Eduardo Garcia-Cimbrelo

Early and late loosening of the acetabular cup after low-friction arthroplasty.

Between 1971 and 1979, 680 low-friction arthroplasties of the hip were performed in 598 patients. The average duration of follow-up was twelve years and eight months. Sixty-one acetabular cups had loosening as seen on roentgenograms eighteen years postoperatively, resulting in a total cumulative probability of loosening of 19 per cent, according to survivorship analysis. In twenty-nine cups, the loosening appeared within ten years after the operation (early loosening) and in thirty-two, more than ten years after the operation (late loosening). Early loosening was associated with deficient structure of the bone of the acetabulum, a previous congenital dislocation of the hip, acetabular fracture, or acetabular protrusion in all instances (p < 0.01). Late loosening was associated with the depth of acetabular wear. Of the thirty-two cups that had more than two millimeters of wear, eighteen (56 per cent) had loosening on the roentgenograms (p < 0.001). In hips that had early loosening, migration was the most frequent finding, and its rate of progression was higher than in hips that had late loosening (p < 0.001). In late loosening, a complete bone-cement radiolucency of more than two millimeters was the most frequent finding. Clinical failure was seen in twenty-two (76 per cent) of the twenty-nine cups that loosened early and in nine (28 per cent) of the thirty-two cups that loosened late. The probability of extensive resorption of bone necessitates close observation of patients who have early loosening, while a reasonable period of observation is possible for those who have late loosening.

Porous-coated cementless acetabular cups in revision surgery: a 6- to 11-year follow-up study.

Between 1986 and 1991, 65 cementless hemispherical acetabular cups were implanted in 60 patients in revision surgery. Different designs were used, including PCA (29 cups), Duraloc (14 cups), Harris-Galante (12 cups), and Omnifit (10 cups). The mean age of patients was 54.7 years. The Paprosky types of the acetabular tone defects were type 1, 2 hips; type 2, 38 hips; type 3A, 15 hips; and type 3B, 10 hips. For unrevised hips, the mean follow-up was 8.3 years (range, 6-11 years). Bone allografts were used in 56 hips: Morcellized cancellous graft was used in 42 hips, structural graft for contained defects was used in 7 hips, and structural graft for uncontained defects was used in 7 hips. There were poor clinical results in 14 hips (22%). Re-revision was necessary in 7 hips (10.8%). There was definite radiographic loosening in 18 hips and possible loosening in 4 hips. Screw failure occurred in 6 hips, and a radiolucency in 1 or more DeLee-Charnley zones was apparent in 45 hips (69.2%). Moderate or severe graft resorption were found in 4 of the 42 morcellized grafts, in 6 of the 7 structural grafts for uncontained defects, and in all 7 of the 7 structural grafts for contained defects. The best results were obtained in hips with a bone defect of less than 30%. The use of a cementless acetabular cup supplemented with screws is contraindicated in hips with a bone defect greater than 50%. Hip reconstruction using structural bone-graft to stabilize the prosthesis gives the worst results.

Mittelmeier ceramic—ceramic prosthesis after 10 years

The clinical status of 83 Mittelmeier ceramic-ceramic (Mark II) cementless total hip prostheses (Autophor, Osteo AG, Selzach, Switzerland) implanted between 1978 and 1984 was analyzed. Retrieved tissue from the revised hips was studied histologically. The mean patient age was 47.5 years (range, 19-71 years). One or both components of 12 hips were revised (16% at 16 years in the survival study). Eleven acetabular components and seven stems were revised, with three of the sockets fractured. The mean follow-up period for the patients with unrevised hips was 12.3 years. Osseointegration was uncommon in both the cup and stem. Radiographic cup loosening was observed in 53% of hips at 16 years in the survival study, with most having a complete radiolucent line of 2 mm around the cup. Radiographic stem loosening appeared in 15% of hips at 16 years. Fibrous stable fixation was present in 64% of stems. Significant radiographic acetabular wear was not observed in any hip. The Mittelmeier Mark II prosthesis had worse long-term results than reported with cemented or other uncemented prostheses. Although there was no significant acetabular wear, intracellular ceramic wear debris was seen in the retrieved tissues.

