Uncemented Total Hip Replacement

During the last 20 years almost 3000 uncemented total hip replacements have been used in the treatment of osteoarthritis and rheumatoid arthritis. The development of an axially located prosthesis is outlined, and the causes of failure indicated. Uncemented prostheses have the advantage of a relatively low mortality and morbidity and the rate of infection in particular is low. Interface pain, with or without frank prosthetic loosening, is the commonest cause of failure, but revisional surgery is relatively easy, and usually successful. Loss of function without significant pain may occur after many years from distal migration of the femoral component. The development of an uncemented metal-on-plastic joint has produced better short-term results than the metal-on-metal articulation, probably because of its lower frictional coefficient and the use of a wider range of pelvic and femoral components.

[How to avoid loosening of the shaft of an artificial hip (author's transl)]

This is the description of a technique to prevent the loosening of the stem of the artificial hip by the help of rodtechs, which are implanted in the cement and in the corticalis. This can be done without a major delay of the operation-proceeding.

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.

Charnley low friction arthroplasty in young patients with osteoarthritis. A 12- to 24-year clinical and radiographic followup study of 84 cases

The long term outcome of 84 Charnley low friction arthroplasties performed between January 1973 and December 1984 on 69 patients (84 hips) with osteoarthritis was assessed. The patients were 55 years old or younger (mean, 46 years) at the time of surgery. The probability of survival was 89.8% (range, 85.9%-93.7%) after 10 years with 69 hips at risk and 73.3% (range, 65.5%-81.1%) after 18 years with 33.5 hips at risk. Of the 84 hips in the study, 24 (28.6%) failed. Of the hips that survived, clinical results were good and excellent with Charnley scores of four or more for pain and function in all hips. Of the hips that survived, 93.3% achieved good or excellent results for movement.

Vastus-Psoas release for acetabular exposure in revision hip surgery

A technique is presented for wide exposure of the acetabulum for revision total hip arthroplasty surgery in the presence of a solidly fixed, modular, or monoblock femoral component without the need for trochanteric osteotomy. The technique involves release of the proximal portion of the vastus lateralis, vastus intermedius, and vastus medialis muscles and the iliopsoas tendon form the femur and placement of the femoral head/neck posterior to the acetabulum. The exposure afforded by this release usually precludes the need for trochanteric osteotomy and/or removal of a well-fixed femoral component in revision surgery that is being done for isolated loosening of acetabular components, thereby decreasing operative time, morbidity, and the risks of complication of trochanteric osteotomy.

Stability of proximal femoral grafts in canine hip arthroplasty

In a canine model, the fixation stability of a prosthesis and proximal bone graft composite were measured relative to the distal femur. One group had the prosthesis graft composite cemented into the distal femur. The second group had the prosthesis graft composite press fit into the distal femur for biologic ingrowth. Displacements of the proximal femoral grafts relative to the host bone in each group were measured after ex vivo (acute with graft) implantation and 4 months after implantation. A third group with no osteotomy (acute intact) simulated perfect graft to host bone union. Relative displacements representing 6 degrees freedom (translation and rotation) were calculated from the displacement values measured by 9 eddy current transducers. Measurements of displacement were used to test the hypothesis that distal press fit fixation equals distal cement fixation at 4 months after implantation. In all cases the measured translations and rotations of the graft to implant construct were small and of a magnitude that should encourage bone ingrowth (< 0.05 mm and < 0.1 degree, respectively). The stability of the press fit group at 4 months was not significantly different from the cemented group in axial and transverse displacement during axial and transverse loading, respectively. There was no difference in stabilities at 4 months between distal press fit and cemented fixation in hip replacements requiring a proximal femoral graft.

Rationale of a flexible press fit cup in total hip replacement. 5-year followup in 280 procedures

A consecutive series of 280 total hip replacements in 261 patients using the Press Fit Cup with a minimum followup of 5 years is presented. The Press Fit Cup is a nonmodular acetabular component with a porous coating made of titanium fibers. It has one peg and is 1.5 mm oversized with biradial eccentricity. It has a flattened pole area, requires no screw fixation, and partially preserves elasticity. The mean age was 71 years for women, 70 years for men. Forty-seven patients (49 hips) died before the 5-year review, and five patients were unable to return for the followup because of physical infirmity. Two hundred eighteen patients (226 hips) were available for the clinical 5-year followup, and 208 patients (213 hips) were available for the radiographic followup. No intraoperative fracture of the acetabulum occurred; four hips dislocated; 94% clinically were rated as excellent or good. One hip in a patient with rheumatoid arthritis had to be revised for aseptic loosening of the cup and nine femoral stems had to be revised. No migration of the cup could be measured. There was no osteolysis seen around the cup. In six cases a radiolucent line was seen in Zone 1, and in eight hips in Zone 3. There was one hip with a continuous radiolucent line which was considered radiographically loose.

