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Clinical outcomes of ACL reconstruction with tibialis anterior allograft using an anteromedial portal approach
THEKNE-02291; No of Pages 4 The Knee xxx (2016) xxx–xxx
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The Knee
Clinical outcomes of ACL reconstruction with tibialis anterior allograft using an anteromedial portal approach Jason Capo, Steven D. Shamah ⁎, Laith Jazrawi, Eric Strauss Department of Orthopaedic Surgery, NYU Hospital for Joint Diseases, 301 East 17th Street, New York, NY 10003, USA
a r t i c l e
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Article history: Received 17 November 2015 Received in revised form 7 June 2016 Accepted 12 June 2016 Available online xxxx Keywords: ACL reconstruction Tibialis anterior allograft Anteromedial portal
a b s t r a c t Background: The purpose of the current study was to evaluate the clinical and functional outcomes of ACL reconstruction with tibialis anterior allograft using the anatomic anteromedial portal approach and aperture sheath and screw fixation. Methods: We evaluated primary ACL reconstructions with tibialis anterior allograft using an anatomic anteromedial portal approach performed at our institution between January 2011 and February 2014. Patients with a minimum of two years of follow-up were contacted and brought back for a complete physical examination of the knee. A KT-1000 arthrometer was used to measure anterior tibial translation in both knees. Clinical outcome scores were generated using validated outcome measures. Results: Forty-five patients with a mean age of 43.9 years were available for complete follow-up at a mean of 30.8 months. Of the 45 patients who came in for follow-up, two were found to have a clinical failure/ruptured graft (4.4%). Significant improvements were noted to be present compared to baseline values for all assessed clinical outcome measurements. KT-1000 arthrometer measures demonstrated a mean (± standard deviation) of 0.26 ± 1.11 mm side to side difference compared to the contralateral side with maximum manual stress applied. Conclusions: Our data demonstrating significant improvements in clinical outcome assessments coupled with excellent KT-1000 arthrometer values and a low rate of clinical failure supports the use of tibialis anterior allografts with an anteromedial portal surgical approach in ACL reconstruction. This improvement in results may be related to more accurate anatomic tunnel placement via AMP drilling and improved graft fixation methods. © 2016 Elsevier B.V. All rights reserved.
1. Introduction Anterior cruciate ligament (ACL) reconstruction is now the sixth most commonly performed orthopedic procedure [28] and that number has been increasing annually [20,14]. Allografts have increasingly been chosen for ACL reconstruction and have several advantages including the absence of donor site morbidity, shorter operative times, improved cosmesis, easier rehabilitation, cost-effectiveness, decreased postoperative pain, and slightly less range of motion loss [5,6,13,25]. The patellar tendon and Achilles, both of which have bony attachments, have been the focus of the majority of allograft research. There is less information in the literature on the use of soft tissue allografts. Despite this, the use of a tibialis anterior tendon is an appealing graft choice for ACL reconstruction. The tendon has superior biomechanical (structural, material, and viscoelastic) properties [11]. According to the 2013 AOSSM ACL Reconstruction survey, tibialis anterior allograft is the most commonly used allograft in primary ACL reconstructions for the adult recreational athlete [1*].
⁎ Corresponding author at: 333 East 38th Street, New York, NY 10016, USA. E-mail address: [email protected] (S.D. Shamah).
The current data on the use of tibialis anterior allograft is both limited and controversial. Prior studies in the sports medicine literature have demonstrated poor clinical outcomes following ACL reconstruction using tibialis anterior allografts. In a study of 69 patients, Singhal et al. reported high rates of subsequent surgery, including a high rate of revision Anterior cruciate ligament reconstruction (ACLR) for graft failure [29]. In a smaller, more recent study, Shybut et al. reported a large number of patients reporting fair or poor outcome scores with demonstration of residual laxity [28]. One of the limitations associated with the prior studies investigating the use of tibialis anterior allografts in ACL reconstruction is the approach used by surgeons to drill the femoral tunnel. There are two techniques that are commonly used for drilling the femoral tunnel, the transtibial technique (TT) and the anteromedial portal (AMP) approach. Use of the AMP approach is an emerging trend based on the ability to better restore ACL anatomy by drilling the femoral tunnel more centrally in the ACL footprint [16,9,33]. The AMP approach has been associated with better rotational stability and anterior translation compared to the TT technique [9]. The prior tibialis anterior allograft studies analyzed patients whose femoral tunnels were drilled using the transtibial technique. While a number of studies have compared the two femoral tunnel drilling approaches using other graft choices [9,22,26,15], at
http://dx.doi.org/10.1016/j.knee.2016.06.002 0968-0160/© 2016 Elsevier B.V. All rights reserved.
