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Two recent studies have shown decreased blood loss in patients given aprotinin undergoing primary hip replacement surgery. Because patients undergoing bilateral (bTHA) or revision total hip arthroplasty (rTHA) suffer more blood loss than those undergoing primary THA, we studied consecutive patients undergoing bTHA or rTHA who were randomized to receive either a blinded solution of 3.8 x 10(6) Kallikrein inactivation units (KIU) aprotinin (n = 29) or placebo (n = 24) throughout the surgical procedure. Total blood loss, measured as intraoperative suction losses, weight of sponges, and postoperative volumetric drainage, was compared between groups. Aprotinin patients had significantly less total blood loss 1498 +/- 110 mL (mean +/- SEM) versus 2096 +/- 223 (P = 0.022), and transfused patients in the aprotinin group received fewer packed red blood cells than placebo-treated patients (confidence interval for the difference -1.69, -0.07). In addition, assessment of biochemical markers of hepatic and renal function did not disclose any clinically important differences between groups. Patients were also assessed for development of deep venous thrombosis (DVT) by preoperative and predischarge bilateral lower limb compression ultrasound. None of the aprotinin-treated patients and three placebo-treated patients demonstrated DVT. Unless this trend for decreased DVT with aprotinin can be confirmed, it is questionable whether the slight reduction in blood loss justifies routine use of this expensive drug.

Medical management of patients having total knee arthroplasty (TKA) involves a pre-operative assessment, pre-operative optimization, and post-operative treatment. The pre-operative assessment is aimed to identify medical problems and determine risk profi le. Investigations are ordered specific to the patient and their medical history. Particular areas for concern are the cardiac, respiratory, neurological, and urinary systems. Pharmacotherapy in the peri-operative period involves stopping or holding some regular medications and prescribing prophylaxis against infection and thromboembolism. The medical management is often carried out by other physicians, but it is important for the orthopedic surgeon to be aware of, and involved, in the process. The aim of medical treatment is to reduce morbidity and mortality. Mortality for TKA has been reported to be 0.2–0.5%.

The first 100 consecutive Genesis II (SmithNephew; Memphis, Tenn) total knee replacements (TKR) procedures performed in 97 patients by the senior investigators (RBB, RSL) had a Kaplan-Meier survivorship of 96% +/- 2% at 12 years with any reoperation as the endpoint. Significant improvements in health-related quality-of-life outcome measures were noted. There were no revisions for implant-related factors (ie, polyethylene wear, osteolysis, or aseptic loosening). No implant demonstrated radiographic loosening. The features of this device are discussed as well as its long-term performance.

With the issues over the surgical treatment of the young osteoarthritic knee far from being resolved, the intellectual concepts associated with a mobile-bearing prosthesis are indeed attractive. The current challenges in knee prosthetic design are centered around attempting to produce normal kinematics, reducing wear and hence achieving greater longevity. Initially, it was hoped that mobile-bearing designs might go a long way toward achieving these aims. These hopes have yet to be borne out in practice.

Ideally, a total knee arthroplasty would mimic normal knee motion. Fluoroscopic studies have suggested a need for “guided motion” to provide a better approximation of normal knee kinematics. The development of the post-cam mechanism in posterior cruciate ligament-sacrificing designs of total knee arthroplasty is an attempt in this direction. Analysis has revealed that all post-cam mechanisms are not the same and that substantial differences exist from one implant type to another. Mikulak et al. have suggested that a substantial number of post-cam implants do not engage as designed. They have also raised the concept of rotational constraint leading to tibial post wear and the transmission of tibial rotational stresses to the modular interfaces (resulting in backside wear) and to the bone-implant interfaces (potentially resulting in loosening). The Puloski et al. study has also emphasized that post-cam mechanisms might result in increased wear debris and hence in negative outcomes such as osteolysis, aseptic loosening, and reactive synovitis. This group found more wear with varus/valgus constrained implants and advised caution with this design. They also described two tibial polyethylene posts that either fractured or were worn away, resulting in an unstable knee that required revision. This indicates that a post-cam mechanism cannot substitute for proper implant alignment and soft-tissue balancing. As we look into the future, the designers of future knee replacements that rely on a post-cam mechanism for guided motion within a total knee replacement must be aware of the surgical and design factors necessary to make this mechanism function properly.