The influence of patient-related factors and the position of the acetabular component on the rate of dislocation after total hip replacement

The senior one of us performed 438 primary and 181 revision total hip arthroplasties with use of so-called modern prostheses between July 1983 and January 1994. Fifty-three patients, who had had forty-seven primary procedures and twelve revisions, either died or were lost to follow-up less than two years after the operation and were excluded from the study. The results for the remaining 446 patients (391 primary procedures and 169 revisions) were analyzed to determine the influence of patient-related and operative factors and the position of the acetabular component on the rate of dislocation. Dislocation occurred after thirty-two (6 per cent) of the 560 total hip arthroplasties: seventeen (4 per cent) of the 391 primary procedures and fifteen (9 per cent) of the 169 revisions (p = 0.046). There was no relationship between the variables of age, gender, obesity, or preoperative diagnosis and dislocation after either primary or revision arthroplasty. Seven (23 per cent) of the thirty arthroplasties in the patients who had a history of excessive intake of alcoholic beverages (more than 2.1 liters [seventy-two ounces] of beer or more than 0.2 liter [six ounces] of other alcoholic beverages a day) were followed by a dislocation compared with twenty-five (5 per cent) of the 530 arthroplasties in the patients who did not have such a history. This difference was significant for the patients who had had a revision arthroplasty (p = 0.00005), but with the numbers available we could not detect a difference for those who had had a primary arthroplasty (p = 0.264). Radiographic analysis was performed for thirty-two hips that had dislocated and thirty-two that had not (seventeen primary procedures and fifteen revisions in each group), matched exactly according to the type of prosthesis and the operative approach (but not age). We detected no association between either the version or the abduction angle of the acetabular component (within the range of 39 to 56 degrees for the primary prostheses and 38 to 57 degrees for the revision prostheses) and the risk of dislocation. Thirty of the thirty-two hips in each group had an abduction angle of the acetabular component that was in the so-called safe range of 30 to 50 degrees.

Bone-graft augmentation for acetabular deficiencies in total hip arthroplasty. Results of long-term follow-up evaluation

The results of 102 consecutive primary and revision total hip arthroplasties performed with bone-grafting for acetabular bone deficiencies were reviewed at an average of 10.2 years (range, 4-18.6) after surgery. Ninety-one percent had structural bone defects and 57% had underlying developmental dysplasia of the hip. Overall acetabular revision rates for aseptic loosening were 8% at 5 years and 26% at 10 years. In addition, in the patients with developmental dysplasia who had primary hip arthroplasties, acetabular revision rates for aseptic loosening were 3 and 18% at 5 and 10 years, respectively. Ninety-six percent of all uninfected grafts incorporated. Bulk grafts fared better than particulate grafts. No difference in failure rate was noted between primary and revision hip arthroplasty, type of deficiency, or amount of graft coverage. Although early results are encouraging, acetabular failure increased significantly with longer follow-up evaluation; however, graft incorporation was successful and facilitated subsequent revision surgery.

Total hip arthroplasty in neglected congenital dislocation of the hip

Between 1984 and 1995, 74 total hip replacements were performed in 64 adult patients who had painful untreated congenital dislocation of the hip. The arthroplasty was performed in the position of the true acetabulum in all patients who had either high or low congenital dislocations of the hip. The femoral head was positioned in the true acetabulum after either osteotomy of the greater trochanter or shortening of the femur, or progressively using external fixation. Information was available on all patients with a followup of 1 to 11 years (mean, 7.2 years). Of the 74 replaced hips, 70 showed marked improvement concerning pain, gait, and mobility, according to the Merle D'Aubigne and Postel scale. Four hips were revised with satisfactory results. The reason for revision was infection in one case and loosening of the plastic cup in three cases. Shortening of the femur by removing a segment of bone below the level of the lesser trochanter followed by osteosynthesis without osteotomy of the greater trochanter was found to be the best method for treating bilateral and several unilateral high congenital dislocation of the hip.

Uncemented total arthroplasty in old quiescent infection of the hip

We reviewed the outcomes of 24 cases (24 patients) of uncemented total hip arthroplasty done to treat secondary osteoarthritis due to quiescent previous infection. There were 16 men and eight women aged from 24 to 78 years (mean, 50 yr). Eight patients had proven or probable tuberculous infection and the other 16 patients had a past history of septic hip. The patients were followed for between 2.5 and 7 years (mean, 4.5 yr). According to the Harris hip rating system, 18 of the patients had excellent or good results. Three patients had a preoperative erythrocyte sedimentation rate of 40 mm/h or higher and had a positive bacterial culture. Two of these patients developed reinfection. The other 21 patients had a preoperative erythrocyte sedimentation rate less than 40 mm/h and no reinfection postoperatively. There were five complications other than infection: dislocation with ipsilateral femoral shaft fracture, intraoperative femoral fracture, cup loosening, periprosthetic osteolysis, and nonunion of the greater trochanter. Uncemented total arthroplasty for old quiescent infection of the hip should be considered if the preoperative erythrocyte sedimentation rate is normal and a course of prophylactic antituberculous therapy is given in patients with an old tuberculous hip.

Early radiological observations may predict the long-term survival of femoral hip prostheses

