Summary

PSI is better in terms of achieving neutral mechanical alignment much more consistently than conventional instrumentation.

Abstract

Background

The primary objective of this randomised control study was to compare the surgical aspects,
radiological parameters and clinical outcomes of total knee joint arthroplasty performed with patient specific
instrumentation and compare it with surgeries done using conventional instruments.

Methods

A total of 100 patients were randomly enrolled into the study and divided into two groups each. All
patients underwent unilateral total knee arthroplasty. One group numbering 50 underwent surgery using Patient
Specific Instruments(PSI Group) and the other group comprising 50 patients underwent surgery with conventional

Methods

(CI Group). Each patient in the PSI Group underwent CT Scan of the knee to be operated for fabrication
of Cutting Guides. All patients underwent weight bearing full length lower limb x-rays before and after surgery
in order to measure and compare mechanical alignment that is Hip-Knee-Ankle (HKA) angles. All surgeries were
performed using Stryker Scorpio° NRG PS design implants. Blood loss and time of surgery between the two
groups were measured intra-operatively. Functional outcomes were measured using The Western Ontario and
McMaster Universities Osteoarthritis Index (WOMAC) scoring system at 6 weeks and 6 months.

Results

There was statistically significant difference in the mean post-operative mechanical alignment achieved
between the two groups (p=0.041). Moreover, the percentage of Outliers (defined as HKA angle of more or less
than 180±3°) was significantly much more in the CI Group (p=0.007). Amount of blood loss during surgery was
significantly less in PSI Group as compared to the other as was the duration of surgery(p<0.001). The technique
demonstrated a very high degree of accuracy as far as predictability of implant size is concerned. However, no
statistically significant difference in functional outcomes was found between the two groups.

Conclusion

PSI is better in terms of achieving neutral mechanical alignment much more consistently than
conventional instrumentation. The technique provides additional advantages of lesser blood loss, decreases
surgical time and improves predictability of implant sizes. The technique has no impact on clinical outcomes at
least in the short term