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Background: In the mid- to late 1970s, on the basis of laboratory and finite element data, many surgeons in the United States began using collared matte-finish femoral components and metal-backed acetabular components in their total hip arthroplasties. The purpose of this study was to evaluate the long-term results of the use of one such construct in arthroplasties performed by a single surgeon in a consecutive nonselected patient cohort.Methods: Between January 1984 and December 1985, 273 patients underwent a total of 304 consecutive nonselected total hip arthroplasties with cement and use of the Iowa femoral component (which is collared, has a proximal cobra shape, and has a matte finish) and a metal-backed TiBac acetabular component performed by a single surgeon. At nineteen to twenty years postoperatively, only two patients (two hips) were lost to follow-up. For clinical evaluation, we attempted to interview all living patients and the families of the patients who had died to verify the status of the hip prosthesis or any revisions. Radiographic evaluation consisted of analysis for loosening and osteolysis as well as wear of the acetabular component.Results: At the time of the nineteen to twenty-year follow-up, the rate of revision of the arthroplasty for any reason was 10.5% (thirty-two hips) for all patients and 25% (twenty-three hips) for living patients. The rate of revision due to aseptic femoral loosening was 2.6% (eight hips). There was radiographic evidence of loosening of the femoral component in fifteen hips (4.9%), including those that were revised, and femoral osteolysis was seen distal to the trochanters in twenty-two hips (7.2%). The rate of revision due to aseptic loosening of the acetabular component was 7.9% (twenty-four hips), and there was radiographic evidence of acetabular loosening in forty-two hips (13.8%), including those that were revised.Conclusions: This study demonstrates the durability of a cemented matte-finish collared femoral component at twenty years postoperatively, with a rate of revision due to aseptic loosening of 2.6%. The metal-backed acetabular component also performed well in many patients, with a 7.9% rate of revision due to aseptic loosening. However, in the living patients, the rate of loosening of the acetabular component, including cases revised because of aseptic loosening, was 30.4%. [ABSTRACT FROM AUTHOR]

Third-body effects are a major cause of the substantial variability of wear in total hip replacements. One potential mechanism by which third-body debris can access wear-critical central regions of closely conforming metal-on-polyethylene bearing couples is by fluid convection during incidents of subluxation accompanying neck-on-liner impingement. To provide evidence for this premise, we determined the association of severity of liner rim indentation damage (indicative of impingement frequency/vigor) and the presence of embedded third-body debris in 194 implants retrieved at revision. Rim damage was graded using the five-point Hospital for Special Surgery scale. Particle embedment was assessed both manually and by means of an image analysis computer program that detected the composition, size, and location of each particle. Sixty-eight percent of the cups showed rim indentation damage. We found an association between severity of rim damage and presence of embedded debris. There was substantial nonuniformity of the spatial distribution of the embedded debris, with the predominance of embedded debris at intermediate latitudes. These findings support the premise of convection of debris-laden joint fluid during lever-out subluxation as a mechanism for wear-consequential third-body particles to gain access to highly loaded regions of the bearing surface, thus potentiating increased wear. [ABSTRACT FROM AUTHOR]

We previously evaluated 119 consecutive total knee arthroplasties that were performed in eighty-six patients with use of the cemented LCS (low contact stress) rotating-platform system with an all-polyethylene patellar component. The average age of the patients at the time of surgery was seventy years (range, thirty-seven to eighty-eight years). The purpose of this study was to report the updated results at a minimum follow-up of fifteen years. Thirty-seven patients (fifty-three knees) were living, and no patient was lost to follow-up. No knee was revised because of loosening, osteolysis, or wear. Three knees required a reoperation (two for periprosthetic fractures and one for infection). No component was revised as a part of the reoperations. Osteolysis was present in three knees. No knee had radiographic signs of component loosening, and there were no dislocated bearings. The average range of motion was from 1 degrees of extension to 105 degrees of flexion. The average clinical and functional Knee Society scores were 43 and 49, respectively, at the preoperative evaluation and 85 and 58 at the time of the final follow-up. We concluded that the cemented LCS rotating-platform knee performed well, with durable clinical and radiographic results at a minimum follow-up of fifteen years. [ABSTRACT FROM AUTHOR]

