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 Table of Contents  
Year : 2021  |  Volume : 4  |  Issue : 2  |  Page : 42-46

Graft diameter as a predictor for functional outcome following arthroscopic anterior cruciate ligament reconstruction: A prospective study

1 Department of Orthopaedics, AIIMS, Patna, Bihar, India
2 Department of Orthopaedics, NMCH, Patna, Bihar, India

Date of Submission25-Jun-2021
Date of Decision19-Jul-2021
Date of Acceptance20-Jul-2021
Date of Web Publication26-Aug-2021

Correspondence Address:
Dr. Ravi Kumar
Department of Orthopaedics, NMCH, Patna, Bihar
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jodp.jodp_9_21

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Background: The purpose of the study was to find the effect of autologous hamstring tendon graft size on patient reported outcome (PRO) measures following Arthroscopic Anterior cruciate ligament (ACL) reconstruction. Materials and Methods: A review of prospectively collected cohort data of 90 patients who had undergone primary ACL reconstruction using hamstring tendon autograft was evaluated. Patient's age, sex, graft diameter at the time of surgery, and minimum of 2 years postoperative functional outcome were assessed using PRO measures, i.e. Tegner Lysholm Knee (TLK) Scoring Scale, Knee Injury and Osteoarthritis Outcome Score (KOOS), and International Knee Documentation Committee score. Mean of the three scores was calculated along with that of graft diameter, and Pearson correlation coefficient was calculated to find the relation between graft diameter and the three-PRO measure scores independently. Two-tailed test was used to compute the statistical significance of parameter inferred from the data sheet. Results: There was a positive linear correlation between the graft diameter and three PRO measures independently; however, two-tailed tests for statistical significance were significant only for TLK Score and KOOS. Conclusion: We conclude that hamstring autograft diameter is one of the important predictor for postoperative functional outcome, and hence, a thicker diameter graft is desirable.

Keywords: Anterior cruciate ligament reconstruction, graft diameter, International Knee Documentation Committee score, Knee Injury and Osteoarthritis Outcome Score, Tegner Lysholm Knee Scoring Scale

How to cite this article:
Kumar S, Kumar A, Kumar R. Graft diameter as a predictor for functional outcome following arthroscopic anterior cruciate ligament reconstruction: A prospective study. J Orthop Dis Traumatol 2021;4:42-6

How to cite this URL:
Kumar S, Kumar A, Kumar R. Graft diameter as a predictor for functional outcome following arthroscopic anterior cruciate ligament reconstruction: A prospective study. J Orthop Dis Traumatol [serial online] 2021 [cited 2021 Dec 6];4:42-6. Available from: https://www.jodt.org/text.asp?2021/4/2/42/324622

  Introduction Top

Anterior cruciate ligament reconstruction (ACLR) is one of the most commonly performed arthroscopic surgeries in orthopedics.[1] Among various graft options available like bone – patellar tendon – bone autograft, quadriceps tendon autograft, and hamstring tendon autograft; use of hamstring tendon autograft has increased due to similarly good results as compared to other while also resulting in decreased donor side morbidity and improved fixation methods.[2],[3],[4],[5] Cadaveric analysis has shown a linear correlation between maximum load to failure and graft cross sectional area,[6] and these findings has been corroborated in several clinical studies too.[7],[8],[9] The harvested hamstring tendon graft is not always of a desired diameter; sometimes, an excessively thin graft is obtained.[10] There are evidences to suggest that graft tensile strength is highly dependent on graft diameter.[11] This is important for hamstring graft as it is an all soft-tissue graft as opposed to bone patellar bone graft which allows direct bone-to-bone healing in the tunnel. However, hamstring tendon remains the most popular choice for autograft in ACLR.[12] Studies have found that hamstring grafts lead to better preservation of extension, higher patient reported outcome (PRO) scores, and less radiographic evidence of osteoarthritis.[13] Clinically, grafts with a diameter <7 mm have been associated with an increased rate of early revision.[14] Literature in our knowledge has limited report showing correlation between the diameter of quadruple hamstring autograft and functional outcome assessment using three PRO measures i.e. Tegner Lysholm Knee (TLK) Scoring Scale, Knee Injury and Osteoarthritis Outcome Score (KOOS), and International Knee Documentation Committee (IKDC) after ACLR.