We reviewed a consecutive series of 527 uninfected hip replacements in patients resident in the UK which had been implanted from 1981 to 1993. All had the same basic design of femoral prosthesis, but four fixation techniques had been used: two press-fit, one HA-coated and one cemented. Review and radiography were planned prospectively. For assessment the components were retrospectively placed into two groups: those which had failed from two years onwards by aseptic femoral loosening and those in which the femoral component had survived without revision or recommendation for revision. All available radiographs in both groups were measured to determine vertical migration and examined by two observers to agree the presence of radiolucent lines (RLLs), lytic lesions, resorption of the neck, proximal osteopenia and distal intramedullary and distal subperiosteal formation of new bone. We then related the presence or absence of these features and the rate of migration at two years to the outcome with regard to aseptic loosening and determined the predictive value of each of these variables. Migration of > or = 2 mm at two years, the presence of an RLL of 2 mm occupying one-third of any one zone, and subperiosteal formation of new bone at the tip of the stem were predictors of aseptic loosening after two years. There were too few lytic lesions to assess at two years, but at five years a lytic lesion > or = 2 mm also predicted failure. We discuss the use of these variables as predictors of femoral aseptic loosening for groups of hips and for individual hips. We conclude that if a group of about 50 total hip replacements, perhaps with a new design of femoral stem, were studied in this way at two years, a mean migration of < 0.4 mm and an incidence of < 10% of RLLs of 2 mm in any one zone would predict 95% survival at ten years. For an individual prosthesis, migration of < 2 mm and the absence of an RLL of < or = 2 mm at two years predict a 6% chance of revision over approximately ten years. If either 2 mm of migration or an RLL of 2 mm is present, the chances of revision rise to 27%, and if both radiological signs are present they are 50%. If at five years a lytic lesion has developed, whatever the situation at two years, there is approximately a 50% chance of failure in the following five years. Our findings suggest that replacements using a limited number of any new design of femoral prosthesis should be screened radiologically at two years before they are generally introduced. We also suggest that radiographs of individual patients at two years and perhaps at five years should be studied to help to decide whether or not the patient should remain under close review or be discharged from specialist follow-up.

Periprosthetic bone remodelling after cementless total hip replacement. A prospective comparison of two different implant designs

In a prospective study of 14 patients undergoing total hip replacement we have used dual-energy X-ray absorptiometry (DEXA) to investigate remodelling of the bone around two different designs of cementless femoral prosthesis. The bone mineral density (BMD) was measured at 12-weekly intervals for a year. Eight patients (group A) had a stiff, collarless implant and six (group B) a flexible isoelastic implant. Patients in group A showed a decrease in BMD from 14 weeks after operation. By 12 months, the mean loss in BMD was 27%, both medially and laterally to the proximal part of the implant. Those in group B showed an overall increase in BMD which reached a mean of 12.6% on the lateral side of the distal portion of the implant. Our results support the current concepts of the effects of stem stiffness and flexibility on periprosthetic remodelling.

Effect of a stemless femoral implant for total hip arthroplasty on the bone mineral density of the proximal femur. A prospective longitudinal study

After total hip arthroplasty with a medullary stem, significant loss of bone mineral density (BMD) has been demonstrated in the proximal-medial femoral cortex. In an attempt to prevent bone loss, a stemless femoral component was designed. Owing to promising experimental results, a prospective clinical trial was undertaken in a limited group of patients, all below the age of 50. Yearly BMD measurements were carried out in the vicinity of the implant and compared with the BMD values obtained in the immediate perioperative period and with the values on the unaffected side. The follow-up period in this study was 4 to 6 years, involving 32 hips in 31 patients. Maintenance of BMD in the operated femur was demonstrated. A statistically significant increase in the BMD of the proximal medial femoral cortex was observed in those patients who had low initial values. In active patients with a life expectancy greater than 30 years, preservation of the proximal bone stock after total hip arthroplasty appears beneficial, as these patients are most likely to need revision surgery, which is more difficult if significant bone loss has occurred. The data further reinforce the crucial role of mechanical stress in BMD maintenance.

Results and complications of total hip arthroplasties in patients with sickle-cell hemoglobinopathies. Role of cementless components

The complications and results of 16 primary and revision total hip arthroplasties in patients with sickle-cell hemoglobinopathies were evaluated. One patient died from renal failure at 1 year, leaving 15 hips in 10 patients for review at a mean follow-up period of 6 years (range, 2-12 years). There were 7 cementless primary total hip arthroplasties and 8 revision arthroplasties, 6 of which were uncemented. Patients were evaluated clinically using a standard hip rating system and radiographically using accepted criteria. There were no early or late deep infections; however, 7 of 8 primary arthroplasties and 5 of 8 revisions had one or more early complications. No cementless component demonstrated loosening; however, there was asymptomatic polyethylene wear in 2 primary arthroplasties, treated with grafting and liner exchange, and femoral osteolysis was present in 4 of 13 cementless arthroplasties, one of which was revised to permit extensive grafting. Of the original 15 arthroplasties performed by the senior author, 5 required some type of reoperation during the study. At most recent follow-up evaluation, no component in the study was radiographically loose. In the hips that did not require reoperation, the overall results were excellent in 6 hips, good in 3, and poor in 1 hip. Of the 5 hips requiring reoperation, the results were excellent in 3 hips, good in 1, and fair in 1 hip at most recent follow-up evaluation. Cementless components should be considered for all primary and revision arthroplasties in patients with sickle-cell hemoglobinopathies, but early complications are frequent and a high incidence of polyethylene wear and osteolysis requiring reoperation may be expected.

