The outcomes that we reviewed included maintenance of the achieved correction , progression of osteoarthritis ( based on the Kellgren and Lawrence classification ) , severity of pain ( as assessed on a visual analog scale -LSB- VAS -RSB- ) , knee function ( as measured with the Hospital for Special Surgery -LSB- HSS -RSB- score and Knee injury and Osteoarthritis Outcome Score -LSB- KOOS -RSB- ) , walking distance , complications , and survival with conversion to a total knee arthroplasty as the end point .