Both extra corporeal shock wave and dexamethasone iontophoresisare effective in treatment of knee osteoarthritis but which one is more effective is not clear yet . so the purpose of this study was to investigate and compare between the effect of shock wave and iontophoresis in treatment of knee osteoarthritis . it was hypothesized that there will be no difference between the effect of shock wave and iontophoresis on treatment of knee osteoarthritis.

60 subjects with grade II knee osteoarthritis will be recruited from outpatient clinic of faculty of physical therapy and then they will be assigned randomly by sealed envelope into three groups ;group A (shock wave group) will received radial extracorporeal shock wave ,group B (Iontophoresis group ) will receive deaxamthasone iontophoresis and group c (control group) will receive traditional tratment ( stregnthening exerciseces) all treatment will be once session per week for four weeks .pain intensity ,knee ROM and knee injury and osteoarthritis outcome score physical function short (KOOS-PS).

Inclusion Criteria:

1. Symptomatic knee OA for at least 3 months according to clinical criteria of American College of Rheumatology
2. Radiologic findings had to be compatible with knee OA, with kelgren and Lawrence (K-L) grade 2 in a simple X ray .
3. Tenderness on medial tibial plateau
4. Intensity of pain: visual analogue scale equal to 5 or greater
5. Failure of two or more types of previous conservative treatment (medication, anti-inflammatory drugs, physical therapy, stretching, acupuncture, orthotics and others)

Exclusion Criteria:

1. Neuorological and vestibular system disorder, systematic inflammatory disease, steroid injections in the last six months
2. Any contraindication to magnetic resonance imaging or radiography, or trauma history on knee
3. history of previous knee surgery -