Dance regional interrelationships

CASE REPORT
NAJSPT Rehabilitation of a Female Dancer with
PatellOfemoral Pain Syndrome: Applying
Concepts of Regional Interdependence in
Practice
Caitlyn Welsh, PT, MPTa
William J. Hanney, PT, DPT, ATC/La,b
Laura Podschun, PT, MPT, OCSa
Morey J. Kolber, PT, PhD, OCS, Cert MDTCc

ABSTRACT
Due to complex movements and high physical demands, CORRESPONDENCE
dance is often associated with a multitude of impairments William J. Hanney, PT, DPT, ATC/L
including pain of the low back, pelvis, leg, knee, and foot. University of Central Florida
This case report provides an exercise progression, empha- Program in Physical Therapy
sizing enhancement of strength and neuromuscular per- HPA 1 D Suite 258
formance using the concept of regional interdependence Orlando, FL 32816
in a 17 year old female dancer with patellofemoral pain Phone: 407-823-0217
syndrome. Email: whanney@mail.ucf.edu

a
Florida Hospital Sports Medicine and Rehabilitation
b
University of Central Florida
Orlando, FL USA
c
Nova Southeastern University

North American Journal of Sports Physical Therapy | Volume 5, Number 2 | June 2010 | Page 85

INTRODUCTION these motions may depend on the strength of proximal
Dance often involves a complex sequence of movements muscle groups that are antagonistic to these movements.10
and high physical demands of strength, stability, and flex- Proper hip strength and neuromuscular control, particu-
ibility. Due to intricate choreography and challenging larly of the gluteus medius and hip external rotators,
performance schedules dancers are potentially at risk for enhances knee stability by controlling the pelvis and lim-
injury. These physical requirements of dance, which iting hip adduction and internal rotation that result in
include prolonged bouts of training and explicit physical increased knee valgus during activity.11 In the absence of
control of their body, make physiologic training just as sufficient proximal strength or muscular control, the
important as skill development for injury prevention. femur may adduct and internally rotate, exaggerating lat-
eral patellar contact due to the valgus moment.12-14
The physical demands of dance often result in injury, Repetitive activities with this mal-alignment may eventu-
which in turn limit a dancer's ability to perform. In a sur- ally lead to patellofemoral pain.10
vey of 324 professional dancers, almost 50% reported
missing between one and twenty-one days of exercise due Patellofemoral pain syndrome (PFPS), also known as
to injury each year.1 Koutedakis and Jamuris1 reported anterior knee pain, remains a common orthopedic com-
that 90% of injuries in dancers involve the low back, plaint2,6 occurring in approximately 1 in every 4 people.15
pelvis, legs, knees, or feet. Prolonged bouts of training Those involved in athletics report an incidence of
with inadequate rest, unsuitable floors, difficult choreogra- patellofemoral pain greater than 25%.10,15 The condition is
phy, and insufficient warm-ups are among the factors that more common in women than men and most often
contribute to dance injuries.2 In their paper, Koutedakis affects younger individuals between the ages of 10 and 35
and Jamuris1 reviewed studies on male and female years.16 Unfortunately, this pain often becomes a chronic
dancers, which suggested that supplementary exercise condition that may fail to respond to conservative meas-
training, beyond that of dance training, can lead to ures.17
improvements in muscle balance and strength.
Symptoms of PFPS typically include the following: pain
Strength training decreases incidence of dance injuries, while ascending and descending stairs, squatting, or pro-
without interfering with the key artistic and aesthetic longed sitting. Swelling, popping or grinding sensations
requirements of a dancer.1 However, strength training has may be present, as well as incidences of knee buckling or
generally not been considered a necessary component of giving way.18,19 The spectrum of symptoms varies greatly
preparation for success in dance.1 This idea is supported among individuals, with complaints ranging from achy
by the view among dancers and choreographers that pain after activity to severe pain when rising from a chair
strength training may create a physique that is not com- or climbing stairs.16
plimentary to the typical dancer's aesthetic appearance.1
Many patients with anterior knee pain are eventually
MacDougal et al3 found increases in muscle strength were
referred to rehabilitation. Although PFPS is one of the
not necessarily accompanied by proportional changes in
most common clinical conditions treated by orthopedic
muscle size. This finding suggests that strength training is
and sports physical therapists, a consensus does not exist
closely related to neural adaptations which increase mus-
regarding how these patients should be managed.16
cle strength.3,4 These neural mechanisms responsible for
Differential diagnostic skills must be utilized to rule out a
strength development include alterations in agonist-antag-
range of inflammatory conditions, mechanical problems,
onist co-activation, increases in motor unit firing rates
and other conditions such as ligamentous injury,
(rate coding), and changes in descending drive to the
tendinopathy, bursitis, and muscle strain.18-20 Identifying
motorneurons.3,4
the origin of the inflammation is important for developing
Previous authors have suggested that proximal factors a treatment plan that will result in prompt resolution of
such as hip and core weakness may contribute to anterior symptoms.16 Failure to do so may result in suboptimal
knee pain.5-7 Additionally, authors have demonstrated that care and poor outcomes.16 Some of the various techniques
women exhibit movements associated with knee valgus commonly used to treat PFPS include non-steroidal anti-
and hip internal rotation when compared to men during inflammatory medication, ice, quadriceps strengthening,
specific movements.6,8,9 The ability of women to control


