To the Editor,
We read the intriguing case series by Bilham et al. [1] which were recently published in your journal. The authors described ultrasonographic dynamic examination findings (during hip traction technique) for the diagnosis of acetabular labral tears. Further, the authors reported that real-time, non-invasive ultrasound (US) examination with dynamic maneuvers may be of additional diagnostic value. We deem this effort of the authors important since invasive imaging methods (e.g. magnetic resonance or computed tomography arthrograms) are otherwise used as the gold standard before arthroscopy [1].
However, we would like to highlight a few important points that we think should be taken into account when performing musculoskeletal US in clinical practice. For example, the authors described that dynamic hip traction caused widening of the hypoechoic gap due to synovial fluid flow during the US examination [1]. This finding is not always very specific and the focal hypoechoic irregularity at the base of the anterior portion of the labrum may “simply” be a sublabral sulcus/recess (a normal anatomic variant) in up to 20% of cases (Supplementary Materials 1 and 2). This hypoechoic area needs to be examined and defined in details because the sublabral recess is generally linear/regular in shape, does not extend into the substance of the labrum or through the entire thickness of the labral floor, and is not associated with other perilabral abnormalities [2] (Supplementary Material 3). On the other hand, since anterior hip pain is not only related with joint problems and may be accompanied by periarticular painful conditions (e.g. periarticular bursa), static/dynamic US examination should be carefully performed [3]—for sure as the extension of prompt physical/specific examination [4].
Supplementary Information
Below is the link to the electronic supplementary material.
Supplementary Figure1 (JPG 1000 KB) Pitfalls in Ultrasound Examination of the Hip Labrum. In normal conditions (A), the synovial membrane (blue line) of the hip can protrude within the sublabral recess/sulcus. In pathological conditions (B), focal synovitis (red line) can progressively develop inside and/or around the labral tear. Yellow: capsule, white: labrum.
Supplementary Video 1 (AVI 7971 KB) Sonographic tracking of the sublabral recess in an asymptomatic volunteer.
Supplementary Video 2 (AVI 7561 KB) Sonographic tracking of a paralabral cyst in a patient with anterior hip pain.
Author contributions
All authors have contributed to the scientific discussion, manuscript writing and editing.
Funding
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Data availability
Data sharing does not apply to this article as no datasets were generated or analyzed during the current study.
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References
- 1.Billham J, Cornelson SM, Koch A, Nunez MJ, Estrada P, Kettner N. Diagnosing acetabular labral tears with hip traction sonography: a case series. J Ultrasound. 2021;24:547–553. doi: 10.1007/s40477-020-00446-x. [DOI] [PMC free article] [PubMed] [Google Scholar]
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- 3.Ricci V, Özçakar L. Ultrasound imaging for anterior hip pain: Hypertrophic bursitis between the direct tendon of the rectus femoris and the iliocapsularis muscle. PM&R. 2019;11:1031–1033. doi: 10.1002/pmrj.12165. [DOI] [PubMed] [Google Scholar]
- 4.Ricci V, Özçakar L. From “ultrasound imaging” to “ultrasound examination”: a needful upgrade in musculoskeletal medicine. Pain Med. 2020;21:1304–1306. doi: 10.1093/pm/pnz231. [DOI] [PubMed] [Google Scholar]
Associated Data
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Supplementary Materials
Supplementary Figure1 (JPG 1000 KB) Pitfalls in Ultrasound Examination of the Hip Labrum. In normal conditions (A), the synovial membrane (blue line) of the hip can protrude within the sublabral recess/sulcus. In pathological conditions (B), focal synovitis (red line) can progressively develop inside and/or around the labral tear. Yellow: capsule, white: labrum.
Supplementary Video 1 (AVI 7971 KB) Sonographic tracking of the sublabral recess in an asymptomatic volunteer.
Supplementary Video 2 (AVI 7561 KB) Sonographic tracking of a paralabral cyst in a patient with anterior hip pain.
Data Availability Statement
Data sharing does not apply to this article as no datasets were generated or analyzed during the current study.