Adolescent locked femoral nail for recurrent femoral fractures in children with osteogenesis Imperfecta: a case report and literature review

Abstract

Background

Osteogenesis imperfecta (OI) is a hereditary connective tissue disorder characterized by increased bone fragility and recurrent fractures. The femur is the most frequently fractured site in pediatric OI patients. Traditional internal fixations such as plates and elastic intramedullary nails carry high complication rates. Although extendable intramedullary nails represent the gold standard for children with OI, they show insufficient stability in adolescent patients with large medullary cavities and severe osteoporosis. Adolescent Locked Femoral Nail (ALFN) is a fixation system designed for adolescents, but its specific efficacy in recurrent femoral fractures in adolescent OI patients has been rarely reported.

Case presentation

A 13-year-old male patient with a confirmed COL1A1 pathogenic variant (Sillence type III OI) experienced four left femoral fractures within 5 years. The first two fractures were treated with plate fixation at a local primary hospital and both resulted in postoperative refracture; the third fracture was managed with plate fixation in our hospital, which also ended in refracture.For the fourth fracture, closed reduction and titanium alloy ALFN fixation were performed, combined with intravenous zoledronic acid infusion. At the 3-year follow-up, the fracture healed uneventfully without refracture; the lower limb alignment was normal, with a 0.5 cm limb-length discrepancy and satisfactory knee function.

Conclusions

ALFN provides central, stable intramedullary fixation, preserves bone blood supply, and matches the anatomical features of the adolescent femur. Combined with anti-osteoporotic medication, ALFN may serve as a valuable option for selected adolescent OI patients with recurrent fractures, wide medullary canals, or failure of previous fixation methods to reduce refracture risk. For adolescents with unexplained recurrent fractures, early genetic testing and individualized surgical planning are critical to improve clinical outcomes.

1. Introduction

Osteogenesis imperfecta (OI) is a genetic connective tissue disorder mainly caused by type I collagen abnormalities, resulting in low bone mineral density, impaired bone microstructure, and markedly increased bone fragility (1–3). The femur is the most common fracture site in children with OI, and the risk is particularly high during adolescence due to active movement and open physes (4). Recurrent fractures can lead to progressive deformity, limb shortening, and poor quality of life (5).

Surgical intervention is essential for recurrent femoral fractures. Traditional plates and elastic intramedullary nails are associated with high complication rates (6). Extendable intramedullary nails (e.g., Fassier-Duval, Bailey-Dubow) are the gold-standard treatment for pediatric OI due to their ability to accommodate skeletal growth (5, 6). However, these devices often lack sufficient stability in adolescent OI patients with extremely enlarged medullary cavities and severe osteoporosis (7).

Adolescent Locked Femoral Nail (ALFN) is specifically designed for patients over 11 years old or weighing more than 50 kg (8). While rigid intramedullary fixation has been reported in adolescents with metabolic bone disease (9), the application of ALFN in adolescent OI patients with recurrent femoral fractures remains poorly documented. We present a 13-year-old OI patient with four left femoral fractures in 5 years, successfully treated with ALFN and zoledronic acid, with a 3-year follow-up.

2. Case presentation

This study was conducted in accordance with the Declaration of Helsinki and approved by the Ethics Committee of Chuxiong Prefecture Hospital of Traditional Chinese Medicine. Written informed consent was obtained from the parents of the minor participant. Patient Luo XX, male, born on July 4, 2009, experienced four left femoral fractures within 5 years. The detailed timeline and treatment course are as follows Table 1:

Table 1.

Chronological Timeline.

Time	Age	Fracture site	Mechanism	Fixation	Implant removal	Outcome
July 2, 2019.	8 y	Left femoral midshaft	Fall	Open reduction + plate	Jan 14, 2020	Refracture 10 days after removal
January 24, 2020	10 y	Left femoral midshaft	Atraumatic	Open reduction + double plates	Not performed	Jun 2020 refracture
June 19, 2020	11 y	Proximal-middle third junction	Sprain	Open reduction + long plate	Aug30, 2021	Mar 2023 refracture
March 31, 2023,	13 y 9 m	Proximal-middle third junction	Fall	Closed reduction + ALFN	Not planned	Healing without refracture at 3 years

2.1. Chronological timeline of fractures and treatment

On July 2, 2019, the patient sustained a closed left femoral midshaft fracture (Figures 1A,B). He presented with left thigh pain and limited movement, and was admitted to a local hospital with a diagnosis of left femoral midshaft fracture. Open reduction and plate internal fixation of the left femoral shaft fracture were performed. Postoperative x-ray review showed good fracture alignment (Figures 1C,D). x-ray at 6 months postoperatively confirmed fracture healing (Figures 1E,F). The plate and screws were removed at the local hospital on January 14, 2020 (Figures 1G,H).

