20-year experience with cemented primary and conversion total hip arthroplasty using so-called second-generation cementing techniques in patients aged 50 years or younger

We present the 20-year experience of 47 hips in 40 patients aged 50 years or younger with cemented primary total hip arthroplasty using second-generation femoral cementing techniques. Average follow-up duration in the 23 patients living at least 17 years was 18.2 years. Overall, 18 hips (38%) had components revised or removed for any reason, at an average duration of 12.6 years. Every revision or reoperation involved removing the acetabular component. Of these 18 acetabular components, 15 (32%) were revised for aseptic loosening. Eleven additional acetabular components were loose by radiographic criteria at final follow-up, yielding prevalence of aseptic acetabular loosening (55%). Four femoral components (8%) were revised for osteolysis without loosening, and 3 (6%) were revised for aseptic loosening. Femoral osteolysis, with or without component loosening, led to revision in 5 ( 11%) hips compared with 6% for aseptic loosening alone. Osteolysis was the primary problem leading to acetabular and femoral component revision in this series of people < or = 50 years old over the first 20 years after the index operation.     

Acetabular revision with morsellised allogenic bone graft and a cemented metal-backed component

Failure of total hip arthroplasty with acetabular deficiency occurred in 55 patients (60 hips) and was treated with acetabular revision using morsellised allograft and a cemented metal-backed component. A total of 50 patients (55 hips) were available for clinical and radiological evaluation at a mean follow-up of 5.8 years (3 to 9.5). No hip required further revision of the acetabular component because of aseptic loosening. All the hips except one had complete incorporation of the allograft demonstrated on the radiographs. A complete radiolucent line of > 1 mm was noted in two hips post-operatively. A good to excellent result occurred in 50 hips (91%). With radiological evidence of aseptic loosening of the acetabular component as the end-point, the survivorship at a mean of 5.8 years after surgery was 96.4%. The use of impacted allograft chips in combination with a cemented metal-backed acetabular component and screw fixation can achieve good medium-term results in patients with acetabular bone deficiency.     

High placement of noncemented acetabular components in revision total hip arthroplasty. A concise follow-up, at a minimum of fifteen years, of a previous report

We previously reported the average ten-year results associated with the use of porous-coated noncemented acetabular shells that were placed at a high hip center at the time of revision total hip arthroplasty in thirty-four patients (thirty-six hips) with severe acetabular bone loss. We now report the average 16.8-year results for twenty-one patients (twenty-three hips). Of the original cohort of forty-four patients (forty-six hips), thirty-nine patients (forty-one hips; 89%) retained the shell. Two shells (4.3%) were revised because of aseptic loosening, and three (6.5%) were revised because of infection. Six femoral components were revised because of femoral osteolysis, and seven were revised because of aseptic loosening without osteolysis. On the basis of our results after an average duration of follow-up of 16.8 years, we believe that the placement of an uncemented acetabular component at a high hip center continues to be an excellent technique for revision total hip arthroplasty in selected patients with severe acetabular bone loss.     

Long-Term Survival of the Cemented Exeter Universal Stem in Patients 50 Years and Younger: An Update on 130 Hips

BackgroundThere is variable evidence regarding survivorship beyond 20 years of total hip arthroplasties in young patients. We report the long-term results of the Exeter cemented hip system in patients ≤50 years at minimum of 20 years.MethodsClinical and radiological outcomes of 130 consecutive total hip arthroplasties in 107 patients aged 50 years or younger at primary operation were reviewed; 77% had a diagnosis other than osteoarthritis. All patients were followed at 5-year intervals, no patients were lost to follow-up, and the status of every implant is known.ResultsMean age at surgery was 41.8 (17-50) years. Mean follow-up was 22.0 (20.0-26.1) years. There were 79 hips surviving, 14 hips (11 patients) deceased, and 37 hips revised. Reasons for revision: 29 hips for aseptic cup loosening (26 stems revised using cement-in-cement, three left in-situ); three stems for femoral osteolysis, two related to acetabular polyethylene wear (14.1 and 17.0 years), one with Gaucher’s disease (21.1 years); one broken stem (12.9 years); one cup for instability (4.3 years–stem revised using cement-in-cement); and two hips with infection (8.5 and 23.8 years). There were no cases of aseptic loosening of the Exeter stem. There were no radiologically loose stems although eight patients had radiological evidence of loosening of the cemented cup. Survivorship at 22 years was 74.9% for revision for all causes and 96.3% for revision of the stem for aseptic loosening or lysis.ConclusionThe Exeter cemented stem has excellent survivorship at minimum 20 years in young patients. Acetabular component survivorship was less favorable, but the advent of highly cross-linked polyethylene may improve this in the long term.     