The purpose of this study was to find out the effect of graft size on PRO measures following anatomical ACLR using quadruple hamstring autograft. Our hypothesis is that autograft hamstring diameter has an effect on the clinical outcome following ACLR. The study is first of its kind in the Indian sub-continent.

  Materials and Methods Top

A review of prospectively collected cohort data of 90 patients (consecutive series of patients) who had primary ACLR using quadruple looped hamstring autograft (semitendinosus and gracilis) between January 2016 and April 2018 was done. This research had been approved by the IRB of the authors' affiliated institutions. The data collected from the medical records department provided patients age, sex, graft used with its diameter, and surgical technique. These data were supplemented with prospectively collected PRO measures: TLK, KOOS, and IKDC score at 3, 6, 12, and 24 months, postoperatively. In this study, we included skeletally mature patient with ACL tear and minimum of 2 years' follow-up. The exclusion criteria included bilateral ACL tear, meniscal injury, associated ligament injury like medial collateral ligament, lateral collateral ligament, posterior cruciate ligament or injury involving posterolateral corner, previous history of ACL repair or reconstruction. In our study, failure was defined as complaint of instability with clinical grade 2 + Lachmann, and/or revision surgery.

A surgical team with single-lead surgeon (experience ≥10 years of arthroscopic surgeries) did all the surgeries at a teaching hospital. After anesthesia, the patient was kept in the supine position with digital tourniquet applied high up on the thigh. A bolster was placed at foot end to keep the knee at 90° flexion and a side support at the level of the tourniquet to prevent falling of the limb sideways and to use it as a fulcrum to apply a valgus force at the knee. Diagnostic arthroscopy was performed and associated injury to meniscus or articular cartilage was noted. Any patient with associated ligament injury or meniscal injury was treated accordingly but was not included in this study. Ipsilateral semitendinosus and gracilis graft were harvested using longitudinal incision over the anteromedial aspect of proximal tibia; graft was prepared over graft preparation board and Fiber wire® (Arthrex) suture was used for preparing the tendon in all the cases. Quadrupled hamstring (semitendinosus and gracilis) was used in all the patients. The prepared tendon was sized, measurements noted and graft attached to the tensioning device over the graft preparation board. Through the standard anteromedial portal, a beath pin was placed at the center of femoral ACL footprint keeping in mind the remnants of the native ACL. We had used the surgical technique as described by S. Kumar et al.[15] For accurate positioning of femoral and tibial tunnel using the indigenously made grid on a transparency sheet and C-arm. Cortical suspensory fixation with adjustable loop endobutton was used to fix graft tendon to femoral side while aperture fixation with bio absorbable interference screw as appropriate to tunnel diameter done to fix graft tendon to tibial side in all the cases.

The patient was made to stand full weight from the postoperative day 1 and start active knee mobilization along with quadriceps strengthening exercises. All patients followed similar standard hospital ACL rehabilitation protocol.

Scheduled follow-ups were at 3, 6, 12, and 24 months postoperatively. Patients were evaluated objectively with Lachmann test, measurement of range of motion and PRO measures i.e. TLK, KOOS, and IKDC scores.

Statistical analysis was performed using the IBM SPSS Statistics for Windows, Version 25.0. Armonk, NY: IBM Corp. Mean of age, PRO measures, and graft diameters was calculated. Pearson correlation coefficient was measured to find out relation between graft diameter and the three PRO independently. Two-tailed test was used to compute the statistical significance of parameter inferred from data sheet.