Figure 1.

(A,B) Post-injury radiographs showing a midshaft fracture of the left femur with displacement and overlap of the fracture fragments. (C,D) Postoperative radiographs demonstrating satisfactory reduction of the fracture. (E,F) Radiographs at 6 months postoperatively showing good fracture healing. (G,H) Radiographs after removal of the plate and screws.

On January 24, 2020, the patient developed left thigh deformity and pain at home without trauma. He was taken to the local hospital, and x-ray showed a left femoral shaft fracture at the same site as the first fracture (Figures 2A,B). Open reduction, iliac bone grafting, and double-plate fixation were performed (Figures 2C,D). x-ray at 5 months postoperatively showed good fracture healing (Figures 2E,F).

Figure 2.

(A,B) Radiographs showing refracture after implant removal, with screw holes visible. (C,D) Postoperative radiographs following open reduction, iliac bone grafting, and double-plate internal fixation. (E,F) Radiographs at 5 months postoperatively, showing gradual healing of the femoral fracture.

On June 19, 2020, the patient sprained his left thigh accidentally at school and again presented with left thigh pain and deformity. He was admitted to the Department of Lower Extremity Trauma Orthopedics of our hospital. x-ray showed a fracture of the proximal-middle third junction of the left femur (Figures 3A,B). After comprehensive evaluation, open removal of the plate and open reduction and plate internal fixation of the femoral fracture were performed on June 22, 2020 (Figures 3C,D). x-ray at 14 months postoperatively showed good fracture healing (Figures 3E,F). Plate internal fixation removal was performed on August 30, 2021, and postoperative x-ray confirmed removal of the plate and screws (Figures 3G,H).

Figure 3.

(A,B) The third femoral fracture, located at the site of the first proximal screw. (C,D) Postoperative radiographs after removal of the original plate, fracture reduction, and internal fixation with a long plate, showing satisfactory fracture reduction. (E,F) Radiographs at 14 months postoperatively showing good fracture healing. (G,H) Post-removal radiographs demonstrating complete removal of the plate and screws, with a thin femoral shaft cortex.

On March 31, 2023, he fell and sustained a fourth fracture at the proximal-middle third junction of the left femur (Figures 4A,B). Preoperative evaluation revealed a wide distal femoral medullary cavity, thin cortex, and severe osteoporosis. Surgical contraindications including local infection, coagulation disorders, and neurovascular injury were excluded. The patient weighed 55 kg, aged 13 years and 9 months. Closed reduction and ALFN (titanium alloy, Φ10 × 340 mm) were performed under C-arm guidance. The entry point of ALFN was chosen on the lateral aspect of the greater trochanter, at the same level as the superior border of the piriform fossa. It is located at the intersection of the line 20 mm distal to the lesser trochanter and a trajectory with a 12° lateral offset angle relative to the medullary canal axis. This point lies on the central axis of the medullary canal on the lateral view (Figure 4C), avoiding injury to the femoral neck physis. Postoperative x-ray showed good fracture reduction and appropriate nail size (Figure 4D). Genetic testing on October 30, 2023, detected a pathogenic variant in the COL1A1 gene, confirming the diagnosis of osteogenesis imperfecta (Figure 4E).

Figure 4.

(A,B) The fourth fracture at the proximal-middle third junction of the left femur, with a wide distal medullary cavity and thin cortex. (C) Schematic diagram of the entry point for the Adolescent Locked Femoral Nail (ALFN) in anteroposterior and lateral views. Adapted with permission from Adolescent Locked Femoral Nailing (ALFN) Operation Manual, Double Medical Technology Inc., Xiamen, China, 2018, Edition 201809, official internal technical manual, official website: www.double-medical.com. (D) Postoperative radiograph after closed reduction and ALFN fixation, showing satisfactory fracture reduction and appropriate nail size. E: SNV/InDel plot. showing a de novo heterozygous COL1A1 mutation, which is responsible for the clinical phenotype of severe OI and recurrent fragility fractures. (E,F) Radiographs at 6 months postoperatively, showing obvious callus formation and no abnormalities of the intramedullary nail. (G) Radiograph at 1 year postoperatively, demonstrating good fracture healing and unremarkable internal fixation. (H,I,J) Radiographs obtained 2 years postoperatively, showing no femoral refracture and intact internal fixation without abnormalities. (K,L) Radiographs obtained 3 years postoperatively, presenting no femoral refracture, normal internal fixation, absence of femoral head osteonecrosis and no hip deformity.

