Manual Therapy to Treat Gluteus Medius Trigger Points

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

This is a blinded randomized controlled trial to assess the effectiveness of manual therapy to improve hip abduction strength in patients with acute anterior knee pain. 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.

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. Pre-treatment evaluation measures will be taken on the patient blinded assessor. These will consist of: Hand held dynamometer hip abduction strength measurements. Pain with single leg squat The subject will then receive the appropriate treatment based on his/her random assignment to experimental treatment groups by the treating therapist. Post-treatment evaluation measures will be taken on all patients by the blinded assessor immediately following treatment. These will be the same measures taken pre-treatment. Hand held dynamometer hip abduction strength measurements. Pain with single leg squat Patients will then perform the same hip and core exercise protocol, Following these exercises Post-Exercise evaluation measures by the blinded assessor. These will be the same measures taken pre-treatment.

Placebo to control for hands on time and attention from therapist followed by hip and core exercises.

Dry Needling will be performed on the patient's ipsilateral gluteus medius muscle with the patient in sidelying. The treating therapist will use the appropriate needle based upon patient's size and location of trigger point [No. 5 (0.25 x 40mm), No. 8 (0.30 x 50mm), or No. 11 (0.30 x 75mm)]. They will target trigger points identified in the ipsilateral gluteus medius. Once the needling is inserted into the trigger point the needle will be moved in multiple directions until the first local twitch response is noted. Once the first local twitch response is obtained, the needling will be performed in an up-and-down fashion, performing 2- to 3-mm vertical motions with no rotations (fast-in and fast-out technique), at approximately 1 Hz for 25 to 30 seconds, with the aim of eliciting local twitch responses. The treating therapist can dry needle each trigger point identified in the gluteus medius with a maximum treatment time of 5 minutes.

Soft tissue mobilization will be performed on the patient's ipsilateral gluteus medius muscle with the patient in sidelying. The treating therapist will apply firm pressure with the palm and side of their hand. The treating therapist will mobilize the gluteus medius muscle in 4 separate directions (Proximal-Distal, Distal-Proximal, Medial-Lateral, and Lateral-Medial). The treating therapist will apply the pressure to reach the upper limit of the patient's tolerable discomfort. At any point in time the patient can request for the therapist to decrease the pressure applied. The treating therapist will perform soft tissue mobilization for 20 mobilizing strokes in each of the 4 directions.

Treating therapist will place hands on the patient's gluteus medius muscle and gently rub, but not apply enough pressure to treat the muscles trigger point. This placebo control is designed to account for hands on time from therapist in the 2 other treatment groups, as well as blinding patient to treatment group.

Patient will perform standardized hip and core exercises using body weight, and elastic bands for resistance. Exercises will take approximately 40 minutes to complete.

Isometric maximal voluntary contraction strength of the hip abductor muscles will be measured with a portable dynamometer. The dynamometer is placed so as the testing pad is positioned 5cm proximal to the lateral femoral condyle. Two to three maximal voluntary contraction trials will be permitted. The subjects will be instructed to produce their maximal force without any concern for the rate of force development. The duration of these contractions will be 5 seconds, and thirty seconds of rest will be given between trials. A third trial is completed only if the difference between the first two maximal voluntary contractions is >10%. • Hip abduction strength will be expressed as a percentage of the patient body weight.

Baseline,Immediately Post-Intervention (anticipated at 5 minutes after baseline testing), Immediately Post-Execise (anticipated to be 1 hour after baseline testing)

Patients will perform 5 single leg squats with the tested limb being the stance limb. Patient will keep hands on their hips and are encouraged to keep their hips level and the center of their knee in line with their second toe during the squat. Patient will be asked to rate their highest pain during the Single Leg squat test using the Numeric Pain Rating Scale (NPRS). The NPRS is an 11-point pain-rating scale ranging from 0 (no pain) to 10 (worst imaginable pain) to assess highest pain intensity during the single leg squat test. A change of 2 points on the NPRS has been found to be the minimal clinically important difference found previously in research ( Childs, 2005)

Baseline,Immediately Post-Intervention (anticipated at 5 minutes after baseline testing), Immediately Post-Execise (anticipated to be 1 hour after baseline testing)

Inclusion Criteria: Acute anterior knee pain of <90days Ipsilateral hip abductor weakness of >15% 2/10 pain with single leg squat Exclusion Criteria: Contraindication to dry needling or soft tissue mobilization Non-mechanical anterior knee pain Fear of needles

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