Heel pain is a common complaint among adults, often disrupting daily activities and reducing quality of life^[1]. While it can stem from various conditions such as heel spurs, Achilles tendinitis, bursitis, or systemic illnesses like gout and rheumatoid arthritis, plantar fasciitis (PF) stands out as the most frequent cause. PF arises from repetitive strain and microtears in the plantar fascia, leading to inflammation and localized heel pain, especially with weight-bearing. It's more frequently seen in women, possibly due to differences in foot structure, footwear habits, and hormonal influences.

People with prolonged standing, athletes engaged in high-impact sports, and those who are overweight or obese are at greater risk. The additional load on the feet in these groups often results in increased strain on the plantar fascia, accelerating tissue damage.

Clinically, PF is recognized as a degenerative condition. Diagnosis typically relies on a patient’s history and physical examination, with hallmark symptoms including pain on the underside of the heel, most severe upon first steps after rest. Tenderness is usually found at the inferomedial aspect of the calcaneal tuberosity.

Plantar fasciitis is commonly diagnosed using clinical history, physical examination, and plain X-rays. However, several other conditions such as enthesopathies, fascia ruptures, infections, and inflammatory disorders can mimic its symptoms, making accurate diagnosis more complex^[2]. To confirm plantar fasciitis, various imaging techniques have been used, including radiography, scintigraphy, MRI, and more recently, high-resolution ultrasound.

Ultrasound has gained popularity due to its non-invasive nature, affordability, availability, and ability to provide high-resolution images of superficial tissues. It also allows real-time dynamic assessment, making it a practical tool in both diagnosis and treatment. Compared to palpation-guided procedures, ultrasound-guided injections have been shown to offer better pain relief outcomes. It’s also useful for guiding shockwave therapy and tracking patient progress over time.

Research, including findings by Osborne and colleagues, identifies key sonographic indicators of plantar fasciitis such as thickened plantar fascia, abnormal fat pad changes, and cortical bone irregularities^[3]. Multiple studies have confirmed the reliability of ultrasound in detecting these abnormalities. Notably, ultrasound and MRI show comparable accuracy when measuring plantar fascia thickness.

Given these advantages, this study aims to assess how effective ultrasonography is as a diagnostic tool for plantar fasciitis. The goal is to evaluate its accuracy, reliability, and practical use in identifying hallmark features like thickening and hypoechogenicity of the fascia.

This was a hospital-based, time-bound, and cross-sectional observational study done in the Department of Radiodiagnosis of M.G.M. Medical College and M. Y. Hospital, Indore, Madhya Pradesh, India after getting approval by ISRB (Institutional Scientific Review Board). The duration of this study was one year from ethics committee clearance. A total of 70 patients referred to our department for high resolution ultrasonography of plantar fascia.

Inclusion criteria

Clinically suspected cases of plantar fasciitis with

1. Heel pad tenderness on clinical examination.
2. Chronic heel pain (> 3 months)

Exclusion criteria

1. Trauma
2. Inflammatory arthritis
3. Neuromuscular disease
4. Pediatric patient (<20 Years)

Study Protocol

 Patients suspected for plantar fasciitis were referred from the department of orthopedics to the Department of Radiodiagnosis for high resolution ultrasonography of the heel. Informed consent was taken after complete description of study and handing over patient information sheet. Body weight and body height were measured in all the patients, and the body mass index (BMI) was calculated. All patients were examined in supine position using a low frequency transducer (3-5 MHz). Patients were asked to lie prone with feet hanging from the edge of the table, and their ankles were placed in dorsiflexion. The probe of the ultrasound was placed on a line connecting the second toe and the mid heel. The focus was adjusted for superficial musculoskeletal examination and gain was adjusted for good penetration of the thick skin of the heel. Normal plantar fascia appears as a “hyperechoic band with linear fibres” on the background of a hypoechoic matrix. The thickness of the plantar fascia was measured within 1 cm of the calcaneal attachment. Thickness of ≥ 4mm was considered as cut off for plantar fasciitis. Quantitative (plantar fascial thickness) as well as qualitative parameters (echogenicity, perifascial fluid collection, perifascial edema, fine calcifications within fascia and presence of calcaneal spur) for 70 consecutive patients with clinically suspected plantar fasciitis was obtained. After performing ultrasound lateral X ray of the foot was obtained for all patients to confirm the presence/absence of sub calcaneal bony spur and fine calcifications. Further depiction of data was done in the form of tables and charts. SPSS was used to analyze the data. Mean and standard deviation of the quantitative variables were calculated.

