The accuracy of routine knee MR imaging in detection of acute neurovascular injury following multiligamentous knee injury.

OBJECTIVE: To assess the accuracy of routine knee MRI in detecting acute popliteal artery and/or common peroneal nerve (CPN) dysfunction following multiligamentous knee injury (MLKI), with correlation of MRI findings to clinical outcome. MATERIALS AND METHODS: Routine MRI knee examinations in 115 MLKI patients (54/115 with acute neurovascular injury, 61/115 without neurovascular injury) were retrospectively reviewed. Cases were classified by injury mechanism and ligamentous injuries sustained. MRI examinations were reviewed by two readers for vascular (arterial flow void, arterial calibre, intimal flap, perivascular hematoma) and CPN (intraneural T2-hyperintensity, calibre, discontinuity, perineural hematoma) injuries. Accuracy of routine knee MRI in the diagnosis of acute neurovascular injury and correlation of MRI findings to clinical outcome were evaluated. RESULTS: Patients included 86/115 males, mean age 33 years. The accuracy of MRI in diagnosis of acute CPN injury was 80.6%, 83.6% (readers 1 and 2): sensitivity (78%, 79.7%), specificity (80%, 86.7%), PPV (78%, 82.5%), and NPV (82.7%, 84.4%). Increased intraneural T2 signal showed a significant correlation to acute CPN dysfunction (p < 0.05). MRI was 75%, 69.8% (readers 1 and 2) accurate in detecting acute vascular injury: sensitivity (73.3%, 86.7%), specificity (75.2%, 67.3%), PPV (30.5%, 36.1%), and NPV (95%, 97.1%). No MRI features of vascular injury showed a statistical correlation with clinical outcome. Neurovascular complications were more common in ultra-low-energy injuries and KD-V3L pattern of ligament disruption. CONCLUSION: Routine MRI is of limited accuracy in assessing vascular complication, but higher accuracy in assessing CPN injury following MLKI. Increased intraneural T2 signal on conventional knee MR imaging shows statistically significant association with clinically documented acute CPN dysfunction following MLKI.

MR imaging in the presence of ballistic debris of unknown composition: a review of the literature and practical approach.

Due to a combination of increasing indications for MR imaging, increased MRI accessibility, and extensive global armed conflict over the last few decades, an increasing number of patients now and in the future will present with retained metallic ballistic debris of unknown composition. To date, there are no guidelines on how to safely image these patients which may result in patients who would benefit from MRI not receiving it. In this article, we review the current literature pertaining to the MRI safety of retained ballistic materials and present the process we use to safely image these patients.

Imaging of the Postoperative Condition of Posterolateral Corner Injuries.

Posterolateral corner (PLC) injuries of the knee are often sustained in combination with anterior or posterior cruciate ligament injuries. A variety of surgical techniques including acute repair, nonanatomical reconstructions, and anatomical reconstructions have been used to treat grade III PLC injuries. Scant literature is available on postoperative imaging of the PLC. This article reviews the more commonly used surgical techniques and the postoperative imaging assessment of the PLC of the knee.

Meniscal root tears occur frequently in multi-ligament knee injury and can be predicted by associated MRI injury patterns.

PURPOSE: The frequency of meniscal root tears in association with multi-ligament knee injury has not been established but adds to the complexity of surgical reconstruction and may have long-term consequences. Therefore, identifying root tears, on preoperative imaging, is important. The aim of this study was to identify the frequency of meniscal root tears, on preoperative magnetic resonance imaging, following multi-ligament injury and distinguish associated injury patterns that may aid detection. METHODS: Cases were identified from a prospectively collected institutional database. The magnetic resonance imaging of 188 multi-ligament injuries [median age 31 years (range 16-64)] was retrospectively reviewed by three musculoskeletal radiologists with the presence of meniscal injuries recorded alongside the ligament injury pattern and intra-articular fractures. Assessment of injury pattern was solely made on this imaging. RESULTS: 38 meniscal root injuries were identified in 37 knees (overall frequency = 20.2%; medial = 10.6%; lateral = 9.6%). The frequency of meniscal root tears was not increased in higher grade injuries (21.5% vs. 17.0%, n.s.). Valgus injury patterns were associated with lateral root tears (p < 0.05) and varus patterns were associated with medial root tears (p < 0.05). Further, fractures in the same compartment were associated with both medial and lateral root tears (p < 0.05). CONCLUSIONS: Meniscal root tears occur more frequently in multi-ligament knee injury than previously reported with isolated anterior cruciate rupture. Root tears can be predicted by ligament injury patterns and fractures sustained (suggestive of a compressive force). In multi-ligament cases, the preoperative magnetic resonance imaging can be used to detect these tears and associated patterns of injury. LEVEL OF EVIDENCE: IV.

