PMC9510676_01
Gross appearance. Gross appearance of the calcaneal region at the initial evaluation. Hair around the region has been clipped for assessment. (A) Lateral view of the left calcaneal region (arrow). (B) Caudocranial view of the left calcaneal region. Remarkable swelling is confirmed around the calcaneal tuberosity (arrow).
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F1
A cyst-like mass and swelling around the calcaneal tendon were revealed on physical examination (Figure 1).
Ultrasonography. (A) Longitudinal view of left calcaneal tendon and calcaneus at the initial evaluation. There is a heterogeneous hypoechoic lesion (arrow), indicating moderate fluid accumulation and/or inflammation within the bursa. (B) Longitudinal view of left calcaneal tendon and calcaneus at 4 weeks postoperatively. Absence of the lesion can be confirmed (arrow). Calcaneus tuberosity was indicated as CT on the figures.
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F2
On ultrasonography (Figure 2A), hypoechoic fluid-filled lesions were located at the normal anatomic position of the gastrocnemius calcaneal bursa, but evidence of calcaneal tendonitis could not be identified. Radiographic and ultrasonographic evaluation of calcaneal region revealed reduced opacity between distal tibia and calcaneal tendon and absence of heterogenous hypoechoic lesions cranial to calcaneal tuberosity (Figure 2B).
Magnetic resonance imaging. (A) T2-weighted sagittal image of the right tarsal joint. (B) Postcontrast fat saturated proton density-weighted sagittal image of the right tarsal joint. (C) T2-weighted sagittal image of the left tarsal joint. (D) Postcontrast fat saturated proton density-weighted sagittal image of the left tarsal joint. (E) T2-weighted coronal image of the right tarsal joint. (F) Postcontrast fat saturated proton density-weighted coronal image of the right tarsal joint. (G) T2-weighted coronal image of the left tarsal joint. (H) Postcontrast fat saturated proton density-weighted coronal image of the left tarsal joint. The gastrocnemius calcaneal bursa (asterisk) and intertendinous bursa (arrowhead) were identified as hyperintense regions. Components of the calcaneal tendon such as common tendon, gastrocnemius tendon, and superficial digital flexor tendon were intact (identified as hypointense string).
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For further investigation, magnetic resonance imaging (MRI) was performed (Figures 3A-H).
Intraoperative images. (A) Prominently enlarged gastrocnemius calcaneal bursa (white arrow) was identified intraoperatively. (B) The serous fluid was released from the incised opening (white arrowhead) on the bursa using a No.11 blade. The opening of the bursa was extended by Castroviejo scissors. (C) The dissection using tenotomy scissors was performed until the normal Achilles tendon was isolated from the bursa. The redundant bursa was removed. (D) The medial retinaculum was sutured to the edge of the tendon using monofilament, absorbable suture material. Note the appearance of normal Achilles tendon after removal of gastrocnemius calcaneal bursa with shrinkage of the swollen lesion (black arrow). Cd, Caudal; Cr, Cranial.
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F4
The calcaneal tendon was surrounded by distended bursa tissue, and the gastrocnemius calcaneal bursa was especially enlarged (Figure 4A). The bursa was dissected from the surrounding tissue and incised carefully using a no. 11 blade, and the serous fluid was released (Figure 4B). The redundant bursa was separated and removed by blunt and sharp dissection until normal Achilles tendon was confirmed (Figure 4C). The medial retinaculum was apposed to the edge of the tendon with monofilament, absorbable suture material (PDS plus USP 3-0, Ethicon, Raritan, NJ, USA) using a horizontal mattress suture (Figure 4D).
Biopsy results. Synovium with adjacent fibrous connective tissue, adipose tissue, and vasculature. Moderate fibrosis (arrowhead) is noted, and moderately edematous lesions (asterisk) are identified (magnification x20, haematoxylin and eosin stain).
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F5
Histopathologic examination revealed that the specimens consisted of synovium with connective tissue with mild to moderate fibrosis (Figure 5).