Please cite this article as: Capo J, et al, Clinical outcomes of ACL reconstruction with tibialis anterior allograft using an anteromedial portal approach, Knee (2016), http://dx.doi.org/10.1016/j.knee.2016.06.002
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J. Capo et al. / The Knee xxx (2016) xxx–xxx
this time, no study in the literature has been dedicated to analyzing the anteromedial portal approach with tibialis anterior allograft for ACL reconstruction. The purpose of the current study was to evaluate the clinical and functional outcomes of ACL reconstruction with tibialis anterior allograft using the anatomic anteromedial portal approach and aperture sheath and screw fixation. These recent advancements in surgical technique and graft fixation methods have led to improvements in ACL reconstruction with low failure rates and high levels of return to athletic activity. Due to these improvements, we hypothesized that our patients would demonstrate excellent knee outcome scores, low failure rates in addition to excellent stability on arthrometric testing. 2. Methods After obtaining approval from our Institutional Review Board, we retrospectively evaluated primary ACL reconstructions with tibialis anterior allograft using an anatomic anteromedial portal approach performed at our institution between January 2011 and February 2014. Subjects were identified from physician surgical logs and office records. All patients were skeletally mature and had magnetic resonance imaging of the affected knee demonstrating complete anterior cruciate ligament rupture. All patients had femoral and tibial tunnel graft fixation using a sheath and screw system (Intrafix, DePuy Mitek Inc., Raynham, MA). Allografts treated with low dose gamma radiation and allografts that were aseptically processed without treatment of low dose gamma radiation were both used. Patients were required to have undergone the specific procedure at least two years prior to follow-up, and were required to be at least 18 years old at time of follow-up. Exclusion criteria included patients younger than 18 years old, patients with incomplete chart information, and patients with previous reconstructive surgery on their knee. Over that period, fifty-five patients met the inclusion criteria. Forty-five patients agreed to come back to the office and participate in the study. All patients followed the same rehabilitation protocol. Some milestones included running straight ahead at three months, and full return to sport at 10 months. At the time of follow-up, a complete physical examination of the knee was performed including assessments of the Lachman and pivot-shift tests and range of motion. A KT-1000 Arthrometer (MEDmetic Corporation, San Diego, CA) was used to measure anterior tibial translation in both knees. Anterior tibial translation was measured at three different stress values: 15 lb, 20 lb, and with maximum manual stress applied. Clinical outcome scores were generated using the International Knee Documentation Committee (IKDC) score, Lysholm score, Kujala score, and Single Assessment Numerical Evaluation (SANE) score. Return to play activity levels were assessed using the Tegner Activity score. Patients were asked to compare their activity levels pre-injury and at final follow-up based on the Tegner activity scale (1 to 10). Post-op radiographs were analyzed for femoral tunnel angle measurements. Finally, patients were asked if they were satisfied with the surgery and whether or not they would have the same procedure using the same graft again, if necessary. Statistical analysis was done using SPSS Statistics Version 18.0 (IBM Inc., Chicago, IL, USA) for all data processing and statistical analyses. Statistical significance was set at p b 0.005.
Figure 1. A bar chart depicting the age distribution of the cohort. Mean age was 43.9 years (range, 25.7 to 69.7 years).
