Hip challenges: what would you do?
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Arthroplasty, Replacement, Hip↗
Biomedical subjects
C A Engh
Publications and source records attributed to C A Engh.
Revision of loose cementless femoral prostheses to larger porous coated components.
The results of 21 revision hip arthroplasties were reviewed. The indication for each revision was a symptomatically loose porous coated femoral component. The loose stems were all replaced with Anatomic Medullary Locking stems. In 16 of the 21 procedures, the acetabular component also was revised. Complications included two intraoperative femoral fractures, one sciatic nerve palsy, and one case of multiple hip dislocations. The mean Harris Hip Score was significantly improved from a mean of 42 points (range, 23-90 points) preoperatively to a mean of 84 points (range, 59-100 points) 6.3 years after the revision. Ninety-five percent of the patients reported less severe hip pain. Ninety percent had improved walking ability. Eighty-five percent stated that they were satisfied with the results of the revision procedure. No femoral component has shown radiographic or clinical signs of repeat loosening, and none have been rerevised. It was concluded that when a cementless femoral component becomes symptomatically loose, replacing the loose stem with a larger and more extensively porous coated component is a successful method for achieving better implant fixation.
Adult↗
Total hip arthroplasty. Concerns with extensively porous coated femoral components.
A series of 507 consecutive, unselected cementless hip arthroplasties performed by one surgeon was reviewed to address specifically potential concerns with the use of extensively coated femoral components, including the frequency and nature of reoperation, thigh pain, component stability, osteolysis, and stress shielding. Excluding hips in patients who had died or were lost to followup, there were 426 hips with minimum 5-year followup. The overall femoral reoperation rate of 2.6% (13 cases) included seven for failure of fixation and six for osteolysis. Of the unrevised cases, 96% of the femoral components showed radiographic bone ingrowth, and 3.7% showed a stable fibrous pattern. Fixation did not deteriorate with time. A 2.9% incidence of activity limiting thigh pain did affect clinical outcome (limp, ambulation tolerance, support), but there were no clinical or radiographic predisposing variables. There was no detectable femoral osteolysis in 88.3% of cases. The remainder had lesions confined to Gruen Zones 1 and 7, suggesting that circumferential extensive coating was protective against distal osteolysis. Although osteolysis did not affect component stability, in six cases it did result in pathologic trochanteric fracture, contributing to the frequency of reoperation. Stress shielding was common (25%) and was related to older patients and the use of larger diameter stems (> 15 mm), but did not predispose to thigh pain, loosening, osteolysis, or an inferior clinical result. These results documented the clinical and radiographic success in the use of extensively coated cementless femoral components. Debris generation from wear and resulting osteolysis remain significant concerns in a hip arthroplasty with this design as with many others. However, concerns about the high incidence of reoperation, thigh pain, component instability, or stress shielding are not supported by this study.
Activities of Daily Living↗
Long-term clinical consequences of stress-shielding after total hip arthroplasty without cement.
Remodeling of the femur, or so-called stress-shielding, was observed on the two-year postoperative radiographs of forty-eight (23 per cent) of 207 hips that were part of a consecutive, non-selected series of 223 hips that had had a primary arthroplasty with use of the anatomic medullary locking hip system. Three patients (three hips) died within ten years after the arthroplasty, leaving forty-four patients (forty-five hips) who had a minimum of ten years of clinical follow-up. At the time of the latest follow-up, thirty-eight patients (86 per cent) reported that they had either no or mild pain related to the hip, forty-two (95 per cent) had less pain than they had had preoperatively, and forty-one (93 per cent) were satisfied with the results of the arthroplasty. Two patients had a reoperation, but neither procedure involved the femoral component; specifically, one patient had a revision of a loose acetabular component and one had an exchange of a polyethylene liner. No femoral component was associated with clinical or radiographic evidence of loosening. Femoral osteolysis, confined to zones 1 and 7 of Gruen et al., was observed on the ten-year radiographs of four of the thirty-three hips for which such radiographs were available. Stress-shielding (defined as evidence of pronounced femoral bone-remodeling on the two-year radiographs) had not adversely affected the outcome for these four hips by the time of the latest follow-up. The findings regarding postoperative pain, function, and over-all satisfaction for the forty-four patients (forty-five hips) who were included in the present study were similar to those reported for our larger (parent) series of patients who had been managed with the anatomic medullary locking hip system and to those reported for a similar series of patients who were followed for 9.5 years after the insertion of a porous-coated anatomic prosthesis. In addition, the prevalence of acetabular and femoral osteolysis (four [12 per cent] of thirty-three hips) and that of revision of the femoral component (zero [0 per cent] of forty-five hips) were lower than those for our larger (parent) series (fifty-four [39 per cent] of 137 hips and three [1 per cent] of 201 hips, respectively) as well as those for the series of patients who had been managed with the porous-coated anatomic prosthesis (thirty-five [45 per cent] and four [5 per cent] of seventy-eight hips, respectively).
