Distal Femur Chondrosarcoma Case | Limb Salvage Reconstruction

Preoperative radiograph of distal femur chondrosarcoma with cortical destruction and internal mineralization

A 58-year-old woman presented with painful, progressively enlarging swelling around the distal femur and knee. Her symptoms were initially attributed to knee osteoarthritis, but the rapid progression of pain and swelling was atypical for uncomplicated degenerative disease.

Patient-friendly summary

The case in one minute

This case illustrates why progressive swelling and pain around the knee should not be assumed to be osteoarthritis when symptoms are rapidly worsening or disproportionate to the radiographic degenerative changes.

Clinical category: Orthopedic oncology
Anatomical site: Distal femur and knee region
Final diagnosis: Chondrosarcoma of the distal femur
Treatment: Wide distal femoral resection and modular distal femoral endoprosthesis
Outcome: Limb preserved with very good postoperative function

Case presentation

A 58-year-old woman presented with a painful, progressively enlarging swelling around the distal femur and knee. Her symptoms had initially been attributed to knee osteoarthritis and treated accordingly. The rapid progression of pain and swelling, however, was atypical for uncomplicated degenerative disease.

Imaging and diagnosis

Plain radiographs demonstrated an aggressive osteolytic lesion of the distal femur with cortical destruction and internal mineralization, raising suspicion for a cartilage-forming malignant bone tumor. Further oncological imaging defined the local extent of the lesion. A planned biopsy confirmed chondrosarcoma, after which the patient was referred for specialized orthopedic oncology management.

For a related educational discussion, read about bone biopsy planning and orthopedic oncology care.

Definitive surgical management

The patient underwent wide oncological resection of the involved distal femur with limb-salvage reconstruction using a modular distal femoral endoprosthesis. The objective was to achieve adequate oncological margins while preserving the limb and restoring knee function.

Systemic therapy and radiotherapy

For localized, resectable conventional chondrosarcoma, complete surgical excision with adequate margins is the mainstay of treatment. Conventional chondrosarcoma is relatively resistant to standard chemotherapy and radiotherapy; therefore, these modalities are not routinely required after adequate resection unless specific histological, anatomical, margin-related, or disease-stage considerations indicate otherwise.

Outcome

Following surgery and rehabilitation, the patient achieved a very good functional outcome with successful limb preservation. Long-term oncological and prosthetic surveillance remains essential.

Educational message

Progressive pain, a rapidly enlarging swelling, night or rest pain, or symptoms disproportionate to apparent osteoarthritis should prompt further investigation. Degenerative changes on imaging do not exclude an underlying bone tumor.

Clinical and operative image sequence

The images are arranged chronologically from preoperative radiographs, through wide resection and gross tumor specimen, to endoprosthetic reconstruction and postoperative radiographs.

**Figure 1. Preoperative AP radiograph**Preoperative AP radiograph of the right distal femur showing an aggressive osteolytic lesion with cortical destruction and internal mineralization, suspicious for a chondrogenic malignancy.

**Figure 2. Preoperative lateral radiograph**Preoperative lateral radiograph demonstrating the destructive distal femoral lesion and its extent around the metaphyseal region.

**Figure 3. Wide en-bloc resection specimen**Wide en-bloc resection specimen of the distal femur after oncological excision, demonstrating the resected bone and surrounding soft-tissue envelope.

**Figure 4. Sectioned resection specimen**Sectioned resection specimen demonstrating the internal gross appearance of the tumor within the distal femur.

**Figure 5. Intraoperative reconstruction**Intraoperative reconstruction after wide distal femoral resection using a modular distal femoral tumor endoprosthesis.

**Figure 6. Intraoperative knee articulation view**Intraoperative view of the distal femoral endoprosthetic reconstruction and knee articulation before wound closure.

**Figure 7. Early postoperative AP radiograph**Early postoperative AP radiograph showing the distal femoral endoprosthesis in position following limb-salvage reconstruction.

**Figure 8. Postoperative radiograph**Postoperative radiograph demonstrating the modular distal femoral endoprosthesis and reconstructed knee.

**Figure 9. Postoperative lateral radiograph**Postoperative lateral radiograph demonstrating the distal femoral endoprosthesis and knee reconstruction.

**Figure 10. Additional postoperative view**Additional postoperative radiographic view confirming the distal femoral endoprosthetic reconstruction.

Case learning points

Can knee osteoarthritis hide a bone tumor?

Degenerative changes may coexist with another pathology. Rapidly progressive swelling, rest pain, night pain, or symptoms disproportionate to typical osteoarthritis should prompt further investigation.

Why was wide resection required?

Chondrosarcoma is a malignant cartilage-forming bone tumor. When localized and resectable, treatment usually depends on complete surgical excision with appropriate margins.

Why use a distal femoral endoprosthesis?

After wide distal femoral resection, a modular tumor endoprosthesis can reconstruct the knee region and support limb preservation when oncologically appropriate.

Does chondrosarcoma always need chemotherapy or radiotherapy?

Conventional chondrosarcoma is relatively resistant to standard chemotherapy and radiotherapy. Management depends on histology, grade, margins, site and disease stage.