Are Pasteurized Autografts Durable for Reconstructions After Bone Tumor Resections?

Frozen inactivated autograft replantation for bone and soft tissue sarcomas

Background

The frozen inactivation of autologous tumor bones using liquid nitrogen is an important surgical method for limb salvage in patients with sarcoma. At present, there are few research reports related to frozen inactivated autograft replantation.

Methods

In this study, we retrospectively collected the clinical data of patients with bone and soft tissue sarcoma treated with liquid nitrogen-frozen inactivated tumor bone replantation, and analyzed the safety and efficacy of this surgical method. The healing status of the frozen inactivated autografts was evaluated using the International Society of Limb Salvage (ISOLS) scoring system. Functional status of patients was assessed using the Musculoskeletal Tumor Society (MSTS) scale.

Results

This study included 43 patients. The average length of the bone defect after tumor resection is 16.9 cm (range 6.3-35.3 cm). Patients with autograft not including the knee joint surface had significantly better healing outcomes (ISOLS scores) (80.6% ± 15% vs 28.2% ± 4.9%, P<0.001) and limb function (MSTS score) (87% ± 11.6% vs 27.2% ± 4.4%, P<0.001) than patients with autografts including the knee joint surface. The healing time of the end of inactivated autografts near the metaphyseal was significantly shorter than that of the end far away from the metaphyseal (9.8 ± 6.3 months vs 14.9 ± 6.3 months, P=0.0149). One patient had local recurrence, one had an autograft infection, five (all of whom had an autograft including the knee joint surface) had joint deformities, and seven had bone non-union.

Conclusion

Frozen inactivated autologous tumor bone replantation is safe and results in good bone healing. But this method is not suitable for patients with autograft involving the knee joint surface.

Feasibility of a Novel In-situ Local Tumor Ablation and Recycling Machine Based on Radiofrequency Dielectric Heating: In-depth Review on Research Background and Preliminary Report of an Experimental Study

Background

In bone sarcomas, chemotherapy has improved the prognosis with advances in diagnostic and surgical technologies, which has led to attempts to save limbs. As early detection and multidisciplinary treatment have improved the survival rate, curative surgery is considered for selected patients with metastatic bone carcinomas. Limb salvage procedures may vary in relation to the reconstruction method, which is accompanied by different complications. To overcome them, we devised a novel concept, in-situ local tumor ablation and recycling machine based on radiofrequency (RF)-induced heating and intended experiments to demonstrate its feasibility.

Methods

The fresh femurs of 6-month-old pigs were used after removing the epiphyses; the distal parts were placed in a heating chamber. Fiber-optic temperature sensors were inserted in the metaphysis, meta-diaphysis, and diaphysis. Temperatures were measured six times each during heating at 27.12 MHz at various powers. Additionally, the compressive and bending stiffnesses were measured six times each for the unprocessed, RF-treated, and pasteurized bones, and the results were compared.

Results

Under 200 W power output, the temperatures at all measurement sites reached 70 ℃ or higher in 6 minutes, and the temperatures were maintained. The median compressive stiffness of RF-heated bones was 79.2% higher than that of pasteurized bones, but the difference was statistically insignificant. The median bending stiffness of RF-heated bones was approximately 66.3% of that of unprocessed bones, which was 20% higher than that of pasteurized bones.

Conclusions

The feasibility to rapidly attain and maintain temperatures for tumor ablation is shown, which favorably preserves bone stiffness through the in-situ local tumor ablation and recycling based on RF heating. The problem of nonuniform temperature distribution might be solved by an optimal design determined from simulation research and additional experiments.

Complications and Outcome of Bone Sarcoma Patients with Limb Salvage using Liquid Nitrogen-treated Bone for Reconstruction

Introduction

The recommended treatment method for bone sarcoma is wide local excision and reconstruction to preserve limb function. Established methods of reconstruction are mega prosthesis or biological reconstruction. This study aimed to determine the complications and functional outcomes associated with limb salvage surgery using liquid nitrogen-treated bone.

Materials and Methods

We retrospectively observed the short-term outcome of limb salvage surgeries where liquid nitrogen bone was used for reconstruction. A total of 15 patients underwent reconstruction with liquid nitrogen auto graft from January 2018 to December 2020. We used the free freezing method of liquid nitrogen treatment after wide local excision of sarcoma. We observed short-term outcomes after liquid nitrogen-treated bone reconstruction in limb salvage surgery. Survival of the auto grafts was recorded using the Kaplan-Meier method with a 95% confidence interval.

Results

The mean follow-up was 19.83 ± 4.5 months. The mean musculoskeletal tumor society score was 62.4 ± 7.9%, while the average Toronto extremity score was 59.6 ± 5.7%. Three patients died during the study duration due to visceral metastasis. Skin necrosis and wound breakdown were major complications in 9 (60%) patients. Deep infection was observed in 4 (26.7%). Similarly, 4 (26.7%) patients had non-union at either the proximal or distal osteotomy site, while the average time of bone union in the rest of the patients was 6.3 ± 1.7 months. A total of 6 (40%) patients underwent reoperation after liquid nitrogen treatment, either due to infection or non-union at the osteotomy site. Recurrence was observed in 3 (20%) of patients.

Conclusion

We observed a high complication rate with liquid nitrogen-treated autograft reconstruction. Vascularized fibula with liquid nitrogen-treated autograft or endoprosthesis should be encouraged.

A comparative study of reconstruction modalities after knee joint-preserving tumor resection: reconstruction with a custom-made endoprosthesis versus reconstruction with a liquid nitrogen-inactivated autologous bone graft

BACKGROUND

This study evaluated the feasibility, complications, graft survival rate, and clinical outcomes of joint-preserving resection using a custom-made endoprosthesis and liquid nitrogen-inactivated autologous bone graft reconstruction in patients with malignant bone tumors around the knee joint.

