Klein’s Lines

Other Known AliasesLine of Klein

DefinitionVirtual line drawn parallel from the femoral neck that should intersect the lateral upper edge of the femoral head

Clinical Significance Used in the radiographical diagnosis of slipped capital femoral epiphysis and allows for early diagnosis and surgical management to prevent avascular necrosis as an adult. The sensitivity and specificity are the highest if modified by a ≥2mm difference in the epiphyseal width lateral to Klein’s line compared to the unaffected side.

HistoryNamed after Armin Klein (1892-1954), who was an American orthopaedic surgeon and received his medical doctorate from Harvard Medical School in 1927. He completed his residency at Boston City Hospital and upon completion joined the faculty at Massachusetts General Hospital. It was here in 1952 that Klein and three colleagues published a case series on children with previously undiagnosed SCFE, but with positive findings using his technique. He would later go on to become Chief of Orthopaedic Surgery at the new Beth Israel Hospital in Boston and obtained teaching positions at Harvard Medical School and Tufts College Medical School.


  1. Firkin BG and Whitwirth JA.  Dictionary of Medical Eponyms. 2nd ed.  New York, NY; Parthenon Publishing Group. 1996.
  2. Bartolucci S, Forbis P.  Stedman’s Medical Eponyms.  2nd ed.  Baltimore, MD; LWW.  2005.
  3. Yee AJ, Pfiffner P. (2012).  Medical Eponyms (Version 1.4.2) [Mobile Application Software].  Retrieved http://itunes.apple.com.
  4. Whonamedit – dictionary of medical eponyms. http://www.whonamedit.com
  5. Up To Date. www.uptodate.com
  6. KLEIN A, JOPLIN RJ, REIDY JA, HANELIN J. Slipped capital femoral epiphysis; early diagnosis and treatment facilitated by normal roentgenograms. The Journal of bone and joint surgery. American volume. 1952; 34-A(1):233-9. [pubmed]
  7. https://journals.lww.com/jbjsjournal/Citation/1954/36040/ARMIN_KLEIN_1892_1954.29.aspx

One thought on “Ep-PAINE-nym

  1. Pingback: PAINE #PANCE Pearl – Orthopaedics | PAINE Podcast and Medical Blog

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s