Analysis of the Impact of Configuration of the Stabilisation System for Femoral Diaphyseal Fractures on the State of Stresses and Displacements.

INTRODUCTION: The treatment of femoral diaphyseal fractures by intramedullary nailing has become a common procedure in orthopaedic surgery. The purpose of this numerical simulation was to present how the changes in configuration of the stabilisation system can affect the stress and displacement state in the bone tissue and implanted device. MATERIAL AND METHODS: The numerical comparison of the stabilisation variants for the type 32-A2 femoral diaphyseal fracture (according to the AO classification) performed by using the Charfix2 (ChM®) anatomical nail locked in a number of chosen ways. The displacement and the stress distributions both in the bone and implant were obtained and analysed by computational simulation. RESULTS: In all models, there was the same characteristic distribution, which shows there were minimal rotational movements of the bone around the anatomical axis. In all cases, stress concentrations were generated in the nail material in the area of the fracture gap. CONCLUSIONS: The obtained results indicate that there is a visible advantage to one-plane distal stabilisation in the reduction of stresses regardless of the type of proximal stabilisation. The results of calculations indicate that the use of proximal stabilisation with a neck screw reduces the possibility of damage to the implant.

Complication of a Femoral Fracture Treated by Intramedullary Nailing - Numerical Analysis of a Clinical Case.

The aim of this paper is to conduct a numerical analysis of a case of femoral fracture treated by intramedullary nailing and confirm the conditions which led to the formation of a pseudarthrosis at the fracture site. A low-energy femoral fracture was treated by placing a ChFN System intramedullary nail with a derotation pin. Using the finite element method, a bone-implant system was generated which made it possible to observe the displacement area and strains in the region of the fracture gap. The calculations were conducted for 3 variants of the model, using a titanium nail (10 mm and 12 mm) and a steel one (10 mm). Analysis of strain distribution indicated that the highest strain values occur in the fracture gap and that they are higher when a titanium alloy is used (0-17% vs 0-11%). Interfragmentary movements caused by an imposed load were also higher when a titanium alloy implant was used. Strain analysis showed that the percentage of elements in the gap area which are potentially able to grow bone tissue is higher when a steel implant is used. It is possible to indicate sites where unfavourable fracture gap healing will take place, which may lead to the development of a pseudarthrosis. The use of a steel implant increases the probability of obtaining stable bone union.

Intramedullary osteosynthesis with gamma nail in treatment of peritrochanteric fractures of the femur.

INTRODUCTION: The treatment of peritrochanteric fractures of the femur, particularly in elderly people is a therapeutic challenge for the surgeon, not only due to the patient's age but also the type of fracture. The aim of the present paper is to assess the efficacy of closed intramedullary osteosynthesis with a gamma nail in the treatment of peritrochanteric fractures depending on the type of fracture and patient age. MATERIAL AND METHODS: The study involved 109 patients treated at the Orthopaedic and Trauma Department of A. Sokolowski Hospital in Walbrzych in 2006. The mean age of the patients was 72 years (range 15-95). The follow-up period was 6-20 months, 15 months on average. A detailed assessment involved 97 patients aged 50 years and older. The study utilised AO and Kyle's classifications of fractures; the criteria of Golec and the 27th Congress of the Polish Society of Orthopaedics and Traumatology (PSOT) were used for radiographic assessment; and the Harris scale was used for functional assessment. RESULTS: According to the standards of radiographic assessment, 75% of patients had excellent and good results, indicating good mechanical efficacy of intramedullary fixation and good fracture consolidation. According to the Harris scale, 13% of the patients achieved poor scores in the functional assessment. The poor results were related to the age of the patients and co-existing general diseases rather than to the degree of fracture instability. CONCLUSIONS: In stable peritrochanteric fractures of the femur, intramedullary gamma nailing was associated with good and excellent results irrespective of the patient's age. Poorer functional results in patients aged 71 or older were due to poorer pre-injury general health and local status of the patient.