Table No 1 Demographic data of the studied patients

Table 1 represents the age and BMI values are expressed as mean ± standard deviation (SD). The mean age of the studied patients was 44.03 years, indicating a middle-aged population. The average BMI was 25.86 kg/m², falling within the overweight category, which may be relevant to the risk of developing plantar fasciitis.

Table 2: Distribution of Patients according to major ultrasonography Findings

Table 2 represents the ultrasonographic characteristics of the study population. In terms of plantar fascia thickness majority of patients (80%) had more than or equal to 4mm plantar fascia thickness and (20%) patients had less than 4mm plantar fascia thickness. Plantar fascia showed hypoechogenicity in (67.14%) patients, while 20% showed hyperechoic and 12.86% had isoechoic characteristics.

Table 3: Comparison of USG Findings (Plantar fascia thickness) Across BMI Categories

Table 3 illustrates the distribution of plantar fascia (PF) thickness on ultrasound in relation to BMI categories: underweight (<18.5 kg/m²), normal (18.5–24.99 kg/m²), overweight (25–29.99 kg/m²), and obese (>30 kg/m²). In the underweight group, 3 patients had normal PF thickness (<4 mm) with a mean of 2.9 mm, while 2 patients showed mild thickening (4.5 mm); no cases of moderate or severe thickening were observed. Among patients with normal BMI, 7 had normal PF thickness (mean 3.3 mm), 6 had mild thickening (mean 4.9 mm), and 3 showed moderate thickening (mean 6.2 mm); none had severe thickening. In the overweight group, 3 patients had normal thickness (mean 3.3 mm), 29 had mild thickening (mean 5.1 mm), 8 had moderate thickening (mean 6.4 mm), and 3 exhibited severe thickening (mean 7.7 mm). Among obese patients, 1 had normal thickness (3.5 mm), 3 had mild thickening (mean 5.1 mm), 1 had moderate thickening (6.9 mm), and 1 had severe thickening (7.9 mm). The variation in plantar fascia thickness across BMI categories was statistically significant, with a p-value of 0.03.

 Table 4: Diagnostic Accuracy of Ultrasonography (USG) to predict plantar fasciitis.

Table 4 shows diagnostic accuracy of ultrasonography (USG) was found to be high, with a sensitivity of 85.71% and a specificity of 71.43%, indicating that USG is effective in correctly identifying positive cases as well as a moderate ability to identify negative cases. The positive predictive value (PPV) was 96.42%, suggesting that most patients identified as positive truly had the condition. However, the negative predictive value (NPV) was 35.71%. The overall diagnostic accuracy of USG was 84.29%, reflecting its usefulness as a screening and diagnostic tool in clinical practice.

Table 5: Diagnostic Accuracy of X-ray to predict plantar fasciitis by comparison with ultrasound.

Table 5 shows diagnostic accuracy of X-ray compared to ultrasonography was found to be highly unreliable. X-ray demonstrated a sensitivity of 19.64%and a specificity of 92.85%, reflecting a high incapability to correctly identify true positive. The positive predictive value (PPV) was 91.66%. Notably, the negative predictive value (NPV) was 22.41%.The overall diagnostic accuracy was 34.28%, highlighting X-ray as a inferior and dependable diagnostic tool when compared with USG.

Figure 1 A 40year old overweight female came with complaints of left heel pain and tenderness since 3 months (BMI -26.9)

Figure a                                                              Figure b

Ultrasonography of left heel showed moderately thickened (mean PF thickness-5.9 mm) and hypoechoic plantar fascia. Xray of left ankle was normal.

Figure 2 A 30year old male presented with the complaints of chronic right heel pain and swelling) Since 6 months (BMI 30.5)

Figure a                                                               Figure b

Figure c

Ultrasonography showed hypoechoic and moderately thickened plantar fascia (mean PF thickness- 6.8mm) with surrounding perifascial edema.

Lateral radiograph of right ankle showed increased heel pad thickness.