Adolescent↗
Radiographic evaluation of penetration by the femoral head into the polyethylene liner over time.
UNLABELLED: We examined the pattern of temporal penetration by thirty-two-millimeter-diameter femoral heads into polyethylene liners in a group of 105 hips (103 patients) in which an Arthropor metal-backed cup had been implanted. Each patient was evaluated radiographically and clinically at a minimum of four different postoperative intervals. The initial evaluation was performed a mean of 2.9 weeks (range, one to fifteen weeks) postoperatively, and the latest evaluation was performed a mean of 7.9 years (range, five to ten years) postoperatively. Two-dimensional wear - that is, penetration by the femoral head into the ultra-high molecular weight polyethylene liner - was determined from anteroposterior radiographs of the pelvis with a computer analysis system that calculated the change in the position of the center of the head relative to the center of the cup. Three new findings are reported. First, there was a large difference (mean, 1.1 millimeters) between the center of the head and that of the cup as measured on the initial postoperative radiographs. This difference underscores the need for researchers to consider the initial displacement of the head when measuring and reporting polyethylene wear. Second, although there was wide variation in responses among individuals, temporal examination of the data revealed a trend toward a decreasing rate of penetration with time. Moreover, the rate of penetration appeared to reach a steady-state value after the sixth postoperative year and remained nearly constant until the ninth postoperative year. Third, by comparing the subsets of patients who had the greatest and the least initial penetration by the head, we found that penetration behavior, although remarkably different between the groups in the first three years postoperatively, became similar with time. CLINICAL RELEVANCE: When making decisions regarding individual patients or hip systems that demonstrate penetration by the femoral head into the polyethylene liner, clinicians should consider the patterns of penetration over time. Measurements of the amount and rate of penetration that are based solely on the most recent radiograph do not represent the full clinical picture. We advocate more frequent radiographic follow-up and, when available, analysis of serial radiographs for patients who have excessive penetration by the femoral head into the acetabular liner.
Adult↗
Treatment of pelvic osteolysis associated with a stable acetabular component inserted without cement as part of a total hip replacement.
Thirty-five patients who had had a primary total hip replacement with a porous-coated acetabular component inserted without cement had a revision procedure to treat pelvic osteolysis. The mean age at the time of the revision operation was forty-nine years (range, twenty-nine to eighty-five years). Forty-six distinct pelvic osteolytic lesions were noted radiographically around the thirty-five cups. These lesions ranged in size from 0.5 by 0.5 centimeter to 6.3 by 2.7 centimeters (mean, 2.6 by 1.7 centimeters). Fourteen of the thirty-five patients had no or only slight occasional pain at the time of diagnosis of the pelvic osteolysis, fifteen patients had pain attributed to a loose femoral component, one had pain related to a spontaneous fracture of the greater trochanter, and one had pain related to recurrent subluxation. The remaining four patients had pain in the groin despite radiographically stable implants. All of the metal-backed porous-coated acetabular components were stable according to the preoperative radiographs, and the stability was confirmed at the time of the revision. The metal shell was left in place and the acetabular liner was exchanged in all thirty-five patients. The osteolytic lesions were debrided, and thirty-four of the forty-six lesions were filled with allograft bone chips. The patients were evaluated a minimum of two years (range, two to five years; mean, 3.3 years) after the revision operation, and all thirty-five sockets were found to be radiographically stable. The bone grafts appeared to have consolidated, and none of the osteolytic defects had progressed. One-third of the lesions were no longer visible on radiographs, regardless of whether or not they had been filled with bone graft. The remaining lesions had decreased in size. It appears that, in the short-term, exchange of the liner and debridement of the granuloma, with or without use of allograft bone chips in the osteolytic defect, is a reasonable alternative to revision of the socket provided that the metal shell is solidly fixed at the time of the revision operation. If the metal shell has been markedly damaged by the femoral head, the locking mechanism for the polyethylene liner is not intact, or a satisfactory replacement liner is not available, then revision of the porous-coated acetabular component is indicated. These results must be considered preliminary. Since osteolysis may take several years to redevelop after a revision, additional follow-up is required.