Causes of death after hip arthroplasty in primary arthrosis

The causes of death in 1,018 patients operated on for primary osteoarthrosis with cemented total hip arthroplasty (THA) were compared with those of age- and sex-matched orthopaedic control patients and those of the general population in Finland. The mean follow-up period was 12 years for the THA patients and 11 years for the control patients. During the first 4 years after surgery, the mortality of the THA patients from circulatory diseases was significantly increased compared with that of the orthopaedic control patients; the number of deaths in patients with THA was 34 compared with 17 for orthopaedic control patients, the relative risk being 2.00 (95% confidence interval, 1.13-3.54). During the 10-year period after the surgery, the relative risk of death of the THA patients compared with the orthopaedic control patients was 1.50 for death from circulatory diseases (95% confidence intervals, 1.11-2.00), 0.42 for accidental death (95% confidence interval, 0.55-1.08), 0.74 for death from cancer, and 0.77 for death from other causes. The observed numbers of deaths from circulatory diseases or by accidents for patients with THA during a postoperative time frame of 5 to 23 years did not differ from the numbers expected for an age- and sex-matched subgroup of the Finnish population. The number of deaths from cancer was less than expected (P = .046).

Design of the femoral component for cementless hip replacement: the surgeon's perspective

Few guidelines are currently available to the surgeon when choosing a specific femoral component for cementless total hip replacement (THR). A survey of the members of the American Association for Hip and Knee Surgeons (AAHKS) was conducted to gain insight into the importance of implant material, stress shielding, and micromotion in the selection of cementless femoral components. A comprehensive survey was distributed to 300 orthopedic surgeons selected from the members of the AAHKS; 169 of the 300 surgeons completed the detailed questionnaire. The results of the survey were analyzed using the SPSS software package to obtain general trends in opinion, and a stepwise regression analysis was used to correlate responses with training and clinical experience. Interestingly, there was little consensus among surgeons with respect to the relative importance of implant material, stress shielding, and micromotion in the selection of prostheses for cementless THR. In general, bone loss secondary to stress shielding was the least important issue, and axial and rotational micromotion were considered progressively more significant problems. Cementless titanium alloy stems were perceived as offering no significant advantage over cobalt chrome alloy stems. Moreover, there was no consensus as to whether a collar was advantageous. Prosthesis stability, restoration of motion, and a proven clinical record were more important to surgeons than were ease of implantation and removal, cost, and availability.

Autotransfusion--bacterial contamination during hip arthroplasty and efficacy of cefuroxime prophylaxis. A randomized controlled study of 40 patients

40 patients undergoing primary hip arthroplasty, given autologous processed blood transfusion, were randomized a receive no antibiotic prophylaxis (group A, n 20) or cefuroxime (1.5 g single injection; group B, n 20). Bacterial contamination at various steps in the autotransfusion procedure was assessed in liquid and solid culture media. The operation field and the wound drainage blood were never contaminated either of the groups but some of the suction tips were. Parts of the Vacufix blood collection bags of group A contained bacteria, but none in group B. Processed red blood cell concentrates in both groups showed bacterial growth. Greater blood loss did not increase the contamination rate in general. Isolated bacteria included the species Staphylococcus epidermidis, coagulase-negative staphylococci and Propionibacteria in both groups, but with different cell counts. In addition, Corynebacterium bovis et minutissimum and Moraxelle were identified in group A. In conclusion, autologous blood transfusion was a safe procedure. If contamination occurred, the bacterial count was low, and the bacteria of low pathogenicity. Antibiotic prophylaxis with cefuroxime reduced this contamination of suction tips and collection bags and limited the transfer of autologous blood products.

Local wound and systemic coagulation/fibrinolysis responses in hip arthroplasty. Influence of allogeneic and autologous blood transfusion

22 patients undergoing elective hip arthroplasty were studied. In 12 patients, a closed-loop autotransfusion system, without anticoagulant, was used and 10 had an ordinary wound drainage allowing repeated blood sampling from the wound. Plasma concentrations of antithrombin (AT), fibrin, soluble (SF) and fibrin D-dimer were determined preoperatively, 3, 8, and 24 hours after starting surgery. Wound drainage blood had increased concentrations of SF and fibrin D-dimer and decreased concentrations of AT compared to reference values and systemic concentrations in patients. Plasma concentrations of SF, fibrin D-dimer and AT did not differ between patients receiving retrieved blood and those receiving stored red blood cell concentrates (RBCs). Patients receiving blood transfusions had lower AT concentrations at 8 hours after starting surgery than those not receiving such a transfusion.

Primary uncemented Osteonics total hip arthroplasty: preliminary results of 2-6 year follow-up

BACKGROUND

Cemented total hip arthroplasty (THA) bears the inherent disadvantages of cement complications. A research toward the improvement of uncemented prosthesis design continues to evolve. The purpose of this report is to present the preliminary results and to identify common problems in uncemented THA.

METHODS

The results of 402 primary Osteonics total hip prostheses were reviewed with an average follow-up period of 3.1 years. The postoperative rating according to the modified D' Aubigne & Postel hip score included functional and radiographic analysis.

RESULTS

The results were rated as good or excellent in 95% of hips. Stable fixation of the prosthesis was shown in 97% of radiographs. The most common zone of focal osteolysis was in the periarticular area.

CONCLUSION

The clinical results in a 2 to 6 year follow-up was encouraging. A relatively high incidence of thigh pain did not correlate with femoral canal filling of prosthesis. Periarticular osteolysis is still an unsettled problem in uncemented prostheses and needs further investigation.

