Sequential technetium-99m HMDP-gallium-67 citrate imaging for the evaluation of infection in the painful prosthesis.

In order to evaluate the clinical utility of sequential technetium-99m HMDP-gallium-67 scanning in patients with painful orthopedic prosthesis, a retrospective review was made of 154 sequential scans performed in 130 patients. Criteria for a positive study included spatially incongruent gallium-technetium uptake or gallium uptake that was congruent but more intense than technetium. Images were interpreted as negative if gallium was congruent and less intense than technetium. Sixty-six patients underwent surgery (31 infected, 35 aseptic), and 64 were evaluated clinically (3 infected, 61 aseptic). The combined results of the surgical and nonsurgical patients yielded a sensitivity of 66%, a specificity of 81%, and an accuracy of 77%. In this series, the technetium-gallium scan combination has proven to be helpful but more recent techniques such as indium-111-labeled leukocytes may prove to be superior to sequential technetium-gallium imaging.

Energy expenditure in patients with low-, mid-, or high-thoracic paraplegia using Scott-Craig knee-ankle-foot orthoses.

Renewed interest in ambulation in patients with paraplegia prompted us to measure the energy expenditure (kcal/kg per min) during standing and ambulating with the Scott-Craig orthosis in nine patients who had low-, mid-, or high-thoracic paraplegia. Energy expenditure during standing and during ambulation with a walker was similar for patients with all levels of paraplegia. In patients with high-thoracic paraplegia, energy efficiency was significantly less (P less than 0.05) than that for patients with mid- or low-thoracic paraplegia, whose efficiency levels were similar. In patients with low-thoracic paraplegia, the only patients who could perform swing-through gait patterns, energy efficiency was increased because of increased velocity. Our data do not support the concept of denying, on the basis of the level of the lesion alone, young, otherwise healthy, well-motivated patients with thoracic paraplegia the opportunity of using Scott-Craig orthoses to supplement wheelchair mobility and activities of daily living.

Prevention of spinal cord injury after transient aortic clamping with tissue factor pathway inhibitor.

BACKGROUND: Lower limb paralysis that occurs in 11% of patients after treatment of thoracic and thoracoabdominal aortic aneurysms is unpredictable and at present not preventable. The proposed cause for the neurologic changes is believed to be spinal cord ischemia combined with ischemia/reperfusion injury. Recombinant tissue factor pathway inhibitor (rTFPI), a multivalent Kunitz-type inhibitor that binds to tissue factor-VIIa complex, was evaluated. METHODS: The effectiveness of rTFPI as an agent to limit spinal cord ischemia/reperfusion injury was studied in a rabbit spinal cord made ischemic for 20 minutes. rTFPI or phosphate-buffered saline solution (control) was given in randomized blinded fashion at the onset and conclusion of ischemia. Animals underwent neurologic evaluation at 24 hours in a blinded fashion with a modified Tarlov Scale to rate the lower limb paralysis (score of 4 = normal function, score of 0 = complete paralysis). RESULTS: Seventy-five percent of the TFPI-treated animals had Tarlov scores of 3 to 4, whereas only 29% of the animals treated with phosphate-buffered saline solution had such scores (p < 0.0014). Spinal cord histologic findings correlated with the neurologic findings. CONCLUSIONS: We believe that TFPI has unique inhibitory properties that make it an effective agent in limiting postoperative paraplegia associated with spinal ischemia.

Supracondylar fracture of the femur after total knee arthroplasty.

