The modern, hybrid total hip arthroplasty for primary osteoarthritis at the Hospital for Special Surgery

We describe our technique and rationale using hybrid fixation for primary total hip arthroplasty (THA) at the Hospital for Special Surgery. Modern uncemented acetabular components have few screw holes, or no holes, polished inner surfaces, improved locking mechanisms, and maximised thickness and shell-liner conformity. Uncemented sockets can be combined with highly cross-linked polyethylene liners, which have demonstrated very low wear and osteolysis rates after ten to 15 years of implantation. The results of cement fixation with a smooth or polished surface finished stem have been excellent, virtually eliminating complications seen with cementless fixation like peri-operative femoral fractures and thigh pain. Although mid-term results of modern cementless stems are encouraging, the long-term data do not show reduced revision rates for cementless stems compared with cemented smooth stems. In this paper we review the conduct of a hybrid THA, with emphasis on pre-operative planning, surgical technique, hypotensive epidural anaesthesia, and intra-operative physiology.

[Cemented stems in hip arthroplasty: history and evolution]

Despite the favorable results in cemented femoral fixation, there is a growing tendency to use uncemented stems. Due to the successful results of cementless acetabular fixation, the most versatile and easy implantation technique, to the misinformation about the "cement disease" and the poor performance of cemented stems with a rough surface. However, the advantages of cemented femoral fixation are numerous: it can be implemented successfully in femurs of diverse morphology and quality of bone, the surgeon can position the implant with the desired femoral anteversion, without it being determined by th natural femoral anteversion, very low incidence of intraoperative and postoperative fractures, allows the addition of antibiotics in patients with a history or predisposition to infection and minimal risk of postoperative leg pain during walking.

A new technique to improve cup inclination accuracy in primary total hip arthroplasty

Accurate inclination and anteversion of the acetabular component is paramount to achieve a stable total hip arthroplasty, prevent prosthetic dislocation and minimize long- term wear. We present and evaluate a simple new technique to improve consistency in cup inclination during primary total hip arthroplasty, based on information available from the preoperative plan. The technique consists of assessing the distance and relationship between the inferomedial border of the acetabular cup and the inferomedial margin of the teardrop, with the use of a measuring probe. This simple surgical gesture improved consistency in cup inclination during total hip arthroplasty.;

Total hip replacement in identical twins with Scheie Mucopolysaccharidosis

Investigation performed at the Hospital for Special Surgery, New York, USA Scheie Syndrome is an autosomal recessive metabolic storage disease with distinct skeletal findings known as "dysostosis multiplex". This paper reports on identical twins with Scheie Syndrome who required total hip arthroplasty for early osteoarthritis of the hip. The surgical approach and exposure was particularly demanding due to the stiffness imposed by the soft tissues arising from infiltration of glycosaminoglycans. The small femoral head and acetabulum limited the diameter of the acetabular component and subsequently the prosthetic head diameter that could be safely utilized without compromising the thickness of the polyethylene liner. Twenty-two millimeter heads with a standard polyethylene insert were therefore utilized in the two arthroplasties performed in 1998 in the first twin, and a 28 mm head with a highly cross linked polyethylene liner, in the arthroplasty performed on the second twin in 2003. This is a relevant issue considering that these patients required an arthroplasty at a young age. Hip arthroplasty relieved pain, improved ambulation and provided a better range of motion in our two patients. There were no peri-operative complications. Long-term survivorship of total hip replacement in this population is not yet known. (Hip International 2005; 15: 55-8).

Age affects the perception of limb length discrepancy in patients with and without a total hip arthroplasty

The amount of lengthening or shortening that can be detected by patients before and after total hip arthroplasty has not been yet quantified. We studied the ability to detect limb length inequality in 194 patients with and without a total hip arthroplasty, match-paired for age and sex. None of the participants had clinical signs of lumbosacral pathology, spinal deformity, or fixed pelvic obliquity; and all had equal functional and actual limb length. The participants walked with shoes, with and without the addition of fixed insoles, to simulate 2.5, 5, 10 and 15 millimeters of shortening and lengthening of the tested limb. Lengthening and shortening were similarly detected. Younger individuals detected the differences better than older ones (p=0.001), and there was a significant correlation between the decade of life and the ability to detect a limb length discrepancy (r=-0.22; p=0.002). This study demonstrates that perception of limb length is affected by the age, with older individuals having less awareness of changes in limb length than younger ones. (Hip International 2004; 14: 249-53).

Inflatable pillows as axillary support devices during surgery performed in the lateral decubitus position under epidural anesthesia

The lateral decubitus position can cause dependent shoulder discomfort or result in traction on the brachial plexus. We measured pressure beneath the dependent shoulder and lateral angulation of the cervical spine in patients positioned in the lateral decubitus position for total hip replacement under epidural anesthesia. Inflatable pillows (Shoulder-Float) beneath the chest wall and head reduced pressure beneath the dependent shoulder from 66 to 12 mm Hg (P < 0.001) and lateral angulation of the cervical spine from 14 degrees to 4 degrees (P < 0.001). In a randomized crossover study of a further 15 patients, the use of inflatable pillows resulted in significantly less pressure beneath the dependent shoulder and chest wall than either a gel-pad or a 1000-mL lactated Ringer's bag. Inflatable pillows placed beneath the chest wall and head in the lateral decubitus position provided lower pressure beneath the dependent shoulder than other support devices and facilitated alignment of the cervical spine.

IMPLICATIONS

When patients lie on their side, this results in pressure beneath the shoulder and tilting of the head and neck to one side. These problems were effectively corrected with an inflatable pillow (Shoulder-Float).

