[Improved radiological imaging of acetabular screw socket]

The improved radiological representation of the cementless acetabular screw-socket at two levels is of fundamental importance for the postoperative determination of position as well as for the judgement of an aseptic loosening. To improve the radiological representation two special radiographic techniques in the anterior-posterior as well as in the axial view have been examined on a human preparation of pelvis and have been scrutinized on a great number of clinical patients. The a.-p. radiography with twenty degrees cranio-caudal prone view in the sagittal plane and the axial radiography with forty-five degrees caudo-cranial prone view in the coronal plane shows the best and fewest overlayed representation of the screw-socket. The position of inclination and anteversion could have been directly determined out of these two radiographs. Malpositions of the screw-socket, especially with regard to the anteversion are easily identifiable due to the special axial radiographic technique. Overprojection of adjoining bone areas, which were possible should be considered at the judgment of the implant-bone-contact. Radiographic technical and positioning problems were not observed in patients. Out of these examinations the a.-p. radiography with twenty degrees cranio-caudal prone view in the sagittal plane and the axial radiography with forty-five degrees caudo-cranial prone view in the coronal plane could be recommended to the radiological diagnosis after implantations of hip prosthesis.

Advantage of the transprosthetic drainage system (TDS) for application in cemented hip arthroplasty--a standardized experimental comparison with other cementing techniques

We constructed a computer-assisted implantation device to compare different cementing techniques of stem implantation in total hip arthroplasty, thus avoiding any manual influence during implantation. We used an intramedullary plug in each case. Conventional cementing techniques, employing an additional lateral drain for the femoral canal or applying the cement by hand, did not lead to a satisfyingly reproducible quality of the cement mantle. With the vacuum cementing technique, in which an additional cannulated screw is inserted into the plug from the lateral side of the femur for the application of the vacuum, the cement mantle improved in quality, but there was still a relatively high number of bubbles incorporated in the cement. We think that, even under improved experimental circumstances, it is not always possible to place the cannulated screw correctly into the plug in order to achieve a satisfying drainage of the femoral canal with this procedure. The transprosthetic drainage system showed the best results due to the optimized position and working capacity of the drain.

The role of bone traumatization in the initiation of proximal deep vein thrombosis during cemented hip replacement surgery in pigs

Hip arthroplasty is associated with a high frequency of postoperative solitary proximal deep vein thrombosis which seems most frequently observed when bone cement is used for prosthesis fixation. Eighteen pigs underwent hemiarthroplasty, eight with cement-fixed prostheses and eight with non-cement prosthesis installation. Levels of thrombin-antithrombin (TAT) complexes, tissue plasminogen activator (t-PA) activity and plasminogen activator inhibitor 1 (PAI-1) activity were determined in femoral vein blood from both limbs during and after surgery. On the operated side, TAT increased during bone traumatization followed by a substantial rise in t-PA activity and a gradual decline in PAI-1 activity. This indicates a local per- and post-operative sequential activation of coagulation and fibrinolysis followed by a fibrinolytic shutdown, all reflected in femoral vein blood on the operated side. In the animals receiving noncemented hip prostheses, the same pattern of activation of coagulation and fibrinolysis occurred on the operated side. This was, however, less marked than with the cement-fixed prostheses. Postoperative scanning electron microscopic (SEM) examination of the femoral veins showed thrombi on the operated side in 62% of the animals in the cement group and 25% in the non-cement group. In an additional study with eight animals undergoing cement-anchored hip prosthesis operations the levels of TAT, t-PA and PAI-I were analysed in femoral vein blood, mixed venous blood and arterial blood. Significantly higher levels were found in femoral vein blood compared with mixed venous blood while no significant change was found in arterial blood compared with mixed venous blood. The hyperthermia induced by curing bone cement was effectively conducted by the implanted prosthesis and did not seem to exert major influence on the activation of coagulation. Extreme rotation of the limbs during surgery did not in itself induce visible vein wall damage as judged by SEM. These studies indicate that traumatization of bone marrow during hip surgery induce a marked local activation of coagulation and a high incidence of deep vein thrombosis in proximal veins, in particular if bone cement is used for prosthesis fixation.

One-stage revision of total hip arthroplasty for deep infection. Long-term followup

One hundred eighty-three total hip arthroplasties were revised for deep infection in a 1-stage procedure using antibiotic containing acrylic cement and systemic perioperative antibiotics. At an average followup of 7 years 9 months, 154 (84.2%) patients were free of infection. The remaining 29 (15.8%) patients had evidence of persistent infection. The quality of pain relief immediately after a revision for deep infection often is a good predictor of success.

Survivorship analysis of acetabular revision in medial, lateral, and global primary osteoarthritis

Acetabular revision rates after cemented total hip arthroplasty vary from series to series in the literature. Little attention has been paid to the type of primary osteoarthritis in these previous series. We studied 782 cemented total hips in 671 patients with an average follow up of 7.5 years. Acetabular revision rates were analyzed in medial, lateral, and global primary osteoarthritis using survivorship analysis. Medial osteoarthritis was associated with a higher acetabular revision rate when compared to lateral osteoarthritis (P = .015). No differences were noted in acetabular revision rates when the preoperative diagnosis was medial vs global or lateral vs global primary osteoarthritis (P = .18 and P = .45, respectively). According to this study, a preoperative diagnosis of medial primary osteoarthritis should be added to a list of several factors associated with increased cemented acetabular failure, especially in the Charnley prosthesis.

