Prospective study of porous-coated anatomic total hip arthroplasty

Seventy-five uncemented porous-coated total hip prostheses were implanted in 64 patients. The results were reviewed after a mean follow-up period of 47 months (range, 40-64 months). The mean preoperative rating was fair, and the mean postoperative rating was excellent. There were six dislocations. Ten patients had mild thigh pain at one year; by two years, the pain had resolved in six patients. Neither moderate nor severe limp nor significant loosening of beads was observed. Only one patient had progressive radiolucent lines. The high rate of dislocation may be related to a compromise of acetabular position to obtain bony fixation in acetabula early in the series. The clinical results were encouraging.     

Results of porous-coated anatomic and duracon total knee arthroplasty

The Duracon total knee replacement and its forerunner the Porous-Coated Anatomic (PCA) knee system have been associated with good results. This study reviews a series of 181 knee replacements performed with these systems by seven general orthopedic surgeons with follow-up to a mean of 6.7 years. The mean Knee Society knee and function scores were 72 and 68. The mean Western Ontario and MacMaster Universities Osteoarthritis Index score was 76, and the mean 12-Item Short-Form Health Survey result was 55. A mean flexion of 104 degrees was recorded, and 93.8% of patients rated their satisfaction as good to excellent. Fifty-five percent of patients had minor radiographic lucencies-these were of questionable clinical significance. Seven patients required revision. These knee systems used in a relatively low-volume general unit provide consistent results comparable with those from larger arthroplasty units.     

Uncemented porous-coated anatomic total hip replacement in Chinese patients

Summary Primary uncemented Porous-Coated Anatomic total hip replacement was carried out in 72 hips in 62 Chinese patients. Their average age was 50 years and the average follow up was 3 1/2 years. The most common diagnosis was avascular necrosis. The average preoperative Harris score of 36.3 points improved to 83.2 at the last follow up. The pain score improved from 13.7 out of 44 to an average of 42. Seven of 8 hips with thigh pain had an inadequately fitting stem which had subsided. Only one cup was revised because of a technical error and one femoral component for loosening. Uncemented Porous-Coated Anatomic total hip replacement gave good early results in Chinese patients.

---

Résumé Soixante-douze hanches chez 62 patients chinois ont été remplacés par des prothèses totale de hanche PCA non cimentées. L'âge moyen des patients était de 50 ans. Le diagnostic le plus fréquent était la nécrose avasculaire. Le suivi moyen était de 3 ans 1/2. Le score pré-opératoire selon Harris était de 36.3 et s'était amélioré à 83.2 lors du dernier contrôle. L'amélioration de la douleur était très bonne. Le score pré-opératoire moyen de la douleur qui était en moyenne de 13,7 pour 44 patients, est passé à une moyenne de 42 lors du dernier suivi. Sept sur 8 hanches avec douleur de cuisse ont eu une pose inadéquate de la tige de prothèse qui montra un certain degré d'enfoncement. La pose inadéquate et l'enfoncement de la tige semblèrent être les causes essentielles contribuant à des douleurs de cuisse. Une planification pré-opératoire signeuse est essentielle pour obtenir une bonne mise en place de la tige. Une seule cupule a été révisée en raison d'une erreur technique et une tige fut reprise en raison du descellement. La prothèse de hanche PCA sans ciment a donné de bons résultats précoces chez les patients chinois.

     

Evaluation of the learning curve associated with uncemented primary porous-coated anatomic total hip arthroplasty.

The results of the first and second groups of 50 consecutive primary, uncemented porous-coated anatomic arthroplasties were analyzed to evaluate the learning curve associated with the procedure. Femoral fit, acetabular cup angle, femoral fracture rate, minimum two-year clinical hip ratings, and clinical symptoms were compared between the two groups. Significant improvement in achieving better femoral canal filling with the prosthesis and lower acetabular cup angle placements was documented in the second 50 cases. Although a definite learning curve in mastering the technique of uncemented total hip arthroplasty was observed, thigh pain rate and clinical ratings were not improved after two years.     