hamstring and gastrocnemius stretching, patella taping or female. She presented with a slender build, as well as a
bracing, and orthotics.15,20 low waist-hip ratio of 0.7524,25 that is typically seen in
dancers. She had no swelling or erythema of her left knee
Vaughn21 highlighted the importance of a regional
with visual inspection. The history of her current injury
examination for a patient with non-specific knee pain,
was insidious onset of approximately one-year duration,
illustrating the concept of regional interdependence. With
as previously noted.
respect to musculoskeletal problems, regional interde-
pendence refers to the concept that seemingly unrelated Functional Status
impairments in a remote anatomical region may con- The patient had stopped dancing 3 weeks prior to
tribute to, or be associated with, the patient's primary examination, per the orthopedic surgeon's recommenda-
complaint.22 In some cases, knee pain may be the sole tion. She reported difficulty walking or running for
presenting symptom when a more proximal or distal periods longer than 10 minutes due to pain. She also
structure such as the pelvis, hip, ankle, or foot is at fault.23 reported that ascending and descending stairs at school
In such cases, the pain may be referred from a more prox- caused an increase in pain, which forced her to take the
imal structure or be consequential to a remotely located elevator some days. The patient demonstrated unilateral
impairment that produces excessive stress on structures of squat with genu valgus collapse bilaterally with report of
the knee, resulting in pain.21 mild retro patellar discomfort.
The purpose of this case report is to demonstrate the Systems Review
importance of strength and neuromuscular training in a At evaluation the patient was 5'6" and 125 lbs with a body
female dancer who presented with PFPS and highlight the mass index of 20.2 which is considered to be at the lower
importance of a regional interdependence model of exam- end of a normal range.26 She reported a history of fainting
ination to identify the origin of knee pain. due to low blood sugar with no occurrences in the past two
years. Also no previous injuries or surgeries were report-
CASE DESCRIPTION AND HISTORY ed. An integumentary and neuromuscular screen
The patient was a 17-year-old female high school student revealed no gross deficits. Family medical history was
who participated in dance activities up to 18 hours a week. unremarkable.
Pain was initially reported in the anterior/medial aspect
of the left knee in December 2007 with no specific mech- Tests and Measures
anism of injury noted. The patient continued, despite Posture
pain in the left knee, to dance on a regular basis. She Standing postural assessment demonstrated the patient's
attempted to join the school cross-country team in the fall spine, hips, and knees were within normal limits (WNL)
of 2008 but was unable to participate due to her knee with exception of increased external rotation bilaterally in
symptoms. the lower quarter. Supine postural assessment revealing
an increase in femoral anteversion, which lead to com-
An orthopedic surgeon evaluated the patient in December
pensations in weight-bearing. The patient also presented
of 2008 with no significant findings related to fracture, dis-
with a Q-angle of 8 degrees bilaterally and the patella was
location, or meniscal involvement which is consistent
hypo-mobile on the left with medial to lateral glides. In
with the presentation of PFPS. Further diagnostic testing
prone the patient presented with rear foot varus of 5
with X-ray and MRI revealed a bone bruise on the medial
degrees bilaterally and a neutral forefoot when examined
femoral condyle and thinning cartilage. The patient opted
in subtalar neutral. Gait was assessed with the patient
for rest from dance and physical therapy.
ambulating in bare feet at a self-selected pace for 30 feet
and rapidly for 30 feet. No significant findings were found
INITIAL EXAMINATION
during gait analysis and the patient had no complaints of
Initial Presentation
pain.
The patient was seen on December 31, 2008 for physical
therapy examination with a chief complaint of left knee Range Of Motion
pain along the inferior and medial pole of the patella. The The patient's active range of motion (AROM) for all hip,
patient appeared to be a healthy and athletic 17 year old knee and ankle, measurements were WNL and symmetri-


