Three-dimensional computed tomography evaluation of semitendinosus harvest after anterior cruciate ligament reconstruction

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.

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.

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.

Morphologic evaluation of remnant anterior cruciate ligament bundles after injury with three-dimensional computed tomography

PURPOSE

This study aimed to investigate the morphological patterns of remnant anterior cruciate ligament bundles after injury (ACL remnant) on three-dimensional computed tomography (3DCT) and compare them with those on arthroscopy.

METHODS

Sixty-three patients (33 males and 30 females; mean age 25.2 ± 10.1 years) who had undergone primary ACL reconstruction between March 2011 and December 2012 were included in this study. The average durations between traumas and 3DCT and between 3DCT and surgery were 101.7 ± 87.2 and 38.2 ± 38.7 days, respectively. ACL remnants were classified into four morphological patterns on 3DCT. 3DCT findings were compared with arthroscopic findings with and without probing.

RESULTS

The morphological patterns of the ACL remnants on 3DCT were well matched with those on arthroscopy without probing (the concordance rate was 77.8%). However, the concordance rate was reduced to 49.2% when arthroscopic probing was used to confirm the femoral attachment of ACL remnants (p ≤ 0.05).

CONCLUSIONS

This study demonstrates that the morphological patterns of ACL remnants on 3DCT were well matched with those on arthroscopy without probing. Therefore, the technique can be useful for preoperative planning of the ACL reconstruction or informed consent to the patients. However, for definitive diagnosis, arthroscopic probing is required.

LEVEL OF EVIDENCE

IV.

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.

Histological Evaluation of Regenerated Semitendinosus Tendon a Minimum of 6 Years After Harvest for Anterior Cruciate Ligament Reconstruction

Background:

Semitendinosus (ST) and/or gracilis (G) autografts are the most used grafts for anterior cruciate ligament (ACL) surgery. The tendons have been shown to be able to regenerate but with focal areas of scar tissue in the short term. There are no long-term histological studies of the regenerated tendons.

Hypothesis:

In the long term, the regenerated ST tendon normalizes and has a similar histology as the contralateral nonharvested tendon.

Study Design:

Case-control study; Level of evidence, 3.

Methods:

Eighteen patients (8 female, 10 male) who underwent ACL surgery using ipsilateral ST/G tendon autografts were included in this study. Percutaneous specimens were obtained from the regenerated ST tendon and the contralateral nonharvested ST tendon under ultrasonographic guidance at a median of 8.4 years (100.5 months; range, 77-129 months) after the harvest procedure. Specimens from the nonoperated side served as controls. The histology and presence of glycosaminoglycans (GAGs) were assessed using a light microscope and a semiquantitative grading system.

Results:

Thirty-six biopsies were obtained (2 biopsies from each patient). In 5 biopsies, the amount of tissue was too small to analyze in the light microscope, and 1 patient had been operated on bilaterally and was therefore excluded. In total, 24 biopsies were included in the histological analysis. In overall terms, there were no significant differences between the regenerated and nonharvested ST tendon in terms of fiber structure, cellularity, vascularity, and level of GAGs a minimum 6 years after harvest of the ST tendon. However, 3 of the regenerated tendons displayed a loss of fiber structure.

Conclusion:

The ST tendon regenerates and may regain a histological appearance similar to that of the nonharvested contralateral tendon, as seen in this study a median of 8.4 years after harvesting. However, in some tendons, loss of fiber structure was found.

Arthroscopically assisted combined anterior and posterior cruciate ligament reconstruction with autologous hamstring grafts-isokinetic assessment with control group

Objective

The aim of the study was to: 1) evaluate the differences in pre-post operative knee functioning, mechanical stability, isokinetic knee muscle strength in simultaneous arthroscopic patients after having undergone an anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL) with hamstring tendons reconstruction, 2) compare the results of ACL/PCL patients with the control group.

Design

Controlled Laboratory Study.

