title: Patient-specific instrumentation versus conventional instrumentation in total knee arthroplasty.
abstract: To compare patient-specific instrumentation (PSI) with conventional instrumentation in total knee arthroplasty (TKA) in terms of component alignment, operating time, and the learning curve required in a non-teaching hospital.
  
  
  
  Records of 33 men and 29 women aged 50 to 88 (mean, 71) years who underwent TKA for osteoarthritis using PSI (n=31) or conventional instrumentation (n=31) by a single surgeon were reviewed. The choice of instrumentation was made by the patient; the surgeon did not express any preference and had not used PSI before. All patients used the same cemented, cruciate-retaining system.
  
  
  
  The PSI and conventional instrumentation groups were comparable in terms of age, body mass index (BMI), American Society of Anesthesiologists grade, pre- and post-operative haemoglobin level, and the need for blood transfusion. Compared with conventional instrumentation, PSI resulted in a smaller coronal femoral component angle (7.7º vs. 6.4º, p=0.003) and posterior tibial slope angle (6.4º vs. 3.2º, p=0.0001), and smaller variance of the respective angles (p=0.006 and p=0.003). In patients with a BMI ≥30, PSI still resulted in a smaller posterior tibial slope angle (5.8º vs. 3.1º, p=0.015) and variance of the angle (p=0.02). The mean tourniquet time was shorter in the PSI group in all patients (p=0.013) and in patients with BMI ≥30 kg/m2 (p=0.0008), and its variance was also smaller in the PSI group (p=0.0004). There was no learning curve required.
  
  
  
  PSI was simple to use, with no learning curve required. It can be used in non-teaching hospitals and in patients with a high BMI and in cases where the use of an intramedullary alignment guide would be problematic due to previous femoral trauma.
authors: Department of Trauma and Orthopaedics, Colchester Hospital University NHS Foundation Trust, Colchester, United Kingdom.
authors: W Cw
authors: WC
authors: Chan
authors: E
authors: E
authors: Pinder
authors: M
authors: M
authors: Loeffler
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation*; D006801:Humans; D007720:Knee Prosthesis; D059032:Learning Curve; D008297:Male; D008875:Middle Aged; D061646:Operative Time; D020370:Osteoarthritis, Knee / Q000601:surgery*; D011474:Prosthesis Design; D017755:Prosthesis Fitting; D012189:Retrospective Studies; D016896:Treatment Outcome
keywords: arthroplasty, replacement, knee; instrumentation; learning curve