In unicompartmental knee arthroplasty (UKA) indicated for medial compartment osteoarthritis, overcorrecting the mechanical axis into excessive valgus is a critical technical error. What is the primary catastrophic consequence of this specific overcorrection?

Explanation:
The correct option is c. The fundamental biomechanical goal of a medial UKA is to slightly undercorrect the varus deformity, intentionally leaving the limb in very mild varus to mimic the patient's pre-disease state and maintain normal ligamentous tension. Overcorrecting the alignment into a valgus position violently shifts the mechanical weight-bearing load into the previously healthy, unresurfaced lateral compartment. This dramatically and rapidly accelerates lateral compartment osteoarthritis, leading to early clinical failure and necessitating a complex revision to a total knee arthroplasty. Reference: Scott WN. Insall & Scott Surgery of the Knee.