Noncemented total knee arthroplasty

Extensive animal experimentation has proven porous titanium fiber composite to be an effective interface for direct attachment of prosthetic devices via bone ingrowth. Titanium has demonstrated excellent biocompatibility in long-term primate experiments. Utilizing this technology, a cementless total knee system has been developed. A pilot study of 34 knees demonstrated the feasibility of anchoring the tibial component without cement. A totally cementless unconstrained total knee replacement was designed with porous titanium fiber composite interfaces. Retention of the posterior cruciate ligament was an essential part of the design. A large range of sizes was chosen to allow precise fitting of individual patients with distribution of load over the maximum surface available. Early clinical results have been very encouraging. Patients have achieved excellent pain relief, rapid return of function, and range of motion exceeding previous designs.     

Long-term results of the cementless porous-coated anatomic total hip prosthesis

Between January 1984 and January 1986, 131 porous-coated anatomic total hip replacements were performed in 119 consecutive patients. Of these, 100 patients (110 hips) who were alive at a minimum of 18 years after replacement were included in the study. The mean age of the patients at surgery was 48.4 years and that of surviving patients at the latest follow-up was 67.8 years. The mean duration of the clinical and radiological follow-up was 19.4 years (18 to 20). The mean Harris hip score initially improved from 55 points before to 95 points at two years after operation, but subsequently decreased to 91 points after six years, 87 points after 11.2 years, and 85 points after 19.4 years. At the final follow-up, 23 hips (18%) of the entire cohort and 21% of survivors had undergone revision because of loosening or osteolysis of the acetabular component and eight hips (6%) of the entire cohort and 7% of survivors for loosening or osteolysis of the femoral component. Only four femoral components (4%) were revised for isolated aseptic loosening without osteolysis and two (2%) for recurrent dislocation. On the basis of these long-term results, the porous-coated anatomic femoral component survived for a minimum of 18 years after operation while the acetabular component was less durable. The findings identify the principles of uncemented joint replacement which can be applied to current practice.     

Osteointegration of bone graft in porous-coated total hip arthroplasty

Since 1983, 19 patients have had bone grafting of acetabular defects in association with a porous-coated acetabular prosthesis. The defects were defined by anatomic location to assess the rates of incorporation at different sites. The average time to incorporation was 12 months, judged by trabecular continuity. Superolateral grafts showed a greater degree of rarefaction than medial grafts. Nonprogressive migration of the graft was seen in only two cases before full incorporation of the graft. Developing lucency was seen up to 2 mm at the prosthesis-graft interface but not at the graft-ilium level. Roentgenograms suggested that integration of porous acetabular prostheses into bone may improve results of reconstructive surgery of the acetabulum.     

Revision of failed total hip arthroplasties with uncemented porous-coated anatomic components

This series represents a relatively short follow-up study of patients who were treated with cementless revisions for failed previous arthroplasties. Many of these cases required extensive bone grafting to the acetabulum and often to the femur. Despite extensive bone grafting, there were no infections. There has been but a single graft resorption after a hemiarthroplasty conversion for recurrent dislocations. To date, all other grafts have remained intact and have shown signs of union. Even though the acetabular components were not anchored in place by adjuvant fixation devices such as screws, migration of the acetabular component has not been a problem. All other components have remained stable, and the supporting grafts appear to have united successfully. Femoral revision has been more technically demanding because the largest stem possible should be placed within the femur to prevent subsidence and provide good stabilization in the proximal metaphyseal area. These short-term results compared favorably with similar series of cemented revisions. Patient selection is important and there are definite candidates for cemented femoral components, particularly with first-time revisions in elderly patients. If there is massive osteolysis in the femur, cemented revision is probably not indicated. Long stems should not be used unless necessary. Cortical defects at the tip of the standard stem obviously would require bypassing the stress riser with a longer stem. If, however, the cortex is intact in this region and stability can be achieved, revision should be carried out with a relatively short stem. Techniques for cementless revision are demanding, but with meticulous attention to detail and technical perfection, the method has a most encouraging prognosis. Longer follow-up evaluations will be necessary to make an accurate evaluation of graft incorporation, but short-term results are encouraging to both surgeons and patients.     

