Anatomical evaluation of the rectus femoris tendon and its related structures

A novel surgical technique for revision anterior cruciate ligament reconstruction using an isolated rectus femoris tendon autograft

INTRODUCTION

Only a few anatomic studies have described an isolated rectus femoris tendon autograft for anterior cruciate ligament (ACL) reconstruction. This study aims to demonstrate a new surgical technique utilising the rectus femoris tendon for ACL reconstruction. This study hypothesises that the rectus tendon autograft will yield satisfying postoperative outcomes in terms of stability, with minimal complications at the harvest site.

METHODS

This retrospective study investigated the outcomes of 28 revision ACL reconstructions using a rectus tendon autograft with a mean follow-up of 41.7 (range, 24.0-64.8) months. A 3 cm longitudinal incision was used to harvest the rectus tendon with an open tendon stripper. Intraoperative collected data included the length of the tendon and thickness of a 4-fold graft. Further outcome parameters include anterior cruciate ligament stability and range of motion. Additionally, postoperative complications, especially donor site morbidity, were documented in type and frequency.

RESULTS

The mean tendon length measured 32.4 cm (range, 30-35 cm). After preparing a 4-fold graft, the mean diameter was 9.2 mm (range, 8.0-10 mm) at the tibial and 9.0 mm (range, 7.5-10 mm) at the femoral end. Stability evaluated by the Lachman test improved significantly from 2 (Interquartile range (IQR), 2-3) preoperatively to 0 (IQR, 0-1) postoperatively (p < .001). Rerupture of the anterior cruciate ligament graft was observed in 2 patients (7.1%). Four patients showed a persistent extension deficit of about 5 degrees postoperatively. Two of them underwent revision surgery due to a Cyclops lesion. Only one patient complained of prolonged pain at the harvest site (3.6%).

CONCLUSION

The 4-fold rectus tendon represents a novel autograft technique in revision ACL reconstruction. This study provides evidence of appropriate graft dimensions and satisfying postoperative outcomes regarding stability. The technique is associated with a low complication rate at the harvest site.

STUDY DESIGN

Case series; Level of evidence, IV.

The accessory heads of the quadriceps femoris muscle may affect the layering of the quadriceps tendon and potential graft harvest lengths

PURPOSE

The aim of the study was to assess the quadriceps femoris system for the presence of additional layers.

METHODS

One hundred and twenty-eight lower limbs fixed in 10% formalin were examined.

RESULTS

Five types of quadriceps tendon layering were found based on the accessory heads of the quadriceps muscle. Type I (55%)-represented by four heads and four layers, and it was something new because standard orthopaedic textbooks described quadriceps tendon as a structure composed of only three layers. Type II (27.4%)-the first four layers were the same as in Type 1, but the accessory tendon of the fifth head of the quadriceps femoris muscle had the deepest attachments. Type III (10.9%)-this type included 6 heads of quadriceps femoris. It consisted of five layers. Type IV (3.1%)-this type included 7 quadriceps femoris heads. This type consisted of only four layers. Type V (3.1%)-this type included 8 heads of the quadriceps femoris heads. This type consist of 5 layers.

CONCLUSION

The findings of this study provide a detailed anatomy of the quadriceps tendon including the accessory tendons of the accessory heads of the quadriceps tendon. The accessory heads of the quadriceps femoris muscle contribute to the layering of the quadriceps tendon. The second conclusion of this study is the development of safe distances depending on the types. Not all types are perfect for harvesting-Type IV seems to be the safest type, in turn Type V the most dangerous.

Distribution of the tensor of the vastus intermedius

The tensor of the vastus intermedius (TVI) was first described by Grob et al. in 2016. It originates from the anteroinferior greater trochanter and inserts into the upper patella and receives blood and nerves independently of other muscles. It has been overlooked, but since micro-surgery and detailed rehabilitation treatments are being developed, more research on it is warranted. Here we report on the TVI in a Korean cadaveric study. A total of 58 cadavers (41 males and 17 females) were included. Thighs were examined using a standardized dissection protocol. The quadriceps femoris muscle was identified and its components were defined by blunt dissection. A total of 116 lower limbs were dissected. In 40 of them, there was a separately innervated TVI muscle belly between the fasciae of the vastus lateralis (VL) and the vastus intermedius (VI) muscles. TVIs were classed as independent (ID), VI, and VL types according to the relative relationship between the TVI, VL, and VI, and subdivided into two parts: Part 1 was the proximal muscular portion of the TVI attached to the VL or VI, and part 2 was the distal aponeurotic area. TVIs were analyzed in detail via 58 Korean cadavers. We subdivided them on the basis of their location and association with related muscles. A larger study is needed to clarify the function and prevalence of the TVI.