Dislocation in low-friction arthroplasty

In a series of 2,050 low-friction arthroplasties, 61 cases (2.97%) of dislocation were analyzed. The mechanism of production was malposition of the components (group 1, 33%), deficiency of the abductor mechanism (group 2, 34%), or the association of both (group 3, 26%). Failure to find a cause was even more rare (group 4, 7%). The best treatment is prevention by careful surgical technique, since good results with different procedures have only been attained in 51% of dislocated hips.

Progression of Radiolucent Lines Adjacent to the Acetabular Component and Factors Influencing Migration after Charnley Low-Friction Total Hip Arthroplasty*†

We analyzed the progression of radiolucent lines around the acetabular cup after 452 Charnley low-friction arthroplasties that had been performed in 392 patients between 1971 and 1976. The average duration of follow-up was twenty years (range, eleven to twenty-five years) for the 442 hips (382 patients) that had the original component in place at ten years. The demarcation of the bone-cement interface was classified according to the system of Hodgkinson et al. We sought to determine if there was a relationship between the progression of the radiolucent line and the age, gender, and weight of the patient; the level of activity; the preoperative diagnosis; or the amount of wear of the acetabular cup. The demarcation increased over time in 138 (31 per cent) of the 452 hips. Radiographs made at the time of the latest follow-up showed migration of eleven (5 per cent) of the 233 acetabular cups with no demarcation on the initial postoperative radiograph, eighteen (11 per cent) of the 167 cups with type-1 demarcation, twelve (35 per cent) of the thirty-four cups with type-2 demarcation, and thirteen of the eighteen cups with type-3 demarcation. Preoperative acetabular protrusion, inflammatory arthritis, and severe acetabular dysplasia as well as a previous operation were associated with the extent of the radiolucent line on the most recent radiograph (p ⩽ 0.05 for all). A high level of activity and more than two millimeters of wear of the acetabular cup also were related to the progression of the radiolucent line (p = 0.0004 and p < 0.0001, respectively). Kaplan-Meier survivorship analysis demonstrated that the greater the demarcation on the initial postoperative radiograph, the greater the risk of migration (p < 0.0001, Mantel-Cox test). Our data suggest that, after a Charnley low-friction arthroplasty, any cemented cup, even one with the least amount of demarcation (types 0 and 1), can migrate. As the type of the initial postoperative demarcation increases, so does the risk of migration of the cup, particularly when there is loss of the acetabular bone stock.

Low relapse with oral antibiotics and two-stage exchange for late arthroplasty infections in 40 patients after 2–9 years

Background and purpose Exchange surgery in late arthroplasty infection is directed against bacteria adhering to implants. Therapies based on antibiotics that are effective intracellularly have been proposed recently. We have combined both strategies to improve the cure rate. Methods 40 consecutive patients (16 hips, 24 knees) were diagnosed with late arthroplasty infection. The organisms isolated were 35 Staphylococcus, 19 of which were methicillin-resistant, 4 Enterococcus, 6 Gram-neg-ative bacilli, and 4 Corynebacterium. The infections were managed by a combined therapy consisting of two-stage exchange surgery and two oral intracellularly-effective antibiotics. The antibiotics were selected according to bacterial sensitivity and intracellular and biofilm effectiveness. Second re-implantation surgery was delayed until clinical and analytical normalization. Patients were in hospital for only 1 week after each surgery, and were followed up prospectively on an outpatient basis (2–9 years). Cure of the infection was defined as absence of clinical, serological, and radiographic signs of infection during the whole follow-up. Results The infection was resolved in 38/40 patients (15/16 hips and 23/24 knees). Interpretation Oral antibiotics that are effective intracellularly in combination with two-stage exchange surgery is a promising alternative for treating late arthroplasty infections. Oral antibiotics shorten hospitalization and reduce patient discomfort.

Circular external fixation in tibial nonunions.

The Ilizarov method based on compression-distraction and subperiostic corticotomy was used in 82 lower extremities. There were 45 tibial nonunions without a significant bone defect and 37 tibial nonunions with a bone defect that required radical removal of the necrotic bone and bone lengthening or bone transport. Bone healing was obtained in 39 of the 45 tibial nonunions without bone defect (mean bone healing, 5.4 months) and in all patients with bone defect (mean bone healing, 15 months for patients treated with bone transport) although secondary surgeries (autografting and tibial nails) were frequent (23 patients). Infection was eradicated in all patients after necrotic bone removal and bone transport. The final mean limb length discrepancy was 0.7 cm for the patients without a bone defect and 2.03 cm for the patients with a bone defect. In the patients in the bone transport group, residual axial deviation and residual limb shortening were common. Circular external fixation is a useful method to solve complex tibial nonunions in patients in whom internal devices and autografting have failed. Patients must be cooperative, and must understand the length of time the frame needs to be worn, and that complications are a probability.