Bone scintigraphic appearance of asymptomatic hydroxyapatite-coated hip arthroplasties

To obtain information about the bone scintigraphic appearance of a hydroxyapatite (HA)-coated proximal femoral implant, this examination was performed on 24 patients with a clinically and radiologically successful femoral implant in hip arthroplasty. The prosthesis had a proximal HA coating for supplementary fixation. The patients' mean age was 50.3 years (range, 28-65 years) at operation. The interval from the operation to the scintigraphy ranged from 6 months to 5.5 years (mean, 2.2 years). Scintigraphy was performed using 99mTc-medronic acid. Quantitative counts were recorded in 4 zones: 3 along the length of the implant (trochanteric region with HA coating, midprosthesis, and distal tip) and 1 below the prosthesis. The results were expressed as ratios using the nonoperated femur as a control value. The results demonstrated that the mean activities in all 4 zones were increased relative to the untreated side. The highest activity was observed in the region around the prosthetic tip, with an elevation of 46% above the control value. This activity showed a significant decline over time. The counts recorded in the trochanteric region, where the implant was coated with HA, were 20% above the control value and similar to those seen in its adjacent noncoated midprosthetic region. In the trochanteric region, however, the activity did not show a decline over the follow-up period.

A more stable posterior approach for hemiarthroplasty of the hip

The dislocation rate following the insertion of a hemiarthroplasty of the hip via the posterior approach is variously quoted as between 8 per cent and 15 per cent. We set out to determine if this could be reduced by preserving the labrum and capsular structures at the time of surgery. We used a modification of the posterior approach, in which the labrum and capsule are preserved which appears not to have been widely reported. This increases the stability of the joint by adding to the depth of the acetabulum. We look prospectively at a series of 150 patients who were treated with an Austin Moore hemiarthroplasty using this technique. There were only two dislocations within 1 year of surgery in the series (one of these being in a patient with a dysplastic acetabulum) making our dislocation rate 1.3 per cent. We conclude that preserving the labrum significantly increases the stability of a hemiarthroplasty when it is inserted via a posterior approach.

Cement pressurisation during hip replacement

The newer techniques of cementing aim to improve interlock between cement and bone around a femoral stem by combining high pressure and reduced viscosity. This may produce increased embolisation of fat and marrow leading to hypotension, impaired pulmonary gas exchange and death. For this reason the use of high pressures has been questioned. We compared finger-packing with the use of a cement gun by measuring intramedullary pressures during the cementing of 31 total hip replacements and measuring physiological changes in 19 patients. We also measured pressure in more detail in a laboratory model. In the clinical series the higher pressures were produced by using a gun, but this caused less physiological disturbance than finger-packing. The laboratory studies showed more consistent results with the gun technique, but for both methods of cementing the highest pressures were generated during the insertion of the stem of the prosthesis.

Total hip arthroplasty in patients with osteonecrosis. The effect of cement techniques

One hundred fifteen patients who underwent total hip replacement for osteonecrosis between June 1972 and April 1990 were divided into 3 groups according to the cause of the disorder: (1) osteonecrosis secondary to alcoholism (21 patients), (2) osteonecrosis secondary to hypersteroidism (29 patients), and (3) idiopathic osteonecrosis (65 patients). To determine the differences in short and long term arthroplasty failure rates, these 3 patient groups were compared with a group of 202 patients who received total hip replacement for osteoarthritis. Statistical analyses were carried out on the following definitions of failure: loosening of the acetabular component, loosening of the femoral component, and revision arthroplasty. Radiolucency and postoperative pain scores also were evaluated. A significant difference in the rate of failure because of loosening of the femoral component was found among the 4 groups. Likewise, a significant difference was found among the 4 groups in all revisions or loosenings or both. However, only the comparison between the idiopathic osteonecrosis and osteoarthritic groups showed a significant difference with survival analysis. Second generation cement technique was as significant as any variable relating to failure. The authors conclude that total hip arthroplasty is an equally viable treatment for the 3 types of osteonecrosis examined in this study; however, failure might be more imminent in studies where larger numbers are needed.

Radiological and survival comparison of four methods of fixation of a proximal femoral stem

We compared the radiological appearances and survival of four methods of fixation of a femoral stem in 538 hips after follow-up for five or ten years. The fixation groups were: 1) press-fit shot-blasted smooth Ti-A1-V stem; 2) press-fit shot-blasted proximally ridged stem; 3) proximal hydroxyapatite (HA) coating; and 4) cementing. Survival analysis at five to ten years showed better results in the HA-coated (100% at five to six years) and cemented stems (100% at 5 to 6 years) than in the two press-fit groups. There was a higher mean rate of migration in the smooth and ridged Ti-A1-V shot-blasted press-fit groups (0.8 mm/year and 0.6 mm/year, respectively) when compared with the HA-coated and cemented prostheses (both 0.3 mm/year). More radiolucent lines and osteolytic lesions were seen in the press-fit groups than in either the HA-coated or cemented implants, with a trend for a lower incidence of both in the HA compared with the cemented group. Proximal osteopenia increased in the press-fit and cemented prostheses with time, but did not do so in the HA group. There was a higher incidence of resorption of the femoral neck with time in the cemented group than in the other three. We conclude that the HA and the cemented interfaces both provide secure fixation with a trend in favour of HA. The cemented prosthesis meets the suggested National Institutes of Health definition of 'efficacious' at ten years.

Acetabular and femoral fixation 15 years after cemented total hip surgery

Total hip arthroplasty in patients younger than 51 years of age remains controversial. The authors report results in 47 hips in 40 patients at an average followup of 15 years. Second generation femoral cementing techniques were used. Special attention was given to studying the differences between the outcome of acetabular versus femoral fixation. The patient group included 11 in whom custom components were used and 13 who had structural autografts for severe acetabular dysplasia. One femoral component and 10 acetabular components were revised for aseptic loosening. After 15 years, improved cementing techniques produced a marked reduction in the rate of femoral aseptic loosening. Loss of fixation of cemented acetabular components was common.

