title: Comparison of quadriceps-sparing minimally invasive and medial parapatellar total knee arthroplasty: a 2-year follow-up study.
abstract: OBJECTIVE
  Quadriceps-sparing minimally invasive total knee arthroplasty (TKA) has been proposed to limit surgical dissection without compromising surgical outcome. We conducted a prospective and randomized study to compare the outcomes of patients who underwent quadriceps-sparing TKA with the outcomes of those who underwent standard medial parapatellar TKA, after a 2-year follow-up period.
  
  
  METHODS
  Eighty primary TKA procedures that were to be performed in 60 osteoarthritis patients were randomly assigned to either a quadriceps-sparing (40 knees) or a standard medial parapatellar (40 knees) group. All surgeries were designed to set the prosthesis with a femoral component alignment of 7° valgus and a tibial component alignment that was perpendicular to the tibial shaft. Surgical time and tourniquet time were recorded. Outcome variables included knee function, as defined by a hospital for special surgery knee score; quadriceps muscle strength, which was measured by an isokinetic dynamometer; pain, as indicated on a visual analog scale; prosthetic position, which was measured on plain radiograph; and range of motion.
  
  
  RESULTS
  Patients who underwent the 38 quadriceps-sparing and 37 standard TKA procedures completed the 2-year follow-up period without any infection or revision. The mean surgical time and tourniquet time were significantly longer in the quadriceps-sparing group. The mean peak quadriceps muscle strength, hamstring muscle strength, normalized muscle balance (hamstring/quadriceps ratio), pain score, function score, and range of motion were comparable in both groups at 2 months and 2 years. In the quadriceps-sparing group, both the femoral and the tibial components were significantly more varus-deviated from the expected position.
  
  
  CONCLUSIONS
  Patients undergoing quadriceps-sparing and standard medial parapatellar TKA had comparable outcomes for quadriceps muscle strength, hamstring-quadriceps balance, and knee function; however, the quadriceps-sparing TKA was more time consuming surgically and resulted in a less accurate prosthesis position.
authors.affiliation: Department of Orthopaedic Surgery, National Taiwan University Hospital, Taipei, Taiwan.
authors.forename: Hongsen
authors.initials: H
authors.lastname: Chiang
authors.forename: Chung-Chien
authors.initials: CC
authors.lastname: Lee
authors.forename: Wei-Peng
authors.initials: WP
authors.lastname: Lin
authors.forename: Ching-Chuan
authors.initials: CC
authors.lastname: Jiang
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007719:Knee Joint / Q000502:physiology; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength; D061646:Operative Time; D059351:Organ Sparing Treatments; D010149:Postoperative Pain / Q000209:etiology; D052097:Quadriceps Muscle / Q000502:physiology / Q000601:surgery*; D016059:Range of Motion, Articular