Three-Dimensional Computed Tomography Imaging Evidence of Regeneration of the Semitendinosus Tendon Harvested for Anterior Cruciate Ligament Reconstruction

Muscle Morphology Does Not Solely Determine Knee Flexion Weakness After Anterior Cruciate Ligament Reconstruction with a Semitendinosus Tendon Graft: A Combined Experimental and Computational Modeling Study

The distal semitendinosus tendon is commonly harvested for anterior cruciate ligament reconstruction, inducing substantial morbidity at the knee. The aim of this study was to probe how morphological changes of the semitendinosus muscle after harvest of its distal tendon for anterior cruciate ligament reconstruction affects knee flexion strength and whether the knee flexor synergists can compensate for the knee flexion weakness. Ten participants 8-18 months after anterior cruciate ligament reconstruction with an ipsilateral distal semitendinosus tendon autograft performed isometric knee flexion strength testing (15°, 45°, 60°, and 90°; 0° = knee extension) positioned prone on an isokinetic dynamometer. Morphological parameters extracted from magnetic resonance images were used to inform a musculoskeletal model. Knee flexion moments estimated by the model were then compared with those measured experimentally at each knee angle position. A statistically significant between-leg difference in experimentally-measured maximal isometric strength was found at 60° and 90°, but not 15° or 45°, of knee flexion. The musculoskeletal model matched the between-leg differences observed in experimental knee flexion moments at 15° and 45° but did not well estimate between-leg differences with a more flexed knee, particularly at 90°. Further, the knee flexor synergists could not physiologically compensate for weakness in deep knee flexion. These results suggest additional factors other than knee flexor muscle morphology play a role in knee flexion weakness following anterior cruciate ligament reconstruction with a distal semitendinosus tendon graft and thus more work at neural and microscopic levels is required for informing treatment and rehabilitation in this demographic.

Semitendinosus muscle morphology in relation to surface electrode placement in anterior cruciate ligament reconstructed and contralateral legs

The semitendinosus tendon is commonly harvested as graft tissue for anterior cruciate ligament reconstruction (ACLR). Although the semitendinosus tendon can regenerate following harvesting, ACLR results in substantial reductions in semitendinosus muscle size and length, potentially complicating electrode placement for electromyography. The purpose of this study was to assess whether the most commonly used electrode placement [recommended by the “Surface Electromyography for Non-Invasive Assessment of Muscles” (SENIAM) project] is appropriate for measuring semitendinosus electromyograms after ACLR. In nine participants (unilateral ACLR with a semitendinosus graft), B-mode ultrasonography was used to bilaterally determine (i) the semitendinosus muscle-tendon junction position and the state of tendon regeneration (latter for the ACLR leg only) and (ii) the anatomical cross-sectional area (ACSA) of the semitendinosus muscle at the SENIAM-recommended electrode placement site at rest and during isometric maximal voluntary contraction (MVC) at two knee joint angles. Depending on the contraction state and joint angle, the semitendinosus muscle had retracted past the recommended placement site in 33–78% of ACLR legs, but not in any contralateral legs. The ACSA of semitendinosus was smaller both at rest and MVC in the ACLR compared to contralateral leg. The ACSA for both legs decreased at MVC compared to rest and at deep compared to shallow knee flexion angles, likely due to sliding of the muscle under the skin. These results suggest SENIAM guidelines are likely unsuitable for recording surface electromyograms from the semitendinosus muscle after tendon harvesting for ACLR as the muscle of interest may not be within the electrode detection volume.

Single versus double hamstring tendon graft in anterior cruciate ligament reconstruction in the paediatric patient: a single-blind randomised controlled trial study protocol

INTRODUCTION

There is currently no clear indication in the literature regarding a single or double hamstring tendon (single bundle) autograft for anterior cruciate ligament (ACL) reconstruction in the paediatric patient. The primary aim of this single blind randomised controlled trial is to determine whether a single or double hamstring tendon graft ACLR leads to superior clinical outcomes postsurgery in paediatric patients with ACL injury.

METHODS AND ANALYSIS

Single site, prospective, single blind, randomised controlled trial with two parallel treatment arms. 100 patients aged 10-18 years who present with an isolated ACL tear±meniscal injury, verified on MRI, will be randomly allocated to one of the two surgical groups. The primary outcomes will be side-to-side difference in anterior tibial translation and graft failure incidence 12 months postsurgery. Primary and secondary outcomes will also be assessed at 2-year and 5-year postsurgery.

ETHICS AND DISSEMINATION

Results will be presented in peer-reviewed journals and at international conferences and disseminated to participants and healthcare professionals via newsletters and hospital presentations. This study is approved by the Children's Health Queensland Hospital and Health Service Human Research Ethics committee.

TRIAL REGISTRATION NUMBER

ACTRN12620001170910p; Australian New Zealand Clinical Trials Registry.

Is there significant regeneration of the hamstring tendons after harvest for ACL reconstruction? A systematic review of literature

BACKGROUND

Regeneration potential of Hamstring tendons after harvest assumes significant clinical relevance as its use has become widespread today. Methods which best assess the regeneration, extent and type of regeneration, plus issues related to functional loss are important for the surgeon to know. This review looks at the literature to find answers to the above questions.

PURPOSE

To summarize the evidence in support of hamstring tendon regeneration, and the most appropriate modality for evaluation of regeneration. Additionally, to evaluate the regeneration in terms of complete or partial, extent and its impact on strength deficit and functional outcomes.

METHODS

We did a systematic review of literature through specified search engines and identified 30 of 285 studies to be relevant (19 prospective and 11 retrospective).

RESULTS

Evaluation of above data suggests tissue regeneration at harvest sites does occur (78.9% of semitendinosus and 42.7% of gracilis tendons), but this regeneration is variable. No established definition of regeneration exists; MRI is an adequate tool to identify regeneration, while biopsy is confirmative. USG is a cost-effective screening method and can document distal progress of regenerate. Semitendinosus and gracilis tendons regenerate at different rates and extents, and often fuse together, but there is no evidence to state that one regenerates better than the other. Proximal retraction of the muscle-tendon junction occurs, along with some atrophy, which affects function to a variable extent. Strength deficits may persist, but they may not convert to significant functional deficits.

CONCLUSION

There is variable hamstring regeneration after harvest, with poorly defined definition of "regeneration". Some changes in the muscle itself, abnormal distal insertion and absence of regeneration in some are documented, along with strength deficits. Although overall functional deficits have been reported to be minimal, a definite change in the anatomy of the medial hamstrings is a factor to be kept in consideration. More information is needed about the long-term consequences.

