title: Algorithmic pie-crusting of the medial collateral ligament guided by sensing technology affects the use of constrained inserts during total knee arthroplasty.
abstract: Intra-operative sensing technology is an alternative to standard techniques in total knee arthroplasty (TKA) for determining balance by providing quantitative analysis of loads and point of contact throughout a range of motion. We used intra-operative sensing (VERASENSE-OrthoSensor, Inc.) to examine pie-crusting release of the medial collateral ligament in knees with varus deformity (study group) in comparison to a control group where balance was obtained using a classic release technique and assessed using laminar spreaders, spacer blocks, manual stress, and a ruler.
  
  
  
  The surgery was performed by a single surgeon utilizing measured resection and posterior-stabilized, cemented implants. Seventy-five study TKAs were matched 1:3 with 225 control TKAs. Outcome variables included the use of a constrained insert, functional- and knee-specific Knee Society score (KSS) at six weeks, four months, and one year post-operatively. Outcomes were analyzed in a multivariate model controlling for age, sex, BMI, and severity of deformity.
  
  
  
  The use of a constrained insert was significantly lower in the study group (5.3 vs. 13.8%; p = 0.049). The use of increased constraint was not significant between groups with increasing deformity. There was no difference in functional KSS and knee-specific KSS between groups at any follow-up interval.
  
  
  
  An algorithmic pie-crusting technique guided by intra-operative sensing is associated with decreased use of constrained inserts in TKA patients with a pre-operative varus deformity. This may cause a positive shift in value and cost savings.
authors.affiliation: Hospital for Special Surgery, 535 East 70th Street, New York, NY, 10021, USA.
authors.forename: Spencer
authors.initials: S
authors.lastname: Amundsen
authors.affiliation: Hospital for Special Surgery, 535 East 70th Street, New York, NY, 10021, USA.
authors.forename: Yuo-Yu
authors.initials: YY
authors.lastname: Lee
authors.affiliation: Hospital for Special Surgery, 535 East 70th Street, New York, NY, 10021, USA. gonzaleza@hss.edu.
authors.forename: Alejandro
authors.initials: A
authors.lastname: González Della Valle
mesh_terms: D000368:Aged; D000465:Algorithms; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D005260:Female; D056305:Genu Varum / Q000150:complications / Q000601:surgery*; D006801:Humans; D007719:Knee Joint / Q000601:surgery; D007720:Knee Prosthesis / Q000009:adverse effects*; D008297:Male; D017888:Medial Collateral Ligament, Knee / Q000601:surgery*; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000150:complications / Q000601:surgery*; D011184:Postoperative Period; D016059:Range of Motion, Articular; D012189:Retrospective Studies
keywords: Intraoperative sensing technology; Ligament balance; Pie crusting; Total knee arthroplasty; Varus deformity