all assessed parameters. The mean IKDC score improved from 32.9 to 86.4 (p b .001). The mean Lysholm score improved from 35.4 to 90.7 (p b .001). The mean Kujala score improved from 46.8 to 91.3 (p b .001). The mean follow-up SANE score was 85.3. See Figure 2. The mean Tegner score decreased from 5.9 pre-injury to 5.3 at final follow-up (p = .007). Thirty-five out of forty-three (81.4%) patients reported getting back to within one level of their pre-injury activity. Overall, 41/43 (93.44%) patients reported that they are happy with their recovery and would have the same surgery with the same graft again, if necessary. Of the 45 allografts utilized, 27 were treated with low dose gamma radiation and 18 were processed aseptically without radiation treatment. No significant differences were found in outcomes between the radiated and non-radiated grafts. Of the two grafts that ruptured, one graft was treated with gamma radiation and one graft was not. KT-1000 arthrometer measures demonstrated a mean of 0.26 ± 1.11 mm (range, −2 to 3) side to side difference compared to the contralateral side with maximum manual stress applied. The mean femoral tunnel angle measured was 135.1 (range, 126.0 to 143.0). The mean graft size diameter used as measured by a graft sizer in the operating room was 8.9 mm (range, 8.0 to 10.0). 4. Discussion The prior literature on tibialis anterior allograft as a graft choice is limited and conflicting. There are three previous studies that reported poor outcomes for ACLR with tibialis anterior allograft. Singhal et al. reported in 2007 unfavorable results in a study of 69 patients (mean age: 31.7 years). Femoral tunnel drilling in this study was done using the transtibial technique and graft fixation was obtained using interference screws. Overall, 16 of the 69 patients (23.2%) required ACL revision for graft failure at a mean of 22 months (range, five to 47 months) following the initial surgery. Twenty-six patients (38%) required additional
3. Results Forty-five patients with a mean age of 43.9 years (range, 25.7 to 69.7 years) were available for complete follow-up at a mean of 30.8 months post-ACLR (range, 24.0 to 45.0 months). Age distribution can be seen in Figure 1. Of the 45 patients who came in for follow-up, two were found to have a clinical failure/ruptured graft (4.44%). The ages of the two patients whose graft failed were 36.3 and 33.5 years old. For the 43 (18 males, 25 females) remaining patients, significant improvements were noted to be present compared to baseline values for
Figure 2. A bar chart depicting pre-operative and post-operative outcome scores. All scores showed significant improvement (p b .001).
Please cite this article as: Capo J, et al, Clinical outcomes of ACL reconstruction with tibialis anterior allograft using an anteromedial portal approach, Knee (2016), http://dx.doi.org/10.1016/j.knee.2016.06.002
J. Capo et al. / The Knee xxx (2016) xxx–xxx
surgery, which included one knee arthroplasty. The mean age of failed patients was 22.8 years. The investigators attributed their high failure rate to using a graft with slow incorporation, use of an accelerated rehabilitation program, early return to sport, and an active, high demand patient population. In their conclusion they cautioned against using tibialis anterior allograft for younger or higher demand patients. Smith et al. reported results of 19 ACL reconstructions (mean age 37 years) with soft tissue allografts [31]. Ninety percent of their allografts were tibialis anterior. They were analyzed using roentgen stereophotographic analysis with each operative knee serving as its own control. The mean increase in laxity was 1.1 mm at six months. Total graft slippage averaged 1.9 mm at four months and 21% of the cohort had a laxity increase of three millimeters or more. However, these patients reported excellent outcome scores. Femoral tunnel drilling was done using the transtibial technique and graft fixation was accomplished using the EZloc femoral fixation device (Arthrotek, Inc., Warsaw, IN). Most recently, Shybut et al. reported unfavorable outcomes for 19 patients (mean age 39.9). They reported that only 65% of patients achieved good or excellent results based on functional outcome scores. 