training were documented prospectively over a 9-week period. Injury incidence was expressed as percentage of all recruits injured, weekly incidence (injuries/1,000 recruits/week), and injuries/1,000 training hours. The incidence of six common specific overuse injuries was also recorded. The overall incidence of injuries over the 9-week period was 31.9% (acute, 13.6%; overuse, 86.4%), or 1.8/1,000 training hours. The highest incidence of injuries was recorded in weeks 1 to 3 and week 9 of training, which were weeks characterized by marching ( > 77% of the training time). The highest incidence (injuries/1,000 training hours) of specific overuse injuries were tibial bone stress reaction (0.33), patellofemoral pain (0.22), and the iliotibial band friction syndrome (0.08). The incidence of stress fractures over the 9-week period was 1.2% (0.07/1,000 training hours). Injuries to the knee, lower leg, and ankle accounted for more than 80% of all injuries. A total of 3.6% of training days were lost during this period, mainly due to bone stress injuries. In order to reduce injuries during basic military training, attention must be directed towards (1) modifying the type of training and (2) prevention of bone stress injuries.
Article
It is widely acknowledged that musculoskeletal injuries occur as a result of vigorous physical activity and exercise, but little quantitative documentation exists on the incidence of or risk factors for these injuries. This study was conducted to assess the incidence, types, and risk factors for training-related injuries among young men undergoing Army infantry basic training. Prior to training we evaluated 303 men (median age 19 yr), utilizing questionnaires and measurements of physical fitness. Subjects were followed over 12 wk of training. Physical training was documented on a daily basis, and injuries were ascertained by review of medical records for every trainee. We performed univariate and multivariate analyses of the data. Cumulative incidence of subjects with one or more lower extremity training-related injury was 37% (80% of all injuries). The most common injuries were muscle strains, sprains, and overuse knee conditions. A number of risk factors were identified, including: older age, smoking, previous injury (sprained ankles), low levels of previous occupational and physical activity, low frequency of running before entry into the Army, flexibility (both high and low), low physical fitness on entry, and unit training (high running mileage).
Article
A new questionnaire was used to evaluate subjective symptoms and functional limitations in patellofemoral disorders. The questionnaire was completed independently by four groups of female subjects: controls (N = 17), and subjects with anterior knee pain (N = 16), patellar subluxation (N = 16), and patellar dislocation (N = 19). The questionnaire mean scores for the groups were 100, 83, 68, and 62 points, respectively (p < 0.0001). The items dealing with abnormal painful patellar movements (subluxations) (p < 0.0001), limp (p < 0.0001), pain (p < 0.0001), running (p < 0.0001), climbing stairs (p < 0.0001), and prolonged sitting with the knees flexed (p < 0.0001) differentiated the study groups most clearly. We recommend that these questions be asked when taking a standardized clinical history of an anterior knee pain patient. We also analyzed lateral patellar tilt and displacement by magnetic resonance imaging (MRI) in 28 subjects with patellar subluxation or dislocation. Low questionnaire sum score correlated best with increased lateral patellar tilt measured during quadriceps contraction in 0 degree knee flexion. It seems that a tendency to lateral patellar tilt during quadriceps contraction causes anterior knee pain and can be imaged in knee extension when the patella is not fully supported by femoral condyles.
Article
The effect of anatomic variation on the risk of overuse injuries has not been adequately evaluated. To determine the association of several common anatomic characteristics (genu varum, genu valgum, genu recurvatum, and lower limb length differences) with risk of overuse injury, we made prospective morphologic measurements of young men prior to beginning 12 week of Army infantry training. The training included frequent running, marching, calisthenics, and other vigorous activities. Lower extremity anatomic landmarks were high-lighted, and front- and side-view photographic slides were taken of the 294 study volunteers. The slides were compute digitized, and the following measures calculated: pelvic width to knee width ratio (to assess genu valgum/varum), quadriceps angle (Q-angle), knee angle at full extension, and lower limb length differences. The cumulative incidence of lower limb overuse injury was 30%. Relative risk of (RR) of overuse injury was significantly higher among participants with the most valgus knees (RR = 1.9). Those with Q-angle of more than 15 degrees had significantly increased risk specifically for stress fractures (RR = 5.4). Anatomic characteristics were associated with several other types of injuries, including pain and nonacute muscle strain due to overuse. This pilot study provides evidence that some lower limb morphologic characteristics may place individuals at increased risk of overuse injuries.
