Radiographically occult femoral and pelvic fractures are not mutually exclusive: a review of fractures detected by MRI following low-energy trauma

Objectives

The purpose of this study was to review the MRI examinations of a large group of low-energy trauma patients in whom pelvic MRI had detected radiographically occult fractures, in order to characterize prevailing fracture patterns and determine how often co-existing proximal femoral and pelvic fractures were observed.

Methods

All patients having pelvic MRI over 5?years were identified. Word-search software selected 269 MRI reports containing the term ‘fracture’. Further scrutiny identified 168 with diagnosis of fracture. MRI request and imaging record review identified 102 low-energy trauma cases that had MRI for clinical suspicion of fracture despite normal radiographs. Sixty-six cases were excluded for the following reasons: no expressed clinical suspicion of occult fracture; history suggesting high-energy trauma; skeletal co-morbidity hindering acute fracture identification; interval more than 2?weeks between radiographs and MRI. The 102 study MRI examinations, which employed a limited two-sequence protocol, were reviewed. Any fracture that had not been appreciated on radiographs was recorded and characterized as femoral, pelvic, or co-existing femoral and pelvic fractures.

Results

The 102 study cases had a median age of 82?years. The median interval between pelvic radiographs and MRI was 3?days. MRI showed undiagnosed femoral fracture in 48/102 cases (47.1%), sacral fracture in 41/102 (40.2%), and pubic fracture in 55/102 (53.9%). In 11/102 cases (10.8%), MRI showed undiagnosed fractures of both proximal femur and pelvic ring (seven sacral, six pubic bone, two other site fractures). In 10/11 cases with co-existing femoral and pelvic fractures, the femoral fracture was incomplete.

Conclusions

Limited pelvic MRI found a high prevalence of radiographically occult femoral and pelvic fractures in low-energy trauma patients, with clinical suspicion of fracture despite normal radiographs. Co-existing occult femoral and pelvic ring fractures were commonly observed, and in such cases, the femoral fracture was likely to be incomplete and multiple pelvic fractures were typically present.     

Standard Radiography: Untapped Potential in the Assessment of Osteoporotic Fracture Risk

Background

Assessment of osteoporotic fracture risk is based primarily on bone mineral density (BMD) measurements using dual X-ray absorptiometry (DXA).

Methods

However, recent evidence indicates that the method is insufficient for accurate individual risk assessment; in addition to methodological inaccuracies related to DXA, the mechanical strength of bone is influenced not only by low BMD but also by other factors that are not captured by DXA.

Results

DXA-based BMD can provide information on the amount of bone but does not elucidate bone structure, which is significant for bone mechanical strength and for fracture risk. In order to achieve more a comprehensive assessment of fracture risk, recent efforts have been directed toward imaging techniques by which bone structural changes can be observed. In addition to novel three-dimensional imaging techniques, analysis of plain radiographs has also been investigated with promising results.

Conclusion

As plain radiographs are cheap and widely available, it was considered of interest to discover how well plain radiography could be utilised for the assessment of bone mechanical competence and fracture risk. In this article, we review studies related to radiographic assessment of fracture risk in order to show the potential of this conventional methodology for screening subjects at risk.

Key Points

? Conventional radiography has sufficient theoretical requirements for assessment of bone structure. ? Bone geometry and trabecular structure can be depicted by and evaluated from standard radiographs. ? Texture-based analysis of radiographs discriminates postmenopausal women with and without fractures. ? Such analysis can also predict fractures in individuals without frank osteoprosis. ? Imaging and subsequent analysis should become more standardised to allow structural quantification     

Digital X-ray radiogrammetry of hand or wrist radiographs can predict hip fracture risk—a study in 5,420 women and 2,837 men

Objectives

To assess whether digital X-ray radiogrammetry (DXR) analysis of standard clinical hand or wrist radiographs obtained at emergency hospitals can predict hip fracture risk.