4/19 patients (21.1%) had laxity on physical exam with a KT-1000 sideto-side difference greater than five millimeters. Their analysis did not reveal a significant correlation between age and outcome. Femoral tunnel drilling was done using the transtibial technique, and DePuy Mitek Rigidfix or Arthrex Transfix devices were used for femoral fixation. In contrast, Nyland et al. showed positive results in a cohort of 18 patients who underwent tibialis anterior ACL reconstruction with interference screw fixation [24]. They did not comment on which technique was used for the femoral tunnel drilling. Seventeen out of eighteen patients (94.4%) had a normal or near normal IKDC clinical examination scores, with mean side-to-side difference on KT-1000 testing of 1.1 mm. All patients returned to their pre-injury level of activity, which the investigators described as moderate. The investigators recommended the use of tibialis anterior allograft in ACLR suggesting that its superior biomechanics may make it a promising graft choice for patients, including younger and high demand patients. Edgar et al., Nakata et al., and Carey et al. also published studies reporting good outcomes for soft tissue allografts [8,23,3]. However, they focused on hamstring and Achilles (without bone plug) allografts and not tibialis anterior. Our patient population resembled the cohorts of Shybut and Singhal. However, unlike any of the previous studies femoral tunnel drilling was performed using the anteromedial portal technique. Our patients showed excellent outcomes on subjective outcome scores and KT1000 arthrometer testing. From these results, we recommend using a tibialis anterior allograft for ACL reconstruction, provided that the femoral tunnel is drilled via the anteromedial portal. We believe that the use of an anteromedial portal aids in placement of the femoral tunnel in the vital location of the anatomic footprint of the ACL origin. Reestablishing the anatomic femoral origin of the ACL is essential when undergoing ACLR with tibialis anterior allograft. Recent emphasis has been placed on more anatomic tunnel positioning in ACL reconstruction, aimed at controlling both anterior tibial translation and tibial rotation [9]. To better restore ACL anatomy, the emerging trend is to drill the femoral tunnel more centrally in the ACL footprint, slightly lower on the wall of the lateral femoral condyle and more anterior than when performing a standard transtibial technique [22,12,34]. The presumption being that a more horizontally oriented graft, as opposed to a vertical graft, will optimize rotary as well as translational stability [21,30,27]. Trying to accomplish this by drilling the femoral tunnel through the use of the transtibial technique may be complicated. Therefore, the use of an anteromedial portal (AMP) has been proposed to drill the femoral tunnel separately in a more horizontal location, achieving adequate tunnel length for fixation and incorporation into the bone [4,1,32].
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Figure 3. An anteroposterior view of a post-operative X-ray following ACL reconstruction using the anteromedial portal approach, which allows for a more anatomic positioning of the allograft. The outlines of the femoral and tibial tunnels are visible.
This portal allows for precise placement of the guidewire and proper visualization of the ACL footprint. In contrast to the traditional transtibial technique, when the tunnel is drilled through the anteromedial portal, the tunnel aperture is shallow and inferior, closer to the center of the footprint and in a more anatomic position [10,7]. This improves the kinematics of the knee [17,18]. When the tunnels are drilled independently, the risk of posterior wall blowout is low [2]. The remaining ACL fibers may be preserved, the interference screws may be placed parallel to the bone plug with no lateral incisions, and single-bundle, double-bundle, and revision procedures may be easily performed [19]. Femoral tunnel placement through the AMP allows better assessment intraoperatively so that the graft placed is the center of the native footprint properly without excess stresses or loads. The ultimate goal of anatomic reconstruction is to place the ACL graft at a more anatomic location on both the tibia and femur. Franchesi et al. reported that femoral tunnel drilling through the AMP improves anteroposterior laxity and rotational stability of the knee, and patients are more likely to return to their pre-operative sport activity [9]. They also found that position of the center of the ACL was lower and more anterior when using an AMP as opposed to the transtibial technique. This was evidence to the belief that the AMP respects the native ACL anatomy and position. A direct effect of drilling the femoral tunnel through the anteromedial portal can be seen from the femoral tunnel angle with respect to the femoral condyles. The femoral tunnel can be seen on post-operative X-rays, with the outline of the tunnel lucent (Figure 3). This result is evidence to the advantageous aspect of the anteromedial portal. The mean femoral tunnel angle measured was 135.1 (range, 126.0 to 143.0), which corresponds to 10:30 and 1:30 on a clock face for right and left knees respectively. See Figure 3. There were some limitations in our study. Our cohort of patients was not as large as some of the previous studies. We did not have many patients that were younger than 30 at the time of surgery. As this study only enrolled patients with tibialis anterior allograft grafts, we cannot directly compare these results to other grafts (ex: BTB autograft) and can only use historical controls. We also cannot directly compare these results to the transtibial technique and need to rely on historical controls. Additionally, future research should continue to analyze the effect that different fixation devices have on outcomes as well as how the modified transtibial technique compares to the anteromedial portal approach. 