Intra- and intertester reliability and criterion validity of the parallelogram and universal goniometers for measuring maximum active knee flexion and extension of patients with knee restrictions

Objective: To examine the intra- and intertester reliability of the universal goniometer (UG) and parallelogram goniometer (PG), and to assess the criterion validity of the same instruments on subjects with knee restrictions. Design: Reliability and validation study. Setting: Radiology department at university hospital. Participants: Sixty subjects (34 men, 26 women; mean age, 52yr) with various knee restrictions. Interventions: Sixteen goniometric measurements were collected per patient by 2 physical therapists. Subjects were evaluated in knee flexion and knee extension positions. To serve as a gold standard, radiographs were taken in both positions. Main Outcome Measures: Active knee flexion and knee extension on 2 goniometers, radiographs. Maximum active range of motion (AROM). Results: The UG intratester reliability (intraclass correlation coefficients [ICCs]) was .997 in flexion and .972 to .985 in extension. The results were also high with the PG (ICC = .996,.953-.955) for flexion and extension, respectively. The intertester reliability was high for flexion (ICC = .977-.982) and for extension (ICC = .893-.926) when using the UG. For the PG, ICC results ranged from .959 to .970 for flexion and from .856 to,898 for extension. Criterion validity (r) varied from .975 to .987 for flexion and from .390 to .442 for extension with the UG, and from .976 to .985 for flexion and .423 to .514 for extension with the PG. Conclusion: Intra- and intertester reliability were high for both goniometers, The results for the criterion validity varied. Our study also revealed that it is preferable to use goniometry rather than Visual estimations when measuring AROM. It is recommended that the same therapist take all the measurements when assessing AROM for UG and PG goniometric measurements on patients with knee restrictions.