Total knee arthroplasty in a young patient with achondroplasia.

Achondroplasia is a genetic skeletal dysplasia, characterised by dwarfism, with upper and lower limb deformities, that can lead to knee osteoarthritis; the surgical treatment is a challenge due to the particular joint anatomy variances. We present a 40-year-old woman, affected by achondroplasia with severe left knee osteoarthritis; the patient was treated conservatively with poor results. Between the ages of 12 and 17 years, she underwent multiple operative procedures for lower limb lengthening and a partial correction of the valgus deformity, by applying an external fixator. The patient was successfully treated with cemented posterior stabilised, fixed-bearing, total knee arthroplasty. The patient affected by achondroplasia, with severe knee osteoarthritis, should be considered for total joint replacement, which can be carried out with or without additional extra-articular osteotomy for alignment correction. Due to skeletal dysplasia in joint deformities, knee replacement requires careful preoperative planning and special technical considerations.