Purpose of the study: High-energy varus or valgus ankle trauma causes severe injury to the capsule and ligaments. We describe a presentation associating massive tears of the lateral/medial collateral ligaments with a transversal wound of the corresponding malleolus. This wound results from excessive tension on the skin cause by the major varus/valgus. We have defined this injury as an open and severe ankle sprain (OSAS).

Material and method: This was a retrospective analysis. We search the databases of three participating centres using the corresponding diagnostic and therapeutic codes from January 2005 to January 2009. The identified files were screened to select patients with OSAS.

Results: There were 11 cases of OSAS. Eight involved the lateral side of the ankle and three the medial side. Mean age was 41 years (range 21–45). All patients were victims of a high-energy trauma (five motorcycle accidents) and four patients had fallen from a high point. Associated injuries were tendon section (n=3), section of the deep fibular nerve (n=2), and section of the anterior tibial artery (n=1). Pneumarthrosis was the only visible anomaly on the plain x-rays of seven ankles. Diagnosis was confirmed preoperatively in all cases clinically with varus-valgus stress manoeuvres.

Conclusion: OSAS is a rare misleading injury. Confusion with a common wound is possible. The risk is to miss acute instability and thus its treatment. The diagnosis should be proposed for all transversal wounds without contusion over the malleolus with normal x-rays.

Purpose of the study: The issue of patellar kinematics remains a difficult problem for patellar resurfacing during conventional or computer-assisted knee surgery, yet adequate knowledge is required for appropriate orientation of the patellar cut and insert positioning. The purpose of this study was to develop a non-invasive tool for in vivo kinematic analysis of the patellar tract and to compare results with the gold-standard invasive method.

Material and methods: A special experimental set-up designed for this study enabled experimental simulation of load-bearing flexion-extension cycles of the knee joint. Range of motion from 0 to 102° was imposed with a computer-controlled motor. The analysis was conduced on 14 complete lower limb cadaver specimens. Patellar kinematics was analyzed for each knee simultaneously with two systems: a non-invasive method using a low-dose stereoradiographic scan linked to a 3D reconstruction software; and the reference system using tripodes implanted on the patella and radio-opaque spherical markers. Six degrees of freedom were considered: three translations and three rotations. Sequential kinematic recordings were made by calculating the position of a patellar landmark in relation to a femoral landmark.

Results: The mean difference between the results obtained with the two systems was less than 1 mm for anteroposterior and vertical translations, greater for mediolateral translations. It was less than 2° for patellar flexion-extension, to the order of the motion itself for abduction-adduction, and to the order of 5° for horizontal tilt.

Discussion and conclusion: The non-invasive technique proposed here appears to be reliable for patellar translations and flexion, but need further improvement for tilt and adduction-abduction. This is particularly true for the 45° to 90° range of motion because of the difficult problem of determining the contours of the patella. Further developments for this tool are under way.