Revision for aseptic loosening of uncemented cups in 4,352 primary total hip prostheses. A report from the Norwegian Arthroplasty Register

From September 1987 until January 1994 the Norwegian Arthroplasty Register recorded 5,021 primary total hip replacements performed with uncemented acetabular components. We compared the survival until revision for aseptic loosening of the cup, in the 11 commonest types (n 4,352). The overall cumulative revision rate for the acetabular components was 3.2% after 5 years and 7.1% after 6 years, with large differences among the designs. With the hydroxyapatite (HA)-coated cups and the hemispheric porous-coated cups, the failure rate was less than 0.1%. Of the unthreaded hemispheric porous-coated cups, Harris-Galante and Gemini (n 626), none had been revised, and of the HA-coated cups, Atoll and Tropic (n 1,943), only 1 had been revised. For the threaded uncoated metal-backed cups, the results varied from no revisions of the PM cups (n 148) to a cumulative 6-year revision rate of 21% for the Ti-Fit (n 300). The all-polyethylene Endler cups (n 334) had a cumulative revision rate of 14%. Women and patients with inflammatory arthritis had poorer results. However, the type and the design of the cups were of far greater importance for the results than patient-related factors.

Early revision among 12,179 hip prostheses. A comparison of 10 different brands reported to the Norwegian Arthroplasty Register, 1987-1993

On the basis of data from the Norwegian Arthroplasty Register during the period 1987-1993, we have compared times to revision for 10 different cemented total hip prostheses. A total of 11,169 patients, with 12,179 primary total hip replacements (THRs), performed with high viscosity cement for primary arthrosis and followed for a maximum of 6.4 years, were included in this study. The Kaplan-Meier estimate of the overall percentage revised after 5 years was 2.5 (95% Confidence Interval: 2.1-3.0). For the Charnley prosthesis (n 6,694), 2.9% were revised after 5 years (95% CI: 2.3-3.4). Using Cox regression to adjust for gender, age, type of cement and use of systemic antibiotic prophylaxis, the Charnley prosthesis was compared with the 9 other brands. The revision rate for the Spectron/ITH combination (Spectron acetabulum, ITH femur) (n 1,034) was only 0.35 (p 0.04) times that of the Charnley prostheses. The Elite/Charnley combination (Elite acetabulum, Charnley femur) (n 507) and the Müller Type prosthesis (n 116) showed poorer results with failure rates 2.3 (p 0.01) and 2.7 times (p 0.04) that of Charnley, respectively. Although the overall results for cemented THRs in general were good, clinically important differences in revision rates were demonstrated among the cemented prosthesis brands. Our findings underline the need for careful evaluation of different total hip replacements.

Ten strategies to reduce blood loss in orthopedic surgery

In any operative procedure, careful surgical dissection with precise hemostasis is one of the most effective ways to minimize surgical blood loss and reduce the need for allogeneic red blood cell transfusion. Several other techniques contribute to reduce blood loss in major orthopedic procedures. These techniques are reviewed and include rehearsal of the procedure and positioning the patient to reduce venous engorgement. In addition, a case report is presented that demonstrates the feasibility of revision hip replacement surgery without the use of transfusion in a Jehovah's Witness patient.

[Total hip alloplasty using the Müller method. A six and a half year follow-up study]

From January 1984 to December 1986, 383 total hip arthroplasties were performed in 353 patients. Median age at operation was 69 (24-85) years. At follow-up median 78 (62-102) months after operation, 261 patients with 278 arthroplasties were still alive. A questionnaire was sent to all living patients, 258 patients (99 per cent) replied. Fifty-seven patients with 61 arthroplasties complained of pain and were called in for a check-up including x-ray. Including the dead patients a total of six arthroplasties had been revised, two because of aseptic loosening of the cup and three because of loosening of both components. One had been revised because of deep infection. In the patients called in for check-up seven were suspected of loosening of the stem and one of loosening of the cup. Survival analysis according to Kaplan-Meier showed a survival rate of the prosthesis of 98.5 per cent at 61/2 years. It is concluded that the results after total hip arthroplasties with the straight stem Müller prosthesis are satisfactory. The patients from this study will be followed prospectively from now on to investigate the long-term survival of this type of prosthesis.

Use of cemented all-polyethylene and metal-backed acetabular components in total hip arthroplasty. A comparative study

The results of 115 primary total hip arthroplasties (97 patients) performed using the Charnley system and contemporary cementing techniques were reviewed. Fifty-five all-polyethylene cups and 60 metal-backed cups were used. The mean follow-up period was 84 months. No statistically significant difference was noted between groups for radiographic loosening and no cup has been revised to date. Survival analysis did not reveal a statistically significant difference between groups. Although all-polyethylene cups had significantly greater polyethylene thickness, no difference was noted for rate of wear. Increased loosening of the metal-backed cups was not observed. Polyethylene thickness is increased by the use of 22-mm heads and this may have accounted for the lack of difference in loosening rates of the all-polyethylene and metal-backed cups.

Failure of a proximally porous-coated femoral prosthesis in revision total hip arthroplasty

A retrospective study was done on a consecutive series of patients who had revision of a femoral hip prosthesis using a titanium-alloy implant with proximal fibermesh pads. Of 28 patients who had revision using a Harris-Galante (Zimmer, Warsaw, IN) femoral prosthesis between 1985 and 1989, 25 of them (25 hip arthroplasties) were followed for an average of 5.5 years (range, 4-8 years); the other 3 had died. There were 12 men and 13 women whose age averaged 55 years. Thirty-two percent of the patients had moderate or severe femoral bone stock deficiency before surgery and 72% had intramedullary femoral bone-grafting. All of the patients had revision of the acetabular component using a cementless Harris-Galante prosthesis. Five (20%) of the 25 patients have undergone repeat femoral revision, 4 for aseptic loosening and 1 for persistent thigh pain. Of the 20 hips that have not been revised, 9 (45%) of the femoral prostheses have subsided 5 mm or more. Femoral endosteal lysis was present in 36% of all the hips. Only 8 (32%) of the 25 patients had radiologic signs of bone ingrowth fixation of the femoral component. The average Harris hip score rose from 46 before surgery for all 25 patients to 82 (range, 55-100) at last follow-up examination for the 20 patients not rerevised. Because of the poor clinical results (36% of patients with a poor Harris hip score [4 patients] or rerevised [5 patients]) and radiologic results (48% subsidence) of femoral reconstruction with this proximally porous-coated femoral prosthesis, its use for revision hip surgery is not recommended.

