The press-fit condylar modular total knee system. Four-to-six-year results with a posterior-cruciate-substituting design.

One hundred and eighteen patients who had had 150 consecutive primary total knee replacements (sixteen bilateral procedures) between February 1988 and February 1990, with insertion of the press-fit condylar modular total knee system with cement, were enrolled in a prospective study. Ninety-six patients (125 knees) were followed for an adequate interval (mean, 4.8 years; range, 3.8 to 6.2 years). Thirteen patients (fifteen knees) died, and nine patients (ten knees) were lost to follow-up. The mean age of the patients at the time of the index arthroplasty was seventy years (range, twenty-nine to eighty-five years). The patients were evaluated clinically and radiographically, according to the scoring system of the Knee Society, and the results on a self-administered questionnaire were used to evaluate pain, function, satisfaction, and patellofemoral symptoms. A Kaplan-Meier survivorship analysis was performed with a revision operation as the end point. The mean functional and clinical scores, according to the system of the Knee Society, were 78 and 93 points, respectively, at the most recent follow-up examination. The result was excellent for 103 knees, good for thirteen, fair for three, and poor for six. Three revision operations were necessary: two because of infection and one because of instability. The over-all rate of patellofemoral symptoms was 8 per cent (ten knees). Three knees had tibiofemoral instability; subsequent modification of the design of the tibial cam decreased the prevalence of this problem. Non-progressive radiolucent lines were present at the cement-bone interface in 39 per cent (thirty-nine) of the ninety-nine knees that had complete radiographic follow-up. No prosthesis had loosened by the time of the most recent follow-up examination. The rate of survival of the implant was 97 per cent at six years, and the standard error of the mean was 1.6 per cent. In the present series, total knee arthroplasties with the press-fit condylar modular knee system resulted in excellent relief of pain, an excellent range of motion, and restoration of function. They were also associated with a low prevalence of patellofemoral problems.

Treatment of castration-induced osteoporosis by a capacitively coupled electrical signal in rat vertebrae.

Castrated male Sprague Dawley rats were subjected to various capacitively coupled electrical fields for six and eight weeks at two and 4.5 months after castration, respectively, with pairs of electrodes that were located paraspinally on the surface of the skin dorsally at the eleventh thoracic and fourth lumbar levels. When the animals were killed, dry and ash weights per unit of volume (apparent density), elastic modulus, ultimate stress, work to failure, trabecular area fraction, and mean trabecular width were determined for selected vertebrae. The results indicated that a sixty-kilohertz, 100-microampere signal (a calculated current density of five microamperes root-mean-square per square centimeter and a field of twelve millivolts root-mean-square per centimeter) significantly reversed the castration-induced osteoporosis in the lumbar vertebrae and restored bone mass per unit of volume in rats that had been stimulated for eight weeks after castration.

Iron deposits surrounding multiple sclerosis plaques.

Autopsy samples from cerebral areas of five brains from patients with multiple sclerosis (MS) and from six control brains were stained with Perls acid ferrocyanide to detect nonheme iron present as hemosiderin. Positive iron reactions were observed only in MS sections surrounding demyelinated plaques. Myelinated white matter near the lesion contained numerous iron-laden ovoid bodied and axons that stained positively for iron. Positive reactions were also found within blood vessels of gray matter near the lesion. A possible source of the iron was extravasated blood.

Arthroscopic treatment of peripatellar fibrosis after total knee arthroplasty.

Forty-eight total knee arthroplasties (42 patients) were treated arthroscopically for symptomatic peripatellar fibrosis. All patients complained of knee pain before surgery. In addition, 47 knees (98%) had clicking or clunking, 35 (73%) had difficulty climbing stairs, and 9 (19%) had motion problems. The results of arthroscopy were 20 good (42%), 9 fair (19%), and 19 poor (40%). The mean follow-up time was 32.8 months (range, 11-75 months). A fourth portal was required in 20 knees (17 patients, 42%), indicating the complexity and difficulty of debridement. No components were found to be loose at the time of arthroscopy. A constellation of symptoms are caused by peripatellar fibrosis. In contrast to past reports, the arthroscopic treatment of peripatellar fibrosis was found to be unpredictable. Debridement of the offending soft tissue did not necessarily guarantee a good result. Arthroscopic management of peripatellar fibrosis is recommended; however, limited and specific surgical goals should be established prior to intervention.

Multiple prosthetic infections after total joint arthroplasty. Risk factor analysis.

The relative risk of age, sex, underlying diagnosis, corticosteroid usage, diabetes mellitus, and major nonprosthetic infection for the development of multiple prosthetic infections was assessed retrospectively. Deep infection occurred in 174 replacement arthroplasties in 145 patients between 1981 and 1993. Patients with rheumatoid arthritis had a significantly larger number of implants per patient (P < .001). Twenty-seven of 145 patients developed a second prosthetic infection, for an overall incidence of 19%. Of these 27, the underlying diagnoses were rheumatoid arthritis in 19, osteoarthritis in 6, neuropathic arthritis in 1, and systemic lupus erythematosus in 1. Rheumatoid arthritis and the occurrence of a major nonprosthetic infection (sepsis) were found to be highly associated with the development of a second prosthetic infection (P < .001 and P = .0001, respectively). In those rheumatoid patients with multiple infections, there was a significantly larger proportion with American Rheumatism Association class III and IV function than those with a single prosthetic infection (P = .0002). In 14 of the 27 cases of more than one prosthetic infection, the infected implants presented clinically within the same month. Ten of these 14 had an associated nonprosthetic infection. It is therefore not possible to accurately calculate the risk that one infected arthroplasty poses to other implants.