Limb-Salvage Options in Growing Children with Malignant Bone Tumors of the Lower Extremity

Is Proximal Tibial Hemiarthroplasty Reconstruction Effective in Minimizing Limb Length Discrepancy Among Skeletally Immature Patients With Primary Bone Sarcomas?

BACKGROUND

Proximal tibial resection and reconstruction with a hinged knee megaprostheses may result in severe limb length discrepancy (LLD) in very young children because of the removal of the distal femoral and proximal physis. An alternative reconstruction using a proximal tibial hemiarthroplasty reconstruction has been proposed and reduces the degree of LLD because the distal femoral physis is preserved. However, there are very few reports on the results from this reconstruction, and it is not certain that the disadvantages of a more unstable knee are outweighed by the possibility of reducing limb length inequality.

QUESTIONS/PURPOSES

(1) What was the survivorship at 5 and 10 years after proximal tibial hemiarthroplasty reconstruction in children with malignant tumors, using amputation, endoprosthesis removal, and revision surgery as the main endpoints of interest? (2) What was the Musculoskeletal Tumor Society Score-93 (MSTS-93) after reconstruction at a minimum of 2 years after the procedure? (3) What percentage of patients experienced a major complication (resulting in unplanned reoperation), and what percentage of patients experienced minor complications (resulting in nonoperative treatment)? (4) What factors were associated with knee subluxation, and what factors were associated with an LLD measuring ≥ 4 cm?

METHODS

This was a retrospective study performed by four consultant surgeons at a tertiary tumor referral center (Beijing Jishuitan Hospital, National Center for Orthopaedics, PR China) between 2005 and 2022. During that time, we generally recommended a tibial hemiarthroplasty to children with primary malignant tumors of the proximal tibia (Enneking stages IA, IB, and IIA and chemotherapy-responsive Stage IIB and IIIB tumors), as well as some metastatic tumors and some soft tissue sarcomas involving and surrounding the proximal tibia in children. We considered the ideal age range to be 9 to 13 years for males and 9 to 12 years for females, and we generally did not offer this procedure unless the surgeon believed that the neurovascular bundle was either uninvolved or could be separated during surgery. During that time, we considered 883 patients with primary malignant bone tumors to be potentially eligible. Of those, 781 were excluded because they underwent joint-preserving endoprosthetic reconstruction, recycled autografts, or extraarticular resection, leaving 110 who met the inclusion criteria for this study. Of those, 15% (16) of patients were lost to follow-up before the minimum follow-up of 2 years, leaving 85% (94) for analysis in this article at a mean ± SD follow-up time of 7 ± 4 years. The most common diagnoses were osteosarcoma (97% [91 of 94]) and Ewing sarcoma (3% [3 of 94]). The mean ± SD age was 11 ± 2 years; 57% (54 of 94) were male. At the last follow-up, 72% (68 of 94) of the patients had no evidence of disease, 9% (8) were alive with disease, 18% (17) had died of disease, and 1% (1) had died of other causes. Survivorship was estimated using the competing risk estimator, and data were presented at 5 and 10 years; outcome scores were derived from a longitudinally maintained institutional database. We reported on patients who developed major complications and underwent unplanned reoperation and minor complications that did not involve further surgery. Cox regression was used to evaluate the factors associated with knee subluxation and severe LLD (≥ 4 cm).

RESULTS

Five-year and 10-year survival of the surgically treated limb free of amputation for all patients was 96% (95% confidence interval [CI] 91% to 99%) and 90% (95% CI 81% to 96%), respectively. The 5-year endoprosthesis removal-free survival rate for all patients was 94% (95% CI 89% to 99%), and the 10-year survival rate was 85% (95% CI 75% to 94%). The 5-year endoprosthetic survivorship free from any revision surgery for all patients was 86% (95% CI 77% to 92%), and the 10-year endoprosthetic survivorship was 68% (95% CI 57% to 79%). The mean ± SD MSTS-93 score was 83% ± 7%. Twenty-eight percent (26 of 94) of patients underwent a total of 28 reoperations. Three percent (3 of 94) of patients underwent revision for knee subluxation (n = 1) and aseptic loosening (n = 2), and 11% (10 of 94) of patients underwent endoprosthesis revision surgery or amputation for local progression (n = 7) and infection (n = 3). No patient had an epiphysiodesis. After controlling for confounding variables such as gender, endoprosthetic type, and mesh reconstruction, multivariate analysis showed that previous surgery at the same site (cause-specific HR 10 [95% CI 5.2 to 59.0]; p < 0.001) and not using medial gastrocnemius flaps (cause-specific HR 7.1 [95% CI 1.4 to 33.0]; p = 0.02) were associated with the increased risk of knee subluxation, whereas age at operation ≤ 9 years was associated with the increased risk of severe LLD (≥ 4 cm) (cause-specific HR 7.3 [95% CI 3.7 to 25.0]; p = 0.002).