The radiographic quantification of scapular malalignment after malunion of displaced clavicular shaft fractures.

BACKGROUND: Malunion after displaced fractures of the clavicle can result in varying degrees of scapular malalignment and potentially scapular winging. The purpose of our study was to quantify the scapular malalignment in patients with midshaft clavicle malunions showing scapular winging. METHODS: Eighteen patients with symptomatic midshaft clavicle malunions showing scapular winging were identified and underwent standardized computed tomography scanning of the thorax. Specific bony landmarks on the clavicle and scapula were digitized, allowing generation of 3-dimensional points. These points were acquired bilaterally so that relative translations comparing the malunited side with the contralateral side could be obtained. Statistical analysis using a paired t test was performed. RESULTS: The mean time from fracture to examination was 42.9 months. There were 15 men and 3 women with a mean age of 41.6 years. The mean clavicular shortening was 21.1 mm (P = .0000004). The acromion of the affected scapula on average translated 24.3 mm. The components of this translation were medial, 11.9 mm (P = .00008); inferior, 20.7 mm (P = .0009); and anterior, 4.6 mm (P = .02). Posterior bony landmarks on the scapula including the superior and inferior angles of the scapula translated a total of 9.9 mm and 5.9 mm, respectively. CONCLUSION: This is the first study to document the degree of scapular malalignment in patients with symptomatic clavicle malunions showing scapular winging. The acromion closely follows the distal clavicular fragment and translates medially, inferiorly, and anteriorly. The translations of the superior and inferior angles of the scapula are quite variable in magnitude and direction, and on average, these angles translate substantially less than the acromion.

Imaging of postoperative avascular necrosis of the ankle and foot.

Avascular necrosis (AVN) of the ankle and foot is an uncommon and often unexpected postoperative complication in patients with persistent pain and disability postprocedure. Artifacts from metallic implants may obscure characteristic imaging signs of AVN, and radiography and computer tomography are the mainstay imaging modalities of the postoperative ankle and foot. MRI and nuclear medicine imaging play an important complementary role in problem solving and excluding differential diagnostic considerations including infection, nonunion, occult fracture, and secondary osteoarthritis.This review article evaluates different imaging modalities and discusses characteristic sites of AVN of the ankle and foot in the postoperative setting including the distal tibia, talus, navicular, and first and lesser metatarsals. Radiologists play a key role in the initial diagnosis of postoperative AVN and the surveillance of temporal evolution and complications including articular collapse and fragmentation, thus influencing orthopedic management.

Cellular markers of muscle atrophy in chronic obstructive pulmonary disease.

Skeletal muscle atrophy in individuals with advanced chronic obstructive pulmonary disease (COPD) is associated with diminished quality of life, increased health resource use, and worsened survival. Muscle wasting results from an imbalance between protein degradation and synthesis, and is enhanced by decreased regenerative repair. We investigated the activation of cellular signaling networks known to mediate muscle atrophy and regulate muscle regenerative capacity in rodent models, in individuals with COPD (FEV(1) < 50% predicted). Nine patients with COPD and nine control individuals were studied. Quadriceps femoris muscle isometric contractile force and cross-sectional area were confirmed to be significantly smaller in the patients with COPD compared with control subjects. The vastus lateralis muscle was biopsied and muscle transcript and/or protein levels of key components of ubiquitin-mediated proteolytic systems (MuRF1, atrogin-1, Nedd4), inflammatory mediators (IkappaBalpha, NF-kappaBp65/p50), AKT network (AKT, GSK3beta, p70S6 kinase), mediators of autophagy (beclin-1, LC3), and myogenesis (myogenin, MyoD, Myf5, myostatin) were determined. Atrogin-1 and Nedd4, two ligases regulating ubiquitin-mediated protein degradation and myostatin, a negative regulator of muscle growth, were significantly increased in the muscle of patients with COPD. MuRF1, Myf5, myogenin, and MyoD were not differentially expressed. There were no differences in the level of phosphorylation of AKT, GSK3beta, p70S6kinase, or IkappaBalpha, activation of NF-kappaBp65 or NF-kappaBp50, or level of expression of beclin-1 or LC3, suggesting that AKT signaling was not down-regulated and the NF-kappaB inflammatory pathway and autophagy were not activated in the COPD muscle. We conclude that muscle atrophy associated with COPD results from the recruitment of specific regulators of ubiquitin-mediated proteolytic pathways and inhibition of muscle growth.

