Abstract
Background:
Custom cutting guides (CCG) in total knee arthroplasty (TKA) use preoperative 3-dimensional imaging to fabricate cutting blocks specific to a patient's native anatomy. To date, small cohorts and short follow-up have limited reports studying clinical and functional outcomes of CCGs versus standard intramedullary and extramedullary alignment instrumentation. The purpose of this study was to determine if CCGs improve clinical outcomes versus standard alignment guides following TKA at a mean of 2 years postoperatively.
Methods:
This was a prospective cohort study of a consecutive series of patients undergoing primary TKA using the same cruciate-retaining, cemented system between January 2009 and April 2012. Exclusion criteria were patients with prior open knee surgery, a flexion contracture of greater than 20 degrees, a distal femoral or proximal tibial defect requiring a metal or allograft augment, the use of either femoral or tibial stem extensions, or a contraindication to obtaining a magnetic resonance imaging (MRI) scan. All patients were offered the option of receiving a preoperative MRI and TKA with CCGs, and each patient self-selected for either the CCG or standard cohort. The first 95 patients that selected CCGs were compared with the first 95 that were performed with standard instrumentation. The alignment goal for all TKAs was a hip-knee-ankle (HKA) angle of 0 degrees with the femoral and tibial components aligned perpendicular to the mechanical axis. University of California at Los Angeles (UCLA), Short Form-12 (SF-12), and Oxford Knee scores were collected preoperatively. These scores, along with the Forgotten Joint score and a questionnaire assessing patient satisfaction and residual symptoms, were administered at most recent follow-up. Postoperative, rotationally controlled coronal scout CT scans were used to measure the overall hip-knee-ankle (HKA) alignment. Perioperative complications occurring within 6 months of the index procedure were reviewed. Independent samples t-tests and Chi-square tests were used, with a p-value <0.05 considered significant.
Results:
95 patients in the standard (mean follow-up 2.5 ± 1.1 years) and 95 patients in the CCG (mean follow-up 2.2 ± 1.0 years) cohorts were analyzed. There was no difference in mean age (p=0.48), BMI (p=0.19), mean tourniquet time (59.1 ± 13.2 minutes in CCG v 59.7 ± 14.7 minutes in standard; p=0.75) or percentage of outliers for HKA alignment (23% in standard versus 31% in CCG with HKA outside of 0 ± 3 degrees; p=0.2) between the two cohorts. However, CCG patients did have increased UCLA (p=0.03), SF-12 physical (p=0.001) and Oxford knee scores (p=0.001) preoperatively. At the most recent follow-up, no differences were present for range of motion, UCLA, SF-12, Oxford Knee, or Forgotten Joint scores between the two cohorts (p=0.09 v 0.76). In addition, no differences were present for the incremental improvement in these scores from preoperatively to postoperatively (p=0.1 v 0.9). Patient satisfaction and the presence of residual symptoms were similar (p=0.1 v 0.8), with only 66.3% of standard patients and 67.6% of CCG patients noting their knee to feel “normal” or comparable to their nonoperative knee (p=0.7). After excluding 5 superficial wound complications in the standard cohort caused by use of a subcutaneous braided suture, no differences in overall or knee related complications were appreciated between the two cohorts (p=0.5 v 0.65).
Conclusions:
At a mean follow-up of greater than 2 years, CCGs fail to demonstrate any advantages in clinical outcomes versus the use of standard instrumentation in TKA. The clinical benefit of CCGs must be proven prior to continued implementation of this technology.