Primary total hip arthroplasty with a proximally porous-coated femoral stem

BACKGROUND: The use of cementless, proximally porous-coated femoral stems for total hip arthroplasty has increased in popularity. The purpose of the present report was to examine the five to ten-year results associated with the use of a so-called second-generation circumferentially proximally porous-coated titanium-alloy stem. METHODS: Between 1991 and 1994, 123 Harris-Galante Multilock femoral stems were implanted in 101 patients. The average age of the patients at the time of surgery was 53.8 years. The patients were followed prospectively and were reevaluated at a minimum of five years postoperatively. No patient was lost to follow-up. Twenty-five patients (thirty hips) were interviewed by telephone, and four patients (five hips) died during the study period because of problems that were unrelated to the operation. The remaining seventy-two patients (eighty-eight hips) had a minimum of five years of clinical and radiographic follow-up. RESULTS: The average duration of follow-up was seventy-eight months. At the time of the most recent follow-up, the average Harris Hip Score was 95 points. Eighty-seven (99%) of eighty-eight stems were biologically stable, with eighty-four hips (95%) having osseous ingrowth and three hips (3%) having stable fibrous fixation. One stem was revised because of loosening. Thirty-three hips (38%) had minimal proximal osteolysis, and no hip had diaphyseal osteolysis. Seventy-two hips (82%) had some degree of stress-shielding in the proximal metaphysis, but only two hips had cortical resorption. None of these patients required additional surgery, and all reported a satisfactory outcome. CONCLUSIONS: Given the young age and high activity level of these patients, this stem fared well: the levels of patient function and satisfaction were high, the rates of loosening and revision were very low, and distal osteolysis did not occur. Osseous fixation occurred reliably. Proximal stress-shielding was seen but did not seem to be clinically important.     

Bilateral total hip arthroplasty comparing hydroxyapatite coating to porous-coated fixation

Fifteen patients had bilateral hip replacement with a porous-coated hip replacement in one hip and in the contralateral hip the same design, which had adjunctive hydroxyapatite coating on the porous coating. These patients were followed for an average of 6.5 years (range, 5–7.9 years). There was no difference in the clinical Harris Hip Scores between the two hips in these patients. The radiographic measurements did show improved bone remodeling in hips with adjunctive hydroxyapatite coating as measured by proximal cancellous hypertrophy and evidence of a buttress sign. The fixation of stems with hydroxyapatite coating showed fewer radiolucent lines (P = .013). The improved bone remodeling, which we had previously reported, has been maintained in these hips at intermediate-term follow-up and the fixation of the hydroxyapatite-coated stems is also now better. The results in these patients with bilateral hips, which allows complete control of the bone type, immunology, weight, activity, and age of the patient, suggests that the use of hydroxyapatite coating does provide improved fixation and the possibility of improved durability.     

Clinical consequences of stress shielding after porous-coated total hip arthroplasty

From a series of 223 extensively porous-coated total hip arthroplasties, 208 hips had radiographic followup at a minimum of 2 years, which could be evaluated for radiographic evidence of stress-shielding. These patients had a mean 13.9-year followup (range, 2-18 years). We compared the outcome of 48 total hip arthroplasties that had radiographically evident stress-shielding with 160 total hip arthroplasties that did not have radiographically visible stress-shielding or that had less severe stress-shielding. Stress-shielding was more likely in females, patients with a low cortical index, and patients with larger stems. At the most recent followup, patients with stress-shielding had a lower mean walking score than patients without stress-shielding and less osteolysis. No patients with stress-shielding had femoral loosening, implant fractures, or loss of porous coating. The revision rate was 13% (six hips) among hips with stress-shielding and 21% (33 hips) among hips without stress-shielding. Fifteen-year survivorship was 93% among hips with stress-shielding and 77% among hips without stress-shielding. Stress-shielding did not produce adverse consequences in these extensively porous-coated total hip arthroplasties.     

