Bone abnormalities of the knee: prevalence and significance at MR imaging

Automated quantitative assessment of bone contusions and overlying articular cartilage following anterior cruciate ligament injury

Quantitative methods to characterize bone contusions and associated cartilage injury remain limited. We combined standardized voxelwise normalization and 3D mapping to automate bone contusion segmentation post-anterior cruciate ligament (ACL) injury and evaluate anomalies in articular cartilage overlying bone contusions. Forty-five patients (54% female, 26.4 ± 11.8 days post-injury) with an ACL tear underwent 3T magnetic resonance imaging of their involved and uninvolved knees. A novel method for voxelwise normalization and 3D anatomical mapping was used to automate segmentation, labeling, and localization of bone contusions in the involved knee. The same mapping system was used to identify the associated articular cartilage overlying bone lesions. Mean regional T1ρ was extracted from articular cartilage regions in both the involved and uninvolved knees for quantitative paired analysis against ipsilateral cartilage within the same compartment outside of the localized bone contusion. At least one bone contusion lesion was detected in the involved knee within the femur and/or tibia following ACL injury in 42 participants. Elevated T1ρ (p = 0.033) signal were documented within the articular cartilage overlying the bone contusions resulting from ACL injury. In contrast, the same cartilaginous regions deprojected onto the uninvolved knees showed no ipsilateral differences (p = 0.795). Automated bone contusion segmentation using standardized voxelwise normalization and 3D mapping deprojection identified altered cartilage overlying bone contusions in the setting of knee ACL injury.

The influence of distribution, severity and volume of posttraumatic bone bruise on functional outcome after ACL reconstruction for isolated ACL injuries

INTRODUCTION

Posttraumatic MRI of ACL tears show a high prevalence of bone bruise (BB) without macroscopic proof of chondral damage. Controversial results are described concerning the association between BB and outcome after ACL tear. Aim of this study is to evaluate the influence of distribution, severity and volume of BB in isolated ACL injuries on function, quality of life and muscle strength following ACL reconstruction (ACLR).

MATERIALS AND METHODS

MRI of n = 122 patients treated by ACLR without concomitant pathologies were evaluated. BB was differentiated by four localizations: medial/lateral femoral condyle (MFC/LFC) and medial/lateral tibial plateau (MTP/LTP). Severity was graded according to Costa-Paz. BB volumes of n = 46 patients were quantified (software-assisted volumetry). Outcome was measured by Lysholm Score (LS), Tegner Activity Scale (TAS), IKDC, isokinetics and SF-36. Measurements were conducted preoperatively (t0), 6 weeks (t1), 26 weeks (t2) and 52 weeks (t3) after ACLR.

RESULTS

The prevalence of BB was 91.8%. LTP was present in 91.8%, LFC 64.8%, MTP 49.2% and MFC 28.7%. 18.9% were classified Costa-Paz I, 58.2% II and 14.8% III. Total BB volume was 21.84 ± 15.27 cm3, the highest value for LTP (14.31 ± 9.93 cm3). LS/TAS/IKDC/SF-36/isokinetics improved significantly between t0-t3 (p < 0.001). Distribution, severity and volume had no influence on LS/TAS/IKDC/SF-36/isokinetics (n.s.).

CONCLUSIONS

No impact of BB after ACLR on function, quality of life and objective muscle strength was shown, unaffected by concomitant pathologies. Previous data regarding prevalence and distribution is confirmed. These results help surgeons counselling patients regarding the interpretation of extensive BB findings. Long-time follow-up studies are mandatory to evaluate an impact of BB on knee function due to secondary arthritis.

The Predicted Position of the Knee Near the Time of ACL Rupture Is Similar Between 2 Commonly Observed Patterns of Bone Bruising on MRI

BACKGROUND

Bone bruises observed on magnetic resonance imaging (MRI) can provide insight into the mechanisms of noncontact anterior cruciate ligament (ACL) injury. However, it remains unclear whether the position of the knee near the time of injury differs between patients evaluated with different patterns of bone bruising, particularly with regard to valgus angles.

HYPOTHESIS

The position of the knee near the time of injury is similar between patients evaluated with 2 commonly occurring patterns of bone bruising.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Clinical T2- and T1-weighted MRI scans obtained within 6 weeks of noncontact ACL rupture were reviewed. Patients had either 3 (n = 20) or 4 (n = 30) bone bruises. Patients in the 4-bone bruise group had bruising of the medial and lateral compartments of the femur and tibia, whereas patients in the 3-bone bruise group did not have a bruise on the medial femoral condyle. The outer contours of the bones and associated bruises were segmented from the MRI scans and used to create 3-dimensional surface models. For each patient, the position of the knee near the time of injury was predicted by moving the tibial model relative to the femoral model to maximize the overlap of the tibiofemoral bone bruises. Logistic regressions (adjusted for sex, age, and presence of medial collateral ligament injury) were used to assess relationships between predicted injury position (quantified in terms of knee flexion angle, valgus angle, internal rotation angle, and anterior tibial translation) and bone bruise group.

RESULTS

The predicted injury position for patients in both groups involved a flexion angle <20°, anterior translation >20 mm, valgus angle <10°, and internal rotation angle <10°. The injury position for the 3-bone bruise group involved less flexion (odds ratio [OR], 0.914; 95% CI, 0.846-0.987; P = .02) and internal rotation (OR, 0.832; 95% CI, 0.739-0.937; P = .002) as compared with patients with 4 bone bruises.

CONCLUSION

The predicted position of injury for patients displaying both 3 and 4 bone bruises involved substantial anterior tibial translation (>20 mm), with the knee in a straight position in both the sagittal (<20°) and the coronal (<10°) planes.

CLINICAL RELEVANCE

Landing on a straight knee with subsequent anterior tibial translation is a potential mechanism of noncontact ACL injury.

Traumatic bone marrow lesions in dual-energy computed tomography

Traumatic bone marrow lesions (TBMLs) are considered to represent a range of concealed bone injuries, including haemorrhage, infarction, and localised oedema caused by trabecular microfracture occurring in the cancellous bone. If TBMLs are not managed timeously, they potentially cause a series of complications that can lead to irreversible morbidity and prolonged recovery time. This article reviews interesting image findings of bone marrow lesions in dual-energy computed tomography (DECT). In addition to combining the benefits of traditional CT imaging, DECT also reveals and identifies various structures using diverse attenuation characteristics of different radiographic spectra. Therefore, DECT has the capacity to detect TBMLs, which have traditionally been diagnosed using MRI. Through evaluating DECT virtual non-calcium maps, the detection of TBMLs is rendered easier and more efficient in some acute accidents.

Distribution of Bone Contusion Patterns in Acute Noncontact Anterior Cruciate Ligament-Torn Knees

BACKGROUND

Bone contusions are commonly observed on magnetic resonance imaging (MRI) in individuals who have sustained a noncontact anterior cruciate ligament (ACL) injury. Time from injury to image acquisition affects the ability to visualize these bone contusions, as contusions resolve with time.

PURPOSE

To quantify the number of bone contusions and their locations (lateral tibial plateau [LTP], lateral femoral condyle [LFC], medial tibial plateau [MTP], and medial femoral condyle [MFC]) observed on MRI scans of noncontact ACL-injured knees acquired within 6 weeks of injury.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

We retrospectively reviewed clinic notes, operative notes, and imaging of 136 patients undergoing ACL reconstruction. The following exclusion criteria were applied: MRI scans acquired beyond 6 weeks after injury, contact ACL injury, and previous knee trauma. Fat-suppressed fast spin-echo T2-weighted MRI scans were reviewed by a blinded musculoskeletal radiologist. The number of contusions and their locations (LTP, LFC, MTP, and MFC) were recorded.

