Comment on

• Relative effectiveness of an extension program and a combined program of manipulation and flexion and extension exercises in patients with acute low back syndrome.

  Erhard RE, Delitto A, Cibulka MT. Erhard RE, et al. Phys Ther. 1994 Dec;74(12):1093-100. doi: 10.1093/ptj/74.12.1093. Phys Ther. 1994. PMID: 7991650 Clinical Trial.
• Evidence for use of an extension-mobilization category in acute low back syndrome: a prescriptive validation pilot study.

  Delitto A, Cibulka MT, Erhard RE, Bowling RW, Tenhula JA. Delitto A, et al. Phys Ther. 1993 Apr;73(4):216-22; discussion 223-8. doi: 10.1093/ptj/73.4.216. Phys Ther. 1993. PMID: 8456141 Clinical Trial.
• The relationship between nonorganic signs and centralization of symptoms in the prediction of return to work for patients with low back pain.

  Karas R, McIntosh G, Hall H, Wilson L, Melles T. Karas R, et al. Phys Ther. 1997 Apr;77(4):354-60; discussion 361-9. doi: 10.1093/ptj/77.4.354. Phys Ther. 1997. PMID: 9105339
• Classification and low back pain: a review of the literature and critical analysis of selected systems.

  Riddle DL. Riddle DL. Phys Ther. 1998 Jul;78(7):708-37. doi: 10.1093/ptj/78.7.708. Phys Ther. 1998. PMID: 9672545 Review.
• Use of a classification system to guide nonsurgical management of a patient with chronic low back pain.

  Maluf KS, Sahrmann SA, Van Dillen LR. Maluf KS, et al. Phys Ther. 2000 Nov;80(11):1097-111. Phys Ther. 2000. PMID: 11046197