SEMS-journal
Original article
published online on 03.04.2024https://doi.org/10.34045/SEMS/2024/1
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Predicting four-stranded hamstring graft size using anthropometrics in the Vietnamese population

exercise is medicine

Nguyen Thanh Tan1,2, Nguyen Huu Dat1, Tran Quang Son1,2,3, Tran Nguyen Anh Duy1,2,4, Ly Huynh Vinh Hung1, Nguyen Tu Thai Bao1,2,4
1 Department of Orthopedics, Faculty of Medicine, Can Tho University of Medicine and Pharmacy, Can Tho, Vietnam
2 Department of Orthopedics and Trauma, Can Tho University of Medicine and Pharmacy Hospital, Can Tho, Vietnam
3 Doctor of Philosophy Program, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
4 The International Graduate Program in Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan

Abstract
Background: This research aims to establish a relationship between anthropometric measurements and the dimensions of four-stranded hamstring autografts within the Vietnamese population.

Methods: We conducted a cross-sectional study on patients diagnosed with anterior or posterior cruciate ligament ruptures and underwent arthroscopic reconstruction using four-stranded hamstring autografts from September 2020 to September 2022. The investigation examined whether there was a correlation between the gender, height, weight, body mass index, femoral length, or thigh circumference of patients and the dimensions of the grafts.

Results: 50 patients (36 males, 14 females, an average age of 32.96 ± 1.46) were included in this study. Weight correlated most significantly with graft diameter, followed by height and BMI. A significantly strong correlation existed between height and graft length, and height was essential in predicting that length. Graft diameter, which strongly correlates with the combination of sex, weight, and height (F = 20.7, R2 = 0.55, p < 0.001) can be predicted by height, weight, or BMI through subsequent linear regression analysis with ­significant values.

Conclusions: The dimensions of four-stranded hamstring autografts exhibit noteworthy correlations with anthropometric variables. These statistical relationships offer valuable insights for orthopedic specialists, enabling them to predict graft sizes, enhance planning, and reduce the likelihood of complications during reconstruction.

Résumé
Contexte: Cette étude vise à établir une relation entre les mesures anthropométriques et les dimensions des autogreffes d’ischio-jambiers à quatre brins au sein de la population vietnamienne.

Méthodes: Nous avons mené une étude transversale sur des patients diagnostiqués avec des ruptures du ligament croisé antérieur ou postérieur et ayant subi une reconstruction arthroscopique à l’aide d’autogreffes d’ischio-jambiers à quatre brins de septembre 2020 à septembre 2022. Nous avons examiné s’il existait une corrélation entre le sexe, la taille, le poids, l’indice de masse corporelle, la longueur du fémur ou la circonférence de la cuisse des patients et les dimensions des greffes.

Résultats: 50 patients (36 hommes, 14 femmes, âge moyen de 32,96 ± 1,46) ont été inclus dans cette étude. La corrélation entre le poids et le diamètre du greffon est la plus significative, suivie de la taille et de l’IMC. Il existe une corrélation très forte entre la taille et la longueur du greffon, et la taille est essentielle pour prédire cette longueur. Le diamètre du greffon, qui est fortement corrélé à la combinaison du sexe, du poids et de la taille (F = 20,7, R2 = 0,55, p < 0,001) peut être prédit par la taille, le poids ou l’IMC grâce à une analyse de régression linéaire ultérieure, avec des valeurs significatives.

Conclusions: Les dimensions des autogreffes d’ischio-jambiers à quatre brins présentent des corrélations notables avec les variables anthropométriques. Ces relations statistiques offrent des informations précieuses aux orthopédistes, leur permettant de prédire la taille des greffons, d’améliorer la planification et de réduire la probabilité de complications lors de la reconstruction.

Mots-clés: ligament croisé antérieur, ligament croisé postérieur, greffe d’ischio-jambier à quatre brins, paramètres ­anthropométriques, autogreffe

