Treatment of Pathological Femoral Fractures Caused by Fibrous Dysplasia Using the Bridging Combination Internal Fixation System: A Case Report

Introduction

Fibrous dysplasia (FD) is a rare benign bone disorder first described by Lichtenstein in 1938 [1]. Histologically, normal lamellar bone is replaced by structurally defective fibro-osseous tissue, weakening the skeleton [2]. Clinically, FD presents as monostotic (80% of cases), polyostotic (PFD), or McCune-Albright syndrome with endocrine disturbances [3–5]. Activating somatic mutations in the GNAS gene drive FD pathogenesis. These mutations impair osteoblastic differentiation and produce mechanically inferior fibrous bone [2,6].

The manifestations of FD are diverse, ranging from no symptoms to local pain, swelling, and deformity [7]. PFD often affects the proximal femur, and severe cases can present with the typical “Shepherd’s crook” deformity. Due to the unique anatomical structure and stress concentration of the proximal femur, patients with PFD are most susceptible to pathological fractures in this region [4].

Current FD therapies center on surgery, the only modality with curative potential. Pharmacologic agents show promise but still lack large-scale evidence supporting their ability to halt disease progression [6,8]. Reported surgical options include curettage, bone grafting, osteotomy, plate fixation, intramedullary nailing, and hip arthroplasty [8]. All current procedures have drawbacks. Curettage plus grafting shows high failure and recurrence rates [9,10]. Plate fixation lacks stability in FD-affected bone [8]. Intramedullary nailing gives strong fixation but increases blood loss during reaming [11], and femurs deformed by FD raise technical difficulty [12]. Total hip arthroplasty is challenging due to limited bone stock and proximal femoral deformity. Therefore, novel and effective treatment strategies remain to be explored.

We report our first use of a bridging combination internal fixation system to treat a patient with PFD, Shepherd’s crook deformity, and a left subtrochanteric pathological fracture. Follow-up showed good results. This report is presented to provide a reference for the surgical treatment of such patients.

Case Report

A 29-year-old Chinese man was injured 15 days before presentation, when he accidentally fell off an electric bike and hurt his left thigh. At the time, he experienced only mild pain and tenderness in the upper part of his left thigh but could still move independently. Believing that conservative treatment would suffice for recovery, he did not pay much attention to the injury and did not seek medical attention. Three days before presentation, the pain in his left thigh worsened significantly and was accompanied by limited mobility in his left lower limb, prompting him to visit our hospital. Upon examination at the hospital, specialized physical findings revealed slight swelling in the left hip area with obvious tenderness and a noticeable adduction deformity in the left lower limb. The patient had a 20-year history of fibrous FD. Additionally, he had experienced 2 significant falls in the past – one 20 years earlier, resulting in a right knee fracture, and another 10 years earlier, resulting in a right femoral fracture. At the time of those falls, due to having mild symptoms, he opted for conservative treatment, which eventually led to significant improvement in his condition.

Following admission, pelvic X-ray, left femoral X-ray, and 3-dimensional computed tomography (CT) of the left hip were obtained. These studies demonstrated bilateral femoral FD complicated by a pathological subtrochanteric fracture of the left femur (Figure 1). Integrating these imaging findings with the patient’s long-standing history of FD, we established the diagnosis of bilateral femoral FD with an acute pathological subtrochanteric fracture of the left femur. After completing routine preoperative examinations, including an electrocardiogram and chest CT, and confirming no surgical contraindications, the patient underwent surgical treatment for a left subtrochanteric femoral fracture under general anesthesia on day 4 of hospitalization.

