Prospective study of magnetic resonance imaging and SPECT bone scans in renal allograft recipients: evidence for a self-limited subclinical abnormality of the hip.

We recently reported that typical abnormalities of avascular necrosis (AVN) in magnetic resonance images (MRI) of the hips of asymptomatic renal transplant recipients whose plain radiographs are normal may improve spontaneously and even disappear completely. We present the results of serial bone scans, most of which were performed with single-photon emission computed tomography obtained over periods as long as 24 mo after transplantation in 72 of these patients. Three paired imaging studies (i.e., MR and bone scan performed within 30 days of each other) were available for each of these patients. In three patients, both the MR images and the bone scans showed changes consistent with bilateral AVN within 4 mo after transplantation. All three patients developed hip pain which was bilateral in two and unilateral in one. Two patients (three hips) required surgical intervention at which time AVN was found on pathologic examination of all three hips. None of the remaining 69 patients developed hip pain during the study. However, in nine patients whose MR studies were consistently normal, at least one bone scan was abnormal (13 hips). The presence of AVN was pathologically confirmed in each of the hips subjected to surgery. Where the imaging findings were identical to those in the asymptomatic patients as well as those in whom the imaging abnormality regressed, we suggest that the subclinical imaging abnormalities represent mild AVN, which is reversible in some cases. Since the process was identified in 10 hips by MRI and in 13 hips by bone scan, both studies are needed to detect subclinical AVN. This may be important if treatment of subclinical disease is clearly shown to prevent progression to symptomatic AVN.

Evaluation of metallic osseous implants with nuclear medicine.

Nuclear medicine has proven to have a valuable role in the evaluation of osseous metallic implants, particularly with joint prostheses, but can assist with evaluation of other appliances as well. The nuclear arthrogram has become an invaluable adjunct to simultaneously performed radiographic contrast arthrography. This application has been best evaluated in what is one of the most common of orthopedic prosthesis problems, namely, loosening of total hip prostheses. Experience indicates that both sensitivity and specificity of loosening of the femoral component can be increased to over 90% through combined use of nuclear with radiographic contrast arthrography. Furthermore the combination of routine skeletal scintimaging with the nuclear arthrogram adds a significant dimension to precise localizing of the nuclear arthrographics agent In-111 chloride. Nuclear medicine also plays an important role in further evaluating the presence of infection associated with metallic implants with In-111 WBC preparations being superior to Ga-67 as the radiopharmaceutical tracer. Infection has been detected with a sensitivity of 73% and a specificity of 93% in our series using combined In-111 WBC and simultaneous skeletal imaging with conventional Tc-99m MDP. Acute infections are more readily identifiable than chronic in association with prostheses.

The Indiana conservative (surface-replacement) hip arthroplasty.

We reviewed the clinical results of the Indiana conservative hip arthroplasty in 116 hips with a two to seven-year follow-up. There were seventeen failures (14.6 per cent). The rate of non-traumatic loosening was 10 per cent and the failure rate for patients with inflammatory arthritis was 33 per cent. No infections, dislocations, subluxations, pulmonary emboli, or deaths were associated with the procedure. For forty-two hips with a successful result and a minimum follow-up of three years, the radiographs were analyzed. Factors that were found to have a high correlation with success of the arthroplasty were preservation of the acetabular subchondral bone, complete coverage of the acetabular component, and selection of the appropriate sizes of femoral and acetabular components. Radiolucency was not found to be a reliable diagnostic sign of, or prelude to, symptomatic loosening of the prosthetic implant.

Remodeling of bone around hydroxyapatite-coated femoral stems.

Two hundred and twenty-four total hip arthroplasties were performed in 201 patients with use of a femoral component with hydroxyapatite coating of the proximal portion of the stem. The mean duration of follow-up was seventy-one months (range, fifty-eight to eighty-seven months). Of the 224 arthroplasties, 208 (93 per cent; 190 patients) yielded a good or excellent clinical result. Four patients (2 per cent) reported mild-to-moderate activity-related pain in the thigh, and two (1 per cent) had aseptic loosening. The radiographic findings of progressive new-bone formation (cancellous condensation and cortical hypertrophy) throughout the zones adjacent to the middle and distal portions of the stem were evidence of early, extensive proximal fixation of the implant, with distal stress transfer through the implant, which is stiffer than the surrounding bone. Remodeling of the femur began early, was predictable, and progressed throughout the follow-up period. Cortical hypertrophy about the middle and distal portions of the stem occurred predominantly in the mediolateral plane (in 105 hips [47 per cent], compared with thirteen hips [6 per cent] in the anteroposterior plane), and it was more common in patients who had had poorer bone quality preoperatively. Intramedullary osteolysis was present in one femur (0.4 per cent) at five years; the osteolytic area was less than five millimeters in its greatest dimension and had not progressed at the time of the six-year follow-up evaluation. This low rate of osteolysis suggests that a circumferential coating of hydroxyapatite may effectively minimize migration of wear debris along the femoral stem. The progressive remodeling of the femur about the middle and distal portions of the stem, as evidenced by cancellous condensation and cortical hypertrophy, has not, to our knowledge, been described previously to this magnitude in association with proximally coated (porous or hydroxyapatite-coated) femoral implants.

