title: Factors That Determine Supination Strength Following Distal Biceps Repair.
abstract: BACKGROUND
  Supination weakness commonly occurs after a distal biceps repair. The goal of this study was to identify factors that could influence postoperative supination strength through a full arc of forearm rotation.
  
  
  METHODS
  Fifteen patients were prospectively studied and underwent a biceps repair using a posterior approach; this cohort was compared with a randomized selection of 17 anterior repair subjects. All patients underwent postoperative magnetic resonance imaging (MRI). Quantitative MRI analysis determined the insertion site angle of the tendon and supinator fat content. Supination strength was measured in 3 forearm positions. A multiple linear regression analysis was performed to determine the effect of all factors on supination strength.
  
  
  RESULTS
  The anterior group had a significantly higher nonanatomic insertion site angle of the tendon than the control group and the posterior group (p < 0.001). The posterior group had significantly greater supinator fat content (p ≤ 0.019) than both the control group and the anterior group. After repair, the posterior group had significantly greater supination strength than the anterior group (p = 0.027). Multiple regression analysis (r = 0.765) found that an anatomic reinsertion of the ruptured tendon (β = 1.159; p < 0.001), posterior approach (β = 0.484; p = 0.043), and limited supinator muscle fat content (β = 0.360; p = 0.013) were significant predictors of the restoration of supination strength in 60° of supination.
  
  
  CONCLUSIONS
  Future directions for distal biceps tendon repair techniques should focus on restoring an anatomic reattachment site while limiting supinator damage.
  
  
  METHODS
  Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.
authors.affiliation: Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania schmidtc@upmc.edu.
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Schmidt
authors.affiliation: Departments of Bioengineering (B.T.B.) and Mechanical Engineering and Materials Science (M.C.M.), University of Pittsburgh, Pittsburgh, Pennsylvania.
authors.forename: Brandon T
authors.initials: BT
authors.lastname: Brown
authors.affiliation: St. Mary's Center for Orthopaedics, Auburn, Maine.
authors.forename: Lars M
authors.initials: LM
authors.lastname: Qvick
authors.affiliation: Department of Orthopaedic Surgery, Crystal Clinic Orthopaedic Center, Kent, Ohio.
authors.forename: Rafal Z
authors.initials: RZ
authors.lastname: Stacowicz
authors.affiliation: Department of Radiology, Allegheny General Hospital, Pittsburgh, Pennsylvania.
authors.forename: Carmen R
authors.initials: CR
authors.lastname: Latona
authors.affiliation: Departments of Bioengineering (B.T.B.) and Mechanical Engineering and Materials Science (M.C.M.), University of Pittsburgh, Pittsburgh, Pennsylvania.
authors.forename: Mark Carl
authors.initials: MC
authors.lastname: Miller
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena / Q000502:physiology; D005260:Female; D005542:Forearm / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000293:injuries / Q000503:physiopathology / Q000601:surgery*; D016059:Range of Motion, Articular / Q000502:physiology; D013484:Supination / Q000502:physiology*; D013708:Tendon Injuries / Q000503:physiopathology / Q000601:surgery*; D016896:Treatment Outcome