Primary total hip arthroplasty with a cementless porous-coated anatomic total hip prosthesis: 10- to 12-year results of prospective and consecutive series.

We performed a prospective study in 108 consecutive patients (116 hips) who were followed for a minimum of 10 years (10-12 years) after primary total hip arthroplasty using an uncemented porous-coated anatomic (PCA) hip prosthesis. The average age of the patients at operation was 48.4 years (range, 19-85 years), and the diagnosis was avascular necrosis of the femoral head in 46 hips, neglected femoral neck fracture in 27, osteoarthrosis secondary to childhood pyogenic arthritis in 24, childhood tuberculous arthritis in 5, and miscellaneous in 14. The average preoperative Harris Hip Score was 55 points, which improved to 87 points at 11 years. Seventy-five hips (65%) were excellent, 11 (9%) were good, and 30 (39%) were poor. The overall rate of revision was 15% (17 of 116 hips). The rate of revision of the femoral component was 11% (13 of 116 hips), and the rate of revision of the acetabular component was 15% (17 of 116 hips). The prevalence of thigh pain was 28% at 11 years. The increase in the incidence of aseptic loosening of the femoral component was found to explain the high incidence of severe thigh pain at 11 years' follow-up. At 11 years, there was femoral osteolysis in 69 hips (59%) and acetabular osteolysis in 65 hips (56%). At 6 years, 20 hips (17%) showed definite wear of the polyethylene liner. At 11 years, 81 hips (70%) showed definite wear of the polyethylene liner. Because the complication rate of the PCA hip prosthesis with respect to loosening, osteolysis, and excessive wear in the polyethylene liner is high, we abandoned the use of this implant.     

Porous coated anatomic non-cemented total hip arthroplasty.

Between November 1984 and December 1989, 318 non-cemented Porous Coated Anatomic (PCA; How-medica, Rutherford, New Jersey) total hip replacements were performed by the authors. A follow-up of 1 to 6 years was allowed. The average age was 53.1 years (from 17 to 71 years). The distribution of right-to-left was approximately equal. There were 192 hip replacements for primary and post-traumatic osteo-arthritis, 42 for rheumatoid arthritis, 40 for avascular necrosis, 29 for congenital dislocation or hip dysplasia with secondary osteo-arthritis, 6 for Perthes disease, 5 for previous sepsis, 2 of whom had had a Girdlestone procedure, 2 for revision of a painful cup arthroplasty, and 1 for conversion of a previously fused hip. All patients were evaluated on a one hundred point Harrington Arthritis Research Centre Scale. Points were awarded for pain (0-35), function (0-35), motion (0-10), deformity (0-10) and gait (0-10). Pre-operative total scores averaged 45.5 (9-71) and postoperative scores averaged 83.9 (55-98). The overall results were excellent 20.5% (90-100), good 59.8% (80-90), fair 16.4% (70-80), and poor 3.3%. Postoperative radiographs were evaluated using zonal analysis. There was no deterioration on the radiographs after two years.     

Mechanical stability of porous-coated acetabular components in total hip arthroplasty.

Five different porous-coated acetabular prosthetic configurations underwent in vitro testing to assess mechanical stability in embalmed cadaver hemipelves: Harris Galante II cup with three cancellous screws, Biomet Universal cup, Whiteside cup with peripheral pegs, Whiteside cup with two cancellous screws, and plain Whiteside cup. Following implantation in a neutral frame, cyclic load testing was done using 33 specimens at 100-kg load for 100,000 cycles using an MTS machine (MTS Systems Corp., Minneapolis, MN). Subsequently, static load-to-failure testing was done in all specimens. Subsidence and micromovement were determined for each specimen using linear variable differential transformers. With cyclic testing, overall cup subsidence revealed a significant increase, from 500 to 100,000 cycles. Overall cup micromovement revealed a significant decrease, and all cup groups demonstrated less than 125 microns (.125 mm) of average mean micromotion at the completion of cyclic testing. The best cup configuration was a 1-mm, oversized, press-fit cup using two 6.5 cancellous screws for additional fixation, which revealed an average mean of 60 microns (.06 mm) of micromovement. Static load testing revealed unacceptable micromovement over 150 microns (.150 mm) in most cups with 300-kg loads.     