Article
In a prospective study to determine the natural history of anterior knee pain caused by overactivity, 60 (15%) of 390 elite Israeli infantry recruits were found to have anterior pain in 77 knees during 14 weeks of basic training. At 6 years' followup, 3 years after returning to civilian life, half of the knees originally with anterior knee pain were still symptomatic, but in only 8% of the originally symptomatic knees was the pain severe, hindering physical activity. The long term prognosis of anterior knee pain caused by overactivity is much better than that reported previously for anterior knee pain in adolescents, but in a small percentage of cases the pain persists at a level that may prevent participation in exertional activities.
Article
To document the conditions seen by medical practitioners at a multidisciplinary sports medicine clinic during a 12-month period on the basis of site of injury, pathology, and sport played. A coding system for anatomical region, pathology, and sport played was designed. The total number of patient diagnoses coded and entered for analysis was 2,429. The most common sports involved were Australian football 322 (13.3%), distance running 299 (12.3%), netball/basketball 210 (8.6%), racquet sports 140 (5.8%), and track running 135 (5.6%). The most commonly injured region was the knee with 668 presentations (27.5%), followed by the upper limb (8.8%). The most frequently diagnosed pathology was overuse/inflammation with 1,115 (45.9%). Other pathologies diagnosed were partial ligament sprains 316 (13.0%), muscle strain 99 (4.1%), compartment syndrome 85 (3.5%), and third-degree ligament tear (3.5%). The most common diagnoses seen were patellofemoral syndrome, lumbar spine disorders, rotator cuff tendinitis, lateral ligament ankle sprain, medial meniscus tear, medial collateral ligament knee sprain, lateral meniscus tear, achilles tendinosis, anterior cruciate ligament tear and sacroiliac joint inflammation. A study of this nature provides valuable information both to the epidemiologist and clinician.
Article
Patellofemoral pain is one of the most common knee disorders seen in orthopaedic practice. Despite its high incidence, treatment of this disorder remains controversial. Traditionally, nonoperative management of patellofemoral pain has focused on restoring normal patellar tracking by improving dynamic stability. Of particular interest to clinicians has been the vastus medialis oblique, which has been implicated as being the primary medial stabilizer of the patella. Although emphasis on the vastus medialis oblique continues to be the mainstay of conservative care of patellofemoral pain, there exists considerable disagreement between research outcomes and clinical practice. This article critically reviews the current literature concerning the treatment of patellofemoral pain with respect to the vastus medialis oblique, taping, and bracing, as well as various forms of therapeutic exercise, and relates these findings to the prevailing views regarding the management of this disorder.
Article
The purpose of this study was to identify rates of diagnosis-specific musculoskeletal injuries in U.S. Marine Corps recruits and to examine the association between patterns of physical training and these injuries. Subjects were 1,296 randomly selected male Marine recruits, ages 17 to 28 yr, who reported to Marine Corps Recruit Depot San Diego for boot camp training between January 12 and September 14, 1993. Recruits were followed prospectively through 12 wk of training for injury outcomes. Injury patterns were examined in relation to weekly volumes and types of vigorous physical training. The overall injury rate was 39.6% (number of recruits injured/population at risk), with 82% of injuries occurring in the lower extremities. Overuse injuries accounted for 78% of the diagnoses. The most frequent site of injury was the ankle/foot region (34.3% of injuries), followed by the knee (28.1%). Ankle sprains (6.2%, N = 1,143), iliotibial band syndrome (5.3%, N = 1,143), and stress fractures (4.0%, N = 1,296) were the most common diagnoses. Injury rates were highest during the weeks with high total volumes of vigorous physical training and the most hours of running and marching. Weekly injury rates were significantly correlated with hours of vigorous physical training (overuse injuries r = 0.667, P = 0.018; acute injuries r = 0.633, P = 0.027). The results of this controlled epidemiological investigation indicate that volume of vigorous physical training may be an etiologic factor for exercise-related injuries. The findings also suggest that type of training, particularly running, and abrupt increases in training volume may further contribute to injury risk.
