title: Comparison of the cable pin system with conventional open surgery for transverse patella fractures.
abstract: BACKGROUND
  The cable pin system is an effective device for fixation of transverse patella fractures. However, whether this device provides superior results using a minimally invasive technique instead of conventional open surgery using the K wire tension band method is unclear.
  
  
  OBJECTIVE
  We asked whether a minimally invasive technique would be associated with (1) increased operative time; (2) reduced postoperative pain; (3) faster recovery of ROM; (4) higher knee scores; and (5) reduced complications.
  
  
  METHODS
  Forty patients with displaced transverse fractures of the patella participated in this prospective, randomized, controlled trial. Twenty of these patients underwent a minimally invasive technique and the others had conventional open surgery using K wires. Some data for six of the 20 patients who underwent the minimally invasive technique were published in an earlier prospective, observational trial. At postoperative intervals of 1, 3, 6, 12, and 24 months, pain was measured by VAS scores, active flexion and extension of the knee were measured in degrees by goniometry, and knee function was evaluated using the Böstman clinical grading scale.
  
  
  RESULTS
  Operative time was longer in the minimally invasive surgery group (54.3 ± 9.8 minutes versus 48.5 ± 6.1 minutes). Pain scores were better (lower) in the minimally invasive surgery group at 1 and 3 months but not at 6 months. Early flexion, ultimate flexion, and knee scores from 3 to 24 months, likewise, were better in the minimally invasive surgery group. Complications mostly related to symptomatic hardware were less common in the minimally invasive surgery group.
  
  
  CONCLUSIONS
  The minimally invasive technique is superior to conventional open surgery using K wires in terms of less early postoperative pain, better mobility angles of the injured knee, higher functional score of the injured knee, and decreased incidence of complications.
  
  
  METHODS
  Level I, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.
authors.affiliation: Department of Orthopedics, Changhai Hospital, The Second Military Medical University, Shanghai, PR China.
authors.forename: Ningfang
authors.initials: N
authors.lastname: Mao
authors.forename: Deding
authors.initials: D
authors.lastname: Liu
authors.forename: Haijian
authors.initials: H
authors.lastname: Ni
authors.forename: Hao
authors.initials: H
authors.lastname: Tang
authors.forename: Qiulin
authors.initials: Q
authors.lastname: Zhang
mesh_terms: D000328:Adult; D000368:Aged; D053587:Arthrometry, Articular; D001696:Biomechanical Phenomena; D001858:Bone Nails; D001864:Bone Wires; D016009:Chi-Square Distribution; D002681:China; D005260:Female; D005593:Fracture Fixation, Internal / Q000009:adverse effects / Q000295:instrumentation*; D050723:Fractures, Bone / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D019060:Minimally Invasive Surgical Procedures; D010147:Pain Measurement; D010149:Postoperative Pain / Q000175:diagnosis / Q000209:etiology; D010329:Patella / Q000000981:diagnostic imaging / Q000293:injuries* / Q000503:physiopathology / Q000601:surgery*; D011446:Prospective Studies; D011474:Prosthesis Design; D011859:Radiography; D016059:Range of Motion, Articular; D020127:Recovery of Function; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult