Indium-111-leukocyte/technetium-99m-MDP bone and magnetic resonance imaging: difficulty of diagnosing osteomyelitis in patients with neuropathic osteoarthropathy.

Fourteen patients (16 sites) with clinical and/or radiographic evidence of neuropathic osteoarthropathy (Charcot joints) were evaluated with combined indium-111-leukocyte (111In-WBC) and technetium-99m-methylene diphosphonate (99mTc-MDP) bone imaging for suspected osteomyelitis. Magnetic resonance (MR) images were obtained in seven patients. Using a positive bone culture as the criterion for the presence of osteomyelitis, there were four true-positive studies, six true-negative sites, and one false-negative 111In-WBC study. Five of 16 sites (31%) had false-positive 111In-WBC uptake at noninfected sites. There were four true-positive and three false-positive MR studies. All false-positives showed at least moderately abnormal findings by both techniques at sites of rapidly progressing osteoarthropathy of recent onset. In this preliminary study, both techniques appear to be sensitive for detection of osteomyelitis, and a negative study makes osteomyelitis unlikely. However, the findings of 111In-WBC/99mTc-MDP and MR images at sites of rapidly progressing, noninfected neuropathic osteoarthropathy may be indistinguishable from those of osteomyelitis.

Contact stress aberrations following imprecise reduction of simple tibial plateau fractures.

Despite the well-recognized association between poorly reduced intraarticular fractures and late degenerative changes, current guidelines regarding the reduction precision necessary to avoid excessive cartilage pressures are based largely on anecdotal clinical observations. To gain a quantitative appreciation of the relation between local pressure elevations and fracture reduction imprecision, a simplified laboratory cadaver model of minimally displaced tibial plateau fractures was developed. Cartilage contact stress distributions were measured as a function of depressed fragment malreduction in seven knees, using high-resolution (100 pixels/mm2) digital image scans of Fuji-film stain patterns. The contact stress data showed a general trend of increases of peak local pressure with increasing fracture site incongruity, and in a few isolated instances the effect was very pronounced. Across the whole series, however, statistically significant departures from anatomic pressure levels did not occur until the fragment stepoff was greater than 1.5 mm. Even at the 3-mm stepoff level, for which the depressed fragment usually no longer made contact with the femoral condyle, the peak local pressure values on the intact side of the fracture line averaged only approximately 75% greater than those prevailing anatomically. Given the successful clinical outcomes normally achieved for conservatively managed simple tibial plateau fractures having stepoff magnitudes (5-10 mm) clearly sufficient to insure fragment articular noncontact, the present laboratory results suggest that nominally factor-of-two peak local pressure elevations, provided that they occur over only small portions of the cartilage surface, are probably within the long-term overall tolerance range of an articular joint.

Use of an articulated external fixator for fractures of the tibial plafond.

We performed a prospective study of forty-nine displaced fractures of the tibial plafond in forty-eight patients managed, at three centers, with an articulated external fixator placed medially across the ankle joint. Forty ankles had interfragmental screw fixation of a reduced articular fracture, and fourteen ankles had bone-grafting. The average duration of external fixation was twelve weeks. All of the fractures healed (one after delayed bone-grafting). There were no infections in any of the operative or traumatic wounds over the tibia. Two wound infections over the fibula resolved with treatment. Eight patients were managed with antibiotics for a pin-site infection, and two patients had curettage and débridement of a pin site in the hindfoot after removal of the fixator. Thirty patients (thirty-one ankles) completed two-year data sheets at an average of thirty months after the injury. The average ankle score was 67 points. Twenty-one patients had grade-0 or 1 osteoarthrosis and nine had grade-2 or 3. One ankle had been treated with an arthrodesis. These data suggest that the prevalence of early complications associated with severe fractures of the tibial plafond and their treatment can be decreased with use of an articulated external fixator combined with limited internal fixation. We concluded that this technique of external fixation is a satisfactory technique for the treatment of these fractures.

