Comparative Analysis of the Morphologic Structure of Quadriceps and Patellar Tendon: A Descriptive Laboratory Study

doi:10.1016/j.arthro.2007.01.032

Arthroscopy: The Journal of Arthroscopic & Related Surgery

Volume 23, Issue 7, July 2007, Pages 744-750

https://doi.org/10.1016/j.arthro.2007.01.032 Get rights and content

Purpose: The difference in ultimate strength between the quadriceps and patellar tendon could be reflected by different morphologic features. Methods: Standardized samples of quadriceps and patellar tendons were harvested from 20 cadavers and were investigated via light and electron microscopy, immunohistochemistry, and morphometry. The thickness of collagen fibrils, fibril-interstitium ratio, density of blood vessels, density of fibroblasts, and distribution of collagen fibrils were analyzed. Results: In comparison with the patellar tendon, the quadriceps tendon showed a significantly higher fibril-interstitium ratio (P = .0004) and a higher fibroblast density (P = .0011). No differences regarding the thickness of collagen fibrils, density of blood vessels, and distribution of fibrils were found. Conclusions: The quadriceps tendon graft can provide approximately 20% more collagen than the patellar tendon graft with the same thickness. This fact can play an important role in the better ultimate strength of the quadriceps tendon. Clinical Relevance: The detailed anatomic description of the quadriceps tendon and patellar tendon explains the difference in their ultimate strength.

Section snippets

Tissues

The distal quadriceps together with the patella and patellar tendon were removed from 1 knee in 20 cadavers (14 male and 6 female cadavers). The mean patient age was 56.6 years (range, 43 to 78 years).

Both quadriceps and patellar tendon samples were then taken from the removed tissue. The samples were investigated by light and electron microscopy and immunohistochemistry and were also analyzed by morphometry.

For the light microscopy examination of the central third of the quadriceps and

Results

Microscopically, both quadriceps and patellar tendons are composed of closely packed collagen bundles in an intracellular matrix of proteoglycan. Fibroblasts were the predominant cell type and are arranged in parallel rows between bundles of collagen fibrils arranged in a parallel manner. The density of fibroblasts in the patellar tendon was 10.65 ± 2.48 cells per 1 mm² of collagen fibrils (range, 8.9 to 14.1 fibroblasts per 1 mm² of collagen fibrils). The density of these cells in quadriceps

Discussion

The quadriceps tendon is the main extensor of the knee. It is composed of 3 layers. The most superficial fibers of the rectus femoris run over the patella and join the patellar tendon, whereas its deeper fibers insert into the base of the patella. The vastus medialis and vastus lateralis unite to form the middle layer of the quadriceps tendon, which inserts into the base of the patella. These muscles also send fibers that blend with the corresponding patellar retinacula. The vastus intermedius

Conclusions

The results of our study showed some differences in the microarchitecture of the quadriceps tendon versus the patellar tendon. The most striking findings were a higher density of collagen fibrils and an increased number of fibroblasts in quadriceps tendon in comparison with patellar tendon. These results correlate with findings of other studies regarding the increased ultimate strength of quadriceps tendon in comparison with the same size of patellar tendon. This may indicate that the

Acknowledgment

The authors thank Peter Rieger for his excellent cooperation concerning electron microscopy, Ursula Sturm for assistance with immunohistochemical staining, and John Moyers and Uli Burkhard for help in the reproduction of microphotographs.

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Cited by (32)

