INTRODUCTION
Refracture of long bones previously stabilised with an intramedullary nail (IMN) following a second high-velocity trauma is rare, although there have been reports of such fractures involving femoral diaphysis with an in situ IMN.1 3 Stress fractures occurring at the proximal tip of a supracondylar IMN are well-reported.4 Leung et al.5 reported intraoperative breakage of the lateral cortex during insertion, and postoperative fractures in the femoral shaft after gamma nailing. They attributed this to impingement of the nail tip on the smaller diameter of the femoral shaft of Chinese patients. Very high incidence of stress fractures at the distal tip of a gamma nail has also been reported in a European population.6 So far, there has been no report of fractures occurring at the distal IMN tip of the femur. The presence of an in situ IMN may significantly alter the impact of trauma on a long bone, and produces a fracture pattern that may be different from a normal bone.
CASE SERIES
Five men (age range, 30-45 years) were injured in motor vehicle accidents and presented to the Post Graduate Institute of Medical Education and Research in Chandigarh, India between June 1999 and December 2001. They each sustained a second high-velocity trauma and refractured the femur previously stabilised with an IMN. In the first injury, the patients had sustained transverse fractures of the diaphyseal femur between the middle and distal third, and had been implanted with an intramedullary Kuntscher nail (n=4) or an interlocking nail (n=1) [Table].
The patients were reinjured in a second motor vehicle accident 6 to 24 months after the first accident. At the time of second injury, patients 1, 2, 3, and 4 had good callus formation and were ambulatory, while patient 5 had delayed union and was walking with stick support. Radiography revealed that all fractures involved the femoral condyle colliding with the tip of the IMN without proximal extension. The IMN was bent at the previous diaphyseal fracture site in patients 1 and 5, while patient 1 had associated fractures in the ipsilateral femoral neck, the contralateral femoral shaft, and the lateral condyle.
All patients underwent surgical treatment: patients 1, 2, and 4 had closed fractures and immediately underwent open reduction and internal fixation (ORIF) after IMN removal. Patient 3, with grade-3 open fracture, underwent thorough debridement and nail removal, followed by temporarily fixation of the articular component using Kirschner wires, and limb stabilisation using a transarticular fixator. The external fixator was removed and ORIF was performed 3 weeks later as the wound healed. Patient 5, with grade-2 open injury, underwent thorough debridement, nail removal, and split-skin grafting, and was put on skeletal traction. ORIF was performed 3 days later (Table).
A lateral approach was used in all patients. In patients 2 and 3, who did not have bent nails, the previously implanted Kuntscher nails were removed through the distal fracture sites. In patients 1 and 5, bent nails were extracted from the distal fracture site after having been straightened to a reasonable degree by applying manual corrective force on the thigh. Patient 4, with an interlocking nail, required removal from a separate incision over the greater trochanter after removal of the interlocking bolts.
Reconstruction of the femoral condyles was difficult in 4 patients due to marked comminution. The comminution was visible on radiographs in patients 3 and 4, while it became evident intraoperatively in patients 1 and 5 who had bent IMNs. All condyles were reconstructed using interfragmentary cancellous lag screws and Kirschner wires (Figs. 1-5). The use of fixed-angle devices was preferred to further stabilise the fractures after restoration of the articular congruity (Figs. 1, 4, and 5). Nonetheless, an angled blade plate was used in patients 2 and 3 as this made the insertion of the blade plate into the reconstructed femoral condyle easier (Figs. 2 and 3). A dynamic condylar screw with a long side plate was used in patients 1 and 5 because their proximal refracture sites also required stabilisation (Figs 1 and 5). A Tbuttress plate was used in patient 4 because the fracture was very distal and there was not enough bone to accept a fixed-angle device (Fig. 4).
Postoperatively, the limbs were immobilised in a groin-to-toe posterior plaster of Paris slab. The slab was removed and knee mobilisation was initiated at 3 weeks. Non-weight-bearing crutch walking was started at 6 weeks, and full weight-bearing was allowed after 12 to 18 weeks. Patient 2 was lost to follow-up, while all other patients were followed up clinically and radiologically for at least 36 months (Table).
In patients 3 and 4, bony union was evident at the distal femoral fracture site by postoperative 4 to 6 months. In patients with associated diaphyseal refractures, bony union was evident at both levels in patient 1 at postoperative 5 months. In patient 5, although sufficient callus formation was seen at the previous fracture site, which initially was a delayed union; there was no evidence of union at the supracondylar level at postoperative 6 months. There was r orption of bone ends, and the gap gradually increased leading to implant failure at postoperative 9 months. The patient underwent a further operation to freshen, realign, and stabilise the fracture ends with a condylar buttress plate, and bone grafting was performed. This resulted in bony union with minimal malalignment at postoperative 13 months (Fig. 5).
Postoperative rehabilitation did not significantly improve range of movement of all patients at postoperative 6 months. Manipulation was thus performed under general anaesthesia in patient 1, whereas arthrolysis and quadricepsplasty following hardware removal from the femoral condyle were performed on patients 3, 4, and 5. Subsequent physiotherapy resulted in the gradual improvement of knee motion. At 36-month follow-up, all patients had more than 100 degrees of knee range of movement (Table) and were rated as having excellent results using Judet's criteria.7
DISCUSSION
Interlocking nailing has become the gold standard for the management of femoral shaft fractures. To our knowledge, there is no report of patients sustaining distal femoral fracture at the in situ IMN tip in a second high-velocity trauma. The nail tip in a long bone acts as a stress riser, potentially concentrating the force of an impact in that region, as in 4 of our cases the second injury resulted in comminution of femoral condyles at the IMN tip. This comminution was clearly visible in radiographs of patients 3 and 4 whose IMNs were not bent. Comminution was seen intra-operatively in patients 1 and 5 who had bent nails. When the nail does not bend on impact, energy gets concentrated around the nail tip resulting in severe comminution; when the nail bends on impact, dissipation of energy may result in less comminution not visible on radiographs. The bending of the nail may be an important factor influencing the severity of comminution, apart from the velocity of the trauma.