A new look at quadriceps tendon - Is it really composed of three layers?

BACKGROUND

The aim of this study was to qualitatively and quantitatively describe the anatomy of the QT including its size, its layers and relationship between layers.

METHODS

Sixty lower limbs (15 females and 15 males fixed in 10% formalin were examined. A retrospective analysis of 20 thigh MRI examinations was performed (10 males, and 10 females).

RESULTS

In all dissected specimens, the quadriceps femoris was composed of 4 layers: superficial (first layer), middle (second layer), middle-deep (third layer) and deep (fourth layer). The first layer (superficial) was formed by the rectus femoris tendon and fascia. The second layer was composed of tendons of the vastus medialis and superficial part of the vastus lateralis. The third layer was formed by the intermediate part of the vastus lateralis. The fourth layer was composed of the tendon of the vastus intermedius. This type of anatomy was visualized in 4 males and 2 female on MRI scans.

CONCLUSION

The findings of this study provide a detailed anatomy of the quadriceps tendon. There were 4 different layers of the QT consistently found in all specimens. The first layer was independent and composed by the rectus femoris tendon, the second was formed by the superficial part of the vastus lateralis and vastus medialis. The third layer was formed by the intermediate part of the vastus lateralis, and the deepest fourth layer was composed of the vastus intermedius. This detailed structural anatomy was also able to be visualized on MRI scans.

Relationship between anatomical injury site of rectus femoris muscle strain and time taken to return to play in Japanese professional soccer players

PURPOSE

The rectus femoris has three myotendinous or myoaponeurosis junctions and causes three types of muscle strain anatomically. We aimed to investigate the anatomical injury site of the rectus femoris muscle strain in professional soccer players as well as the characteristic findings on magnetic resonance imaging (MRI) and to evaluate its relationship with the time taken to return to play at competition levels.

METHODS

Thirteen Japanese professional soccer players who sustained injuries to the rectus femoris were included in this study. The mechanism of injury, anatomical injury site, severity, absence of hematomas, and time taken to return to competition were evaluated.

RESULTS

Ten patients were injured while kicking and three while sprinting. The anatomical injury site was the origin aponeurosis in two cases, intramuscular tendon in eight cases, and distal aponeurosis in three cases. The severity was one-degree in three cases and two-degree in 10 cases. Hematomas were observed in five cases. Cases with injuries caused by sprinting, two-degree injuries, or clear hematomas were associated with significantly longer periods of return to play than the other cases. Additionally, patients with distal aponeurosis-type injuries tended to take a long time to return to the competition.

CONCLUSIONS

In rectus femoris muscle strain, it is important to evaluate the anatomical injury site, severity, and absence of hematomas on MRI. Not only the injury mechanism, a clear hematoma, and high severity but also distal aponeurosis injuries may be associated with long periods of return to play at competition levels.

Quadriceps tendon autograft for anterior cruciate ligament reconstruction: state of the art

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.

Quadriceps Tendon Lengthening for Obligatory (Habitual) Patellar Dislocation in Flexion

Obligatory patella dislocation in flexion is an uncommon form of patellar instability, where the patella is located in extension and dislocates with every episode of knee flexion. This results in dramatically altered patellofemoral kinematics and can be extremely debilitating due to extensor strength deficits and lack of knee confidence in flexion. Concomitant pathology, which is often seen, includes a tight lateral retinaculum and a shortened extensor mechanism. Lengthening the extensor mechanism is a critical part of successful patellar stabilization, and has not been well-reported. Herein, we present a technique of quadriceps lengthening for the treatment of obligatory patellar dislocation.

Full thickness quadriceps tendon grafts with bone had similar material properties to bone-patellar tendon-bone and a four-strand semitendinosus grafts: a biomechanical study

PURPOSE

Despite increasing interest in utilizing quadriceps tendon (QT) grafts in anterior cruciate ligament reconstruction (ACLR), data on the optimal quadriceps graft thickness are limited. The purpose of this study was to characterize the mechanical properties for the quadriceps tendon, comparing full-thickness (FT) QT grafts with and without bone to a partial-thickness (PT) QT graft, and comparing the three QT grafts to four-stranded semitendinosus (4-SST) and bone-patellar tendon-bone (BTB) grafts and one experimental graft, the two-stranded rectus femoris (RF).