Determinants of regeneration and strength of hamstrings after anterior cruciate ligament reconstruction-fate of hamstring tendon

BACKGROUND AND AIM

Arthroscopic reconstruction of anterior cruciate ligament (ACL) surgical procedure using hamstring autograft is the most common surgery performed in the arena of sports medicine and arthroscopy. Most studies in literature are ambiguous regarding the fate of hamstrings based on function, regenerative potential, and cross-sectional area (CSA). The aim of this research study is analysis of the fate of hamstring tendons (both semitendinosus and gracilis) during the time course for determinants of regeneration and strength.

METHODS

Fifty patients who were operated for unilateral isolated ACL reconstruction from July 2015 to June 2018 were evaluated for the fate of harvested hamstring tendons which included the following: regeneration, cross-sectional area (CSA), strength, and insertion of regenerated hamstrings by isometric torque and isokinetic strength. MRI of knee was performed for both knees concerning the semitendinosus (ST), gracilis (G), Sartorius, biceps femoris, and medial head of gastrocnemius.

RESULTS

Eighty-four percent men and 16% women within a mean patient age of 34 ± 4.12 years were evaluated and all 50 (100%) patients demonstrated hamstring regeneration by the MRI measurements at six months and at one year post-ACL reconstruction. The torque of isometric knee flexion measured in 60° was found to be remarkably lower in the ACL-reconstructed lower extremity compared to that of the contralateral limb (87.13 ± 20.18% of BW), at 90° (49.17 ± 15.09% BW), and at 105° (43.91 ± 13.17% BW), respectively (p < 0.01). However, at 30° flexion and 45° flexion, the difference was insignificant (116.48 ± 21.07% BW for 30° and 100.16 ± 25.12% BW for 45°).

CONCLUSIONS

It was found that the properties of musculotendinous units of ST and G were significantly transformed after their harvesting for ACL reconstruction and these weaknesses contribute to the flexion deficit of knee in the deeper range of flexion in the operated limb. Therefore, approaches facilitating tendon regeneration and preservation must be warranted.

Knee flexion strength deficits correlate with distal extent of tendon regeneration after hamstring harvest. Preliminary data from an Ultrasound based classification

BACKGROUND

As more evidence comes to light that hamstring harvesting may not be as benign a procedure as previously thought, considerable interest is being generated towards corelating the knee flexural strength deficits with the degree of tendon regeneration. The current study aimed to corelate knee flexion strength deficits with ultrasonographically quantified degree of hamstring regeneration after tendon harvest.

STUDY DESIGN

31 patients of ACL reconstruction with hamstring grafts were divided into 2 groups (6 months and 1-year post op) according to time of follow up. Ultrasonography of both the knees to assess Semitendinosus tendon dimensions was done. Regeneration was classified as non-significant, mild (Zone 1, till 4 cm above the lateral joint line), moderate (Zone 2 ,at the level of the lateral joint line) and significant (Zone 3, 1.5 cm below the lateral joint line) as the regenerate happens from proximal to distal. Regenerate dimensions were compared with US measurements from the opposite knee. Bilateral isokinetic strength tests of the knees were done to evaluate flexion strength, and strength deficits were compared with degree of tendon regeneration.

RESULTS

14 (45%) of cases had no regeneration at both time periods. 7 patients (41%) in the 6-month post-op group showed some form of regeneration, and 10 patients (71%) in the 1-year post-op group showed regeneration. 29/31 patients had some flexion strength deficit. Strength deficit correlated with the level and degree of tendon regeneration, with non-significant regeneration cases showing higher strength deficit (mean - 28.51%), and cases with significant regeneration showing least amount of strength deficit (mean - 3.66%).

CONCLUSION

Flexion strength deficits after hamstring harvest are significant and corelate with degree of tendon regeneration, which improves over time. US is adequate to quantify degree of tendon regeneration, which in turn can help prognosticate return of flexion strength.

Tendon regeneration and muscle hypotrophy after isolated Gracilis tendon harvesting - a pilot study

Purpose

The gracilis tendon (GT) is a commonly used autologous graft in Orthopaedic surgery. The majority of information on knee function and outcomes after hamstring harvest is related to both semitendinosus and GT harvest. Little is known regarding isolated harvest of a GT. It was hypothesized that isolated GT harvest would lead to altered gait patterns (e.g. augmented anterior-posterior translation or rotation in the tibiofemoral joint) and consequently a higher prevalence of cartilage lesions and meniscal tears in knees.

Methods

GT harvesting was performed on patients with chronic acromioclavicular joint instability without previous knee injuries or surgeries. MRI of both knees and thighs were performed. Knee MRI were evaluated using the Whole-Organ Magnetic Resonance Imaging Score (WORMS). Inter- and intraobserver reliabilities, cross-sectional areas of different muscles, fatty infiltration of the gracilis muscle (GM) and GT regeneration were evaluated. The contralateral limb served as reference. The observers were blinded towards the identity of the patients and the operatively treated side.

Results

After a mean time of 44 months after surgery testing was performed on 12 patients. No significant side-to-side differences were found using WORMS, although there was a trend towards increased cartilage lesions after GT harvest (median healthy knee 4.8 and GT harvested knee 7.8 p = 0.086). Inter- and intraobserver repeatability was high with 0.899 (95% confidence interval (CI) 0.708–0.960) and 0.988 (95% CI 0.973–0.995), respectively. A significant hypotrophy of the GM with a mean decrease of 25.3%, 18.4% and 16.9% occurred at 25% (p = 0.016), 50% (p = 0.007) and 75% (p = 0.002) of the length of the femur from distal. No compensatory hypertrophy of other thigh muscles or increased fatty infiltration of the GM was found. Tendon regeneration took place in eight out of 12 patients. In case of regeneration, the regenerated tendon inserted in a more proximal place.

Conclusion

Isolated harvest of the GT for shoulder procedures did not affect knee MRI significantly indicating therefore in general suitable graft utilization for surgeries outside of the knee. GT regenerated in most patients with just a more proximal insertion and a hypotrophy of the muscle belly.

Functional Effects of Single Semitendinosus Tendon Harvesting in Anatomic Anterior Cruciate Ligament Reconstruction: Comparison of Single versus Dual Hamstring Harvesting

Background

This study aimed to determine the effects of single semitendinosus tendon (ST) harvesting for anterior cruciate ligament (ACL) reconstruction by comparing outcomes of single ST and semitendinosus-gracilis tendon (ST-G) harvesting.