RESULTS

Contusions were observed in 135 of 136 patients. Eight patients (6%) had 1 contusion, 39 (29%) had 2, 41 (30%) had 3, and 47 (35%) had 4. The most common contusion patterns within each of these groups were 6 (75%) with LTP for 1 contusion, 29 (74%) with LTP/LFC for 2 contusions, 33 (80%) with LTP/LFC/MTP for 3 contusions, and 47 (100%) with LTP/LFC/MTP/MFC for 4 contusions. No sex differences were detected in contusion frequency in the 4 locations (P > .05). Among the participants, 50 (37%) had medial meniscal tears and 52 (38%) had lateral meniscal tears.

CONCLUSION

The most common contusion patterns observed were 4 locations (LTP/LFC/MTP/MFC) and 3 locations (LTP/LFC/MTP).

Longitudinal Effects of Acute Anterior Cruciate Ligament Tears on Peri-Articular Bone in Human Knees Within the First Year of Injury

Anterior cruciate ligament (ACL) tears are common sports-related knee injuries that increase the risk of developing post-traumatic osteoarthritis. ACL tears are rarely an isolated injury but are often associated with traumatic bone marrow lesions (BMLs). While early loss of bone mass following the ACL injury has been previously described, to date, microarchitectural information has not been reported due to the limited resolution of clinical imaging systems. In this study, we provide the first evidence of detailed bone mass and microarchitectural changes in the first 10 months following an acute ACL tear, and localized to traumatic BMLs. Fifteen participants with an acute unilateral ACL tear were assessed at four-time points using dual-energy X-ray absorptiometry and high-resolution peripheral quantitative computed tomography, and traumatic BMLs were identified with magnetic resonance imaging. Loss of bone mass was localized to the injured knee (-4.6% to -15.8%, depending on bone and depth) and was accelerated immediately following the injury before suggesting a recovery phase. This loss of bone was accelerated even greater in traumatic BMLs (-18.2% to -20.6%, depending on bone). Bone loss was accompanied by microstructural degeneration of trabecular bone. For example, in the lateral femur of the injured knee, the subchondral bone plate decreased in thickness (-9.0%). This study confirmed loss of bone mass in the months following ACL tears and described the underlying bone microstructural changes. The presented bone changes were accelerated in regions of traumatic BMLs. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2325-2336, 2019.

Bone bruise in anterior cruciate ligament rupture entails a more severe joint damage affecting joint degenerative progression

PURPOSE

During anterior cruciate ligament (ACL) injury, the large external forces responsible for ligament rupture cause a violent impact between tibial and femoral articular cartilage, which is transferred to bone resulting in bone bruise detectable at MRI. Several aspects remain controversial and await evidence on how this MRI finding should be managed while addressing the ligament lesion. Thus, the aim of the present review was to document the evidence of all available literature on the role of bone bruise associated with ACL lesions.

METHODS

A systematic review of the literature was performed on bone bruise associated with ACL injury. The search was conducted in September 2017 on three medical electronic databases: PubMed, Web of Science, and the Cochrane Collaboration. Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines were used. Relevant articles were studied to investigate three main aspects: prevalence and progression of bone bruise associated with ACL lesions, its impact on the knee in terms of lesion severity and joint degeneration progression over time and, finally, the influence of bone bruise on patient prognosis in terms of clinical outcome.

RESULTS

The search identified 415 records and, after an initial screening according to the inclusion/exclusion criteria, 83 papers were used for analysis, involving a total of 10,047 patients. Bone bruise has a high prevalence (78% in the most recent papers), with distinct patterns related to the mechanism of injury. This MRI finding is detectable only in a minority of cases the first few months after trauma, but its presence and persistence have been correlated to a more severe joint damage that may affect the degenerative progression of the entire joint, with recent evidence suggesting possible effects on long-term clinical outcome.

CONCLUSION

This systematic review of the literature documented a growing interest on bone bruise associated with ACL injury, highlighting aspects which could provide to orthopaedic surgeons evidence-based suggestions in terms of clinical relevance when dealing with patients affected by bone bruise following ACL injury. However, prospective long-term studies are needed to better understand the natural history of bone bruise, identifying prognostic factors and targets of specific treatments that should be developed in light of the overall joint derangements accompanying ACL lesions.

LEVELS OF EVIDENCE

IV, Systematic review of level I-IV studies.

Bone Bruises in Children and Adolescents Not Associated With Ligament Ruptures

Background:

Clinical characteristics of uncomplicated bone bruises (ie, not associated with a ligament rupture, meniscal tear, or fracture of the knee) in young athletes have scarcely been reported.

Purpose:

To identify mechanisms of injury, characterize bone bruise patterns, and identify clinical factors relating to recovery in young patients suffering uncomplicated bone bruises about the knee.

Study Design:

Case series; Level of evidence, 4.

Methods:

A review of clinical records and magnetic resonance imaging (MRI) findings of patients seen at a single institution was completed.

Results:

We identified 62 children and teenagers (mean age, 13.9 years; range, 8-18 years) who had a total of 101 bone bruises on MRI. The injuries occurred during a variety of organized and recreational sporting activities, the most common being football, basketball, and soccer. The majority (61.4%) of bone bruises occurred as a result of noncontact mechanisms. Patients reported a mean pain scale score of 6.3 of 10 (range, 2-10) on presentation. Frequent clinical findings included non–joint-line tenderness (64.5%), limited range of motion (58.1%), joint-line tenderness (54.8%), and positive meniscal signs (50.0%). The majority of bone bruises (61.4%) were located medially, and the most common bone bruise type was subcortical (58.4%), followed by medullary/reticular (35.6%) and articular impaction (5.9%). The only factor related to time to recovery was mechanism of injury; patients reporting a noncontact mechanism required significantly more time to recover than those reporting a contact mechanism (mean, 99.7 ± 74.8 vs 65.7 ± 38.8 days, respectively; F = 3.753, P = .049).

Conclusion:

In this case series of 62 pediatric patients with non–anterior cruciate ligament (ACL) bone bruises, the majority occurred in the medial compartment, suggesting that these bone bruises result from a mechanism distinct from the pivot-shift mechanism, classically thought to cause ACL injuries.

Bone marrow lesions in osteoarthritis: What lies beneath

Osteoarthritis (OA) is the most common joint disease in the United States, affecting more than 30 million people, and is characterized by cartilage degeneration in articulating joints. OA can be viewed as a group of overlapping disorders, which result in functional joint failure. However, the precise cellular and molecular events within which lead to these clinically observable changes are neither well understood nor easily measurable. It is now clear that multiple factors, in multiple joint tissues, contribute to degeneration. Changes in subchondral bone are recognized as a hallmark of OA, but are normally associated with late-stage disease when degeneration is well established. However, early changes such as Bone Marrow Lesions (BMLs) in OA are a relatively recent discovery. BMLs are patterns from magnetic resonance images (MRI) that have been linked with pain and cartilage degeneration. Their potential utility in predicting progression, or as a target for therapy, is not yet fully understood. Here, we will review the current state-of-the-art in this field under three broad headings: (i) BMLs in symptomatic OA: malalignment, joint pain, and disease progression; (ii) biological considerations for bone-cartilage crosstalk in joint disease; and (iii) mechanical factors that may underlie BMLs and drive their communication with other joint tissues. Thus, this review will provide insights on this topic from a clinical, biological, and mechanical perspective. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1818-1825, 2018.

