chapter 10: Patellar Dislocation


Any direct blow to the patella may result in articular cartilage injury. Although the pattern of cartilage degeneration subsequent to direct trauma may simulate that noted in patients who have malalignment, the post‑traumatic course and subsequent treatment will often be different. In general, the clinician will approach direct trauma to the patella without dislocation as any other direct articular injury. Certainly, if there is a fracture, immobilization with reduction and fixation of the fracture will be necessary. Open reduction with tension band wiring after alignment of distracted and displaced articular fragments is generally most satisfactory (24).

Subsequent to blunt trauma (25), with or without fracture, articular cartilage breakdown is common. Many patients notice some crepitation, but many have little associated pain. Unfortunately, some of these patients eventually develop erosion of articular cartilage to bone and true arthrosis of the patellofemoral joint. It is important for the clinician to recognize when a patient has articular degeneration related to trauma as opposed to malalignment. In the former group, treatment should be directed to the articular surface itself, and procedures such as lateral retinacular release generally are not helpful. Lateral release should not be the treatment of choice for patients with blunt articular injury to the patella and subsequent arthrosis. In fact, some patients will become worse after lateral retinacular release when there is no pre‑existing malalignment.

Treatment of the patient with articular cartilage damage but no malalignment must be directed specifically to the articular surface, assuming that reflex sympathetic dystrophy has not evolved as a result of the injury. Selective burr arthroplasty or articular debridement may be helpful using arthroscopic technique in some patients if there is a localized lesion with exposed bone and some good or satisfactory surrounding articular cartilage to which contact stresses may be transferred. When patellar articular injury is extensive, and there is no evidence of reflex sympathetic dystrophy, some patients may benefit from tibial tubercle anteriorization or anteromedialization. This is most desirable if proximal articular cartilage on the patella is intact, because anteriorization of the tibial tubercle will result in a proximal shift of contact stresses as well as unloading the joint (26). As a last resort, patellectomy may be the procedure of choice to remove a badly damaged and widely eburnated patella.




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