Total hip arthroplasty without cement in obese patients. A minimum two-year clinical and radiographic follow-up study.

A retrospective study of patients who had had a primary total hip arthroplasty without cement between 1983 and 1990 was done to examine differences in clinical and radiographic results between obese and normal-weight individuals. Patients were considered to be of normal weight if the body-mass index (calculated as weight in kilograms divided by height in meters squared) was between twenty and less than thirty, and they were considered to be obese if the body-mass index was thirty or more. There were 127 normal-weight patients (142 hips) and fifty-five obese patients (sixty hips) in the analysis. Eight obese patients (eight hips) who had a body-mass index of forty or more were considered to be morbidly obese and were examined separately as a subset of the obese group. The duration of follow-up averaged forty-eight months (range, twenty-four to ninety-two months). There were no differences between the groups with regard to age, diagnosis, the type of stem or cup, the type of bone, the postoperative level of activity, or the duration of follow-up. The obese patients had a significantly greater loss of blood during the operation than the patients in the normal-weight group. There were no significant differences between groups with regard to the prevalence of perioperative complications, the number of units of blood transfused, the operative duration, or the duration of hospitalization. Of the 202 hips, 184 (91 percent) were pain-free or only mildly painful at the latest follow-up examination.(ABSTRACT TRUNCATED AT 250 WORDS)

Hydroxyapatite-coated total hip femoral components in patients less than fifty years old. Clinical and radiographic results after five to eight years of follow-up.

One hundred and thirty-three patients (152 hips) who were an average of thirty-nine years old (range, sixteen to forty-nine years old) received a proximally hydroxyapatite-coated femoral prosthesis as part of a total hip arthroplasty and were followed for a minimum of five years (average, 6.4 years; range, five to 8.3 years) or until revision. The average Harris hip score was 47 points (range, 22 to 77 points) preoperatively and 93 points (range, 49 to 100 points) at the time of the latest clinical evaluation. Two patients who had a well fixed femoral implant had activity-limiting pain in the thigh at the time of the most recent examination. Radiographic changes consistent with bone-remodeling (cortical hypertrophy and bone condensation) typically were seen around the mid-part of the shaft of the prosthesis. Forty-eight (32 per cent) of the 148 hips that were included in the radiographic analysis demonstrated a small amount of erosive scalloping in either zone 1 or zone 7 of Gruen et al., and intramedullary osteolysis was suspected in only one hip. All stems were radiographically osseointegrated according to a modification of the criteria described by Engh et al. Four stems were revised, but none of the revisions were performed because of mechanical failure (two stems were revised in conjunction with a revision of the cup because of pain; one, because of an infection; and one, after a traumatic femoral fracture that occurred six years postoperatively). Thus, the rates of aseptic and mechanical failure were both 0 per cent. The combined rate of failure, which included the two stems that were revised because of pain and the two stems that were associated with pain that limited activity, was 2.6 per cent (four of 152 stems). The over-all clinical results associated with hydroxyapatite-coated femoral components were excellent in this group of young patients after intermediate-term follow-up. A review of serial radiographs showed mechanically stable implants with osseous ingrowth, evidence of stress transmission at the middle part of the stem, and minimum endosteal osteolysis.

Fixation of acetabular cups without cement in total hip arthroplasty. A comparison of three different implant surfaces at a minimum duration of follow-up of five years.