METHODS

We retrospectively analyzed 23 consecutive patients who underwent joint preservation surgery between 2008 and 2018 at our center. The study cohort included 13 patients who underwent custom-made endoprosthesis reconstruction and 10 who underwent liquid nitrogen-inactivated autologous bone graft reconstruction. The resected bone length, distance between the resection line and the joint, intraoperative blood loss, operation time, complications, and MSTS were compared between the two groups.

RESULTS

The median follow-up time was 68.5 months in the endoprosthesis group and 65.3 months in the inactivated autograft group. There were no significant differences in baseline characteristics, resected bone length, distance between the resection line and the joint, or intraoperative blood loss between the two groups. The operative time was longer in the inactivated bone graft group than in the endoprosthesis group (p < 0.001). The endoprosthesis group had more complications (six patients) and reoperations due to complications (five) than the inactivated autograft group (one), but there was no significant difference in the incidence of complications between the two groups (p = 0.158). The inactivated autograft group had one patient with type 1b complications, while the endoprosthesis group had one with type 1b complications, one with type 2b complications, and one with type 4a complications. One patient in the endoprosthesis group with type 5a complications experienced two soft tissue recurrences. The overall 5-year survival rate was 86.5% and the graft survival and final limb salvage rates were 100% in both groups. After the follow-up period, the mean MSTS scores were 91% ± 7% in the endoprosthesis group and 94% ± 6% in the inactivated autograft group, with no significant difference (p = 0.280).

CONCLUSION

Joint-preserving resection is a reliable and effective tumor resection method that can achieve good postoperative function. There were no significant differences in the incidence of complications, overall survival rate, or graft survival rate between the two groups.

What Are the Complications, Function, and Survival of Tumor-devitalized Autografts Used in Patients With Limb-sparing Surgery for Bone and Soft Tissue Tumors? A Japanese Musculoskeletal Oncology Group Multi-institutional Study

BACKGROUND

Tumor-devitalized autografts treated with deep freezing, pasteurization, and irradiation are biological reconstruction methods after tumor excision for aggressive or malignant bone or soft tissue tumors that involve a major long bone. Tumor-devitalized autografts do not require a bone bank, they carry no risk of viral or bacterial disease transmission, they are associated with a smaller immunologic response, and they have a better shape and size match to the site in which they are implanted. However, they are associated with disadvantages as well; it is not possible to assess margins and tumor necrosis, the devitalized bone is not normal and has limited healing potential, and the biomechanical strength is decreased owing to processing and tumor-related bone loss. Because this technique is not used in many countries, there are few reports on the results of this procedure such as complications, graft survival, and limb function.

QUESTIONS/PURPOSES

(1) What was the rate of complications such as fracture, nonunion, infection, or recurrence in a tumor-devitalized autograft treated with deep freezing, pasteurization, and irradiation, and what factors were associated with the complication? (2) What were the 5-year and 10-year grafted bone survival (free from graft bone removal) of the three methods used to devitalize a tumor-containing autograft, and what factors were associated with grafted bone survival? (3) What was the proportion of patients with union of the tumor-devitalized autograft and what factors were associated with union of the graft-host bone junction? (4) What was the limb function after the tumor-devitalized autograft, and what factors were related to favorable limb function?

METHODS

This was a retrospective, multicenter, observational study that included data from 26 tertiary sarcoma centers affiliated with the Japanese Musculoskeletal Oncology Group. From January 1993 to December 2018, 494 patients with benign or malignant tumors of the long bones were treated with tumor-devitalized autografts (using deep freezing, pasteurization, or irradiation techniques). Patients who were treated with intercalary or composite (an osteoarticular autograft with a total joint arthroplasty) tumor-devitalized autografts and followed for at least 2 years were considered eligible for inclusion. Accordingly, 7% (37 of 494) of the patients were excluded because they died within 2 years; in 19% (96), an osteoarticular graft was used, and another 10% (51) were lost to follow-up or had incomplete datasets. We did not collect information on those who died or were lost to follow-up. Considering this, 63% of the patients (310 of 494) were included in the analysis. The median follow-up was 92 months (range 24 to 348 months), the median age was 27 years (range 4 to 84), and 48% (148 of 310) were female; freezing was performed for 47% (147) of patients, pasteurization for 29% (89), and irradiation for 24% (74). The primary endpoints of this study were the cumulative incidence rate of complications and the cumulative survival of grafted bone, assessed by the Kaplan-Meier method. We used the classification of complications and graft failures proposed by the International Society of Limb Salvage. Factors relating to complications and grafted autograft removal were analyzed. The secondary endpoints were the proportion of bony union and better limb function, evaluated by the Musculoskeletal Tumor Society score. Factors relating to bony union and limb function were also analyzed. Data were investigated in each center by a record review and transferred to Kanazawa University.

