Spot and Diffuse Signs: Quantitative Markers of Intracranial Hematoma Expansion at Dual-Energy CT.

Purpose To compare dual-energy CT with iodine quantification to single-energy CT for evaluation of the spot sign for intracranial hematoma expansion. Materials and Methods In this retrospective study, 42 patients (mean age, 66 years ± 15 [standard deviation]; 19 women) were referred for dual-energy CT assessment of intracranial hemorrhage from October 2014 to January 2017. A machine learning approach (naive Bayes classifier) was used to identify iodine markers of extravasation for risk of hematoma expansion. Specificity and sensitivity of these markers were then independently validated in 65 new patients from February 2017 to February 2018. Results Analysis of dual-energy CT images identified two features of iodine extravasation: total iodine concentration within the hematoma (Ih) and focal iodine concentration in the brightest spot in the hematoma (Ibs) as predictors of expansion. The I2 score derived from these features provided a measure of expansion probability. Optimal classification threshold was an I2 score of 20 (95% confidence interval [CI]: 18, 23), leading to correct identification of 39 of 46 (85%; 95% CI: 71%, 94%) of the hematomas on the training set (sensitivity of 79% [11 of 14; 95% CI: 57%, 100%] and specificity of 88% [28 of 32; 95% CI: 76%, 99%]), and 62 of 70 (89%; 95% CI: 79%, 95%) of the hematomas on the validation set (sensitivity of 71% [10 of 14; 95% CI: 48%, 95%] and specificity of 93% [52 of 56; 95% CI: 86%, 100%]). Sensitivity, specificity, and accuracy of conventional spot sign were, respectively, 57% (eight of 14), 90% (29 of 32), and 80% (37 of 46) on the training set and 57% (eight of 14), 83% (47 of 56), and 75% (53 of 70) on the validation set. Conclusion This study identified two quantitative markers of intracranial hemorrhage expansion at dual-energy CT of the brain. The I2 score derived from these markers highlights the utility of dual-energy CT measurements of iodine content for high sensitivity risk assessment. © RSNA, 2018 Online supplemental material is available for this article.

Dual-Energy Head CT Enables Accurate Distinction of Intraparenchymal Hemorrhage from Calcification in Emergency Department Patients.

Purpose To evaluate the ability of dual-energy (DE) computed tomography (CT) to differentiate calcification from acute hemorrhage in the emergency department setting. Materials and Methods In this institutional review board-approved study, all unenhanced DE head CT examinations that were performed in the emergency department in November and December 2014 were retrospectively reviewed. Simulated 120-kVp single-energy CT images were derived from the DE CT acquisition via postprocessing. Patients with at least one focus of intraparenchymal hyperattenuation on single-energy CT images were included, and DE material decomposition postprocessing was performed. Each focal hyperattenuation was analyzed on the basis of the virtual noncalcium and calcium overlay images and classified as calcification or hemorrhage. Sensitivity, specificity, and accuracy were calculated for single-energy and DE CT by using a common reference standard established by relevant prior and follow-up imaging and clinical information. Results Sixty-two cases with 68 distinct intraparenchymal hyperattenuating lesions in which the reference standards were available were included in the study, of which 41 (60%) were confirmed as calcification and 27 (40%) were confirmed as hemorrhage. Sensitivity, specificity, and accuracy of DE CT for the detection of hemorrhage were 96% (95% confidence interval [CI]: 81%, 100%), 100% (95% CI: 91%, 100%), and 99% (95% CI: 92%, 100%) and those of single-energy CT were 74% (95% CI: 54%, 89%), 95% (95% CI: 83%, 99%), and 87% (95% CI: 76%, 94%), respectively. Six of 68 (9%) lesions were classified as indeterminate and three (4%) were misinterpreted with single-energy CT alone and were correctly classified with DE CT. Conclusion DE CT by using material decomposition enables accurate differentiation between calcification and hemorrhage in patients presenting for emergency head imaging and can be especially useful in problem-solving complex cases that are difficult to determine based on conventional CT appearance alone. (©) RSNA, 2016 Online supplemental material is available for this article.

An Electrocorticography Grid with Conductive Nanoparticles in a Polymer Thick Film on an Organic Substrate Improves CT and MR Imaging.

