Interest of short implants in hip arthroplasty for osteonecrosis of the femoral head: comparative study "uncemented short" vs "cemented conventional" femoral stems.

PURPOSES: Osteonecrosis of the femoral head (ONFH) is a dramatic condition resulting in joint destruction in the late stages. Total hip arthroplasty allows function recovery with satisfactory implant survival. Recently, the use of uncemented short stems has been suggested to improve the conservation of bone stock. METHODS: We performed a retrospective study on 16 hip arthroplasties-11 patients-implanted for ONFH between 2008 and 2017. We aimed to compare the outcomes of the two types of arthroplasty-"uncemented short" vs "cemented conventional" femoral stem-in terms of pain (visual analogue scale), function (Harris Hip Score), and survival (radiography). RESULTS: We included six  "uncemented short" and ten "cemented conventional" femoral stems. Mean pre-operative EVA was 7.5 and the mean HHS was 40.3. At last follow-up of seven years, mean VAS was 1.2 (SD ± 0.83) in the "uncemented short" group and 1.6 (SD ± 0.97) in the "cemented conventional" group. Mean HHS was 94 (SD ± 0.81) in the "uncemented short" group and 92.6 (SD ± 2.69) in the "cemented conventional" group. However, radiographic analysis revealed a lower stress shielding in the "uncemented short" stem group. One complication occurred (hip dislocation in the "cemented conventional" stem group). CONCLUSION: Uncemented short stems total hip arthroplasties may be an interesting alternative to more conventional implants with similar functional results but less stress shielding and a bone stock economy in this young population of patients.

Traumatic cervical spine injuries in a patient with pycnodysostosis.

Pycnodysostosis is a rare hereditary disease, characterized by systemic bone sclerosis. Susceptibility to long bone fractures is characteristic, whereas vertebral fractures are extremely rare. We report a case of a 21-year-old man with a past history of pycnodysostosis and spontaneous leg fractures who was admitted in hospital for a neck pain after a banal fall. Radiological examination revealed C1-C2-C3 posterior arch fractures with a C3-C4 left articular fracture dislocation. A surgical stabilization was decided but refused by the patient. To the best of our knowledge, this is the first publication that reports pycnodysostosis with cervical spine traumatic staged injuries.