Cementless Acetabular Socket Revisions Using Metasul Metal-on-Metal Bearings

Thirty-four hips were treated with cementless acetabular socket revisions using a metal-on-metal bearing. The causes of revision were aseptic loosening in 33 hips and septic loosening in 1 hip. Revisions were performed for acetabular sockets in 28 hips and for acetabular sockets and femoral stems in 6 hips. Mean follow-up duration was 6.2 years (range, 4.0-9.1 years), and mean Harris Hip Scores improved from 56 to 92 points. No hip required further revision for aseptic loosening. Focal femoral osteolysis newly developed in zone I in 1 hip, which was treated by curettage and bone grafting. The authors suggest that second-generation metal-on-metal bearings in cementless acetabular socket revisions can achieve good medium-term clinical and radiographic results.     

The fate of stable femoral components retained during isolated acetabular revision: a six-to-twelve-year follow-up study

BACKGROUND: The decision as to whether to revise a well-fixed femoral component in hips requiring isolated acetabular revision is challenging. The purpose of the present study was to determine the long-term results of, and the complications associated with, retention of a stable and well-fixed femoral component during isolated acetabular revision. METHODS: We retrospectively reviewed the clinical and radiographic results for thirty-one patients (thirty-two hips) who underwent isolated revision acetabuloplasty without removal of a well-fixed femoral component. The reason for acetabular revision was aseptic loosening in thirty-one hips and malposition in one hip. Of the thirty-two femoral components, twenty-one were cemented and eleven were cementless. The average duration of follow-up from the time of the index revision was 8.1 years (range, 6.4 to 12.5 years), and the average duration of total service of the femoral component was seventeen years (range, seven to twenty-five years) from time of the initial implantation. The average age of the patients at the time of the index revision was sixty-six years (range, twenty-nine to eighty-seven years). RESULTS: Thirty-one (97%) of the primary femoral components were judged to be stable and well fixed at the latest follow-up evaluation. One femoral component (3%) was revised because of aseptic loosening, eight years after the index acetabular revision and seventeen years after the initial total hip arthroplasty. Radiographic evaluation of the thirty-one femoral components that were not revised demonstrated no evidence of loosening or subsidence. There were no dislocations, nerve palsies, or intraoperative fractures associated with retention of the femoral component. Twenty-seven (84%) of the acetabular components were judged to be stable at the latest follow-up evaluation. CONCLUSION: In hips treated with isolated acetabular revision, a well-fixed femoral component can be retained successfully without adversely affecting the acetabular exposure; the placement, position, or stability of the acetabular component; or the ability to restore bone stock. The data from the present study support the decision to retain a well-fixed femoral component when the acetabular component needs to be revised.     

Total hip arthroplasty with cement and without acetabular bone graft for severe hip dysplasia. A concise follow-up, at a minimum of twenty years, of a previous report

We previously evaluated a cohort of fifty-three patients with severe hip dysplasia (Crowe Type-II, III, or IV subluxation) who underwent a total of sixty-six Charnley total hip arthroplasties. The acetabular component was placed at the anatomic hip center, the superolateral defect was filled with cement, and no bone-grafting was used to supplement the acetabular wall. All but one patient, who was lost to follow-up, were followed until death or for a minimum of twenty years. Radiographic and functional follow-up data were collected prospectively. This retrospective review included twenty-four patients (thirty-four hips) who were alive at a minimum of twenty years following the surgery. Fourteen (22%) of the sixty-five hips underwent revision of a component, with eleven of the revisions performed because of aseptic loosening. Eight of those eleven hips underwent revision because of acetabular loosening alone; two, because of femoral loosening alone; and one, because of loosening of both components. The combined prevalence of revision because of aseptic loosening of the acetabular component and radiographic evidence of failure of the acetabular component was 28% (eighteen hips). With the numbers available, the need for acetabular revision was not associated with the percentage of cement coverage (p = 0.362) or the Crowe classification (p = 0.159). At a minimum of twenty years postoperatively, the survivorship of the acetabular component was 86% +/- 8% with revision because of aseptic loosening as the end point and 82% +/- 10% with revision because of aseptic loosening or radiographic evidence of loosening as the end point. The results that we evaluated at a minimum of twenty years after use of this technique can be compared with the results of other techniques in studies with similar long-term follow-up periods.     