Methods

ACL reconstruction with ST-G harvesting (D group, n = 60) or single ST harvesting (S group, n = 60) were included according to inclusion criteria. Subjective assessments included subjective International Knee Documentation Committee score, Lysholm score, and Tegner activity scale score. Objective assessments included isokinetic strength and functional tests. These tests were completed at 36 months of follow-up. Magnetic resonance imaging (MRI) and second-look arthroscopy findings were evaluated. In the S group, regeneration properties were assessed by serial ultrasonography (US).

Results

The S group showed significantly less deep flexor strength deficit than the D group (p < 0.001). Deep flexor power deficits showed significant correlation with the shift of musculotendinous junction of the ST. There was significant difference in the cocontraction test between the groups (p = 0.012), and the S group tended to show better results in other functional tests at the last follow-up. There were no significant differences in graft tension and synovial coverage on second-look arthroscopy between the groups. In the S group, the regeneration rates assessed by US at the joint line and distal insertion were 81.7% and 80%, respectively at 6 months of follow-up.

Conclusions

The S group showed significantly less deficit in deep flexor strength and tended to show better clinical results at the last follow-up than the D group. In the S group, more than 80% showed good regeneration at the 6-month follow-up. Hence, single ST harvesting is effective in minimizing flexor weakness and functional deficits and shows great potential for regeneration.

Predictive Factors of Hamstring Tendon Regeneration and Functional Recovery After Harvesting: A Prospective Follow-up Study

BACKGROUND

Semitendinosus and gracilis tendons may regenerate after harvesting for ligament reconstruction procedures. However, predictive factors of tendon regeneration and the extent of functional recovery remain unclear.

PURPOSE

To identify predictive factors for hamstring tendon regeneration and to examine the morbidity of nonregenerated hamstring tendons.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Of the 154 patients who were included in a prospective follow-up study, 79 underwent reconstruction of the anterior cruciate ligament entailing the hamstring tendons and met the following inclusion criteria: (1) anterior cruciate ligament rupture diagnosed by physical examination and magnetic resonance imaging (MRI), (2) MRI within 6 months after trauma, (3) age between 18 and 45 years, and (4) 2-year follow-up MRI data available. Hamstring tendon regeneration was assessed as complete if a tendon-like structure could be visualized at the level of the joint line or more cranially. Patient characteristics-such as age, sex, body mass index, alcohol/nicotine use, activity level (Tegner scores), and functional instability (1-legged hop test)-were evaluated preoperatively and at 2 years to determine predictive factors for tendon regeneration or examine functional recovery of hamstring tendon regeneration.

RESULTS

At 2 years' follow-up, 67.1% of the patients showed regeneration of semitendinosus tendons, 81.0% of gracilis tendons, and 59.5% of both tendons. The likelihood of semitendinosus tendon regeneration significantly decreased with aging (odds ratio [OR], 0.92 change per year of age; 95% CI, 0.84-0.99; P = .03) and smoking (OR, 0.20; 95% CI, 0.05-0.77; P = .02). No predictive factor was found for gracilis tendon regeneration. Regeneration of the semitendinosus and gracilis tendons was negatively related with smoking (OR, 0.22; 95% CI, 0.06-0.79; P = .02). Patients without regeneration showed similar postoperative visual analog scale scores during physical activity, similar Tegner scores, and a significant decrease of the upper leg circumference, as compared with their preoperative results. Regardless of the regeneration status, 1-legged hop test results significantly increased at 2-year follow-up.

CONCLUSION

Hamstring tendon regeneration occurs less frequently in older patients and in smokers. However, absence of regenerated tendons does not seem to cause a loss of function.

The natural history of donor hamstrings unit after anterior cruciate ligament reconstruction: a prospective MRI scan assessment

PURPOSE

The aim of this prospective study was to assess the natural history of the donor hamstrings, compared to the contralateral knee and thigh.

METHODS

In 47 patients who had ACL reconstruction (hamstrings technique), bilateral knees and thighs were investigated using MRI scans, up to 2 years post-operatively.

RESULTS

Tendon regeneration below the knee joint line of the semitendinosus occurred in 30/47 (64 %) patients and of the gracilis tendon in 17/47 (36 %) patients. Insertion of both tendons at the "pes anserinus", with normal anatomic relations, was observed in 5/47 (11 %) patients. Semitendinosus and gracilis donor muscles were found retracted in 41/47 (87 %) patients. In 25/47 (53 %) patients, there was evidence of fatty infiltration of the semitendinosus muscle. All (47/47) (100 %) patients showed semitendinosus muscle atrophy and 41/47 (87 %) patients showed gracilis muscle atrophy, compared to the contralateral limb. High signal intensity on STIR images was observed in the semitendinosus in 22/47 (46 %) patients and in the gracilis muscle in 30/47 (64 %) patients, on MRI examination performed up to 24 months post-operatively.

CONCLUSIONS

The "regenerated" hamstrings tendons most commonly do not regenerate fully anatomically, so they should not be considered as a first choice for re-harvesting in revision ACL reconstruction. The "donor hamstrings muscles" are found to be shorter, contracted, thinner and with a long-term abnormal MRI signal, features which are considered to be related to reduced muscle performance (knee flexion and internal rotation) post-operatively.

LEVEL OF EVIDENCE

II.

Hamstring Strength Asymmetry at 3 Years After Anterior Cruciate Ligament Reconstruction Alters Knee Mechanics During Gait and Jogging

BACKGROUND

Anterior cruciate ligament reconstruction (ACLR) using a hamstring tendon autograft often results in hamstring muscle strength asymmetry. However, the effect of hamstring muscle strength asymmetry on knee mechanics has not been reported.

HYPOTHESIS

Participants with hamstring strength asymmetry would demonstrate altered involved limb knee mechanics during walking and jogging compared with those with more symmetric hamstring strength at least 2 years after ACLR with a hamstring tendon autograft.

STUDY DESIGN

Controlled laboratory study.

METHODS

There were a total of 45 participants at least 2 years after ACLR (22 male, 23 female; mean time after ACLR, 34.6 months). A limb symmetry index (LSI) was calculated for isometric hamstring strength to subdivide the sample into symmetric hamstring (SH) (LSI ≥90%; n = 18) and asymmetric hamstring (AH) (LSI <85%; n = 18) groups. Involved knee kinematic and kinetic data were collected using 3-dimensional motion analysis during gait and jogging. Peak sagittal-, frontal-, and transverse-plane knee angles and sagittal-plane knee moments and knee powers were calculated. Independent-samples t tests and analyses of covariance were used to compare involved knee kinematic and kinetic variables between the groups.

