Hip spica versus Rush pins for management of femoral diaphyseal fractures in children.

BACKGROUND: Femoral fractures are common in children between 2 and 12 years of age and 75% of the lesions affect the femoral shaft. Traction followed by a plaster cast is universally accepted as conservative treatment. We compared primary hip spica with closed reduction and fixation with retrogradely passed crossed Rush pins for diaphyseal femur fracture in children. The hypothesis was that Rush pin might provide better treatment with good clinical results in comparison with primary hip spica.
MATERIALS AND METHODS: Fifty children with femoral fractures were evaluated; 25 of them underwent conservative treatment using immediate hip spica (group A) and 25 were treated with crossed retrograde Rush pins (group B). The patients ages ranged from 3 to 13 years (mean of 9 years).
RESULTS: Mean duration of fracture union was 15 weeks in group A and 12 weeks in group B. Mean duration of weight bearing 14 weeks in group and 7 weeks in group B. Mean hospital stay was 4 days in group A and 8 days in group B. Mean followup period in group A was 16 months and group B was 17 months. Complications such as angulation, shortening, infection were compared.
CONCLUSIONS: Closed reduction and internal fixation with crossed Rush pins was superior in terms of early weight bearing and restoration of normal anatomy.

INTRODUCTION

Femoral shaft fractures are one of the most common fractures of lower extremity in children and the most commonly requiring hospitalization.123 Some degrees of angular deformity and some centimeters of shortening are acceptable in children according to age group because children have tremendous remodeling potential.123 Variety of methods are used for treatment of pediatric diaphyseal femur fractures including immediate spica casting, traction followed by spica casting, external fixators, osteosynthesis with plate, internal fixation with intramedullary rod or flexible intreamedullary nail.123 Choice of treatments depends upon age of children, anatomical site and fracture pattern. Traditionally, children below 6 years are treated with immediate hip spica and adolescent children are with operative methods.123

External fixators are associated with increased chances of pin tract infection and refracture. Plate osteosynthesis need extensive soft tissue stripping and resurgery for removal. Intramedullary rods increase chances of avascular necrosis of femoral head and damage to physis.12 Flexible intramedullary nailing has become an increasingly popular method of pediatric femoral fracture fixation.45 Systemic reviews and various cohort studies have shown excellent clinical results with flexible intramedullary nails (Rush pins) for children and few studies have extended its indication to preschool going children also.2345 We present a comparative study between intramedullary Rush pins and immediate spica casting for pediatric diaphyseal femur fracture.

MATERIALS AND METHODS

50 children (with age range 3-13 years) who presented between November 2010 and December 2012 with diaphyseal femur fracture were included in study. The informed consent was taken from parents. Twenty five were treated by hip spica cast (Group A) and twenty five by Rush pin allocated sequentially (Group B).

Inclusion criteria for selection of patients were diaphyseal femoral fracture of age group 3-13 years, with or without comminution, multiple fractures, fractures in patients with polytrauma. Undisplaced fractures treated by traction and hip spica, pathological fracture, open fracture, children with neuromuscular disorders, metabolic bone disorders, irritable patients with head injury, associated vascular injury needing repair were excluded.

Fracture pattern was classified according to AO classification type 32A1 [Figure 1a]. In group A fracture was reduced on the same or next day of presentation to hospital under fluoroscopy control one and half spica cast were applied under general anesthesia, traction after applying on fractured limb. Hip was flexed between 30° and 40°, while knee and ankle were kept in neutral position [Figure 1b]. X–ray was evaluated immediately after spica cast application [Figure 1c]. Criteria of acceptable reduction were based upon Kasser et al. [Table 1].6 Children were admitted to hospital until parents learned how to take care of spica. Followup was performed at 2nd weeks for evaluation of reduction and spica related complications [Figure 1d]. Radiological evaluation was performed at 6th weeks for evaluation of radiological union [Figure 1e]. If bridging callus was seen at three cortices, child was asked to bear weight with or without support according to pain tolerance [Figure 1f]. If callus was not evident long leg cast was applied for 4 more weeks.