Commonly, total hip prostheses have had a higher neck-shaft angle than the host bone and thus a tendency to reduce the femoral offset. Restoration of the femoral offset may be important as it has been shown to enhance hip stability and to improve the range and strength of abduction. The purpose of this study was to determine which of two designs was best able to restore femoral offset in comparison to the contralateral normal hip. Two hundred and two primary total hip patients were included in a radiographic study. Measurements were taken from a postoperative anteroposterior radiograph of the pelvis. The Synergy femoral component with a more varus neck-shaft angle of 131 degrees and a standard or high offset option tended to restore the femoral offset more reliably than did the Mallory-Head femoral component with a neck shaft angle of 135 degrees.

A prospective, randomized, blinded clinical trial was done to evaluate polyethylene versus metal bearing surfaces in total hip replacement. Forty-one patients were randomized to receive either a metal (23 patients) or a polyethylene (18 patients) insert. The femoral and acetabular components were identical with the acetabular insert the only variable. Patients were assessed preoperatively and postoperatively using radiographs, multiple outcome measures (Western Ontario MacMaster University Score, Harris hip score, Short Form-12), erythrocyte metal ion analysis (cobalt, chromium, titanium), and urine metal ion analysis (cobalt, chromium, titanium). Patients were followed up for a minimum of 2 years (mean 3.2 years; range, 2.2-3.9 years). There were no differences in radiographic outcomes or outcome measurement tools between patients. Patients receiving a metal-on-metal articulation had significantly elevated erythrocyte and urine metal ions compared with patients receiving a polyethylene insert. Patients who had metal-on-metal inserts had on average a 7.9-fold increase in erythrocyte cobalt, a 2.3-fold increase in erythrocyte chromium, a 1.7-fold increase in erythrocyte titanium, a 35.1-fold increase in urine cobalt, a 17.4-fold increase in urine chromium, and a 2.6-fold increase in urine titanium at 2 years followup. Patients receiving a polyethylene insert had no change in erythrocyte titanium, urine cobalt, or urine chromium and a 1.5-fold increase in erythrocyte cobalt, a 2.2-fold increase in erythrocyte chromium, and a 4.2-fold increase in urine titanium. Forty-one percent of patients receiving metal-on-metal articulations had increasing metal ion levels at the latest followup.

Cemented fixation of the femoral stem is the gold standard for patients older than 60 years. The importance of reliably achieving an adequate cement mantle has been shown in many studies. Currently, inspection and grading of plain radiographs is the accepted method for study of the cement mantle. However, the reliability of plain radiographs for this purpose has been questioned. In addition, the interobserver agreement of current grading systems has been shown to be limited. A new in vitro method of cement mantle analysis is described. Plastic replicas of six contemporary stems were implanted into femurs from cadavers. The specimens were imaged with a computed tomography scanner. Detailed, computer-assisted analysis of mantle thickness was done. Comparisons were made between designs. A subset was compared with standard radiographs. Plain radiographs overestimated thickness and underestimated the deficiencies. There was significant variability in the mantle produced by the different designs. Commonly used designs had deficiencies in their mantles by standard criteria despite proper surgical technique. The importance of being fully acquainted with the particular implant one uses is emphasized by these results. This is a valuable technique for investigation of the effects on the cement mantle of implant design, surgical technique, and patient anatomy.

The 10- to-13 year performance of 307 Mallory Head cementless tapered total hip replacements in 283 patients was assessed. Eighty-five percent of patients had a diagnosis of osteoarthritis. Fifty-one percent of patients were women. The mean patient age was 64 +/- 10 years. The Hex Loc cementless acetabular component and titanium alloy femoral heads were used in each patient. At final followup, 37 (13%) patients died, 32 (10%) had revision surgery, and two (1%) were lost to followup. No femoral stem was revised for aseptic loosening, but one was revised because of sepsis and one was revised because of a periprosthetic fracture. Wear, osteolysis, and loosening were problems with the Hex Loc cementless acetabular components and 31 (10%) acetabular components required revision because of these mechanisms. The mean Harris hip score at final followup of the remaining patients was 87 +/- 14 points. Three percent of these patients had thigh pain. Radiographic assessment revealed that no femoral stem or acetabular socket was definitely or probably loose. Three-dimensional wear assessment using the Devane technique was 0.35 mm per year. The Mallory Head cementless, tapered femoral component performed well in the patients in the current study, but unfortunately, the clinical results were compromised by the use of a suboptimal cementless acetabular component, the use of polyethylene that was gamma-irradiated in air, and by the use of titanium alloy femoral heads. Future developments obviously will be in the areas of better acetabular component design, alternate polyethylene sterilization methods, and enhancements of the femoral stem in terms of offset choices, neck design, and perhaps ingrowth surface.

