Irreducible, incarcerated vertical dislocation of patella into a Hoffa fracture

Abstract

Rotational dislocations of patella, which involve rotation of the patella around a horizontal or vertical axis are rare. These rotational dislocations of patella are difficult to reduce by close methods. These dislocations can have associated osteochondral and retinacular injury. We report a case of a 20-year-old male who presented with swelling and pain in the right knee following a motor cycle accident. Radiological evaluation using the computed tomography revealed a patellar dislocation with a concomitant Hoffa fracture. Patella was rotated around the vertical axis and was incarcerated into the Hoffa fracture. This is a very rare injury and first of its kind to be reported. The difficulties in diagnosis, mechanism of injury and management have been discussed. We feel closed reduction of such an injury is likely to fail and open reduction is recommended.

Vertical patellar dislocation: A pediatric case report and review of the literature

“… 15-18 Garrison described a similar mechanism where the blow is directed at the medial patellar edge, causing the articular surface to face laterally, 8 which has been described less often in the literature. 19-21 Traumatic injuries with non-specific directionality have also been described and include motorcycle accidents, 22 , 23 a collision with the wall while running, 14 falling out of a window, 24 a rollercoaster accident, 25 falling down a staircase, 26 crashing while operating a lawnmower, 27 falling off a ladder, 17 slipping on ice, 28 and a soccer collision. 29 Before reduction can be completed, it is important to determine the direction of the patella articular surface.…”

“…We recommend a closed reduction as the first line of treatment in the absence of ipsilateral fractures or hemarthrosis. 6 , 22 , 23 , 25 Of note, Corso et al stated that extra-articular VPDs lodged against the lateral femoral condyle warrant open reduction. 19 However, a closed reduction of an extraarticular VPD was achieved as early as 1982.…”

A rare case of Hoffa fracture combined with lateral patellar dislocation

“…More rarely, this injury is seen in combination with patellar dislocation [3] . Beside dislocation of the patella, the Hoffa fracture is also described with knee dislocation [4] , femoral shaft fracture [5] , meniscal tear [6] , bicondylar fracture [3] , or incarceration of the patella into the fracture [7] . Therefore, we recommend a CT scan for analysis of the fracture pattern and an MRI, if there is any hint for combined injuries.…”

Irreducible Patellar Dislocation; Incarcerated into a Distal Femur Fracture: A Case Report and Review of the Literature

“…Other less common types of patellar dislocation have been described in the literature, including medial, superior (5,6) and with rotation about the horizontal (7) or vertical axes (8). Rotational patellar dislocation is most often irreducible and has a high incidence of chondral damage (9).…”