The intramedullary nailing using a single knee incision for treatment of extraarticular floating knee (nine cases).

CONTEXT: Floating knee injuries are uncommon and complex injuries. Management of this injury has been variously described in the literature. AIMS: We present the outcome of the intramedullary nailing using a single knee incision for treatment of extraarticular floating knee.
MATERIALS AND METHODS: We report a retrospective series of nine patients with extraarticular floating knee.
RESULTS: There were seven men and two women with an average age of 35 years. At least one of the fractures was open in three cases. The average Injury Severity Score was 17. According to Fraser's classification, 100% of the cases are type I. All our patients were treated by the intramedullary nailing using a single knee incision. The mean operating time was 146 min. The mean follow-up is 19 months. According to the Karlström criteria, the end results were excellent in two cases, good in four, acceptable in two, and poor in one. Bone union was achieved in eight cases with an average period of 93 days.
CONCLUSIONS: The intramedullary nailing using a single knee incision has shown in this series better results.

INTRODUCTION

The floating knee is a concept defined by Blake and Mcbryde[1] to describe the ipsilateral fractures of the femur and the tibia, the most often encountered aspect is the extraarticular floating knee. It often results from high-energy trauma and is usually accompanied by other potentially vital lesions.[23]

If the surgical treatment is favorable, the osteosynthesis techniques have evolved with the generalization of the anterograde than retrograde locked nailing, so the goal of our retrospective study is to highlight the long-term outcomes of the double nailing with single incision technique, which mean retrograde for the femur and anterograde for the tibia in the treatment of extraarticular floating knee.

MATERIALS AND METHODS

This was a retrospective study of 11 patients treated between 2008 and 2011 for ipsilateral femoral and tibial diaphyseal fractures. Two patients were excluded from the study (lost of view), so only nine patients were included. The inclusion criteria were referring to the existence of extraarticular floating knee (type I classification Fraser et al.,[4]) treated by the technique of double nailing all by the knee. Joint floating knee (type II classification of Fraser et al.,[4]) and floating knees treated by other techniques were excluded.

Locoregional examination looked for skin opening (classified according to the classification Cauchoix et al.,[5]), vascular or nerve damage, impairment of the central pivot of the knee, and other lesions. The general examination sought for associated lesions. The severity of the floating knee was evaluated using the Injury Severity Score (ISS) defined by Baker et al.[6]

The radiological analysis of the lesions was made using the classification of Winquist and Hansen[8] for bone comminution and classification of Fraser et al.,[4] for histological types [Figure 1].

Figure 1

Fraser's classification

The fixation of the fractures consisted of a double nailing retrograde for the femur and anterograde for the tibia. This surgery was performed on an ordinary table, with a single internal parapatellar incision and a single installation [Figure 1]. The assessment criteria were surgical technique, operative time, per and postoperative complications, measuring the total operative bleeding (that was based on the calculation of the cell volume lost[9] which was difficult due to the emergency), and finally the length of hospitalization.

The clinical results were evaluated with the score Karlström and Olerud[10] [Table 1]. The radiological results were judged by the time of consolidation, the occurrence or not of the nonunion, and the presence or absence of the malunion.

Table 1

Karlström and Olerud score

RESULTS

During the trauma, the average age was 35 years (19-52years). The gender distribution was predominantly male with seven men and two women. The fracture concerned the right side in five cases and the left in four cases.

The floating knee was closed in six patients. The femoral fracture was open in one case (stage I) and the tibial fracture was open in two cases (one case stage I and one case stage II). No vascular nerve or central pivot damage has been found. The association with other lesions was common: Two head injuries, one case of abdominal trauma, and other one of maxillofacial trauma. The mean ISS score was 17. Three patients had a score superior than 18 considered as a polytrauma.

According to the classification of Fraser et al.,[4], all our patients have a type I floating knee [Figure 2]. For the femur fracture we had five cases of distal third, four cases of middle third. Concerning the tibia fractures, we found four cases of the middle third, three cases of proximal third and two cases of distal third. According to the Winquist and Hansen's classification,[8] we noted three type I fractures, four type II fractures, and two type III fractures.

Figure 2

(a) Floating knee type I (b) Double nailing technique all by the knee (c) 11 months follow-up

The period of management was an average of three days (1-8 days). The nailing with single knee incision was performed in all cases. The mean operating time was 146 min (110-215 min). The operating time for femur was 70 min on average (35-120 min). Operative time for the tibia was 60 min (30-100 min). Open fractures treated with recommended antibiotics. No vascular or muscular action was necessary. The treatment of lesions has been carried out by multidisciplinary teams and intensive care was needed in one case.

The measurement of cell volume lost was difficult, but operative bleeding seems less than other surgical techniques (no cases of transfusion requirements have been reported). No septic or thrombotic complications have been found. There were no deaths in our series. The average hospital stay was 7 days with extremes of 4 and 21 days.

