The Planovalgus Foot: A Harbinger of Failure of Posterior Cruciate-Retaining Total Knee Replacement

The etiology of posterior tibial tendon insufficiency is multifactorial; the disorder may be due to chronic attrition, rheumatoid arthritis (in 13% to 64% of cases1), chronic overpronation, degenerative joint disease, or Charcot neuropathy. More than half of the affected patients report no history of trauma. Rather, an insidious and progressive flatfoot may develop with or without medial or lateral pain in the hindfoot2. Patients with posterior tibial tendon insufficiency and a planovalgus foot demonstrate abnormal kinematics during the gait cycle, including lateral shift of the tibiotalar contact area3 (Fig. 1), functional malalignment3, increased valgus stress at the knee4,5, and relative internal rotation of the tibia and talus (external rotation of the foot)6. The offset of the mechanical axis of the lower extremity increases with the severity of the hindfoot deformity3. Consequently, these changes raise concern about potential problems with an ipsilateral total knee arthroplasty. The purpose of this study was to evaluate the relationship between failed total knee arthroplasties and ipsilateral posterior tibial tendon insufficiency.