STUDY DESIGN: Case-control study of females with patellofemoral pain syndrome (PFPS) and a control group. OBJECTIVES: Three different approaches were used to examine the utility of a 2-dimensional (2-D) frontal plane projection angle (FPPA) measure of knee alignment. First, we measured the FPPA association with respect to 3-dimensional (3-D) lower extremity joint rotations during single-leg squats. Second, we determined the correlation of the FPPA during single-leg squats with hip and knee joint rotations during running and single leg jumping.  Third, we compared the FPPA between females with and without PFPS. BACKGROUND: PFPS is associated with altered lower extremity kinematics during weight-bearing activities that decrease retropatellar contact area and increase retropatellar stress. An objective and simple procedure to quantify altered kinematics during weight-bearing activities may help clinicians identify individuals who may likely benefit from interventions to improve lower extremity kinematics. METHODS AND MEASURES: Twenty females with PFPS and 20 healthy female controls performed single-leg squats, running, and repetitive single-leg jumps while 3-D lower extremity kinematics were recorded. The FPPA was recorded by a digital camera during single-leg stance and single-leg squats. Correlation coefficients were used to quantify the association between the FPPA and transverse and frontal plane hip and knee angles for all activities. Independent t tests were used to compare FPPA values between groups. RESULTS: FPPA values representing medial displacement of the knee during single-leg squats were associated with increased hip adduction (r = 0.32 to 0.38, P<.044) and knee external rotation (r = 0.48 to 0.55, P<.001) across activities. FPPA values for the PFPS group reveal greater medial displacement of the knee compared with those of the control group during single-leg squats (P = .012). CONCLUSION: The association between the FPPA and lower extremity kinematics that are associated with PFPS suggest that the FPPA during single-leg squats may be a useful clinical measure. However, these methods should not be used to quantify 3-D joint rotations. LEVEL OF EVIDENCE: Level 5.

J Orthop Sports Phys Ther. 2008;38(10):606-615, published online 11 July 2008. doi:10.2519/jospt.2008.2706

KEY WORDS: anterior knee pain, kinematics, knee, patella, 2-dimensional analysis

STUDY DESIGN: Cross-sectional experimental laboratory study. OBJECTIVES: To investigate the relationships between hip strength and hip kinematics, and between arch structure and knee kinematics during prolonged treadmill running in runners with and without patellofemoral pain syndrome (PFPS). BACKGROUND: Hip weakness can lead to excessive femoral motions that adversely affect patellofemoral joint mechanics. Similarly, foot mechanics, which are influenced by foot structure, are also known to influence patellofemoral joint mechanics. Thus, proximal and distal factors should be considered when studying individuals with PFPS. METHODS AND MEASURES: Twenty recreational runners with PFPS (5 male, 15 female) and 20 matched uninjured runners participated in the study. Hip abduction and hip external rotation isometric strength measurements were collected before and after a prolonged run, while the arch height index was recorded on all runners before the run. Lower extremity kinematic data were collected at the beginning and end of the run. Two-way repeated-measures analyses of variance (ANOVAs) were used for analysis. RESULTS: Both groups displayed decreases in hip abductor and external rotator strengths at the end of the run. The PFPS group displayed significantly lower hip abduction strength [(kg x cm)/body mass] compared to controls (PFPS group: begin 15.3, end 13.5; uninjured group: begin 17.3, end 15.4). At the end of the run, the level of association between hip abduction strength and the peak hip adduction angle for the PFPS group was statistically significant, indicating a strong relationship (r = -0.74). No other associations with hip strength were observed in either group. Arch height did not differ between groups and no significant association was observed between arch height and peak knee adduction angle during running. CONCLUSIONS: Runners with PFPS displayed weaker hip abductor muscles that were associated with an increase in hip adduction during running. This relationship became more pronounced at the end of the run. LEVEL OF EVIDENCE: Therapy, level 5.

J Orthop Sports Phys Ther. 2008;38(8):448-456, published online 15 April 2008. doi:10.2519/jospt.2008.2490

KEY WORDS: arch height index, hip abductor muscle strength, hip external rotator muscle strength, knee valgus

There was a 50% increase in the number of abstract submissions this year. In the end, 33 abstracts were accepted. These were grouped into sessions addressing structural, neuromuscular, biomechanical, and hormonal factors that may influence the gender bias in ACL injury in­cidence. It was interesting to note that the majority of abstracts submitted were in the area of neuromuscular and biomechanical factors, with only a few in the ar­eas of structural and hormonal factors. This suggests a trend in the research focus towards the more modifiable factors.  

