title: 3D Computed Tomography Evaluation of Morphological Changes in the Femoral Tunnel After Medial Patellofemoral Ligament Reconstruction With Hamstring Tendon Graft for Recurrent Patellar Dislocation.
abstract: BACKGROUND
  Reconstruction of the medial patellofemoral ligament (MPFL) for recurrent lateral patellar dislocation is gaining popularity. However, the morphological changes in the femoral tunnel after MPFL reconstruction are still not fully documented.
  
  
  OBJECTIVE
  This study used 3-dimensional (3D) computed tomography to evaluate morphological changes in the femoral tunnel after MPFL reconstruction with hamstring tendon graft to investigate factors affecting the phenomenon and to elucidate whether it is associated with clinical outcomes.
  
  
  METHODS
  Case series; Level of evidence, 4.
  
  
  METHODS
  Twenty-three patients with recurrent patellar dislocation were prospectively enrolled in this study. The patients included 6 males and 17 females with a mean age of 24 years (range, 14-53). The MPFL was reconstructed by creating 2 patellar bone sockets and 1 femoral bone socket anatomically under X-ray control, and the semitendinosus autograft was fixed with cortical suspension devices. Computed tomography scans obtained 3 weeks and 1 year after surgery were reconstructed into 3D constructs with a volume analyzer. Cross-sectional areas (CSAs) of the aperture and inside the femoral tunnel were compared between the 2 time points. Likewise, the location of tunnel walls and center of the femoral tunnel footprint were evaluated. Relationships were assessed between femoral tunnel morphological changes and potential risk factors-such as age, body mass index, sex, femoral tunnel positioning, patellar height, sulcus angle, congruence angle, lateral tilt angle, degree of trochlear dysplasia, lateral deviation of the tibial tubercle, and Kujala score.
  
  
  RESULTS
  No patient reported recurrence of patellar dislocation during the follow-up period. The CSA of the femoral tunnel aperture enlarged by 41.1% ± 34.7% ( P < .01). The center, anterior border, and proximal border of the femoral tunnel significantly shifted in the anterior direction ( P < .01). The distal border significantly shifted in both anterior and distal directions ( P < .01). Patella alta was associated with distal migration of the tunnel center ( P < .05). Morphological changes were not associated with other risk factors or Kujala score.
  
  
  CONCLUSIONS
  The CSA of the femoral tunnel aperture enlarged, and the tunnel aperture migrated anteriorly with time after MPFL reconstruction. Risk factors for patellar dislocation other than patella alta did not influence morphological changes of the femoral tunnel.
authors.affiliation: Department of Sports Orthopaedics, Osaka Rosai Hospital, Sakai, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Kita
authors.affiliation: Department of Sports Orthopaedics, Osaka Rosai Hospital, Sakai, Japan.
authors.forename: Yoshinari
authors.initials: Y
authors.lastname: Tanaka
authors.affiliation: Department of Sports Orthopaedics, Kansai Rosai Hospital, Amagasaki, Japan.
authors.forename: Yukiyoshi
authors.initials: Y
authors.lastname: Toritsuka
authors.affiliation: Department of Sports Orthopaedics, Osaka Rosai Hospital, Sakai, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Amano
authors.affiliation: Department of Sports Orthopaedics, Seihu Hospital, Sakai, Japan.
authors.forename: Ryohei
authors.initials: R
authors.lastname: Uchida
authors.affiliation: Department of Sports Orthopaedics, Seihu Hospital, Sakai, Japan.
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Shiozaki
authors.affiliation: Faculty of Comprehensive Rehabilitation, Osaka Prefecture University, Habikino, Japan.
authors.forename: Rikio
authors.initials: R
authors.lastname: Takao
authors.affiliation: Faculty of Comprehensive Rehabilitation, Osaka Prefecture University, Habikino, Japan.
authors.forename: Shuji
authors.initials: S
authors.lastname: Horibe
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery*; D000070632:Hamstring Tendons / Q000637:transplantation*; D006801:Humans; D021621:Imaging, Three-Dimensional; D008023:Ligaments, Articular / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D031222:Patellar Dislocation / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery*; D057071:Patellofemoral Joint / Q000000981:diagnostic imaging* / Q000601:surgery*; D012008:Recurrence; D013848:Thigh; D013977:Tibia / Q000601:surgery; D014057:Tomography, X-Ray Computed; D014182:Transplantation, Autologous; D055815:Young Adult
keywords: MPFL reconstruction; clinical outcome; femoral tunnel enlargement; risk factors