The average follow-up was 19 months (range: 4-40 months). The clinical results were evaluated with the score Karlström and Olerud[10] [Table 1]. It was excellent for two, good for four, medium for two, and bad for one (related to nonunion). Two patients showed a flexion deficit of the knee but still greater than 90°, but none had an extension deficit. We also noted a case of intermittent knee pain.

No rotational disorder has been reported. No anteroposterior instability of the knee or meniscal tear was diagnosed.

A favorable evolution with consolidation was noted in eight cases with 93 days as average time.

Aseptic nonunion of the femur occurred in one case [Figure 3], which was treated by decortication and graft.

Figure 3

(a) In the immediate postoperative period (b) Aseptic nonunion of the femur after 8 months

The radiological evaluation of the nonunion showed axial deviations distributed as follows:

The femur: Two varus (maximum 10°), one valgus (6°), a flexum (8°), and no recurvatum;

The tibia: One varus (5°), no valgus, flexum none recurvatum.

No patient presented clinical repercussions requiring osteotomy. No difference in length of the lower limbs was noted.

DISCUSSION

The relative scarcity of floating knee found in the literature[2111213] should not obscure the severity of these injuries in the context of polytrauma.

In general terms, the floating knee most often occurs in polytrauma patients requiring multidisciplinary care. In our series, three patients were polytrauma. Schiedts et al.,[14] reported a 100% polytrauma rate. Mortality on arrival is reported with a rate of 5.6%[15] to 8.6%.[16] The skin wound is a common complication, 69% had at an open fractures.[2471015161718192021] Neurological involvement is reported in about 10% of cases and vascular in 6.4% of cases.[2415212223] The association of meniscal-ligamentous injury to a floating knee is a concept gained, though in our series no meniscal and none ligament injuries were found. McAndrew and Pontarelli[24] reported the lowest rate (7%). In most studies,[41314202125] the diagnosis of ligament damage is done at the stage of laxity. We believe that the search for knee ligament injuries was the rule after internal fixation of both fractures. Extraarticular type I floating knees are much more common than type II in all nonexclusive series.[241126] Note that our series focuses on the floating knee type I (100%).

Due to the scarcity of floating knees and their variability, the study of literature does not provide therapeutic guidelines especially for type II.[27] However, most authors recommend surgical treatment for both type I and for type II;[111718232728] and in the most recent series, the treatment of floating knee type I made the maximum use double nailing[171823293031] with two methods: Single versus double incision nailing technique. Comparing these two techniques, double nailing with single incision can make only one installation on ordinary radiolucent table with a significant time savings in both operative skin-to-skin time and the overall time including intervention and installation.[2331] This interest of single incision has been pointed out by Ríos et al.,[31] for which the functional outcome is better. The criticism of this technique is mainly focused on the ligament problem.[233233] Indeed, it seems difficult to make a repair center pivot or ligament with nails in place,[23] but we believe that ligament injuries are rare in type I floating knee, they are mostly confined in types II. Also, Gregory et al.,[17] has not found any case in the series, and so is in our study. In addition, all secondary intraarticular gestures, according Piétu et al.,[23] have been made only for the type II floating knee.

Functional results after ipsilateral fracture of the femur and tibia are difficult to assess given the diversity of evaluation criteria. In the series using criteria Karlström and Olerud, the rate of satisfactory results varies from 28%[4] to 83%.[21] In our series, the rate of satisfactory results is about 90%. The literature review showed that the functional level, age,[19] vascular involvement, joint or not floating knee,[34] opening fractures, and their complexity and their seat (distal femur)[35] appear to predominate as well as the involvement of the central pivot. The ISS does not appear to influence the functional result[23] and the detrimental role of smoking could not be assessed.[19] As a result, the floating knee type I has a better outcome that type II.[2334] And according to our study, we can also deduce that the floating knee type I treated by nailing with single incision become better than those treated by t other osteosynthesis resources, because we found less intraoperative complications (less bleeding, less need for transfusion, less fat embolism) and even less postoperative complication (less risk of infection and less hospital stay), although functional outcomes, mobility, and patella syndrome are comparable.[23] This interest has been pointed out by Ríos et al.,[31] for which the functional outcome is better if single incision nailing technique is used.

The nonunion is a relatively rare complication in our series with a femoral nonunion in one case. Although with nailing the nonunion rate has decreased, it varies in the series of 4%-11% for the femur and 3%-30% for the tibia.[23] The factors included in the consolidation are age, sex, type of floating knee, seat, comminution, and open fractures. Malunions are relatively common and underline the difficulty to give a correct axis in case of floating knee. Karlström and Olerud[10] and McAndrew and Pontarelli[24] reported this complication in respectively 3% and 17.8% of cases. In our series, malunion was noted in three cases, neither is symptomatic. There was no significant difference in the incidence of nonunion or malunion between anterograde and retrograde nailing series.

CONCLUSION

Currently, double nailing is recommended in floating knee type I specially with single incision technique because it is more preferable: We used a single approach, a single installation, less bleeding, less risk of systemic complications (fat embolism), less operative time, less hospital stay, less risk of infection, but with a restriction due to the possible associated damage of central pivot. For satisfactory results, it is recommended to select patients (floating knee type I).