Beverly A. Morris

Use of enoxaparin, a low-molecular-weight heparin, and unfractionated heparin for the prevention of deep venous thrombosis after elective hip replacement. A clinical trial comparing efficacy and safety. Enoxaparin Clinical Trial Group.

A randomized, parallel-group, open-label clinical trial (the physicians, patients, and staff were not blinded with regard to the regimen that had been used) was conducted, between December 1988 and September 1990, to compare the safety and efficacy of enoxaparin, a low-molecular-weight heparin, with the safety and efficacy of unfractionated heparin for the prevention of deep venous thrombosis after elective hip replacement. Six hundred and ten patients were randomized, and 607 patients received one of the study medications. The evaluations of efficacy included contrast-media venography, non-invasive vascular examination, and clinical examination. Data on efficacy were available for 604 patients, who had been assigned to one of three treatment groups: thirty milligrams of enoxaparin every twelve hours (194 patients), forty milligrams of enoxaparin once daily (203 patients), or 5000 units of unfractionated heparin every eight hours (207 patients). All drugs were administered subcutaneously. Dosages were not adjusted on the basis of the results of coagulation tests or the body weight of the patient. Treatment was initiated within twenty-four hours after the operation and continued for a maximum of seven days. The primary safety outcome was the occurrence of bleeding episodes. An intent-to-treat patient analysis revealed that deep venous thrombosis occurred in nine (5 per cent) of the 194 patients who received thirty milligrams of enoxaparin every twelve hours, thirty (15 per cent) of the 203 patients who received forty milligrams of enoxaparin once daily, and twenty-four (12 per cent) of the 207 patients who received unfractionated heparin. The rate of deep venous thrombosis was significantly lower in the group that received thirty milligrams of enoxaparin every twelve hours than in the group that received unfractionated heparin (p = 0.03) and in the group that received forty milligrams of enoxaparin once daily (p = 0.0002). No clinically symptomatic pulmonary embolism was observed during the treatment or follow-up phase of this study in the group that received thirty milligrams of enoxaparin every twelve hours. Analysis of evaluable patients revealed a marked reduction in the rate of deep venous thrombosis in the group that received thirty milligrams of enoxaparin every twelve hours (eight [6 per cent] of 136 patients) compared with the group that received heparin (twenty-one [15 per cent] of 145 patients) (p = 0.10); however, this difference was not significant because of the small number of patients included in this analysis.(ABSTRACT TRUNCATED AT 400 WORDS)

The effect of preoperative exercise on total knee replacement outcomes.

This study compared the effects of preoperative physical therapy or general cardiovascular conditioning exercises with the routine procedure of no preoperative physical therapy on patients undergoing primary total knee replacement. Thirty patients were randomly assigned to 1 of 3 groups. Group 1 was the control group. Group 2 participated in a physical therapy program designed to strengthen the upper and lower limbs and improve knee range of motion. Group 3 participated in a cardiovascular conditioning program, consisting of arm ergometry, cycle ergometry, aquatic exercises, and aerobic activity. All patients were evaluated preoperatively and postoperatively using the Hospital for Special Surgery Knee Rating, the Arthritis Impact Measurement Scale, and the Quality of Well Being instrument. Both experimental groups tolerated their respective exercise protocols extremely well. All 3 groups showed significant improvement postoperatively as measured by the Hospital for Special Surgery Knee Rating, the Arthritis Impact Measurement Scale and the Quality of Well Being measurement scales. However, neither type of preoperative exercise added to the degree of improvement after surgery at any of the postoperative evaluations.

The influence of continuous passive motion on the results of total knee arthroplasty

Twenty-two primary total knee arthroplasties were prospectively randomized into one of two treatment protocols. Ten of these patients were managed in the hospital after surgery by means of a postoperative splint. The remaining 12 patients were placed immediately postoperatively in the recovery room into the continuous passive motion (CPM) device. The study compares the range of motion, analgesic use, hospital stay, and the volume of hemovac output in the two groups. These cases demonstrated two statistically significant findings with the use of CPM: (1) decreased use of narcotic analgesics and (2) decreased length of hospital stay.

Postoperative use of continuous passive motion, transcutaneous electrical nerve stimulation, and continuous cooling pad following total knee arthroplasty*

Three rehabilitation modalities relating to in-hospital postoperative care following unilateral total knee arthroplasty (UTKA) were studied regarding their effect on pain management and UTKA outcome: (1) continuous passive motion (CPM); (2) CPM with transcutaneous electrical nerve stimulation (TENS); and (3) CPM with continuous cooling pad (CCP). Phase I: CPM. Twenty-two UTKA patients were randomized into two postoperative care groups: (1) 12 with CPM; and (2) 10 with no CPM. Total hospitalization pain medication consumption was significantly less for the CPM group (P less than .05). Phase II: CPM With TENS. Forty-eight UTKA patients were randomized into three postoperative care groups: (1) 18 with an ipsilateral thigh TENS unit delivering sensory threshold stimulation; (2) 18 with a subthreshold TENS unit; and (3) 12 with no TENS unit. All groups used CPM. No significant difference was found regarding pain medication consumption. Phase III: CPM With CCP. Thirty consecutive UTKA patients were divided into two postoperative care groups: (1) 15 with a CCP unit; and (2) 15 with no CCP unit. Both groups used CPM. No significant difference was found regarding total or intramuscular hospitalization pain medication consumption. However, oral hospitalization pain medication consumption was significantly less for the CCP group (P less than .01). This postoperative UTKA study demonstrates significantly decreased total in-hospital pain medication consumption when comparing CPM vs no CPM, significantly decreased oral in-hospital pain medication consumption when comparing CPM with CCP vs CPM without CCP, but no difference when comparing CPM with TENS vs CPM without TENS.(ABSTRACT TRUNCATED AT 250 WORDS)

e-Knee: evolution of the electronic knee prosthesis. Telemetry technology development.

