Optimizing fixation methods for stable and unstable intertrochanteric hip fractures treated with sliding hip screw or cephalomedullary nailing: A comparative biomechanical and finite element analysis study.

BACKGROUND: Despite recent advances in implants and surgical techniques, catastrophic and clinical failures in the treatment of intertrochanteric fractures continue to occur, with dire consequences in an overall frail population subset. The aim of the current study is to evaluate the effect of the factors under the surgeons' control, namely fracture reduction and implant selection, on the biomechanical behavior of fracture fixation constructs. MATERIAL-METHODS: An experimental protocol was conducted with the use of instrumented sawbones, in order to validate the finite element models. The implants used were the Gamma3®and DHS systems. Subsequently, a series of scenaria were considered, including various reduction and implant angle combinations. Data were retrieved concerning the peak cancellous bone stresses around the hip screw and the volume of cancellous bone in the femoral head stressed at critical levels, as well as implant stresses and stresses on the cortical bone of the distal fragment. RESULTS: All stable fracture models displayed significantly decreased cancellous bone stresses and implant stresses compared to their unstable counterparts, regardless of implant used. The effect of increasing implant angle led to a decrease in implant stresses in all models studied, but had a beneficial effect on the stresses in the cancellous bone of the proximal fragment only in the subgroups of stable fractures with both implants and unstable fractures treated with a cephalomedullary nail (CMN). In unstable fractures anatomically reduced, the use of CMN led to significantly lower peak stresses in the cancellous bone and a smaller volume of bone stressed at critical levels. Increasing the reduction angle by 5 ° led to a significant decrease in both peak stresses and volume of bone stressed at critical levels, more prominent in the sliding hip screw (SHS) models. Decreasing the reduction angle into varus by 5 or 10 ° led to a significant increase in bone and implant stresses regardless of implant used. CONCLUSIONS: In stable two-part (AO31.A2) fractures the use of the SHS appears to be biomechanically equivalent to CMN. In unstable, anatomically reduced fractures, the use of CMN leads to significantly reduced cancellous bone stresses and decreased rotation of the proximal fragment during loading. A reduction in varus should be avoided at all costs. In unstable fractures treated with SHS a reduction in slight valgus appears to be biomechanically beneficial. The highest implant angle that allows for proper screw position and trajectory in the femoral head should be used for stable fractures with both implants and unstable fractures treated with Gamma3®.

The Marchetti-Vicenzi elastic locked nail for the treatment of femoral shaft fractures: a review of 100 consecutive cases.

A total of 100 hundred femoral fractures in 97 patients were treated with the Marchetti-Vincenzi universal bundle elastic nail; six of the fractures were open. Closed fractures were classified according to AO and Winquist; open fractures were classified according to Gustilo. A total of 91 fractures united (average 12 weeks) and six led to non-union. There were two deep and one superficial infections. In three cases, the secondary nails protruded from the anterior cortex of the femoral condyle; in two cases intraoperatively and in the third case 2 months postoperatively, due to severe osteoporosis. The cylindrical part of the nail did not fail, whereas all the secondary nails failed in one patient as well as one secondary nail in another patient at the level of the fracture; these two cases exhibited non-union. We consider the absence of distal screws the major advantage of this particular nail, followed by position of the entry point and the limited reaming. We believe that the absence of a pin guide is a disadvantage. The elasticity of the nail has a positive effect in certain cases while in other cases it acts negatively, resulting in a relatively high proportion of non-unions as in our series. Therefore our conclusion is that this nail is not appropriate for the treatment of femoral shaft fractures.

Colour Doppler ultrasonography of the ophthalmic artery: flow parameters in normal subjects. The significance of the resistance index.

BACKGROUND: The aim of this study was to assess the flow characteristics in ophthalmic arteries and to detect their possible relationships to those in the common and internal carotid arteries. METHODS: Sixty healthy subjects (age range 20-74 years) with normal vascular findings, stratified by age and sex were recruited to the study. A colour Doppler ultrasound examination of the neck arteries was performed, followed by a colour Doppler ultrasound examination of the 120 ophthalmic arteries included. Peak systolic velocity, end diastolic velocity and resistance index (RI) of the common carotid, internal carotid and ophthalmic arteries, as well as the insonation depth of the ophthalmic arteries were measured. RESULTS: The mean values (standard deviation) of the measured parameters for the ophthalmic arteries were: insonation depth: 38.38 mm (2.60 mm), peak systolic velocity: 34.71 cm/sec (6.38 cm/sec), end diastolic velocity: 7.95 cm/sec (1.70 cm/sec), resistive index: 0.77 (0.04). The resistance index of the ophthalmic arteries was, in all cases, greater than that of the ipsilateral common carotid artery which in turn, was greater than that of the internal carotid. The value of the index in the ophthalmic arteries, when the circulation is normal in the extra- and intracranial arteries is rarely lower than 0.70. CONCLUSIONS: When an inversion of the ratio between the resistance index of the ophthalmic artery and that of the common carotid or an index value lower than 0.70 in the ophthalmic artery is observed, further investigation is needed as this situation cannot be considered normal. The resistance index seems to be the most reliable parameter for the estimation of normal circulation in ophthalmic arteries.

Uncemented total hip arthroplasty in the elderly.

Between January 1991 and December 1994, 132 uncemented total hip arthroplasties (THA) were performed on 125 patients over 65 years of age; of which 102 arthroplasties, performed in 90 patients, were followed for at least 4 years. One revision was necessary following fracture of an acetabular component secondary to trauma. The post-operative Harris hip score (HHS) ranged from 87 to 99. Radiologically there were no signs of subsidence of more than 3 mm, nor of osteolysis. Five patients experienced thigh pain. Based on the clinical and radiological results, uncemented total hip arthroplasties can give satisfactory function in elderly patients.

Closed interlocked nailing in comminuted and segmental femoral shaft fractures.

One hundred eight femoral shaft fractures in one hundred six adults were treated by closed intramedullary interlocked nailing. Ninety-two fractures were severely comminuted and 16 fractures were segmental. The procedures were done with the patients in the supine position. A modification of the cylinder guide for fixation of the distal screws is described. All the fractures healed in an average of 18 weeks (range, 12-24 weeks). Dynamization was performed in 15 fractures. There were two postoperative complications, which did not ultimately affect the clinical results. No infections or delayed unions were observed. Closed intramedullary interlocked nailing seems to be the treatment of choice for comminuted and segmental fractures of the femoral shaft provided that all the technical details are followed by the surgeon.

Ipsilateral fractures of the femur and tibia.

From October 1987 to September 1990, 32 patients with ipsilateral fractures of the femur and the tibia were treated. There were 20 men and 12 women with a mean age of 27 years (range 18-75 years). All were caused by road accidents. There were 7 femoral and 22 tibial open fractures. The management of the fractures was partially the same. The tibial fractures were reduced and stabilized by a unilateral external fixator, while in 29 out of 32 femoral fractures, a closed intramedullary nailing was performed. The remaining three patients with an open grade III fracture were initially treated by external fixation, with two of them converted into nailing. The time of hospitalization ranged from 12 to 105 days (mean 30 days). The femoral fractures healed in an average of 15.5 weeks, while the tibial fractures healed in 18.5 weeks. The evaluation of our results was made according to Karlstrom and Olerud's criteria. We achieved 81 per cent excellent or good results and 19 per cent acceptable or poor, in a follow-up time of 19.5 months.