cal bilaterally except for hip internal rotation with right Functional Outcome Measurements
internal rotation (IR) measured at 29 degrees and left IR At initial examination the patient scored a 49/80 on the
measured at 39 degrees. Lower Extremity Functional Scale (LEFS).27,28 She also
scored a 3.7/10 on the Patient-Specific Functional Scale
Pain
(PSFS)29 in which the patient identifies specific functional
A 10 mm visual analog scale (VAS) was used to elicit an
tasks which are limited and rates them zero to ten with
objective description of the patient's pain level.26 The
lower numbers reflecting greater levels of limitation.
patient reported 8/10 pain during dance class, which was
the activity that most aggravated the symptoms. Pain was
ASSESSMENT
alleviated to 0/10 with sitting or resting. The patient
The patient's primary impairment was knee pain
reported 5/10 pain levels with walking more than 10 min-
secondary to non-traumatic sports related injury. The
utes on even or uneven ground, as well as ascending or
physical therapy evaluation revealed an overall decrease
descending 10 steps at school. Symptoms were localized
in strength and muscle imbalances. This is particularly
to the medial aspect of the knee around the medial joint
the case for her hip musculature which is needed to per-
line. No tenderness to palpation occurred during examina-
form as a dancer. Weakness of the left hip abductor and
tion.
external rotator muscles allowed for increased anterome-
Muscle Strength dial vector forces and disproportionate stress on the
The patient's strength was measured using manual anterior/medial left knee. Due to pain while dancing, her
muscle testing as described by Daniels and orthopedic physician placed the patient on activity limita-
Worthingham.26 (Table 1) Abdominal (rectus abdominus tions and no return to dance until after the first 4 weeks of
and obliques) were measured at 4/5 in supine position treatment. The prescription was to evaluate and treat one
with trunk flexion. The patient was unable to hold a time a week for 6 weeks due to unusually high co-pay and
prone plank greater than five seconds before increasing financial limitations.After the initial examination, the
her lordotic curve suggesting weakness. All measure- patient was treated once per week for three weeks, and
ments were taken in a pain free manner. then once every other week, for six total sessions.

Table 1. Reported hip and knee strength measures. Plan of Care Design
The rehabilitation program integrated aspects of a
regional interdependence approach with a focus on
improving muscular strength and coordination, correcting
muscle imbalances, and enhancing neuromuscular con-
trol. Physical therapy interventions were initiated with a
home exercise program (HEP) following initial examina-
tion. The patient's initial home program included single
leg exercises for hamstring, gluteus medius and gluteus
maximus muscle strengthening, single leg squats, side
planks with knees flexed, as well as instruction for trans-
verse abdominus muscle contraction with all exercises.
Special Tests & and Muscle Length Assessments The patient was instructed to perform exercises daily,
Based on the patient complaints of left knee pain several completing two sets of ten for each exercise.
special tests were performed to rule out ligamentous and
meniscal involvement. The patient tested negative bilat-
erally for the following tests: Lachman's and anterior
drawer test for anterior cruciate ligament (ACL) stability,
McMurray's test for medial and lateral meniscus, 90/90
test for hamstring muscle length, Thomas test for iliop-
soas and rectus femoris muscle length, and Ober's test for
iliotibial band length.


INTERVENTION
Follow-up Visit 1
Assessment
The patient reported pain intensity of 6/10 VAS the week living and progression to return to dance that could be
following the initial examination, with the symptoms carried over for home program due to limited visits. The
most intense at night after performing exercises and nor- patient externally rotated her lower extremities, a natural
mal activity at school. She had not returned to dance but position for dancers, and demonstrated genu valgus dur-
had returned to teaching 3 children's dance classes which ing exercises. She also complained of pain with single leg
were 30 minutes in duration within the past week. She exercises. When cued to maintain her foot in a neutral
performed her HEP every other day since examination position with correct lower quarter alignment, the patient
and described the pain as intense and achy after the exer- reported decreased knee pain during therapeutic exercis-
cises. es, especially with single leg exercises.
The treatment focus was on simple strengthening exercis-
es for hip and core muscles necessary for activities of daily

Table 2. Follow up visit 1 exercises performed in clinic.

