Metal release and excretion from cementless titanium alloy total knee replacements.

Concentrations of titanium, aluminum, and vanadium were measured in the serum and urine of patients with titanium alloy cementless primary total knee arthroplasty components. Patients were categorized in one of five groups. In Group 1, the patellar and tibial articulating surfaces were made of carbon fiber reinforced ultrahigh molecular weight polyethylene. In Group 2, the patellar and tibial surfaces were made of ultrahigh molecular weight polyethylene. In Group 3, the femoral titanium alloy articulating surface was nitrogen ion implanted with ultrahigh molecular weight polyethylene patellar and tibial articulating surfaces. Patients in Group 4 had failed patellar components, and Group 5 was comprised of age and gender matched control subjects without implants. Serum concentrations of titanium were approximately 50 times greater in patients with failed patellar components (Group 4) and approximately 10 times greater in patients with carbon fiber reinforced polyethylene bearing surfaces (Group 1) when compared with Groups 2 and 3 and the control subjects (Group 5). For aluminum and vanadium, no detectable differences were observed among any of the groups. In addition, analysis of 24-hour urine samples showed no significant differences in titanium, aluminum, or vanadium concentrations among any of the groups. Elevated serum titanium levels may serve as a marker of patellar component failure or accelerated femoral component wear in total knee replacements with titanium alloy bearings. The toxicologic ramifications of these findings are unknown.

Implant stability in revision total hip arthroplasty: allograft bone packing following extended proximal femoral osteotomy.

One method of revising the femoral component in revision total hip arthroplasty in the presence of compromised femoral bone stock is to pack the upper femur with particulate allograft and then to cement the femoral component into the allograft bed. This technique is being used clinically with encouraging results. Additionally, surgical exposure of the femoral canal during revision total hip arthroplasty can be greatly improved with an extended trochanteric osteotomy, which is subsequently repaired with wires or cables. To assess the feasibility of performing the allograft bone packing technique following an extended trochanteric osteotomy, the stability of this construct in a cadaver model was measured, using micromotion sensing instruments and loads applied on a materials testing machine. The stability of the cemented allograft impaction construct following extended trochanteric osteotomy was comparable to the stability of the control construct, which consisted of a similar impacted allograft construct without osteotomy. The stability of the osteotomized side was comparable to that of the control side. It is concluded that the initial in vitro stability of the allograft impaction technique following extended proximal femoral osteotomy is adequate to justify experimental in vivo use.

Revision of the acetabular component without cement after total hip arthroplasty. A follow-up note regarding results at seven to eleven years.

The results of revision of the acetabular component without cement, performed for aseptic loosening, were reported previously after a mean of forty-four months for 138 hips (132 patients). After an additional mean duration of follow-up of almost five years, twelve patients (twelve hips) had died before they could be followed long enough for the later study and nine patients (eleven hips) had been lost to follow-up; thus, a total of 111 patients (115 hips) were available for follow-up at a mean of 100 months (range, seventy-eight to 135 months). Between the earlier and later times of follow-up, six additional acetabuli had had a repeat revision: one, for recurrent dislocation; two, for infection; and three (which were stable), at the time of a revision of the femoral stem. No revision of the acetabular cup was performed because of aseptic loosening, and no cup was noted to have migrated. Radiographs were available for 105 patients (109 hips) at a mean of ninety-eight months (range, seventy-eight to 135 months). Five (5 per cent) of the 109 cups were surrounded by a complete radiolucent line and three (3 per cent), by a partial progressive radio-lucent line. A radiolucent line adjacent to a screw was seen in association with two cups (2 per cent), and osteolysis was noted at the margin of four cups (4 per cent). Revision of the acetabular component with a porous-coated, nearly hemispherical fiber-metal component inserted without cement was associated with a high rate of excellent results at the seven to eleven-year follow-up examination.

Complications of a cable grip system.

From a group of 643 total hip arthroplasties, 98 patients required trochanteric osteotomies, and in 68 the trochanteric osteotomies were repaired with the Dall-Miles cable grip system (Howmedica, Rutherford, NJ). Trochanteric nonunion occurred in 17 of these patients (25%), with fraying and fragmentation of the cable present in 15 (88%). Of the 51 patients with radiographic union, 18 (35%) also had signs of fraying and fragmentation. Bone destruction around the cable in the area of the lesser trochanter was seen in seven patients (10%). Large deposits of metal debris at the inferior border of the acetabulum were seen in eight hips (12%). Multifilament cable did not appear to offer significant advantages over standard monofilament wire, and the potential problems of fraying, fragmentation, and free-floating metallic debris must be considered.