广泛微孔涂层非骨水泥假体在股骨翻修的应用

目的报告采用广泛微孔涂层非骨水泥股骨假体对失败的骨水泥固定股骨假体翻修的近期效果。方法1998年至2003年,对20例骨水泥固定型人工髋关节置换后无菌性松动的股骨假体采用广泛微孔涂层假体进行翻修。翻修前使用国产假体18例,进口假体2例;全髋关节置换14例,人工股骨头置换6例。所有假体均为骨水泥固定,早期骨水泥技术固定18例,第二代骨水泥技术固定2例。原始疾病为股骨头无菌性坏死14例,股骨颈骨折6例。从初次关节置换到翻修手术的时间最短5年,最长17年,平均11.5年。其中4例患者为再次翻修。根据Paprosky分型,Ⅰ型3髋,Ⅱ型6髋,ⅢA型11髋。翻修假体,AML(DePuy)5髋,Solution(DePuy)7髋,Full-coated(Zimmer)6髋,Perfecta延长柄(WrightMed)2髋。翻修时患者平均年龄64岁(41～77岁),术后平均随访时间40个月(18～60个月)。结果Harris评分从术前平均34分改善为术后平均85分。根据Engh骨长入分级标准评定,术后X线表现骨性固定17例,稳定性纤维固定3例。无一例因松动需要再翻修的病例,骨皮质密度和厚度均明显增加。结论广泛微孔涂层假体在股骨干骺端和股骨髓腔同时存在缺损时,可以在相对正常的股骨远端髓腔获得轴向及抗旋转初始稳定,为骨长入和生物学固定创造条件。     

High placement of porous-coated acetabular components in complex total hip arthroplasty

The authors retrospectively evaluated the results of 56 hips in 51 patients with an acetabular deficiency who had a total hip arthroplasty with a porous-coated, cementless acetabular component implanted at a high hip center. Forty-nine cases were revisions and seven were primary operations. The mean height of the hip center was 43 mm above the interteardrop line compared to 14 mm for the anatomic center, threefold higher than normal. In contrast, the mean horizontal locus was reduced compared to normal (33 vs 37 mm for the anatomic center). Sixteen acetabular components were small (46–48 mm o.d.) and eight were miniature (40–44 mm o.d.). Despite superior placement of the acetabular component, 32 limbs were lengthened by the procedure. The mean preoperative Harris hip score was 51 (range, 28–93). At a mean follow-up period of 40 months (range, 24–64 months), the mean Harris hip score was 86 (range, 36–100). In 23 hips no radiolucent lines were present at the interface of the bone to the porous mesh, and 33 hips had a thin (0.5 mm), nonprogressive radiolucent line in one or more zones. No acetabular component had migrated and no problems occurred with the screws. Four hips (3 revisions and 1 primary operation) had a complete radiolucent line on one oblique view of the acetabulum. No acetabular component has been revised for loosening. These short-term data suggest that under circumstances in which the acetabulum cannot be reconstructed at the anatomic level without a major structural bone-graft, superior placement of the porous-coated acetabular component against viable host-bone at a higher level than normal may be an acceptable alternative.     

Total hip arthroplasty with the porous-coated anatomic hip prosthesis: results at 11 to 18 years

The authors had previously reported good results with apparent fixation of a series of porous-coated anatomic hips at 2 to 4 years. In a larger series of 133 hips with porous-coated anatomic uncemented components, 91 hips in 82 patients were available for a follow-up of 11 years or greater. Although 3.1% of acetabular cups had migrated or had been revised at 2 to 4 years; at 11 to 18 years, there was 37% lysis, 21.7% migration, and 32.3% revision. For the femur at 2 to 4 years, there was 3.1% migration and 1.5% revision. At 11 to 18 years, there was 27.2% lysis (proximal only), 6.6% migration, and 3.2% revision. Survival analysis for migration or revision for the femoral was 94%, and for the acetabular component, 63%, deteriorating markedly after 10 years.     