Methods

A total of 45,538 radiographs depicting the left hand were gathered from three emergency hospitals in Stockholm, Sweden. Radiographs with insufficiently included metacarpal bone, fractures in measurement regions, foreign material or unacceptable positioning were manually excluded. A total of 18,824 radiographs from 15,072 patients were analysed with DXR, yielding a calculated BMD equivalent (DXR-BMD). Patients were matched with the national death and inpatient registers. Inclusion criteria were age ≥ 40 years, no prior hip fracture and observation time > 7 days. Hip fractures were identified via ICD-10 codes. Age-adjusted hazard ratio per standard deviation (HR/SD) was calculated using Cox regression.

Results

8,257 patients (65.6 % female, 34.4 % male) met the inclusion criteria. One hundred twenty-two patients suffered a hip fracture after their radiograph. The fracture group had a significantly lower DXR-BMD than the non-fracture group when adjusted for age. The HR/SD for hip fracture was 2.52 and 2.08 in women and men respectively. The area under the curve was 0.89 in women and 0.84 in men.

Conclusions

DXR analysis of wrist and hand radiographs obtained at emergency hospitals predicts hip fracture risk in women and men.

Key Points

? Digital X-ray radiogrammetry of emergency hand/wrist radiographs predicts hip fracture risk. ? Digital X-ray radiogrammetry (DXR) predicts hip fracture risk in both women and men. ? Osteoporosis can potentially be identified in patients with suspected wrist fractures. ? DXR can potentially be used for selective osteoporosis screening.     

The Radiographic Union Score for Hip (RUSH): the use of a checklist to evaluate hip fracture healing improves agreement between radiologists and orthopedic surgeons

Objective

The assessment of fracture healing following intertrochanteric fracture fixation is highly variable with no validated standards. Agreement with respect to fracture healing following surgery is important for optimal patient management. The purpose of this study was to (1) assess reliability of intertrochanteric fracture healing assessment and (2) determine if a novel radiographic scoring system for hip fractures improves agreement between radiologists and orthopedic surgeons.

Materials and methods

A panel of three radiologists and three orthopedic surgeons assessed fracture healing in 150 cases of intertrochanteric fractures at two separate time points to determine inter-rater and intra-rater agreement. Reviewers, blinded to the time after injury, first subjectively assessed overall healing using frontal and lateral radiographs for each patient at a single time point. Reviewers then scored each fracture using a Radiographic Union Score for Hip (RUSH) form to determine whether this improves agreement regarding hip fracture healing.

Results

Inter-rater agreement for the overall subjective impression of fracture healing between reviewer groups was only fair (intraclass coefficient [ICC]?=?0.34, 95 % CI: 0.11–0.52. Use of the RUSH score improved overall agreement between groups to substantial (ICC?=?0.66, 95 % CI: 0.53–0.75). Across reviewers, healing of the medial cortex and overall RUSH score itself demonstrated high correlations with overall perceptions of healing (r?=?0.53 and r?=?0.72, respectively).

Conclusions

The RUSH score improves agreement of fracture healing assessment between orthopedic surgeons and radiologists, offers a systematic approach to evaluating intertrochanteric hip fracture radiographs, and may ultimately provide prognostic information that could predict healing outcomes in patients with femoral neck fractures.     

Correlation between radiological assessment of acute ankle fractures and syndesmotic injury on MRI

Objective

Owing to the shortcomings of clinical examination and radiographs, injury to the syndesmotic ligaments is often misdiagnosed. When there is no indication requiring that the fractured ankle be operated on, the syndesmosis is not tested intra-operatively, and rupture of this ligamentous complex may be missed. Subsequently the patient is not treated properly leading to chronic complaints such as instability, pain, and swelling. We evaluated three fracture classification methods and radiographic measurements with respect to syndesmotic injury.

Materials and methods

Prospectively the radiographs of 51 consecutive ankle fractures were classified according to Weber, AO-Müller, and Lauge-Hansen. Both the fracture type and additional measurements of the tibiofibular clear space (TFCS), tibiofibular overlap (TFO), medial clear space (MCS), and superior clear space (SCS) were used to assess syndesmotic injury. MRI, as standard of reference, was performed to evaluate the integrity of the distal tibiofibular syndesmosis. The sensitivity and specificity for detection of syndesmotic injury with radiography were compared to MRI.

