Flexible intramedullary nailing for distal femoral fractures in patients with myopathies

Abstract

Purpose

Distal femoral fractures are quite common in nonambulating patients with myopathies, as they present marked osteoporosis. The deterioration of preexisting knee flexion contracture is a known problem, as these fractures are usually angulated posteriorly. The goals of treatment are to reduce immobilization and bed rest to a minimum, prevent function loss, and prevent refracture. The aim of our work was to investigate if these goals can be achieved by an operative treatment with closed reduction and flexible intramedullary nailing (FIN).

Methods

Six distal femoral fractures in four nonambulating patients with myopathies (three Duchenne muscular dystrophy and one nemaline myopathy) were treated with FIN between 2005 and 2011. Patient charts and radiographs were reviewed to determine if intra- or postoperative complications occurred and to detect the interval to wheelchair mobilization and hospital discharge. Pre- and postoperative knee flexion contracture was noted from the patient charts of our reeducation unit, where patients were already known preoperatively.

Results

Wheelchair mobilization without further immobilization after an interval of 2–3 days was possible. No aggravation of knee flexion contracture was detected in our patient series. No complications associated to the operative treatment itself and no refractures in the follow up occurred.

Conclusion

Our experience showed that FIN is a low invasive and sufficiently stable osteosynthesis in such fractures. Left in place, nails will reinforce mechanical stability.

Introduction

Femoral fractures are a rather common problem in nonwalking patients with myopathies such as Duchenne muscular dystrophy (DMD). These are most often located in the supracondylar region and occur regularly after a fall from a wheelchair [1, 2]. Due to the trauma mechanism and the usually already preexisting slight flexion contracture of the knee, the distal fragment is usually displaced in flexion. Gross displacement is rarely found [2, 3].

The treatment of these fractures is a true challenge for the physician. Fortunately, these patients often do not present with pronounced pain, as their weak muscles cannot contract as in healthy subjects. The goals of treatment are to reduce immobilization and especially bed rest to a minimum in order to avoid respiratory complications and to preserve maximal function possible after fracture healing. Lesions in nonambulating patients are often low-energy fractures and refractures do occur occasionally. Only a few reports deal with the management of femoral fractures in patients with DMD; not surprisingly, they advocate mainly nonoperative treatment [2, 4]. However, we are also familiar with similar cases where wheelchair mobilization was difficult after nonoperative treatment and at least one case where these problems resulted in decubital ulcers and, finally, the passing of the patient. Such cases are not usually published. In order to allow postoperative treatment without plasters or splints, we began stabilizing these fractures with flexible intramedullary nailing (FIN). In addition, we hypothesized that operative treatment would provide other advantages: not removing the nails should prevent refracture and a correct reduction or even over-reduction of the distal fragment in extension should avoid increasing knee flexion contracture. The purpose of this work was to ascertain if FIN is a reliable technique for osteosynthesis in those fractures and to evaluate if the goals to mobilize these patients rapidly without plasters or splints and to avoid increase in knee flexion contracture and refracture can be achieved.

We present our experience with FIN of six femoral fractures in nonambulating patients with myopathies.

Materials and methods

Between 2005 and 2011, we treated four boys (three DMD and one nemaline myopathy) with six distal femoral fractures (two bilateral) with FIN. The mean age of the patients was 12.6 years (range 7.9–17.0 years) and the mean body weight was 39.7 kg (range 23–63 kg). All four patients were nonambulating at the time of the fracture. Previous medical history revealed that two of the four patients had already undergone spinal instrumentation and three patients had had one or more surgical interventions for soft tissue release due to joint deformation. The medical records were reviewed retrospectively to detect if eventual intra- or postoperative complications occurred and to note the postoperative interval until wheelchair mobilization and hospital discharge. In addition, the mechanism of trauma and delay to surgery after hospital admission were noted. Radiographs were inspected to ascertain the direction and amount of initial dislocation, as well as to detect reduction and bone healing. All patients were already regularly followed by the rehabilitation unit in our hospital and, therefore flexion, contracture of the knee was documented in all patients during the last 6 months before the accident and also no longer than 6 months after bone healing. Clinical follow up of these patients ranged from 6 months to 6 years and radiological follow up ranged from 6 weeks to 6 years. The study was conducted according to the recommendation of the national ethic committee in charge of clinical research in humans and to the Declaration of Helsinki of 1975, revised in 2000.

