Rehabilitation of a Female Dancer with Patellofemoral Pain Syndrome: Applying Concepts of Regional Interdependence in Practice

Abstract

Due to complex movements and high physical demands, dance is often associated with a multitude of impairments including pain of the low back, pelvis, leg, knee, and foot. This case report provides an exercise progression, emphasizing enhancement of strength and neuromuscular performance using the concept of regional interdependence in a 17 year old female dancer with patellofemoral pain syndrome.

INTRODUCTION

Dance often involves a complex sequence of movements and high physical demands of strength, stability, and flexibility. Due to intricate choreography and challenging performance schedules dancers are potentially at risk for injury. These physical requirements of dance, which include prolonged bouts of training and explicit physical control of their body, make physiologic training just as important as skill development for injury prevention.

The physical demands of dance often result in injury, which in turn limit a dancer's ability to perform. In a survey of 324 professional dancers, almost 50% reported missing between one and twenty-one days of exercise due to injury each year.¹ Koutedakis and Jamuris¹ reported that 90% of injuries in dancers involve the low back, pelvis, legs, knees, or feet. Prolonged bouts of training with inadequate rest, unsuitable floors, difficult choreography, and insufficient warm-ups are among the factors that contribute to dance injuries.² In their paper, Koutedakis and Jamuris¹ reviewed studies on male and female dancers, which suggested that supplementary exercise training, beyond that of dance training, can lead to improvements in muscle balance and strength.

Strength training decreases incidence of dance injuries, without interfering with the key artistic and aesthetic requirements of a dancer.¹ However, strength training has generally not been considered a necessary component of preparation for success in dance.¹ This idea is supported by the view among dancers and choreographers that strength training may create a physique that is not complimentary to the typical dancer's aesthetic appearance.¹ MacDougal et al³ found increases in muscle strength were not necessarily accompanied by proportional changes in muscle size. This finding suggests that strength training is closely related to neural adaptations which increase muscle strength.^3,4 These neural mechanisms responsible for strength development include alterations in agonist-antagonist co-activation, increases in motor unit firing rates (rate coding), and changes in descending drive to the motorneurons.^3,4

Previous authors have suggested that proximal factors such as hip and core weakness may contribute to anterior knee pain.^5–7 Additionally, authors have demonstrated that women exhibit movements associated with knee valgus and hip internal rotation when compared to men during specific movements.^6,8,9 The ability of women to control these motions may depend on the strength of proximal muscle groups that are antagonistic to these movements.¹⁰ Proper hip strength and neuromuscular control, particularly of the gluteus medius and hip external rotators, enhances knee stability by controlling the pelvis and limiting hip adduction and internal rotation that result in increased knee valgus during activity.¹¹ In the absence of sufficient proximal strength or muscular control, the femur may adduct and internally rotate, exaggerating lateral patellar contact due to the valgus moment.^12–14 Repetitive activities with this mal-alignment may eventually lead to patellofemoral pain.¹⁰

Patellofemoral pain syndrome (PFPS), also known as anterior knee pain, remains a common orthopedic complaint^2,6 occurring in approximately 1 in every 4 people.¹⁵ Those involved in athletics report an incidence of patellofemoral pain greater than 25%.^10,15 The condition is more common in women than men and most often affects younger individuals between the ages of 10 and 35 years.¹⁶ Unfortunately, this pain often becomes a chronic condition that may fail to respond to conservative measures.¹⁷

Symptoms of PFPS typically include the following: pain while ascending and descending stairs, squatting, or prolonged sitting. Swelling, popping or grinding sensations may be present, as well as incidences of knee buckling or giving way.^18,19 The spectrum of symptoms varies greatly among individuals, with complaints ranging from achy pain after activity to severe pain when rising from a chair or climbing stairs.¹⁶

Many patients with anterior knee pain are eventually referred to rehabilitation. Although PFPS is one of the most common clinical conditions treated by orthopedic and sports physical therapists, a consensus does not exist regarding how these patients should be managed.¹⁶ Differential diagnostic skills must be utilized to rule out a range of inflammatory conditions, mechanical problems, and other conditions such as ligamentous injury, tendinopathy, bursitis, and muscle strain.^18–20 Identifying the origin of the inflammation is important for developing a treatment plan that will result in prompt resolution of symptoms.¹⁶ Failure to do so may result in suboptimal care and poor outcomes.¹⁶ Some of the various techniques commonly used to treat PFPS include non-steroidal anti-inflammatory medication, ice, quadriceps strengthening, hamstring and gastrocnemius stretching, patella taping or bracing, and orthotics.^15,20

