SECONDARY INTERNAL FIXATION IN OPEN COMMUNITED FRACTURES OF FEMUR Is It The Correct Alternative?
Hetal A Chiniwala, Sanjay B Dhar
Clinical and Research Fellow, Department of Orthopaedics, Gyeong-Sang National University Hospital, Chinju, South Korea.
Objectives : The purpose of this study was to evaluate the efficacy of external fixator as an interim mode of stabilization, converted to internal fixation and compare it to the role of external fixator as a definitive mode of stabilization, in the treatment of open comminuted fractures of femur.
Material and Methods : It is the retrospective analysis of 37 open comminuted fractures. The patients were treated with either ring fixator; dynamic axial fixator or the combination of the two, according to the type of fracture, general condition of patient and need for secondary soft tissue procedures. The debridement, impregnation of antibiotic mixed cement beads done primarily and periodically. The secondary procedures like internal bone transport, vascularized fibula graft, internal fixation was carried out.
Results : The mean time of union, total duration of the fixator and rates of complications were evaluated. The mean time for union of fracture was shorter in the patients with open comminuted fractures treated with definitive external fixation compared to those treated by primary external fixator and converted later to internal fixator in comminuted fractures. There were fewer incidences of the knee stiffness and infection in the patients treated with definitive external fixator.
Conclusion : The external fixator can be used as a definitive mode of stabilization in patients with open, comminuted fractures. It often facilitates, the often necessary secondary reconstructive procedures like bone transport and vascularized fibula graft.
External fixation is used to treat patients with open femoral fractures with or without large bone defect for an interim stabilization or definite treatment.  According to several studies, primary internal fixation or use of external fixator for interim stabilization and its conversion to a definite internal fixation provides a better outcome, compared with use of external fixation as the definite mode of fixation. [2,11-13] However, when treating patients with open fractures with comminution and large bone defect, internal fixation is difficult and time consuming. The external fixation is relatively atraumatic and the periosteal circulation is not disturbed, unlike with the use of most internal fixation devices.  External fixation is an useful treatment for complex fractures with bone defect, because it has the advantage of making adjunctive reconstructive procedures (e.g. cancellous bone grafting, vascularized bone grafting, and internal bone transport) very easy.
External fixation has complications like delayed union, pin-tract infection, and loss of knee motion. [4,12] However, little has been studied regarding the efficacy of external fixation in achieving bone union. The purpose of this study was to evaluate the efficiency of external fixator when used as a definite mode of fixation and to compare it to its use as an interim fixation to be replaced by internal fixation in open comminuted fractures of femur.
MATERIAL AND METHODS
Thirty-four patients with 37 open comminuted fractures of the femur were treated with external fixator. All the fractures were classified according to the Winquist classification of comminution.  According to the classification, 3 patients were type I, 10 patients were type II, 9 patients were type III and 15 fractures were type IV. Also, 37 open fractures in 34 patients were classified according to Gustilo and Anderson classification for open fractures (Table 1). In this study, associated injuries were seen in 22 patients with fractures, head injury in 9 patients, chest injury in 3 patients, ipsilateral tibia fracture in 10 patients, and pelvis fracture in 13 patients. There were 26 men and 8 women, (average age, 32 years). The two types of external fixators used in this study were Ilizarov fixator (Smith-Nephew, Memphis, TN, USA) and monolateral Dynafixator (Hyupjin, Seoul, Korea). The Ilizarov fixator was used in 22 fractures; monolateral fixator was used in 12 patients, and Hybrid assembly that combined the Ilizarov and monolateral fixators in 3 patients.
TABLE 1 Classification of fractures according to Gustilo, Anderson classification and distribution of fracture for definitive external fixator and secondary conversion to internal fixation Definitive external fixation Secondary internal fixation Open fractures
Grade II 11 9 Grade III 10 1 Total 26 11
In the Ilizarov frame, an arch was used at the proximal third of the femur and full rings were used at the middle third and distal third of the femur. In the proximal segment of femur, the half-pins were used for fixation. The monolateral fixator was used for the fractures of the femoral diaphysis. The hybrid assembly was used for middle and distal third fractures. It included the 2 full rings placed in the distal fragment, usually in the distal third of the femur and monolateral fixator placed in the proximal fragment. The latter was connected to the proximal ring of the 2 full ring assembly by hybrid clamps. The soft tissues were thoroughly debrided and the necrotic bone was excised in all patients. Antibiotic mixed cement beads were inserted, whenever wound contamination was significant.
Cancellous bone grafting was required in 24 fractures.
