Evaluation of a Treatment Algorithm for Patients With Patellofemoral Pain Syndrome

Patellofemoral pain syndrome (PFPS) accounts for 25 to 40% of knee pain in young and active individuals. PFPS is described as anterior knee pain around the patella which is aggravated by activity, particularly activities that increase patellofemoral forces such as squatting, ascending or descending stairs, running, and jumping. It is common in adolescents and physically active adults. Females are more likely to experience PFPS than males. PFPS is a multi-factorial condition with no clear etiology and is considered a syndrome and not a diagnosis. Dye has described PFPS as one of the most difficult orthopedic conditions to manage.

Multiple theories exist regarding a cause for PFPS pain. A primary theory for the cause of PFPS is abnormal patellar tracking which results in excessive patellofemoral joint compressive forces. Many factors contributing to abnormal patellar tracking have been suggested including; hip and quadriceps weakness, delayed or diminished activation of vastus medialis obliquus, increased Q-angle, altered lower extremity mechanics and decreased lower extremity flexibility. Due to the number of suggested contributory factors to PFPS pain, a vast amount of interventions exist and are frequently used by clinicians. Although, physical therapy interventions have been shown to be effective over sham interventions, many individuals will have recurrent or chronic pain. Ninety-six percent of patients report having problems four years following their diagnosis of PFPS. A possible reason for the continued pain is that PFPS is a multi-factorial condition and the treatments may not address all of the contributing factors in each individual.

If all of the contributing factors for the patient's PFPS are identified, addressing all of these factors at once may not be the best approach. Performing hip strengthening prior to quadriceps strengthening results in decreased levels of pain with exercise. Individuals with reduced flexibility are more likely to have impaired lower extremity mechanics. Performing traditional lower extremity strengthening exercises when there is impaired lower extremity mechanics results in increased patellofemoral joint contact forces.

In an attempt to better treat individuals with PFPS, classification systems to subgroup patients with PFPS have been proposed, but their effectiveness has not been evaluated. An important clinical question with classification systems is what to do when a patient does not nicely fit into one subgroup. If a patient does not meet or meets the criteria for multiple subgroups, how is the patient treated? No evidence exists on the relative frequency with which patients with PFPS fall into each of these proposed subgroups and whether these subgroups are mutually exclusive.

The clinical classification systems reported in literature only address physical impairments. Psychosocial factors have also been identified as important when treating patients with PFPS. In a study by Piva et al. fear avoidance beliefs were the strongest predictor of outcomes for function and pain. Mental health status on the Medical Outcomes Short Form-36 is correlated with severity of patellofemoral symptoms in athletes. The results of these studies highlight the necessity of addressing psychosocial factors when treating PFPS.

Therefore, the authors have designed a new classification system (PFPS algorithm) for subgrouping patients based on the patient's clinical presentation. There are four subgroups in the new PFPS algorithm: Fear-Avoidance, Flexibility, Functional Malalignment, and Strengthening with function progression. The criteria and intervention of each subgroup is addressed sequentially over the episode of care. This classification system aims to address problems encountered if individuals meet the criteria for multiple subgroups. There is also a psychosocial component to address the needs of individuals with activity avoidance. The PFPS algorithm is goal-based, where meeting the criteria to pass through each subgroup is the focus of the treatment. Clinicians can provide whichever physical therapy intervention that allows an individual patient to meet the criteria of each subgroup. Interventions used in the PFPS algorithm are based on best available evidence, clinician's experience, and the patient's individual response to the intervention.

A pilot study assessing the feasibility of a full study assessing this algorithm and it effectiveness was performed previously by the study investigators (IRB13-00749). The primary aims of this pilot study were met. The therapists and clinic personnel successfully worked together to carry out all treatments required to conduct a future full scale randomized controlled trial. The ordered treatment approach used in the PFPS algorithm, addressing soft tissue tightness, altered lower extremity kinematics, neuromuscular deficits and psychosocial factors in a sequential manor, resulting in clinically significant improvements in Anterior Knee Pain Scale and Global Rating of Change scores. With minor changes to the protocol and outcome measures used, a full randomized controlled trial assessing the effectiveness of the PFPS algorithm was deemed feasible.

The primary objective of this study is to assess the efficacy of using a sequential treatment approach to treat patellofemoral pain syndrome.

Patient will be randomized into one of two treatment groups; either the PFPS algorithm or the control group which is an impairment based approach.

Impairment Based Approach:

The control group will be an impairment based approach with treatment focusing on impairments found during evaluation in the lower quarter. The evaluation of the lower quarter will assess motion, flexibility, strength and body mechanics. The joints of the lower quarter include the lumbar spine, hip, knee, ankle and foot. Specific attention will be paid to quadriceps and hip strength, hip and knee flexibility, and squatting, jumping, walking and running mechanics. Treatment will consist of 2 visits per week for 6 weeks. Treatments will last for 45-60 minutes. Exercises will be given for the patient to perform at home at the therapist discretion. Interventions will be individualized to the patient and will be at the therapist's discretion. Therapists can use treatments including but not limited to: exercise, manual therapy, taping and bracing, orthotics, modalities, and education. Home exercises will be given the therapist discretion consistent with standard care.

PFPS treatment algorithm:

The PFPS treatment algorithm is a objective goal driven treatment program. Treatment is at the therapist discretion with the objective to meet the requirements for each subgroup. Evidence from literature guides treatment to best meet these goals.

The first group within the classification system is Fear Avoidance, as research has shown that a change in fear-avoidance beliefs about physical activity is one of the best predictors for improved functional outcome.

The second group is Flexibility. This is the second group in the system because research shows that patients with decreased flexibility are unable to properly perform functional malalignment test. Also quadriceps length and gastrocnemius/soleus lengths are strongly associated with PFPS.

The third group is Functional Malalignment. This group assesses the patient's form with functional tasks. If the patient demonstrates impaired mechanics, time is spent with strengthening and motor control so that the patient will be able to strengthen and return to full function with proper technique.

The final group is Strengthening/Return to Function. This group will work strengthening of the lower quarter muscles with particular attention to the quadriceps, hip abductor and external rotators. This is also the time to progress the patient back to sport or functional activity.

-Fear Avoidance Belief Questionnaire (A score of 15 or greater on this questionnaire results in being give a PFPS fear avoidance booklet and treatment using a Cognitive Behavioral emphasis)

Primary Muscle Flexibility Requirements (Not meeting 1 of these flexibility measures results being placed into the flexibility subgroup)

• Quadriceps ≥ 130 degrees
• Gastrocnemius ≥ 12 degrees
• Soleus ≥ 20 degrees
• Weight Bearing Dorsiflexion ≥ 48 degrees

Secondary Muscle Flexibility (Having tightness in at least 3 of the following tests results in being placed into the flexibility subgroup)

• Thomas test
• Ober's Test
• Hamstring Straight Leg Raise ≥ 80 degrees
• Adductor Flexibility

Functional Malalignment (Score of great than 1 results in being placed into functional malalignment subgroup)

• Lateral Step Down test
• Single Leg Squat test

Strengthening/Functional Progression (A limb symmetry index score of >=90% for each of these test is used to determine adequate LE strength and function)

• Single Hop Test
• Triple Hop Test
• Crossover Hop for Distance test
• Timed Step Down test