Tape-Reinforced Graft Suturing and Retensioning of Adjustable-Loop Cortical Buttons Improve Quadriceps Tendon Autograft Biomechanics in Anterior Cruciate Ligament Reconstruction: A Cadaveric Study
2024, Arthroscopy - Journal of Arthroscopic and Related Surgery
To investigate the biomechanical effects of tape-reinforced graft suturing and graft retensioning for all–soft tissue quadriceps tendon (ASTQT) anterior cruciate ligament reconstruction (ACLR) in a full-construct human cadaveric model.
Harvested cadaveric ASTQT grafts were assigned to either (1) double-suspensory adjustable-loop cortical button device (ALD) fixation in which both graft ends were fixed with a suspensory fixation device with (n = 5) or without (n = 5) tape-reinforced suturing or (2) single-suspensory distal tendon fixation in which only the patellar end was fixed with an ALD (n = 5) or fixed-loop cortical button device (FLD) (n = 5). All specimens were prepared using a No. 2 whipstitch technique, and tape-reinforced specimens had an integrated braided tape implant. Graft preparation time was recorded for double-suspensory constructs. Samples were tested on an electromechanical testing machine using a previously published protocol simulating rehabilitative kinematics and loading.
Tape-reinforced graft suturing resulted in greater graft load retention after cycling (11.9% difference, P = .021), less total elongation (mean [95% confidence interval (CI)], 5.57 mm [3.50-7.65 mm] vs 32.14 mm [25.38-38.90 mm]; P < .001), greater ultimate failure stiffness (mean [95% CI], 171.9 N/mm [158.8-185.0 N/mm] vs 119.4 N/mm [108.7-130.0 N/mm]; P < .001), and less graft preparation time (36.4% difference, P < .001) when compared with unreinforced specimens. Retensioned ALD constructs had less cyclic elongation compared with FLD constructs (mean total elongation [95% CI], 7.04 mm [5.47-8.61 mm] vs 12.96 mm [8.67-17.26 mm]; P = .004).
Tape-reinforced graft suturing improves time-zero ASTQT ACLR construct biomechanics in a cadaveric model with 83% less total elongation, 44% greater stiffness, and reduced preparation time compared with a whipstitched graft without tape reinforcement. ALD fixation improves construct mechanics when compared with FLD fixation as evidenced by 46% less total elongation.
Tape-reinforced implants and graft retensioning using ALDs improve time-zero ACLR graft construct biomechanics in a time-zero biomechanical model. Clinical studies will be necessary to determine whether these implants improve clinical outcomes including knee laxity and the incidence of graft rupture.
Quadriceps tendon autograft for anterior cruciate ligament reconstruction: state of the art
2022, Journal of ISAKOS
Citation Excerpt :
The ultrastructure of the QT has been more thoroughly defined. Hadjicostas evaluate the histology of the QT and found 20% more collagen and 30% more fibroblasts per mm2 than with the matched patella tendon [28]. These are factors that may account for the superior structural properties of the QT versus the PT graft.
The ideal graft for anterior cruciate ligament reconstruction (ACLR) continues to be debated. Although first described in 1984, use of the quadriceps tendon (QT) autograft has only recently gained popularity. The biomechanical properties of the QT autograft are favourable compared to bone-patellar tendon-bone (BPTB) and doubled hamstring (HS) grafts with a higher load to failure and a modulus of elasticity that more closely approximates the native anterior cruciate ligament (ACL). The QT graft can be harvested with or without a bone plug, as either a full thickness or a partial thickness graft, and even through minimally invasive techniques. The surgeon must be aware of potential harvest risks including patellar fracture or a graft that is of insufficient length. Numerous short-term studies have shown comparable results when compared to BPTB or hamstring HS autografts with similar graft failure rates, patient-reported outcomes. A major advantage of QT ACLR is reduced donor site morbidity compared to BPTB. However, some persistent quadriceps weakness after QT ACLR has also been reported. The current literature shows that use of the QT autograft for ACLR provides equivalent clinical results compared to other autografts with less donor site morbidity. However, future studies with longer follow-up and higher level of evidence are needed to identify specific populations where the QT may have additional advantage.
How preconditioning and pretensioning of grafts used in ACLigaments surgical reconstruction are influenced by their mechanical time-dependent characteristics: Can we optimize their initial loading state?
2021, Clinical Biomechanics
Citation Excerpt :
Despite this study did not find different macroscopic behaviours related to the several grafts tested, their specificity should not be ignored. Micro-structural differences were in fact reported between hamstring and patellar tendons (Guillard et al., 2012; Hadjicostas et al., 2007). Although these grafts are of the same typology of tissue, they were harvested from different knee anatomical locations, definitely with a specific different function.
Consensus about a pre-implant preparation protocol adaptable to any graft used in Anterior Cruciate Ligament reconstruction is still lacking. In fact, there is not agreement on reliable metrics that consider both specific graft dimensional characteristics, such as its diameter, and the inherent properties of its constitutive material, i.e. ligaments or tendons. Aim of the present study was to investigate and propose the applied engineering stress as a possible metrics.
Preconditioning and pretensioning protocol involved groups of grafts with different section (10 or 32 mm²) and materials (i.e. human patellar and hamstring tendons, and synthetic grafts). A 140 N load was applied to the grafts and maintained for 100 s. Initial stress and following stress-relaxation (a mechanical characteristic that can be related to knee laxity) were specifically analysed.
Initial stress, ranging between 4 and 12 MPa, was affected primarily by the graft cross-section area and secondarily by the choice of the graft material. In terms of loss of the initial stress, stress-relaxation behaviour varied instead on a narrower range, namely 13–17%.
Engineering stress can be identified as the correct metrics to optimize the initial state of each graft to avoid excessive stiffness, laxity or fatigue rupture phenomena.
Comparative and Morphological Analysis of Commonly Used Autografts for Anterior Cruciate Ligament Reconstruction with the Native Anterior Cruciate Ligament: An Electron Microscopic and Morphologic Study
2018, The Anterior Cruciate Ligament: Reconstruction and Basic Science: Second Edition
Ligaments and tendons are similar in composition but differ in proportion and arrangement. Tendons are being used as grafts for the ACL reconstruction. Their microscopic structure has not been sufficiently studied and compared to the native ACL. A null hypothesis was declared stating that the anterior cruciate ligament should be histological, morphologically and functionally different from the tendon grafts used for ACL reconstruction. We investigated similarities and differences of the structure of ACL and tendons used as a graft tissue for ACL recon- struction. In this study, standardized samples of quadriceps, hamstrings (semitendinosus and gracilis) and patellar tendons, and the ACL were harvested from 26 autopsies (average age 36.4) and were investigated using light and electron microscopy, immunohistochemistry and mor- phometry. The thickness of the collagen fibrils, collagen organization and diameter, the fibril/interstitium ratio, density of fibroblasts and blood vessels, and distribution of the collagen type I, III and V fibrils were analyzed. The semitendinosus showed the highest density of fibroblasts and blood vessels, while the gracilis the highest fibril/ interstitium ratio. No differences regarding the thickness of collagen fibrils and distribution of fibrils were found. The ACL had the highest concentration of type III and V collagen fibrils as well as elastic fibers. The histological and ultrastructural appearance of the ACL differs from those of the tendons used as graft, for ACL reconstruction. Its ultrastructure is varied and complex, with its collagen fibers bundles lying in many directions.
Quadriceps tendon autograft for anterior cruciate ligament reconstruction: A comprehensive review of current literature and systematic review of clinical results
2015, Arthroscopy - Journal of Arthroscopic and Related Surgery
Citation Excerpt :
The tendon has been shown to be relatively hypovascular in a region approximately 1 to 2 cm proximal to the superior pole of the patella, with vascularity within the superficial portion of the quadriceps tendon being more abundant than in the deep layers (vastus intermedius).22 Hadjicostas et al.23 investigated the quadriceps and patellar tendon morphology using light and electron microscopy, immunohistochemistry, and morphometry. Harris et al.11 had previously used morphometric analysis to show that the thickness of the quadriceps tendon was 1.8 times that of the patellar tendon and that the quadriceps tendon had significantly higher ultimate strength.
The autograft of choice for anterior cruciate ligament (ACL) reconstruction remains controversial. Recently, there has been an increase in interest in the quadriceps tendon as an autologous graft option for ACL reconstruction. The purposes of this study were to provide an in-depth review of quadriceps tendon anatomy, histology, and biomechanics and to synthesize reported clinical outcomes of ACL reconstructions using quadriceps tendon autografts. We hypothesize that (1) published studies on the anatomic, histologic, and biomechanical data regarding the quadriceps tendon support its use as a graft option for ACL reconstruction and (2) clinical outcomes of ACL reconstruction using quadriceps tendon autograft have similar clinical outcomes to bone–patellar tendon–bone autografts with less donor-site morbidity.
We performed a comprehensive review of the literature regarding the anatomy, histology, and biomechanical studies of the quadriceps tendon, as well as a systematic review of clinical studies (Level of Evidence I-III) evaluating outcomes after ACL reconstruction using quadriceps tendon autograft. Stability outcomes, functional outcomes, range of motion, patient satisfaction, morbidity, and complications were comprised.
Fourteen studies were included in the review of clinical results, including 1,154 ACL reconstructions with quadriceps tendon autograft. Six studies directly compared quadriceps tendon autografts (n = 383) with bone–patellar tendon–bone autografts (n = 484). Stability outcomes (Lachman, pivot-shift, and instrumented laxity testing), functional outcomes (International Knee Documentation Committee and Lysholm scores), overall patient satisfaction, range of motion, and complications were similar between quadriceps tendon and other graft options. Less donor-site morbidity was seen in patients who underwent quadriceps tendon ACL reconstructions.
Use of the quadriceps tendon autograft for ACL reconstruction is supported by current orthopaedic literature. It is a safe, reproducible, and versatile graft that should be considered in future studies of ACL reconstruction.
Level III, systematic review of Level I, II, and III studies.
Current trends in graft choice for anterior cruciate ligament reconstruction – part I: anatomy, biomechanics, graft incorporation and fixation
2023, Journal of Experimental Orthopaedics