We evaluated 377 patients (428 hips) who had been managed, by a total of fourteen surgeons at twelve clinical sites in the United States and Europe, with a porous-coated press-fit acetabular cup, a hydroxyapatite-coated threaded screw-in cup, or one of two similar designs of hydroxyapatite-coated press-fit cups between April 1987 and November 1992. The same type of hydroxyapatite-coated femoral stem was inserted without cement in all patients. After a minimum duration of follow-up of five years (mean, 7.9 years; range, 5.3 to 9.1 years), one (1 per cent) of the 131 hydroxyapatite-coated threaded cups, two (2 per cent) of the 109 porous-coated press-fit cups, and twenty-one (11 per cent) of the 188 hydroxyapatite-coated press-fit cups had been revised because of aseptic loosening. A common radiographic sign of impending failure of the hydroxyapatite-coated press-fit cups was radiolucency at the interface between the implant and the subchondral bone beneath it. This radiolucency usually was seen initially more than two years after implantation. Radiographic evaluation of the 383 acetabular implants that were in situ at the time of the most recent follow-up showed that 123 (99 per cent) of the 124 hydroxyapatite-coated threaded cups, 101 (98 per cent) of the 103 porous-coated cups, and 139 (89 per cent) of the 156 hydroxyapatite-coated press-fit cups were stable with osseous ingrowth (as indicated by the absence of radiolucency at the interface and the absence of migration within the acetabulum). The probability of revision due to aseptic loosening was significantly greater for the hydroxyapatite-coated press-fit cups than it was for the hydroxyapatite-coated threaded cups or the porous-coated press-fit cups (p < 0.001 for both comparisons). Within the group of patients who had a hydroxyapatite-coated press-fit cup, the probability of revision due to aseptic loosening was significantly greater in association with a young age (p = 0.003), female gender (p = 0.02), the use of a femoral head with a diameter of thirty-two millimeters (p = 0.018), and the use of a thin polyethylene liner (p < 0.001). We found that the hydroxyapatite-coated threaded cups and the porous-coated press-fit cups continued to perform well more than five years after the operation. The hydroxyapatite-coated press-fit cups that were revised probably failed because the fixation interface beneath the cup could not sustain the tensile stresses that were imposed between the cup and the bone by the activity of the patient. Our data suggest that, in the specific biomechanical environment of the acetabulum, physical interlocking between the cup and the supporting bone beneath it may be a prerequisite for long-term stability.

Early clinical experience with hydroxyapatite-coated femoral implants.

As part of a multi-center study, 238 titanium stems that were proximally coated with hydroxyapatite were implanted in 220 patients between January 1988 and December 1989. Ninety-two of these stems in eighty-three patients had a minimum of two years of follow-up, including analysis of the clinical and radiographic data. Clinically, the patients were essentially pain-free before six months and had a low (4 per cent) prevalence of pain in the thigh and a very high composite Harris hip-score (mean, 95 points) at two years. Radiographically, subsidence was detected in 8 per cent of the implants; no implant had more than three millimeters of subsidence. Radiolucencies were characteristically seen around the uncoated distal part of the stem, in 70 per cent of the implants. Contrastingly, radiolucencies were rare in the hydroxyapatite-coated proximal zones and were most often found anteriorly, in only 5 per cent of the implants. Areas of increased formation of cancellous bone were seen beneath femoral cortical bone at the interface between the hydroxyapatite-coated and uncoated parts of the stem, in 67 per cent of the implants. Calcar resorption was found in 49 per cent of the implants. Cortical thickening was present in 17 per cent of the implants at the uncoated distal part of the stem. Two of the 238 femoral implants were revised: one because of infection and one because of aseptic loosening associated with non-union of a subtrochanteric osteotomy.

Salvage of a recurrently dislocating total hip prosthesis with use of a constrained acetabular component. A retrospective analysis of fifty-six cases.

Fifty-six constrained acetabular components were placed, between April 1988 and February 1993, in fifty-five patients who had had recurrent dislocations (average, six dislocations; range, two to twenty dislocations) of the femoral component after a previous total hip arthroplasty. All patients had additional factors contributing to the instability of the implant, including absence or disruption of the abductor mechanism, poor health, mental retardation, confusion, and Alzheimer disease. One patient was lost to follow-up. The remaining patients were followed clinically for a minimum of three years (average, sixty-four months; range, thirty-seven to ninety-seven months) or until the time of death. During the follow-up interval, only two (4 per cent) of the fifty-five patients had a subsequent dislocation. The use of this type of component should be considered for patients who have recurrent dislocation if other treatment modalities are unlikely to be effective.

Conservative total hip arthroplasty.

Surface replacement arthroplasty of the hip is a relatively new procedure by orthopedic standards. The test of time is not yet far enough along to allow sound conclusions to be made, but the early results have been encouraging. Most of our failures occurred early in our experience, and our resulting have been steadily improving as our knowledge grows. Significant improvements have been made in surgical technique and prosthetic design. Refinements continue, and we are confident that surface replacement will withstand the test of time and prove to be a useful procedure, especially in younger patients suffering from severe cox arthrosis.

Preoperative planning of total hip arthroplasty.

Preoperative planning of a total hip replacement is a necessary first step in arthroplasty. If properly done, it can shorten the learning curve for new prosthetic systems, minimize intraoperative guesswork, and decrease surgical time. It also will allow the surgeon to fulfill one of the universal goals of reconstructive surgery--precision with reproducibility.

