title: Impact of patellar height on unicompartment knee arthroplasty: does patella baja lead to an inferior outcome?
abstract: BACKGROUND
  Though a number of series with long-term results have been published, there is still a paucity of literature on the role of patellar height after unicompartment knee arthroplasty (UKA). The present study was conducted with a hypothesis that patella baja may lead to a poor outcome at follow-up.
  
  
  METHODS
  A retrospective review of 134 knees was performed and patellar height calculated before and after UKA by Blackburne-Peel index (BPI) and the Insall-Salvati ratio (ISR) on true lateral radiographs of the patients in 30° of flexion taken pre-operatively and at 1 year, 2 years and final follow-up (minimum 5 years). Statistical analysis was performed to evaluate the outcomes.
  
  
  RESULTS
  There was a decrease in ISR in 14.18 % and in BPI in 19.4 % at final follow-up. There was a significant decrease in BPI values while the decrease was not significant for ISR. After eliminating the pre-operative patella baja, 7.3 % developed post-operative patella baja, according to ISR, while 11.5 % developed patella baja as per BPI. At final follow-up there was a statistically significant decrease in stair climbing scores in patients with patella baja when compared to patients with normal ISR.
  
  
  CONCLUSIONS
  Patients with a decrease in patellar height as per ISR have a decrease in stair climbing score at mid-term follow-up while the overall KSS, and pain scores are not affected by a change in patellar height and neither is there a significant progress in patellofemoral osteoarthritis among patients with patella baja compared to normal patella.
authors.forename: Devdatta Suhas
authors.initials: DS
authors.lastname: Neogi
authors.forename: Ji Hoon
authors.initials: JH
authors.lastname: Bae
authors.forename: Chang Woo
authors.initials: CW
authors.lastname: Seok
authors.forename: Hong Chul
authors.initials: HC
authors.lastname: Lim
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects* / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000601:surgery; D007720:Knee Prosthesis / Q000009:adverse effects; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000145:classification / Q000000981:diagnostic imaging / Q000601:surgery*; D010329:Patella / Q000000981:diagnostic imaging / Q000601:surgery*; D017847:Patellar Ligament / Q000000981:diagnostic imaging / Q000601:surgery*; D020959:Polyethylene; D011475:Prosthesis Failure / Q000009:adverse effects; D011859:Radiography; D016059:Range of Motion, Articular; D012189:Retrospective Studies; D018570:Risk Assessment / Q000379:methods; D016896:Treatment Outcome
chemical_list: D020959:Polyethylene
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