1. Imaging Findings

Based on the provided lumbar spine X-ray, abdominal CT, and follow-up MRI, the main findings are:

• The T12 vertebral body shows a marked loss of height or collapse, with more pronounced anterior collapse, suggesting a compression fracture.
• On CT or MRI, there may be gas density within the vertebral body (vacuum cleft sign), or on MRI, corresponding low signal intensity (T1 and T2 low signal) can be seen. In some cases, high-signal fluid signs (fluid sign) may be present.
• No obvious destructive changes in adjacent vertebral bodies or intervertebral discs are observed, and there is no significant swelling or mass in the surrounding soft tissues.
• The patient also shows signs of osteoporosis, with reduced bone density leading to an increased risk of vertebral collapse.

2. Possible Diagnoses

Based on the above imaging characteristics and the patient’s advanced age and history of osteoporosis, the following diagnoses can be considered:

1. Kümmel's Disease
   Typically presents as a vertebral collapse occurring some time after a mild trauma, with a characteristic “vacuum cleft sign” within the vertebral body. The pathological mechanism is primarily related to aseptic necrosis or nonunion of the vertebral body. This aligns well with the patient’s history of progressive collapse over several months and the imaging findings.
2. Malignancy (Metastatic Tumor) or Pathological Fracture
   Malignant bone metastases may show vertebral destruction or collapse, often accompanied by bone destruction, soft tissue masses, or involvement of other sites. Currently, there is no clear evidence of tumor in this case, but further follow-up or clinical evaluation is required to rule out malignancies.
3. Vertebral Infection (Spondylitis or Discitis)
   Infection can lead to vertebral destruction or collapse, often accompanied by abnormal signals within or around the vertebral body or intervertebral disc, and clinical symptoms of infection. No such changes are observed in this case so far.

3. Final Diagnosis

Considering the patient’s age, history of osteoporosis, mild trauma, the vacuum cleft sign on imaging, and the delayed vertebral collapse over several months, the most likely diagnosis is:

Kümmel's Disease

If there is still doubt, further imaging follow-up, bone scan, or relevant blood tests can be performed to exclude tumors or infections. If clinically indicated, a biopsy can be considered to confirm the diagnosis definitively.

4. Treatment Plan and Rehabilitation

The treatment strategy depends on the severity of symptoms, degree of vertebral deformity, and the patient’s overall health status, and generally includes:

1. Conservative Management
   Suitable for patients with relatively mild symptoms. This may include pain medications, wearing a brace (e.g., lumbar or thoracolumbar support) to stabilize the spine, and anti-osteoporotic therapy (e.g., bisphosphonates, vitamin D, calcium supplements) to improve bone density.
2. Minimally Invasive Procedures
   Vertebroplasty or kyphoplasty can help stabilize the vertebral body, alleviate pain, and potentially restore some vertebral height. These procedures are indicated in patients with significant pain or fractures that fail to heal.
3. Surgical Treatment
   For severe vertebral collapse with spinal cord or nerve compression, or instability of the spine, surgical decompression and internal fixation may be considered, along with bone grafting or fusion to restore spinal stability.

Rehabilitation and Exercise Prescription:

• Gradual Progression and Individualization:
  Because the patient has severe osteoporosis and fragile vertebrae, an individualized exercise plan should be developed under the guidance of a specialist or rehabilitation therapist. Excessive loading should be avoided to prevent further fractures.
• Initial Phase (Early Rehabilitation):
  Begin with low-intensity core stabilization and gentle joint mobility exercises, such as supine or seated abdominal breathing, pelvic tilting, and straight leg raises. Each session can last about 10–15 minutes, 1–2 times per day, progressing gradually according to tolerance.
• Intermediate Phase (Strength and Balance Training):
  Once symptoms improve, light resistance exercises (e.g., elastic band training) and lower-limb balance exercises (e.g., seated to standing, heel raises and step-backs with support) can be added, 2–3 times per week, each session 15–30 minutes. Gradually increase resistance and difficulty to strengthen muscles and improve balance.
• Later Phase (Functional Enhancement and Endurance):
  With no significant pain, low-intensity aerobic exercises (such as walking with support or low-speed cycling) can be introduced. They are recommended 3–5 times per week, each session 20–30 minutes, adjusting intensity based on heart rate and perceived exertion. Avoid overexertion and monitor skeletal and cardiopulmonary status to adjust the program as needed.
• Precautions:
  Throughout rehabilitation, closely monitor pain, skeletal loading, and cardiopulmonary tolerance. If new or unresolved pain occurs, seek medical attention promptly to rule out refracture or other complications.

Disclaimer: The above analysis report is for reference only and cannot replace a physician’s in-person diagnosis and treatment. The final diagnosis and treatment plan should be made in consideration of the patient’s actual condition and the judgment of professional medical personnel. If you experience any new symptoms or have concerns, please consult a physician promptly.