Redefining Optimal Nail to Medullary Canal Diameter Ratio in Stainless Steel Flexible Intramedullary Nailing of Pediatric Femur Fractures

Treatment of Length-Unstable Pediatric Femur Fractures in Children Aged 5 to 11 years: A Focused Review

Pediatric femur fractures in children aged 5 to 11 years are typically classified as length-stable versus length-unstable. For length-stable fracture patterns, there is frequent consensus among pediatric orthopaedic specialists regarding the appropriateness of flexible intramedullary nails, submuscular plates (SMP), or lateral-entry rigid intramedullary nails (LE-RIMN). With length-unstable fracture patterns, however, the decision is more complex. Age, weight, fracture pattern, fracture location, surgical technique, surgeon experience, several implant-specific details, and additional factors are all important when choosing between flexible intramedullary nail, SMP, and LE-RIMN. These familiar methods of fixation may all be supported by conflicting and sometimes heterogeneous data. When planning to treat length-unstable fractures in young children, surgeons should understand evidence-based details associated with each implant and how each patient-specific scenario affects perioperative decisions.

Treatment of Pediatric Femoral Shaft Fractures

Diaphyseal femur fractures are common in pediatric orthopaedic settings. A patient-specific treatment plan incorporates several factors, including age, weight, fracture pattern, associated injuries, and social considerations. Nonaccidental trauma should be considered in children younger than 3 years. In general, young children are treated with noninvasive immobilization (Pavlik harness or early hip spica casting) while school-aged children are treated with internal fixation. Internal fixation options include flexible intramedullary nails, rigid locked intramedullary nails, and plate osteosynthesis. Flexible intramedullary nails have the best outcomes in children of appropriate weight, aged 5 to 11 years, with stable fracture patterns. Lateral-entry rigid intramedullary nails have been designed for use in older children. External fixation is usually reserved for complex scenarios. Regarding all treatment methods, surgeons should be aware of several technical factors necessary to optimize outcomes.

Radial and ulnar medullary canal diameter in children: Anatomical limitations of elastic stable intramedullary nailing

INTRODUCTION

Surgery is inevitable for children who cannot achieve the ideal reduction in forearm fractures. The biggest limitation of the elastic stable intramedullary nail (ESIN) fixation method is the diameter of the medullary canal. This study aimed to measure the medullary canal diameters of the radius and ulna at different ages in children.

METHODS

The forearm radiographs of 540 children were retrospectively reviewed. All background characteristics, including weight, sex, maturity of the radius and ulna, and length of the radius and ulna, were measured and recorded. Children with radius and ulnar diameters shorter than 2 mm were analyzed by statistical regression analysis by SPSS software.

RESULTS

When we set 2 mm as the minimum medullary canal diameter, our results showed that patients aged 3-12 years had radius and ulnar diameters under this limit. The regression analysis of risk factors with the 2 mm diameter limitation had significant differences based on age (P = 0.006) and sex (P = 0.033). There was no significant difference between patients based on weight (P = 0.056), ulnar length (P = 0.946), radius length (P = 0.503), radius maturity (P = 0.655), or ulnar maturity (P = 0.774).

CONCLUSIONS

The average medullary canal diameter remained constant until 12 years of age. However, the average diameter length did not increase significantly after the age of 12 years. The incidence of medullary canal diameter shorter than 2 mm was correlated with age and sex. Our results suggest that surgeons should pay attention to the medullary diameter of the anteroposterior and lateral radiographs to determine the ESIN diameter.

Leg length discrepancy after skeletal maturity in patients treated with elastic intramedullary nails after femoral shaft fractures in childhood

PURPOSE

The purpose was to study radiographic and perceived leg length discrepancy after skeletal maturity in patients treated for femoral shaft fractures with elastic stable intramedullary nails in childhood.

METHODS

Thirty-five adults underwent standing radiographs and answered a questionnaire regarding perception of leg length discrepancy. Demographic data, fracture characteristics, angulation, stability of fixation, and callus formation, at time of fracture, were assessed.

RESULTS

Mean age at fracture was 10.2 (4.9-16.7) years, and mean follow-up time was 11.1 (3.8-16.8) years. In 8 of 35 participants, the fractured limb was 11-15 mm longer than the non-fractured, and in 16, 1-10 mm longer. In eight participants, the fractured limb was 1-10 mm shorter than the non-fractured, and in three participants, 12-23 mm shorter. The younger the child, the greater the lengthening (R_s = -0.49, p = 0.003). The greater the femoral angulation at time of fracture, the greater the shortening (R_s = 0.42, p = 0.013). There was no significant correlation between stability of fixation or callus formation 1 month postoperatively and radiographic leg length discrepancy after skeletal maturity. Fourteen (40%) had perception of leg length discrepancy at follow-up, of whom eight had a radiographic leg length discrepancy of 10-24 mm.

CONCLUSION

Treatment with elastic stable intramedullary nail of femoral shaft fracture in childhood may result in radiographic leg length discrepancy. Younger children were more prone to lengthening and should possibly be assessed before skeletal maturity. The degree of fracture stability or callus formation at the time of fracture did not significantly affect leg length discrepancy. Perception of leg length discrepancy was not necessarily associated with a radiographic leg length discrepancy (≥10 mm).

