Cortical Atrophy Related to Tumor Prosthesis in Skeletally Immature Osteosarcoma Patients

Outcomes of Fixed-Hinged Knee Prosthesis for Distal Femoral Osteosarcoma in Skeletally Immature Patients: First Results

The best surgical choice for distal femur osteosarcoma in skeletally immature patients remains controversial. A fixed hinged knee prosthesis has been designed to preserve the growth plates in the adjacent tibia, expecting tibial growth to be continued. This study aims to report the (1) clinical outcomes after prosthetic replacement, (2) postoperative complications, and (3) length of discrepancy of the operative tibia with the unaffected tibia. Thirty-four skeletally immature patients (averaged 9 years at surgery; range, 5-12 years) with distal femoral osteosarcoma underwent placement of this hinged knee prosthesis between January 2015 and August 2018. Postoperative function and complications were assessed. Length discrepancy was measured using a series of full-length standing anteroposterior radiographs of the bilateral lower extremity. The average follow-up duration was 34 months (2.8 years). In the last follow-up, four patients expired because of pulmonary metastasis. Two patients presented with local recurrence of the soft tissue. Postoperatively, the flexion range of the knee joint range was between 100 and 130 degrees, with an average of 115.2 degrees. The mean functional score of living patients evaluated using the Musculoskeletal Tumor Society scoring system was 89.2% (range, 76.7-100%). Types 1 (three patients), 2 (one patient), 3 (two patients), and 5 (two patients) complications exist. Among them, three patients received revision surgery. The proximal tibial physis still grew after surgery, with an average of 74.3% (range, 30-100%) growth potential compared with the unaffected proximal tibial physis. Moreover, 27 children exhibited tibial length discrepancy compared with the contralateral tibia, and the mean discrepancy in tibial length was 1.1 cm (range, 0.2-3.1 cm). This hinged knee prosthesis can keep the growth potential in the adjacent tibia, provides satisfying functional outcomes, and has a lower postoperative complication rate. Thus, it could serve as an alternative intervention for distal femoral osteosarcoma in skeletally immature patients.

What is the Cumulative Incidence of Revision Surgery and What Are the Complications Associated With Stemmed Cementless Nonextendable Endoprostheses in Patients 18 Years or Younger With Primary Bone Sarcomas About the Knee

BACKGROUND

Osteosarcoma and Ewing sarcoma are more common diagnoses in preadolescent and adolescent children compared with the adult population. A greater percentage of patients are treated with limb salvage and reconstruction using modular tumor endoprostheses. Implant-to-bone fixation can be cemented or cementless. Cementless tumor endoprostheses rely on biologic osteointegration for implant stability, and chemotherapy during childhood and adolescence can disturb the bone turnover rate and reduce bone mineral density, which in turn may predispose patients with uncemented endoprostheses to a high rate of revision surgeries.

QUESTIONS/PURPOSES

(1) What is the cumulative incidence of revision operations for any cause (wound dehiscence, periprosthetic fracture, hinge breakage, aseptic loosening, infection, local recurrence, implant removal, and amputation) of cementless tumor endoprostheses around the knee? (2) What is the cumulative incidence of aseptic loosening, periprosthetic fracture, hinge breakage, and infection, and what proportion of patients had other complications? (3) What was the mean limb length discrepancy (LLD) at the time of skeletal maturity? (4) What was the median Musculoskeletal Tumor Society (MSTS) score at most recent follow-up or just before implant removal/amputation if implant removal/amputation were performed?

METHODS

Between 2008 and 2019, we treated 328 patients younger than 18 years for a primary bone sarcoma around the knee at our institution. Of those, 138 were treated with resection and reconstruction using two different types of modular tumor endoprostheses. During this period, our general indications for an endoprosthesis were patients who were candidates for an intraarticular resection of the distal femur or proximal tibia and who were at least 10 years of age. Uncemented fixation was always preferred. Cemented fixation was only done when intraoperative press-fitting of a cementless stem was not possible. Among uncemented implants, 26 patients died before completing 2 years of follow-up with intact implants and without further surgery, three were lost to follow-up before 2 years, and four patients received implants as a secondary salvage surgery after a failed primary biologic reconstruction with a vascularized fibular bone graft, leaving 94 patients for evaluation in this retrospective study. The mean age was 15 ± 2 years and the median (interquartile range) follow-up duration was 51 months (39 to 74). We did a competing risks analysis to tally cumulative incidence of all-cause revision procedures and cumulative incidence of aseptic loosening, periprosthetic fracture, hinge breakage, and infection. Other complications, including wound dehiscence, local recurrence, and stem breakage, were characterized descriptively and ascertained by review of electronic records of a longitudinally maintained institutional database by the treating surgeons. LLD was measured by serial clinical assessments and CT scans, starting since primary salvage surgery and until the latest follow-up of every patient. For the analysis of remaining LLD, we included only patients who were skeletally immature at time of primary resection and who had reached skeletal maturity by their latest follow-up (73% [69 of 94]). Functional outcome was assessed using MSTS scores obtained from a review of electronic records of a longitudinally maintained institutional database.