RESULTS

There were no differences in sagittal- and frontal-plane knee angles between the groups ( P > .05 for all). The AH group demonstrated decreased tibial internal rotation during weight acceptance during gait ( P = .01) and increased tibial external rotation during jogging at initial contact ( P = .03) and during weight acceptance ( P = .02) compared with the SH group. In addition, the AH group demonstrated decreased peak negative knee power during midstance ( P = .01) during gait compared with the SH group, after controlling for gait speed, which differed between groups.

CONCLUSION

Participants with hamstring strength asymmetry showed altered involved knee mechanics in the sagittal plane during gait and in the transverse plane during gait and jogging compared with those with more symmetric hamstring strength.

CLINICAL RELEVANCE

Hamstring strength asymmetry is common at 3 years after ACLR with a hamstring tendon autograft and affects involved knee mechanics during gait and jogging. Additional research is warranted to further investigate the longitudinal effect of these alterations on knee function and joint health after ACLR.

Morphologic Characteristics and Strength of the Hamstring Muscles Remain Altered at 2 Years After Use of a Hamstring Tendon Graft in Anterior Cruciate Ligament Reconstruction

BACKGROUND

The hamstring tendon graft used in anterior cruciate ligament (ACL) reconstruction has been shown to lead to changes to the semitendinosus and gracilis musculature.

HYPOTHESIS

We hypothesized that (1) loss of donor muscle size would significantly correlate with knee muscle strength deficits, (2) loss of donor muscle size would be greater for muscles that do not experience tendon regeneration, and (3) morphological adaptations would also be evident in nondonor knee muscles.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Twenty participants (14 men and 6 women, mean age 29 ± 7 years, mean body mass 82 ± 15 kg) who had undergone an ACL reconstruction with a hamstring tendon graft at least 2 years previously underwent bilateral magnetic resonance imaging and subsequent strength testing. Muscle and tendon volumes, peak cross-sectional areas (CSAs), and lengths were determined for 12 muscles and 6 functional muscle groups of the surgical and contralateral limbs. Peak isokinetic concentric strength was measured in knee flexion/extension and internal/external tibial rotation.

RESULTS

Only 35% of the patients showed regeneration of both the semitendinosus and gracilis tendons. The regenerated tendons were longer with larger volume and CSA compared with the contralateral side. Deficits in semitendinosus and gracilis muscle size were greater for muscles in which tendons did not regenerate. In addition, combined hamstring muscles (semitendinosus, semimembranosus, and biceps femoris) and combined medial knee muscles (semitendinosus, semimembranosus, gracilis, vastus medialis, medial gastrocnemius, and sartorius) on the surgical side were reduced in volume by 12% and 10%, respectively. A 7% larger volume was observed in the surgical limb for the biceps femoris muscle and corresponded with a lower internal/external tibial rotation strength ratio. The difference in volume, peak CSA, and length of the semitendinosus and gracilis correlated significantly with the deficit in knee flexion strength, with Pearson correlations of 0.51, 0.57, and 0.61, respectively.

CONCLUSION

The muscle-tendon properties of the semitendinosus and gracilis are substantially altered after harvesting, and these alterations may contribute to knee flexor weakness in the surgical limb. These deficits are more pronounced in knees with tendons that do not regenerate and are only partially offset by compensatory hypertrophy of other hamstring muscles.

Inducement of tissue regeneration of harvested hamstring tendons in a rabbit model

OBJECTIVES

The objective of this study was to determine if the use of fascia lata as a tendon regeneration guide (placed into the tendon canal following harvesting the semitendinosus tendon) would improve the incidence of tissue regeneration and prevent fatty degeneration of the semitendinosus muscle.

MATERIALS AND METHODS

Bilateral semitendinosus tendons were harvested from rabbits using a tendon stripper. On the inducing graft (IG) side, the tendon canal and semitendinosus tibial attachment site were connected by the fascia lata, which was harvested at the same width as the semitendinosus tendon. On the control side, no special procedures were performed. Two groups of six rabbits were killed at post-operative weeks 4 and 8, respectively. In addition, three healthy rabbits were killed to obtain normal tissue. We evaluated the incidence of tendon tissue regeneration, cross-sectional area of the regenerated tendon tissue and proportion of fatty tissue in the semitendinosus muscle.

RESULTS

At post-operative week 8, the distal end of the regenerated tissue reached the vicinity of the tibial insertion on the control side in two of six specimens. On the IG side, the regenerated tissue maintained continuity with the tibial insertion in all specimens. The cross-sectional area of the IG side was significantly greater than that of the control side. The proportion of fatty tissue in the semitendinosus muscle on the IG side was comparable with that of the control side, but was significantly greater than that of the normal muscle.

CONCLUSIONS

Tendon tissue regenerated with the fascia lata graft was thicker than naturally occurring regenerated tissue. However, the proportion of fatty tissue in the semitendinosus muscle was greater than that of normal muscle.Cite this article: K. Tabuchi, T. Soejima, H. Murakami, K. Noguchi, N. Shiba, K. Nagata. Inducement of tissue regeneration of harvested hamstring tendons in a rabbit model. Bone Joint Res 2016;5:247-252. DOI: 10.1302/2046-3758.56.2000585.

Hamstring Tendon Regeneration After Harvesting: A Systematic Review

BACKGROUND

Hamstring tendons are often used as autografts for anterior cruciate ligament (ACL) reconstruction. However, no systematic review has been performed describing consequences such as hamstring tendon regeneration rate and determinants of hamstring tendon regeneration.

PURPOSE

To summarize the current literature regarding hamstring tendon rate regeneration, the time course of regeneration, and determinants of hamstring regeneration.

STUDY DESIGN

Systematic review.

METHODS

A search was performed in the Embase, Medline (OvidSP), Web of Science, Cochrane, PubMed, and Google Scholar databases up to June 2014 to identify relevant articles. A study was eligible if it met the following inclusion criteria: tendons were harvested, regeneration at harvest site was assessed, population size was at least 10 human subjects, full-text article was available, and the study design was either a randomized controlled trial, prospective cohort study, retrospective cohort study, or case control study. A risk of bias assessment of the eligible articles was determined. Data describing hamstring tendon regeneration rates were pooled per time period.

RESULTS

A total of 18 publications met the inclusion criteria. The mean regeneration rate for the semitendinosus and gracilis tendons was, in all cases, 70% or higher. More than 1 year after harvesting, 79% (median [IQR], 80 [75.5-90]) of the semitendinosus tendons and 72% (median [IQR], 80 [61-88.5]) of the gracilis tendons were regenerated. No significant differences in regeneration rate could be found considering patient sex, age, height, weight, or duration of immobilization. Results did not clearly show whether absence of regeneration disadvantages the subsequent hamstring function. Five studies measured the regeneration rate at different moments in time.