CONCLUSION

For skeletally immature patients with proximal tibial sarcomas, proximal tibial hemiarthroplasty appears to be a reasonable alternative to the standard rotating-hinge megaprosthesis, especially for pediatric patients age 10 years and older. This reconstruction can preserve the distal femoral epiphyseal growth capacity and thus potentially reduces final LLD. Moreover, patient age, skeletal maturity, implant availability, technical expertise, and surgeon preference should be considered when choosing a reconstructive approach after proximal tibial resection in children with osteosarcoma. This study did not compare pediatric patients treated with extendable prostheses. Future studies should consider direct comparisons between the two types of prosthetic reconstruction.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Lengthening the Transfemoral Amputation Stump Using Vascularized Flap From Amputated Limb: A Case Report

CASE

A 10-year-old male patient was diagnosed with osteosarcoma and initially underwent prosthetic reconstruction following an extra-articular resection. Local recurrence with extensive neurovascular invasion necessitated the decision to perform a transfemoral amputation. To maximize functional outcome through lengthening the stump, a tibial osseocutaneous vascularized flap from the amputated limb was integrated into amputation stump, utilizing plate-and-screw fixation. At the final follow-up, the patient was independently ambulatory using a custom-made prosthesis.

CONCLUSION

We present a patient operated with a novel technique to increase transfemoral amputation stump length for recurrent osteosarcoma by using an osseocutaneous flap reconstruction.

Custom-made semi-joint prosthesis replacement combined ligament advanced reinforcement system (LARS) ligament reconstruction for the limb salvage surgery of malignant tumors in the distal femur in skeletal immature children

Purpose

To explore the application of Custom-made Semi-joint prosthesis replacement combined with Ligament Advanced Reinforcement System (LARS) ligament reconstruction for the limb salvage surgery (LSS) of malignant tumors in the distal femur and provide selections for the LSS of malignant tumors in skeletal immature children.

Methods

A total of 8 children with malignant tumors in the distal femur who underwent Custom-made Semi-joint prosthesis replacement combined LARS ligament reconstruction for LSS from January, 2018 until December, 2019 in our bone and soft tissue tumor center were retrospectively recruited. The prosthesis related complications, oncological prognosis and knee function were observed, and the surgical efficacy was comprehensively evaluated.

Results

The average follow-up time was 36.6 months (30-50 months). The average osteotomy length was 13.2 cm (8-20 cm) according to the preoperative imaging results and the length of the customized prosthesis. Two years after operation, the average MSTS-93 score was 24.4 (16-29) which indicated good limb functions. The range of motion of the knee was 0°-120°, with an maximum average of 100°. At last follow-up, the average height of the children increased by 8.4 cm (6-13 cm), and the average limb shortening was 2.7 cm (1.8-4.6 cm). One patient had wound complications in the early postoperative period, wound scab fell off to form superficial ulcer, in whom debridement and suturing were performed. One patient developed hematogenous disseminated prosthesis infection 2 years after surgery, and the prosthesis is now in situ with anti-infection treatment. One patient developed pulmonary metastasis during follow-up, and received chemotherapy and targeted therapy with lesion well controlled. At the last follow-up, there was no local tumor recurrence or prosthesis loosening.

Conclusion

Under the premise of appropriate case selection, customized semi-joint prosthesis replacement combined with LARS ligament reconstruction provides a new option for LSS in children with distal femur malignant tumors. LARS ligament reconstruction ensures the stability and range of motion of the knee joint, which maximally preserves the epiphysis of the tibia side and the growth function of the tibia side, reduces the complications of limb length inequality in the long term and creates conditions for limb lengthening or total joint replacement in adults.

Preserving the rectus femoris and improving limb function after total femoral prosthesis replacement following resection of femoral malignant tumors

Background

Current research is focused on the factors that influence the maintenance of limb function after total femoral replacement. This retrospective study investigated the difference in functional outcomes in patients with invasion of the rectus femoris vs. an intact rectus femoris that underwent total femoral replacement with a modular total femur prosthesis.

