Medial cortex strain distribution during noncemented total hip arthroplasty.

Intraoperative proximal femur fractures are a significant concern during noncemented total hip arthroplasty. The current study was performed to investigate the hypothesis that broaching the femur and inserting the stem without using mallet applied impact loads will reduce the risk of intraoperative fracture. Rosette strain gauges were applied to the medial and anteromedial cortex of six human anatomic specimen femurs to compare the strain distribution for broaching and stem insertion. Eight additional femurs were used to compare the strain distribution for stem insertion using impact loading and constant rate stem insertion. For the impact loading stem insertions, the soft tissues surrounding the femur were modeled. Constant rate stem insertions were performed using a mechanical testing machine. The largest strains measured at the medial and anteromedial sites primarily were aligned with the femur hoop axis. The largest strain magnitude, orientation, and sign (tensile or compressive) varied widely among femurs. The stem insertion strains were significantly larger than the broaching strains (two-way analysis of variance with replication). The impact stem insertion strains were not significantly different from the constant rate stem insertion strains. The results indicate that the femur geometry and material properties have a greater influence on the strain distribution than does the implantation technique.

Relative rates of fracture of the hip in the United States. Geographic, sex, and age variations.

We studied the Medicare data from 1984 through 1987 for 687,850 fractures of the hip that had occurred in the United States. Our purpose was to determine the geographic, sex-specific, and age-interval variations in the relative risk of fracture of the hip in elderly white individuals. The rates of cervical, trochanteric, and subtrochanteric fracture, and the over-all rate of fracture at any of the three levels, increased with age, were greater for women than for men, and were higher in the Southern part of the country. However, there were regional, sex, and age variations. The ratio of cervical to trochanteric fractures was significantly higher in the East South Central region and lower in the Middle Atlantic and New England regions (p < 0.05). These were the same areas with the highest and lowest over-all rates, respectively, of fracture of the hip. The ratio of cervical to trochanteric fractures decreased from 1.52 in women who were sixty-five to sixty-nine years old to 0.81 in women who were at least eighty-five years old, but it stayed at approximately 1.00 for the corresponding age-groups of men. The ratio of fracture of the hip in women to fracture of the hip in men varied depending on the level of the fracture.

Minimum 4-year follow-up of the PCA total knee arthroplasty in rheumatoid patients.

One hundred twenty-one consecutive nonrandomized primary total knee arthroplasties in 94 patients were performed between 1980 and 1984 using the Porous-Coated Anatomic prosthesis in patients with a diagnosis of severe rheumatoid arthritis. Of the 94 patients, 81 patients were able to be followed for more than 4 years, with the remaining 13 dying from unrelated causes prior to the 48-month follow-up. Of those arthroplasties with 48-month follow-up, 55 were uncemented and 26 were cemented. An 81% good to excellent result was seen for the cemented group and a 91% good to excellent result for the uncemented group. The postoperative arc of motion for the cemented group was 94 degrees, with the postoperative arc of motion in the uncemented group being 102 degrees. In evaluation of component interfaces, there were almost no lucencies seen among the femoral group, with no component failures in either group. Thirty-six percent of the uncemented group developed nonprogressive radiolucent lines along the tibial tray; 97% of these radiolucencies were less than 1 mm. Complications in the cemented group included a revision of one patellar and one tibial component for component loosening. In the uncemented group, complications included one case of deep sepsis following an intra-articular injection, loosening of two patellar components requiring revision, and loosening of two tibial components requiring revision.

Approaches to senior care #9. Results of total knee arthroplasty in patients 80 years and older.

Experience with total knee arthroplasty in the extremely elderly population, which has not been previously reported, is reviewed. Sixty-two total knee prostheses were implanted in 43 patients aged 80 to 95 years (average, 82 years). Ninety percent of the patients had a preoperative diagnosis of osteoarthritis. The results were compared with those obtained in a younger reference group (average age, 62 years) receiving 60 total knee prostheses.

Revision of septic total knee arthroplasty.

Nine patients with septic total knee arthroplasties (TKA) were treated between 1980 and 1984; six were gram-positive infections and three were gram-negative. Initial treatment included the maintenance of all solidly fixed components. Patients with loose components were treated with removal of all prosthetic material and subsequent reimplantation after a six-week course of antibiotics. At follow-up examination six of nine patients had satisfactory results. One patient maintained his original femoral and tibial components and one patient required a knee fusion to treat his recurrent gram-negative infection. Overall, complications were associated with chronic infection, gram-negative infection, and abnormalities of the extensor mechanism.

Characterization of human synovial mast cells.