RESULTS

The 8-year cumulative incidence of revision surgery for any cause was 32% (95% confidence interval 23% to 42%). The 8-year cumulative incidence of aseptic loosening was 5% (95% CI 2% to 11%), periprosthetic fracture was 9% (95% CI 4% to 15%), hinge breakage was 19% (95% CI 12% to 28%), and infection was 7% (95% CI 3% to 14%). Other complications included wound dehiscence in 2% (2 of 94), stem breakage in 2% (2 of 94), and local recurrence in 2% (2 of 94) of patients. Stress shielding of the cortical bone around implanted stems was observed in 26% (24 of 94). The mean LLD for those who were skeletally immature at the time of primary resection and who reached skeletal maturity was 3.5 ± 2.6 cm. At latest follow-up, the median (IQR) MSTS score for all patients, excluding those who had complete implant removal or amputation, was 26 (24 to 27) of a maximum score of 30.

CONCLUSION

We observed a high rate of early revision and relatively frequent complications associated with the use of cementless fixation, and although this was not a comparative study, the findings were not superior to those reported by others who have studied cemented fixation for this indication. Furthermore, there may be some disadvantages with cementless fixation, such as stress shielding. Comparative studies about fixation methods are needed. The prevalence of bushing breakage in the current study highlights the importance of future modifications in the hinge design of both types of prostheses used in this study. Patients who were skeletally immature at the time of primary surgery had a LLD no more than 5 cm at skeletal maturity; consequently, nonexpandable endoprostheses may be appropriate for some adolescent patients who have limited remaining growth, although which patients are best suited for this approach would require specific study.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Thirty-Day Outcomes following Pediatric Bone and Soft Tissue Sarcoma Surgery: A NSQIP Pediatrics Analysis

BACKGROUND

Pediatric bone and soft tissue sarcomas are rare; therefore, national registries are essential tools for orthopedic oncology research. Past studies provide excellent data on long-term prognosis and survival trends but fail to examine treatment-specific morbidity. The aim of this study is to use a national registry to describe patient demographics, comorbidities, and adverse events in the first thirty days following surgical management of pediatric bone and soft tissue sarcomas.

METHODS

A retrospective review of patients in the American College of Surgeons National Surgical Quality Improvement Program-Pediatrics database (NSQIP-P) was performed. The cohort was partitioned by tumor origin (bone versus soft tissue) and tumor location (axial versus appendicular).

RESULTS

One-hundred ninety-two patients were identified. Bone sarcomas were more common (71.9%) and predominately appendicular (62.3%), while soft tissue sarcomas were predominately axial (77.8%). The overall complication rate was 8.9%. The most frequent etiologies were wound dehiscence (3.6%) and infectious complications such as surgical site infections (2.6%), pneumonia (1.6%), urinary tract infections (1.6%), and C. diff colitis (1.0%). Twenty-four percent of patients experienced bleeding requiring transfusion. The unplanned readmission rate was 12.5% (3.6% related to principle procedure), and the unplanned reoperation rate was 4.7% (4.2% related to principle procedure). The mortality rate was 1.0%. Neoadjuvant chemotherapy was associated with higher rates of wound dehiscence and infectious complications. There were no differences in adverse events with respect to tumor origin or location.

CONCLUSION

Approximately 1 in 11 pediatric patients will experience a complication in the first thirty days following surgery. However, perioperative mortality remains low. This study represents the first comprehensive review of pediatric bone and soft tissue sarcoma surgery in the NSQIP-P database. As the case volume of NSQIP-P continues to grow, NSQIP-P has the potential to become a powerful tool for pediatric orthopedic oncology research.

Integration of a Three-Dimensional-Printed Titanium Implant in Human Tissues: Case Study

A titanium alloy implant of appropriate pore size can potentially enhance osseointegration and soft tissue integration. However, the human clinical application of such implants has not been reported. Here, we present a case of limb salvage surgery for a bone tumor using customized three-dimensional (3D)-printed Ti6Al4V radius and ulna implants. The patient presented with local recurrence at the proximal junction of the ulna and underwent a re-wide excision. Single forearm bone surgery was performed using another 3D-printed implant after resection of the recurrent tumor with an ulnar implant. Host osseointegration and soft tissue integration of the retrieved implant were quantified through histological evaluation. The total tissue integration rates of the implant at the proximal and distal bone junctions were 45.96% and 15.03%, respectively. The mesh structure enhanced bone integration by up to 10.81% in the proximal and by up to 8.91% in the distal bone junction. Furthermore, the soft tissue adhesion rates of the implant shaft were 59.50% and 50.26% in the axial and longitudinal cuts, respectively. No area was left unoccupied throughout the shaft of the implant. Overall, these results indicate that the 3D-printed Ti6Al4V titanium alloy implant with a rough surface has considerable tissue integration ability.