1. A Systematic Review of Bioabsorbable Versus Metallic Screws
in Anterior Cruciate Ligament Reconstruction
Ethan Lloyd Weisgarber
University of Toledo - 2016

2. ii
Acknowledgments
Thank you to my research mentor, Dr. Jiayong Liu of the Department of Orthopaedic
Surgery at the University of Toledo, who provided both the impetus for the start of this project
and constant guidance throughout.

3. iii
Table of Contents
Acknowledgments 1
Table of Contents 2
List of Figures 1
Introduction 2
Interference Screws 2
Anterior Cruciate Ligament Reconstruction 3
Methods 4
Study Identification 4
Study Characteristics 5
Data Analysis 8
Results 9
Functional Outcome Comparison 9
Other Measures of Function 11
Discussion 13
Complications 13
Future Directions 14
Conclusion 16
References 17
Appendix 19
Abstract 23

4. 1
List of Figures
Methods
Figure 1: Study Identification Procedure Page 5
Table 1: Characteristics of the Article Set 6
Appendix
Figure A1: JMP Oneway Analysis and T-test of Lysholm Score by
ooooScrew Class
19
Figure A2: JMP Oneway Analysis and T-test of IKDC Score by Screw
ooooClass
19
Figure A3: JMP Oneway Analysis and T-test of Percent Negative for
ooooPivot Shift by Screw Class
20
Table A1: Complete Numbers Spreadsheet of Data Set Values 21
Table A2: Complete Numbers Spreadsheet of Reported Complication
ooooData
22

5. 2
Introduction
Interference Screws
Metallic interference screws were first used for graft fixation in 1983, and have since
proven to be reliable in both biocompatibility and strength, becoming the gold standard in
surgical fixation. Metallic interference screws are not without their drawbacks, however. They
are known to regularly hinder magnetic resonance imaging due to their material properties. They
are also frequently difficult to remove in the event that revision surgery is necessary, and
complications during the initial surgery are not uncommon, as metallic interference screws have
been known to cause laceration of grafts and/or sutures upon primary insertion1.
Bioabsorbable interference screws have proven to provide a fixation strength comparable
to metallic interference screws with a decreased probability of graft laceration, no MRI
interference, and no need to remove the screw if revision surgery is needed. Still, bioabsorbable
screws have their own set of issues: they are more likely to fracture upon insertion, which
increases the likelihood for subsequent infection, and migration of the screw further into the knee
joint has been observed. There are multiple variations on the material used to manufacture
bioabsorbable screws, which include poly-L-lactic acid (PLLA), polyglycolic acid (PGA), poly-
D,L-lactic acid, PGA with trimethylene carbonate, PLLA with hydroxyapatite, and PLLA with
beta-tricalcium phosphate. PLLA is frequently used with minimal complications, usually
absorbing within a year post-operatively, depending on screw size. Large variations in absorption
time have been noted with some materials, such as PGA, which has been reported to persist
without complete absorption for as long as six years1.

6. 3
Anterior Cruciate Ligament Reconstruction
Both of the previously mentioned classes of interference screws have been applied in
anterior cruciate ligament (ACL) reconstruction to provide a reliable form of fixation to bind the
torn ligament and reduce long-term morbidity associated with the injury. ACL disruption is
extremely common, especially in sports medicine, with over 50,000 reconstructions being
performed annually. Such a high incidence of this injury and its subsequent corrective surgery
make this an essential topic of analysis1.
With a growing number of randomized controlled trials examining the functional
outcome of bioabsorbable versus metallic screws in anterior cruciate ligament reconstruction, a
systematic review of the relevant literature was completed in order to determine whether
functional outcome is significantly altered when applying a bioabsorbable interference screw in
ACL reconstruction versus a metallic interference screw.