Article
Anterior knee pain (AKP) is a common pathological condition, particularly among young people and athletes, associated to an abnormal motion of the patella during the bending of the knee and possibly dependent on a muscular or structural imbalance. A lack of synergy in the quadriceps muscles results in a dynamic misalignment of the patella, which in turn produces pain. AKP rehabilitative therapy consists of conservative treatment whose main objective is to strengthen the Vastus Medialis. The aim of this article is to study the quadriceps muscle control strategy in AKP patients during an isokinetic exercise. Analysis of the muscle activation strategy is important for an objective measurement of the knee functionality in that it helps to diagnose and monitor the rehabilitative treatment. Surface electromyography (EMG) from the three superficial muscles of the femoral quadriceps during a concentric isokinetic exercise has been analyzed along with the signals of knee joint position and torque. A group of 12 AKP patients has been compared with a group of 30 normal subjects. Analysis of the grand ensemble average of the EMG linear envelopes in AKP patients reveals significant modifications in Vastus Medialis activity compared to the other quadriceps muscles. In order to study the synergy of the muscles, temporal identifiers have been associated to the EMG linear envelopes. To this end, EMG linear envelope decomposition in Gaussian pulses turned out to be effective and the results highlight an appreciable delay in the activation of the Vastus Medialis in AKP patients. This muscular unbalance can explain the abnormal motion of the patella.
Article
Patellofemoral pain is often a challenge for the physiotherapist, because of its complex aetiology. Physiotherapists with their understanding of soft tissue structure and muscle function are well positioned to effectively manage most patellofemoral problems by improving the extensibility and mobility of tight structures and improving the timing of the elongated muscles. This will involve recognising the biomechanical factors contributing to the symptoms, adequately explaining to the patient the cause of the symptoms and teaching the patient how to manage the symptoms. Specific training of certain muscles with accurate feedback to change the timing of these muscles during functional and sporting activities will be required if this problem is not to recur.
Article
By collecting data from 45 students at a ski high school, we found that a total of 73% of the students reported activity-related pain/injuries of the knee. Sixty-one percent had overuse injuries, 27% malalignment, and 12% had indistinct knee pain. Females suffered more knee pain/injuries (88%) than males (57%). Significantly higher Q-angle degrees were recorded for females (16) than for males (10). "Jumper's knee" was found in all competitive students with a KT manual maximum difference (MMD) of 3 mm or more (mean 4 mm), with a hard endpoint, whereas this was less common among the other competitive students (P < 0.05). The students were given counselling about training and physiotherapy. In the follow-up study 1 year later, a significant reduction of knee pain/overuse injuries, from 73% to 35%, was recorded. This may be related to better equipment, the development of techniques, and training of the muscles. A high volume of training and knee instability, with MMD of 3 mm or more, seemed to be correlated with an increased risk for "jumper's knee" and, possibly, for skiing injuries. By identifying those at increased risk, preseason recommendations can be made and ski injuries may be prevented.
