A Multicenter Study of Radiographic Measures Predicting Failure of Arthroscopy in Borderline Hip Dysplasia: Beware of the Tönnis Angle
Authors: McQuivey KS, Secretov E, Domb BG, Levy BA, Krych AJ, Neville M, Hartigan DE
Background
Borderline hip dysplasia presents a complex challenge in hip preservation. Accurate preoperative assessment is crucial to determine candidacy for arthroscopy versus more extensive bony procedures. This study investigates which radiographic measurements most accurately predict surgical failure.
Methods
Data were gathered from multiple centers evaluating patients with borderline hip dysplasia (LCEA 18–25°) who underwent arthroscopy. Radiographic parameters including the Tönnis angle were analyzed to identify their predictive value for clinical failure or revision surgery.
Key Findings
- A Tönnis angle >10° was strongly associated with clinical failure.
- 84% of patients with a Tönnis angle >10° required subsequent revision surgery.
- Other parameters (e.g., LCEA alone) were less predictive than the Tönnis angle in this population.
Conclusions
The Tönnis angle is a critical predictor of hip arthroscopy failure in borderline dysplasia. Elevated angles suggest insufficient acetabular coverage and are better addressed with alternative surgical strategies.
What Does This Mean for Providers?
In borderline dysplasia, a Tönnis angle >10° should raise red flags regarding the suitability of hip arthroscopy. Providers should consider alternative treatments such as periacetabular osteotomy (PAO) in these cases, as the risk for revision arthroscopy is high.