Injury patterns to the posteromedial corner of the knee in high-grade multiligament knee injuries: a MRI study.

Injury patterns to the posteromedial corner of the knee have not been previously studied in the context of multiligament knee injuries. We performed a retrospective magnetic resonance imaging and clinical review of a consecutive series of 27 dislocatable knees presenting to a single level-one trauma center from 2005 to 2008. Post-injury magnetic resonance imaging studies were reviewed by two fellowship-trained musculoskeletal radiologists to assess injury patterns to the posteromedial corner. In our series, injury to at least one structure within the posteromedial corner was observed in 81% (22/27) of cases while injury to the superficial medial collateral ligament alone was seen in 63% (17/27) of cases. Furthermore, injuries to the posterior horn of the medial meniscus were associated with a tear of the meniscotibial ligaments in all cases and with a tear of the posterior oblique ligament in 67% of cases. All patients with grade III laxity (>10 mm medial opening) under an examination under anesthesia had a complete tear of the posterior oblique ligament and meniscotibial ligament in addition to a medial collateral ligament injury. Injury to the semimembranosus attachment alone was not associated with clinically significant laxity under an examination under anesthesia. Our findings demonstrate that injuries to the posteromedial corner are common in the setting of traumatic knee dislocations. Interestingly, high-grade medial instability during an examination under anesthesia and injury to the posterior horn of the medial meniscus may be important indicators for further posteromedial corner injury.

Weightbearing CT scan of severe flexible pes planus deformities.

BACKGROUND: The three-dimensional relationships of the bones in the foot in a flatfoot deformity are difficult to assess with standard radiographs. CT scans demonstrate these relationships but are typically made in a nonweightbearing mode. Our objective was to assess the use of a weightbearing CT apparatus to image the feet in patients with severe flexible pes planus deformities and to better define the anatomical changes that occur. MATERIALS AND METHODS: A specialized device was designed and constructed to simulate weightbearing to the feet during CT examination. Eighteen normal feet and 30 painful severe and flexible pes planus feet were imaged in both the non weightbearing and weightbearing states, set at 50% of body weight. Several measurements of intertarsal relationships were made of the pes planus and normal feet. Navicular floor to skin distance, forefoot arch angle, and subtalar joint subluxation were measured in the coronal plane in both the weightbearing and nonweightbearing states. T-tests were used to analyze measurements of navicular floor to skin distance and forefoot arch angle. RESULTS: The weightbearing device had a significant effect on foot configuration for both normal and pes planus feet (p = 0.0008) and (p < 0.0001) respectively for both floor to skin distance and forefoot arch angle. There was a significant difference between normal feet and pes planus feet with regard to the forefoot arch angle in the nonweightbearing (p = 0.02) and weightbearing states (p = 0.01). Four of the pes planus patients had evidence of subtalar joint subluxation which was more pronounced in the weightbearing state. There was no significant difference between the navicular floor to skin distance in the normal versus pes planus feet in either the non weightbearing (p = 0.05) or the weightbearing states (p = 0.07). CONCLUSION: A device was designed and constructed to apply a weightbearing load equal to that of 50% body weight with minimal to no patient discomfort. The resultant effects on foot configuration were significant, and are useful for assessment of degree of flexible flat foot deformity, thus guiding clinical management. The measure which most significantly differed between pes planus patients and normal volunteers was the forefoot arch angle. Forefoot arch angle may therefore be the most useful measure for the imaging diagnosis of flexible pes planus, and the degree of planus deformity.

Prevalence of vertebral fractures in adults with cystic fibrosis and their relationship to bone mineral density.