Figure 1

(a) X-ray right thigh anteroposterior and lateral views showing femoral shaft fracture before spica cast application (b) Clinical photograph of same patient with hip spica case applied in 30°-40° of flexion at hip (c) X-rays anteroposterior and lateral views of same patient showing alignment in hip spica (d) Clinical photograph of same patient with hip spica showing broken spica at 2 weeks followup (e) X-ray anteroposterior and lateral views of same patient at 6 weeks followup showing alignment and callus formation (f) X-ray anteroposterior and lateral views at 4 months followup showing alignment of fragments and remodelling

Table 1

Criteria of acceptable reduction

In group B, under general anesthesia, two small skin incisions were made on either side of distal metaphysis and two holes are made obliquely facing toward medullary cavity with help of 4 mm awl, an inch proximal to growth plate. Two precontoured C-shaped Rush pins were passed retrogradely with fluoroscopy control until both tips reached just at distal fragment. Fracture was reduced closely with manual traction and Rush pins are pushed into medullary cavity of proximally diaphyseal fracture fragment under fluoroscopy control [Figures 2A (a-e) and 2B (a)]. Tips of the pins are targeted up to the level of neck and base of the greater trochanter. Care was taken that commercially made pre bent distal part of stainless steel Rush pin lied on cortical surface of the supracondylar region of the femur without soft tissue was impingement. Size of the Rush pins were measured as 40% of narrowest diameter of femur on anterioposterior (AP) and lateral view. Sizes of pins were selected below 2.5-3 mm. In initial 5 cases we applied posterior long leg plaster of Paris back slab. Thus we later discontinued and only knee immobilizer was applied postoperatively until sutures were removed on 2 weeks. As soon as pain was tolerable, hip and knee was mobilized and non weight bearing ambulation was allowed. Weight bearing was permitted once bridging callus was evident on X-ray on three cortices. Followup was carried out at 6th, 12th week, 6th months, 1 year and 2 years for radiological and clinical evaluation [Figure 2B (c and d)]. Rush pins were routinely removed after 1 year of surgery. Treatment cost was calculated as total amount paid to hospital which covered admission; investigation, operation and hospital stay charges.

Figure 2A

(a) Clinical photographs showing point of entry (b and c) Peroperative fluoroscopic view showing flexible intramedullary pins beingnegotiated (d) X-rays of thigh anteroposterior and later views showing femoral shaft fracture (e) X-rays of thigh anteroposterior and lateral views immediate postoperative x-rays showing flexible pins in situ

Figure 2B

(a) X-ray of thigh anteroposterior and lateral views at 14 months followup showing flexible nails in situ and union (b) Clinical photographs of same patient showing range of motion (c) X-ray of thigh anteroposterior and lateral views showing complete fracture healing at 24 months followup. Implant has been removed

Statistical analysis

Magnitude of difference between two groups was measured between means in both group by IBM SPSS (Kathmandu, Nepal) at 11.5 software for windows and significance of difference was measured by determining P value using Chi-square test for qualitative variables and for quantitative variable by independent t-test and Man Whitney U test depending upon whether P value obtained from Kolmogorov-Smirnov Z test for homogeneity of variance was below or above 0.05. P < 0.05 considered as statistically significant.

RESULTS

Age in both groups ranged from 3 to 13 years with mean age of 6.4 ± 3.46 years. Male to female ratio was 2.5:1 and 4:1 in group A and B respectively. Fracture pattern was classified according to AO classification which showed type 32A1 was the most common pattern of injury. Spiral or long oblique fractures or fracture with comminution more than two-third of diameter of bone were considered unstable. Fall related injury either from hill slope, tree, cliff or wall was most common mode of injury which comprises of 88% of injury in each group A and B. Anatomically, middle one third diaphyseal femur fracture was most common site of femur fracture in this study [Table 2].

Table 2

Clinical details of groups A and B

Mean followup period in group A was 16.1 months (range 6-26 months) and group B was 17 months (range 6-28 months). One patient in group A was lost to followup and hence excluded from analysis.

