Overcoming the Technical Challenges of Total Knee Arthroplasty in Patients Affected by Hereditary Multiple Exostoses: a Case Report and Literature Review

Hereditary multiple exostoses (HME), also known as familiar osteochondromatosis or diaphyseal aclasis, are an autosomal dominant inherited genetic pathology that is characterized by the presence of multiple benign osteochondromas. Knee deformity is common in patients with HME, with nearly a third of patients developing genu valgus. Total knee arthroplasty (TKA) has been used to correct valgus deformities with advanced knee osteoarthritis (OA). However, concomitant limb deformities and altered anatomy of the knee make this surgery particularly challenging. We present a case report and a mini-review of the literature on this topic. We present the case of a 50-year-old Caucasian woman, affected by hereditary multiple exostoses, who came to our attention for progressive pain in the right knee. Upon further examination, the knee had a prominent valgus alignment, concomitant valgus instability, and flexion contraction. The patient was treated with total knee arthroplasty using a semi-constrained design. The patient was re-evaluated at 24-month follow-up, and there were no signs of implant loosening, the knee function improved significantly, and the patient was very satisfied. Given the recurring technical difficulties of such procedure in these patients, we describe our experience as well as the need for preoperative planning, the use of appropriate constraint when required, the high frequency of ligament instability, bony defects, and patellar maltracking. TKA must be considered when necessary, in these patients, as good to excellent clinical results can be achieved and maintained, allowing for significant improvements in quality of life.