The effect of preoperative donation of autologous blood on deep-vein thrombosis after total hip arthroplasty

We have assessed the effect of the donation of autologous blood and the preoperative level of haemoglobin on the prevalence of postoperative thromboembolism in 2043 patients who had a total hip arthroplasty. The level of haemoglobin was determined seven to ten days before surgery and all patients had venography of the operated leg on the fifth postoperative day. The number of patients who had donated autologous blood (1037) was similar to that who had not (1006). A significant decrease in the incidence of deep-vein thrombosis (DVT) was noted in those who had donated blood preoperatively (9.0%) compared with those who had not (13.5%) (p = 0.003). For all patients, the lower the preoperative level of haemoglobin the less likely it was that a postoperative DVT would develop. Of those who had donated blood, 0.3% developed a postoperative pulmonary embolism compared with 0.7% in those who had not, but this difference was not statistically significant. No significant difference was found in the requirements for transfusion between the two groups.

The effect of preoperative donation of autologous blood on deep-vein thrombosis after total hip arthroplasty

We have assessed the effect of the donation of autologous blood and the preoperative level of haemoglobin on the prevalence of postoperative thromboembolism in 2043 patients who had a total hip arthroplasty. The level of haemoglobin was determined seven to ten days before surgery and all patients had venography of the operated leg on the fifth postoperative day. The number of patients who had donated autologous blood (1037) was similar to that who had not (1006).

A significant decrease in the incidence of deep-vein thrombosis (DVT) was noted in those who had donated blood preoperatively (9.0%) compared with those who had not (13.5%) (p = 0.003). For all patients, the lower the preoperative level of haemoglobin the less likely it was that a postoperative DVT would develop.

Of those who had donated blood, 0.3% developed a postoperative pulmonary embolism compared with 0.7% in those who had not, but this difference was not statistically significant. No significant difference was found in the requirements for transfusion between the two groups.

Pigmented villonodular synovitis of the hip: 2- to 23-year followup study

Pigmented villonodular synovitis affecting the hip is rare. Seven new patients are presented and 117 cases from the literature are reviewed. Among the new patients, two refused treatment; in one patient, severe bone loss was observed after a radiographic followup of 21 years; the second patient showed no radiographic changes 2 years after diagnosis. One patient underwent a synovectomy and had a recurrence 9 years later, requiring a total hip replacement. The remaining four patients underwent synovectomy and primary total hip replacement with no recurrences detected after an average followup of 13 years (range, 2-23 years). Among 117 cases published, 62 patients (53%) did not have enough information for analysis. A metaanalysis using the remaining 55 patients was done. In nine patients (16%; nine of 55) the diagnosis was made with a preoperative biopsy. Treatment consisted of synovectomy in 26 patients (47%; 26 of 55), arthroplasty in 24 (43%; 24 of 55), arthrodesis in two (4%; two of 55), and hindquarter amputation in a patient misdiagnosed as having synovial sarcoma (2%; one of 55). Two patients (4%; two of 55) were not treated. Ten patients had a recurrence (19%; 10 of 53); nine in the synovectomy group (35 %; nine of 26) and one in the joint replacement group (4%; one of 24). Synovectomy is recommended for patients with preserved articular cartilage and total hip replacement is recommended for patients with secondary osteoarthritis. Removal of all macroscopic tumors including careful curetting of the osteolytic lesions should be done as they may constitute a source of recurrence.

Effective bactericidal activity of tobramycin and vancomycin eluted from acrylic bone cement

We studied the bioactivity of vancomycin and tobramycin eluted from methylmethacrylate bone cement. Aliquots of the drainage were obtained at 1, 6, 12 and 24 hours following total hip prosthetic implantation with vancomycin-tobramycin-loaded cement in 3 patients. The samples were analyzed with fluorescence polarization immunoassay and bioassay, using group B streptococcus for vancomycin and Escherichia coli for tobramycin. These bacteria were selected due to the effectiveness of vancomycin and poor effectiveness of tobramycin against group B streptococcus and conversely with E. coli. The immunodetection of vancomycin averaged 14 (1 hour), 9 (6 hours), 10 (12 hours) and 11 microg/mL (24 hours). The bioassay averaged 47, 36, 79 and 41 microg/mL (p = 0.03). The immunodetection of tobramycin averaged 43, 21, 18 and 14 microg/mL; and bioassay 30, 15, 15 and 12 microg/mL (p = 0.1). Both antibiotics eluted with a highly effective bactericidal activity. Our findings indicate that the presence of tobramycin has a synergistic-like effect on the bactericidal activity of vancomycin, which has not been previously reported. We recommend a combination of vancomycin and tobramycin with cement for the treatment of orthopedic infections caused by gram-positive organisms.

Bone density adjacent to press-fit acetabular components. A prospective analysis with quantitative computed tomography

BACKGROUND

The status of periprosthetic bone stock is an important concern when revision total hip arthroplasty is undertaken. Remodeling of periprosthetic femoral bone after total hip arthroplasty has been studied extensively, and the phenomenon of femoral stress-shielding has been well characterized. Finite element analysis and computer-simulated remodeling theory have predicted that retroacetabular bone-mineral density decreases after total hip arthroplasty; however, remodeling of periprosthetic pelvic bone in this setting has yet to be well defined. This study was conducted to evaluate the short-term natural history of periacetabular bone-mineral density following primary total hip arthroplasty.

METHODS

Periacetabular bone-mineral density was studied prospectively in a group of twenty-six patients who underwent primary hybrid total hip arthroplasty for the treatment of advanced osteoarthritis. Density within the central part of the ilium (directly cephalad to a press-fit acetabular component) was assessed with serial quantitative computed tomography. Baseline density was measured within the first five days following the total hip arthroplasty. Ipsilateral density measurements were repeated at an average of 1.28 years postoperatively. Density values at corresponding levels of the contralateral ilium were obtained at both time-points in all patients to serve as internal controls.

RESULTS

Bone-mineral density decreased significantly (p< or =0.001) between the two time-points on the side of the operation. The mean absolute magnitude of the interval density reduction (75 mg/cc) was greatest immediately adjacent to the implant (p<0.001), but it was also significantly reduced (by 35 mg/cc) at a distance of 10 mm cephalad to the implant (p = 0.001). Relative declines in mean density ranged from 33% to 20% of the baseline values. No focal bone resorption (osteolysis) was detected at the time of this short-term follow-up study. With the numbers available, no significant interval alteration in bone-mineral density was found on the untreated (internal control) side (p> or =0.07).