We reviewed the data on thirty-six supracondylar fractures of the femur (in thirty-four patients) that occurred after total knee arthroplasties that were done between April 1974 and December 1981. Patients who had osteoporosis, rheumatoid arthritis, one or more previous arthroplasties of the knee, or inadvertent breeching of the anterior aspect of the femoral cortex at operation appeared to be particularly at risk for a supracondylar femoral fracture. Malalignment of the component could not be implicated as a cause. Twenty-six fractures (in twenty-five patients) were treated by non-operative methods. Seventeen of them (65.4 per cent) healed and required no surgical treatment. Fourteen of the seventeen were followed for more than two years; they had no significant difference in the knee score and lost less than 10 degrees of motion. The nine remaining knees required revision of the arthroplasty because of non-union in four knees, malunion in two, loosening of the component in two, and extension lag in one. At an average of forty months after revision, the nine knees were rated as having one excellent, four good, three satisfactory, and one failed result. In contrast, only three of the five fractures that were treated by early open reduction and internal fixation had a satisfactory result, and one of them required a second bone-grafting procedure. One patient died perioperatively and another required an above-the-knee amputation because of sepsis. Of the three fractures that were initially treated by external fixation, one had an excellent and two had a good result at an average of forty-five months after fracture. We have found that supracondylar fractures that occur after total knee arthroplasty can be managed by either traction or application of a cast, or both, which usually results in healing of the fracture and a satisfactory outcome of the arthroplasty. Patients who have a poor arthroplasty result after non-operative treatment of the fracture usually can undergo a revision arthroplasty with the expectation of a satisfactory outcome. Operative treatment of the fracture should be reserved for patients who do not have osteopenia and in whom stable fixation can be achieved, for those who demand a highly functional arthroplasty, and for those in whom adequate closed reduction cannot be maintained.

Comparison of indium-labeled-leukocyte imaging with sequential technetium-gallium scanning in the diagnosis of low-grade musculoskeletal sepsis. A prospective study.

We prospectively compared sequential technetium-gallium imaging with indium-labeled-leukocyte imaging in fifty patients with suspected low-grade musculoskeletal sepsis. Adequate images and follow-up examinations were obtained for forty-two patients. The presence or absence of low-grade sepsis was confirmed by histological and bacteriological examinations of tissue specimens taken at surgery in thirty of the forty-two patients. In these thirty patients, the sensitivity of sequential Tc-Ga imaging was 48 per cent, the specificity was 86 per cent, and the accuracy was 57 per cent, whereas the sensitivity of the indium-labeled-leukocyte technique was 83 per cent, the specificity was 86 per cent, and the accuracy was 83 per cent. When the additional twelve patients for whom surgery was deemed unnecessary were considered, the sensitivity of sequential Tc-Ga imaging was 50 per cent, the specificity was 78 per cent, and the accuracy was 62 per cent, as compared with a sensitivity of 83 per cent, a specificity of 94 per cent, and an accuracy of 88 per cent with the indium-labeled-leukocyte method. In patients with a prosthesis the indium-labeled-leukocyte image was 94 per cent accurate, compared with 75 per cent accuracy for sequential Tc-Ga imaging. Statistical analysis of these data demonstrated that the indium-labeled-leukocyte technique was superior to sequential Tc-Ga imaging in detecting areas of low-grade musculoskeletal sepsis.

Scintigraphic evaluation in musculoskeletal sepsis.

In this article, the mechanism of technetium, gallium, and indium-labeled white blood cell localization in septic processes is detailed, and the method of interpretation of these three isotopes with relationship to musculoskeletal infection is outlined. Specific clinical application of technetium, gallium, and indium-labeled white blood cell imaging for musculoskeletal sepsis is reviewed.

Optical coherent transient header/data isolation technique.

We experimentally demonstrate a novel, all-optical technique that spatially isolates two parts of a temporally encoded optical information stream from each other by means of spatial-spectral holographic technology. A brief reference pulse is applied to an inhomogeneously broadened absorber [Tm(3+):YAG (0.1 at. %) at ~4.4 K] in the direction opposite that of the information stream, overlapping it on a boundary between the two temporal parts to be isolated (i.e., the header and the data). Another brief reference pulse subsequently applied in the opposite (the same) direction as that of the information stream results in an emitted optical output that mimicks only the part of the information stream that follows (precedes) the first reference pulse in a timeforward (time-reversed) fashion, completely isolated from the other part.

Optical coherent-transient true-time-delay regenerator.

We propose a novel all-optical true-time-delay regeneration technique that is well suited for control of phasedarray antennas with time-delay beam steering. Using coherent transients, this versatile technique has the ability to regenerate a variable delay onto an optical waveform of arbitrary shape and high bandwidth. We performed simulations indicating that future research could extend the delay resolution to the subpicosecond regime. We also present proof-of-concept experimental results for a true-time-delay regenerator combined with signal processing.

Coherent transient optical signal processing without brief pulses.

