Tunnel Enlargement in Single Bundle ACL Reconstruction Using Bio-Interference Screw, Transfix and Tight Rope RT: A Comparitive Study Using Computed Tomography-Dr. Ankit Goyal

1. Tunnel Enlargement in Single Bundle ACL
Reconstruction using Bio Interference Screw,
Transfix And Tight Rope RT – A comparative
study using computed tomography
Dr. Ankit Goyal
Assistant Professor
Sports Injury Centre
Safdarjung Hospital
Delhi
Indian Arthroscopy Society,2014, Hyderabad

2. Introduction
Tunnel widening after ACL reconstruction is
a well known phenomenon. Extent to which
tunnel widens with different fixation
methods though is a matter of debate.

3. Discussion- Why this study??
*Tunnel enlargement in the revision setting
represents a difficult technical challenge
with possible compromise of graft
placement, fixation, and graft incorporation
 First study in our knowledge
comparing the tunnel dilatation of
TIGHTROPE RT with other graft
fixation devices.

4.  The purpose of this Prospective study was to
determine the influence of three different fixation
methods on the femoral tunnel widening and their
effect on the clinical outcomes after ACL
reconstruction using hamstring grafts.

5. Etiology- Multifactorial ???
Mechanical factors
 Motion of the graft within the tunnel*
 “Bungee- Cord effect”
 “ Windshield Wiper Effect”
 “Creep” of Graft tissue leading to
elongation
Hoher J, Moller HD, Fu FH. Bone Tunnel enlargement after Anterior Cruciate ligament reconstruction: fact or
Fiction? Knee Surg Sports Traumatol Arthrosc 1998;6:231-240.
Rodeo et al. Tendon healing in a bone tunnel differs at the tunnel entrance versus tunnel exit; an effect of graft
tunnel motion? Am J Sports Med 2006;34:1790-1800
Martin et al. Orthop Clin North Am. 2002;33:685-696

6. Etiology-
Multifactorial ???
Fixation methods/devices
*Suspensory graft fixation results in more elastic graft
construct and may contribute to the so called Bungee effect
, which has been suggested to contribute to tunnel widening.
*Wilson et al. Tunnel enlargement after anterior cruciate ligament surgery. Am J Sports Med 2004;32:543-549.
**Some authors believed that graft tunnel motion was due to the non
articular fixation, but when fixation changed to the articular surface ,
the enlargement did not reduced either.
**Koboyashi etal. A retrospective review of bone tunnel enlargement after ACL reconstruction with hamstring
tendons fixed with a metal round cannulated interference screw . Arthroscopy 2006;22:1093-1099.

7.  Improper graft placement*
Non- Anatomical
Anantomical
*
Etiology- Multifactorial ???
Segawa et al. Bone tunnel enlargement after ACL reconstruction using hamstring tendons. Knee Surg Sports Traumatol
Arthrosc 2001;9:206-210.
*Garofalo et al. Femoral tunnel placement in ACL reconstruction: Rationale of the two incision technique. J orthop Surg Res
2007; 2:10.
*Jepsen et al. Does the position of the femoral tunnel affect the laxity or clinical outcome of ACL reconstructed knee? A
clinical, prosp randomized study. Arthroscopy 2007;23: 1326-1333

8. Etiology-
Multifactorial ???
 Redirecting Forces at the tunnel entrance
 Accelerated rehabilitation
Paesseler et al . The effect of different rehabilitation protocols on Tibial
tunnel widening after ACL reconstruction with hamstrings. 2001. ISAKOS
Congress, Montreaux, Switzerland

9. Etiology- Multifactorial ???
Biological factors –
 Synovial fluid propagation within the tunnels
 Increased cytokine levels.
 Graft swelling – in case of allograft tissue
Fink C etal. Tibial tunnel enlargement following anterior cruciate ligament reconstruction with patellar tendon
autograft.Arthroscopy2001;17:138-143.
Hoher J, et al.Bone tunnel enlargement after anterior cruciate ligament reconstruction: Fact or fiction. Knee Surg Sports Traumatol
Arthrosc 1998;6:231-240.
Insalata et al. Tunnel expansion following anterior cruciate ligament reconstruction: A comparison of hamstring and patellar tendon
autografts. Knee Surg Sports Traumatol Arthrosc 1997;5:234-238.

