In computer simulations, the shape of the range of motion (ROM) of a stem with a cylindrical neck design will be a perfect cone. However, many modern stems have rectangular/oval-shaped necks. We hypothesized that the rectangular/oval stem neck will affect the shape of the ROM and the prosthetic impingement. Total hip arthroplasty (THA) motion while standing and sitting was simulated using a MATLAB model (one stem with a cylindrical neck and one stem with a rectangular neck). The primary predictor was the geometry of the neck (cylindrical vs rectangular) and the main outcome was the shape of ROM based on the prosthetic impingement between the neck and the liner. The secondary outcome was the difference in the ROM provided by each neck geometry and the effect of the pelvic tilt on this ROM. Multiple regression was used to analyze the data.Aims
Methods
There remains confusion in the literature with regard to the spinopelvic relationship, and its contribution to ideal acetabular component position. Critical assessment of the literature has been limited by use of conflicting terminology and definitions of new concepts that further confuse the topic. In 2017, the concept of a Hip-Spine Workgroup was created with the first meeting held at the American Academy of Orthopedic Surgeons Annual Meeting in 2018. The goal of this workgroup was to first help standardize terminology across the literature so that as a topic, multiple groups could produce literature that is immediately understandable and applicable. This consensus review from the Hip-Spine Workgroup aims to simplify the spinopelvic relationship, offer hip surgeons a concise summary of available literature, and select common terminology approved by both hip surgeons and spine surgeons for future research. Cite this article:
There is ambiguity concerning the nomenclature and classification of fractures of the ring of the second cervical vertebra (C2). Disruption of the pars interarticularis which defines true traumatic spondylolisthesis of C2, is often wrongly called a pedicle fracture. Our aim in this study was to assess the influence of asymmetry on the anatomical and functional outcome and to evaluate the criteria of instability established by Roy-Camille et al. We studied the plain radiographs and CT scans of 24 patients: 13 were judged to be asymmetrical, ten were considered unstable and 14 stable. Treatment was with a Minerva jacket in 15 fractures and by operation in nine. Surgery was undertaken in patients with severe C2 to C3 sprains. One patient with an unstable lesion refused operation and was treated conservatively with a poor radiological result. Our study showed that asymmetry of the fracture did not affect the outcomes of treatment and should not therefore influence decisions in treatment. The criteria of Roy-Camille seem to be reliable and useful. We prefer the posterior approach to the cervical spine, which allows both stabilisation of the fracture and correction of a local kyphosis.
