Treatment of a femoral neck fracture in a patient with dwarfism: a case report

Abstract

Background

Femoral neck fractures in patients with pituitary dwarfism present significant surgical challenges due to anatomical variations, compromised bone quality, and limited therapeutic options. The management of such cases requires careful consideration of both the anatomical constraints of and the potential complications associated with various fixation methods.

Case presentation

This report presents the case of a 30-year-old female with congenital pituitary dwarfism who sustained a subcapital femoral neck fracture following trauma. After suffering a workplace injury due to a fall, the patient experienced left hip pain, limited mobility, and difficulty walking. The patient presented with characteristic features of dwarfism, including diminutive stature (1.2 m), multiple skeletal abnormalities, and significant osteoporosis. X-ray and hierarchical phase-contrast tomography examinations of the left hip joint revealed a displaced subcapital femoral neck fracture with compromised bone quality and a notably narrow medullary cavity. Surgical treatment was subsequently performed on the patient. After the onset of combined spinal-epidural anesthesia, the patient was placed on a traction bed and closed reduction was attempted three times, all unsuccessfully. The direct anterior approach in the supine position was then chosen for open reduction of the left subcapital femoral neck fracture. After surgery, pain relief and treatment to prevent venous thrombosis were provided. A postoperative digital radiography examination of the left hip showed good alignment of the fracture fragments. Two weeks post-surgery, the stitches were removed and the patient was discharged.

Conclusions

This study aimed to fill the gap in the literature on the selection of internal fixation methods for femoral neck fractures in patients with pituitary dwarfism. Compared with the widespread use of three cannulated screws, the femoral neck system (FNS), a type of internal fixation device for treating femoral neck fractures, was chosen for internal fixation within the medullary cavity due to stenosis. This method avoided the need for multiple drillings with guide pins to ensure internal fixation. Although the procedure prolonged the surgery, it provided better stability and compression capability at the fracture site. The outcome showed that the FNS was a better choice for patients with a similar condition.

Background

Dwarfism is a growth and development disorder caused by anterior pituitary growth deficiency due to endocrine, genetic, or nutritional factors. Patients mainly exhibit short stature [1]. Femoral neck fractures in patients with dwarfism are clinically rare, posing significant challenges for orthopedic surgeons due to the short and thin femoral neck, increased epiphyseal exostosis, flexion deformities, and slow fracture healing [2,3,4]. Dwarfism is often associated with reduced bone quality, heightening the risk of osteogenesis imperfecta and avascular necrosis [5]. Additionally, comorbidities such as restrictive lung disease, spinal stenosis, and obstructive sleep apnea complicate anesthesia and perioperative management, increasing the likelihood of surgical complications [6, 7].

Current treatments for femoral neck fractures in patients with dwarfism include conservative approaches such as traction and cast immobilization, which are often ineffective due to alignment challenges. Surgical options are also available, such as internal fixation with cannulated screws or dynamic hip screws. However, implant placement is complicated by altered femoral geometry and inadequate bone healing, increasing the risk of implant failure [8]. In older patients or those with pre-existing joint degeneration, hemiarthroplasty or total hip arthroplasty may be considered. These procedures necessitate custom prostheses due to altered anatomy, and they carry a high risk of complications such as dislocation, nerve damage, and prosthesis loosening [9]. External rotation intertrochanteric osteotomies are also an option to correct deformities and preserve the femoral head. However, complex bone structure and lower healing capacity make postoperative recovery unpredictable [10].

Femoral neck fractures in patients with dwarfism are relatively rare in clinical practice. Moreover, treatment is a challenge for orthopedic surgeons because the femoral neck in these patients is slender and short and fracture healing is slow. Furthermore, there is a lack of literature on the selection of internal fixation methods for femoral neck fractures in patients with pituitary dwarfism. In response to these challenges, the femoral neck system (FNS), an internal fixation method for a femoral neck fracture, was used on a patient with dwarfism as shown in this case report. The aim in using this method was to guide other orthopedic surgeons in exploring more choices for internal fixation methods when faced with a similar case.

Case presentation

History: A 30-year-old woman with congenital pituitary dwarfism slipped and fell at her workplace and immediately felt pain in her left hip. After experiencing subsequent difficulty in standing and walking, the patient went to the hospital for treatment.

Physical examination: There was no obvious swelling of the left hip, but pressure pain at the midpoint of the left groin was obvious. In addition, the left hip joint showed limited flexion, and a subsequent Patrick test was positive. The fourth fingers of both hands were developmentally malformed, with palpable shortening of the fourth metacarpal bone, deviation of the fourth metacarpophalangeal joint at the proximal end, and relative shortening of the fourth finger as a whole. The fourth toes of both feet also had developmental deformities. While the proximal phalanges were palpable, the middle and distal phalanges were undeveloped and the distal end formed a soft tissue mass. All phalanges exhibited normal skin color and adequate vascular perfusion. The patient’s height was about 1.2 m, there were no obvious abnormalities in the neurological examination as her intelligence was normal, and she was able to move around during the day.