Acetabulum↗
Titanium prosthetic wear debris in remote bone marrow. A report of two cases.
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Acetabulum↗
History of the American health care system: its cost control programs and incremental reform.
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Cost Control↗
Femoral fixation in primary total hip arthroplasty.
We have presented the major advantages of using femoral components that have porous coating over the entire stemmed portion and have a cylindrical distal shape. The advantages of a stem with these design features also are reflected in the changing pattern of hip implant usage. A decade ago, the most frequently used porous-coated implants were those designed predominantly for metaphyseal fixation. At that time, the only commercially available, extensively porous-coated stem with a cylindrical distal stem shape was the anatomic medullary locking (AML) prosthesis. Currently, the most commonly used porous-coated prosthesis is the extensively porous-coated AML. Virtually all implant manufacturers now make a stem with design features similar to the AML. While concerns about stress shielding and prosthesis removal remain, they have not proven to be a clinical problem in our experience. We have used these stems in all of our primary total hip arthroplasties for 20 years and continue to do so.
Cementation↗
Hip challenges: what would you do?
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Adult↗
Long-term results of use of the anatomic medullary locking prosthesis in total hip arthroplasty.
A total hip arthroplasty was performed, with use of the anatomic medullary locking hip system, in 223 consecutive, non-selected hips in 215 patients. The mean age of the patients at the time of the operation was fifty-five years (range, sixteen to eighty-seven years). Twenty-one patients (twenty-two hips) were lost to follow-up and twenty-seven patients (twenty-seven hips) died less than ten years postoperatively. The remaining 167 patients (174 hips) were followed for a minimum of ten years (mean, eleven years; maximum, thirteen years). There were twenty reoperations involving a component. The rate of survival at twelve years was 0.97 +/- 0.02 (mean and standard error) for the stem and 0.92 +/- 0.03 for the cup. Patients who had osteolysis were younger than those who did not have osteolysis (mean age, forty-seven compared with fifty-six years; p < 0.01). Similarly, patients who had a reoperation were younger than those who did not have a reoperation (mean age, forty-six compared with fifty-four years; p < 0.01). The radiographic appearance of progressive wear that, in our opinion, was severe enough to cause the femoral head to completely penetrate the polyethylene liner was the most frequent reason for reoperation.
Adolescent↗
Incidence of late bead shedding from uncemented porous coated cups. A radiographic evaluation.
A radiographic study was performed on late head separation from the porous surface of clinically well functioning and radiographically stable Arthropor uncemented acetabular components. Of 104 cups in 102 patients, 11 (10.6%) showed bead separation from the porous coated surface. Bead shedding occurred at an average of 4.2 years (range, 2-7 years). In each case the phenomenon was progressive. In the group that shed beads, there was a higher prevalence of acetabular radiolucencies (63.6% versus 25.8%) and of osteolysis (45.5% versus 10.8%). These differences were statistically significant. The group that shed beads also had a higher polyethylene wear rate (0.21 mm/year versus 0.16 mm/year) and were younger (49.5 years versus 59.5 years). All cups that shed beads remained clinically and radiographically stable. Thus, the clinical impact of these observations is uncertain. However, the higher prevalence of acetabular lucencies and osteolysis in these patients, in combination with an increased polyethylene wear rate, require thorough clinical and radiographic followup to uncover potential loosening problems of these acetabular components.
Acetabulum↗
Treatment of complications in primary cementless total hip arthroplasty.
Five hundred eight consecutive cases (481 patients) treated with the extensively porous coated Anatomic Medullary Locking prosthesis were followed for an average of 9 years (range, 5-14 years). Thirty-one (6%) hips were lost to followup and 33 (7%) hips had complications that required revision surgery. The indications for revision were symptomatic stem loosening (six cases), symptomatic cup loosening (five cases), asymptomatic periarticular osteolysis (seven cases); trochanteric fracture through an osteolytic cyst (four cases), polyethylene fracture (five cases), sepsis (one case), and heterotopic ossification (one case). The surgical treatment of these complications is described. After these revisions, 11 (33%) cases had additional complications, most commonly a dislocation. Four required a second revision. Questionnaires and physical examinations were used to compare the outcome of the cases requiring revision with the outcome of those that did not. There were no differences in patient satisfaction between cases requiring revision surgery and those that did not (97% and 95% patient satisfaction, respectively). Function was also similar between the two groups, with 93% reporting increased function in each group.
