Patellofemoral alignment: Reliability

David A. Tomsich, Arthur J. Nitz, A. Joseph Threlkeld, Robert Shapiro

Research output: Contribution to journalArticlepeer-review

77 Scopus citations


Clinical assessment of the patellofemoral alignment is frequently performed, yet the repeatability of these measurements has not been previously investigated. This study examined the reliability of measuring patellofemoral alignment. The Q angle, A angle, and patellar orientation (mediolateral tilt, mediolateral position, superoinferior tilt, and rotation) of 27 healthy subjects were measured over three trials using standardized positioning and operationally defined goniometric, pluri-cal caliper, and visual estimation measurement techniques. Intratester and intertester intraclass correlation coefficients of measurements obtained with the pluri- cal caliper and goniometer ranged from .52 to .86 and .003 to .61, respectively. Intratester and intertester standard errors of the instrumented measurements ranged from 1.6 to 3.5° and 3.2 to 6.8° (.28 and .55 cm for mediolateral position, respectively. Intratester kappa's of visually estimating patellar orientation ranged from .40 to .57. Intertester kappa's were between .03 and .30. The results suggest that both clinical estimation and instrumented measurement of patellofemoral alignment may be unreliable.

Original languageEnglish
Pages (from-to)200-208
Number of pages9
JournalJournal of Orthopaedic and Sports Physical Therapy
Issue number3
StatePublished - 1996


  • alignment
  • patellofemoral
  • reliability

ASJC Scopus subject areas

  • Physical Therapy, Sports Therapy and Rehabilitation


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