Total hip arthroplasty with a cemented, polished, collared femoral stem and a cementless acetabular component. A follow-up study at a minimum of ten years

BACKGROUND: Recent studies have suggested that cemented femoral components with a polished surface may provide superior long-term fixation when compared with femoral components with a roughened surface. The purpose of this study was to evaluate the results of total hip arthroplasty with a cemented femoral component with a polished surface finish and compare them with the results of total hip arthroplasty performed with a similar design of cemented femoral component with a rougher surface finish. METHODS: We retrospectively reviewed a consecutive group of 132 patients (149 hips) in whom primary total hip arthroplasty had been performed by one surgeon using a cemented collared femoral component with a polished (0.1-microm Ra) surface finish and a cementless acetabular component. Ninety-eight patients (115 hips) were followed for a minimum of ten years. We compared the survivorship of this prosthesis with that of a femoral component of similar design but with rougher surfaces (matte or grit-blasted). RESULTS: No polished stems were revised because of aseptic loosening or demonstrated radiographic evidence of loosening; however, eight hips (5.4%) with a polished stem demonstrated osteolysis distal to the greater or lesser tro-chanter. In contrast, six stems (2.0%) with a matte surface finish of 0.8-microm Ra were revised because of aseptic loosening, and an additional five stems were seen to be loose radiographically. Eleven stems (9.2%) with a grit-blasted surface finish of 2.1-microm Ra were revised because of aseptic loosening, and an additional four stems were seen to be loose radiographically. The difference in the prevalence of revision due to aseptic loosening between the group with the 0.1-microm Ra surface and the group with the 2.1-microm Ra surface was significant (p = 0.001), as was the difference between the prevalence of revision due to aseptic loosening between the group with the 0.8-microm Ra surface and the group with the 2.1-microm Ra surface (p = 0.001). No cups were revised because of aseptic loosening, and one hip had radiographic signs of acetabular loosening. CONCLUSIONS: This study demonstrated excellent durability of a prosthesis consisting of a cemented, collared, polished femoral component and a cementless acetabular component. While no hips were revised because of aseptic loosening, distal femoral osteolysis was observed in eight hips (5.4%), a higher prevalence than has been reported by others after similar durations of follow-up of tapered, collarless, polished femoral components.     

Clinical and radiological evaluation of revision hip arthroplasty using the cement-in-cement technique

We reviewed 44 consecutive revision hip replacements in 38 patients performed using the cement-in-cement technique. All were performed for acetabular loosening in the presence of a well-fixed femoral component. The mean follow-up was 5.1 years (2 to 10.1). Radiological analysis at final follow-up indicated no loosening of the femoral component, except for one case with a continuous radiolucent line in all zones and peri-prosthetic fracture which required further revision. Peri-operative complications included nine proximal femoral fractures (20.4%) and perforation of the proximal femur in one hip. In five hips wiring or fixation with a braided suture was undertaken but no additional augmentation was required. There was an improvement in the mean Japanese Orthopaedic Association score from 55.5 (28 to 81) pre-operatively to 77.8 (40 to 95) at final follow-up (p < 0.001). Revision using a cement-in-cement technique allows increased exposure for acetabular revision and is effective in the medium term. Further follow-up is required to assess the long-term results in the light of in vitro studies which have questioned the quality of the cement-in-cement bond.     

Minimum 20-Year Follow-Up Results of Revision Total Hip Arthroplasty With Improved Cementing Technique

A consecutive, non-selective cohort of 83 (77 patients) cemented total hip arthroplasty revisions using contemporary cementing techniques was analyzed at a minimum of 20 years following the index procedure. No patients were lost to follow-up. The average age at revision was 62.4 years (23 to 89). Twenty-two hips (26.5%) had had a reoperation, eighteen (21.7%) for aseptic loosening, 3 (3.6%) for femoral prosthesis fracture and 1 (1.2%) for dislocation. The incidence of re-revision for aseptic femoral loosening was 7.5% and for aseptic acetabular loosening was 21.7%. These results confirm that cemented femoral revision using improved cementing techniques is a durable option in revision hip surgery. In contrast to this, THA revisions using a cemented acetabular component have been less durable at this length of follow-up.     