LEVEL OF EVIDENCE

level IV, case series.

Defining length stability in paediatric femoral shaft fractures treated with titanium elastic nails

INTRODUCTION

Optimal paediatric femoral shaft fracture patterns or lengths amenable to titanium elastic nail stabilization have not been well defined. The purpose of this study is to identify radiographic parameters predictive of treatment failure with flexible intramedullary nails based upon fracture morphology.

METHODS

A retrospective review was performed of all femoral shaft fractures treated with flexible intramedullary nails over a five-year period. All patients with at least six weeks of postoperative radiographic imaging were included. Fracture characteristics included location, pattern, length, obliquity, angulation, translation and shortening. Postoperative radiographs were reviewed to determine shortening and angulation.

RESULTS

There were 58 patients with 60 femoral shaft fractures stabilized with titanium nails, with 46 healing within acceptable parameters and 14 considered malunions. Six of the 14 malunions developed complications requiring early unplanned intervention. No patients in the treatment success group had a complication. Between the treatment success and failure groups, fracture pattern, location, length, obliquity, angulation, translation or shortening were not statistically different. Mean nail canal fill was significantly lower in the failure group (0.72 versus 0.81; p = 0.0146), with a receiver operating characteristic curve identifying canal fill 76% as the optimal threshold.

CONCLUSION

This is the first study to measure the length and obliquity of paediatric femoral shaft fractures and to determine their relationship to radiographic alignment after healing. None of the preoperative fracture characteristics were predictive of malalignment or shortening. We recommend the use of larger nail sizes in the treatment of paediatric femoral shaft fractures, especially if there is concern for residual instability.

LEVEL OF EVIDENCE

IV.

"Unstable" Pediatric Femoral Shaft Fractures Treated With Flexible Elastic Nails Have Few Complications

OBJECTIVES

To determine our complication rate in pediatric femoral shaft fractures treated with flexible elastic nailing and to determine fracture characteristics that may predict complications.

DESIGN

Retrospective cohort study.

SETTING

One Level 1 and One Level 2 academic trauma centers.

PATIENTS/PARTICIPANTS

One hundred one pediatric femoral shaft fractures treated from 2006 to 2018.

MAIN OUTCOME MEASUREMENT

Major and minor complications.

RESULTS

One hundred one femurs met inclusion criteria. The average age was 7 years (range 3-12 years). The average weight was 29.0 kg (range 16-55 kg). The average follow-up was 11 months (6-36 months). Ninety-three patients underwent elective implant removal at our institution. Fifty-one of the 101 (50%) fractures were "unstable" patterns. Ninety-three percent had implants that filled >80% of the canal (69 titanium and 32 stainless steel). Seventeen percent (18) had cast immobilization. All fractures went on to union. No patient required revision surgery for malunion as follows: 6 had coronal/sagittal malalignment >10 degrees, 3 had malrotation >15 degrees, and none had a leg length inequality >1 cm. Three patients had an unplanned surgery as follows: 2 for prominent implants and 1 for refracture after a second injury. There were no patient, fracture, or treatment characteristics that were predictive of complications or unplanned surgery, including "unstable" fractures (P = 0.78).

CONCLUSION

Our study demonstrates that flexible elastic nailing can be safely used in most pediatric femoral shaft fractures, including those previously described as "unstable."

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions to Authors for a complete description of levels of evidence.

The Association of Metal Frame Construct of ESIN and radiographic bone healing of pediatric forearm fractures

INTRODUCTION

The gold-standard surgical procedure of both-bone forearm shaft fracture repair is elastic stable intramedullary nailing (ESIN). Disadvantages effects of ESIN have suggested to be a consequence of inappropriate surgical techniques, while recommendations are not always followed. The purpose of the study was to analyze the effect of inadequate metal frame construct on impaired fracture healing, refracture and changing alignment.

MATERIALS AND METHODS

It is a population-based study including all consecutive patients, aged less than 16 years, who had been treated for forearm shaft fracture by ESIN during the ten-year period 2009-2018. Altogether 71 patients were included. Non-union, delayed union, and re-fracture during the following 12 months were taken as the main outcome, while inferior metal frame construct of ESIN and the surgical technique characteristics were taken the explanatory factors. Radiographic loss of reduction was a secondary outcome and a change >5° in alignment at any postoperative follow-up exam was recognized.

RESULTS

Two out of 71 fractures (3%) failed to unite, and ossifying operation was needed. Five cases (7%) showed delayed bone healing, but they ossified in five months without any intervention. These seven patients (10%) had been treated more often with larger nails (> 0.7x MCD) (p = 0.027) and by open reduction (p = 0.02), compared with thinner nails and closed reduction, respectively. Two (3%) patients had a second fracture; however, they happened 2 years after the initial injury. Other surgery or fracture related factors didn't associate with impaired ossifying. Regarding the secondary outcome, altogether 24 (35%) of the analyzed 67 patients showed >5° change in alignment during the postoperative follow-up but only one patient had clinically significant instability that required re-reduction. The alignment changed more usually in distal-third fractures, compared with middle or proximal third fractures (p = 0.019).

