Manual Therapy to Treat Gluteus Medius Trigger Points to Improve Hip Abduction Strength in Patients With Anterior Knee Pain.

People with anterior knee pain have significant hip abductor muscle weakness compared to healthy people (Prins, 2009). Hip abductor weakness has a strong correlation with impaired lower extremity mechanics and increased pain with functional activity (Stickler et al. 2014). A study by Roach et al in 2013 found that 97% of patients with anterior knee pain had a trigger point in their gluteus medius muscle, while only 23% of healthy controls had trigger points. Trigger points alter normal muscle activity and increase pain in patients (Lucas, 2010, Ibarra et al 2011). Hip abduction strengthening has been found to significantly decrease pain and improve function in patients with anterior knee pain (Earl, 2011). By decreasing trigger points in the gluteus medius the investigators may be able to increase hip abduction strength reducing pain and dysfunction in patients with anterior knee pain.

Both Dry Needling (DN) and Soft Tissue Mobilization (STM) are manual therapy interventions commonly used by physical therapist to decrease trigger points in muscles. Currently, no research has examined the effectiveness of manual therapy to treat trigger points and improve hip abductor strength in patients with anterior knee pain. Clinically, the investigators have noted that after a patient has been treated with STM or DN that the investigators see immediate improvements in hip abduction strength. The investigators do not know if noted improvements result from repeated strength testing practice or actual improved firing strength of muscles.

The primary objective of this study is to see if manual therapy to the gluteus medius can significantly alter within-session measurements of hip abductor strength in patients with anterior knee pain.

The secondary objective of this study is to see if manual therapy to the gluteus medius can significantly alter within session pain in patients with anterior knee pain.

Patients referred to our physical therapy clinic for anterior knee pain will be considered for this study. After explaining the study and answering any patient or parent questions, informed consent will be obtained for those individuals wishing to participate. The participants will be screened to see if they meet the inclusion criteria, and will be randomly to a treatment group (Dry Needling, Soft Tissue Mobilization, Placebo control). This will be a single blinded research study with the assessor being blinded to the intervention. The therapist who performs the hip abductor strength measurements will not be the same therapist who performs the experimental interventions. The patient cannot be blinded to the treatment that they receive. The therapist performing the intervention will open a sealed envelope that allocates patient to Dry Needling, Soft Tissue Mobilization, or Sham Needling group. Following the experimental intervention all patients will perform the same hip and core exercise protocol.