Results of Opening-wedge High Tibial Osteotomy Using Iliac Crest Allograft Compared to Iliac Crest Autograft

Inclusion Criteria: * Varus malalignment of knee with of without osteoarthritis: the angle between the articular surface and anatomical axis of tibia\< 82 degrees * at least 7.5 mm opening wedge is needed in medial proximal tibia to correct the deformity assessed during pre-op planning Exclusion Criteria: * symptomatic lateral compartment osteoarthritis of knee * rheumatoid arthritis or other inflammatory joint diseases * less than 100 degrees of knee range of motion * grade III laxity in knee collateral ligaments * history of surgery or fracture in the limb * \>15 degrees flexion contracture * age \<16 or \>60 years * \>20 degrees varus deformity * failure to attend follow-up visits * sever bone loss in medial tibial plateau or medial femoral condyle * \>1cm joint subluxation * presence of lateral trust during walking * presence of patella baja * skin derangements on medial proximal tibia * any form of nicotine addiction