Custom-made 3D printed patient specific guides (PSG) improves component axial alignment in total knee arthroplasty (TKA)

Background

Usage of Patient Specific Instrumentation (PSI) or Patient Specific Guides (PSG) in TKA has evolved rapidly in the past decade. Restoration of Mechanical axis in TKA is vital to achieve good functional outcome and long term implant survival. We carried out a comparative study to assess the efficacy of PSG in achieving neutral axial alignment and its impact on early functional outcomes compared to Conventional Instrumentation (CI).

Methods

Patients eligible as per study design (n = 100) undergoing TKA were randomized and divided in two equal groups which were matched in baseline demographics and clinical profile. All the patients in the PSG group (n = 50) and conventional instrumentation (CI) group (n = 50) underwent TKA with same implant. Pre-operative CT scans done as per specified protocol to acquire image data for 3D printing PSG. Duration of surgery and post-operative Hip-Knee-Ankle (HKA) angles achieved in the two groups was compared. Post-operative functional outcomes were assessed using WOMAC scores.

Results

There was statistically significant difference in the mean post-operative axial alignment achieved between the two groups (p = 0.041). Outliers (180 ± 3 deg) of HKA angle were more in the CI Group (p = 0.007). There was no difference in functional outcomes between the two groups at one year. Duration of surgery was significantly less in PSG Group (p < 0.001).

Conclusion

3D printed PSG are superior in achieving neutral HKA axis as compared to CI in TKA. Better axial alignment of TKA components does not correlate with better patient reported functional outcomes. PSG use significantly reduces surgical time.