MR Imaging of Patellar Cartilage Degeneration at 0.02 T

MR imaging with a 0.02 T resistive magnet was used to establish the correlation between the histologic grading of patellar cartilage degeneration and fat water separation images or T1- and T2-relaxation times. We examined 23 cadaveric patellae. There was a positive correlation between histologically graded cartilage degeneration and T1-relaxation time. Patellar cartilage was well differentiated from surrounding structures on chemical shift water proton images, and an evaluation of cartilage degeneration was possible. No correlation was found between cartilage damage and T2-relaxation time. Chemical shift imaging at 0.02 T is easy to perform and gives further information of cartilage disorders.

Low-Field Strength Magnetization Transfer Contrast Imaging of the Patellar Cartilage

The time-dependent saturation transfer (TDST) method was applied at 0.1 T in order to evaluate the magnetization transfer contrast (MTC) of the patellar cartilage in vivo. Nine knees were examined. The MTC image of the knee is also demonstrated. The MTC of 63% of the patellar cartilage was attained. Magnetization transfer MR imaging may be of additional help in the evaluation of cartilage disorders at low-field MR imaging.

Diseases of Subchondral Bone 1

The subchondral zone plays an important role in both the structural and biochemical maintenance of articular cartilage. Knowledge of the structure, function, and pathophysiology of the normal subchondral bone/articular surface interface is essential for an understanding of the pathogenesis of many of the disease entities that we will review in this chapter.

Midterm follow-up after implantation of a polyurethane meniscal scaffold for segmental medial meniscus loss: maintenance of good clinical and MRI outcome

PURPOSE

The preservation of meniscal structure and function after segmental meniscal loss is of crucial importance to prevent early development of osteoarthritis. Implantation of artificial meniscal implants has been reported as a feasible treatment option. The purpose of this study was to assess the clinical and magnetic resonance imaging (MRI) results 4 years after implantation of a polyurethane scaffold for chronic segmental medial meniscus deficiency following partial medial meniscectomy.

METHODS

Eighteen patients received arthroscopic implantation of an Actifit(®) polyurethane meniscal implant (Orteq Sports Medicine, London, UK) for deficiency of the medial meniscus. Patients were followed at 6, 12, 24, and 48 months. Clinical outcome was assessed using established patient-reported outcome scores (KOOS, KSS, UCLA Activity Scale, VAS for pain). Radiological outcome was quantified by MRI scans after 6, 12, 24, and 48 months evaluating scaffold morphology, tissue integration, and status of the articular cartilage as well as signs of inflammation.

RESULTS

Median patient age was 32.5 years (range 17-49 years) with a median meniscal defect size of 44.5 mm (range 35-62 mm). Continuing improvement of the VAS and KSS Knee and Function Scores could be observed after 48 months compared to baseline, whereas improvement of the activity level according to UCLA continued only up to 24 months and decreased from there on. The KOOS Score showed significant improvement in all dimensions. MRI scans showed reappearance of bone bruises in two patients with scaffold extrusion. No significant changes in the articular cartilage could be perceived.

CONCLUSION

Arthroscopic treatment for patients with chronic segmental meniscal loss using a polyurethane meniscal implant can achieve sustainable midterm results regarding pain reduction and knee function.

LEVEL OF EVIDENCE

IV.

Preliminary Result of Percutaneous Screw Fixation for Bone Bruise of the Tibial Plateau

This study reports the preliminary results of surgical treatment of bone bruise of the tibial plateau. Twelve patients underwent percutaneous screw fixation with a mean follow-up of 15 months. The mean duration of surgery was 15 minutes. Preoperatively, 1 week postoperatively, 1 month postoperatively, 6 months postoperatively, and 12 months postoperatively, the mean visual analog scale scores were 7.3, 2.6, 1.2, 0.6, and 0.5, respectively. The mean Hospital for Special Surgery scores were 56, 78, 89, 95, and 98, respectively. In selective patients with bone bruise, the percutaneous screw fixation is feasible to resolve pain and prevent compression of the articular surface.

Imaging Patterns in MRI in Recent Bone Injuries Following Negative or Inconclusive Plain Radiographs

BACKGROUND

Few bony injuries and most soft tissue injuries cannot be detected on plain radiography. Magnetic resonance imaging (MRI) can detect such occult bony injuries due to signal changes in bone marrow. In addition to excluding serious bony injuries, it can also identify tendon, ligament, cartilage and other soft tissue injuries and thus help in localizing the cause of morbidity.

AIMS AND OBJECTIVES

To determine the MRI imaging patterns in recent bone injuries (less than 4 weeks) following negative or inconclusive plain radiographs. To determine the role of MRI in recent fractures.

RESULTS

Out of the 75 individuals with history of recent injury of less than 4 weeks duration, fracture line was demonstrated in 16 patients (21%) who had no obvious evidence of bone injury on plain radiographs. Bone contusion or bruising of the bone was demonstrated in 39 (52%) patients. This was the commonest abnormality detected in MRI. The remaining 20 patients did not show any obvious injury to the bone on MR imaging however, soft tissue injury could be demonstrated in 12 (16%) patients which show that the extent of soft tissue injury was relatively well demonstrated by MR imaging. The present study showed that occult injuries commonly occur at the Knee followed by Ankle, Wrist, Foot, Elbow, Leg, Hands, Hips & Spine.

CONCLUSION

The study showed that MR is efficient in the detection of occult bone injuries which are missed on radiography. Compared to radiographs, MRI clearly depicted the extent of injuries and associated soft tissue involvement. MRI demonstrates both acute and chronic injuries and also differentiates both, whereas radiography has poor sensitivity for acute injuries. Also, the soft tissue injuries like tendionous and ligamentous injuries cannot be identified on radiographs.

Improvement in outcomes after implantation of a novel polyurethane meniscal scaffold for the treatment of medial meniscus deficiency

PURPOSE

Meniscal injury resulting in segmental loss of meniscal tissue is a major risk factor for the development of osteoarthritis. Tissue engineering strategies have provided scaffolds for meniscal regeneration in order to establish a treatment option for patients with limited opportunities for meniscal reconstruction. The purpose of this study was to assess the clinical and magnetic resonance imaging (MRI) results 2 years after implantation of a polyurethane scaffold for chronic segmental medial meniscus deficiency following partial medial meniscectomy.

METHODS

Eighteen patients were treated with arthroscopic implantation of an ActiFit(®) (Orteq Sports Medicine) polyurethane meniscal scaffold for meniscus deficiency of the medial meniscus. Patients were followed up at 6, 12, and 24 months. Clinical outcome was assessed using patient-reported outcome scores (KOOS, KSS, UCLA activity scale, VAS for pain). Radiological outcome was assessed using MRI at 6, 12, and 24 months by evaluating scaffold morphology, scaffold integration, and additional joint injury, as well as joint inflammation.

RESULTS

Eighteen patients with a median age of 32.5 years (range 17-49) were enrolled. Statistically significant improvements were present in all patients, but one at 2 years compared to baseline in all categories. Complete resorption of the scaffold occurred in one patient representing a failure to treatment. MRI showed abnormal signal intensity of the scaffold when compared to residual meniscal tissue but without synovitis or joint inflammation. Extrusion of the scaffold was present in four patients. No correlation between scaffold extrusion and clinical outcome was observed.

CONCLUSION

Arthroscopic implantation of a polyurethane meniscal scaffold in patients with chronic segmental medial meniscus deficiency is not only a safe procedure but leads to good clinical results at a 2-year follow-up. Scaffold extrusion did not appear to affect clinical outcome.