RESULTS

The cumulative incidence rate of any complication was 42% at 5 years and 51% at 10 years. The most frequent complications were nonunion in 36 patients and infection in 34 patients. Long resection (≥ 15 cm) was associated with an increased risk of any complication based on the multivariate analyses (RR 1.8 [95% CI 1.3 to 2.5]; p < 0.01). There was no difference in the rate of complications among the three devitalizing methods. The cumulative graft survival rates were 87% at 5 years and 81% at 10 years. After controlling for potential confounding variables including sex, resection length, reconstruction type, procedure type, and chemotherapy, we found that long resection (≥ 15 cm) and composite reconstruction were associated with an increased risk of grafted autograft removal (RR 2.5 [95% CI 1.4 to 4.5]; p < 0.01 and RR 2.3 [95% CI 1.3 to 4.1]; p < 0.01). The pedicle freezing procedure showed better graft survival than the extracorporeal devitalizing procedures (94% versus 85% in 5 years; RR 3.1 [95% CI 1.1 to 9.0]; p = 0.03). No difference was observed in graft survival among the three devitalizing methods. Further, 78% (156 of 200 patients) of patients in the intercalary group and 87% (39 of 45 patients) of those in the composite group achieved primary union within 2 years. Male sex and the use of nonvascularized grafts were associated with an increased risk of nonunion (RR 2.8 [95% CI 1.3 to 6.1]; p < 0.01 and 0.28 [95% CI 0.1 to 1.0]; p = 0.04, respectively) in the intercalary group after controlling for confounding variables, including sex, site, chemotherapy, resection length, graft type, operation time, and fixation type. The median Musculoskeletal Tumor Society score was 83% (range 12% to 100%). After controlling for confounding variables including age, site, resection length, event occurrence, and graft removal, age younger than 40 years (RR 2.0 [95% CI 1.1 to 3.7]; p = 0.03), tibia (RR 6.9 [95% CI 2.7 to 17.5]; p < 0.01), femur (RR 4.8 [95% CI 1.9 to 11.7]; p < 0.01), no event (RR 2.2 [95% CI 1.1 to 4.5]; p = 0.03), and no graft removal (RR 2.9 [95% CI 1.2 to 7.3]; p = 0.03) were associated with an increased limb function. The composite graft was associated with decreased limb function (RR 0.4 [95% CI 0.2 to 0.7]; p < 0.01).

CONCLUSION

This multicenter study revealed that frozen, irradiated, and pasteurized tumor-bearing autografts had similar rates of complications and graft survival and all resulted in similar limb function. The recurrence rate was 10%; however, no tumor recurred with the devitalized autograft. The pedicle freezing procedure reduces the osteotomy site, which may contribute to better graft survival. Furthermore, tumor-devitalized autografts had reasonable survival and favorable limb function, which are comparable to findings reported for bone allografts. Overall, tumor-devitalized autografts are a useful option for biological reconstruction and are suitable for osteoblastic tumors or osteolytic tumors without severe loss of mechanical bone strength. Tumor-devitalized autografts could be considered when obtaining allografts is difficult and when a patient is unwilling to have a tumor prosthesis and allograft for various reasons such as cost or socioreligious reasons.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Graft Survivals after Reconstruction Using Tumor-Bearing Frozen Bone in the Extremities

Tumor-bearing frozen autografts have been widely used for reconstruction of bone defects caused by tumor resection. However, some patients undergo removal of the grafted bone due to surgical site infection, tumor recurrence, or fractures of the grafted bone. In this retrospective cohort study, predictive factors for graft survival were investigated in 123 patients who underwent reconstructions using a tumor-bearing frozen autograft after bone tumor resection of the extremities. To determine the independent predictors of graft survival, the association between various parameters and graft survival was investigated. The graft survival rates were 83.2% at 5 years and 70.2% at 10 years. Among the 123 frozen autografts, 25 (20.3%) were removed because of complications. In univariate analyses, male sex, BMI of ≥23.6, tibia, and chemotherapy were significantly associated with poor graft survival, whereas the pedicle/hemicortical freezing procedure was significantly associated with better graft survival. Multivariate analysis using the Cox proportional hazards regression model revealed that BMI of ≥23.6 (HR, 3.4; p = 0.005), tibia (HR, 2.3; p = 0.047), and freezing procedure (HR, 0.3; p = 0.016) were independently associated with graft survival. Based on the results, pedicle or hemicortical freezing techniques are recommended in cases where these techniques can be applied.

Biological reconstruction of bone defect after resection of malignant bone tumor by allograft: a single-center retrospective cohort study

BACKGROUND

Allograft reconstruction following the resection of malignant bone tumors is associated with high rates of complications and failures. This study aimed to evaluate the efficacy and current problems of allograft reconstruction techniques to optimize treatment strategies at our center.

MATERIALS AND METHODS

Thirty-eight cases (16 men and 22 women), who were diagnosed with malignant bone tumors and had undergone allograft reconstruction, were recruited. Allograft was fixed by intramedullary nail, single steel plate, double plate, and intramedullary nail combined plate in 2, 4, 17, and 15 cases, respectively. Allograft union, local recurrence, and complications were assessed with clinical and radiological tests. Tumor grade was assessed using the Enneking staging of malignant bone tumors. Functional prognosis was evaluated by the Musculoskeletal Tumor Society (MSTS) scoring system.

RESULTS

Intercalary and osteoarticular reconstructions were performed in 32 and 6 cases, respectively. Six patients underwent reoperation related to allograft complications, four patients had local recurrence, and three patients with allograft fracture underwent allograft removal. A total of eight host-donor junctions showed nonunion, including seven cases (18.4%) in diaphysis and one case (3.1%) in metaphysis (p < 0.01). Host rejection and secondary osteoarthritis occurred in nine and two cases, respectively. No deep infection and internal fixation device fracture occurred. The overall allograft survival rate was 81.6%. Postoperative MSTS score of patients with allograft survival was 26.8 ± 2.9, indicating a significant improvement as compared to their preoperative function.

CONCLUSIONS

Allograft represents an excellent choice for intercalary bone defects after malignant bone tumor resection. Robust internal fixation protection across the whole length of the allograft is an important prerequisite for the survival of the allograft, while multidimensional osteotomy, intramedullary cement reinforcement, and pedicled muscle flap transfer can effectively improve the survival rate and healing rate of the allograft.

Factors affecting the incorporation of extracorporeally irradiated autograft for the treatment of bone tumours-a retrospective analysis from a tertiary referral centre

PURPOSE

Re-implantation of the tumor bearing autograft following extracorporeal radiation therapy (ECRT) has been established as an oncologically safe biological reconstruction technique following resection of bone sarcomas. However, factors affecting the ECRT graft-host bone incorporation have not been fully investigated. An insight into the factors that influence graft incorporation can circumvent the complications and increase graft survival.

METHODS

A total of 96 osteotomies in 48 patients with intercalary resections of primary extremity bone sarcomas (mean age 15.8 years, mean follow-up 42.1 months) were analyzed retrospectively for factors ECRT autograft-host bone union.