Surgical technique

All surgeries were realized under general anesthesia in supine position. No traction table was used. In 5 of 6 fractures, FIN was realized in a descending manner. The location of the incision just above the level of the greater trochanter was confirmed with fluoroscopy, as the greater trochanter in these patients is difficult to palpate due to the tissue consistency and the coxa valga. Perforation of the cancellous bone is carried out with a bone awl at the anterior and inferior part of the prominent part of the greater trochanter. We used flexible nails made of titanium, which are already pre-bent at the tip and were only slightly bent in the more proximal part. The nail diameter was chosen according to the rule of 40 % of the medullary cavity diameter [5]. It is advisable to push the nail through the metaphyseal area under the control of an image intensifier, as the nail can easily emerge through the osteoporotic bone. The first nail is pushed to the fracture site and then a second nail is inserted in the medullary canal through another hole slightly more proximal and turned 180° as it reaches the fracture site. The knee is then extended and if the fracture is only angulated (usually in flexion) without lateral displacement, the distal fragment will extend with the knee and the anterior cortical bone of the proximal fragment will impact in the distal fragment. Any distraction of the fracture site should be avoided in those cases, as it is not possible to maintain additional length with FIN. The two nails should then be pushed across the fracture site and each directed towards one condyle until they cross the physis. After control with the image intensifier, nails are cut as short as possible and completely impacted in the bone if possible in order not to cause any soft tissue irritation (Fig. 1).

Fig. 1.

Typical posterior angulation (top left) of a distal femoral fracture and after reduction in slight extension and flexible intramedullary nailing (FIN)

In the one patient with a completely displaced fracture, closed reduction was not possible. After open reduction, an ascending FIN was carried out with the entry points each slightly distal to the medial and lateral epicondyle. The nails were directed towards the femoral head and the greater trochanter in order to completely stabilize the bone.

Results

The fracture mechanism and location are noted in Table 1. All but one fracture showed only angulation but no gross displacement and, of those five fractures, only one was displaced in extension, with the remainder angulated in flexion to various degrees. All patients were operated not later than 1 day after hospital admission in order to minimize immobilization time, whereas patient 2 was not seen until 5 days after fracture.

Table 1.

Patients and knee mobility before fracture and after fracture consolidation

Case	Age (years)	Mechanism	Location	Diameter of nails, direction	Delay to wheelchair mobilization (days)	KFCa preop.	KFCa postop.	Hospital stay (days)	Complications
1	12.1	Traffic accident	Supracondylar bilateral	3.5 mm (right side), 4.0 mm (left side) descending	3	R 40° L 35°	R 40° L 35°	11	None
2	17.0	Fall from toilet seat/commode	Distal femur displaced	3.5 mm ascending, open reduction necessary	2	50°	50°	5	None
3	7.9	Fall from wheelchair	Supracondylar	2.5 mm descending	2	0°	0°	5	None
4	13.5	Fall from wheelchair in a transporter	Supracondylar bilateral	4.0 mm descending	11b	R 15° L 10°	R 0° L 0°	17	Pulmonary infection

^aKFC: knee flexion contracture before fracture and after fracture consolidation

^bMobilization in the wheelchair was possible on the first day after extubation was conducted

Three of four patients could be mobilized in their wheelchairs on the second or third days after the surgical intervention. One patient with a bilateral supracondylar fracture presented significant pulmonary fluid overload at admission to our institution. Surgery was performed as soon as the medical condition made general anesthesia possible, which was the case 24 h after admission. Extubation was conducted shortly after the intervention. Respiratory degradation occurred due to a complicating pulmonary infection which needed reintubation 2 days after surgery for a duration of 1 week. After that, mobilization in the wheelchair was immediately possible and hospital discharge was conducted after 4 days. The duration of hospitalization ranged between 5 and 17 days.