Methods

The medical records of patients who underwent total femoral replacement with a modular total femur prosthesis between July 2010 and March 2017 at our institute were retrospectively reviewed. The patients were divided into two groups: group A had invasion of the rectus femoris and group B had an intact rectus femoris. Functional status was assessed using the Musculoskeletal Tumor Society Rating Scale (MSTS) and the Harris Hip Score (HHS). Complications were assessed using the International Society of Limb Salvage classification that was published in 2011 and modified in 2014.

Results

The mean total MSTS score (23.0 ± 4.8 vs. 17.6 ± 3.1; P = 0.02) and the mean total HHS score (80.17 ± 6.24 vs. 55.38 ± 13.30; P = 0.001) were significantly higher in patients with intact rectus femoris compared with patients with invasion of the rectus femoris. Patients with an intact rectus femoris achieved significantly better limb function (support and gait) and active range of motion (P &lt; 0.05). The overall complication rate was 35.7%.

Conclusions

Functional outcomes after total femoral replacement were significantly better in patients with an intact rectus femoris compared with patients with invasion of the rectus femoris, possibly because more muscle mass can be preserved around the femur in patients with an intact rectus femoris.

Survival and failure modes of the Compress® spindle and expandable distal femur endoprosthesis among pediatric patients: A multi‐institutional study

BACKGROUND

Expandable endoprostheses can be used to equalize limb length for pediatric patients requiring reconstruction following large bony oncologic resections. Outcomes of the Compress® Compliant Pre-Stress (CPS) spindle paired with an Orthopedic Salvage System expandable distal femur endoprosthesis have not been reported.

METHODS

We conducted a multi-institutional retrospective study of pediatric patients with distal femoral bone sarcomas reconstructed with the above endoprostheses. Statistical analysis utilized Kaplan-Meier survival technique and competing risk analysis.

RESULTS

Thirty-six patients were included from five institutions. Spindle survivorship was 86.3% (95% confidence interval [CI], 67.7-93.5) at 10 years. Two patients had a failure of osseointegration (5.7%), both within 12 months. Twenty-two (59%) patients had 70 lengthening procedures, with mean expansions of 3.2 cm (range: 1-9) over 3.4 surgeries. The expandable mechanism failed in eight patients with a cumulative incidence of 16.1% (95% CI, 5.6-31.5) at 5 years. Twenty-nine patients sustained International Society of Limb Salvage failures requiring 63 unplanned surgeries. Periprosthetic joint infection occurred in six patients (16.7%). Limb preservation rate was 91% at 10 years.

CONCLUSIONS

There is a high rate of osseointegration of the Compress® spindle among pediatric patients when coupled with an expandable implant. However, there is a high rate of expansion mechanism failure and prosthetic joint infections requiring revision surgery.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

A Cryoprotectant-Gel Composite Designed to Preserve Articular Cartilage during Frozen Osteoarticular Autograft Reconstruction for Malignant Bone Tumors: An Animal-Based Study

OBJECTIVE

We designed a highly adhesive cryoprotectant-gel composite (CGC), based on regular liquid-form cryoprotectant base (CB), aiming to protect cartilage tissue during frozen osteoarticular autograft reconstruction for high-grade sarcoma around the joint. This study aimed to evaluate its effectiveness in rat and porcine distal femur models.

DESIGN

Fresh articular cartilage samples harvested from distal rat and porcine femurs were divided into 4 test groups: untreated control group, liquid nitrogen (LN) freezing group, LN freezing group pretreated with CB (CB group), and LN freezing group pretreated with CGC (CGC group). Microscopic and macroscopic evaluation of cartilage condition, TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling) assay, and apoptotic protein analysis of chondrocytes were performed to confirm our results.

RESULTS

In the rat model, CGC could prevent articular cartilage from roughness and preserve more proteoglycans when compared with the LN freezing and CB groups. Western blot analysis showed CGC could prevent cartilage from LN-induced apoptosis supported by caspase-3/8 apoptotic signaling cascade. Macroscopically, we observed CGC could reduce both articular clefting and loss of articular luminance after freezing in the porcine model. In both models, CGC could reduce articular chondrocytes from degeneration. Fewer TUNEL-positive apoptotic and more viable chondrocytes in cartilage tissue were observed in the CGC group in our animal models.

CONCLUSION

Our study proved that CGC could effectively prevent cartilage surface and chondrocytes from cryoinjury after LN freezing. Freezing articular cartilage surrounded with high concentration of CGC can be a better alternative to preserve articular cartilage during limb salvage surgery for malignant bone tumor.

