Advertisement

Diminished Hip Labral Width May Predict Inferior Outcome After Hip Femoroacetabular Impingement Surgery: Diminutive Labral Width is a Relative Indication for Labral Reconstruction

Published:January 24, 2023DOI:https://doi.org/10.1016/j.arthro.2023.01.020

      Abstract:

      Hip labral “width” should be defined as the distance from the condrolabral junction to the tip of the labrum in triangular cross-section. "Height” should refer to the distance from the joint surface to the perilabral recess (perpendicular to the width). "Length” is the distance from the anterior end of the labrum, adjacent to the anterior transverse acetabular ligament (TAL), to the posterior end of the labrum, adjacent to the posterior TAL (as may be relevant in reconstructions). Most studies of labral size focus on width, as it is thought to most contribute to the suction seal effect and hip stability. MRI most accurately measures labral width. Labral width at the time of surgery should be considered its maximal size; the labrum is reduced in size after repair. Hypoplastic labrums may result in worse outcomes after hip arthroscopy, and hyperplastic labrums may result higher scores than normoplastic labrums in patients with primary FAIS. Diminutive labral width is a relative indication for labral reconstruction.
      As with many nascent areas of study, nomenclature, relevant values, and importance of hip labrum size are still being crystalized. The current state of the literature is replete with a myriad of terms defining the same measurements. Width,
      • Kaplan D.J.
      • Samim M.
      • Burke C.J.
      • Meislin R.J.
      • Youm T.
      Validity of Magnetic Resonance Imaging Measurement of Hip Labral Width Compared With Intraoperative Assessment.
      • Kaplan D.J.
      • Samim M.
      • Burke C.J.
      • Baron S.L.
      • Meislin R.J.
      • Youm T.
      Decreased Hip Labral Width Measured via Preoperative Magnetic Resonance Imaging Is Associated With Inferior Outcomes for Arthroscopic Labral Repair for Femoroacetabular Impingement.
      • Brinkman J.C.
      • Domb B.G.
      • Krych A.J.
      • et al.
      Is Labral Size Predictive of Failure With Repair in Hip Arthroscopy?.
      • Drager J.
      • Rasio J.
      • Newhouse A.
      • Beck E.
      • Chahla J.
      • Nho S.J.
      Patients With a Hypotrophic Labrum Achieve Similar Outcomes After Primary Labral Repair Compared With Patients With a Normal-Sized Labrum: A Matched Cohort Analysis of 346 Patients With Femoroacetabular Impingement Syndrome.
      height,
      • Storaci H.W.
      • Utsunomiya H.
      • Kemler B.R.
      • et al.
      The Hip Suction Seal, Part I: The Role of Acetabular Labral Height on Hip Distractive Stability.
      and length as used by Liu, Gao, Wu, Dong, Zhang, and Xu in their recent study, “Changes in Hip Labral Size Two Years After Arthroscopic Repair are Correlated with Preoperative Measurements on Magnetic Resonance Imaging”

      Liu R, Gao G, Wu R, Dong H, Zhang S, Xu Y. Changes in hip labral size two years after arthroscopic repair are correlated with preoperative measurements on magnetic resonance imaging. Arthroscopy 2023;39:XXX-XXX.