Purpose To develop an electrocorticography (ECoG) grid by using deposition of conductive nanoparticles in a polymer thick film on an organic substrate (PTFOS) that induces minimal, if any, artifacts on computed tomographic (CT) and magnetic resonance (MR) images and is safe in terms of tissue reactivity and MR heating. Materials and Methods All procedures were approved by the Animal Care and Use Committee and complied with the Public Health Services Guide for the Care and Use of Animals. Electrical functioning of PTFOS for cortical recording and stimulation was tested in two mice. PTFOS disks were implanted in two mice; after 30 days, the tissues surrounding the implants were harvested, and tissue injury was studied by using immunostaining. Five neurosurgeons rated mechanical properties of PTFOS compared with conventional grids by using a three-level Likert scale. Temperature increases during 30 minutes of 3-T MR imaging were measured in a head phantom with no grid, a conventional grid, and a PTFOS grid. Two neuroradiologists rated artifacts on CT and MR images of a cadaveric head specimen with no grid, a conventional grid, and a PTFOS grid by using a four-level Likert scale, and the mean ratings were compared between grids. Results Oscillatory local field potentials were captured with cortical recordings. Cortical stimulations in motor cortex elicited muscle contractions. PTFOS implants caused no adverse tissue reaction. Mechanical properties were rated superior to conventional grids (χ(2) test, P < .05). The temperature increase during MR imaging for the three cases of no grid, PTFOS grid, and conventional grid was 3.84°C, 4.05°C, and 10.13°C, respectively. PTFOS induced no appreciable artifacts on CT and MR images, and PTFOS image quality was rated significantly higher than that with conventional grids (two-tailed t test, P < .05). Conclusion PTFOS grids may be an attractive alternative to conventional ECoG grids with regard to mechanical properties, 3-T MR heating profile, and CT and MR imaging artifacts. (©) RSNA, 2016 Online supplemental material is available for this article.

Clinical applications of dual-energy CT in head and neck imaging.

Dual-energy CT provides insights into the material properties of the tissues and can differentiate between tissues that have similar attenuation on conventional, single energy CT imaging. It has several useful and promising applications in head and neck imaging that an otolaryngologist could use to deliver improved clinical care. These applications include metal artifact reduction, atherosclerotic plaque and tumor characterization, detection of parathyroid lesions, and delineation of paranasal sinus ventilation. Dual-energy CT can potentially improve image quality, reduce radiation dose, and provide specific diagnostic information for certain head and neck lesions. This article reviews some current and potential otolaryngology applications of dual-energy CT.

Outpatient falls prevention program outcome: an increase, a plateau, and a decrease in incident reports.

OBJECTIVE: We implemented an outpatient falls guideline in 2008 in the department of radiology. Here, we describe our multiyear experience. MATERIALS AND METHODS: This was a retrospective study conducted between April 2006 and September 2013 to investigate outpatient falls. The span of the study was divided into eight periods. The incident reporting system was searched for the falls and the fall-related variables. RESULTS: A total of 327 falls occurred during 5,080,512 radiology examinations (rate, 0.64/10,000 total examinations). The highest rate was in period 6 (0.83/10,000 examinations). The average for periods 1 and 2 is 0.39/10,000 examinations (37 falls/945,427 examinations), and the average for periods 3-6 is 0.77/10,000 examinations (204 falls/2,656,805 examinations). The average rate for periods 7 and 8 is 0.58/10,000 examinations (86 falls/1,478,280 examinations). There was a statistically significant increase in the total number of falls reported between period 2 and period 3 (p = 0.02). There was a statistically significant decrease in outpatient falls between period 6 and period 7 (p = 0.01). The number of falls among patients 60 years old or older was 177 falls/2,180,093 examinations (rate, 0.81/10,000 examinations), and that among patients younger than 60 years was 150 falls/2,900,419 examinations (rate, 0.52/10,000 examinations), with a statistically significant difference (p = 0.007). Although the rate of falls was higher among female patients, there was no statistically significant difference between the sexes (p = 0.18). CONCLUSION: The outcome of the outpatient falls guideline was characterized by an increase, a plateau, and a decrease in incident reports. The initial increase may be due to the Hawthorne effect. The plateau may represent the value closest to the true incidence. The decrease may represent the effect of the program.

Applications of dual-energy CT in emergency radiology.

OBJECTIVE: Recent technologic advances in MDCT have led to the introduction of dual-energy CT (DECT). The basic principle of DECT is to acquire images at two different energy levels simultaneously and to use the attenuation differences at these different energy levels for deriving additional information, such as virtual monochromatic images, artifact suppression, and material composition of various tissues. CONCLUSION: A variety of image reconstruction and postprocessing techniques are available for better demonstration and characterization of pathologic abnormalities. DECT can provide both anatomic and functional information of different organ systems. This article focuses on the main applications of DECT in emergency radiology.