CONCLUSIONS

ESIN resulted in good radiographic bone healing in the vast majority (90%) of the patients and completely perfect metal frame construct was not required.

Retrograde Stainless Steel Flexible Nails Have Superior Resistance to Bending in Distal Third Femoral Shaft Fractures

BACKGROUND

It has been shown that retrograde titanium flexible intramedullary nails (Ti FIN) provide superior resistance to bending compared to antegrade Ti FIN in distal femur fractures. The purpose of this study was to compare resistance to torsional and bending forces of stainless steel (SS) FIN, with or without a locking screw, and Ti FIN in distal third femoral shaft fractures. We hypothesize that locked retrograde SS FIN will demonstrate greater resistance to both bending and torsional forces.

METHODS

Thirty adolescent synthetic femur models were used to simulate transverse distal femoral fractures at either 60 mm or 90 mm proximal to the distal femoral physis. The femurs were instrumented with antegrade Ti FIN, antegrade SS FIN, retrograde Ti FIN, retrograde SS FIN, or retrograde locked SS FIN. Three models for each construct at both osteotomy levels were tested. Models were analyzed to determine maximum resistance to bending and torsion.

RESULTS

In fractures 60 mm from the physis, retrograde SS FIN demonstrated statistically superior resistance to bending when compared with both antegrade and retrograde Ti FIN (P=0.001 and 0.008, respectively) and antegrade SS FIN (P=0.0001). Locked SS constructs showed a trend towards greater resistance to bending forces when compared with unlocked constructs (P>0.05). No significant difference was seen in resistance to bending when fractures were 90 mm proximal to the distal femoral physis between the five groups. No significant differences were observed in resistance to torsion in either the proximal or distal fracture models, regardless of construct type.

CONCLUSIONS

Retrograde SS FIN confer significantly greater resistance to bending forces for fractures 60 mm proximal to the distal femoral physis compared with Ti FIN or antegrade entry SS FIN. In fractures 90 mm from the physis, no differences were noted in our model. Our results support the use of retrograde SS nails in the pediatric patient with distal femoral shaft fractures.

LEVEL OF EVIDENCE

Level II-comparative biomechanical study.

A Quartet of Elastic Stable Intramedullary Nails for More Challenging Pediatric Femur Fractures

INTRODUCTION

The insertion of 2 elastic stable intramedullary nails (ESINs) is a common treatment for pediatric femur fractures. However, the use of this technique in length-unstable or metadiaphyseal fractures has historically been associated with higher complication rates. To improve stability, the addition of a third ESIN has been assessed biomechanically and clinically, but the addition of a fourth nail has only been evaluated biomechanically. The purpose of this study is to report our surgical technique and radiographic outcomes using a quartet of ESINs in pediatric femur fractures.

METHODS

A retrospective review was performed of pediatric patients with length-unstable or metadiaphyseal femur fractures who were treated with 4 ESINs by a single surgeon from 2008 to 2013. Nails were inserted in a retrograde manner, 2 each from medial and lateral starting points. Patients were followed clinically and radiographically until the union and routine removal of hardware. Primary outcomes included fracture union, sagittal, and coronal plane alignment, and complications.

RESULTS

Fourteen patients underwent quartet ESIN placement. Two patients were excluded: one for early loss to follow-up and another with a diagnosis of osteogenesis imperfecta. The average patient age was 9.3 years (range, 4 to 14 y) and weight was 47 kg (range, 21 to 95 kg). All fractures achieved radiographic union at mean 5.5 months (range, 2 to 9 mo). Hardware was removed at a mean of 9.4 months (range, 2 to 22 mo) following implantation. At final mean follow-up of 18 months, patients and families reported no functional limitations. There were no hardware failures or revision surgeries. There were no limb length discrepancies or malalignment at the time of final radiographic follow-up. There were 2 minor complications-1 patient with pain secondary to nail migration resulting in prominence at the knee and another with refracture following a fall. The stable refracture occurred before complete fracture union and hardware removal and went on to the union without the need for any additional treatment.

CONCLUSIONS

Treatment with a quartet of ESINs should be considered for skeletally immature children with length-unstable or metadiaphyseal femur fractures. In this series, all fractures achieved union without major complications or hardware failure. This modification to traditional elastic nailing techniques is an option for the surgeon to consider as an alternative to rigid intramedullary nailing, submuscular plating, or external fixation.

LEVEL OF EVIDENCE

Level IV.

Pediatric Orthopedic Trauma: An Evidence-Based Approach

The management of pediatric fractures has evolved over the past several decades, and many injuries that were previously being managed nonoperatively are now being treated surgically. The American Academy of Orthopaedic Surgeons has developed clinical guidelines to help guide decision making and streamline patient care for certain injuries, but many topics remain controversial. This article analyzes the evidence regarding management of 5 of the most common and controversial injuries in pediatric orthopedics today.