Bone bruises are a diagnosis of the MRI scan era. These scans which came into widespread use at reasonable diagnostic accuracy in the early 1990s. This is of course a real handicap when it comes to determining a prognosis for the long term. In the early days images were relatively poor, and because the prognosis was assumed to be benign, these patients were generally not followed up. So our long-term follow-up of these lesions is somewhat lacking….
The term ‘bone bruise’ is synonymous with bone contusion, occult microfracture, or subchondral osseous lesion. I’m going to quickly canter through the literature (which in some cases is contradictory or not conclusive) on the following bone bruise topics:
- diagnosis & classification
- Where you find them, and what they mean in different circumstances
- associations with other pathology
- controversies, such as whether they mean a more painful recovery or not, etc
- long-term prognosis of the lesion, where available
Diagnosis & Classification.
The MRI features are of poorly marginated areas of abnormality with decreased signal intensity on T1-weighted sequences, increased signal intensity on T2-weighted sequences, or both. These features result from haemmorhage or oedema in trabecular bone.
Apart from the upper humerus, there isn’t much volume of trabecular bone in the upper limb, so the majority of the literature concerns the knee, foot & ankle, and hip.
The basic pattern is of either ‘reticular’ or ‘geographic’ bruises.
Reticular (network or net-like pattern) bone bruises are phenomena of medullary bone, at a distance from the joint surface/subchondral bone plate. They show as a serpiginous region of increased T2-weighted fat-suppressed signal.
https://www.ajronline.org/doi/full/10.2214/AJR.07.2276
These are less likely than other bruise types to be still present at 6 months post-injury.
A geographic bone bruise is a phenomenon of the subchondral bone adjacent to a joint. In the knee, the pattern of the bruising may be characteristic of particular types of injury:
- ACL pivot-shift injury – posterior margin tibial plateau & mid- portion lateral femoral condyle
- PCL injury – anterior tibia at point of impact
- Hyper-extension injury – anterior bruises femoral & tibial condyles, +/- ACL/PCL injuries; medial or lateral position of bruises may indicate varus/valgus stresses at impact
- ‘Clip’ injury or injury sustained in a tackle – bruise lateral femoral condyle and injury to medial collateral ligament of knee
- Patella dislocation – anterolateral aspect lateral femoral condyle and medial aspect of patella. There may be signs of oedema at the femoral attachment of the medial patellofemoral ligament (MPFL)
Pathogenesis & Outcome.
When first described, it was thought that bone bruises would clear up with no sequelae. That early view has since changed as far as many doctors are concerned.
Some bone bruises may behave benignly, but some seem to be associated with cartilage injury and later degeneration.
Munk & Vellet, 1993. ‘Lesions of Cartilage & Bone Around the Knee’. Topics in Magnetic Resonance Imaging. 5(4): 249-262.
These authors described subchondral fractures and bone ‘contusions’; and recognised that these lesions may be of significance in the development of degenerative change. They described the classical lesion associated with ACL rupture as being an impaction injury of the lateral femoral condyle just above the anterior horn of the lateral meniscus, and another on the posterior lip of the tibia. Degradation of cartilage above these trabecular fractures can be detected as early as 6-12 months post-injury. The overlying cortex may or may not be intact initially.
1998, Miller et al. ‘The Natural History of Bone Bruises. A Prospective Study of Magnetic Resonance Imaging-Detected Trabecular Microfractures in Patients with Isolated Medial Collateral Ligament Injuries.’ Am J Sports Med. Vol 26, No 1, 1998: 15-19.
MRI was performed in 65 patients with medial collateral ligament injuries, identifying 29 (45%) trabecular microfractures/bone bruises. 83% were followed up; in all the bone bruises resolved over 2-4 months.
1999. Faber et al. ‘Occult Osteochondral Lesions After Anterior Cruciate Ligament Rupture. Six-Year Magnetic Resonance Imaging Follow-up Study’. THE AMERICAN JOURNAL OF SPORTS MEDICINE, Vol. 27, No. 4, 489-494.
n=23, 6 year clinical & MRI review. Marrow signal changes persisted in 15 (65%) of the patients. There was no evidence of significant cartilage thinning of the lateral tibial plateau over this timescale. However, the lateral femoral condyle showed thinning in 2 patients initially, but thinning was present in 13 at follow-up. 8 of these patients had concomitant subchondral bone changes. 10 patients had no thinning. The authors suggested that the initial injury caused irreversible changes in the knee.
2000. Sanders et al. ‘Bone Contusion Patterns of the Knee at MR
Imaging: Footprint of the Mechanism of Injury’. RadioGraphics 2000; 20:S135–S151
Good teaching article; good illustrations. More ‘cut & dried’ than real life.
