Lumbar Hyperextension Fracture after Direct Anterior Total Hip Arthroplasty.

Introduction: Patients with stiff and brittle spines, such as those with ankylosing spondylitis (AS), are at an increased risk of intraoperative and post-operative complications. Specifically, patients with AS who undergo total hip arthroplasty (THA) with a direct anterior approach are at risk for vertebral fractures due to patient positioning and manipulation necessary to utilize this approach. To the best of our knowledge, this is the second publication discussing vertebral fracture following THA with direct anterior approach and the first depicting a hyperextension fracture. Case Report: A 78-year-old male with previous medical history of rheumatoid arthritis, AS, chronic back pain, and non-union left acetabular fracture and post-traumatic arthritis following a fall and subsequent open reduction and internal fixation presented for THA. The patient did not complain of back pain preoperatively. On post-operative day (POD) 1 he began complaining of back pain when ambulating. On POD 3, he complained of acute on chronic exacerbation of back pain, and computed tomography at that time was significant for unstable L2 hyperextension fracture necessitating T12-L4 fusion. Conclusion: Patients with a history of AS are at increased risk for vertebral fractures when having THA with a direct anterior approach. This approach subjects patients to extension forces that may cause damage to their vertebrae. Due to this risk, physicians should take care when planning their method for THA in this population and consider using alternative approaches or be more mindful of the patient's condition when positioning them intraoperatively.