Results

The Weber and AO-Müller fracture classification system, in combination with additional measurements, detected syndesmotic injury with a sensitivity of 47% and a specificity of 100%, and Lauge-Hansen with both a sensitivity and a specificity of 92%. TFCS and TFO did not correlate with syndesmotic injury, and a widened MCS did not correlate with deltoid ligament injury.

Conclusion

Syndesmotic injury as predicted by the Lauge-Hansen fracture classification correlated well with MRI findings. With MRI the extent of syndesmotic injury and therefore fracture stage can be assessed more accurately compared to radiographs.     

Union of the ulnar styloid fracture as a function of fracture morphology on conventional radiographs

Objective

In a retrospective radiological study, the authors aimed to detect the influence of fracture morphology on the union rate of ulnar styloid fractures associated with distal radial fractures.

Materials and methods

Eighty-two out of 101 ulnar styloid fractures were included in the final statistical analysis. Initially, they were grouped into six different morphological types based on a novel classification system. They were also classified as per the established Fernández and Frykman classification systems. Furthermore, the initial ulnar styloid displacement was measured in conventional anteroposterior radiographs. Union of the ulnar styloid fracture was evaluated after at least 6 months of follow-up.

Results

The current investigators demonstrated that the various ulnar styloid fracture patterns have no significant predictive value for ulnar styloid union. In contrast, it could be attested, that an initial fragment dislocation of greater than 2.4 mm in the conventional AP radiographs has a significantly lower chance of successful union (p?=?0.022).

Conclusion

Initial displacement of the ulnar styloid should be measured in each distal radial fracture with a concomitant ulnar styloid fracture. This could be useful to inform the decision regarding surgical fixation of the ulnar styloid fragment in patients with an unstable distal radioulnar joint (DRUJ) or persistent symptoms at the ulnar aspect of the wrist.     

Radiologische Diagnostik des multiplen Myeloms

Clinical/methodical issue

Robust and reliable imaging methods are required to estimate the skeletal tumor load in multiple myeloma, as well as for the diagnosis of extraskeletal manifestations. Imaging also plays an essential role in the assessment of fracture risk and of vertebral fractures.

Standard radiological methods

The conventional skeletal survey has been the gold standard in the imaging of multiple myeloma for many years.

Methodical innovations

Other modalities which have been investigated and are in use are whole-body computed tomography (WBCT), 18F-fluorodeoxyglucose positron emission tomography computed tomography (FDG PET-CT) and whole-body magnetic resonance imaging (WBMRI). These techniques are able to depict both mineralized bone and the bone marrow with a high sensitivity for myeloma lesions.

Performance

Several studies have shown that cross-sectional imaging is superior to the skeletal survey in the detection of myeloma lesions and WBMRI has been shown to be significantly more sensitive than WBCT for the detection of focal myeloma lesions as well as for diffuse infiltration. The FDG PET-CT technique has a sensitivity comparable to WBMRI.

Achievements

Due to the higher sensitivity in the detection of myeloma lesions WBCT and WBMRI should replace the skeletal survey.

Practical recommendations

A WBCT should be performed if there is suspicion of multiple myeloma. If no focal lesions are found WBMRI or at least MRI of the spine and pelvis should be additionally performed if available. If WBMRI has been initially performed and focal lesions are present, an additional WBCT may be performed to assess the extent of bone destruction and fracture risk. In cases of monoclonal gammopathy of undetermined significance (MGUS), solitary and smoldering myeloma, a WBMRI, if available, should be performed in addition to WBCT.     

Explorative study of the sensitivity and specificity of the pronator quadratus fat pad sign as a predictor of subtle wrist fractures

Objective

To investigate the value of post-traumatic pronator quadratus (PQ) fat pad sign as a reliable predictor of subtle wrist fractures.

Materials and methods

This was a prospective study of 68 patients undergoing X-ray for traumatic wrist injuries and subsequent MRI. The reliability of a positive PQ fat pad sign on X-ray, defined as either raised, interrupted or obliterated, was evaluated in detection of subtle wrist fractures.

