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 Table of Contents  
Year : 2012  |  Volume : 24  |  Issue : 3  |  Page : 93-96

The importance of using ultrasonography in knee osteoarthritis

Department of Internal Medicine, Cairo University, Cairo, Egypt

Date of Submission05-Sep-2012
Date of Acceptance05-Sep-2012
Date of Web Publication16-Jul-2014

Correspondence Address:
Mohamed A El-Ghobary
28 Samir Abdul Raoof St, 8th District, Nasr City,, 123 Cairo
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Source of Support: None, Conflict of Interest: None

DOI: 10.7123/01.EJIM.0000422604.53524.16

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Radiographic features of osteoarthritis (OA) do not correlate with its symptoms at the individual patient level; thus, conventional radiography has limitations. Ultrasonography plays an important role in the diagnosis of musculoskeletal disorders. It reveals soft-tissue abnormalities such as pes anserine bursitis, Baker’s cyst, effusion, synovial hypertrophy, meniscal tear, and collateral ligament injury.

Aim of work

The aim of this study was to detect changes in the knee that cannot be visualized using conventional radiography and to better understand and manage unexplained pain in OA.


There was a discrepancy between the results obtained by clinical examination and those by ultrasonography. Knee effusion was found in 21 knees (70%); synovial hypertrophy was found in three knees (10%), of them two showed Baker’s cyst and marked effusion; Baker’s cyst was found in eight knees (27%); and pes anserine bursitis was found in one knee. Results that could not be found by clinical examination were: cartilage degeneration in 27 knees (90%) and meniscal degeneration in 26 (86%). Meniscal degeneration and synovial hypertrophy were correlated significantly with advanced cartilage degeneration (P<0.001).


Ultrasonography can be used for diagnosing soft-tissue lesions, for grading the severity of OA, and for guiding and monitoring therapy.

Keywords: cartilage, guided injection, joints, osteoarthritis, osteophytes, synovitis, ultrasonography

How to cite this article:
Ragab G, El-Ghobary MA, El Gohary RM. The importance of using ultrasonography in knee osteoarthritis. Egypt J Intern Med 2012;24:93-6

How to cite this URL:
Ragab G, El-Ghobary MA, El Gohary RM. The importance of using ultrasonography in knee osteoarthritis. Egypt J Intern Med [serial online] 2012 [cited 2020 Dec 4];24:93-6. Available from: http://www.esim.eg.net/text.asp?2012/24/3/93/136005

  Introduction Top

Osteoarthritis (OA) refers to a group of joint disorders that are caused by a variety of factors but with common clinical and pathological features. The disease is difficult to define succinctly because of its complex pathological nature and heterogenous clinical presentation. With regard to epidemiological studies, OA is usually defined according to changes seen on radiography 1.

These changes can be graded according to existing criteria, which generally focus on the presence of joint space narrowing, osteophytes, subchondral bone sclerosis, subchondral bone cysts, and bone-end deformities. However, the radiographic features of OA do not correlate with its symptoms at the individual patient level; thus, conventional radiography (CR) has limitations in the clinical setting. Ultrasonography, in contrast, reveals soft-tissue abnormalities such as pes anserine bursitis, Baker’s cyst, effusion, synovial hypertrophy, meniscal tear, and collateral ligament injury 2. For these reasons, novel imaging techniques are being tested and used as an adjuvant to CR in the investigation and management of OA in the clinical setting.

  Materials and methods Top

This study was conducted on 15 patients (30 knees) who presented to the outpatient Rheumatology clinic with knee pain and were diagnosed according to ACR criteria for OA.

Full clinical examination

Clinical tests included determination of ESR, analysis of CBC and uric acid, and detection of viral hepatitis markers.

Radiographic assessment: All patients were assessed on the basis of posteroanterior, lateral, and sunrise views. Bone erosions, osteophytes, and joint space narrowing were recorded.