Stanmore total hip replacement in younger patients: review of a group of patients under 50 years of age at operation

Fifty-seven Stanmore Total Hip replacements were implanted between 1974 and 1986 in patients under the age of 50 years. We have reviewed the results in terms of survivorship and function, and assessed the reasons for revision. Of the original 57, 22 (39%) have been revised at an average of 12 years from implantation, usually for aseptic loosening. Most of them had originally been implanted for osteoarthritis. Prostheses cemented with second-generation techniques have lasted significantly longer, and acetabular loosening emerged as a continuing problem. The overall survivorship was 90% at 10 years and 68% at 15 years. Cemented hip replacement appears to be a viable option in younger patients and the Stanmore implant is comparable with other cemented prostheses in this age group.

Total hip arthroplasty after previous proximal femoral osteotomy

We compared 74 total hip arthroplasties (THAs) carried out after previous proximal femoral osteotomy with a diagnosis-matched control group of 74 primary procedures performed during the same period. We report the perioperative results and the clinical and radiological outcome at five to ten years. We anticipated a higher rate of complications in the group with previous osteotomy, but found no significant difference in the rate of perioperative complications (11% each) or in the septic (8% v 3%) and aseptic (4% each) revision rates. There was a trend towards improved survival in the group without previous osteotomy (90% v 82%), but this difference was not statistically significant. The only significant differences were a higher rate of trochanteric osteotomy (88% v 14%) and a longer operating time in the osteotomy group. Our study indicates that THA after previous osteotomy is technically more demanding but not necessarily associated with a higher rate of complications. Furthermore, proximal femoral osteotomy does not jeopardize the clinical and radiological outcome of future THA enough to exclude the use of osteotomy as a therapeutic alternative in younger patients.

Prosthetic replacement of the hip in dogs using bioactive bone cement

Total hip arthroplasties were performed in dogs using bioactive bone cement consisting of silane treated CaO-MgO-SiO2-P2O5-CaF2 glass powder as the filling particles and bisphenol-a-glycidyl methacrylate based resin as the organic matrix, and the outcomes were compared with the results of polymethylmethacrylate bone cement. The mechanical properties of the bioactive bone cement were stronger than the mechanical properties of polymethylmethacrylate bone cement. The bonding strength of the bioactive bone cement to bone in dogs' femora increased with time, reaching 4.7 MPa at 6 months, whereas that of polymethylmethacrylate bone cement did not increase, remaining at 1.0 MPa. Results of histologic examination showed direct bonding between the bioactive bone cement and bone, and the bony trabeculae around the cement mantle grew with time. However, in polymethylmethacrylate bone cement, an intervening soft tissue layer was evident at the bone cement interface. Direct bonding of the bioactive bone cement at the interface through an apatite layer of 30 microm in thickness was shown through observation with the scanning electron microscopy. Using this bioactive bone cement in clinical settings may help alleviate serious problems associated with cemented total hip arthroplasty, such as aseptic loosening of the implant and mechanical failure of the bone cement.

Acetabular osteolysis and migration in bipolar arthroplasty of the hip: five- to 13-year follow-up study

We have reviewed 65 bipolar arthroplasties of the hip in 55 patients with osteoarthritis secondary to dysplasia. The mean age at operation was 56 years (42 to 79) and the mean period of follow-up was 7.2 years (5.0 to 13.0). The average Merle d'Aubigné and Postel score before operation was 10.3 and at final follow-up 15.0. There were excellent or good results in 42 hips (65%). Migration of the outer head was observed in 50 hips (77%), most often in the group with a centre-edge angle of less than 0 degrees, an acetabular head index of less than 60%, coverage of the outer head by the original acetabulum of less than +10 degrees and after bone grafting of the acetabulum. This migration was progressive in 31 (62%) of the 50 hips, with massive osteolysis of the acetabulum in eight. The extent and progression of migration were closely associated with this osteolysis. Four hips required revision for extensive migration of the outer head with destruction of the acetabulum or severe acetabular osteolysis, and nine hips are awaiting revision for failure of the bipolar prosthetic head. The overall failure rate was 18%. We report major problems after bipolar hip arthroplasty for osteoarthritis secondary to hip dysplasia with progressive migration of the outer head and massive acetabular osteolysis at five years or more after operation.

Comparison of warfarin use in total knee replacement vs total hip replacement

The purpose of this retrospective study was to determine the efficacy of warfarin prophylaxis against deep vein thrombosis (DVT) in total hip arthroplasty (THA) vs total knee arthroplasty (TKA). A review of venograms in 223 patients with THA and in 189 cases of TKA was carried out. The overall DVT rate in THA was 22%. The overall DVT rate in TKA was 46%. We conclude that combined or alternate methods need to be used to decrease the rate of DVT following TKA to that of THA.