STUDY OBJECTIVES: The objectives of this study were to determine the prevalence of morphometric vertebral fractures in a large cohort of adult cystic fibrosis (CF) patients, and to examine the association between fractures and bone mineral density (BMD). DESIGN: Cross-sectional retrospective study. SETTING: A tertiary care academic hospital. PATIENTS: Adult CF patients who had undergone BMD testing and chest radiography within 1 month of each other. MEASUREMENTS AND RESULTS: BMD was measured by dual-energy x-ray absorptiometry (DXA) at the lumbar spine (LS) and femoral neck (FN). Vertebral fractures were diagnosed using lateral chest radiographs. Several clinical and biochemical variables were assessed as correlates. Sixty subjects (36%) had z scores between -1.0 and -2.5, and 15 subjects (9%) had z scores of < -2.5. Twelve patients (7.2%) had 19 morphometric fractures. The mean BMD at the LS was 1.266 g/cm(2) in the fracture group and 1.112 g/cm(2) in the nonfracture group (p = 0.0002). The mean BMD at the FN was 1.129 g/cm(2) in the fracture group and 0.987 g/cm(2) in the nonfracture group (p = 0.0006). Both FEV(1) and body mass index were significantly associated with BMD at both the LS and the FN. CONCLUSION: Seven percent of adult patients with CF had vertebral fractures as determined by morphometry. Subjects in the fracture group had both clinically and statistically higher BMD as measured by DXA. Our findings raise the intriguing possibility that BMD may not be useful in identifying CF patients with fractures.

Avascular necrosis of the talus: a pictorial essay.

The talus is predisposed to avascular necrosis (AVN), or bone death due to ischemia, owing to its unique structure, characteristic extraosseous arterial sources, and variable intraosseous blood supply. Both traumatic and atraumatic causes have been implicated in talar AVN. The risk of posttraumatic AVN can be predicted using the Hawkins classification system. In addition, the "Hawkins sign" can be used as a radiographic marker that excludes the development of AVN. At radiography, talar AVN typically manifests as an increase in talar dome opacity (sclerosis), followed by deformity and, in severe cases, articular collapse and bone fragmentation. At any stage of this sequence, the radiographic findings can vary depending on differences in the vascular status of the talus and the degree of bone repair. Magnetic resonance imaging is the most sensitive technique for detecting talar AVN and can be used when AVN is strongly suspected clinically despite normal radiographic findings. Computed tomography (CT) also demonstrates typical patterns and can be used to confirm radiographic findings. Coronal CT is required for viewing the articular surface of the talar dome to rule out subtle depression, collapse, and fragmentation. Nevertheless, radiography remains the mainstay of the diagnosis and temporal observation of talar AVN.

Bone mineral density predicts fractures in chronic kidney disease.

Fractures are common in chronic kidney disease (CKD). The optimal methods by which to assess fracture risk are unknown, in part, due to a lack of prospective studies. We determined if bone mineral density (BMD) by dual-energy X-ray absorptiometry (DXA), and/or high-resolution peripheral quantitative computed tomography (HRpQCT) could predict fractures in men and women ≥18 years old with stages 3 to 5 CKD. BMD was measured by DXA (at the total hip, lumbar spine, ultradistal, and 1/3 radius) and by HRpQCT (at the radius), and subjects were followed for 2 years for incident morphometric spine fractures and low-trauma clinical fractures. The mean age of the subjects was 62 years with equal numbers having stages 3, 4, and 5 CKD. Over 2 years there were 51 fractures in 35 subjects. BMD by DXA at baseline was significantly lower at all sites among those with incident fractures versus those without. For example, the mean BMD at the total hip in those with incident fractures was 0.77 g/cm2 (95% confidence interval [CI], 0.73 to 0.80) and in those without fracture was 0.95 g/cm2 (95% CI, 0.92 to 0.98). Almost all baseline HRpQCT measures were lower in those with incident fracture versus those without. For example, volumetric BMD in those with incident fractures was 232 mg HA/cm3 (95% CI, 213 to 251) and in those without fracture was 317.6 mg HA/cm3 (95% CI, 306 to 329.1). Bone loss occurred in all subjects, but was significantly greater among those with incident fractures. Our data demonstrate that low BMD (by DXA and HRpQCT) and a greater annualized percent decrease in BMD are risk factors for subsequent fracture in men and women with predialysis CKD.

Computer navigation in the reduction and fixation of femoral shaft fractures: a randomized control study.