Revision total hip arthroplasty in patients younger than 55 years old. Clinical and radiologic results after 4 years

Since 1979, all revision total hip arthroplasties performed in Sweden have been entered into a prospective multicenter study. Between 1979 and 1982, 65 patients (67 hips) younger than 55 years old required revision arthroplasty because of aseptic loosening. These patients were followed clinically and radiographically for 2-6 years (mean, 4 years). Thirteen patients requiring a second revision because of a recurrent aseptic loosening and one because of subluxations were classified as failures and were not included in the final follow-up study. In the remaining 52 hips (50 patients), the results, rated by the Harris hip score, were good or excellent in 15 hips (29%), fair in 9 hips (17%), and poor in 28 hips (54%). Early complications were rare. Ten hips in 10 patients had radiographic signs of gross loosening of the acetabular or femoral component. mechanical failure, defined as gross loosening or a second revision, was identified in 36% of hips included in the study (n = 67). Revision hip arthroplasty using cement in young and middle-aged patients with cemented primary arthroplasty gave a high rate of failure, because of aseptic loosening. The use of alternative methods and techniques must be explored for revision surgery in younger patients.     

Revision of a cemented acetabular component to a cementless acetabular component. A ten to fourteen-year follow-up study.

BACKGROUND: Although cementless acetabular components are routinely used in revision hip surgery, few investigators have evaluated the retention and efficacy of these components in the long term. In the current study, the clinical and radiographic outcomes of a series of arthroplasties performed by one surgeon with a cementless acetabular component were assessed at a minimum of ten years. METHODS: From 1986 through 1988, sixty-one consecutive revision total hip arthroplasties were performed in fifty-five patients because of aseptic failure of one or both components of a prosthesis in which both components had been cemented. Twenty-eight patients (thirty-two hips) were alive at a mean of 12.9 years (range, 11.5 to 14.3 years) after the operation. In all of the patients, the acetabular component was revised to a porous-coated Harris-Galante component inserted without cement, and the femoral component was revised to an Iowa component affixed with contemporary cementing techniques. The hips were evaluated clinically and radiographically at a minimum of ten years subsequent to the index revision. No hips were lost to follow-up. RESULTS: None of the acetabular components required revision because of aseptic loosening. Two hips (3%) demonstrated radiographic evidence of aseptic loosening of the acetabular component. The polyethylene liner was exchanged during the follow-up period in eight hips. CONCLUSION: After a minimum of ten years of follow-up, cementless acetabular fixation in revision hip arthroplasty had produced durable results that were markedly better than those reported for acetabular fixation with cement.     

A second-generation cementless total hip arthroplasty mean 9-year results

Two hundred fifty-eight primary total hip arthroplasties in 231 patients were implanted using a circumferentially, proximally porous-coated, collared femoral component and a cementless, hemispherical, porous-coated acetabular component and followed up for a mean of 9 years (5-14 years). Four femoral components were revised (2 stems for infection and 2 stems for aseptic loosening). One additional femoral component was radiographically loose at last follow-up. Nine hips underwent acetabular revision (4 for instability, 2 for infection, 2 for loosening, and 1 for osteolysis). Ten-year survivorship with revision or loosening of any component as the end point was 92%; with femoral component aseptic loosening as end point, survivorship was 98%; with acetabular aseptic loosening as the end point, survivorship was 99%. Osteolysis was identified in 26 hips (13%).     

