1. Imaging Findings

Based on the patient’s X-ray, ultrasound, CT, and MRI images, the following characteristics can be observed:

• X-ray: Mild local soft tissue swelling near the ankle joint and potential signs of bone destruction (e.g., focal decreased bone density, blurred margins, or slight periosteal reaction).
• Ultrasound: Shows edema in the subcutaneous tissue and adjacent muscles, along with periosteal thickening. A fluid hypoechoic area adjacent to the bone cortex may indicate an abscess or effusion.
• CT: Local cortical bone destruction and periosteal reaction are visible, with a round or irregular low-density area in the bone suggesting a “cavitary” change consistent with Brodie’s abscess; mild to moderate edema or low-density shadows may also be seen in the soft tissues.
• MRI: Abnormal bone marrow signals in the lesion region. On T1-weighted images, the signal is low, while on T2 and STIR sequences, the signal is high. After contrast enhancement, a ring-enhancing pattern is noted, suggesting a localized abscess within bone or soft tissues and inflammatory reactions around necrotic areas.

2. Potential Diagnoses

Based on the imaging findings and the patient’s history (14-year-old adolescent, persistent local pain and swelling with mild redness after trauma, but no significant systemic fever), the following diagnoses should be considered:

• Subacute Osteomyelitis (Brodie’s Abscess): Caused by bacterial infection leading to osteomyelitis, but with atypical clinical presentation. Imaging often shows one or multiple low-density/low-signal lesions, with possible calcification or periosteal reaction. The patient’s age and local symptoms fit a subacute infectious process.
• Ewing's Sarcoma, Osteoblastoma, or Other Malignant Bone Tumors: Although these malignancies frequently present with more pronounced pain, bone destruction, and soft tissue masses, they must still be considered when focal bone lesions are identified. However, the imaging findings here are more indicative of an infectious lesion, making malignancy less likely.
• Chronic Osteomyelitis: A long-standing infection can lead to bone destruction and the formation of sequestra, but the patient’s one-month course suggests a subacute phase. Moreover, chronic osteomyelitis often features sinus tracts, sequestra (dead bone), and involucrum (new bone shell).

3. Final Diagnosis

Considering the patient’s age, history of trauma, clinical presentation (local swelling and pain, mild redness without significant systemic fever), and imaging findings (focal bone lesion, periosteal reaction, deep soft tissue edema, ring-enhanced areas on MRI), the most likely diagnosis is:

Subacute Osteomyelitis, with or without Brodie’s Abscess.

To confirm the diagnosis and identify the pathogen, further laboratory tests (e.g., complete blood count, C-reactive protein, ESR, and pathogen culture) are usually required. A biopsy or surgical exploration may be necessary as well.

4. Treatment Plan & Rehabilitation

• Medication and Conservative Treatment:
  • Antibiotic therapy based on pathogen sensitivity is the first choice, typically requiring a long course of treatment (4–6 weeks or longer).
  • If a significant abscess or bone cavity is present, local drainage or surgical curettage may be necessary.
• Surgical Indications:
  • If the lesion is large, with notable bone destruction or poor response to conservative management, surgical intervention is warranted (removal of necrotic bone and abscess, possibly with bone grafting).
• Rehabilitation / Exercise Prescription:

  The core goal of rehabilitation is to facilitate recovery of the affected limb while preventing joint stiffness and muscle atrophy, ensuring bone healing and overall safety:

  • Acute Phase (Early Stage, 2–4 weeks): Focus on immobilization or partial weight bearing, along with mild exercises:
    • Ankle joint flexion and extension: 2–3 times daily, 10–15 repetitions each.
    • Isometric muscle exercises: Under physician or therapist guidance, perform isometric contractions of the quadriceps and gastrocnemius, 2–3 sets per day, holding each contraction for 6–8 seconds.
  • Subacute Phase (Middle Stage, 4–8 weeks): Once the condition stabilizes and pain subsides, gradually increase weight bearing and the range of joint movement:
    • Water-based exercises: If available, perform ankle and knee flexion/extension or light stepping in shallow water for about 15–20 minutes, 2–3 times per week.
    • Low-intensity aerobic exercise: For example, use a stationary bike on light resistance for 10–15 minutes, 2–3 times per week.
  • Strengthening Phase (Late Stage, 8 weeks and beyond): After the bone infection is largely controlled and bone healing appears good, gradually return to regular physical activities:
    • Functional strength training: Use resistance bands or light weights to target ankle and calf musculature (e.g., presses, heel raises, ankle circles).
    • Progressively reintroduce running and jumping: Begin with brisk walking, then slow jogging, increasing intensity slowly and avoiding excessive load.

  Throughout the rehabilitation, follow the FITT-VP principles (Frequency, Intensity, Time, Type, Volume, Progression) and adjust according to bone healing status and pain levels.

Disclaimer:
This report provides a preliminary analysis based on the available information and is intended only as a reference. It does not replace in-person consultation or professional medical advice. If there is any doubt or if symptoms worsen, please seek prompt medical attention or follow specialist guidance.