METHODS

Forty-eight (n = 48) young cadaveric grafts (mean age 32 ± 6 years) were utilized for testing with N = 8 specimens in each of the following groups; (1) FT QT with bone, (2) FT QT without bone, (3) PT QT without bone, (4) BTB, (5) RF, and (6) 4-SST. Each specimen was harvested and rigidly fixed in custom clamps to a dynamic tensile testing machine for biomechanical evaluation. Graft ultimate load and stiffness were recorded. Independent groups one-factor ANOVAs and Tukey's pairwise comparisons were performed for statistical analyses.

RESULTS

FT QT with bone and 4-SST grafts demonstrated similar ultimate loads to BTB grafts (both n.s), whereas PT QT demonstrate statistically significantly lower ultimate loads to BTB grafts (n.s) and 4-SST grafts (n.s). Furthermore, no statistically significant differences were observed between the ultimate loads of FT QT vs. PT QT grafts without bone (n.s) or between FT QT with vs. without bone (n.s). FT QT grafts with bone did not demonstrate statistically significantly greater ultimate loads than PT QT grafts without bone (n.s). The RF graft demonstrated statistically significantly lower ultimate loads to BTB grafts (p < 0.005) and 4-SST grafts (p < 0.014).

CONCLUSIONS

Full thickness QT grafts with bone had similar material properties to BTB and a 4-SST grafts, while Partial thickness QT graft without bone had significantly lower material properties than BTB and 4-SST, in a biomechanical setting.

Current and future of anterior cruciate ligament reconstruction techniques

In recent years, anterior cruciate ligament (ACL) reconstruction has generally yielded favorable outcomes. However, ACL reconstruction has not provided satisfactory results in terms of the rate of returning to sports and prevention of osteoarthritis (OA) progression. In this paper, we outline current techniques for ACL reconstruction such as graft materials, double-bundle or single-bundle reconstruction, femoral tunnel drilling, all-inside technique, graft fixation, preservation of remnant, anterolateral ligament reconstruction, ACL repair, revision surgery, treatment for ACL injury with OA and problems, and discuss expected future trends. To enable many more orthopedic surgeons to achieve excellent ACL reconstruction outcomes with less invasive surgery, further studies aimed at improving surgical techniques are warranted. Further development of biological augmentation and robotic surgery technologies for ACL reconstruction is also required.

Qualitative and Quantitative Anatomy of the Human Quadriceps Tendon in Young Cadaveric Specimens

Background:

A detailed understanding of the anatomy of the quadriceps tendon (QT) is clinically relevant, owing to its increased use as a graft in anterior cruciate ligament reconstruction.

Purpose:

To qualitatively and quantitatively describe the anatomy of the QT in younger adult specimens.

Study Design:

Descriptive laboratory study.

Methods:

A total of 18 nonpaired cadaveric knees with a mean age of 30.1 years (range, 18-38 years) were utilized for this study. A 3-dimensional coordinate measuring system was used to assess the structural relationships between the different layers of the QT and their attachments to the patella, and QT thickness was measured medially, centrally, and laterally at 2-cm intervals from the patellar eminence line (PEL; defined as a straight line between the medial and lateral patellar eminences) and proximally.

Results:

In all specimens, 3 distinct layers formed the QT. The first (superficial) layer was formed by the rectus femoris, which was fused to the second layer with an unclearly defined direct attachment to the patella. The median length of the QT was 86.9 mm (range, 68.4-98.9 mm). The second (middle) layer consisted of the vastus medialis and vastus lateralis and was found to have fibers running in an oblique direction that attached on the patella. A “fuse point,” where the proximal part of the rectus femoris started to merge to the second layer, was identified at a median of 48.7 mm (range, 27.9-62.6 mm) from the PEL. The third (deep) layer consisted of the vastus intermedius. The median thickness of the graft centrally at 20, 40, 60, 80, and 100 mm from the PEL was 8.5, 7.2, 7.5, 6.5, and 5.4 mm, respectively.

Conclusion:

Overall, 3 different layers of the QT were consistently found in all specimens. The first layer was fused with the second layer, and the direction of the fibers of the second layer or the vastus medialis and vastus lateralis was oblique. The median length of the QT was 86.9 mm, and the thickness of the tendon diminished proximally.

Clinical Relevance:

This study allows for a better understanding of QT anatomy when harvesting the tendon as a graft for ligamentous reconstruction.

