The objective of this study was to evaluate the conditions of ankle stability and the morphological and/or lesional factors in sprains that determine when instability becomes chronic. It is based on a review of the literature and the data from the 2008 Sofcot symposium. The biomechanics of the ankle cannot be reduced to a simple flexion-extension movement with one degree of freedom as characterized by the talocrural joint: its function cannot be dissociated from the subtalar joint, allowing the foot to adapt to the ground surface. Functional stability is related to the combination of the particular biometry of the joint surfaces and a multiaxial ligament system. The bone morphology of the talus, shaped like a truncated cone, explains the potential instability in plantar flexion; the radii of curvature of the talar dome have a variable mediolateral distribution: most often the medial radius of curvature is inferior to the lateral radius of curvature (66%), sometimes equal (19%), or inverted (15%). Joint kinematics, combining rotation and slide, can therefore be modulated by the talar morphology, explaining the occurrence of at-risk ankles. Ligament stability relies on the organization in three parts of the lateral collateral ligament and the specific subtalar ligaments: the cervical and the talocalcaneal interosseous ligament. The different injury mechanisms are largely responsible for the sequence of ligament lesions: the most frequent is inversion. The first ligament stabilizers correspond to the cervical and anterior talofibular ligaments; the talocalcaneal ligament, by its oblique orientation, is solicited when there is a dorsal varus-flexion component. In chronic instability, these mechanisms explain the onset of associated lesions (impingement, osteochondral lesions, fibular tendon pathology), which can play a role in instability syndrome. Ligament lesions determine laxity, characteristic of mechanical instability. Functional instability goes along with proprioceptive deficiency. There are postural factors such as varus of the hindfoot that favor instability. Knowledge of all these factors, often associated, will provide a precise lesional assessment and treatment adapted to the instability.

II (randomized prospective study).

Level IV. Retrospective study.

This paper purpose is to suggest an in-depth approach to diagnose the causes and lesions associated with and consecutive to chronic ankle instability due to ankle collateral ligament laxity. The different therapeutic and medicosurgical options adapted to this diagnostic approach are identified. The diagnostic aim is to precisely locate the ligamentous injuries of the tibiofibular, subtalar, talar and calcanean system, to identify the predisposing factors such as the hindfoot morphology, and any lesions associated with chronicity: anterolateral impingement, fibular injury, osteochondral lesions of the talus dome and early osteoarthritis. Clinical tools are used in particular to identify areas of pain and for comparative analysis of mobility and laxity (ligament testing). There are also radiological tests, weight-bearing plain X-ray (stress X-ray), (alignment of the hind foot, with a Meary view [metal wire circling the heel], arthrosis), dynamic images to confirm and quantify laxity (manually, with a Telos device, with patient-controlled varus) and also more sophisticated techniques (ultrasound, CT arthrogramm, gadolinium enhanced MRI, MR arthrogramm) to identify ligament, tendon and cartilage damages. They are adapted to the lesions which have been identified in the diagnostic work-up: conservative first, to treat proprioceptive deficits (a new neuromuscular reprogramming technique which emphasizes muscle preactivation) and any static disorders (plantar orthotics); then surgical, to repair any collateral ligament (or sometimes subtalar) injury with three types of procedures: tightening the capsuloligamentous structures, ligament reconstruction with reinforcement (using the fibrous periosteum, the frondiform ligament (of Retzius) or tendinous reconstruction with the plantaris muscle, the peroneus tertius or even the calcanean tendon) and tendon tansfer procedures using all or part of the peroneus brevis (whole peroneus brevis and half peroneus brevis procedures). Any additional surgical procedures which may be indicated based on the results of the diagnostic work-up are performed at the same time as primary surgery when possible as needed (medial complex repair, calcaneal realignment osteotomies, talus osteochondral injuries debridment or fixation, anterior and posterior impingement suppression, tendon tears repair). The goal of this diagnostic and therapeutic approach is to stop the progression of laxity and to protect the ankle against degenerative arthritis, which is the main risk in these chronic conditions.

Excision is not a suitable treatment for all comminuted fractures of the radial head. In elbows where instability can be predicted, a replacement arthroplasty of the radial head is more effective. The aim of this paper was to present the medium-term results of the Judet floating radial head prosthesis. This operation was performed on 14 patients between 1992 and 2003, of whom 12 were reviewed at a mean follow-up of five years and three months (1 to 12 years). The outcome was assessed using the Mayo elbow performance score and a modified Disability of Arm Shoulder Hand (DASH) questionnaire. There were six excellent results, four good, one fair and one poor, as graded by the Mayo score. The mean DASH score was 23.9/100 (0 to 65.8/100). The only significant complication occurred in one patient who developed a severe complex regional pain syndrome. There were no patients with secondary instability of the elbow, implant loosening, cubitus valgus, osteoporosis of the capitellum, or pain in the forearm and wrist. Our experience, combined with that of other authors using this device, has encouraged us to continue using the Judet prosthesis in comminuted fractures of the elbow where instability is a potential problem.