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

ORIGINAL ARTICLE

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

Yuin Cheng Chin • Ramesh Wijaya • Le Roy Chong •

Haw Chong Chang • Yee Han Dave Lee

Received: 15 July 2013 / Accepted: 8 September 2013

� Springer-Verlag France 2013

Abstract

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 inves-

tigate 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 ima-

gings 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.

Keywords Knee � Bone contusion � Ligament

injury

Introduction

Bone bruise represents an entity of occult bone lesions that

can only be picked up by magnetic resonance imaging

(MRI). Clinically, it can cause pain and tenderness.

It is defined by Mink and Deutsch [1] to be a traumat-

ically involved, geographic, and nonlinear area of signal

loss involving the subcortical bone detected on T1-

weighted magnetic resonance images and as increased

signal intensity on T2-weighted images. Its occurrence in

the knee is commonly associated with more serious liga-

ment injuries such as rupture of the anterior cruciate liga-

ment (ACL) [2–6] where bone bruises are found in the

lateral compartment of the knee [4, 5, 7, 8].

Previous studies have shown that the location of bone

bruise in the knee reflects the mechanism of injury and the

accompanying ligamentous injury [9]. It has been widely

reported that the presence of a lateral compartment bruise

is in keeping with an ACL injury from the pivot shift

mechanism [9, 10].

Sanders et al. [9] described five different mechanisms of

injuries and the accompanying bone bruise pattern: pivot

shift, dashboard, clip, hyperextension, and lateral patella

dislocation injuries. He found that the pivot shift injury

loads the ACL and can result in its rupture. Once the ACL

Y. C. Chin (&)

Yong Loo Lin School of Medicine, National University of

Singapore, Singapore, Singapore

e-mail: [email protected]

R. Wijaya

Department of General Surgery, Changi General Hospital,

Singapore, Singapore

L. R. Chong

Department of Diagnostic Radiology, Changi General Hospital,


H. C. Chang � Y. H. D. Lee

Department of Orthopaedic Surgery, Changi General Hospital,


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Eur J Orthop Surg Traumatol

DOI 10.1007/s00590-013-1319-6

is disrupted, anterior subluxation of the tibia relative to the

femur occurs. This results in impaction of the lateral

femoral condyle against the posterolateral margin of the

lateral tibial plateau. The resulting bone contusion pattern

involves the posterior aspect of the lateral tibial plateau and

the midportion of the lateral femoral condyle near the

condylopatellar sulcus.

Lateral compartment bruises are also associated with

MCL injury. This has been described by Miller et al. [11]

where they studied on the prevalence and location of bone

bruises associated with MCL injury. This pattern of bruising

has been attributed to the direct impact of a valgus stress that

results in an impaction force opposite the ligamentous injury.

Mair et al. [12] describe the location of bone bruises

associated with PCL injury to be more widely dispersed

about the knee medially, laterally, and involving the patella.

This varied pattern of bruising has been postulated to be

because PCL injury does not usually occur in isolation but

with other ligamentous injury (e.g., MCL and LCL).

While medial compartment bruises have been said to

correlate with LCL/posterolateral injury from the hyper-

extension–varus injury mechanism [12], there are few

studies that describe the mechanism of medial side bruising

in ACL injuries. Kaplan et al. [7] suggested that a bone

contusion in the medial compartment in an ACL injury

might occur as a contrecoup mechanism by means of

compensatory varus alignment and internal rotation of the

femur after the initial injury with the pivot shift mechanism.

A recent study carried out by Kyoung et al. [13] found

that the prevalence of injuries involving the menisci and

MCL tended to increase according to the increasing extent

of the bone contusion. This finding suggests that a greater

force results in a greater bone contusion throughout the

knee and has been shown by Kyoung et al. [13] that this is

associated with more meniscus injury.

Our aims of this study were to investigate the incidence

and pattern of bone bruising seen in the ACL injury cohort,

the non-ACL injury cohort, and between both cohorts.

We hypothesized that (1) there would be a difference in

the pattern of bruising between the ACL and non-ACL

injury cohort; (2) there would be a difference in the pattern

of bruising between isolated and combinatory ACL injury;

and (3) medial side bone bruising would occur more

commonly in patients with multi-ligamentous injury or

meniscal injury.

Patients and methods

We reviewed the knee MRIs of all patients \50 years of

age, who had an injury to the knee, over a 6-month period

between January and June 2009. Knee MRIs were

performed on these patients for pain, trauma history, and

instability complaints within 10 weeks of a well-described

injury.

The MRI examination consisted of oblique sagittal T2-

weighted, sagittal intermediate spin density, T2-weighted

images, and T1-weighted coronal images on a 1.5 T

magnet. The presence of bone bruise on MRI was reflected

as an area of decreased signal intensity seen on T1-

weighted images and increased signal intensity on T2-

weighted images [14].

