Posts tagged patellofemoral pain
Which Muscle's Weakness Predicts Future Knee Pain?

Patellofemoral Pain Syndrome, pain under the knee cap, is the most common diagnosis of knee pain affecting both sedentary and active individuals. Muscle weakness in the hip and knee are often present in individuals with this diagnosis, but a cause and effect relationship between strength and knee pain has been difficult to established. In short, the research is divided on this relationship especially within the variable of hip weakness. Thus questions remain on which muscle imbalances may predispose an otherwise pain free individual for future patellofemoral pain.

A recent systematic review of the available evidence on the development of patellofemoral pain syndrome reviewed 18 studies of 4818 research participants (Neal et al. Br J Sp Med. 2019). Authors found three common groups of research subjects including military recruits, adolescents, and runners. They reported moderate to strong evidence body mass index, age, and leg alignment were not predictive of future knee pain. Interestingly, although common in clinical patients, moderate evidence reported hip weakness was not predictive of future knee pain. Authors reported quadricep weakness, especially among military recruits, was associated with future onset of knee pain.

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Reducing Your Risk for Knee Pain

Patellofemoral pain (PFP) is characterized by diffuse pain behind or around the patella or knee cap. It occurs when the knee is loaded and bent with activities such as: running, jumping, squatting or ascending/descending stairs. The prevalence of PFP is 22.7% in both adults and adolescents, and with the inherit link between PFP and Knee Osteoarthritis, further investigation is warranted to look at the factors contributing to PFP in order to develop successful injury prevention programs. A recent article was published on predictive variables for future development PFP (Bradley et al. BJSM 2018).

The authors reviewed 18 prospective studies, including over 4,800 participants (Military, Runners, Adolescents) to investigate factors contributing to PFP. Factors contributing included: weakness in quadriceps and increased baseline hip abduction strength. Contrary to past evidence, there is no change in likelihood of developing PFP with sex, BMI or Q angle of hips and knees.  Targeting quadriceps and hip strengthening exercises, as well as, assessing movement mechanics are appropriate interventions and preventative treatments for PFP.

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Is My Hip Or Knee More To Blame For My Knee Pain?

The knee is a vulnerable joint at times due to its' location adjacent to the two long levers of our thigh and leg bones.  The length of the levers allows the ankle and hip to exert a high amount of forces across the knee.  The importance of treating these adjacent joints in patients with knee pain is reflected in our current understanding of functional movements including walking, stair climbing, hiking, and running.  Patient's who experience knee pain during these movements frequently demonstrate hip weakness and an inability to control their knee position during single limb loading.  The increased load under the knee cap is due to abnormal pressure and contact area on the thigh (femur).  A recent biomechanical analysis quantifies the knee cartilage stresses at the patellofemoral joint highlighting the importance of analyzing the hip in patients with knee pain.

Liao and colleagues analyzed cartilage stresses between the knee cap and thigh during squatting tasks with varying degrees of thigh and shin rotation (Clin Biomech. 2018).  The authors found a progressively greater cartilage stresses with increasing degrees of thigh rotation, but found a decrease in cartilage stress with progressive shin rotation.  Additionally, progressive thigh movement toward the midline of the body also was shown to increase knee cartilage loading.  The authors concluded thigh internal rotation and movement toward the midline had the greatest impact on knee cartilage forces.  These findings support prior research studies highlighting the importance of examining and treating the hip in patients with knee pain.

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Muscle Weakness Differs Between Males and Females with Knee Pain
knee-pain-patellofemoral pain-exercises

Patellofemoral pain syndrome (pain around the knee cap) is the most frequent cause of knee pain and the most common diagnosis seen in sports medicine and physical therapy clinics.  The condition is often the result of a change in the dynamic alignment of the leg and knee joint during functional activities such as squatting, stair climbing, and running.  Contributing factors often include a loss of ankle mobility, as well as, hip weakness.  Many people assume the hip abductors or glut medius musculature is to blame, but without a thorough assessment most important muscle impairments are missed.  A new article reports on which muscle groups are weakest among males with patellofemoral pain syndrome. 

The International Journal of Sports Physical Therapy reported on the strength differences between males and females with knee pain (Hoglund et al. 2018).  Authors recruited 36 asymptomatic males and 36 males with patellofemoral pain syndrome into their study and examined the strength of their hip and knee joints.  The authors found significant differences in gluteus maximus or hip extensor strength between the two male groups.  Interestingly, no differences were noted between gluteus medius or hip abductor strength.  This study highlights strength differences between females, frequently hip abductor weakness, and males with knee pain.  

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Review Highlights Effectiveness of Manual Therapy for Patients with Knee Pain

Patellofemoral Pain (pain under the knee cap) is the most common source of knee pain among active individuals and athletes.  Symptoms are secondary to increased joint pressure between the knee cap and thigh during walking, hiking, squatting, kneeling, cycling or running.  Most commonly this diagnosis is secondary to muscle imbalances including hip and knee weakness which can be resolved with Physical Therapy treatments.  In addition to exercise, manual therapy to the lower quarter joints has also been shown to reduce pain in patients with patellofemoral pain.  

A recent review article in the Journal of Orthopedic and Sports Physical Therapy (Eckenrode et al. 2018) examined the available medical literature behind manual therapy treatments in patients with knee pain.  Authors included 9 previous studies where authors had utilized physical therapy and manual therapy in the treatment program.  Manual therapy was shown to reduce knee pain and self reported function in the short term, but long term results were not found.  This is consistent with treatment in our Boulder physical therapy practice where manual therapy is used in the short term to reduce pain and facilitate a transition to a higher level strengthening program.  

To learn more on how Physical Therapy can help you overcome knee pain contact your local Physical Therapist. 

Education, Gait Retraining, or Exercise for Management of Runners with Knee Pain
runners knee-knee pain-treatment-exercise-gait training

Patellofemoral pain, commonly referred to as runner's knee, is one of the most common reasons patients seek care in Physical Therapy clinics.  In short, the symptoms are caused by abnormal forces between the knee cap and thigh bone.  The condition is effectively treated by Physical Therapy interventions including manual therapy, exercise, and gait retraining.  The goal of these interventions is to normalize the forces across the knee joint and improve the capacity of the body to absorb their sport's forces.  A recent study compared different Physical Therapy interventions to determine which was most effective for improving patellofemoral pain symptoms.

A randomized controlled trial in the British Journal of Sports Medicine examined the impact of either education on training and symptom management, or exercise and an education program, or gait retraining and an education program on knee pain symptoms among 69 runners (Esculier et al. 2017).  The followed the runners on these 8 week programs on outcomes at 1, 4, and 5 months.  They were assessed for subjective reports of pain as well as strength and running mechanics.  As expected, each group improved over each time period but strength gains were seen in only the exercise group and improved gait mechanics were only seen in the gait retraining group.  Importantly, education on symptom management offered the largest impact on the runner's improvements and remained the most important factor for recovery.