Pelvic lysis and polyethylene wear at 5-8 years in an uncemented total hip

The clinical and radiographic results of 160 primary, uncemented porous coated total hip replacements performed at 3 teaching hospitals were reviewed. Followup was obtained in 132 of 148 (89%) nondeceased patients. The acetabular component is a full hemisphere, fabricated of cobalt chrome with a sintered bead coating and was implanted with screws in all cases. A 32 mm cobalt chrome femoral head was used in all cases. At 2 to 4 years the incidence of pelvic lysis was 0 and no acetabular revisions had been performed. At 5 to 8 years followup, 3 of 132 (2%) femoral stems had been revised, while on the acetabulum side discrete expansile pelvic lytic lesions occurred in 15 cases (11%) with 8 cases (5%) requiring revision. Abrasion of the screwhead against the backside of the polyethylene liner was seen in all retrieved cases and may have contributed to the development of the lytic lesions seen. Use of this uncemented press fit hemispheric acetabular components, using adjunctive screw fixation resulted in an unacceptably high rate of polyethylene wear and aggressive pelvic lysis. While the results on the femoral side were good, the results with this uncemented acetabular system did not represent an improvement over previous cemented or uncemented acetabular components.

Reimplantation of infected hip arthroplasties using bone allografts

Twenty-two patients with deep infection of an hip prosthesis received delayed reimplantation using bone allografts. Sixteen were done using noncemented components and 6 using femoral components that were fixed with antibiotic impregnated cement. Bulk allografts were used at the acetabular site in 2 patients and at the femoral site in 4 patients. Morselized allografts were used at the acetabular site in 20 patients and at the femoral site in 10 patients. The causative organisms were virulent in 10 hips and low virulent in 12 hips. At an average followup of 4 years (range, 2-7 years), 91% of patients were free of infection and 73% had a successful functional result. Two had a recurrent infection; 1 of them had a pseudomonas infection and another had a methicillin resistant Staphylococcal infection. The recurrence of infection tended to be higher if the causative organism was virulent. The use of bone allografts at the staged reimplantation of the infected hip arthroplasty did not increase the incidence of recurrent infection. Both cemented and noncemented reimplantations had a successful result in eradicating the infection. However, hybrid reimplantation with a cemented femoral component and fixed porous acetabular component had a better functional outcome than noncemented reimplantation using porous femoral component and nonfixed acetabular component.

Radiographic analysis of a cemented titanium alloy femoral component

Proximal femoral cortical bone remodeling was evaluated radiographically about a 1 piece cemented titanium alloy femoral prosthesis implanted with modern cement techniques and was compared with one described previously in which early cement techniques and a stainless steel stem were used. Two hundred twenty-six total hip replacements (196 patients) were observed for an average of 6.3 years (range, 5-10 years). Analysis of all hips revealed that the ratio of cortical thickness to that of the overall femoral bone diameter did not change significantly about the periprosthetic bone throughout the length of the study. Cortical hypertrophy and atrophy occurred at rates similar to those seen with the early cement techniques. Distal fusiform cortical hypertrophy and the formation of osteosclerotic (reactive) lines at the bone cement interface occurred at approximately half the rate using modern cement techniques. In addition, cortical atrophy was associated with the formation of these reactive lines, the occurrence of osteolytic lesions, and progressive bone cement interface radiolucencies. Although periprosthetic cortical atrophy occurred at rates similar to those reported previously, important differences were noted between the findings of this study and the earlier study; these differences most likely were a result of cement technique or the prosthesis.

The effect of surgical approach on femoral stem position in canine cemented total hip replacement

A prospective clinical study was designed to determine the effect of surgical approach on femoral stem position in canine cemented total hip replacement. Candidates for total hip replacement were randomly placed into one of two groups. In one group (n = 10), a craniolateral approach to the hip joint was made, incorporating a femoral trochanteric osteotomy. In the other group (n = 11), a craniolateral approach to the hip joint was made without performing a femoral trochanteric osteotomy. Radiographs obtained immediately after the operation were evaluated by two independent examiners for femoral stem position (neutral, varus, or valgus) and percentage of femoral canal fill, using a defined protocol. There was no statistical difference in femoral stem position between the study groups, whereas a greater percentage of canal fill was associated with the neutral femoral stem position.

Uncemented total hip arthroplasty in osteonecrosis: a 2- to 10-year evaluation

All patients undergoing uncemented total hip arthroplasty for end stage hip disease related to osteonecrosis of the femoral head were assessed prospectively between November 1983 and October 1992. The results of clinical evaluation using the Harris Hip score and radiographic assessment of fixation were analyzed to identify features of success or failure that may be unique to this population. Four different stem types and 4 different acetabular components were used. Sixty-four patients had 98 hips implanted during the time of the study. The 42 male and 22 female patients averaged 41 years of age (range, 21-69 years). Average followup was 87.3 months (7.3 years; range, 31-134 months). The cause of osteonecrosis was corticosteroids (42 hips), alcohol (27 hips), trauma (5 hips), and other (24 hips). Three patients (5 hips) have died and 4 patients (6 hips) are lost to followup. At last followup 65 of 87 hips (75%) remained radiographically stable and clinically functional, 18 of 87 (21%) have been revised, and 4 were failing (osteolysis). Of the 22 hips with revision or impending failure, 4 were for technical reasons on the femoral side and 18 were for acetabular wear. Patient factors such as weight or underlying disease state did not seem to influence the ability to achieve stable fixation or contribute to accelerated failure. Failures related primarily to problems of first generation devices including accelerated wear of acetabular components, technical issues of femoral component placement (undersizing of components or femoral fracture), and the use of noncircumferentially coated femoral components. Age may be a factor in early failure. This 10-year experience with total hip arthroplasty for the patient with end stage hip disease due to osteonecrosis suggests that uncemented total hip arthroplasty can be applied predictably to this younger, potentially more active patient population.