LEVEL OF EVIDENCE

IV.

Magnetic resonance imaging-based diagnosis of occult osseous injuries in traumatic knees

BACKGROUND

Occult osseous knee injuries, such as bone bruises, can produce persistent pain and functional loss. Although bone bruises cannot be identified through direct examination or traditional radiographs, magnetic resonance imaging (MRI) has emerged as an effective diagnostic method. Nevertheless, the natural history of these injuries remains to be fully defined. Therefore, we used MRI to detect and follow bone bruise injuries secondary to knee trauma.

METHODS

We retrospectively reviewed knee MRIs from patients with bone bruising caused by trauma. Occult injuries were initially identified by MRI and subsequently rescanned for follow-up at 3 and 9 months. All patients underwent physical examinations, direct radiological imaging, and MRI.

RESULTS

Although direct radiographs showed no abnormalities, we used MRI to identify a total of 22 patients (age range: 19-42 years; mean: 28 years) with bone bruising. After 3 months, injuries remained detectable in 68.2% of the subjects, whereas 18.2% displayed bone bruising after 9 months. The majority of Type I lesions resolved spontaneously, whereas 80% of Type II injuries remained following 3 months, and 30% persisted at 9 months. Ligament and meniscal lesions were observed in 63.6% of patients with bone bruising and appeared to hinder recovery.

CONCLUSION

Bone bruises generally resolved within 3 to 9 months in subjects with no soft tissue lesions and minor trauma. However, ligament and meniscal lesions were observed in the majority of patients, and these individuals required longer treatment and recuperation. Overall, these findings can contribute to improving the management of occult osseous knee injuries.

Bone bruises in anterior cruciate ligament injured knee and long-term outcomes. A review of the evidence

Background

Bone bruises are frequently associated with anterior cruciate ligament (ACL) tears as a result of trauma or direct shear stress of the bone.

Purpose

To review the evidence regarding the characteristics of the bone bruise associated with ACL tears, its relevance on clinical outcomes, and its progression over time. In particular, the long-term effects of the bone bruise on the knee osteochondral architecture and joint function were evaluated.

Study design

Review; level of evidence: 4.

Methods

An electronic search was performed on PubMed. Combinations of keywords included: “bone bruise AND knee”; “bone bruise AND anterior cruciate ligament”; “bone bruise AND osteo-chondral defects”. Any level of evidence studies concerning bone bruises in patients with partial or complete ACL tears were retrieved.

Results

A total of 25 studies were included; three of them investigated biomechanical parameters, seven were concerned with clinical outcomes, and 15 were radiological studies. Evaluation of the bone bruise is best performed using a fat-saturated T2-weighted fast spin echo exam or a short tau inversion recovery sequence where fat saturation is challenging. The location of the injury has been demonstrated to be more frequent in the lateral compartment of the joint (lateral femoral condyle and lateral tibial plateau). It is associated with ACL tears in approximately 70% of cases, often with collateral ligament or meniscal tears. Mid- and long-term outcomes demonstrated a complete healing of the marrow lesions at magnetic resonance imaging, but chondral defects detected with T1ρ sequences are still present 1 year after the ACL injury. Functional examination of the knee, through clinical International Knee Documentation Committee scores, did not show any correlation with the bone bruise.

Conclusion

Although bone bruise presence yields to higher pain levels, no correlation with functional outcomes was reported. Most studies have a short-term follow-up (<2 years) compared to the length of time it takes to develop post-traumatic osteoarthritis, so it still remains unclear whether the initial joint injury and bone bruise have a direct relationship to long-term function.

Use of dual-energy CT and virtual non-calcium techniques to evaluate post-traumatic bone bruises in knees in the subacute setting

OBJECTIVE

The purpose of this study was to determine the ability of dual-energy computed tomography (DECT) and virtual non-calcium (VNCa) imaging to detect magnetic resonance imaging (MRI)-demonstrated bone bruises several weeks after unilateral knee injury.

MATERIALS AND METHODS

Patients with unilateral knee injury and MRI-confirmed bone bruises who had undergone a DECT scan of both knees were retrospectively identified. Two radiologists evaluated VNCa images for bruises in four regions per knee without knowing the MRI results. The mean CT numbers were calculated for the lesion-positive and lesion-negative regions of the injured knee, and the contralateral knee.

RESULTS

Fourteen patients with a total of 36 regions positive for bone bruises on MRI were identified. The median delay between injury and DECT was 37 days (range, 11-99 days). The mean CT numbers in VNCa images for lesion-positive and lesion-negative regions were -7.6 ± 24.9 HU and -58.2 ± 19.5 HU, respectively. There were no significant differences in mean CT number between the lesion-negative regions in the injured knee and the contralateral knee. No resolution of bruising was seen before week 5, and bone bruising was still identifiable in one out of the two patients scanned at 10 weeks following injury.

CONCLUSIONS

DECT and VNCa images can identify bone bruising for at least 10 weeks after injury.

Comparison Between Sexes of Bone Contusions and Meniscal Tear Patterns in Noncontact Anterior Cruciate Ligament Injuries

BACKGROUND

Valgus load has been linked to female predominance and mechanism for noncontact anterior cruciate ligament (ACL) injuries. Magnetic resonance imaging (MRI) studies reporting frequent medial contusions in noncontact ACL injuries suggest anterior translation rather than a valgus mechanism.

HYPOTHESIS

Bone contusion and meniscal tear patterns differ between sexes.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

This study included a review of clinic notes, operative reports, and MRI of patients younger than 20 years who underwent acute primary ACL reconstruction for a noncontact injury between January 1, 2005, and January 1, 2010. A blinded musculoskeletal MRI radiologist reported the incidence of medial and lateral femoral and tibial bone contusions on MRI, as well as the severity of medial versus lateral tibial contusions. The location of the bone contusions and meniscal tears and the maximal tibial contusion severity were compared through chi-square analysis (statistical significance, P < .05).

RESULTS

A total of 73 patients met inclusion criteria: 28 males, 45 females; mean age, 16.1 ± 1.7 years (males), 16.5 ± 1.7 years (females). No significant differences were noted between sexes for location of tibial contusions (P = .32), femoral contusions (P = .44), or meniscal tears (P = .715). The most common tibial contusion pattern was to have both medial and lateral tibial contusions, in both male (57%) and female (60%) patients. The most common femoral contusion pattern was lateral only in females (62%) and both medial and lateral in males (50%). The percentage of female (29%) and male (29%) patients with isolated medial meniscal tears was nearly identical. More males (29%) than females (18%) had isolated lateral meniscal tears (P = .72). No significant difference in the relative severity of the tibial contusions was noted (P = .246). The lateral tibial contusion was rated as being more severe than the medial in the majority of females (64%) and males (57%).

CONCLUSION

No significant differences were detected between sexes with noncontact ACL injuries for location of tibial or femoral contusions or meniscal tears or for severity of medial versus lateral tibial contusions. The MRI data were not consistent with the valgus collapse mechanism of injury.

Bone bruise patterns in knee injuries: where are they found?

PURPOSE

Bone bruise represents an entity of occult bone lesions that can occur in the knee, causing knee pain and tenderness clinically. The aim of this study was to investigate the incidence and pattern of bone bruising seen in the anterior cruciate ligament (ACL) injury cohort, the non-ACL injury cohort, and between both cohorts.

METHODS

We reviewed 710 knee magnetic resonance imagings performed over a 6-month period. Eighty-eight patients with prior history of a knee injury were identified. The mechanism of injury and other clinical findings was noted.