  Results Top

There were 90 cases in this cohort; 85 male (94.44%) and 5 female (5.56%) with age ranging from 17 years to 50 years with a mean age of 28 years. The graft diameter ranged from 6 to 10 mm with mean of 8 mm. The number of patients with various graft diameters is shown in [Figure 1]. In our series, the minimum follow-up was of 2 years.
Figure 1: Number of patients with various graft diameter

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The PRO scores at the end of 2 years were taken into consideration. TLK scores range from 0 (worse disability) to 100 (less disability). IKDC scores have possible score range 0–100, where 100 means no limitation with daily or sporting activities and the absence of symptoms. Similarly, KOOS score range from 0 to 100, with 0 representing extreme problems and 100 representing no problems. The mean of TLK, IKDC, and KOOS scores was 89.54, 66.57, and 84.89, respectively.

Pearson correlation had positive linear correlation between graft diameter and TLK score, graft diameter and IKDC score, graft diameter and KOOS score, but the two-tailed test for statistical significance was significant only for TLK and KOOS scores, thereby implying that although with the increase in graft diameter all the three subjective score increases but that is significant only for TLK and KOOS scores [Table 1].
Table 1: Correlation between graft diameter and various scores

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We had two patients who were failure in our study; first patient (P1) (20 years/male) had graft diameter of 6.5 mm while 7 mm in the second patient (P2) (28 years/male). P1 on follow-up at 2 years had TLK score as 90, IKDC score as 48 and KOOS score as 85. Surprisingly, the TLK and KOOS scores were comparable to mean of total TLK and KOOS scores at 2 years of follow-up. For P2 TLK, IKDC and KOOS scores at 2 years' follow-up were 72, 57, and 85, respectively; TLK and IKDC scores were low as compared to total mean while KOOS score was at par.

  Discussion Top

There are various factors such as age, sex, height, weight, BMI, thigh circumference, activity level, initial injury mechanism, associated injury, graft diameter, and type of reconstruction which are of paramount importance in bringing about desired outcome. Among various autograft options for ACLR, hamstring has become very popular among knee surgeons. Various anatomical studies have revealed that the diameter of the normal ACL varies from 6 to 12 mm (mean: −11 mm).[14],[16] Since ample length and diameter of the graft assists in accelerated rehabilitation and reduce risk of graft re-rupture, so achieving the desired dimension is of paramount importance for a good long-term outcome following ACLR.

Literature has quite a good number of clinical data in support of large diameter autograft. Our findings are in accordance to a Multicenter Orthopedic Outcomes Network cohort study which was the first study to relate graft size to PRO scores and had concluded that smaller hamstring autograft size is a predictor of poorer KOOS sport/recreation function at 2 years after primary ACL reconstruction.[7]

Our findings are overall in agreement with other research work which assessed relation between graft diameter and risk of revision. Magnussen et al.[14] concluded that use of hamstring autografts 8 mm in diameter or less in patients aged <20 years is associated with higher revision rates. This was further endorsed in a systematic review which concluded that a graft of at least 8 mm should be used to decrease the risk of having a failure following hamstring ACLR.[17] However, another study published in 2016 concluded that there is a significant relationship between hamstring autograft diameter and the likelihood for revision ACLR.[18]

As the factors affecting knee stability following ACLR is multifactorial, a biomechanical study carried out by Bedi et al.[19] showed that increasing graft size did not increase stability at the time of reconstruction. They also showed that increasing graft size did not compensate for poor stability produced by malposition of the tunnels; concluding that anatomic reconstruction is far more important than graft size at least for the time-zero stability. To minimize tunnel malposition, we had used the technique as described by Kumar et al.[15]

On the contrary, several studies have not been able to find correlation between graft diameter and knee laxity. Tohyama et al.[20] while evaluating gender-based differences in outcome after anatomic double-bundle ACL reconstruction with hamstring tendon autografts found that although females had significant smaller graft diameter but assessment for ligament laxity at the 2-year postoperative evaluation in the female group were approximately identical to those of the male group. This was again endorsed by Park et al.[8] who did not find statistically significant differences in clinical result and knee stability to exist between the groups when patients were divided by the diameter of four-strand graft into those of below 7.5 mm (Group 1, 149 patients) and those of 7.5 mm or more (Group 2, 147 patients) and concluded that small graft diameter did not necessarily increase instability and the risk of re-tear, but noted that a diameter of 8.0 mm or more was expected to provide better results. Similarly, Kamien et al.[9] concluded that statistically significant difference was not found in terms of graft size and activity level correlating with failure rate in ACL reconstruction with hamstring autograft. Recently, a study done by Wernecke et al.[21] concluded that increasing hamstring autograft diameter neither reduced revision rates nor improved clinical outcomes when assessed using TLK, IKDC, and KOOS scores postoperatively.

