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A retrospective review of 101 operatively treated radial neck fractures in children and analysis of risk factors for functional outcomes

  • Lei Yang
    Affiliations
    Department of Pediatric Surgery, West China Hospital, Sichuan University, No. 37 Guo Xue Xiang, Chengdu, Sichuan, 610041, People's Republic of China
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  • Xiaodong Yang
    Affiliations
    Department of Pediatric Surgery, West China Hospital, Sichuan University, No. 37 Guo Xue Xiang, Chengdu, Sichuan, 610041, People's Republic of China
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  • Jingjing Zuo
    Affiliations
    Rehabilitation Medicine Centre, West China Hospital, Sichuan University, No. 37 Guo Xue Xiang, Chengdu, Sichuan, 610041, People's Republic of China
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  • Daoxi Wang
    Affiliations
    Department of Pediatric Surgery, West China Hospital, Sichuan University, No. 37 Guo Xue Xiang, Chengdu, Sichuan, 610041, People's Republic of China
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  • Lang Li
    Affiliations
    Department of Pediatric Surgery, West China Hospital, Sichuan University, No. 37 Guo Xue Xiang, Chengdu, Sichuan, 610041, People's Republic of China
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  • Xueyang Tang
    Correspondence
    Correspondent author at: Department of Pediatric Surgery, West China Hospital, Sichuan University, No. 37 Guo Xue Xiang, Chengdu, Sichuan, 610041, People's Republic of China.
    Affiliations
    Department of Pediatric Surgery, West China Hospital, Sichuan University, No. 37 Guo Xue Xiang, Chengdu, Sichuan, 610041, People's Republic of China
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Open AccessPublished:July 08, 2022DOI:https://doi.org/10.1016/j.injury.2022.07.016

      Highlights

      • Radial neck fracture is a rare injury in childhood, but with a high rate of associated injuries, among which the ulnar fracture is the most common one.
      • Radial nerve palsy is a common combined injury in pediatric radial neck fracture, which was significantly associated with the severity of fractures.
      • Considering the significant correlation between fracture severity and open reduction rate, fracture severity classified as Judet type IV and open surgical method were independent predictors for unsatisfactory functional outcomes.

      Abstract

      Introduction

      Radial neck fracture is a less common injury in childhood and many factors are associated with the final functional outcomes. This study aimed to describe the clinical and radiological results of the patients with radial neck fractures treated surgically and assess the potential risk factors for poor functional outcomes.

      Patients and Methods

      This study enrolled 101 children with radial neck fracture and treated surgically at our department. Patients were followed up at least three years and assessed clinically and radiographically. The primary outcome of this study was the functional outcome assessed by using Metaizeau criteria and the secondary outcome was complications of radial head necrosis, postoperative radial nerve palsy, bone union, infection, and skin irritation. Related risk factors for unsatisfactory functional outcomes were recorded and analyzed by multivariable logistic regression.

      Results

      In total, 101 patients with 101 elbows (44 on the left side, 57 on the right side) were evaluated in our study, including 55 females (54.5%) and 46 males (45.5%), with a mean age of 7.5±2.7 years old (range, 3 to 14 years). There were 65.3% excellent (66 cases), 18.8% good (19 cases), 11.9% fair (12 cases), and 4.0% bad (4 cases) results in these patients. The rate of satisfactory outcome was 65.3% (66/101) and the rate of “unsatisfactory outcome” was 34.7% (35/101). Complications included postoperative radial nerve palsies in 15 cases (14.9%), radial head necrosis in 4 cases (4.0%), skin irritation due to the nail-end in 5 cases (5.0%), infection in 2 cases (2.0%), and bone nonunion in 1 patient (1.0%). Only Judet type (OR, 5.78; CI, 1.72-19.39, p=0.005) and surgical method (OR, 12.68; CI, 2.55-63.06, p=0.002) were independent risk factors for the unsatisfactory functional outcomes.

      Conclusions

      Closed reduction with intramedullary fixation is a primary treatment for type III and IV radial neck fractures in children. Fracture severity classified as Judet type IV and open surgical method were independent predictors for unsatisfactory functional outcomes.

