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.

Topographic matching of distal radius and proximal fibula articular surface for distal radius osteoarticular reconstruction

During osteoarticular reconstruction of the distal radius with the proximal fibula, congruity between the two articular surfaces is an important factor in determining the quality of the outcome. In this study, a three-dimensional model and a coordinate transformation algorithm were developed on computed tomography scanning. Articular surface matching was performed and parameters for the optimal position were determined quantitatively. The mean radii of best-fit spheres of the articular surfaces of the distal radius and proximal fibula were compared quantitatively. The radial inclination and volar tilt following reconstruction by an ipsilateral fibula graft, rather than the contralateral, best resembles the values of the native distal radius. Additionally, the ipsilateral fibula graft reconstructed a larger proportion of the distal radius articular surface than did the contralateral. The ipsilateral proximal fibula graft provides a better match for the reconstruction of the distal radius articular surface than the contralateral, and the optimal position for graft placement is quantitatively determined.

Osteoarticular reconstructive surgery in malignant bone tumors: the importance of external fixators

This paper is a retrospective study on 8 patients admitted and treated in Paediatric Surgery and Orthopaedics Clinic of "M. S. Curie" Hospital Bucharest between 1997 and 2007. The patients with malignant bone tumors (table 1.) were studied by sex, tumor type, location, age at the moment of diagnosis, age at the moment of the last evaluation, type of surgery, external fixator implanted, complications, results and survival period. We also considered for each patient the extent of the tumor to diaphysis, soft tissue involvement, involvement of physis and epiphyseal invasion, articular extent, vessels and nerves invasion, presence of metastases and local skin invasion. The certain diagnosis was based on pathological anatomy exam, because clinical and imagistic data were not decisive in each case. There were studied only those patients who received external fixators, the only method to achieve oncological safe resection and osteoarticular recontruction. We used monoplanar or circular fixators, in adjustable or mixed mountings. The postoperative complications were not fatal. The survival period has been between 6 months and 18 years. Only two patients, who have survived 6 months and respectively 18 months, were not able to return to prior activities. The other six were reinserted in social activities. Nowadays, there is made a great effort to save the affected limbs. The conservative treatment is preferred to the amputation, which is being used in very few cases. The development of reconstructive bone surgery is sustained by the possibility to delineate the tumor by diagnosis based on imaging and by the possibility to use modern preoperative and postoperative chemotherapy and radiotherapy. Limb conservation was possible only in aggressive benign tumors up to 1970. Since then the same treatment was preferred also in malignant bone tumors, because the relapse appeared as frequent as in cases with amputation but the physical and psychological comfort made the patients to accept it readily. The goal of malignant bone tumors treatment is to save the life of the patient, to preserve the affected limb, to maintain the length and function of the limb. Oncologic surgery consists of "en bloc" tumor resection followed by bone reconstruction or modular prosthetic replacement. Modular prosthetic replacement leads to the loss of at least one growing cartilage. The use of radiotherapy in some cases may also affect other growing cartilages, leading to limb length discrepancies.