RESULTS

On univariate analysis, age < 20 years, metaphyseal osteotomy site, V-shaped diaphyseal osteotomy, and use of additional plate at diaphyseal osteotomy had a significantly faster time to union, while gender, tumour type, bone involved, resection length, chemotherapy, type of fixation, and use of intra-medullary fibula did not influence union time. In multivariate analysis, V-shaped diaphyseal osteotomy and use of additional plate at diaphyseal ostetomy were the independent factors with favourable time to union. None of the analyzed factors was found to have a significant effect on the union rate. The major complications were non-union in 11.4% patients, graft failure in 2.1%, infection in 12.5%, and soft tissue local recurrences in 14.5% patients.

CONCLUSION

Modified diaphyseal osteotomy and augmentation of the stability of the reconstruction using additional small plates enhance the incorporation of ECRT autograft.

Joint-preservation surgery for bone sarcoma in adolescents and young adults

Bone sarcoma often occurs in childhood, as well as in adolescents and young adults (AYAs). AYAs differ from pediatric patients in that their bone is skeletally mature and the physis has almost disappeared with the completion of growth. Although AYAs spend less time outside, they often participate in sports activities, as well as driving, working, and raising a family, which are natural activities in daily living. Multidisciplinary approaches involving imaging, multi-agent chemotherapy, surgical procedures, and careful postoperative care has facilitated an increase in limb-sparing surgery for bone sarcoma. In addition, recent advances in imaging modalities and surgical techniques enables joint-preservation surgery, preserving the adjacent epiphysis, for selected patients following the careful assessment of the tumor margins and precise tumor excision. An advantage of this type of surgery is that it retains the native function of the adjacent joint, which differs from joint-prosthesis replacement, and provides excellent limb function. Various reconstruction procedures are available for joint-preserving surgery, including allograft, vascularized fibula graft, distraction osteogenesis, and tumor-devitalized autografts. However, procedure-related complications may occur, including non-union, infection, fracture, and implant failure, and surgeons should fully understand the advantages and disadvantages of these procedures. The longevity of the normal limb function for natural activities and the curative treatment without debilitation from late toxicities should be considered as a treatment goal for AYA patients. This review discusses the concept of joint-preservation surgery, types of reconstruction procedures associated with joint-preservation surgery, and current treatment outcomes.

A Viability Analysis of Tumor-Bearing Frozen Autograft for the Reconstruction After Resection of Malignant Bone Tumors Using 99m Tc-MDP Scintigraphy

PURPOSE OF THE REPORT

Several methods are used to reconstruct bony defects after malignant tumor excision. Tumor-bearing frozen autograft reconstruction is a biological procedure in which tumor-bearing bone is reused after devitalization with liquid nitrogen to kill tumor cells. The viability of frozen autografts has not been fully evaluated over time. We therefore aimed to evaluate the viability of devitalized bone grafts, using 99m Tc-MDP scintigraphy.

PATIENTS AND METHODS

Seventy-four patients who underwent frozen autograft reconstruction after the excision of a malignant bone tumor were enrolled. Two hundred forty-two postoperative 99m Tc-MDP scans were reviewed. For a quantitative analysis, the region of interest on the frozen bone segment and a symmetric region of interest on the contralateral normal area were manually set. The radioactive tracer uptake ratio was calculated by dividing the count density of the frozen bone segment by that of the contralateral normal area in each image. An uptake ratio of 0.9 to 1.1 was defined as a normalization of tracer uptake.

RESULTS

Normalization of tracer uptake was achieved in 95% to 97% of the cases by 60 months postoperatively, and earlier in the middle zone and peripheral zone in the pedicle freezing group in comparison to the free freezing group (both P = 0.03). Fracture and nonunion was associated with a low uptake ratio, whereas infection was associated with a high uptake ratio before the occurrence of the event.

CONCLUSIONS

The calculation of the uptake ratio using 99m Tc-MDP scans was an objective and accurate evaluation method. The period to normalization of tracer uptake in the pedicle frozen bone was significantly earlier than that in the free frozen bone. The postoperative complications can be also predicted.

Factors Influencing Nonunion and Fracture Following Biological Intercalary Reconstruction for Lower-Extremity Bone Tumors: A Systematic Review and Pooled Analysis

OBJECTIVES

To determine nonunion rate, fracture rate, and their risk factors following biological intercalary reconstruction for lower extremity bone tumors.

METHODS

A systematic review and pooled analysis were conducted. PubMed, Embase, and Wiley Cochrane Library were searched from inception up to June 01, 2020. Studies concerning biological intercalary reconstruction after resection of lower extremity bone tumors were included. Overall nonunion and fracture rates were calculated. For studies reporting patient outcomes individually with precise graft characteristics and fixation methods, the individual data were extracted. Patients with demographical and clinical characteristics, including age, sex, tumor location, graft characteristics, and fixation method, were pooled for a multivariate analysis. For each factor of interest, odds ratio (OR), 95% confidence interval (95% CI), and p-value from logistic regression were reported.

RESULTS

A total of 2776 articles were identified from the initial literature search and 76 studies (2052 patients) were included. Sixty-nine studies were case series and seven were comparative studies. The overall nonunion rate was 19% (382/2052; range: 0%-53%), and the overall fracture rate was 17% (344/2052; range: 0%-75%). Thirty of the 76 studies (362 patients) reported patients' characteristics individually and were thus included in the pooled multivariate analysis. Intramedullary nail fixation was associated with a significantly higher nonunion rate compared to plate fixation (OR = 2.2, 95% CI: 1.23-4.10, p = 0.009). Reconstruction with a vascularized fibula graft had a statistically non-significant lower nonunion rate than reconstruction without the graft (OR = 0.6, 95% CI: 0.34-1.07, p = 0.086). Devitalized autografts had a lower fracture risk than allografts (OR = 0.3, 95% CI: 0.14-0.64, p = 0.002), and males tended to have higher fracture risk than females (OR = 2.1, 95% CI: 1.00-4.44, p = 0.049).