      Keywords

      Introduction

      Radial neck fracture is a rare injury in childhood, and accounts for approximately 1% of all fractures and 5%-17% of all elbow fractures in children [
      • Macken AA
      • Eygendaal D
      • van Bergen CJ.
      Diagnosis, treatment and complications of radial head and neck fractures in the pediatric patient.
      ,
      • Nicholson LT
      • Skaggs DL.
      Proximal Radius Fractures in Children.
      ]. Treatment usually depends on the fracture type and degree of displacement, including nonoperative treatment of cast immobilization, closed reduction with or without internal fixation, and open reduction with internal fixation [
      • Kiran M
      • Bruce C
      • George H
      • Garg N
      • Walton R.
      Intramedullary devices in the management of Judet III and IV paediatric radial neck fractures.
      ,
      • Keil H
      • Schnetzke M
      • Kocharyan A
      • Vetter SY
      • Beisemann N
      • Swartman B
      • Grützner PA
      • Franke J.
      Long-term results after non-operative and operative treatment of radial neck fractures in adults.
      ]. The outcome of radial neck fracture in children is generally good when treated properly. However, there is still a high risk of unsatisfactory functional results, with an overall incidence of 15-33% [
      • Schmittenbecher PP
      • Haevernick B
      • Herold A
      • Knorr P
      • Schmid E.
      Treatment decision, method of osteosynthesis, and outcome in radial neck fractures in children: a multicenter study.
      ,
      • Tan BH
      • Mahadev A.
      Radial neck fractures in children.
      ]. Literature showed various attempts to establish the factors associated with the poor outcomes, such as age, fracture type, time to reduction and methods of reduction. Some of these factors are still controversial [
      • Nicholson LT
      • Skaggs DL.
      Proximal Radius Fractures in Children.
      ,
      • Kiran M
      • Bruce C
      • George H
      • Garg N
      • Walton R.
      Intramedullary devices in the management of Judet III and IV paediatric radial neck fractures.
      ,
      • Kumar S
      • Mishra A
      • Odak S
      • Dwyer J.
      Treatment principles, prognostic factors and controversies in radial neck fractures in children: A systematic review.
      ,
      • Zimmerman RM
      • Kalish LA
      • Hresko MT
      • Waters PM
      • Bae DS.
      Surgical management of pediatric radial neck fractures.
      ,
      • Garcia-Alvarez F
      • Gil-Albarova J
      • Bello ML
      • Bueno AL
      Seral F. Results in displaced radial neck fractures in children. Metaizeau technique versus arthrotomy.
      ].
      This retrospective study aimed to describe the clinical and radiological results of the patients with radial neck fractures treated surgically and assess the potential risk factors for poor functional outcomes.

      Patients and methods

      This retrospective study was approved by the Human and Ethics Committee for Medical Research at Sichuan University and was in accordance with the Declaration of Helsinki. There were a totally of 101 patients with radial neck fractures treated surgically in our department, West China Hospital, from January 2012 to January 2019. Informed consent was obtained from each patient’ parents. The inclusion criteria were as follows: patients less than 14 years old, acute injury and treated surgically within seven days, and more than three years follow-up with complete data. The exclusion criteria were pathological fractures, severe open injury, and nonsurgical treatment. The classification of fractures was based on the Judet criteria, which divided the fractures into four types according to the angle between shaft and epiphyseal axes: type I =0°, type II =0°-30°, type III =30°-60°, type IV a = 60° -80°. type IV b ≥ 80°.
      Surgery was performed by three senior pediatric orthopedic surgeons well-trained in this technique under general anesthesia. Less than three attempts of closed reduction with gentle manipulation, or the Metaizeau procedure without leverage technique were performed to achieve the reduction [
      • Metaizeau JP
      • Lascombes P
      • Lemelle JL
      • Finlayson D
      • Prevot J.
      Reduction and fixation of displaced radial neck fractures by closed intramedullary pinning.
      ]. If the reduction was unacceptable, an open procedure was considered. A lateral Kocher approach was made to achieve the radio-capitellar arthrotomy and open reduction of fractures. A 2.0-2.5mm elastic intramedullary nail was inserted from the distal radial to maintain the reduction of radial head. All patients received cast immobilization in the functional position for 4-6 weeks and followed the same rehabilitation program when the cast was removed. The intramedullary nail was removed usually six months after operation in the outpatient clinic under local anesthesia, according to the bone union on X-ray achieved before removal. Fewer were removed 1 year after operation for personal reasons. This group of patients was followed up at least for three years, with a mean follow-up of 3.8±2.6 years (range from 3-6 years). The radiographic outcomes were assessed in the first month, the third month, the sixth month, the twelfth month, and the third year. Functional outcomes were recorded based on the final follow-up.
      The baseline data were collected from the hospital records, including gender, age, side, type of fracture based on Judet classification [
      • Metaizeau JP
      • Lascombes P
      • Lemelle JL
      • Finlayson D
      • Prevot J.
      Reduction and fixation of displaced radial neck fractures by closed intramedullary pinning.
      ], combined injuries, preoperative radial nerve palsy, early reduction within 24 hours or delayed reduction beyond 24 hours, and surgical methods. All patients were assessed functionally and radiographically by two independent pediatric orthopedics together. The range of joint movement was evaluated by comparing with the healthy side and were conducted by this two pediatric orthopedics, who were also blinded to other data and analysis. The primary outcome of this study was the functional outcome assessed by using Metaizeau criteria (Table 1). The secondary outcomes were complications of radial head necrosis, postoperative radial nerve palsy, bone union, infection, and skin irritation [
      • Kumar S
      • Mishra A
      • Odak S
      • Dwyer J.
      Treatment principles, prognostic factors and controversies in radial neck fractures in children: A systematic review.
      ,
      • Metaizeau JP
      • Lascombes P
      • Lemelle JL
      • Finlayson D
      • Prevot J.
      Reduction and fixation of displaced radial neck fractures by closed intramedullary pinning.
      ,
      • Hemmer J
      • Happiette A
      • Muller F
      • Barbier D
      • Journeau P.
      Prognostic factors for intramedullary nailing in radial neck fracture in children.
      ]. In our study, we termed the excellent result in Metaizeau criteria as a “satisfactory outcome.” The good, fair, and bad results in Metaizeau criteria were termed as “unsatisfactory outcome.”
      Table 1Metaizeau functional classification.
      FunctionLoss of motion (Degree)
      Excellent0
      Good0-20
      Fair20-40
      Bad>40
      Loss of motion: the total loss of movement in flexion/extension and pronation/supination compared with the healthy side
      SPSS 26 was used for data analysis. Continuous data were reported using the mean ± standard deviation (SD) and range. Categorical data are reported as numbers and percentages. Risk factors for functional outcome were evaluated using a logistic regression model, and odds ratios (ORs) with 95% confidence intervals (CIs) were also obtained. Chi-squared tests and student's t-tests were also used in a subgroup or univariate analysis. A p-value of less than 0.05 was considered significant.