10. Timing of the Tunnel enlargement
Authors Timing of tunnel
enlargement
Journal
Dyer and Elrod Tunnel widening occurs in
the first 6 months
Tunnel widening in ACL reconstruction: A
prospective evaluation of hamstring and
patellar tendon grafts. Knee Surg Sports
Traumatol Arthrosc 1999;7:138-145.
Peyrache et al. Tunnel widening occurs
early and stabilizes in the
first year
Tibial tunnel enlargement after ACL
reconstruction by autogenous bone
patellar tendon-bone grafts. Knee Surg
Sports Traumatol Arthrosc. 1996;11:353-
54
Fink et al. Greatest amount of tunnel
widening occurs within the
first 6 weeks
Tibial tunnel enlargement following ACL
reconstruction with a patellar tendon
autograft. Arthroscopy 2001;17:138-43.

11. Material and methods
 48 patients (January 2008 and March 2012)
16 Patients
Bio interference
Transfix
16 Patients
Bio interference
Tightrope RT
16 Patients
Bio interference
Bio interference

12. Selection Criteria
Inclusion Criteria
1. Age 20-40 years
2. Unilateral ACL rupture with or without meniscal tear
diagnosed clinically as well as by Magnetic resonance imaging
3. Time interval between ACL injury and reconstruction of 6
weeks to 2 years
4. Normal contralateral knee
Exclusion criteria
1. Meniscal tear requiring repair
2. Multiligamentous injury

13. Material and methods
The three groups were matched for
age, sex and duration since injury.
*Tunnel measurements were done on
CT scan at 2 weeks, 6 months and 1
year.
Diameter of tunnels was measured at
aperture(A), widest part of tunnel(B)
and just below suspension points in
Group 1 and 2 and at the tip of
Bioscrew(C) in both the Oblique
sagittal and Oblique Coronal
Sections.
All the three groups had similar
rehabilitation protocol.
*Marchant et al. Comparison of plain radiography, Computed tomography and magnetic resonance imaging in the
evaluation of bone tunnel widening after ACL reconstruction. Knee Surg Sports Traumatol Arthrosc 2010;18(8);1059-
1064

14. Material and methods
Results were evaluated on two fronts:
1. Femoral tunnel enlargement using CT and
comparing them with each group.
2. Clinical outcome was assessed with KT-1000
Arthrometer, International Knee documentation
Committee (IKDC) and Lysholm score.

15. Statistical analysis
 The unpaired t test was used to analyze the difference of
means for tunnel dilatations. The test was referenced for
2-tailed P values for its significance, and P < .05 was
assumed to be statistically significant.
 The Wilcoxon signed-rank test was performed to
statistically evaluate the significance of clinical outcome by
Lysholm and IKDC 2000 Subjective Knee Evaluation scores
for all groups. The resulting P < .05 was accepted as a
statistically significant difference in the median of paired
observations.

16. Results
 Maximum tunnel dilatation was at aperture (Point A) in Transfix and
Tightrope group while it was at Midway (Point B) for Bio interference
group.
 There was no statistical significant difference in the femoral
widening among the three groups.
 There was no statistically significant difference between the three
groups on KT 1000 side to side measurement, International Knee
Documentation Committee (IKDC) and Lysholm score.

17. RESULTS Sagittal Section Coronal Section
Femoral
Widening
6
Months
1
year
P
Value
6
Months
1 Year P
Value
Aperture
Transfix 35.2% 62.3% .019 33.4% 68.3% .41
Tight rope RT 38.1% 63.2% .015 37.4% 66.8% .35
Bioscrew 31.2% 58.5% .017 32.5% 63.2% .27
Midway
Transfix 33.2% 60.9% .012 31.2% 62.4% .017
Tight rope RT 35.1% 60.6% .023 34.6% 64.3% .245
Bioscrew 33.5% 67.2% .26 34.2% 68.2% .321
Suspension Point
Transfix 15.1% 32.8% .712 18.4% 33.7% .813
Tight rope RT 16.5% 31.4% .45 19.3% 37.4% .67
Bioscrew 14.2% 30.5% .19 15.5% 32.4% .54

18. 70
60
50
40
30
20
10
0
6 Months 12 Months
Transfix
Tight Rope RT
Bioscrew
SAGITTAL SECTION
APERTURE ( POINT A)
Percentage (%) 

19. 80
70
60
50
40
30
20
10
0
6 Months 12 Months
Transfix
Tight Rope RT
Bioscrew
CORONAL SECTION
APERTURE POINT(A)
Percentage (%) 

