Addition Effect of the Ankle Manual Therapy to Muscle Strengthening Exercise in Women With Patellofemoral Pain

Patellofemoral pain (PFP) is the most common overuse injury of the lower limb, its prevalence is around 20% in general population, and women are more likely to develop PFP compared to men. PFP may develop as a result of increased pressure and joint stress due to an reduction in contact area in the patellofemoral joint. The excessive dynamic knee valgus is an important contributor to patella misalignment and for the increasing of laterally directed forces on the patella, and restriction in ankle dorsiflexion range of motion (ROM) has been previously associated with excessive dynamic knee valgus. Although the evidence shows that strengthening exercises for the quadriceps and gluteus promote improvement of knee pain and function, there is a lack of studies that investigate if targeted interventions for improvement ankle dorsiflexion may promote additional benefits in knee pain and function when performed in combination with strengthening exercises. Thus, the aimed of this study is analyze the addition effect of calf stretching and ankle mobilization to quadriceps and gluteus strengthening on knee pain and function in women with PFP who display ankle dorsiflexion restriction.

The study sample will be formed by 68 women with PFP who show ankle dorsiflexion restriction, divided into two groups: Experimental Group (EG, n = 34), that will receive two manual therapy techniques (calf muscle stretching and ankle mobilization) followed by five muscle strengthening exercises focusing on quadriceps and posterolateral hip complex (PHC), and; Control Group (CG, n = 34), that will receive only the five muscle strengthening exercises focusing on quadriceps and PHC. The treatment sessions will be individual and supervised by a physiotherapist, will last 40-50 minutes and will perform twice a week for six weeks. Before starting each treatment session, both groups will perform warm up with a walk or exercise bike for 5 minutes.

The calf muscle stretching will be performed passively in two repetitions with 30 seconds of held in the stretching position and 30 seconds of rest between repetitions. The ankle mobilization will be performed using the Weight-bearing Mobilization with Movement (WB-MWM) technique, being applied in two sets of 10 repetitions with two minutes of rest between sets.

The five muscle strengthening exercises will be as follows: (a) clam exercise; (b) hip abduction exercise in side lying; (c) knee extension exercise in a sitting position; (d) squat exercise, and; (e) forward lunge exercise. All exercises will be performed in three sets of 12 repetitions with on minutes of rest between sets and two minutes of rest between exercises.

Regarding the intensity of the exercises, this will be monitored by the physiotherapist according to the perception of the level of effort and difficulty reported by the participant when completing the series of each exercise, according to the specifications of the modified Borg scale (CR-10). The exercises will be carried out with a load between 60-80% of the capacity and level of effort reported by the participant. The load will be increased by 2-10% when the patient is able to perform 12 full repetitions in the last series of the exercise with perceived effort \<60%.

Eligibility Criteria:
Inclusion Criteria:

* Presence of anterior knee pain for at least 3 months, unrelated to any traumatic knee event and reproducible by performing at least two of the following activities: sitting for a long time, squatting, kneeling, ascending or descending stairs, walking or running long distances, and performing jump-landing tasks;
* Anterior knee pain in the previous week with an intensity of at least 3 points on numeric pain rating scale (NPRS);
* Score in the Anterior Knee Pain Scale less than or equal to 86 points, and;
* Limited ankle dorsiflexion range of motion in closed kinetic chain, identified by a weight-bearing lunge test in which the distance between foot and wall being less than or equal to 10 cm.

Exclusion Criteria:

* History of surgery or fracture in the lumbar spine, hip, knee, ankle, or foot;
* Referred pain from the lumbar spine, hip, ankle, or foot;
* History of patellar subluxation;
* Presence of knee swelling;
* Presence of meniscal, ligament or tendon injury, and;
* Osgood-Schlatter or Siding-Larsen-Johansson syndrome.