Hydroxyapatite in total hip arthroplasty: five-year clinical experience.

Excellent clinical and radiographic results are seen with HA-coated femoral components at 5-year follow up. These stems are well fixed proximally, and the transmission of stress is noted to occur at the transition from the coated to uncoated stem. Longer follow up is needed to determine if the currently stable HA-coated implants will become threatened by wear debris and subsequent osteolysis, as has been the case in many long-term studies of other hip implants.

Reconstruction of acetabular deficiency utilizing iliac bone graft.

ABSTRACT; Acetabular reconstructions were performed on 12 hips possessing deficient acetabuli. Eleven required total hip arthroplasties for relief of pain; seven of which were surface replacements. The one remaining h ip had erosion of the posterior wall, secondary to spastic paraparesis, and the posterior wall was reconstructed. The etiologies of the deficient acetabuli included five secondary to fracture/dislocation, four with acetabular dysplasias, and three related to failed acetabular components from conventional total hip arthroplasties. There were six posterior Hp deficiencies, five superior rim deficiencies, and one central deficiency. The iliac crest provided the graft material utilized in 11 of 12 cases; in one case the femoral head was used for reconstruction. All peripheral defects, however, were handled similarly regardless of the source of graft material, in that all grafts were secured with at least two cortical cancellous screws lagged for compression. Central defects utilized single cortex grafts keyed into the defect upon a bed of cancellous graft and rimmed with methyl methacrylate. All patients were followed at routine intervals; the shortest followup was 14 months, and the longest 32 months. All grafts showed radiographic evidence of union by one year. Three-phase bone scans were routinely done in patients undergoing surface replacement by one year. The scan appearance of the femoral head was identical to other uncomplicated surface replacements. The grafted area showed increased uptake.The purpose of this report is twofold: to present iliac crest as a graft material from which deficient acetabuli can be reconstructed when autogenous femoral head is not available, and to offer a fixation technique potentially less demanding and yet no less secure than those previously suggested. The results of this study indicate that, in selected situations, iliac crest graft acetabuloplasty can be successfully employed so that the total hip arthroplasties may be performed reducing fear of premature acetabular loosening related to insufficient bony coverage of the acetabular component.

Primary cemented total hip arthroplasty: five to twelve year clinical and radiographic follow-up.

A retrospective clinical and roentgenographic study was completed on 131 primary cemented total hip arthroplasties with a minimum of five years follow-up (mean, seven years; range, five to twelve years). Second generation cement technique including plugging of the medullary canal, cement gun filling, and pressurization of the canal was used. Acetabular cement was also pressurized. The total mechanical failure rate of the acetabular components was 18.4% compared to that of the femoral components which was 3.1%. There was a significantly higher incidence of acetabular component failure in rheumatoid arthritis patients (38.9%) compared to a preoperative diagnosis of primary osteoarthritis (14.1%) (p = 0.013). Yet there were no rheumatoid arthritis patients in the femoral component revision group. There were no differences in revision rates for metal-backed versus nonmetal-backed cups (p = 0.113). The average thickness of the proximal medial cement mantle was 2.8 millimeters in the loosening group and 5.4 millimeters in the nonloosening group (p = 0.333). All failures occurred in those patients whose proximal medial cement mantle was less than five millimeters. The authors strongly endorse the use of hybrid total hip arthroplasty and emphasize the need for meticulous surgical technique especially in obtaining a cement mantle of sufficient thickness in the proximal medial aspect of the femur.

When is total hip arthroplasty a failure? The patients' perspective.

Total hip arthroplasty (THA) patients (186 primary, 92 revision) were surveyed regarding their satisfaction, their expectations regarding longevity, of the hip implant, and their perspective on the potential or actual need for revision surgery. The vast majority of patients were glad they had the original THA, would do it again if faced with a similar choice, and would recommend it to others. One-third of patients believed their current implants would last the rest of their life. The most common responses to either potential or actual failure were happiness it lasted as long as it did, accepting it as "one of those things," and disappointment. No primary THA patients and only 7% of revision of THA patients indicated that they would consider the primary THA a failure when revision surgery was indicated.

Timing of the revision total hip replacement.

The purpose of this article is to define guidelines in regard to timing of revision surgery for total hip replacement. One important variable, in addition to incapacitating pain, is the presence of progressive bone loss associated with loose implants. Indications for revision are presented based on the immediacy of the situation. Timing for revision is categorized as immediate, delayed up to 6 months, delayed beyond 6 months, and elective. Clinical examples of indications are included. Useful diagnostic studies for evaluating the need for revision surgery are discussed. These procedures include several types of arthrography to aid in differential diagnosis.