      have all been used. This muddies the waters and needlessly complicates an already challenging topic. For the field to advance, standard terms must be agreed upon.
      I suggest we use, “width” when referring to the distance from the condrolabral junction to the tip of the labrum in triangular cross-section. I suggest we use, “height” when referring to the distance from the joint surface to the perilabral recess (perpendicular to the labral width). Lastly, I would use, “length” for the distance from the anterior end of the labrum, adjacent to the anterior transverse acetabular ligament (TAL), to the posterior end of the labrum, adjacent to the posterior TAL (as may be relevant in reconstructions). Most studies of labral size (have) focused on width, as it is thought most contributes to the suction seal effect and hip stability.
      • Philippon M.J.
      • Nepple J.J.
      • Campbell K.J.
      • et al.
      The hip fluid seal--Part I: the effect of an acetabular labral tear, repair, resection, and reconstruction on hip fluid pressurization.
      Given its proposed importance, the question of whether or not labral width can be accurately measured preoperatively has been investigated by several centers,
      • Walker M.
      • Maini L.
      • Kay J.
      • et al.
      The dimensions of the hip labrum can be reliably measured using magnetic resonance and computed tomography which can be used to develop a standardized definition of the hypoplastic labrum.
      ,
      • Comfort S.M.
      • Ruzbarsky J.J.
      • Ernat J.E.
      • Philippon M.J.
      Preoperative Magnetic Resonance Imaging Predicts Intraoperative Labral Width at the 9-O'clock and 12-O'clock Positions in Primary Hip Arthroscopy.
      including by myself and my mentors,
      • Kaplan D.J.
      • Samim M.
      • Burke C.J.
      • Meislin R.J.
      • Youm T.
      Validity of Magnetic Resonance Imaging Measurement of Hip Labral Width Compared With Intraoperative Assessment.
      ,
      • Kaplan D.J.
      • Samim M.
      • Burke C.J.
      • Baron S.L.
      • Meislin R.J.
      • Youm T.
      Decreased Hip Labral Width Measured via Preoperative Magnetic Resonance Imaging Is Associated With Inferior Outcomes for Arthroscopic Labral Repair for Femoroacetabular Impingement.
      (as well as by Liu et al.). With multiple studies demonstrating validity, I believe we can consider MRI a useful tool in measuring labral width. However, that answer only leads to more questions including, “what is a small or large labrum?”, and more importantly, “does labral size affect outcomes?”
      A recent systematic review found hypotrophic labral width has been defined as 3-7 mm in various studies, while hypertrophic has had a range of >6-10 mm.
      • Walker M.
      • Maini L.
      • Kay J.
      • et al.
      The dimensions of the hip labrum can be reliably measured using magnetic resonance and computed tomography which can be used to develop a standardized definition of the hypoplastic labrum.
      Some investigations have used arbitrary cut-offs,
      • Drager J.
      • Rasio J.
      • Newhouse A.
      • Beck E.
      • Chahla J.
      • Nho S.J.
      Patients With a Hypotrophic Labrum Achieve Similar Outcomes After Primary Labral Repair Compared With Patients With a Normal-Sized Labrum: A Matched Cohort Analysis of 346 Patients With Femoroacetabular Impingement Syndrome.
      while others, like by Liu et al, use a cohort-specific value, (such as 1-2 standard deviations above or below the mean). Further complicating matters, different modalities have been shown to produce different width measurements, with MRI measurements shown to be greater than arthroscopic
      • Philippon M.J.
      • Nepple J.J.
      • Campbell K.J.
      • et al.
      The hip fluid seal--Part I: the effect of an acetabular labral tear, repair, resection, and reconstruction on hip fluid pressurization.
      (this is likely due to practical considerations as MRI can measure from the actual chondrolabral base, while arthroscopic probe measurement likely can not reach as medial to the actual chondrolabral junction). Storaci et al found labrums < 6 mm had decreased suctional seal properties compared to those >6 mm, but this value was arbitrarily selected.
      • Storaci H.W.
      • Utsunomiya H.
      • Kemler B.R.
      • et al.
      The Hip Suction Seal, Part I: The Role of Acetabular Labral Height on Hip Distractive Stability.