The temporal processing operations of convolution and correlation are demonstrated through optical coherent transient techniques, in which two long, low-intensity frequency-chirped pulses replace the single, brief reference pulse of a traditional three-pulse excitation sequence (brief pulse, pattern pulse, and data pulse). Here, a four-pulse excitation sequence is used (two frequency-chirped pulses, pattern pulse, and data pulse) in which the particular order and timing of the chirped pulses with respect to the other waveforms determine the processing operation. An experiment is performed with biphase-coded pattern and data pulses to demonstrate both the correlation and the convolution operations. A new atomic rephasing process that we call delayed rephasing is demonstrated.

Isolated congenital pseudarthrosis of the fibula: report of a case and review of the literature.

A child with isolated congenital pseudarthrosis of the fibula and progressive valgus ankle deformity was successfully treated by reconstruction of the fibular diaphysis with bone graft.

Chirped-pulse programming of optical coherent transient true-time delays.

Programming an optical coherent transient true-time delay device with two frequency-chirped pulses provides a novel means of performing broadband (> >GHz) true-time delay with a wide dynamic range of delays with fine temporal resolution. We have demonstrated true-time delays exceeding 2micros with sub-100-ps resolution. Chirped-pulse programming has the advantages over the previously proposed brief pulse programming [Opt. Lett. 21 1102 (1996)] of reduced instantaneous power requirements and the ability to control the true-time delay by frequency shifting the programming pulses.

Optical coherent transient continuously programmed continuous processor.

A novel technique for continuously programming an optical coherent transient spatial-spectral signal processor is proposed. The repeated application of two spatially distinct optical programming pulses to a nonpersistent hole-burning material writes an accumulated spatial-spectral population grating. An optical data stream is introduced on a third beam, resulting in a processor output signal that is spatially distinct from all the input pulses. Programming and processing take place simultaneously, asynchronously, and continuously. In the case of true-time delays, the efficiency that is achievable with currently available materials is of the order of that predicted for a perfect photon-gated device.

A 30-year-old man with a mass in the distal left thigh and radiating leg pain.

The following case describes the imaging and clinical findings of a condition of interest to the orthopaedic surgeon. Initial history, physical findings, and imaging examinations are presented here for your consideration. The final clinical diagnosis and relevant discussion can be found on the following pages.

Rotationplasty as a reconstructive operation after tumor resection.

Reconstruction in the skeletally immature patient following resection of osteosarcoma about the knee is a challenging problem. Salvaging of the limb with allogeneic or prosthetic replacement results in a shortened limb with functional limitations. Arthrodesis yields a stiff and shortened limb. The so-called growing prosthesis has a high complication rate and is still unproven. However, rotationplasty has been successfully used as a reconstructive technique following resection of these types of tumors in the skeletally immature patient. A limb with normal sensation and proprioceptions, adequate range of motion, and without leg-length discrepancies, functional limitations, or painful neuroma is to be expected. Although a prosthesis must be worn, these patients are active and participate in unrestricted physical activity. Cosmetic acceptance has not been a problem and complications are minimal. Thus, rotationplasty requires only a single operation and results in a highly functional limb.

Mitchell osteotomy for hallux valgus: long-term follow-up and gait analysis.

In this retrospective study of 96 Mitchell first-metatarsal osteotomies performed on 69 patients with an average follow-up of 7 years, we found that more than 86% were completely satisfied and that the procedure was equally effective in all age groups. Excessive first metatarsal shortening, dorsiflexion of the osteotomy, and failure to correct the intermetatarsal angle to 10 degrees or less correlated with poorer results. This study demonstrates a relationship between metatarsal shortening and osteotomy plantarflexion. Gait analysis demonstrated that these patients do not have normal foot mechanics postoperatively.

Energy expenditure of paraplegic patients standing and walking with two knee-ankle-foot orthoses.

To determine which kind of knee-ankle-foot orthosis (KAFO) is more efficient, we measured energy expenditure in standing, walking with a walker, and walking with crutches by eight subjects using the Scott-Craig KAFO and a single-stopped long-leg KAFO. All subjects had complete motor paralysis below the level of their lesion and had been fully trained to use KAFOs. Every subject used both types of KAFO, and energy expenditure--per minute and per meter traveled--was measured by oxygen consumption. No significant difference in energy expenditure appeared during standing. During ambulation, however, mean energy expenditure was less with the Scott-Craig KAFO than with the single-stopped type: 31% less kcal/m with a walker and 25% less kcal/min with crutches. These results suggest that the Scott-Craig KAFO is more energy-efficient than the single-stopped long-leg KAFO.