Adolescent↗
Fractures through cystic lesions of the greater trochanter. A cause of late pain after cementless total hip arthroplasty.
Four patients who presented with sudden onset of hip pain 7 to 11 years after successful porous-coated cementless hip arthroplasty are described. These four patients were all diagnosed to have fractures through osteolytic cysts in the greater trochanter. One patient was seen initially with a displaced fracture of the greater trochanter. Two patients were treated operatively with curettage of the cystic area and with polyethylene exchange. One of these patients underwent revision of the femoral component in addition to the polyethylene exchange. Two patients were treated nonoperatively. The fractures treated nonoperatively have healed and the patients have resumed their normal activities. This report should stimulate an awareness of fractures through cystic lesions of the greater trochanter as a late cause of hip pain after porous-coated cementless hip arthroplasty.
Adult↗
An analysis of a retrieved Prodigy femoral prosthesis.
Radiographic and histologic data of an autopsy-retrieved femur containing a Prodigy stem (DePuy, Warsaw, IN) in situ for 26 months were analyzed. The Prodigy is a porous-coated Anatomic Medullary Locking stem modified with a smooth groove, the Redux Groove, on its medial central portion. This Redux Groove, designed to increase stem flexibility and decrease periprosthetic bone resorption, decreases the porous surface area available for bone ingrowth. In this case, however, the decreased porous area did not affect diaphyseal bone ingrowth. Additionally, although there is a concern that the groove will provide a pathway for debris migration, no evidence of debris was found in the tissue at the groove site. Although the Redux Groove's value in decreasing periprosthetic bone loss is still uncertain, this case demonstrated less proximal bone loss than was reported in similar dual-energy x-ray absorptiometry studies of autopsy cases containing Anatomic Medullary Locking stems without a groove. Analysis of more cases with longer in situ intervals is necessary to determine if the groove decreases resorptive bone remodeling and if the groove becomes a conduit for particulate debris migration. It is emphasized that results of this one case may not be representative of all Prodigy cases.
Absorptiometry, Photon↗
Bone remodeling around cementless hip implants.
Bone remodeling results from the adaptation of bone to the stresses that act upon it. The insertion of an endoprosthesis into a femur changes the stress distribution within the femur, causing the bone to remodel. In this paper, we show how radiographic bone remodeling changes can be used to determine implant fixation and how bone remodeling changes can be quantitated by using dual-energy x-ray absorptiometry analysis as well as computer-assisted videodensitometry.
Absorptiometry, Photon↗
Wear of polyethylene cups in total hip arthroplasty. A study of specimens retrieved post mortem.
The wear of polyethylene components of total hip replacements has previously been studied radiographically and by analysis of retrieved components. The extent of wear, however, has largely been determined from components retrieved at reoperation and has therefore been based on a subset of patients in whom the prosthesis is more likely to show excessive wear. The study of cups retrieved post mortem provides a better indication of the extent of wear of well functioning components. Twenty-six polyethylene liners were retrieved at autopsy from nineteen patients, after a mean of ninety-one months (range, thirty-three to 206 months) in situ. Each component had articulated with a thirty-two-millimeter-diameter femoral head. The components were evaluated visually for evidence of polyethylene wear such as pitting, scratching, and burnishing. Additionally; a shadowgraph technique was used to examine molds of the inner surface of the liner to determine the direction and extent of wear. The mean extent of linear wear of the retrieved liners was 0.45 millimeter (range, 0.17 to 1.07 millimeters), and the mean rate of wear was 0.07 millimeter (range, 0.02 to 0.18 millimeter) per year. The mean volumetric wear was 245.3 cubic millimeters (range, 13.0 to 779.1 cubic millimeters), and the mean rate of volumetric wear was 39.8 cubic millimeters (range, 1.0 to 131.3 cubic millimeters) per year. The mean rate of wear for the twenty-six liners was 45 to 69 per cent less than the rates reported in the literature for polyethylene liners retrieved at reoperation. Examination of the articulating surface did not reveal gross evidence of surface failure such as delamination or fatigue cracks. In general, the surfaces were merely burnished and scratched. The rates of wear of press-fit, metal-backed liners were significantly higher than those of all-polyethylene cemented components (p < 0.05). Additionally, statistical analysis revealed no correlation between wear and the patient's age, weight, or gender; the duration of implantation; or the thickness of the polyethylene. These results indicate that wear of the polyethylene of well functioning hip replacements is not as excessive as reported previously.
Acetabulum↗
What would you do? Challenges in hip surgery.
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Aged↗