      Until either additional biomechanical studies can identify a specific minimal threshold width that is necessary for an adequate suction seal, or a larger clinical study can confirm a threshold width, I will define hypoplasia based on our MRI study, consistent with most literature, based on 1 standard deviation less than the cohort’s mean (5 mm at 3’o clock, 4.9 at 11:30, and 3.6 mm at 1:30).
      • Kaplan D.J.
      • Samim M.
      • Burke C.J.
      • Baron S.L.
      • Meislin R.J.
      • Youm T.
      Decreased Hip Labral Width Measured via Preoperative Magnetic Resonance Imaging Is Associated With Inferior Outcomes for Arthroscopic Labral Repair for Femoroacetabular Impingement.
      MRI is likely the most useful modality to base future research on, as it is part of the routine standard of care for this patient population.
      It is important to note that labral width at the time of surgery should be considered its maximal size. While an early study found spontaneous labral regrowth after debridement,
      • Abrams G.D.
      • Safran M.R.
      • Sadri H.
      Spontaneous hip labrum regrowth after initial surgical debridement.
      a more recent study by Yoo et al found the labrum actually reduced in size after repair.
      • Yoo J.I.
      • Ha Y.C.
      • Lee Y.K.
      • Lee G.Y.
      • Yoo M.J.
      • Koo K.H.
      Morphologic Changes and Outcomes After Arthroscopic Acetabular Labral Repair Evaluated Using Postoperative Computed Tomography Arthrography.
      The findings of Liu et al. confirm a lack of regrowth after repair. Accordingly, surgeons should consider width measured on preoperative MRI as the maximum width of the repaired labrum when preoperative planning.
      All of the above is only relevant if labral size affects patient outcomes. The cadaver study by Storaci et al.
      • Storaci H.W.
      • Utsunomiya H.
      • Kemler B.R.
      • et al.
      The Hip Suction Seal, Part I: The Role of Acetabular Labral Height on Hip Distractive Stability.
      did find hypotrophic labrums had decreased maximal distraction force, distance to suction seal rupture and peak negative pressure. Our retrospective paper found hypoplastic labrums had lower PRO scores, and achieved MCID and PASS at lower rates than normoplastic labrums.
      • Kaplan D.J.
      • Samim M.
      • Burke C.J.
      • Baron S.L.
      • Meislin R.J.
      • Youm T.
      Decreased Hip Labral Width Measured via Preoperative Magnetic Resonance Imaging Is Associated With Inferior Outcomes for Arthroscopic Labral Repair for Femoroacetabular Impingement.
      On the other side of the spectrum, Liu et el’s study found hyperplastic labrums had higher PRO scores and achieved Pass at higher rates than normoplastic labrums. While these two clinical studies suggest labral size plays a role in outcomes, both were retrospective and had limited numbers in their hypoplastic and hyperplastic cohorts. It should also be noted that retrospective studies by Drager et al
      • Drager J.
      • Rasio J.
      • Newhouse A.
      • Beck E.
      • Chahla J.
      • Nho S.J.
      Patients With a Hypotrophic Labrum Achieve Similar Outcomes After Primary Labral Repair Compared With Patients With a Normal-Sized Labrum: A Matched Cohort Analysis of 346 Patients With Femoroacetabular Impingement Syndrome.
      and Brinkman et al
      • Brinkman J.C.
      • Domb B.G.
      • Krych A.J.
      • et al.
      Is Labral Size Predictive of Failure With Repair in Hip Arthroscopy?.
      did not find a relationship between labral size and patient outcomes. Importantly, these studies only apply to primary FAIS patients as it has been shown that dysplasia may affect labral size.
      • Nwachukwu B.U.
      • Gaudiani M.A.
      • Marsh N.A.
      • Ranawat A.S.
      Labral hypertrophy correlates with borderline hip dysplasia and microinstability in femoroacetabular impingement: a matched case-control analysis.
      ,
      • Gupta A.
      • Chandrasekaran S.
      • Redmond J.M.
      • et al.
      Does Labral Size Correlate With Degree of Acetabular Dysplasia?.
      Based on the current state of the literature, I am confident that hip labrum width can be measured on MRI, and will continue to incorporate the measurement as part of my routine preoperative work-up (similar to how most hip arthroscopists measure alpha angle and lateral center-edge angle for each patient). I will use diminutive labral width as one indication to have a graft for labral reconstruction available. I do think labrum width may contribute to outcomes, but am not yet ready to make treatment decisions based solely on labral size. For our field to reach this point, we will need additional compelling biomechanical studies as well as prospective investigations.