Multidisciplinary Approach to Hemipelvectomy for Pelvic Sarcomas

» Pelvic sarcomas are a rare and diverse group of tumors in terms of size and histology.» Pelvic sarcomas present a treatment challenge to the orthopaedic oncologist.» The size and location of these tumors require a varied approach to resection and reconstruction, but the tumor's proximity to other internal structures within the pelvis (e.g., the bladder, the iliac vessels, and the bowel) makes extrication demanding.» The ideal treatment requires assembling a hemipelvectomy team that consists of an orthopaedic oncologist, a surgical oncologist, a urologist, a vascular surgeon, a gynecologic oncologist, a plastic and reconstructive surgeon, a dedicated anesthesia team, and a dedicated rehabilitation physical therapy team. Each member can use his or her expertise to address the individual aspects of the pelvic resection and achieve the optimal oncologic and functional outcome.

Lower Limb Reconstruction Using Tibial Strut Autograft after Resection of Primary Malignant Bone Tumors in Skeletally Immature Patients

Background

Reconstruction of large bone defects in skeletally immature patients remains a surgical challenge. We report the long-term clinical outcomes of a novel surgical technique for lower limb reconstruction using the tibia as a strut autograft following resection of primary malignant bone tumors in skeletally immature patients.

Methods

We retrospectively reviewed the medical records of six patients diagnosed with lower limb primary bone sarcoma. All patients underwent tumor resection and reconstruction using tibial strut autograft. The radiological and clinical outcomes including complications at the recipient and donor sites were assessed.

Results

The mean age at presentation was ten years (range 6-15 years). Two cases had osteosarcoma and four had Ewing sarcoma. The mean length of the resected tumor and tibial autografts were 20.83 and 19.33 cm respectively. Union at both ends was achieved in five grafts while one graft achieved union only at the distal end. The mean time for union of the proximal and distal junctions was 4 and 8.8 months respectively. The mean follow-up period was 8.4 years (range 14 months-20 years). One patient developed a foot drop, and three patients underwent subsequent joint arthrodesis (2 knees and 1 ankle). The mean musculoskeletal tumor society functional score was 80.8%. Two patients had clinically significant leg-length discrepancy that needs further lengthening procedure. Four patients survived with no evidence of disease and two patients died due to their primary oncologic disease. All donor sites regenerated, with the earliest signs of new bone formation at (2-4) weeks post-operatively.

Conclusion

Reconstruction using non-vascularized‎ tibia strut autograft after resection of primary malignant lower limb bone tumors can be a viable alternative method for reconstructing large bone defects in the immature skeleton.

Is Use of BMP-2 Associated with Tumor Growth and Osteoblastic Differentiation in Murine Models of Osteosarcoma?

BACKGROUND

The putative benefit of rhBMP-2 is in the setting of limb reconstruction using structural allografts, whether it be allograft-prosthetic composites, osteoarticular allografts, or intercalary segmental grafts. There are also potential advantages in augmenting osseointegration of uncemented endoprosthetics and in reducing infection. Recombinant human BMP-2 might mitigate nonunion in structural allograft augmented osteosarcoma limb salvage surgery; however, its use is limited because of concerns about the prooncogenic effects of the agent.

QUESTIONS/PURPOSES

(1) To assess if BMP-2 signaling influences osteosarcoma cell line growth. (2) To characterize degree of osteosarcoma cell line osteoblastic differentiation in response to BMP-2. (3) To assess if BMP-2 signaling has a consistent effect on local or systemic tumor burden in various orthotopic murine models of osteosarcoma.

METHODS

In this study, 143b, SaOS-2 and DLM8-M1 osteosarcoma cell lines were transfected with BMP-2 cDNA controlled by a constitutive promoter (experimental) or an empty vector (control) using a PiggyBac transposon system. Cellular proliferation was assessed using a quantitative MTT colorimetric assay. Osteoblastic differentiation was compared between control and experimental cell lines using quantitative real-time polymerase chain reaction of the osteoblastic markers connective tissue growth factor, Runx-2, Osterix, alkaline phosphatase and osteocalcin. Experimental and control cell lines were injected into the proximal tibia of either NOD-SCID (143b and SaOS-2 xenograft model), or C3H (DLM8-M1 syngeneic model) mice. Local tumor burden was quantitatively assessed using tumor volume caliper measurements and bioluminescence, and qualitatively assessed using post-mortem ex vivo microCT. Lung metastasis was qualitatively assessed by the presence of bioluminescence, and incidence was confirmed using histology. rhBMP-2 soaked absorbable collagen sponges (experimental) and sterile-H2O soaked absorbable collagen sponges (control) were implanted adjacent to 143b proximal tibial cell line injections to compare the effects of exogenous BMP-2 application with endogenous upregulation.