RESULTS

Among these 88 patients, 58 patients had an associated ACL injury (31 had isolated ACL injuries; 27 had combined ACL and other ligamentous injuries). Among the 30 who had non-ACL injuries, 15 had either an MCL, LCL, or PCL injury. The remaining 15 patients had no associated ligament injury. With an ACL injury, the most common bone bruise sites are the lateral femur (74%) and lateral tibia (64%). Without an ACL injury, the pattern of bruising was more common in the lateral femur (69%) and medial tibia (37%).

CONCLUSION

Bone bruises are important as previous studies have shown that they can cause persistent knee pain. Our study has shown that there are differences in pattern of bone bruising in knee injuries with or without ACL injuries.

Mechanism of traumatic knee injuries and MRI findings

Bone bruises are focal abnormalities in subchondral bone marrow due to trabecular microfractures as a result of traumatic force. These trauma-induced lesions are better detected with magnetic resonance (MR) imaging using water-sensitive sequences. Moreover, the pattern of bone bruise is distinctive and allows us to understand the dynamics of trauma and to predict associated soft injuries. This article discusses the mechanism of traumatic injury and MR findings.

Fracturas en extremidades "Cuando se convierten en un reto diagnóstico"

El trauma en extremidades es un evento que se presenta a diario en los servicios de urgencias en la mayoría de veces es de fácil diagnóstico imagenológico solo con la radiología convencional. En algunas ocasiones la persistencia del dolor osteomuscular, sin mejoría con el manejo médico, es la situación que lleva a consultar de nuevo al paciente para explorar su causa y la radiología convencional no muestra lesión ósea por lo cual la patología se convierte en un reto diagnóstico para el personal médico lo que retraso en su diagnóstico y conlleva a posibles complicaciones. Dado a estas condiciones es importante conocer por parte del clínico la fisiopatología y los diferentes tipos de ayudas diagnósticas imagenológicas que le permitan diagnosticar a tiempo las fracturas ocultas. Nuestro objetivo es valorar la utilidad de las diferentes técnicas de imágenes diagnósticas en el estudio de las fracturas ocultas, realizando una búsqueda sistemática en la literatura de su fisiopatología, características, interpretación, uso racional y adecuado en las imágenes diagnósticas. [Pérez, L. Fracturas en extermidades. Cuando se convierten en un reto diagnóstico. MedUNAB 2013;16(1):24-33].

Determining bone bruises of the knee with magnetic resonance imaging

Introduction

Injuries that develop secondary to minor traumas and cannot be detected via direct examination methods, but are detected via advanced imaging methods, such as magnetic resonance (MR) imaging, are called occult bone injuries or bone bruises. In such injuries, diagnostic arthroscopy usually does not reveal any pathology. MR imaging methods are quite beneficial for the diagnosis of such clinical conditions, which cause acute pain and restriction of motion. The present study aimed to assess occult bone injuries via MR imaging in patients who presented with minor knee trauma.

Patients and Methods

Twelve patients who presented with minor knee trauma were included in the study. Etiological factors in these patients included walking a long distance, falls, and minor trauma. All patients underwent physical examinations, direct radiological imaging, MR imaging, and diagnostic arthroscopy.

Results

Direct radiographs of the patients showed no pathological fracture. Bone marrow changes detected on the MR images were classified according to Lynch’s classification as Type I lesions in nine patients and Type II lesions in three patients.

Conclusion

We suggest that MR imaging methods should be the gold standard for the diagnosis of minor traumatic bruise injuries of the knee.

The safety and short-term efficacy of a novel polyurethane meniscal scaffold for the treatment of segmental medial meniscus deficiency

PURPOSE

Meniscal loss is associated with an increased risk of developing osteoarthritis. Tissue engineering solutions, which include the development of novel material scaffolds, are being utilised to aid the regeneration of meniscal tissue. The purpose of this study was to monitor the safety profile and the short-term efficacy of a novel polyurethane meniscal scaffold in the treatment of patients with painful knees following partial medial meniscectomy.

METHODS

Ten consecutive patients with segmental tissue loss from the medial meniscus were treated with the arthroscopic implantation of an Actifit(®) (Orteq Sports Medicine) polyurethane meniscal scaffold. Patients were followed up at 2 and 6 weeks, then again at 6 and 12 months. Primary outcome measures included reporting of complications and patient-reported outcome scores (KOOS, KSS, UCLA Activity scale, VAS pain). Secondary outcome was MRI assessment at 6 and 12 months looking at scaffold morphology, integration and associated joint injury/inflammation.

RESULTS

Eight male and 2 female patients were included in the study with a mean age of 29 (range 18-45). No complications were reported. All patients were happy with their surgery. At 6 months, a statistically significant improvement (P < 0.05) in all PROMS except the UCLA activity scale and VAS pain scale were noted. The improvement remained at 12 months. MRI analysis revealed the presence of scaffolds at 6 months, with evidence of some tissue integration in many improvements in scaffold morphology and ICRS classification of cartilage in the medial compartment were noted at 12 months. No synovitis was noted in the joint or adverse reactions in the other compartments.

CONCLUSION

The new Actifit(®) polyurethane scaffold has been shown to be a safe, effective implant, for the treatment of patients with pain as a result of segmental medial meniscus loss at 1 year.

LEVEL OF EVIDENCE

IV.

Determination of the Interday and Intraday Reliability of Serum Cartilage Oligomeric Matrix Protein in a Physically Active Population

OBJECTIVE

To determine the intraday and interday reliability of serum cartilage oligomeric matrix protein (sCOMP) in a physically active population with no history of lower extremity surgery.

DESIGN

A repeated-measures reliability study was employed to determine the intraday and interday reliability of sCOMP in a physically active cohort. A total of 23 subjects were recruited to the laboratory on 3 separate occasions for nonfasting serum collection. Subjects had no history of lower extremity surgery and were free from acute injury within the last 3 months.

RESULTS

Our results indicate strong reliability for both intraday intraclass correlation coefficient (ICC) (0.76) and interday ICC (0.74) sCOMP values.

CONCLUSION

Our results demonstrate that following 30 minutes of inactivity, nonfasting serum samples remain stable over the course of 1 day and between 2 consecutive days in a healthy population with no history of lower extremity surgery. Future research studies are needed to further investigate the magnitude of change in this biomarker for patients with acute articular cartilage damage to determine its appropriateness for use in this population and for varying degrees of articular cartilage severity.

Magnetic resonance imaging of the knee after medial unicompartmental arthroplasty

OBJECTIVE

We evaluated safety and potential diagnostic value of magnetic resonance (MR) imaging of the knee treated with medial unicompartmental arthroplasty (MUA).

METHODS

The treated knee of 8 patients who underwent MUA was studied with four different 1.5-T MR sequences. Two radiologists independently evaluated eleven anatomical items using a score from 0 (not assessable) to 3 (completely assessable). The sum of the scores for each sequence was divided by the potential maximal sum, obtaining a percentage visibility index (PVI) for each item.

RESULTS

No adverse effect was reported during or within 30 min after the exam. Posterior cruciate ligament was unseen in all patients by both observers. The following PVIs were reported for the remaining ten items: femoral-patellar relationship 83-100%; femoral-patellar cartilage 92-100%; Hoffa's fat pad 75-92%; patellar ligament 79-100%; lateral meniscus 100%; femoral-tibial lateral joint 100%; lateral collateral ligament 96-100%; anterior cruciate ligament 54-83%; femoral-tibial lateral cartilages 92-100%; posterolateral corner 100%. Agreement between readers was found in 331/352 (94%) evaluations (k=0.74-0.78).