Clinical and roentgenographic evaluation of noncemented porous-coated anatomic medullary locking (AML) and porous-coated anatomic (PCA) total hip arthroplasties

Eighty-four primary noncemented porous-coated total hip arthroplasties (THAs) in 78 patients were reviewed clinically and roentgenographically at an average follow-up period of 37 months. The average patient age was 51.9 years. Sixty-four Anatomic Medullary Locking (AML) devices were placed in 58 patients, and 20 Porous-Coated Anatomic (PCA) devices were placed in 20 patients. The AML devices had been in situ an average of 36 months (range, 24-49 months), and the PCA devices had been in situ an average of 40 months (range, 29-51 months). The average patient ages were 52.7 and 49.2 years for AML and PCA patients, respectively. The AML devices included three that were fully coated, 59 that were five-eighths coated, and two that were one-third coated. The average preoperative Harris hip score was 38.2 for the AML devices and 33.2 for the PCA devices. The average postoperative Harris hip score was 80.7 for the AML devices and 83.8 for the PCA devices. Pain related to the implant was present in 30% of the AML devices and 30% of the PCA devices. Roentgenographically, no component demonstrated complete radiolucency, and all components demonstrated roentgenographic evidence of bone ingrowth. Roentgenographic changes with time noted for both the AML and PCA devices included: neck roundoff, neck osteolysis, neck corticocancellization, endosteal bone bridging, and distal hypertrophy. On roentgenographic zonal analysis, radiolucency greater than 1 mm was observed most frequently in the most proximal lateral zone and distal tip of the femoral component. The current series of cases, although clinically acceptable, does not support the current widespread enthusiasm for primary noncemented AML and PCA total hip systems. Cemented THA appears to produce superior clinical results, particularly when contemporary cementing techniques are employed.     

Middle-term results of anatomic medullary locking total hip arthroplasty

We report the results of cementless, anatomic, medullary locking hip prosthesis application in our first consecutive series. We used the so-called Asian size of prosthesis with proportionally smaller stem sizes in both diameter and length. Forty-seven stems and sockets were analyzed with a mean follow-up of 69 months. The mean Merle d’Aubigné hip scores were 8 points preoperatively and 16 points at the final follow-up. Radiologically, the stems showed excellent stability without loosening. Stress shielding around the stems did occur in most cases but did not progress. Preoperative bone quality influenced the extent of stress shielding evaluated at the final follow-up: higher stress shielding was noted in poorer quality bones at the time of operation. There were problems with the sockets. The shallow socket and impingement at the protruded rim seemed to cause a high incidence of dislocation (13%). Massive polyethylene wear occurred in 5 sockets. These sockets were 48 and 46 mm in diameter with 26 mm heads. In conclusion, the stems of the anatomic medullary locking hip prostheses used in Japan showed satisfactory stability even in poor quality bones, but there were problems with the polyethylene liners. Our solution was to use larger sockets with 22 mm heads.     

The porous-coated anatomic total hip prosthesis: 11- to 13-year results

Of 137 consecutive primary porous-coated anatomic (PCA) arthroplasties performed, complete data was available on 107 hips in 93 patients at an average of 12.4 years (range, 11-13 years). The average Harris Hip Score improved from 44 to 85 at final follow-up, with 78% good or excellent result. Thirteen percent (14 of 107) of acetabular components and 4 porous ingrowth stems were deemed failures. Osteolytic lesions were seen in 7.5% (8 of 107) of acetabular components. Survivorship of the PCA prosthesis as a whole was 83% at 12.4 years. This first-generation femoral stem performed well, with only 4 failures, all of which occurred in patients with avascular necrosis in which unrecognized pathologic changes in the proximal femur may have inhibited bone ingrowth. The majority of the failures can be attributed to aseptic loosening of the acetabular component.