The mechanical effects of extracorporeal irradiation on bone

Inactivation and replantation of the knee joint: an infeasible surgical method

BACKGROUND

The inactivation and replantation of autologous tumor bones are important surgical methods for limb salvage in patients with malignancies. Currently, there are few reports on the inactivation and replantation of the knee joint. In this study, we aimed to evaluate the feasibility of our surgical approach.

METHODS

This is a retrospective case series study. We retrospectively collected the clinical data of patients with sarcoma treated with knee joint inactivation and replantation and analyzed the efficacy of this surgical method. The bone healing and complications in these patients after inactivated autograft replantation were assessed.

RESULTS

This study included 16 patients. Fifteen patients had osteosarcoma, and one had Ewing's sarcoma. The average length of the inactivated bone is 20.2 cm (range 13.5-25.3 cm). All the patients underwent internal plate fixation. The average follow-up duration was 30 months (range 8-60 months). Before the data deadline of this study, eight (50%) patients were still alive, and eight (50%) died of sarcoma metastasis. Eight (50%) patients achieved bone healing at the diaphysis site of the inactivated tumor bone, with an average bone healing time of 21.9 months (range, 12-36 months). Five (31%) patients died due to metastases and did not achieve bone healing. Two (12.5%) patients did not achieve bone healing because of infection, and one (6.3%) patient underwent amputation due to tumor recurrence. Ten (62.5%) patients experienced fractures around the joint ends of the inactivated replanted bone, and eight of these ten patients were combined with joint dislocation.

CONCLUSION

The incidence of joint deformities after the knee-joint inactivation and replantation is extremely high and is not recommended for use.

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.

Extracorporeal radiation and reimplantation: a safe and viable option for reconstruction after sacral tumor resection?

Primary tumors of the sacrum are difficult to manage, as they often require morbid resections and complex reconstructions. In the case of tumors such as chordoma or chondrosarcoma, aggressive resections are often required to achieve appropriate margins (extending disease-free survival), followed by complex reconstructions. These reconstructions are aimed at restoring the pelvic ring and have traditionally resulted in a lumbosacral construct that utilizes structural allograft/autograft bone (fibula most commonly used) and more recently, reconstruction with 3D-printed custom sacral prostheses. While there are no reports of anatomical reconstruction using sacral allografts, extracorporeal radiation therapy (ECRT) and reimplantation provides a size and shape-matched irradiated autograft which avoids the cultural stigma, structural strength and graft-host concerns associated with allografts, as well as the high costs and time to production associated with custom 3D-printed implants. Here we present an illustrative case with technical notes, outlining the steps used at our center for ECRT. While early results with ECRT in the sacrum are promising, future larger studies should be carried out to help detect differences that may exist in long-term complications.