CONCLUSIONS

Reconstruction with intramedullary nail fixation is related to an elevated risk of nonunion. Allografts and males have a higher fracture risk than devitalized autografts and females, respectively. Further high-quality comparative analyses with large sample sizes and adequate follow-up duration are needed to validate these findings.

Surgical Site Infection after Bone Tumor Surgery: Risk Factors and New Preventive Techniques

The management of malignant bone tumors requires multidisciplinary interventions including chemotherapy, radiation therapy, and surgical tumor resection and reconstruction. Surgical site infection (SSI) is a serious complication in the treatment of malignant bone tumors. Compared to other orthopedic surgeries, the surgical treatment of malignant bone tumors is associated with higher rates of SSIs. In patients with SSIs, additional surgeries, long-term administrations of antibiotics, extended hospital stays, and the postponement of scheduled adjuvant treatments are required. Therefore, SSI may adversely affect functional and oncological outcomes. To improve surgical outcomes in patients with malignant bone tumors, preoperative risk assessments for SSIs, new preventive techniques against SSIs, and the optimal use of prophylactic antibiotics are often required. Previous reports have demonstrated that age, tumor site (pelvis and tibia), extended operative time, implant use, body mass index, leukocytopenia, and reconstruction procedures are associated with an increased risk for SSIs. Furthermore, prophylactic techniques, such as silver and iodine coatings on implants, have been developed and proven to be efficacious and safe in clinical studies. In this review, predictive factors of SSIs and new prophylactic techniques are discussed.

Compressive Strength Characteristics of Long Tubular Bones after Hyperthermal Ablation

Thermoablation is used in the treatment of tumorous bones. However, little is known about the influence such thermal treatment has on the mechanical properties of bone tissue. The purpose of this work was to study the influence of thermal treatment in a range of 60–100 °C (in increments of 10 °C) on the structural properties of pig femurs using an original approach that involved a periosteal arrangement of heating elements providing gradual dry heating of the bone from its periphery to its center. Heating of freshly extracted bone tissue segments was performed ex vivo using surface heaters of a Phoenix-2 local hyperthermia hardware system. Mechanical testing followed the single-axis compression scheme (traverse velocity of 1 mm/min). In the 60–90 °C range of heating, no attributes of reduced structural characteristics were found in the samples subjected to thermoablation in comparison to the control samples taken from symmetric areas of adjacent cylinders of healthy bones and not subjected to heat treatment. The following statistically significant changes were found as a result of compressing the samples to 100 °C after the heat treatment: reduced modulus of elasticity and increased elastic strain (strain-to-failure), mainly due to increases in plastic deformation. This finding may serve as evidence of a critical ex vivo change in the biomechanical behavior of bone tissues at such temperatures. Thus, ex vivo treatment of bone tissue in the thermal range of 60–90 °C may be used in studies of thermoablation efficiency against tumor involvement of bones.

Does Local Zoledronate Applied to Pasteurized Bone Autografts Improve the Likelihood of Union of Graft-Host Junctions after Limb-sparing Surgery?

BACKGROUND

Pasteurized bone autograft is a recycling biological reconstruction method for limb-sparing surgery when an allograft or other reconstruction technique is unavailable. Since the application of a local bisphosphonate to morselized allografts can reduce graft resorption and enhance bone formation without systemic complications, adding the local bisphosphonate to pasteurized bone autografts should reduce the graft resorption and improve the graft incorporation to host bone. However, no study that we know of has described the outcomes of local bisphosphonate application to massive allografts or pasteurized bone autografts. Thus, this study compared the outcomes of pasteurized bone autografts with and without local zoledronate.

QUESTIONS/PURPOSES

(1) What is the survival of pasteurized bone autografts and what complications lead to graft removal? (2) Does treatment of pasteurized bone autografts with zoledronate alter the survival of pasteurized bone autografts compared with grafts without treatment? (3) Does the local application of zoledronate reduce the proportion of patients with fractures because of metaphyseal graft resorption? (4) Does local application of zoledronate improve union at the graft-host bone junction compared with untreated grafts?

METHODS

Between July 2011 and December 2019, we performed 538 musculoskeletal bone tumor resections. Of these, 101 patients underwent reconstruction with pasteurized bone autografts. Other reconstructions included tumor prostheses (150 patients), allografts (70 patients), reconstruction using a bone cement-plate construct (62 patients), and resection only (155 patients). We generally used pasteurized bone autograft when tumors showed an osteoblastic pattern, had less than one-third cortical destruction, and less than half of metaphyseal bone destruction. Six percent (6 of 101) were lost to follow-up, 6% (6 of 101) had incomplete clinical data, and 16% (16 of 101) had a follow-up period less than 2 years without an event, leaving 73 patients for evaluation. The median (interquartile range) age of the patients was 18 years (15 to 26). Ninety-seven percent (71 of 73) had a diagnosis of bone sarcoma. The median follow-up time was 46 months (33 to 75). From 2011 to 2014, 21 pasteurized bone autografts were prepared without local zoledronate, and from 2014 to 2019, 52 pasteurized bone autografts were prepared with local zoledronate because we thought it might improve union and reduce resorption of the graft. From our tumor registry database, we obtained age, sex, use of chemotherapy, graft length and location, pasteurized bone graft type, fixation methods, the use of local zoledronate, osteotomy gap, complications, proportion of grafts that united by 2 years, and local recurrences. Curves for graft survival were determined using the Kaplan-Meier method with the endpoint of autograft removal and metaphyseal fracture from graft resorption. The probabilities of graft removal were estimated by cumulative incidences using the competing risk analysis, where death was considered as the competing event. Intergroup differences in survival and multivariable analyses were performed using the log-rank test and a Cox regression analysis. A logistic regression model was used to evaluate the association between graft-host osseous union by 2 years and other baseline factors. Union was defined when a callus was seen to bridge the osteotomy line for at least three cortices in both the AP and mediolateral planes.

