Managing Patellofemoral Pain Syndrome: New Research Insights and Treatment Strategies
Patellofemoral pain affects nearly one-fourth of the population each year, with females experiencing almost double the risk of males. (1,2) The condition accounts for approximately 7% of all medical diagnoses. (3)
Fortunately, evidence-based chiropractors are well-equipped to manage patellofemoral pain syndrome (PFPS). This blog will highlight the most essential clinical pearls from the past year of research, including a dozen systematic reviews. In less than 5 minutes, you’ll learn valuable new clinical skills for managing this common presentation.
1. What are the symptoms of patellofemoral pain syndrome?
The cardinal symptom of patellofemoral pain syndrome, aka “Runner’s Knee,” is anterior knee pain that intensifies with weight-bearing activity, particularly during activities that load the joint, including prolonged walking, running, squatting, jumping, kneeling, arising from a seated position or stair climbing- especially walking down stairs or downhill. (4,5)
2. What causes patellofemoral pain syndrome?
Patellofemoral pain typically develops from a combination of cartilage vulnerability, improper biomechanics, and demanding activity, i.e., squats, stair climbing, running, etc. *If you’re a numbers nerd and are looking for a deeper dive, The American Journal of Sports Medicine (6) recently quantified activity and exercise-related patellofemoral load.
The patella naturally tends to migrate laterally due to the pull of the quadriceps and the slight natural valgus of the lower extremity. (7) This causes a “lateral patellar tracking disorder” where the lateral patellar facet rubs against the lateral femoral condyle. This compression is often compounded by one or more of the following biomechanical functional deficits.
Gluteus medius weakness
Patellofemoral pain syndrome patients consistently demonstrate hip abductor weakness with resultant kinematic problems, particularly uncontrolled hip adduction when ambulating. (8-13) Biomechanical studies have shown that excessive hip adduction is the “[primary] biomechanical variable associated with running injury.” (14) Some debate persists as to whether hip abductor weakness is a cause or a symptom of patellofemoral pain syndrome; however, this argument is largely inconsequential since rehabbing hip abductor weakness is essential, regardless. (15)
ITB tightness
Multiple studies have found that patellofemoral pain syndrome patients’ ITB and lateral retinaculum are tighter and thicker. (16-19) Excessive tightness in the ITB and lateral retinaculum are thought to contribute to patellar mal-tracking by limiting medial centration. (15)
Foot hyperpronation
Loss of the longitudinal arch causes internal rotation of the tibia and subsequent deviation of the patella, increasing one's risk of patellofemoral pain syndrome. (20-26)
Gait deficits
Runners with slow cadence or excessively narrow gait patterns (i.e., crossover gait) are predisposed to patellofemoral pain syndrome. Additionally, running with a rear-foot strike imposes higher loads on the knee and patellofemoral joints. In contrast, a forefoot strike transitions the load toward the ankle joint and Achilles tendon. (27)
Wildcard ⚠️: VMO weakness
VMO atrophy is inconsistently present in patellofemoral pain syndrome patients, although a causal relationship has not been established. (15,28-30)
3. How do you evaluate patellofemoral pain syndrome?
Watch this patellofemoral pain syndrome assessment tutorial for the top patellofemoral pain syndrome tests.
PFPS is primarily a diagnosis of exclusion, and the following tests can help solidify the diagnosis.
Squatting
The most sensitive physical examination test for patellofemoral pain syndrome patients is pain with squatting. (31) Differentiating meniscal pain from patellofemoral pain may be accomplished by having the patient perform a two-legged squat. Meniscal pain is expected at the bottom of the squat, while patellofemoral pain is present during descent and ascent.
Step test
The step test is performed by placing one foot on a 6-inch block with hands on hips. Using the affected limb, lower your body in a controlled and gradual manner until the heel of the opposite leg touches the floor. This test for patellofemoral pain syndrome reproduces pain in three-fourths (74%) of PFPS patients. (32)
Patellar grind
This PFPS test begins by applying a compressive downward force to the supine patient’s patellofemoral joint. The patient is then asked to contract their quadriceps muscle while the patellofemoral joint is compressed. Pain or crepitus indicates patellofemoral irritation. Patients with a positive grind test are significantly more likely to develop subsequent knee osteoarthritis. (34) *Clinicians should use caution when performing this test, not unnecessarily to provoke pain or create new irritation.
Patellar mobility
Patellar mobility may be assessed with the Patellar Glide test and Patellar tilt test or by observing patellar tracking during active knee flexion/extension. (35)
ChiroUp subscribers can review any of the tests mentioned above in their Clinical Skills tab.
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Functional assessment
Examining a patient's gait, posture, and footwear can help identify patellofemoral pain syndrome triggers. (36) Clinicians should be particularly observant of foot hyperpronation, which primarily contributes to patellar mal-tracking. Gluteus medius (hip abductor) weakness may be assessed by observing for pelvic drop or knee valgus (Trendelenberg sign) when performing a single-leg stand, single-leg squat, or single-leg 6” step down.
Deeper dive: Check out these on-demand ChiroUp webinars for common functional deficits:
Wildcard ⚠️: Radiographs
Plain radiographs of the knee are generally unnecessary for the simple diagnosis of patellofemoral pain syndrome but can exclude other more advanced diagnoses, such as osteoarthritis, patellar fracture, and osteochondritis. (31)
4. What are the top patellofemoral pain syndrome treatments?
Here are nine evidence-based, in-office treatments for patellofemoral pain syndrome.
