1. Imaging Findings

Based on the provided X-ray and MRI images, the lesion is located around the midshaft of the tibia in the left lower leg. On plain radiographs, there is significant bony destruction with a multilocular or septated radiolucent appearance. Part of the lesion boundary is clear, but irregularities are observed in some areas. No obvious pathological fracture is noted, and there is no significant periosteal reaction.
MRI shows local erosion or marked thinning of the tibial cortex. The lesion exhibits heterogeneous signals on T1- and T2-weighted images, with multiple small low or mixed-signal septations, suggesting the presence of different internal components. There is no extensive soft tissue swelling or prominent soft tissue mass, but localized soft tissue involvement is noted.

2. Possible Diagnoses

1. Adamantinoma:
   • Most common in patients aged 20–50, typically presenting in the mid-tibia with multifocal, eccentric, or trans-cortical bony destruction.
   • Symptoms may include localized intermittent pain or swelling, with a protracted course.
   • Imaging often reveals a multilocular destructive lesion and possible satellite nodules, which align with the findings in this case.
2. Fibrous Dysplasia:
   • May present with a “ground-glass” appearance, with relatively well-defined lesion margins.
   • However, the small infiltrative or septated changes and satellite lesions on MRI in this case are more consistent with Adamantinoma.
3. Osteofibrous Dysplasia:
   • Primarily seen in children and adolescents, mainly involving the tibial cortex with fibrous lesions, but it usually does not show obvious multilocular lucent areas or satellite nodules.
4. Other Bone Tumors or Metastases (e.g., Osteosarcoma, Metastatic Lesions):
   • If the lesion is very aggressive, these could be considered. However, the clinical history and imaging features in this case lean more toward Adamantinoma.

3. Final Diagnosis

Considering the patient’s age (22 years old), clinical presentation (mid-tibia pain and swelling for several months), imaging features (multilocular radiolucent lesion, lack of significant periosteal reaction, localized cortical destruction of the mid-tibia, and small satellite lesions), and common site of occurrence, the most likely diagnosis is Adamantinoma.
For definitive confirmation, a histopathological biopsy is still required.

4. Treatment Plan and Rehabilitation

Treatment Strategy:
For Adamantinoma, the recommended treatment is wide en-bloc surgical resection to minimize the risk of local recurrence. Depending on the extent of resection, bone grafting or reconstruction may be required to maintain the mechanical stability of the tibia. Postoperative follow-up with chest imaging is advised to screen for pulmonary metastases, and the need for adjuvant therapy depends on the pathological stage and surgical outcomes.

Early Rehabilitation and Exercise Prescription:
(1) Early Postoperative Phase (0–4 weeks):

• Monitor the surgical incision for proper healing and avoid excessive weight-bearing.
• When approved by the physician, engage in non-weight-bearing joint mobility exercises, such as active movement of the ankle and knee joints.
• Perform simple isometric or light resistance exercises for the upper limbs and the healthy lower limb to maintain basic muscle strength and cardiovascular function.

• Based on bone healing and the surgeon’s advice, gradually transition to partial weight-bearing ambulation with the support of crutches.
• Engage in low-impact functional training such as water activities or seated leg stretches to reduce stress on the affected limb.
• Continue strengthening the upper limbs and the healthy lower limb to maintain overall balance and stability.

• Once imaging and clinical evaluation confirm adequate bone healing, progressively increase weight-bearing activities, eventually transitioning to full weight-bearing.
• Appropriate exercises include walking on flat ground, cycling, and gentle squats, gradually increasing load intensity.
• Maintain a frequency of 3–5 training sessions per week, about 30 minutes each, with appropriate rest intervals.

• Closely monitor pain, swelling, or other symptoms during rehabilitation; seek medical advice if concerns arise.
• If the patient has other comorbidities (e.g., reduced cardiopulmonary function), further adjustments to exercise intensity and modalities are required.

Disclaimer: This report provides a reference analysis based on the current information and does not replace in-person diagnosis or professional medical advice. Specific diagnosis and rehabilitation plans should be tailored to the patient’s actual condition and follow clinical guidelines.