7. 4
Methods
Literature was searched systematically for all articles accessible through the PubMed
database focusing on a comparison of bioabsorbable and metallic screw fixation in anterior
cruciate ligament reconstruction, specifically randomized controlled trials examined in studies
written in English.
Study Identification
PubMed was initially searched using the term “bioabsorbable screw”, with 479 article
results returned. Over four-hundred of these results were excluded by filtering the results to only
include articles examining randomized controlled trials, leaving a data set of 44 articles. These
articles were initially used for data analysis, as this study was originally intended to compare the
post-operative outcome of bioabsorbable screws versus titanium screws across all surgeries
covered in the datas set: these included studies concerning bioabsorbable screw application in
ankle fracture repair, distal tibiofibular syndesmosis injury fixation, and jaw fracture treatment.
Among these studies, however, there was no uniform method of reporting post-operative
functional outcome. The most common procedure examined among this initial data set was
anterior cruciate ligament reconstruction, with 29 articles examining patients undergoing the
procedure. After discussing the issue with the research supervisor, it was decided that the data
analysis would focus exclusively on ACL reconstruction, excluding another 15 articles. Among
the remaining 29 studies, 15 articles were comparing the outcome of bioabsorbable screw
application among various surgical procedures, with no control patients being administered
metallic screw fixation. Fifteen articles were thus excluded from data analysis for the lack of
metallic screw comparison. Of the 14 remaining articles, one study in German (initially

8. 5
examined due to its inclusion of an English abstract) was excluded, as data required for
comparison was not made available in the study abstract. Thirteen studies concerning
comparison of bioabsorbable and metallic screw fixation in ACL reconstruction remained for
data extraction and analysis. A flowchart of the study identification procedure can be found
below as Figure 1.
Study Characteristics
Characteristics of the studies examined, such as authors, publication year, total number of
patients, mean follow-up time, effective follow-up rate, type of bioabsorbable screw used, type
of metallic screw used, graft material, and timing of rehabilitation can be seen in Table 1 below.
All but one study was published since 20002. Number of patients examined in each study had a
Figure 1: Study Identification Procedure

9. 6
wide range, with one study examining as few as 40 patients, and another study examining over
200 subjects. The majority of studies were found to have used poly-L-lactic acid (PLLA)
bioabsorbable screws. Similarly, a majority used titanium interference screws for fixation,
although it is important to note that the other six studies examined did not specify the metallic
screw material, and it is a possibility that all studies examined used titanium fixation screws. The
most popular graft material among the data set was BPTB (bone-patellar tendon-bone) autograft,
although hamstring tendon autografts were also common to multiple studies. Lastly, a
rehabilitation plan starting immediately after surgery was frequent among the studies examined,
Authors Publication Year Total Number of
Patients
Mean Follow Up
Time (months)
Effective Follow-
Up Rate
Type of
Bioabsorbable
Screw
Type of Metallic
Screw
Graft Material Timing of
Rehabilitation
Benedetto KP,
Fellinger M, Lim TE,
Passler JM, Schoen
JL, Willems WJ
2000 124 12 91.1% PGA/TMC Titanium BPTB Autograft 2 weeks postop
Kaeding C, Farr J,
Kavanaugh T,
Pedroza A
2005 97 12 100.0% PLLA Titanium BPTB Autograft Unclear
Drogset JO, Straume
LG, Bjørkmo I, Myhr
G
2005 41 90 82.9% PLLA Titanium BPTB Autograft Unclear
Arneja S, Froese W,
MacDonald P.
2004 35 18 85.7% PLLA Unclear Semitendinosus-
Gracilis Graft
Immediately After
Surgery
McGuire DA, Barber
FA, Elrod BF, Paulos
LE
1999 204 28.8 80.4% PLLA Unclear BPTB Autograft,
BPTB Allograft,
Achilles Tendon
Allograft,
Combination of
Autologous and
Allogeneic Grafts
Immediately After
Surgery
Fink C, Benedetto KP,
Hackl W, Hoser C,
Freund MC, Rieger M
2000 40 24 92.5% PGA/TMC Titanium BPTB Autograft Immediately After
Surgery
Myers P, Logan M,
Stokes A, Boyd K,
Watts M
2008 114 24 87.7% HA-PLLA Titanium Hamstring Tendon
Autograft
Not Mentioned
Arama Y, Salmon LJ,
Sri-Ram K, Linklater
J, Roe JP, Pinczewski
LA.
2015 40 60 95.0% PLLA-HA Titanium Hamstring Tendon
Autograft
Immediately After
Surgery
Drogset JO,
Grøntvedt T, Jessen
V, Tegnander A,
Mollnes TE, Bergh K
2011 41 24 97.6% PLLA Titanium BPTB Autograft Immediately After
Surgery
Moisala AS, Järvelä T,
Paakkala A, Paakkala
T, Kannus P, Järvinen
M
2008 62 24 88.7% PLLA/TMC Unclear Quadrupled
Hamstring
Tendons Autograft
Immediately After
Surgery
Järvelä T, Moisala AS,
Sihvonen R, Järvelä
S, Kannus P, Järvinen
M
2007 77 24 94.8% PLLA Unclear Hamstring Tendon
Autograft
Immediately After
Surgery
Suomalainen P,
Järvelä T, Paakkala A,
Kannus P, Järvinen M
2012 90 60 72.2% PLLA/TMC Unclear Hamstring Tendon
Autograft
Immediately After
Surgery
Drogset JO,
Grøntvedt T,
Tegnander A
2006 41 24 90.2% PLLA Unclear BPTB Autograft Immediately After
Surgery
1
Table 1: Characteristics of the Article Set 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14

