Background The presence of thigh muscle edema as characterized by increased signal intensity on MRI has been used to support the diagnosis of presumed local anesthetic-induced myotoxicity reported after total knee arthroplasty (TKA) with continuous adductor canal block (CACB). However, neither postoperative baseline imaging appearance nor muscle enzyme values have been described in conjunction with this clinical scenario. Thus, the usefulness of MRI or enzymatic biomarkers of muscle injury for supporting the diagnosis of local anesthetic myotoxicity is unknown.
Methods This descriptive case series documents postoperative MRI appearance of the ipsilateral upper leg, plus preoperative and postoperative creatine phosphokinase and aldolase values in volunteer patients who underwent uncomplicated TKA with CACB.
Results In 27 volunteer patients with no postsurgical evidence of clinically relevant myotoxicity, anterior thigh muscle edema was universally evident on imaging (n=12) and muscle enzyme values (n=19) were normal or only slightly elevated.
Conclusions The non-specificity of these findings suggests that MRI and near normal muscle enzyme levels are of limited diagnostic value when there is clinical suspicion of local anesthetic myotoxicity in the setting of TKA with CACB.
Trial registration number NCT04821245.
- postoperative complications
- lower extremity
Data availability statement
All data relevant to the study are included in the article or uploaded as supplementary information. Deidentified raw data provided as supplementary information with this article.
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Contributors LM participated in study design, data analysis, and manuscript preparation. JMN participated in study design and coordination, patient recruitment, data analysis, and manuscript preparation. CCB participated in study design, radiological analysis, data analysis, and manuscript preparation. DWJ participated in radiological coordination and approved the manuscript. NAH participated in analgesic management and approved the manuscript. KMM participated in orthopedic management and approved the manuscript. DW participated in analgesic management and approved the manuscript. PJV participated in study design, orthopedic management, and approved the manuscript.
Funding Supported by a Washington State Society of Anesthesiologists Seafair Grant.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.