Total hip replacement using porous-coated cobalt-chrome femoral implants designed for biological fixation has been evaluated in 307 patients after two years and in 89 patients after five years. Histological study of 11 retrieved specimens showed bone ingrowth in nine and fibrous tissue fixation in two. Fixation by bone ingrowth occurred in 93% of the cases in which a press fit of the stem at the isthmus was achieved, but in only 69% of those without a press fit. The clinical results at two years were excellent. The incidence of pain and limp was much lower when there was either a press fit of the stem or radiographic evidence of bone ingrowth. Factors such as age, sex, and the disease process did not influence the clinical results. Most cases showed only slight resorptive remodelling of the upper femur, but in a few cases with a larger, more rigid stem, more extensive bone loss occurred. The results after five years showed no deterioration with time. Fixation by the ingrowth of bone or of fibrous tissue both appeared to be stable, but bone ingrowth gave better clinical results.

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Porous-coated hip replacement. The factors governing bone ingrowth, stress shielding, and clinical results

Certain roentgenographic signs have value in predicting the fixation of a cementless femoral component to bone by osseointegration. Other signs have value in predicting the gross stability of a cementless femoral component. The authors have determined the specificity and sensitivity of the signs for osseointegration in cases in which the histologic fixation has been confirmed after implant removal. The authors have also determined the specificity and sensitivity of the signs for gross implant stability in cases in which the stability has been confirmed at reoperation. Statistical methods were used to determine a numeric value for each of these roentgenographic signs, and these values were combined into a score. The score was divided into fixation by osseointegration and mechanical implant stability. The two scores were then combined into an overall score. When signs of osseointegration were present, the implant was always stable, and the overall scores were the highest. When signs of osseointegration were absent, the mechanical stability varied, and the scores were lower. A neutral or slightly negative score correlated with failed osseointegration but secondary successful implant stabilization. A very low negative score correlated with gross implant instability. To confirm the validity of the scoring system, the two-year postoperative score was determined for 1005 cases in which the clinical outcome was known. A strong correlation between the presence of symptoms and a low score confirmed the value of the scoring system for diagnosing implant loosening as the cause of symptoms. As a second test, the two-year and five-year postoperative results were compared in the same patients. A high two-year score correlated with durable implant stability through five years. A low two-year score correlated with a higher incidence of late symptomatic loosening.

Roentgenographic assessment of the biologic fixation of porous-surfaced femoral components.

The results were reviewed for 259 patients who had open reduction and internal fixation of 262 displaced acetabular fractures within twenty-one days after the injury. Two hundred and fifty-five hips were followed for a mean of six years (range, two to fourteen years) after the injury; the remaining seven, which clearly had a poor result, were followed for less than two years. According to the classification of Letournel and Judet, associated fracture types accounted for 208 (79 per cent) of the fractures, with both-column fractures being the most common type (ninety-two hips; 35 per cent). Two hundred and fifty-eight hips were operated on with a single operative approach (Kocher-Langenbeck, ilioinguinal, or extended iliofemoral). The four remaining hips were operated on with a Kocher-Langenbeck as well as an ilioinguinal approach. The reduction was graded as anatomical in 185 hips (71 per cent). The rate of anatomical reduction decreased with increases in the complexity of the fracture, the age of the patient, and the interval between the injury and the reduction. The over-all clinical result was excellent for 104 hips (40 per cent), good for ninety-five (36 per cent), fair for twenty-one (8 per cent), and poor for forty-two (16 per cent). The clinical result was related closely to the radiographic result. The clinical result was adversely affected by associated injuries of the femoral head, an older age of the patient, and operative complications. It was positively affected by an anatomical reduction and postoperative congruity between the femoral head and the acetabular roof. Osteonecrosis of the femoral head was noted in eight hips (3 per cent), and progressive wear of the femoral head was seen in thirteen (5 per cent). Subsequent operations included a total replacement of seventeen hips (6 per cent), an arthrodesis in four (2 per cent), and excision of ectopic bone in twelve (5 per cent). These findings indicate that in many patients who have a complex acetabular fracture the hip joint can be preserved and post-traumatic osteoarthrosis can be avoided if an anatomical reduction is achieved. An increase in the rate of anatomical reduction and a decrease in the rate of operative complications should be the goals of surgeons who treat these fractures.

