Title : Congenital knee dislocation in a preterm newborn
Abstract:
Congenital knee dislocation (CKD) is a rare condition with an estimated incidence of 1 per 100,000 live births. It is characterised by hyperextension of the knee detected clinically at birth, and can either be an isolated finding or associated with other congenital anomalies or syndromes. Risk factors for CKD can be classified into intrinsic factors such as genetic anomalies, neuromuscular disorders, and extrinsic factors including mechanical anomalies such as packaging disorders, extended breech position. Its diagnosis may be suspected antenatally during second trimester ultrasound scans, but is confirmed by physical examination at birth. Clinically, CKD presents with anterior displacement of the tibia in relation to the femur, with or without joint dislocation. Initial assessment should include assessing the degree of hyperextension, identifying anterior skin grooves, and if the dislocation is reducible, to guide treatment and prognosis. Classification of CKD severity can be divided into three grades, based on clinical and radiological assessment from Tarek’s classification. They are divided into grade I (more than 90° passive flexion range of movement and radiological finding of simple recurvatum), grade II (30-90° passive flexion and radiological finding of subluxation/dislocation), and grade III (<30° passive flexion and radiological finding of dislocation). Treatment options of CKD are guided by its severity, ranging from conservative measures such as physiotherapy, serial casting or bracing, to surgical options of soft tissue release.
In this paper, a case is presented of Tarek Grade 1 CKD diagnosed at birth in a moderate preterm 32+3 weeks baby girl, who was born via emergency caesarean-section for maternal pre-eclampsia with baby in breech presentation, and subsequently admitted to high dependency for mild respiratory distress syndrome requiring positive pressure ventilation. At birth, clinical assessment revealed hyperextension of left knee with anterior skin folds present. She was treated conservatively within the first few hours of life with serial left above knee splinting, and had a good clinical outcome prior to discharge. Through this paper, CKD’s epidemiology, diagnosis, classification and management will also be discussed.
