Transient Osteoporosis of Bilateral Knee Joints in Twin Pregnancy: A Case Report - A Valuable Addition to the Medical Literature.

INTRODUCTION: Transient osteoporosis (TO) is a rare, self-limiting condition characterized by the acute onset of joint pain and radiological evidence of periarticular osteopenia with bone marrow edema on magnetic resonance imaging (MRI). It most commonly affects the hip during the third trimester of pregnancy or the early postpartum period. Knee involvement is uncommon, and bilateral knee involvement is exceedingly rare, particularly in association with twin pregnancy. We report a rare case of bilateral TO of the knees in the early postpartum period following twin gestation, highlighting its clinical presentation, diagnostic workup, and management. CASE REPORT: A 34-year-old female presented in the early postpartum period after a twin pregnancy with severe bilateral knee pain and inability to bear weight, which began during the third trimester. There was no history of trauma, corticosteroid use, alcohol abuse, or systemic illness. Clinical examination revealed quadriceps wasting, joint line tenderness, and painful restriction of knee movements bilaterally. Laboratory investigations showed elevated ESR with normal rheumatoid markers. Plain radiographs demonstrated periarticular osteopenia of both knees. MRI revealed diffuse bone marrow edema involving bilateral femoral condyles and patellae, with minimal joint effusion, consistent with TO. The patient was managed conservatively with transnasal salmon calcitonin (200 IU daily for 3 months), calcium and Vitamin D supplementation, analgesics, and protected weight bearing. Significant symptomatic improvement was observed within 4 weeks, and a follow-up MRI at 6 months showed complete resolution of marrow edema. At the 1-year follow-up, the patient had regained a full, pain-free range of motion. CONCLUSION: Bilateral TO of the knee in pregnancy is an extremely rare clinical entity that should be considered in the differential diagnosis of severe atraumatic knee pain in late pregnancy or the postpartum period. MRI plays a pivotal role in early diagnosis. Conservative management with symptomatic therapy and pharmacological support, including transnasal calcitonin, may provide effective pain relief and functional recovery. Early recognition is essential to prevent complications such as insufficiency fractures.