CONCLUSION

Hamstring tendons regenerated in the majority of patients after ACL reconstruction. The majority of the hamstring tendon regeneration was found to occur between 1 month and 1 year after harvest. No significant determinants for hamstring tendon regeneration could be identified because of a lack of research. The function and strength of the regenerated hamstring remained unclear.

Hamstring Tendon Regeneration After Harvest for Anterior Cruciate Ligament Reconstruction: A Systematic Review

PURPOSE

To assess whether the portions of the semitendinosus and gracilis tendons harvested for anterior cruciate ligament reconstruction have the potential to regenerate and, if so, to evaluate the histologic properties and actual function of this newly formed tissue.

METHODS

We performed a comprehensive search of CINAHL (Cumulative Index to Nursing and Allied Health Literature), Embase, Medline, the Cochrane Central Registry of Controlled Trials, and SPORTDiscus from inception of the databases to July 2014, using various combinations of keywords. Studies focusing on hamstring tendon and muscle regeneration through imaging and histology, as well as on the related functional outcomes, were selected. We included studies assessing evidence of tissue regeneration with imaging (magnetic resonance imaging, 3-dimensional computed tomography, ultrasonography) or with histologic examination of biopsy samples (or a combination thereof).

RESULTS

Nineteen articles were included in this review, with a total of 400 patients observed. The overall rate of tissue regeneration was 86.0%, with similar values shown in most studies regardless of the methodology of the assessment. Biopsy confirmed that the tissue found at the site in 74% of the cases showed typical histologic features of the tendon. The mean modified Coleman Methodology Score of the studies included was 52.7 points, showing a modest methodologic quality for the studies published to date.

CONCLUSIONS

In over 85% of the cases analyzed, regeneration signs of the harvested tendon were found through different imaging and histologic methodologies. A torque deficit in deep knee flexion is always present postoperatively, but the cause for this is still unclear. There is a need for better-designed trials featuring a higher level of evidence to further investigate this matter, and the effects of postoperative care and the surgical approach used on the regeneration process should be analyzed in the future.

LEVEL OF EVIDENCE

Level IV, systematic review of Level II, III, and IV studies.

Isokinetic dynamometer evaluation of the effects of early thigh diameter difference on thigh muscle strength in patients undergoing anterior cruciate ligament reconstruction with hamstring tendon graft

After anterior cruciate ligament (ACL) reconstruction, which muscle groups are more affected from frequently developing thigh muscle atrophy is a matter of debate. We evaluate the effect of thigh circumference difference between patients' knees who were administered the ACL reconstruction with hamstring tendon autograft and intact knees, on torque between the hamstring and quadriceps muscles. Fifty-five patients at least 6 months follow-up period available were included in our study. Power measurements of quadriceps and hamstring muscle groups in patients' extremities were done by using isokinetic dynamometer. The maximum torque values at 60°/sec, 240°/sec in frequency, positions of flexion and extension were determined. In accordance with our findings it is still possible to encounter the thigh atrophy in average 28 months after ACL reconstruction surgery even under physical rehabilitation programs and appropriate follow-up. It is inevitable for the clinician to consider these changes in diagnosis and rehabilitation stages. It can't be ignored that muscle weakness mechanisms developing in the thigh circumference vary according to the thigh muscle group and knee flexors play an important role in thigh atrophy when determining an appropriate rehabilitation program after reconstruction application.

Partial harvesting technique in anterior cruciate ligament reconstruction with autologous semitendinosus tendon to prevent a postoperative decrease in deep knee flexion torque

BACKGROUND

A significant decrease in deep knee flexion torque has been reported after harvesting the semitendinosus tendon for anterior cruciate ligament (ACL) reconstruction. Thus, we have developed a partial harvesting technique that leaves part of the width of the insertion of semitendinosus tendon by splitting it. Our hypothesis was that the partial harvesting technique would reduce postoperative functional deficits in deep knee flexion by achieving regeneration of harvested tendon without shortening.

METHODS

A total of 36 patients who underwent ACL reconstruction with an autologous semitendinosus tendon by means of either the conventional whole harvesting technique (whole-ST group, n=16) or the partial harvesting technique (partial-ST group, n=20) were included in this study. Clinical outcome, semitendinosus muscle length, and deep knee flexion torque were assessed 2 years after surgery.

RESULTS

No significant group differences were found in terms of range of motion, Lysholm score, or anterior knee laxity. Shortening of the semitendinosus muscle was significantly less in the partial-ST group (mean 8mm) than in the whole-ST group (mean 36 mm; P<0.001). The side-to-side ratio of isometric knee flexion torque in the prone position with 90° of knee flexion was statistically different between the partial-ST (87.0 ± 20.4%) and whole-ST (55.3 ± 13.9%; P<0.001) groups.

CONCLUSIONS

The present partial harvesting technique not only prevented shortening of the semitendinosus muscle, but also reduced the deficit in the maximum knee flexion angle in the standing position and a decrease in the deep knee flexion torque in the prone position with the partial harvesting technique compared to the nonoperated side with good clinical outcomes.

LEVEL OF EVIDENCE

Case-control study, Level III.

Evaluation of hamstring muscle strength and morphology after anterior cruciate ligament reconstruction

This study aimed to clarify the relationship between knee flexor strength and hamstring muscle morphology after anterior cruciate ligament (ACL) reconstruction using the semitendinosus (ST) tendon and to determine the causative factors of decreased knee flexor muscle strength. Fourteen male and ten female patients who resumed sports activities after surgery participated in the experiment. Isometric knee flexion torque was measured at 30°, 45°, 60°, 90°, and 105° of knee flexion. Magnetic resonance imaging (MRI) was used to calculate ST muscle length and hamstring muscle volume, and to confirm the status of ST tendon regeneration. The correlation between the MRI findings and flexor strength was analyzed. Regenerated ST tendon was confirmed in 21 of the 24 patients, but muscle volume (87.6%) and muscle length (74.5%) of the ST in the operated limb were significantly smaller than those in the normal limb. The percentage of the knee flexion torque of the operated limb compared with that of the normal was apparently lower at 105° (69.1%) and 90° (68.6%) than at 60° (84.4%). Tendon regeneration, ST muscle shortening, and ST muscle atrophy correlated with decreased knee flexion torque. These results indicated that preserving the morphology of the ST muscle-tendon complex is important.