      Supplementary Data

      References:

        • Kaplan D.J.
        • Samim M.
        • Burke C.J.
        • Meislin R.J.
        • Youm T.
        Validity of Magnetic Resonance Imaging Measurement of Hip Labral Width Compared With Intraoperative Assessment.
        Arthroscopy. 2020; 36: 751-758
        • Kaplan D.J.
        • Samim M.
        • Burke C.J.
        • Baron S.L.
        • Meislin R.J.
        • Youm T.
        Decreased Hip Labral Width Measured via Preoperative Magnetic Resonance Imaging Is Associated With Inferior Outcomes for Arthroscopic Labral Repair for Femoroacetabular Impingement.
        Arthroscopy. 2021; 37: 98-107
        • Brinkman J.C.
        • Domb B.G.
        • Krych A.J.
        • et al.
        Is Labral Size Predictive of Failure With Repair in Hip Arthroscopy?.
        Arthroscopy. 2020; 36: 2147-2157
        • Drager J.
        • Rasio J.
        • Newhouse A.
        • Beck E.
        • Chahla J.
        • Nho S.J.
        Patients With a Hypotrophic Labrum Achieve Similar Outcomes After Primary Labral Repair Compared With Patients With a Normal-Sized Labrum: A Matched Cohort Analysis of 346 Patients With Femoroacetabular Impingement Syndrome.
        Arthroscopy. 2020; 36: 2614-2620
        • Storaci H.W.
        • Utsunomiya H.
        • Kemler B.R.
        • et al.
        The Hip Suction Seal, Part I: The Role of Acetabular Labral Height on Hip Distractive Stability.
        Am J Sports Med. 2020; 48: 2726-2732
      1. Liu R, Gao G, Wu R, Dong H, Zhang S, Xu Y. Changes in hip labral size two years after arthroscopic repair are correlated with preoperative measurements on magnetic resonance imaging. Arthroscopy 2023;39:XXX-XXX.

        • Philippon M.J.
        • Nepple J.J.
        • Campbell K.J.
        • et al.
        The hip fluid seal--Part I: the effect of an acetabular labral tear, repair, resection, and reconstruction on hip fluid pressurization.
        Knee Surg Sports Traumatol Arthrosc. 2014; 22: 722-729
        • Walker M.
        • Maini L.
        • Kay J.
        • et al.
        The dimensions of the hip labrum can be reliably measured using magnetic resonance and computed tomography which can be used to develop a standardized definition of the hypoplastic labrum.
        Knee Surg Sports Traumatol Arthrosc. 2021; 29: 1432-1452
        • Comfort S.M.
        • Ruzbarsky J.J.
        • Ernat J.E.
        • Philippon M.J.
        Preoperative Magnetic Resonance Imaging Predicts Intraoperative Labral Width at the 9-O'clock and 12-O'clock Positions in Primary Hip Arthroscopy.
        Arthrosc Sports Med Rehabil. 2022; 4: e1331-e1337
        • Abrams G.D.
        • Safran M.R.
        • Sadri H.
        Spontaneous hip labrum regrowth after initial surgical debridement.
        Clin Orthop Relat Res. 2013; 471: 2504-2508
        • Yoo J.I.
        • Ha Y.C.
        • Lee Y.K.
        • Lee G.Y.
        • Yoo M.J.
        • Koo K.H.
        Morphologic Changes and Outcomes After Arthroscopic Acetabular Labral Repair Evaluated Using Postoperative Computed Tomography Arthrography.
        Arthroscopy. 2017; 33: 337-345
        • Nwachukwu B.U.
        • Gaudiani M.A.
        • Marsh N.A.
        • Ranawat A.S.
        Labral hypertrophy correlates with borderline hip dysplasia and microinstability in femoroacetabular impingement: a matched case-control analysis.
        Hip international : the journal of clinical and experimental research on hip pathology and therapy. 2019; 29: 198-203
        • Gupta A.
        • Chandrasekaran S.
        • Redmond J.M.
        • et al.
        Does Labral Size Correlate With Degree of Acetabular Dysplasia?.
        Orthop J Sports Med. 2015; 32325967115572573