Materials and Methods

Results of 11 ACL/PCL patients had been matched with 22 uninjured control participants (CP). Prior to surgery, and minimum 2 years after it, functional assessment (Lysholm and IKDC 2000), mechanical knee joint stability evaluation (Lachman and “drawer” test) and isokinetic tests (bilateral knee muscle examination) had been performed. Different rehabilitation exercises had been used: isometric, passive exercises, exercises increasing the range of motion and proprioception, strength exercises and specific functional exercises.

Results

After arthroscopy no significant differences had been found between the injured and uninjured leg in all isokinetic parameters in ACL/PCL patients. However, ACL/PCL patients had still shown significantly lower values of strength in relative isokinetic knee flexors (p = 0.0065) and extensors (p = 0.0171) compared to the CP. There were no differences between groups regarding absolute isokinetic strength and flexors/extensors ratio. There was statistically significant progress in IKDC 2000 (p = 0.0044) and Lysholm (p = 0.0044) scales prior to (44 and 60 points respectively) and after the reconstruction (61 for IKDC 2000 and 94 points for Lysholm).

Conclusions

Although harvesting tendons of semitendinosus and/or gracilis from the healthy extremity diminishes muscle strength of knee flexors in comparison to the CP, flexor strength had improved. Statistically significant improvement of the knee extensor function may indicate that the recreation of joint mechanical stability is required for restoring normal muscle strength. Without restoring normal muscle function and strength, surgical intervention alone may not be sufficient enough to ensure expected improvement of the articular function.

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.

Bilateral magnetic resonance imaging and functional assessment of the semitendinosus and gracilis tendons a minimum of 6 years after ipsilateral harvest for anterior cruciate ligament reconstruction

BACKGROUND

Previous studies are contradictory in terms of the function, regeneration potential, insertion point, and cross-sectional area of the semitendinosus and gracilis tendons after harvest for anterior cruciate ligament (ACL) reconstruction.

HYPOTHESES

In the long term, the tendons will regenerate in most patients with a more proximal point of insertion, the cross-sectional area of the tendons will be smaller compared with the nonoperated contralateral side, and the patients will be weaker in terms of the internal rotation and deep flexion of the knee.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Nineteen patients (9 women and 10 men) who had undergone ACL reconstruction a minimum of 6 years earlier, median 8.5 years (range, 6-11 years), with ipsilateral semitendinosus and gracilis autografts, underwent bilateral magnetic resonance imaging (MRI) of their knees. An experienced, independent musculoskeletal radiologist evaluated all MRI examinations. To evaluate the function, strength measurements in deep knee flexion and internal rotation were performed using an isokinetic strength-testing machine.

RESULTS

The semitendinosus tendon had regenerated in 17 of 19 (89%) patients and the gracilis tendon in 18 of 19 (95%) patients, as seen on MRI. There were no significant differences between the point of insertion for the tendons on the operated and nonoperated sides. The cross-sectional areas of the regenerated tendons revealed no significant differences compared with the normal tendons on the contralateral side, as measured 4 cm above the joint line. The patients were significantly weaker in terms of deep knee flexion at 60 and 180 deg/sec, but they were stronger in terms of internal rotation of the tibia at 60 deg/sec in the operated leg compared with the nonoperated leg.

CONCLUSION

The semitendinosus and gracilis tendons regenerated in the majority of patients and regained an almost normal point of insertion on the pes anserinus a minimum of 6 years after harvest. The regenerated tendons had a cross-sectional area similar to that on the nonoperated contralateral side. The patients revealed a strength deficit in deep knee flexion but not in internal rotation.

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.

The effects of hamstring harvesting on outcomes in anterior cruciate ligament-reconstructed patients: a comparative study between hamstring-harvested and -unharvested patients

PURPOSE

The purpose of this study was to evaluate the effects of hamstring harvesting in patients after anterior cruciate ligament (ACL) reconstruction by comparing groups with and without hamstring harvesting.

