Periprosthetic fractures are a recognized complication of total knee arthroplasty. Fractures may occur intraoperatively or postoperatively, and risk factors have been identified that may predispose an individual to such a complication. We report 7 cases of periprosthetic tibial fractures after low contact stress total knee arthroplasty, a complication encountered by the senior author (D.E.B.) only after a change in practice from a cemented implant to a cementless one. In light of this previously unreported complication in our unit, we attempted to identify common features within this group of patients that may have contributed to fracture occurrence. Statistical analysis revealed a highly significant (P<.005) risk of periprosthetic tibial fracture in patients with a preoperative neutral or valgus knee. Age, gender, and diagnosis did not appear to increase the risk of fracture significantly. All patients displayed evidence of reduced bone mineral density in the lumbar spine and femoral neck regions on dual-energy x-ray absorptiometry scanning. Patients with a preoperative neutral or valgus knee and local evidence of osteopenia represent a high-risk group, in whom particular care in alignment should be taken. In this group, it may be preferable to have the tibial component inserted with cement fixation.