Corticotomy with internal bone transport was performed in 5 fractures. In one patient, arthrodesis was performed after double corticotomy, one at proximal tibia and other at proximal femur followed by internal bone transport in view of the severely comminuted intra-articular fracture with bone loss (Figs. 1a,b,c). Acute shortening of bone to close the bone defects and lengthening of bone at the distant corticotomy site was performed in two patients. Vascularized fibula graft for reconstruction of the defects was used in 1 patient (Figs. 2a,b,c). The bone gap was 7 cm in patient treated with vascularized fibula graft. The conversion to definitive internal fixation was performed in 11 of 37 fractures (Table 1). The intramedullary nail with interlocking screws was used in 9 patients and 2 patients were treated with dynamic condylar screw and plate. The patients were evaluated regularly for assessment of union and joint function. The active, assisted active and passive range-of-motion exercises were used in rehabilitation for knee function. Isometric and isotonic muscle strengthening exercises were performed. The gradual weight bearing was begun once there was evidence of union. The union was defined as radiological bony continuity in both anteroposterior and lateral radiographs with no pain or mobility at the fracture site on weight bearing without fixator.
The average follow up period was 2.3 years (range, 2-3.6 years). The mean duration of external fixator was 23.6 weeks for the patients with definitive external fixation and 13.2 weeks in patients receiving interim treatment with external fixation.
Fig 1a Fig 1b Fig 1c Preoperative radiographs show severely comminuted(type IV) grade IIIa open fracture of distal third with bone loss. Long film shows trifocal transport and arthrodesis of knee. Final radiograph shows healed corticotomy sites and knee fusion.
The average time interval between removal of the external fixator and execution of internal fixation was 9 days (range, 7-19 days). The time interval varied depending upon the condition of pin-tracts and of the wound after the removal of the fixator. The average fracture union time was 23.6 weeks in definitive external fixation and 29.2 weeks in interim fixator with internal fixation.
Knee stiffness was the most common complication seen in the patients at the final follow up. It was seen in 7 patients. These patients had a free range of motion of less than 60o.
Quadricepsplasty was performed in 2 patients, whereas Brisement force alone was used in 3 patients to improve the knee range of movement. It was noted that rate of this complication was more in patients with secondary internal fixation (4 fractures - 36%) than in patients with definitive external fixator (2 fractures - 11%).
Pin-tract infection was seen in 20% patients. However, it was not severe enough to require removal of the pin or to cause osteomyelitis, or to alter the plan of management. Angulation of more than 10o were seen in 3 patients. Of these 3 patients, anterior or posterior angulation was seen in 1 patient and varus angulation was seen in 2 patients.
Noticeable clinical deformity was however present in only one patient after vascularized fibula graft. Two out of these 6 patients belong to type IV of Winquist classification.
Infection was seen in one patient treated with secondary internal fixation. One patient, who was treated with secondary closed interlocked intramedullary nail, required removal of nail, antibiotic mixed cement bead insertion. The bone graftingwas done later and union was obtained. The residual shortening of more than 2 cm were seen in 3 patients (maximum shortening, 3.5 cm).
Fig 2a Fig 2b Fig 2c Radiograph shows a Grade IIIa comminuted middle and lower third fracture (type IV) immobilized with an Ilizarov fixator. After persistent discharge from the wound, fragments were removed and dead space packed with antibiotic-mixed cement beads. Radiograph shows healed fracture after vascularized fibula graft
Primary intramedullary nailing has become very popular for femoral fractures including open grade II and III fractures since the last decade. [2,11] Primary intramedullary nailing is reported to have high union and low complication rates. However, this is suitable in fractures at the middle third of femur and grade I or II open fractures. Immediate internal fixation is only relatively indicated for grade III femoral fractures and should be applied with caution.  Reproducing the good results consistently in complex fractures with comminution involving a large segment and bone defect, using intramedullary nailing, is very difficult. The use of the external fixator in these patients reduces their time in the hospital and facilitates their postoperative rehabilitation by allowing rapid healing of the fracture. 
In terms of systemic (especially pulmonary) results, the patients with pulmonary injury may suffer additional pulmonary decompensation as the result of reamed and unreamed nailing.  An immediate stabilization with an external fixator may be beneficial in these patients until pulmonary status is improved.  The primary internal fixation is usually delayed till the patientís general condition and the condition of the wound permits such procedure. [2,12] However, the delay in stabilization can prove hazardous in patients with associated multi system injury.  In such patients, early and quick stabilization is important, not only for the better outcome of the fracture but also for the avoidance of pulmonary complications and better rehabilitation of the associated injury. 
