Fall Risk Associated with Continuous Peripheral Nerve Blocks Following Knee and Hip Arthroplasty.

Combined scientific advances in pharmaceutical agents, perineural blocks, and pump delivery capabilities such as those used with continuous peripheral nerve blocks have demonstrated advantages in pain management for patients undergoing joint arthroplasty. This report documents the incidence of falls increased after the implementation of a continuous peripheral nerve block program for patients undergoing knee and hip arthroplasty in an academic medical center.

An implantable telemetry device to measure intra-articular tibial forces.

Tibial forces are important because they determine polyethylene wear, stress distribution in the implant, and stress transfer to underlying bone. Theoretic estimates of tibiofemoral forces have varied between three and six times the body weight depending on the mathematical models used and the type of activity analyzed. An implantable telemetry system was therefore developed to directly measure tibiofemoral compressive forces. This system was tested in a cadaver knee in a dynamic knee rig. A total knee tibial arthroplasty prosthesis was instrumented with four force transducers located at the four corners of the tibial tray. These transducers measured the total compressive forces on the tibial tray and the location of the center of pressure. A microprocessor performed analog-to-digital signal conversion and performed pulse code modulation of a surface acoustic wave radio frequency oscillator. This signal was then transmitted through a single pin hermetic feed-through tantalum wire antenna located at the tip of the stem. The radio frequency signal was received by an external antenna connected to a receiver and to a computer for data acquisition. The prosthesis was powered by external coil induction. The tibial transducer accurately measured both the magnitude and the location of precisely applied external loads. Successful transmission of the radio frequency signal up to a range of 3m was achieved through cadaveric bone, bone cement, and soft tissue. Reasonable accuracy was obtained in measuring loads applied through a polyethylene insert. The implant was also able to detect unicondylar loading with liftoff.

Patient compliance with outpatient prophylaxis: an observational study.

The need for prophylaxis against venous thromboembolic disease following lower-extremity joint replacement is well documented and accepted. Although low molecular weight heparin is approved for inpatient and extended prophylaxis beyond the hospital environment, orthopedic surgeons must determine the duration of injectable low molecular weight heparin based on the period of venous thromboembolic disease risk and on patient compliance with self-administration of medication at home. Lack of confidence in patients' ability to self-administer injections may contribute to hesitancy in prescribing injectable prophylaxis. This observational study evaluated the effectiveness of a self-injection education program. Findings demonstrate that when properly instructed, patients safely and efficaciously self-administer low molecular weight heparin at home. With shorter hospital stays, self-administration of low molecular weight heparin may optimize the clinical outcomes of orthopedic patients.

Erythrocyte viability in blood salvaged during total joint arthroplasty with cement.

BACKGROUND: Erythrocyte salvage, the collection of a patient's blood shed from the surgical wound, is one aspect of blood management. Previous investigators have examined salvaged blood for content; however, to our knowledge, none have examined the viability of erythrocytes after exposure to the chemical and thermal reactions produced by motorized instruments and polymethylmethacrylate during surgery. The purpose of this study was to determine the viability of salvaged erythrocytes from patients undergoing primary total joint arthroplasty with cement. METHODS: Erythrocyte viability studies were performed on specimens from three subjects with use of a double isotope-labeling technique employing chromium-51 and technetium-99m. With use of a fresh blood specimen obtained prior to surgery and a specimen of salvaged blood that had been recycled, washed, and filtered with use of the Cell Saver, the viability of the Cell-Saver-processed erythrocytes, labeled with chromium-51, was calculated on the basis of the technetium-99m-labeled red blood-cell mass. RESULTS: The mean erythrocyte viability (and standard deviation) in blood salvaged with use of the Cell Saver was 88.0% +/- 3.8%. The standard of the American Association of Blood Banks for minimum erythrocyte viability in adequately cross-matched allogeneic blood or predeposited autologous blood is 70%. CONCLUSIONS: The high rate of viability of the erythrocytes in this study shows that the Cell Saver is a valuable adjunct to other blood management techniques for patients having total joint arthroplasty. We believe that the very high mean rate of erythrocyte viability and the extremely small standard deviation in our three subjects, as compared with the standards of the American Association of Blood Banks, made additional study subjects unnecessary.

The efficacy of continuous bupivacaine infiltration following anterior cruciate ligament reconstruction.

PURPOSE: The purpose of this study was to determine whether continuous infiltration of a local anesthetic into the surgical wound for 48 hours will diminish the need for narcotics and improve the postoperative pain experience for patients undergoing anterior cruciate ligament (ACL) reconstruction using a patellar tendon autograft. TYPE OF STUDY: Prospective, randomized, double-blind study with a placebo and an experimental group. METHODS: Twenty-six patients were randomly assigned to receive either normal saline (placebo) or bupivacaine (experimental) for 48 hours. Both groups received a single intra-articular bolus injection of 35 mL of 0.25% bupivacaine and 5 mg. of morphine at the conclusion of surgery. The placebo group received an infusion of 2 mL/h of normal saline and the experimental group received an infusion of 2 mL/h of 0.25% bupivacaine, both for 48 hours. The anesthetic was infused using a disposable elastomeric pump (Baxter Healthcare, Deerfield, IL). Patients were evaluated using a pain and pain relief assessment questionnaire and visual analogue scale (VAS). Narcotic consumption was also documented. The pump was discontinued either by the patient at home or by a physical therapist. RESULTS: There was a statistically significant (P <.05) difference in VAS pain and pain relief scores reported by patients receiving the infusion of 0.25% bupivacaine. Patients in the treatment group also consumed 37% less narcotics than the placebo group. The operating room time, tourniquet time, weight, and age of this population were similar in the 2 groups. There were no complications with the catheter technique. CONCLUSION: This report of a new technique suggests that surgical knee patients receiving local anesthetic infusion postoperatively experience less pain and require less narcotics. The disposable pump allowed administration of the medication on an outpatient basis.

Venous thromboembolism: prevention & treatment.

Venous thromboembolism still threatens the lives of hundreds of thousands of people in the United States--and some of them are your patients. Here's how to put the latest research and technology to good use in the fight against thromboembolic disease.

Clinical practice guidelines for early mobilization hours after surgery.

This clinical practice guideline (CPG) is the product of cohesive interdisciplinary collaboration. The impact of this project merits more than routine attention given the lack of published nursing literature. The Department of Nursing acted as the catalyst to improve the quality of patient care. This initiative resulted in a pivotal change in the standard of care, updating outmoded orthopaedic nursing practices. The most significant change improved the time patients began their first postoperative activity. Dangling the patient on the day of surgery enhanced the benefits of early activity and reduced the time from 16.8 to 6 hr with no adverse patient consequences. The CPG also demonstrated excellent postoperative pain management, realizing pain scores below 4 (0-10 scale) at multiple time points. In addition, the length of stay improved from 4.3 to 2.8 days. The results support the value of implementing a CPG.