Figure 1. Unilateral leg press with elastic tubing.


Figure 4. Cable cord bilateral squat
Figure 2. Monster walk with with upper extremity row with elastic
elastic tubing around distal thigh. tubing and abduction resistance.

Figure 3. Prone push up position with
knee to chest at neutral and lateral and
medial angles with lower extremity move-
ment.


Follow-up Visit 2

Assessment
Upon return to treatment a week later the patient had min- decrease severe genu valgus collapse due to lack of
imal to no pain at rest or with activity with most intense strength of abductor and external rotator muscles. The
pain measured at a 2/10 on VAS. She had not increased her patient complained of fatigue and cramping in stabilizing
activity but was able to ascend and descend stairs at school. hip during exercises performed with foot in neutral hip
Upon reassessment for strength the patient demonstrated rotation position. The patient was able to climb stairs with-
better structural alignment of the lower quarter with out any pain and had no reports of knee pain during treat-
demonstration of bilateral squat and unilateral squat and a ment. The patient was instructed to use elastic tubing dur-
decrease in pain during performance of each. She contin- ing HEP for proper recruitment of abductor and external
ued to demonstrate a genu valgus collapse with unilateral rotator muscles and their ability to decrease vector forces
squat. on anterior/medial knee during closed chain activities.
She continued HEP performance every other day during
Due to a decrease in overall pain intensity with exercise,
the week between treatments. HEP was expanded to
the treatment focus was progressed to functional
include diagonal hops and single leg squats with ER of hip
movements with strengthening to mimic simple dance
during squat and IR of hip with rising.
maneuvers. Elastic tubing was utilized for hip abductor
muscle resistance during all single leg hip exercises to


Figure 5. Unilateral leg press with circle board. Figure 6. Forward step ups.


Figure 7. Single leg squat with internal rotation (IR) of hip concentric motion
and eternal rotation (ER) of hip with eccentric motion.


Follow-up Visit 3

Assessment
Upon return to therapy a week later the patient reported improved abduction/ER strength during sagittal plane
having had no pain in her knee all week during ADL's but activities by demonstrating decreased valgus collapse
that she had not returned to dance class. She did contin- with unilateral squatting. The patient continued to lack
ue to teach a children's class, which only required very proper control in coronal plane activities and movement
simple dance moves, all of which were pain free. She no with complaints of fatigue in hips. Over the next week
longer used the elevator at school and could ascend and the patient was allowed to return to tap class and jogging
descend stairs without pain. on pavement 1-2 miles a day. These activities were fol-
lowed with return to ballet and contemporary dance
Due to the patient's report of no pain all week, treatment class the following week. She returned to therapy after
exercises were advanced to mimic dance moves with two weeks. Her HEP was advanced to include the
multiple planes and involvement of upper and lower complex activities she had performed during in-clinic
extremities in a sport specific preparation for return to treatment.
dancing. During treatment the patient demonstrated


Figure 8. Side planks with knees flexed and single leg Figure 9. Crabwalk with squat and
abduction of top leg. elastic tubing around distal thigh.


Follow-up Visit 4

Assessment
The patient reported a return to dance class 4 days a week strated proper form with jumps and no compensations.
for about 8 hours a week at 80% of pre-injury levels. She Following pre-treatment re-examination the patient had no
reported only minimal pain during ballet class with certain complaints of pain or fatigue with treatment exercises. The
moves that required excessive external rotation. The HEP was advanced to focus on unilateral squats, jumps,
patient was able run pain free on a treadmill for 2 miles for and hops in an externally rotated position for return to
warm-up. For re-examination prior to treatment the patient sport training. The patient was to increase dance class
performed bilateral jumps and unilateral hops on even and hours and intensity and return to therapy in two weeks for
uneven surfaces to assess power and distance. She demon- discharge.


