Total Knee Arthroplasty in a Patient With Neurofibromatosis 1.

Neurofibromatosis 1 (NF1) is a rare genetic syndrome that leads to the development of neurofibromas and increases the risk of malignancy, including malignant peripheral nerve sheath tumors. Patients with NF1 often have other orthopaedic manifestations, including short stature, osteopenia, and dysplasia. A 47-year-old patient with a history of NF1 and multiple neurofibromas of the right lower extremity presented with a severe valgus deformity, instability, and osteoarthritis of the right knee that was debilitating to daily life. Over time, the patient lost proprioception and potentially some sensation to the right knee with neurofibroma formation, leading to the development of Charcot arthropathy of the right knee with secondary osteoarthritis. The preoperative workup consisted of a magnetic resonance imaging of the knee to confirm no malignancy was present and templating to ensure the standard implant size was amenable for the patient. A primary total knee arthroplasty was performed with a cemented-stemmed hinged knee implant. At 6 months post-surgery, the patient had a dramatic improvement in her pain and quality of life.