OBJECTIVES: We investigated the accuracy of reduction of intramedullary nailed femoral shaft fractures in human cadavers, comparing conventional and computer navigation techniques. METHODS: Twenty femoral shaft fractures were created in human cadavers, with segmental defects ranging from 9 to 53 mm in length (Winquist 3-4, AO 32C2). All fractures were fixed with antegrade 9 mm diameter femoral nails on a radiolucent operating table. Five fractures ("Fluoro" group) were fixed with conventional techniques and fifteen fractures ("Nav 1" and "Nav 2" groups) with computer navigation, using fluoroscopic images of the normal femur to correct for length and rotation. Postoperative CT scans compared femoral length and rotation with the normal leg. RESULTS: Mean leg length discrepancy in the computer navigation groups was smaller, namely, 3.6 mm for Nav 1 (95% CI: 1.072 to 6.128) and 4.2 mm for Nav 2 (95% CI: 0.63 to 7.75) vs. 9.8 mm for Fluoro (95% CI: 6.225 to 13.37) (p<0.023). Mean rotational discrepancies were 8.7° for Nav 1 (95% CI: 4.282 to 13.12) and 5.6° for Nav 2 (95% CI: -0.65 to 11.85) vs. 9.0° for Fluoro (95% CI: 2.752 to 15.25) (p=0.650). CONCLUSIONS: Computer navigation significantly improves the accuracy of femoral shaft fracture fixation with regard to leg length, but not rotational deformity.

The indications for and the prognostic significance of amputation as the primary surgical procedure for localized soft tissue sarcoma of the extremity.

BACKGROUND: The indications for primary amputation of a localized soft tissue sarcoma (STS) of the extremity are not well defined in the literature. However, it has been suggested that patients who require an amputation to treat an STS are at increased risk for developing metastases. We categorized the main indications for primary amputation in our patient population and compared their oncological outcome with the outcome of patients who underwent limb-sparing surgery. METHODS: 413 consecutive patients treated surgically at a single center for primary, nonmetastatic, deep, intermediate-, or high-grade STS of the extremity were reviewed. Indications for primary amputation were identified. Demographics and outcomes were compared between the amputation and limb-salvage groups. Multivariate Cox model analysis was used to identify independent risk factors for systemic relapse. RESULTS: Twenty-five (6%) of 413 patients with STS underwent primary amputation: they were older (P = .05), had larger tumors (P = .001), and had a significantly greater risk of developing metastatic disease than patients who underwent limb-sparing procedures (P = .008). However, multivariate analysis demonstrated that the only independent predictors of systemic relapse were tumor size (P = .0001) and tumor grade (P = .0001). Primary amputation was not an independent risk factor for metastatic disease. CONCLUSIONS: The decision to perform a primary amputation for an STS of the extremity is based on the location and local extent of the tumor, and the expected function of the extremity after tumor resection. The higher risk of metastases for patients who require primary amputation is accounted for by independent risk factors associated with their tumors--predominantly large tumor size.

Distinguishing transient osteoporosis of the hip from avascular necrosis.

INTRODUCTION: To review the circumstances surrounding the misdiagnosis of transient osteoporosis of the hip (TOH) as avascular necrosis (AVN) and to increase physician awareness of the prevalence and diagnosis of this condition in young men, we reviewed a series of cases seen in the orthopedic unit at St. Michael's Hospital, University of Toronto. METHODS: We studied the charts of patients with TOH referred between 1998 and 2001 with a diagnosis of AVN for demographic data, risk factors, imaging results and outcomes. RESULTS: Twelve hips in 10 young men (mean age 41 yr, range from 32-55 yr) were identified. Nine men underwent magnetic resonance imaging (MRI) before referral, which showed characteristic changes of TOH. All 10 patients were referred for surgical intervention for a diagnosis of AVN. The correct diagnosis was made after reviewing patients' charts and the scans and was confirmed by spontaneous resolution of both symptoms and MRI findings an average of 5.5 months and 7.5 months, respectively, after consultation. CONCLUSIONS: Despite recent publications, the prevalence of TOH among young men is still overlooked and the distinctive MRI appearance still misinterpreted. Symptoms may be severe but resolve over time with reduced weight bearing. The absence of focal changes on MRI is highly suggestive of a transient lesion. A greater level of awareness of this condition is needed to differentiate TOH from AVN, avoiding unnecessary surgery and ensuring appropriate treatment.