To pilot a provincial joint replacement registry using electronic point-of-care data collection.Data collection study.Southwestern Ontario, which has a population base of 3.5 million people.Eighteen orthopedic surgeons.Information on total hip and knee replacements was obtained by the orthopedic surgeons over a 6-month period. Information was obtained in paper form and electronically on hand-held computers.Patient demographics, waiting times from referral to operation, patient satisfaction and relevance and value of electronic records compared with paper records.Data were collected on 815 total hip and knee arthroplasties. A slightly greater number of hips required revision than knees. The majority of patients were in the 60 to 90-year age range. With respect to the waiting time from referral to operation 10% of patients waited less than 5 weeks, 50% waited less than 30 weeks, and 90% waited less than 59 weeks. There was a high level of patient satisfaction with the operation and with hospital care received. Most surgeons found that the gathering and use of data electronically was relevant and easy. The electronic data were more timely, accurate and complete than paper records.Electronic point-of-care data collection is appropriate, particularly in high-volume, high-cost surgical interventions such as total joint replacements.

Femoral osteolysis is and will remain an important cause of THA failures. The presentation is initially radiographic and patients may or may not become symptomatic. If so, pain is the most common symptom. Infection is the most common differential diagnosis and must be excluded. Osteolysis is usually progressive and may eventually lead to loss of implant fixation, implant fracture, or periprosthetic fracture. Multiple factors influence the decision to revise a femoral component, including the degree and type of bone loss, the rate at which it is progressing, the potential for fracture, the degree of symptoms, especially pain, and the activity level and general health of the patient. There are many options for revising failed femoral stems, each with varying degrees of success. The choice of technique and prosthesis used in the revision can be guided by a simple bone defect classification presented in this chapter. Revision of femoral components in these patients can be fraught with complications and poor results; hence, the importance of preoperative planning cannot be overemphasized.

In summary, if TKRs are to be performed in patients who are younger and more active than those who had the initial procedures in the 1970s and 1980s, better wear performance is imperative for long-term durability, especially if surgeons continue to consider the versatility associated with modular knee-replacement systems to be a necessity. At least with some designs, including the Oxford knee and the LCS knee, the results after a minimum follow-up of 10 years are comparable with the best results after arthroplasty with fixed-bearing designs in terms of wear, loosening, and osteolysis (Table 7). As with fixed-bearing designs, there are additional challenges in terms of optimizing bearing-surface conformity and improving kinematics. Improvements in future designs of mobile-bearing total knee replacements should include better control of bearing mobility patterns to reduce the prevalence of the abnormal kinematic motions that have been observed in fluoroscopic evaluations.

The results of 106 high tibial valgus osteotomies in 85 patients were evaluated after a minimum 10-year followup to determine survivorship, complications, and risk factors associated with failure. Using Kaplan-Meier survivorship analysis, 73% of patients at 5 years, 51% of patients at 10 years, 39% at 15 years, and 30% at 20 years after high tibial osteotomy had not required conversion of the high tibial osteotomy to a total knee arthroplasty. Univariate Cox regression analysis of risk factors showed that age older than 50 years, previous arthroscopic debridement, presence of a lateral tibial thrust, preoperative knee flexion less than 120 degrees, insufficient valgus correction, and development of delayed union or nonunion were significantly associated with probability of early failure. Multivariate Cox regression analysis showed that a body mass index of less than 25 kg/m2, presence of a lateral tibial thrust, and development of delayed union or nonunion were significantly associated with probability of early failure. Using recursive partitioning analysis of risk factors with the Wilcoxon test, a subset of patients who were younger than 50 years of age and who had preoperative knee flexion greater than 120 degrees had a probability of survival after high tibial osteotomy approaching 95% at 5 years, 80% at 10 years, and 60% at 15 years. These results suggest that survival of high tibial osteotomy can be improved through careful patient selection and surgical technique.