      Results

      Demographic characteristics

      101 patients with 101 elbows (44 on the left side, 57 on the right side) were evaluated in our study, including 55 females (54.5%) and 46 males (45.5%), with a mean age of 7.5±2.7 years old (range, 3 to 14 years). Twenty-seven (26.7%) patients had associated injuries, including 16 (15.8%) proximal ulnar fractures, 6 (5.9%) ulnar shaft fractures, 3 (3.0%) fractures of medial epicondyle of the humerus, 1 (1.0%) fracture of lateral condyle of humerus, and 1 (1.0%) humerus shaft fracture (Figure 1). Twelve patients (11.9%) suffered symptoms of radial nerve palsy before surgical treatment, and all recovered within 6 months. Of the 12 patients with nerve palsy, seven (35.0%, 7/20) were Judet type IVb and five (6.2%, 5/81) were type III or IVa fractures (P=0.001). The other detailed data were presented in Table 2.
      Fig 1
      Fig. 1Pediatric radial neck fractures with different associated injuries.
      (a and b) Radial neck fracture with an associated olecranon fracture. (c and d) Radial neck fracture with an associated proximal ulnar fracture. (e and f) Radial neck fracture with an associated ulnar shaft fracture. (g and h) Radial neck fracture with an associated fracture of lateral condyle of the humerus.
      Table 2Demographic data and outcomes of the patients with radial neck fractures.
      CharacteristicsCohort size(n=101)
      Gender
      Female55(54.5%)
      Male46(45.5%)
      Mean age, years7.5±2.7
      Side involved
      Left44(43.6%)
      Right57(56.4%)
      Type of fracture
      Judet type III42(41.6%)
      Judet type IV a39(38.6%)
      Judet type IV b20(19.8%)
      Associated injuries27(26.7%)
      Radial nerve palsy12(11.9%)
      Delayed reduction60(59.4%)
      Surgical method
      Open24(23.8%)
      Closed77(76.2%)
      Metaizeau function
      Excellent66(65.3%)
      Good19(18.8%)
      Fair12(11.9%)
      Bad4(4.0%)
      Postoperative radial nerve palsy15(14.9%)
      Radial head necrosis4(4.0%)
      Skin irritation5(5.0%)
      Bone nonunion1(1.0%)
      Infection2(2.0%)

      Fracture type and treatment

      According to Judet classification, 42cases (41.6%) were type III fractures, 39 cases (38.6%) were type IVa fractures, and 20 cases (19.8%) were type IVb fractures. Forty-one patients (40.6%) were treated with an early reduction within 24 hours, and 60 patients (59.4%) received delayed surgical treatment. Seventy-seven patients (76.2%) underwent closed reduction with intramedullary fixation, and 24 patients (23.8%) received the open procedure. The open reduction rate in type IV fractures (37.3%, 22/59) was significantly higher than that (4.8%, 2/42) in type III fractures (p<0.001).