RESULTS

The 5-year survival rate of all 73 pasteurized grafts was 85% (95% confidence interval 74% to 92%). With the numbers available, we found no difference in the 5-year survival rates between grafts with and without local zoledronate (90% [95% CI 78% to 96%] versus 74% [95% CI 48% to 89%]; p = 0.30). Eleven percent (8 of 73) of patients had metaphyseal fractures because of graft resorption, primarily associated with osteoarticular grafts (5-year fracture-free survival 56% [95% CI 20 to 80]) rather than pasteurized graft-prosthesis composites (94% [95% CI 78% to 98%]) and intercalary grafts (91% [95% CI 50 to 99]; p = 0.001); there was no association with the use of local zoledronate (13%; 7 of 52) compared with those without local zoledronate (5%; 1 of 21) (odds ratio 3.1 [95% CI 0.4 to 27]; p = 0.43). Of the 84 graft-host bone junctions, 85% (71) of the grafts unified within 2 years, 7% (6) unified after 2 years, and 8% (7) of grafts showed nonunion. Union within 2 years was associated with fixation using plate compared with those with stem and with both stem and plate (odds ratio 6.6 [95% CI 1.4 to 31]; p = 0.02) and grafts treated with local zoledronate compared with those without treatment (OR 5.9 [95% CI 1.3 to 28]; p = 0.02).

CONCLUSION

The application of local zoledronate to pasteurized bone autografts for limb-sparing surgery improved the likelihood of graft union compared with untreated grafts, especially when the osteotomy junctions were fixed using plate osteosynthesis, but it did not appear to alter the proportion of patients who experience metaphyseal fracture of the grafts because of graft resorption. Although this is a small study, it suggests that the treatment of pasteurized bone autografts and perhaps bone allografts should be studied further to determine whether bisphosphonates or other adjuncts can improve the union time and return to function in patients undergoing bone tumor resections using these reconstruction types.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Strategies for large bone defect reconstruction after trauma, infections or tumour excision: a comprehensive review of the literature

Large bone defects resulting from musculoskeletal tumours, infections, or trauma are often unable to heal spontaneously. The challenge for surgeons is to avoid amputation, and provide the best functional outcomes. Allograft, vascularized fibular or iliac graft, hybrid graft, extracorporeal devitalized autograft, distraction osteogenesis, induced-membrane technique, and segmental prostheses are the most common surgical strategies to manage large bone defects. Given its optimal osteogenesis, osteoinduction, osteoconduction, and histocompatibility properties, along with the lower the risk of immunological rejection, autologous graft represents the most common used strategy for reconstruction of bone defects. However, the choice of the best surgical technique is still debated, and no consensus has been reached. The present study investigated the current reconstructive strategies for large bone defect after trauma, infections, or tumour excision, discussed advantages and disadvantages of each technique, debated available techniques and materials, and evaluated complications and new perspectives.

Clinical outcomes of frozen autograft reconstruction for the treatment of primary bone sarcoma in adolescents and young adults

Age affects the clinical outcomes of cancer treatment, including those for bone sarcoma. Successful reconstruction using frozen autograft after excision of bone sarcoma has been reported; however, little is known about the clinical outcomes of frozen autograft reconstruction according to age. The purpose was to evaluate the clinical outcomes of the frozen autograft reconstruction focusing on skeletally mature adolescents and young adults (AYAs) that was 15 to 39 years of age. A total of 37 AYA patients with primary bone sarcoma on the appendicular skeleton were enrolled in this study. The mean follow-up period was 89 months. The graft survival (GS), overall survival (OS), recurrence-free survival (RFS), complications and the function were retrospectively evaluated using medical records. The 10-year GS, OS, and RFS rates were 76%, 84%, and 79%, respectively. Bone union was achieved with a rate of 94% within 1 year after surgery, and nonunion (n = 1) and fracture (n = 2) were infrequently observed. Graft removal was performed in 7 cases, and the most common reason for the removal was infection (n = 5). The Musculoskeletal Tumor Society score was excellent in 23 cases of the available 29 cases. Frozen autograft reconstruction for AYAs showed excellent clinical outcomes, although the long-term follow-up is required.

Devitalized Autograft Associated with the Vascularized Fibula Graft: Irradiation versus Freezing Methods

BACKGROUND

 Among the alternatives for the management of malignant bone tumors is the "devitalized autograft associated with vascularized fibula graft." The devitalization process is achieved by pasteurization, irradiation, or freezing. The combination of these grafts has been broadly researched for more than 25 years. However, there is no research currently published comparing the various methods or their respective outcomes.

METHODS

 A retrospective study was compiled of 26 devitalized autografts associated with vascularized fibula performed to limb salvage of malignant bone tumors. They were divided into two groups according to the devitalization method: either freezing (12 procedures) or irradiation (14 procedures). Clinical, radiographic, and scintigraphic results were assessed at least 24 months after surgery.

RESULTS

 The union rates reached 83.3% in the freezing group and 92.8% in the irradiated group but did not express different outcomes. Scintigraphic viability was observed in all the grafts that achieved radiographic union (Mann-Whitney U-test: p = 0.005). Three patients had nonunion, with only one having no viability in the scintigraphy (Mann-Whitney U-test: p = 0.001). There was no malignant recurrence in the autograft, only in surrounding soft tissues. Local recurrence was statistically higher in larger tumors (Mann-Whitney U-test: p = 0.025).

CONCLUSION

 Both groups presented similar union rates and are considered safe to devitalize bone graft despite different outcomes observed. The survivor rates observed could be limited by the existence of the techniques.

Salvage Reconstruction With the Masquelet Technique Following Wide Resection for Chondrosarcoma of the Proximal Femoral Metaphysis: A Case Report

BACKGROUND

Bone reconstruction following a wide resection for a malignant musculoskeletal tumor remains challenging, especially for an intercalary defect following the resection of a metaphyseal lesion.

