| disease | Osteochondrosis of the Epiphysis and Apophysis |
| alias | LCP |
Legg-Calve-Perthes disease (LCP), commonly referred to as Perthes disease, is the most common osteochondrosis. It predominantly affects children aged 3 to 10 years, with a higher incidence in boys than girls, at a ratio of 4–6:1. Occasionally, cases may occur in children under 2 years or over 10 years of age. Bilateral involvement is seen in about 10% of cases, and the disease course typically lasts 2 to 4 years. This condition is characterized by ischemic necrosis of the epiphysis, primarily affecting the femoral head epiphysis and the metaphysis of the femur, with occasional involvement of the acetabulum.
bubble_chart Clinical Manifestations
Initial stage [first stage] Symptoms are relatively vague, with limb fatigue often being the earliest symptom. There is grade I pain in the hip during weight-bearing, but it disappears after rest, accompanied by subtle limping. Hip abduction and rotation are affected early on, and pain can be felt when tapping the hip along the long axis of the femur. There is tenderness in the anterior hip, and the pain radiates to the knee joint, leading to misdiagnosis as a knee disorder.
As the condition progresses, the pain becomes persistent. The child exhibits obvious limping, and the gluteal and thigh muscles develop disuse atrophy. The Trendelenburg test is positive, and hip flexion with varus deformity causes relative shortening of the affected limb. With the formation of a flat hip, the absolute length of the limb also becomes shorter than that of the healthy side. In adulthood, this leads to early-onset osteoarthritis.
In the initial stage of the disease, X-rays show no positive findings. The early radiographic manifestations of femoral head osteoepiphysio-chondropathy include lateral displacement of the ossification center of the femoral head and widening of the medial joint space (a widening of even 1–2 mm has diagnostic value and can be compared with the unaffected side). This is caused by increased intra-articular pressure due to synovitis and swelling of the joint capsule's fat pad. Some believe the lateral displacement is due to the ossification center moving outward rather than the entire femoral head shifting. After the femoral head displaces laterally, the anterosuperior quarter inevitably bears excessive load, and the acetabular rim continuously compresses the femoral head, leading to marginal compression fractures. These are more clearly visible on X-rays taken in the hip abduction position (frog-leg position), prompting some to emphasize the routine use of abduction views. Arthrography may reveal thickening of the medial cartilage of the femoral head, likely due to proliferation of cartilage cells on the medial side as the ossification center stops developing. The ossification center also appears smaller on X-rays, with increased epiphyseal density and temporary developmental arrest. Later, a dome-shaped subchondral lucency appears in the femoral head, visible only on abduction X-rays, representing the fracture line of the necrotic area. When the lower limb is abducted, the volume between the ossification center's edge and the epiphyseal cartilage suddenly increases, slightly separating bone fragments and allowing air to enter the fracture line, making it visible—this is also called the intra-epiphyseal gas sign. The anterolateral portion of the epiphysis is the first to undergo necrosis (and the first to show repair), and this is only clearly visible in abduction views, whereas anteroposterior X-rays often misleadingly suggest whole femoral head involvement. The femoral head begins to flatten, the metaphysis thickens, and disuse osteoporosis appears in the hip bones. Subsequently, the repair process begins, with radiographic signs of bone necrosis, bone resorption, and new bone deposition coexisting. The femoral head gradually regains its smooth contour, but if timely and effective treatment is not administered, it may become mushroom-shaped by this stage. To accommodate the deformed femoral head, the acetabulum also flattens and becomes shallow with an irregular shape. The acetabulum fails to fully contain the femoral head, leading to subluxation, while the femoral neck becomes broad and short. Due to changes in the weight-bearing line, early signs of osteoarthritis may appear in adulthood. In recent years, the widespread clinical use of CT and MRI (magnetic resonance imaging) has greatly aided the early diagnosis of this condition.
bubble_chart Treatment MeasuresTreatment Measures
At the onset of the disease, since the child's hip joint is highly sensitive, skin traction can be applied for 1–2 weeks first. After the acute symptoms subside, further treatment can be considered.
(1) Non-surgical Treatment: In the past, long-term hip spica cast fixation was used, but due to its significant impact on child development and joint function, it is now rarely or no longer employed. Various types of abduction braces are currently the commonly adopted treatment methods, aiming to: (1) deeply position the femoral head within the acetabulum; (2) avoid compression of the femoral head by the acetabular labrum; (3) ensure even pressure distribution on the femoral head; (4) maintain good mobility of the hip joint; and (5) preserve the round shape of the femoral head and the normal structure of the acetabulum as much as possible. In one group of 68 cases treated with abduction and internal rotation brace fixation, the excellent and good rate reached 91%, but the average fixation duration was 19 months, which is still too long.