The retreat was cohosted by Kentucky Sports Medicine and Drayer Physical Therapy Institute and sponsored by DonJoy, Aircast, Bluegrass Bracing, and Smith and Nephew. To accommodate the increase in number of high-quality abstracts, the meeting was ex­tended to 2 full days. The retreat was attended by both clinicians and scientists with a common interest in the ACL injury gender bias. The 60-plus participants in­cluded registrants from across the United States as well as Canada and Australia. As with the previous retreats, the group consisted of physicians, physical therapists, athletic trainers, and scientists in the areas of biome­chanics, motor control, and neuromuscular function. Thirty percent of the participants in the 2006 retreat were participants in a previous retreat as well. 

The for­mat of the meeting included 1 keynote presentation per day, along with 15-minute podium presentations made by some of the participants. The keynote presenters were chosen for their scientific contribution to the un­derstanding of factors associated with the gender bias seen in the incidence of ACL injuries. Ton van den Bo­gert, PhD, from the Department of Biomedical Engi­neering at the Cleveland Clinic gave the first keynote titled "ACL Injuries: Do We Know the Mechanisms?" The second keynote presenter was William Garrett, MD, PhD, from the Department of Orthopedics at Duke University, whose talk was titled "Anterior Cruciate Lig­ament Injury Mechanisms and Risk Factors." Following all of the presentations, a consensus development ses­sion was held. In the pages of this supplement, you will find the consensus statement and an abstract on each of the 33 presentations made at the conference, organized by the topics listed above. 

J Orthop Sports Phys Ther. 2007;37(2):A1-A32. doi:10.2519/jospt.2007.0301

KEY WORDS: anterior cruciate ligament, ACL injuries, gender 

After sitting through 4 to 5 days of podium presentations and sorting through hundreds of posters, I have often left scientific meetings with a desire for more science relating to my own area of research. By design, this is the nature of these large annual scientific meetings. There is a need for these meetings to be broad and inclusive in order to attract a wide range of scientists. Certainly, the upside of this is that you have the opportunity to be exposed to the most current research in a number of areas that may be peripheral to your own research agenda. Interest groups have emerged in societies such as the American Physical Therapy Association (APTA) and the American College of Sports Medicine (ACSM), which help to provide more focused programming within these large meetings. However, the topic areas are often still fairly broad in nature.

Throughout the 1990s, the Research Section of the APTA has sponsored a number of successful weeklong research retreats on topics including motor control and neural plasticity. Experts in the field were chosen as keynote speakers and research abstracts were solicited from within the scientific community. These retreats were viewed as great forums for rich academic discussions among graduate students, clinicians, and seasoned scientists.

J Orthop Sports Phys Ther. 2003; 33(8):435-436.

Key Words: research, retreats

This was the second research retreat focused on gender bias in anterior cruciate ligament (ACL) injuries, the first having taken place in Lexington, KY in April 2001. The purpose of this second retreat was to revisit the factors thought to be associated with gender bias in ACL injuries and to update the consensus statement from 2001. The retreat was again cosponsored by Kentucky Sports Medicine and Joyner Sportsmedicine Institute and was attended by both clinicians and scientists with a common interest in the ACL injury gender bias. The 50-plus participants included registrants from across the United States as well as Canada, Australia, and Norway. As with the previous retreat, the group consisted of physicians, physical therapists, athletic trainers, and scientists in the areas of biomechanics, motor control, and neuromuscular function. Thirty percent of the participants in the 2003 retreat were present for the first retreat as well. A call for abstracts for the retreat was announced in the summer of 2002. All abstracts were then peer reviewed for scientific merit and relevance to the retreat topic. In the end, 19 abstracts were accepted for podium presentations. These were grouped into sessions addressing structural, neuromuscular, biomechanical, and hormonal factors that may influence the gender bias in ACL injury incidence. In addition, a new session on intervention programs was included. The format of the meeting included 1 keynote presentation per day along with 20-minute podium presentations made by some of the participants. The keynote presenters were chosen for their scientific contribution to the understanding of factors associated with the gender bias seen in the incidence of ACL injuries. Bruce D. Beynnon, PhD, from the University of Vermont gave the first keynote titled "Risk Factors for Knee Ligament Trauma." The second keynote presenter was Braden C. Fleming, PhD, also from the University of Vermont, whose talk was titled "Biomechanics of the Anterior Cruciate Ligament." This supplement includes a consensus statement, a listing of the presentations and authors, and an abstract on each of the 19 presentations made at the conference, organized by the topics listed above.