Exclusion criteria included: previous history of trauma, gout, and joint injection (6 months earlier).


A Philips HDI 5000 linear transducer (Philips ATL Company, Universal Diagnostic Solutions, South California, USA) with color Doppler and power Doppler was used at 7.5–12.5 MHz for performing the ultrasonography. Standardized US-defined pathological findings described by OMERACT were also followed 3.

Statistical analysis

The statistical package for social sciences (version 15.0; SPSS Inc., Chicago, Illinois, USA) was used for data analysis. The results are expressed as mean±SD. The t-test was used to compare group results. The χ2 and Fisher’s exact test were used to compare categorical variables. Correlations below 0.05 were considered significant.

Knee examination was performed by acquisition of images of the knee joint according to the recommendations of the European League Against Rheumatism 4. It was recommended that the knee be imaged initially with patients supine in the neutral or slightly flexed (30°) position for lateral and anterior images and then in the prone position for posterior images. Slight flexion with contraction of the quadriceps aids visualization of the suprapatellar pouch, and maximal flexion aids visualization of the trochlear cartilage. Standard scans should include imaging in the transverse and longitudinal planes of the suprapatellar region, infrapatellar region, and posterior knee (medial and lateral). In addition, the knee should be imaged longitudinally over the medial and lateral aspects of the joint. Cartilage pathology can be appreciated in the trochlea of the distal femur, with the knee in full flexion.

Grades of cartilage affection

Cartilage was assessed and graded on the basis of sharpness, clarity, and thickness.

0=normal (no signs of degeneration).

Grade 1=loss of sharpness of the cartilage margins.

Grade 2=loss of homogeneity of the articular cartilage.

Grade 3=thinning of the cartilaginous layer +1 and 2.

Grades of knee effusion

0=effusion less than 4 mm or no effusion.

1=mild (more than 4 mm in one recess).

2=moderate (effusion in two recesses).

3=marked (effusion in three recesses).

  Results Top

Knee effusion: Using ultrasonography, knee effusion was detected in 21 knees (70%) of a total of 30, of which mild effusion was detected in 11, moderate in eight, and marked in two.

Synovial hypertrophy was detected in three knees (10%), two of which showed Baker’s cyst and marked effusion.

Baker’s cyst was found in eight knees (27%) and pes anserine bursitis was found in one knee. Clinical examination could not detect very important structural knee changes: cartilage degeneration in 27 knees (90%), meniscal degeneration in 26 knees (86%), and meniscal extrusion (a bulge more than 3 mm, which pushes on the collateral ligament) in seven knees (23%) [Table 1].
Table 1: Ultrasonographic abnormalities in 30 knees

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Meniscal degeneration and extrusion related significantly with advanced cartilage degeneration [Table 2].
Table 2: Relation between cartilage degeneration and meniscal lesion in knee osteoarthritis

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Osteophytes were detected in all 30 knees (100%), whereas cartilage narrowing was detected in 13 knees (43%), with no difference between those having cartilage narrowing and those who did not.

Although knee effusion did not correlate with synovial hypertrophy in general, advanced knee effusion did significantly (P<0.05).

Synovial hypertrophy also correlated with advanced cartilage degeneration (P<0.001), meniscal degeneration (P<0.001), and meniscal extrusion (P<0.05) [Table 4]. However, it did not correlate with the weight of the patients nor with the duration of the disease [Table 3].
Table 3: Demographic characteristics of patients with knee osteoarthritis with and without synovial hypertrophy

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Table 4: Relation between synovial hypertrophy and ultrasonographic findings in knee osteoarthritis

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  Discussion Top

The role of musculoskeletal ultrasonography in various rheumatic disorders is expanding because of the availability of higher-resolution ultrasonographic machines that can be used for visualizing them. Radiographic features of OA do not correlate with its symptoms at the individual patient level; thus, the value of CR has limitations in the clinical setting. Ultrasound detects soft tissue abnormalities and can be used to describe the typical features of synovial hypertrophy, effusion, osteophytes, and cartilage thinning at the knee joint. In addition, meniscal extrusion and tears may be visualized in association with displacement of the collateral ligaments.