Paraplegic energy expenditure during negotiation of architectural barriers.

Long-leg braces are often used by persons with paraplegia to negotiate architectural barriers, and thereby increase their wheelchair mobility. Such barriers include ramps, stairways, and narrow corridors requiring multiple turns. This study was designed to measure the energy expenditure during such activities for two long-leg orthoses: standard braces without a dorsiflexion stop and Scott-Craig braces. Energy expenditure was measured in eight subjects by indirect spirometry using Douglas bag collection and Haldane analysis. Data obtained were used to calculate oxygen consumption per minute, volume of oxygen per turn, step, or meter, and calories per minute during each activity. Using Scott-Craig braces on one day and standard braces on another day, each subject negotiated five 90 degrees turns and two 180 degree turns, ten 15.24 cm steps, both up and down, and an 11.9 m ramp inclined 12 degrees, both up and down. Milliliters of oxygen consumed per kilogram of body weight per turn, step, or meter were recorded for Scott-Craig braces, standard braces, and normal walking. All of these activities required a high expenditure of energy. No significant difference was apparent between the standard and the Scott-Craig braces for any activity.

Variable-time-delay optical coherent transient signal processing.

A technique is proposed and experimentally demonstrated that achieves simultaneous optical pattern waveform storage and programmable time delay for continuous real-time signal processing by use of optical coherent transient technology. We achieve variable-time-delay and broadband signal processing by frequency shifting of two chirped programming pulses, the chirp rate of one being twice that of the other, without using brief reference pulses and without changing the timing of the programming sequence. We demonstrate the technique experimentally in Tm(3+): YAG at 5 K for 40-MHz chirps by performing temporal signal convolution with true-time delays that vary over a 250-ns range.

Modification of the Van Nes rotationplasty: report of a case.

Rotationplasty is a reconstructive option that provides a highly functional limb after tumor resection about the knee in the skeletally immature patient. However, in the very young child with large intramedullary extension of the tumor, leg length may not be possible to maintain. Described is a modification of the Van Nes rotationplasty that preserves the proximal tibial physis, allowing maximization of future growth.

Tumor necrosis factor-alpha mediates orthopedic implant osteolysis.

Osteolysis complicating arthroplasty reflects progressive generation of implant-derived wear particles, which prompt an inflammatory reaction attended by recruitment of osteoclasts to the prosthesis-bone interface. To identify a soluble mediator of periprosthetic osteolysis we first showed that implant particles induce c-src in murine bone marrow macrophages (BMMs), a protein specifically expressed when these cells commit to the osteoclast phenotype. The fact that tumor necrosis factor-alpha (TNF) is a potent osteoclastogenic agent while at the same time is the only soluble moiety known to be c-src inductive suggests that this cytokine may mediate implant particle-induced osteoclastogenesis. Consistent with this hypothesis, prosthesis-derived wear particles, recovered at revision arthroplasty, dose-dependently prompt TNF secretion by BMMs. Similarly, particulate polymemthylmethacrylate, the major component of orthopedic implant cement, induces BMM expression of TNF mRNA and protein in a time- and dose-dependent manner. Furthermore, failure of BMMs derived from mice deleted of both the p55 and p75 TNF receptors to express c-src in response to polymemthyl-methacrylate indicates TNF is an essential mediator of particle induction of this osteoclast specific protein. To test the hypothesis that TNF mediates implant osteolysis, we established an in vivo murine model of this condition that histologically mirrors that of man. Verifying that TNF is essential to development of particle osteolysis, mice failing to express both the p55 and p75 TNF receptors are protected from the profound bone resorption attending polymemthyl-methacrylate particle implantation on calvariae of wild-type animals. Finally, the protective effect of deletion of both TNF receptors is recapitulated in mice lacking only the p55 receptor. Thus, targeting TNF and/or its p55 receptor may arrest wear particle osteolysis.