Computer Navigation-Aided Joint-Preserving Resection and Custom-Made Endoprosthesis Reconstruction for Bone Sarcomas: Long-Term Outcomes
Bone sarcomas involving the metaphysis of long bones traditionally require joint excision to achieve safe surgical margins. However, preserving the joint while ensuring oncological safety has been a persistent challenge. Recent advancements in imaging technology and computer-assisted navigation have enabled surgeons to precisely delineate tumor boundaries and perform joint-preserving resections. This study evaluated the long-term outcomes of a novel approach combining computer navigation-aided resection with custom-made endoprosthesis reconstruction for bone sarcomas in the femur and tibia.
Background and Rationale
Segmental resection and endoprosthetic reconstruction remain standard treatments for bone sarcomas. Historically, tumors involving the metaphysis necessitated joint excision due to the difficulty of achieving tumor-free margins while preserving articular structures. Magnetic resonance imaging (MRI) and computed tomography (CT) advancements now allow precise visualization of tumor extent, enabling trans-metaphyseal osteotomies. However, residual bone length after joint-preserving resection is often limited, complicating reconstruction. Custom-made endoprostheses with extracortical plate fixation have emerged as a solution, providing stable fixation even with short residual bone segments.
Computer navigation technology, initially applied in spinal and pelvic surgeries, enhances precision by fusing CT and MRI data. This integration allows surgeons to plan virtual osteotomies at safe distances from tumor edges and execute them intraoperatively with minimal error. This study demonstrates the efficacy of this approach in preserving joints, optimizing functional outcomes, and minimizing complications.
Surgical Methodology
Preoperative Planning
Between 2008 and 2015, 24 patients with diaphyseal or metaphyseal bone sarcomas underwent joint-preserving resection and reconstruction. Preoperative imaging included radiography, contrast-enhanced CT, MRI, and bone scans. Tumor boundaries were mapped using CT-MRI fusion in a navigation workstation (CT Spine, Stryker Navigation), generating 3D models to plan osteotomy lines ≥10 mm from the tumor edge.
Custom-made prostheses (LDK Co., Ltd.) were designed using Mimics® software. Each prosthesis featured an extracortical plate fixed to the residual bone via locking screws, ensuring stability. Residual bone length requirements were ≥10 mm for tibial tumors and ≥30 mm for femoral tumors.
Intraoperative Navigation
Intraoperatively, navigation trackers were fixed to unaffected bone. Image-to-patient registration utilized ISO-C C-arm 3D imaging (23 patients) or point-to-point registration (1 patient). The navigation system confirmed osteotomy planes, ensuring alignment with preoperative plans. After tumor resection, specimens were analyzed to verify margins.
Reconstruction Technique
For distal femoral or proximal tibial tumors (21 patients), defects were reconstructed with custom prostheses fixed to residual bone via extracortical plates. Intramedullary stems cemented into adjacent bone provided additional stability. Three patients with extensive femoral involvement underwent total femoral resection and hip reconstruction with bipolar arthroplasty. Tibial reconstructions included gastrocnemius flaps to cover prostheses and reinforce patellar tendon reattachment.
Postoperative Care
Patients began physiotherapy after drain removal, progressing to partial weight-bearing at 3–6 weeks and full weight-bearing by 3 months. Those with patellar tendon reattachment used knee braces for 8 weeks. Adjuvant chemotherapy followed wound healing for osteosarcoma and Ewing sarcoma patients.
Clinical Outcomes
Oncological and Surgical Results
All resections achieved wide margins. The median distance from the resection margin to the joint was 30 mm (range: 13–80 mm). Resection accuracy analysis revealed a mean error of 3.12 mm in specimen length and 2.09 mm in margin distance from the tumor. At a median follow-up of 62.5 months (range: 24–134), 21 patients remained disease-free. Three developed lung metastases, with two succumbing to the disease. One patient experienced local soft-tissue recurrence.
Complications
Six patients (25%) required reoperation:
- Infection: One superficial and one deep infection resolved with debridement and flap reconstruction.
- Wound Issues: One hematoma and one delayed healing.
- Mechanical Failure: Two cases of prosthesis loosening (7 and 87 months postoperatively). The 5- and 10-year implant survival rates were 91.3% and 79.9%, respectively.
Functional Outcomes
Mean Musculoskeletal Tumor Society (MSTS) score at final follow-up was 91% (range: 80–100%), reflecting excellent joint function and mobility.
Discussion
Precision and Safety
Computer navigation enabled precise osteotomies, minimizing margin errors and preserving maximal healthy bone. The fusion of CT and MRI data improved tumor boundary visualization, critical for joint preservation. The 4% local recurrence rate aligns with literature reports (0–4%), underscoring the technique’s oncological safety.
Prosthetic Stability
Extracortical plate fixation addressed challenges of short residual bone segments. Despite median residual bone lengths of 30 mm (femur) and 10 mm (tibia), only two mechanical failures occurred. The high 10-year survival rate (79.9%) compares favorably with traditional intercalary prostheses (63–68%). Immediate stability was achieved through exact prosthesis-bone interface matching and multi-screw fixation (up to six screws).
Functional Advantages
Preserving native joints and ligaments contributed to superior MSTS scores (91%) versus non-navigated joint-sparing techniques (77–88%). Early mobilization protocols further enhanced recovery.
Limitations
The study’s retrospective design and small sample limit generalizability. Residual bone lengths <30 mm were not explored, warranting further research.
Conclusions
Computer navigation-aided joint-preserving resection with custom endoprosthesis reconstruction offers a reliable, functionally superior option for metaphyseal bone sarcomas. The technique balances oncological safety with mechanical stability, achieving durable outcomes and high patient satisfaction. Future studies should explore its applicability in cases with extremely short residual bone segments.
doi.org/10.1097/CM9.0000000000001750
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