10. 7
although again there are multiple studies in which the timing of rehabilitation was unclear from
the information given or not mentioned at all.
The data table of all values extracted from the study set can be found attached in the
appendix as Table A1. The total number of patients enrolled in the sum of the studies was
calculated to be 1006, although not all of these patients were available for follow-up. The
number of patients at the mean-follow up point from all studies was found to be 883, with the
average study mean follow-up time calculated as 32.7 months, or approximately two years and
seven months. A total of 528 bioabsorbable interference screw procedures were examined, with a
corresponding 464 metallic interference screw fixations included in the data set. The 64-patient
disparity between the two experimental groups is due to multiple studies that applied
bioabsorbable interference screws to both double-bundle and single-bundle graft procedures to
be compared to a control group of single-bundle, metallic interference screw fixation subjects.
Thus, in these studies, the number of patients receiving a bioabsorbable screw outnumber those
receiving a metallic screw two to one.
Effective follow-up rate was consistently high among the majority of studies, with the
study conducted by Suomalainen et. al.14 reporting the lowest follow-up rate at 72.2%. The
average follow-up rate was calculated to be 89.1% over all studies.

11. 8
Data Analysis
Upon initial examination of the data set, multiple measures of functional outcome were
noted. There were four measures that were seen in a majority of the studies examined (at least
seven of the thirteen studies): the Lysholm Knee Scoring Scale, the International Knee
Documentation Committee (IKDC) Subjective Knee Evaluation, the Pivot Shift Test, and the
stability measurements obtained via the KT-1000 arthrometer.
Initial data analysis (including average and standard deviation calculations) was
completed on the study set using Apple Numbers version 3.6.2. Further analysis (such as oneway
analyses and t-tests) was done using JMP version 12, developed by the SAS Institute.

12. 9
Results
Functional Outcome Comparison
The Lysholm Knee Scoring Scale serves to evaluate functional outcomes of knee
ligament surgery, specifically quantifying symptoms of joint instability. Patients are given a
questionnaire in which multiple options are given in reference to individual categories (limp,
support, locking, instability, pain, swelling, stair climbing, and squatting). A lower score in each
of these categories (such as a “severe/constant limp, which is given a score of zero) is indicative
of a worse functional outcome. The scores in each category are summed to give a value, with the
highest possible score being 100. Nine out of thirteen (approximately 69%) of the studies
examined for this review reported scores using the Lysholm Knee Scoring Scale, making this
scoring method the most common among the data set. Scores reported for the Lysholm Knee
Scoring Scale for individual studies can be found attached in the appendix as Table A1. The
average value among all studies for the patients administered bioabsorbable screw fixation was
calculated to be 92.8, with a standard deviation of 3.2. The corresponding average value among
the patients administered metallic screw fixation was found to be 93.0, with a standard deviation
of 3.8.
The IKDC Subjective Knee Evaluation aims to detect improvement or retrogression in
knee function, symptoms of injury, and ability to participate in activities (such as sports) due to
knee impairment. The IKDC Standard Knee Evaluation form was first introduced in 1993 and
has undergone multiple revisions to exist in its current form: an 18 item questionnaire with seven
items focusing on symptoms, nine concerning proficiency of daily activity completion, one