This study was conducted on 15 patients (30 knees), of whom 11 were women and four were men, who presented at the outpatient Rheumatology clinic with knee pain and were diagnosed according to ACR (1986) criteria for OA 5. Ultrasonography was used to detect changes in the knees of patients having OA.

OA is more common in women as compared with men, and hence our study included 11 women and four men. The number of women was almost three-folds that of men, which is in agreement with the results of Dieppe et al. (2008). There was no significant difference between the presence and absence of synovial hypertrophy with respect to the weight of the patients, although it is known that the severity and prevalence of knee OA are higher in obese individuals compared with those of normal weight. In our study, patients having synovial hypertrophy had the disease for a longer duration (6 vs. 4 years) compared with those not suffering from it, although this was not statistically significant (P>0.05) [Table 3]. It is well known that knee OA is a progressive disease, which means that older populations suffer from a more severe form of the disease. However, in our study, there was no correlation between the age of the patients and the presence of synovial hypertrophy, which may be because of the small number of patients studied 6.

Imaging of the popliteal fossa helps in identification of Baker’s cysts associated with OA. These appear as hypoechoic or anechoic masses arising between the semimembranosus and the medial head of the gastrocnemius tendons. They may have a heterogenous echoic appearance as they can be filled with debris from the communication with the knee joint. Leakage of fluid from the cyst is characterized by the presence of fluid within the surrounding tissue and a beaked appearance of the cyst distally. Complete rupture and emptying of the cyst may be indicated only on the detection of residual fluid between the heads of the semimembranosus tendon and the medial gastrocnemius 7.

Pathological changes in the cartilage, such as thinning, heterogeneity, and loss of clarity (described previously), can be observed. These changes, in particular thinning, are generally more pronounced in OA than in inflammatory arthritis. Ultrasonographically detected changes in the hyaline cartilage of the knee are unclear. The peripheral, superficial aspects of menisci can also be visualized using ultrasonography, allowing some meniscal pathological conditions such as cysts, extrusion, or horizontal tears to be detected. Meniscal extrusion has been shown to be significantly associated with symptomatic knee OA. It is a significant component of the joint space narrowing as observed radiographically and has been shown to be associated with ultrasonographically detectable displacement of the medial collateral ligament and some pain parameters 8.

Our results agree with those of Mendieta et al. (2006), who compared 81 patients having symptomatic knee OA with 20 patients having asymptomatic knee OA. They found that the frequent ultrasonographic findings in the knees of patients with symptomatic OA were suprapatellar effusions (79%), meniscal lesions (45%), Baker’s cysts (37%), infrapatellar bursitis (8.6%), and anserine bursitis (0.6%) 9.

In our study, there was a significant correlation between synovial hypertrophy and severity of effusion, between synovial hypertrophy and cartilage degeneration, and between meniscal degeneration and meniscal extrusion, implying that synovial hypertrophy is found in the severe forms of the disease [Table 4].

Moreover, our results agree with those obtained in the study by Naredo et al. 10 on patients with primary knee OA. They found that the more frequent ultrasonographic findings in symptomatic knees were effusion (47%), medial meniscus extrusion (61%), and Baker’s cysts (22%). These patients were associated with a significantly higher pain score than those who had no findings at ultrasonography 10. Ultrasonography can be used not only for diagnosis but also for treating Baker’s cysts and monitoring response to therapy. In this series of OA patients, injection of corticosteroids into the knee joint accounted for a reduction in the dimensions of Baker’s cyst as well as in cyst wall thickness 11.

