Abstract
Purpose
To define a distraction distance (pull length) cut‐off that would differentiate those patients with hip microinstability and those without the disorder, called the Pull‐Out Test.
Methods
In total, 100 consecutive patients undergoing hip arthroscopy were included in the study. Patients were separated into a hip microinstability group (HMI) and non‐hip microinstability group (NHI) based on the results of Beighton's score, the abduction–extension–external rotation test, hip extension–external rotation examination, and the prone instability test. Inclusion criteria were patients with an magnetic resonance imaging‐proven labral tear who did not respond to conservative treatment and underwent hip arthroscopy. Exclusion criteria included those patients undergoing revision hip arthroscopy, had a previous surgery on the ipsilateral hip, or had severe arthritis in the hip. The Pull‐Out Test was performed before surgery with the hip in 30° of abduction and the foot in 30° of external rotation. A blinded examiner places gross axial traction on the leg until a firm end point is reached. The distraction distance between the femoral head and acetabulum is the pull length.
Results
In total, 32 patients made up the HMI group whereas 68 patients were in the NHI group. The average pull length for the NHI group was 0.9 ± 0.1 cm and 1.7 ± 0.4 cm for the HMI group (
P
Conclusions
The Pull‐Out Test is a useful test in identifying and confirming the presence of hip microinstability in patients undergoing hip arthroscopy. A pull‐length of 1.3 cm or greater is consistent with the presence of microinstability with a specificity of 94% and a sensitivity of 96%.
Level of Evidence
Level IV, diagnostic, case‐control study.