13. 10
concerning sports participation, and one inquiry about the patient’s current knee function. The
IKDC score falls into one of four classifications: Normal, Nearly Normal, Abnormal, or Severely
Abnormal. As most patients pre-operatively fall into either “abnormal” or “severely abnormal”, a
shift to normal/nearly normal is desired post-operatively. Seven of the thirteen studies
(approximately 54%) reported outcome via IKDC score, which was quantified for analysis as
“percent normal”, calculated by taking the number of patients falling into the “normal” or
“nearly normal” designation as a fraction of the total patients available for follow-up in each
fixation device grouping. Scores reported for the IKDC Subjective Knee Evaluation for
individual studies can be found attached in the appendix as Table A1. The average value among
all studies for the patients administered bioabsorbable screw fixation was calculated to be 88.3,
with a standard deviation of 5.5. The corresponding average value among the patients
administered metallic screw fixation was found to be 87.0, with a standard deviation of 11.5.
The Pivot Shift Test checks for instability of the knee joint, as the degree of instability
acts as a determinant of knee function; a high degree of instability may be associated with the
patient felling that the one is “not secure” or may “give out”. The physician flexes and extends
the leg with the knee pointed inward towards the patient, making the test quite uncomfortable for
the subject, subsequently making accurate results difficult to obtain with a conscious patient after
the first test. Like the IKDC Evaluation, seven of the thirteen studies (approximately 54%)
reported outcomes using the pivot shift test. Results were given as “percent negative”, i.e., the
fraction of patients in each screw group that were not positive for pivot shift. Scores reported for
pivot shift for individual studies can be found attached in the appendix as Table A1. The average
value among all studies for the patients administered bioabsorbable screw fixation was calculated

14. 11
to be 79.6%, with a standard deviation of 9.1%. The corresponding average value among the
patients administered metallic screw fixation was found to be 74.5%, with a standard deviation of
15.2%.
One-way analyses were completed using JMP Statistical Analysis software. Distribution
of the values analyzed and t-test data can be found in the appendix as Figures A1, A2, and A3 for
Lysholm scores, IKDC values, and pivot shift percentages, respectively. Lysholm Score was first
analyzed by screw class, with a t-test being run subsequently, assuming unequal variances. With
a confidence level of 0.95 [a significance level (alpha) of 0.05], the test indicated that there was
no significant difference in Lysholm score between bioabsorbable and metallic screws, with a p-
value of 0.60. Similarly, the t-test run comparing values by interference screw class for the IKDC
scale returned a p-value of 0.65, again exceeding the significance level of 0.05, indicating that
there was no significant difference in IKDC evaluation scores between the two screw classes.
Lastly, a t-test was applied to compare the values for the percent of patients negative for the pivot
shift test by screw class. A calculated p-value of 0.52 again exceeded the significance level of
0.05, indicating that there was no statistical difference in the percentage of patients testing
negative for the pivot shift test between bioabsorbable and metallic interference screw groups.
Other Measures of Function
The KT-1000 arthrometer is an instrument used to measure the motion of the anterior
tibia relative to the femur before and after ACL reconstructive surgery. Differences in data
reporting in reference to the KT-1000 arthrometer, however, made the outcomes among studies

15. 12
difficult to compare. Although almost every study made reference to measuring functional
outcome using the KT-1000 arthrometer, five studies reported results as a percent of subjects
within designated motion intervals (such as <3 mm, 3-5 mm, >5 mm), while seven studies
reported an average value with a corresponding standard deviation for motion at follow-up
among each screw group. Without access to the raw data for these studies, it was not possible to
compare the functional outcomes measured via the KT-1000 arthrometer over the entire data set.
One other stability measure seen in multiple studies, usually in conjunction with the
Lysholm Knee Scoring Scale, was the Tegner Activity Level Scale. It was not, however, reported
in a majority of the studies examined.

16. 13
Discussion
To summarize the results of comparing the three measures of functional outcome
examined in this review, no significant difference was found between interference screw groups
in reference to Lysholm Score, IKDC Evaluation, or the Pivot Shift Test. These results suggest
that while bioabsorbable screw fixation is an acceptable alternative to traditional metallic
interference screw fixation, a better functional outcome is not necessarily expected with one
screw type versus another. This result is in agreement with that found by Shen et. al.1, who
arrived at similar results after conducting a meta-analysis of ten studies comparing bioabsorbable
and metallic screws in randomized controlled trials concerning ACL reconstruction.
Complications
Post-operative complications were discussed in several of the studies examined. A
spreadsheet of complications reported in the data set can be found attached in the appendix as
Table A2. Not all studies addressed post-operative complications, although there were multiple
studies that reported “no complications” among the corresponding subject set at the time of
follow-up. Furthermore, some studies reported the number of complications seen among each
fixation device group, without giving further detail on the nature of the individual problems. The
most common complication reported among the bioabsorbable screw group was effusion, with
14 cases. Reduced range of motion and infection were also somewhat common among this
group, with four cases reported for each. There were also incidences of reflex sympathetic
dystrophy, thrombophlebitis, pain in the lateral compartment, crepitus and laxity, cyst over tibial
tunnel, and reinjury among the bioabsorbable screw patients, with a total of 41 bioabsorbable