Hence, the literature is ambiguous in establishing relation between graft diameter and PRO measures. Among various factors that influence the likelihood of success following ACLR, graft selection is one of the basic tenets. In our study, over 31% of patients had graft diameter < 8 mm and although various ways for graft augmentation like using allograft, 5-strand graft by tripling semitendinosus have been advocated, the authors here did not augment grafts in any of the patients.[22] A viable and better alternative is to make graft selection decision a part of preoperative planning for all ACLR and hereby allowing surgeons to choose an ideal graft on an individual basis.[23]

This study has used the most commonly used PRO measures for assessing functional outcome and in authors opinion the literature has limited reports of correlation between graft diameter and assessment of functional outcome postoperatively at the end of 2 years of follow-up. This is first of its kind study in our sub-continent and only study to find statistically significant positive correlation between PRO measures such as TLK, KOOS, and the graft diameter.

This study has some limitations which have to be pointed out like male predominance (94.4%) in gender distribution and short follow-up period.

  Conclusion Top

On the basis of our findings and statistical analysis, we can safely conclude that the graft diameter is an important predictor of functional outcome following ACLR. We feel a practical alternative to avoid intra-operative inadequate graft is that the surgeon should make graft selection a part of preoperative evaluation and be prepared with ACL augmentation techniques.

Data availability statements

The authors confirm that the data supporting the findings of this study are available within the article.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