Arterial Spin Labeling technique and clinical applications of the intracranial compartment in stroke and stroke mimics - A case-based review.

Magnetic resonance imaging perfusion (MRP) techniques can improve the selection of acute ischemic stroke patients for treatment by estimating the salvageable area of decreased perfusion, that is, penumbra. Arterial spin labeling (ASL) is a noncontrast MRP technique that is used to assess cerebral blood flow without the use of intravenous gadolinium contrast. Thus, ASL is of particular interest in stroke imaging. This article will review clinical applications of ASL in stroke such as assessment of the core infarct and penumbra, localization of the vascular occlusion, and collateral status. Given the nonspecific symptoms that patients can present with, differentiating between stroke and a stroke mimic is a diagnostic dilemma. ASL not only helps in differentiating stroke from stroke mimic but also can be used to specify the exact mimic when used in conjunction with the symptomatology and structural imaging. In addition to a case-based overview of clinical applications of the ASL in stroke and stroke mimics in this article, the more commonly used ASL labeling techniques as well as emerging ASL techniques, future developments, and limitations will be reviewed.

Adult tibial shaft fractures - different patterns, various treatments and complications.

BACKGROUND: Tibial Fractures constitute a large number of emergency operations in most trauma centers. There are different approaches for tibial fractures. To our knowledge, there is insufficient evidence to consider post-operative complications in relation to both surgical methods and the types of fractures. Our purpose is to report our experience regarding the efficacy and complications associated with diverse surgical methods of different patterns of tibial shaft fractures in adults. MATERIAL/METHODS: We studied 387 adult patients. The patients' information was registered from the charts and after examination. The methods used were intramedullary interlocking nails, simple intramedullary rods, plating and external fixation. Early and late complications were recorded and by applying the DELPHI method different treatments were compared. Finally, the safest mode of treatment is proposed. RESULTS: In the intramedullary interlocking nails method the most noticeable complication was delayed union and the highest rate of complications was seen in open oblique fractures. In the simple intramedullary rods method the most frequent complication was pain, and in the with butterfly fractures the complications were the most. In the plating method the most frequent complication was pain, and most of the complications were seen in open comminuted fractures. Finally, in the external fixation method the most frequent complication was non-union and complications were the highest in the patients with oblique, comminuted and segmented fractures. CONCLUSIONS: The proposed method to treat transverse, oblique and butterfly fractures is simple intramedullary rods; whereas intramedullary interlocking nails is the better method for comminuted, segmented and spiral fractures.

Pseudo-patella baja after total knee arthroplasty.

BACKGROUND: One of the complications of total knee arthroplasty (TKA) which has not yet been directly addressed is pseudo-patella baja (PPB). True patella baja (PB) is present when the length of the patellar tendon becomes shorter. PPB is present when the patella tendon is not shortened, but the level of the joint line is elevated. This study was conducted to assess PPB in TKA. MATERIAL/METHODS: Sixty patients who had had a primary TKA at our center between 1995 and 2005 were included. The average follow-up was 27.5 months. The Knee Society Scoring (KSS), lateral knee x-rays and the Blackburne-Peel index were used for assessments. RESULTS: Out of the 60 patients, 43 (72%) demonstrated no joint line elevation or patellar tendon shortening (group A). Fifteen patients (25%) had joint line elevation (group B), and both PB and PPB were present in 2 (3%) patients (group C). KSS was lower in groups B and C compared with group A, but this difference was not statistically significant. The average range of motion (ROM) in group A was significantly higher compared with either group B or C, and patients in groups B and C showed significantly more severe pain compared with group A (P<0.001). CONCLUSIONS: PPB is not an uncommon finding after TKA and is associated with a statistically significant decrease in ROM and an increase in pain. Furthermore, KSS in the PPB group was less than in patients without PPB, although the difference was not statistically meaningful.

Epidemiology of adult tibial shaft fractures: a 7-year study in a major referral orthopedic center in Iran.