Diagnosis of infection in ununited fractures. Combined imaging with indium-111-labeled leukocytes and technetium-99m methylene diphosphonate.

The results of combined scintigraphy in which indium-111-labeled leukocytes and technetium-99m methylene diphosphonate were used were compared with the results of cultures of open bone at 102 sites of delayed union or non-union, to determine the effectiveness of this combination as a preoperative indicator of osteomyelitis. There were twenty-five true-positive, fifty-nine true-negative, eleven false-positive, four false-negative, and three indeterminate interpretations, yielding, for the diagnosis of osteomyelitis, a sensitivity of 86 per cent, a specificity of 84 per cent, an accuracy of 82 per cent, a positive predictive value of 69 per cent, and a negative predictive value of 94 per cent. There were few false-negative scans; false-positive results were most likely at a metaphyseal site adjacent to a joint in which there was post-traumatic arthropathy, at the site of a failed arthrodesis, and at the site of an unstable delayed union or non-union.

Focal osteolysis at the junctions of a modular stainless-steel femoral intramedullary nail.

BACKGROUND: During routine follow-up of patients treated with a three-piece stainless-steel modular femoral nail, osteolysis and periosteal reaction around the modular junctions of some of the nails were noted on radiographs. The purpose of this study was to evaluate the prevalence, etiology, and clinical relevance of these radiographic findings. METHODS: Forty-four femoral fractures or nonunions in forty-two patients were treated with a modular stainless-steel femoral intramedullary nail. Seventeen nails were excluded, leaving twenty-seven intramedullary nails in twenty-seven patients for this study. All patients had had a femoral diaphyseal fracture; nineteen had had an acute fracture and eight, a nonunion. These twenty-seven patients returned for radiographs, a physical examination, assessment of functional outcomes, assessment of thigh pain with a visual analog scale, determination of serum chromium levels, and nail removal if desired. A control group of sixteen patients treated with a one-piece stainless-steel femoral intramedullary nail was evaluated with use of the same outcome measures and was compared with the group treated with the modular femoral nail with regard to prevalence of thigh pain and serum chromium levels. Twelve modular femoral nails were removed according to the study protocol. The modular nail junctions were analyzed for corrosion products, and histopathologic analysis of tissue specimens from the femoral canal was performed. RESULTS: The twenty-seven patients were seen at a mean of twenty-one months after fracture fixation; twenty-six of the twenty-seven fractures healed. Twenty-three femora had at least one of three types of abnormalities-osteolysis, periosteal reaction, or cortical thickening--localized to one or both modular junctions. Eighteen patients had severe reactions, defined as osteolysis of > or =2 mm, cortical thickening of > or =5 mm, and/or a periosteal reaction (group 1). Nine patients had mild or no reactions (group 2). Serum chromium levels in group 1 (mean, 1.27 ng/ mL; range, 0.34 to 3.12 ng/mL) were twice as high as those in group 2 (mean, 0.53 ng/mL; range, 0.12 to 1.26 ng/mL). However, this difference did not reach significance with the numbers available. The differences in serum chromium levels between group 1 and the control group with a one-piece nail (mean, 0.26 ng/mL; range, 0.015 to 1.25 ng/mL) (p<0.01) and a control group without an implant (mean, 0.05 ng/mL; range, 0.015 to 0.25 ng/ mL) (p<0.01) were significant. The level of thigh pain recorded on the visual analog scale was also significantly different between group 1 and the control group with a one-piece implant (p = 0.03). Retrieved modular nails had signs of fretting corrosion as well as stainless-steel corrosion products adherent to the junction where the osteolysis occurred. Histologic and spectrographic analysis revealed two types of corrosion products that were consistent with stainless-steel within the peri-implant tissue and were associated with a foreign-body granulomatous response. CONCLUSIONS: The presence of corrosion products at the taper junctions suggests that particulate debris was a major factor in the etiology of the radiographic findings of osteolysis, periosteal reaction, and cortical thickening. Serum chromium levels were substantially elevated in the patients with a modular femoral nail, and such levels may serve as a marker of fretting corrosion of these devices.