Mobile bearing total knee arthroplasty kinematically allows the advantages of large and congruent surface contact and low contact pressures, while preserving flexion, extension, and rotation in knee motion. In allowing for these degrees of freedom, the interface between bone and component also is protected from high stress. The Self Aligning I total knee arthroplasty initially was implanted in patients after its development at the authors' institution in 1990. Between 1990 and 1994, 141 patients with osteoarthritis of the knee underwent 172 total knee replacements using this system. At average followup of 5.6 years (range, 5-8 years), clinical results using this system showed a 94% satisfaction rate (good or very good). Two revision surgeries have been performed for polyethylene wear, with none of the remaining knees showing evidence of discernible wear. Complications included four cases of deep infection, four cases where a press fit femoral component failed (nonporous coated) and the patients required revision surgery, four traumatic fractures (three patellar and one supracondylar), one popliteal artery occlusion, and one revision for stiffness. Three patients required manipulation under anesthesia for arthrofibrosis. Kaplan-Meier survival curves show the probability of survival to be 91.7%, with revision surgery for any reason as an end point, and 98.8% for revision surgery because of polyethylene wear as an end point. Following the initial learning curve with this prosthesis, the medium term results using this system show maintenance of clinical success. No progressive evidence of polyethylene wear with time has been found, supporting the concept of mobile bearing arthroplasty in extending the service life of total knee arthroplasty.

The clinical and radiographic efficacy of cementless taper design femoral components in total hip arthroplasty was determined. Cementless, taper design, femoral components have been shown to offer comparable clinical results to cemented femoral implants in a double blind, randomized, clinical trial. No differences were observed in terms of disease specific, patient specific, global health, functional capacity, or cost to utility outcome measures. The prevalence of pain in the thigh was the same in each group. Fixation of cementless, taper design, femoral stems depended on three-point fixation as shown on lateral radiographs. A clinical algorithm for femoral stem selection, based on more than 10 years experience with more than 1000 cementless, taper design femoral stems has been developed. Cementless, taper design, femoral implants currently are used in 75% of the authors' patients, provided they are younger than 75 years of age and have funnel shaped proximal femoral medullary canals. Cemented femoral stems are used in older patients, those who have cylindric medullary canals, and those who have inflammatory or unusual bone diseases (Paget's disease, previously irradiated bone).

We reviewed the results of 172 plasma-sprayed, titanium primary total hip arthroplasties inserted without cement and followed 5 to 7 years. Hips were replaced for a wide range of diagnoses and patient ages. No femoral components had been revised nor were considered unstable. Clinical results have been excellent; 88% of hips had either no or a slight amount of pain and only 5% of patients had thigh pain when specifically asked. Radiographically, this femoral component achieved stability after an initial subsidence in 9% of cases. Extensive femoral bone resorption was rare, and distal cortical hypertrophy was commonly seen. Pelvic osteolysis occurred in 16 (9%) cases and was considered major in 10 of these. It was the cause of failure of 3 acetabular components. Femoral endosteal lysis was not observed. We concluded that mechanical stability of the Mallory-Head titanium total hip prostheses is excellent. However, significant pelvic osteolysis has occurred commonly with this implant design, and will continue to pose major reconstructive problems in the future.

To examine the necessity and cost-effectiveness of interpretation by radiologists of orthopedic radiographs obtained for patients who undergo total hip or knee replacement.A prospective study. Serial preoperative and postoperative x-ray films of the joint in patients scheduled to undergo total hip or knee joint replacement during one calendar year were interpreted by both radiology and orthopedic department staff and compared. Intraoperative findings were used to confirm the radiologic interpretation. The follow-up was 1 year.A university teaching hospital.Primary or revision total hip or knee replacement.Differences in interpretation of radiographs by radiologists and orthopedic surgeons for any of the four procedures. A change in orthopedic management.For preoperative radiographs, there were no discrepancies between the radiologists and orthopedic surgeons with respect to primary joint replacement. For 100 revision procedures there were 15 discrepancies, but in all cases the orthopedic surgeon's interpretation proved to be correct. For the postoperative radiographs, there were no discrepancies in the group of revision hip replacements. For the other three groups there were a total of six discrepancies and in all cases the orthopedic surgeon's interpretation was correct. In two cases conditions were present that were not recognized by staff from either the radiology department or orthopedic department.Interpretation by radiologists of total joint radiographs in patients who undergo primary or revision total hip or knee replacement arthroplasty is not necessary or cost-effective.