5. Conclusion Our data demonstrating significant improvements in all clinical outcome assessments coupled with excellent KT-1000 arthrometer values and a low rate of clinical failure supports the use of tibialis anterior
Please cite this article as: Capo J, et al, Clinical outcomes of ACL reconstruction with tibialis anterior allograft using an anteromedial portal approach, Knee (2016), http://dx.doi.org/10.1016/j.knee.2016.06.002
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Please cite this article as: Capo J, et al, Clinical outcomes of ACL reconstruction with tibialis anterior allograft using an anteromedial portal approach, Knee (2016), http://dx.doi.org/10.1016/j.knee.2016.06.002
Contents lists available at ScienceDirect
The Knee
Clinical outcomes of ACL reconstruction with tibialis anterior allograft using an anteromedial portal approach Jason Capo, Steven D. Shamah ⁎, Laith Jazrawi, Eric Strauss Department of Orthopaedic Surgery, NYU Hospital for Joint Diseases, 301 East 17th Street, New York, NY 10003, USA
a r t i c l e
i n f o
Article history: Received 17 November 2015 Received in revised form 7 June 2016 Accepted 12 June 2016 Available online xxxx Keywords: ACL reconstruction Tibialis anterior allograft Anteromedial portal
a b s t r a c t Background: The purpose of the current study was to evaluate the clinical and functional outcomes of ACL reconstruction with tibialis anterior allograft using the anatomic anteromedial portal approach and aperture sheath and screw fixation. Methods: We evaluated primary ACL reconstructions with tibialis anterior allograft using an anatomic anteromedial portal approach performed at our institution between January 2011 and February 2014. Patients with a minimum of two years of follow-up were contacted and brought back for a complete physical examination of the knee. A KT-1000 arthrometer was used to measure anterior tibial translation in both knees. Clinical outcome scores were generated using validated outcome measures. Results: Forty-five patients with a mean age of 43.9 years were available for complete follow-up at a mean of 30.8 months. Of the 45 patients who came in for follow-up, two were found to have a clinical failure/ruptured graft (4.4%). Significant improvements were noted to be present compared to baseline values for all assessed clinical outcome measurements. KT-1000 arthrometer measures demonstrated a mean (± standard deviation) of 0.26 ± 1.11 mm side to side difference compared to the contralateral side with maximum manual stress applied. Conclusions: Our data demonstrating significant improvements in clinical outcome assessments coupled with excellent KT-1000 arthrometer values and a low rate of clinical failure supports the use of tibialis anterior allografts with an anteromedial portal surgical approach in ACL reconstruction. This improvement in results may be related to more accurate anatomic tunnel placement via AMP drilling and improved graft fixation methods. © 2016 Elsevier B.V. All rights reserved.
1. Introduction Anterior cruciate ligament (ACL) reconstruction is now the sixth most commonly performed orthopedic procedure [28] and that number has been increasing annually [20,14]. Allografts have increasingly been chosen for ACL reconstruction and have several advantages including the absence of donor site morbidity, shorter operative times, improved cosmesis, easier rehabilitation, cost-effectiveness, decreased postoperative pain, and slightly less range of motion loss [5,6,13,25]. The patellar tendon and Achilles, both of which have bony attachments, have been the focus of the majority of allograft research. There is less information in the literature on the use of soft tissue allografts. Despite this, the use of a tibialis anterior tendon is an appealing graft choice for ACL reconstruction. The tendon has superior biomechanical (structural, material, and viscoelastic) properties [11]. According to the 2013 AOSSM ACL Reconstruction survey, tibialis anterior allograft is the most commonly used allograft in primary ACL reconstructions for the adult recreational athlete [1*].
⁎ Corresponding author at: 333 East 38th Street, New York, NY 10016, USA. E-mail address: [email protected] (S.D. Shamah).