METHODS

We evaluated the effect of hamstring harvesting in 73 consecutive patients who underwent ACL reconstruction: 39 patients whose hamstrings were harvested for autografts (group H) were compared with 34 patients who received allografts during the same time period (group C [control]). The cases and controls were compared by analyzing the following variables: age, height, weight, mean follow-up period, type of tissue used, and meniscal surgery. Outcomes were assessed by the Lysholm knee score, Tegner activity score, and KT-2000 side-to-side difference (MEDmetric, San Diego, CA), as well as functional performance tests. The flexor deficit and isokinetic peak torque for knee flexion were measured in the sitting position (0° to 90°), and the flexion torque at 90° was measured in the prone position (60° to 120°).

RESULTS

Although significant knee flexion weakness after ACL reconstruction was observed, a significantly greater knee flexor deficit was found in autograft patients than in allograft patients (P < .001). No differences were found between groups in terms of clinical and functional results regardless of hamstring harvesting. The performance of both study groups in all 4 functional tests were significantly correlated with flexor deficit in the sitting position (P < .05) but not in hyperflexion. Significant flexor deficits in both normal and hyperflexed positions were noted in both groups when compared with the unaffected knee (group H, P < .001; group C, P = .002).

CONCLUSIONS

These results indicate significant knee flexion weakness compared with the unaffected knee after ACL reconstruction regardless of hamstring harvesting. Moreover, the greater increase in knee flexor deficit in the hamstring-harvested group compared with the allograft group was statistically significant. However, clinical and functional outcomes were similar between the groups.

LEVEL OF EVIDENCE

Level III, case-control study.

The process of tendon regeneration in an achilles tendon resection rat model as a model for hamstring regeneration after harvesting for anterior cruciate ligament reconstruction

PURPOSE

The purpose of this study was to clarify the mechanism of tendon regeneration by investigating macroscopically, histologically, and biomechanically.

METHODS

Fifty, adult, female Sprague-Dawley rats were used. The Achilles tendon in the left hind limb was removed totally by use of the tendon-stripping device. Rats were killed at 2, 7, 30, 90, and 180 days after surgery, and the regenerate tendons were dissected. Contralateral Achilles tendons were used as normal controls. Gross anatomic changes, microscopic remodeling, and recovery of biomechanical properties of regenerate tendons were investigated. The expressions of type I collagen, type III collagen, and transforming growth factor β1 were also investigated by immunohistochemistry.

RESULTS

The regenerate tendons formed in all specimens. In the early phase, hematoma and soft granulation tissue were observed at the harvest defect. These gradually matured with time, and the microscopic structure became quite similar to normal at 180 days after surgery. These findings occurred uniformly along the entire length of the regenerate tendon. However, the biomechanical properties were significantly inferior to the normal tendons (P < .05). Transforming growth factor β1 was well co-localized with inflammatory cells and fibroblasts in the regenerate tendons. The type I-type III collagen ratio in the regenerate tendon was significantly decreased in the early phase (P < .05) but gradually increased with time.

CONCLUSIONS

Tendon regeneration and maturation occurred uniformly along the length of regenerate tendons. The hematoma that initially occupies the harvest defect acted as a scaffold for fibroblast precursor cells from the surrounding peritendinous tissue and tendon sheath. The mechanical properties of regenerate tendon were significantly inferior to contralateral control even at 180 days after surgery, and the alteration of the collagen composition would have an influence on mechanical properties of regenerate tendon.

CLINICAL RELEVANCE

Clinicians should be cautious about using reharvested hamstring tendons for ligament reconstruction surgery.

