Aseptic necrosis of the femoral head in children

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Artem Naumenko

This article was written together with Artem Naumenko, chief physician of the MedinUA clinic. 14 years of experience Contact a doctor

Femoral head epiphysiolysis (FEH)

is a pathology that occurs in adolescents and children. For reasons that are still not entirely understood, the head of the femur slips off the neck in the opposite direction. This causes pain, stiffness and instability in the affected limb.

Treatment for SCFE involves surgery to prevent the femoral head from slipping. To achieve the best outcome, it is important to make a diagnosis as quickly as possible. Without early detection and proper treatment, SCFE can lead to potentially serious complications.

Description

SCFE is the most common hip disorder in adolescents. In SCFE, the epiphysis, or head of the femur, slips from the neck of the bone at the growth plate.

SCFE usually develops during periods of rapid growth, shortly after puberty. In boys, this most often occurs between the ages of 12 and 16; in girls aged 10 to 14 years.

Sometimes SCFE occurs suddenly after a minor fall or injury. More often, however, the condition develops gradually over several weeks or months, without any injury.

SCFE is often described based on whether the patient is able to put weight on the affected limb. Knowing the type of SCFE will help your doctor determine the proper treatment.

Treatment[edit | edit code]

Conservative treatment consists of unloading the joint using orthopedic devices, a plaster cast or crutches. Exercises are also prescribed to maintain range of motion in the joint. Sometimes a Petri splint is applied for a while. For Perthes disease type C or B/C in children 8 years of age or older, it is more appropriate to undergo surgery. Children under 8 years of age with type A or B lesions, regardless of treatment tactics, have a favorable prognosis, while children with type C have an unfavorable prognosis. Girls have a worse prognosis than boys.

Types of EGBC include:

Stable EGBC. With stable SCFE, the patient can walk or weight-bear the affected limb, with or without crutches. Most cases of SCFE are stable.

Unstable EGBC. This is a more serious form. The patient cannot walk or put weight on the leg, even with crutches. Unstable SCFE requires urgent treatment. Complications associated with SCFE are much more common in patients with unstable slip.

SCFE usually occurs on only one side of the body; however, in 40 percent of patients (especially those under 10 years of age), SCFE also occurs on the opposite side—usually within 18 months.

Radiation diagnostics

Radiography

It does not have high sensitivity in determining epiphysiolysis.

In the acute stage of proximal epiphysiolysis: widening of the distance between the epiphysis and diaphysis, determined mainly in the lateral sections.

In the chronic stage of epiphysiolysis: sclerosis, subperiosteal cysts, demineralization, fragmentation.

MRI semiotics

T1-WI: expansion of the growth zone, mainly on the lateral side, isointense MR signal.

T2-FS: hyperintense MR signal of an expanded growth zone with adjacent hyperintense trabecular edema.

Symptoms

Symptoms of SCFE vary depending on the severity of the condition.

A patient with mild or stable SCFE will usually experience intermittent pain in the groin, knee, and/or hip over several weeks or months. This pain usually worsens with physical activity. The patient may limp after a period of activity.

In more severe or unstable forms of SCFE, symptoms may include:

• Sudden onset of pain, often after a fall or injury
• Inability to walk or put weight on the leg
• Outward rotation (external rotation) of the affected leg
• Leg length discrepancy—the affected leg may appear shorter than the opposite leg

During the exam, your doctor will ask about your child's general health and medical history. He will then talk to you about your baby's symptoms and ask when the symptoms started.

Treatment

The goal of treatment is to prevent slipping of the displaced femoral head. Surgery is always indicated.

Early diagnosis of SCFE provides the best opportunity to stabilize the hip joint and prevent complications. With timely and appropriate treatment, limb function can be expected to be unaffected.

Once SCFE is confirmed, your child will not be allowed to put any weight on the injured limb and will likely be hospitalized. In most cases, the operation is performed within 24-48 hours.

Juvenile epiphysiolysis of the femoral head

Juvenile epiphysiolysis of the femoral head is a pathology in which the epiphysis is completely or partially separated from the rest of the bone in the projection of the growth zone. Occurs during puberty against the background of endocrine disorders. Less commonly observed in chronic renal failure, after radiotherapy, or develops idiopathically. It manifests itself as increasing pain, which is subsequently accompanied by limitation of movements, lameness and increased fatigue of the limb. As a result, a contracture is formed. The diagnosis is made taking into account complaints, examination data and X-ray results. Surgical treatment – ​​open osteosynthesis, osteotomy, allo- or autoplasty.

The incidence is estimated to be 10 per 100,000 people, but it varies by race and geographic area. The incidence is known to affect children aged 9–16 years with bilateral involvement in up to 50% of patients. In most cases, the cause of SCFE is unclear, but risk factors include male gender, endocrine disorders, and mechanical stress due to obesity, femoral retroversion, and a tendency toward oblique growth plate projection.

