Relevance of the Popliteal Angle to Hamstring Length in Cerebral Palsy Crouch GaitThompson, Neill Stuart M.D., F.R.C.S. (Trand Orth); Baker, Richard Jonathan Ph.D.; Cosgrove, Aidan Patrick M.D., F.R.C.S.; Saunders, Jennifer Lynne M.C.S.P., S.R.P.*; Taylor, Trevor Childs F.R.C.S.Journal of Pediatric Orthopaedics: May-June 2001 - Volume 21 - Issue 3 - p 383-387 Selected Topics Abstract Author Information The popliteal angle is a widely used clinical means of assessing hamstring length in cerebral palsy patients. The relevance of the popliteal angle as a measure of hamstring length was assessed in this prospective study. Sixteen patients with cerebral palsy with crouch gait had their conventional and modified popliteal angles measured by nine observers on two separate occasions. With use of the conventional and modified forms of the test, 74 and 70%, respectively, of the observed variability was inter-and intraobserver related. The range of SDs for each observer using the conventional test was 7.1–13.6° (average 10.9°), and with use of the modified form of the test, the range was 6.3–4.2° (average 10.5°). The maximum hamstring length of each subject during gait was determined by three-dimensional modelling of their lower limbs. The modified popliteal angle measurements of the most repeatable observer demonstrated an inverse relationship between modified popliteal angle and maximum hamstring length (p < 0.01) and muscle excursion (p < 0.01). Only 10 of 32 limbs had short medial hamstrings. Study conducted at Musgrave Park Hospital, Belfast, Northern Ireland. From the Department of Orthopaedic Research, Musgrave Park Hospital, Belfast; and *Fleming Fulton School, Belfast, Northern Ireland Address correspondence and reprint requests to Mr. N. S. Thompson, Department of Orthopaedic Research, Musgrave Park Hospital, Stockmans Lane, Belfast BT9 7JB, Northern Ireland. E-mail: NEILLT@ aol.com © 2001 Lippincott Williams & Wilkins, Inc.