[Traumatic knee dislocation with popliteal vascular disruption: retrospective study of 14 cases].

PURPOSE OF THE STUDY: Complex femorotibial dislocation of the knee joint generally results from high-energy trauma caused by a traffic or a contact sport accident. Besides disruption of the cruciate ligaments, in 10-25% of patients present concomitant palsy of the common peroneal nerve and more rarely disruption of the popliteal artery. The purpose of this work was to assess outcome in a monocentric consecutive series of knee dislocations with ischemia due to disruption of the popliteal artery and to focus on specific aspects of management.

MATERIAL AND METHODS: This retrospective series included eleven men and three women, aged 18 to 74 years (mean 47 years). The right knee was injured in five and the left knee in six. Trauma resulted from a farm accident in six patients, fall from a high level in two, a traffic accident in three and a skiing accident (fall) in one. Two other patients with morbid obesity were fall victims. Nine patients had a single injury, two presented an associated serious head injury, one a severe chest injury, and one multiple trauma with coma, chest contusion, and abdominal lesions. One patient had a fracture of the distal femur with associated ischemia. Five knee dislocations were open with a popliteal wound for three and a posteromedial wound for two. Four patients presented total sciatic nerve palsy and nine palsy of the common peroneal nerve. The dislocation was documented in ten cases: lateral (n=1), anterior (n=4), posterior (n=5). For four patients, the dislocation had been reduced during pre-hospital care. Preoperative arteriography was available for eight patients and confirmed the disruption of the popliteal artery; the diagnosis was obvious in six other patients who were directed immediately to the operative theatre without pre-operative imaging. Revascularization was achieved with a upper popliteal-lower popliteal bypass using an inverted saphenous graft. The graft was harvested from the homolateral greater saphenous vein in eight patients and the contralateral vein in six. On average, limb revascularization was achieved after 10.07 hours ischemia. Intravenous heparin was instituted for 810 days followed by low-molecular-weight heparin. The dislocation was stabilized by a femorotibial fixator in nine patients and a cruropedious cast in five. An incision was made in the anterolateral and posterior leg compartments in twelve patients. A revision procedure was necessary on day one in one patient because of recurrent ischemia; a second bypass using an autologous venous graft was successful. One other 75-year-old patient also presented recurrent ischemia on day five; the bypass was reconstructed but the patient died from multiple injuries. Seven thin skin grafts were used to cover the aponeurotomy surfaces. Mean duration of the external fixator was 3.4 months. The five patients treated with a plaster case were immobilized for 2.7 months on average. Ligament repair was performed in three patients (one lateral reconstruction and one double reconstruction of the central pivot for the two others). A total prosthesis with a rotating hinge was implanted in two patients aged 67 and 74 years after removal of the external fixator at six and seven months. Failure of the ligament repair also led to arthroplasty in a third patient.

RESULTS: Blood supply to the lower limb was successfully restored as proven by the renewed coloration of the teguments and-or presence of distal pulses in 13 patients. Transient acute renal failure required dialysis in one patient. Four patients developed pin track discharges and there was one case of septic arthritis of the knee joint which was cured after arthrotomy for wash-out and adapted antibiotics. Outcome was assessed a minimum 18 months follow-up (average 22 months) for the 13 survivors. The three sciatic palsies recovered partially at five and six months in the tibial territory but with persistent paralysis in the territory of the common peroneal nerve. The nine cases of common peroneal nerve palsy noted initially regressed completely or nearly completely in three patients, partially in three and remained unchanged in three. The results were assessed as a function of the final knee procedure: outcome was satisfactory for the patients with a total knee arthroplasty. Outcome of the three ligamentoplasties was good in one, fair in one, and a failure in one (revision arthroplasty). Patients treated by immobilization without a second surgical procedure complained of joint instability with a variable clinical impact; their knee retained active flexion greater than 90 degrees and complete extension.

DISCUSSION: An analysis of the literature and the critical review of our clinical experience was conducted to propose a coherent therapeutic attitude for patients presenting this type of trauma. The prevalence of disruption of the popliteal vascular supply in patients with knee dislocation is between 4 and 20%. The rate is closely related to that of injury to nerves and soft tissue. Ischemia should be immediately suspected in all cases of knee dislocation. The pedious and tibial pulses must be carefully noted before and after reduction of the dislocation to determine whether or not there is an organic arterial lesion. If the pulses are absent initially, they should be expected to reappear strong, rapidly and permanently after reduction. Otherwise, arteriography should be performed. Dislocation stretches the artery between two points of relative anchorage in the adductor ring and the soleus arcade to the point of rupture. Repair requires a bypass between the upper popliteal artery and the tibioperoneal trunk using an inverted saphenous graft because the walls are torn over several centimeters. The traumatology and vascular surgical teams must work in concert from the beginning of the surgical work-up in order to establish a coherent operative strategy founded on primary reduction of the dislocation, installation of a fixator and then vascular repair and aponeurotomy incisions. It would be preferable to wait until the bypass is proven patent and wound healing is complete before proposing ligament repair. This should be done after a precise anatomic work-up to assess each ligament lesion. Bony avulsion or simple disinsertion can however be repaired in the emergency setting at the time of the bypass as well as any ligament rupture which is obvious and-or situated on the medial collateral approach. Secondarily, elements of the central pivot can be repaired in young patients with an important functional demand. Arthroplasty is not warranted except in the elderly patient. Dissection of the popliteal fossa or debridement of the wound enables a careful anatomic assessment of the nerve trunks. In the event of a peroneal nerve disruption, it is advisable to fix the nerve ends to avoid retraction. Beyond three months without clinical or electromyography recovery, surgical exploration is indicated. In the event more than 15 cm is lost, there is no hope for a successful graft. Complete knee dislocation is extremely rare. It can be caused by high-energy trauma associated with several ligament ruptures, particularly rupture of the central pivot observed in 10-25% of cases with common peroneal nerve palsy. Compression, contusion or disruption of the popliteal artery is very rarely caused by the displacement of the femur or the tibia. Limb survival may be compromised. Mandatory emergency restoration of blood supply will modify immediate and subsequent surgical strategies. There has not however been any study exclusively devoted to double joint and vascular involvement. Our objective was to present a critical retrospective analysis of a consecutive series of knee dislocations with ischemia due to disruption of the common popliteal artery treated in a single center and to describe the specific features of management strategies for a coherent diagnostic and therapeutic approach.