CONCLUSIONS

We suggest that the observed decline in bone-mineral density represents a remodeling response to an altered stress pattern within the pelvis that was induced by the presence of the acetabular implant. This finding corroborates the predictions of finite element analysis and computer-simulated remodeling theory. It remains to be seen whether this trend of atrophy of retroacetabular bone stock will continue with longer follow-up or will ultimately affect the long-term stability of press-fit acetabular components.

Dislodgment of polyethylene liners in first and second-generation Harris-Galante acetabular components. A report of eighteen cases

BACKGROUND

Dislodgment of the polyethylene liner is an increasingly common complication following total hip arthroplasty. The purposes of this study are to present the results in a series of patients with this complication and to analyze the mode of failure.

METHODS

Between November 1995 and January 2001, eighteen patients who had had a total hip arthroplasty presented with dislodgment of the polyethylene liner from a Harris-Galante metal acetabular shell. The medical records, radiographs, operative notes, and retrieved components were reviewed. In addition, scanning electron microscopy was used to study the fractured surfaces in a shell that had four broken tines.

RESULTS

The components had been in situ for an average of seven years (range, three to eleven years). Seventeen components were second generation, and one was first generation. Symptoms developed spontaneously in sixteen patients, during sexual intercourse in one, and following a fall on the hip in one. Radiographs showed eccentric positioning of the head in all of the hips and broken tines in six. All of the shells were well fixed. Treatment consisted of revision of the shell in four patients, exchange of the liner in four, cementation of a new liner into the shell in seven, and cementation of an all-polyethylene cup in three. The liners had severe damage of the rim. Scanning-electron microscopy of the fractured surfaces of four tines revealed a fatigue pattern.

CONCLUSIONS

We believe that, as the liner wears and becomes loose because of an inadequate locking mechanism, progressive micromotion occurs and the load increases on the polyethylene rim until it deforms and/or fractures. Subsequently, nothing prevents the liner from rotating out of the shell. As this mechanism of failure appears to include fatigue failure of the locking tines and wear of the liner, this complication is likely to increase as the components age in situ.

Comparison of the transtrochanteric and posterior approaches for total hip replacement

One-hundred fifty-six consecutive total hip replacements through a lateral transtrochanteric approach were evaluated and compared to a closely matched group of 160 consecutive similar procedures via a posterior approach. The lateral approach did not have any dislocations and created a greater abductor lever arm. However, a 4.5% complication rate was related to the greater trochanter and degraded the result. The posterior approach provided a shorter operative time, required less blood replacement, and resulted in a shorter hospital stay. However a 4.4% incidence of dislocation decreased the rate of recovery and the final result. Since this early experience, an improved technique of reattaching the short external rotators had mitigated the problem of dislocations. Wound and systemic complications, postoperative results, radiographic findings and prosthetic positioning were not significantly different in comparable patients treated by the 2 surgical approaches.

Radiology of total hip replacements

The early and late roentgenograms of the first 100 consecutive Charnley low friction arthroplasties, performed at the Hospital for Special Surgery from October 1968 to October 1970 demonstrate interesting reactions of joint structure. Osteoporosis, early breakage of the wires and trochanteric bed covered by cement were the main factors preventing or delaying the healing of the osteotomy of the greater trochanter. Almost all hips showed a radiolucent line at the acetabular bone-cement junction and about half at the femoral junction. One-third of the hips had increased femoral cortical thickness. Four hips had sterile loosening of the femoral component with a varus shift. Though about one-third of the hips had some ectopic ossification, in only 3 hips was it severe enough to adversely affect the end result. The use of radiopaque cement seems advantageous over the radiolucent type. Arthrography has proven useful for the diagnosis of complications, particularly if subtraction technique is employed.

The safety and efficacy of intraoperative heparin in total hip arthroplasty

A single dose of unfractionated heparin (15 U/kg), administered intravenously before surgery on the femur suppresses thrombogenesis during total hip replacement. Nine hundred eighty-nine patients (1021 hips) who received one dose of intraoperative heparin with hypotensive epidural anesthesia were followed up prospectively for 3 months. Asymptomatic deep vein thrombosis assessed by ultrasound in the first 198 consecutive patients showed an incidence of 7.1% (14 of 198). The incidence of clinical deep vein thrombosis in the subsequent 791 patients was 0.88% (seven of 791). Symptomatic pulmonary embolism occurred in 0.5% (five of 989). No patients died and there was one major bleeding episode. Based on this favorable experience, intraoperative heparin appears safe and efficacious as thromboembolic prophylaxis.

Warfarin-associated intracapsular hemorrhage causing an acutely painful total hip arthroplasty: a rare complication of prolonged anticoagulant therapy

Hemorrhage is the most prevalent adverse effect of oral anticoagulant therapy. The incidence of bleeding complications is related to the duration and range of therapy. A patient on long-term warfarin anticoagulation developed a spontaneous intracapsular bleed into a total hip arthroplasty that had been implanted 11 years before. Joint aspiration allowed early recognition with immediate resolution of symptoms. Diagnosis and treatment of this rare complication are discussed with a review of the literature.

Pneumatic compression hemodynamics in total hip arthroplasty

A crossover study was performed to evaluate the effect of several pneumatic compression devices and active dorsoplantar flexion in 10 patients who underwent total hip arthroplasty. Using the Acuson 128XP/10 duplex ultrasound unit with a 5-MHz linear array probe, peak venous velocity and venous volume were assessed above and below the greater saphenous vein and common femoral vein junction. A computer generated randomization table was used to determine the order of the test conditions. The pneumatic compression devices evaluated included two foot pumps, one foot and calf pump, one calf pump, and three calf and thigh pumps. Statistical analyses included analysis of variance and analysis of variance with covariance between devices and patients. The covariates tested were the baseline measurements and the order in which the devices were tested. Differences between devices relate in part to the frequency and rate of inflation and the location and type of compression. Pulsatile calf and foot and calf pneumatic compression with a rapid inflation time produced the greatest increase in peak venous velocity, whereas compression of the calf and thigh showed the greatest increase in venous volume. Because patient and nursing compliance is essential to the success of mechanical prophylaxis for thromboembolic disease, the more simple, yet efficacious, devices that are easier to apply and less cumbersome appear to have a greater likelihood of success. In the active and alert patient, active dorsoplantar flexion should be encouraged.