17. 14
screw subjects experiencing postoperative complications among the examined studies. A total of
46 complications were reported among patients receiving metallic interference screw fixation.
Effusion and infection were most commonly seen (five cases each), with cases of reduced range
of motion, hemarthrosis, pain at the site of tibial staples, pain in the region of inferior patella, and
reinjury also being reported among the data set. Although post-operative complication rate
among metallic screw subjects exceeded that of the bioabsorbable screw group, in order to truly
understand the nature of complications in relation to screw material, further analysis must be
completed.
Future Directions
While the results of this study are in-line with previous analyses conducted in a similar
fashion, research in this area still has room to expand. As mentioned previously, there are
multiple materials being used in the manufacturing of bioabsorbable screws. Although PLLA
appears to be the most commonly used material, investigations should be conducted regarding its
efficacy versus other materials. Also previously mentioned was the application of bioabsorbable
screws in multiple methods of ACL graft reconstruction. For instance, it would be valuable to
understand if a screw type is associated with a better functional outcome when a double-bundle
procedure is used versus a single-bundle graft.
Although meta-analyses have been conducted to examine functional outcome of metallic
versus bioabsorbable screws, they have not been far-reaching in scope. Future analyses should be
done searching multiple databases in order to include all relevant existing literature examining
the subject. Another aim for these future studies is information that would have been valuable
during this research — raw data. Some of the issues encountered during this review would have

18. 15
been easily remedied with access to individual subject measures of function, such as the
reporting disparity between studies with regard to the KT-1000 arthrometer.
Lastly, the data set examined in this study can be further analyzed. Statistical methods
such as heterogeneity tests and assessment of publication bias can yield information as to the
quality of the data gathered and the conclusions reached. Information such as radiologic results
can also be pooled and quantified.

19. 16
Conclusion
Although surgical methods applying bioabsorbable fixation devices are still relatively
new, enough literature has emerged on the subject to warrant systematic analysis. With ACL
reconstruction being so prevalent, the procedure lends itself well to study, and the multiple
methods of evaluating functional outcome are easily compared. Like other reviews before it, this
study found no significant functional difference in patients undergoing ACL fixation with a
bioabsorbable interference screw versus a metallic counterpart, at least in reference to the
measures of Lysholm score, IKDC evaluation, and the pivot shift test. Further analysis should be
completed in the future to confirm that bioabsorbable screws are truly a reliable alternative to the
gold standard in graft fixation.