Results

Out of 68 patients, 28 had a positive PQ sign without any obvious bony injuries on plain radiographs; of these, the PQ fat pad was obliterated in 11, disrupted in 12, and raised in five cases. Fractures defined as cortical interruption or trabecular fractures were revealed in 13/28 (46 %) patients with a positive PQ sign but only in 7/40 (18 %) patients with a negative sign. With regards to different types of abnormal PQ fat planes, fractures were present in 7/12 patients with a disrupted plane (58 %), 6/11 patients with an obliterated plane (54 %), and none of the patients with a raised plane. The overall sensitivity and specificity of a positive PQ sign in the prediction of occult wrist fractures were 65 and 69 %, respectively.

Conclusions

Our findings indicate that a positive pronator quadratus (PQ) fat pad sign is not a reliable predictor of subtle fractures of the wrist, although we believe that it is a useful radiographic sign in justifying MRI for further clarification of possible joint abnormalities including occult fracture and cortex interruption.     

Can the tibial slope be measured on lateral knee radiographs?

Purpose

The posterior tibial slope influences both the natural knee stability as well as the stability and kinematics after total knee arthroplasty (TKA). Exact definition of the posterior tibial slope (PTS) requires lateral radiographs of the lower limb. Only lateral knee radiographs are routinely obtained after TKA, however. The purpose of the present study therefore was to analyse the relationship between PTS measurement results on short and expanded lateral knee radiographs.

Methods

The PTS was measured on 100 consecutive lateral radiographs of the lower limb using the mechanical and three diaphyseal axes with various distances below the tibial plateau.

Results

Significant differences between PTS results were found for all three diaphyseal axes, with the smallest differences and the strongest correlation for a diaphyseal axis at 16 and 20 cm below the tibial plateau. Using short distances below the tibial plateau (6 and 10 cm) resulted in an overestimation of the PTS of 3°, on average.

Conclusion

The PTS measurements in long lateral knee radiographs are more accurate compared to short radiographs. On short lateral knee radiographs, only a estimation of the PTS can be carried out.

Level of evidence

Diagnostic study, Level II.     

MDCT findings after elbow dislocation: a retrospective study of 140 patients

Objective

To assess the number and anatomical location of fractures associated with elbow dislocation, to study the correlation between the direction of dislocation and the trauma energy, and to assess radiographs’ diagnostic performance characteristics for fractures using MDCT as a reference standard.

Materials and Methods

A retrospective study was performed at a level 1 trauma center, finding a total of 140 patients who had sustained an elbow dislocation and who had undergone a subsequent MDCT examination. The CT and radiographs of the patient were reviewed by two musculoskeletal radiologists. CT images were analyzed for the site and size of the fracture fragments. In addition, the primary direction of the dislocation, patients’ age, and gender were recorded. Trauma energy was also assessed.

Results

One hundred and thirty-four out of 140 patients (96 %) had a fracture that was seen on the correlative CT examination. The most common anatomical fracture locations were the coronoid process of the ulna 84 out of 140 (60 %), the radial head 75 out of 140 (54 %), and the humeral capitellum 57 out of 140 (41 %). Multiple fractures were seen in 71 out of 134 (53 %) patients with fractures. The left elbow was more commonly dislocated than the right one. The overall sensitivity of the radiographs was 62 % and the specificity 96 %.

Conclusion

Small fractures and impaction fractures are almost invariably present in elbow dislocations, and half of the patients have more than one fracture. Radiographs have a sensitivity of only 62 %. MDCT is an invaluable method for determining the extent of bony injury and revealing occult fractures.     

Treatment for unstable distal clavicle fractures (Neer 2) with locking T-plate and additional PDS cerclage

Purpose

The purpose of the current study was to assess the clinical and radiological results after locking T-plate osteosynthesis with coracoclavicular augmentation of unstable and displaced distal clavicle fractures (Neer type 2).

Methods

Thirty patients, treated between January 2007 and January 2010 were followed up after a median follow-up time of 12.2 months (range 4.7–37.2). The Constant and DASH scores were used to evaluate the clinical outcome, and anterior–posterior and 30° cephalic view radiographs were performed to assess the bony healing.

Results

In all patients, the fracture healing was achieved within the first 10 weeks after surgery. All patients regained good or excellent shoulder function and returned to previous occupation and activity levels. The mean Constant and DASH scores were 92.3 points and 6.2 points, respectively. We did not observe any severe intra- or post-operative complication within the time of follow-up.