CASE REPORT

Here, we describe a surgical procedure using the Masquelet technique for the biological reconstruction of a huge subtrochanteric bone defect following failed pasteurized autologous bone grafting for a conventional chondrosarcoma of the proximal femoral metaphysis with a subtrochanteric pathological fracture. The patient, a 43-year-old Japanese male, was able to walk without a cane or a brace at 15 months after the final operation (International Society of Limb Salvage score, 86.7%).

CONCLUSION

This procedure should be considered as one of the reconstruction options following the wide resection of malignant bone tumors located in the metaphysis.

What Are the Challenges and Complications of Sterilizing Autografts with Liquid Nitrogen for Malignant Bone Tumors? A Preliminary Report

BACKGROUND

Reconstruction of defects after resection of malignant bone tumors with liquid nitrogen-sterilized recycled autografts is an alternative to bone allografts and endoprostheses in resource-constrained environments. Most studies reporting favorable outcomes with liquid nitrogen-sterilized autografts for bone reconstruction are geographically restricted to a few countries, and the technical challenges of routinely using liquid nitrogen intraoperatively, especially when using the pedicle freezing technique, has not been documented.

QUESTIONS/PURPOSES

(1) What are the technical challenges of liquid nitrogen sterilization of bone tumors for inexperienced surgeons? (2) What are the complications associated with the procedure?

METHODS

Between May 2017 and October 2019, 88 patients underwent limb salvage procedures for malignant bone tumors of the extremities at our institution. An endoprosthesis was used for reconstruction of the defect following resection in 45% (40 of 88) of these patients, mostly in adults (median age 21 years; range 9 to 68). In the remaining 55% (48 of 88) of patients undergoing biological reconstruction, liquid nitrogen-sterilized autograft was used in 90% (43 of 48), extracorporeal irradiation-sterilized autograft was used in 4% (2 of 48) and allograft was used in 6% (3 of 48). Of the 43 patients receiving liquid nitrogen-sterilized autograft, 5% (2 of 43) were excluded due to loss to follow-up and the remaining 95% (41 of 43) were included for the analysis. Liquid nitrogen-sterilized autograft was the preferred method of reconstruction at our institution during the study period, unless the patient had an indication for prosthesis reconstruction; extracorporeal irradiation-sterilized autograft was used due to resource constraints with liquid nitrogen and allograft was used when patients insisted.All surgical procedures were performed by the same team of trained orthopaedic oncology surgeons. The medical records of the included 41 patients were retrieved using an institutional database search in this retrospective study, and all were used to ascertain technical challenges associated with the operations as well as early (within 3 weeks of the index procedure) and late complications (those occurring 3 weeks or more after surgery). The technical challenges were defined as follows: the quantity of liquid nitrogen to be used; arranging, storing and handling of liquid nitrogen in the operating room, type and size of the container to be used for sterilization, the positioning of the container during pedicle freezing, level of fibular osteotomy for pedicle freezing of tibia, soft tissue protection, limb rotation during pedicle freezing, managing tourniquet time, and any other intraoperative factors with the use of liquid nitrogen for sterilizing the autograft. As our experience with the technique gradually grew, the answers to the above-mentioned factors were determined. Considering the removal of autograft as the endpoint of interest, survival of the autograft was determined by Kaplan-Meier analysis.The median (range) patient age was 14 years (2 to 49), and 54% (22 of 41) were males. Osteosarcoma was the most common diagnosis (68%, [28 of 41]) followed by Ewing's sarcoma (20%, [8 of 41]). On presentation, 27% of patients (11 of 41) had radiological evidence of pulmonary metastasis. Tumors were seen frequently around the knee (39% [16 of 41] proximal tibia and 22% [9 of 41] distal femur). Before resection 85% (35 of 41) underwent neoadjuvant chemotherapy. Sixty-six percent (27 of 41) underwent pedicle-freezing and the remaining 34% (14 of 41) underwent free-freezing of the tumor segment of the bone. The median (range) duration of surgery was 280 minutes (210 to 510). The patients were followed up for a median (range) duration of 21 months (5 to 30); two patients were lost to follow-up.

RESULTS

With gradual experience using liquid nitrogen-sterilization over time at our institution, we determined that the following factors helped us in performing liquid nitrogen-sterilization more efficiently. For every operation 15 L to 20 L of unsterilized liquid nitrogen was arranged, 1 or 2 days before the procedure, and stored in industrial-grade cryocylinders in the operating complex. During the procedure, the operating surgeons wore additional plastic aprons under the surgical gowns, surgical goggles, and rubber boots. The staff managing the liquid nitrogen in the operating room wore thermal protective gloves. For most of the pedicle freezing procedures, we used a cylindrical stainless-steel container that was 30 cm in height and 15 cm in diameter, with a narrow opening. The container was kept on a separate moveable cart that was placed next to the operating table at a slightly lower level, and it was wrapped in multiple cotton rolls, plastic sheets, surgical sheets, and a crepe bandage. For pedicle freezing of the tibia, we performed the fibular osteotomy at least 5 cm away from the planned surgical margin, roughly around the axis of rotation of the limb. The soft tissue at the base of the delivered bone segment was dissected for at least 5 cm beyond the planned surgical margin of bone, and was protected with multiple layers of cotton rolls, plastic drapes, a single roll of Esmarch and crepe bandage. The tumor segment was externally rotated during pedicle freezing for all anatomic sites (proximal tibia, distal tibia, proximal humerus, and proximal femur). The tourniquet was inflated just before pedicle freezing to prevent tumor dissemination and not before the initial incision in all pedicle freezing procedures.Thirty-nine percent of patients (16 of 41) experienced complications associated with the procedures, and 15% (6 of 41) underwent revision surgery. Early complications (occurring within 3 weeks of the index procedure) were skin necrosis in four of 16 patients, intraoperative fracture in one of 16, superficial infection in one of 16, and neurapraxia in one of 16 patients. Late complications (occurring 3 weeks or more after surgery) were resorption of the recycled bone in four of 16 patients, nonunion of the osteotomy site in two of 12, delayed union of the osteotomy site in one of 16, collapse of the recycled bone in one of 16, and local recurrence in 1 of 16 patients. Kaplan-Meier survivorship free from removal of autograft at 2 years after surgery was 92% (95% confidence interval 89 to 96).