J Orthop Sports Phys Ther. 2003;33(8):A1-A30.

Key Words: anterior cruciate ligament (ACL), gender bias, intervention

Study Design: Cross-sectional. Objectives: To determine if females with anterior knee pain are more likely to demonstrate hip abduction or external rotation weakness than a similar, asymptomatic, age-matched control group. Background: Diminished hip strength has been implicated as being contributory to lower-extremity malalignment and patellofemoral pain. The identification of reliable and consistent patterns of weakness in this population may help health care professionals establish a more effective treatment plan. Methods and Measures: Hip abduction and external rotation isometric strength measurements were recorded for the injured side of 15 female subjects with patellofemoral joint pain (mean ± SD age, 15.7 ± 2.7 years; age range, 12-21 years). These were compared with strength measurements from the corresponding hip of 15 age-matched female control subjects (mean ± SD age, 15.7 ± 2.7 years; age range, 12-21 years). All strength measurements were made using hand-held dynamometers. Results: Subjects with patellofemoral pain demonstrated 26% less hip abduction strength (P<.001) and 36% less hip external rotation strength (P<.001) than similar age-matched controls. Conclusions: The results indicate that young women with patellofemoral pain are more likely to demonstrate weakness in hip abduction as well as external rotation than age-matched women who are not symptomatic.

J Orthop Sports Phys Ther. 2003;33(11):671-676.
 

Key Words: anterior knee pain, hip abduction, hip external rotation, knee, patella

Understanding foot motion is pivotal to understanding lower extremity mechanics during gait. The aim of the second Foot and Ankle Research Retreat was to address the issues related to the measurement of foot motion. It was sponsored by the Foot and Ankle Special Interest Group and the Orthopaedic Section of the APTA, along with the Department of Biokinesiology and Physical Therapy at the University of Southern California, and was held this past spring. A variety of different foot models were presented. Issues related to reliability and validity were discussed. New techniques, including the use of gait simulators and fast-PC MRI imaging, were presented. The description of this retreat, along with the abstracts of the presentations and the consensus statement from the participants are included in this issue. It is hoped that, as those interested in measuring foot motion read through these abstracts and the consensus statement, ideas for future research will be generated.

J Orthop Sports Phys Ther. 2004; 34(9):502-503. doi:10.2519/jospt.2004.0109

Key Words: foot motion, lower extemity mechanics, gait

This was the second Foot and Ankle Research Retreat sponsored by the Foot and Ankle Interest Group of the Orthopedic Section of the American Physical Therapy Association. It was hosted by the Department of Biokinesiology and Physical Therapy at the University of Southern California and was held April 30 to May 1, 2004. The purpose of this second retreat was to address the measurement of foot motion, focusing on the various foot models that have recently been proposed in the scientific community. Clinicians and scientists with a common interest in the measurement of foot and ankle mechanics attended the retreat. The 40-plus participants included registrants from across the United States as well as Australia, Singapore, and England. A scientific call for abstracts for the retreat was announced in the summer of 2003. All abstracts were then peer reviewed for scientific merit and relevance to the retreat. In the end, 14 abstracts were accepted for podium presentations. These were grouped into sessions addressing multisegment foot models, hindfoot modeling, and new techniques and applications. The format of the 2-day meeting included 1 keynote presentation each day, along with 20-minute podium presentations made by some of the participants. Thirty-minute discussions followed each session and each keynote address. The keynote presenters were chosen for their scientific contributions in the area of measuring foot and ankle motion. Arne Lundberg, MD, PhD, from the Karolinska Institute in Stockholm, Sweden gave the first keynote. Dr. Lundberg is a pioneer in the area of measuring multisegment foot motion, and his address was titled ‘‘The Ankle/Foot Complex: Solid Block, Gearbox or Cushion?’’ The second keynote presenter was Neil Sharkey, PhD, from The Pennsylvania State University. Dr. Sharkey developed one of the first gait simulators, and he presented his research in a keynote titled ‘‘One Step at a Time: Lessons Learned from Cadaver Simulation of Locomotion.’’ In this special report, you will find a consensus statement, a listing of the presentations and authors, and an abstract of each of the presentations made at the conference.