Conclusion

The presented technique turned out to be a reliable method providing good results without showing severe complications.

Level of evidence

Case series, Level IV.     

The fate of the joint space in Legg–Calvé–Perthes’ disease

Objective

This study was undertaken to identify variations in the hip joint space in patients with healed Legg–Calvé–Perthes’ disease (LCPD) and to correlate these changes with the radiological outcome of treatment.

Methods

The width of the joint space was measured on radiographs of 121 skeletally mature individuals with healed LCPD. The joint space width at the stage of healing in 79 patients was compared with the joint space at skeletal maturity. The hips were graded by the Stulberg classification and the femoral head radius was measured. Associations between the joint space width, the Stulberg class and the femoral head radius were tested. The reproducibility of measurement was tested by measuring 30 radiographs twice and computing the intra-class correlation coefficient (ICC). The joint space width was measured on radiographs of 25 patients taken both while recumbent and standing, to determine if the joint space alters on weight-bearing.

Results

The reproducibility of measurements was satisfactory; no difference was noted in the joint space in recumbent and weight-bearing films. Increased joint space was noted both at healing of the disease and at skeletal maturity; the width was minimally increased in Stulberg Class I hips and considerably increased in Class III, IV and V hips. There was a significant correlation between the increase in joint space and enlargement of the femoral head.

Conclusions

An increase in joint space width occurs quite frequently following LCPD; the increase is most evident in hips with a poor outcome. The implications of this observation need to be elucidated.     

Who is more accurate in the diagnosis of neck of femur fractures, radiologists or orthopaedic trainees?

Objective

Our study aims to compare the sensitivity and specificity between orthopaedic trainees and radiologists in diagnosing occult hip fractures from pelvic radiographs.

Methods

All patients undergoing computed tomography (CT) of the hip for a suspected occult hip fracture at our two centres between November 1, 2010 and October 31, 2011 were retrospectively identified. Two orthopaedic trainees (RJ and ED) independently reviewed the initial radiographs, and if both agreed a fracture was present this was recorded. The reports from the radiologist of the initial radiograph and subsequent CT were recorded, with the CT report used as the standard of reference for comparison of performance.

Results

239 CTs were performed for suspected neck of femur fractures during the study period, compared to only 20 in 2006–07, reflecting a 1,095 % increase. The interpretation of radiographs by the orthopaedic trainees showed a sensitivity of 55.4 % and specificity of 96.6 %. In comparison, the radiologists had a sensitivity of 60.7 % and specificity of 92.9 %; this difference was shown not to be statistically significant. Radiologists and orthopaedic trainees agreed when interpreting the majority of radiographs with a Kappa co-efficient of 0.77 (a statistical measure of inter-rater agreement). In 20 of the 174 cases (11.5 %) where the radiologist and orthopaedic trainees agreed no fracture was present, the subsequent CT revealed a fracture.

Conclusion

Orthopaedic trainees and radiologists have similar accuracy at interpreting pelvic radiographs for suspected hip fractures, so the trainee’s opinion can be relied upon. If uncertainty exists, then either the orthopaedic trainee or radiologist should request further imaging urgently as we believe this will expedite diagnosis and treatment of hip fractures, and ensure judicious use of CT.     

The difficult diagnosis of cartilaginous tibial eminence fractures in young children

Purpose

Anterior tibial eminence fracture is the main mode of ACL failure in patients with open physes. In young children, purely cartilaginous avulsions of the tibial ACL insertion are possible. The aim of this study was to focus on patients referred for misdiagnosed cartilaginous tibial eminence fractures.

Methods

Ten young patients with cartilaginous tibial eminence fractures were identified in the hospital database. Six of them were misdiagnosed and included in this retrospective case series. Clinical data at the time of injury, radiographs and MRI were analysed in order to evaluate the causes which could have led to inappropriate management.

