DO WE NEED TO CEMENT FEMORAL STEMS IN OSTEOPETROSIS?

Osteopetrosis is a rare condition characterized by an increased bone density. Patients with osteopetrosis represent a greater orthopaedic surgical challenge for its hard, sclerotic, and brittle bone and its reduced or virtual medullary canal rendering femoral canal preparation difficult from overheating during reaming. The purpose of this study was to describe 1) whether cemented or cementless femoral stems have better implant survival in THA for patients with osteopetrosis and 2) the rate and nature of complications after THA in these patients. A retrospective descriptive Canadian multicentre (n=23) study was conducted involving all orthopedic centers treating patients with osteopetrosis. Osteopetrosis patients who underwent THA in the treatment of primary osteoarthritis or secondary to a hip fracture were identified after a survey of The Canadian Arthroplasty Society members. Hospital databases from nine participating centres identified cases between July 1997 and February 2023. Medical charts and databases were reviewed for patient demographics (age, gender, Body Mass Index, medical comorbidities, previous hip surgery, mechanism of fracture, surgical indication), surgical data (femoral stem fixation (cemented or cementless) and post-operative orthopedic complications. Available imaging studies at the latest follow-up were analyzed by an independent examiner to grade the probability of femoral implant loosening. A total of 22 THA, 10 cemented and 12 cementless, from 18 patients were censed Canada-wide and included in this study. The mean age at THA was 45.6 ± 19.1 years (range 18 – 76.1), most of them (70%) were female. The mean follow-up time was 9.1 ± 5.9 years (range 1-26). The 10-year survivorship for femoral implant revision is better for cementless stems (89% vs 71%, p=0.18) without reaching statistical significance. THA with cementless femoral stem also have a better 10-year survivorship for reoperation for all-cause 89% vs 52% (p = 0.03). Intraoperatively, four cases (18.2%) sustained an acetabular wall fracture and/or an acetabular column fracture during the insertion of a press fit non-cemented cup while three patients (13.6%) had a femoral shaft fracture. Orthopedic postoperative complications were significantly more frequent with a cemented stem (50% vs 8.3%, p=0.04). Post-operative complications led to a total of six reoperations (4 revisions): five involved cemented stems and one involved a cementless stem (p= 0.04). Despite a low prevalence, orthopedic surgeons may encounter patients with osteopetrosis in need of THA. These patients usually present with normal general health and bone morphology as well as with normal life span. In this Canadian series, cementless implants were likely to have better 10-year survivorship when considering femoral stem revision and all cause reoperation when compared to cemented stems.