Our purpose was to develop a fully instrumented tibial component of a total knee prosthesis (Fig. 1) containing multichannel transducers (load cells), a microtransmitter, and an antenna. Three complex technologies were incorporated into a prosthesis capable of measuring in vivo tibiofemoral compressive forces to transmit “real-time” data. The geometry was modified to accommodate the transducer and electronic technologies (Fig. 2). Fig. 1: Photograph of instrumented prototype and polyethylene insert. Fig. 2: Schematic of the e-Knee, a total knee prosthesis containing transducers (load cells), a transmitter, and an antenna. As a result of the development of a fully instrumented implant, direct load measurements were recorded intraoperatively during the course of a total knee replacement. Long-term collection of in vivo measurements of loads on a total knee prosthesis will allow future improvements in knee-replacement design, rehabilitation, and assistive devices such as lower-extremity braces, orthotics, and shoes. This report describes the history and preliminary results of the use of a total knee prosthesis with a telemetric implant, the e-Knee. Until now no devices or methods for measuring loads in vivo in the knee have been available. Measurement of tibiofemoral forces is directly relevant to the design and technique of implantation of knee prostheses. The wear and deformation of the articulating surface (polyethylene), the distribution of stress to the implant, the mechanical behavior of the bone-implant interface, and the load-carrying characteristics of the remaining bone are intimately related to the joint load. Until now, investigators have relied principally on theoretical data from mathematical modeling, biomechanical testing of cadavers, and clinical gait analysis to predict the physical forces on the knee (Fig. 3). Fig. 3: Theoretical model. Predictions based on theoretical data have revealed that tibiofemoral forces range from three to six times body weight during walking, ascending and descending stairs, and isokinetic exercise. While the information gleaned from …

Patient-controlled analgesia compared with intramuscular injection of analgesics for the management of pain after an orthopaedic procedure

Patients who were scheduled for an elective joint replacement or spinal procedure were randomly assigned prospectively to one of two groups for the management of postoperative pain: ninety-one patients (Group I) controlled the administration of a narcotic analgesic themselves and ninety-three patients (Group II) received intramuscular injections of a narcotic analgesic, as needed. The patients who controlled the analgesic used a smaller amount of the analgesic on the first postoperative day, but the over-all amount was not significantly different between the two groups. The group that received intramuscular injections reported less pain overall, according to one of three pain-assessment scales, and had more relief of pain over-all and on the first postoperative day, according to another scale. The patients who had had a total joint replacement and who controlled the analgesia walked farther on the first postoperative day than those who received intramuscular injections. There were no significant differences between the two groups with regard to the rate of complications, the arterial oxygen saturation levels during the first twenty-four hours after the operation, or the length of stay in the hospital. The nursing staff preferred the patient-administered method of analgesia, as it necessitated equal or less nursing time to assemble, initiate, and maintain than traditional intramuscular injections. The average cost per patient was

In vivo changes after mechanical injury.

58.58 for the patient-administered analgesia and

Osteonecrosis of the femoral head in patients with inflammatory arthritis or asthma receiving corticosteroid therapy.

22.45 for the intramuscular injections.(ABSTRACT TRUNCATED AT 250 WORDS)

Hemodilution with other blood reinfusion techniques in total hip arthroplasty

Chondrocytes undergo apoptosis in response to mechanical injury in vitro. The current clinical study correlates arthroscopic and magnetic resonance imaging results with biopsy specimens of cartilage from patients with knee injury. Twenty patients were evaluated at a mean 2.7 months after acute knee injury. The mean age of the patients was 32 years and the mean weight was 83 kg. Cartilage lesions were graded separately on magnetic resonance images and arthroscopy in a blinded manner. During arthroscopy, a 1.8 mm diameter biopsy specimen was obtained from the edge of cartilage lesion. The biopsy specimen underwent histologic examination by safranin O staining and detection of chondrocyte apoptosis by the presence of deoxyribonucleic acid fragmentation. There was a positive correlation in 50% (10 of 20) when the presence or absence of cartilage lesions by magnetic resonance imaging was correlated with arthroscopy. All cases of partial thickness or full-thickness cartilage loss that were seen by arthroscopy also were detected by magnetic resonance images. Apoptotic cells were significantly more numerous in biopsy specimens from lesions compared with control biopsy specimens. The findings of reduced cell viability attributable to apoptosis may have profound implications for cartilage repair. This opens potential therapeutic avenues for the treatment of posttraumatic cartilage lesions through apoptosis prevention.

Blood Loss and Transfusion Rate in Noncemented and Cemented/Hybrid Total Hip Arthroplasty. Is There a Difference? A Comparison of 25 Matched Pairs

The utilization of corticosteroids in the management of acute and chronic inflammatory processes, such as asthma or inflammatory arthritis, has been implicated in the adverse effects of multiple organ systems. One potential area of these negative consequences in the use of corticosteroids is the development of osteonecrosis of the femoral head. A direct time/dosage relationship for treatment with corticosteroids of patients with an established diagnosis of asthma or inflammatory arthritis and femoral osteonecrosis is unknown. A prospective study was undertaken to evaluate the use of corticosteroids and the incidence of osteonecrosis of the femoral head and potentially establish a time/dosage relationship in this patient population. No direct relationship between corticosteroid dosage and the development of femoral head osteonecrosis in 1420 hip-years was demonstrated at 10-year follow up.