Clinical orthopaedics and related research
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Clin. Orthop. Relat. Res. · Feb 1993
The use of lower tourniquet inflation pressures in extremity surgery facilitated by curved and wide tourniquets and an integrated cuff inflation system.
Use of the lowest possible cuff inflation pressure should minimize the pathogenic effects of compression beneath the pneumatic tourniquet. Curved tourniquets (designed to fit conically shaped limbs) and wider tourniquets were associated with significantly lower arterial occlusion pressure (AOP) than standard, straight tourniquets on the arms and legs of 26 normal volunteers. ⋯ Incomplete hemostasis was associated with elevated systolic blood pressure in several cases, but acceptable surgical hemostasis was achieved by incremental increase of the cuff inflation pressure. Curved cuffs, wide cuffs, and an integrated cuff inflation system should facilitate the use of lower tourniquet inflation pressures in extremity surgery.
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Clin. Orthop. Relat. Res. · Feb 1993
Methylmethacrylate plasma levels during total hip arthroplasty.
Methylmethacrylate (MMA) plasma concentrations were measured in 11 patients scheduled for total hip arthroplasty. After acetabular and after femoral cement implantation, sequential blood samples were withdrawn from pulmonary and radial artery catheters. The peak concentration of MMA (mean +/- standard error of the mean) in pulmonary artery blood occurred two minutes after cement implantation and was significantly higher after acetabulum (5.0 +/- 1.3 micrograms/ml) than after femoral cement insertion (1.9 +/- 0.6 micrograms/ml). ⋯ The initial half-life was 0.3 +/- 0.1 minutes, and the terminal half-life was 3 +/- 0.7 minutes. The areas under the curve (AUC) were determined for pulmonary (AUCpa) and radial (AUCra) plasma samples, and the ratio (AUCpa - AUCra)/AUCpa was computed: 55.1 +/- 7.8% of MMA was cleared during the transpulmonary passage. These results demonstrate that: (1) MMA could be determined after each cement implantation, (2) MMA plasma concentrations were higher after acetabulum than after femoral cement implantation, and (3) the half-life is short and the total pulmonary clearance is high.
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Reasons for reoperation after knee revision surgery are implant loosening, sepsis, extensor mechanism problems, fractures of bone or prosthetic components, wear debris, and limited range of motion. The purpose of this study was to review the complications requiring reoperation in a large number of condylar revision total knee arthroplasties to determine the incidence and outcome after treatment. Six hundred fifty-five condylar revision total knee arthroplasties performed during a ten-year period were retrospectively reviewed. ⋯ All patients were observed for an average of 7.5 years. Twenty-four knees (52%) were considered clinical failures because of pain, limited motion, instability, and sepsis. Awareness of these failure modes may help to prevent complications by strict attention at the time of revision surgery to protection of the patellar tendon attachment and collateral ligaments, balancing of the extensor mechanism, preservation of the patellar blood supply, proper component position and sizing, restoration of the mechanical axis, and use of more constrained implant designs.
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Clin. Orthop. Relat. Res. · Jan 1993
Occlusion of arterial flow in the extremities at subsystolic pressures through the use of wide tourniquet cuffs.
Tourniquet-induced peripheral neuropathy is at least partially attributable to excessive forces applied to the nerves beneath cuffs inflated to high pressures. Lowering the inflation pressure to the minimum necessary to obtain an effective arrest of blood flow distal to the tourniquet cuff should increase the safety of these systems. Tourniquet cuffs with widths varying from 4.5 cm to 80 cm were applied to the upper and lower extremities of 34 healthy, normotensive volunteers. ⋯ The occlusion pressure was inversely proportional to the ratio of tourniquet cuff width to limb circumference and was in the subsystolic range at a cuff width to limb circumference ratio above 0.5. Wide tourniquet cuffs can achieve an effective arrest of the regional arterial circulation at subsystolic pressures of inflation. Wide cuffs may reduce the risk of tourniquet-induced injury to underlying soft tissues by lowering the inflation pressure required to secure a bloodless field.
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Clin. Orthop. Relat. Res. · Nov 1992
Comparative StudyIn vitro elution characteristics of commercially and noncommercially prepared antibiotic PMMA beads.
The successful treatment of osteomyelitis with commercially prepared gentamicin-polymethylmethacrylate (PMMA) (Septopal) beads and surgical debridement has led to the use of this technique in the United States. However, commercially prepared gentamicin-PMMA beads are not currently available to orthopedic surgeons in the United States. ⋯ This study compares the measured amount of antibiotic elution of either gentamicin or tobramycin from laboratory manufactured Zimmer, Simplex, or Palacos beads to commercially prepared gentamicin-PMMA (Septopal) beads. During a 30-day study period, commercially prepared gentamicin-PMMA beads eluted more total antibiotic and maintain higher concentrations than did antibiotic acrylic composites manufactured in the authors' laboratory.