The prosthesis-bone interface adjacent to tibial components inserted without cement. Clinical and radiographic follow-up at nine to twelve years.

We evaluated the radiographic and functional status of a one-piece composite tibial component, designed to be inserted without cement, that was developed and used only at our institution. Thirty-six patients (thirty-seven knees) were managed with the component between November 1981 and September 1983, and none were lost to follow-up. When they were last seen, thirty-four (92 per cent) of the thirty-seven knees had a well-fixed tibial component, both clinically and radiographically. Eight patients (eight knees; 22 per cent) died. Eleven patients (eleven knees; 30 per cent) had a revision at an average of sixty-five months (range, four to ninety-five months) postoperatively. The reason for the revision was failure of a metal-backed patellar component in three knees, excessive wear of the polyethylene of the tibial component in one, a hematogenous infection in four, aseptic loosening of the tibial component in two, and chronic synovitis in one. The remaining seventeen patients (eighteen knees; 49 per cent) were seen for clinical and radiographic follow-up at an average of eleven years (range, nine to twelve years) after the operation. With removal of the implant as the end point, the cumulative rate of survival was 83 per cent at fifty-six months and 67 per cent at 108 months. Some of the failures were secondary to features of the prosthetic design that currently are considered to be inadequate, including a metal-backed patellar component and carbon-fiber-reinforced polyethylene. In the twenty-six knees in which the prosthesis had been retained, the implant was stable and the prosthesis-bone interface was unchanged as seen radiographically at the time of the most recent follow-up examination. This finding demonstrates that a porous ingrowth surface is capable of providing a secure interface for biological fixation over the long term.

Revision total hip arthroplasty using a cementless acetabular component. Technique and results.

Are the midterm results (range, 7-11 years) for revision of the acetabulum with a cementless hemispherical component comparable with other published revision techniques at similar followup? One hundred thirty-eight acetabular revisions for aseptic loosening were done in 132 patients using a cementless hemispherical component coated with titanium mesh and inserted with supplemental screw fixation. Twelve patients died, 9 were lost to followup, and 6 could not return for followup, leaving 111 patients (115 hips) with a mean of 100 months of followup. Thirteen hips required revision (11%): 4 were done for recurrent dislocations, and 6 for sepsis; 3 stable cups were revised (at the time of stem revision). No cup was revised for aseptic loosening. Radiographic review was available for 105 patients (109 hips) at mean 98-month followup (78-135 months). A complete radiolucency was seen in 4% of the cups, a partial progressive radiolucency in 3%, and a partial nonprogressive radiolucency in 54%; no radiolucency was present in 39%. A screw radiolucency was seen in 2%, and osteolysis at the cup margin in 4%. Revision of the acetabulum with a cementless porous-coated hemispherical fiber-metal component is superior to the results reported for acetabular revisions with cement at similar followup.

Revision total hip arthroplasty using a cementless acetabular component: technique and results.

One hundred thirty-eight acetabular revisions for aseptic loosening were performed in 132 patients using a cementless hemispherical component coated with titanium mesh and inserted with supplemental screw fixation. Twelve patients died, 9 were lost to follow-up and 6 could not return, leaving 111 patients (115 hips) at mean 100 months follow-up. Thirteen hips required revision (11%); 4 for recurrent dislocations, 6 for sepsis, and 3 stable cups were revised (at the time of stem revision). No cup was revised for aseptic loosening. Radiographic review was available for 105 patients (109 hips) at mean 98 month follow-up (78 to 135 months). One hundred cups (91%) were considered stable. Seven cups were possibly unstable (7%), one cup was probably unstable (1%), and one septic hip had an unstable cup (1%). Four percent of the cups showed a complete radiolucency. A partial progressive radiolucency was seen in 3%, a partial nonprogressive radiolucency in 54%, and no radiolucency was present in 39%. A screw radiolucency was seen in 2%, and osteolysis at the cup margin in 4%. Revision of the acetabulum with a cementless porous-coated hemispherical fiber-metal component seems to be superior to the results reported for acetabular revisions with cement at similar follow-up.