Exercise
Per the 2016 consensus statement by the International Patellofemoral Pain Research Committee, exercise therapy is considered the primary treatment approach for individuals with PFPS (37). Due to the multifactoral etiology of patellofemoral pain syndrome, a combination of hip and knee exercises is most beneficial. (36,38)
Whole-Body Vibration
Combining whole-body vibration with exercise may lead to more significant pain reduction than exercise alone in patellofemoral pain syndrome patients. (39)
BFR
While the evidence on Blood Flow Restriction exercise is inconclusive, some researchers have found that BFR improves pain and function for patients with patellofemoral pain syndrome. (15,40) Additionally, combining BFR and IASTM has been shown to be more effective than either therapy in isolation. (41)
What is BFR?
BFR, or blood flow restriction training, is a technique that involves partially restricting blood flow to a muscle group while performing exercises at a lower intensity than traditional strength training. This restriction is typically achieved using a tourniquet or adjustable bands applied to the limb with about 70% pressure. By limiting blood flow, BFR creates a hypoxic environment in the muscles, which triggers a cascade of physiological adaptations that lead to increased strength, muscle growth, and improved endurance. (15)
Manipulation
Manipulation of the lumbar spine, hip, sacroiliac joint, knee, and ankle regions may benefit patellofemoral pain syndrome patients. (43,44) Mobilization and manipulation of the patellofemoral and tibiofemoral joints may provide benefits for PFPS patients. (5,36,45) Research has shown that lumbopelvic manipulation can improve knee pain, knee position sense, and balance in patients with patellofemoral pain. (46)
Myofascial release
Myofascial release and stretching should be directed at hypertonic muscles, including the TFL, gastrocnemius, soleus, hamstring, piriformis, hip rotators, and psoas.
IASTM
IASTM may be appropriate for tightness in the iliotibial band, vastus lateralis, posterior hip capsule, and lateral knee retinaculum. Research indicates that IASTM treatment can enhance knee pain relief, improve muscle flexibility, and increase knee strength without pain. (41)
Dry needling
Research has shown that dry needling plus stretching outperforms prescription NSAIDs and stretching, providing superior and longer-lasting effects lasting at least six months. (47)
Therapeutic Taping
There is conflicting evidence concerning the effectiveness of traditional patellofemoral taping, i.e., McConnel taping. (48-52) Studies on elastic therapeutic tape are also mixed but encouraging. (79-81) Taping, including exercise, is most useful in a comprehensive, multi-modal treatment approach. (36)
Orthotics
Foot orthotics may be beneficial in reducing pain and improving function in patellofemoral pain syndrome patients. (36, 53-55,78).
Wildcard ⚠️: EMS
A 2017 Cochrane Review found limited, low-quality evidence regarding the effectiveness of e-stim for patellofemoral pain syndrome treatment, suggesting a slight reduction in pain but insufficient support for improvements in strength or function. (56).
5. What are the best exercises for patellofemoral pain syndrome?
Since hip abductor weakness is a critical factor in developing patellofemoral pain syndrome, strengthening exercises targeting the gluteus medius prove most effective, leading to decreased pain and improved function. (54,57-65) Potential exercises would include:
TFL Stretch
Dynamic Wall Squat
Clam with Band
Advanced Clam
Patellofemoral pain syndrome rehab should include progressive hip and knee strengthening with open and closed-chain exercises. (6,36) In addition to correcting underlying functional triggers, a straightforward, progressive program might consider the following progression (6):
Walking
Seated knee extension
Low step up
Low step-down
60° double-leg squat
High step-up
Single-leg squat
Sports-related activity
6. What are the essential ADLs for patellofemoral pain syndrome?
Gait Training
Training patellofemoral pain syndrome patients to increase their step rate by 10% produces lasting improvements in pain and function. (66-69) Selecting moderate running speeds (~3.1 m/s) with reduced training duration or an interval-based approach may be more effective for managing cumulative patellofemoral joint kinetics than running at slow speeds. (70)
Footwear
Runners should change shoes every 250 to 500 miles. Running shoes with less than 5mm heel drop decreased patellofemoral joint stress significantly by reducing total knee extension. (71) Running shoes with less than 5mm heel drop decrease patellofemoral joint stress significantly by reducing total knee extension. (72) Providers should counsel runners on choosing between motion-control, cushioned, stability, or neutral shoes. See this prior Running blog for details.
10% rule
One study found that those who abruptly increased their training mileage by more than 30% over two weeks were more susceptible to injury (73). In particular, new runners are vulnerable to breaking the “10% rule”, i.e., do not increase any activity by more than 10% from the previous level. (15)
PNE
Recent studies suggest that patellofemoral pain syndrome is not solely a peripheral issue but also involves central sensitization, as evidenced by heightened pain perception and hyperalgesia in affected individuals (74-76). This highlights the need for a multi-faceted approach that addresses both physical and psychological factors, as corroborated by a systematic review linking patellofemoral pain syndrome to increased anxiety, depression, catastrophizing, and fear of movement (77).
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ChiroUp subscribers can download the following infographics from their forms library by searching the name of the infographic.
Preventing Problems 101: The 10% Rule
Proper Running Mechanics
Choose the Correct Athletic Shoe
Rethinking Chronic Pain
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