20. 17
References
1. Shen, C., Jiang, S. D., Jiang, L. S., & Dai, L. Y. (2010). Bioabsorbable versus metallic
interference screw fixation in anterior cruciate ligament reconstruction: a meta-analysis of
randomized controlled trials. Arthroscopy: The Journal of Arthroscopic & Related Surgery,
26(5), 705-713.
2. Arama Y, Salmon LJ, Sri-Ram K, Linklater J, Roe JP, Pinczewski LA. Bioabsorbable Versus
Titanium Screws in Anterior Cruciate Ligament Reconstruction Using Hamstring Autograft: A
Prospective, Blinded, Randomized Controlled Trial With 5-Year Follow-up. Am J Sports Med.
2015 Aug;43(8):1893-901. doi: 10.1177/0363546515588926. Epub 2015 Jun 24. PubMed PMID:
26109611.
3. Arneja S, Froese W, MacDonald P. Augmentation of femoral fixation in hamstring anterior
cruciate ligament reconstruction with a bioabsorbable bead: a prospective single-blind
randomized clinical trial. Am J Sports Med. 2004 Jan-Feb;32(1):159-63. PubMed PMID:
14754739.
4. Benedetto KP, Fellinger M, Lim TE, Passler JM, Schoen JL, Willems WJ. A new
bioabsorbable interference screw: preliminary results of a prospective, multicenter, randomized
clinical trial. Arthroscopy. 2000 Jan-Feb;16(1):41-8. PubMed PMID: 10627344.
5. Drogset JO, Straume LG, Bjørkmo I, Myhr G. A prospective randomized study of ACL-
reconstructions using bone-patellar tendon-bone grafts fixed with bioabsorbable or metal
interference screws. Knee Surg Sports Traumatol Arthrosc. 2011 May;19(5):753-9. doi:
10.1007/s00167-010-1353-4. Epub 2011 Jan 14. PubMed PMID: 21234545; PubMed Central
PMCID: PMC3076560.
6. Drogset JO, Grøntvedt T, Jessen V, Tegnander A, Mollnes TE, Bergh K. Comparison of in
vitro and in vivo complement activation by metal and bioabsorbable screws used in anterior
cruciate ligament reconstruction. Arthroscopy. 2006 May;22(5):489-96. PubMed PMID:
16651157.
7. Drogset JO, Grøntvedt T, Tegnander A. Endoscopic reconstruction of the anterior cruciate
ligament using bone-patellar tendon-bone grafts fixed with bioabsorbable or metal interference
screws: a prospective randomized study of the clinical outcome. Am J Sports Med. 2005 Aug;
33(8):1160-5. Epub 2005 Jul 6. PubMed PMID: 16000666.
8. Fink C, Benedetto KP, Hackl W, Hoser C, Freund MC, Rieger M. Bioabsorbable
polyglyconate interference screw fixation in anterior cruciate ligament reconstruction: a

21. 18
prospective computed tomography-controlled study. Arthroscopy. 2000 Jul-Aug;16(5):491-8.
PubMed PMID: 10882444.
9. Järvelä T. Double-bundle versus single-bundle anterior cruciate ligament reconstruction: a
prospective, randomize clinical study. Knee Surg Sports Traumatol Arthrosc. 2007 May;15(5)
500-7. Epub 2007 Jan 10. PubMed PMID: 17216271.
10. Kaeding C, Farr J, Kavanaugh T, Pedroza A. A prospective randomized comparison of
bioabsorbable and titanium anterior cruciate ligament interference screws. Arthroscopy. 2005
Feb;21(2):147-51. PubMed PMID: 15689862.
11. McGuire DA, Barber FA, Elrod BF, Paulos LE. Bioabsorbable interference screws for graft
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PubMed PMID: 10424549.
12. Moisala AS, Järvelä T, Paakkala A, Paakkala T, Kannus P, Järvinen M. Comparison of the
bioabsorbable and metal screw fixation after ACL reconstruction with a hamstring autograft in
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screws with hamstring autograft in anterior cruciate ligament reconstruction: a prospective
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14. Suomalainen P, Järvelä T, Paakkala A, Kannus P, Järvinen M. Double-bundle versus single-
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22. 19
Appendix
Figure A1: JMP Oneway Analysis and T-test of Lysholm Score by Screw Class
Figure A2: JMP Oneway Analysis and T-test of IKDC Score by Screw Class

23. 20
Figure A3: JMP Oneway Analysis and T-test of Percent Negative for Pivot Shift by Screw Class

24. 21
Table A1: Complete Numbers Spreadsheet of Data Set Values

25. 22
Table A2: Complete Numbers Spreadsheet of Reported Complication Data

26. 23
Abstract
A Systematic Review of Bioabsorbable Versus Metallic Screws in Anterior Cruciate
Ligament Reconstruction
Ethan Weisgarber
Objective: Determine if functional outcome is significantly altered in ACL reconstruction
completed with a bioabsorbable interference screw over a metallic screw.
Method: The PubMed Database was systematically searched in order to obtain the relevant
literature (13 randomized controlled studies) from which multiple study characteristics were
extracted. The data set was subsequently analyzed for values indicating functional outcome, such
as Lysholm score, IKDC evaluation, KT-1000 arthrometer testing, and pivot shift prevalence
among each fixation device group.
Results: The average values and standard deviations calculated for all three measures among
both fixation device groups were found to exceed the significance level of 0.05 after application
of t-tests with JMP statistical software.
Conclusion: No statistical significant difference was found between interference screw groups in
reference to Lysholm Score, IKDC Evaluation, or the percent of subjects negative for pivot shift.