Fractures of the acetabulum: accuracy of reduction and clinical results in patients managed operatively within three weeks after the injury.

1. The results have been reported of total hip replacement by a low-friction technique using high-density polyethylene for the acetabular component in 379 primary interventions, performed between November 1962 and December 1965 and followed for between four and seven years.

2. Apart from failures due to infection, the rate of which in the era under review was 3·8 per cent, late failures from mechanical causes were unusual after total hip replacement by this technique. When the socket was cemented in position, which is now routine, the late mechanical failure from all causes was only 1·3 per cent in 210 cases.

3. As regards the quality of the results and their maintenance over the years, the results were so good (Table X) that it was unnecessary to distinguish an intermediate class of "improvement" between success and failure.

4. As regards relief of pain and ability to walk, the average final rating, on a scale numbered 1 to 6, was 5·9 for both, indicating 90 per cent of patients in Grade 6 (excellent) and only 10 per cent in Grade 5 (good).

5. The average recovery of movement was not as spectacular and was influenced considerably by the pre-operative range, but in all cases that range was improved on. Even starting with the stiffest of hips about one patient in four regained a right angle of flexion movement. There was no tendency to lose movement with the passage of time.

6. As regards late infection (2·2 per cent out of a total of 3·8 per cent), the various findings tend to exonerate cement as a cause.

7. The mechanical details of the technique became stabilised in the period 1959 to 1962 in the Teflon era, and with the exception of improved methods of reattachment of the greater trochanter, they are identical with our current practice in 1971.

The long-term results of low-friction arthroplasty of the hip performed as a primary intervention

From 1982 to 1988, 147 cemented acetabular components were revised with cementless hemispherical press-fit components, with an average follow-up period of 5.7 years (range, 3–9 years). Acetabular defects were typed from 1 to 3 and reconstructed with a bulk or support allograft. Type 1 defects had bone lysis around cement anchor sites and required particulate graft. Type 2A and B defects displayed progressive bone loss superiorly and required particulate graft, femoral head bulk graft, or cup superiorization. Type 2C defects required medial wall repair with wafer femoral head graft. Type 3A and B defects demonstrated progressive amounts of superior rim deficiencies and were treated with structural distal femur or proximal tibia allograft. Six of the 147 components (4.0%), all type 3B, were considered radiographically and clinically unstable, warranting revision. Three of the six were revised. Moderate lateral allograft resorption was noted on radiographs, but host-graft union was confirmed at rerevision. Size, orientation, and method of fixation of the allografts play an important role in the integrity of structural allografts, while adequate remaining host-bone must be present to ensure bone ingrowth.

Acetabular defect classification and surgical reconstruction in revision arthroplasty. A 6-year follow-up evaluation.

Late results in 243 arthroplasties with an acrylic prosthesis for traumatic or osteoarthritic conditions are reported.

Early results (after one year) show the importance of the restoration of the normal mechanics of the hip joint by the preservation or the restoration of normal length of the femoral neck, the exact correction of anteversion, and the precise fit of the prosthetic head to the acetabulum. A good exposure of the joint through the posterolateral approach appears necessary in order to fulfill these conditions.

Late results (from two to five years) show deterioration of the functional results in 20 per cent. These deteriorations appear to be caused by bone absorption around the Judet prosthesis and the consequent loosening of the prosthesis.

A new type of cervico-capital prosthesis is proposed which makes possible:

1. Restoration of the normal length of the femoral neck when it is congenitally or pathologically short;

2. Correction of anteversion, even when very marked;

3. A weight-bearing surface on a more vascularised part of the femur;

4. The distribution of pressure on bone so as to lessen bone absorption, to prevent its ill effects, and, particularly, to decrease mobility of the prosthesis.

R. M. D'Aubigné

Papers

Functional results of hip arthroplasty with acrylic prosthesis

Functional results of hip arthroplasty with acrylic prosthesis