Vaughn²¹ highlighted the importance of a regional examination for a patient with non-specific knee pain, illustrating the concept of regional interdependence. With respect to musculoskeletal problems, regional interdependence refers to the concept that seemingly unrelated impairments in a remote anatomical region may contribute to, or be associated with, the patient's primary complaint.²² In some cases, knee pain may be the sole presenting symptom when a more proximal or distal structure such as the pelvis, hip, ankle, or foot is at fault.²³ In such cases, the pain may be referred from a more proximal structure or be consequential to a remotely located impairment that produces excessive stress on structures of the knee, resulting in pain.²¹

The purpose of this case report is to demonstrate the importance of strength and neuromuscular training in a female dancer who presented with PFPS and highlight the importance of a regional interdependence model of examination to identify the origin of knee pain.

CASE DESCRIPTION AND HISTORY

The patient was a 17-year-old female high school student who participated in dance activities up to 18 hours a week. Pain was initially reported in the anterior/medial aspect of the left knee in December 2007 with no specific mechanism of injury noted. The patient continued, despite pain in the left knee, to dance on a regular basis. She attempted to join the school cross-country team in the fall of 2008 but was unable to participate due to her knee symptoms.

An orthopedic surgeon evaluated the patient in December of 2008 with no significant findings related to fracture, dislocation, or meniscal involvement which is consistent with the presentation of PFPS. Further diagnostic testing with X-ray and MRI revealed a bone bruise on the medial femoral condyle and thinning cartilage. The patient opted for rest from dance and physical therapy.

INITIAL EXAMINATION

Initial Presentation

The patient was seen on December 31, 2008 for physical therapy examination with a chief complaint of left knee pain along the inferior and medial pole of the patella. The patient appeared to be a healthy and athletic 17 year old female. She presented with a slender build, as well as a low waist-hip ratio of 0.75^24,25 that is typically seen in dancers. She had no swelling or erythema of her left knee with visual inspection. The history of her current injury was insidious onset of approximately one-year duration, as previously noted.

Functional Status

The patient had stopped dancing 3 weeks prior to examination, per the orthopedic surgeon's recommendation. She reported difficulty walking or running for periods longer than 10 minutes due to pain. She also reported that ascending and descending stairs at school caused an increase in pain, which forced her to take the elevator some days. The patient demonstrated unilateral squat with genu valgus collapse bilaterally with report of mild retro patellar discomfort.

Systems Review

At evaluation the patient was 5′6″ and 125 lbs with a body mass index of 20.2 which is considered to be at the lower end of a normal range.²⁶ She reported a history of fainting due to low blood sugar with no occurrences in the past two years. Also no previous injuries or surgeries were reported. An integumentary and neuromuscular screen revealed no gross deficits. Family medical history was unremarkable.

Tests and Measures

Posture

Standing postural assessment demonstrated the patient's spine, hips, and knees were within normal limits (WNL) with exception of increased external rotation bilaterally in the lower quarter. Supine postural assessment revealing an increase in femoral anteversion, which lead to compensations in weight-bearing. The patient also presented with a Q-angle of 8 degrees bilaterally and the patella was hypo-mobile on the left with medial to lateral glides. In prone the patient presented with rear foot varus of 5 degrees bilaterally and a neutral forefoot when examined in subtalar neutral. Gait was assessed with the patient ambulating in bare feet at a self-selected pace for 30 feet and rapidly for 30 feet. No significant findings were found during gait analysis and the patient had no complaints of pain.

Range Of Motion

The patient's active range of motion (AROM) for all hip, knee and ankle, measurements were WNL and symmetrical bilaterally except for hip internal rotation with right internal rotation (IR) measured at 29 degrees and left IR measured at 39 degrees.

Pain

A 10 mm visual analog scale (VAS) was used to elicit an objective description of the patient's pain level.²⁶ The patient reported 8/10 pain during dance class, which was the activity that most aggravated the symptoms. Pain was alleviated to 0/10 with sitting or resting. The patient reported 5/10 pain levels with walking more than 10 minutes on even or uneven ground, as well as ascending or descending 10 steps at school. Symptoms were localized to the medial aspect of the knee around the medial joint line. No tenderness to palpation occurred during examination.