Article
Many patient-based knee-rating scales are available for the evaluation of athletic patients. However, there is little information on the measurement properties of these instruments and therefore no evidence to support the use of one questionnaire rather than another. The goal of the present study was to determine the reliability, validity, and responsiveness of four knee-rating scales commonly used for the evaluation of athletic patients: the Lysholm scale, the subjective components of the Cincinnati knee-rating system, the American Academy of Orthopaedic Surgeons sports knee-rating scale, and the Activities of Daily Living scale of the Knee Outcome Survey. All patients in the study had a disorder of the knee and were active in sports (a Tegner score of 4 points). Forty-one patients who had a knee disorder that had stabilized and who were not receiving treatment were administered all four questionnaires at baseline and again at a mean of 5.2 days (range, two to fourteen days) later to test reliability. Forty-two patients were administered the scales at baseline and at a minimum of three months after treatment to test responsiveness. The responses of 133 patients at baseline were studied to test construct validity. The reliability was high for all scales, with the intraclass correlation coefficient ranging from 0.88 to 0.95. As for construct validity, the correlations among the knee scales ranged from 0.70 to 0.85 and those between the knee scales and the physical component scale of the Short Form-36 (SF-36) and the patient and clinician severity ratings ranged from 0.59 to 0.77. Responsiveness, measured with the standardized response mean, ranged from 0.8 for the Cincinnati knee-rating system to 1.1 for the Activities of Daily Living scale. All four scales satisfied our criteria for reliability, validity, and responsiveness, and all are acceptable for use in clinical research.
Article
Patellofemoral arthrosis is one of the most common causes of knee pain in middle-aged patients, and is often associated with patellofemoral malalignment. A correct diagnosis is established by history taking and physical and radiographic examinations of the knee. The initial treatment of choice is conservative treatment, which includes anti-inflammatory drugs, use of a knee brace, quadriceps-strengthening exercises, physical therapy, and modification of activity. Surgery is indicated when patients fail to improve after at least 6 months of conservative treatment and are functionally disabled. Lateral retinacular release and proximal realignment are performed only in selected cases. Distal realignment by anteromedial transfer of the tibial tubercle is the most effective method for treating patients with patellofemoral arthrosis. The magnitude of anteromedial transfer of the tibial tubercle must be individualized, and rigid internal fixation enables immediate postoperative rehabilitation. In knees with patellofemoral arthrosis with no malalignment, a 20-mm anterior displacement without medial transfer of the tibial tubercle is suggested. A 15-mm anterior displacement plus 5 to 10 mm of medial transfer of the tibial tubercle is recommended in knees with patellofemoral arthrosis and mild to moderate malalignment. In knees with severe malalignment, 15 mm of medial transfer and 10 mm of anterior displacement are recommended. A triple osteotomy is considered in knees with patellofemoral osteoarthrosis and patella baja. Patellofemoral resurfacing arthroplasty is only done in carefully selected patients. A patellectomy should be avoided if at all possible. Total knee arthroplasty is indicated in knees with bi- or tricompartmental osteoarthritis.
Article
The goal of this prospective study was to determine the outcome-predictive role of various parameters in the nonoperative treatment of chronic anterior knee pain patients. Thirty patients followed a five-week treatment program, which consisted out of only closed kinetic chain exercises. Prior to this treatment all subjects were evaluated on muscular characteristics, subjective symptoms, weight, sex, duration of symptoms and functional performance. A multiple stepwise regression analysis revealed that the reflex response time of m. vastus medialis obliquus (VMO) (P=0.041; 0.026), and the duration of symptoms (P=0.019; 0.045) were the only two parameters which were significantly associated with the outcome (evaluated by the Kujala score) at five weeks, and at three months. The shorter the duration of symptoms, or the faster the reflex response time of VMO prior to the treatment, the better the outcome after a closed kinetic chain exercise program. The statistical significance of these parameters in this study may be seen as an indication of the importance of these variables as predictors of the outcome of a closed kinetic chain strengthening program. Using this information, it seems clinically important to begin the treatment program before the anterior knee pain becomes more chronic and treatment results become less good.