      Outcomes and postoperative complications

      The mean follow-up was 3.8±2.6 years (range from 3-6 years). Based on the Metaizeau criteria, there were 65.3% excellent (66 cases), 18.8% good (19 cases), 11.9% fair (12 cases), and 4.0% bad (4 cases) results in these patients (Figure 2). The rate of satisfactory outcome was 65.3% (66/101) and the rate of “unsatisfactory outcome” was 34.7% (35/101). The mean range of motion in elbow were flexion 148°±5°, extension -3°±4°, pronation 78° ±8° and supination 94°±7°, with a main impairment on pronation. Radial nerve palsies developed in 15 patients (14.9%) after operation, including 12 (11.9%) preoperative nerve injuries and 3 (3.0%) new onsets. All patients with nerve palsies recovered within 6 months. Skin irritation due to the nail end was observed in five patients (5.0%), and all were relieved after nail removal. There were two (2.0%) cases of postoperative infections, which were treated with antibiotics and drainage. Bone nonunion occurred on one patient (1.0%) due to a severe infection. Four patients (4.0%) developed radial head necrosis of various degrees, including one IVa fracture, and 3 type IVb fractures (Figure 3).
      Fig 2
      Fig. 2Radiographic outcomes of an 11-years old boy with type III radial neck fracture on the right side.
      (a and b) Preoperative radiographs with front and lateral views. (c and d) Postoperative radiographs of the radial neck on the first day after the operation. (e and f) Postoperative radiographs in the first month after the operation. (g and h) Radiograph at the sixth month after the initial surgery.
      Fig 3
      Fig. 3Radiographic outcomes of an 11-years old boy with type III radial neck fracture on the left side.
      (a and b) Preoperative radiographs with front and lateral views. (c and d) Postoperative radiographs of the radial neck on the first day after the operation. (e and f) Postoperative radiographs at the third month after the operation. (g and h) Radiograph at the sixth month after the initial surgery, and radial head necrosis was presented.

      Risk for functional outcome

      Radial nerve palsy, Judet type and surgical method were significant factors for functional outcomes (Table 3), while adjusted for other factors, only Judet type (OR, 5.78; CI, 1.72-19.39, p=0.005) and surgical method (OR, 12.68; CI, 2.55-63.06, p=0.002) were independent risk factors for the unsatisfactory functional outcome (Table 4).
      Table 3Patients’ charactoristics and functional outcomes.
      CharacteristicsFunctional outcomeP
      SatisfactoryUnsatisfactory
      Gender0.415
      Female3421
      Male3214
      Mean age, years7.5±2.77.5±2.60.915
      Side0.599
      Left3014
      Right3621
      Type of fracture<0.001
      Judet type III375
      Judet type IV2930
      Associated injuries14130.085
      Delayed reduction38220.607
      Surgical methods<0.001
      Open618
      Closed6017
      Radial nerve palsy480.031
      Bold values are statistically significant p<0.05
      Table 4Multivariate analysis for risk factors of functional outcomes.
      CharacteristicsRisk factorsOdds ratio95% CIP
      Functional outcomeAge1.09(0.89-1.34)0.392
      Associated injuries0.36(0.08-1.55)0.170
      Delayed reduction1.49(0.51-4.36)0.472
      Surgical method12.68(2.55-63.06)0.002
      Type of fracture5.78(1.72-19.39)0.005
      Radial nerve palsy3.66(0.69-19.57)0.129
      CI: confidence interval. Bold values are statistically significant p<0.05

