Presentation at Canadian Orthopaedic Association Annual Meeting 2012 - PASTA Bridge - A New Technique in PASTA Repairs: A Biomechanical & Clinical Evaluation

1. PASTA Bridge - A New Technique in PASTA
Repairs: A Biomechanical & Clinical
Evaluation
Alan M. Hirahara, M.D., FRCS(C)
Private Practice
Sacramento, CA USA
Medical Director Team Physician Consultant
Sacramento State Athletics Sacramento River Cats Oakland A’s
MiLB - AAA

2. BIOMECHANICAL EVALUATION

3. Objective of Study
• To evaluate the biomechanical strength & clinical
effectiveness of a new PASTA repair technique – PASTA
Bridge
• To introduce a novel technique in PASTA repair that is
significantly easier, carries less risk, does not require
arthroscopic knot tying, and is as effective as current trans-
tendon techniques

4. Introduction
• In the literature, PASTA lesions can cause significant
pain for patients
• Debridement alone of tears < 50% thickness can result in
good/excellent outcomes but can progress on to full
thickness tears (6.5-34.6%)
• Current repair techniques can lead to excellent results
but are technically challenging
Romeo et al. Arthroscopy 2011; 27(4): 568-80.

5. Study Design - Biomechanical
• Case-control study
• Six matched pairs of fresh frozed cadaver
shoulders
– 3 male / 3 female
– Average age = 49 ± 12 years

6. Study Design
• For each sample, a partial tear of supraspinatus tendon was
replicated by using a sharp blade to transect 50% of the medial
side of supraspinatus from tuberosity 1 cm wide
• From each matched pair, one humerus selected to receive a PASTA
repair using one 4.5mm titanium Corkscrew FT
• Contralateral repair done using a PASTA Bridge repair
• Half of the samples of each repair were performed on the right
humeri to avoid a mechanical bias
• All repairs performed by an orthopaedic surgeon

7. Study Design
• Biomechanical testing conducted using an INSTON 8871 Axial Table Top
Servohydraulic Testing System, with a 5kN load cell attached to cross-
head
• System calibrated using FastTrack software, and load & position controls
run through WaveMaker software
• Each sample positioned on a fixed angle fixture & secured to testing
surface so direction of pull performed 45° to humeral shaft
• Custom fixture with inter-digitated brass clamps attached to cross-head,
and dry ice was used to freeze the tendon to the clamp

8. Study Design
• For each sample, we determined
– Ultimate load, yield load, and stiffness
– Cyclic displacement and strain of each sample at both
the articular margin and at the repair site
– Paired t-tests (α = 0.05) to determine if differences in
ultimate load or strain between the two repairs were
significant

9. Pasta Bridge Technique

10. PASTA Bridge: Construct Strength
Comparison Study
SutureTak and SwiveLock PASTA Repair
Ultimate Yield Stiffness Displacement (mm) Strain (mm/mm)
Donor # Side Gender Age Mode of Failure
Load (N) Load (N) (N/mm) Repair Margin Repair Margin
10-09064 R M 62 1637 1637 144 0.12 0.12 1.015 1.009 humeral head broke
10-08024 L M 27 1499 1308 136 0.52 0.21 1.056 1.014 tendon tore mid-substance
10-11021 R F 53 811 811 65 0.29 0.63 1.041 1.043 tendon tore at repair
10-09062 R F 52 899 899 61 0.63 0.44 1.177 1.048 humeral head broke
11-01032 L M 46 402 402 74 0.78 0.36 1.133 1.027 muscle body tore from tendon
10-10068 L F 53 810 660 81 0.48 0.21 1.062 1.016 muscle body tore from tendon
Average 49 1010 953 94 0.47 0.33 1.081 1.026
Standard Deviation 12 468 449 37 0.24 0.19 0.061 0.016
Titanium Corkscrew PASTA Repair
Ultimate Yield Stiffness Displacement (mm) Strain (mm/mm)
Donor # Side Gender Age Mode of Failure
Load (N) Load (N) (N/mm) Repair Margin Repair Margin
10-09064 L M 62 1398 1395 112 0.24 0.22 1.026 1.013 muscle body tore from tendon
10-08024 R M 27 1642 1642 122 0.14 0.36 1.024 1.022 tendon tore at repair
10-11021 L F 53 922 922 58 0.37 0.53 1.091 1.033 humeral head broke
10-09062 L F 52 969 969 132 0.34 0.54 1.052 1.041 tendon tore at repair
11-01032 R M 46 1003 1003 88 0.58 0.27 1.094 1.021 muscle body tore from tendon
10-10068 R F 53 575 575 82 0.27 0.49 1.050 1.034 tendon tore at repair
Average 49 1085 1084 99 0.32 0.40 1.056 1.027
Standard Deviation 12 378 378 28 0.15 0.14 0.030 0.010