Several case reports have described diaphyseal refractures with bent IMNs in situ following a secondary trauma1,2,8; however, none has discussed the correlation between the healing status of the previous fracture and the amount of energy required to cause a refracture and bending of an IMN. Much more energy is required to cause a refracture and bending of an IMN in completely healed fractures than incompletely healed ones. Therefore, the impact on patient 5, with delayed union of the diaphyseal fracture, may be weaker than that on patient 1, who had good callus formation. This explains why patient 1 had associated fractures of the ipsilateral femoral neck, contralateral femoral shaft, and lateral condyle.
The first step of the management is to remove the IMN. Extraction of the nail was easier in patients 2 and 3 with straight nails as the nail tip was accessible through the distal femoral fracture. In patients 1 and 5 with bent Kuntscher nails, the nails were first straightened to facilitate extraction. The interlocking nail in patient 4 had to be removed proximally because of its construct. Removing a bent interlocking nail is difficult. Various methods have been described in the literature including in situ straightening through external force on the femur9 or sectioning of the nail and removing each piece separately.10 The bent nail can also be sectioned to half of its diameter and then straightened.3,11
Due to marked comminution, multiple screws and Kirschner wires were used in all patients for interfragmentary reconstruction of femoral condyles before placing a fixation device. Johnson12 believes that the unique design of the 95°-angled blade plate, combined with countersunk subchondral Kirschner wires and cancellous lag screws, provides excellent fixation of the distal femoral articular surface in comminuted intra-articular fractures, whereas the dynamic condylar screw is considered less effective in extensive comminution of the medial femoral condyle. Angled blade plates were used in patients 2 and 3 as this made the insertion of the blade plate into the reconstructed femoral condyle easier. Dynamic condylar screws with long side plates were used in patients 1 and 5. The separate assembly of the side plate and the dynamic condylar screw allows the side plate to slide beneath the muscles without splitting them; thus preserving the vascularity of the middle fragment. A T-buttress plate was used in patient 4 because the supracondylar fracture was very close to the joint surface and there was not enough bone to accept a fixed-angle device. The patient had slight varus malposition in fixations.
The course to union was uneventful in patients 1, 3, and 4, whereas patient 5 had nonunion and patient 2 was lost to follow-up. Patient 5 had a grade-2, open fracture on the medial femoral condyle. The wound was debrided and covered with a split skin graft before surgery. However, the grafted skin on the medial side restricted surgery to the lateral aspect of the distal femur. This may have caused inadequate compression on the medial side and led to implant failure at 9 months. Refixation with adequate compression at the fracture site and bone grafting eventually led to bony union.
Retrograde intramedullary supracondylar nails have also been used for treatment of distal femoral fractures. Leggon and Feldmann13 concluded that incidence of varus or valgus malunion was less with the use of supracondylar nails because they were more reliable in controlling distal shaft fractures (although rotational malunion was still a problem). However, the use of retrograde femoral nailing for treatment of supracondylar femoral nonunions was disappointing.
Knee stiffness was present in all patients at early follow-up. This could partly be due to the previous open intramedullary nailing that jeopardised both endosteal and periosteal vascularity. Lateral plate fixation may have further aggravated the situation. Particularly in patients 3 to 5, who had AO type-C3 fractures with short distal fragments, had knee stiffness requiring secondary procedures at the knee joint. Therefore, a less invasive stabilisation system without autogenous bone grafting has become popular and has been reported to have a high union rate and a low incidence of infection.14 Mira et al.15 reported that only 17% of patients with diaphyseal femur fractures had normal quadriceps function at long-term follow-up. All of our patients had their previous fractures treated at other rural hospitals where open intramedullary nailing, though outdated, was still practised due to a lack of proper imaging and infrastructure. Knee mobilisation was delayed for fear of loss of fixation as the patients had severe comminution in the second injury. A combination of extra-articular muscle contracture caused by previous open intramedullary nailing, comminution, intraarticular hardware, and late knee mobilisation leading to joint adhesions and capsular scarring attributed to knee stiffness in our patients.
To increase knee motion, patient 1 underwent manipulation under general anaesthesia, whereas patients 3, 4, and 5 underwent hardware removal, arthrolysis, and quadricepsplasty.16-17 Eventually at 36-month follow-up, all patients had acceptable range of movement of the knee. Satisfactory outcome was reported in 75% to 85% of patients with distal femur fractures treated by ORIF with either 95° condylar plate or dynamic condylar screw.13 The overall outcome of our patients was satisfactory. There was no infection or gross malalignment. Mild loss of range of movement of the knee was expected considering the severity of the injuries.
CONCLUSION
Refracture of the distal femur with an in situ IMN following high-velocity trauma is rare. The presence of an in situ IMN potentially concentrates the force of an impact and aggravates comminution. Nail removal may be difficult if the IMN is bent. Anatomic reconstruction of femoral condyles and stabilisation using an appropriate plate can provide a satisfactory outcome.
© 2005 Western Pacific Orthopaedic Association Provided by ProQuest LLC. All Rights Reserved.
Source: Journal of Orthopaedic Surgery
