Predicted Rate of Secondary Malignancies Following Adjuvant Proton Versus Photon Radiation Therapy for Thymoma.

PURPOSE: Thymic malignancies are the most common tumors of the anterior mediastinum. The benefit of adjuvant radiation therapy for stage II disease remains controversial, and patients treated with adjuvant radiation therapy are at risk of late complications, including radiation-induced secondary malignant neoplasms (SMNs), that may reduce the overall benefit of treatment. We assess the risk of predicted SMNs following adjuvant proton radiation therapy compared with photon radiation therapy after resection of stage II thymic malignancies to determine whether proton therapy improves the risk-benefit ratio. METHODS AND MATERIALS: Ten consecutive patients treated with double-scattered proton beam radiation therapy (DS-PBT) were prospectively enrolled in an institutional review board-approved proton registry study. All patients were treated with DS-PBT. Intensity modulated radiation therapy (IMRT) plans for comparison were generated. SMN risk was calculated based on organ equivalent dose. RESULTS: Patients had a median age of 65 years (range, 25-77 years), and 60% were men. All patients had stage II disease, and many had close or positive margins (60%). The median dose was 50.4 Gy (range, 50.4-54.0 Gy) in 1.8-Gy relative biological effectiveness daily fractions. No differences in target coverage were seen with DS-PBT compared with IMRT plans. Significant reductions were seen in mean and volumetric lung, heart, and esophageal doses with DS-PBT compared with IMRT plans (all P≤.01). Significant reductions in SMNs in the lung, breast, esophagus, skin, and stomach were seen with DS-PBT compared with IMRT. For patients with thymoma diagnosed at the median national age, 5 excess secondary malignancies per 100 patients would be avoided by treating them with protons instead of photons. CONCLUSIONS: Treatment with proton therapy can achieve comparable target coverage but significantly reduced doses to critical normal structures, which can lead to fewer predicted SMNs compared with IMRT. By decreasing expected late complications, proton therapy may improve the therapeutic ratio of adjuvant radiation therapy for patients with stage II thymic malignancies.

Compression arthrodesis of the ankle by triangular external fixation: biomechanical and clinical evaluation.

This article describes a technique of ankle arthrodesis using a triangular external fixation frame and presents the results of biomechanical analysis and clinical experience with the frame. Clinical evaluation of 23 ankle arthrodeses performed using a triangular external fixation frame yielded a 91.3% fusion rate at an average of 11 weeks postfusion. The triangular frame was 79% stiffer than a compression-only external frame in torsion and 39% stiffer in anteroposterior bending. This high rate of fusion is attributed to the elimination of micromotion at the fusion site because of the increased rigidity of the triangular external compression frame.

The incidence of large venous emboli during total knee arthroplasty without pneumatic tourniquet use.

UNLABELLED: Echogenic venous emboli accompany tourniquet deflation during total knee arthroplasty. Two types of echogenic emboli appear in the central circulation: small venous emboli (miliary emboli) and large venous emboli (masses of echogenic material superimposed on miliary emboli). Presumably, medullary cavity trespass releases small and large echogenic emboli. However, patients undergoing lower extremity procedures with a tourniquet have large echogenic emboli regardless of medullary cavity invasion. Avoiding tourniquet inflation may decrease the release of large venous emboli. Thirteen patients undergoing total knee arthroplasty without pneumatic tourniquet received intramedullary guides and 11 patients received tibial extramedullary guides. Recordings of hemodynamic variables, mixed venous oximetry, end-tidal CO2, and echocardiographic images were made after the induction of anesthesia and for 15 min after femoral prosthesis cementing. Mean arterial pressure did not change during the study, and mean pulmonary arterial pressure increased minimally. Large venous emboli appeared in eight patients, small venous emboli appeared in 12 patients, and no emboli appeared in four patients. Compared with previous investigations of large venous emboli during total knee arthroplasty with a pneumatic tourniquet, multiple logistic regression analysis discloses a 5.33-fold greater risk of large venous embolism accompanied the use of a tourniquet during total knee arthroplasty. IMPLICATIONS: One third of knee replacements performed without a tourniquet demonstrated large emboli. Reducing marrow cavity invasion did not decrease the release of large emboli. Compared with knee replacement without tourniquet, tourniquet use places patients at a 5.33-fold greater risk of having a large emboli.

