Atypical Fracture of Femur in Association with Familial Hypokalemic Periodic Paralysis: A Case Report

Introduction: Hypokalemic periodic paralysis (HPP) is an important and a reversible but rare cause of paralysis. Periodic paralyses are of two types. The first one is primary which is also known as familial type and the second one is secondary periodic paralysis which is due to other underlying pathologies [1]. Important secondary causes can be categorized as metabolic, infectious and losses from the body, etc. [2]. HPP associated with bony abnormalities in form of spontaneous atypical fractures in femoral shaft with coxa vara is an unusual presentation.

Case report: Here is a case report of 26 year old lady who presented with pain in the proximal part of right thigh and weakness in both the upper and the lower limbs. She was diagnosed as familial HPP (FHPP) with atypical fracture of proximal third diaphysis of femur. Confirmation of the expected diagnosis was done with history, laboratory tests, and plain radiographs. Previously also, she had similar episode of weakness and opposite side femur atypical fracture.

Conclusion: Association of atypical femur diaphysis fracture and FHPP is a rare presentation of an uncommon disease but should be kept in mind whenever treating any HPP patient. The patient complaining of pain in limbs should be taken seriously as atypical fractures are prone to be missed. In future, further genetic studies are required to establish this rare association.