The arthroscopic drainage, irrigation, and débridement of late, acute total hip arthroplasty infections: average 6-year follow-up

We present our experience with arthroscopy for the treatment of late, acute periprosthetic hip infections in 8 consecutive patients, treated from 1989 to 1994. After a hip aspiration confirmed the presence of bacterial infection, all patients underwent prompt arthroscopic treatment, which consisted of drainage, lavage, and debridement. Postoperatively, patients were given 2 to 6 weeks of intravenous antibiotics, followed by long-term oral antibiotic suppression. At a mean follow-up of 70 months (range, 29-104 months), no recurrence of infection occurred. No progressive radiographic loosening was noted. Based on this initial study, we believe that arthroscopic irrigation and debridement can benefit well-selected patients who suffer late, acute hip periprosthetic infections. Effective treatment requires early diagnosis, prompt arthroscopic debridement, well-fixed components, a sensitive microorganism, and patient tolerance to and compliance with the antibiotic therapy.

The incidence of venous thromboembolism after total hip arthroplasty: a specific hypotensive epidural anesthesia protocol

We retrospectively reviewed all consecutive unilateral primary total hip arthroplasty (THA) procedures performed by 3 attending surgeons on the Arthroplasty Service at our institution from January 1, 1990, to December 31, 1993. All surgery was performed under a specific hypotensive epidural anesthesia protocol. Hypotensive epidural anesthesia at our institution provides a lower level of hypotension (mean arterial pressure of 50-60 mmHg) as compared to hypotensive anesthesia used more generally around the world (mean arterial pressure >70 mmHg). For each patient, hospital and postdischarge office records for a minimum of 3 months after surgery were reviewed for the type of postoperative screening test, the incidence of deep venous thrombosis (DVT), and the incidence of symptomatic pulmonary embolism (PE). Overall, 2,592 primary unilateral THAs were performed with 78.6% (2,037 of 2,592) of patients receiving a venogram. Our protocol for thromboembolic disease prophylaxis in these patients included aspirin postoperatively as well as antithromboembolic disease stockings and early ambulation (24-48 hours postoperatively). The 555 patients who did not receive venography were managed with a different protocol that included warfarin postoperatively as well as antithromboembolic disease stockings and early ambulation. This high-risk group consisted of patients who received warfarin preoperatively (ie, cardiac valve) or patients with a history of DVT who were to receive warfarin postoperatively, regardless of venography result. Overall, DVT was diagnosed in 10.3% (210 of 2,037) of patients who had a venogram. Of these patients who had venography, 2.3% (46 of 2,037) had an isolated proximal DVT; 6.0% (123 of 2,037), a distal DVT; and 2.0% (41 of 2,037), both a proximal and a distal DVT. Of the 87 cases of proximal DVT identified, 60.9% (53 of 87) were femoral DVT; 18.4% (16 of 87), popliteal DVT; and 20.7% (18 of 87), both femoral and popliteal DVT. Of the 164 distal DVT, 68.3% (112 of 164) were major calf DVT and 31.7% (52 of 164) were minor calf DVT. The overall incidence of major venous thrombosis (sum of proximal and major calf thrombi) was 9.8% (199 of 2,037) in patients who had venography. Ventilation-perfusion scanning was used selectively in patients symptomatic for PE. Overall, symptomatic PE was diagnosed by ventilation-perfusion scan in 1.0% (26 of 2,592) of patients, with 0.58% (15 of 2,592) of patients having an in-hospital PE. Of the 15 patients who had an in-hospital PE, 11 patients had a venogram, and only 3 of 11 were positive. Late symptomatic PE was defined from discharge (mean, 7 +/- 2 days) to 3 months after discharge from the hospital and occurred in 0.42% (11 of 2,592) of patients. One of the 11 late symptomatic PEs was fatal. In the overall study, this represents 0.04% (1 of 2,592) fatal PE. Of the 11 patients with a late symptomatic PE, 10 had venograms in the hospital, and all 10 were negative for DVT. Overall, in the patients with a positive venogram, the incidence of symptomatic PE was 1.4% (3 of 210), whereas in the patients with a negative venogram, the incidence of symptomatic PE was 0.44% (8 of 1,827). At our institution, patients who undergo primary THA performed with hypotensive epidural anesthesia, postoperative aspirin, antithromboembolic disease stockings, and early ambulation have a low risk for thromboembolic disease.

Dose response of intravenous heparin on markers of thrombosis during primary total hip replacement

BACKGROUND

Thrombogenesis in total hip replacement (THR) begins during surgery on the femur. This study assesses the effect of two doses of unfractionated intravenous heparin administered before femoral preparation during THR on circulating markers of thrombosis.

METHODS

Seventy-five patients undergoing hybrid primary THR were randomly assigned to receive blinded intravenous injection of either saline or 10 or 20 U/kg of unfractionated heparin after insertion of the acetabular component. Central venous blood samples were assayed for prothrombin F1+2 (F1+2), thrombin-antithrombin complexes (TAT), fibrinopeptide A (FPA), and D-dimer.