Anatomy, Morphology and Function of the Tensor of Vastus Intermedius: A Systematic Review

The tensor of vastus intermedius is a newly discovered muscle that is located at the anterior compartment of the thigh. The aim of the present study is to report, assess and synthetize the existing evidence on the anatomy, variation and morphological characteristics of the TVI as well as to examine its clinical importance. A systematic review was performed evaluating both anatomical and medical imaging studies which provided information about TVI anatomy, prevalence, variations and morphological characteristics. The search strategy was conducted in major electronic databases. Two reviewers worked independently to screen all possible references via a title/abstract examination. Methodological quality was examined with the Anatomical Quality Assurance checklist. A total of 295 cadaveric knees were included in the nine studies where in 244 (82.7%) cases the TVI was identified. Based on this evidence, it appears that the TVI is located between the vastus lateralis and vastus intermedius. The muscle belly is located proximally, and it is combined with a broad and flat aponeurosis before forming a tendinous structure that is attached at the medial aspect of the patella. The TVI presented some morphological variations and complex muscle architecture that varied along its length. There is insufficient good quality evidence as more than half of the included studies were ranked as having a "High" risk of bias with various methodological issues. Higher quality studies are recommended to evaluate the TVI morphology to better understand its functional and clinical importance.

Intramuscular differences in shear modulus of the rectus femoris muscle during passive knee flexion

PURPOSE

This study aimed to determine (1) intramuscular regional differences in the changes in the shear modulus of the rectus femoris (RF) muscle during passive knee flexion and (2) the relationship between shear modulus and passive knee extension torque.

METHOD

The shear modulus maps as an index of muscle stiffness and the passive torque were obtained at seven regions during passive knee flexion at 2°/s within a knee joint range of motion of 0°-130° in 16 healthy males.

RESULTS

The shear modulus of RF increased with the knee angle of flexion. The shear modulus of each longitudinal region was greater in the order of proximal, central, and distal region (p < 0.05). The relationship between the shear modulus and passive torque was highly fitted for all 16 subjects (p < 0.05). The mean coefficient of determination (R²) at second-order polynomial model per subject was 0.96 (± 0.03; range 0.61-0.99), and whole group was 0.58 (± 0.03; range 0.54-0.64) in all regions.

CONCLUSIONS

The passive stiffness of RF was higher in the proximal region than in the other regions during passive knee flexion. Furthermore, the shear modulus-passive torque was related regardless of the measurement region within a muscle, and the results suggest that the passive knee extension torque reflects passive muscle stiffness of the RF.

Quadriceps tendon autograft for anterior cruciate ligament reconstruction is associated with high revision rates: results from the Danish Knee Ligament Registry

PURPOSE

The quadriceps tendon (QT) has recently gained interest as an anterior cruciate ligament reconstruction (ACLR) autograft. There is a paucity of data from large cohort studies on failures and revision rates after ACLR using the QT graft. The purpose of the present study is to use the Danish Knee Ligament Reconstruction Registry (DKRR) to compare revision rates, objective knee stability and subjective clinical outcomes in patients who have undergone ACLR with QT, hamstring tendon (HT), and patellar tendon (PT) as a graft for ACLR. It was hypothesized that QT autografts would result in similar objective knee stability and revision rates as HT and PT autografts.

METHODS

Data on primary ACLRs in the DKRR from 2005 through 2017 were analyzed. Knee injury and Osteoarthritis Outcome Scores (KOOS), Tegner activity scale scores, sagittal knee laxity, pivot-shift tests at 1-year follow-up and revision rates at 2-year follow-up were compared for the three autograft cohorts.

RESULTS

A total of 531 QT, 14,213 HT and 1835 PT ACLR were registered in the DKLR between 2005 and 2017. QT autograft was associated with statistically significant increased laxity (1.8 mm) compared to HT autograft (1.5 mm) (p < 0.001) and more positive pivot shift. There was a significant higher revision rate for QT (4.7%), compared to PT (1.5%) and HT (2.3%) autografts at 2-year follow-up (p < 0.002).

CONCLUSION

Quadriceps tendon autografts for ACLR was associated with higher revision rates than HT and PT grafts. QT graft was also associated with small increased objective knee laxity and more positive pivot shift than HT and PT grafts.

LEVEL OF EVIDENCE

III.

Anatomical study of quadriceps tendon for anterior cruciate ligament reconstruction

Background

The quadriceps tendon is a promising alternative graft choice for anterior cruciate ligament (ACL) reconstruction. Morphology of the graft directly affects the biomechanical properties. However, a few studies are evaluating the anatomical structures of quadriceps tendon as a graft in Asian population.

Objective

To define the anatomical structures of quadriceps tendon as a graft for ACL reconstruction.

Methods

Forty-nine quadriceps tendons were dissected and analyzed. Measurements were also done including length, width, and thickness.