The current data on the use of tibialis anterior allograft is both limited and controversial. Prior studies in the sports medicine literature have demonstrated poor clinical outcomes following ACL reconstruction using tibialis anterior allografts. In a study of 69 patients, Singhal et al. reported high rates of subsequent surgery, including a high rate of revision Anterior cruciate ligament reconstruction (ACLR) for graft failure [29]. In a smaller, more recent study, Shybut et al. reported a large number of patients reporting fair or poor outcome scores with demonstration of residual laxity [28]. One of the limitations associated with the prior studies investigating the use of tibialis anterior allografts in ACL reconstruction is the approach used by surgeons to drill the femoral tunnel. There are two techniques that are commonly used for drilling the femoral tunnel, the transtibial technique (TT) and the anteromedial portal (AMP) approach. Use of the AMP approach is an emerging trend based on the ability to better restore ACL anatomy by drilling the femoral tunnel more centrally in the ACL footprint [16,9,33]. The AMP approach has been associated with better rotational stability and anterior translation compared to the TT technique [9]. The prior tibialis anterior allograft studies analyzed patients whose femoral tunnels were drilled using the transtibial technique. While a number of studies have compared the two femoral tunnel drilling approaches using other graft choices [9,22,26,15], at
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Please cite this article as: Capo J, et al, Clinical outcomes of ACL reconstruction with tibialis anterior allograft using an anteromedial portal approach, Knee (2016), http://dx.doi.org/10.1016/j.knee.2016.06.002
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this time, no study in the literature has been dedicated to analyzing the anteromedial portal approach with tibialis anterior allograft for ACL reconstruction. The purpose of the current study was to evaluate the clinical and functional outcomes of ACL reconstruction with tibialis anterior allograft using the anatomic anteromedial portal approach and aperture sheath and screw fixation. These recent advancements in surgical technique and graft fixation methods have led to improvements in ACL reconstruction with low failure rates and high levels of return to athletic activity. Due to these improvements, we hypothesized that our patients would demonstrate excellent knee outcome scores, low failure rates in addition to excellent stability on arthrometric testing. 2. Methods After obtaining approval from our Institutional Review Board, we retrospectively evaluated primary ACL reconstructions with tibialis anterior allograft using an anatomic anteromedial portal approach performed at our institution between January 2011 and February 2014. Subjects were identified from physician surgical logs and office records. All patients were skeletally mature and had magnetic resonance imaging of the affected knee demonstrating complete anterior cruciate ligament rupture. All patients had femoral and tibial tunnel graft fixation using a sheath and screw system (Intrafix, DePuy Mitek Inc., Raynham, MA). Allografts treated with low dose gamma radiation and allografts that were aseptically processed without treatment of low dose gamma radiation were both used. Patients were required to have undergone the specific procedure at least two years prior to follow-up, and were required to be at least 18 years old at time of follow-up. Exclusion criteria included patients younger than 18 years old, patients with incomplete chart information, and patients with previous reconstructive surgery on their knee. Over that period, fifty-five patients met the inclusion criteria. Forty-five patients agreed to come back to the office and participate in the study. All patients followed the same rehabilitation protocol. Some milestones included running straight ahead at three months, and full return to sport at 10 months. At the time of follow-up, a complete physical examination of the knee was performed including assessments of the Lachman and pivot-shift tests and range of motion. A KT-1000 Arthrometer (MEDmetic Corporation, San Diego, CA) was used to measure anterior tibial translation in both knees. Anterior tibial translation was measured at three different stress values: 15 lb, 20 lb, and with maximum manual stress applied. Clinical outcome scores were generated using the International Knee Documentation Committee (IKDC) score, Lysholm score, Kujala score, and Single Assessment Numerical Evaluation (SANE) score. Return to play activity levels were assessed using the Tegner Activity score. Patients were asked to compare their activity levels pre-injury and at final follow-up based on the Tegner activity scale (1 to 10). Post-op radiographs were analyzed for femoral tunnel angle measurements. Finally, patients were asked if they were satisfied with the surgery and whether or not they would have the same procedure using the same graft again, if necessary. Statistical analysis was done using SPSS Statistics Version 18.0 (IBM Inc., Chicago, IL, USA) for all data processing and statistical analyses. Statistical significance was set at p b 0.005.
Figure 1. A bar chart depicting the age distribution of the cohort. Mean age was 43.9 years (range, 25.7 to 69.7 years).