Emboli observed with use of transesophageal echocardiography immediately after tourniquet release during total knee arthroplasty with cement.

The right atrium and the right ventricle of fifty-five patients were imaged with transesophageal echocardiography during fifty-nine total knee arthroplasties performed with cement and the use of general anesthesia. The patients ranged in age from thirty-two to eighty-three years (mean, 65.5 years). Cardiopulmonary parameters were measured with use of hemodynamic monitoring systems, such as pulse oximeters, pulmonary artery catheters, and radial artery catheters. In addition, a femoral vein catheter was inserted on the side of the operation in ten of the fifty-five patients. Showers of echogenic material traversing the right atrium, the right ventricle, and the pulmonary artery after the tourniquet was deflated were observed to various degrees in all patients and lasted three to fifteen minutes. The mean peak intensity occurred within thirty seconds (range, twenty-four to forty-five seconds) after the tourniquet was released. The mean mixed venous oxygen saturation (and standard error of the mean) decreased (from 83+/-0.9 to 72+/-1.5 per cent) and the mean pulmonary arterial pressure increased (from 20+/-1.0 to 27+/-1.0 millimeters of mercury [2.67+/-0.13 to 3.60+/-0.13 kilopascals]), compared with the values before the tourniquet was released, in all patients. The pulmonary vascular resistance index increased after release of the tourniquet (to a maximum of 328+/-29 dyne.s.cm(-5).m2; p = 0.00002) only in the patients who had echogenic material that was at least 0.5 centimeter in diameter. Clinical pulmonary embolism developed postoperatively in three patients; all three had had echogenic particles that were more than 0.5 centimeter in maximum diameter on imaging. Blood aspirated from one of the pulmonary artery catheters and from five of the ten femoral vein catheters demonstrated fresh venous thrombus. Histological evaluation of the aspirates failed to demonstrate fat, marrow, or particles of polymethylmethacrylate. Surgeons should consider acute pulmonary embolism as a diagnosis when evaluating a patient who has hemodynamic collapse during total knee arthroplasty performed with cement.

Pseudoaneurysm following femoral fracture.

If the physician is aware of this diagnosis and maintains an appropriate level of suspicion and low threshold to commence duplex evaluation. The potential morbidity of a fracture-induced traumatic pseudoaneurysm can be minimized.

Functional results of percutaneous laser discectomy.

The purpose of the study was to evaluate laser disc decompression with the KTP 532 laser, used in conjunction with a percutaneous technique, in contained, small to moderately sized lumbar disc herniation. Sixty-three patients who had a contained herniated nucleus pulposus (HNP) and underwent percutaneous laser disc decompression were prospectively studied. Sixty-one were available for follow-up. Access to the disc space was attained with an 18-gauge probe, followed by dilating cannulas guided with an image intensifier. Discography was not performed. The power was set at 10 W, and laser pulses were delivered for 0.2 seconds, with an interval of 0.5 seconds. A total of 1250 J was delivered to the disc space. The average follow-up was 31.75 months (range, 20 to 45 months). Overall, 44 patients (72%) achieved relief of radicular pain, and 33 patients (54%) achieved relief of low back pain. Thirty-six of 61 patients (59%) returned to work by postoperative week 4. Fourteen patients failed treatment, experiencing persistent symptoms (with scores on the Andrews and Lavyne rating scale of < or = 3). In this study group, optimal results were obtained when symptoms were treated within 1 year of presentation. Results from a historical control group are provided for comparison.

A six-degrees-of-freedom instrumented linkage for measuring the flexibility characteristics of the ankle joint complex.

Diagnosis of ligament injuries to the ankle joint complex is a difficult clinical problem which relies primarily on manual physical examination and on radiographic evaluations. In an attempt to develop a reliable, quantitative diagnostic tool for such injuries we developed a six-degrees-of-freedom instrumented linkage (Ankle Flexibility Tester-AFT) capable of measuring the flexibility characteristics of the ankle joint complex in vivo. The unique non-serial structure of this linkage was such that these characteristics were recorded directly in an ]anatomical coordinate system which enhanced clinical interpretation. The goal of the present study was to develop this linkage and to test its accuracy and its test-retest reliability. The positional accuracy of the AFT was measured and was found to be better than 0.5 mm for translation and 1.2 degrees for rotations. The results obtained from a study conducted on two cadaveric specimens indicate negligible effect of loading rate on the flexibility characteristics within the range of possible manually applied loads. Finally, the reliability of the AFT was examined from test-retest studies conducted on a total of thirteen young healthy volunteers. The intraclass correlation coefficient (ICC), calculated from the test-retest data, indicated a reliability higher than 0.85. It was concluded that the high reliability and accuracy of the AFT, its simplicity of operation, the easy alignment procedure, the on-line load-displacement results, and the elimination of complex data processing render this device suitable for use in the clinic as well as in the research laboratory.