J Orthop Sports Phys Ther. 2004;34(9):A1-A18. doi:10.2519/jospt.2004.0302

Key Words: foot and ankle motion, measurement, multisegment foot models, hindfoot models

Study Design: Randomized clinical trial. Objectives: To investigate the clinical efficacy of the addition of the Protonics system to a standard exercise-based patellofemoral rehabilitation protocol. Background: The Protonics system has been suggested as an intervention for patients with patellofemoral pain syndrome (PFPS). However, the effects of this system have not been compared to the effects associated with traditional exercise-based rehabilitation alone. Methods and Measures: Seventeen of 34 females (mean age, 28 years; range, 13-55 years) diagnosed with PFPS were randomly assigned to wear the Protonics system while participating in a conventional exercise-based rehabilitation program. Functional and patient-reported outcome measures were evaluated, including Kujala score and the lateral step-up test. In addition, measurements of hip internal and external rotation, hip extension, and iliotibial band muscle length were compared between groups. Results: Patients in both groups demonstrated improvement in Kujala score (P<.001), performance on the lateral step-up test (P<.001), and pain during the step-up test (P<.001) at the conclusion of the study. However, there was no difference between groups with respect to improvement in Kujala score (P = .33), step-up test performance (P = .47), or pain during the step-up test (P = .24). Patients using the Protonics system demonstrated greater gain in passive hip extension (P = .023) and increased hip external rotation motion (P = .017) at discharge versus patients treated with exercise alone. However, there was no difference in iliotibial band flexibility (P = .80) or hip internal rotation motion (P = .09) between groups. A greater proportion of patients in the Protonics group reported no pain with step-up testing at each 2-week interval. However, the 2.2 fewer visits required by patients in the Protonics group to meet discharge criteria did not achieve statistical significance (P = .08). Conclusions: Patients using the Protonics system demonstrated a shift in available hip rotation and increased passive hip extension flexibility. However, these changes were not outside the bounds of potential measurement error and did not translate into significant functional differences from a similar group treated with exercise alone. The economic implications of an average 2.2-visit decrease in treatment sessions per patient using the Protonics system are uncertain.

J Orthop Sports Phys Ther. 2005;35(4):210-219. doi:10.2519/jospt.2005.1566

Key Words: anterior knee pain, hip rotation, Kujala score, therapeutic exercise

Study Design: Correlational study. Objectives: To determine whether, and to what degree, a relationship exists between forefoot angle and weight-bearing midfoot and rearfoot position. Background: There have been conflicting reports with regard to the degree to which the structure of the foot may influence the function. The influence of forefoot structure on weight-bearing midfoot and rearfoot position has not been extensively investigated. Methods and Measures: Fifty-one healthy subjects participated in this study (26 male and 25 female). Forefoot angle was measured in prone as varus (positive numbers), neutral (0), or valgus (negative numbers). Navicular drop was measured from subtalar joint neutral to unilateral standing relaxed. Rearfoot angle was measured in relaxed single-limb stance as the angle between a line that bisected the calcaneus and a line that bisected the lower third of the leg. The relationships between forefoot angle and navicular drop, and between forefoot angle and relaxed rearfoot angle, were investigated. The same relationships were also investigated in the neutral forefoot subgroup when the sample was divided in 3 subgroups based on 1 standard deviation of forefoot angle. Results: There is a significant relationship between forefoot angle and relaxed rearfoot angle (r = 0.52, P<.001), as well as between forefoot angle and navicular drop (r = 0.55, P<.001), in the whole sample (n = 51). Average degrees of forefoot angle in the neutral subgroup (between 1.0° and 8° of varus) are not associated with predictable positions of relaxed rearfoot angle (r = 0.19, P = .24) or navicular drop (r = 0.01, P = .96). Conclusions: Based on the results of this study, there is a significant relationship between forefoot angle and relaxed rearfoot angle, as well as between forefoot angle and navicular drop, in healthy subjects. These relationships were not found when forefoot varus values were within a standard deviation of the sample mean.

J Orthop Sports Phys Ther. 2005;35(9):559-566. doi:10.2519/jospt.2005.1541

Key Words: biomechanics, foot position, pronation, subtalar joint