Abstract
Patients with thin hip capsules, capsular redundancy, capsular defects, hypermobility, dysplasia, and female patients are at increased risk of hip instability. As our understanding of the factors that contribute to hip instability has increased, so too has our ability to identify “at-risk” patients, in whom we should avoid surgery or perform capsular repair or plication following hip arthroscopy to achieve optimal results. We must tailor our surgical planning accord to gender, bony morphology, capsular volume, and properties of the tissue.
“Praemonitus, praemunitus”— Forewarned is forearmed.
A reasonable knowledge of Latin is helpful in medicine, but an understanding of the meaning of Latin proverbs is invaluable for life! As surgeons, we typically exist in a state of constant paranoia, sometimes healthy, sometimes not. Our internal dialogue keeps us alert to potential dangers lurking around the next drape: “What can I potentially damage during this operation?”; “Should I restrict that patient weight-bearing?”; “Will my fixation hold with that many anchors?”; and “Is better really the enemy of good?” But, it is these very fears that make us conscientious. They force us take a complete history, be thorough in our clinical examination, and meticulously assess preoperative imaging, so we have prior knowledge of possible dangers or problems, which may offer us a tactical advantage during surgery. Although we may need to think and act on-the-fly during an operation, the best surgeons do their decision-making and planning long before they wash their hands. The study by Metz, Featherall, Froerer, Mortensen, Tomasevich, and Aoki , entitled, “Female Patients and Decreased Hip Capsular Thickness on Magnetic Resonance Imaging Associated With Increased Axial Distraction Distance on Exam Under Anesthesia: An In-Vivo Study,”
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is a perfect example of how a little forewarning can leave the surgeon forearmed for the “wonderful struggle” that can be hip arthroscopy.In this study, the authors have demonstrated clearly that the hip capsular dimensions impact the distraction distance during hip arthroscopy.
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As one would expect, female patients have thinner capsules and, therefore, their hips are more easily distractible. As the authors conclude, female patients may be at increased risk of instability, a fact that has also been shown by others.2
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Indeed, the clearly demonstrated figures displayed in this study are very helpful and will surely add to the already existing knowledge to help us define patients who are “at-risk” for hip instability. Devitt et al. have previously shown that dysplastic patients are also more likely to have thinner capsules, hypermobility, and hip capsular redundancy.3
Furthermore, the importance of the results of the current study is supported by the consensus findings of an international expert consensus group seeking to define the “Criteria for the Operating Room Confirmation of the Diagnosis of Hip Instability”
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; consensus agreement was achieved for 8 criteria, 3 of which related directly to this study, namely, ease of hip distraction under anaesthesia (100.0% agreement), a capsular defect (86.7% agreement), and capsular status (80.0% agreement).Notwithstanding the importance of hip capsular management at the time of hip arthroscopy, an awareness of hip capsule dimensions has potentially a huge role in determining those patients that might be best to avoid surgery or be at increased risk of a poor outcome with surgery.
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Marland et al. have recently defined specific radiographic measures of acetabular dysplasia and hip instability on outcomes of female patients undergoing hip arthroscopy for femoroacetabular impingement.6
It would be interesting to see if there is a similar correlation with the findings of the current study by Metz et al.,1
in terms of hip capsular thickness and patient outcomes. However, perhaps the ultimate advantage of being forewarned about a thin capsule and an easily-distractible hip is to plan a surgical solution. Waterman et al. have previously demonstrated a method to reduce intra-articular volume with arthroscopic plication for capsular laxity.7
Kalisvaart et al. have also demonstrated improved short-term (1 year) pain and functional outcomes in patients with isolated arthroscopic suture capsular plication of the hip.5
In conclusion, this study adds to work of Magerkuth et al. and Packer et al., who have correlated radiographic findings with hip capsular laxity.
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When combined with our ever-increasing knowledge of the anatomy and function of the hip capsule, it provides surgeons with a greater awareness of structures, which can greatly impact the outcome of hip arthroscopy.10
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Perhaps a bit of paranoia is not such a bad thing. After all, as Woody Allen says, “Paranoia is knowing all the facts!”.Supplementary Data
- ICMJE author disclosure forms
References
- Female patients and decreased hip capsular thickness on magnetic resonance imaging associated with increased axial distraction distance on exam under anesthesia: An in vivo study.Arthrosccopy. 2022; 38: 3133-3140
- Criteria for the operating room confirmation of the diagnosis of hip instability: The results of an International Expert Consensus Conference.Arthroscopy. 2022; 38: 2837-2849.e2
- Hip instability: Anatomic and clinical considerations of traumatic and atraumatic instability.Clin Sports Med. 2011; 30: 349-367
- Generalized joint hypermobility is predictive of hip capsular thickness.Orthop J Sports Med. 2017; 52325967117701882
- Hip instability treated with arthroscopic capsular plication.Knee Surg Sports Traumatol Arthrosc. 2017; 25: 24-30
- Association of radiographic markers of hip instability and worse outcomes 2 to 4 years after hip arthroscopy for femoroacetabular impingement in female patients.Am J Sports Med. 2022; 50: 1020-1027
- Intra-articular volume reduction with arthroscopic plication for capsular laxity of the hip: A cadaveric comparison of two surgical techniques.Arthroscopy. 2019; 35: 471-477
- The cliff sign: A new radiographic sign of hip instability.Orthop J Sports Med. 2018; 62325967118807176
- Capsular laxity of the hip: Findings at magnetic resonance arthrography.Arthroscopy. 2013; 29: 1615-1622
- A quantitative analysis of hip capsular thickness.Knee Surg Sports Traumatol Arthrosc. 2015; 23: 2548-2553
- An anatomical study of the acetabulum with clinical applications to hip arthroscopy.J Bone Joint Surg Am. 2014; 96: 1673-1682
Article info
Footnotes
The authors report no conflicts of interest in the authorship and publication of this article. Full ICMJE author disclosure forms are available for this article online, as supplementary material.
See related article on page 3133
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© 2022 by the Arthroscopy Association of North America
