Time Difference Between Onsets of Lateral And Medial Hamstring Muscles During Gait in Patients With Patellofemoral Pain.
Condition: Patellofemoral Pain
MeSH terms: Patellofemoral Pain Syndrome
Study type: Interventional

Summary: 
      Early activation of lateral hamstrings (LH) in respect of medial hamstrings (MH) may cause
      abnormal knee abduction and external rotation moments in individuals. This situation may
      increase the risk of ligament injury and may be the reason for susceptibility of
      patellofemoral pain (PFP). The aim of this study is to compare the time delays in
      electromyographic studies between medial and lateral hamstrings in patients with PFP and
      asymptomatic subjects.
    

Detailed description: 
      Patellofemoral pain (PFP) is a very common complaint in younger population with still unclear
      and controversial etiology. It was suggested that a combination of intrinsic and extrinsic
      factors cause PFP. The strain of the retropatellar subcondral bone caused by excessive
      lateral patellar tracking is known to be the one among intrinsic factors (Thomee R.1999).
      Imbalance of the dynamics between knee extensor muscles, Vastus Medialis (VM) and Vastus
      Lateralis (VL), has also received a great research interest during last 10 years. However,
      uneven timing between onsets of counterpart knee flexor muscles, Lateral and Medial
      hamstring, were just considered as a possible etiological factor of the PFP (Patil S.2011),
      yet this hypothesis remains to be proven. The investigators aimed to investigate whether
      there is a relative time delays of the LH (biceps femoris, BF) and MH (semitendinosus, ST)
      during the walking at the self-selected speed in patients with patellofemoral pain. Even
      though dynamic EMG investigations are challenging because of cross-talks between muscles,
      hence difficult to determine clearly onset times, the investigators think that any
      information acquired during walking would be highly important because patellofemoral pain is
      mainly exaggerated by dynamic activities.

      15 patients who were diagnosed with PFP (age 28.73±7.44, height 169.73±7.09, weight
      67.47±14.31) and 15 asymptomatic subjects (age 30.47±6.22, height 167.87±7.81, weight
      67.87±13.48) were recruited in the study. The inclusion criteria for PFP subjects was
      presence of the anterior and retropatellar pain for minimum 2 months scaled as 3 in
      accordance with Numeric Analog Scale during at least two of the following activities: stair
      descending, ascending, squatting, prolonged sitting, jumping, sitting on the knees. Surface
      EMG was recorded from Medial Hamstring and Lateral Hamstring muscles at 1000 Hz sampling rate
      during walking at participants' normal walking speed. EMG data obtained from 5 gait trials
      were evaluated. The EMG traces were full wave rectified and low pass filtered at 50 Hz. Delay
      in timing before heel strikes between MH and LH was calculated. Statistical significance
      between differences in time delays was analysed using "paired sample t-test".
    

Intervention name(s): kujala patellofemoral pain scale; Surface EMG; Q angle measurement
Intervention type(s): Other; Diagnostic Test; Other
Intervention description(s): Kujala patellofemoral pain scale was used to evaluate knee functions of the PFP subjects.; The surface EMG electrodes (silver/silver chloride, pre-gelled, Ambu Blue Sensor, Denmark) (Konrad P.) with an interelectrode distance of 20 mm between centers were used to record an EMG signal during walking. Portable 8 channel (TELEEMG, BTS, Milan, Italy) with built in x10 amplifications, 10-450 Hz bandpass and sampling rate of 1000 Hz were used for recording. The location and orientation of the electrodes for each MH (ST) and LH (BF) were identified according to SENIAM (Surface ElectromyoGraphy for the Non-Invasive Assessment of Muscles) criteria.; Q angle measurement was applied to both patellofemoral pain and control group subjects in standing position.
Allocation: Non-Randomized
Intervention model: Parallel Assignment
Intervention model description: Participants which were included in the study were divided into 2 groups as patient group who included the patients diagnosed with Patellofemoral pain and asymptomatic group which was considered as control group.
Masking: Single (Outcomes Assessor)
Primary purpose: Screening
Keywords: onset , hamstring muscles, patellofemoral pain