Figure 3 A 61year old obese male patient came with the complaints of left heel pain and swelling since 6 months (BMI-32.4)

Figure a                                                              Figure b

Figure c                                                         Figure d

On ultrasound plantar fascia appeared thickened (mean PF thickness- 5.7mm) and hypoechoic with perifascial fluid collection. Xray of left ankle appeared normal.

This study aimed to assess the diagnostic value of ultrasonography in identifying plantar fasciitis, focusing on plantar fascia thickness, echogenicity, and its correlation with BMI. The findings support the growing consensus that ultrasound is a reliable, non-invasive tool for diagnosing plantar fasciitis and evaluating the severity of plantar fascia pathology.

The most notable ultrasonographic finding was a plantar fascia thickness of ≥4 mm, observed in 80% of patients. This threshold is widely accepted in literature as indicative of plantar fasciitis. Additionally, the predominance of hypoechoic changes (67.14%) aligns with the degenerative and inflammatory nature of the condition, which often results in reduced echogenicity of the fascia due to edema and microtears. This is comparable to the findings by Cardinal et al. (1996)^[4], who reported hypoechogenicity in approximately 70% of cases hyperechoic and isoechoic appearances were less frequently observed in 14 (20%) and 9 (12.86%) patients, respectively.

BMI was found to significantly influence plantar fascia thickness (p = 0.03). Overweight and obese patients demonstrated higher rates of moderate and severe thickening, suggesting that increased mechanical load on the heel contributes to plantar fascia degeneration. These results are consistent with with Rastegar et al. (2016)^[5] and McMillan et al. (2009)^[6] that identified obesity as a key risk factor for plantar fasciitis due to altered foot biomechanics and greater stress on soft tissues.

Ultrasound demonstrated a high sensitivity (85.71%) and specificity (71.43%) for diagnosing plantar fasciitis, with an overall diagnostic accuracy of 84.29%. Its high positive predictive value (96.42%) suggests that a thickened plantar fascia on ultrasound is strongly associated with clinical plantar fasciitis. However, the lower negative predictive value (35.71%) indicates that a normal ultrasound does not entirely exclude the diagnosis, particularly in early or less severe cases. These findings are consistent with those of Kane et al. (2001)^[7], who reported a sensitivity of 90% and specificity of 70% for USG based on PF thickness ≥4 mm. Similarly, Mohanty et al. (2017)^[8] observed an accuracy of 86%, supporting the reliability of sonographic parameters in clinical decision-making.

When compared to X-ray, ultrasound vastly outperformed in terms of sensitivity (85.71% vs. 19.64%). Although X-rays showed higher specificity (92.85%), their overall diagnostic accuracy was much lower (34.28%). This reflects the X-ray’s limitations in detecting soft tissue changes and emphasizes its role primarily in identifying calcaneal spurs rather than plantar fascia pathology itself. These results is consistent with Sadeghi et al. (2019)^[9] found that while radiographic findings were present in 15–20% of symptomatic patients, many individuals with plantar fasciitis did not show radiographic changes, especially in early stages. Similarly, a study by Kamel et al. (2021)^[10] noted that USG was superior to X-ray in detecting not just PF thickening, but also associated soft tissue changes like perifascial edema and hypoechogenicity features not visible on radiographs.

In summary, this study confirms the diagnostic advantage of ultrasonography over X-ray in evaluating plantar fasciitis. Its ability to visualize soft tissue changes, guide interventions, and correlate findings with clinical symptoms makes it a valuable tool in both diagnosis and management. Furthermore, the strong association between BMI and plantar fascia thickness underscores the importance of weight management in both prevention and treatment strategies for plantar fasciitis.

Ultrasonography proves to be an effective, non-invasive, and accessible tool for diagnosing plantar fasciitis, especially through assessment of plantar fascia thickness and echogenicity. Its high sensitivity and diagnostic accuracy make it superior to X-ray, which is limited in evaluating soft tissue changes. The significant correlation between higher BMI and increased plantar fascia thickness highlights the role of body weight in disease progression. Incorporating ultrasound into routine clinical evaluation can enhance early detection and treatment planning. These findings also emphasize the need for preventive strategies such as weight management to reduce the burden of plantar fasciitis.

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