Staged lengthening arthroplasty for pediatric osteosarcoma around the knee

Management of limb length discrepancy after bone sarcoma resection about the knee in the skeletally immature

Patients with bone sarcomas increasingly choose limb salvage. This can lead to issues with limb length discrepancy (LLD) for the skeletally immature. We synthesize management options into an algorithm and report our results. Patients with bone sarcomas involving any location from the femoral diaphysis to the tibial diaphysis 12 years or younger were reviewed. Our clinical pathway prescribed patients with metadiaphyseal lesions to intercalary allograft reconstruction, epiphyseal lesions and less than 5 cm expected LLD to osteoarticular allograft and patients with more than 5 cm expected LLD to extendable prosthesis. Twenty patients met inclusion criteria: 11 with osteoarticular allografts, 5 with extendable prostheses and 4 with intercalary allografts; median age 11.5 years; median follow-up 8.2 years; and final median LLD 1.6 cm. Five patients had contralateral epiphysiodesis, two patients underwent contralateral femoral shortening and a median of 6 (range 4-8) lengthenings were performed for extendable prostheses. Four patients had residual LLD over 3 cm. There were 13 revisions in 8 patients and 2 amputations. Limb-salvage in paediatric bone sarcoma of the knee can be managed with multiple techniques producing satisfactory results in regards to LLD. Careful pre-operative planning and shared decision making is a requisite given the high rate of secondary procedures for both LLD and reconstructive failures. Level of evidence: Level III Retrospective Comparative Study.

Advancing pediatric bone sarcoma care: navigating complications and innovating solutions in limb salvage and reconstruction-why, when, and how to treat limb length inequalities

Pediatric bone sarcomas, particularly osteosarcomas, present unique challenges in the realm of orthopedic oncology, given their predilection for the metaphyseal regions of long bones and the intricate balance required between achieving oncologic control and preserving limb function. This abstract encapsulates findings from a comprehensive review aimed at advancing pediatric bone sarcoma care, focusing on navigating the complications and innovating solutions for complications of limb salvage and reconstruction focusing on limb length inequalities and accompanying bone defects. Advancements in imaging, surgical techniques, and adjuvant therapies have shifted the paradigm from amputation to limb-sparing surgeries, albeit with significant challenges, especially in young patients where growth potential complicates reconstructive outcomes. The series highlights the complexity of managing limb length discrepancies (LLD), the cornerstone of limb salvage challenges, and the innovative approaches to address them, including modular endoprosthetic reconstruction with expandable prostheses, magnetic lengthening nails and biological reconstruction strategies like vascularized fibula grafts. This review underlines the importance of a multidisciplinary approach in managing pediatric bone sarcomas, where the aim extends beyond mere survival to ensuring quality of life through functional limb preservation. It highlights the need for ongoing innovation in surgical and reconstructive techniques tailored to the pediatric population's unique needs, emphasizing the potential of emerging technologies and methodologies to improve outcomes. Future research should aim to fill the existing knowledge gaps, particularly in comparing pediatric and adult surgical outcomes, to refine treatment protocols and improve patient care in this challenging domain.

Bone-Regeneration Therapy Using Biodegradable Scaffolds: Calcium Phosphate Bioceramics and Biodegradable Polymers

Calcium phosphate-based synthetic bone is broadly used for the clinical treatment of bone defects caused by trauma and bone tumors. Synthetic bone is easy to use; however, its effects depend on the size and location of the bone defect. Many alternative treatment options are available, such as joint arthroplasty, autologous bone grafting, and allogeneic bone grafting. Although various biodegradable polymers are also being developed as synthetic bone material in scaffolds for regenerative medicine, the clinical application of commercial synthetic bone products with comparable performance to that of calcium phosphate bioceramics have yet to be realized. This review discusses the status quo of bone-regeneration therapy using artificial bone composed of calcium phosphate bioceramics such as β-tricalcium phosphate (βTCP), carbonate apatite, and hydroxyapatite (HA), in addition to the recent use of calcium phosphate bioceramics, biodegradable polymers, and their composites. New research has introduced potential materials such as octacalcium phosphate (OCP), biologically derived polymers, and synthetic biodegradable polymers. The performance of artificial bone is intricately related to conditions such as the intrinsic material, degradability, composite materials, manufacturing method, structure, and signaling molecules such as growth factors and cells. The development of new scaffold materials may offer more efficient bone regeneration.

