pseudoarthrosis

Pseudoarthrosis, or false joint, is a type of fracture nonunion in which healing fails to produce a stable, solid bone ends and there is continued motion at the fracture site. Over time a fibrous or fibrocartilaginous tissue, and sometimes a synovial-like lining, may form and simulate a joint. It most often involves the tibia, followed by the femur, clavicle, and humerus, but can occur at any bone.

Classification typically distinguishes by biology and mechanics. Hypertrophic pseudoarthrosis shows abundant callus formation with preserved biologic potential but insufficient stability. Atrophic and oligotrophic forms have poor biologic activity with little or no callus. Causes include mechanical instability, inadequate immobilization, infection, compromised blood supply, and systemic factors such as smoking, diabetes, malnutrition, or certain medications. Inflammation and previous surgeries can also contribute.

Clinically, patients may have chronic pain, swelling, deformity, and a palpable or visible gap with movement at the fracture site. Diagnosis combines history with radiographs and often CT or MRI. Radiographs show persistent fracture lines, lack of progressive healing, and varying degrees of instability; hypertrophic cases show progressive callus despite motion, whereas atrophic forms show little or no callus.

Management aims to achieve stability and a biologically favorable environment for healing. Nonoperative options are limited for established pseudoarthrosis and may include prolonged immobilization or electrical bone stimulation in select cases. Most cases require surgical treatment with stabilization (intramedullary nailing or plating) and bone grafting to restore structural continuity. Biological augmentation (autograft, allograft, or growth factors) and vascularized grafts may be used for poor biology. Addressing infection, metabolic factors, and smoking cessation is essential. Prognosis varies by location and biology but successful union can be achieved in a substantial proportion of patients with appropriate treatment.