Postoperative autotransfusion after total knee arthroplasty.

To evaluate the quality of shed blood postoperatively after total knee arthroplasty (TKA), the safety of autotransfusion, and to minimize homologous transfusion, the Autovac system was used for reinfusion of whole blood following cemented TKA. The system was used in 50 consecutive patients who were reinfused an average of 420 cc of whole blood. Twenty-five patients had a calcium binding resin anticoagulant within the collection canister. A second group of 25 patients had 40 cc of acid citrate dextrose anti-coagulate (ACD-A) in the collection canister as an anticoagulant. Fifteen hematologic parameters were measured during five time periods. Each study group was compared to a control group of 25 TKAs with a standard drain. The clinical safety of auto-transfusion with ACD-A was proven. Blood collected in the calcium binding resin had a statistically significant higher hemoglobin (P < .05), plasma-free hemoglobin (P < .05), fibrin split products (P < .05), and a different white blood cell differential.

The incidence of venous emboli during extramedullary guided total knee arthroplasty.

During total knee arthroplasty (TKA), instrumentation of the marrow cavity with an intramedullary guide appears responsible for fatal intraoperative pulmonary embolism. Transesophageal echocardiography demonstrates venous emboli (VE) after tourniquet deflation during intramedullary guided TKA. Extramedullary guides avoid manipulating the marrow cavity. We determined the incidence of VE in 20 patients undergoing extramedullary guided TKA. Recordings of hemodynamic variables, mixed venous oximetry, end-tidal CO2 and N2 tensions, and echocardiograph images occurred after induction of anesthesia, after tourniquet inflation, during cementing, and for 15 min after tourniquet deflation. Large VE appeared in 14 patients and small VE in the other 6 patients. Large VE occurred only after deflation of the tourniquet. Beginning 3 min after tourniquet deflation, mean pulmonary arterial pressures increased from the baseline of 21 +/- 1.0 to 30 +/- 1.3 mm Hg and remained increased for the duration of the procedure. The incidence of large VE with extramedullary guided TKA did not differ compared to the previously reported incidence with intramedullary guided TKA. These data suggest that VE might arise from a thrombogenic effect of the tourniquet rather than from manipulation of the marrow cavity.

Results of lumbar disk surgery in a city compensation population.

This is a retrospective analysis of 118 patients who underwent 132 operations in a city compensation setting for the treatment of lumbar disk disease from January 1976 to December 1987. Each of these patients had a work-related injury. There was a minimum 2-year follow up with an average follow up of 6.9 years. No patients were lost to follow up. The purpose was to determine what percentage of patients treated in a work-related setting could be expected to return to a sustained, pre-injury employment state following a carefully executed lumbar spine surgical procedure. Satisfactory surgical results were considered achieved only by those patients who returned to full-duty work status. Only 31 of the 118 patients (26%) returned to full duty and were considered satisfactory. Regarding the number of surgical procedures, 31 of 132 operations (23%) were successful. Sixteen reoperations in 13 patients all resulted in failure. Only 16 of the 64 patients (25%) treated with laminectomy and diskectomy alone had a satisfactory result. When a two-level, posterior lateral spinal fusion was added the success rate was increased to 44%, with 12 of 27 patients returning to work. Six patients with spinal stenosis underwent decompression laminectomy and entry level foraminotomies, and all had unsatisfactory results. Five patients with isthmic spondylisthesis underwent a Gill procedure and fusion. Only one of these patients (25%) returned to work. For a 2-year period chymopapain injection was given to 14 patients. Only two returned to work, with a 14% success rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Conversion of resection arthroplasty to total hip replacement.