RESULTS

No changes in the markers of thrombosis were noted after insertion of the acetabular component. During surgery on the femur, significant increases in all markers were noted in the saline group (P < 0.0001). Heparin did not affect D-dimer or TAT. Twenty units per kilogram of heparin significantly reduced the increase of F1+2 after relocation of the hip joint (P < 0.001). Administration of both 10 and 20 U/kg significantly reduced the increase in FPA during implantation of the femoral component (P < 0.0001). A fourfold increase in FPA was noted in 6 of 25 patients receiving 10 U/kg of heparin but in none receiving 20 U/kg (P = 0.03). Intraoperative heparin did not affect intra- or postoperative blood loss, postoperative hematocrit, or surgeon's subjective assessments of bleeding. No bleeding complications were noted.

CONCLUSIONS

This study demonstrates that 20 U/kg of heparin administered before surgery on the femur suppresses fibrin formation during primary THR. This finding provides the pathophysiologic basis for the clinical use of intraoperative heparin during THR.

Effect of increasing temperature on the properties of four bone cements

This investigation uses a laboratory model to evaluate the effects of a heated femoral stem on the biomechanical properties of four common acrylic bone cements. American Society for Testing Materials dog bone shaped acrylic cement specimens made at four test temperatures, 0 degree C, 23 degrees C, 37 degrees C and 50 degrees C, were tested for modulus, ultimate tensile strength, fracture toughness, and percent porosity. Fatigue strength was tested in Simplex P at 23 degrees C and 37 degrees C. The data allow direct comparison among four cement brands at each of the four temperature conditions. No adverse changes of the mechanical properties were found for any cement at any temperature. Modulus, fracture toughness, and fatigue strength were unaffected by increased temperature. Ultimate tensile strength increased in Simplex P and Zimmer Osteobond but was unaffected for Zimmer Regular and Palacos R cements. Percent porosity was related to temperature changes inversely in all brands studied, except for Palacos R which consistently had low porosity, unaffected by temperature variation. Fatigue strength of Simplex P was unaffected by heating to 37 degrees C. Based on this laboratory model, heating of the femoral stem could save time without sacrificing mechanical properties of acrylic bone cement.

Role of polyethylene oxidation and consolidation defects in cup performance

Quality factors such as particle consolidation and oxidation have been claimed to impair the performance of ultrahigh molecular weight polyethylene implants, but no definite data estimate their real effect. To assess the influence of these quality determinants in wear, wear rate, and time in service at a single, well proven design, the percentage area of polyethylene sections occupied by nonconsolidated polyethylene particles, the presence of a white band, and the amount of polyethylene oxidation (through density curves) were evaluated in 92 retrieved Charnley acetabular components with available clinical data. The average percentage area of nonconsolidated polyethylene particles in cup sections was 3.1%. There were 11 cups showing a subsurface white band. The authors observed an average density in the deep polyethylene of 0.9420 g/cc after an average in vivo use of 9.8 years (range, 0.08-20.3 years). Banded cups showed significantly higher subsurface densities. When studying the relationship among clinical and material factors with performance variables, wear measurements (obtained through radiographic methods and direct measurements of polyethylene thickness in the collected implants) correlated with age at implantation, activity, and time in service. Weight was a determinant of the wear rate. None of the studied polyethylene quality factors showed a definite association with wear performance or time to failure in this series. Implant survivorship was not significantly impaired in the 22.225-mm Charnley low friction replacement by a subsurface white band or by a higher area occupied by nonconsolidated particles. Fewer nonconsolidated particles were not associated with longer survivorship. This design proved tolerance to polyethylene quality variations, in the signaled ranges, without a significant effect in the system performance.

Enhancement of bone formation in the setting of repeated tissue deformation

The purpose of this study was to investigate whether the osteoinductive recombinant human bone morphogenetic protein 2, combined with a collagen carrier, could enhance bone formation when exposed to controlled amounts of tissue deformation. Chambers that allow for the multiple harvestings of tissue specimen were used. The devices were implanted in the tibial metaphyses of skeletally mature New Zealand White rabbits. A tissue ingrowth canal in each device either was left empty or filled with a collagen carrier with or without 0.6 microgram of recombinant human bone morphogenetic protein 2. The tissue ingrowth canal was deformed cyclically during a period of 2 minutes daily, according to a previously described deformation protocol. The tissue that developed in the chambers was harvested every 3 weeks. Undecalcified histologic sections of each tissue sample were stained with trichrome and von Kossa stains and subjected to histomorphometric analysis. It was found that deformation decreased the area occupied by bone trabeculae in the empty chambers and carrier controls. The amount of bone formed in the chambers treated with bone morphogenetic protein 2 was significantly greater than that in the chambers subjected to micromotion and left empty or implanted with the collagen carrier. The amount of bone in chambers with motion and bone morphogenetic protein 2 was equal to that in chambers left empty and not subjected to micromotion. Qualitative histologic analysis of the bone formed with bone morphogenetic protein 2 revealed normal bone trabeculae. These findings indicate that bone morphogenetic protein 2 may be useful in augmenting bone formation in conditions that otherwise would favor the formation of fibrous tissue.

Patients' expectations and satisfaction with total hip arthroplasty

Although there have been many studies focusing on the increasingly important assessment of patients' satisfaction, few studies have specifically addressed this tissue for total hip arthroplasty (THA). The goals of this study were to measure patients' satisfaction with THA and to evaluate the relationships of expectations and outcome to patients' satisfaction. A total of 180 patients were surveyed 2 to 3 years after THA about their experiences with THA. Patients cited 45 different expectations, which were grouped into five categories reflecting improvement in pain, walking, psychological state, essential activities, and nonessential activities. Overall, 89% of patients were satisfied with the results of surgery. Lower rates of satisfaction were found in patients who had a better preoperative condition (as measured by the surgeons with The Hospital for Special Surgery Hip Scale), in patients who expected improvement in nonessential activities, and in patients who reported worse postoperative condition (as measured by self-assessment with the Hip Rating Questionnaire and the Medical Outcomes Study Short-form General Health Survey). Patients were also asked how they came to THA. Nearly 50% of patients were first referred to an orthopaedist by family or friends or based on their own knowledge. Seventy-four percent either had subsequently referred others for THA or would have done so if they knew someone with hip pain. This study demonstrates that satisfaction with THA is a complex phenomenon, affected by expectations, outcome, and what patients know about the procedure from their community network. A better understanding of THA satisfaction will enable better future selection of patients and an additional dimension of outcome, both of which are important to patients and payers.