      Discussion

      The functional outcome of radial neck fracture is associated with many factors, among which open reduction is most reported in the literature [
      • Baghdadi S
      • Shah AS
      • Lawrence JTR.
      Open reduction of radial neck fractures in children: injury severity predicts the radiographic and clinical outcomes.
      ,
      • Falciglia F
      • Giordano M
      • Aulisa AG
      • Di Lazzaro A
      • Guzzanti V.
      Radial neck fractures in children: results when open reduction is indicated.
      ,
      • Xia A
      • You C
      • Han J
      • Wu D
      • Xia Y
      • Wang J.
      Comparison of different treatments for children with radial neck fracture and analysis of prognostic factors.
      ,
      • Kaiser M
      • Eberl R
      • Castellani C
      • Kraus T
      • Till H
      • Singer G.
      Judet type-IV radial neck fractures in children: Comparison of the outcome of fractures with and without bony contact.
      ]. Zimmerman et al [
      • Zimmerman RM
      • Kalish LA
      • Hresko MT
      • Waters PM
      • Bae DS.
      Surgical management of pediatric radial neck fractures.
      ] described a 30% open reduction rate in their 151-patients study of radial neck fractures and found open reduction as a significant risk factor for worse results. While some authors believed that a more severe fracture type usually resulted in a more invasive treatment, and might cause additional damage to tissue, blood supply, and finally poor outcomes [
      • Gutiérrez-de la Iglesia D
      • Pérez-López LM
      • Cabrera-González M
      • Knörr-Giménez J.
      Surgical techniques for displaced radial neck fractures: predictive factors of functional results.
      ,
      • Rouhani A
      • Chavoshi M
      • Sadeghpour A
      • Aslani H
      • Mardani-Kivi M.
      Outcome of open reduction and Kirschner wire fixation in pediatric radial neck fracture.
      ,
      • Shabtai L
      • Arkader A.
      Percutaneous reduction of displaced radial neck fractures achieves better results compared with fractures treated by open reduction.
      ]. This correlation between fracture type and the open reduction would make it difficult to determine whether open reduction was an independent risk factor for the outcomes. Thus, a statement of “need for open reduction” was introduced by Kumar et al to describe this correlation between fracture severity and open reduction [
      • Kumar S
      • Mishra A
      • Odak S
      • Dwyer J.
      Treatment principles, prognostic factors and controversies in radial neck fractures in children: A systematic review.
      ].
      In our study, 24 patients (23.8%) underwent open reduction treatment. The rate of unsatisfactory results in open reduction group (75%, 18/24) was significantly higher than that (22.1%, 17/77) in the closed reduction group (p≤0.001). We also noticed the correlation between fracture severity and open reduction rate (p<0.001). When considering age, fracture type, radial nerve palsy, combined injuries, open surgical method was still an independent risk factor for unsatisfactory outcomes. Thus, we believed that the open surgical procedure was a significant predictor of unsatisfactory outcomes and should only be considered for the last step. Closed reduction was still the primary choice for most severely displaced radial neck fractures and should be tried first.
      To achieve closed reduction, various attempts and techniques have been carried out. Metaizeau technique using a flexible intramedullary nail is the most common way to achieve the closed reduction and fixation [
      • Metaizeau JP
      • Lascombes P
      • Lemelle JL
      • Finlayson D
      • Prevot J.
      Reduction and fixation of displaced radial neck fractures by closed intramedullary pinning.
      ]. Shabtai et al [
      • Shabtai L
      • Arkader A.
      Percutaneous reduction of displaced radial neck fractures achieves better results compared with fractures treated by open reduction.
      ] reported a small incision-assisted reduction technique by placing a blunt side of a large Steinman pin to help reduction. Other assisted closed reduction methods by using a Kirschner or mosquito clamps were also presented in the literature [
      • Wang J
      • Chen W
      • Guo M
      • Su Y
      • Zhang Y.
      Percutaneous reduction and intramedullary fixation technique for displaced pediatric radial neck fractures.
      ,
      • Ö Bilal
      • A Murat Kalender
      • Karsli B
      • Kilinçoğlu V
      • Kinaş M
      • Dündar N
      Radiological and functional outcomes of modified Metaizeau technique in displaced radial neck fractures.
      ]. Su et al [
      • Su Y
      • Jin C
      • Duan X
      • Wang J
      • Li K
      Treatment of displaced radial neck fractures under ultrasonographic guidance in children.
      ] described an ultrasonographic guided closed reduction with Kirschner wires as a feasible treatment and could reduce the radiation exposure and the risk of posterior interosseous nerve injury. Colozza et al [
      • Colozza A
      • Padovani S
      • Caruso G
      • Cavaciocchi M
      • Massari L.
      Arthroscopically assisted reduction and pinning of a radial neck fracture in a child: a case report and review of the literature.
      ] reported an arthroscopically assisted reduction as an effective treatment method, which showed benefit in the direct visualization of the articular surface, intraarticular lesion detection, and decrease in radiation exposure. In our opinion, closed reduction and intramedullary nail fixation was an effective and less invasive choice that should be attempted before open reduction. While the closed manipulation should be gentle and multiple attempts should be avoided [
      • Pring Maya E.MD
      Pediatric radial neck fractures.
      ].
      Delayed reduction has been reported as a predictor for poor outcomes in some other fractures, such as the femoral neck fracture [
      • Patterson JT
      • Tangtiphaiboontana J
      • Pandya NK.
      Management of pediatric femoral neck fracture.
      ]. Timing of reduction for pediatric radial neck fracture was still controversial and fewer studies focused on this. Zimmerman et al [
      • Zimmerman RM
      • Kalish LA
      • Hresko MT
      • Waters PM
      • Bae DS.
      Surgical management of pediatric radial neck fractures.
