Is Ultrasound Effective in Diagnosing Internal Derangements of the Knee?

doi:10.4236/ojo.2013.38059

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Open Journal of Orthopedics, 2013, 3, 321-324

Published Online December 2013 (http://www.scirp.org/journal/ojo)

http://dx.doi.org/10.4236/ojo.2013.38059

Open Access OJO

321

Is Ultrasound Effective in Diagnosing Internal

Derangements of the Knee?

S. K. Venkatesh Gupta, Sugnanam Sirish Aditya

Department of Orthopaedics, Mamata Medical College/General Hospital, Khammam, India.

Email: [email protected]

Received October 30th, 2013; revised November 29th, 2013; accepted December 15th, 2013

Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original

and by SCIRP as a guardian.

ABSTRACT

Internal derangement of knee significan tly affects daily activities of patients and management of su ch cases with accu-

rate diagnosis and early treatment is of utmost importance. This study determines the benefits of arthroscopy directly

and also compares the sensitivity and specificity of ultrasound, MRI and arthroscopic findings in diagnosing internal

derangements of the knee. This is a prospective study of 50 cases that in cludes patients having knee pain and instability

of joint for more th an 6 weeks, symptoms of locking of knee joint or effusion and h aving no bony injury as con firmed

by X ray. Results were analysed and sensitivity and specificity were calculated. The present study supports that the

clinical diagnosis is of primary necessity, while ultrasound and MRI are additional diagnostic tools in diagnosing IDK.

Arthroscopy combines more accurate diagnosing tool and therapeutic modality, which is a more convenient, economical

and convincing technique to both surgeon and patient alike. Although ultrasound is less accurate than MRI, it is cost

effective and available at most of the peripheral centres. So it is better to do ultrasound rather than MRI for diagnosing

IDK in peripheral centres and refer to specialty clinics or tertiary centres for further diagnosis and treatment.

Keywords: Knee; Menisci; MRI; Ultrasound; ACL; PCL; Arthroscopy

1. Introduction

The modern high speed motor vehicular trauma and the

sporting life style have become obsessions in all age

groups, causing damage to bone and soft tissue elements

especially of knee and causing internal derangement in-

juries. They account for a large number of referred cases

to specialty clinics and referral centers not only from the

peripherals and general practitioners but also from other

major centres. As it comes in the way of daily activities

and significantly affects financial earning of the person

and family, it is important to deal such cases with accu-

rate diagnosis and early treatment [1-4].

Combined lesions are more difficult to diagnose. The

clinical examination and special tests to determine insta-

bility and internal derangement still stand as preliminary

and gold standard s, more reliable and cost ef fective ways

of diagnosing such knee problems. Literature reviews

show that clinical examination is not always accurate to

diagnose IDK [5,6]. Ultrasound and MRI are non inva-

sive tools in investigating internal derangements of knee,

but false and misleading results are equally reported in

the literature. The difficulty in diagnosing lesions of the

knee is that different lesions in the knee joint can pro-

duce similar findings. Arthroscopy has been considered

as the gold standard for the diagnosis of IDK, but is in-

vasive, expensive and requires day surgery admission.

Hence, this study is inten ded to determine the benefits of

arthroscopy directly and also to compare the sensitivity

and specificity of ultrasound , MRI and arthroscopic find-

ings in diagnosing internal derangements of the knee.

2. Methodology

This is a prospective study of 50 cases admitted to

Mamata General and Super Speciality Hospital between

May 2011 and Dec 2012 having knee joint problem like

pain and instability of knee joint for more than 6 weeks,

those with recent symptoms of locking of knee joint or

effusion and those with chronic knee pain having no

Is Ultrasound Effect iv e in Diagnosing Internal Derangements of the Knee?

322

bony injury confirmed by x ray were included. All pa-

tients were clinically examined and were evaluated with

x-ray, ultrasound, MRI scan and diagnostic arthroscopy.

Patients treated for tuberculosis of knee and septic arthri-

tis, chronic osteoarthrosis or ankylosis of knee and those

who underwent arthroscopy previously were excluded

from the study. A standard 7.5 MHz ultrasound probe

and 0,3 Tesla MRI scanner was used in this study.

2.1. Positioning during Ultrasound Examination

Ultrasound of the knee was performed with a using a

linear array 7.5 MHz probe. The patient was initially

placed supine with the knee extended. The anterior horns

were examined from the medial and lateral aspects re-

spectively. The knee was then flexed to 90 degrees and

the probe rotated laterally to ex amine the Anterior Cruci-

ate Ligament (ACL). This was a dynamic examination

with the knee being serially extended during the proce-

dure.

The patient was then turned prone and the posterior

horns were examined from the medial and lateral aspects

respectively. The Posterior Cruciate Ligament (PCL) was

then examined with the probe rotated medially.

2.2. Positioning of Patient during Arthroscopy

Arthroscopy of knee is done by hanging limb by side of

table with knee in 90˚ degrees of flexion and for full

range of motion at knee joint during procedure (Figure

1).

2.3. Portal Placement

In our complete study we used anteromedial and antero

lateral portals for diagnostic arthroscopy (Figure 1).

3. Results

The study had 50 patients of which 40 (80%) were males

and 10(20%) wer e f e males.

In our study patients are in between 18 to 50 years of

age.

More no of patients are in between 21 to 30 years of

age (Chart 1).

Mean age of the study group was 28.3 years with age

range between 19 - 43 years.

In our study of 50 patients there are different modes of

injury in which Sports injury (64%) was the most com-

monest cause of modality of injury followed by road

traffic accident (16%) (Chart 2).

All patients were clinically examined and were evalu-

ated with X-ray, ultrasound, MRI scan and diagnostic

arthroscopy.