CONCLUSIONS

MR imaging after MUA offers a safe and reproducible evaluation of residual knee anatomy except for cruciate ligament, and can be used to follow-up these patients.

Magnetic resonance imaging in traumatic hip subluxation

Athletic traumatic hip subluxations are rare. Classic radiographic features have been well described. This case highlights the potential pitfalls of immediate magnetic resonance imaging. Femoral head contusions and acetabular rim fractures are common associated findings usually apparent with magnetic resonance imaging (MRI). However, in this case an MRI done 3 hours post injury failed to show any edema in either location, making the appearance of these findings on subsequent MRIs difficult to interpret. An acute MRI more than 48 hours post injury may have been more helpful.

Location of bone bruises and other osseous injuries associated with acute grade III isolated and combined posterolateral knee injuries

BACKGROUND

Bone bruises on magnetic resonance imaging (MRI) are common in patients with acute knee ligament injuries and have been well described for injuries involving the anterior and posterior cruciate ligaments and the medial collateral ligament. These have not yet been described in detail for posterolateral corner injuries.

HYPOTHESIS

Acute grade III posterolateral corner (PLC) injuries are often accompanied by bone bruises located in the medial compartment.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

One hundred two patients with acute grade III PLC knee injuries and MRI scans within 6 weeks of injury were prospectively identified. Images were reviewed for the location of bone bruises, which were defined as areas with high signal intensity adjacent to the joint surface on fat-suppressed, T2-weighted sequences.

RESULTS

Overall, 83 patients had at least 1 bone bruise and 56 patients had a bone bruise of the anteromedial femoral condyle. Tibial plateau fractures were found in 19 knees, with 12 in the anteromedial quadrant. Isolated PLC injuries were found in 28 patients; of this group, 18 had at least 1 bone bruise with 17 located in the anteromedial femoral condyle. Seventy-four patients sustained a combined ligamentous injury; 65 of these had at least 1 bone bruise on MRI and 39 had a bone bruise on the anteromedial femoral condyle. In patients with a combined injury to the PLC and anterior cruciate ligament (38), anteromedial femoral condyle bruises were seen in 19 patients and posteromedial tibial plateau bruises in 11.

CONCLUSION

Medial compartment bone bruises, most commonly of the anteromedial femoral condyle, were frequently found in patients with both acute isolated and combined PLC injuries. Thus, the presence of an anteromedial femoral condyle bone bruise should increase the level of suspicion of a concurrent PLC knee injury. In addition, we believe that the presence of a posteromedial tibial plateau bone bruise may be a secondary sign of a potential combined PLC injury in the setting of anterior cruciate ligament tear.

Bone bruise in acute traumatic patellar dislocation: volumetric magnetic resonance imaging analysis with follow-up mean of 12 months

OBJECTIVE

The aim of the study was to assess volumetric analysis of bone bruises in acute primary traumatic patellar dislocation by magnetic resonance imaging (MRI) and resolving resolution of bruises in follow-up MRI.

MATERIALS AND METHODS

MRI was performed in 23 cases. A follow-up examination was done at a mean of 12 months after dislocation. Volumes of patellar and femur bruises for every patient were evaluated separately by two musculoskeletal radiologists, and mean values of the bruises were assessed. Other MRI findings were evaluated, together with agreement by consensus. Bone bruise volumes were compared with other MR findings.

RESULTS

In the acute study 100% of patients showed bruising of the lateral femoral condyle and 96% bruising of the patella. The bruise was located at the medial femoral condyle in 30% and at the patellar median ridge in 74% of patients. The median volume of the femoral bruise was 25,831 mm(3) and of the patellar bruise 2,832 mm(3). At the follow-up study 22% of patients showed bruising of the lateral femoral condyle and 39% bruising of the patella, the median volumes of the bruises being 5,062 mm(3) and 1,380 mm(3), respectively. Larger patellar bruise volume correlated with larger femur bruise volume in the acute (r = 0.389, P = 0.074) and the follow-up (r = 1.000, P < 0.01) studies. Other MRI findings did not correlate significantly with bone bruise volumes.

CONCLUSION

Bone bruising is the commonest finding in cases of acute patellar dislocation, being seen even 1 year after trauma and indicating significant bone trabecular injury in the patellofemoral joint. A large bruise volume may be associated with subsequent chondral lesion progression at the patella. We concluded that the measurement of bone bruise volume in patients with acute patellar dislocation is a reproducible method but requires further studies to evaluate its clinical use.

Significance of magnetic resonance imaging signal change in the pedicle in the management of pediatric lumbar spondylolysis

STUDY DESIGN

Prospective study.

OBJECTIVE

To investigate the time course of signal changes in the adjacent pedicle in fresh pediatric lumbar spondylolysis.

SUMMARY OF BACKGROUND DATA

A recent study reported that high signal change (HSC) on T2-magnetic resonance image (MRI) in the pedicle adjacent to the pars interarticularis could be an indicator of early spondylolysis. In addition, the HSC-positive pars defects showed significant better bony healing than the HSC-negative pars defects. However, there has been no report on the time course and the duration of HSC.

METHODS

We prospectively investigated 10 boys and 5 girls with fresh lumbar spondylolysis showing HSC in the adjacent pedicle. Their mean age was 15.1 years, ranging from 10 to 17 years. Two patients had multilevel unilateral spondylolysis. Among 15 patients, HSC was found in 22 (12 unilateral and 5 bilateral) pedicles. At the first presentation, the diagnosis of spondylolysis was made based on the plain radiograph findings, multidetector computed tomograms (CTs), and MRI. Every month from the first presentation, follow-up MRIs were taken. When HSC disappeared, multidetector CT was taken to confirm bony healing of the pars defect.

RESULTS

Bony healing of the pars was obtained in 21 out of 22 defects. The bony healing rate was 95.6%. In 19 pedicles of 12 patients, HSC gradually diminished by every month until it disappeared 3 months later, and radiologic osseous healing was confirmed by CT in all but 1 patient. In the 3 remaining pedicles of 3 patients, HSC took more than 4 months to disappear.

CONCLUSION

In this study, HSC disappeared in most pedicles on the 3-month follow-up MRI. In patients who did not comply with treatment, HSC tended to last longer. These results led us to hypothesize that MRI at the third month during follow-up can indicate whether the conservative treatment is being successful or not.

MRI-detected subchondral bone marrow signal alterations of the knee joint: terminology, imaging appearance, relevance and radiological differential diagnosis

OBJECTIVE

To discuss terminology, radiological differential diagnoses and significance of magnetic resonance imaging (MRI)-detected subchondral bone marrow lesions (BMLs) of the knee joint.

METHODS

An overview of the published literature is presented. In addition, the radiological appearance and differential diagnosis of subchondral signal alterations of the knee joint are discussed based on expert consensus. A recommendation for terminology is provided and the relevance of these imaging findings for osteoarthritis (OA) research is emphasized.

RESULTS

A multitude of differential diagnoses of subchondral BMLs may present with a similar aspect and signal characteristics. For this reason it is crucial to clearly and specifically define the type of BML that is being assessed and to use terminology that is appropriate to the condition and the pathology. In light of the currently used terminology, supported by histology, it seems appropriate to apply the widely used term "bone marrow lesion" to the different entities of subchondral signal alterations and in addition to specifically and precisely define the analyzed type of BML. Water sensitive sequences such as fat suppressed T2-weighted, proton density-weighted, intermediate-weighted fast spin echo or short tau inversion recovery (STIR) sequences should be applied to assess non-cystic BMLs as only these sequences depict the lesions to their maximum extent. Assessment of subchondral non-cystic ill-defined BMLs on gradient echo-type sequences should be avoided as they will underestimate the size of the lesion. Differential diagnoses of OA related BMLs include traumatic bone contusions and fractures with or without disruption of the articular surface. Osteonecrosis and bone infarcts, inflammation, tumor, transient idiopathic bone marrow edema, red marrow and post-surgical alterations should also be considered.