Union was defined clinically by the absence of bony tenderness and no pain at the fracture site on weight bearing. Radiological fracture union was defined by the presence of callus. 16 children in group B who could be trained for ambulation with walking aids started walking much earlier than 14 children in group A late after removal of spica with significant mean difference (13.38 ± 2.3 2 days in group B vs. 52.33 ± 4.5 52 days in group A, P = 0.000). Rest of children in group B started walking after suture removal. Similarly, children in group B started walking without aid with mean duration of 6.6 ± 1.29 6 weeks as compared to 10.67 ± 4.32 4 weeks in group A (P = 0.002). 17 children in group B and 13 in group A were school going before the fracture. Mean duration of return to school in group B was 8.82 ± 01.7 8 weeks and 15.6 ± 2.98 15 weeks in group A (P = 0.000). In group A, clinicoradiological union was achieved within 12 weeks duration in 10 cases, in 16 weeks in another 12 cases and within17 week in last 2 cases with mean union time of 13.25 ± 2.43 12 weeks whereas all the fractures united within 12 weeks in group B with mean duration of 10.76 ± 0.72 10 weeks (P = 0.000). Children returned to full activities at mean time of 8.76 ± 2.27 8 weeks in group B and 12.08 ± 4.51 12 weeks in group A (P = 0.027) [Table 3].

Table 3

Outcome variables comparing two groups A and B

Children in group B were discharged from hospital with average duration of 6.56 ± 2.75 2 days as compare to 3.32 ± 1.4 days in group A (P = 0.000). Total hospital cost including readmission and repeat surgery for Rush pin removal were more for children with fracture managed with Rush pins (US dollars 50.68 ± 11.70) group B versus 31.04 ± 12.16 group A, (P = 0.000) [Table 3]. Increased hospital cost in group B can be attributed to longer hospital stay which ranges from 3 to 14 days as many patients in our teaching hospital come from far and remote distance from where it is not only expensive but also difficult for coming to hospital for removal of sutures. Hence, they preferred longer hospital stay until sutures were removed.

The outcome was evaluated according to Flynn's grading.7 Table 4 shows individually and overall group B have superior outcome as compare to group A. 19/25 (76%) had excellent, 5/25 (20%) had satisfactory and 1/25 (4%) had poor result in children in group B as compare to 4/24 (17%) excellent, 11/24 (49%) satisfactory and 9/24 (44%) poor in group A (P = 0.000).

Table 4

Flynn's Grading (2001, JPO)7

The children were assessed for malunion both linear, rotational and limb length disparity.

In group A, 3 patients had plaster sores at perineal area which recovered with dressing and antibiotics; 1 child had broken and loosened hip spica on 2nd week [Figure 1d] and needed reapplication of spica; 4 children had increased angular deformity or overlapping but within acceptable range on 2nd weeks of followup.

In group B, 2 children had complications related with long protruded Rush pin at entry site. One child presented with pin tract infection on the 7th day of surgery which recovered after trimming of protruded part; another child presented with bursitis after 1 year which recovered after removal of Rush pins. One patient had lost AP alignment on the 6th week followup. In one child, penetration of posterior cortex of base of neck was identified in subsequent followup. Rush pin was removed on 6th month and did not show any changes of avascular necrosis until 1½ years of followup. Another patient had penetration of greater trochanter and he also had no limb length discrepancy.

DISCUSSION

Staheli and Sheridan8 defined the ideal treatment of femoral shaft fractures in children as one that controls alignment and length, does not compress or elevate the extremity excessively, is comfortable for the child and convenient for the family and causes the least negative psychological impact possible. Immediate spica casting or skeletal traction and application of a cast is common method for treatment of diaphyseal femoral fractures in children and young adolescents and surgical intervention is indicated in open fractures, multitrauma, concomitant head injuries, burns and neuromuscular wounding. However, psychosocial and economic effects of spica cast immobilization on children and their families have been reported by Hughes et al.9 and many studies advocate early fixation of femur fracture because complications inherent in conservative treatment, such as malunion and shortening, cast intolerance, financial factors and increased hospitalization can be decreased by surgery. Among operative methods, flexible intramedulary nail has been used increasingly due to its simplicity and characteristics of load sharing internal splint which maintains length and alignment of the limb until bridging callus is formed and spares the risk of damaging the physis or the blood supply to the capital femoral epiphysis with proper surgical technique.