Follow-up Visit 5

Assessment
Upon return to therapy two weeks later the patient tive 40-yard dashes at maximum speed and performed
reported being 100% better. She returned to dance 5 days a repetitive jumping and skipping for 40 yards each. All activ-
week for 9-10 hrs a week at 100% pre-injury level. She also ities performed on pavement, with no reports of pain with
reported jogging 3 miles twice a week on off dance days. either activity.
Prior to physical therapy she could only perform one pirou-
ette however now was able to perform three in succession.
After re-examination for discharge the patient ran consecu-



OUTCOMES strength and 26% less hip abductor muscle strength than
At the discharge examination all hip and knee manual mus- control subjects.10 Bogla et al35 also showed similar results
cle tests were graded as 5/5. Overall pain level was a 0/10 for subjects with PFPS, who demonstrated 24% less hip
on VAS with all activities of daily living, school require- external rotator muscle strength and 26% less hip abductor
ments, ascending and descending stairs, as well as with muscle strength than controls. These studies support the
dancing. The patient scored a 74/80 on the Lower theory that hip abductor and hip external rotator muscle
Extremity Functional Scale and an 8.7/10 on the PSFS. The weakness may allow excessive hip adduction and hip inter-
one exception was a 1/10 pain on VAS, which the patient nal rotation during activity, thus contributing to
described with certain ballet pliés and turnouts that patellofemoral joint stress.10,34,36 More importantly, several
required maximal external rotation on both extremities. authors have reported favorable outcomes in patients who
This limitation did not limit her performance in ballet participated in a rehabilitation program targeting the hip
class. She reported gradually increasing the amount of time musculature for the treatment of anterior knee pain.34, 37, 38
she spent dancing each week, but was able to perform at
Authors have reported that female athletes land with less
100% of pre-injury level while in class. She was perform-
knee flexion, less time to peak knee flexion, greater knee
ing and teaching dance class 5 days a week for up to 10-12
valgus, greater vertical ground reaction forces, and less
hours a week at time of discharge.
hamstring activation than male athletes which may lead to
ACL injury.39 Jumping and landing is an integral part of
DISCUSSION
dance. Lephart et al,6,11 suggested that the neuromuscular
Weakness of the hip abductor and external rotator muscle
characteristics of the lower extremity in female athletes
may be associated with poor eccentric control of femoral
can be improved with a basic exercise program of jumps
adduction and internal rotation during weight-bearing
and single leg stance exercises which may reduce the risk
activities. This lack of control can contribute to malalign-
for injury. A reduction in injury rate after a strength-train-
ment of the patellofemoral joint as the femur medially
ing program alone was reported in those after ACL injury.6
rotates under the patella.30,31 To reduce excessive lateral
Elevated neuromuscular control may account for some of
patellar deviations during weight-bearing activities and
the strength gains.40 Improvements in a muscle's ability to
potentially reduce anterior knee pain, physical therapy
generate force, appears to be a way for dancers to enhance
intervention was necessary to address hip muscle perform-
their performance.1 The dancer presented in this case
ance and control of the LE during activity.32,33 Decreased
study demonstrated significant functional improvements
hip stability due to muscular weakness, especially that of
as reflected by the LEFS and PSFS scores with a primary
the gluteus medius and external rotator muscles, may
intervention of strengthening. An awareness of these fac-
affect the patellofemoral joint position in some patients.5
tors will assist dancers to improve training techniques and
Decreased hip abductor and hip external rotation muscle
to employ effective injury prevention strategies.
strength may allow the pelvis to collapse under the weight
of the body during single-leg stance which is a common
CONCLUSION
maneuver in dance. When a dancer drops their hip, a val-
This case report outlines rehabilitation guidelines, a
gus stress at the knee can occur and that may aggravate a
therapeutic exercise program, functional training interven-
patellofemoral joint condition.5,17
tions, and outcomes utilized with a female dancer with
Robinson and Nee34 demonstrated that females between 12 PFPS. The patient achieved a successful outcome, return-
and 35 years of age, presenting with unilateral PFPS ing to full participation of dance training and employment
demonstrate significant impairments in the isometric as a dance instructor. Critical to this case was implement-
strength of their symptomatic limbs for hip abduction, ing concepts associated with regional interdependence.
extension, and external rotation when compared to unin- Proximal weakness through the core and hip region of this
jured control subjects. Additional researchers have shown female dancer likely contributed to deficits in neuromuscu-
that young females with PFPS demonstrate hip abduction lar control of the lower extremity kinetic chain during
and external rotation muscle weakness when compared to squatting, jumping, and hopping. Clinicians should consid-
that of age-matched non-symptomatic females.10 Subjects er the influence of proximal impairments when examining
with PFPS demonstrated 36% less external rotation muscle and treating a patient with dysfunction of the lower limb.


