Objective: To investigate by high frequency grey-scale ultrasonography (US) and power Doppler sonography (PDS) the modality and frequency of involvement of the Achilles tendon and plantar fascia in chondrocalcinosis (CC), and to correlate these findings with clinical complaints and radiographic evidence.
Methods: The heels of 57 consecutive patients with CC were evaluated by US, PDS, and radiography. One control group of 50 consecutive patients with osteoarthritis (OA) without signs of CC was studied in the same way. A second control group of 50 healthy subjects underwent only US/PDS examination. All subjects also underwent clinical assessment.
Results: US revealed Achilles tendon calcifications in 57.9% of those with CC, but none in the control groups. Plantar fascia calcifications were observed in 15.8% of CC and in 2% of OA cases, but not in healthy controls. US showed no significant difference in postero-inferior and inferior calcaneal enthesophytosis between subjects with CC (59.6% and 61.4%, respectively) and those with OA (46% and 44%, respectively). Such alterations were also present, in lower percentages, in the healthy controls. Posterior and inferior calcaneal erosions were absent in all groups. Achilles enthesopathy was found in 22.8% of patients with CC (14.9% of heels, with vascular signals in 11.4% of heels on PDS). Deep retrocalcaneal bursitis was found in 10.5% of patients with CC (7% of heels, with vascular signals in 5.2% of heels on PDS). Plantar fasciitis was found in 40.3% of patients with CC (36% of heels, with vascular signals in 2.6% of heels on PDS) and in 14% of OA patients, but not in healthy controls. No significant correlation was found between talalgia or sex of patients and presence of calcifications. A significant correlation was observed between talalgia and Achilles enthesopathy (r = 0.78, p < 0.0001), deep retrocalcaneal bursitis (r = 0.7, p < 0.0001), and plantar fasciitis (r = 0.31, p < 0.001). A significant correlation between talalgia and vascular signals on PDS was observed in Achilles enthesopathy (r = 0.91, p < 0.0001) and deep retrocalcaneal bursitis (r = 0.65, p < 0.0001). The presence of vascular signals on PDS was significantly associated with the presence of tendinous and bursal grey-scale US alterations. Achilles tendon calcifications were 39% sensitive, 100% specific, and 77% accurate for the presence of CC, whereas plantar fascia calcifications were 15% sensitive, 98% specific, and 54% accurate. Excellent agreement was found between US and radiography in detecting Achilles tendon calcifications (k = 0.86), plantar fascia calcifications (k = 0.77), postero-inferior enthesophytosis (k = 0.90), and inferior enthesophytosis (k = 0.83).
Conclusion: Calcaneal tendon calcifications are frequent and asymptomatic findings in patients with CC, and they have a high specificity for this disease. US shows high agreement with radiography in depicting calcifications and enthesophytosis. Inflammatory changes of the calcaneal soft tissues are frequently observed by US and PDS in patients with chondrocalcinosis.