Imaging Findings

Based on the provided knee MRI images, combined with the patient's clinical symptoms (knee pain, suspected patellar tendinopathy, and lateral meniscus injury), the following radiological features are observed:

• In the sagittal and coronal sequences, abnormal signals are seen in the posterior horn of the lateral meniscus and the region where it connects to the joint capsule. There is a possible subtle disruption of structural continuity from the meniscus to the related fascia (e.g. the popliteomeniscal fascicles).
• An increased gap between the lateral meniscus and surrounding soft tissue, which may indicate reduced stability of the meniscus or increased mobility (potential “meniscal migration” or “hypermobility”).
• Mild thickening and increased signal intensity of the patellar tendon, suggesting patellar tendinitis (patellar tendinopathy).
• No obvious fracture line is observed. No large-scale cartilage defects or significant degenerative changes are noted in the joint.

Potential Diagnoses

Combining the clinical history and imaging findings, the possible diagnoses include:

1. Lateral meniscal tear or lateral meniscal hypermobility (meniscal instability): The patient's lateral knee pain may be caused by a tear of the lateral meniscus or a lesion in the fascicular structure (especially the popliteomeniscal fascicles), leading to decreased meniscal stability and possible pain or mechanical symptoms.
2. Patellar tendinitis (patellar tendinopathy): Patellar tendinopathy is caused by repetitive loading or chronic overuse of the patellar tendon, with imaging findings showing thickening and abnormal signals in the tendon, consistent with some of the findings in this case.
3. Other soft tissue injuries or meniscus-related pathologies: Such as meniscal root attachment injuries, joint capsule or synovial plica lesions, which are less common clinically but should be considered in cases of lateral knee pain.

Final Diagnosis

Taking into account the 45-year-old female patient, lateral knee pain, clinical exam findings suggesting lateral meniscus injury and patellar tendon pain, as well as MRI findings indicating abnormalities in the lateral meniscus and structures such as the popliteomeniscal fascicles, the most likely diagnoses are:

• Lateral meniscal tear/instability (with popliteomeniscal fascicle injury)
• Patellar tendinitis (patellar tendinopathy)

If further differentiation of the type of meniscal instability and the extent of the tear is needed, arthroscopic evaluation may be considered to directly observe and confirm the integrity of the meniscus and the popliteomeniscal fascicle attachments.

Treatment Plan and Rehabilitation Program

Based on the patient's symptoms, imaging findings, and physical condition, the following treatment and rehabilitation strategies may be considered:

1. Conservative Treatment:
   • In the short term, reduce or avoid activities that place excessive stress on the knee joint, such as squats and jumping.
   • Non-steroidal anti-inflammatory drugs (NSAIDs) can be used to control pain and inflammation, supplemented by physical therapy (heat therapy, ultrasound, low-frequency electrical stimulation, etc.) if necessary.
   • Incorporate joint stability training as well as strengthening exercises for the quadriceps and hamstrings to reduce stress on the meniscus and patellar tendon.
2. Surgical Indications:
   • If arthroscopic examination confirms a significant tear of the lateral meniscus or rupture of the popliteomeniscal fascicles with marked meniscal instability or mechanical locking symptoms, arthroscopic repair or partial resection of the damaged tissue may be considered.
   • If there is severe structural damage to the patellar tendon, surgical reconstruction or release may be evaluated after failure of conservative treatment.
3. Rehabilitation Training and Exercise Prescription (FITT-VP Principle):
   • Frequency (F): Begin at approximately 3 times per week and increase to 4-5 times per week as tolerated.
   • Intensity (I): Focus on light to moderate intensity exercises (e.g., light resistance training, low-impact aerobic exercise), avoiding excessive knee impact.
   • Time (T): Each session should last about 20-30 minutes initially. As pain subsides and muscle strength improves, gradually increase to 40 minutes.
   • Type (T): Choose activities with less impact on the knee, such as swimming, cycling, or using an elliptical machine. Supplement these with strength and stretching exercises targeting the quadriceps, hamstrings, and iliotibial band.
   • Progression (P): As symptoms improve and strength increases, gradually enhance the difficulty and intensity of training, progressing from basic wall sits and straight leg raises to light weight-bearing squats and resistance band exercises, and eventually to jogging or plyometric training (provided there is no significant pain or discomfort).
   • Volume and Individualization (V, I): Adjust training volume according to the patient's feedback, pain levels, and fatigue. If notable pain or discomfort appears, stop the activity and consult a specialist.

Close monitoring of the knee during rehabilitation is essential. If persistent pain or restricted joint movement occurs, suspend related training and seek medical evaluation promptly.

Disclaimer: This report is a medical analysis based on the current information provided, for reference only. It cannot replace in-person consultation or the diagnosis and treatment advice of qualified healthcare professionals. If you experience any discomfort or have further health concerns, please seek prompt medical attention or consult a professional doctor.