Human synovium obtained at arthroplasty from patients with rheumatoid arthritis (RA) and osteoarthritis (OA) were characterized by assessing mast cell morphology, content and function. Histological studies confirmed significant numbers of mast cells in both RA and OA synovium. Electron microscopic data support the morphologic similarity between human synovial mast cells and human mast cells in lung and intestine. Likewise, synovial mast cells do not appear to be functionally different from pulmonary or intestinal mucosal mast cells. Mast cell suspensions with a cellular histamine content of 4.3 +/- 0.5 pg/cell (mean +/- SEM) released histamine following provocation with anti-IgE and calcium ionophore but not compound 48/80, f-met peptide or bradykinin. Prostaglandin D2 (PGD2) and leukotriene C4 (LTC4) were also released in response to anti-IgE. Auranofin inhibited anti-IgE provoked histamine, PGD2 and LTC4 release while gold sodium thiomalate, cromolyn and indomethacin had no effect on histamine release. Theophylline inhibited anti-IgE induced histamine release only at concentrations greater than or equal to 10(-3) M. Our study argues against functional or morphologic mast cell heterogeneity of human intestinal, lung and synovial origin and suggests that mast cells may have a pathogenic role in both RA and OA.

The effects of inaccurate bone cuts on femoral component position in total knee arthroplasty.

Patterns of malposition of total knee femoral components are presented and are correlated to specific faulty bone cuts. Femoral component malposition pattern recognition will facilitate intraoperative correction of inaccurate bone cuts.

Revision total knee arthroplasty for aseptic failure.

Twenty-four patients with 28 failed total knee arthroplasties replaced with porous-coated anatomic (PCA) primary or revision components were studied over a two- to four-year period. Overall, there were 68% good and excellent results and three failures. When evaluated according to mode of failure, 83% of the patients who had a definable mechanical problem achieved good or excellent results. Patients who had revision operations for incapacitating pain or in whom no clearly definable problem could be ascertained before operation were not significantly improved. Complications that led to poor results were deep sepsis, wound necrosis, and extensor mechanism abnormalities.

Effects of polymethylmethacrylate exposure upon macrophages.

The effects of polymethylmethacrylate (PMMA) exposure upon macrophage viability and function were studied in an attempt to determine what role these cells play in the loosening of cemented arthroplasties. P388D1 murine macrophage cell line was exposed to PMMA and polystyrene particles of similar size and concentration. DNA synthesis following exposure to PMMA or polystyrene was studied by [3H]thymidine incorporation. Macrophage function was studied by analyzing the ability of activated macrophages to kill mast cell targets following particle exposure. Our results demonstrate that exposure of macrophages to PMMA particles in vitro inhibits DNA synthesis and impairs their cytotoxic ability. Histologic examination revealed that macrophages phagocytose both PMMA and styrene particles, but the former eventually lyse these cells. Our studies suggest that the histologic appearance of macrophages and foreign body giant cells at the bone-cement interface may be secondary to a repetitive cycle of PMMA particle phagocytosis and cell death, similar to that found in a foreign body granulomatous response.

A histologic comparison of aseptic loosening of cemented, press-fit, and biologic ingrowth prostheses.

The histology of interface membranes from aseptic loosened prostheses of various types including cemented, press-fit, and biologic ingrowth varieties was compared. Pseudosynovial implant-facing surfaces were present in specimens from all types. The remaining portions of these membranes showed distinct characteristics as well. Cemented implant membranes contained many macrophages and giant cells and evidenced frequent granuloma formation. Press-fit membranes consisted of poorly vascularized, dense fibrous tissue within the loosened press-fit membrane. Macrophages and giant cells were rare, except in one specimen containing ceramic debris particles. Biologic ingrowth membranes were the most vascular and contained loosely organized connective tissue and islands of woven bone. Macrophages were common. One out of six specimens from patients with rheumatoid arthritis contained massive numbers of lymphocytes and plasma cells but not mast cells. The greatest numbers of mast cells were present in membranes from patients with osteoarthritis and in all cases were associated with the presence of stainless steel and/or chrome cobalt particles.

Total knee arthroplasty following patellectomy.

Eleven patients with a previous patellectomy and primary total knee arthroplasty (TKA) had chart reviews, recent clinical examinations, evaluation of roentgenograms, rating of knee arthroplasty on a standard scale, and quantitation of quadriceps and hamstring torque using an isokinetic dynamometer. Good to excellent results were present in only five of the 11 knees studied, compared with 11 of 11 patients in a control group with intact patellae. Quadriceps and hamstring torque and strength were diminished relative to the control groups. Factors that correlated with a success or failure of TKA in patients with previous patellectomy included: number of previous knee operations, three or less; presence of severe arthritic changes roentgenographically; and quadriceps performance of greater than 40 ft-lb at 30 degrees/second testing speed. Patients without patellae who lack these favorable prognostic factors for a successful TKA should be strongly considered for bracing or primary arthrodesis, rather than knee arthroplasty.

