1. Patient Specific Instruments for primary TKA
Dr (Prof) Raju Vaishya
MS, MCh Orth (L’Pool), FRCS (England)
Sr Consultant Orthopaedic surgeon
Indraprastha Apollo Hospitals, N Delhi

2. Goals of Total Knee Arthroplasty
Accurate mechanical axial alignment.
Symmetric tension on ligaments in flexion and extension.
Equalization of flexion and extension gaps.

3. Traditional technique: I/M femoral guide and E/M tibial guide.
TECHNIQUES OF TKA
Traditional technique:
I/M femoral guide and E/M tibial guide.
Computer assisted system:
Intra operative planning.
Patient specific instruments:
Pre operative planning.

4. Advances in TKA
Computer navigation – although considered GOLD STANDARD due to better alignment, but had potential disadvantages of –
- significant capital outlay
- additional preoperative set up
- cumbersome in the operating
room, taking up substantial floor
space

5. Customized jigs A new and innovative technology.
Improves alignment and sizing of the joint by using computer-generated images of the patient’s anatomy to determine precise bone cuts, and implant positioning during the surgery.

6. Technique for jig manufacturing
MRI based - better suited for soft tissue. Segmentation process performed on surface of articular cartilage.
CT based - better suited for imaging of hard tissue. Segmentation process performed on sub chondral surface creating an image of bone.

7. Step 5: Pre Op Plan Approval Step 4: Pre Op Plan Preparation
Step 3: Segmentation
Step 1: Examination
Step 2: Scan
Step 6: Jig Designing
Step 5: Pre Op Plan Approval
Step 4: Pre Op Plan Preparation
Step 9: Surgery
Step 7: Manufacturing
Step 8: Shipping

8. Custom fitting blocks
Femoral PSI Jig
Tibial PSI Jig

9. HOW IS PSI DIFFERENT..?
Less invasive: No use of intramedullary femoral alignment guide.
Less operative time: Many steps are by passed.
Human error is minimised: Patient specific blocks used for pin position.
Intra operative complications avoided: Pre operative planning.

10. Postoperative mechanical alignment
Noble et al : Mechanical alignment in patient operated using PSI compared to conventional technique was statistically closer to neutral zero (2.8° vs. 1.7°)
Ng et al. : Observed a lower rate of rate of outliers ±3° from neutral with PSI in comparison with conventional (14.4 % vs %, respectively).
(J Arthroplasty. 27(1):153–155; 2012)
(Clin Orthop Relat Res.470(1):99–107; 2012)

11. OPERATING TIME
PSI cuts down approximately 1/3rd steps in comparison to TKA with conventional technique.
Also patient specific blocks make alignment easy and fast.
It is therefore expected to decrease some operative time with PSI.

12. Advantages of custom jigs – OR efficiency
David R. Lionberger et al
The PSI cases were 1.45 times more profitable than CAS allowing for approximately 3 PSI cases versus 2 CAS cases in one 8 hour OR day. Results from this series show that PSI improves OR efficiency.
Patient Specific Instrumentation 
Journal of Arthroplasty, ahead of print, March 2014.

13. BLOOD LOSS Femoral intra medullary invasion is avoided with PSI.
Also the operating time is decreased with PSI.
So the less invasive PSI technique is considered to decrease the blood loss in TKA.

14. BLOOD LOSS
Boonen B et al. : In 40 patients operated by PSI showed mean blood loss was 60 mL less with PSI compared to conventional intramedullary technique.
Chareancholvanich et al. : Not able to find any decrease in blood loss or transfusion requirement with PSCG group.
(Acta Orthop. 83(4):387–393; 2012)
(Bone Joint J. 95-B(3):354-9; 2013)

15. LENGTH OF HOSPITAL STAY
Accurate mechanical alignment ,less invasiveness , less blood loss, and less operative time all leads to early rehabilitation of patient.

16. Number of Instrument Trays
With fewer steps in PSI, number of instruments required is also decreased.
Simple and less instruments required.
Nobel et al. showed instrument trays reduced by more than 3 trays.

17. Our experience - PSI
There are a number of potential advantages like less number of opened tray, decreased sterilization time and quicker patient turnover in a high volume replacement centre.
The cost and time duration for making the custom blocks can be reduced by local manufacturing of the blocks. The cost has been brought down to $400 and delay in blocks decreased to 1 week at our centre.
Vaishya R et al. J Arthroplasty. 2014
Vaishya R et al. International Orthopaedics, (SICOT) March 2014.

18. Benefits of PSI SURGEONS:
Easy and simple technique with minimal learning curve.
More efficient surgery- less no. of instruments & trays.
Greater accuracy- pre-op determination of alignment & sizing.
Increased patient satisfaction- less traumatic surgery.

19. Benefits of PSI HOSPITAL:
Cost saving- less no. Of instruments & trays to clean & sterilize.
Inventory reduction-less no. of trays to store & maintain.
Better OR utilisation-less OR time, so more patient turn over.

20. Benefits of PSI PATIENTS:
Less invasive procedure- no violation of I/M canal.
Faster surgery- leads to less blood loss & anaesthesia use.
Faster return to routine activities- faster & more productive recovery

21. Post Bilateral TKR

23. Thank You 23