Normalized and proportionalized cemented femoral stem designs. A 10-year clinical study

Two hundred fifteen cemented total hip arthroplasties were performed in 184 patients using normalized and proportionalized femoral stems. Normalization or stepped tapering of the stem minimizes development of tensile hoop stresses by altering force transmission from the femoral stem to the cement mantle. The proportionality of the stem was based on an anatomic study that resulted in the development of a series of prostheses achieving a more complete femoral canal fill. Patients were followed clinically and radiographically from 8 to 12 years or until revision. Average hip scores (d'Aubigne and Postel) improved for pain (3.0-5.9), function (2.9-5.5), and motion (3.3-5.5). Radiographic results demonstrated a 4% incidence of loosening, a 16% incidence of cortical hypertrophy, and no femoral stem fractures. Revision rate was 3%. These results support use of this device.

Cementless total hip arthroplasty in patients with osteonecrosis of the femoral head

The authors studied 61 patients (78 hips) who had avascular necrosis of the femoral head, seen in followup for an average of 7.2 years (range, 6-9 years) after they had primary cementless porous-coated total hip arthroplasty. This study was undertaken to determine whether cementless porous-coated prostheses have any merit over reported cemented total hip arthroplasty using contemporary techniques. The average age of the patients at the time of surgery was 48 years old (range, 20-73 years). The average preoperative hip score was 45.6 points (range, 28-75 points), which improved to 90.3 points (range, 34-100 points) at the 7.2-year followup examination. Sixteen of 78 arthroplasties failed in the period of followup, for an overall failure rate of 20.5%. Of the failed hips, 11 had femoral component loosening, 4 had femoral and acetabular component loosening, and 1 had excessive wear in the polyethylene liner. Four femoral components and 5 acetabular components were revised. Twenty-one of the 78 hips (27%) had an average of 5.6 mm (range, 3-9 mm) of wear in the polyethylene liner. Sixteen (20.5%) of 78 hips had acetabular and femoral periprosthetic osteolysis, and 22 (28.2%) hips had femoral periprosthetic osteolysis only. The cementless total hip arthroplasty in this series had a higher incidence of aseptic loosening of the femoral component, polyethylene liner wear, and periprosthetic osteolysis than that reported for cemented total hip arthroplasty using contemporary techniques.

[A shock-absorber-damper endoprosthesis for the hip joint]

The paper deals with the construction of an implant for complete thigh joint removal. The implant works on a new principle, i.e. division of the major parts of the prosthesis into load-carrying and bearing parts which are isolated all the way with damping silicone gaskets. The implant has a fundamentally new construction. It is accessible for commercial production by advanced technologies and readily applicable in clinical practice. The estimated results of its application are positive as when used, the implant brings a considerably less pressure to bear on the bone than do the well-known Russian and foreign implant models.

Intraoperative complications during total hip arthroplasty

Total hip replacement is one of the most common adult reconstructive procedures performed today. Even though training in total hip replacement has become fairly common in many orthopedic residency programs, complications can still occur during surgery. Preoperative planning and close attention to detail may prevent intraoperative problems. Awareness of the potential downfalls allows the surgeon to properly prepare for surgery, avoid intraoperative complications, and manage unavoidable problems when they do arise.

Survivorship of uncemented proximally porous-coated femoral components

Three hundred seventy-five consecutive total hip arthroplasty revisions done using proximally porous-coated femoral components of 6 designs were reviewed a mean of 4.7 years after surgery. Fifty-nine hips have been rerevised for aseptic femoral loosening, and 4 for osteolysis. Moderate or severe pain was present in 23% of surviving hips, and radiographic evidence of femoral loosening was present in 38% of surviving hips at the most recent followup. At 8 years, survivorship free of revision for aseptic femoral failure (for loosening or osteolysis) was 58% (95% confidence intervals, 44.3%, 69.6%); survivorship free of aseptic femoral loosening (revision for aseptic loosening or radiographic loosening) was 20% (95% confidence intervals, 12%, 27%); and survivorship free of symptomatic femoral loosening (revision for aseptic loosening or radiographic femoral loosening with moderate or severe pain) was 45% (95% confidence intervals, 32.3%, 56%). More severe preoperative bone loss correlated with poorer survivorship free of aseptic loosening and subsidence of > or = 5 mm. Differences among the prosthetic-type groups with respect to patient's age, gender, and bone loss severity precluded direct comparison of performance for each prosthetic type; however, all the prostheses had a significant rate of rerevision and aseptic loosening. Stable long-term fixation with the proximally porous-coated femoral components used in this series was not achieved on a predictable and reproducible basis. The damaged, weakened bone often present in the proximal femur during revision probably does not provide an optimal environment for sturdy initial or long-term biologic fixation of these devices that rely on the proximal femoral bone for fixation.

Results of cemented femoral revision total hip arthroplasty using improved cementing techniques

Seventy-nine consecutive femoral component revision total hip arthroplasties done in 73 patients from 1977 to 1983 using a distal intramedullary cement plug and a cement gun delivery system were evaluated to determine if improved results were obtained with newer cementing techniques. At a minimum 10-year followup interval, only 1 patient was not available for followup and 47 hips had minimum 10-year followup radiographs. The incidence of femoral rerevision for aseptic loosening was 9.5% for those hips with minimum 10-year followup and 5.4% for the entire group. The incidence of radiographic femoral failure (defined as a revision or definite or probable loosening) was 26.1% for those hips followed for a minimum of 10 years and 16.3% for the entire group. Compared with historical controls, these results represent an improvement over those reported with the use of earlier cementing techniques.

