Clinical presentation of Perthes disease
The disease begins gradually. In childhood, the pathology is classified as osteochondropathy of the epiphyses of tubular bones — Legg-Calvé-Perthes disease. Laboratory data are non-specific, and the pain syndrome is atypical.
Main clinical manifestations:
- Rapid fatigue when walking.
- Moderate pain in the hip joint. Important feature: pain often radiates to the knee joint area on the affected side.
- Appearance of a limp (including intermittent claudication).
- Limitation of hip abduction.
- Visual atrophy of the thigh and gluteal muscles.
- Shortening of the affected limb.
It is critically important to identify the disease at an early stage. In the upright position, the femoral head experiences immense stress, which, given the onset of necrosis, creates a high risk of developing severe secondary deformations.
Five stages of pathological development
The process of destruction and subsequent restoration of bone tissue takes several years and goes through strictly defined stages:
- Pre-radiological stage (aseptic necrosis). Lasts up to 6 months. The spongy substance is affected (osteoporosis stage), but the articular cartilage remains intact.
- Stage of sclerosis (pathological fracture). Takes from 3 to 6–8 months. At this stage, distinct radiological signs appear — the femoral head begins to flatten.
- Stage of fragmentation (resorption). Lasts 1–1.5 years. Revascularization occurs: blood vessels and connective tissue grow into the affected zone. Old bone is resorbed while new bone is simultaneously formed.
- Stage of repair. Sequestered shadows on images disappear. The necrotic tissue is completely replaced by newly formed bone (with areas of radiolucency).
- Final stage (secondary changes). The shape and structure of the affected area are restored to the characteristics of mature bone.
Diagnosis and outcome variants
Since plain radiography does not reveal bone pathology in the first stage, at the slightest clinical suspicion, high-resolution methods must be used: CT, MRI, scintigraphy, or densitometry.
Disease outcomes depend on the timeliness of treatment:
- Ideal: complete restoration of joint anatomy (extremely rare).
- Favorable: anatomical characteristics are as close to normal as possible.
- Unfavorable: the femoral head acquires a pathological mushroom-like shape. In the future, this inevitably provokes degenerative processes and the development of deforming arthrosis.
Aseptic necrosis as a complication of fractures
In adults, aseptic necrosis of the femoral head is often the consequence of trauma, particularly transcervical femoral neck fractures. The risk of necrosis development directly depends on the chosen treatment tactics.
Risk factors and prevention:
- The later osteosynthesis surgery is performed and the longer fragment displacement persists, the more severely the blood supply to the head is disrupted.
- Open osteosynthesis (with joint opening) is more traumatic and more often leads to necrosis. In elderly patients in such cases, arthroplasty is preferred.
- To prevent fracture disimpaction and the development of necrosis, a conservative approach is used: immobilization on a Böhler splint and skeletal traction through the tibial tuberosity with a small weight (2–3 kg). The use of heavy weights is strictly contraindicated.
Rehabilitation: Exercise therapy is prescribed from the first days. Traction is removed after 1.5–2 months, after which walking on crutches without weight-bearing on the affected leg is permitted. Gradual weight-bearing is introduced at 3–4 months. Full weight-bearing is allowed no earlier than 6 months — this is critically important for the prevention of avascular necrosis.
To memorize the 5 stages, use the abbreviation NSFRV: Necrosis (pre-radiological), Sclerosis, Fragmentation, Repair, Restoration (final).
Class and exam questions
Why do X-rays fail to show pathology in the early stages?
In the first months (up to half a year), only the spongy substance is affected, while the cartilage remains intact. Detecting the disease during this period requires MRI, CT, or scintigraphy.
Where can pain radiate when the hip joint is affected?
Pain often radiates to the knee joint area on the affected side, which can misdirect the diagnostic process.
How to prevent femoral head deformation in the treatment of fractures?
Early axial load must be avoided. Patients are prescribed walking on crutches without bearing weight on the affected leg, and full weight-bearing is allowed no earlier than 6 months later.
What else to study on this topic
- Osteochondropathy of the tibial tuberosity (Osgood-Schlatter disease)
- Köhler disease I and II (involvement of the navicular and metatarsal bones)
- Conservative and surgical treatment of transcervical femoral fractures
- Aseptic necrosis of the lunate bone (Kienböck's disease)
- Specific complications of carpal bone fractures
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