A prospective randomized clinical trial comparing cemented to cementless total hip arthroplasty has been ongoing at the author's institution since 1987. All parameters assessed showed that there was no statistically significant difference in any of the health related quality of life measures used when patients with cement were compared with patients without cement at any of the followup periods as many as 4 years later. The improvement was dramatic and sustained. No components (cemented or cementless) have been revised to date (average, 4.8 years). A radiographic analysis showed probable loosening of the cemented socket in 24% and presumed minimal pelvic osteolysis in 8%. The cementless sockets showed a greater frequency and severity of pelvic osteolysis (14%). The cemented femoral component was judged to be possibly loose in 10%; however, none were considered probably loose. The patients who had cementless femoral components were doing extremely well with the components showing very little subsidence or proximal stress protection noted. Osteolysis on the femoral side was not seen in any of the cementless stems. Total hip replacement gives comparable clinical results when health related quality of life measures are analyzed; however, metal backed cemented acetabular components have a high rate of radiographic failure. Short-term stability of a non-cemented porous coated titanium stem, however, gave excellent clinical and radiographic results.

A comparative radiographic review of 217 cementless total knee replacements was done 4 years after surgery to look for radiographic change at the screw-bone interface. There were 102 Miller Galante I knee prostheses, 59 Miller Galante II prostheses, and 56 Anatomic Modular Knee prostheses studied. If the appearance of the screw-bone interface had changed, this was classified according to the width of the lucency. Two hundred sixty-five of the 851 screws that were studied showed some evidence of change, with 185 (21.7%) of the screws showing a cavitary appearance change. The AMK prosthesis showed the higher incidence of cystic and cavitary changes. Polyethylene debris is thought to be responsible for generation of osteolysis and the radiographic appearance change. Design of the components and particularly the polyethylene attachment mechanisms may be responsible for the differences in the frequencies of osteolysis.

One hundred eighty-five total knee revisions were done by the 2 senior authors from 1988 to 1994. Of these, 17 patients were identified as having severe osteolysis. The average age was 62.7 years, and the average weight was 90.8 g. All patients had osteoarthritis. Preoperative aspiration was negative in all patients. Eight patients had a metal-backed patella, 8 had a cementless implant, 4 had a cemented implant, and 5 had a hybrid implant. The average time interval from the index surgery to radiographic evidence of lysis was 56 months. Radiographic review showed gross polyethylene wear in 10 patients, loose tibial implants in 8, fractured baseplates in 2, and evidence of a metallic synovitis in 2. Retrieved polyethylene liners had a average thickness of 7 mm, and none were conforming. Osteolytic defects were defined and classified according to Engh's criteria. The histology showed a foreign body reaction with intracellular refractile polyethylene particles. Four cases had metallic debris. The exposure at the time of revision required a rectus snip in 4, V-Y-quadricepsplasty in 2, and tibial tubercle osteotomy in 1. Posterior stabilized implants were used in 65% and a constrained implant in 30%. Lytic defects were reconstructed with cement only in 47% of knees, allograft in 30%, and metallic wedges in 35%. Based on this report, the authors conclude that younger, overweight patients seem to be at higher risk of implant failure and that osteolysis is not restricted to cementless implants. Furthermore, because review of the radiographs leads to a constant underestimation of the lytic defect, the surgeon must be prepared to deal with complex revisions.

One hundred patients with osteoarthritic knees were randomized either to have their patella resurfaced or not resurfaced using the same total knee replacement. These patients were assessed preoperatively and a minimum 2 years postoperatively using disease-specific (Knee Society Clinical Rating System) and functional capacity (30 second stair climbing and knee flexor and extensor torques) outcome measures. Two patients in the not resurfaced group required reoperation because of anterior knee pain. At 2 years' followup, the not resurfaced group had significantly less pain and better knee flexor torques than did the resurfaced group, whereas the results of the Knee Society Function Scores, 30 second stair climbing, and knee extensor torques were similar. These results suggest that longer-term followup is required, but that one should keep an open mind regarding patellar resurfacing during total knee replacement.

