A NEW THRESHOLD FOR APPENDICULAR LEAN MASS DISCRIMINATES MUSCLE WEAKNESS IN WOMEN WITH HIP FRACTURE: A CROSS-SECTIONAL STUDY. Objective To investigate the relationship between measures of muscle mass and grip strength in women with subacute hip fracture. Firstly, we aimed to assess the capability of the current thresholds for appendicular lean mass (aLM), aLM-to-body-mass-index ratio and aLM/height2 to separate weak and non-weak women. Secondly, we aimed to explore alternative thresholds for the 3 measures of muscle mass to discriminate weakness. Design Cross-sectional study of 160 women with hip fracture admitted to a rehabilitation hospital. We assessed aLM by dual-energy x-ray absorptiometry and grip strength by a Jamar hand dynamometer. Weakness was defined as grip strength <16 kg. Results Weakness was not significantly associated with aLM <15.02 kg, aLM-to-body-mass-index ratio <0.512 or aLM/height2 <5.67 kg/m2. For aLM (but not for the other 2 measures of muscle mass) an alternative threshold (11.87 kg instead of 15.02 kg) significantly discriminated weakness: χ2 (1, n=160)=10.77 (p=0.001). The association between aLM <11.87 kg and grip strength <16 kg persisted after adjustment for age and body mass index: odds ratio =2.50 (95% CI 1.17-5.34; p=0.018). Conclusions Data suggests that the current thresholds for measures of muscle mass do not discriminate weakness in women with subacute hip fracture. For aLM an alternative cutoff-point actually separated weak and non-weak women. CORRESPONDING AUTHOR: Dr. Marco Di Monaco, Osteoporosis Research Center, Division of Physical Medicine and Rehabilitation, Presidio Sanitario San Camillo, Strada Santa Margherita 136, 10131, Torino, Italy. Tel. 0039 011 8199411; Fax 0039 011 8193012; Email Marco.di.monaco@alice.it,m.di-monaco@h-sancamillo.to.it DISCLOSURES: All the authors have no conflicts of interest. The study was not funded. The authors had no financial benefits for the study. The results have not been previously presented. Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.