Results

The patients’ median age at the time of injury was 7 years (5–8.5). The main cause of injury was a low-energy domestic accident (n = 4). Radiographs at the time of injury were normal (n = 4) or showed a very thin ossification (n = 2). The traditional MRI findings of ACL injuries were all negative. On T2 sequences, an epiphyseal fluid signal allowed for a retrospective diagnosis. Cartilaginous tibial eminence fractures were regularly prolonged posteriorly giving a ‘double-PCL sign’ in 4 of the 6 patients. On a median of 6 months (2.5–48) after the injury, patients were referred for repeat giving ways (n = 5) and/or limitation of extension or hyperextension (n = 4). Symptoms were related to non-union, ossification and secondary enlargement of the avulsed fragment.

Conclusions

Post-traumatic knee joint effusions in children aged 9 or younger, even occurring after a low energy trauma and with normal radiographs, should suggest a cartilaginous tibial eminence fracture. Systematic MRI examinations should be mandatory in these patients in whom the avulsed fragment may appear as a double-PCL sign. During follow-up, new radiographs are recommended. A better knowledge of this rare entity should allow us to avoid misdiagnosis and to perform an early refixation of the avulsed fragment.

Level of evidence

III.     

Radiographic prevalence of CAM-type femoroacetabular impingement after open reduction and internal fixation of femoral neck fractures

Purpose

The purpose of this study was to estimate the radiographic prevalence of CAM-type femoroacetabular impingement (FAI) in elderly patients (≥50 years) who have undergone internal fixation for femoral neck fracture.

Methods

A total of 187 frog-leg lateral radiographs of elderly patients who underwent internal fixation for a femoral neck fracture were reviewed by two independent reviewers. The alpha angle, beta angle, and femoral head–neck offset ratio were calculated. The presence of two abnormal radiographic parameters was deemed to be diagnostic of radiographic CAM-type impingement.

Results

Radiographic CAM-type FAI was identified in 157 out of 187 (84 %) patients who underwent internal fixation for fractures of the femoral neck. Moderate-to-good inter-observer reliability was achieved in the measurement of radiographic parameters. With reference to fracture subtypes and prevalence of radiographic features of CAM-type morphology, 97 (72 %) out of 134 patients were positive for CAM in Garden subtypes I and II, whereas 49 (85.9 %) out of 57 patients had radiographic CAM in Garden III and IV subtypes.

Conclusion

There was a high prevalence of CAM-type FAI in patients that underwent surgical fixation of femoral neck fractures. This is significantly higher than the reported prevalence in non-fracture patient populations. The high prevalence of CAM morphology could be related to several factors, including age, fracture morphology, quality of reduction, type of fixation, and fracture healing.

Level of evidence

IV.     

Intra-articular calcifications following arthroscopic ACL reconstruction: prevalence and possible significance

Purpose

The goal of our study was to determine the frequency of intra-articular calcifications on initial postoperative radiographs following arthroscopic ACL reconstruction, describe their appearance, hypothesize their etiology, and determine their significance.

Materials and methods

Review of records and post-operative radiographs for individuals undergoing arthroscopic ACL reconstruction at our institution identified 758 knees between November 2002 and April 2010. All patients underwent femoral and tibial tunnel drilling regardless of graft source. All but 23 underwent notchplasty.

Results

Intra-articular calcifications on initial postoperative radiographs were observed in 252 knees. The majority of calcifications were curvilinear, paralleling the posterior femoral condyles. Nineteen of the patients with calcifications on initial studies had repeat radiographs within 6 years. The calcifications resolved in every case.

Conclusions

This study shows that intra-articular calcifications are a common finding on initial post-operative radiographs following ACL reconstruction. We feel they are of doubtful clinical significance, and in our limited experience, they eventually resolve. They should not be confused with chondrocalcinosis or vascular calcification.     

Darstellung subtiler Schläfenbeinstrukturen

Purpose

The purpose of this study was to compare the visualization of subtle, non-pathological temporal bone structures on cone beam computed tomography (CBCT) and multi-detector computed tomography (MDCT) in vivo.

Materials and methods

Temporal bone studies of images from 38 patients archived in the picture archiving and communication system (PACS) were analyzed (slice thickness MDCT 0.6 mm and CBCT 0.125 mm) of which 23 were imaged by MDCT and 15 by CBCT using optimized standard protocols. Inclusion criteria were normal radiological findings, absence of previous surgery and anatomical variants. Images were evaluated blind by three trained observers. Using a five-point scale the visualization of ten subtle structures of the temporal bone was analyzed.