Revision arthroplasty with an isoelastic uncemented femoral stem

We carried out 102 hip revision arthroplasties using an uncemented isoelastic femoral stem on 92 patients between 1985 and 1989. The proximal femoral bone stock had deteriorated in 45%. Eleven patients died during the mean follow up of 5.7 years. The femoral component has been revised again for loosening in 13, for infection in 5 and for dislocation in 3. Radiographs of 70 hips showed incipient migration at 3 months in 20, and at the time of review 27 hips had migrated 5 mm or more. Nine stems had migrated more than 8 mm and were judged to be loose. There were 11 fractures before operation and 15 during operation; they all healed. Slight cortical hypertrophy of not more than 2 mm was present in most cases. Three patients (4 hips) were excluded because of severe systemic illness. Of the remaining 66 hips, the clinical outcome was excellent in 18%, good in 50%, fair in 26% and poor in 6%. The isoelastic stem is associated with poor primary fixation which is indicated by early subsidence. The results, with a total failure rate of 33%, are unsatisfactory and the isoelastic femoral stem used in this series cannot be recommended for revision operations.

Revision total hip replacement using the S-ROM femoral component

The proximally porous-coated, modular S-ROM femoral component was used in 52 complex total hip revisions done in 48 patients. These patients had severe bone loss, leg length inequality, and instability. Twenty-two patients required structural femoral allografts; 8 had previous resection arthroplasties for sepsis. The mean number of previous hip operations was 3. The stem was press fit, and the metaphyseal sleeve was selectively cemented to the allograft. The preoperative Harris rating was 44 points; at a mean of 3 years, followup was 82 points. Eighty-four percent of the patients were satisfied with their outcomes. No radiographic or histologic evidence of fretting at the modular sleeve-stem junction or along the stem was seen. Significant thigh pain persisted in 2 patients and was directly related to stem diameters > 17 mm. Complications in these complex cases were not infrequent, reflecting the need for allograft augmentation, and included greater trochanter bursitis and nonunion in 20 hips, minor nonpropagating fracture in 13 hips, and 12 dislocations. Mechanical loosening occurred in 5 hips. There were no complications attributable to the S-ROM modular femoral component, and the prosthesis has proven to be versatile and did well in these very difficult cases.

Proximal femoral allografts for reconstruction of bone stock in revision arthroplasty of the hip

Proximal femoral allografts have been used to restore uncontained circumferential defects of the multiply revised total hip arthroplasty. These grafts are used with long stem components that are cemented to the graft but not the host. The junction of host and graft is stabilized by the stem and a step cut with cerclage wires. Autograft bone is placed at the junctions to induce union. Full weightbearing is delayed until union occurs between the graft and the host femur, usually by 3 months. One hundred sixty-eight structural femoral allografts were done; average followup was 4.8 years as of January 1, 1995. Success was defined as an increase in the clinical score of at least 20 points, a stable implant, and no need for further surgery related to the allograft. The success rate in 130 patients with at least 2 years followup is 85%. There have been 17 revisions in 16 patients: 3 revisions for infection, 8 for dislocation, 5 for nonunion, and 1 for pain. The revision rate is 10.1%. Radiographic analysis showed 7 nonunions, minor resorption in 6 patients, and significant resorption in 1 patient. All implants are stable with no lucent lines. The results support using this technique for full circumferential segmental proximal femoral defects in revision hip arthroplasty.

Preliminary report of impaction grafting for exchange femoral arthroplasty

Gie and Ling have described a method for femoral component revision using compressed morselized cancellous allograft and a cemented collarless polished taper stem. The authors report their early experience with this technique. Of the first 67 patients who had femoral exchange by impaction grafting, 60 were alive 2 to 5 years after hip revision; 2 hips failed because of late sepsis, and 5 patients were decreased. In 56 individuals available for review, the Harris Hip Score average was 90 points, with > 80% reporting no pain. On radiograph, 48% of the stems showed an average of 2.8 mm of subsidence in the polymethylmethacrylate mantle, but only 7% of the cement graft composites had subsided in the cortical tube. Lucent lines were rare, and in 93% of revised femurs the radiographs showed evidence of graft incorporation and bone remodeling. There were 6 reoperations in the group: 3 for late fracture of the femoral shaft and 3 for cup exchange (2 chronically dislocating, 1 loose). No evidence for femoral component loosening was found in this group. Further study is necessary, but these preliminary findings give rise to cautious optimism that this is a reliable method for femoral revision, reconstruction, and reconstitution.

Morselized allograft in acetabular reconstruction. A postmortem retrieval analysis

Contained acetabular defects often are repaired at revision surgery using morselized bone allograft. The extent to which this graft becomes incorporated is unknown, and the value of radiographs for predicting allograft incorporation is unclear. To better understand the effectiveness of morselized allograft in revision hip arthroplasty, the authors studied postmortem specimens from 3 patients treated with this type of graft. Histologic analysis of acetabular components in situ for 18 months showed allograft fragments invested with loose myxofibrous tissue. Vascularized tissue had penetrated the allograft fragments to a depth of 4 mm. In peripheral areas, the vascularized ingrowth was accompanied by partial osteoclastic resorption of graft trabeculae and application of living bone to allograft fragments. After 53 months in situ, graft fragments had remodeled and showed progressive vascular ingrowth. By 83 months, the graft almost completely had incorporated. Morselized allograft bone is useful for restoring bone deficiency within contained acetabular defects. The graft does incorporate, but the extent of graft incorporation cannot be predicted accurately by postoperative radiographs.

Uncemented porous-coated anatomic total hip replacement in Chinese patients

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.