11. PASTA Bridge – Methods of Failure

12. Results
• No significant difference in the two groups in
all parameters
• Mode of failure was always biological, not
mechanical

13. Discussion
• Despite using smaller anchors, we have created a
sturdy, reliable, easy, percutaneous repair
technique that is just as strong as conventional
larger suture anchor repairs
• Minimal risk of damaging shoulder during
surgery
• Proven biomechanical strength

14. CLINICAL EVALUATION

15. Study Design - Clinical
• Case-control study
• Collection period: 8/09 – 12/11
• Pain scores, ASES scores taken every month for 6
months
– ROM measured pre-op and monthly for 3 months post
– Date of discharge and date of return to work were noted

16. Study Design
• All patients requiring a PASTA repair
• Inclusions:
– PASTA lesion > 25% thickness
• Exclusions:
– any post-operative trauma
– non-compliance with physical therapy protocol
• Failure to heal:
– Evaluated any symptoms 4-6 months post-op with repeat MRA or
surgery

17. Patient Data
Study Group Control Group
• 35 patients • 26 patients
• 15 male / 20 female • 12 male / 14 female
• Age range: 22 – 80 years • Age range: 17 – 72 years
• Age average: 52.07 years • Age average: 47.75 years

18. Results
Pain Scores ASES Scores
p = NS p = NS
7.0 80.0
6.0 70.0
60.0
5.0
50.0
4.0
40.0
3.0
30.0
2.0
20.0
1.0 10.0
0.0 0.0
Pre-op 1 2 3 4 5 6 Pre-op 1 2 3 4 5 6
Month Month Month Month Month Month Month Month Month Month Month Month
 Control Group: n = 26
 Study Group: n = 35

19. Range of Motion
160.0
140.0
120.0
100.0
Control Flexion
Degrees
80.0 Study Flexion
Control ER
60.0
Study ER
40.0
20.0
0.0
Initial Visit 1 Month 2 Month 3 Month
No Significant Difference Between the 2 Groups

20. Results – Return to Work
124.0
140.0
99.8
120.0
100.0
80.0
Days
60.0
40.0
20.0
0.0
Control Group Study Group
No Significant Difference Between the 2 Groups

21. Results – Days to Discharge
p = 0.02
241.7
250.0
200.0
139.7
150.0
Days
100.0
50.0
0.0
Control Group Study Group

22. Results - Failures
p = 0.078
4
3.5
3
4/26
2.5
2
1.5
1
1/35
0.5
0
Control Group Study Group

23. Results
• No significant difference in
– VAS pain scores
– ASES scores
– Return to work
– Failures - 15.4% to 2.9%
• Significant difference in
– Days to discharge

24. Discussion
• The PASTABridge is just as effective as trans-tendon repairs but
– Easy, percutaneous technique
– Does not require any arthroscopic knot tying
– Minimal risk of damaging shoulder during surgery
– Proven biomechanical strength
• Will require a randomized controlled trial and larger sample size to
better evaluate the results

25. Extension Bridge

26. Conclusion
• The PASTA Bridge is a viable, simple
technique to repair PASTA lesions that carries
minimal risk, compared with current trans-
tendon techniques

27. THANK YOU