Comparative study of the Orthofix and Pittsburgh frames for external fixation of unstable pelvic ring fractures.

We compared the mechanical performance of the Orthofix pelvic external fixator with that of the Pittsburgh triangular frame (PTF) on eight fresh-frozen cadaver pelves with experimentally created Malgaigne (double-vertical) fracture/dislocations. The pelves were quasi-statically loaded in longitudinal compression and loss of reduction (i.e., failure) was defined as 1.5 cm of diastasis at either of the fracture/dislocation sites. The Orthofix frame-pelvis complex (four 6-mm half-pins) was comparable to the PTF-pelvis complex (eight 5-mm half-pins) in terms of load to failure and overall stiffness, but was 4-7 times stiffer at lower load levels. Both frame-and-pin complexes deformed moderately at the pin-bone interface, but, while the PTF also showed moderate displacement between frame components, the Orthofix had almost no frame intercomponent motion.

Mechanical analysis of the factors affecting dynamization of the Orthofix Dynamic Axial Fixator.

Loading trials were conducted to identify mechanical factors affecting dynamization of a commercially available external fixator (Orthofix) that is designed to undergo free telescopic motion when axially loaded. Angular variations between the proximal and distal screw clamps and the telescoping fixator body failed to produce fixator binding (failure to dynamize) in any of the loading trials. However, binding was produced by applying external torques in magnitudes that occasionally occur during routine ambulation. The specific torque necessary to induce binding (typically 3-4 Nm) was only a weak function of axial load magnitude, axial loading frequency, or simulated fracture stiffness. Among several geometrical variables of fixator application, only the pre-extension of the telescoping body and circumferential misalignment between proximal and distal pin clusters had an appreciable influence on the threshold binding torque. Axial fixator motions were also monitored in a small adjunct clinical series of 22 dynamized tibial fractures. The fixator dynamized appropriately in 15 cases (68%). Three patients (14%) showed evidence of fixator binding, and another four (18%) had less than predicted slider excursions. The role of several design factors implicated in torque-induced fixator binding is discussed in light of the benchtop and clinical observations.

Unilateral external fixation until healing with the dynamic axial fixator for severe open tibial fractures.

One hundred one cases of open tibia fractures were treated until healing with a unilateral external fixation device that permits fracture site compression with weight bearing. There were 38 type II and 63 type III (24 IIIA, 33 IIIB, six IIIC) open fractures. A standard protocol was followed including irrigation and debridement and, when necessary, flap coverage (19 cases) and bone grafting (31 cases). Fixators were applied at the first debridement and removed when the fracture was healed. All patients were permitted early partial weight bearing and progressed to full weight bearing with fixator dynamization. Ninety-six cases healed in the fixator (12-50 weeks; average, 24.6). Three of the five failures were associated with screw complications. Five patients required screw changes and 29 required oral antibiotic therapy for screw complications. Ninety-five percent of healed cases had angulation of less than 10 degrees (in any plane). There were only six fracture site infections during the course of treatment. Dynamic axial fixation may be applied at the first debridement and be used until healing in severe open tibia fractures. Change of the fixator to another treatment method is not required.

Radiographic fracture assessments: which ones can we reliably make?