Visualization of torn anterior cruciate ligament using 3-dimensional computed tomography

Recently, a remnant-preserving anterior cruciate ligament (ACL) reconstruction technique has been developed. However, the preoperative condition of remnant ACL is occasionally difficult to evaluate by magnetic resonance imaging. The purpose of this study is to evaluate the accuracy of pre-operative visualization of remnant ACL using three-dimensional computed tomography (3D-CT). The remnant ACL in 25 patients was examined by 3DCT before ACL reconstruction surgery. Findings on 3D-CT images and arthroscopy were compared. The 3D-CT images were classified into 4 groups: Group A, remnant fibers attached to the posterior cruciate ligament (PCL); Group B, those located between the PCL and the lateral wall; Group C, those attached to the lateral wall; and Group D, no identifiable remnant fibers on the tibial side. These groups were made up of 4, 3, 9 and 9 patients, respectively. Findings on 3D-CT images were identical to those during arthroscopy in 20 of 25 cases (80%). Remnant ACL can be accurately evaluated using 3D-CT in 80% of cases of torn ACL. This novel method is a useful technique for pre-operative assessment of remnant ACL.

Semitendinosus tendon regeneration after anterior cruciate ligament reconstruction: can we use it twice?

PURPOSE

It has been demonstrated that the semitendinosus tendon can regenerate after being harvested in its whole length and thickness for anterior cruciate ligament (ACL) reconstruction. Ultrasound studies and guided biopsies of the regenerated tendon have shown compatibility and resembling features of the normal tendon. The question is if this neo-tendon is biologically and functionally adequate for re-use?

METHODS

Two randomised groups of 150 volunteers were followed up for two years after harvesting the semitendinosus only (25) or the semitendinosus and gracilis tendons (25) in ACL reconstruction. The patients were followed up with clinical and ultrasound examinations, biopsies and histological tests. Surgical exploration was done in three patients for macroscopic verification. The injected arteries of four lower limbs were dissected and the tendon's arterial supplies were examined.

RESULTS

Seventy-two percent of the cases showed regeneration of the semitendinosus tendons. The neotendons were inserted mostly below the knee joint (83.3%) where they had fused with the gracilis tendon, and above the joint (60%) when the gracilis was harvested as well. The isokinetic strength of the hamstrings and quadriceps was not significantly diminished on the operated side. A macroscopic and histological analysis of the regenerated tendons demonstrates close resemblance to normal anatomy, with focal areas of fibrosis. In one patient the regenerated tendon was used for medial patellofemoral ligament reconstruction.

CONCLUSION

The semitendinosus muscle can recover and the tendon has great potential to regenerate after harvesting for ACL reconstruction. Our data suggest that the regenerated tendons could be used for iterative ligament reconstruction.

Regeneration of hamstring tendons after anterior cruciate ligament reconstruction

PURPOSE

Primary aim of the study was analysis of hamstring tendon regeneration after anterior cruciate ligament reconstruction (ACLR). Secondary aim was analysis of isokinetic muscle strength in relation to hamstring regeneration. The hypothesis was that regeneration of hamstring tendons after ACLR occurs and that regenerated hamstring tendons contribute to isokinetic hamstring strength with regeneration distal to the knee joint line.

METHODS

Twenty-two patients scheduled for ACLR underwent prospective MRI analysis of both legs. MRI parameters were tendon regeneration and morphology, muscle retraction and muscle cross-sectional area. A double-blind, prospective analysis of isokinetic quadriceps and hamstrings strength was performed.

RESULTS

Regeneration of the gracilis tendon after ACLR occurred in all patients. Regeneration of the semitendinosus tendon occurred in 14 patients. At 1 year, the surface area of the semitendinosus and gracilis muscle decreased compared to both preoperatively (P < 0.01) and the contralateral leg (P < 0.01). The cross-sectional area of the semitendinosus muscle decreased in the absence of tendon regeneration (P = 0.05). The cross-sectional area of the gracilis muscle was greater in case of regeneration distal to the joint line (P = 0.01). Muscle retraction of the semitendinosus muscle was increased in case of nonregeneration (P = 0.02). There was no significant relationship between isokinetic flexion strength and tendon regeneration.

CONCLUSION

Hamstring tendons regenerated after harvest of both semitendinosus and gracilis tendons for ACLR. There was no relation between isokinetic flexion strength and tendon regeneration.

Unsuccessful regeneration of the semitendinosus tendon harvested for anterior cruciate ligament reconstruction: report of two cases

Recent magnetic resonance imaging (MRI) and three-dimensional (3D) computed tomography (CT) analyses have demonstrated that semitendinosus tendon can regenerate at a high rate following harvesting the tendon for anterior cruciate ligament (ACL) reconstruction. Although it is known that the regeneration of the semitendinosus tendon does not occur in all the patients, the reason for this unsuccessful regeneration of the tendon in certain patients remains unknown. We recently encountered two cases in which regeneration of the semitendinosus tendon was unsuccessful because of apparent reasons. These patients experienced a sudden sharp pain in the posterior aspect of their thighs when their hamstring muscles were subjected to aggressive load at 3 and 4 weeks after surgery. At the follow-up examination conducted after 12 months, 3D CT imaging revealed unsuccessful regeneration of the semitendinosus tendons in both cases. Severe proximal retraction of the semitendinosus muscle belly was also confirmed.

Inducement of semitendinosus tendon regeneration to the pes anserinus after its harvest for anterior cruciate ligament reconstruction-A new inducer grafting technique

Purpose

To investigate the usefulness of the “inducer grafting” technique for regeneration of the semitendinosus (ST) tendon after its harvest for anterior cruciate ligament (ACL) reconstruction.

Methods

Twenty knees of 20 patients (mean age at the time of surgery, 23.1 years) underwent ACL reconstruction with a double bundle autograft using the ST tendon (7 patients) and the ST + the gracilis (G) tendons (13 patients).

“Inducer grafting” technique

After harvesting the ST tendon, a passing pin with a loop thread is inserted along with the tendon stripper. The passing pin is pulled out from the medial thigh and the loop thread retained. As an inducer graft, the ST tendon branch is used. After the ACL graft has been secured, the inducer graft is sutured to the pes anserinus and the proximal end passed through by pulling the thread out. Then the inducer graft is placed within the tendon canal. The mean follow-up period was 15 months. The presence and morphology of the regenerated ST tendon were examined by MRI. And the isometric hamstring strength was examined at 45°, 90° and 120° of knee flexion.

