INTRODUCTION Midflexion instability in primary total knee replacement (TKR) is an evolving concept. Successful treatment of instability requires an understanding of the different types of instability. METHODS A literature review was performed to identify information pertinent to midflexion instability in primary total knee replacement, utilising PRISMA guidelines. Databases searched included ...

Dislocation and instability of the shoulder joint are rare occurrences in childhood. Traumatic, infectious, congenital, and neuromuscular causes of pediatric recurrent shoulder dislocations are reported before. Central nervous system infection in infancy may be a reason for shoulder instability during childhood. This situation, which causes a disability for children, can be treated successfully...

Patellar instability is a generic term that is used to describe patellar dislocation, patellar subluxation, and general symptomatic instability. Patellofemoral instability is a relatively difficult condition to treat; accurate management of the condition should take into account the anatomy of the joint and its stabilizing structures. The goal of any treatment should be to restore the normal an...

Because osseous abnormalities result in distal radioulnar joint instability, a sigmoid notch osteotomy is used to restore stability. This article describes a case of distal radioulnar joint volar instability treated with sigmoid notch osteotomy of the volar rim.A 22-year-old man presented with a 9-month history of right wrist pain with volar instability after a fall, which was treated conservat...

Relative risk of impingement and joint instability during sexual activities after total hip arthroplasty (THA) has never been objectively investigated. Hip range of motion necessary to perform sexual positions is unknown. A motion capture study with two volunteers was performed. 12 common sexual positions were captured and relevant hip joint kinematics calculated. The recorded data were applied...

When all the inputs of a parallel manipulator (PM) are locked, the manipulator is usually turned into a structure. When an uncertainty singularity occurs for a PM, the latter structure is unstable or, in other words, it may undergo infinitesimal or finite motion. Hence, the investigation of the uncertainty singularities of a PM can be reduced to the instability analysis of its corresponding str...

Failure of the distal radioulnar joint leads to significant dysfunction of the upper limb. Numerous surgical procedures have been suggested to address this problem. In degenerative arthritis, joint instability and ulnar stump dislocation after salvage procedures such as Darrach distal resection or Sauvé-Kapandji distal fusion, an ideal solution may not be available. The ultimate option to resto...