OBJECTIVE: To identify the fracture characteristics that can be reliably assessed by analysis of plain radiographs of tibial plateau fractures. DESIGN: Radiographic review study. PARTICIPANTS: Five orthopaedic traumatologists served as observers. INTERVENTION: Observers made assessments based on the radiographs of fifty-six tibial plateau fractures. Precise definitions of the assessments to be made were agreed on by all observers. The tested assessments included raters' abilities to identify and locate fracture lines, identify the presence of fracture displacement and comminution, make quantitative measurements of displacement, and characterize qualitative features of fractures. For thirty-eight of the fractures that had a computed tomography (CT) scan available, assessments were repeated using both radiographs and CT scans. MAIN OUTCOME MEASURES: To characterize interobserver reliability, percentage agreement and kappa statistics were calculated for categorical variables, and intraclass correlation coefficients (ICC) were calculated for noncategorical variables. RESULTS: Reliability of the assessments varied widely. Determining the location of fracture lines had the greatest reliability, whereas the subjective assessments of fracture stability and energy showed the poorest reliability. Although the ICCs for quantitative measurements approached acceptable levels, the tolerance limits were extremely wide. The addition of a CT scan improved the reliability of most assessments, but not to a statistically significant degree. CONCLUSIONS: Many basic radiographic interpretations relied on in making treatment decisions are made variably by observers. Using experienced raters and precise definitions of fracture assessments does not guarantee a high level of agreement. Discrete assessments have higher interrater agreements than do more qualitative assessments. Quantitative measures have wide tolerance limits and, therefore, probably cannot be used reproducibly to classify fractures or make treatment decisions. We conclude the reliability of fracture classification is limited by raters' abilities to agree on basic radiographic assessments.

Clinical failure after posterior wall acetabular fractures: the influence of initial fracture patterns.

OBJECTIVE: To determine radiographic and clinical features that predict rapid failure after open reduction and internal fixation of posterior wall acetabular fractures. DESIGN: Retrospective radiographic review and patient follow-up study. SETTING: University hospital. PATIENTS: Forty-two patients with posterior wall acetabular fractures. INTERVENTION: Open reduction and internal fixation. MAIN OUTCOME MEASURES: Radiographs, Merle D'Aubigné scores, Musculoskeletal Functional Assessment. RESULTS: Eleven patients had complete loss of joint space by one year postinjury; eight of these individuals required reconstructive surgery. These patients more commonly had fractures with comminution of three fragments or more (p = 0.001) or fracture into the subchondral arc at the level of the acetabular roof (p = 0.045). CONCLUSION: Poor outcomes after open reduction and internal fixation are associated with certain types of posterior wall fracture patterns.

Effects of pulsed electromagnetic fields on bone healing in a rabbit tibial osteotomy model.

OBJECTIVE: The purpose of this study was to determine the effect of pulsed electromagnetic field (PEMF) exposure on healing tibial osteotomies in New Zealand White rabbits. DESIGN: One-millimeter Gigli saw osteotomies were stabilized by external fixation. One day after surgery, rabbits were randomly assigned to receive either no exposure (sham control) or thirty minutes or sixty minutes per day of low-frequency, low-amplitude PEMF. Radiographs were obtained weekly throughout the study. Rabbits were euthanized at fourteen, twenty-one, or twenty-eight days, and tibiae underwent either destructive torsional testing or histologic analysis. To determine the baseline torsional strength and stiffness of rabbit tibiae, eleven normal intact tibiae were tested to failure. RESULTS: Sixty-minute PEMF-treated osteotomies had significantly higher torsional strength than did sham controls at fourteen and twenty-one days postoperatively. Thirty-minute PEMF-treated osteotomies were significantly stronger than sham controls only after twenty-one days. Normal intact torsional strength was achieved by fourteen days in the sixty-minute PEMF group, by twenty-one days in the thirty-minute PEMF group, and by twenty-eight days in the sham controls. Maximum fracture callus area correlated with the time to reach normal torsional strength. CONCLUSION: In this animal model, low-frequency, low-amplitude PEMF significantly accelerated callus formation and osteotomy healing in a dose-dependent manner.

Effects of imposed hindfoot constraint on ankle contact mechanics for displaced lateral malleolar fractures.