      ] described time to surgery as one of the independent predictors for unsuccessful outcomes. While Garcia-Alvarez et al [
      • Garcia-Alvarez F
      • Gil-Albarova J
      • Bello ML
      • Bueno AL
      Seral F. Results in displaced radial neck fractures in children. Metaizeau technique versus arthrotomy.
      ] found no relation between delayed treatment and the functional results in children with radial neck fractures. As one of the traumatic centers in our region, most traumatic surgeries in our hospital could be performed within 12 or 24 hours. In our study, 60 patients (59.4%) received delayed surgical treatment, which mainly resulted from the long time spent on transfer from the initial hospital. Even though there was no significant difference in the functional results between early reduction and delayed reduction, we still preferred the earlier treatment.
      The type of fracture usually influences the therapeutic choice and prognosis [
      • Zimmerman RM
      • Kalish LA
      • Hresko MT
      • Waters PM
      • Bae DS.
      Surgical management of pediatric radial neck fractures.
      ,
      • Gutiérrez-de la Iglesia D
      • Pérez-López LM
      • Cabrera-González M
      • Knörr-Giménez J.
      Surgical techniques for displaced radial neck fractures: predictive factors of functional results.
      ]. Judet type I and II fractures can be treated nonoperatively with a cast or splint immobilization and achieve excellent or good results [
      • Schmittenbecher PP
      • Haevernick B
      • Herold A
      • Knorr P
      • Schmid E.
      Treatment decision, method of osteosynthesis, and outcome in radial neck fractures in children: a multicenter study.
      ]. Most Judet type III and IV injuries require surgical treatment [
      • Shlykov MA
      • Milbrandt TA
      • Abzug JM
      • Baldwin KD
      • Hosseinzadeh P.
      Displaced radial neck fractures: what are my options?.
      ]. Considering the different remodeling potential in children, the acceptable angulation and translation vary by age [
      • Pring Maya E.MD
      Pediatric radial neck fractures.
      ]. While most authors still believed an angulation of less than 30 degrees and translation of less than 50% as indications for non-reduction treatment at any age [
      • Kumar S
      • Mishra A
      • Odak S
      • Dwyer J.
      Treatment principles, prognostic factors and controversies in radial neck fractures in children: A systematic review.
      ,
      • Metaizeau JP
      • Lascombes P
      • Lemelle JL
      • Finlayson D
      • Prevot J.
      Reduction and fixation of displaced radial neck fractures by closed intramedullary pinning.
      ,
      • Gutiérrez-de la Iglesia D
      • Pérez-López LM
      • Cabrera-González M
      • Knörr-Giménez J.
      Surgical techniques for displaced radial neck fractures: predictive factors of functional results.
      ]. For this group of patients, only Judet type III and IV fractures with more than 30 degrees angulation or 50% translation were indicated for surgical treatment of reduction and fixation.
      In a study of seventy-eight patients with radial neck fractures [
      • Basmajian HG
      • Choi PD
      • Huh K
      • Sankar WN
      • Wells L
      • Arkader A.
      Radial neck fractures in children: experience from two level-1 trauma centers.
      ], the rate of unsatisfactory results in type III and IV was 58% (26/45), significantly higher than that in other types. The correlation between the Judet grade and functional outcomes has also been confirmed by many other studies [
      • Zimmerman RM
      • Kalish LA
      • Hresko MT
      • Waters PM
      • Bae DS.
      Surgical management of pediatric radial neck fractures.
      ,
      • Gutiérrez-de la Iglesia D
      • Pérez-López LM
      • Cabrera-González M
      • Knörr-Giménez J.
      Surgical techniques for displaced radial neck fractures: predictive factors of functional results.
      ]. In our study, we observed a significantly higher rate of unsatisfactory outcomes in patients with type IV fractures (50.8%,30/59) when compared to those with type III fractures (11.9%, 5/42). Adjusting for other factors, fracture severity based on Judet type remained an independent risk factor for unsatisfactory outcomes.
      The rate of associated injuries in pediatric radial neck fractures was reported as high as 39% in the previous studies, while there seemed to be no relation between associated injuries and functional outcomes [
      • Baghdadi S
      • Shah AS
      • Lawrence JTR.
      Open reduction of radial neck fractures in children: injury severity predicts the radiographic and clinical outcomes.
      ,
      • Basmajian HG
      • Choi PD
      • Huh K
      • Sankar WN
      • Wells L
      • Arkader A.
      Radial neck fractures in children: experience from two level-1 trauma centers.
      ]. In our study, 27 patients (26.7%) sustained associated injuries, and the most common injury was ulnar fracture. The presence of associated injuries was not a predictive factor for unsatisfactory outcomes. De Mattos et al [
      • De Mattos CB
      • Ramski DE
      • Kushare IV
      • Angsanuntsukh C
      • Flynn JM.
      Radial neck fractures in children and adolescents: an examination of operative and nonoperative treatment and outcomes.
      ] reported 34% of patients with associated injuries in their study, and the most common one was the ulnar fracture. They also found no relation between associated injuries and functional outcomes, which was similar to us. In our study, the open reduction rate of patients with associated injuries was 59.3% (16/27), significantly higher than that (10.8%, 8/74) of patients without associated injury (p ≤0.001). One possible reason was that the concomitant injuries might result in more instability and hinder the ability to maintain reduction.
      It is still controversial whether age is a risk factor for the outcome of pediatric radial neck fractures [
      • Kumar S
      • Mishra A
      • Odak S
      • Dwyer J.
      Treatment principles, prognostic factors and controversies in radial neck fractures in children: A systematic review.
      ,
      • Zimmerman RM
      • Kalish LA
      • Hresko MT
      • Waters PM
      • Bae DS.
      Surgical management of pediatric radial neck fractures.
