title: Non-anatomical capsular closure of a standard parapatellar knee arthrotomy leads to patellar maltracking and decreased range of motion: a cadaver study.
abstract: OBJECTIVE
  A parapatellar approach disrupts the medial soft tissue stabilizers of the patella. We hypothesized that soft tissue realignment during arthrotomy closure of native cadaveric knees influences patellar kinematics leading to decreased range of motion.
  
  
  METHODS
  Parapatellar arthrotomy was performed in seven native human cadaveric knees that did not contain arthroplasty components. Capsular closure was performed with figure-of-eight sutures in five different positions for each specimen. The capsule was closed anatomically, and then shifted 1.5 or 3 cm distal, or 1.5 or 3 cm proximal relative to surgical markings of the patellar poles. In each closure position, real-time patellar kinematics and range of motion were recorded using a navigation system with patellar tracking function.
  
  
  RESULTS
  Maximum knee flexion was significantly reduced with closure shifted 3 cm proximal (133° ± 8.2°, p < 0.001) or distal (139° ± 6.4°, p < 0.05) compared to anatomical closure (147° ± 4.1°). All closure positions significantly influenced patellar rotation at 45°, 90°, and 120° of flexion (p < 0.001). Closure 1.5 or 3 cm distal increased lateral patellar shift relative to the mechanical axis (p < 0.01). Patellar tilt was significantly decreased at 90° and 120° by closure 3 cm distal (p < 0.01) and at 120° when closed 1.5 cm distal (p < 0.05).
  
  
  CONCLUSIONS
  Imprecise arthrotomy closure significantly impacted patellar kinematics and passive range of motion. Therefore, every effort should be made to provide anatomical closure of the extensor mechanism to preserve native patellar movement kinematics.
  
  
  METHODS
  V.
authors: Department of Orthopaedic Surgery, Wake Forest School of Medicine, Medical Center Boulevard, Winston-Salem, NC, 27157-1070, USA, jplate@wakehealth.edu.
authors: Johannes F
authors: JF
authors: Plate
authors: Thorsten M
authors: TM
authors: Seyler
authors: Jason J
authors: JJ
authors: Halvorson
authors: Anthony C
authors: AC
authors: Santago
authors: Jason E
authors: JE
authors: Lang
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects / Q000379:methods*; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D008875:Middle Aged; D010329:Patella / Q000503:physiopathology* / Q000601:surgery; D057071:Patellofemoral Joint / Q000503:physiopathology* / Q000601:surgery; D016059:Range of Motion, Articular; D012399:Rotation; D013536:Suture Techniques