The surgical procedure was as follows. After satisfactory anesthesia was achieved, the patient was placed in a supine position with the buttocks elevated and the left lower limb routinely disinfected and draped. A 9-cm incision was made just below the left greater trochanter, and the skin and subcutaneous tissue were incised. Hemostasis was achieved using an ablation electrode, and the iliotibial band and greater trochanter bursa were sharply incised. The left femoral subtrochanteric fracture with lateral angulation and displacement was observed. The proximal femur was deformed and osteoporotic. The fracture was reduced by traction and external rotation of the left lower limb. An additional 7-cm longitudinal incision was created over the distal lateral aspect of the left thigh; the skin, subcutaneous tissue, and iliotibial band were incised in sequence. A long, blunt, curved Kelly forceps was then introduced to establish a submuscular tunnel extending from the greater trochanter to the lateral femoral condyle. The bridging combination internal fixation system (Tianjin Vima) was contoured according to the morphology of the patient’s femur and placed on the lateral side of the femur, with temporary fixation using Kirschner wires. Fluoroscopy with a C-arm showed satisfactory reduction of the left femoral subtrochanteric fracture and restoration of cortical continuity. The length and position of the bridging combination internal fixation system were satisfactory. Holes were drilled, depths measured, and screws were inserted to fix the fracture ends in the proximal and distal parts of the left femur. Fluoroscopy was repeated to confirm satisfactory fracture reduction and appropriate position and length of the internal fixation. The wound was irrigated, a negative pressure drain was placed, and the incision was sutured. The wound was covered with sterile dressing. (Note: the bridging combination internal fixation system used in this procedure – composed of connecting rods, fixation blocks, and locking screws – was supplied by Tianjin Vima. The implants included 2 connecting rods (6 mm in diameter, 400 mm in length); 9 fixation blocks with 6-mm holes, with 4 single-rod/single-hole, 3 double-rod/single-hole, and 2 double-rod/double-hole blocks; and 9 locking screws, 5 mm in diameter, with 5 placed proximal to the fracture line (85 mm, 55 mm, 60 mm, 60 mm, and 55 mm in length) and 4 placed distal to the fracture line (32 mm, 32 mm, 34 mm, and 45 mm in length).

Postoperatively, the patient was returned to the ward and received prophylactic antibiotic therapy, thromboprophylaxis, anti-edema treatment, analgesia, and active fluid resuscitation. On postoperative day 2, a follow-up X-ray of the left femur was performed, as shown in Figure 2A and 2B. The patient was discharged on postoperative day 5 after an uneventful recovery.

A tailored rehabilitation protocol was instituted. On postoperative day 1, static quadriceps contractions and ankle-pump exercises were initiated to prevent venous thrombo-embolism. From postoperative day 2, passive or active-assisted hip and knee flexion was introduced within a 0° to 30° arc. Between day 3 and week 4, the range of motion was progressively advanced: hip flexion 0° to 90°, abduction 0° to 15°, adduction 0° to 10°; and knee flexion 0° to 90°, internal rotation 0° to 5°, and external rotation 0° to 15°. A hinged knee brace was worn for the first 2 weeks to protect soft-tissue healing. From 4 to 8 weeks, the program was intensified: hip flexion 0° to 120°, abduction 0° to 30°, adduction 0° to 20°; and knee flexion 0° to 130°, internal rotation 0° to 10°, and external rotation 0° to 30°. Weight-bearing was strictly staged according to implant stability and compromised bone quality: non-weight-bearing for the first week, toe-touch weight-bearing from week 1 to week 4, partial weight-bearing from week 4 to week 12, and full weight-bearing thereafter, contingent upon absence of pain and radiographic evidence of progressive callus formation.

After discharge, the patient regularly attended outpatient follow-ups. At the 1-month follow-up, new bone callus formation was observed at the fracture site, as shown in Figure 2C and 2D. At the 3-month follow-up, the fracture line had become indistinct, and the amount of bone callus had significantly increased, compared with the 1-month follow-up, as shown in Figure 2E and 2F. At 4 months after surgery, the fracture line had almost disappeared, and the patient was able to perform hip and knee flexion exercises exceeding 90°, as shown in Figure 2G–2I. At 6 months after surgery, the fracture line had completely disappeared, and the patient was able to walk and squat normally, indicating good functional recovery of the affected limb, as shown in Figure 2J–2M. The patient’s preoperative Harris Hip Score for the left hip was 28 points; this improved to 73 points at 3 months after surgery and to 88 points at 6 months. In addition, we used the Radiographic Union Scale for Hip (RUSH) score [13] to perform serial radiographic assessments at 1, 3, and 6 months after surgery, yielding scores of 9, 22, and 28 points, respectively. These findings further confirm the efficacy of this treatment approach.