Long-term results of aseptic cemented Charnley revisions

One hundred eighty low-friction arthroplasties of the hip in 164 patients in first-time revision surgery were operated between 1973 and 1985. This series used only cement fixation, and aseptic loosening and femoral stem fractures were the only indications for revision. The average follow-up period was 11.5 years. Intra-operative and postoperative complications were frequent: femoral shaft fracture (13 cases), femoral shaft perforation (12 cases), deep infection (14 cases), and dislocation (15 cases). Twenty-eight hips were rerevised or removed (resulting in a total cumulative probability of rerevision of 20% after 16 years, according to survivorship analysis). Nineteen cups were rerevised (13% after 16 years, according to survivorship analysis), and 24 femoral stems were rerevised (16% after 16 years, according to survivorship analysis). Radiographic cup and femoral loosening appeared in 29 and 36 cases, respectively (24 and 22% after 16 years, respectively, according to survivorship analysis). Good results were observed when there was a healthy and intact bone bed, whereas poor results were related to inadequate bone stock in the acetabulum and femur. Radiolucent lines were frequent in both components; radiolucent lines less than 2 mm wide were frequent in acetabular zone 1. Pistoning of the prosthesis and the cement within the bone and calcar pivot was the most frequent type of stem loosening.

The femoral component in low-friction arthroplasty after ten years.

In 623 low-friction arthroplasties ten years after implantation, 70 hips (18.04% after 16 years) showed loosening of the femoral component. Eighty-four percent appeared within ten years. Fracture of the stem occurred in 4.3% of cases after 16 years, and resorption over 5 mm of the femoral neck occurred in 9.3%. Calcar cysts appeared in 2.9% and endosteal cavitations in 18.04% after 16 years; both findings were related to acetabular wear greater than 2 mm. Gruens Type III (calcar pivot) was the least common loosening (6.8%) during the first ten years. After this time its incidence increased to 17.1%. Loosening of the femoral component was not related to age, weight, or activity. It was, however, associated with poor surgical technique, i.e., varus position (46%), cementation defects (34%), and/or femoral neck osteotomy on the lesser trochanter (36%).

Loosening of the cup after low-friction arthroplasty in patients with acetabular protrusion: THE IMPORTANCE OF THE POSITION OF THE CUP

Between 1972 and 1990, we performed 168 primary low-friction arthroplasties in 125 patients with acetabular protrusion. Twelve hips were lost to follow-up within eight years and eight which became infected were excluded from the final study. Of the 148 hips remaining, 62 with a mild protrusion were classified as group 1, 54 with moderate or severe protrusion as group 2 and, after 1985, 32 with moderate and severe protrusion which required bone grafts as group 3. The mean follow-up was 18.3 years (3 to 24) for group 1, 17.4 years (8 to 22) for group 2 and ten years (8 to 13) for group 3. There were 31 revisions of the cup, 12 in group 1 and 19 in group 2. According to the Kaplan-Meier analysis the overall rates at 20 years were 21 +/-10.79% in group 1 and 37 +/- 11.90% in group 2. There have been 43 radiological loosenings: 22 in group 1, 21 in group 2 and none so far in group 3, at ten years. The overall loosening rates at 20 years were 42 +/-14.76% in group 1 and 49 +/- 19.50% in group 2. The grafts were well incorporated in all group-3 hips, and the bone structure appeared normal after one year. The distance between the centre of the head of the femoral prosthesis and the approximate true centre of the femoral head was less in group 3 than in groups 1 and 2 (p < 0.01). According to the Cox proportional-hazards regression this was the single most important factor in loosening of the cup (odds ratio 1.11; 95% CI 1.05 to 1.18/mm). Better results were obtained in moderate and severe protrusions reconstructed with bone grafting than in hips with mild protrusion which were not grafted.