Painful flail lt knee post PPRP in 52 year old

52 yr old lad PPRP  had THR  rt side due to pain in a dysplastic hip 8 yrs back. followed by periprosthetic fracture 2 yeasr post op. Nov presents with pain lt knee at rest worse on wlking. cannot tolerate pain any more in the lt flail knee.  Attempted bracing to prevent the 30 degree hyperextension with no relief. Hence an RHK was done to eliminate pain and improve her gait secondarily.  In a flail limb do we do a rotaing hinge or simple hinge. the literature is a bit grey. we need a 5 degree recurvatum with a further stop ideally. We improved her gait and relieved pain for now with a link RHK with recurvatum stop