Pourbagher et al. 12 showed that sonographically guided intra-articular injection of sodium hyaluronate in patients with hip OA is easy to perform and is a safe, economical, and well-tolerated method of treatment. In contrast to fluoroscopic or computed tomographic guidance, the sonographic technique exposes neither the patient nor the physician to radiation 12. In our opinion this technique can also be applied to the knee.

Kristoffersen et al. 13 demonstrated that primary OA is associated with synovial thickening in 61 of 71 patients, and hyperemia was detected in 51 of them. This confirms that there is a variable degree of inflammation among the patients, and those having inflammation respond to local injections of corticosteroids 13.

  Conclusion Top

Ultrasonography can be used for diagnosing soft-tissue lesions, grading the severity of OA, and for guiding and monitoring therapy.[13]

  References Top

1.Zhang Y, Jordan JM. Epidemiology of osteoarthritis. Rheum Dis Clin North Am. 2008;34:515–529  Back to cited text no. 1
2.Guermazi A, Eckstein F, Hellio Le Graverand-Gastineau MP, Burstein D, Keen H, et al. Osteoarthritis: current role of imaging. Med Clin North Am. 2009;93:101–126  Back to cited text no. 2
3.Wakefield RJ, Balint PV, Szkudlarek M, Filippucci E, Backhaus M, D'Agostino MA, et al. OMERACT musculoskeletal ultrasound including defenitions for ultrasonographic pathology. J Rheumatol. 2005;32:2485–2486  Back to cited text no. 3
4.Backhaus M, Burmester GR, Gerber T, Grassi W, Machold KP, Swen WA, et al. Guidelines for musculoskeletal ultrasound rheumatology. Ann Rheum Dis. 2001;60:641–649  Back to cited text no. 4
5.Altman R, ASCh E, Bloch D, Borestein D, Barndt K, et al. The American College of Rheumatology criteria for the classification and reporting of osteoarthritis of the knee. Arthritis Rheum. 1986;29:1039–1049  Back to cited text no. 5
6.Paul D. Osteoarthritis: clinical features. Primer on rheumatic diseases. 2008;Vol. 11.13th ed.:224–225  Back to cited text no. 6
7.Bianchi S, Martinoli C Ultrasound of the musculoskeletal system. 20071st ed. Berlin Springer:409–507  Back to cited text no. 7
8.Jeannie C, Keneth K. Ultrasonography in osteoarthritis: recent advances and prospects for the future. Curr Opin Rheumatol. 2008;20:560–564  Back to cited text no. 8
9.DeMiguel ME, Bonilla HG, Martin ME, et al. Clinical and ultrasonographic findings related to knee pain in osteoarthritis. Osteoarthritis Cartilage. 2006;14:540–544  Back to cited text no. 9
10.Naredo E, Cabero F, Palop MJ, Collado P, Cruz A, Crespo M, et al. Ultrasonographic findings in knee osteoarthritis: a comparative study with clinical and radiographic assessment. Osteoarthritis Cartilage. 2005;13:568–544  Back to cited text no. 10
11.Acebes JC, Sánchez-Pernaute O, Díaz-Oca A, Herrero-Beaumont G. Ultrasonographic assessment of Baker’s cysts after intra-articular corticosteroid injection in knee osteoarthritis. J Clin Ultrasound. 2006;34:113–117  Back to cited text no. 11
12.Pourbagher MA, Ozalay M, Pourbagher A. Accuracy and outcome of sonographically guided intra-articular sodium hyaluronate injections in patients with osteoarthritis of the hip. J Ultrasound Med. 2005;24:1391–1395  Back to cited text no. 12
13.Kristoffersen H, Torp-Pedersen S, Terslev L, Ovistgaard E, Holm CC, Ellegaard K, Bliddal H, et al. Indications of inflammation visualized by ultrasound in osteoarthritis of the knee. Acta Radiol. 2006;47:281–286  Back to cited text no. 13


  [Table 1], [Table 2], [Table 3], [Table 4]


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