A consultant musculoskeletal radiologist reviewed 710

consecutive MRIs of the knee performed at tertiary level

institution over this 6-month period. The MRI scans were

assessed for the location of bone bruise and any associated

ligamentous injury. The location of bone bruise was

described to be either in the medial or lateral tibia, femur or

patella. The ligament injuries were divided into those with

isolated ACL injury and combined ACL and other ligament

injuries.

The case notes were retrospectively reviewed for the

mechanism of injury (contact or non-contact).

For the mechanism of injury, patients were classified

into the contact group if there was an external force applied

to the knee (such as a blow to the knee). If there was no

external force to the knee at the time of the injury, the

mechanism was classified as non-contact (twisting injury).

Statistical analysis

Demographic and clinical characteristics of the orthopedic

patients involving categorical variables are summarized

using counts and percentages. For continuous variables, the

mean and standard deviation were used to describe the data

distribution. The associations between outcome and cate-

gorical risk factors were tested using the Fisher’s exact test

due to the presence of small counts. Differences in means

between two groups were compared using the Student’s

t test. Effect estimates for categorical variables were cal-

culated as prevalence ratios. For continuous variables, the

effect estimates were calculated as the difference in means.

All statistical analyses were generated using the STATA

software, version 11 (StataCorp LP, College Station, TX,

USA), and SPSS, version 20, using a two-sided test at the

5 % level of significance.

Results

Of the 710 MRI investigations performed, 88 patients had

bone bruises identified on the MRI. There were 72 males

(81.8 %) and 16 females (18.2 %). The mean patient age was

26.9 years (SD 9.2). Of these 88 patients, 71 (80.7 %) had


123

bruising in the femur, 62 (70.5 %) in the tibia, and nine

(10.2 %) in the patella. The mechanism of injury for 65

patients (73.9 %) was non-contact in nature while the

remaining 23 patients (26.1 %) suffered from a contact injury.

Fifty-eight patients, out of the 88, had an ACL injury

while the remaining 30 had non-ACL injury. The various

subdivisions of the cohort with ACL injury and the cohort

with non-ACL injury are listed in Fig. 1.

ACL and non-ACL injury cohort

The prevalence ratio of 0.62, 95 % CI [0.37, 1.05], indi-

cates a 38 % reduction in the prevalence of ACL injury in

the contact group as compared with the non-contact

(twisting) group. This suggests that the main mechanism of

ACL injury is non-contact (twisting) rather than contact.

The prevalence ratio of 2.01, 95 % CI [1.36, 2.98],

indicates that the prevalence of ACL injuries in patients

with tibia bruising is twice that of those without tibia

bruising. This suggests that patients with ACL injuries tend

to have tibia bruise.

The prevalence ratio of 1.93, 95 % CI [1.38, 2.70],

indicates that the prevalence of ACL injuries in patients

with lateral tibia bruising is twice that of those without

lateral tibia bruising. This suggests that patients with ACL

injuries tend to have lateral tibia bruise.

However, there was no evidence of difference between

the 2 cohorts when comparing the pattern of femur and

patella bruising and the pattern of bruising in the medial and

lateral compartments. Table 1 summarizes these results.

Isolated and combined ACL injury cohort

The prevalence ratio of 0.96, 95 % CI [0.58, 1.59], indi-

cates that there was no difference between the number of

bruises when comparing the patients with isolated or

combined ACL injury.

Although there was a pattern of increased incidence of

bruising in the medial tibia and medial femur with the

combined ACL and other ligament injury compared to the

isolated ACL injury, this was not found to be statistically

significant. There was no evidence of difference between

Frequency ACL + PCL 3 ACL + MCL 8 ACL + MCL + LCL 8 ACL + MCL + PCL 3 ACL + LCL 4 ACL + LCL + PCL 1 Total 27

Frequency PCL 4 PCL + MCL 2 PCL + LCL 1 MCL 4 MCL + LCL 2 LCL 2 Total 15

710 MRI

88 knees with bone bruise included

58 knees with ACL injury

30 knees with NO ACL injury

31 knees with

isolated ACL injury

27 knees with

combination ACL injury

15 knees with bone bruise and

NO ligamentous

injuries

15 knees with

ligamentous injury and NO ACL

injury

PCL = Posterior cruciate ligament. MCL = Medial collateral ligament. LCL = Lateral collateral ligament.

Fig. 1 Flow chart of

methodology study


123

the two cohorts when comparing the pattern of tibia, femur,

and patella bruising and the pattern of bruising in the

medial and lateral compartments. Table 2 summarizes

these results.