Muscle Strength

The patient's strength was measured using manual muscle testing as described by Daniels and Worthingham.²⁶ (Table 1) Abdominal (rectus abdominus and obliques) were measured at 4/5 in supine position with trunk flexion. The patient was unable to hold a prone plank greater than five seconds before increasing her lordotic curve suggesting weakness. All measurements were taken in a pain free manner.

Table 1.

Reported hip and knee strength measures.

Tested Muscle Group	Right	Left
Hip flexors	5/5	4/5
Hip adductors	5/5	4/5
Hip extensors	5/5	4/5
Hip abductors	5/5	4/5
Hip external rotators	5/5	4/5
Hip internal rotators	5/5	4/5
Knee flexors	5/5	5/5
Knee extensors	5/5	5/5

Special Tests & and Muscle Length Assessments

Based on the patient complaints of left knee pain several special tests were performed to rule out ligamentous and meniscal involvement. The patient tested negative bilaterally 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 iliopsoas and rectus femoris muscle length, and Ober's test for iliotibial band length.

Functional Outcome Measurements

At initial examination the patient scored a 49/80 on the Lower Extremity Functional Scale (LEFS).^27,28 She also scored a 3.7/10 on the Patient-Specific Functional Scale (PSFS)²⁹ in which the patient identifies specific functional tasks which are limited and rates them zero to ten with lower numbers reflecting greater levels of limitation.

ASSESSMENT

The patient's primary impairment was knee pain secondary to non-traumatic sports related injury. The physical therapy evaluation revealed an overall decrease in strength and muscle imbalances. This is particularly the case for her hip musculature which is needed to perform as a dancer. Weakness of the left hip abductor and external rotator muscles allowed for increased anteromedial vector forces and disproportionate stress on the anterior/medial left knee. Due to pain while dancing, her orthopedic physician placed the patient on activity limitations and no return to dance until after the first 4 weeks of treatment. The prescription was to evaluate and treat one time a week for 6 weeks due to unusually high co-pay and financial limitations.After the initial examination, the patient was treated once per week for three weeks, and then once every other week, for six total sessions.

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 control. Physical therapy interventions were initiated with a home exercise program (HEP) following initial examination. 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 transverse abdominus muscle contraction with all exercises. The patient was instructed to perform exercises daily, completing two sets of ten for each exercise.

INTERVENTION

Follow-up Visit 1

Assessment

The patient reported pain intensity of 6/10 VAS the week following the initial examination, with the symptoms most intense at night after performing exercises and normal activity at school. She had not returned to dance but had returned to teaching 3 children's dance classes which were 30 minutes in duration within the past week. She performed her HEP every other day since examination and described the pain as intense and achy after the exercises.

The treatment focus was on simple strengthening exercises for hip and core muscles necessary for activities of daily living and progression to return to dance that could be carried over for home program due to limited visits. The patient externally rotated her lower extremities, a natural position for dancers, and demonstrated genu valgus during exercises. She also complained of pain with single leg exercises. When cued to maintain her foot in a neutral position with correct lower quarter alignment, the patient reported decreased knee pain during therapeutic exercises, especially with single leg exercises.

Table 2.

Follow up visit 1 exercises performed in clinic.

Exercise	Purpose and Rationale
Standing unilateral hamstring curls	Hamstring strengthening
Bilateral squats on inverted BOSU to 30 degrees of knee flexion	Lower quarter strengthening and proprioception
Unilateral leg press with elastic tubing for abduction resistance (Figure 1)	Abductor cueing during squat
Monster walk with elastic tubing around distal thigh (Figure 2)	Hip and thigh strengthening and abductor cueing
Latissimus pull down	Core strengthening/stabilization
Side planks with knees flexed	Core strengthening/stabilization
Prone push up position with knee to chest at neutral and lateral and medial angles with lower extremity movement (Figure 3)	Core strengthening/stabilization
Cable cord bilateral squat with upper extremity row with elastic tubing and abduction resistance (Figure 4)	Core strengthening/stabilization, lower quarter strengthening and proprioception

Figure 1.

Unilateral leg press with elastic tubing.

Figure 2.

Monster walk with elastic tubing around distal thigh.

Figure 3.

Prone push up position with knee to chest at neutral and lateral and medial angles with lower extremity movement.

