Pseudarthrosen

Experimental model of normotrophic pseudarthrosis of a rabbit’s tibia

Background. The formation of a pseudarthrosis is one of the most severe complications of bone fractures. Pseudarthrosis occurs as a result of a disorder in the fracture union, has a poor prognosis and requires long-term treatment and repeated surgeries. A small number of representative pseudarthrosis models makes it difficult to conduct preclinical studies of promising pharmacological substances, bone replacement materials and surgical methods of treatment.The aim. To develop and to validate an experimental model of normotrophic pseudarthrosis of a rabbit’s tibia by creating diastasis between bone fragments, forming local vascularization disturbance and using unstable fixation.Materials and methods. The study was carried out on Soviet Chinchilla rabbits. The animals were divided into 2 groups: in experimental group, we formed tibial pseudarthrosis; in control group, we made a simple transverse tibial fracture. The pseudarthrosis was formed by segmental resection (5 mm) of the middle third of the tibia, bone fragments dilatation for 5 mm, removal of periosteum and bone marrow within 5 mm followed by daily destabilization of a fracture in an external fixation device. The duration of the experiment was 6 weeks. X-ray examination of the fracture area was carried out weekly, multi-layer spiral computed tomography (MSCT) and histological examinations were carried out at the end of the experiment.Results. The survival value in the experiment was 100 %. According to weekly X-ray examination, fracture union was registered only in the control group and occurred on average on the 22,8 ± 5,1 day, while the formation of pseudarthrosis was observed only in the experimental group, and radiographic signs of a pseudarthrosis were noted on average on the 33,6 ± 3,5 day. The formation of a pseudarthrosis by the end of the experiment was confirmed by MSCT and histological studies.Conclusions. The developed model of the normotrophic pseudarthrosis of a rabbit’s tibia can be used for experimental tests of various factors for stimulating reparative regeneration and methods for treatment of the pseudarthrosis.

[Synthetic bone replacement substances]

Bone substitute materials have been successfully used for bone defects in orthopedics and trauma surgery for a long time; however, there are cases, especially in bone defects with a critical size, in which the treatment is complicated. Nowadays, multiple bone substitute materials are available. Autologous cancellous bone grafts remain the gold standard among the bone replacement materials; however, donor site morbidity and the limited availability of autologous cancellous bone represent restrictions for autologous bone grafting. Allogeneic cancellous bone grafts have also been successfully for years in the treatment of bone defects; however, infection rates of more than 10% have been described for the use of allogeneic cancellous bone. By introducing synthetic bone substitutes further alternatives are currently available to the user for the individual treatment of bone defects. The aim of this study is to demonstrate the advantages and disadvantages of various synthetic bone substitute materials.

A case report of upper limb loss of substance: Use of functional gracilis free flap, brachioradialis transposition and bioglass for bone regeneration

Complex trauma of the upper limb is a common consequence of involvement in serious accidents. Loss of substance including nerve, bone, tendons and vascular defects are challenging surgical issues. A 27- year-old male presented with complex upper limb trauma and loss of a proximal third of the posterior forearm structure as well as loss of active finger extension, ulnar and radial nerve territory anesthesia and ulnar fracture. A composite nerve-tendon-muscle-skin gracilis free flap was retrieved from the contralateral leg, related to tendon transfer of BR to ELP, to supply active hand extension. The patient was required to adhere to intensive post-surgical rehabilitation and monitored for a 3-year follow-up period. Our assessment revealed adequate skin trophism and sufficient muscle strength recovery against resistance (M5). The functional flap associated with tendon transfer was considered an efficient procedure for the management of a complex trauma with loss of posterior interosseous nerve and bone exposition. The free re-innervated gracilis flap may be used to repair complex soft tissue defects with exposed bone and to restore finger extension following severe forearm injuries.