Contact stress distributions on the tibial plafond were mapped in a series of eight fresh-frozen cadaver specimens in which displaced lateral malleolar fractures were studied. These included gripping (a) by snugly lacing the foot in an athletic shoe, (b) by polymethylmethacrylate potting of the calcaneus alone, and (c) by potting of the calcaneus plus talus. Each of these three gripping conditions was tested both for rigid and for nearly frictionless transverse external constraint conditions. Across the series, the grip-dependent changes in contact stress distributions were found to be very minor compared with the wide interspecimen variability that was consistently present. Moreover, although contact stresses generally increased with progressive lateral fibular fragment offsets of up to 5 mm, such an effect was far more modest than that seen in previous cadaver work. The present laboratory cadaver findings suggest that the contact stress elevations occurring clinically for displaced lateral malleolar fractures are probably relatively mild and likely not directly responsible for late secondary degeneration.

External fixation of tibial plafond fractures: is routine plating of the fibula necessary?

OBJECTIVES: To determine the advantages and disadvantages of plating an associated fibula fracture in tibial plafond fractures treated with external fixation that spans the ankle. STUDY DESIGN: Retrospective clinical review. METHODS: The incidence of treatment complications and the outcomes achieved were compared between two groups of patients with tibial plafond fractures and associated fractures of the fibula. Both groups were treated by a uniform technique of monolateral external fixation. One group, consisting of twenty-two patients with twenty-two fractures, had plate fixation of the distal fibula and the other group, thirty-one patients with thirty-two fractures, had no fibular fixation. RESULTS: The demographics of the two groups, including sex, fracture classification, and number of open fractures, were similar. The outcome of the two groups for radiographic arthrosis and clinical ankle score, measured at minimum two-year follow-up, showed no statistically significant difference. The total numbers of complications were not statistically different between the two groups (p = 0.15), but the types of complications varied. Group I had eight complications: five fibular wound infections, two fibular nonunions, and one angular nonunion. Group II had seven complications: six angular malunions and one tibial wound infection. CONCLUSION: Open reduction and internal fixation of the fibula fracture in tibial plafond fractures treated with external fixation that spans the ankle is associated with a significant rate of complications, and good clinical results may be obtained without fixing the fibula.

Rank order analysis of tibial plafond fractures: does injury or reduction predict outcome?

We investigated the effects of severity of initial injury pattern and the quality of the articular reduction on outcome of displaced intra-articular distal tibial fractures, using a series of 25 patients who were treated with articulated external fixation and limited internal fixation, which provided a spectrum of reduction quality. Outcome was assessed by clinical ankle scores and radiographic arthrosis. The results demonstrate the rank order method to be a reliable means of stratifying severity of injury and quality of reduction. Neither injury nor reduction correlated with clinical ankle score. Reduction had a significant correlation with radiographic arthrosis. We conclude that the rank order method is useful in stratification of fracture patients, and that factors other than injury pattern and quality of articular reduction are important in determining outcome of patients with this severe articular injury.

External fixation for open tibia fractures. A management strategy.

The management of open tibia fractures with the Dynamic Axial Fixator, including the method of application and postoperative care, is described. This fixator is utilized until healing. Weight bearing and axial fracture site movement promote an early callus response. The results obtained in the first 35 cases in which it was used at our institution are presented. Thirty-three of the fractures were successfully treated until healing in the external fixator.

Imaging techniques for evaluation of postoperative orthopedic infections.

Labeled leukocyte scintigraphy is the preferred imaging technique for the evaluation of suspected postoperative orthopedic infections. Labeled leukocyte localization returns to a normal pattern faster than MRI after bone trauma, surgical procedures, and treatment of osteomyelitis. 99mTc HMPAO labeled leukocyte scintigraphy is useful, particularly in children, because less peripheral blood volume is required for labeling. However, delayed 16-20 hour imaging is usually needed to detect low-grade osteomyelitis, and 111In WBC usually provides better images in adults. Combined 111In WBC/99mTc sulfur colloid marrow images improve the specificity for detection of osteomyelitis in regions containing active bone marrow. Simultaneous 111In leukocyte/99mTc bone SPECT imaging is usually necessary in regions such as the skull, spine, and hips, where there is overlapping bone, and soft tissues.