Radiological examinations: A hierarchical phase-contrast tomography (HiP-CT) (see Fig. 1) revealed a left subcapital femoral neck fracture, with embedded bone fragments and swelling of the surrounding soft tissues, and a lumbosacral displaced vertebra (Castellvi type IIa). Pelvic digital radiography (DR) also showed a left subcapital femoral neck fracture (see Fig. 2).

Fig. 1

HiP-CT scan shows the left subcapital femoral neck fracture and narrow pulp cavity

Fig. 2

Pelvic DR shows the left subcapital femoral neck fracture

Diagnosis

(1) Fracture of the left femoral neck; (2) congenital scoliosis; (3) congenital sacralization of the fifth lumbar vertebra; (4) developmental deformity of the fourth digits of both feet; (5) congenital shortening deformity of the fourth fingers of both hands; (6) osteochondroma of the proximal left tibia; (7) right kidney cysts; (8) congenital absence of a uterus; (9) bilateral emphysema; and (10) congenital pituitary dwarfism.

Case characteristics. The patient had a femoral neck fracture with an intercalated and displaced fracture end, indicating that surgical treatment was required. The characteristics of this case were as follows:

• 1. A subcapital femoral neck fracture was accompanied by rotational displacement of the femoral head during closed reduction, which would be difficult to correct through closed reduction.

• 2. The anatomical structure of the patient with pituitary dwarfism complicated the femoral neck fracture in that it was similar to that of a child, with a narrow femoral bone marrow cavity [11].

• 3. HiP-CT and X-ray examinations showed that the patient had obvious osteoporosis.

• 4. The patient’s blood volume was similar to that of a child. This could exacerbate the risk of surgery, so bleeding would need to be minimized during surgery [12].

Treatment plan. The patient’s treatment plan was as follows:

• 1. Internal fixation was the preferred treatment for the displaced subcapital femoral neck fracture.

• 2. After admission, the patient was treated with left lower-limb immobilization,

pain relief, and prevention of venous thrombosis.

3. An examination was conducted and the patient’s physical condition was assessed to rule out surgical contraindications.

Preoperative plan. The patient’s preoperative plan was as follows:

• 1. If two or three attempts at closed reduction were unsuccessful, a minimally invasive open reduction approach would be selected to minimize intraoperative bleeding.

• 2. Most scholars still recommend the use of three hollow screws to fix the broken ends of a fracture. However, since the femoral neck pulp cavity was narrow in this patient, it would be difficult to implant more than two hollow screws with a diameter of 7.3 mm, which is typically used for an adult femoral neck fracture. Theoretically, 3.5-mm hollow screws, which are commonly used in children, could be used to fix the fracture. However, the following challenges had to be considered: (a) it would be difficult to place the screws because the entry pin would need to be adjusted repeatedly; and (b) because the patient had osteoporosis, even if the screws were successfully implanted, screw loosening and withdrawal were very likely, resulting in a fracture that was not effectively fixed and slow bone healing.

• 3. Regarding the possibility of joint replacement, the customization of the prosthesis would have resulted in high costs.

• 4. The direct anterior approach (DAA) was chosen for open reduction, which had the advantage of being minimally invasive, with nominal bleeding and damage to the surrounding muscles.

• 5. The FNS was chosen for the internal fixation of the femoral neck fracture.

Surgical procedures. The surgical procedures were as follows:

• 1. After the onset of combined spinal-epidural anesthesia, the patient was placed on a traction bed and closed reduction was attempted three times, all unsuccessfully.

• 2. After failure of the closed traction procedure, an anterolateral incision (via the DAA) was made in the left hip. The skin, subcutaneous tissue, and deep fasciae tissue were incised, separating the tensor fasciae latae muscle from the sartorius muscle, to expose the Hunter’s canal and the femoral head and neck.

• 3. After anatomical repositioning of the fractured ends of the femoral neck, it was temporarily immobilized using Kirschner wire (K-wire).

• 4. The entry pin was placed at the projected level of the lesser trochanter. A 130° guide along the femoral neck was inserted. According to the guidance device, the guide pin was drilled toward the femoral head. Using a C-arm X-ray machine, the guide was adjusted so that the guide pin could be inserted into the center position of the femoral neck in positive and lateral positions away from the subchondral bone. At the entry point of the hollow secondary pin guide, a 4-cm incision was made to reveal the lateral wall below the greater trochanter layer by layer. After drilling the hole along the guide pin, the bolt-bone plate component was inserted into the femoral head. Subsequently, the bone plate screws and anti-rotation screw were locked in the appropriate positions. The C-arm X-ray machine confirmed that the internal fixation position was appropriate.

Perioperative management plan. The patient’s perioperative management plan was as follows:

• 1. Cefuroxime was used for perioperative infection prevention (1.5 g ivgtt once 30 min before surgery and 1.5 g ivgtt 24 h after surgery).

