We report a case of ossification of the posterior atlantoaxial membrane associated with an os odontoideum in a 46-year-old woman. She developed myelopathy following a minor motor vehicle accident. The patient underwent posterior atlantoaxial arthrodesis and resection of the ossified lesion and recovered uneventfully. Long-standing atlantoaxial instability might have played a role in ectopic oss...

Magnetic resonance (MR) imaging can be a very useful tool in the evaluation of instability in the athlete's shoulder. Technical options of MR imaging, such as arthrography, higher power magnets, and shoulder positioning, have enhanced MR evaluation of the shoulder. This update discusses the application of new MR techniques to a variety of shoulder instability patterns, including anterior instab...

J Bone Joint Surg [Br] 2010;92-B:651-5. Received 30 September 2009; Accepted after revision 26 January 2010 We present the long-term outcome, at a median of 18 years (12.8 to 23.5) of open posterior bone block stabilisation for recurrent posterior instability of the shoulder in a heterogenous group of 11 patients previously reported on in 2001 at a median follow-up of six years. We found that f...

We place a standard Dirichlet process prior on the inverse-link function of a binary regression model and study the posterior distribution as the prior precision parameter converges to zero. Simple closed-form expressions are available for the limiting posterior density of the regression parameters and the posterior predictive distribution. This limiting posterior exhibits instability as the sa...

BACKGROUND It has been recognized that there is a distinction between shoulder laxity and shoulder instability and that there is a wide range of normal shoulder laxities. Our goals were (1) to evaluate if the ability to subluxate the shoulder over the glenoid rim in patients under anesthesia would be more prevalent than the inability to do so, (2) to determine if patients with a diagnosis of in...

Posterior tibial tendon dysfunction is considered one of the most common causes of progressive adult acquired flatfoot deformity. The etiology leading to the dysfunction of posterior tibial tendon remains controversial. The purpose of this study was to quantify strain on the posterior tibial tendon in cadaver feet exhibiting hyperpronation caused by flexible instability of the talotarsal joint ...

Although lumbar instability is considered to be responsible for the majority of chronic or recurrent backaches, the word ‘instability’ is still poorly defined. A number of different definitions exist, but as yet there are no clear and validated clinical features by which instability might be diagnosed. It is also not clear how instability as such might set up pain and disability. It is generall...