(2) Surgical Treatment: Attempts have been made to alter the circulation of the femoral head ossification center through surgical methods, such as drilling, bone graft insertion, or establishing blood supply communication between the femoral head and neck, but these have not yielded effective results. Some advocate synovectomy of the hip joint to treat this condition, which shows certain efficacy, though the mechanism of action remains unclear. Others have used pedicled (muscle flap or vascular) bone grafting, vascular implantation, etc. In recent years, subtrochanteric or intertrochanteric osteotomy has gained relatively widespread recognition abroad. The advantages of this procedure include: (1) treatment completion within 6–8 weeks post-surgery; (2) no need for further bracing or other activity and weight-bearing restrictions post-surgery; (3) induction of hyperemia in the upper femur by osteotomy; and (4) efficacy comparable to long-term abduction brace fixation without being inferior. Complications of osteotomy include limb shortening deformity, residual hip subluxation, nonunion at the osteotomy site, and restricted joint mobility. Generally, surgery performed before the age of 7 yields better outcomes, with continuous improvement observed in the years following the procedure. The healing process of femoral head epiphyseal necrosis can be shortened. Post-surgery, the affected limb is shortened by an average of 1.4 cm.
The prognosis is related to the age of onset, duration of the condition, and the correctness of the treatment method. Generally, if the disease occurs before the age of 5, the prognosis is good, and in some cases, no treatment may even be necessary.
To assess prognosis and determine treatment methods, Catterall classified the disease into four grades based on X-ray findings (anteroposterior and abduction views). Grade I: Only the anterior part of the epiphysis is affected, with no joint surface collapse. The involved bone can be completely absorbed without necrotic bone formation or metaphyseal bone changes, and the regeneration process can achieve full recovery. Grade II: The anterior and lateral parts of the epiphysis are affected to varying degrees. The femoral head collapses but can still maintain the original height of the epiphysis. Necrotic bone forms but can be absorbed, and cystic changes appear in the metaphysis, which will later disappear. Grade III: Only a small portion of the epiphysis remains non-necrotic. Due to new bone covering the necrotic bone, a "head within a head" appearance is seen on anteroposterior X-rays. The femoral head collapses and can no longer maintain its original height, and the metaphysis has widened. Grade IV: The entire epiphysis has become necrotic, the femoral head takes on a mushroom shape, the metaphysis shows significant widening and other bone changes, and remodeling of the femoral head occurs, though restoration to its original shape is difficult.
There is no doubt that the prognosis for grades I and II is good, while that for grades III and IV is poor. After further research, Catterall also found that some children recover without treatment, while others require timely and correct treatment to avoid serious consequences. He proposed the concept of the so-called "head-at-risk signs." Clinically, these "risk signs" include: obese children, limited hip joint movement with adduction contracture; on X-ray, they include: Gage's sign, lateral subluxation of the femoral head, calcification on the lateral side of the epiphysis, and horizontal growth plate of the epiphysis. If these signs appear, prompt treatment is essential, with intertrochanteric or subtrochanteric osteotomy being the most effective methods. If no "risk signs" are present, regardless of the group, no treatment is necessary.
Femoral head osteoepiphysio-chondropathy needs to be differentiated from the following diseases.
(1) Hip joint subcutaneous node is often difficult to distinguish, especially in the early stages. Hip joint subcutaneous node is a localized, progressive, destructive, inflammatory sexually transmitted disease that can involve the femoral head, acetabulum, and femoral neck. The X-ray sign of joint capsule swelling due to joint effusion can persist for a considerable period of time. In contrast, femoral head osteoepiphysio-chondropathy is a subchondral aseptic necrosis sexually transmitted disease, with the main X-ray manifestations being increased density of necrotic bone, deformation, and secondary hip osteoarthritis, without significant joint effusion or abscess formation.
(2) Transient (temporary) synovitis of the hip joint Both conditions are similar in terms of age of onset and synovitis manifestations, but their courses differ. Transient synovitis has no abnormal X-ray findings. In recent years, 99mTc scanning has been helpful: 99Tc uptake is reduced in femoral head osteoepiphysio-chondropathy.
(3) Cretinism The epiphyseal changes in cretinism can manifest as irregular calcification spots, but their appearance and fusion times are delayed compared to normal children. The long diameter of the bone is shortened due to impaired endochondral ossification. Additionally, the child's intellectual disability and other conditions can help differentiate it.
(4) Slipped capital femoral epiphysis The clinical symptoms of both conditions are similar. However, slipped capital femoral epiphysis occurs in older individuals, and limited internal rotation and adduction of the hip joint (Drehman's sign) are characteristic features.