Symptoms

Due to the nonspecificity, mild severity of symptoms and the low prevalence of pathology, the early stages of juvenile epiphysiolysis often remain undiagnosed.

Patients complain of intermittent pain in the hip or knee joint, which bothers them for several weeks or months. Gait is impaired and lameness is noted. In severe cases, the patient is unable to bear the weight of the entire body on the affected limb. The affected limb is slightly turned outward compared to the healthy leg. The length of the affected limb decreases by 2-3 cm.

Treatment should begin as early as possible. Surgery is often scheduled 24-48 hours after diagnosis. Early diagnosis of femoral head epiphysiolysis provides the best chance of achieving the treatment goal (stabilization of the hip joint).

Complications

The main complication of the disease is early severe arthrosis of the hip joint. Limitation of mobility caused by juvenile epiphysiolysis and progressive degenerative changes in the joint, as well as impaired support on the leg, cause disability in patients.

Diagnostics

Damage to the femoral head is diagnosed by orthopedic traumatologists based on complaints, the results of an objective examination and imaging techniques. The main method of examination is radiography of the hip joint. The procedure is performed in 2 projections; the lateral projection is the most informative. Changes depend on the stage of the disease.

First, the growth cartilage expands on x-rays, the neck becomes layered and spotted due to alternating areas of osteosclerosis and osteoporosis. Then a progressive displacement of the head is detected, after which the fracture line is visible. At the final stage, signs of fracture consolidation, remodeling of the femoral neck, and narrowing of the joint space are revealed.

X-rays are complemented by computed tomography of the hip joint, which is performed to detail pathological changes and assess the viability of the femoral head. Patients are prescribed a consultation with an endocrinologist and additional studies to diagnose hormonal disorders. Differential diagnosis of juvenile epiphysiolysis is carried out with Perthes disease.

Treatment

Standard treatment involves in-situ threading of the femoral head; thus stabilizing the femoral head and causing physiological growth to stop. This prevents any further displacement as a result of the non-anatomical position, limiting further femoral neck growth and remodeling. This results in a shortened femoral neck, decreased hip offset and shortened lever arm for the abductors, and an increased risk of femoroacetabular impact.

The Free Gliding Screw System for SCFE with its telescopic design was created to prevent or stop further displacement of the femoral head in children with open growth plates without affecting normal growth of the proximal femur. There is limited evidence in the literature regarding fixation in SCFE that allows the femoral neck to continue to grow; in addition, to date there have been no clinical studies evaluating the results of the FG screw. Therefore, we designed a study to analyze the growth and remodeling of the femoral neck after in-situ growth screw fixation for the treatment of SCFE.

Surgical techniques that stabilize the SCFE and prevent further displacement while still allowing continued growth are preferred. In fact, this approach has been successfully tried in Scandinavia using the Hansson rod, in Germany using Kirschner wires, and in North America using cannulated screws (Depuy-Synthes) leaving them on the surface.

Results from a recent 3-year follow-up study of 54 children treated with Hansson pins show stabilization of the SCFE without further displacement, allowing femoral neck lengthening of up to 20 mm, and reconstruction with improvement in the alpha angle to a mean of 14.5°. The results also show a positive correlation between alpha angle and femoral neck height.

Disadvantages of current non-fusion technologies that allow further growth include the need to place implants on the cortex and the need for revision surgery to replace implants once they have outgrown.

The innovative Pega Medical Free-Gliding (FG) screw for SCFE treatment overcomes these limitations with a modular telescopic design. The two-part device includes a proximal filament component located entirely within the epiphysis and a female member that interfaces with the lateral cortex.

Radiographic analysis shows that the FG screw prevents further displacement and premature closure of the lamina physis, allowing growth to continue. More importantly, thanks to the modular telescopic design, the implant does not need to be left in place or replaced as the child grows. Results from a recent study, a two-year follow-up of 58 SCFE patients treated with FG screw implantation, show an average increase in length of 7.7 mm and an average improvement in alpha angle of 6.9°. The results indicate that the remaining growth accounts for femoral neck remodeling, anatomical misalignment of the hip joint, and a reduction in the risk associated with SBVS.

The Pega Medical FG Screw is a new non-fusion approach to SCFE treatment that avoids the need for protruding implant placement. The FG screw has been shown to prevent further displacement while not inhibiting growth and promoting remodeling, which is important in reducing the risk of limb length discrepancy and femoroacetabular impingement, and in preventing the development of early osteoarthritis.

Growth and remodeling of the femoral neck after fixation in place of a screw construct allowing joint growth.

Ashlee Dobbe FRCSC; David G. Little MBBS; Oliver Birke MD; Paul Gibbons

Westmead Children's Hospital, Westmead, New South Wales, Australia

The purpose of this study is to analyze the growth and remodeling of the femoral neck after in-situ screw fixation in the treatment of SCFE with the possibility of joint growth.