BACKGROUND: Epidemiologic differences among various fracture sites and within different populations are important as they imply different cultures and lifestyles in each region. One of these fractures is the tibial shaft fracture. Rather few epidemiological studies have been undertaken on this injury. This study was designed to provide an update on various aspects of tibial shaft fractures during 1999-2006 in a referral educational orthopedic center in Iran. MATERIAL/METHODS: The charts of 854 adult patients were evaluated in a cross-sectional study. All the patients were examined and the results were registered. The collated information was classified along with descriptive statistical analysis. RESULTS: The highest frequency of these fractures was seen in the 20-30 year age group in both genders, and women had a higher rate than men in people aged > or =50 years old. The most common cause of fractures was road traffic accidents; 54% of all injuries were closed fractures and 46% were open. The most frequent fracture pattern was comminuted and the fewest were segmented and with butterfly fractures. The most noticeable complication early after treatment was infection and those during at least one year follow-up were pain, nonunion, and delayed union. CONCLUSIONS: The peak frequency of tibial shaft fractures in Iran was one decade higher than in European populations and in those > or =50 years old the rate was higher in women, which was two decades lower than the mentioned populations. Furthermore, in this study in addition to high-energy trauma, low-energy trauma also had a great role.

Delayed effects of sulfur mustard poisoning on CD4+ and CD8+ lymphocytes in Iranian veterans 25 years after exposure.

BACKGROUND: Sulfur mustard is a chemical warfare agent that produces cellular damage via alkylation and protein cross-linking. Sulfur mustard affects the skin, lungs, and eyes, as well as the gastrointestinal, endocrinal, and hematologic systems. We studied the potential delayed toxic effects of sulfur mustard on white blood cells and some of its derivatives including polymorphonuclear lymphocytes and lymphocytes (CD4+ and CD8+) among Iranian veterans, approximately 25 years after exposure. MATERIAL/METHODS: One hundred thirteen sulfur mustard-poisoned veterans registered for this prospective study. Hematologic, immunophenotyping, and flow cytometric evaluations were done to samples from patients as well as 20 healthy age- and sex-matched control volunteers. Hematologic and immunologic variables were compared between both groups of subjects. Values for P less than.05 were considered statistically significant. RESULTS: Total white blood cell count and percentage of polymorphonuclear lymphocytes were significantly higher in sulfur-mustard-exposed veterans than in control subjects (P=0.008 and <0.001). The percentages of total and CD4+ lymphocytes were significantly lower in sulfur-mustard-exposed veterans than they were in control subjects (P=0.008 and P<0.001). CD8+ lymphocyte percentage and CD4+/CD8+ ratio were not significantly different between the 2 groups. CONCLUSIONS: Severe exposure to sulfur mustard may cause long-term damage to the immune system in humans. CD4+ T cells were significantly lower in persons exposed to sulfur mustard. However, there was no statistically significant between-group difference regarding CD8+ T cells. Impaired immunity may be responsible for the increased risk of infections in these patients.

Temporal evolution of vasospasm and clinical outcome after intra-arterial vasodilator therapy in patients with aneurysmal subarachnoid hemorrhage.

Intra-arterial (IA) vasodilator therapy is one of the recommended treatments to minimize the impact of aneurysmal subarachnoid hemorrhage-induced cerebral vasospasm refractory to standard management. However, its usefulness and efficacy is not well established. We evaluated the effect IA vasodilator therapy on middle cerebral artery blood flow and on discharge outcome. We reviewed records for 115 adults admitted to Neurointensive Care Unit to test whether there was a difference in clinical outcome (discharge mRS) in those who received IA infusions. In a subset of 19 patients (33 vessels) treated using IA therapy, we tested whether therapy was effective in reversing the trends in blood flow. All measures of MCA blood flow increased from day -2 to -1 before infusion (maximum Peak Systolic Velocity (PSV) 232.2±9.4 to 262.4±12.5 cm/s [p = 0.02]; average PSV 202.1±8.5 to 229.9±10.9 [p = 0.02]; highest Mean Flow Velocity (MFV) 154.3±8.3 to 172.9±10.5 [p = 0.10]; average MFV 125.5±6.3 to 147.8±9.5 cm/s, [p = 0.02]) but not post-infusion (maximum PSV 261.2±14.6 cm/s [p = .89]; average PSV 223.4±11.4 [p = 0.56]; highest MFV 182.9±12.4 cm/s [p = 0.38]; average MFV 153.0±10.2 cm/s [p = 0.54]). After IA therapy, flow velocities were consistently reduced (day X infusion interaction p<0.01 for all measures). However, discharge mRS was higher in IA infusion group, even after adjusting for sex, age, and admission grades. Thus, while IA vasodilator therapy was effective in reversing the vasospasm-mediated deterioration in blood flow, clinical outcomes in the treated group were worse than the untreated group. There is need for a prospective randomized controlled trial to avoid potential confounding effect of selection bias.

Root-cause analysis and health failure mode and effect analysis: two leading techniques in health care quality assessment.

