title: Extensor mechanism allograft reconstruction for extensor mechanism failure following total knee arthroplasty.
abstract: BACKGROUND
  Extensor mechanism disruption following total knee arthroplasty is a rare but devastating complication. The purpose of this study was to report our experience with extensor mechanism allograft reconstruction for chronic extensor mechanism failure.
  
  
  METHODS
  Fifty consecutive extensor mechanism allograft reconstructions were performed in forty-seven patients with a mean age of 67.6 years who were followed for a mean time of 57.6 months (range, twenty-four to 125 months). The operative technique included the use of a fresh-frozen, correctly sized full extensor mechanism allograft that was tensioned tightly in full extension. Patients were evaluated clinically with use of the Knee Society score, and reconstructions were considered failures if the patient had a score of <60 points or a recurrent extensor lag of >30° or if they required revision or removal of the allograft.
  
  
  RESULTS
  Nineteen reconstructions (38%) were considered failures, including four revised to a second extensor mechanism allograft due to failure of the allograft, five for deep infection, and ten considered clinical failures secondary to a Knee Society score of <60 points or an extensor lag of >30°. The mean Knee Society score improved from 33.9 to 75.9 points (p<0.0001). The estimated Kaplan-Meier survivorship with failure for any reason as the end point was 56.2% (95% confidence interval, 39.4% to 70.1%) at ten years.
  
  
  CONCLUSIONS
  Extensor mechanism disruption following total knee arthroplasty is a difficult complication to treat, with modest outcomes. Extensor mechanism allograft reconstruction is a reasonable option; however, patients must be informed regarding the substantial risk of complications, and although initial extensor mechanism function may be restored, expectations regarding longer-term outcomes are more guarded.
authors.affiliation: Rush University Medical Center, 1611 West Harrison Street, Suite 300, Chicago, IL 60612. E-mail address for C.J. Della Valle: craigdv@yahoo.com.
authors.forename: Nicholas M
authors.initials: NM
authors.lastname: Brown
authors.affiliation: Department of Orthopaedic Surgery, Cleveland Clinic, 9500 Euclid Avenue, A41, Cleveland, OH 44195.
authors.forename: Trevor
authors.initials: T
authors.lastname: Murray
authors.affiliation: Rush University Medical Center, 1611 West Harrison Street, Suite 300, Chicago, IL 60612. E-mail address for C.J. Della Valle: craigdv@yahoo.com.
authors.forename: Scott M
authors.initials: SM
authors.lastname: Sporer
authors.affiliation: Rush University Medical Center, 1611 West Harrison Street, Suite 300, Chicago, IL 60612. E-mail address for C.J. Della Valle: craigdv@yahoo.com.
authors.forename: Nathan
authors.initials: N
authors.lastname: Wetters
authors.affiliation: Rush University Medical Center, 1611 West Harrison Street, Suite 300, Chicago, IL 60612. E-mail address for C.J. Della Valle: craigdv@yahoo.com.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Berger
authors.affiliation: Rush University Medical Center, 1611 West Harrison Street, Suite 300, Chicago, IL 60612. E-mail address for C.J. Della Valle: craigdv@yahoo.com.
authors.forename: Craig J
authors.initials: CJ
authors.lastname: Della Valle
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D064591:Allografts / Q000601:surgery*; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D001696:Biomechanical Phenomena; D005500:Follow-Up Studies; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008875:Middle Aged; D010329:Patella / Q000601:surgery; D017847:Patellar Ligament / Q000601:surgery; D011859:Radiography; D016059:Range of Motion, Articular; D019651:Plastic Surgery Procedures / Q000379:methods*; D013977:Tibia / Q000601:surgery; D016896:Treatment Outcome