REFERENCES 16. Mueller K, Snyder-Mackler L. Diagnosis of
1. Koutedakis Y, Jamuris A. The dancer as a performing patellofemoral pain after arthroscopic menisectomy.
athlete: physiological considerations. Sports Med. 2004; J Orthop Sports Phys Ther. 2003;30:138-142.
34:651-661. 17. Natri A, Kannus P, Jarvinen M. Which factors predict the
2. Sohl P, Bowling A. Injuries to dancers: prevelance, long-term outcome in chronic patellofemoral pain
treatment, and prevention. Sports Med. 1990;9:317-322. syndrome? A 7-year perspective follow-up study.
Med Sci Sports Exerc. 1998;30:1572-1577.
3. MacDougall J, Elder G, Sale D. Effects of strength
training and immoblization on human muscle fibers. 18. McConnell J, Gresamer R. The Patella. Gaithersburg, MD:
Eur J Appl Physiol Occup Physiol. 1980;43:25-34. Aspen Publishing; 1998.

4. Gabriel D, Kamen G, Frost G. Neural adaptations to 19. Powers C, Landel R, Sosnick T. The effects of patella
resistive exercise mechanisms and recommendations for taping on stride characteristics and joint motion in
training exercises. Sports Med. 2006;36:133-149. subjects with patellofemoral pain. 1997. 1997;26:286-291.

5. Fulkerson J. Diagnosis and treatments of patients with 20. Wilk K, Davies G, Mangine R, Malone T. Patellofemoral
patellofemoral pain. Am J Sports Med. 2002;30:447-456. disorders: a classification system and clinical guidelines
for nonoperative rehabilitation. J Orthop Sports Phys Ther.
6. Lephart S, Ferris C, Riemann B, Myers J, Fu F. Gender 1998;28:307-322.
differences in strength and lower extremity kinematics
during landing. Clin Orthop. 2002:162-169. 21. Vaughn D. Isolated knee pain: a case report highlighting
regional interdependence. J Orthop Sport Phys Ther. 2008;
7. Akuthota V, Nadler SF. Core strengthening. Arch Phys 38:616-623.
Med Rehabil. 2004;85:S86-92.
22. Wainner R, Whitman J, Cleland J, Flynn T. Regional
8. Malinzak R, Colby S, Kirkendall D, Yu B, Garrett W. A interdependence: a musculoskeletal examination model
comparison of knee joint motion patterns between men whose time has come. J Orthop Sports Phys Ther. 2007;
and women in selected athletic taks. Clin Biomech. 2001; 37:658-659.
16:438-445.
23. Mckenzie D, Clement D, Taunton J. Running shoes,
9. Sigward S, Salem G, Powers C. Kinemaic and kinetic orthotics, and injuries. Sports Med. 1985;2:334-337.
analysis of sidestep cutting: a comparison between males
and females. Clin Biomech. 2001;16:952-953. 24. Azizi F, Esmaillzadeh A, Mirmiran P, Ainy E. Is there an
independent association between waist-to-hip ratio and
10. Ireland M, Wilson J, Ballantyne B, Davis I. Hip strength cardiovascular risk factors in overweight and obese
in females with and without patellofemoral pain. women? Int J Cardiol. 2005;101:39-46.
J Orthop Sports Phys Ther. 2003;33:671-676.
25. Wardle J, Brodersen NH, Cole TJ, Jarvis MJ, Boniface
11. Lephart S, Abt J, Ferris C, et al. Neuromuscular and DR. Development of adiposity in adolescence: five year
biomechanical characteristic changes in high school longitudinal study of an ethnically and socioeconomica-
athletes: a plyometric versus basic resistance program. ly diverse sample of young people in Britain. BMJ. 2006;
Br J Sports Med. 2005;39:932-938. 332:1130-1135.
12. Hubertu H, Hayes W. Patelofemoral contact pressures: 26. Aaras A, Horgen G, Bjorset HH, Ro O, Walsoe H.
the influence of Q-angle and tendofemoral contact. Musculoskeletal, visual and psychosocial stress in VDU
J Bone Joint Surg Arm. 1984;66:715-724. operators before and after multidisciplinary ergonomic
13. Lee T, Yang B, Sandusky M, McMahon P. The effects of interventions. A 6 years prospective study--Part II. Appl
tibial rotation on the patellofemoral joint: assessment of ‘ Ergon. 2001;32:559-571.
the changes in in situ strain in preipatellar reticaulum 27. Binkley JM, Stratford PW, Lott SA, Riddle DL. The Lower
and the patellofemoral contact pressures and areas. Extremity Functional Scale (LEFS): scale development,
J Rehabil Res Dev. 2001;38:463-469. measurement properties, and clinical application. North
14. Mizuno Y, Kumagai M, Mattessich S. Q-angle influences American Orthopaedic Rehabilitation Research Network.
tibiofemoral and patellofemoral kinematics. J Orthop Res. Phys Ther. 1999;79:371-383.
2001;19:834-840. 28. Watson CJ, Propps M, Ratner J, Zeigler DL, Horton P,
15. Laprade J, Culham E, Brouwer B. Comparison of 5 Smith SS. Reliability and responsiveness of the lower
isometric exercises in the recruitment of the vastis extremity functional scale and the anterior knee pain
medialis oblique with and without patellofemoral pain. scale in patients with anterior knee pain. J Orthop Sports
J Orthop Sports Phys Ther. 1998;27:197-204. Phys Ther. 2005;35:136-146.