all assessed parameters. The mean IKDC score improved from 32.9 to 86.4 (p b .001). The mean Lysholm score improved from 35.4 to 90.7 (p b .001). The mean Kujala score improved from 46.8 to 91.3 (p b .001). The mean follow-up SANE score was 85.3. See Figure 2. The mean Tegner score decreased from 5.9 pre-injury to 5.3 at final follow-up (p = .007). Thirty-five out of forty-three (81.4%) patients reported getting back to within one level of their pre-injury activity. Overall, 41/43 (93.44%) patients reported that they are happy with their recovery and would have the same surgery with the same graft again, if necessary. Of the 45 allografts utilized, 27 were treated with low dose gamma radiation and 18 were processed aseptically without radiation treatment. No significant differences were found in outcomes between the radiated and non-radiated grafts. Of the two grafts that ruptured, one graft was treated with gamma radiation and one graft was not. KT-1000 arthrometer measures demonstrated a mean of 0.26 ± 1.11 mm (range, −2 to 3) side to side difference compared to the contralateral side with maximum manual stress applied. The mean femoral tunnel angle measured was 135.1 (range, 126.0 to 143.0). The mean graft size diameter used as measured by a graft sizer in the operating room was 8.9 mm (range, 8.0 to 10.0). 4. Discussion The prior literature on tibialis anterior allograft as a graft choice is limited and conflicting. There are three previous studies that reported poor outcomes for ACLR with tibialis anterior allograft. Singhal et al. reported in 2007 unfavorable results in a study of 69 patients (mean age: 31.7 years). Femoral tunnel drilling in this study was done using the transtibial technique and graft fixation was obtained using interference screws. Overall, 16 of the 69 patients (23.2%) required ACL revision for graft failure at a mean of 22 months (range, five to 47 months) following the initial surgery. Twenty-six patients (38%) required additional
3. Results Forty-five patients with a mean age of 43.9 years (range, 25.7 to 69.7 years) were available for complete follow-up at a mean of 30.8 months post-ACLR (range, 24.0 to 45.0 months). Age distribution can be seen in Figure 1. Of the 45 patients who came in for follow-up, two were found to have a clinical failure/ruptured graft (4.44%). The ages of the two patients whose graft failed were 36.3 and 33.5 years old. For the 43 (18 males, 25 females) remaining patients, significant improvements were noted to be present compared to baseline values for
Figure 2. A bar chart depicting pre-operative and post-operative outcome scores. All scores showed significant improvement (p b .001).
Please cite this article as: Capo J, et al, Clinical outcomes of ACL reconstruction with tibialis anterior allograft using an anteromedial portal approach, Knee (2016), http://dx.doi.org/10.1016/j.knee.2016.06.002
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surgery, which included one knee arthroplasty. The mean age of failed patients was 22.8 years. The investigators attributed their high failure rate to using a graft with slow incorporation, use of an accelerated rehabilitation program, early return to sport, and an active, high demand patient population. In their conclusion they cautioned against using tibialis anterior allograft for younger or higher demand patients. Smith et al. reported results of 19 ACL reconstructions (mean age 37 years) with soft tissue allografts [31]. Ninety percent of their allografts were tibialis anterior. They were analyzed using roentgen stereophotographic analysis with each operative knee serving as its own control. The mean increase in laxity was 1.1 mm at six months. Total graft slippage averaged 1.9 mm at four months and 21% of the cohort had a laxity increase of three millimeters or more. However, these patients reported excellent outcome scores. Femoral tunnel drilling was done using the transtibial technique and graft fixation was accomplished using the EZloc femoral fixation device (Arthrotek, Inc., Warsaw, IN). Most recently, Shybut et al. reported unfavorable outcomes for 19 patients (mean age 39.9). They reported that only 65% of patients achieved good or excellent results based on functional outcome scores. 4/19 patients (21.1%) had laxity on physical exam with a KT-1000 sideto-side difference greater than five millimeters. Their analysis did not reveal a significant correlation between age and outcome. Femoral tunnel drilling was done using the transtibial technique, and DePuy Mitek Rigidfix or Arthrex Transfix devices were used for femoral fixation. In contrast, Nyland et al. showed positive results in a cohort of 18 patients who underwent tibialis anterior ACL reconstruction with interference screw fixation [24]. They did not comment on which technique was used for the femoral tunnel drilling. Seventeen out of eighteen patients (94.4%) had a normal or near normal IKDC clinical examination scores, with mean side-to-side difference on KT-1000 testing of 1.1 mm. All patients returned to their pre-injury level of activity, which the investigators described as moderate. The investigators recommended the use of tibialis anterior allograft in ACLR suggesting that its superior biomechanics may make it a promising graft choice for patients, including younger and high demand patients. Edgar et al., Nakata et al., and Carey et al. also published studies reporting good outcomes for soft tissue allografts [8,23,3]. However, they focused on hamstring and Achilles (without bone plug) allografts and not tibialis anterior. Our patient population resembled the cohorts of Shybut and Singhal. However, unlike any of the previous studies femoral tunnel drilling was performed using the anteromedial portal technique. Our patients showed excellent outcomes on subjective outcome scores and KT1000 arthrometer testing. From these results, we recommend using a tibialis anterior allograft for ACL reconstruction, provided that the femoral tunnel is drilled via the anteromedial portal. We believe that the use of an anteromedial portal aids in placement of the femoral tunnel in the vital location of the anatomic footprint of the ACL origin. Reestablishing the anatomic femoral origin of the ACL is essential when undergoing ACLR with tibialis anterior allograft. Recent emphasis has been placed on more anatomic tunnel positioning in ACL reconstruction, aimed at controlling both anterior tibial translation and tibial rotation [9]. To better restore ACL anatomy, the emerging trend is to drill the femoral tunnel more centrally in the ACL footprint, slightly lower on the wall of the lateral femoral condyle and more anterior than when performing a standard transtibial technique [22,12,34]. The presumption being that a more horizontally oriented graft, as opposed to a vertical graft, will optimize rotary as well as translational stability [21,30,27]. Trying to accomplish this by drilling the femoral tunnel through the use of the transtibial technique may be complicated. Therefore, the use of an anteromedial portal (AMP) has been proposed to drill the femoral tunnel separately in a more horizontal location, achieving adequate tunnel length for fixation and incorporation into the bone [4,1,32].