Exposure of marine invertebrates to high temperatures leads to a switch from aerobic to anaerobic metabolism, a drop in the cellular ATP concentration ([ATP]), and subsequent death. In mammals, AMP-activated protein kinase (AMPK) is a major regulator of cellular [ATP] and activates ATP-producing pathways, while inhibiting ATP-consuming pathways. We hypothesized that temperature stress in marine invertebrates activates AMPK to provide adequate concentrations of ATP at increased but sublethal temperatures and that AMPK consequently can serve as a stress indicator (similar to heat shock proteins, HSPs). We tested these hypotheses through two experiments with the rock crab, Cancer irroratus. First, crabs were exposed to a progressive temperature increase (6 degrees C h(-1)) from 12 to 30 degrees C. AMPK activity, total AMPK protein and HSP70 levels, reaction time, heart rate and lactate accumulation were measured in hearts at 2 degrees C increments. AMPK activity remained constant between 12 and 18 degrees C, but increased up to 9.1(+/-1.5)-fold between 18 and 30 degrees C. The crabs' reaction time also decreased above 18 degrees C. By contrast, HSP70 (total and inducible) and total AMPK protein expression levels did not vary significantly over this temperature range. Second, crabs were exposed for up to 6 h to the sublethal temperature of 26 degrees C. This prolonged exposure led to a constant elevation of AMPK activity and levels of HSP70 mRNA. AMPK mRNA continuously increased, indicating an additional response in gene expression. We conclude that AMPK is an earlier indicator of temperature stress in rock crabs than HSP70, especially during the initial response to high temperatures. We discuss the temperature-dependent increase in AMPK activity in the context of Shelford's law of tolerance. Specifically, we describe AMPK activity as a cellular marker that indicates a thermal threshold, called the pejus temperature, T(p). At T(p) the animals leave their optimum range and enter a temperature range with a limited aerobic scope for exercise. This T(p) is reached periodically during annual temperature fluctuations and has higher biological significance than earlier described critical temperatures, at which the animals switch to anaerobic metabolism and HSP expression is induced.

We asked, "What are the quantitative variances in sagittal femoral bowing in patients who were indicated for total knee arthroplasty?" We retrospectively evaluated 145 consecutive patients who underwent 166 primary total knee arthroplasties with adequate preoperative nonrotated sagittal plane full-leg lateral radiographs. Digital radiographs were processed such that each femoral shaft was divided into three segments. A purpose-written program determined the flexion/extension of the femoral component using the Knee Society method of focusing on the distal femur and a second method using the whole femur. The median angle of curvature of the proximal, middle, and distal thirds of the femora were 5.4 degrees, 0.2 degree, and 3.1 degrees, respectively, with the largest bow occurring in the proximal segment followed by the distal segment and with the least bow in the middle segment. The median angles for femoral component flexion were considerably different with the whole femur angle showing more flexion (4 degrees) than that of the Knee Society angle (1.421 degrees). We found an inverse relationship between distal angle of curvature and height as well as weight. Men had greater proximal bowing and less distal bowing than women. The effects of these variances may have implications in development of osteoarthritis and total knee arthroplasty component survival.

We sought to determine if acetabular cages prevented rerevision and loosening in acetabular reconstructions in the setting of pelvic discontinuity. We followed 15 patients with 16 acetabular cage reconstructions for an average 5 years (range, 2-8 years). Acetabular classifications included two Type 2C, six Type IIIA, and eight Type IIIB. We assessed Merle d'Aubigné scores, rerevisions, radiographic loosening, and complications. We treated seven patients with structural allograft and six patients with cancellous allograft. Five hips (31%) were revised or resected because of aseptic loosening (4 hips) and sepsis (1 hip) at an average 46 months. Three additional hips were loose. Merle d'Aubigné scores for pain and walking increased from 3.7 points preoperatively to 6.8 points at the final followup. Complications included one infection, four nerve palsies, and one dislocation. Acetabular cages in the setting of pelvic discontinuity were associated with a high failure rate at intermediate-term followup.

The management of bone loss encountered during acetabular revision remains challenging. In order to obtain a successful surgical result, preoperative planning is required to estimate the severity and location of bone defects. Most acetabular revisions can be treated with the use of a cementless hemispherical component. However, a successful surgical reconstruction requires component stability. Depending on the degree of bone loss, the surgical reconstruction may require the use of cancellous or structural bone graft, acetabular augmentation, an acetabular cage, a custom implant, or an acetabular transplant.

