Anatomic reduction and internal fixation of diaphyseal forearm fractures in adults is considered the treatment of choice to achieve final goal of union and restoration of the limb functions as similar as possible to the prefracture status.This study tries to assess the clinical effectiveness of a new forearm intramedullary nail system (The Be. Te. Forearm Intramedullary Nail System) which offers improved biological and biomechanical features.The study started with brief reference to the anatomical facts of the forearm bones stressing upon certain anatomical considerations including: the radial bow with its crucial importance on the range of forearm motions, the styloid process of ulna with the attached triangular fibrocartilage complex. Anatomy of the interosseous membrane and its functions regarding prevention of proximal migration of radius when the radial head excised, transmission of forces from the radius distally to the ulna proximally in addition to its function in hinge mechanism for rotatory motion of the forearm had been inferred.Biomechanics of the forearm had been described. The axis of pronation-supination (from the center of the radial head to the base of styloid ulna), the forearm anatomical axis (extends from mid-point between epicondyles of humerus and mid-point between styloid processes of radius and ulna) and the relation between them had been discussed.Biomechanics of intramedullary fixation had been shortly discussed. There are two principals of medullary fixation (gliding which includes: flexible intramedullary implants and rigid implants and non-gliding one referred as interlocking system). To characterize the mechanical behavior of an implant and its secondary effect on bone healing, the material from which it is fabricated, the loads imposed on the implant and the geometric features of both the implant and the fracture must be put in consideration. The major features that influence the strength of fixation of intramedullary implant within bone (implant-bone fixation) are: the material and structural properties of the implant, the loads applied to bone-implant construct and the fracture geometry. A brief discussion of the mechanical bases of bone healing had been expressed.The art of internal fixation of fractures utilizing various implants has undergone important and basic changes. Two major approaches are well known to be used for surgical fixation of fractures: The conventional approach depends upon the rigid fixation of fractures and the direct bone healing and the biological approach considering the importance of preservation of soft tissues and careful protection of bone fragments and their vascularity. Intramedullary nailing as a method fixation of diaphyseal fractures of forearm has many advantages including : Minimal surgical trauma, avoiding periosteal stripping, preservation of fracture haematoma in closed nailing technique, fewer loads were put on the implant and more loads afforded on the surrounding cortical bone, early mobilization of the affected limb and lower incidence of refracture after nail removal.Reviewing the literature regarding the use of intramedullary fixation in forearm fractures had been mentioned. Various implants had been used including: K-wires, Steinman pins and Rush pins. Also, the evolution of nails utilized in forearm fractures had been mentioned including: Street nail (1957), Sage nail (1959), Hackethal bundle nailing (1959), Von-Saal square nail (1961), Schneider nail (1971), ForeSight nail (1995) and variable designs of locked nails.The mechanism of injury of the forearm fractures and the causative trauma either direct or indirect had been declared. The study shifted to the clinical and radiological diagnosis of the fractures with a brief hint about the new modalities of investigations as magnetic resonance imaging and computerized scanning.Regarding the patients of the study, 103 adult patients (166fractures) with diaphyseal fractures of the forearm bones were dealt with and they constituted the material of the study.63 patients with both forearm bones fractures.10 patients with radial shaft fractures.30 patients with ulnar shaft fractures.Patients were classified according to their age, sex, fracture type (closed or open), causative trauma, fracture configuration and location and associated injuries.The management of the fractures started with the diagnosis both clinical and radiological and management of the closed fractures. It was followed by managing certain problems as: open fractures, Galeazzi fracture-dislocation and Monteggia fracture. Full description of the Be. Te. Intramedullary Forearm Nail System had been discussed. At the same time the advantages and tactics of application of the new intramedullary nailing were explained as a method of internal fixation of forearm fractures. The technical steps of reduction and intramedullary nailing of the fractures were discussed. The post-operative care of closed fractures included no immobilization in 71% of cases, posterior slab and orthosis in 19% and long arm cast in 10% of the closed fracture cases. Open fracture cases (18 cases) managed by meticulous debridment, copious irrigation with sterile saline and stabilization of the fracture by intramedullary nailing. Post-operative management included: Antibiotic regimen and immobilization in light soft dressing (56%), above elbow posterior slab, orthotic device (22%) and a long-arm cast (22%).The results of the study had been assessed utilizing a special scheme of evaluation consisted of eight parameters:1- Pain. 2- Union. 3-Range of motion.4- Deformity. 5- Infection. 6- Grip strength.7- Ability to work. 8- Bone - Implant construct failure.The study ended with the following results:Excellent: 65 cases (63.1%).Good: 21 cases (20.4%).Fair: 9 cases (8.7%).Poor: 8 cases (7.8%).Some complications developed in our study including: Infection, delayed-union, non-union, malunion, nerve injury (posterior interosseous and superficial branch of radial nerve), implant-bone disproportion and failure to achieve proper stability of fractures. The rate of complications was similar to many previous studies.The final results of the study had been analyzed and compared with results of other similar studies. The total ”Excellent” and ”Good” cases were 86 cases (83.5%) and if the ”Fair” results - which were considered as ”satisfactory” results in other studies - were added, the net functional result would be 92.2% which is similar to - and might be higher than - other studies.ConclusionsAnatomical reduction and internal fixation of diaphyseal fractures of the forearm in adults is mandatory to achieve a satisfactory functional result. The use of intramedullary nailing particularly the closed technique is a preferred method for internal fixation because of: minimal surgical exposure, less scarring and disfigurement, lowered risk of infection, lower risk of soft tissue injury, less risk of refracture after implant removal and minimal period of convalescence.The use of intramedullary nailing in closed and some open (Grade I, GradeII and GradeIIIA) diaphyseal fractures of the forearm is recommended as evidenced by the results of the present study.