Torsional stability depends upon divergence of the rods in the proximal metaphysis and resistance to sagittal and coronal bending results from spreading of the pre bent rods through the diaphysis, size of the rod and material properties of the rod. Micro motion confirmed by elasticity of fixation promotes early callus formation. The Young modulus of stainless steel is nearly double that of titanium (approximately 200 GPa versus approximately 110 GPa), making it a much stiffer material with less elastic properties. Mahar et al.10 in their study have reported regarding the material alloy for flexible nails, no conclusive evidence is provided in the literature that supports the superiority of titanium over steel. Differences between these two materials have been observed in laboratory tests and it is generally accepted that steel is stronger, yet less flexible.

A study by Lee et al.11 demonstrated that ender nail fixation of simulated femur fractures maintained fracture length and rotational control with weight bearing of up to 40% of body weight, even in presence of comminution whereas Fricka et al.12 reported that the titanium implants provided greater stability in resisting torsional loading and axial compression in both transverse and comminuted fractures in biomechanical comparative study with stainless steel nails. Besides elastic property, retrogradely passed adequate size crossed Rush pins offer all the advantages of closed reduction technique and internal fixation with flexible intramedullary nails. Excellent clinical results using stainless steel flexible nails have been reported for both stable and unstable femur fracture in children. Rathjen et al.13 assume that the stiffer properties of a stainless steel implant should confer greater fracture stability, especially in the setting of an unstable fracture pattern.

A study by Wall et al.14 have demonstrated 118 patients with use of titanium elastic nails as compared with stainless steel elastic nails and noted the malunion rate was significantly higher in the titanium group (23.2%; thirteen of fifty-six) than in the stainless steel group (6.3%; three of forty-eight). The risk of malunion was nearly four times higher in the titanium group than in the stainless steel (Rush pin) group. Cramer et al.,15 prospectively evaluated 57 femoral shaft fractures in children treated with Ender rods, 21 of which were either spiral fractures or comminuted. Although, the results were not stratified according to fracture stability, the authors noted no clinically significant leg length discrepancy or malunion. Four patients did demonstrate radiographic angular deformities of <15° deviation at final followup. Another advantage of stainless steel nail would be readily availability and lesser cost. Lee et al.,16 in their study have reported that antegrade intramedullary Rush pin fixation for femoral shaft fracture in children older than 7 years is a simple and reliable alternative. A study by Simanovsky et al.17 defined that the flexible intramedullary nails can be a safe treatment option in children aged 3-5 years for femoral shaft fracture.

Treatments using nails for fixation have been indicated for patients between the ages of 4 and 17 years, although Bopst et al.17 more recently reported an indication for children as young as 1.5 years of age and Simanovsky et al.16 for those aged 3 years and over. This age group includes the phase at which these patients go to school and thus, independence during treatment is important for these patients. By reducing hospitalization time, children may return to school earlier, thereby avoiding social isolation and the need for extra care, such as the care needed to maintain hygiene when individuals are treated using casts.41920

Another advantage of Rush pin would be readily availability according to the size of pediatric femoral bone length, no need to cut and bend at the entry site of insertion. The available pre bent Rush pins are easily removable and less irritable soft-tissue. Pre bent stainless steel Rush pins are cheap, universally available and can be manufactured locally.

This study had a prospective design and used a convenience sample, which were limitations of the study. The different characteristics of the two groups of patients were also a limitation. Nonetheless, this study points toward the important that femoral shaft fractures in children can be better treated with surgery.

Retrograde intramedullary crossed Rush pins are effective method of management of pediatric diaphyseal femur fracture as compare to primary hip spica in terms of early ambulation, return to normal activities and school earlier.