1. Radiological Findings

Based on the provided X-rays:

• Obvious signs of joint effusion are visible around the elbow joint, especially the posterior fat pad sign, suggesting fluid or exudate within the joint capsule.
• The main ossification centers around the child’s elbow (including the radial head, capitellum, trochlea, etc.) are generally visible. However, the medial epicondyle is not seen in its normal anatomical position.
• A displaced bone fragment can be seen projected within the joint space, overlapping the articular surface on the lateral view, suggesting a significantly displaced medial epicondyle fragment (suspected avulsion fracture fragment).
• Because the patient is 13 years old and still in the skeletal development stage, and considering the CRITOL sequence, the medial epicondyle should be visible but is not clearly shown in its normal location.

2. Possible Diagnoses

Based on the above radiological features and clinical symptoms (pain, swelling, limited mobility after a sports injury), the possible diagnoses include:

1. Avulsion Fracture of the Medial Epicondyle of the Humerus
   Due to traction forces causing a fracture at the local ligament or tendon attachment site; imaging often shows an abnormally positioned fracture fragment with marked displacement.
2. Elbow Physeal Injury (Growth Plate Injury)
   An injury near the growth plate, which can be confused with an avulsion fracture. However, the fracture line or abnormal density usually appears closer to the growth plate region, requiring additional imaging for clarification.
3. Elbow Dislocation with Associated Fracture
   A complete or partial dislocation may be accompanied by a fracture, especially an avulsion of the medial epicondyle. However, since X-rays indicate that the radial head and capitellum appear to align, a major dislocation is less likely; an avulsion fracture is more probable.

3. Final Diagnosis

Considering the patient’s age, clinical presentation (traumatic injury during judo training), imaging features (local swelling, fat pad sign, displaced medial epicondyle fragment), and the timing of epiphyseal appearance, the most likely diagnosis is:

Medial Epicondyle Avulsion Fracture of the Humerus.

4. Treatment Plan and Rehabilitation

4.1 Treatment Strategy

• Conservative Treatment: If the fragment displacement is minimal (generally less than 5 mm) and the articular surface or growth plate is not significantly affected, a cast or brace can be used to limit excessive elbow motion and allow natural healing.
• Surgical Treatment: If the fracture fragment is significantly displaced (more than 5–10 mm), or if there is entrapment or instability of the joint, surgical reduction and internal fixation (using screws or Kirschner wires, etc.) should be considered to restore joint stability and prevent future cubitus valgus deformity or limited joint function.
• Medication and Pain Management: Moderate use of anti-inflammatory and analgesic medications can help relieve pain and reduce inflammation. Other pain management measures may be considered short-term under medical evaluation.

4.2 Rehabilitation and Exercise Prescription

Principles of rehabilitation: gradual progression and individualization.

• Immobilization and Rest Period (postoperative or acute phase of injury, about 4–6 weeks):
  • Use of a brace or cast, focusing primarily on swelling reduction and pain management.
  • Encourage active movement of the shoulder, wrist, and fingers to prevent muscle atrophy and joint stiffness.
  • Avoid any activities that may cause excessive traction on the elbow or reinjury.
• Joint Mobility Recovery Phase (after removing the cast or brace, about 6–8 weeks):
  • Under the guidance of a professional rehabilitation therapist, perform passive and active elbow flexion and extension exercises, carefully controlling range and intensity, and gradually increasing range of motion.
  • Engage in joint mobility exercises 2–3 times per day, each session lasting about 10–15 minutes, with rest intervals.
  • Avoid rapid twisting motions or placing excessive resistance on the elbow.
• Strength and Functional Training Phase (after 8 weeks):
  • Gradually increase upper limb resistance training, such as using resistance bands or light dumbbells to strengthen muscles around the elbow.
  • Maintain a controlled pace of movement, starting with lower resistance and higher repetitions (10–15 reps per set), and gradually increase resistance.
  • Incorporate functional movement training to slowly regain daily and sports-related abilities.

Throughout the rehabilitation process, regular follow-ups are necessary to adjust the exercise program based on recovery progress. If significant pain or discomfort occurs, stop the relevant activities and consult a physician or rehabilitation therapist.

FITT-VP Principle Example:

• Frequency: 3–5 times per week, with at least one rest day after each training session.
• Intensity: Start with low resistance or small-range movements. Gradually increase intensity according to joint stability and pain response.
• Time: 10–30 minutes per session, divided into segments—for example, 10 minutes of range-of-motion exercises + 10 minutes of light resistance training.
• Type: Emphasize improving range of motion and endurance first, gradually transitioning to strength training.
• Volume: Adjust the total workout volume according to the patient’s tolerance, continuously monitoring muscle fatigue and pain.
• Progression: Increase resistance, extend exercise time, or add more complex movements as recovery allows.

Disclaimer

This report is solely a reference analysis based on the provided imaging and history. It cannot replace an in-person consultation or professional medical advice. If you have any questions or if symptoms worsen, please seek immediate medical attention or consult a specialist.