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Common peroneal nerve palsy (CPNP) is an uncommon but potentially disabling complication following total knee arthroplasty (TKA). Most cases are associated with severe valgus deformity or extensive lateral releases; however, we encountered a rare presentation following a medial parapatellar approach in a neutral knee. In this report, we present the case of a 55-year-old female with bilateral knee osteoarthritis and a BMI of 52.09 who underwent simultaneous bilateral TKA. The procedure was uneventful, and she was discharged the same day without neurological deficits. Shortly thereafter, she developed progressive right-sided foot drop, which prompted evaluation two months postoperatively. Examination revealed dense right foot drop with sensory loss below the knee. Needle electromyography (EMG) confirmed severe common peroneal neuropathy, in which we initiated conservative management with an ankle-foot orthosis (AFO), structured physical therapy, and serial EMG monitoring. Over the following months, the patient demonstrated steady neurological recovery, culminating in near-complete functional improvement at 11 months. This case highlights that CPNP can occur even without valgus deformity or lateral surgical exposure. Recognizing risk factors, especially morbid obesity, combined with early diagnosis, structured rehabilitation, and close follow-up, can lead to excellent outcomes.

Keywords: Total knee arthroplasty; Common peroneal nerve palsy; Medial parapatellar approach; Obesity; Foot drop