1. Radiological Findings

Based on the provided X-ray of the left lower leg, a high-density shadow can be seen in the local soft tissue, presenting as irregular fragments. Considering the patient’s history of trauma, a retained glass foreign body is highly suspected. The soft tissue margins may show mild swelling, indicating a potential inflammatory or infective reaction. The overall continuity of the bone structure (including the tibia and fibula) is relatively preserved, with no definite fracture lines or significant bone destruction observed.

2. Potential Diagnoses

1. Retained glass foreign body with secondary soft tissue infection: After trauma, the patient has persistent pain and has sought medical attention multiple times. Combining the high-density shadow on X-ray and the patient’s history, the most likely diagnosis is retained glass debris, leading to ongoing local soft tissue irritation or infection.
2. Other soft tissue foreign bodies or injuries: Such as metal fragments or other radiopaque materials; however, clinically and historically, retained glass is more likely.
3. Soft tissue abscess or encapsulation: Due to long-term infection or repeated irritation, there may be a focal fluid collection or abscess. However, the sensitivity of conventional X-ray in diagnosing abscess is limited, and further imaging studies (such as ultrasound, CT, or MRI) may be required for confirmation.

3. Final Diagnosis

Combining the patient’s age (20 years old), the history of left lower limb trauma with retained glass foreign body, recent recurrent infections, local pain, and the X-ray findings, the most likely final diagnosis is:

• Retained glass foreign body in the soft tissue of the left lower leg with secondary infection.

If there are still uncertainties regarding the nature of the foreign body or the condition of the soft tissue, further confirmation can be obtained through ultrasound or CT to determine the exact location of the foreign body and the extent of surrounding tissue damage.

4. Treatment Plan and Rehabilitation

4.1 Treatment Strategy

• Surgical debridement and foreign body removal: In the appropriate setting of anesthesia and sterile conditions, surgical removal of the retained glass shards should be performed, along with thorough debridement to reduce the risk of reinfection.
• Anti-infective treatment: Based on the surgical findings and likely bacterial pathogens, empirical or targeted antibiotic therapy may be administered, with the duration depending on the severity of the infection.
• Wound management and regular follow-up: Postoperatively, the wound should be kept clean and reviewed regularly to ensure proper healing and to prevent recurrent infection.

4.2 Rehabilitation and Exercise Prescription

Once the foreign body is removed and the infection is under control, progressive rehabilitation may be initiated. The following is based on the FITT-VP principles (Frequency, Intensity, Time, Type, Progression) for reference:

1. Early Phase (1-2 weeks postoperatively)
   • Frequency: 2-3 sessions of mild activities per day.
   • Intensity: Limited to a level that does not cause significant pain or wound discomfort.
   • Time: Approximately 5-10 minutes each time, encouraging gentle movement of the ankle and knee joints.
   • Type: Primarily active range of motion exercises, such as ankle dorsiflexion, plantarflexion, and circular movements, avoiding vigorous weight-bearing.
   • Progression: Gradually increase activity frequency as pain and swelling subside.
2. Intermediate Phase (2-4 weeks postoperatively)
   • Frequency: 3-4 exercise sessions per week.
   • Intensity: Gradually increase lower leg and quadriceps strength training as tolerated without significant pain, e.g., light resistance band exercises.
   • Time: 15-20 minutes per session, with appropriate rest intervals.
   • Type: Under the guidance of a physician, light weight-bearing exercises may be attempted, such as standing leg raises and slow squats.
   • Progression: As joint range of motion improves, progressively increase the proportion of lower limb strength training.
3. Late Phase (4-6 weeks postoperatively and beyond)
   • Frequency: 3-5 sessions per week, increasing as functional recovery allows.
   • Intensity: Gradually and appropriately increase weight-bearing intensity, such as slow jogging and weighted squats.
   • Time: 20-30 minutes per session; additional rest intervals may be added if necessary.
   • Type: Include exercises for strengthening the calf muscles and core, along with balance and coordination training.
   • Progression: Once normal daily activities are resumed, progressively return to higher-intensity exercises while continuing to monitor local responses.

Throughout the rehabilitation process, local pain, redness, or discharge should be closely monitored. If any abnormality occurs, promptly seek medical attention and adjust the rehabilitation plan accordingly.

4.3 Special Considerations

• Infection Monitoring: If the wound remains red, swollen, painful, or if discharge increases, or if systemic symptoms (fever, chills, etc.) occur, persistent or recurrent infection should be suspected, and prompt medical attention should be sought.
• Personal Protection: During exercise, keep the wound area dry and clean, and avoid intense friction that may cause secondary injury.

Disclaimer:
This report is based on the preliminary analysis of the provided clinical and imaging information. It is for reference only and cannot replace an in-person consultation or professional medical advice. If you have any questions or changes in condition, please seek medical attention or professional guidance promptly.