Unlabelled: We report the results of a minimum 21-year followup of a consecutive series of 103 patients who had 136 Marmor cemented unicompartmental knee replacements done between 1975 and 1982. Patients were evaluated clinically and radiographically. At minimum 21-year followup 14 patients (19 knees) were alive, 87 patients (115 knees) had died, and only two patients (two knees) were lost to followup. The average age at surgery was 70.9 years. The average followup Hospital for Special Surgery knee score was 58. The average Knee Society final followup clinical and functional scores averaged 72 and 53 points, respectively. Nineteen knees (14%) were revised during the 21-year followup period: nine for progression of disease, eight for loosening, and two for pain, at an average of 10.6 years (range, 1-22 years). Of the 19 knees in the 14 patients who were still alive at final followup, seven (37%) were revised: two for tibial loosening, four for disease progression, and one for pain. Unicompartmental knee replacements in this relatively older age group of patients performed well at minimum 21-year followup. Although we are encouraged by these results, only 22% were done in patients who were younger than 65 years at the time of surgery and the results in this group were significantly less durable., Level of Evidence: Therapeutic study, Level IV-1 (case series). See the Guidelines for Authors for a complete description of levels of evidence.

The goal of revision total knee arthroplasty is to restore the anatomical alignment of the knee and to provide a stable joint. Joint stability is obtained by balancing the various knee ligaments remaining at the time of revision surgery and by using an implant with added stability if necessary. Understanding the limits of the various designs available (cruciate retaining, cruciate substituting, valgus-varus constraining, and linked) should help the surgeon construct a stable and durable construct.

Blood management in the perioperative period of the total joint arthroplasty procedure has evolved over the last 3 decades. Strategies have changed and are changing based on a better understanding of blood loss and blood replacement options in this patient population. Patient-specific options based on preoperative hemoglobin levels and patient comorbidities as well as anticipated blood loss have been developed and studied. Patient-specific blood management programs have provided cost-efficient care with low morbidity.

Constrained acetabular components have been used to treat certain cases of intraoperative instability and postoperative dislocation after total hip arthroplasty. We report our experience with a tripolar constrained component used in these situations since 1988. The outcomes of the cases where this component was used were analyzed for component failure, component loosening, and osteolysis. At average 10-year followup, for cases treated for intraoperative instability (2 cases) or postoperative dislocation (4 cases), the component failure rate was 6% (6 of 101 hips in 5 patients). For cases where the constrained liner was cemented into a fixed cementless acetabular shell, the failure rate was 7% (2 of 31 hips in 2 patients) at 3.9-year average followup. Use of a constrained liner was not associated with an increased osteolysis or aseptic loosening rate. This tripolar constrained acetabular liner provided total hip arthroplasty construct stability in most cases in which it was used for intraoperative instability or postoperative dislocation.

Although low-molecular-weight heparin (LMWH) is a widely used form of thromboprophylaxis in orthopedic surgery, concerns remain over the concomitant use of regional anesthesia (RA)/postoperative regional analgesia (PRA) stemming from reports in the 1990s of spinal hematoma associated with this combination. One of the objectives of the Second American Society of Regional Anesthesia (ASRA) Consensus Conference was to address the safety of LMWH in combination with neuraxial anesthesia. The guidelines are designed in part to help orthopedic surgeons already using or contemplating the use of LMWH prophylaxis to avoid or minimize potential complications arising from its use with RA/PRA. Clinicians should consult the ASRA guidelines for recommendations on total daily dose, timing of the first postoperative dose, and dose schedule for anticoagulants used in conjunction with RA/PRA.

The cementless acetabular components used over the past 2 decades have varied in type of ingrowth fixation, supplemental fixation, locking mechanisms, and bearing surface. We evaluated 15-year follow-up results from 2 cementless acetabular components: the Harris-Galante I (HG; Zimmer, Warsaw, IN) and the PCA (Howmedica, Rutherford, NJ), in terms of revision and radiographic loosening. Three of the 120 HG I acetabular components were revised for wear and osteolysis without loosening. Seventeen of the 100 PCA components were revised for aseptic loosening (with or without osteolysis). Including those cases revised, 21 PCA acetabular components were loose radiographically, and no HG I component was loose. At least with these 2 first-generation designs, differences were seen in performance of the acetabular component in terms of revision and loosening at 15 years.

This article reviews the changing modes of failure in total knee arthroplasty over the past decade. Reasons for failure include polyethylene wear, aseptic loosening, instability, infection, arthrofibrosis, malalignment, or malposition, deficient extensor mechanism, periprosthetic fracture, and isolated patellar resurfacing. Awareness of the modes of failure may lower the prevalence of failure and aid in developing designs and techniques to better address the problems.

Bone loss is a challenging problem with complex acetabular revisions. With an adequate biologic and mechanical environment, uncemented hemispheric component reconstructions have provided long-term durable results for acetabular revisions. Decisions about reconstructive options can be made with the aid of a classification system that addresses the location and severity of bone loss as it relates to achieving the prerequisites for biologic fixation with a hemispheric component. Structural allograft may be used to provide a mechanical environment that supports host bone ingrowth into an acetabular component. Alternatively, structural allograft may allow restoration of joint mechanics in situations where host bone loss precluded biologic fixation. We describe the indications and technique for the use of structural allograft in revision acetabular surgery.

