title: Unstable trochanteric fractures augmented with calcium phosphate cement. A prospective randomized study using radiostereometry to measure fracture stability.
abstract: OBJECTIVE
  Internally fixed unstable trochanteric fractures might be difficult to retain in position during healing. Secondary displacement might lead to malunion and poor functional result. The aim with this study was to measure whether augmentation with resorbable calcium-phosphate cement could improve fracture stability as shown in biomechanical studies.
  
  
  METHODS
  26 ambulatory patients with an unstable trochanteric fracture were randomized to treatment with a sliding screw device alone (Controls) or the same device combined with calcium-phosphate cement for augmentation (Augmented). All patients were allowed unrestricted weight bearing after surgery. Fracture movement was measured with radiostereometry (RSA) at 1 and 6 weeks and at 6 months.
  
  
  RESULTS
  Two patients died during the study period due to unrelated causes and another three were excluded due to technical problems with the RSA in two and concomitant illness in one. 21 patients (11 Augmented and 10 Controls) were followed according to the study protocol. At 1 week the augmented fractures had moved on average 1.9+/-1.7 mm while movement in the controls was 4.0+/-2.4 mm (p < 0.05). The average total movement from the day after surgery until 6 months, when all fractures had healed, was 7.8+/-6.2 mm for the augmented fractures and 13.2+/-4.3 mm for the controls (p < 0.05). Varus angulation was the most pronounced rotational movement for both groups although augmented fractures revealed less varus angulation compared with controls at all time points. Rotation around the longitudinal and transversal axes were small with no significant differences between treatment groups.
  
  
  CONCLUSIONS
  Augmentation with calcium-phosphate cement improved the stability of unstable trochanteric fractures fixed with a sliding screw device. The improvement was most pronounced for varus angulation and lateral and distal migration of the head and neck fragment.
authors.affiliation: Department of Orthopedics, Uppsala University Hospital, Uppsala, Sweden. Per.Mattsson@ortopedi.uu.se
authors.forename: P
authors.initials: P
authors.lastname: Mattsson
authors.forename: S
authors.initials: S
authors.lastname: Larsson
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D001843:Bone Cements; D001863:Bone Screws; D002130:Calcium Phosphates / Q000627:therapeutic use*; D005260:Female; D006620:Hip Fractures / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D008297:Male; D011446:Prospective Studies; D012399:Rotation; D016474:Weight-Bearing
chemical_list: D001843:Bone Cements; D002130:Calcium Phosphates; C020243:calcium phosphate