Combined ACL and other ligament injury cohort

The presence of MCL or LCL injury did not predispose a

patient with ACL injury to bruising in any compartment

(Table 3).

Comparing patients with medial, lateral, or bilateral

meniscus injury

There was no evidence of difference between the patterns

of bruising in patients with or without meniscus injury, and

the location of meniscus injury also did not predispose to

bruising in any compartment (Table 4).

Discussion

In our study, we found that the incidence of bone bruise in

our study population was 12.4 %. While bone bruises were

found to be dispersed completely throughout the knee and

the patella, they were found most commonly in the lateral

femur (69.3 %). This has been demonstrated in previous

studies that showed bone bruising to be more prevalent in

the lateral compartment than the medial compartment [5,

15–19].

Our study found a higher incidence of lateral compart-

ment bruise in patients with ACL injury. This is similar to

what has been previously noted in other studies of ACL

injury [2–4, 6, 8, 9]. Sanders et al. [9] described this to be

due to the pivot shift mechanism that is commonly impli-

cated in an ACL injury. This suggests that the suspicion for

an ACL injury needs to be heightened in the presence of a

lateral compartment bruise pattern.

Table 1 Characteristic of bone

bruising in ACL and non-ACL

injury cohort

Characteristics Total

(n = 88)

ACL

(n = 58)

Non-ACL

(n = 30)

Effect estimate P value

Mechanism of injury (%)

Non-contact (twisting) 58 (65.9) 44 (75.9) 14 (24.1) 1.00

Contact 17 (19.3) 8 (47.1) 9 (52.9) 0.62 [0.41, 0.94] 0.036

Tibia (%)

No 26 (29.6) 10 (38.5) 16 (61.5) 1.00

Yes 62 (70.5) 48 (77.4) 14 (22.6) 2.01 [1.36, 2.98] 0.001

Medial tibia (%)

No 54 (61.4) 35 (64.8) 19 (35.2) 1.00

Yes 34 (38.6) 23 (67.7) 11 (32.4) 1.04 [0.77, 1.42] 0.821

Lateral tibia (%)

No 46 (52.3) 21 (45.7) 25 (54.4) 1.00

Yes 42 (47.7) 37 (88.1) 5 (11.9) 1.93 [1.42, 2.63] 0.000

Femur (%)

No 17 (19.3) 8 (47.1) 9 (52.9) 1.00

Yes 71 (80.7) 50 (70.4) 21 (29.6) 1.50 [0.968, 2.31] 0.089

Medial femur (%)

No 65 (73.9) 42 (64.6) 23 (35.4) 1.00

Yes 23 (26.1) 16 (69.6) 7 (30.4) 1.08 [0.77, 1.51] 0.800

Lateral femur (%)

No 27 (30.7) 15 (55.6) 12 (44.4) 1.00

Yes 61 (69.3) 43 (70.5) 18 (29.5) 1.27 [0.90, 1.79] 0.224

Patella (%)

No 79 (89.8) 54 (63.4) 25 (31.7) 1.00

Yes 9 (10.2) 4 (44.4) 5 (55.6) 0.65 [0.35, 1.18] 0.264

Medial (%)

No 45 (51.1) 29 (64.4) 16 (35.6) 1.00

Yes 43 (48.9) 29 (67.4) 14 (32.6) 1.05 [0.77, 1.41] 0.824

Lateral (%)

No 18 (20.5) 9 (50.0) 9 (50.0) 1.00

Yes 70 (79.6) 49 (70.0) 21 (30.0) 1.40 [0.92, 2.12] 0.162


123

As compared to an isolated ACL injury, our study

demonstrated that the presence of other ligamentous inju-

ries in an ACL injury resulted in a more varied pattern of

bone bruising. Even though lateral compartment bruising

was still more common, we found a higher incidence of

medial compartment bruising in this cohort than the iso-

lated ACL injury group.

This can be attributed to the complex injury mechanism

and the greater force involved in a multi-ligamentous injury.

Both Mink and Deutsch [1] and Miller et al. [11] have

described a lateral compartment bruising pattern that is seen

with a MCL injury. They explained this to be due to a con-

trecoup event resulting in a force of impaction that is oppo-

site to the ligamentous injury. Similarly, in a study carried

out on posterolateral complex injuries of the knee, Ross et al.

[20] describe a characteristic anteromedial pattern of bone

bruise associated with such injuries. By combining the dif-

ferent patterns of bruising that occurs with each type of lig-

amentous injury, this may explain the wider variation of

pattern of bruising in those with combined ligament injuries.

This suggests that the presence of a medial compartment

bruise seen on the MRIs of ACL-injured patients should raise

our suspicion for other associated ligament injuries.

Although the locations of the bone bruises were more

varied, we did not find, from our study, that the combined

ligament group had higher numbers of bone bruises. We

also could not identify the pattern of bone bruising asso-

ciated with the type of collateral ligament injury with a

combined ACL injury.