Appositional bone bridging of primary gaps in the dome area of uncemented, porous acetabular components

Reported here are two cases of primary hybrid arthroplasties using a cemented stem and an uncemented, porous acetabular component. Because of the configuration of the acetabula, a residual central gap remained after implantation of the socket. Unimpacted grafts were used to fill the spaces. The gaps, amounting to 4 to 5 mm on the postoperative radiographs, had disappeared at the 30-40-month follow-up examination, with no radiolucent lines at the bone-implant interface. Both sockets were evaluated by roentgen stereophotogrammetric analysis for 2 years, and by using this technique for detecting micromovements, central migration as a reason for the disappearance of the gaps was precluded. Bony apposition of primary gaps of up to 5 mm in the central area of well-fixed porous acetabular components seems possible.

Effect of neck resection on torsional stability of cementless total hip replacement

Loosening of the femoral component in total hip arthroplasty commonly results from inadequate resistance to torsional loads. We evaluated 20 adult human cadaver femora to determine the effect of different neck-resection levels on torsional resistance of the femoral component. All specimens were prepared for fixation with the Impact modular total hip replacement. Each femoral diaphysis was overreamed 2 mm to achieve only proximal fixation. The specimens were then divided into groups of five and implants were inserted with the precision press-fit technique. Each specimen was loaded in an Instron stress-testing device. A linearly variable differential transducer was then attached to the specimen to measure micromotion at the medial interface between the implant and bone. Each specimen was loaded until failure occurred. When all of the neck was preserved, torsional load to failure was significantly better than in the 50%, 15%, and 0% neck-preservation specimens. At a 20 N-m torsional load, the 100% and 50% neck preservation specimens had similar micromotion, but the 15% and 0% specimens had gross motion and a large standard deviation at this load level. Without distal fixation, the femoral component is highly dependent on proximal geometry for resistance to torsional loading. Preserving the femoral neck provides an effective means of resistance. Maintaining the entire femoral neck most effectively reduces miromotion at low loads, but maintaining the midshaft area of the femoral neck appears to most effectively control micromotion at higher torsional loads. Resection below the midshaft of the neck markedly decreases the torsional load-bearing capacity of the proximal femur.

Femoral revision hip arthroplasty with uncemented, porous-coated stems

One hundred seventy-five cementless femoral hip revision surgeries with extensively porous-coated stems and 161 concomitant acetabular revisions done from 1984 to 1991 were retrospectively reviewed. Average age at surgery was 62.4 years. Followup ranged from 2 to 10 years (average, 5 years). One hundred sixty-eight femoral components (96%) remain in place. Two unstable components, 1 stable fibrous component, and 1 bone ingrowth component were painful and required rerevision. Two femoral components were removed as part of resection arthroplasties for repetitive acetabular failure caused by pelvic dissociation. One component was removed for late hematogenous infection. Using the Engh radiographic criteria, femoral stems were judged to have achieved bony ingrowth in 82.8% (n = 174) of the cases. Bony ingrowth occurred more frequently when the canal was filled with the prosthesis and with lesser degrees of bone stock deficiency. Severe stress shielding occurred in 11 (7.6%; n = 144) of the bone in-grown cases and correlated with preoperative osteoporosis and larger diameter prosthesis. Significant thigh pain was less common in the bone ingrown (4.2%; n = 144) than in the stable fibrous group (18.5%; n = 27). Significant thigh pain in bone ingrown stems was more likely to occur with osteoporotic and bone stock-deficient femurs. To date, significant wear and osteolysis have not been observed.

Ten years of experience with porous acetabular components for revision surgery

A prospective study was completed for 139 porous-coated revision acetabular components that were implanted with rim fit fixation and had a mean of 4.3 years' followup (range, 2-9.8 years). The Anatomic Porous Replacement component was studied. Harris Hip Scores were used for clinical evaluation, and the pain and limp components of the Harris Hip Score were assessed. Radiographic measurements were recorded as radiolucent lines by Delee and Charnley zones. Clinical results were of lesser value in this study because of the emphasis on the acetabular component. Of these components, 4.3% had revision; only 2 (1.4%) were revised for loosening. Migration occurred in 2.1% of these acetabular components. In the first 2 years postoperatively, 17.4% of components had increased radiolucent lines and 9.4% had fewer radiolucent lines. After 2 years, fixation was stable: 4% had progressively more radiolucent lines and 2% fewer radiolucent lines. The authors could not show any statistical difference in radiographic fixation of these components when adjunctive screw fixation was used or not used. Fixation of the acetabular components was better when slurry bone graft was not used to layer the acetabular surface. Fixation was similar whether the rim fit was obtained with or without protrusion of the medial dome of the cup into the pelvis. The authors did not observe osteolysis in the acetabular bone surrounding these components.

Recementing a femoral component into a stable cement mantle using ultrasonic tools

Recementing a femoral prosthesis into a retained cement mantle was done during revision total hip arthroplasty in 15 patients using ultrasonic tools to reshape the existing cement mantle. Early complications such as bone perforation or fracture were avoided. The 2-year followup in 4 patients revealed no adverse effect on the bone-cement interface as judged radiographically. One patient had rerevision for instability at 1 year after operation. Indications for this technique include isolated failure of the cement-prosthesis interface, femoral component fracture, or isolated acetabular revision in which exposure needs, instability, leg length inequality, or femoral-head size dictated change of the femoral component.

Influence of surgical approach on dislocations after Charnley hip arthroplasty

Dislocations occurring in 3,199 Charnley total hip arthroplasties in two orthopaedic centers between 1979 and 1991 performed by either the transtrochanteric or posterior approach were studied. The incidence of dislocation within 2 years of surgery (2.8%), as well as the overall frequency (3.4%), did not differ between the two centers. Regardless of approach, there was a higher risk of dislocations for patients with osteoarthrosis. A logistic regression analysis, reflecting the differences in preoperative hip diagnoses and sex, indicated that the dislocation rate was not influenced by the surgical approach. More early dislocations were documented after the posterior approach, but without increases in the rates of recurrence or revision. Arthroplasties performed by less experienced surgeons through the posterior approach resulted in more dislocations.