      ]. The mean age of the patients in our study was 7.5±2.7 years, which was consistent with the study of Basmajian et al [
      • Basmajian HG
      • Choi PD
      • Huh K
      • Sankar WN
      • Wells L
      • Arkader A.
      Radial neck fractures in children: experience from two level-1 trauma centers.
      ], but much younger than the average age of 9-10 years in the literature [
      • Saeed W
      • Waseem M.
      Elbow fractures overview.
      ]. We noticed that age was not a significant risk factor for the outcome, which was also supported by most previous studies [
      • Hemmer J
      • Happiette A
      • Muller F
      • Barbier D
      • Journeau P.
      Prognostic factors for intramedullary nailing in radial neck fracture in children.
      ,
      • Baghdadi S
      • Shah AS
      • Lawrence JTR.
      Open reduction of radial neck fractures in children: injury severity predicts the radiographic and clinical outcomes.
      ]. Some authors found that age more than 10 years was a predictor for worse outcomes because of the lower remodeling potential in older patients [
      • Zimmerman RM
      • Kalish LA
      • Hresko MT
      • Waters PM
      • Bae DS.
      Surgical management of pediatric radial neck fractures.
      ,
      • Basmajian HG
      • Choi PD
      • Huh K
      • Sankar WN
      • Wells L
      • Arkader A.
      Radial neck fractures in children: experience from two level-1 trauma centers.
      ]. De Mattos et al [
      • De Mattos CB
      • Ramski DE
      • Kushare IV
      • Angsanuntsukh C
      • Flynn JM.
      Radial neck fractures in children and adolescents: an examination of operative and nonoperative treatment and outcomes.
      ] explained that older children more than 10 years old were more likely to have severely displaced fractures requiring open surgical treatment and resulting in a higher risk of poor outcome. We performed a subgroup analysis based on the age and found that the rate of satisfactory results (65.5%, 55/84) in patients less than 10 years was similar to that (64.7%, 11/17) of patients older than 10 years old(p=0.951). We believed in the potential of remodeling in young patients, but it seemed to have less effect on the outcomes of surgically treated radial neck fractures. This remodeling potential might benefit patients who underwent nonoperative treatment or those who suffered with a residual angulation more. More research was needed to clarify the relation between remodeling potential and outcomes.
      Radial nerve palsy is a common combined injury in pediatric radial neck fracture, and few studies focus on its effect on the functional outcome [
      • Kumar S
      • Mishra A
      • Odak S
      • Dwyer J.
      Treatment principles, prognostic factors and controversies in radial neck fractures in children: A systematic review.
      ,
      • Saeed W
      • Waseem M.
      Elbow fractures overview.
      ]. We found radial nerve palsy as a potential predictor of the unsatisfactory functional outcomes (P=0.031). While adjusted for other factors, it was no longer statistically significant. This was mainly because the preoperative radial nerve palsy was highly associated with more displaced and angulated fracture types (P=0.001), and more severe fracture types usually meant worse results.
      More than five different outcome scales were reported in literature to evaluate the functional outcomes of radial neck fractures which have similarly grades (Excellent to Poor) but were defined very differently. Thus, the reported satisfactory results rate varied a lot. In a study of 50 patients by Su et al [
      • Su Y
      • Jin C
      • Duan X
      • Wang J
      • Li K
      Treatment of displaced radial neck fractures under ultrasonographic guidance in children.
      ], they reported an excellent and good rate of 82% according to MEPI, including 62% excellent results and 20% good results. De Mattos et al [
      • De Mattos CB
      • Ramski DE
      • Kushare IV
      • Angsanuntsukh C
      • Flynn JM.
      Radial neck fractures in children and adolescents: an examination of operative and nonoperative treatment and outcomes.
      ] found a similar result that the rate of excellent result was only 52.8% for patients treated surgically. When considering the good results as successes, the successful treatment rate could reach 73.6%. Hemmer et al [
      • Hemmer J
      • Happiette A
      • Muller F
      • Barbier D
      • Journeau P.
      Prognostic factors for intramedullary nailing in radial neck fracture in children.
      ] reported a 73% excellent result and 11% good results according to Metaizeau criteria. When using their own evaluation criteria, they concluded 71% good results and 29% poor results. In another study by Zimmerman et al [
      • Zimmerman RM
      • Kalish LA
      • Hresko MT
      • Waters PM
      • Bae DS.
      Surgical management of pediatric radial neck fractures.
      ], the success rate was 68.7% (90/131), which was defined as an active elbow flexion of ≥120°, a flexion contracture of <20°, a forearm rotation of ≥90° with ≥45° of both supination and pronation, and the absence of osteonecrosis, premature physeal arrest, or neurovascular injury.
      If the satisfactory results were defined as excellent and good results, we could achieve a satisfactory rate of 84.2% (85/101), which was similar to most previous studies. Here we chose a strict criterion for “satisfactory results” in our study, resulting in a low satisfactory result of 65.3% (66/101). Thus, this result could be explained together with the specific four-grades scaling system. We also found a high rate of unsatisfactory results in the open reduction group (75%) in our study. This might be a result of the strict criteria of satisfactory results, and the fact that “need for open reduction” was significantly associated with poor results.
      The limitations of the study included retrospective, non-comparative study design, and a short follow-up. At last follow-up, some patients were still skeletally immature, which made changes in outcomes assessment possible. Another limitation was that the functional assessing system did not take daily activity and pain into consideration. We chose the Metaizeau criteria as the functional evaluation, because it was a relatively objective and accurate way for young children and was widely used in the previous studies.