Our study also shows that even without an ACL injury,

the most common location of a bone bruise is still in the

lateral compartment. This may be due to varied

Table 2 Characteristics of bone bruising in isolated and combined ACL injury cohort

Characteristics Total (n = 58) Isolated (n = 31) Combination (n = 27) Effect estimate P value

Number of bruise(s) (%)

1 bruise 35 (60.3) 19 (54.3) 16 (45.7) 1

[1 bruise 23 (39.7) 12 (52.2) 11 (47.8) 0.96 [0.58, 1.59] 1

Tibia (%)

No 10 (17.2) 3 (30.0) 7 (70.0) 1

Yes 48 (82.8) 28 (58.3) 20 (41.7) 1.94 [0.87, 4.35] 0.164

Medial tibia (%)

No 35 (60.3) 20 (57.1) 15 (42.9) 1

Yes 23 (39.7) 11 (47.8) 12 (52.2) 0.84 [0.50, 1.39] 0.593

Lateral tibia (%)

No 21 (36.2) 8 (38.1) 13 (61.9) 1

Yes 37 (63.8) 23 (62.2) 14 (37.8) 1.63 [0.94, 2.82] 0.103

Femur (%)

No 8 (13.8) 5 (62.5) 3 (37.5) 1

Yes 50 (86.2) 26 (52.0) 24 (48.0) 0.83 [0.43, 1.60] 0.712

Medial femur (%)

No 42 (72.4) 24 (57.1) 18 (42.9) 1

Yes 16 (27.6) 7 (43.8) 9 (56.3) 0.77 [0.42, 1.36] 0.393

Lateral femur (%)

No 15 (25.9) 9 (60.0) 6 (40.0) 1

Yes 43 (74.1) 22 (51.2) 21 (48.8) 0.85 [0.50, 1.45] 0.765

Patella (%)

No 54 (93.1) 30 (55.6) 24 (44.4) 1

Yes 4 (6.9) 1 (25.0) 3 (75.0) 0.45 [0.12, 1.71] 0.329

Medial (%)

No 29 (50.0) 16 (55.2) 13 (44.8) 1

Yes 29 (50.0) 15 (51.7) 14 (48.3) 0.94 [0.58, 1.52] 1

Lateral (%)

No 9 (15.5) 4 (44.4) 5 (55.6) 1

Yes 49 (84.5) 27 (55.1) 22 (44.9) 1.24 [0.60, 2.55] 0.72


123

mechanisms of injuries involved in these patients, which

resulted in a net impact on the lateral compartment.

We have found that having a meniscus injury did not

predispose to bruising in any compartment. This is unlike

what Kyoung et al. [13] found where a greater force results

in a greater bone contusion throughout the knee and is

associated with more meniscus injury.

These reflect that the location of a bone bruise should

lead to careful MRI inspection and physical examination

for other ligamentous and meniscus injuries.

Conclusion

There are differences in pattern of bone bruising in knee

injuries with or without ACL injuries. Future studies to be

carried out could correlate the pattern of bone bruising in

the knee with the understanding and rehabilitation of knee

injuries in our population.

Acknowledgments The authors would like to thank Ms Wong

Hung Chew, A/Prof Tai Bee Choo and Mr Benjamin Er for their

efforts in performing the statistical analysis for this paper.

Table 3 Combined ACL cohort—MCL versus LCL injuries

Group of patients with ACL, MCL and LCL injuries Total

ACL ? MCL ACL ? LCL ACL ? MCL ? LCL ACL

Medial/lateral

Only at medial

Count 1 1 0 6 8

% within medial/lateral 12.5 % 12.5 % 0 % 75.0 % 100.0 %

Only at lateral

Count 6 2 4 16 28

% within medial/lateral 21.4 % 7.1 % 14.3 % 57.1 % 100.0 %

Both medial and lateral

Count 4 1 4 12 21


Total

Count 11 4 8 34 57


P = 0.888

Table 4 Comparing location of bone bruise in patients with medial meniscus versus lateral meniscus versus bilateral meniscus injuries

Group of patients with ACL and medial, lateral or no meniscus injury Total

ACL ? medial meniscus ?

lateral meniscus

ACL ? isolated

medial meniscus

ACL ? isolated

lateral meniscus

ACL ? no

meniscus

Medial/lateral

Only at medial

Count 1 2 3 2 8


Only at lateral

Count 9 2 7 10 28


Both medial and lateral

Count 8 4 4 5 21


Total

Count 18 8 14 17 57


P = 0.562


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Conflict of interest All the authors do not have any financial and

personal relationships with other people or organizations that could

inappropriately influence (bias) their work.

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

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