Results

One month after the operation in all the patients, MRI demonstrated a low-intensity structure at the anatomical location of the ST, at the level of the superior pole of the patella and the joint line, apparently representing the regenerated ST tendon. Four months after the operation, the distal portion of the regenerated ST tendon had reached the pes anserinus in all patients. Twelve months after the operation, the regenerated ST tendon was hypertrophic in 19 of the 20 patients (95%). The isometric knee flexion torque of the ACL-reconstructed limb was significantly lower at 90° and 120° compared with the contralateral limb.

Conclusion

These results suggest that the “inducer grafting” technique is able to improve the regeneration rate of the harvested ST tendon and promote hypertrophy of the regenerated ST tendon, extending all the way to the pes anserinus. However, this technique couldn’t improve the deficits in knee flexion torque after ACL reconstruction.

Effects of knee immobilization on morphological changes in the semitendinosus muscle-tendon complex after hamstring harvesting for anterior cruciate ligament reconstruction: evaluation using three-dimensional computed tomography

BACKGROUND

It is desirable to maintain the morphology of the semitendinosus muscle-tendon complex after tendon harvesting for anterior cruciate ligament (ACL) reconstruction. The purpose of this study was to evaluate the effect of knee immobilization on morphological changes in the semitendinosus muscle-tendon complex.

METHODS

In total, 39 patients who underwent ACL reconstruction with autologous semitendinosus tendons were included in this study. After surgery, the knee was immobilized for 3 days in 1 group of patients (group 1; 24 patients; control group) and for a longer period (10-14 days) in the other group (group 2; 15 patients). Three-dimensional computed tomography (3D CT) examination was performed at 6 and/or 12 months after the surgery for all patients. Morphological changes in the semitendinosus muscle-tendon complex (proximal shift of the semitendinosus muscle-tendon junction, width of the regenerated semitendinosus tendons, re-insertion sites of the regenerated tendons, and rate of semitendinosus tendon regeneration) were evaluated.

RESULTS

Successful regeneration of the semitendinosus tendon was confirmed in all patients in group 2. In group 1, 3D CT showed that regeneration of the semitendinosus tendon was unsuccessful in 1 of the 24 patients. The average length of the proximal shift of the semitendinosus muscle-tendon junction was 7.3 ± 2.5 cm in group 1 and 7.2 ± 1.9 cm in group 2. There were no significant differences between the 2 groups with regard to the morphological changes in the semitendinosus muscle-tendon complex.

CONCLUSIONS

This study showed that the structure of regenerated tendons could be clearly identified in 38 of 39 cases (97.4%) after ACL reconstruction. However, prolonged knee immobilization (10-14 days) could not prevent morphological changes in the semitendinosus muscle-tendon complex.

Relationships among tendon regeneration on MRI, flexor strength, and functional performance after anterior cruciate ligament reconstruction with hamstring autograft

BACKGROUND

There are numerous reports on hamstring tendon regeneration after harvest for anterior cruciate ligament (ACL) reconstruction. However, few studies have evaluated the relationships among the magnetic resonance imaging (MRI) findings of hamstring regeneration, muscle strength, and functional results.

PURPOSE

This study evaluates the correlations among the hamstring regeneration on MRI, flexor strength, and functional performance after hamstring tendon harvesting in ACL reconstruction.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

We enrolled 45 patients who underwent primary ACL reconstruction using hamstring tendon autografts and in whom flexor strength, functional performance, and preoperative and postoperative MRI results were evaluated at least 2 years postoperatively. Isokinetic flexion strength was tested in the standard and prone positions. We evaluated the differences in flexor strength and functional performance according to the number of regenerated tendons. The correlation between the MRI findings (the number of regenerated hamstring tendons and proximal shift of the musculotendinous junction) and the functional performance and flexor strength was analyzed.

RESULTS

The patients were divided into 3 groups according to the regeneration of the hamstring tendons on MRI: both semitendinosus and gracilis tendons regenerated (group SG), only 1 tendon regenerated (group O), and no tendon regenerated (group N). Significant differences were found in the flexor deficit between group N and groups SG and O on the standard and prone position isokinetic tests. There was a significant correlation (ρ = -.472) between the number of regenerated hamstring tendons and the carioca test result. The proximal shift significantly correlated with the flexor deficit in the prone position isokinetic test (semitendinosus, r = .449; gracilis, r = .366).

CONCLUSION

Hamstring tendons regenerated after harvest for ACL reconstruction in a high proportion of the patients. The flexor strength with both the standard and prone position isokinetic tests differed in the 3 groups. The number of regenerated hamstring tendons was significantly correlated with performance on the carioca test. Proximal shifting of the musculotendinous junction was significantly correlated with flexor deficit on the hyperflexion isokinetic test.

Morphology of hamstring torque-time curves following ACL injury and reconstruction: mechanisms and implications

The purposes of this study were (i) to examine the effects of anterior cruciate ligament (ACL) status on hamstring force steadiness, peak hamstring strength, quadriceps (antagonist) activation, and physical performance, and (ii) to evaluate the associations of physical performance with hamstring steadiness and hamstring strength. Thirteen subjects with unilateral deficiency of the ACL (ACLD), 39 matched subjects with unilateral reconstructed ACL (ACLR; n = 25 with bone-patella tendon-bone (ACLR-PT) graft and n = 14 with combined semitendinosus and gracilis tendon (ACLR-STGT) graft) and 33 control subjects participated. Each subject performed maximal-effort isokinetic knee flexion repetitions at 180° s(-1) with electromyography (EMG) electrodes attached to their medial and lateral quadriceps muscles. Physical performance was assessed using the single-limb long hop for distance. Wavelet-derived mean instantaneous frequency (Mif) of flexor torque-time curves was significantly (p < 0.05) higher (i.e., less smooth) in ACLR-STGT subjects compared to the ACLD, ACLR-PT and control subjects. No significant differences existed for peak hamstrings strength (i.e., peak torque produced) or quadriceps antagonist EMG activity. Positive correlations were identified between hamstrings force steadiness and quadriceps antagonist activity for ACLD (r =  0.797), ACLR-PT (r = 0.467), and ACLR-STGT (r = 0.628) subjects. For ACLR-STGT subjects, reduced hamstrings force steadiness associated with poorer long-hop performance (r = -0.695). Reduced steadiness amongst ACLR-STGT subjects may reflect motor output variability of the antagonist (i.e., quadriceps dyskinesia) and/or agonist musculature-a maladaptive feature which potentially contributes to poorer single-limb hop performance. Measures of hamstring force steadiness in combination with traditional measures of peak hamstring strength provide valuable clinical information regarding knee joint function following ACL injury/ACLR.