Article
To determine if persons with patellofemoral pain (PFP) demonstrate elevated patellofemoral joint (PFJ) stress during stair ascent and descent when compared to persons without PFP. A cross sectional study utilizing an experimental and a control group. Ascending and descending stairs is one of the most painful activities of daily living for persons with PFP. Whether or not the pain associated with stair ambulation is the result of elevated joint stress (force per unit area) has not been explored. 10 subjects with a diagnosis of PFP and 10 subjects without pain completed two phases of data collection, (1) MRI assessment to determine PFJ contact area and (2) comprehensive motion analysis during stair ambulation at self selected climbing velocities. Data obtained from both data collection sessions were utilized as input variables into a biomechanical model to quantify PFJ stress. Although the knee extensor moment and PFJ reaction force (PFJRF) were significantly reduced in the PFP subjects during stair ascent, there was no difference in PFJ stress between groups. Similarly, there were no differences in PFJ stress during stair descent. Our results do not support the hypothesis that subjects with PFP demonstrate greater joint stress during stair ascent and descent compared to subjects without pain. However, subjects with PFP appeared to maintain normal levels of PFJ stress by minimizing the PFJRF. This was accomplished through a slower cadence and a reduced knee extensor moment. PFP is a common syndrome causing pain and functional limitations during stair climbing and other activities requiring high levels of quadriceps activity. Information obtained from this study will be useful in understanding the biomechanical mechanisms contributing to functional deficits in the PFP population.
Article
To determine whether individuals with patellofemoral pain (PFP) demonstrate elevated patellofemoral joint (PFJ) stress compared with pain-free controls during free and fast walking. A cross-sectional study utilizing an experimental and a control group. Although the cause of PFJ pathology is believed to be related to elevated joint stress (force per unit area), this hypothesis has not been adequately tested and causative mechanisms have not been clearly defined. Ten subjects with a diagnosis of PFP and 10 subjects without pain participated. All subjects completed two phases of data collection: 1) magnetic resonance imaging (MRI) assessment to determine PFJ contact area and 2) comprehensive gait analysis during self-selected free and fast walking velocities. Data obtained from both phases were required as input variables into a biomechanical model to quantify PFJ stress. On the average, PFJ stress was significantly greater in subjects with PFP compared with control subjects during level walking. The observed increase in PFJ stress in the PFP group was attributed to a significant reduction in PFJ contact area, as the PFJ reaction forces were similar between groups. Our results are consistent with the hypothesis that increased patellofemoral joint stress may be a predisposing factor with respect to development of PFP. Clinically, these findings indicate that treatments designed to increase the area of contact between the patella and the femur may be beneficial in reducing the PFJ stress during functional activities. Patellofemoral pain affects about 25% of the population, yet its etiology is unknown. Knowledge of the biomechanical factors contributing to patellofemoral joint pain may improve treatment techniques and guide development of prevention strategies.
Article
To examine the effect of the application of tape over the patella on the onset of electromyographic (EMG) activity of vastus medialis obliquus (VMO) relative to vastus lateralis (VL) in participants with and without patellofemoral pain syndrome (PFPS). Randomised within subject. University laboratory. Ten participants with PFPS and 12 asymptomatic controls. Three experimental taping conditions: no tape, therapeutic tape, and placebo tape. Electromyographic onset of VMO and VL assessed during the concentric and eccentric phases of a stair stepping task. When participants with PFPS completed the stair stepping task, the application of therapeutic patellar tape was found to alter the temporal characteristics of VMO and VL activation, whereas placebo tape had no effect. In contrast, there was no change in the EMG onset of VMO and VL with the application of placebo or therapeutic tape to the knee in the asymptomatic participants. These data support the use of patellar taping as an adjunct to rehabilitation in people with PFPS.