Figure 4.

Cable cord bilateral squat with upper extremity row with elastic tubing and abduction resistance.

Follow-up Visit 2

Assessment

Upon return to treatment a week later the patient had minimal to no pain at rest or with activity with most intense pain measured at a 2/10 on VAS. She had not increased her activity but was able to ascend and descend stairs at school. Upon reassessment for strength the patient demonstrated better structural alignment of the lower quarter with demonstration of bilateral squat and unilateral squat and a decrease in pain during performance of each. She continued to demonstrate a genu valgus collapse with unilateral squat.

Due to a decrease in overall pain intensity with exercise, the treatment focus was progressed to functional movements with strengthening to mimic simple dance maneuvers. Elastic tubing was utilized for hip abductor muscle resistance during all single leg hip exercises to decrease severe genu valgus collapse due to lack of strength of abductor and external rotator muscles. The patient complained of fatigue and cramping in stabilizing hip during exercises performed with foot in neutral hip rotation position. The patient was able to climb stairs without any pain and had no reports of knee pain during treatment. The patient was instructed to use elastic tubing during HEP for proper recruitment of abductor and external rotator muscles and their ability to decrease vector forces on anterior/medial knee during closed chain activities. She continued HEP performance every other day during the week between treatments. HEP was expanded to include diagonal hops and single leg squats with ER of hip during squat and IR of hip with rising.

Table 3.

Follow up visit 2 exercises performed in clinic.

Exercise	Purpose and Rationale
Single leg body weight squat to 45 degrees of knee flexion	Eccentric quad control
Unilateral leg press with circle board (figure 5)	Reactive neuromuscular control
Forward step-ups with elastic tubing and abduction resistance on weight-bearing leg (figure 6)	Quadriceps muscle strengthening with abductor cueing
Bounding Stair climbs (2 Sets of 5 steps)	Quadriceps muscle strengthening
Single leg squat with IR of hip concentric motion and external rotation (ER) of hip with eccentric motion (figure 7)	Hip and quadriceps muscle strengthening with complex movement

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 having had no pain in her knee all week during ADL's but that she had not returned to dance class. She did continue to teach a children's class, which only required very simple dance moves, all of which were pain free. She no longer used the elevator at school and could ascend and descend stairs without pain.

Due to the patient's report of no pain all week, treatment exercises were advanced to mimic dance moves with multiple planes and involvement of upper and lower extremities in a sport specific preparation for return to dancing. During treatment the patient demonstrated improved abduction/ER strength during sagittal plane activities by demonstrating decreased valgus collapse with unilateral squatting. The patient continued to lack proper control in coronal plane activities and movement with complaints of fatigue in hips. Over the next week the patient was allowed to return to tap class and jogging on pavement 1-2 miles a day. These activities were followed with return to ballet and contemporary dance class the following week. She returned to therapy after two weeks. Her HEP was advanced to include the complex activities she had performed during in-clinic treatment.

Table 4.

Follow up visit 3 exercises performed in clinic.

Exercise	Purpose and Rationale
Side planks with knees flexed and single leg abduction of top leg (figure 8)	Abduction/ER strength with core strengthen ing/stabilization
Unilateral leg press to 45 degrees of knee flexion with circle board	Lower quarter strengthening and proprioception
Crabwalk with squat and elastic tubing around distal thigh (figure 9)	Core strengthening/stabilization and hip abductor cuing
Bounding Stair Climbs (3 sets 10 reps)	Reactive neuromuscular control and proprioception
Single leg stance on even ground with contra lateral LE sagittal and frontal plane lower reaches to cone	Reactive neuromuscular control and proprioception

Figure 8.

Side planks with knees flexed and single leg abduction of top leg.

Figure 9.

Crabwalk with squat and elastic tubing around distal thigh.

Follow-up Visit 4

Assessment

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

Table 5.

Follow up visit 4 exercises performed in clinic.

Exercise	Purpose and Rationale
Fast paced walk and moderate jog on treadmill between 4.0 and 6.0 mph for 10 minutes	Endurance
Bilateral squats on balance board with AP instability to 45 degrees of knee flexion with elastic tubing proximal to knees	Reactive neuromuscular control, proprioception, and abductor cueing

Follow-up Visit 5

Assessment

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

Table 6.

Follow up visit 5 exercises performed in clinic.