Reports of posterior-stabilized total knee replacements have shown excellent clinical success. However, tibial post-femoral cam impingement has been seen in modular component retrievals. This finding has been associated with transmission of rotational forces to the modular tray-polyethylene interface with subsequent backside polyethylene wear and the development of osteolysis. Femoral cam-tibial post designs that allow hyperextension and limit rotational constraint may minimize this impingement. Technical considerations including the avoidance of femoral component flexion and posterior tibial slope will minimize anterior tibial post impingement.

Background: Most intermediate and long-term studies of cemented posterior-cruciate-substituting total knee prostheses were performed with nonmodular tibial components. The purpose of this study was to evaluate the intermediate-term results of posterior-cruciate-substituting total knee arthroplasties in which a cemented modular tibial component had been used, with a particular focus on evaluating the prevalence of radiographic osteolysis., Methods: Between 1992 and 1995, 176 consecutive primary total knee arthroplasties with use of the Insall-Burstein II system were performed in 134 patients at our institution. A modular metal-backed tibial component was inserted in 145 knees, and an all-polyethylene tibial component of the same design was inserted in thirty-one. Standard-terminology questionnaires were completed or Knee Society and The Hospital for Special Surgery scores were determined preoperatively and at the time of final follow-up, at an average of 6.4 years (range, 5.0 to 7.9 years). Initial postoperative radiographs were compared with those made at the time of final follow-up to assess component position, wear, radiolucent lines, and osteolysis., Results: Ninety-two patients (128 knees) treated with the modular tibial component were alive at the time of final follow-up. No patient was lost to follow-up. Radiographs were available for 105 knees (82%). Three knees had been revised because of instability or infection; none had been revised because of loosening or osteolysis. The mean Knee Society clinical and functional scores were 85 points (range, 41 to 100 points) and 79 points (range, 30 to 100 points), respectively, at the time of final follow-up. According to The Hospital for Special Surgery score, 94% of the knees had a good or excellent result. Knee flexion averaged 113 degrees (range, 90 degrees to 130 degrees ) at the time of final follow-up. Osteolysis was present in seventeen (16%) of the knees with radiographic follow-up. Osteolysis did not develop in any knee in which an all-polyethylene tibial component had been used. Two knees (in one patient) were revised because of osteolytic lesions found at the time of follow-up for the study. Both of these knees had anterior wear of the tibial post due to impingement and backside tibial polyethylene wear., Conclusions: Modular Insall-Burstein II total knee prostheses were found to function well after five to eight years of follow-up. However, the high prevalence of osteolysis in patients who had good or excellent clinical scores is worrisome. Particular attention should be paid to preventing flexion of the femoral component, posterior slope of the tibial component, or hyperextension of the knee when posterior-cruciate-substituting total knee arthroplasty is performed. We also recommend routine follow-up radiographs after all total joint arthroplasties to detect asymptomatic osteolytic changes.

This study identifies new radiographic indices to approximate the location of the elbow rotational axis. With use of electromagnetic motion tracking source data, the average rotational axis of the ulnohumeral articulation was calculated in seven cadaveric specimens. Quasi-lateral radiographs of the elbow specimens were then analyzed to identify radiographic landmarks of the elbow axis in the lateral view. The spatial relationships of these landmarks with the elbow aligned on-axis were contrasted with their relationships in eight distinct off-axis alignments. Elbow axis orientation in the transverse plane (internal/external rotation) was identified by the location of a dense intramedullary cortical line, appearing in the projection of the distal humerus in relation to the periosteal surface of the posterior cortex of the humerus. This intramedullary line corresponds to the posteromedial cortex of the distal humerus. Correct alignment occurred when this line laid 27.1+/-3.7% of the anteroposterior humeral diameter anterior from the periosteal surface of the posterior cortex. Axis orientation in the coronal plane (abduction/adduction) was identified by the concentric appearance of radiographic arcs formed by the capitellum, trochlear sulcus, and medial trochlear flange. Using these radiographic indices, three orthopaedic surgeons were able to fluoroscopically align the elbow along the axis of rotation with an accuracy of 3.7+/-1.8 degrees. These results are immediately applicable to fluoroscopic identification of the elbow axis. This technique can be used to increase the accuracy of hinge placement during application of hinged external fixation or distraction arthroplasty.