20. 80
70
60
50
40
30
20
10
0
6 Months 12 Months
Transfix
Tight Rope RT
Bioscrew
SAGITTAL SECTION
MIDWAY POINT(B)
Percentage (%) 

21. 80
70
60
50
40
30
20
10
0
6 Months 12 Months
Transfix
Tight Rope RT
Bioscrew
CORONAL SECTION
MIDWAY POINT(B)
Percentage (%) 

22. 35
30
25
20
15
10
5
0
6 Months 12 Months
Transfix
Tight Rope RT
Bioscrew
SAGITTAL SECTION
SUSPENSION-POINT ( C)
Percentege (%) 

23. 40
35
30
25
20
15
10
5
0
6 Months 12 Months
Transfix
Tight Rope RT
Bioscrew
CORONAL SECTION
SUSPENSION-POINT ( C)
Percentege (%) 

24. Results
 The IKDC 2000 Subjective Knee Evaluation score
improved by a mean of
 by 41.33 points (range, 32.53 to 56.3 4) in the Transfix
group
 37.3 points (range, 33.41 to 45.72) in the Tight rope RT
group (P <.001)
 by 40.32 points (range, 33.56 to 55.87) in Bio-interference
group.

25. Clinical scores and KT-1000 data
Group 1- Transfix
Preoperative Post-operative
6 Months
Post-operative
1 year
IKDC
Normal
0 43.7% 46.6%
Nearly Normal 0 54.1% 52.2%
Abnormal 47.6% 2,2% 1.2%
Severely Abnormal 52.4% 0 0
Lysholm 51.8+/- 12.3 93.8+/-3.4 94.9+/- 4.1
KT-1000
(side to side
difference)
3.19+/- 1.7 1.5+/-0.7 1.5+/-0.4

26. Clinical scores and KT-1000 data
Group 2- Tightrope RT
Preoperative Post-operative
6 Months
Post-operative
1 year
IKDC
Normal
0 42.7% 44.6%
Nearly Normal 0 54% 54.2%
Abnormal 45.6% 3.3% 1.2%
Severely Abnormal 54.6% 0 0
Lysholm 56.8+/- 12.3 95.6+/-3.4 96.8+/- 4.1
KT-1000 4.1 +/- 1.6 1.8+/-0.7 1.9+/-0.4

27. Clinical scores and KT-1000 data
Group 3- Aperture fixation
Pr eoperative Post-operative
6 Months
Post-operative
1 year
IKDC
Normal
0 42.7% 44.6%
Nearly Normal 0 54% 54.2%
Abnormal 45.6% 3.3% 1.2%
Severely Abnormal 54.6% 0 0
Lysholm 56.8+/- 12.3 95.6+/-3.4 96.8+/- 4.1
KT-1000 4.3 +/- 1.2 1.6+/-0.9 1.8+/-0.4

28. CT scans (Aperture Fixation)
2 Weeks
Coronal section Sagittal section

31. CT scans (transfix Fixation)
2 Weeks
Oblique Coronal Oblique sagittal

32. CT scans (transfix Fixation)
6 months
Oblique Coronal Oblique sagittal

33. CT scans (transfix Fixation)
1 year
Oblique coronal Oblique sagittal

34. CT scans (Tight rope RT Fixation)
2 weeks
Oblique Coronal Oblique sagittal

35. CT scans (Tight rope RT Fixation)
6 months
Oblique Coronal Oblique sagittal

36. CT scans (Tight rope RT Fixation)
1 year
Oblique Coronal Oblique sagittal

37. Discussion
 Tunnel enlargement was seen in Group 1 ( Transfix) because of:
i. Suspensory Fixation
ii. Non- anatomical tunnel
 Koboyashi etal. A retrospective review of bone tunnel enlargement after ACL reconstruction with hamstring
tendons fixed with a metal round cannulated interference screw . Arthroscopy 2006;22:1093-1099.
 Abebe et al. Femoral tunnel placement during ACL reconstruction. An in vivo imaging analysis comparing
transtibial and 2 incision tibial tunnel independent techniques. Am J Sports Med 2009 ;37:1904-11.
 Arnold eta. Single incion technique misses the anato9mical femoral ACL insertion : A cadaver study. Knee
Surg Sports Traumatol Arthrosc 2001;9:194-99.

38. Discussion
Secondly due a more vertical tunnel a synovial fluid may
seek inside the tibial and femoral tunnels leading to
tunnel dilatation.
*Hoher at al. Bone tunnel enlargement after ACL reconstruction, fact or Fiction?
Knee Surg Sports Traumatol Arthrosc 19989;6:231-240
* Skripiotz et al. Pressure induced periprosthetic osteolysis. Rat model. J orth Res
2000;18:481-84.

