Aramid-epoxy composite internal fixation plates: a pilot study.

Mechanical tests were conducted on an aramid-epoxy composite laminate in vitro and in vivo to determine its suitability for internal fixation plates. This material, fashioned into blank test coupons the size of the standard 4-hole AO-ASIF plates, had a tensile modulus of elasticity significantly lower than bone. In three-point bending, blank test coupons exhibited a low yield strength that would limit utility in significant load-bearing situations, but changes in the layer configuration of the composite could be expected to improve this characteristic. Under destructive loads, these specimens appeared to be less subject to catastrophic failure than carbon fibre composites. Using 4-hole test coupons fastened to a plastic tube simulating bone, four-point bending tests showed that strain-shielding was significantly reduced by aramid composite relative to carbon fibre composite or metal plates. Finally, in-vivo tests on canine femora demonstrated that aramid composite plates were well tolerated and caused less strain shielding during weightbearing, but significant differences in cortical atrophy and porosity beneath steel versus aramid plates were not apparent. Although the plates were relatively flexible, they could not be preformed during surgery like a metal plate.

Nonunions of fractures of the proximal and distal thirds of the shaft of the femur.

Subtrochanteric and supracondylar fractures of the femur are challenging, and specific anatomic and mechanical problems make fixation precarious. With careful selection of devices and techniques, nonunions may be avoided. Nonunion treatment requires strong immobilization and osteogenesis stimulation with bone grafts. Non-invasive and semi-invasive salvage systems are not as effective as invasive procedures. The first goal of salvage is union. Joint function and muscle strength are secondary goals to be achieved later.

Zickel supracondylar nails for fractures of the distal end of the femur.

Between 1974 and 1984 the Zickel supracondylar nail system was used to fix 82 femora. Sixty-nine femora had supracondylar fractures and 13 supracondylar osteotomies. A high rate of union (98%) was achieved in the fracture group, which included a variety of fracture types, but five supracondylar osteotomies failed to unite initially and required additional surgery. Knee motion exceeded 90 degrees in 70% of the femora that healed but was poorest in the T or Y intracondylar fracture group, in which only 46% exceeded 90 degrees. The operation may be performed as either open or closed nailing. Closed nailing, when possible, is the procedure of choice because of the decreased postoperative morbidity and increased knee motion. Two-thirds of this series were patients older than 60 years, and the device seems particularly helpful in aged individuals.

Knee joint angle: its relationship to quadriceps femoris activity in normal and postarthrotomy limbs.

The relationship of knee joint angle to maximum effort quadriceps femoris activity, as measured by smoothed and rectified EMG, was systematically examined in 30 normal and 18 post-meniscectomy limbs. Our results show that motor unit activity depends not only upon joint angle, but also upon peripheral receptor feedback, which is altered in the post-arthrotomy limbs, producing the characteristic "extensor lag" or inability to maintain the knee at 0 degrees while flexing the hip. The significant interaction of joint position and limb condition must therefore be taken into account when evaluating or rehabilitating pathologic joint conditions. Current motor control theory does not account for the findings presented; an alternative model, proposing integration of the central motor program and peripheral receptor feedback, is presented, which may explain the "extensor lag."

Subtrochanteric femoral fractures.

Femoral fractures in the subtrochanteric and proximal shaft regions require special management because of the great stresses inflicted on the area. Stability is best achieved with intramedullary fixation when there is adequate control of both proximal and distal fragments. Intertrochanteric fractures with small subtrochanteric components can often be adequately fixed with strong nail plate or screw plate devices. When the major fracture is subtrochanteric, an intramedullary device should be used to permit stability of the bone by impaction. Experience with a special device composed of an intramedullary rod and triflanged nail indicates that this appliance performs well in the fixation of subtrochanteric fractures.

Fractures of the adult femur excluding the femoral head and neck: a review and evaluation of current therapy.

A review and appraisal of current methods of treatment of fractures of the femur including operative and nonoperative methods as well as complications or limitations of various methods, reveals that a specific appliance or procedure is of value only when used with proper indication and proper technique. When internal fixation is performed, load-sharing between appliance and bone is mandatory, because of the large mechanical stresses involved. Intramedullary fixation permits load-sharing more often than extramedullary fixation and should be used on femoral fractures whenever possible. Conservative management with traction and braces can be valuable for young patients with fracture of the distal femur, but requires careful technique and follow-up to avoid excessive shortening or deformity. The proximal, middle and distal part of the femur should be evaluated separately as each area has specific anatomic limiations and biomechanical requirements.

A new intramedullary fixation device for the distal third of the femur.

A new fixation device was designed for fractures of the distal third of the femur. An additional use has been for the stabilization of supracondylar osteotomies. The device consists of two- pre-shaped rods which are inserted through the medial and lateral femoral condyles into the medullary canal. The proximal end is ductile and the distal end rigid. Cross compression screws through the distal condylar ends anchor the rods and provide additional fixation for inter-condylar fractures. The preliminary experience in 17 patients demonstrates case of insertion and satisfactory internal fixation.

Intramedullary fixation of pathological fractures and lesions of the subtrochanteric region of the femur.

The Zickel intramedullary appliance was used without methylmethacrylate in forty-six patients to stabilize thirty-five fractures and eleven impending fractures associated with osseous lesions in the subtrochanteric region of the femur. Early mobilization or ambulation was possible in nearly all cases. The patients with actual fractures survived an average of 4.7 months, while those with lesions stabilized prophylactically survived an average of 13.8 months postoperatively. Fourteen of the thirty-five patients with fractures showed union after an average of 4.5 months.

An intramedullary fixation device for the proximal part of the femur. Nine years' experience.

Nine years' experience with a combined intramedullary rod and triflanged nail in eighty-four non-pathological fractures in the subtrochanteric region of the femur is reported and a system of classifying these fractures based on morphology is offered. The appliance was successful in permitting early mobilization of patients and afforded a high rate of union of the fractures. The problems of varus displacement of the distal fragment and protrusion of the device into the joint were not encountered, and there was only one mechanical failure.