RESUMEN
PURPOSE: To introduce a new magnetic resonance imaging (MRI) sign, termed the Cobra sign, and identify its diagnostic metrics. The secondary aim was to demonstrate that this sign can be a source of false evaluation of tendon retraction in patients with proximal hamstring avulsion injury. METHOD: This retrospective cohort study targeted patients surgically treated for proximal hamstring avulsion injury from January 2019 to June 2023. The MRI Cobra sign was defined as a wavy curved T2-hypointense band with the free end folding distally over itself, resembling a cobra head. The primary outcome measure was the characterization of the Cobra sign in patients with proximal hamstring avulsion injury. The secondary outcome was the association of this sign with tendon retraction. The study included 81 proximal hamstring avulsion injury patients (mean age of 45.7, SD = 13.9), with 41 (50.6%) complete avulsions, 33 semimembranosus, and 7 conjoint tendons. RESULTS: The MRI Cobra sign was found in 25 patients (17 semimembranosus and 8 complete). It was confirmed surgically only in semimembranosus cases. It demonstrated 51.5% sensitivity and 83.3% specificity for isolated semimembranosus avulsions, with a significant positive likelihood ratio of 3.0. MRI retraction was 10.05 cm (±3.0), reducing to 7.9 cm (±2.5) on surgical measurement (mean difference = 2.0 cm, p < 0.001). The regression analysis confirmed MRI retraction's influence on the Cobra sign, with a 1.4 odds increase per unit (p < 0.001). In linear regression analysis, each unit increase in MRI retraction corresponded to a 79% increase in surgical retraction (coefficient 0.7, t = 11.1, p < 0.001). CONCLUSION: The Cobra sign demonstrated acceptable diagnostic accuracy for isolated semimembranosus avulsion, with a high specificity of 83.3%, a low sensitivity of 51.5%, and a positive likelihood ratio of 3.0. The presence of the Cobra sign indicates an overestimated MRI retraction by approximately 21%. LEVEL OF EVIDENCE: Level III.
RESUMEN
INTRODUCTION: Synthol injection for body contouring has been used by bodybuilders for some time. We report two extremely rare systemic complications; pulmonary granulomatosis and hypercalcemia, in a woman who has received Synthol injections for buttocks augmentation. PRESENTATION OF CASE: The case discussed in this report is of a 36-year-old lady who presented for severe hypercalcemia and nephrocalcinosis. Subsequent workup revealed granulomas in the buttocks and in the lungs. Upon questioning, it was discovered that she had received Synthol injection for buttocks augmentation a few months earlier. Labs were consistent with calcitriol mediated hypercalcemia, a phenomenon observed in granulomatous diseases. A diagnosis of foreign body granulomatosis with pulmonary migration and secondary hypercalcemia was made. The patient was started on prednisone and showed an initial positive response. DISCUSSION: Reported complications of Synthol include pain, muscle deformity, and ulceration at the injection site. Hypercalcemia secondary to foreign body granulomatosis after Synthol injection has been reported only once previously, and here we report a second case. The hypercalcemia is thought to be calcitriol mediated, where overexpression of CYP27B1 in the macrophages forming the granulomas leads to pathological extrarenal calcitriol production. Pulmonary granulomatosis, theorized to be secondary to hematologic migration of the injected material, has never been reported previously with Synthol use. CONCLUSION: Synthol injection for body contouring may be a cause of extensive local and pulmonary foreign body granulomatosis leading to calcitriol mediated hypercalcemia. History of cosmetic injections should not be disregarded during history taking.