A new osteotome for performing chevron trochanteric osteotomy

We report on the use of a new modified osteotome for performing chevron trochanteric osteotomy during hip arthroplasty. It is easy to use and the apex of the chevron is directed distally, thus producing a large segment of osteotomized trochanter, while avoiding the problems of fragmentation and splintering. At the end of the procedure, the trochanter is easily seated back within its concave bed, automatically achieving anatomical reduction and allowing easier fixation using the cruciate wiring technique. In a series of 77 primary hip arthroplasties, bony trochanteric union was achieved within 6 months in all patients.

Revision total hip arthroplasty using a cementless acetabular component. Technique and results

Are the midterm results (range, 7-11 years) for revision of the acetabulum with a cementless hemispherical component comparable with other published revision techniques at similar followup? One hundred thirty-eight acetabular revisions for aseptic loosening were done in 132 patients using a cementless hemispherical component coated with titanium mesh and inserted with supplemental screw fixation. Twelve patients died, 9 were lost to followup, and 6 could not return for followup, leaving 111 patients (115 hips) with a mean of 100 months of followup. Thirteen hips required revision (11%): 4 were done for recurrent dislocations, and 6 for sepsis; 3 stable cups were revised (at the time of stem revision). No cup was revised for aseptic loosening. Radiographic review was available for 105 patients (109 hips) at mean 98-month followup (78-135 months). A complete radiolucency was seen in 4% of the cups, a partial progressive radiolucency in 3%, and a partial nonprogressive radiolucency in 54%; no radiolucency was present in 39%. A screw radiolucency was seen in 2%, and osteolysis at the cup margin in 4%. Revision of the acetabulum with a cementless porous-coated hemispherical fiber-metal component is superior to the results reported for acetabular revisions with cement at similar followup.

[Single-session bilateral hip alloplasty. A simultaneous procedure in 79 patients]

The aim of the study was to evaluate the per- and postoperative complications in 79 consecutively operated selected patients with bilateral hip disease who had bilateral hip replacements performed in one session. It was carried out as a retrospective examination of the case records, a questionnaire and clinical and radiological follow-up of 41 patients after a median of 7.5 years. No serious complications were registered peroperatively, and the duration of anaesthesia was on average three and a half hours. Eight patients were treated for early postoperative complications. The average hospitalization time was 15 days. Forty-one patients were followed up at a minimum of five years postoperatively. All patients were fully satisfied with the result, and there had been no cases of dislocation or reoperation. The average hip function index had been 7.2 preoperatively, and was at follow-up found to be 16.7. Radiological examination showed signs of looseness in 12 of the 82 examined hips. It is concluded that in selected patients with bilateral hip disease necessitating bilateral hip replacement the two operations may with benefit be carried out in one session.

Low friction arthroplasty at 10 to 20 years. Consequences of plastic wear

One hundred eighty-seven patients, in whom 224 low friction arthroplasties were done by 1 surgeon from 1972 to 1983, were observed for 10 to 20 years. An attempt was made to reassess each patient annually. Pain, walking, and passive range of motion were graded on a 6-point scale (d'Aubigné and Postel assessment). Active movements, straight leg raising, and abduction against gravity were recorded in degrees. The average scores, based on 224 assessments done preoperatively, 1914 assessments done during the first 10 years, and 590 assessments done during the second 10 years, were as follows: pain--3.28, 5.71, and 5.59 points; walking--3.34, 5.16, and 4.87 points; passive range of motion--3.42, 4.61, and 4.54 points; straight leg raising--40.5 degrees, 60.8 degrees, and 54.9 degrees points; and abduction against gravity--8.8 degrees, 24.3 degrees, and 19.0 degrees points. The percentage of cases with no cement-bone interface demarcation based on > 2000 radiologic observations was as follows: cup Zone I--9.9%, Zone II--26.4%, and Zone III--26.3%; and femoral Zone 1--72.5%, Zone 2--96.7%, Zone 3--94.2%, Zone 4--89.6%, Zone 5--96.7%, Zone 6--96.3%, and Zone 7-72.6%. A relationship was seen between wear of the socket, and cup migration and revision, development of femoral endosteal erosions (significant at 95% confidence level), and femoral prosthesis migration and revision. Ultra high molecular weight polyethylene particles that migrate to the cement-bone interface are believed to be an important cause of loosening and failure in total hip arthroplasty.

The rat as an animal model for total hip replacement arthroplasty

Dogs, goats, and sheep are the most commonly used animals in studies of total hip replacement (THR) arthroplasty. However, the development of a small, laboratory animal model could have significant economic and housing advantages over these models when studying the long-term systemic effects of chronic mechanically functional implants. A THR was designed and fabricated with a cobalt-alloy (F-75) femoral and UHMWPE acetabular component for PMMA-cemented implantation in the rat. Mature Sprague-Dawley rats (n = 18) were maintained at a constant weight (450 g) and were trained to walk on a low-speed (6 m/min), horizontal treadmill, 15 min/day, 5 days/week. Each animal was randomly assigned to one of three surgical groups: functional, nonfunctional, and sham. The functional and nonfunctional groups underwent identical procedures, except that in the nonfunctional group the femoral head was placed so as to prevent articulation with the socket in the acetabular component. The sham procedure consisted of exposing and opening the joint capsule and the iliac wing without luxating the femoral head or severing the ligamentum teres. In addition, half of the animals in each group resumed exercising on the treadmill at 1 week after surgery. The implants were recovered at 2 months after surgery. The results show that the surgical procedure is feasible in the rat, the postoperative recovery was typical of that for THR, and the rats were able to resume their exercising regimens. Radiographic evaluation revealed that the majority of the sham and the nonfunctional animals had luxated hips, while the majority of the functional animals had reduced hips. Histological results were typical of THR in other species. The success of the surgical model suggests that the rat may be a feasible, reduced-cost alternative to other lab species in systemic, long-term THR studies.