X rays were done to rule out associated fractures.

In our study we screened four structures like lateral

Figure 1. Patient positioning and portal placement in ar-

throscopy.

556

NOOFCASES

17

18‐20 21‐30 31‐4041‐50

AgedistributionofStudyPopulation

Chart 1. Age distribution of study population.

sp orts

injury

RTAdomesticothers

Sports

injur y

RTAonthersdomestic

Chart 2. Graph deipicting mode of injury in patients with

Internal derangement of knee in our study.

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Is Ultrasound Effect iv e in Diagnosing Internal Derangements of the Knee?

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323

meniscus, medial meniscus, anterior cruciate ligament

and posterior cruciate ligament.

We compared results of ultrasound and MRI with di-

agnostic arthroscopy.

The results of 50 cases evaluated for internal de-

rangement of knee with MRI, Ultrasound and arthro-

scopy are tabulated in Table 1.

MRI had 74.1% sensitivity and 100% specificity in

diagnosing ACL injuries while ultrasound scan had

74.2% sensitivity and 100% specificity in our study

group. MRI had 96.1% sensitivity and 95.8% specificity

in diagnosing Medial mensical injuries while ultrasound

scan had 85.2% sensitivity and 86.1% specificity. MRI

had 85.7% sensitivity an d 100% sp ecificity in diagno sing

lateral meniscal injuries while ultrasound scan had 71 .4 %

sensitivity and 100% specificity. Our results show that

ultrasound scan is equally good in picking up internal

derangement of knee as compared to MRI scan (Table

2).

4. Discussion

Ultrasound diagnosis of orthopedic conditions has gath-

ered pace in recent years. It has become popular because

it is safe, quick, inexpensive and fairly reliable [7,8].

Ultrasound diagnosis of Internal derangement of knee

has been tried in various studies with variable results.

Most of these studies compare ultrasound with arthro-

scopy or arthrography [9-12]. Some of the cadaver and

clinical studies on the d iagnostic efficiency of ultrasound

in Internal derangement of knee report high yield rates

with sensitivity for menisci ranging from 76% to 100%

and specificity from 50% to 97% [8,9,12]. In other stud-

ies the sensitivity for menisci was as low as 30% to 40%

[8,11]. The use of 7.5 MHz probe for the visualization of

the menisci is well established and our experience was

the same (2). In our study the sensitivity and specificity

for the lateral meniscus was 71.4% and 100% respec-

tively. The sensitivity and specificity for the medial me-

niscus was 85.2% and 86.1% respectively. The number

of lateral menisci was very low and therefore the results

should be interpreted with caution. However, the nu mber

of medial menisci was significant so both MRI and ul-

trasound showed a high sensitivity and specificity. We

also had good sensitivity and sp ecificity for the ACL but

did not have any PCL injuries in th e series. All structures,

i.e. medial meniscus, lateral meniscus, ACL and PCL

were visualized clearly in all knees. Although there were

no PCL injuries, the PCL was clearly visualized with

ultrasound, whereas its visualization can be a problem on

MRI. As it is shown from our results, the ultrasound

findings in IDK compare well with both arthroscop y and

MRI. In some cases, as for example the PCL, we think it

was even more helpful than MRI. Ultrasound is not

widely used as a diagnostic test for knee injuries, and

there has to be a learning curve for its routine use [11,13].

Competent and experienced radiologist can diagnose

IDK with help of ultrasound rather than expensive MRI.

Ultrasound is available in all peripheral centres, where as

MRI is only available in tertiary centres. So it is better to

Table 1. Summary of results.

Lesion Arthroscopy MRI ultrasound

Torn Normal Abnormal Torn Normal Abnormal Torn Normal

LM 7 43 6 0 44 0 5 45

MM 27 23 20 5 25 7 23 20

Complete Partial Normal

ACL 20 7 23 13 7 30 3 17 30

PCL 0 0 50 0 0 50 0 0 50

LM - Lateral meni s cus; MM - Medial meniscus; ACL- Anterior cruciate ligament PCL - Posterior cruciate ligament.

Table 2. Sensitivity & specificity of MRI and ultrasound.

LESION MRI ULTRASOUND

SENSITIVITY SPECIFICITY SENSITIVITY SPECIFICITY

Lateral meniscus 85.7% 100 71.4% 100%

Medial meniscus 96.1% 95.8% 85.2% 86.1%

Anterior cruciate l ig a ment 74.1% 100 74.2% 100%

Posterior cruciate ligament N/A N/A N/A N/A

Is Ultrasound Effect iv e in Diagnosing Internal Derangements of the Knee?

324

do ultrasound rather than MRI for diagnosing IDK in

peripheral centres and refer to specialty clinics or tertiary

centres for further diagnosis and treatment [10-12].

5. Conclusion

The present study supports that the clinical diagnosis is

of primary necessity. Ultrasound and MRI are additional

diagnostic tools for diagnosing internal derangement of

knee. Arthroscopy combines more accurate diagnosing

tool and therapeutic modality, which is a more conven-

ient, economical and convinci ng t echnique to both surgeon

and patient alike. However, high expectations from pa-

tients knowing the diagnosis befor e undergoing interven-

tional procedures like arthroscopy make ultrasound and

MRI the highly demanding and needed technique in di-

agnosing IDK. MRI is considered as a more sensitive te-

chnique compared to ultrasound. However, MRI has false

and misleading results as high as 20% - 30% in knee pa-

thologies as being reported in standard literature which is

also confirmed in our study. Although ultrasound is less

accurate than MRI, it is cost effective and available at

most of the peripheral centres. We recommend that ul-

trasound be used at present as a screening test before a

MRI is performed or where clinical examination is diffi-

cult or unclear.

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