9-year-old male obese child presented with bowing deformity of the left knee and length discrepancy, together with pain and tenderness related to abnormal medial prominence at proximal tibia.
9-year-old male obese child presented with bowing deformity of the left knee and length discrepancy, together with pain and tenderness related to abnormal medial prominence at proximal tibia. Plain X-ray & CT of the knee show marked tibial varus deformity with increased metaphyseal diaphyseal angle above 20 degrees in addition to marked irregularity, destruction, fissuring, sclerosis, collapse and deformity of the proximal metaphyseal sub epiphyseal region with multiple air lucencies and marginal peaking.
Blount Disease: The local disturbance of growth of the medial and dorsal segments of the proximal tibial metaphysis and adjacent epiphysis in this condition is also called tibia vara. When the deformity is noted between 1 and 6 years of age, it is termed infantile Blount disease and is six to eight times as frequent as the more severe adolescent type appearing later. It may be unilateral or bilateral. The characteristic radiographic feature is an abrupt lateral bending of the medial cortical wall of the proximal metaphysis of the tibia with a spur and above it a more or less vertically oriented continuation of the superior border of the metaphysis. The medial portion of the epiphyseal ossification center is smaller than the lateral portion, and its superior margins, the future medial portion of the tibial plateau, slopes downward and medially. Blount disease was considered an osteochondrosis (i.e., a result of ischemic necrosis), but the metaphyseal defect is due to replacement of bone by cartilage extending downward from the epiphysis. The condition is differentiated from physiological bowing and bowing of rickets and of metaphyseal chondrodysplasia by the sharp cortical angle, but serial examinations may be necessary to establish the increasing local deformity that is part of the disease. Occasionally, similar deformities can be observed in the opposing femur at the knee.
Adolescent Blount Disease
Based on the provided weight-bearing X-ray and CT images of the lower limb, the following are observed:
1. A prominent medial protrusion and a sharp cortical angle at the medial metaphyseal region near the proximal tibia of the left knee joint;
2. A downward inclination of the medial articular surface of the proximal tibia, with growth disturbance at the medial metaphysis, and visible irregular local bone changes;
3. A certain degree of length discrepancy of the left lower limb compared to the right side;
4. No obvious fracture line or significant soft tissue swelling signs are seen on the images, but corresponding local bone changes are noted at the site of medial pain and tenderness.
These findings are consistent with the characteristic features of Blount’s disease (tibia vara), especially the abnormal bone changes and proliferative alterations at the medial proximal tibial metaphysis.
Given the patient’s age (9 years old), obesity, genu varum deformity, and the imaging findings of a medial proximal tibial metaphyseal lesion, possible diagnoses include:
Considering the patient’s age, obesity, genu varum deformity, localized pain, and the aforementioned radiographic features, the most likely diagnosis is Blount’s disease (tibia vara).
Further confirmation may involve MRI or other evaluations to assess the cartilage and growth plate. If needed, blood tests or bone metabolism-related indicators may be reviewed to rule out rickets or other systemic causes.
1. Treatment Strategy:
· Conservative Treatment: For early-stage or mild deformities, using braces (orthoses) to externally fix the lower limb or limit the varus angle can be considered. Weight control via nutritional management and appropriate exercise is crucial to reduce stress on the knee joint.
· Surgical Treatment: In cases of more severe deformity or unsatisfactory response to conservative therapy, high tibial osteotomy and internal fixation can be considered to correct the mechanical axis and reduce early joint damage.
2. Rehabilitation/Exercise Prescription Suggestions (FITT-VP principle):
· Type of Exercise (Type): Emphasize low-impact activities such as swimming, stationary cycling, and lower limb strength training (seated knee extension/flexion, light weight-bearing, etc.)
· Frequency (Frequency): 3–5 times per week, gradually increasing based on fitness level
· Intensity (Intensity): Primarily low to moderate intensity, monitored by patient feedback and heart rate. If significant pain or increased varus stress occurs, adjust accordingly
· Time (Time): Start with 20–30 minutes each session, increasing to 40–60 minutes as tolerated
· Progression (Progression): Progress gradually with improved joint stability and muscle strength, avoiding excessive joint friction and varus stress
· Volume and Personalization (Volume & Personalization): Under professional guidance, tailor total training volume based on the patient’s weight, muscle strength, joint flexibility, and physical development, regularly evaluating outcomes and adjusting as needed.
3. Special Precautions:
· If the patient experiences pronounced pain, joint instability, or is in post-surgical recovery, rehabilitation should be conducted under the supervision of a professional therapist or exercise specialist;
· Throughout the rehabilitation process, focus on weight management and correction of the knee joint axis, avoiding undue weight-bearing and high-impact activities;
· Periodic follow-up imaging is necessary to evaluate outcomes of osteotomy or brace treatment and to adjust the treatment plan in line with the patient’s growth and development.
This report is based on available imaging and clinical information and is intended for reference only. It cannot replace face-to-face clinical diagnosis or professional medical advice. If you have any doubts or notice changes in condition, please seek timely medical consultation and follow-up care under the guidance of a specialist.
Adolescent Blount Disease
