[Diagnosis, Treatment and Complications of Knee Dislocation: a Retrospective Study].

PURPOSE OF THE STUDY Acute knee dislocation is a less common injury of the knee joint. It is, however, a serious injury with a high rate of nerve and vascular damage and it is considered a limb threatening injury with long-term functional disability, which can ultimately lead to amputation. Knee dislocations constitute less than 0.5% of all joint dislocations. Most of these injuries occur in highenergy traumas and careful diagnosis can identify the patient at risk of this injury. MATERIAL AND METHODS The total number of patients with knee dislocation was 37. The incidence of knee dislocation was 2.5 patients per year. The mean age of patients was 49 years. After the evaluation of blood supply to the limb and before the examination of the ligament injury, routine X-ray views of the affected joint were performed. It was necessary to confirm good blood supply of the limb, in which knee dislocation had been suspected. In patients with reduced knee joint and asymmetric pulses in the lower limb, CT angiography was indicated. The absence of peripheral pulses and the presence of serious clinical signs of peripheral blood supply disruption in case of the reduced knee or irreducible knee dislocation necessitated immediate revision by a vascular surgeon performed in the operating room. RESULTS Dislocation of the knee without TKA (a total of 34 cases) was caused by a high-energy trauma in 19 cases (56%) and in 7 cases (21%) it was a part of polytrauma. The most common was a motorcycle accident, namely in 7 cases (21%). In 12 cases (35%), it was a low-energy trauma, a fall or a slip while walking. In three cases (9%), the patients suffered an open knee dislocation. In 18 patients (47%), no knee surgery was performed. The knee ligament injury was treated non-operatively through knee brace fixation. An open revision with sutures of injured ligament structures and knee capsule was performed in 16 patients (42%). In two cases, above-the-knee amputation was done. External fixation was performed in two polytrauma patients. Three cases of infectious complications were reported. Nerve lesions were observed in 9 cases (25%). Vascular lesions were recorded in 9 cases (25%). Deep vein thrombosis was observed in three cases in our study group. The Lysholm knee questionnaire was used to assess subjective difficulties. DISCUSSION In agreement with the literature, these injuries occur most frequently when riding on motorcycle. The patients, in whom a vascular lesion was identified and revascularisation performed within 8 hours, showed a significantly lower incidence of amputations (11%) compared to those who underwent surgery after 8 hours (86%). Majority of vascular surgeons consider 6 hours to be the time limit for the performance of vascular reconstruction since a surgery performed after 6 hours is accompanied by a higher complication rate. Currently, the aim of the final treatment is to perform anatomic suture or reconstruction of knee ligaments and meniscus to achieve a stable, pain-free, functional knee and to prevent any complications. CONCLUSIONS Knee joint dislocation ranks among less common injuries that can be accompanied by a vascular injury in 20% on average and a nerve lesion in 10-40% (around 25% on average). A negative X-ray in spontaneous reduction of knee dislocation can be misleading for proper diagnosis. It is crucial to rule out a vascular injury that might be a limb threatening. In case of a vascular lesion, an early reconstruction of vascular supply is necessary within 6 hours after the injury. The revascularisation performed later is accompanied by a high risk of complications and can ultimately lead to above-the-knee amputation. It is most appropriate to refer such serious injuries to specialised trauma centres that avail of necessary equipment and experience with treating the patients who sustained such complicated orthopaedic injuries. As to the ligament reconstruction, most surgeons prefer to postpone the procedure in majority of cases by 10-14 days. Key words: knee dislocation, vascular injury, neurologic injury, ligament reconstruction, irreducible dislocation.