Relationship between muscle volume and muscle torque of the hamstrings after anterior cruciate ligament reconstruction

The muscle torque per unit volume of the hamstrings on the injured and uninjured sides in patients with ACL reconstruction were compared with participants with no history of knee injury to examine whether a similar mechanism leading to quadriceps weakness exists in the hamstrings of these patients. The study population consisted of 18 and 52 patients at <or=6 and 12 months after ACL reconstruction, respectively, and 35 healthy controls. The hamstring volume was measured on MRI. To identify the muscle torque per unit volume, the peak torque of knee flexion was divided by the hamstring volume. Most muscle torque per unit volume indexes were not significantly different between the patients at <or=6 months (injured side: 0.133+/-0.03 Nm/cm(3), 60 degrees /s; 0.107+/-0.03 Nm/cm(3), 180 degrees /s; uninjured side: 0.139+/-0.02 Nm/cm(3), 60 degrees /s; 0.107+/-0.02 Nm/cm(3), 180 degrees /s) and controls (0.170+/-0.05 Nm/cm(3), 60 degrees /s; 0.121+/-0.05 Nm/cm(3), 180 degrees /s). However, the muscle torque per unit volume of patients at 12 months in both injured (0.118+/-0.03 Nm/cm(3), 60 degrees /s; 0.092+/-0.02 Nm/cm(3), 180 degrees /s) and uninjured sides (0.120+/-0.03 Nm/cm(3) at 60 degrees /s; 0.094+/-0.02 Nm/cm(3), 180 degrees /s) were significantly lower than those of controls (P<0.01). We found no evidence of recruitment disorder in the hamstrings of the patients. The results of this study indicated that the mechanism of muscle weakness of the hamstrings after reconstruction was different from that of the quadriceps, although the precise mechanism remains to be determined.

Isokinetic Dynamometry in Anterior Cruciate Ligament Injury and Reconstruction

The use of isokinetic dynamometry has often been criticised based on the face-validity argument that isokinetic movements poorly resemble the everyday multi-segmented, dynamic activities of human movements. In the anterior cruciate ligament (ACL) reconstruction or deficiency population where muscle deficits are ubiquitous, this review paper has made a case for using isokinetic dynamometry to isolate and quantify these deficits in a safe and controlled manner. More importantly, the usefulness of isokinetic dynamometry, as applied in individuals with ACL reconstruction or deficiency, is attested by its established known-group and convergent validity. Known-group validity is demonstrated by the extent to which a given isokinetic measure is able to identify individuals who could and could not resume pre-morbid athletic or strenuous activities with minimal functional limitations following an ACL injury. Convergent validity is demonstrated by the extent to which a given isokinetic measure closely associates with self-report measures of knee function in individuals with ACL reconstruction. A basic understanding of the measurement properties of isokinetic dynamometry will guide the clinicians in providing reasoned interventions and advancing the clinical care of their clients. Key words: Biomechanics, Knee, Validity

Hamstring tendons regeneration after ACL reconstruction: an overview

Despite the long lasting research the ideal method of reconstructing the ACL has not been found so far. The last year's attention has shifted to the use of the multistrand hamstring tendon grafts. High ultimate tensile load, multiple-bundle replacement that better approximates the anatomy of the normal ACL and low donor site morbidity are the main advantages of this ACL replacement graft. These theoretical advantages have been multiplied when surprisingly studies have shown that semitendinosus and gracilis tendons actually regenerate after harvesting for use as ACL autografts. In this review article we summarize the current knowledge concerning the hamstring regeneration and we focus on issues that have clinical relevance or issues that have not been answered so far.

Knee-Flexion Torque and Morphology of the Semitendinosus after ACL Reconstruction

PURPOSE

The present study aimed to clarify the relationship between deficits in knee-flexion torque and morphological changes in the semitendinosus muscle-tendon complex after harvesting the semitendinosus tendon for anterior cruciate ligament (ACL) reconstruction.

METHODS

Isometric knee-flexion torque at 45 and 90 degrees of knee flexion was measured in limbs of 23 patients (22 +/- 4 yr) who underwent unilateral ACL reconstruction (12-43 months postoperation) using ipsilateral semitendinosus tendon. Magnetic resonance imaging scans were used to calculate the muscle volume and the muscle length of the semitendinosus and to confirm the presence of the regenerated semitendinosus tendon.

RESULTS

The percentage of the knee-flexion torque of the ACL-reconstructed limb compared with that of the contralateral limb was lower at 90 degrees than at 45 degrees . The regeneration of the semitendinosus tendon-like structure was confirmed in 21 of the 23 patients. However, muscle volume and muscle length of the semitendinosus in the ACL-reconstructed limb were significantly smaller compared with in the contralateral limb.

CONCLUSION

Deficits in knee-flexion torque at deep knee flexion were associated with the atrophy and shortening of the semitendinosus after harvesting the semitendinosus tendon for ACL reconstruction.

Predictive value of preoperative 3-dimensional computer tomography measurement of semitendinosus tendon harvested for anterior cruciate ligament reconstruction

PURPOSE

The aim of this study was to evaluate preoperative measurement of the semitendinosus tendon (ST) by 3-dimensional computed tomography (3-D CT), before using ST as the substitute in the anterior cruciate ligament (ACL) reconstruction.

TYPE OF STUDY

Cross-sectional study to compare anatomic findings with clinical findings.

METHODS

The study involved 28 patients who underwent ACL reconstruction using autogenous ST graft. Preoperative 3-D CT images of ST were obtained with a multidetector-row CT scanner, and rendered qualitatively by the volume-rendering technique. The length and cross-sectional area of ST measured with 3-D CT were compared with the length of the harvested ST and the cross-sectional area of the grafted quadrupled tendon.

RESULTS

The total length of ST measured with 3-D CT ranged from 220.3 to 285.4 mm, with a mean (+/- SD) of 248.0 +/- 17.1 mm, and that measured at surgery ranged from 230.0 to 290.0 mm, with a mean of 257.1 +/- 16.5 mm. These 2 values showed a close positive correlation (gamma = 0.634, P = .002). The cross-sectional area of ST measured with 3-D CT ranged from 4.29 to 18.5 mm2 with a mean of 11.9 +/- 4.6 mm2, and that of the substitute measured at surgery ranged from 28.3 to 56.7 mm2 with a mean of 45.5 +/- 6.9 mm2). There was no significant correlation between the areas of ST measured by CT and the areas of ST measured during surgery.

CONCLUSIONS

Preoperative 3-D CT imaging predicts the length of ST. These findings support the measurement of ST length by 3-D CT as a useful tool for planning ACL reconstructive surgery and for providing important preoperative information to patients.

LEVEL OF EVIDENCE

Level III, diagnostic study.