Article
Painful disorders of the patellofemoral joint are one of the most frequent complaints in orthopaedic and sports medicine. The purpose of this study was to assess the value of single photon emission computed tomography (SPECT) bone imaging compared with arthroscopy in the differential diagnosis of anterior knee pain. Twenty-seven patients with chronic anterior knee pain and 27 age matched control patients were examined prospectively. All patients underwent a detailed clinical history and a thorough physical examination of the knee. Planar and SPECT knee scintigraphy was performed using 99mTc methylene diphosphonate (99mTc-MDP). Subsequently, arthroscopic examination of all three compartments of the affected knee was performed. The association between the scintigraphic findings and arthroscopy was examined statistically. Planar and SPECT scintigrams were classified as follows: focal or diffuse uptake in the patella only (eight patients), uptake in the patella and a corresponding focus in the distal femur (12 patients), and uptake in the patella associated with linear increased activity along the distal femur (six patients). One patient had no patellofemoral SPECT abnormalities. Six of eight patients with isolated increased patellar activity were diagnosed with chondromalacia of the patella, while 2/8 patients had arthroscopic findings unrelated to patellofemoral abnormalities. Seven of 12 patients with corresponding uptake in the patella and distal femur were diagnosed with patellofemoral arthritis. Eleven other patients with corresponding patellar and femoral activity were diagnosed with increased lateral patellar compression syndrome. In these patients the patellar foci were always lateral, and they separated during flexion of the knee. Seven patients had further scintigraphic findings in addition to patellofemoral abnormalities, unsuspected clinically. Nine of 27 patients in the control group (33%) had either focal or diffuse increased patellar uptake. Compared to arthroscopy SPECT imaging had a sensitivity of 100% for patellofemoral abnormalities and a specificity of 64% (negative predictive value, 100%; and positive predictive value, 72%). The overall observed agreement between SPECT and arthroscopy was 81% (kappa=0.63). It is concluded that SPECT imaging of the knee is highly sensitive for the diagnosis of patellofemoral abnormalities. SPECT significantly improves the detection of maltracking of the patella and the ensuing increased lateral patellar compression syndrome. This information could be used to treat patellofemoral problems more effectively.
Article
To determine knee angular velocity changes during stair descent and slow velocity eccentric isokinetic quadriceps contraction, in normal controls and patellofemoral pain syndrome patients. Isokinetic and kinematic analysis of the performance of patellofemoral pain syndrome patients and matched normal controls. In the presence of increased patellofemoral joint stresses, patellofemoral pain syndrome patients have been shown to adopt compensatory strategies to minimise joint loading and therefore pain. One of the compensatory strategies reported, is that of the break phenomena, which results in a change quadriceps torque production. Twenty female patients with patellofemoral pain syndrome and 20 asymptomatic matched controls participated in the study. All subjects had their isokinetic eccentric and concentric quadriceps torque assessed at 30 degrees/second and 2-dimensional video data taken when descending from a step. Variations in knee angular velocity and torque curves were then identified. None of the subjects demonstrated a break on isokinetic concentric quadriceps contraction. Of the patellofemoral pain syndrome patients, 50% (10 out of 20) had a break in eccentric torque curve on testing, compared with 15% (3 out of 20) of the controls. Abnormal curve perturbation was demonstrated to occur in none of the controls isokinetically, but 20% (4 out 20) of the patellofemoral pain syndrome patients had perturbations in their torque curves. On stair decent a break was seen in 60% (12 out of 20) of the patellofemoral pain syndrome patients and 15% (3 out of 20) of the control subjects on analysis of the knee angular velocity. Twenty percent (4 out of 20) of the patellofemoral pain syndrome patients and 10% (2 out of 20) of the controls had abnormal curve perturbation on analysis of their stair descent. The implications are that there appears to be a relationship between patellofemoral pain syndrome and control of eccentric quadriceps contraction. This relationship is possibly related to joint and soft tissue loading not just the degree of pain, with the break being a saving reflex to prevent further stress. Exercise to rehabilitate the quadriceps in patellofemoral pain syndrome should be chosen with regard to joint loading and range of movement as well as velocity of contraction, in order to facilitate quadriceps activation as opposed to inhibiting it.