Methods: We conducted a retrospective study of 42 patients who underwent in-situ fixation using the PEGA Medical Free Gliding SCFE screw between 2015 and 2021. Radiographs at 6 weeks, 3 months, 12 months, 24 months, and growth plate closure were reviewed. Radiographs were evaluated for posterior angulation (PSA), screw length change, alpha angle (α-angle), femoral neck inclination (NSA), femoral head displacement (HNO), and articular-trochanteric distance (ATD).

Results: A total of 58 hips from patients with a mean age of 11.2 years were reviewed. 39 patients were treated for SCFE, and the remaining 19 were treated prophylactically. There was a mean increase in screw length of 7.69 mm (P < 0.001). HNO increased by an average of 9.64 mm (p = 0.002). Alpha angle improved by an average of 6.89 degrees (P0.001). ATD remained positive with an overall trend toward a mean increase of 1.28 mm (P = 0.4).

Conclusions: Change in screw length, positive ATD, preserved HNO, and trend toward improvement in alpha angle indicate that the PEGA Free Gliding SCFE Medical Screw promotes continued femoral neck growth. Further research is needed to evaluate the correlation of femoral neck growth and improvement in femoral neck remodeling, and to identify the patient population and severity of malalignment that are most likely to benefit significantly.

Significance: The positive correlation observed between screw length change, HNO, and ATD demonstrated that remaining growth accounts for femoral neck remodeling and enables the joint to achieve optimal/near-anatomic hip alignment and reduces the risk of femoroacetabular impingement.

Procedures

The surgical procedure will depend on the severity of the slip.

Treatments used to treat SCFE include:

• Fixation in the place of initial localization. This procedure is used most often for patients with stable or mild SCFE. The doctor makes a small incision, then inserts a locking screw through the growth plate to maintain the position of the femoral head and prevent further slipping.
• Open reduction. For patients with an unstable SCFE, the physician may first make an incision in the femur and then carefully reset the femoral head to its normal anatomical position.
• The doctor then inserts one or two metal screws to secure the bone until the growth plate closes. This is a more complex procedure and requires more recovery time.

Complications

Although early diagnosis and proper treatment of SCFE will help reduce the likelihood of complications, problems may persist for some patients.

Aseptic necrosis

In severe cases, SCFE leads to limited blood supply to the femoral head. This can lead to gradual and very painful bone destruction, a condition called avascular necrosis or osteonecrosis.

When bone breaks down, the articular cartilage covering the bone also breaks down. Without this smooth cartilage, bone rubs against bone, leading to arthrosis in the joint. Some patients may require additional surgery to reconstruct the hip.

AN is more common in patients with unstable SCFE. Because signs of AN may not be visible on x-ray until 12 months after surgery, the patient will undergo x-ray examination during this time period.

Chondrolysis

Chondrolysis is a rare but serious complication of SCFE. In chondrolysis, the articular cartilage on the surface of the hip joint degenerates very quickly, resulting in pain, deformity, and loss of mobility in the affected hip.

Although the cause of this condition is not yet fully understood by doctors, it is believed that it may be the result of inflammation in the hip joint.

Intensive physical therapy and anti-inflammatory medications may be prescribed for patients who develop chondrolysis. Over time, there may be a gradual return of hip mobility.

Statistics

Epiphysiolysis accounts for 15 to 30% of all childhood fractures. These fractures are a medical emergency because they can cause bending and differences in limb length.

Fracture healing occurs faster in children than in adults.

A pediatric orthopedic surgeon who performs the appropriate examination will help determine the nature of the growth plate injury, select the appropriate treatment method, and schedule follow-up to evaluate the recovery process.

Fractures in the area of ​​the growth plate are common, but they usually do not pose a serious problem. Bone deformation accompanies epiphysiolysis only in 1-10% of cases.

Recovery

Load on the leg

After surgery, your child will walk on crutches for several weeks. Your doctor will give you specific instructions about when you can start putting full weight on your leg. To prevent further injury, it is important to follow your doctor's instructions carefully.

Physiotherapy

The physical therapist will provide specific exercises that will help strengthen the muscles of the thigh and lower extremity and improve range of motion.

Sports and other activities

Your child will not be allowed to participate in active sports or activities for some time after surgery. This will help minimize the likelihood of complications and allow for healing. Your doctor will tell you when your child can safely resume normal activities.

Further care

Your doctor will schedule a follow-up appointment within 18 to 24 months after surgery. These visits may include x-rays every 3 to 4 months to ensure that the growth plate is closed and no complications have arisen.

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Classification of epiphysiolysis

Currently, several classification systems have been developed. The most common system is probably the Salter-Harris classification.