A new technique, the 3-dimensional technique, has been developed. Using a digitzer, points taken from anteroposterior and lateral radiographs are input into a personal computer. A 3-dimensional solid model of the prosthesis is created using custom software. Tilt and anteversion of the acetabular cup are measured, and the model is rotated to a standard frontal view, allowing measurement of femoral head displacement from the center of the acetabular cup. Comparing serial radiographs of the same patient gives the direction and distance of femoral head displacement over time, and this value is used to calculate the minimum volume of polyethylene debris generated. The 3-dimensional technique has been validated by construction of a precision acrylic phantom, and milling of a metal-backed acetabular cup to simulate polyethylene wear. Three-dimensional measurement of femoral head displacement using this technique has an accuracy of +/- 0.15 mm, and volume calculations are within 8% of the true amount of polyethylene removed from the cup. The 3-dimensional technique gives previously unavailable information, and can be used for clinical evaluation of polyethylene wear and evaluation of new prosthetic designs and bearing surfaces.

The new 3-dimensional technique was applied to the radiographs of 141 patients who had received Porous Coated Anatomic total hip prostheses. Values were obtained for the position of the acetabular cup, the 3-dimensional distance and direction of femoral head displacement, and the minimum volume of polyethylene debris produced. Mean age of the patients at the time of replacement was 61 years old; mean followup was 5.6 years (range, 4-7.2 years). Change in the position of the femoral head between initial and long-term followup films was assumed to represent polyethylene wear, and formulas were used to calculate the minimal volume of polyethylene debris produced. The overall rate of 3-dimensional femoral head displacement was 0.264 mm per year, almost twice that usually quoted in the current literature for 2-dimensional linear wear. A significant contribution to this value was made by anterior and posterior displacement. Two-dimensional femoral head displacement (measured in the plane of anteroposterior radiographs) on the same patients was 0.149 mm per year. The mean minimum volume of polyethylene debris produced after 5.6 years was 0.448 cm3 (range, 0.00-2.83 cm3), giving a mean rate of 0.079 cm3 polyethylene debris produced each year. Thirteen patients in this series had radiologic osteolysis and a significantly greater femoral head displacement and polyethylene volumetric wear than those with no osteolysis. Patients with a 32-mm femoral head diameter and a polyethylene linear1 cm thick had a significantly greater amount of polyethylene wear. This series gives previously unavailable data on 3-dimensional femoral head displacement and is the first report that correlates the minimum volume of polyethylene wear produced with radiologic osteolysis.

Both noncemented fixation and improved cemented fixation of total hip replacements emerged to counteract the clinical and radiographic failures of early cemented procedures. A randomized clinical trial comparing a second-generation cemented with a second-generation noncemented total hip replacement demonstrated that in the medium term both implants allow excellent, disease-specific, global and functional capacity outcome measures. No significant differences existed between the cemented and noncemented implants in terms of these parameters or revision rate. Cost-to-utility analyses of both types of replacements revealed that total hip replacement is one of the most cost-effective medical interventions. Noncemented total hip replacements seem as efficacious as cemented devices in patients younger than 70 years.

Randomization is the best method of obtaining comparable groups in clinical trials, yet it is seldom used to compare one surgical treatment with another. The use of historic controls or unblinded randomization can lead to bias in selection and to questionable outcome results. The publication of clinical studies that are unblinded and not randomized should be questioned.