In this review article, the authors provide a detailed series of guidelines for effectively performing root-cause analysis (RCA) and health failure mode and effect analysis (HFMEA). RCA is a retrospective approach used to ascertain the "root cause" of a problem that has already occurred, whereas HFMEA is a prospective risk assessment tool whose aim is to recognize risks to patient safety. RCA and HFMEA are used for the prevention of errors or recurring errors to create a safer workplace, maintain high standards in health care quality, and incorporate time-saving and cost-saving modifications to favorably affect the patient care environment. The principles and techniques provided here should allow reviewers to better understand the features of RCA and HFMEA and how to apply these processes appropriately. These principles include how to organize a team, identify root causes, seed out proximate causes, graphically describe the process, conduct a hazard analysis, and develop and implement potential action plans.

Post-dural Puncture Headache: A Comparison Between Median and Paramedian Approaches in Orthopedic Patients.

BACKGROUND: Post-dural puncture headache (PDPH) is an iatrogenic complication of spinal anesthesia. Reported risk factors for PDPH include sex, age, pregnancy, needle tip shape and size, bevel orientation, approach and others. Little is known regarding the effect of different approaches on the incidence of PDPH. OBJECTIVES: In this study we aimed to compare the incidence of PDPH in the case of median and paramedian approaches in patients undergoing spinal anesthesia for orthopedic operations. PATIENTS AND METHODS: Patients scheduled for orthopedic surgery under spinal anesthesia between 2007 and 2008 were studied in a double-blinded randomized controlled trial. The patients were randomized to receive spinal anesthesia by either a median (n = 75) or paramedian (n = 75) approach through a 25-gauge Crawford needle. No premedication was given, and all patients received 500 mL of normal saline intravenously and 4 mL of 0.5% isobaric Marcaine 30 minutes prior to surgery in both approaches. RESULTS: Fifteen patients (10%) developed PDPH. There was no significant difference in the incidence of PDPH in both groups, with 7 (9.3%) patients in the median approach group versus 8 (10.7%) in the paramedian approach group developing typical PDPH (P = 0.875). However, a significant difference in PDPH incidence (P = 0.041) was observed between females (9; 16.7%) and males (6; 6.3%). CONCLUSIONS: There is no difference between median and paramedian approaches with respect to PDPH incidence; the paramedian approach is therefore recommended, especially for older patients with degenerative changes in the spine and intervertebral spaces and those who cannot take the proper position. Moreover, the rate of PDPH was found to be significantly higher in females than in males.

The effect of tranexamic acid on reducing blood loss in cementless total hip arthroplasty under epidural anesthesia.

Total hip arthroplasty (THA) is associated with high intraoperative and postoperative blood loss. Antifibrinolytic drugs have been used to minimize the potential risks of bleeding and blood transfusion. Studies on the effect of tranexamic acid on decreasing blood loss in THA have revealed interesting results, but most have focused on cemented THA. Yet its benefits in THA, especially in cementless THA, have not been proved. We conducted a prospective double-blind randomized controlled study on 64 patients who were candidates for cementless THA under epidural anesthesia between 2006 and 2008. Patients were randomly assigned into study and control groups. Patients in both groups were well matched regarding preoperative characteristics. Five minutes preoperatively 32 patients of the study and control groups received 15 mg/kg tranexamic acid or normal saline intravenously respectively. Our findings showed a significantly smaller decrease in 6- and 24-hour postoperative hemoglobin levels, less intraoperative and postoperative bleeding, and less need for allogenic blood transfusion in the tranexamic acid group. Our results also revealed a higher mean of 6- and 24-hour hematocrit level and shorter hospital stay in the tranexamic acid group compared to the control group, which were not statistically meaningful. In our study no thromboembolic event was seen; except 1 patient in the control group. Our study showed that administering tranexamic acid before the start of cementless THA under epidural anesthesia can reduce intraoperative and postoperative bleeding as well as need for blood transfusion.

Clinical results of reversed V-shaped high tibial corticotomy with minimally invasive surgery without internal fixation devices.