29. Chatman AB, Hyams SP, Neel JM, et al. The Patient-
Specific Functional Scale: measurement properties in
patients with knee dysfunction. Phys Ther. 1997;
77:820-829.
30. Powers C, Ward S, Fredericson M, Guillet M, Shellock F.
Patellofemoral kinematics during weight-bearing knee
extension in persons with lateral subluxation of patella: a
preliminary study. J Orthop Sports Phys Ther. 2003;
33:677-685.
31. Powers C. The influence of altered lower-extremity
kinematics on patellofemoral joint dysfunction: a
theoretical perspective. J Orthop Sports Phys Ther. 2003;
33:639-646.
32. Cossley K, Bennell K, Cowan S, Green S. Analysis of
outcome measures for persons with patellofemoral pain:
which are reliable and valid? Arch Phys Med Rehabil.
2004;85:815-822.
33. Cossley K, Bennell K, Cowan S, Green S, McConnell J.
Physical therapy for patellofemoral: a radomized, double-
blinded placebo-controlled trial. Am J Sports Med. 2002;
30:857-865.
34. Robinson R, Nee R. Analysis of hip strength in females
seeking physical therapy treatment for unilateral
patellofemoral pain syndrome. J Orthop Sports Phys Ther.
2007;37:232-238.
35. Bolgla L, Malone T, Umberger B, Uhl T. Hip strength and
hip and knee kinematics during stair descent in females
with and without patellofemoral pain syndrome.
J Orthop Sports Phys Ther. 2008;38:12-18.
36. Powers C, Landel R, Perry J. Timing and intensity of
vastis muscle activity during functional activities in
subjects with and without patellofemoral pain. Phys Ther.
1996;76:946-955.
37. Mascal C, Landel R, Powers C. Management of
patellofemoral pain targeting hip, pelvis, and trunk
muscle function: 2 case reports. J Orthop Sports Phys
Ther. 2003;33:647-660.
38. Tyler T, Nicholas S, Mullaney M, McHugh M. The role of
hip muscle function in the treatment of patellofemoral
pain syndrome. Am J Sports Med. 2006;34:630-636.
39. Wikstrom E, Tillman M, Schenker S, Borsa P. Failed jump
landing trials: deficits in neuromuscular control. Scand J
Med Sports. 2008;18:55-61.
40. Ploutz L, Tesch P, Biro R. Effect of resistance training on
muscle use during exercise. J Appl Physiol. 1994;
76:1675-1681.


Dance regional interrelationships

More Related Content

What's hot

Viewers also liked

Similar to Dance regional interrelationships

More from Andrew Cannon

Recently uploaded

Dance regional interrelationships