Introduction

The susceptibility of anterior and posterior cruciate ligaments to injuries in sports or traffic accidents is well-established. Isolated anterior cruciate ligament (ACL) injuries are predominant among knee injuries, accounting for 64% of knee-related injuries [1]. Conversely, isolated posterior cruciate ligament (PCL) injuries are less frequent. Both ACL and PCL injuries may lead to posttraumatic osteoarthritis, resulting in chronic pain, limited function, and a reduction in the quality of life [2,3]. Cruciate ligament reconstruction is often recommended to prevent the progression of osteo­arthritis and enable patients to regain their pre-injury activity level [4]. However, the long-term impact of ACL and PCL reconstruction surgery on the incidence of knee osteo­arthritis requires further investigation [5,6].
Various graft options, such as hamstring autograft, bone-patellar tendon-bone graft, quadriceps tendon graft, allograft, or synthetic graft, are available for cruciate ligament reconstructions. Studies indicate that 45-89% of orthopedic and knee surgeons opt for hamstring tendon grafts in ACL and PCL reconstruction [7-9]. Furthermore, four-stranded hamstring grafts are biomechanically considered the strongest grafts [10]. Research suggests that a minimum graft diameter of 7 mm, with a minimum length of 8 cm for ACL reconstruction or 9 cm for PCL reconstruction, can reduce the failure rate [11-14]. However, clinical studies and Magnetic Resonance Imaging (MRI) evidence reveal significant variability in graft diameter among the population [13,15-18]. The drawback of using a hamstring autograft is its potentially smaller size, posing operational challenges and increasing the risk of postoperative failure. Therefore, predicting graft size preoperatively becomes crucial for selecting fixation methods or grafts.
Recent studies have explored methods to predict graft size for cruciate ligament reconstructions, especially in the case of four-stranded hamstring autografts [9,15,19]. In Vietnam, where four-stranded hamstring autografts are commonly employed in ACL and PCL ligament reconstruction, there is a lack of research guiding the prediction of graft size based on anthropometric measurements specific to Vietnamese ­patients. Hence, this study aims to establish the correlation between anthropometric variables (sex, body height, body weight, corresponding body mass index (BMI), femur length, and thigh circumference) and the dimensions of four-stranded hamstring grafts.

Methods

This cross-sectional study was conducted in our hospital from September 2020 to September 2022. The research was approved by the Scientific Review Committee of Can Tho University of Medicine and Pharmacy (Number 1207/DHYDCT issued on August 21st, 2020). Participants were informed of the purpose and procedure and voluntarily signed an informed consent form.
Our present study includes posttraumatic knee patients aged 18 to 60 who require an ACL or PCL reconstruction using a four-stranded hamstring autograft. Exclusion criteria were patients with a severe pathological background, deformation diseases, nutritional disorders, tendinopathies, tendon harvesting failure, or patients with degenerative diseases. Our patients were diagnosed with ACL or PCL ruptures under physical examination and confirmed with MRI. The demographics of patients included sex, age, mode of injury, and anthropometric data, including height (centimeter), weight (kilogram), BMI (kg/m2), femur length (centimeter), and thigh circumference (centimeter). Femur length was determined by measuring from the greater trochanter’s apex to the lateral femoral condyle. We measured the thigh circumference at a level of 15 cm proximal to the upper outer edge of the knee joint. Patients were explained to have ACL and PCL reconstruction using hamstring tendon autografts.
One certified knee arthroscopy surgeon did all surgeries using the OLIBAS harvesting technique described in the previous paper [1]. We used an anteromedial incision over the proximal tibial to expose the pes anserinus with the gracilis and semitendinosus tendons exposure. We carefully harvested both tendons with a tendon stripper. After removing fat and muscle tissue within the tendon, both tendons were done using the four-stranded method (Figure 1). To prepare autograft, free ends of the gracilis and semitendinosus tendons were whipstitched together with nonabsorbable sutures. The graft was then passed through a loop and folded in the middle. A standard graft-diameter block with 0.5-mm increments measured the graft diameter (millimeter). The final diameter was considered the smallest dimension the graft could go through. The graft length (centimeter) using the ruler on the drill bit. The final length was measured from end to end. A single-bundle ACL or PCL reconstruction was then carried out. The relationship between the anthropometric measurements and the graft size was then analyzed.
Data were calculated using Statistical Package for Social Sciences (SPSS) version 24.0 (IBM Corp., New York, the United States of America) for Windows. Descriptive statistics were used to demonstrate categorical data (proportions and frequencies) and continuous variables (means, standard deviations). Pearson’s correlation test detected the relationship between anthropometric measurements and graft dia­meter or length. In cases where a positive correlation was observed, simple linear regression analysis was applied to estimate the linear relationships. Multiple linear regression was used to predict graft diameter from sex, height, and weight. The results were considered statistically significant with the p value < 0.05.