Exercise	Purpose and Rationale
Jog on treadmill at patient's selected 6.0 mph for 1 mile	Endurance
Double knees to chest jumps	Power
40 yd sprint on pavement	LE power
40 yd high skips on pavement	Speed, power, and agility

OUTCOMES

At the discharge examination all hip and knee manual muscle tests were graded as 5/5. Overall pain level was a 0/10 on VAS with all activities of daily living, school requirements, ascending and descending stairs, as well as with dancing. The patient scored a 74/80 on the Lower Extremity Functional Scale and an 8.7/10 on the PSFS. The one exception was a 1/10 pain on VAS, which the patient described with certain ballet pliés and turnouts that required maximal external rotation on both extremities. This limitation did not limit her performance in ballet class. She reported gradually increasing the amount of time she spent dancing each week, but was able to perform at 100% of pre-injury level while in class. She was performing and teaching dance class 5 days a week for up to 10-12 hours a week at time of discharge.

DISCUSSION

Weakness of the hip abductor and external rotator muscle may be associated with poor eccentric control of femoral adduction and internal rotation during weight-bearing activities. This lack of control can contribute to malalignment of the patellofemoral joint as the femur medially rotates under the patella.^30,31 To reduce excessive lateral patellar deviations during weight-bearing activities and potentially reduce anterior knee pain, physical therapy intervention was necessary to address hip muscle performance and control of the LE during activity.^32,33 Decreased hip stability due to muscular weakness, especially that of the gluteus medius and external rotator muscles, may affect the patellofemoral joint position in some patients.⁵ Decreased hip abductor and hip external rotation muscle strength may allow the pelvis to collapse under the weight of the body during single-leg stance which is a common maneuver in dance. When a dancer drops their hip, a valgus stress at the knee can occur and that may aggravate a patellofemoral joint condition.^5,17

Robinson and Nee³⁴ demonstrated that females between 12 and 35 years of age, presenting with unilateral PFPS demonstrate significant impairments in the isometric strength of their symptomatic limbs for hip abduction, extension, and external rotation when compared to uninjured control subjects. Additional researchers have shown that young females with PFPS demonstrate hip abduction and external rotation muscle weakness when compared to that of age-matched non-symptomatic females.¹⁰ Subjects with PFPS demonstrated 36% less external rotation muscle strength and 26% less hip abductor muscle strength than control subjects.¹⁰ Bogla et al³⁵ also showed similar results for subjects with PFPS, who demonstrated 24% less hip external rotator muscle strength and 26% less hip abductor muscle strength than controls. These studies support the theory that hip abductor and hip external rotator muscle weakness may allow excessive hip adduction and hip internal rotation during activity, thus contributing to patellofemoral joint stress.^10,34,36 More importantly, several authors have reported favorable outcomes in patients who participated in a rehabilitation program targeting the hip musculature for the treatment of anterior knee pain.^{34, 37, 38}

Authors have reported that female athletes land with less knee flexion, less time to peak knee flexion, greater knee valgus, greater vertical ground reaction forces, and less hamstring activation than male athletes which may lead to ACL injury.³⁹ Jumping and landing is an integral part of dance. Lephart et al,^6,11 suggested that the neuromuscular characteristics of the lower extremity in female athletes can be improved with a basic exercise program of jumps and single leg stance exercises which may reduce the risk for injury. A reduction in injury rate after a strength-training program alone was reported in those after ACL injury.⁶ Elevated neuromuscular control may account for some of the strength gains.⁴⁰ Improvements in a muscle's ability to generate force, appears to be a way for dancers to enhance their performance.¹ The dancer presented in this case study demonstrated significant functional improvements as reflected by the LEFS and PSFS scores with a primary intervention of strengthening. An awareness of these factors will assist dancers to improve training techniques and to employ effective injury prevention strategies.

CONCLUSION

This case report outlines rehabilitation guidelines, a therapeutic exercise program, functional training interventions, and outcomes utilized with a female dancer with PFPS. The patient achieved a successful outcome, returning to full participation of dance training and employment as a dance instructor. Critical to this case was implementing concepts associated with regional interdependence. Proximal weakness through the core and hip region of this female dancer likely contributed to deficits in neuromuscular control of the lower extremity kinetic chain during squatting, jumping, and hopping. Clinicians should consider the influence of proximal impairments when examining and treating a patient with dysfunction of the lower limb.