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.

Biodegradable Polymers as Drug Delivery Systems for Bone Regeneration

Regenerative medicine has been widely researched for the treatment of bone defects. In the field of bone regenerative medicine, signaling molecules and the use of scaffolds are of particular importance as drug delivery systems (DDS) or carriers for cell differentiation, and various materials have been explored for their potential use. Although calcium phosphates such as hydroxyapatite and tricalcium phosphate are clinically used as synthetic scaffold material for bone regeneration, biodegradable materials have attracted much attention in recent years for their clinical application as scaffolds due their ability to facilitate rapid localized absorption and replacement with autologous bone. In this review, we introduce the types, features, and performance characteristics of biodegradable polymer scaffolds in their role as DDS for bone regeneration therapy.

Limb Salvage Using Non-hinged Endoprosthesis and Staged Correction of Leg-length Discrepancy for Children with Distal Femoral Malignant Tumors

OBJECTIVE

Limb salvage in pediatric patients remains a challenge. We describe a staged strategy. The procedure includes: (i) tumor removal and non-hinged static endoprosthesis reconstruction; (ii) leg length discrepancy (LLD) correction by shoe lift or distraction osteogenesis; and (iii) maturity reconstruction by regular endoprosthesis. The aim of the study was to investigate the results of non-hinged static megaprosthesis reconstruction and staged LLD correction in the treatment of malignant tumors in the distal femur in children.

METHODS

Non-hinged megaprostheses were implanted in 12 pediatric patients with osteosarcoma in the distal femur. The prosthesis consists of a femoral component with constrained condylar knee (CCK) design, and a tibial component with a small-diameter press-fit stem and derotation fins. A posterior stabilizing polyethylene component is fixed on the tibial component. The cases were prospectively followed up with focus on the growth rate of adjacent uninvolved bone in the salvaged limb, joint stability, knee stability, function outcome, length discrepancy, and surgery-related complications.

RESULTS

There were five girls and seven boys included in the study, with an average age at the time of primary surgery of 10.0 years (range, 8-12 years). All the tumors were located in the distal femur. The average follow up was 76.3 months (range, 24-139 months). The Ligament Augmentation and Reconstruction System (LARS) ligament was used in two patients to enhance the soft tissue reattachment and reconstruct medial collateral ligament (MCL). Ten patients were alive at the final follow-up and two had died of lung metastases. Expected LLD was 6.7 cm (range, 3.0-13.2 cm) at initial surgery. At the final follow-up, nine patients reached skeletal maturity and the actual LLD at the femur was 5.3 cm (range, 3.0-10.1 cm), excluding 1 cm correction at initial surgery by endoprosthesis. The proximal tibia physis showed an average of 86.7% (range, 56.5%-100%) growth of the contralateral side. The mean reduction in tibial length was 1.2 cm (range, 0.5-4.7 cm). Six patients received distraction osteogenesis at a mean length of 5.4 cm (range, 3.0-9.1 cm). Range of knee movement was between 85° and 125°, with an average of 102.5°. The Musculoskeletal Tumor Society 93 score of patients alive was 80.6 (range, 60-90).

CONCLUSION

Non-hinged static megaprosthesis followed by LLD correction with shoe lift or staged distraction osteogenesis appears to be an alternative option to treat children with malignant bone tumors around the knee.

Joint-preserving tumour resection around the knee with allograft reconstruction using three-dimensional preoperative planning and patient-specific instruments

BACKGROUND

The region around the knee joint is a common location of malignant bone tumours. Limb salvage procedures, whenever possible, are preferred to amputation. Allograft reconstruction is an accepted procedure to restore large bone defects. Preoperative three-dimensional (3D) planning and patient-specific instruments (PSI) have already been introduced. The purpose of this study was to provide a technical guideline for joint preserving tumour resection and allograft reconstruction around the knee using 3D planning and PSI.