CONCLUSION

Different entities of subchondral BMLs that are of relevance in the context of OA research may be distinguished by specific imaging findings, patient characteristics, symptoms, and history and are discussed in this review.

Bone bruising of the distal forearm and wrist in children

Bone bruising represents a new category of bone injury that can only be demonstrated by magnetic resonance imaging (MRI) with fat suppression. This study proposed the nature of non-radiographically evident injuries of the distal radius and wrist in children whose symptoms did not resolve after 5 weeks. We aimed to describe and classify the lesions and delineate the importance and potential complications of the injuries. Bone bruising was diagnosed in 20 patients (mean age: 11.6 years; range: 9-13 years). Bone bruises were classified according to anatomical location and whether they were solitary lesions or were combined with other injuries. Injuries of the distal radius were classified according to location: type 1 was localised to the metaphysis, close to the physeal plate; type 2 involved both the metaphysis and diaphysis; and type 3 extended on both sides of the distal radial growth plate. The type 1 injuries were consistent with complete, un-displaced Salter-Harris type I fractures, whilst type 3 lesions were potentially Salter-Harris type V injuries. Our data indicate that an MRI should be considered for a child with an injury to the distal radius or wrist whose symptoms do not resolve after 5 weeks of immobilisation.

Occult fractures of extremities

Recent advances in cross-sectional imaging, particularly in CT and MR imaging, have given these modalities a prominent role in the diagnosis of fractures of the extremities. This article describes the clinical application and imaging features of cross-sectional imaging (CT and MR imaging) in the evaluation of patients who have occult fractures of the extremities. Although CT or MR imaging is not typically required for evaluation of acute fractures, these modalities could be helpful in the evaluation of the occult osseous injuries in which radiographic findings are equivocal or inconclusive.

Bone bruises associated with ACL rupture: correlation with injury mechanism

BACKGROUND

Different patterns of bone bruising are seen on magnetic resonance imaging in acute anterior cruciate ligament ruptures. These patterns may relate to the mechanism of injury.

HYPOTHESIS

There is a correlation between the mechanism of anterior cruciate ligament injury and bone bruise patterns on magnetic resonance imaging.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Data regarding the mechanism of anterior cruciate ligament rupture were collected prospectively on patients who had anterior cruciate ligament reconstructions. Inclusion criteria included a clear history of mechanism, magnetic resonance imaging within 6 weeks of injury, and no previous knee injury. Patients were divided into noncontact and contact mechanism groups. Bone bruise frequency, location, depth, and intensity were analyzed using magnetic resonance imaging and correlated with the mechanism of injury.

RESULTS

Two hundred fifty-six patients were identified; 100 met the inclusion criteria, 86 were in the noncontact mechanism group, and 14 were in the contact mechanism group. The proportion of bone bruises in the lateral compartment in both groups was higher (P < .001) than in the medial compartment. Bone bruising was more frequent, deeper, and more intense in the noncontact group, with frequency (P = .019) and intensity (P < .001) scores reaching significance at the lateral tibial plateau. Medial compartment bone bruising was seen more frequently than previously reported, particularly in the noncontact group.

CONCLUSION

The noncontact mechanism appears to cause more severe bone bruising in both the medial and lateral compartments.

Association of knee bone bruise frequency with time postinjury and type of soft tissue injury

This study correlated the frequency of bone bruises with soft tissue injuries in the knee and examined bruise frequency as a function of time postinjury. Magnetic resonance imaging of 1546 patients revealed bone bruises in 19% of patients without an associated meniscal or ligamentous injury. For those patients presenting with at least one meniscoligamentous injury, the frequency of bruising was 60% at 0 to 4 weeks, 42% at 4 to 10 weeks, and 31% at 10 to 26 weeks postinjury. The frequency of bruising varied with the presence of concomitant injuries, with the greatest frequency of bruises (78%) observed in patients with anterior cruciate ligament injuries.

Histopathological perspective on bone marrow oedema, reactive bone change and haemorrhage

This article presents a systematic review of the current biomedical literature surrounding the aetiopathogenesis and histopathological features of bone marrow oedema, reactive bone change and haemorrhage. Bone marrow oedema is generally demonstrated as a non-specific finding on magnetic resonance imaging in association with infections, tumours and avascular necrosis. When it occurs in isolation as a primary event not triggered by any obvious bony pathology in the clinical setting of debilitating joint pain, it constitutes the "bone marrow oedema syndrome". Although the latter diagnosis is based on magnetic resonance (MR) imaging, showing the lesion as areas of signal hyperintensity within the marrow, recent radiology-histology correlational studies have shown variably interstitial marrow oedema, necrosis, fibrosis and trabecular bone abnormalities. In light of these facts, the use of the term bone marrow oedema syndrome in a radiological context might be considered questionable, but histopathological techniques are not sensitive in detecting increased extracellular fluid. Reactive bone changes may be focal or diffuse and usually amount to increased bone formation. Bone marrow haemorrhage, due to trauma, results in bone bruising, a condition in which the size of the bruise and associated osteochondral injury determines the outcome, although the natural history of these lesions is still being researched.

Articular cartilage injury of the posterior lateral tibial plateau associated with acute anterior cruciate ligament injury

Thirty-nine knees in 39 patients with recent anterior cruciate ligament (ACL) rupture (age 14-55 years; with a mean age of 22.8 years) were selected from our cases of ACL reconstruction from July 2005 to June 2006, to take part in a study on articular cartilage injury of the posterior lateral tibial plateau associated with acute ACL injury and on the correlation between bone bruises depicted on MRI and cartilage injury of the posterior lateral tibial plateau detected at arthroscopic ACL reconstruction. Using preoperative MRI, we evaluated whether there were bone bruises or not in the lateral compartment of the knee and divided them accordingly into two groups: the bone bruise positive group and the negative group. The differences in the proportions of the lateral meniscus (LM) tears and the cartilage injuries in the two groups were evaluated using Fisher's exact probability test. Thirty-five cases out of 39 arthroscopic ACL reconstructions (89.7%) were regarded as bone bruise positive in the lateral compartment and four cases (10.3%) were regarded as negative. At arthroscopic ACL reconstruction, 33 cases (84.6%) had tears in the LM posterior horn, 34 cases (87.2%) had articular cartilage injuries in the lateral femoral condyle and 29 cases (74.3%) had articular cartilage injuries in the posterior lateral tibial plateau. From 35 bone bruise positive cases, 32 cases (91.4%) had tears in the LM posterior horn, 33 cases (94.3%) had articular cartilage injuries in the lateral femoral condyle and 28 cases (80%) had articular cartilage injuries in the posterior lateral tibial plateau. Of four bone bruise negative cases, one case (25%) had a tear in the LM posterior horn, articular cartilage injury of the lateral femoral condyle and of the posterior lateral tibial plateau. There was a statistically significant correlation between the proportion of bone bruise and cartilage injury of the lateral femoral condyle (P = 0.004), that of the posterior lateral tibial plateau (P = 0.04) and that of tears in the LM posterior horn (P = 0.008). This current study has demonstrated that we need to pay attention to cartilage damage of the posterior lateral tibial plateau as well as to posterior horn tears in LM, when acute ACL injury is shown. We also have to ensure that we follow the long-term progress of cartilage injuries, with the aim of preventing these injuries becoming osteoarthritis after ACL reconstruction.