[Current knowledge and future perspectives of cementless endoprosthetics]. / Heutige Kenntnisse und Zukunftsperspektiven der zementlosen Endoprothetik.

The current problems facing the clinician, regarding young patients whose hips and knees have completely deteriorated, involve a return to function, as well as a longer life for the prosthesis than that rendered by cement fixation. The alternatives to cemented primary fixation devices have not yet with stood the test of time. In addition, when aseptic loosening of cemented prostheses occurs, cemented revisions have already demonstrated a high failure rate after a short-term follow-up, particularly in the hip. A follow-up period of up to 6 years for a cementless total knee and a short-term follow-up for a cementless hip (up to 3 years), using a porous metal bone contact surface, have shown very satisfactory clinical results in primary total hip and knee prostheses and revision of the total hip without the use of bone cement. These early results justify continuation of this clinical trial.

Results of total knee arthroplasty after failed proximal tibial osteotomy for osteoarthritis.

The cases of twenty-one consecutive patients who had a minimally constrained total knee arthroplasty (six of whom had a cemented and fifteen, an uncemented prosthesis) after a failed proximal tibial osteotomy for osteoarthritis were compared with those of a non-consecutive group of twenty-one patients who had had a primary total knee arthroplasty for osteoarthritis. The groups were matched according to age and sex of the patient, type of prosthesis and fixation, and length of follow-up. At an average length of follow-up of 2.9 years, a good or excellent result was obtained in 81 per cent of the patients who had had a previous osteotomy. At an average length of follow-up of 2.8 years, a good or excellent result was obtained in 100 per cent of the patients who had had a primary arthroplasty. Two patients in the osteotomy group and none in the primary arthroplasty group required additional surgery. At the time of arthroplasty, technical difficulties in exposing the proximal part of the tibia were noted in three patients in the group that had undergone an osteotomy. The results of total knee arthroplasty after failed proximal tibial osteotomy approached but did not equal the results after primary total knee arthroplasty.

Reflex sympathetic dystrophy as a cause of poor results after total knee arthroplasty.

In a series of 662 primary total knee arthroplasties, reflex sympathetic dystrophy (RSD) was diagnosed in five patients (0.8%), four of whom demonstrated marked limitation of flexion requiring manipulation during the early postoperative period. Limitation of flexion, along with excessive pain and cutaneous hypersensitivity, should alert the surgeon to the possibility of RSD. Classic posttraumatic RSD findings of objective vasomotor changes and radiographic osteopenia may be difficult to interpret in patients after total knee arthroplasty. Sympathetic blockade is the key diagnostic and therapeutic measure in the management of RSD. RSD should be considered in a differential diagnosis of early poor results after total knee arthroplasty.

Femoral head avascular necrosis: CT assessment with multiplanar reconstruction.

Thirty-two patients with avascular necrosis (AVN) of the femoral head underwent imaging studies using computed tomography with multiplanar reconstructions (CT/MPR). Staging of the disease by means of CT/MPR images was compared with traditional staging by means of routine frontal and frog-leg lateral radiographs. CT/MPR examination upgraded staging in 30% of the hips studied and made significant contributions to patient management in 14 (54%) of 26 patients for whom both CT scans and plain-film radiographs were available for comparison. Asymptomatic and radiographically normal contralateral hips were found at CT study to have stage II or stage III AVN in four patients. Subtle alterations in trabecular patterns, joint spaces, femoral-head contours, and acetabula were well defined on CT/MPR studies in many cases; previously undetected or ill-defined abnormalities were frequently visualized. The major weight-bearing components of the hip (anterior and posterior acetabular columns, acetabular dome, and superior pole of the femur), which may be poorly defined on CT scans due to partial volume effects on the transaxial images, were best seen on the sagittal and coronal reconstructions. A new system for staging AVN is suggested.

The importance of increased intraosseous pressure in the development of osteonecrosis of the femoral head: implications for treatment.

Early diagnosis of osteonecrosis by radiograph, bone scan, CT scan, magnetic resonance imaging (MRI), intraosseous pressure measurement, or intraosseous venogram can lead to early successful treatment. For early (Ficat stages I and II) osteonecrosis of the hip, core decompression can provide diagnostic confirmation and pain relief and may prevent progression of disease. For more advanced disease (Ficat stages II and IV), osteotomy, endoprosthetic or bipolar prosthetic replacement, total hip arthroplasty, and arthrodesis are surgical options.