Correlation between the rotational degree of the dial test and arthroscopic and physical findings in posterolateral rotatory instability

Diagnosing posterolateral rotatory instability (PLRI) is difficult because it occurs rarely, takes time to manifest, and no single definitive tool exists in diagnosing posterolateral corner injuries. We sought to evaluate the correlation between rotational degrees in the dial test and physical and arthroscopic findings that surgically verified PLRI in the knee joint. Patients (n = 67) who were diagnosed as having PLRI and received posterolateral reconstruction (n = 57) and repair (n = 10) from 1998 to 2006 were recruited. Preoperative physical findings were evaluated under anesthesia, and arthroscopic findings during surgeries were analyzed. A dial test with post-anesthesia (spinal or general) was conducted. We divided patients into three subgroups (A: <15°, B: 15–20°, and C: >20°), according to differences in rotational degrees in the dial test. All tests showed significant differences among the three groups and positive findings increased as the rotational degrees increased. No test showed a statistically significant difference in the specific group. All tests except for popliteal hiatus widening showed significant differences among the three groups and positive findings also increased as the rotational degrees increased. The total incidence and positive rate of each physical examination and the popliteal hiatus arthroscopic findings in PLRI significantly increased as the rotational degree in the dial test increased. The number of positive findings on physical examination was larger than the number of positive findings by arthroscopy in all three groups.