View all citing articles on Scopus

: Research was performed at the Department of Pathology, University of Heidelberg. The authors report no conflict of interest.

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Original ArticleComparative Analysis of the Morphologic Structure of Quadriceps and Patellar Tendon: A Descriptive Laboratory Study

Section snippets

Tissues

Results

Discussion

Conclusions

Acknowledgment

Arthroscopy

Arthroscopy

Arthroscopy

Arthroscopy

Arthroscopy

Reconstruction of the anterior cruciate ligamentA technique using the central one-third of the patellar ligament

J Bone Joint Surg Am

Secondary reconstruction of anterior cruciate ligament in athletes by using the semitendinosus tendonPreliminary report of 78 cases

Am J Sports Med

A method for replacement of the anterior cruciate ligament of the kneeReport of twenty cases

J Bone Joint Surg Am

Anterior cruciate ligament reconstruction using quadriceps patellar tendon graftPart II. A specific sport review

Am J Sports Med

Long-term followup of anterior cruciate ligament reconstruction using the quadriceps tendon substitution for chronic anterior cruciate ligament insufficiency

Am J Sports Med

The anterior cruciate ligament: A technique of repair and reconstruction

Clin Orthop Relat Res

Arthroscopically assisted ACL reconstruction using autologous quadriceps tendon

Central quadriceps tendon for anterior cruciate ligament reconstructionPart 1: Morphometric and biomechanical evaluation

Am J Sports Med

Original Article
Comparative Analysis of the Morphologic Structure of Quadriceps and Patellar Tendon: A Descriptive Laboratory Study