39. Tunnel widening after anterior cruciate ligament reconstruction: a
prospective randomized computed tomography--based study comparing 2
different femoral fixation methods for hamstring graft
Femoral tunnel widening was significantly less in the Transfix group
compared with the EndoButton group.
Sabat D.et al. Arthroscopy. 2011 Jun;27(6):776-83.
.
Literature review

40. Discussion
 Tight rope RT is suspensory fixation device and does not
have a fixed loop. The increased lengthening of the loop may
be attributed to the friction locking mechanism at very low
loads, akin to a Chinese finger trap.
 Our opinion is that a long term study is required to evaluate
whether the loop of the tight rope lengthens over a period of
time when patient starts to have full range of motion.
Barrow et al. Femoral suspension devices for Anterior Cruciate Ligament
Reconstruction. Do adjustable loops Lengthen? American Journal of Sports Medicine
2014 .Vol 42,No.2.343-49.
Buck etal. Timeline of tibial tunnel expansion after the single incision hamstring ACL
reconstruction. Arthroscopy 2004;20:34-36.

41. Discussion
Tunnel widening in
Aperture Fixation
Tunnel Widening After Hamstring Anterior Cruciate Ligament
Reconstruction Is Influenced by the Type of Graft Fixation Used: A
Prospective Randomized Study
There was a significant reduction of Tunnel widening in
both the femur and the tibia using fixation points close
to the joint, compared with the system where the
distance between the fixation points is long.
Peter Fauno et al. Arthroscopy ,Volume 21, Issue 11, Pages 1337–1341,
November 2005.


42. Femoral tunnel widening after quadrupled hamstring
anterior cruciate ligament reconstruction
Femoral tunnel widening was greater in
femoral cross pin fixation, compared to
bioabsorbable screw fixation
Philip Cheung et al. Journal of
Orthopaedic Surgery 2010;18(2):198-202

43.  There have been studies though which contradict this
concluding that the tunnel widening cannot be avoided by
fixation closer to the joint.
 Associated with the “ Creep” of the graft on cyclical loading
leading to delayed tendon bone healing.
 Buelow et al. A new Bicortical tibial fixation technique in ACL reconstruction with quadraple hamstring
tendon graft. Knee Surg Traumatol Arthrosc 2000;8:218-225.
 Clatworthy et al. tunnel widening in hamstring ACL reconstruction: A prospective clinical and radiological
evaluation of four different technique. ISAKOS congress, Manteaux, Switzerland May 14-18, 2001;120.

44. Discussion
Our study found no
difference in the clinical
outcomes of all the 3 groups-independent
of the tunnel
dilation

45. From current literature, tunnel widening does not appear
to correlate with a poor clinical result, but on the other
hand, there is only very few data beyond 3 years.
Asik M et al. The mid- to long-term results of the anterior cruciate ligament reconstruction with
hamstring tendons using Transfix technique. Knee Surg Sports Traumatol Arthrosc. 2007;15:965–72
Plaweski S et al . Anterior cruciate ligament reconstruction: assessment of the hamstring autograft
femoral fixation using the EndoButton CL. Orthop Traumatol Surg Res. 2009;95:606–13
Chen CH et al. Arthroscopic single-bundle anterior cruciate ligament reconstruction with
periosteum-enveloping hamstring tendon graft: clinical outcome at 2 to 7 years. Arthroscopy.
2010;26:907–17.
Webster et al. Bone tunnel enlargement following ACL reconstruction: a randomized comparison of
hamstring and patellar tendon bone graft with 2 year follow up. Knee Surg Sports Traumatol
Arthrosc;2001:9(2):86-91

46. Limitations of the Study
 Small Sample size of each group of patients
 Graft Fixation:
a. Anteromedial vs. Transtibial
b. No uniformity in the Loop size in tight rope RT
c. No uniformity in the Screw size in aperture fixation
d. No uniformity in the Graft size

47. Conclusion
 Tunnel widening occurs mostly in 1st year after ACL
reconstruction and occurs with every type of graft fixation
device.
 Exact etiology remains unknown and is probably
multifactorial.
 In literature opinion varies regarding optimal fixation
device.
 In our study we did not find any significant difference in
femoral tunnel enlargement in all three fixation devices.

48. THANK
YOU….