Long-term results and survivorship of Protasul 10 straight stem Müller femoral hip prosthesis

In a retrospective study 88 consecutively cemented Protasul 10 straight stem total hip prostheses, implanted during a two year period, were investigated. After a nine to ten year period 8 hips had been revised. In the clinically and radiologically checked group, the patients' opinion was in 82% very good or good, in 9% moderate and in 9% bad. The X-Ray findings showed in 20% an initial or advanced loosening of the stem and/or the cup. The survivorship after a nine to ten year period is 89%.

Course of bone mineral content changes around cementless Zweymueller total hip arthroplasty. A 4-year follow-up study

In this prospective study we followed the bone mineral content (BMC) changes over time in seven zones of interest around uncemented Zweymueller total hip arthroplasty (THA) components, using dual-energy X-ray absorptiometry (DEXA) combined with a radiographical analysis of the distal femoral cortices, close to the tip of the stem. In 36 women (average age 55 years) operated on for primary hip osteoarthritis, BMC of the hips was measured preoperatively and 2 weeks, 1 year and 4 years postoperatively. In particular, a significant decrease of the preoperative values (ranging from 35% to 42.53%; P = 0.05 to 0.01) was noted immediately postoperatively in zones 2-7. Thereafter, an additional significant increase of BMC was observed between the first and last observations at the greater (30%, P < 0.05) and lesser (35.48%, P < 0.01) trochanter. The BMC changes over time were not related to the age of the patients. The BMC reduction observed immediately after implantation of the Zweymueller THA is probably related to the intraoperatively removed bone from (1) the medial and distal inner surface of the acetabulum and (2) the inner femoral cortex. Thereafter, the BMC in zones 2, 6 and 7 remained practically unchanged. The fact that a significantly delayed BMC increase was found in the region of the greater and minor trochanter 4 years later may be due to an increasing, continuous bone turnover in the intertrochanteric area. Thus, the Zweymueller screw socket becomes definitively anchored immediately postoperatively in the medial and distal thirds of the acetabulum and remains stable over time, whereas the Zweymueller stem is mainly anchored within the distal femoral cortex as well as within the mass of the greater and minor trochanter, and was still stable at the 4-year follow-up.

[Validity and reproducibility of osteodensitometric DEXA-measurements following total hip endoprosthesis]

For the determination of reproducibility of bone densitometric measurements we performed a measurement according to the DEXA- method. 35 patients after implantation of total hip replacement were examined with a Lunar DPX-L. We received a maximum reproduction error of 1.2% according to the GRUEN-analysis. The operated hip of 17 patients showed an increase in bone density between 5 and 18% by the implantation of an arthroplasty compared to the preoperative values. The non-operated prosthesis-corrected hip showed a reproduction error of 3.8% in ROI 1 in 17 patients, otherwise a maximum of 1.3%. Considering an interfemoral difference in bone density of up to 20%, differences in periprosthetic bone density of up to 40% compared to the contralateral side can be within the normal range in a retrospective measurement. Therefore retrospective determination of bone density after cementless hip arthroplasty only is of limited value. Only prospective analysis can provide reliable information about the actual loss of bone density.

Failure mechanisms of anatomic porous replacement I cementless total hip replacement

The APR-I Hip System was designed for metaphyseal bone attachment by proximal patch porous coating and the acetabular component was a hemisphere fixed with screws. The results of 100 consecutive primary total hip arthroplasties performed with the APR-I were studied in patients still alive after an average of 6.7 years. The selection of hips for implantation of this hip system was limited to those patients in whom a satisfactory intraoperative fit could be obtained. This resulted in a distribution of patients such that 75% were younger than age 65 years and only 15% had osteoporotic bone. The revision rate was 16% with a mechanical failure rate of 11%. Seventy percent of hips had progressive loss of fixation. loss of femoral component fixation was correlated with younger patient age, higher patient activity level, metaphyseal fill of less than 90%, and increased polyethylene wear and osteolysis. Eighty-nine percent of hips maintained femoral neck contact with the porous coated collar. The acetabular component was well fixed in 97% of hips. The failure rate of the APR-I stem is unacceptably high and this stem is no longer used by the authors.

Short term prophylaxis against heterotopic bone after cementless hip replacement

The aim of the current study was to reveal whether 7 days of indomethacin treatment sufficiently prevents heterotopic ossification after cementless total hip arthroplasty. One group received indomethacin for 14 days (n = 102), and the second for 7 days (n = 99) after cementless total hip arthroplasty. At followup 1 year postoperatively, the average Harris Hip Score was 91 points in the 14-day treatment group and 89 points in the 7-day treatment group. The incidence of heterotopic ossification as outlined by Brooker was similar in both groups. Ninety-six patients in the 14-day treatment group had heterotopic ossification Grades 0 or 1, and 6 patients had Grade II heterotopic ossification; whereas in the 7-day treatment group, 95 patients had Grades 0 or 1 heterotopic ossification and 4 patients had Grade II ossification. None of the patients had Grades III or IV heterotopic ossification. In the 14-day treatment group, headache, dizziness, or gastritic disorders develop in 10 patients, and in the 7-day treatment group, 7 patients had these effects. This study shows that treatment with 100 mg indomethacin daily for 7 days is not significantly different than 14 days of treatment for the prevention of formation of severe heterotopic ossification after cementless hip arthroplasty.