We performed a study to determine the prevalence, severity, and natural history of pain in the thigh in patients who had a total hip replacement with a porous-coated anatomic prosthesis and to determine if there was an association between the radiographic findings and the pain in the thigh. We previously reported the results in these patients two years after the operation. The present study included ninety-four patients (101 total hip replacements) who had been followed for a minimum of five years--six of the original group of patients had died from unrelated causes, two had had a revision, and one had been lost to follow-up. The patients were assessed prospectively with use of the Harris hip score and a visual-analog scale for pain in the thigh. Two of us, who were blinded to the clinical result, reviewed the radiographs retrospectively for the morphology of the proximal aspect of the femur; distal fit; metaphyseal fill; alignment of the stem; shedding of beads; distal cortical hypertrophy; pedestal formation; cancellous condensations at the distal end of the porous ingrowth surface; and the presence, extent, and location of radiolucent lines around the femoral component. At five years, pain in the thigh was found in association with twenty-seven hips (27 per cent). The pain was new in fourteen thighs (14 per cent), unchanged (from that at the two-year follow-up examination) in eight (8 per cent), increased in four (4 per cent), and decreased in one (1 per cent). Pain in the thigh was most strongly associated with a poor Harris hip score and the presence of loose beads.

This report details 16 cases of focal posteromedial tibial polyethylene wear and failure after total knee arthroplasty. This wear phenomenon was associated with an external rotatory subluxation of the tibial component relative to the femoral component. Failure occurred in ten Miller Galante 1, three Porous Coated Anatomic, two Kinematic, and one Press-Fit Condylar knee designs at a mean time of 45 months from their implantation. With this type of failure, there did not seem to be a relationship with metal type, fixation, polyethylene manufacturing method, or polyethylene thickness. A relatively flat design of the tibial articular surface was common to all of these components. In certain patients this articular design may allow excessive component translation, which leads to polyethylene deformity, wear, and subluxation. Some methods for preventing this failure mode are reported here.

Arthroplasty is now an important and frequently performed orthopedic procedure. This article focuses on the imaging of abnormalities frequently encountered in patients who have undergone arthroplasty. The emphasis is on plain film analysis, although arthrography, computed tomography and nuclear medicine are also discussed. Among the problems illustrated are loosening of the prosthesis, component fatigue or failure, and infection. The authors recommend techniques to optimize imaging. Although most of the entities illustrated involve hip arthroplasty, the principles are valid for arthroplasty at other sites.

One hundred consecutive primary total knee arthroplasties performed by a single surgeon were prospectively randomized into two groups to study the effect of tourniquet release for hemostasis on postoperative blood loss and transfusion requirements. The two groups were comparable. Variables such as antiinflammatory drug use; anesthetic; soft-tissue release; and component fixation were analyzed. There was no significant difference between the groups in terms of perioperative blood loss, decrease in hemoglobin or hematocrit level, transfusion need, or incidence of wound or thromboembolic complications. Tourniquet release for hemostasis is not an effective means of limiting postoperative blood loss or reducing transfusion need after primary total knee arthroplasty.

Plasma spray coatings on titanium alloy total hip replacements (THRs) provide a viable alternative to sintered bead or diffusion-bonded fiber metal ingrowth surfaces. The plasma spray process enables the titanium alloy implant to retain 90% of its fatigue strength, as opposed to less than 50% for sintered or diffusion-bonded cementless devices. Laboratory and clinical evidence suggest that plasma spray cementless THRs perform as well, if not better, than other cementless implants. Clinical trials have demonstrated the superiority of a plasma spray cementless THR (Mallory-Head) over a sintered bead cementless THR (PCA) and the equivalent results to a cemented THR. Plasma spray coatings on titanium alloy hip replacements provide a safe, predictable coating for cementless fixation of THRs in the short to medium range of follow-up periods.

The success of a total hip arthroplasty (THA) is dependent on many more parameters than simply the prosthesis used. This study has demonstrated that a randomized controlled clinical trial of 250 patients comparing two types of hip prostheses (cemented versus cementless) with virtually complete follow-up examination is feasible. It also demonstrates that patients are willing to answer extensive quality-of-life questionnaires that allow complete assessment of the impact of hip arthroplasty on the patient's overall health-related quality of life. This study has also demonstrated that THA is an extremely effective intervention when one assesses its ability to impact on patients health-related quality of life with no difference between cement versus cementless at two years' follow-up examination.

Cementless total hip arthroplasties using 110 porous-coated anatomic (PCA) and 105 consecutive Mallory-Head (MH) prostheses were reviewed using prospectively gathered clinical data and a detailed radiographic analysis. In an earlier experience with the PCA, 13% of patients experienced thigh pain at 1 year and 23% at 2 years. Positive radiographic correlates with thigh pain included subsidence, distal cortical hypertrophy, a tight diaphyseal fit, and stem tip sclerosis. In the current MH study group, the incidence of thigh pain was 7% at 1 year and 3% at 2 years. No radiographic findings correlated positively with thigh pain. The results of this short-term clinical comparison suggest that a long, straight, tapered design offered better initial stability than its anatomic counterpart as reflected in the much lower incidence of thigh pain. These results may translate into improved osseous integration and long-term success.