Results

Subtle middle ear structures showed a tendency to be more easily distinguishable by CBCT with significantly better visualization of the tendon of the stapedius muscle and the crura of the stapes on CBCT (p?=?0.003 and p?=?0.033, respectively). In contrast, inner ear components, such as the osseus spiral lamina and the modiolus tended to be better detectable on MDCT, showing significant differences for the osseous spiral lamina (p?=?0.001). The interrater reliability was 0.73 (Cohen’s kappa coefficient) and intraobserver reliability was 0.89.

Conclusion

The use of CBCT and MDCT allows equivalent and excellent imaging results if optimized protocols are chosen. With both imaging techniques subtle temporal bone structures could be visualized with a similar degree of definition. In vivo differences do not seem to be as large as suggested in several previous studies.     

Triple fracture during rehabilitation after revision total knee arthroplasty

Purpose

The incidence of periprosthetic fractures after knee-joint implant revisions is increasing in prevalence. We present a method of treatment for a patient who sustained a triple fracture—a periprosthetic femur fracture, a patella fracture, and a tibial shaft fracture.

Methods

The femoral fracture was treated with a specially designed intramedullary nail, the patella fracture with a figure-of-eight suture, and the tibial shaft fracture by a minimal-invasive plate osteosynthesis using a percutaneous plating technique.

Results

Osseous consolidation was confirmed, and the patient presented a satisfying range of movement under full-weight-bearing conditions after mobilisation.

Conclusions

Simultaneous multiple periprosthetic fractures are a special challenge, and in situ coupling of the endoprosthesis with a slotted hollow nail presents a valuable option for the treatment.

Level of evidence

Level V, Expert opinion.     

MRI for response assessment in metastatic bone disease

Background

Beyond lesion detection and characterisation, and disease staging, the quantification of the tumour load and assessment of response to treatment are daily expectations in oncology.

Methods

Bone lesions have been considered “non-measurable” for years as opposed to lesions involving soft tissues and “solid” organs like the lungs or liver, for which response evaluation criteria are used in every day practice. This is due to the lack of sensitivity, specificity and measurement capabilities of imaging techniques available for bone assessment, i.e. skeletal scintigraphy (SS), radiographs and computed tomography (CT).

Results

This paper reviews the possibilities and limitations of these techniques and highlights the possibilities of positron emission tomography (PET), but mainly concentrates on magnetic resonance imaging (MRI).

Conclusion

Practical morphological and quantitative approaches are proposed to evaluate the treatment response of bone marrow lesions using “anatomical” MRI. Recent developments of MRI, i.e. dynamic contrast-enhanced (DCE) imaging and diffusion-weighted imaging (DWI), are also covered.

Key Points

? MRI offers improved evaluation of skeletal metastases and their response to treatment. ? This new indication for MRI has wide potential impact on radiological practice. ? MRI helps meet the expectations of the oncological community. ? We emphasise the practical aspects, with didactic cases and illustrations.     

Rapid osteolysis of the femoral neck: consequence of an insufficiency fracture of the hip?

Purpose

To describe the imaging and clinical features of rapid osteolysis of the femoral neck in an attempt to better understand this uncommon pathology.

Materials and methods

We retrospectively reviewed the files of 11 patients (six women and five men) aged 53–78 years diagnosed with rapid osteolysis of the femoral neck. Available imaging studies included radiographs, CT, MRI, and bone scintigraphy. Histopathological evaluations were available for seven cases.

Results

All patients presented with complaints of hip pain, six of whom had acute symptoms, while the rest had progressive symptoms and impairment. All but one case were found to have bone deposition in adjacent hip muscles. CT confirmed bone deposition in adjacent tissues and true osteolysis of the femoral neck with relative sparing of the articular surfaces. Bone scintigraphy and MRI were useful to exclude underlying neoplastic disease.

Conclusions

Rapid osteolysis of the femoral neck tends to occur in patients with underlying comorbidities leading to bone fragility and may actually represent a peculiar form of spontaneous insufficiency fracture. Recognition of its imaging features and clinical risk factors may help distinguish this process from other more concerning disorders such as infection or neoplasm.