2002. Bretlau et al, ‘Bone bruise in the acutely injured knee‘. Knee Surg, Sports Traumatol, Arthrosc (2002) 10 :96–101
DOI 10.1007/s00167-001-0272-9
n=64. Acute trauma to knee. Bone bruise (BB) present in 35; follow-up MRI at 4 months & 12 months. 69% BB present at 4 months, 12% at 12 months. Damage to menisci or knee ligaments found in 94% of BB. In patients with no BB, the number of ligament injuries was lower.
2006. Nakamae et al. ‘Natural history of bone bruises after acute knee injury: clinical outcome and histopathological findings’. Knee Surg Sports Traumatol Arthrosc (2006) 14:1252–1258
DOI 10.1007/s00167-006-0087-9
These authors reviewed publications relating to the natural history of BB. Bone bruises with subchondral or osteochondral injuries, or geographic bone bruises seemed to persist on MRI, sometimes for years after the trauma. Biopsies of articular cartilage taken from over the lesions revealed degeneration or necrosis of chondrocytes & loss of proteoglycan. These authors felt that BB were indicative of a significant injury to articular cartilage, and support the suggestion that severe BB is a precursor of degenerative change.
2007. Boks et al. ‘MRI Follow-Up of Posttraumatic Bone Bruises of the Knee in General Practice’. AJR 2007; 189:556–562. DOI:10.2214/AJR.07.2276
n=80 patients, 157 BB. The median healing time for bone bruises was 42.1 weeks. Healing was prolonged in the presence of OA or in older individuals. Reticular lesions healed faster and were less likely than other types to be present after 6 months.
2007, Boks et al. ‘Clinical Consequences of Posttraumatic
Bone Bruise in the Knee’. The American Journal of Sports Medicine, Vol. 35, No. 6
DOI: 10.1177/0363546506297059
There is no statistically significant relationship, nor a clinically relevant relationship, between the presence of bone bruise and pain severity in patients who sustained knee injury in general practice.
2009. Vannet, Kempshall, & Davies, reported ‘Secondary collapse of lateral femoral condyle following bone bruise: A case report’. Acta Orthop. Belg., 2009, 75, 695-698.
This bone bruise was associated with ACL rupture, & lateral meniscus tear. He re-presented 12 days later with partial collapse of the condyle, and received a surgical reduction by elevation. Bone bruises are not necessarily innocuous.
2018, Filardo et al. ‘Bone bruise in anterior cruciate ligament rupture entails a more severe joint damage affecting joint degenerative progression’. Knee Surgery, Sports Traumatology, Arthroscopy (2019) 27:44–59
https://doi.org/10.1007/s00167-018-4993-4
Systematic review. n=10,047. Prevalence BB in ACL injury 78%. Higher prevalence on lateral side of the knee. Thought that the presence & persistence of BB linked to worse long term outcome.
2018. Gomez et al. ‘Bone Bruises in Children and Adolescents
Not Associated With Ligament Ruptures’. The Orthopaedic Journal of Sports Medicine, 6(7), 2325967118786960
DOI: 10.1177/2325967118786960
n=62 paediatric patients with 101 bone bruises not associated with ACL injury. 61% occurred in non-contact mechanisms. 61% were medial. 58% were subcortical, followed by medullary/reticular (35%), & articular impaction (6%). Non-contact mechanisms took longer to heal (99 days versus 65 days.
2018, Aravindh et al. ‘Association of Compartmental Bone Bruise
Distribution With Concomitant Intra-articular and Extra-articular Injuries in Acute Anterior Cruciate Ligament Tears After Noncontact Sports Trauma’. The Orthopaedic Journal of Sports Medicine, 6(4), 2325967118767625
DOI: 10.1177/2325967118767625
n= 155/168 patients (92%). BB in the lateral compartment of the knee are associated with lateral meniscus injuries. BB involving both compartments are associated with MCL & LCL injuries in addition to lateral meniscus injuries. Demographic factors not associated with any particular pattern, presence or absence of BB. BB detected at >3 months after injury presaged a more difficult return to full activity and maybe a worse long-term prognosis. The review highlighted differences in sequences, definitions etc..
Summary:
- the MRI features are of poorly marginated areas of abnormality with decreased signal intensity on T1-weighted sequences, increased signal intensity on T2-weighted sequences, or both
- reticular bone bruises resolve quicker than subchondral/geographic bone bruises, and have a better prognosis
- in the majority of cases, bone bruises in the knee are accompanied by significant ligamentous and/meniscal injuries
- the placement of the bone bruises may indicate the type of accompanying soft tissue injury
- persistent bone bruises may indicate a more severe injury & a worse long-term prognosis
- pain is not significantly related to the presence of bone bruise
- in children without ACL injury the prognosis is good