Effect of epidural analgesia on venous blood flow after hip arthroplasty

The effects of postoperative epidural infusions using local anesthetic and narcotic were assessed in reference to lower extremity blood flow. Nineteen patients who underwent unilateral total hip arthroplasty were randomly assigned to receive a postoperative epidural infusion of either 5 microg/ml fentanyl or 5 microg/ml fentanyl plus 0.125% bupivacaine at a rate of 10 ml per hour. The infusions were started after complete resolution of the operative epidural blockade. Femoral venous blood flow volume and velocity were measured above and below the saphenous vein bifurcation using an Acuson #128XP/10 computed sonography system (duplex ultrasound) and proprietary software. Femoral venous blood flow was not affected by the type of infusion and did not increase during the study period. However, femoral venous blood flow volume increased 50% after active flexion and extension of the foot, 10 times in quick succession. The addition of bupivacaine (a local anesthetic that blocks sympathetic afferent nerves) to a postoperative epidural infusion does not augment blood flow from the deep veins of the leg after total hip arthroplasty. Alternatively, lower extremity skeletal muscle activity significantly enhances femoral venous blood flow and may be a useful adjunct in deep venous thrombosis prevention.

Cemented total hip arthroplasty in patients with osteonecrosis. A 6-year minimum follow-up study of second-generation cement techniques

Twenty patients with osteonecrosis of the femoral head underwent 28 total hip arthroplasties using cement from 1981 to 1985. Femoral reconstruction was by use of second-generation cement techniques. Twenty-four hips in 17 patients were available for review at a mean follow-up period of 7.7 years. The mean age at surgery was 55 years. Clinical evaluation demonstrated 79% excellent, 4% good, and 4% fair results. Three hips (12.5%) required revision for loosening. The cumulative probability of survival was estimated to be 85.7% at 10 years. Second-generation cement techniques and implant designs did improve the clinical results in this high-risk group; however, the overall mechanical failure rate remained high.

Core decompression for osteonecrosis of the femoral head

A retrospective++ review of core decompression of the femoral head for treatment of osteonecrosis was done. Cause of osteonecrosis, radiographic stage and progression, complications, and clinical results were evaluated. The study was based on 54 hips in 45 patients (98.2% followup rate). All patients reported pain preoperatively. Thirty-five hips (30 patients) were considered to have failed. Of these, 26 hips (23 patients) underwent total hip arthroplasty. The remaining 9 hips (7 patients) had little or no relief of pain and no improvement in function, but had not undergone total hip arthroplasty at last followup. The average time to failure was 11.1 months (2-34 months). Nineteen hips (16 patients) were considered successful. Fifteen hips (12 patients) were graded good to excellent and 4 hips (4 patients) were graded fair in terms of clinical results with an average followup of 47.5 months (12.4-95.7 months). The mean preoperative Hospital for Special Surgery hip score improved from 24.6 points (range, 18-38 points) to 34.2 points (range, 20-40 points). There were 2 intertrochanteric femur fractures in this group (5 and 6 weeks postoperatively). The overall success rate of core decompression in this series was 35.2% (19 of 54 hips, 45 patients). The results of core decompression in this study were poor in general and had an unpredictable effect on disease progression.

Hypotensive epidural anesthesia for total hip arthroplasty: a review

Hypotensive epidural anesthesia provides arterial hypotension to maintain a mean arterial pressure of 50 mmHg and it can be used to reduce blood loss during total hip replacement. The technique combines an extensive epidural blockade with an intravenous infusion of low-dose epinephrine. This results in arterial hypotension, but with preservation of central venous pressure, heart rate, stroke volume, cardiac output, and an augmentation of blood flow to the lower extremity. The technique does not appear to adversely affect cardiac, renal, or cerebral function and is used safely in patients with hypertension, ischemic heart disease, and in the elderly. Intraoperative blood losses during primary total hip replacement are between 100 and 300 mL. Perioperative transfusions have declined with the introduction of the technique. Radiological evidence of improved fixation of cemented acetabular components has been observed. Rates of deep-vein thrombosis are low: 2-3% proximal deep-vein thrombosis with an overall rate of 10%. In-hospital mortality is 0.1%; lower than previously published rates. In conclusion, hypotensive epidural anesthesia is safe and provides a number of advantages over conventional anesthetic techniques for total hip replacement.

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.

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.

Complications of femoral and acetabular modularity

The versatility of modular total hip arthroplasties have rapidly extended their applications. However, these new interfaces can lead to complications that were not observed with monolithic components. These problems have been noted with modular femoral and acetabular components and have been associated with the generation of particulate debris. This article reviews the authors' clinical observations and histologic, biomechanic, and spectophotometric evaluations of modular total hip arthroplasties. New data comparing both synovial fluid metal levels in well-fixed and loose monolithic and modular prosthetic hip implants are presented. In modular total hip components, synovial fluid cobalt levels correlated positively with patient weight and length of implantation. The generation of particulate debris in modular total hip components may induce periprosthetic osteolysis. Taper locks for femoral components and locking mechanisms for the polyethylene liner and metallic cup must be designed to avoid the production of particulate debris.

Magnetic resonance imaging of the pelvis. New orthopaedic applications

A preliminary study of using magnetic resonance angiography to detect occult proximal thrombi in patients who had hip arthroplasty was done. Despite the presence of susceptibility artifact caused by metallic components, diagnostic visualization of thigh vessels was made in a preliminary series of 15 patients. Confirmation of all previously documented (by contrast venogram via dorsal foot vein cannulation or Doppler study) proximal thrombi was made in all 15 patients. One patient had a thrombus in the contralateral extremity that had been undetected by Doppler study; 4 additional pelvic thrombi occurred in 3 patients, which had been undocumented previously. Because magnetic resonance angiography is noninvasive, requiring no contrast agent, it has advantages over conventional venography to detect occult proximal thrombi. New fast spin echo sequences are discussed that enhance visualization of regional anatomic structures adjacent to metallic prosthetic components. Emphasis was placed on assessing the posterior soft tissue envelope in patients having recurrent dislocations after total hip arthroplasty, despite acceptable component alignment. Preliminary results show a consistent absence of a posterior pseudocapsule in patients having dislocations, as compared with control patients having no dislocations.