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Figure 3. An anteroposterior view of a post-operative X-ray following ACL reconstruction using the anteromedial portal approach, which allows for a more anatomic positioning of the allograft. The outlines of the femoral and tibial tunnels are visible.
This portal allows for precise placement of the guidewire and proper visualization of the ACL footprint. In contrast to the traditional transtibial technique, when the tunnel is drilled through the anteromedial portal, the tunnel aperture is shallow and inferior, closer to the center of the footprint and in a more anatomic position [10,7]. This improves the kinematics of the knee [17,18]. When the tunnels are drilled independently, the risk of posterior wall blowout is low [2]. The remaining ACL fibers may be preserved, the interference screws may be placed parallel to the bone plug with no lateral incisions, and single-bundle, double-bundle, and revision procedures may be easily performed [19]. Femoral tunnel placement through the AMP allows better assessment intraoperatively so that the graft placed is the center of the native footprint properly without excess stresses or loads. The ultimate goal of anatomic reconstruction is to place the ACL graft at a more anatomic location on both the tibia and femur. Franchesi et al. reported that femoral tunnel drilling through the AMP improves anteroposterior laxity and rotational stability of the knee, and patients are more likely to return to their pre-operative sport activity [9]. They also found that position of the center of the ACL was lower and more anterior when using an AMP as opposed to the transtibial technique. This was evidence to the belief that the AMP respects the native ACL anatomy and position. A direct effect of drilling the femoral tunnel through the anteromedial portal can be seen from the femoral tunnel angle with respect to the femoral condyles. The femoral tunnel can be seen on post-operative X-rays, with the outline of the tunnel lucent (Figure 3). This result is evidence to the advantageous aspect of the anteromedial portal. The mean femoral tunnel angle measured was 135.1 (range, 126.0 to 143.0), which corresponds to 10:30 and 1:30 on a clock face for right and left knees respectively. See Figure 3. There were some limitations in our study. Our cohort of patients was not as large as some of the previous studies. We did not have many patients that were younger than 30 at the time of surgery. As this study only enrolled patients with tibialis anterior allograft grafts, we cannot directly compare these results to other grafts (ex: BTB autograft) and can only use historical controls. We also cannot directly compare these results to the transtibial technique and need to rely on historical controls. Additionally, future research should continue to analyze the effect that different fixation devices have on outcomes as well as how the modified transtibial technique compares to the anteromedial portal approach. 5. Conclusion Our data demonstrating significant improvements in all clinical outcome assessments coupled with excellent KT-1000 arthrometer values and a low rate of clinical failure supports the use of tibialis anterior
Please cite this article as: Capo J, et al, Clinical outcomes of ACL reconstruction with tibialis anterior allograft using an anteromedial portal approach, Knee (2016), http://dx.doi.org/10.1016/j.knee.2016.06.002
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Web references [1⁎] The American Orthopaedic Society for Sports Medicine Allografts for ACL reconstruction Survery report. https://www.sportsmed.org/AOSSMIMIS/members/downloads/ research/AllograftACLReconstructionSurveyReport.pdf.
Please cite this article as: Capo J, et al, Clinical outcomes of ACL reconstruction with tibialis anterior allograft using an anteromedial portal approach, Knee (2016), http://dx.doi.org/10.1016/j.knee.2016.06.002