RESULTS

Constitutive expression of BMP-2 increased the in vitro proliferation of 143b cells (absorbance values 1.2 ± 0.1 versus 0.89 ± 0.1, mean difference 0.36 [95% CI 0.12 to 0.6]; p = 0.01), but had no effect on SaOS-2 and DLM8-M1 cell proliferation. In response to constitutive BMP-2 expression, 143b cells had no differences in osteoblastic differentiation, while DLM8-M1 cells downregulated the early marker connective tissue growth factor (mean ΔCt 0.2 ± 0.1 versus 0.6 ± 0.1; p = 0.002) and upregulated the early-mid range marker Runx-2 (mean ΔCt -0.8 ± 0.1 versus -1.1 ± 0.1; p = 0.002), and SaOS-2 cells upregulated the mid-range marker Osterix (mean ΔCt -2.1 ± 0.6 versus -3.9 ± 0.6; p = 0.002). Constitutive expression of BMP-2 resulted in greater 143b and DLM8-M1 local tumor volume (143b: 307.2 ± 106.8 mm versus 1316 ± 387.4 mm, mean difference 1009 mm [95% CI 674.5 to 1343]; p < 0.001, DLM8-M1 week four: 0 mm versus 326.1 ± 72.8 mm, mean difference 326.1 mm [95% CI 121.2 to 531]; p = 0.009), but modestly reduced local tumor growth in SaOS-2 (9.5 x 10 ± 8.3x10 photons/s versus 9.3 x 10 ± 1.5 x 10 photons/s, mean difference 8.6 x 10 photons/s [95% CI 5.1 x 10 to 1.2 x 10]; p < 0.001). Application of exogenous rhBMP-2 also increased 143b local tumor volume (495 ± 91.9 mm versus 1335 ± 102.7 mm, mean difference 840.3 mm [95% CI 671.7 to 1009]; p < 0.001). Incidence of lung metastases was not different between experimental or control groups for all experimental conditions.

CONCLUSIONS

As demonstrated by others, ectopic BMP-2 signaling has unpredictable effects on local tumor proliferation in murine models of osteosarcoma and does not consistently result in osteosarcoma cell line differentiation. Further investigations into other methods of safe bone and soft tissue healing augmentation and the use of differentiation therapies is warranted.

CLINICAL RELEVANCE

Our results indicate that BMP-2 has the potential to stimulate the growth of osteosarcoma cells that are poorly responsive to BMP-2 mediated osteoblastic differentiation. As this differentiation potential is unpredictable in the clinical setting, BMP-2 may promote the growth of microscopic residual tumor burden after resection. Our study provides further support for the recommendation to avoid the use of BMP-2 after limb-salvage surgery in patients with osteosarcoma.

Preservation of the Epiphysis and Growth Plate in the Surgical Management of Femoral Osteosarcoma in a Skeletally Immature Patient by Intercalary Resection and Biological Reconstruction: A Case Report

Osteosarcoma arises most frequently in the metaphysis around the knee and its management by limb salvage surgery in skeletally immature pediatric patients is extremely challenging. Common reconstructive methods such as endoprosthetic or biological reconstruction are not fully capable of dealing with durability-related and growth-related problems and their functional outcomes are not as good as those seen in adult cases. A definitive limb salvaging procedure in children that outperforms amputation or rotationplasty has not yet been established. Herein, we report a case of stage IV osteosarcoma in the femur of a 7-year-old boy that was safely managed with intercalary resection preserving the distal femoral growth plate and epiphysis, followed by biological reconstruction using a frozen tumor-devitalized autograft. Good response to preoperative chemotherapy and the diaphyseal location of the tumor enabled us to perform a tumor resection that spared the growth plate and preserved the native knee joint structure. Plate fixation over the growth plate was terminated by removing the locking screws in the epiphysis after 44 months, which restored growth capacity to some extent. At 50 months postoperatively, no recurrence or progression of the disease was observed. The patient uses an extension shoe and reports having little discomfort in his daily life despite having a restricted range of motion and limb length discrepancy. In conclusion, limb salvage with biological reconstruction in skeletally immature patients can provide an acceptable functional outcome, including minimized limb length discrepancy, if critical damage to the growth plate and articular components can be avoided.