Successful total hip arthroplasty for patient with TCIRG1-associated autosomal recessive osteopetrosis

INTRODUCTION AND IMPORTANCE: Autosomal recessive osteopetrosis (ARO) is a group of disease characterized by osteoclast dysfunction inhibiting bone resorption and bone turnover, with TCIRG1-associated ARO leading to autosomal recessive infantile malignant osteopetrosis (OPTB1, MIM entry number # 259700). While most patients with TCIRG1-associated osteopetrosis present a malignant clinical course and shortened lifespan, a few cases of mild osteopetrosis associated with TCIRG1 have been reported recently. In this study we report a rare case of non-malignant TCIRG1-associated osteopetrosis, with detail clinical characterization, genetic analysis and underwent successful total hip replacement surgery. CASE PRESENTATION: 24-year-old female patient came to us with limp gait, hip pain in both sides, severe stiffness. She suffered multiple fractures, bilateral hip osteoarthritis, right leg was 2 cm shorter compared with left leg. The patient had a limp gait due to severe pain and leg length discrepancy. CLINICAL DISCUSSION: Whole Exome Sequencing, result of genetic analysis shown the patient had a compound heterozygous genotype at TCIRG1 (c.1194dup, p.Gly399ArgTer and c.334G > A, p.Gly112Arg). Total hip replacement was performed. The joint exposure and femoral canal reaming was difficult due to complete deformity of femoral head, loss of canal and high bone density. Post-operation period was uneventful; the patient rehabilitated as planned without further complication. CONCLUSION: This is the first case of TCIRG1-associated osteopetrosis reported in Vietnam and one of the few cases of non-malignant TCIRG1-associated osteopetrosis. This case report suggests that total hip replacement is a viable option for the treatment of hip osteoarthritis in patients with mild form osteopetrosis.