MATERIAL AND METHODS

3D triangular surface models are created based on computed tomography (CT) and magnetic resonance imaging (MRI) data, whereby tumour expansion in the bone and affection of the surrounding structures are assessed. We describe the preoperative 3D analysis and planning in tumours around the knee joint. In addition, we provide a description of different PSI as well as cutting-techniques to enlarge the toolkit and facilitate a broad range of joint preserving tumour resections with allograft reconstruction around the knee. The basic guide serves for the registration of the preoperative plan for the surgery. Reference pins facilitate the application of further guides. Different additional guide designs can be applied, such as "safety guides," "osteotomy guides," and "allograft adjustment guides."

DISCUSSION

The use of 3D planning and generation of PSI offers valuable tools in tumour resection and allograft reconstruction around the knee joint. To perform complex osteotomies and to preserve vital structures PSI seems to be helpful tools. A step-by-step guideline is provided for the use of 3D preoperative planning and sequentially applied patient-specific guides.

Staged lengthening and reconstruction for children with a leg-length discrepancy after excision of an osteosarcoma around the knee

AIMS

Children treated for osteosarcoma around the knee often have a substantial leg-length discrepancy at skeletal maturity. The aim of this study was to investigate the results of staged skeletal reconstruction after a leg lengthening procedure using an external fixator in these patients.

PATIENTS AND METHODS

We reviewed 11 patients who underwent staged reconstruction with either an arthroplasty (n = 6) or an arthrodesis (n = 5). A control group of 11 patients who had undergone wide excision and concurrent reconstruction with an arthroplasty were matched for gender, location, and size of tumour. We investigated the change in leg-length discrepancy, function as assessed by the Musculoskeletal Tumor Society Scale (MSTS) score and complications.

RESULTS

A mean 5.2 cm (1.7 to 8.9) of lengthening was achieved. The mean MSTS scores significantly improved after staged reconstruction (p = 0.003) but were still worse than those of the control group (p = 0.049). However, the MSTS scores of the arthroplasty subgroup were comparable with those of the controls, although the extensor lag was greater and the range of movement was less. The patient group experienced more complications, but all of these resolved.

CONCLUSION

Approximately 5 cm of lengthening and significant functional improvement can be achieved by staged reconstruction and lengthening, without major complications. Although it has limitations, this method of treatment seems to be a satisfactory surgical option for growing children with a significant leg-length discrepancy after excision of an osteosarcoma around the knee. Cite this article: Bone Joint J 2017;99-B:401-8.

Temporary hemiarthroplasty with a synthetic device in children with osteosarcoma around the knee as a bridging procedure until skeletal maturity

BACKGROUND

We hypothesized that hemiarthroplasty with a synthetic device in skeletally immature patients with osteosarcoma around the knee would be functional due to high adaptability in the pediatric age group, and may decrease the number of surgeries until limb equalization by preserving the nearby physis.

METHODS

We analyzed the outcomes of 25 hemiarthroplasties (12 distal femur, 13 proximal tibia). Average patient age was 11.8 years. We assessed (1) whether hemiarthroplasty could be considered as a viable option and could preserve growth of the nearby physis, and (2) whether these patients could reach the final goal of adult-type tumor prosthesis implantation within a preplanned number of surgeries.

RESULTS

Three (12%) of 25 hemiarthroplasties showed failure. Average Musculoskeletal Tumor Society functional score of 23 patients was 25.1. Average tibial and femoral shortening for the corresponding reconstruction was 0.3 cm and 0.5 cm, respectively. In terms of number of surgeries for limb equalization, 19 patients (76%) had less, four (16%) had equal, and two (8%) had more surgeries than planned.

CONCLUSIONS

Hemiarthroplasty is a sound option until skeletal maturity, allowing surgeons to choose the appropriate procedure based on the patient's growth status, and may reduce the amount of shortening by preserving nearby physis.