title: Human growth hormone may be detrimental when used to accelerate recovery from acute tendon-bone interface injuries.
abstract: BACKGROUND
  There have been few scientific studies that have examined usage of human growth hormone to accelerate recovery from injury. The hypothesis of this study was that human growth hormone would accelerate tendon-to-bone healing compared with control animals treated with placebo in a rat model of acute rotator cuff injury repair.
  
  
  METHODS
  Seventy-two rats underwent repair of acute rotator cuff injuries and were randomized into the following postoperative dosing regimens: placebo, and human growth hormone at 0.1, 1, 2, 5, and 10 mg/kg/day, administered subcutaneously once per day for fourteen days (Protocol 1). An additional twenty-four rats were randomized to receive either (1) placebo or (2) human growth hormone at 5 mg/kg, administered subcutaneously twice per day for seven days preoperatively and twenty-eight days postoperatively (Protocol 2). All rats were killed twenty-eight days postoperatively. Mechanical testing was performed. Ultimate stress, ultimate force, stiffness, energy to failure, and ultimate distension were determined.
  
  
  RESULTS
  For Protocol 1, analysis of variance testing showed no significant difference between the groups with regard to ultimate stress, ultimate force, stiffness, energy to failure, or ultimate distension. In Protocol 2, ultimate force to failure was significantly worse in the human growth hormone group compared with the placebo group (21.1 ± 5.85 versus 26.3 ± 5.47 N; p = 0.035). Failure was more likely to occur through the bone than the tendon-bone interface in the human growth hormone group compared with the placebo group (p = 0.001). No significant difference was found for ultimate stress, ultimate force, stiffness, energy to failure, or ultimate distension between the groups in Protocol 2.
  
  
  CONCLUSIONS
  In this rat model of acute tendon-bone injury repair, daily subcutaneous postoperative human growth hormone treatment for fourteen days failed to demonstrate a significant difference in any biomechanical parameter compared with placebo. Furthermore, subcutaneous administration of 5 mg/kg of human growth hormone twice daily from seven days preoperatively until twenty-eight days postoperatively demonstrated lower loads to ultimate failure and a higher risk of bone fracture failure compared with placebo.
authors: Orthopedic Institute, Section of Sports Medicine and Shoulder Surgery, 810 East 23rd Street, Sioux Falls, SD 57117, USA. Kbaumga@yahoo.com
authors: Keith M
authors: KM
authors: Baumgarten
authors: Harvey A
authors: HA
authors: Oliver
authors: Jack
authors: J
authors: Foley
authors: Ding-Geng
authors: DG
authors: Chen
authors: Peter
authors: P
authors: Autenried
authors: Shanzhong
authors: S
authors: Duan
authors: Patrick
authors: P
authors: Heiser
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D004195:Disease Models, Animal; D050723:Fractures, Bone / Q000188:drug therapy* / Q000503:physiopathology / Q000601:surgery; D019382:Human Growth Hormone / Q000008:administration & dosage* / Q000494:pharmacology; D007279:Injections, Subcutaneous; D036341:Intercellular Signaling Peptides and Proteins / Q000008:administration & dosage*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013708:Tendon Injuries / Q000188:drug therapy* / Q000601:surgery; D014945:Wound Healing / Q000187:drug effects*
chemical_list: D036341:Intercellular Signaling Peptides and Proteins; D019382:Human Growth Hormone