Discussion

FD is a rare congenital, benign, self-limiting bone disease [1], with a low incidence rate, accounting for approximately 0.2% of all primary bone tumors [14]. Due to the low incidence of FD, there is currently no unified standard treatment protocol. According to the literature, treatment strategies include conservative management and surgical intervention [15,16].

The decision to treat patients with FD surgically should be made after a thorough assessment of the patient’s condition. Age is an independent factor affecting surgical outcomes. Children have active bone metabolism and are prone to recurrence after surgery. Therefore, for patients who do not require surgery, such as those without significant deformity, with a small lesion destruction range, and a low risk of pathological fracture, surgery should be considered after skeletal maturation. However, for patients with severe skeletal lesions such as Shepherd’s crook deformity of the proximal femur or pathological fractures, early surgery should be considered to prevent more severe deformities and a decline in quality of life. At present, intramedullary nailing is regarded as a reliable surgical option for FD patients who have an associated pathological proximal femoral fracture, because it stabilizes the femur, prevents further fractures, and preserves the neck–shaft angle [17]. Ippolito et al [18] contend that intramedullary nailing is the optimal treatment when both the femur and tibia of a child are diffusely affected by FD. Moreover, Yang et al [5] treated a patient with multiple FD and proximal femoral Shepherd’s deformity, pathological femoral shaft fractures, and nonunion using osteotomy and intramedullary nailing, effectively improving the patient’s prognosis. However, although intramedullary nailing can span the entire femur and provide excellent mechanical stability, it is not without drawbacks. First, it offers limited precision in fragment reduction [19]. Second, because the femora of FD patients contain dysplastic bone and abundant vasculature, reaming inevitably damages these tissues, increasing intraoperative blood loss and surgical risk [11,20]. Finally, intramedullary nails are prefabricated and cannot be easily contoured intraoperatively, and the distorted femoral anatomy in FD markedly increases operative difficulty [12]. Considering the severe deformity in this case and the high risk associated with intramedullary nail insertion, we elected to use a bridging combination internal fixation system, which offers several advantages [21]: (1) small incisions reduce blood loss and operative time, facilitating early recovery; (2) the construct provides high stability – its clamp-and-rod design can be locked in multiple planes to create a “3-dimensional spatial fixation” that effectively resists torsion and shear forces, yielding a low rate of loss of reduction; (3) the system can be readily contoured to match the patient’s individual bone morphology, ensuring intimate implant-bone contact and markedly diminishing surgical difficulty. (4) More importantly, traditional large plates have a load-shielding effect, which may hinder bone healing, especially in cases of poor-quality bone. In contrast, this system uses a multi-level, skip-pattern screw arrangement to provide a load-sharing effect, allowing the bone to bear physiological loads, thus promoting bone remodeling and healing. This is particularly crucial for patients with FD who have poor-quality bone. After a 6-month follow-up, the patient’s prognosis was found to be highly favorable, further confirming the appropriateness of our chosen approach.

Although this case demonstrates favorable short-term outcomes, it is important to acknowledge the limitations inherent in our report. First, the report concerns only a single case with a follow-up period of just 6 months. Since FD is a chronic condition, long-term outcomes such as implant failure, disease progression, and the need for revision surgery remain unknown. Second, there is no comparison with other techniques in a controlled setting. This limits the ability to draw definitive conclusions about the relative effectiveness of the bridging combination internal fixation system compared to alternative approaches, such as intramedullary nailing or large plate systems. Additionally, this case does not explore in detail the specific anatomical factors that made this patient suitable for the system, but not for an intramedullary nail.

Conclusions

In this report, we used a novel bridging combination internal fixation system to treat a patient with FD of the proximal femur, complicated by a pathological fracture and Shepherd’s deformity. This system provides minimal invasiveness, stable fixation, and easy contouring. At the 6-month follow-up, the fracture had healed well, and the patient’s limb function had recovered satisfactorily. This report suggests it may be a viable treatment option, but further validation through a larger case series is needed.