Results

Table I demonstrated the baseline characteristics of the participants, including demographics and anthropometric data. After excluding five patients due to the lack of some anthropometric measurements, our study shows 50 patients, with a majority of males and a minority of females. The average age spanned from young adulthood to middle age. The average weight and height were within typical ranges, and the average BMI fell within the healthy range. Injuries were predominantly related to sports and vehicular accidents. The majority of patients were diagnosed with anterior cruciate ligament ruptures. Femur length, thigh circumference, and graft dimensions were recorded for analysis.
Table II demonstrated Pearson’s correlation analysis of the anthropometric measurements with four-stranded hamstring graft diameter and length. It revealed that with the graft diameter, the patient’s weight had a strong positive correlation (r = 0.73, p < 0.001), height (r = 0.54, p < 0.001), and BMI (r = 0.51, p < 0.001) had moderate positive correlations. On the other hand, high circumference showed a weak positive correlation with the graft diameter (r = 0.50, p < 0.001).

Figure 1: Illustration of the simple linear regression between the graft diameter and anthropometric measurements(BMI, height, weight, and thigh circumference with corresponding A, B, C, and D).
Figure 1: Illustration of the simple linear regression between the graft diameter and anthropometric measurements (BMI, height, weight, and thigh circumference with corresponding A, B, C, and D).
Figure 2: Illustration of the simple linear regression between the graft length and height.

The subsequent simple linear regressions were performed between the graft diameter and anthropometric characteristics including BMI, height, weight, and thigh circumference, which were demonstrated respectively in Figures 1-A, 1-B, 1-C, and 1-D. Height was a significant measurement to ­predict graft length with a strong association (r = 0.67, p < 0.001). There were no significant correlations between femur length with the graft diameter and length, also BMI and thigh circumference with the graft length.
Subsequent linear regression analysis indicated that height (R2 = 0.28, p < 0.001), weight (R2 = 0.52, p < 0.001), and BMI (R2 = 0.25, p < 0.001) had a significant value in predicting graft diameter. Multiple regression analysis investigated the optimal linear combination of variables for predicting the doubled-stranded hamstring graft diameter. Weight and height had a significant regression result with F = 17.23, R2 = 0.55, and p < 0.001. Height was essential in predicting graft length (R2 = 0.44, p < 0.001) (Figure 2).
We also found that sex confounded the relationship between height, weight, and graft diameter. The prediction model with weight, height, and sex also demonstrated a significant regression with F = 20.7, R2 = 0.55, and p < 0.001. The regression equations are summarized in Table III.

Table I: Characteristics of the study participants (N = 50)
Table II: Correlation analysis of the anthropometric measurements (weight, height, BMI, femur length, and thigh circumference) with four-stranded hamstring graft diameter and length
Table III: Regression equations using anthropometric measurements to predict the graft diameter and length