In a group of patients who underwent total hip arthroplasty because of rheumatoid arthritis, the outcome in 42 hips was assessed. There were 17 cemented and 25 uncemented prostheses. The average follow-up was 5 years for cemented prostheses and 3 years for uncemented prostheses. The average Harris hip scores were similar in the two groups (84 and 86 respectively). Radiologically, the incidence of migration of femoral and acetabular components was similar in the two groups. Component migration was not affected by component fixation. Uncemented implants may have a role in hip arthroplasty in patients with rheumatoid arthritis.

Thirty-one patients with avascular necrosis of the hip were treated by 34 total hip arthroplasties (THAs). All patients were observed prospectively with a minimum two-year follow-up evaluation (average, 46 months; range, 24-84 months). Twenty had cemented arthroplasties using contemporary cementing techniques. This included insertion of a medullary plug, cleansing of the canal with a medullary brush, pulsatile lavage irrigation, and insertion of the cement with a cement gun. In 14 hips, a cementless prosthesis was used. Patients were rated using a modified Harris hip score. Sequential postoperative roentgenograms were analyzed in each patient. The overall Harris hip score ratings were 88 in the cemented and 84 in the noncemented groups. Mechanical failure with loosening of the femoral component occurred in one patient who developed deep sepsis. Significant thigh pain occurred in four patients in the noncemented group. Previous studies in the literature have generally reported unfavorable results in patients with avascular necrosis of the hip treated with THA. Using cementless and cemented fixation with contemporary cementing techniques, improved results can be expected. A high incidence of thigh pain (29%) in the cementless group remains a problem.

An in vitro model has been developed to measure in-plane strains of the cement mantle, sandwiched between the tibial component and the underlying cancellous bone following total knee arthroplasty. Maximal in-plane strains occurred in the cement mantle below the contact points between the femoral and tibial components. These strains were significantly reduced by increasing the thickness of the polyethylene and even more impressively by metal backing. Eccentric loading, by as little as 5°, increased the strains in the loaded compartment by 26 per cent and decreased those in the unloaded compartment by 62 per cent. The addition of torsion to axial loading did not significantly alter the principal direct strains or the principal shear strains. Although surface-covering tibial components have been advocated, continuous support of the cortical rim did not appear to be important in reducing cement mantle strains. While other studies have emphasized the critical stresses that may occur in the polyethylene tibial components of total knee implants, this study highlights the potential for localized cement fatigue with improperly sized components or with eccentric loading.

A technique of posterior cervical spine fusion (the "Dewar procedure") that allows immediate stabilization of the spine requiring only minimal external support is described. The procedure was performed in 16 patients with unstable fractures or fracture-dislocations of the cervical spine. All patients went on to develop solid fusion. Twelve patients incurred neurologic deficit due to their injury, and those with root involvement all recovered following fusion. Patients rendered quadriplegic as a result of their accident did not show any useful neurologic recovery but were able to start rehabilitation earlier and avoid the complications of nonoperative treatment. There were no significant complications related to surgery.

We studied the cases of twelve patients who had bilateral exertional compartment syndrome involving one or all of the compartments of the lower extremities. The patients were divided into three groups based on the clinical findings. Group I consisted of seven patients with symptoms involving the anterior or lateral compartments only; Group II, of three patients with involvement of the deep posterior compartments alone; and Group III, of two patients with involvement of both the anterior and deep posterior compartments. On the basis of their clinical signs and symptoms each patient underwent dynamic tissue-pressure measurements using a slit catheter before, during, and for as long as thirty minutes after exercise. All patients had elevated resting and peak-to-peak dynamic pressure measurements. Treatment consisted of bilateral compartmental fasciotomy, as indicated. All of the patients in Group I had complete relief of symptoms; however, one patient in Group II and one in Group III had a recurrence of symptoms in the deep posterior compartment.