CONCLUSION

Liquid nitrogen-sterilization is an alternative technique that requires some training and experience for the surgeon to become proficient in treating primary malignant bone tumors. Because it is widely available, it may be an option worth exploring in resource-constrained environments, where allografts and endoprostheses cannot be procured. The methods we developed to address the technical challenges will require more study and experience, but we believe these observations will aid others who may wish to use and evaluate liquid nitrogen sterilization of extremity bone sarcomas.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Bone defect reconstruction with autologous bone inactivated with liquid nitrogen after resection of primary limb malignant tumors: An observational study

Surgical treatment of malignant bone tumors comprises tumor resection and reconstruction. The most commonly used reconstruction method is prosthesis replacement, which achieves good early function, but has a high long-term incidence of complications. Another reconstruction option is autologous bone replantation, which has the advantages of anatomical matching and no need for large bone bank support. Few studies have evaluated reconstruction with liquid nitrogen-inactivated autogenous bone.The present study aimed to evaluate the oncological results, bone healing results, complications, and indications of reconstruction with liquid nitrogen-inactivated autogenous bone grafts.The study population comprised 21 consecutive patients. The tumor site was the tibia in 9 cases, femur in 8, and humerus in 4. There were 37 osteotomy ends in total. After freezing and rewarming, the medullary cavity of the autogenous bone was filled with antibiotic bone cement. Seventeen patients received bilateral plate fixation, 2 received intramedullary nail and distal plate fixation, and 2 received single plate fixation.The average follow-up was 31 ± 6 months. Eighteen patients survived without tumors, and the 3-year survival rate was 80.4%. All cases had adequate surgical margins, but recurrence developed in 1 patient. Metastasis occurred in 3 patients, who all died of metastasis. Intraoperative inactivated bone fracture occurred in 1 patient, and screw breakage was found in 1 patient. Nonunion occurred at 1 humeral diaphysis osteotomy site, and 1 patient was lost to follow-up; the average healing time of the other 35 ends was 13 ± 6 months, and the bone healing rate was 97.2%. The average bone healing times in the metaphysis and diaphysis were 9 ± 3 months and 15 ± 6 months (P = .003). The average bone healing times in the upper and lower limbs were 16.6 ± 7.4 months and 12.3 ± 5.8 months (P = .020). The average Muscle and Skeletal Tumor Society score was 28 ± 3 (21-30) in the 18 survivors.Liquid nitrogen-inactivated autologous bone replantation for primary malignant limb tumor was safe and effective, as shown by the relatively low complication rate, high bone healing rate, and satisfactory postoperative function. This is a reliable biological reconstruction method for malignant bone tumors with specific site and bone destruction characteristics.

A long-term follow-up study of extracorporeal irradiated autografts in limb salvage surgery for malignant bone and soft tissue tumors: A minimum follow-up of 10 years after surgery

BACKGROUND AND OBJECTIVES

The aim of this study is to assess the survival, function, radiographic appearance, and modes of failure of extracorporeal irradiated (ECI) autografts in a long-term setting.

METHODS

We retrospectively reviewed 87 patients who were treated for bone and soft tissue tumors using ECI autografts between 1988 and 2009.

RESULTS

The 56 patients had a minimum follow-up of 10 years, and the median follow-up period was 16.5 years. The reimplantation procedures included 24 osteoarticular grafts, 16 intercalary grafts, 10 autograft-prosthetic composite grafts, and 6 hemicortical grafts. The 15-year graft and event-free survival rates were 76.8% and 47.9%, respectively. Infection and structural failure were the most common reasons for additional surgery. The time for additional surgery was significantly longer in patients with composite grafts (P < .01). The median Musculoskeletal Tumor Society score and the International Society of Limb Salvage score were 80% and 84%, respectively.

CONCLUSIONS

ECI autografts are a durable option for reconstruction after resection of musculoskeletal tumors and provide good function over more than 15 years. Most graft failures occurred within 5 years of the index surgery. However, composite grafts showed a tendency to fail more than 10 years after the surgery.

BMP9 promotes osteogenic differentiation of SMSCs by activating the JNK/Smad2/3 signaling pathway

Synovial mesenchymal stem cells (SMSCs) with high proliferation and multi differentiation ability, and low immunogenicity have attracted research attention for their potential application in tissue engineering. Once their ability of osteogenesis is strengthened, it will be of practical value to apply the SMSCs in the field of bone regeneration. The current study aimed to investigate the osteogenic characteristics of SMSCs induced by bone morphogenetic protein 9 (BMP9) both in vitro and in vivo and to elucidate the mechanism underlying these characteristics. Specifically, different BMPs were assessed to determine the protein that would be the most favorable for stimulating osteogenic differentiation of SMSCs following their separation. The BMP9-enhanced osteogenesis of SMSCs was fully investigated in vitro and in vivo, and the c-Jun N-terminal kinase (JNK)/Smad2/3 signaling pathway stimulated by BMP9 was further explored. Our data suggested that BMP9 could significantly promote gene and protein expression of runt-related transcription factor 2, alkaline phosphatase, osteopontin, and osteocalcin, and SP600125, a JNK-specific inhibitor, could effectively decrease this tendency. Similar results were also confirmed in rats with cranial defects. In conclusion, our study indicated that BMP9 promotes bone formation both in vitro and in vivo possibly by activating the JNK/Smad2/3 signaling pathway.