Acetabular reconstruction with impaction bone-grafting and a cemented cup in patients younger than fifty years old

BACKGROUND: Acetabular bone deficiency can present a challenge during total hip arthroplasty, especially in young patients. The purpose of the present study was to evaluate the long-term clinical and radiographic outcomes of primary and revision acetabular reconstruction with use of an impaction bone-grafting technique and a cemented polyethylene cup in young patients who had preexisting acetabular bone deficiency. METHODS: Forty-two consecutive acetabular reconstructions were performed in thirty-seven patients who were younger than fifty years old (average, 37.2 years old). The impaction bone-grafting technique was used for twenty-three primary and nineteen revision acetabular reconstructions. Twenty-eight patients (thirty-one hips) were available for review after a minimum duration of follow-up of fifteen years. Clinical and radiographic results were assessed, and survivorship analysis was performed with the Kaplan-Meier method. RESULTS: Eight hips were revised at a mean of twelve years (range, three to twenty-one years) after a primary reconstruction (four hips) or revision reconstruction (four hips). The revision was performed because of aseptic loosening of the acetabular component in four hips and because of culture-proven septic loosening in two. Two additional cups (both in hips that had had a revision reconstruction) were revised, during revision of the femoral stem, because of wear (one hip) or because of persistent intraoperative instability (one hip). Twenty-eight hips (in twenty-five patients) had retention of the acetabular component for a minimum of fifteen years. The mean Harris hip score for that group was 89 points. Twenty-six of these twenty-eight hips had no or slight pain. Kaplan-Meier analysis revealed a twenty-year survival rate of 80% (95% confidence interval, 67% to 94%) with acetabular revision for any reason as the end point and of 91% (95% confidence interval, 80% to 100%) with acetabular revision because of aseptic loosening as the end point. CONCLUSIONS: Acetabular reconstruction with use of impaction bone-grafting and a cemented polyethylene cup is a reliable and durable technique that is associated with good long-term results in young patients with acetabular bone-stock defects.     

Omnifit cementless total hip arthroplasty. A 10-year average followup.

Seventy-six hips in 67 patients were evaluated an average of 119 months (range, 61-150 months) after total hip arthroplasty with porous coated Omnifit femoral and acetabular components. The patients were young (average age, 45 years), and most were male (67%). Two stems and one cup were revised for aseptic loosening, for aseptic revision rates of 2.6% on the femoral side and 1.3% on the acetabular side. Thigh pain was present in three cases, one of which was activity limiting. Twenty-five (35.7%) hips had evidence of osteolysis confined to proximal Gruen Zone 1 or 7 or to the acetabulum (22 proximal femoral, three both). There were no cases of intramedullary osteolysis in surviving stems. Thirteen (17.1%) hips have undergone reoperation for bone grafting of progressive proximal osteolysis without component revision, at an average 93 months after the total hip arthroplasty. At an average 40 months after reoperation, all stems remain well fixed, and there has been no recurrence of osteolysis of grafted femoral lesions. These results suggest that a circumferentially proximally porous coated femoral component in cementless total hip arthroplasty can provide stable fixation for as long as 12 years after implantation and caseal the canal from distal osteolysis. Serious concerns remain about the incidence of proximal femoral osteolysis.     

Excellent Long-Term Survival Rate of Polished,Tapered, Cemented Stems in Patients Aged 35 Years or Younger With Avascular Necrosis or Inflammatory Arthritis of the Hip

BackgroundTotal hip arthroplasty (THA) for avascular necrosis (AVN) or inflammatory arthritis (IA) comes with a relatively high risk of aseptic stem loosening, especially in young patients. There are limited long-term data on the survivorship of polished, tapered, cemented stems in this population. We therefore performed a single-center retrospective study investigating the survival of this particular stem type in young patients with AVN or IA.MethodsAll patients aged ≤35 years who had received a THA for AVN or IA operated on by the senior author between 1990 and 2010 at the University Hospitals Leuven were identified. In total, 85 THAs in 62 patients were included. Primary endpoint was revision of the femoral component for aseptic loosening. Secondary endpoints were revision of the acetabular component for aseptic loosening, revision for other reasons, and the presence of radiolucencies around the components.ResultsThe mean follow-up for the entire cohort was 18.0 ± 5.3 years (range 8.0-28.9). Taking revision for aseptic loosening as endpoint, the survival of cemented stems was 100% after 15 years and 95.1% after 20 years. Survival of uncemented cups (91.3%) was significantly better than survival of cemented cups (50.3%) after 20 years of follow-up for aseptic loosening. Taking revision for any reason as endpoint, the survival of THAs with uncemented and cemented cups was 90% and 43.1% at 20 years respectively. Radiolucencies developed in the cement mantles around 11 of the 81 nonrevised stems, mainly in zones 1 and 7.ConclusionIn this cohort of young patients with high-risk profiles for aseptic stem loosening, polished, tapered, cemented stems showed excellent long-term survival rates and they therefore remain a viable alternative to uncemented stem designs.     