Radiographic evaluation showed that the goal to place the distal fragment in extension was achieved in all cases. Radiographic follow up showed that all fractures healed without evidence of secondary displacement or significant varus or valgus malalignment.

Clinical follow up showed that, after fracture healing—but no more than 6 months after surgery—knee flexion deficit completely resolved in one patient with a bilateral fracture who had only 10°–15° deficit bilaterally before his fractures. Knee extension remained complete in one patient who did not present knee flexion contracture. In two patients who did not stand before they sustained the fracture, knee flexion contracture was between 35° and 50° preoperatively and did not alter postoperatively.

Discussion

The increased risk for and prevalence of fractures in patients with myopathies are well investigated [3, 4, 6–8] and will likely further increase, as glucocorticosteroid treatment is the standard of care [9]. Calcium and vitamin D or alendronate administration are investigated treatments to improve bone mineral density and, eventually, reduce fracture risk [10, 11]. On the other hand, only a few reports exist focused on the fracture treatment in these patients, which advocate mainly nonoperative treatment. We present a small case series of nonambulating patients with myopathies who were treated operatively with FIN.

We are aware that, in the literature [1, 2], a favorable outcome after nonoperative treatment is reported. These patients do present considerable anesthetic risks because of the severe impairment of pulmonary and heart function. Therefore, indication for surgery should be considered carefully. Even though it is worthwhile not to delay surgery for a long time, it is very rarely an emergency and the decision to operate on these children should be made among a team involving not only the family, the surgeon, the anesthetist, and subspecialists like cardiologists or pneumologists, but also the physiotherapists who treat these patients regularly. As anesthesia even for extensive surgery such as spinal instrumentation is possible, anesthesia is arguable in most of these patients also for operative fracture treatment. However, this surgery should be executed by an experienced surgeon in order to keep it a short and low-invasive intervention.

We do believe that operative treatment does have advantages over nonoperative treatment at least in selected cases. Granata et al. [4] argued that, in wheelchair-bound patients, no worsening in functional ability occurred after nonoperative fracture treatment in their group, as it was already evaluated at a minimum. Hsu et al. [2] reported that, in a group of nonambulating patients with distal femoral fractures, they accepted a minimal amount of posterior displacement, which led to an increased knee flexion contracture. A more detailed description of the functional outcome or eventual difficulties is not found in those reports. Nevertheless, an increased knee- and hip-flexion contracture often makes transfers and also positioning more difficult or leads to an inability to stationary standing in those who do. Physiotherapists often work intensely to prevent the deterioration of knee flexion contracture and sometimes even elective soft-tissue releases are performed. Therefore, we think that, in those patients who still wish to execute stationary standing or in those where the preexisting flexion contracture already leads to some problems in positioning, avoiding increased flexion contracture or even improving it should be an important goal in the treatment of these fractures. A nonoperative treatment with reduction alone could solve this problem, but will require sedation or even general anesthesia in most cases. The fracture will also be less stable after such a manipulation. This could potentially cause more pain and difficulties during mobilization.

In addition, increased bone fragility is an issue and will persist after nonoperative fracture treatment, which is often a concern as fractures occur after low-energy trauma. FIN is currently the treatment of choice in pediatric femoral fractures in school-aged children [12, 13] and is a described method to stabilize bone fragility as, for example, in unicameral bone cysts [14]. The FIN technique is also a possible method to treat metaphyseal fractures of the upper extremity such as proximal humerus fractures, supracondylar fractures, and radial neck fractures, and provides sufficient stability to allow for immediate mobilization [5]. In our opinion, FIN is the most appropriate implant for such fractures not only because it is the least invasive, but plates and screws often do not provide sufficient stability and the bone is prone to refracture above or below the level of a plate. Rigid locked intramedullary nails have a high risk of false route in osteoporotic bone and are inapplicable in cases where a nonanatomic reduction is sought.

In conclusion, our report shows that FIN is a feasible, reliable, and low invasive method in these metaphyseal osteoporotic fractures. We think that operative treatment with FIN should be discussed in those patients who need general anesthesia for fracture reduction and should certainly be considered in those patients where mobilization in the wheelchair is difficult or impossible with splints or casts if general anesthesia is arguable.