Survival and functional outcomes after hemiarthroplasty in children with proximal tibial osteosarcoma.

BACKGROUND

Treatment options for correcting limb-length discrepancy after limb-salvage reconstruction for proximal tibial osteosarcoma in children have several limitations. Therefore, we aimed to evaluate the feasibility, complications, prognosis, and clinical outcomes of reconstruction using hemiarthroplasty after tumor resection in pediatric patients with proximal tibial osteosarcoma.

METHODS

We conducted a comprehensive retrospective analysis of the data of pediatric patients with osteosarcoma of the proximal tibia who underwent surgery between December 2008 and November 2018 at our center. We enrolled 49 consecutive patients who underwent hemiarthroplasty. The cruciate ligaments of all patients were reconstructed using special spacers, and the medial and lateral collateral ligaments of the knee and joint capsule were reconstructed using a mesh. Postoperatively, if the unequal length of both lower limbs exceeded 4 cm or knee instability occurred, a second-stage surgery was performed for limb lengthening and replacing the distal femoral prosthesis. We analyzed the oncological prognosis, complications of hemiarthroplasty, postoperative stability, and postoperative function.

RESULTS

The follow-up period ranged between 11 and 159 months, with a median of 84 (62, 129) months. The overall 5-year survival rate was 83.2%. Thirty-nine patients survived at the end of the follow-up period with 34 prostheses (87.2%). The overall prosthesis survival rate was 87.4% after 5 years, indicating the long-term benefits of the procedure. Limb length was measured in 28 adult patients. The average limb-length discrepancy was 33 ± 15 mm with a median of 33 mm (21, 47); the femur and tibia caused a discrepancy of 8.5 ± 9.9 mm and 24.8 ± 15.5 mm, respectively. The patients had 30-135° of knee motion, with a mean of 82 ± 24°. The femoral tibial angle was greater on the affected side than on the healthy side, with a mean difference of 4.5°±3.6°. The Musculoskeletal Tumor Society (MSTS) score was 25 ± 3. Five patients underwent second-stage distal femoral prosthesis replacement, with mean MSTS scores of 24 ± 2 and 28 ± 1 before and after second-stage surgery, respectively.

CONCLUSIONS

Hemiarthroplasty in children reduces limb-length discrepancy in adulthood by rebuilding cruciate ligaments, lateral collateral ligaments, and the joint capsule, thereby improving knee stability.