The John Charnley Award. Thrombogenesis during total hip arthroplasty

The activation of the clotting cascade leading to deep venous thrombosis begins during total hip arthroplasty, but few studies have assessed changes in coagulation during surgery. A better understanding of thrombogenesis during total hip arthroplasty may provide a more rational basis for treatment. In 3 separate studies, the following observations were made. Circulating indices of thrombosis and fibrinolysis: prothrombin F1.2, thrombin-antithrombin complexes, fibrinopeptide A, and D-dimer, did not increase during osteotomy of the neck of the femur or during insertion of the acetabular component, but rose significantly during insertion of the femoral component. Thrombin-antithrombin complexes, fibrinopeptide A, and D-dimer were higher after insertion of a cemented component than insertion of a noncemented femoral component. A significant decline in central venous oxygen tension was observed after relocation of the hip joint and after insertions of cemented and noncemented femoral components, providing evidence of femoral venous occlusion during insertion of the femoral component. In patients receiving a cemented femoral component, mean pulmonary artery pressure increased after relocation of the hip joint, indicating intraoperative pulmonary embolism. No changes in mean pulmonary artery pressure were noted with noncemented total hip arthroplasty. Administration of 1000 units of unfractionated heparin before insertion of a cemented femoral component blunted the rise of fibrinopeptide A. The results of these studies suggest that (1) the greatest risk of activation of the clotting cascade during total hip arthroplasty occurs during insertion of the femoral component; (2) femoral venous occlusion and use of cemented components are factors in thrombogenesis during total hip arthroplasty; and (3) measures to prevent deep venous thrombosis during total hip arthroplasty (such as intraoperative anticoagulation) should begin during surgery rather than during the postoperative period and be applied during insertion of the femoral component.

Hip arthroplasty in patients with chronic renal failure

Patients with chronic renal failure who underwent total hip arthroplasty were retrospectively evaluated. Thirty hips in patients with renal transplants and 16 hips in patients on chronic renal dialysis were reviewed. The average follow-up period was 54 months. The renal transplant patients exhibited generally satisfactory results. Their postoperative course was comparable to that of patients with avascular necrosis undergoing hip reconstruction without underlying renal disease. However, patients undergoing hip arthroplasty while on chronic renal dialysis had poor results (81%), including a deep infection rate of 19%. It was concluded that total hip arthroplasty be reserved for patients who are expecting a renal transplant or preferably those who have already received a successful transplant.

Polyethylene and metal debris generated by non-articulating surfaces of modular acetabular components

We report a prospective study of the liner-metal interfaces of modular uncemented acetabular components as sources of debris. We collected the pseudomembrane from the screw-cup junction and the empty screw holes of the metal backing of 19 acetabula after an average implantation of 22 months. Associated osteolytic lesions were separately collected in two cases. The back surfaces of the liners and the screws were examined for damage, and some liners were scanned by electron microscopy. The tissues were studied histologically and by atomic absorption spectrophotometry to measure titanium content. The pseudomembrane from the screw-cup junction contained polyethylene debris in seven specimens and metal debris in ten. The material from empty screw holes was necrotic tissue or dense fibroconnective tissue with a proliferative histiocytic infiltrate and foreign-body giant-cell reaction. It contained polyethylene debris in 14 cases and metal in five. The two acetabular osteolytic lesions also showed a foreign-body giant-cell reaction to particulate debris. The average titanium levels in pseudomembranes from the screw-cup junction and the empty screw holes were 959 micrograms/g (48 to 11,900) and 74 micrograms/g (0.72 to 331) respectively. The tissue from the two lytic lesions showed average titanium levels of 139 and 147 micrograms/g respectively. The back surfaces of the PE liners showed surface deformation, burnishing, and embedded metal debris. All 30 retrieved screws demonstrated fretting at the base of the head and on the proximal shaft. Non-articular modular junctions create new interfaces for the generation of particulate debris, which may cause granulomatous reaction.

Polyethylene and metal debris generated by non-articulating surfaces of modular acetabular components

We report a prospective study of the liner-metal interfaces of modular uncemented acetabular components as sources of debris. We collected the pseudomembrane from the screw-cup junction and the empty screw holes of the metal backing of 19 acetabula after an average implantation of 22 months. Associated osteolytic lesions were separately collected in two cases. The back surfaces of the liners and the screws were examined for damage, and some liners were scanned by electron microscopy. The tissues were studied histologically and by atomic absorption spectrophotometry to measure titanium content. The pseudomembrane from the screw-cup junction contained polyethylene debris in seven specimens and metal debris in ten. The material from empty screw holes was necrotic tissue or dense fibroconnective tissue with a proliferative histiocytic infiltrate and foreign-body giant-cell reaction. It contained polyethylene debris in 14 cases and metal in five. The two acetabular osteolytic lesions also showed a foreign-body giant-cell reaction to particulate debris. The average titanium levels in pseudomembranes from the screw-cup junction and the empty screw holes were 959 micrograms/g (48 to 11,900) and 74 micrograms/g (0.72 to 331) respectively. The tissue from the two lytic lesions showed average titanium levels of 139 and 147 micrograms/g respectively. The back surfaces of the PE liners showed surface deformation, burnishing, and embedded metal debris. All 30 retrieved screws demonstrated fretting at the base of the head and on the proximal shaft. Non-articular modular junctions create new interfaces for the generation of particulate debris, which may cause granulomatous reaction.