External fixation in such cases of multiple injuries offers a quick method of stabilization, and it provides versatility in further management of the wound and the fracture.
External fixation is recommended for the use as a temporary mode of stabilization for open femoral fractures until the damaged soft tissues heal, either spontaneously or with a soft tissue procedure to allow secondary internal fixation. [1,12,13] A brief period of external fixation and long fixator free period prior to internal fixation are recommended to avoid subsequent bone infection.  Time of conversion to internal fixation depends upon the improvement in wound condition and the general condition of the patient. In our study, the average time of external fixation was 13.2 weeks in patients who were treated with secondary internal fixation. It was more in patients with grade III fractures, because subsequent soft-tissue procedures were necessary for closure of the large wounds and this increased the duration of fixator. However, it was considerably lesser in patients with grade I fractures (Table 3).
Most of the studies recommend a short external fixator period to be replaced by internal fixation. They do so to prevent the complications like knee stiffness, pin-tract infection associated with a long fixator period. However, hardly any studies have been made to compare the efficacy of the different modes of internal and external fixation in achieving the bony union.
Van den Bossche et al. reported mean union time of 40.6 weeks in patients treated with interim external fixation and converted to internal fixation.  This is considerably long time compared to the union time seen in the current study. In the current study, we noticed a longer average union time in fractures converted to secondary internal fixation after initially stabilizing them with the external fixator. This was true in grade II open fractures, which have apparently small and clean looking skin wounds, but marked intra-compartmental muscle devitalization particularly when associated with comminution. The failure to extend this benign-looking wounds for debridement causes conditions that promote bacterial growth. Also, there is temptation to conserve the loose fragments of bone to avoid creation of large void in view of planned subsequent conversion to internal fixation. This leads to delay in soft tissue healing and in many patients it leads to low-grade infection, thus causing a long delay in the union of fracture and increasing incidence of infection. Therefore, careful examination of the soft tissues and liberal extension of the wounds with radical excision of the devitalized fragments at the initial debridement is of the utmost importance, irrespective of the mode of definitive stabilization.
The conversion to secondary internal fixation in the comminuted and open fractures disturbs the revascularization process of small fragments that has begun after the primary stabilization. This leads to delay in union despite the apparently good stability it can provide.
The use of intramedullary nails, particularly those used after preliminary reaming of bone marrow canal, is accompanied by injury to marrow tissues, the endosteum, and the nutrient vessels. This damage partly or completely suppresses endosteal bone formation.  In osteosynthesis with plates, the blood supply to the bone is damaged by periosteal elevation, drilling, tapping and inserting screw.  The external fixator is very effective in achieving the bony union.  Few studies have reported very rapid and high union rate with external fixator. [6,7] In the comminuted open fractures there are problems like increased soft tissue loss, loss of bone and decreased vascularity of tissues. The filling of these huge gaps may require specialized procedures, like vascularized fibula graft or internal bone transport or acute shortening at the fracture site, followed by lengthening at distant corticotomy site.
The long-standing treatment with external fixator is reported to have the risks, such as stiffness of the knee joint, mal-union, and pin-tract infection.  In current study, 36% of the patients who had secondary internal fixation experienced knee stiffness, whereas 11% of patients who had definitive fixator experienced knee stiffness. The increase in number of operations that require excessive soft tissue handling, as with internal fixation, increases the chance of fibrosis and adhesion of muscles, resulting in joint contracture. In this current study, the longer average duration of fixator time in patients with definite external fixation did not result in increased stiffness of the knee. However, we noticed that the incidence of stiffness of knee was higher in patients in whom ring fixator was used than in patients in whom monolateral fixator or hybrid assembly was used. This may be because the wires transfixed the quadriceps. This complication can be avoided by using half pins instead of wires, whenever possible. The incidence of pin-tract infection was 25% in this current study. However, no infection was serious enough to have resulted in removal of pin or change in the plan of the treatment. Such fixator-related complications can be avoided if careful attention is paid to the choice of fixator, regular care of pin-tract, providing timely treatment of early pin-tract infection, promoting regular physiotherapy, without any compromise in the results.
The external fixator is very useful for stabilization, and it can be used as definitive mode of stabilization in patients with comminuted open fractures. The conversion to secondary internal fixation in such instances may lead to delay in union of fracture and increase the risk of infection and knee stiffness.
External fixator provides a simple and quick means of treating these injuries; also they are very versatile in these morbid injuries requiring periodic readjustments and debridement.
The external fixator also facilitates subsequent reconstructive procedures, in view of large bone defects.