High tibial osteotomy is a method of treating knee osteoarthritis due to genu varum in advanced stages. High tibial osteotomy-associated problems continue to be reported. The purpose of this study was to investigate the clinical results of a new, innovative method of high tibial osteotomy with 3- to 13-year follow-up. Between 1996 and 2006, our new surgical method was performed on 293 patients with medial compartment osteoarthritis and genu varum. All patients were examined preoperatively, 6 months postoperatively, and at final follow-up. The Hospital for Special Surgery Knee Scoring System (HSS) was used at final follow-up, and limb alignment and patient satisfaction were reassessed. Immediate postoperative complications included varus recurrence, knee instability, and peroneal nerve palsy, and no signs of tibial nonunion or infection were observed. At final follow-up, 3 cases of genu recurvatum, 2 cases of peroneal nerve palsy, and 25 cases of loss of correction were observed. Average postoperative HSS score was 85 (range, 47-97), and 97.8% of the patients were satisfied. This new method is a good alternative for the correction of genu varum because it requires a small incision, is soft tissue friendly, is a corticotomy instead of an osteotomy, requires no internal or external fixation devices, has a shorter duration and an acceptable complication and recurrence rate, and results in satisfactory HSS scores and higher patient satisfaction rates.

Congenital dislocation of the knee in a 16-year-old girl.

Congenital dislocation of the knee ranges from hyperextension of the knee to translation of the femur on the tibia. Treatment options include bracing, splinting, manipulation and casting, and surgery. A 16-year-old girl presented with an inability to walk, stand upright, or bend her knees. She exhibited deformity of both lower extremities. She had deformed knees from birth, and they had been put in a cast for 2 months. No other therapeutic measures were taken. The patient walked on her abnormally hyperextended knees and could hyperextend the knees to 150 degrees recurvatum. She was diagnosed with a grade III congenital dislocation of the knee, and a flexion-shortening osteotomy at the distal femur above the trochlear level was performed on her knees in 2 sessions. Postoperatively, range of motion changed from hyperextention to 80 degrees flexion. A femoral supracondylar osteotomy was also performed 2 years later, and as a result, a 15 degrees flexion and 15 degrees valgus were added to the limb. The patient is now able to stand and walk without a knee brace and has 90 degrees passive and 80 degrees active knee flexion on both sides. Congenital dislocation of the knee is a rare congenital disorder. The results of treatment are favorable if started before age 3 months, or sometimes before age 2 years, but there is no effective treatment for older, neglected cases; therefore, we believe this case report demonstrates a novel surgical approach.

Modified ilioinguinal approach to the acetabulum and pelvis from beneath the inguinal ligament: a subinguinal approach.

The ilioinguinal approach is favoured for fractures of the anterior part of the pelvis, but it is associated with some technical difficulties and it is not suitable for some complex fractures. In 2008, a modified ilioinguinal approach was introduced by Farid Yr which afforded visualisation of the inside and outside of the pelvis. The approach involves retroperitoneal access below the inguinal ligament to preserve the integrity of the inguinal canal and allows exposure of anterior and medial wall fractures as well as the anterior hip capsule. Despite the dimensions of the procedure, closure is anatomical because repair of the inguinal canal floor is not required. We report the use of this approach in 17 patients with T-type fractures of the acetabulum, transverse fractures of acetabulum, Tile C1 pelvic fractures, malunion of the pelvis and acetabular dysplasia. The approach is recommended in complex cases of acetabular surgery (including obese or muscular patients) and complicated or old fractures in which a better exposure is required. It is useful in visualisation of the anterior wall and labrum and intra articular structures, and in viewing the internal anatomy of the pelvis and acetabulum. It may be a suitable approach for periacetabular osteotomy.

Sudden peroneal nerve palsy in a varus arthritic knee.

Peroneal nerve palsy has been reported in association with traumatic and nontraumatic causes. We encountered a 75-year-old man whose peroneal nerve palsy developed suddenly following varus deformity of the arthritic knee. A review of the literature found 1 other report describing a progressive peroneal nerve palsy associated with a varus deformity of the knee due to arthritis. Our patient had progressive intractable knee pain; 3-compartment, severe degenerative changes in the knees; varus knee malalignment and laxity; right peroneal nerve palsy; and decreased sensation to light touch and pinprick on the dorsum of the right foot. The preoperative WOMAC score was 36. Nerve conduction studies confirmed acute peroneal neuropathy with conduction block at the fibular neck and secondary axonal degeneration. Magnetic resonance imaging of the knee showed osteophytes and cysts surrounding the fibular neck. Although their compression could be responsible for the nerve palsy, the sudden process made this less possible. Thus, the patient underwent total knee arthroplasty of both knees without exploration of the nerve. At 5-month follow-up, the WOMAC score was 78. The patient walked with a cane with no varus thrust, and his right knee had no varus laxity in full extension. The peroneal nerve did not retain its function. Sensory examination and postoperative nerve conduction studies showed no improvement.