Ultrasound Accurately Measures Presence, Length and Diameter of the Palmaris Longus Tendon
Christine Cleora Johnson, MD1; Emil Stefan Vutescu, MD2; Theodore T. Miller, MD3; Ogonna K. Nwawka, MD3; Daniel J. Johnson, BS4; Steve K Lee, MD3; Scott W Wolfe, MD5
1Orthopaedic Surgery, Hospital for Special Surgery, New York, NY; 2Columbia, New York, NY, 3Hospital for Special Surgery, New York, NY; 4Vanderbilt University Medical Center, Nashville, TN, 5Hand and Upper Extremity Surgery, Hospital for Special Surgery, New York, NY
Purpose: Inadvertent harvest of the median nerve is a devestating and avoidable complication of harvest of the palmaris longus (PL) tendon. Accurate assessment of PL presence and dimensions preoperatively would minimize this risk, and simultaneously assure the harvest of adequate donor material for tendon graft. The purpose of our study was to determine the ability of ultrasound to accurately detect the PL and its dimensions. We hypothesized that ultrasound would accurately predict the presence, length and diameter of the palmaris longus tendon.
Methods: 17 cadaveric upper extermities were studied using a LOGIQ E9 ultrasound system (General Electric Healthcare, Milwaukee, WI). Two board-certified musculoskeletal radiologists assessed the presence of the PL tendon, as well as its length and diameter. Each wrist was explored through a 2cm transverse wrist incision, and the tendon, when present, was harvested with a tendon stripper and measured. A two-way mixed consistency intraclass correlation coefficient (ICC) was used to assess inter-rater reliability and agreement between surgical and ultrasound measurements.
Results: The PL tendon was present in 13 of 17 specimens for a prevalence of 76%. Both radiologists correctly identified the tendon in all 13 specimens for a sensitivity of 100%. Both radiologists also accurately identifed tendon absence in the remaining four specimens for a specificity of 100%. Ultrasound assessment of length (mean, 10.9 ± 3cm) forrelated with surgical measurements of tendon length (mean, 12.2 ± 3.6cm, ICC: 0.97, p<0.05). Ultrasound measurements of tendon diameter (mean, 0.54 ± 0.13cm) also correlated with surgical measurements (mean, 0.50 ± 0.13cm, ICC: 0.79, p<0.05). Intraclass correlation coefficient between the radiologists' measurement of PL tendon dimensions was almost perfect (ICC: 0.97, p<0.05).
Conclusion: These data demonstrate that ultrasound can determine palmaris tendon presence, length, and diameter with excellent accuracy and almost perfect inter-observer reliability. Ultrasound is a useful tool for preoperative evaluation of the palmaris longus tendon that will increase patient safety.
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