The Borderline Dysplastic Hip in a Young Athlete
A 24-year-old female recreational marathon runner presents with 8 months of right groin pain that began insidiously without trauma. Pain is worse with prolonged sitting and with hip flexion beyond 90 degrees, and she now limits her long runs. Examination: painful impingement sign with flexion-adduction-internal rotation, painful log roll, and restricted internal rotation to 10 degrees at neutral (left side 35 degrees). Radiographs show a lateral center-edge angle of 22 degrees, a Tonnis angle of 12 degrees, a sharp angle of 42 degrees, and a congruent joint space with no osteoarthritic changes. MRI shows a labral tear anterosuperiorly and no cartilage loss on the acetabular side. She is a high-demand athlete who wishes to return to marathons.
1. How do you interpret the borderline radiographic indices, and what does this mean for operative planning?
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The indices straddle the dysplasia/Borderline dysplasia boundary: LCEA 22 degrees is at the lower limit of normal (borderline 18-25), Tonnis angle 12 degrees is normal-to-borderline, and a sharp angle of 42 degrees is at the upper normal limit. The restricted internal rotation and positive FAI test point to an intrasubstance cam/pincer component or capsular restriction rather than pure instability. Key judgment: in a congruent, non-arthritic joint with a labral tear, the decision is whether the labrum is failing because of instability (dysplasia-driven) or impingement (morphology-driven). I would obtain a false-profile view and a Dunn 45 view to characterize anterior coverage and cam morphology, and consider a CT for version. If anterior coverage is deficient, isolated arthroscopic labral repair risks failure; if coverage is adequate, arthroscopic treatment of cam/labral pathology is reasonable. The radiographic numbers alone do not dictate the operation - the pattern of coverage and cartilage status do.
2. She asks whether she can avoid surgery and keep running. How do you counsel her, and what is your nonoperative plan?
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Counsel that there is no high-level evidence that running accelerates arthritis in a congruent hip, but that her current pain is activity-limiting and her exam shows a mechanically irritable hip. A structured 8-12 week trial is appropriate: activity modification (reduce mileage, avoid deep hip flexion loading), hip flexor and gluteal strengthening, core stability, and a gradual return-to-run program. Inject a diagnostic intra-articular corticosteroid/local anesthetic if the diagnosis is in doubt - a positive response supports an intra-articular source. Set objective milestones: pain-free ADLs, negative impingement sign, and tolerance of a graded run-walk program. If she plateaus or the labral symptoms persist, proceed to arthroscopy with the caveat that return to marathon distance is not guaranteed and that dysplasia increases the risk of failure if coverage is truly deficient.
3. If she undergoes arthroscopy, what findings would change your intraoperative plan?
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Findings that would escalate or change the plan: (1) diffuse chondral damage on the acetabular side (Outerbridge III-IV) - debride rather than repair, and counsel against high-demand return; (2) a labrum that is degenerate and non-repairable - consider reconstruction rather than repair; (3) a cam lesion with a large alpha angle - perform femoroplasty; (4) a pincer component with a deep acetabulum - rim trimming with care not to worsen coverage; (5) if the labrum is avulsed and the acetabular rim is dysplastic with deficient coverage, consider labral reconstruction and possible later reorientation rather than aggressive rim trimming. Document cartilage status and coverage before deciding; the intraoperative exam under anesthesia (range of motion, impingement) guides the amount of bony resection.