      Conclusions

      Closed reduction with intramedullary fixation is a primary treatment for type III and IV radial neck fractures in children. There is still a high risk of unsatisfactory results for children with displaced fractures treated surgically. Fracture severity classified as Judet type IV and open surgical method were independent predictors for unsatisfactory functional outcomes.

      Funding

      This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors, or any pharmaceutical and industry support.

      Ethics approval and consent to participate

      This retrospective study was approved by the Human and Ethics Committee for Medical Research at Sichuan University and was in accordance with the Declaration of Helsinki. Informed consent was obtained from all patients’ parents for being included in the study.

      Consent for publication

      The patients’ parents were informed that data from the research would be submitted for publication and gave their consent.

      Availability of data and materials

      The datasets used and analyzed during the current study are available from the corresponding author on reasonable request.

      Authorship

      LY put forward the idea and wrote the first draft of the manuscript and interpretation of data for the work; JJZ and LL completed the data collection and analysis. DXW and XDY completed patients’ follow up, assessment, and data collection. XYT revised and approved the manuscript. All authors contributed to the work equally, reviewed the manuscript for important intellectual content and approved the final version to be published. All authors meet the criteria for authorship established by the International Committee of Medical Journal Editors.

      Declarations of interest

      None.

      Acknowledgements

      Not Applicable.

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