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Ejerhed L, Kartus J, Sernert N, Köhler K, Karlsson J. Patellar tendon or semitendinosus tendon autografts for anterior cruciate ligament reconstruction? A prospective randomized study with a two-year follow-up. Am J Sports Med 2003;31:19-25.  Back to cited text no. 2
Feller JA, Webster KE. A randomized comparison of patellar tendon and hamstring tendon anterior cruciate ligament reconstruction. Am J Sports Med 2003;31:564-73.  Back to cited text no. 3
Freedman KB, D'Amato MJ, Nedeff DD, Kaz A, Bach BR. Arthroscopic anterior cruciate ligament reconstruction. Am J Sports Med 2003;31:2-11.  Back to cited text no. 4
Laxdal G, Kartus J, Hansson L, Heidvall M, Ejerhed L, Karlsson J. A prospective randomized comparison of bone-patellar tendon-bone and hamstring grafts for anterior cruciate ligament reconstruction. Arthroscopy 2005;21:34-42.  Back to cited text no. 5
Hamner DL, Brown CH Jr., Steiner ME, Hecker AT, Hayes WC. Hamstring tendon grafts for reconstruction of the anterior cruciate ligament: Biomechanical evaluation of the use of multiple strands and tensioning techniques. J Bone Joint Surg Am 1999;81:549-57.  Back to cited text no. 6
Mariscalco MW, Flanigan DC, Mitchell J, Pedroza AD, Jones MH, Andrish JT, et al. The influence of hamstring autograft size on patient-reported outcomes and risk of revision after anterior cruciate ligament reconstruction: A Multicenter Orthopaedic Outcomes Network (MOON) Cohort Study. Arthroscopy 2013;29:1948-53.  Back to cited text no. 7
Park SY, Oh H, Park S, Lee JH, Lee SH, Yoon KH. Factors predicting hamstring tendon autograft diameters and resulting failure rates after anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc 2013;21:1111-8.  Back to cited text no. 8
Kamien PM, Hydrick JM, Replogle WH, Go LT, Barrett GR. Age, graft size, and Tegner activity level as predictors of failure in anterior cruciate ligament reconstruction with hamstring autograft. Am J Sports Med 2013;41:1808-12.  Back to cited text no. 9
Charlton WP, Randolph DA Jr., Lemos S, Shields CL Jr. Clinical outcome of anterior cruciate ligament reconstruction with quadrupled hamstring tendon graft and bioabsorbable interference screw fixation. Am J Sports Med 2003;31:518-21.  Back to cited text no. 10
Boniello MR, Schwingler PM, Bonner JM, Robinson SP, Cotter A, Bonner KF. Impact of hamstring graft diameter on tendon strength: A biomechanical study. Arthroscopy 2015;31:1084-90.  Back to cited text no. 11
Magnussen RA, Granan LP, Dunn WR, Amendola A, Andrish JT, Brophy R, et al. Cross-cultural comparison of patients undergoing ACL reconstruction in the United States and Norway. Knee Surg Sports Traumatol Arthrosc 2010;18:98-105.  Back to cited text no. 12
Mascarenhas R, Tranovich MJ, Kropf EJ, Fu FH, Harner CD. Bone-patellar tendon-bone autograft versus hamstring autograft anterior cruciate ligament reconstruction in the young athlete: A retrospective matched analysis with 2–10 year follow-up. Knee Surg Sports Traumatol Arthrosc 2012;20:1520-7.  Back to cited text no. 13
Magnussen RA, Lawrence JT, West RL, Toth AP, Taylor DC, Garrett WE. Graft size and patient age are predictors of early revision after anterior cruciate ligament reconstruction with hamstring autograft. Arthroscopy 2012;28:526-31.  Back to cited text no. 14
Kumar S, Kumar A, Kumar R. Accurate positioning of femoral and tibial tunnels in single bundle anterior cruciate ligament reconstruction using the indigenously made bernard and hurtle grid on a transparency sheet and C-arm. Arthrosc Tech 2017;6:e757-61.  Back to cited text no. 15
Girgis FG, Marshall JL, Monajem A. The cruciate ligaments of the knee joint. Anatomical, functional and experimental analysis. Clin Orthop Relat Res. 1975 Jan-Feb;(106):216-31. doi:10.1097/00003086-197501000-00033. PMID: 1126079.  Back to cited text no. 16
Conte EJ, Hyatt AE, Gatt CJ Jr., Dhawan A. Hamstring autograft size can be predicted and is a potential risk factor for anterior cruciate ligament reconstruction failure. Arthroscopy 2014;30:882-90.  Back to cited text no. 17
Spragg L, Chen J, Mirzayan R, Love R, Maletis G. The effect of autologous hamstring graft diameter on the likelihood for revision of anterior cruciate ligament reconstruction. Am J Sports Med 2016;44:1475-81.  Back to cited text no. 18
Bedi A, Maak T, Musahl V, O'Loughlin P, Choi D, Citak M, et al. Effect of tunnel position and graft size in single-bundle anterior cruciate ligament reconstruction: An evaluation of time-zero knee stability. Arthroscopy 2011;27:1543-51.  Back to cited text no. 19
Tohyama H, Kondo E, Hayashi R, Kitamura N, Yasuda K. Gender-based differences in outcome after anatomic double-bundle anterior cruciate ligament reconstruction with hamstring tendon autografts. Am J Sports Med 2011;39:1849-57.  Back to cited text no. 20
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Amini MH, Prieto JF. Biologic and mechanical augmentation in anterior cruciate ligament reconstruction: Fibrin clot augmentation of 5-strand hamstring autograft. Arthrosc Tech 2017;6:E1851-5.  Back to cited text no. 22
Cobanoglu M, Ozgezmez FT, Omurlu IK, Ozkan I, Savk SO, Cullu E. Preoperative magnetic resonance imaging evaluation of semitendinosus tendon in anterior cruciate ligament reconstruction: Does this have an effect on graft choice? Indian J Orthop 2016;50:499-504.  Back to cited text no. 23
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