Perioperative low-molecular-weight heparin. Is it effective and safe

In previous randomised clinical trials of thromboprophylaxis after total hip replacement, low-molecular-weight heparin has been given for an arbitrary 7 to 14 days. The risk factors are mainly perioperative and it is possible that a shorter course may be adequate. We assessed the safety and effectiveness of a three-day course. We assessed 156 primary THR patients after randomisation to either a control group or to receive enoxaparin at 12 hours preoperatively and 12 and 36 hours postoperatively. Thrombosis was diagnosed by routine venography. Haemorrhagic side-effects were assessed by measurement of blood loss, and soft-tissue side-effects by descriptive scores for wound discharge and bruising of the leg. The prevalence of calf thrombosis was 15.4% in the enoxaparin group and 32.1% in the control group (p = 0.01); the prevalence of proximal thrombosis was 15.4% and 17.9% respectively (not significant). There was no difference in haemorrhagic side-effects or wound discharge, but there was more bruising in the enoxaparin group.

Custom-made molds that prevent cement extrusion through bone defects

The success of a hip arthroplasty using a cemented femoral component relies in part on the quality of the cement technique, and is enhanced by obtaining a uniform, well-pressurized cement mantle around the prosthesis. For that reason, cortical bone defects in the femur pose technical difficulties for the surgeon planning a cemented femoral component. In this article, a new technique is presented that is used to prevent cement extrusion through defects in the femoral cortex when pressurizing the cement mantle around the prosthesis. Custom-molded polymethylmethacrylate (bone cement) plugs may be fashioned during operation to fill temporarily defects of almost any size.

[Total hip endoprosthesis following resection arthroplasty]

From 1976 to December 1994, a total of 347 patients underwent implantation of a hip prosthesis at the ENDO-Klinik for treatment of an unsatisfactory condition following resection arthroplasty. From 1976 to 1987, 143 patients were treated and in 1989 the results obtained in these patients were analysed: 99 of them were available for a follow-up examination in 1989, and 64 for a further examination in 1995. In 130 cases infection had been the reason for joint resection. At the time of the prosthesis operation (1-20 years later) intraoperative biopsy revealed that infection was still present in 41 cases (31.5%). Only 15 of these infections had been detected preoperatively by joint aspiration. This shows that the value of resection arthroplasty as a method of treating periprosthetic infection is limited and lends support to the one-stage exchange operation, which is the method we prefer in cases of infected hip prostheses. The operative technique and preparation for implantation of the prosthesis are described, as are septic and aseptic complications and the measures that can be taken to treat them. In spite of the patients' generally poor initial condition and with due consideration for the further revision operations, the medium-term results finally obtained are poor in only 9%.

Autogenous bone grafts from the femoral head for the treatment of acetabular deficiency in primary total hip arthroplasty with cement. Long-term results

Thirty-five consecutive total hip arthroplasties in twenty-eight patients were performed with use of cement and insertion of an autogenous graft from the femoral head. Five patients (six hips) subsequently died or were lost to follow-up. The results for the remaining twenty-three patients (twenty-nine hips) were reviewed retrospectively at a mean of eleven years (range, seven to seventeen years) after the operation. All of the grafts united. The mean estimated coverage of the acetabular component by the autogenous graft was 27 per cent (range, 15 to 45 per cent). Three sockets (10 per cent) were revised because of symptomatic loosening without infection at a mean of ten years (eight, ten, and twelve years) after the index procedure. All three hips were found to have viable, bleeding bone in the region of the remaining graft. An additional eight acetabular components had a nonprogressive, asymptomatic, continuous radiolucent line at the cement-bone interface. This finding was assumed to indicate loosening of the socket, so the total prevalence of loosening was 38 per cent (eleven of twenty-nine sockets). There was no significant difference between the loose and the well fixed components in terms of the amount of coverage by the graft (p > 0.2) or the method of fixation (p > 0.4). There was no collapse or resorption of the graft that was of mechanical consequence. Autogenous femoral-head bone-grafting is a useful technique with a good potential for long-term success when the amount of coverage by the graft is limited to less than 40 per cent of the surface of the acetabular component.

[Allograft transplantation in pelvic instability following prosthesis exchange]

The collective consists of 19 patients with 21 operations after multiple revision operations with complete pelvic instability. The reconstruction was done with tibia (11x) and femur allografts (6x). The bridging was reached by pressfit contact. The junction side was supplemented with autologous bone chips. The allografts were fixed with screws or plates. In all patients a good primary stability was achieved. Partial weight bearing was gained within 10.1 week and full weight bearing in 15.1 weeks. We notice one allograft fracture after 4 months and one infection after 3 months. The reoperation rate was 4. The clinical results are encouraging. No lytic lines were seen between the acetabulum cup implant and the allograft within 20.1 months time.

Failure of the Ring polyethylene uncemented acetabular cup

We report a high rate of failure of the Ring polyethylene cementless cup caused largely by granulomatous osteolysis. We have reviewed 126 prostheses inserted from 1986 to 1992 at from 11 to 90 months after surgery. There was radiological evidence of osteolytic granulomas adjacent to the external surface of the cup in 32%, appearing on average at three years from operation. In a subgroup of 59 prostheses followed for at least four years the incidence of such changes was 54%. A total of 27 cups (22%) have required revision, 21 for granulomatous loosening at an average follow-up of five years. In the retrieved prostheses there was obvious polyethylene abrasion and histological examination confirmed the presence of polyethylene wear debris. We found no significant correlation of osteolysis with cup size, although smaller cups were predominant among those having revision.