Poor results of the cementless total hip arthroplasty with a nonporous coated acetabular component: AcSys Shearer Cup

Background This study followed patients for a minimum of 7 years after primary total hip arthroplasty using cementless acetabular components and evaluated their outcomes. Methods We followed 73 patients (75 hips), who had undergone total hip arthroplasty with cementless nonporous coated acetabular components (3M AcSys Shearer Cup) for a mean of 9.8 years (range 7–13 years). There were 61 women and 12 men with a mean age of 53 years (range 27–69 years) at surgery. The diagnosis was primary osteoarthritis in 9 hips, osteoarthritis secondary to developmental dysplasia in 58 hips, osteonecrosis of the femoral head in 6 hips, and rheumatoid arthritis in 2 hips. Results Three cups were revised because of aseptic loosening, and one cup was revised following removal of the prosthesis due to deep infection. Radiographic loosening was observed in 22 hips at the latest follow-up. The survival rate at 10 years was 94.7% with revision as the endpoint and 72% with radiographic loosening as the endpoint. The Merle d'Aubigné and Postel hip score showed significant improvement postoperatively and was maintained well even in cases showing radiographic loosening. Conclusions The intermediate radiological results with the AcSys Shearer Cup were unsatisfactory because of the high loosening rate, although the revision rate was low. The nonporous outer surface and the poor fixation mechanism between the metal shell and liner may have contributed to the high failure rate. Regular radiological review is recommended when this cup is used because early loosening is often painless.     

人工髋关节置换术后翻修病例分析

目的分析人工髋关节置换术后翻修的原因,评价全髋翻修术的临床效果。方法本组33例34髋。初次关节置换类型:全髋置换21例,双杯髋关节置换1例,人工股骨头置换11例。翻修原因:无菌性松动23例24髋,髋臼位置不良1例1髋,股骨头置换后髋臼磨损5例5髋,感染4例4髋。翻修距初次手术时间:1年以内5髋,1～2年1髋,5～10年18髋,10～13年10髋。翻修假体类型:非骨水泥型假体20髋,混合型假体7髋,骨水泥型假体7髋。结果平均随访3.5年。1例术后半年发生股骨柄松动进行再翻修,其余病例假体保留,优良率为82.4%。结论翻修的最常见原因为无菌性松动,人工股骨头置换时髋臼磨损也是翻修原因之一,对较年轻的股骨颈骨折患者,如行假体置换,最好采用全髋关节置换。翻修术采用非骨水泥型假体较好。     

Long-term results of a hydroxyapatite-coated femoral component in total hip replacement: a 15- to 21-year follow-up study

Between 1986 and 1991 we implanted 331 consecutive Furlong hydroxyapatite-coated femoral components of a total hip replacement in 291 patients. A cemented acetabular prosthesis was used in 217 hips and a hydroxyapatite-coated component in 114. We describe the long-term clinical and radiological survival of the femoral component at a mean follow-up of 17.5 years (15 to 21). Only two patients (0.68%) were lost to follow-up. With revision of the femoral component for any reason as the endpoint, the survival at a mean of 17 years was 97.4% (95% confidence interval 94.1 to 99.5), and with revision for aseptic loosening as the endpoint it was 100%. The survival at a maximum of 21 years with revision of the femoral component for any reason as the endpoint was 97.4% (95% confidence interval 81.0 or 99.5). These results compare favourably with the best long-term results of cemented or uncemented femoral components used in total hip replacement.     

Use of constrained acetabular components for hip instability: an average 10-year follow-up study

The short-term efficacy of using constrained acetabular components for hip instability in the total hip arthroplasty construct has been documented. However, long-term concerns including late dislocation, loosening of components, and osteolysis have not been addressed. The authors evaluated, at an average 10.3-year follow-up, 101 tripolar constrained components (Stryker Howmedica Osteonics) used in the total hip arthroplasty construct. At final follow-up, 6 hips had dislocated or had failure of the constrained component, 5 of which were revised. In addition, 4 hips were revised for aseptic loosening of the acetabular component, 4 hips were revised for aseptic femoral loosening, and 1 hip was revised for acetabular osteolysis. Considering the complexity of the cases, this component has provided durable fixation and hip stability at this intermediate-term follow-up.