Ankle dislocation without fracture.

Dislocation of the ankle without accompanying malleolar fracture has been regarded as a rare lesion, with few cases reported in the literature. To date, there has been no precedent for accurate descriptions of the mechanisms, optimum treatment, and long-term prognosis of this injury. Our goal was to evaluate these variables by a retrospective review of cases from our institution. We identified eight patients who had sustained ankle dislocation without fracture and were treated at the University of Iowa during the period 1958 to 1986. We interviewed and examined each patient and obtained ankle radiographs at an average of 11.5 years postinjury (range 2 to 24 years). After analyzing our cases and other reported in the literature, we have found that this injury is most common in young people (average age 31 years, range 10 to 73 years) and males (72%), and occurs most frequently in falls, motor vehicle accidents, and sports (86%). Medial displacement occurs most frequently (27%). Disruption of the mortise occurs variably. The most likely mechanism appears to be anterior or posterior extrusion of the talus from the mortise secondary to a force applied to the plantarflexed foot. Final displacement is then determined by the position of the foot and the direction of the force applied. Physical findings are commensurate with the deformity. Neurovascular compromise is uncommon (10%). Closed reduction is almost invariably accomplished easily unless the deformity is accompanied by posterior tibiofibular dislocation. Optimum treatment appears to be immobilization in a short leg cast for 6 weeks with no weightbearing for the first 3 weeks. Long-term follow-up revealed the following. Results were all good to excellent considering the following variables: return to work and sports activities, pain, instability, swelling, and ankle and subtalar joint motion. No patient reported instability and all returned to work and sports participation. We noted mild pain and swelling that was not severe enough to require medication in 25% of patients. Range of motion was normal in all but four patients; none of these lacked more than 10 degrees of motion in any plane. Radiographic abnormalities consisted of minor ligamentous or capsular calcification in all patients, small osteophytes in four patients, and minimal joint space narrowing in one patient. No patient had normal radiographs.

Dynamic external fixation for stabilization of nonunions.

Twenty-five long-bone nonunions were stabilized until healing with a dynamic axial fixator (DAF). Seventeen cases were culture positive and ten had open draining wounds. Five cases had segmental gaps larger than 3 cm. In addition to the DAF, infected atrophic cases received debridement, coverage, and bone graft. Cases with segmental gaps were usually treated with massive posterolateral grafts to create a tibiofibular synostosis. Hypertrophic cases received only compression and weight bearing. Bone grafts were performed in 14 cases. The DAF was usually removed after 16-24 weeks of treatment. Twenty of the twenty-five cases were healed at DAF removal and required no further intervention. Nine of the ten hypertrophic cases healed in an average of 18.1 weeks without graft. Thirteen of 15 atrophic cases were bone grafted. Cases with segmental gaps larger than 3 cm were treated with prolonged external fixation to protect maturing grafts, but were still subject to stress fracture after fixator removal.

Cast brace treatment of proximal tibia fractures. A ten-year follow-up study.

The long-term outcome of tibial plateau fractures treated by cast bracing was observed in 29 patients sustaining 30 tibial plateau fractures more than ten years after injury. Clinical and roentgenographic evaluation was performed and showed 61% good results overall. Range of motion averaged 117 degrees. Iowa knee score averaged 71 of 100 possible points. Thirty-two percent of the patients developed moderate or severe roentgenographic posttraumatic degenerative arthritis. Minimally displaced fractures were observed to do very well clinically without roentgenographic evidence of degenerative joint disease after a ten-year follow-up period. Seventy percent of displaced bicondylar fractures developed degenerative joint disease in clinical and roentgenographic evaluation. Cast bracing of minimally displaced fractures gave satisfactory results, whereas cast bracing of more complex fractures produced variable functional results.