Discussion

Fifty patients (36 males, 14 females, an average age of 32.96 ± 1.46) were included in this cross-sectional study. Weight correlated most significantly with graft diameter, followed by height and BMI. A significantly strong correlation existed between height and graft length, and height was an essential factor in predicting that length. Graft diameter, which strongly correlates with the combination of sex, weight, and height, can be predicted by height, weight, or BMI through subsequent linear regression analysis with significant values.
Earlier research indicated that cruciate ligament ruptures tended to occur in young and active individuals, with a particular vulnerability observed in men [20,21]. Our study aligns with these findings, as we observed a higher incidence of cruciate ligament injuries among men (36 patients) compared to women (14 patients), and their average age was ­notably young. The number of patients in sports or traffic accidents was high as well, and male patients are more susceptible than females to those injuries. It was considered the reality in Vietnam due to the mechanism of injury and weighty traffic issues.
Regarding the anthropometric measurements of patients, recent studies exhibit certain distinctive characteristics. Earlier investigations revealed that their subjects had higher anthropometric measurements than the Vietnamese population [14,22], suggesting potential differences in fitness levels among various populations. This could be seen as the difference in fitness among populations. The mean autograft diameter was comparable to Sakti et al.’s study conducted in a South East Asian population with a 7.36 ± 0.66 mm diameter. However, when comparing our results with other studies conducted in American, Dutch, or Indian populations, they had higher graft diameters, which were more than 8.0 mm [9,18,23]. Additionally, the Vietnamese anthropomorphic characteristics in our study are smaller than those of Caucasian people. Pereira et al. and Goyal et al.’s studies showed that the average anthropometric measurements of Brazilian and Indian people are larger than that of our population [24,25]. That is the reason why it is necessary to have a study researching the correlation between anthropometric data and graft size in a specific population. In addition, the mean graft length overcame the minimum length of the hamstring autograft (8 cm for ACL reconstruction, 9 cm for PCL reconstruction) to decrease complications, as mentioned in previous studies [11,12].
Most published studies reported that height, weight, and BMI were notable predictors of 4-stranded hamstring graft diameter [9,21,23,26]. Among the variables, weight was seen to be the most significant, followed by height and BMI, and relatively consistent with the results of Mardani-Kivi et al.’s study [27], but different from previous studies that reported that height was the most significant [28-30]. Thigh circumference had a weak positive correlation with graft diameter, which was also seen in Gupta et al.’s study (r = 0.325) but in contrast to the result of Treme et al.’s study that to be a significant predictor (r = 0.6) [26,31]. Patient’s height had a strong correlation and weight had a weak correlation with graft length, which was similar to other studies [14,26,30, 31]. These variations of correlations can be explained by the diversity among the population and also depending on the patient’s physical status.
Our study employs sequential simple and multiple linear regression analyses to predict the dimensions of four-stranded hamstring autografts in Vietnamese patients. Significantly, weight and height emerge as primary predictors for graft diameter, with weight carrying more weight, while graft length is primarily influenced by the patient’s height alone. Noteworthy is identifying a correlation between sex and graft diameter, alongside weight and height, a finding consistent with prior studies [16,22].
There should be a discussion of a few study limitations. The prolonged COVID-19 isolation period initially prompted our institution to postpone elective surgeries, resulting in a relatively minor participant pool, potentially limiting statistical power. Variations in measurement methods, mainly when calculating thigh circumference, may result in discrepancies and affect the findings regarding the relationship between graft dimensions. Additionally, our study revealed limited variability in the length and diameter of the graft. This can be attributed to using a standard graft-diameter block with 0.5-mm increments to measure the graft diameter in millimeters and the graft length in centimeters using a ruler on the drill bit. Given the scarcity of arthroscopic tools during the pandemic isolation period, we meticulously adjusted the graft sizes to align with the drill bit. Compared to previous studies [14,22,32], our results were slightly smaller with low variability as our sample consisted of young, healthy Vietnamese patients with comparable body shapes, which likely contributed to the minimal observed variability. Furthermore, our study is limited by the lack of sufficient data relating to body composition, cardiovascular fitness, and functional movement screening, which impacts the correlation between fitness and anthropometric measures. Addressing this limitation will be a focus of our future investigations.
Our findings comprehensively addressed the impact of graft size on postoperative outcomes, shedding light on the ideal dimensions for four-stranded hamstring autografts in the Vietnamese population and informing strategies to avoid graft failure. Further investigation involving follow-up of patients with smaller grafts compared with those with larger grafts may uncover additional insights into these outcomes for future studies.
In cruciate reconstruction, four-stranded hamstring autografts are the most preferred graft option. Some studies reported a significant relationship between graft sizes and patients’ anthropometry. Most of them were from America, Europe, and some Asian countries, and they helped surgeons have better surgical planning. However, to our knowledge, no study was available to help conclude how to predict graft size depending on the Vietnamese population using anthropometric measurements. Therefore, this is the first study to fill the gap.
In the Vietnamese population, weight emerges as the foremost predictor for anticipating the diameter of a four-stranded hamstring autograft, with height and BMI following in significance. Height stands out as the sole substantial indicator for forecasting graft length. Sex, weight, and height exhibit meaningful regression outcomes concerning autograft diameter. These regression analyses serve as valuable tools for orthopedists, aiding in determining optimal graft sizes. Such insights contribute to enhanced planning and play a pivotal role in mitigating the risk of reconstruction failure.

Practical implications

– Preoperative hamstring autograft size prediction is crucial to preparing fixation methods or graft choices.
– Weight mostly correlated with graft diameter.
– Height strongly correlated with graft length.
– Regressions between anthropometric measurements and hamstring autograft size exist for optimal planning and minimizing the risk of reconstruction failure.

Acknowledgments, conflict of interest, and funding

The authors thank Can Tho University of Medicine and Pharmacy and the University Hospital for supporting this study.
The authors state that there are no conflicts of interest to declare. The authors received no financial support for the research, authorship, and publication of this article.

Corresponding author

Nguyen Tu Thai Bao
Department of Orthopedics, Faculty of Medicine,
Can Tho University of Medicine and Pharmacy,
Can Tho, Vietnam – 179, Nguyen Van Cu Street,
An Khanh ward, Ninh Kieu District, Can Tho, Vietnam
Tel: +84-939409701
Email: nttbao@ctump.edu.vn

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