Abstract
Hypothesis
Custom cutting blocks can produce similar alignment compared to computer navigated and conventional total knee arthroplasty (TKA) techniques.
Method
We conducted a retrospective review of 37 patients who underwent TKA by a single surgeon in a teaching hospital setting. Groups were conventional method (10), computer assisted navigation (10), and custom blocks (18). The custom group was further subdivided to CT and MRI based blocks. Post-operative alignment was measured (blinded) using full length weight bearing radiographs at 18 weeks on average. Hospital records were reviewed to determine operative time, transfusion requirements, length of hospital stay, complications and cost.
Results
Post-operative mechanical axis was within 3 degrees of neutral in 100% of the navigation group, 70% of the conventional group and 50% of the custom block group. Average alignment was within 1.8, 3.1 and 3.6 degrees of neutral for each group respectively. The operative time was greater for the computer navigation group (86.7 min) compared to the conventional (72.1) and MRI custom block groups which involved unfamiliar instrumentation (73.8). CT based block procedures involved otherwise familiar instruments and averaged 61.2 minutes. Length of hospital stay and complications were similar for all three groups. Total cost was the least for the conventional group. Increased costs were associated with computer equipment, pre-operative advanced imaging and custom blocks.
Conclusions
Custom cutting blocks in this small series obtain worse radiographic positioning of total knee arthroplasty components compared to conventional and computer navigation techniques. Further studies with greater number of patients, CT alignment analysis and long-term follow-up are required.
