Medical Imaging Analysis Report

I. Imaging Findings

Based on the X-ray and MRI images of the knee joint provided by the patient, a soft tissue mass is observed beneath the patella (i.e., near the patellar tendon and fat pad area). The plain radiograph (X-ray) reveals irregular calcifications within the lesion, located at the inferior margin of the patella and within the anterior fat pad of the knee, possibly accompanied by local soft tissue prominence. A CT scan (if available) could further confirm its calcified or ossified components, typically appearing as an oval or irregular soft tissue density containing ossifications or calcifications.

On MRI, especially on T2-weighted and T2*-weighted sequences, the interior of the lesion shows heterogeneous signals, characterized by mixed high and low intensities: high intensities may correspond to cartilaginous matrix or mild edema, while low intensities may indicate calcified or ossified deposits. The lesion boundary is relatively well-defined, partially demarcating it from surrounding structures. There may be slight compression or even superficial cortical erosion of the patella or femoral condyle.

II. Potential Diagnoses

Based on the clinical and imaging characteristics, the following diagnoses should be considered:

1. Intra-articular Chondroma (Extraskeletal Chondroma)
   Usually located in the infrapatellar fat pad region, with possible calcification or ossification of the cartilaginous matrix. On MRI, it typically presents with heterogeneous signals. It is a rare cartilage tumor.
2. Primary Synovial Chondromatosis
   Commonly presents with synovial thickening and the formation of multiple cartilaginous nodules inside the joint cavity, often accompanied by numerous loose bodies or nodules. Similarities with this case include the presence of cartilaginous calcification or ossification, but it usually has a more diffuse involvement with multiple nodules within the joint space.
3. Chondrosarcoma
   A malignant cartilaginous tumor. X-ray or MRI may also reveal calcifications or ossifications. However, malignancy is often suggested by pronounced bone destruction, poorly defined lesion boundaries, and evident invasive growth. Clinically, symptoms typically worsen progressively.

III. Most Likely Final Diagnosis

Taking into account the patient's age (44 years), symptoms (anterior knee pain for one year, restricted range of motion, and soft tissue swelling in the infrapatellar region), imaging findings (prominent cartilaginous calcification or ossification in the infrapatellar fat pad presenting as a localized mass with heterogeneous MRI signals), the most likely diagnosis is Intra-articular Chondroma (Extraskeletal Chondroma).

If clinical ambiguity persists, further histological biopsy or intraoperative frozen section analysis could be performed to determine benign or malignant nature.

IV. Treatment and Rehabilitation Plan

1. Treatment Strategy
Surgical resection is the first-line treatment, generally performed arthroscopically or with an open procedure aiming to completely remove the lesion. Given potential calcified or ossified components, thorough debridement is essential to reduce recurrence. If the lesion is large or anatomically complex, the surgical approach might require more detailed planning, possibly involving a “windowing” procedure or a small-incision method.

2. Rehabilitation and Exercise Prescription
Postoperative rehabilitation can be guided by a gradual approach following the FITT-VP principle (Frequency, Intensity, Time, Type, Volume, Progression):

• Early Postoperative Stage (Weeks 1–2)
  • Focus on reducing swelling, alleviating pain, and preventing joint stiffness;
  • Apply CPM (Continuous Passive Motion) or passive range-of-motion exercises 2-3 times per day, each session lasting 10-15 minutes, stopping short of provoking severe pain;
  • Perform isometric quadriceps exercises (contract the thigh muscles while the leg is straight), holding for 5-10 seconds before relaxing, with 10-15 repetitions per set, 2-3 sets per day.
• Mid Postoperative Stage (Weeks 3–6)
  • As joint mobility improves, gradually add active flexion and extension exercises and low-load closed-chain exercises (e.g., seated small-range knee flexion);
  • Continue 2-3 daily sessions of range-of-motion exercises, each lasting 15-20 minutes, incorporating progressive resistance using elastic bands or light weights (around 0.5–1 kg);
  • Emphasize coordinated training of the quadriceps and hamstring muscles, while avoiding excessive load on the joint.
• Late Postoperative Stage (6 Weeks and Beyond)
  • Once near-normal range of motion is regained and pain is manageable, gradually introduce partial weight-bearing and functional activities such as walking on level surfaces or mild stair climbing;
  • Continue progressive strengthening, along with balance and proprioceptive exercises;
  • Depending on clinical assessment and functional milestones, gradually resume running, light hopping, or other higher-impact activities.

Disclaimer

This report is based solely on the available data for reference and does not replace in-person consultations or professional medical advice. If you have any concerns or if your condition changes, please consult a specialist and undergo further examinations to determine the most appropriate diagnosis and treatment plan.