title: A retrospective review of bone tunnel enlargement after anterior cruciate ligament reconstruction with hamstring tendons fixed with a metal round cannulated interference screw in the femur.
abstract: OBJECTIVE
  To assess bone tunnel enlargement after anterior cruciate ligament (ACL) reconstruction with the use of hamstring tendons fixed with a round cannulated interference (RCI) screw in the femur.
  
  
  METHODS
  A consecutive series of 30 ACL reconstructions performed with hamstring tendons fixed with an RCI screw in the femur and with staples via Leeds-Keio ligament in the tibia was retrospectively reviewed. The clinical outcome was evaluated through the Lysholm score. Anterior instability was tested by Telos-SE (Telos Japan, Tokyo, Japan) measurement. The location and angle of each femoral and tibial tunnel were measured with the use of plain radiographs, and bone tunnel enlargement greater than 2 mm detected any time 3, 6, 12, and 24 months postoperatively was defined as positive. Each factor (location and angle of the tunnels, sex, affected side, age, Lysholm score, and Telos-SE measurement) was compared between enlarged and nonenlarged groups.
  
  
  RESULTS
  Positive enlargement of the bone tunnel (>2.0 mm) was observed in 36.7% (11 of 30) on the femoral side and 33.3% (10 of 30) on the tibial side, and in 6 knees of both sides. Half of patients (15 of 30) had an enlarged tunnel on the femoral or the tibial side until 1 year postoperatively. In most cases, enlargement reached maximum at 6 months postoperatively. Female patients tended to have an enlarged tunnel, especially on the femoral side (P < .05). Tunnel enlargement was not correlated with location and angle of the tunnels. Moreover, no difference was found in Lysholm score and Telos-SE measurement between enlarged and nonenlarged groups, although the nonenlarged group tended to exhibit higher Lysholm score and lesser instability.
  
  
  CONCLUSIONS
  Bone tunnel enlargement of the femoral or tibial side was observed in half of patients (6 in both sides, 5 only in the femur, and 4 only in the tibia) after ACL reconstruction was performed with a hamstring tendon fixed with an RCI screw. Female patients had a greater chance for enlargement of the femoral tunnel than did males. This enlargement had no significant impact on patient activity and on anterior instability of the knee 1 year after surgery.
  
  
  METHODS
  Level IV, Therapeutic case series.
authors.affiliation: Department of Orthopaedic Surgery, Faculty of Medicine, Kyoto University, Kyoto, Japan. masakoba@kuhp.kyoto-u.ac.jp
authors.forename: Masahiko
authors.initials: M
authors.lastname: Kobayashi
authors.forename: Yasuaki
authors.initials: Y
authors.lastname: Nakagawa
authors.forename: Takashi
authors.initials: T
authors.lastname: Suzuki
authors.forename: Shuzo
authors.initials: S
authors.lastname: Okudaira
authors.forename: Takashi
authors.initials: T
authors.lastname: Nakamura
mesh_terms: D000293:Adolescent; D000328:Adult; D016118:Anterior Cruciate Ligament / Q000601:surgery*; D001182:Arthroscopy / Q000379:methods*; D001863:Bone Screws; D015331:Cohort Studies; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000601:surgery*; D005500:Follow-Up Studies; D006801:Humans; D007593:Joint Instability / Q000209:etiology; D007719:Knee Joint / Q000601:surgery; D008297:Male; D008592:Menisci, Tibial / Q000601:surgery; D008875:Middle Aged; D011183:Postoperative Complications / Q000209:etiology; D011184:Postoperative Period; D011859:Radiography; D016059:Range of Motion, Articular; D012189:Retrospective Studies; D017792:Surgical Stapling; D013710:Tendons / Q000637:transplantation*; D013977:Tibia / Q000000981:diagnostic imaging / Q000601:surgery*; D014182:Transplantation, Autologous; D016896:Treatment Outcome