2.2. Postoperative rehabilitation and follow-up

Postoperative rehabilitation after ALFN surgery，Partial weight-bearing at 6 weeks; full weight-bearing at 12 weeks; active knee and hip exercise from postoperative day 3. No implant removal is planned. The patient received intravenous zoledronic acid (3 mg) every 6 months, combined with calcium and vitamin D supplementation. x-ray at 6 months postoperatively showed fracture healing (Figures 4F,G). At the 3-year follow-up, annual x-ray reviews showed no refracture of the femur or other sites (Figures 4H–L). The left lower limb was 0.5 cm shorter than the right, and the lower limb alignment was within the normal range (Figure 5A). The patient had no lower limb deformity and normal knee flexion and extension at 3 years postoperatively (Figures 5B–D).Skeletal Maturity and Physeal Status: a) Age 8 years: distal femoral physes fully open, b) Age 10 years: distal femoral physes partially open; c) Age 11 years: distal femoral physes closing; d) Age 13 years: distal femoral physes nearly closed.

Figure 5.

(A) Full-length radiograph of both lower extremities at 3 years postoperatively shows a 0.5 cm shortening of the left lower extremity compared with the right, with the alignment of both lower extremities within normal limits. (B,D) At 3 years postoperatively, the patient has no lower extremity deformity and normal knee flexion and extension.

3. Discussion

Pediatric osteogenesis imperfecta (OI) is a rare hereditary bone disease characterized by markedly increased bone fragility and recurrent fractures. The molecular mechanism is mostly attributed to abnormal type I collagen structure or synthesis (10). Genetically, COL1A1 and COL1A2 mutations are the most common causes, accounting for approximately 69% of pathogenic variants in children with recurrent fractures (11). The present patient carried a pathogenic variant in the COL1A1 gene, consistent with the severe clinical phenotype. The femur is the most frequently injured site in children with OI, particularly during infancy and puberty. Minimal trauma can induce fractures, and previous fracture is a strong risk factor for refracture (12). This patient sustained four left femoral fractures within 5 years after trivial injuries, which is highly typical of severe OI. The patient had blue sclera, no dentinogenesis imperfecta, no hearing impairment, and a negative family history. He was classified as Sillence type III OI.

Conservative treatment including casting, bracing, and traction may be considered for stable, minimally displaced fractures but is limited by complications such as joint stiffness, muscle atrophy, and further bone loss. Therefore, surgical intervention is strongly recommended for recurrent femoral shaft fractures in OI (5, 13).With the development of multidisciplinary management, surgery combined with anti-resorptive agents has become the standard strategy for OI fractures. Zoledronic acid improves bone mineral density and reduces fracture risk and has been safely used in pediatric OI patients (14). Intramedullary fixation is the preferred surgical method, whereas conventional plating is no longer recommended due to inherent disadvantages. As an eccentric fixation method, plate-screw systems require extensive exposure and periosteal stripping before fixation, which not only disrupts blood supply at the fracture site but further weakens the already fragile cortical bone, easily causing stress concentration at the fixation site and leading to complications such as implant failure and refracture. Intramedullary fixation is an important surgical technique. The core goal of surgery is to balance fracture healing, deformity correction, functional recovery, minimally invasive trauma, and refracture prevention, while taking into account the skeletal growth needs of adolescent patients (6). Elastic intramedullary nails and Kirschner wire fixation also carry high complication risks and cannot meet the long-term stable fixation needs of OI children (7).

Before the diagnosis of osteogenesis imperfecta (OI) was confirmed, the child underwent plate fixation for two femoral fractures at a local primary hospital. For the first fracture at the age of 8 years—a transverse midshaft femoral fracture in an 8-year-old child—elastic intramedullary nailing is the evidence-based first-line surgical option. Conventional plate fixation, however, is not recommended for this indication due to inherent drawbacks, including extensive periosteal stripping, disruption of bone blood supply, stress concentration, and a significantly increased risk of refracture. For the second and third fractures (at the ages of 10 and 11 years), although telescopic extendable intramedullary nailing represents the gold-standard treatment for femoral fractures in children with OI, this technique was not applicable due to the patient's narrow femoral medullary canal and extremely poor bone quality. Meanwhile, elastic intramedullary nailing was also unsuitable for this case because of the patient's insufficient bone mass and high risk of fracture displacement after reduction. At the time of the third fracture (11 years old, weighing 42 kg), although the patient weighed 42 kg, Adolescent Locked Femoral Nail (ALFN) or telescopic intramedullary nailing could have been considered. However, the treating surgeon was an adult orthopedist who did not fully recognize the patient's underlying OI, and plate fixation was therefore used again. The successful outcome of ALFN fixation in this patient strongly suggests that earlier transition from load-bearing plate fixation to load-sharing intramedullary fixation may reduce the risk of refracture in pediatric OI patients once the diagnosis is suspected. The implant selection was progressively adjusted according to the patient's increasing age, body weight, enlarging medullary canal, and skeletal maturity. In recent years, combined internal fixation with intramedullary nail and plate has emerged as a research hotspot in the management of fractures in patients with osteogenesis imperfecta (OI). For adolescent and adult OI patients, particularly those presenting with severely comminuted and long-segment fractures involving the middle and distal femoral shaft, standalone intramedullary nailing often cannot provide adequate bone purchase and anti-rotational stability, thereby necessitating adjunct plate fixation. Furthermore, combined internal fixation serves as an optimal salvage and reconstructive option for complex clinical scenarios, including previous internal fixation failure (e.g., intramedullary nail migration or breakage), fracture nonunion, and angular deformities greater than 30° that require corrective osteotomy (15).

3.1. Extendable intramedullary nails vs. ALFN

Extendable intramedullary nails (e.g., Fassier-Duval) are effective in young children with OI and can lengthen with skeletal growth (16). However, they may provide insufficient stability and anti-rotation control in adolescent OI patients with extremely wide medullary cavities and severe osteoporosis, leading to loosening and refracture (7). Adolescent Locked Femoral Nail (ALFN) is specifically designed for adolescents and provides central, locked, three-dimensional stability that better fits large canals. Rigid intramedullary nailing has been reported in adolescents with metabolic bone disease (9), but the specific application of ALFN in adolescent OI patients with recurrent fractures and failed previous fixation has rarely been reported.

ALFN is inserted through a lateral trochanteric entry point, which avoids injury to the femoral head blood supply and the proximal femoral physis (8). Closed insertion preserves periosteal blood supply and promotes faster healing. These advantages explain the uneventful union and absence of refracture during 3-year follow-up in this patient.

3.2. Synergistic effect of ALFN and zoledronic acid

Stable fixation provided by ALFN allowed early functional exercise and protected against refracture. Combined with periodic zoledronic acid infusion, bone mineral density and bone quality were improved, creating a synergistic effect that contributed to the favorable long-term outcome.

3.3. Limitations

ALFN is not suitable for patients with severe femoral bowing deformity before corrective osteotomy. Gentle manipulation is required to avoid iatrogenic fractures, which occur in approximately 4.2% of orthopedic procedures in OI patients (17). In addition, both ALFN and telescopic nailing require specialized surgical skills, limiting widespread use in primary hospitals.

4. Conclusions

This case demonstrates that ALFN may be a useful salvage option for selected adolescent OI patients with recurrent femoral fractures, wide medullary canals, or failure of traditional fixation methods. ALFN combined with zoledronic acid provides stable fixation, promotes fracture healing, and reduces refracture risk. Early genetic testing and individualized surgical strategy are critical for improving outcomes in these patients.

Funding Statement

The author(s) declared that financial support was not received for this work and/or its publication.

Data availability statement

The original contributions presented in the study are included in the article/Supplementary Material, further inquiries can be directed to the corresponding author.

Ethics statement

This study was conducted in accordance with the Declaration of Helsinki and approved by the Ethics Committee of Chuxiong Yi Autonomo us Prefecture Hospital of Traditional Chinese Medicine. Written informed consent was obtained from the individual(s), and minor(s)' legal guardian/next of kin, for the publication of any potentially identifiable images or data included in this article.

Author contributions

WY: Writing – review & editing, Writing – original draft. JL: Writing – review & editing. ZC: Writing – review & editing. JD: Writing – original draft. ZZ: Writing – review & editing. TX: Writing – original draft. DW: Writing – review & editing, Writing – original draft.

Conflict of interest

The author(s) declared that this work was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Generative AI statement

The author(s) declared that generative AI was not used in the creation of this manuscript.

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