• 2. Abduction of the left lower limb was prevented by keeping it in a neutral position. The quadriceps muscle of the thigh was exercised two days after surgery.

• 3. Pain relief and treatment to prevent venous thrombosis were provided.

• 4. Two weeks post-surgery, the stitches were removed and the patient was discharged.

Follow-up procedures. These were conducted on the patient one month after discharge to her hometown. The DR of the left hip joint was re-examined to evaluate the healing of the fracture and whether the internal fixation was loose (see Fig. 3).

Fig. 3

DR of the left subcapital femoral neck fracture one month post-surgery

The patient walked with crutches to aid in bearing weight on the left lower limb. The patient showed no signs of infection in the left hip and no complications, such as deep vein thrombosis, in the left lower limb. According to the telephone follow-up four months post-surgery, the patient’s left hip was no longer painful and she could walk normally. Ten months post-surgery, the patient’s DR examination at the local hospital showed that the left subcapital femoral neck fracture had healed.

Discussion and conclusions

A femoral neck fracture in a person with pituitary dwarfism is relatively rare in clinical practice, and there is a lack of clinical experience in the diagnosis and treatment of such patients. Currently, there are no generally accepted choices for the treatment of a femoral neck fracture in those with pituitary dwarfism due to the conditions of a short femoral neck and osteoporosis. Among the treatments available, including the closed traction method, surgical treatment, and internal fixation, the goal of treatment remains the same: to achieve fracture healing and anatomical reduction [13]. At the same time, intraoperative bleeding must be minimized during surgery. Therefore, during the patient’s operation as reported in this case, closed traction reduction in a fracture traction bed was performed three times. After failing to achieve reduction, refractory femoral neck fracture surgery was considered, with open reduction and internal fixation as the chosen procedures.

In terms of surgical treatment, the DAA [14] was selected, which exposed the hip joint between the sartorius muscle and the tensor fasciae latae muscle and had the advantage of not cutting through any muscle. This was a minimally invasive approach that entered between the muscle space, effectively reducing local muscle damage and intraoperative bleeding.

In terms of the selection of surgical internal fixation, the diameter of the femoral cervical medullary cavity was narrow, making it impossible to place more than two conventional size (7.3 mm) hollow screws. It was also difficult to control the rotation of a single hollow screw. Using two or three hollow screws with a smaller diameter would still be difficult because the pin path would have to be adjusted multiple times, increasing the number of C-arm fluoroscopy images and operating time. Thus, the treatment plan for femoral neck fractures in children was applied. A small-diameter hollow screw with K-wire was selected. However, because the patient also had osteoporosis, not enough pressure could be applied to compress the fracture. It was also more likely that the screw would eventually loosen and fail to fix the fracture. Different from a pediatric femoral neck fracture, the fracture healing time of this patient would be longer, requiring long-term bed immobilization and no early functional exercise. One study [15] reported that a patient with dwarfism and a femoral neck fracture suffered an internal fixation fracture after being fitted with three 3.5-mm hollow screws and getting out of bed to walk.

Compared with three hollow screws as the internal fixation method, which is the most common fixation method for femoral neck fractures, the FNS is a new type of proximal femoral anti-rotation nail based on the principles of biomechanics and anatomy. The primary advantage of the FNS lies in its unique anti-rotation design, which effectively prevents rotational displacement of the fracture. It can also be affixed to the femoral shaft with an external steel plate and integrated with anti-rotation screws and locking nails to enhance the biomechanical stability of the femoral neck and shaft [16, 17]. Another advantage of the FNS is its dynamic sliding design. This allows pressure to be applied to the fracture site during surgery and causes a slight sliding of the fracture site to promote fracture healing during postoperative recovery [18]. Studies have shown that compared with cannulated compression screws, the FNS significantly reduces surgical steps, operation time, and C-arm fluoroscopy image frequency. Therefore, it can improve surgical efficiency [19] and provide a more stable fixation effect.

In this case report, the FNS ensured that the secondary guide pin was located in the center of the femoral neck so that there was enough space for the fixation screw and the tension screw to be placed safely. As a result, there was no need to adjust the position of each guide pin multiple times to place the cannulated screws, which reduced the number of intraoperative C-arm fluoroscopy images. At the same time, this achieved compression of the broken ends of the fracture, which helped the fracture to heal.

This study aimed to fill the gap in the literature on the selection of internal fixation methods for femoral neck fractures in patients with pituitary dwarfism. In this case report, the FNS was chosen for fracture fixation, which avoided the difficulty of inserting an undesirable amount of hollow screws. The use of smaller and fewer screws and K-wire led to the loosening of the screws and retraction, while at the same time allowing pressure to be applied on the broken ends of the fracture with good results. The outcome showed that the FNS was a better choice for patients with pituitary dwarfism suffering from a femoral neck fracture.