Article, Orthopedics

Lateral patellar dislocation with vertical axis rotation of 90?

Case Report

Lateral patellar dislocation with vertical axis rotation of 908

Lateral patellar dislocation with vertical rotation of 908 is rare. We describe a case of dislocation of the patella around its vertical axis after a direct traumatism on the medial edge of the patella. The closed reduction was carried out with success under general anesthesia.

Patellar dislocation is a relatively frequent lesion for young subjects. However, most are extra-articular. Intra- articular dislocation is rare and can occur around the horizontal or vertical axis of the patella. The side variety with a rotation of 908 around the vertical axis is exceptional. We report a traumatic case of patellar dislocation with a rotation of 908 according to the vertical axis, with orthopedic reduction.

An 8-year-old patient was admitted to the emergency department of the hospital Lucien Hussel of Vienne for trauma of the left knee after a fall from a staircase. He complained about sharp pain of the knee, with a functional impotence. The examination had objectified a flessum knee of 808, with an obviously luxated patella covered under the skin (Figs. 1 and 2). Palpation revealed that the articular facet of the patella looked anterolateral with a tended and twisted patellar tendon. The examination did not find any cutaneous injury or disorders of a vasculo-highly strung person. Standard radiographs objectified a side dislocation of the kneecap with rotation around its axis of 908 (Fig. 3). The orthopedic reduction had been carried out under general anesthesia by extending the member with pressure on the medial edge of the patella. The reduction was confirmed radiologically. An immobilization by a splint foundation of concrete was maintained for 4 weeks. The result was good, with complete return of the function of the knee and without aftereffect and repetition.

Intra-articular dislocation of the patella is a rare pathology [1, 2]. It can occur around the axis centers of the horizontal or vertical patella. Dislocation with rotation of 908 according to the axis vertical to the kneecap was described for the first time in 1844 by Cooper [3]. The exact mechanism is not clear, and several theories were proposed. Most cases were reported among Adolescent boys with an average age of 16 years [4]. Reichell [5] suggested that the laxity of the ligaments at the teenagers explains the great mobility of the kneecap and, thereafter, the great risk of dislocation in this category of young age, whereas similar

lesions would cause a tendinous rupture in adults. The traumatisms of high energy can cause other tendinous tears, ligamental or osteochondral, such as a depression of the patella in the femoral condyle [6]; these tears define the long-term forecast. Sporting accidents are the most reported cause [7]. The mechanism in these cases seems to be a direct traumatism on the side or medial edge of the knee, whereas this last is in extension with a contracted quadriceps. Most authors recommended an open reduction such as primary education process. Six similar cases were reported in the last 15 years; and in 4 cases, the multiple closed reductions had not succeeded, driving with a bloody reduction [8-10]. To reduce the risk of osteochondral lesions, many authors suggest a surgical reduction [11]. The course is often favorable with a good functional result [12].

The side variety of patellar dislocation with a rotation of 908 around the vertical axis is extremely rare. The preserving treatment can be tried each time the closed reduction is possible. The functional results are always satisfactory without after effects.

Fig. 1 Image showing side patellar dislocation with vertical rotation of 908 and attitude of the knee in inflection.

0735-6757/$ – see front matter D 2007

733.e2 Case Report

Fig. 2 Radiograph of the knee showing the side position of the

patella with rotation of 908. Fig. 3 Radiograph of control after the reduction in patellar


Elibrahimi Abdelhalim Abdelmjid Elmrini Fawsi Boutayeb

Department of Orthopaedic Surgery Alghasssani Hospital, UH Hassan II of Fe`s, Morocco E-mail address: [email protected]

Said Habi Kamal Maatougui Jean Marie Leleu

Department of Orthopaedic Surgery Lucien Hussel hospital of Vienne

French, France



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