Conversion of Girdlestone arthroplasty is a demanding procedure dependent on adequate debridement at time of resection and appropriate long-term antibiotic therapy. Patients must be followed closely for persistent sepsis through ESR, aspiration, and physical examination. Pre-reconstruction, existing bone stock should be assessed and revision techniques utilized where appropriate. Our experience is that conversion of Girdlestone pseudoarthrosis to THR can yield good functional results and restore independence.

Echogenic emboli upon tourniquet release during total knee arthroplasty: pulmonary hemodynamic changes and embolic composition.

Echogenic venous emboli accompany tourniquet deflation during total knee arthroplasty. The associated pulmonary hemodynamic alterations and determined embolic composition were measured in 34 patients, undergoing 35 procedures. Ten patients received a femoral venous catheter on the operative side. Hemodynamic variables, heart rate and mixed venous oximetry, end-tidal CO2 and nitrogen tensions, and transesophageal echocardiograms were recorded after induction of anesthesia (baseline), after tourniquet inflation, after cementing, and for 15 min after tourniquet deflation. Echocardiograms revealed either showers of miliary echogenic material (Group S, 9 patients), or large echogenic masses superimposed on the showers (Group MS, 26 patients). In Group MS only, pulmonary vascular resistance index increased above baseline (205 +/- 16 [SEM] dyne.s.cm-2) beginning 5 min after tourniquet deflation (maximum 328 +/- 29, P < 0.05). Mean pulmonary arterial pressure increased above baseline (20 +/- 1.0 mm Hg) for both Groups S and MS beginning 3 min after tourniquet deflation (27 +/- 1.0, P < 0.05). Cardiac index did not change. Five of 10 patients demonstrated fresh thrombus from the catheter in the operative limb. Echogenic emboli occurred in all patients upon tourniquet deflation during knee arthroplasty. Pulmonary vascular resistance index increased only in patients with large echogenic material. Our data suggest that these emboli represent fresh thrombus formation during tourniquet inflation. Heparin administration prior to tourniquet inflation may diminish embolic showers.

Acetabular osteolysis in total hip arthroplasty: prevention and treatment.

Osteolysis can occur around loose, as well as well fixed, cemented or cementless acetabular components in total hip arthroplasty. Histologic studies of tissues biopsied from osteolytic regions suggest an adverse foreign body response to polyethylene and other particulate debris from prosthetic materials. Phagocytosis of these particles by macrophages and giant cells stimulate the production of proteolytic enzymes and inflammatory mediators, all leading to tissue destruction. The importance of polyethylene wear debris is now fully appreciated, and it is clear that this is the major contributor to particulate debris. The authors strongly recommend the avoidance of 32 mm femoral heads, thin acetabular component liners, titanium heads, and acetabular screws when absolutely necessary. We strongly advise 26 mm to 28 mm femoral heads, polyethylene thickness of at least 8 mm, precise liner shell contact, rigid fixation of the acetabular metal shell, intimate bone-acetabular shell contact, and circumferential porous coating of femoral components to decrease the amount of and migration potential of polyethylene debris (Table). Based on our current knowledge, these measures will minimize the problem of acetabular osteolysis.

Technique for in vivo measurement of the three-dimensional kinematics and laxity characteristics of the ankle joint complex.

We introduce here a technique to measure the three-dimensional kinematics and laxity characteristics of the ankle joint complex in vivo. The system consists of an optoelectric, kinematic data acquisition system that is used to measure the motion of the ankle joint complex in response to controlled moments applied through a system of pneumatic actuators. As a first step toward development of the method into a quantitative diagnostic tool for injuries of ankle ligaments, we addressed the following questions: (a) What is the reliability for measurement of range of motion and laxity of the ankle joint complex? (b) Are there significant differences in laxity between the left and right joints of a healthy individual? and (c) Are there significant differences in laxity of the ankle joint complex between men and women? To answer these questions, we performed repeated measures of range of motion and laxity of paired ankles in a population of 18 healthy young individuals. The high intraclass correlation coefficients obtained from the statistical analysis indicate that the new experimental system is highly reliable in measurement of total range of motion and total laxity of the ankle joint complex. We further concluded that, within the statistical power available in our experimental design, there are no significant differences in either range of motion or laxity between left and right ankles of healthy individuals or between men and women.