Bone bruise in magnetic resonance imaging strongly correlates with the production of joint effusion and with knee osteoarthritis

BACKGROUND

The findings of magnetic resonance imaging (MRI) have not been studied systematically in patients with osteoarthritis (OA). The objective here was to compare MRI findings with radiological findings in patients with knee pain and to identify factors that influence the progression of OA of the knee.

METHODS

Of 212 patients with knee pain and MRI of the knee joint, 161 patients were selected for the study after exclusion of cases of trauma and other arthritides. MRI was used to evaluate the presence and degree of bone bruise, hydrarthrosis, and injuries to the cruciate ligament and meniscus. Bone bruise was classified into four types, and hydrarthrosis into four grades. Radiologically, OA progression in the femorotibial and patellofemoral joints was analyzed according to the Kellgren-Lawrence classification. Age was divided into four groups based on distribution quartiles. Logistic regression analysis and a generalized linear model with Poisson regression were used to analyze correlations among these factors.

RESULTS

Bone bruise was present in 87 cases, hydrarthrosis in 100, cruciate ligament injury in 20, and meniscus injury in 98. The presence of bone bruise was not related to age, cruciate ligament injury, meniscus injury, nor to OA of the patellofemoral joint, but was related to hydrarthrosis and to OA of the femorotibial joint. Femorotibial OA was much more strongly associated with bone bruise than with hydrarthrosis. Furthermore, analyzing the relation between the types of bone bruise and the degree of hydrarthrosis using a generalized linear model with Poisson regression, there was a positive correlation between the grade of bone bruise and the amount of hydrarthrosis.

CONCLUSIONS

A factor associated with the degree of osteoarthritis of the knee is bone bruise observed on MRI. The degree of hydrarthrosis is related to the grade of bone bruise, but is not linked to the degree of osteoarthritis.

MRI Follow-Up of Posttraumatic Bone Bruises of the Knee in General Practice

OBJECTIVE

Our purpose was to study the natural course of bone bruises in posttraumatic knees and to describe possible determinants of this course.

SUBJECTS AND METHODS

Prospective MRI follow-up data were gathered for patients with bone bruises after sustained knee trauma. Follow-up ceased when the bone bruise could no longer be discerned or after 1 year of follow-up. For each patient we studied the relationships between time to healing of all bone bruises and the explanatory variables age, sex, obesity, workload, sports load, number of bone bruises, osteoarthritis, and concomitant knee lesions using survival analyses. We also investigated the relationships between resolution of individual bone bruises and lesion type, size and location, and the explanatory variables at 6 months and at 12 months separately, using logistic regression analyses for repeated measurements and generalized estimating equations.

RESULTS

In 80 patients, 157 bone bruises were found. The estimated median healing time was 42.1 weeks. Healing was prolonged in patients having a higher number of bone bruises and in the presence of osteoarthritis. Resolution of individual bone bruises was prolonged in the presence of osteoarthritis and greater age. Reticular lesions were less likely to be present after 6 months than other bone bruise types. None of the remaining tested variables had prognostic value.

CONCLUSION

Median healing time of bone bruises is 42.1 weeks. Prognosis is particularly influenced by the presence of osteoarthritis. Age, type of bone bruise, and number of bruises also have prognostic value.

MAGNETIC RESONANCE IMAGING FEATURES OF OBLIQUE AND STRAIGHT DISTAL SESAMOIDEAN DESMITIS IN 27 HORSES

Injury to the oblique and straight distal sesamoidean ligaments is becoming recognized as a more common cause of lameness in horses than was previously thought. The purpose of this study was to review the magnetic resonance (MR) imaging findings of 27 horses affected with desmitis of the oblique and/or straight distal sesamoidean ligament and determine long-term prognosis for horses with this diagnosis. Imaging was performed with horses in right lateral recumbency in a high-field 1 T magnet. All horses had lameness localized to the digit or metacarpophalangeal/metatarsophalangeal joint region with diagnostic local anesthetic blocks. Ten horses had forelimb lameness and 17 horses had hind limb lameness. MR imaging revealed abnormalities in the oblique distal sesamoidean ligaments in 18 horses, in the straight distal sesamoidean ligament in three horses, and in both the oblique and straight distal sesamoidean ligament in six horses. Treatment consisted of a 6-month rest and rehabilitation program in all horses. The digital flexor tendon sheath was injected with methylprednisolone acetate and hyaluronic acid in 22 horses to decrease inflammation in the injured ligaments before starting the rest and rehabilitation program. Two horses had ligament splitting performed, one in the oblique distal sesamoidean ligament and one in the straight distal sesamoidean ligament. MR imaging is an effective method for diagnosing injury to the oblique and straight distal sesamoidean ligaments in horses. Treatment, primarily a 6-month rest and rehabilitation program, allowed 76% of the horses to successfully resume performance.

Natural history of bone bruises after acute knee injury: clinical outcome and histopathological findings

The purpose of this paper is to review the scientific literature on the natural history of bone bruises and the experimental studies regarding the histopathological effects of impaction load on articular cartilage and subchondral bone. Bone bruises with subchondral or osteochondral injuries, or geographic bone bruises seemed to be persistent for years after trauma on MRI. Biopsy samples of the articular cartilage overlying the bone bruise lesions showed degeneration or necrosis of chondrocytes and loss of proteoglycan. Experimental studies using a single impact load revealed chondrocytes death, alteration of the mechanical properties of cartilage explants and/or an increase in the thickness of subchondral bone. These data are indicative of a significant injury to normal articular cartilage homeostasis, and support the suggestion that severe bone bruise is a precursor of early degenerative changes. We recommend delaying return to full weightbearing status when a severe bone bruise is detected to prevent further collapse of subchondral bone and further aggravation of articular cartilage injury.

Follow-up of Occult Bone Lesions Detected at MR Imaging: Systematic Review

PURPOSE

To perform a systematic review of the literature regarding the natural course of posttraumatic occult bone lesions (often referred to as bone bruises) detected at magnetic resonance (MR) imaging.

MATERIALS AND METHODS

A systematic review of the literature was performed by searching the MEDLINE database (from January 1966 to February 2003) with the keywords bone bruise, trauma, follow-up, and MRI. Keywords were linked by using the Boolean operator AND. Studies were included if all of the following criteria were fulfilled: patients sustained trauma, MR imaging was used as a diagnostic method, results of clinical or MR imaging follow-up were available, and study was written in English, Dutch, German, French, Spanish, Italian, Swedish, Danish, or Norwegian. The quality of each study was assessed by using a standardized criteria set, and kappa statistics were estimated to rate the level of agreement between the two reviewers. Results were compared with regard to study design and quality scores.

RESULTS

The MEDLINE search identified 266 articles, 13 of which met the inclusion criteria. The quality of the included studies was moderate. The two reviewers initially agreed on 179 quality items (kappa = 0.84). The study population was generally small, and follow-up periods ranged from 1 to 73 months. Four different classification systems were used, and in two studies bone bruise was not specified. Study results suggest a generally good clinical prognosis of bone bruises. Normalization of MR imaging appearance is possible and is most often encountered after the occurrence of reticular lesions. Cartilage loss at follow-up is often found in cases of initial cartilage damage (impaction or osteochondral fracture).

CONCLUSION

In general, a healing response was often encountered after sustained posttraumatic occult bone lesions. The initial MR imaging appearance appears to have prognostic value.