Controversies in soft-tissue anterior cruciate ligament reconstruction: grafts, bundles, tunnels, fixation, and harvest

Increased stability has been reported with both autografts and allografts for anterior cruciate ligament (ACL) reconstruction. However, meta-analysis has shown significantly lower overall knee stability rates and more than double the abnormal stability rate with allografts. Some issues surrounding allograft sterilization (ie, risk of disease transmission) are unresolved, and cost is also a concern. Single-bundle ACL reconstruction can produce high stability rates when tunnels are properly placed, but there is evidence that double-bundle repair may offer greater rotatory stability. Cortical fixation has been associated with increased stability owing to the high stiffness of cortical bone. Anterior and posterior approaches are both recommended. The controversy related to single-bundle versus double-bundle ACL reconstruction remains unresolved.

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.

Evaluation of anterior talofibular ligament lesion using 3-dimensional computed tomography

OBJECTIVE

The aim of this study was to evaluate the applicability of 3-dimensional computed tomography (3D CT) imaging for the diagnosis of anterior talofibular ligament (ATFL) injury.

METHODS

Six patients with lateral instability of ankle joint were examined with 3D CT preoperatively. Three patients had chronic ATFL tear, and the others had os subfibulare. 3D CT images were compared with magnetic resonance imaging and the operative findings.

RESULTS

The ATFL in the uninvolved side could be depicted clearly by 3D CT in all patients. In patients with chronic ATFL tear, 3D CT could evaluate the condition of ATFL remnant much better than MRI. In patients with os subfibulare, the relationship between bone fragment and ATFL was clearly imaged in 3D CT. Surgical findings in all patients were correlated well with 3D CT.

CONCLUSIONS

This study showed that 3D CT has the possibility of being a useful diagnostic tool for evaluation of ATFL lesion.

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.

Hamstring muscle function after tendon harvest for anterior cruciate ligament reconstruction: evaluation with T2 relaxation time of magnetic resonance imaging

BACKGROUND

Regeneration of the semitendinosus and gracilis tendons after harvesting for anterior cruciate ligament reconstruction has been reported; however, muscle belly function after tendon regeneration has not been well documented.

HYPOTHESIS

The semitendinosus and gracilis muscles are highly activated during knee flexion if their tendons are well regenerated after anterior cruciate ligament reconstruction.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Hamstring muscle activation in 11 patients who had undergone anterior cruciate ligament reconstruction with semitendinosus and gracilis tendons was evaluated by measuring the increase of T2 relaxation time measured via magnetic resonance imaging after knee flexion exercise. Tendon regeneration was evaluated via magnetic resonance imaging.

RESULTS

Both muscles increased T2 relaxation time after knee flexion exercise in the operated legs, and there was no significant difference in those values between the operated and nonoperated legs. All the semitendinosus tendons were regenerated at or below the joint line, but no gracilis tendons were observed beyond the joint line. The results indicated that both muscles were highly recruited during knee flexion, regardless of the degree of their tendon regeneration.

CONCLUSION

The semitendinosus and gracilis muscles are able to restore or maintain their contractile capability after harvest of their tendons for anterior cruciate ligament reconstruction, regardless of the degree of regeneration.

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

OBJECTIVE

The purpose of this study was to evaluate the regeneration of semitendinosus tendons harvested for anterior cruciate ligament (ACL) reconstruction using 3-dimensional (3D) computed tomography (CT) imaging and to compare the degree of regeneration with hamstring strength.

METHODS

Twenty-nine patients who underwent ACL reconstruction using ipsilateral autogenous semitendinosus tendons were examined before surgery and 6 and 12 months after surgery by 3D CT imaging. The types of regenerated tendons and the proximal shift of the muscle-tendon junction were evaluated.

RESULTS

The types of regenerated semitendinosus tendons varied from case to case. There was a positive correlation between the peak torque ratio of the hamstring muscle strength and the proximal shift of the muscle-tendon junction 6 months after surgery. The proximal shift did not affect the peak torque ratio 12 months after surgery, however.

CONCLUSIONS

A proximal shift of the muscle-tendon junction may help to explain the individual differences in early postoperative hamstring muscle strength recovery.