[Results of cementless acetabular revision surgery]

The great number of hip revision arthroplasties and the cementless fixation of arthroplasties has led to more and cementless hip revision operations with bone transplantation. This retrospective study shows the results of a clinical and radiological follow-up of 34 patients with an average age of 71 years and 4 months at their hip revision arthroplasty. The subjective and clinical result in the Harris-Hip-Score 3 years and 9 months (1 year 4 months-6 years 3 months) after surgery shows 67% of the patients content with the result of the revision arthroplasty. The Harris-Hip-Score shows an average of 41.1 points preoperatively and 73.2 points at the follow-up examination. The loosening-rate was 11.8%, all arthroplasties which seemed loosened radiologically had also a bad result clinically. No correlation could be shown between the age of the patients and the clinical results as well as between an additional stem revision (15 patients) and the clinical result in the Harris-Hip-Score. All revision operations were done with bone transplantation and demonstrate, that the concept of cementless fixation of acetabular component gives satisfactory results.

Total hip replacement arthroplasty in patients with inflammatory arthritis

1. Hip involvement in inflammatory arthritis is a relatively common entity. 2. Total hip replacement offers the most reliable surgical treatment option for pain relief and the restoration of hip function when medical management is exhausted. 3. Preoperative evaluation and perioperative medical management should focus on the particular medical problems of patients with systemic rheumatologic conditions. 4. In patients without protrusio deformity, cemented total hip replacement with modern cement technique offers excellent long-term functional results.

The effects of implant orientation, canal fill, and implant fit on femoral strain patterns and implant stability during catastrophic testing of a canine cementless femoral prosthesis

Cementless femoral stems were placed into 12 normal greyhound femora. The implanted femora were divided into three groups by stem orientation and implant size and loaded in axial compression at a rate of 25 newtons (N) per second until failure. Rosette strain gauges were used to measure femoral principal strains at 500 N, 1,000 N, 1,500 N, and at maximum load. During maximum load, varus orientation of the femoral stem had significantly higher tensile hoop strains in the proximomedial cortex, whereas neutral orientation had higher tensile hoop strains along the cranial cortex. Femoral fractures occurred in these areas of peak tensile strain. There was no difference in maximum load between groups, therefore varus orientation did not predispose to fracture. Maximizing canal fill and implant fit increased implant stability.

Total hip arthroplasty

Since 1970 there has been a dramatic increase in the number of total hip arthroplasties done in this country. Many patients have a new lease on life following this operative procedure. There has been a tremendous change in the operative procedure itself, the prostheses, and the preoperative and postoperative care of patients over the past 25 years. This article addresses the present day procedure as well as current methods and concerns for nurses in the care of the patient with total hip arthroplasty.

Comparison of the results of cemented, porous-ingrowth, and threaded acetabular cup fixation. A meta-analysis of the orthopaedic literature

A meta-analysis of the orthopaedic literature was performed to evaluate the clinical performance of cementless, threaded acetabular cups. The hypothesis for the study was that the clinical performance of the cementless, threaded acetabular cup is equivalent to that of the cemented and porous-ingrowth acetabular cups. Ninety-five articles were included in the study. There were 1,269 cases in the threaded cup group, 1,979 in the porous control group, and 10,230 in the cemented control group. The primary outcome variable tested was the rate of aseptic loosening of the acetabular components as measured by the revision rates following the index total hip arthroplasty procedure. Other measures of acetabular component loosening that were analyzed included clinical rating scores, pain scores, frequency of radiolucencies according to location and size, frequency of radiolucencies as a separately defined outcome variable, progressive radiolucencies, and component migration. The threaded cup group was found to have a significantly higher rate of revision, clinical and pain score failures, progressive radiolucencies and migrations when compared with the cemented and porous control groups (P < .05). Despite the many limitations of meta-analyses and the poor state of the orthopaedic literature database, this study provides a reasonable comparison of the clinical performance of threaded acetabular cups with that of cemented and porous-ingrowth acetabular cups.

Extended proximal femoral osteotomy. A new technique for femoral revision arthroplasty

An osteotomy technique for removal of distally fixed cemented and cementless femoral components is described. The anterolateral proximal femur is cut for one third of its circumference, extended distally, and levered open on an anterolateral hinge of periosteum and muscle. This creates an intact muscle-osseous sleeve composed of the gluteus medius, greater trochanter, anterolateral femoral diaphysis, and vastus lateralis, and exposes the fixation surface as well as distal cement. This technique combines the advantages of an extremely wide exposure of component fixation surfaces and preservation of soft tissue attachments to cut bone. In addition, it allows alteration of the proximal femur to facilitate accurate and safe distal cement removal and canal machining under direct vision. The possibility of placing the component in varus is eliminated. The proximal femur is allowed to conform more accurately to the revision prosthesis, a weakened or damaged trochanter is protected from iatrogenic injury, and soft tissue tension can be adjusted. The osteotomy is then repaired with cerclage wires or cables. The first 20 patients treated with this technique are reviewed. Excellent cement and component removal and optimal revision component implantation were obtained with no change in postoperative regimen and reliable healing.

[Replacement of infected total hip prosthesis in two stages]

Since 1975 we have treated 36 infected hip replacements by a two stage procedure in which the prosthesis and cement were first removed. Gentamicin impregnated beads were left at the sites of the prosthesis. Not less than 45 days later a fresh prosthesis was inserted into the hip. In two hips revision was not undertaken because of persistence of infection. The remaining 34 hips received a fresh prosthesis when the site was bacteriologically sterile. Gentamicin impregnated cement was used and antibiotics were given for a further three months. The functional results were satisfactory at an average of five years of follow up. Incomplete removal of methylmethacrylate was a factor in the persistence of infection and of pain in the absence of infection. The bacteriological efficacy of Gentamicin impregnated beads is uncertain, but their use gave a better functional result.