Treatment of the infected total hip arthroplasty with a two-stage reimplantation protocol

Forty-four patients (46 hips) with infected total hip arthroplasties were evaluated. They were entered into a protocol that included resection arthroplasty, six weeks of intravenous antibiotics which obtained a minimum postpeak serum bactericidal titer of 1:8, and possible reimplantation. Thirty-two of 46 hips (70%) were reimplanted. At an average of 40 months (range, 24-74 months) after reimplantation, infection recurred in three hips (9%). In two of the three recurrent infections, 1:8 bactericidal titers were not attained. Both of these hips were infected with gram-negative organisms. Minimum postpeak serum bactericidal titers of 1:8 were attained in 28 of 32 hips that were reimplanted, and only one of these hips (4%) had a recurrent infection (p = 0.035). The presence of retained cement after resection arthroplasty (ten hips) was not associated with recurrent infection. Fourteen hips (12 patients were not reimplanted as a result of a combination of factors, including inadequate bone stock, poor soft-tissue quality, and antibiotic resistance of the infecting organism. The treatment of an infected total hip arthroplasty with resection arthroplasty, six weeks of intravenous antibiotics that attains a minimum postpeak serum bactericidal titer of 1:8, and reimplantation can be an effective and safe treatment.

The prevalence of deep venous thrombosis after total hip arthroplasty with hypotensive epidural anesthesia

A prospective, randomized trial was done to evaluate the prevalence of deep venous thrombosis following primary unilateral or bilateral total hip arthroplasty with use of hypotensive epidural anesthesia, external pneumatic-compression boots, and aspirin (Group I) and with use of hypotensive epidural anesthesia and aspirin (Group II). All operations were performed by two of us (E. A. S. and T. P. S.) through a posterolateral approach. Two hundred and thirty-one patients who were more than thirty-nine years old and who had a total of 250 primary total hip arthroplasties were included in the study. There were 113 patients (124 hips) in Group I and 118 patients (126 hips) in Group II. All patients had venography on the sixth, seventh, or eighth postoperative day. Group I had no proximal thrombi, seven distal thrombi (6 per cent), and one late pulmonary embolus (1 per cent). Group II had one proximal thrombus (popliteal) (1 per cent), eight distal thrombi (6 per cent), and one late pulmonary embolus (1 per cent). The difference was not significant (p = 0.65). However, a significant difference may have been noted if the study population had been larger. The combination of hypotensive epidural anesthesia and aspirin is effective prophylaxis against deep venous thrombosis in patients who have a primary total hip arthroplasty. The extremely low rate of deep venous thrombosis in the present study may be attributed to the use of hypotensive epidural anesthesia and the associated decrease in blood loss and transfusion requirements.(ABSTRACT TRUNCATED AT 250 WORDS)

An analysis of the head-neck taper interface in retrieved hip prostheses

The purpose of this study was to examine the mating surfaces of femoral heads and stems for evidence of corrosion, and to evaluate the quality of the taper lock of modular hip prostheses. Forty-eight implants with three different designs were evaluated. Group I (26 implants) had a cobalt alloy head and cobalt alloy stem. Group II (ten implants) had a cobalt alloy head and a titanium stem. Group III (12 implants) had a cobalt alloy head with a titanium stem that was coupled in the factory via a shrink fit. The implants were examined under light microscopy and scanning electron microscopy. In cases where the femoral head was still assembled to the stem, pull-off testing was performed using an MTS machine. The average failure load for the pull-off tests for each group of prostheses was as follows: Group I (nine implants) 3,003 N +/- 623 N; Group II (six implants) 4453 N +/- 570 N; and Group III (12 implants) 6859 N +/- 3525 N. The Group III implants required a significantly greater pull-off force than those in Group I (p = 0.002). There was no evidence of corrosion in Group I. In Group II, crevice corrosion was noted in one taper interface and there was fretting in two other tapers. No corrosion was noted in Group III. Improving the tolerances of the mating surfaces may be a key factor in preventing corrosion. This would not only increase the forces that are necessary to debond the matting surfaces, but also decrease corrosion by reducing micromotion and fluid at the taper interface.

Palacos gentamicin for the treatment of deep periprosthetic hip infections

Between 1983 and 1986, 40 hip arthroplasties in 40 patients with documented deep infection were reimplanted using Palacos Gentamicin at The Hospital for Special Surgery. Palacos Gentamicin was added to the standard protocol, which included removal of the prosthesis, cement, if present, and a thorough debridement of infected and necrotic tissue, six weeks of intravenous antibiotics with a postpeak serum bactericidal titer of at least 1:8 against the infecting bacteria, followed by reimplantation of the hip. Sixteen of the patients also had the placement of gentamicin-impregnated beads at the time of prosthetic removal. All patients had a deep periprosthetic infection, 13 with Staphylococcus epidermidis, seven Staphylococcus aureus, four Streptococcus, three Enterococcus, three with gram-positive bacteria, four Escherichia coli, two Proteus, one Pseudomonas, and three anaerobic organisms. At an average follow-up period of five years (range, two to ten), two of the 40 hips (5%) developed recurrent infection. These cases recurred at one month in a patient immunocompromised by end-stage systemic lupus erythematosus (S. epidermidis) and at five months in a patient with severe titanium metallosis (S. aureus). No recurrence was noted in eight cases with gram-negative organisms or in three cases of mixed infections. No infection recurred after five months in the remaining patients before their death or last follow-up examination. Of the remaining 38 hips, 16 died of causes unrelated to the hip, leaving 21 with an average follow-up period of 7.5 years. Clinical results in these patients were 14 excellent, five good, two fair, and no poor results.(ABSTRACT TRUNCATED AT 250 WORDS)

Total hip replacement in the elderly: cost-effective alternatives

The cost of the prosthetic components can represent approximately 15% to 25% of the total cost of hospitalization, depending upon whether cemented or cementless fixation is selected. The excellent long-term clinical data of cemented fixation and the cost of the implants clearly favor cemented fixation for total hip arthroplasty in the elderly patient.