Results

The maximum length of superficial quadriceps tendon was 63.2 ± 12.5 mm (range 37.6–83.4). The maximum length of tendon at the deepest part was 57.2 ± 11.5 (range 30.9–83.4). The maximum length of quadriceps tendon was located at 61.4% ± 13% (range 31.8–83.6) from medial edge of the patella insertion (approximately 5 mm lateral from the center of quadriceps tendon insertion). The width of quadriceps tendon at patella insertion was 42.4 ± 3.8 mm (range 33.8–50.5). The thickness of quadriceps tendon at its maximum length on patella insertion was 6.9 ± 2.0 mm (range 1.5–9.5). Positive correlation between the height of cadaver and the maximum length of quadriceps tendon was noted.

Conclusions

The maximum length of quadriceps tendon was located 5 mm lateral from the center of quadriceps tendon insertion. Thus, we recommend marking midline of the quadriceps tendon insertion as a medial border of the harvested graft to get maximum length of the graft. Graft length measurement using superficial anatomy should be cautioned because graft shortening might occur.

Quadriceps tendon vs. patellar tendon autograft for ACL reconstruction using a hardware-free press-fit fixation technique: comparable stability, function and return-to-sport level but less donor site morbidity in athletes after 10 years

INTRODUCTION

The use of quadriceps tendon-patellar bone (QTB) autograft for anterior cruciate ligament (ACL) reconstruction is gaining momentum. Yet, long-term results that compare this procedure with established methods are lacking. The aim of this study was to report and compare long-term results of ACL reconstruction using QTB autografts versus bone-patellar tendon-bone (BPTB) autografts, both anchored using a hardware-free press-fit fixation technique.

MATERIALS AND METHODS

60 athletes (Tegner score ≥6) with primary ACL rupture were prospectively randomized into two groups. 56 patients were evaluated after a mean duration of 12.2 ± 1.9 months (range 10-14) and 43 patients after 10.3 ± 0.2 years (range 10-11).

RESULTS

On final follow-up, 90% of patients scored very good and good results in the functional Lysholm score (mean 99 ± 7.1, range 74-100 points). Normal or almost normal IKDC score was reported by 84% of the patients (mean 97 ± 9.5, range 60-100 points). The activity level decreased in the Tegner score from median of 7 before injury to 6 after 10 years. The KT-1000 arthrometer showed a difference in the anterior translation of less than 3 mm (mean 1.0 ± 1.2, range - 1 to 5 mm) in 91% of the patients. Significant degeneration was radiologically detected in one patient per group. No tunnel widening was seen in any patient. Up to 97% of all patients were satisfied with the operative procedure. No significant differences were found in the mentioned parameters between the two groups and also in comparison with the 1-year results. The only significant difference was in the donor site morbidity. Significantly more patients in the BPTB group had complaints during kneeling both at 1 (p < 0.001) and 10 years (p = 0.019). Squatting was also subjectively more problematic in the BPTB group than in the QTB group both after 1 (p = 0.003) and 10 years (p = 0.046).

CONCLUSIONS

This study shows equally good functional, clinical and radiological long-term results for both hardware-free methods of ACL reconstruction. These results clinically confirm the safety of press-fit anchoring after 10 years. The failure rate in this study was very low, with only one re-rupture in 10 years. The increased donor site morbidity when using the BPTB autograft compared to the QTB autograft supports already reported data. It was also seen in this study for the implant-free press-fit techniques.

STUDY DESIGN

Prospective and randomized, level of evidence 2.

Quadriceps tendon grafts does not cause patients to have inferior subjective outcome after anterior cruciate ligament (ACL) reconstruction than do hamstring grafts: a 2-year prospective randomised controlled trial

OBJECTIVE

We performed a randomised controlled trial (RCT) in patients undergoing ACL reconstruction (ACLR) using either quadriceps tendon graft (QT) or semitendinosus/gracilis hamstring (STG) graft. We compared subjective outcome (primary outcome) and knee stability, donor site morbidity and function (secondary outcomes).

METHODS

From 2013 to 2015, we included 99 adults with isolated ACL injuries in the RCT. Fifty patients were randomised to QT grafts and 49 to STG grafts and followed for 2 years. Patient evaluated outcomes were performed by subjective International Knee Documentation Committee, Knee Injury and Osteoarthritis Outcome Score, Kujala and Tegner activity scores. Knee laxity was measured with a KT-1000 arthrometer. Donor site morbidity was evaluated by the 'donor site-related functional problems following ACLR score'. One-leg hop test tested limp strength symmetry.

RESULTS

At 2-year follow-up, there was no difference between the two graft groups regarding subjective patient outcome, knee stability and reoperations. Also, at 2 years, donor site symptoms were present in 27% of patients in the QT group and 50% of patients in the STG group. The donor site morbidity score was 14 and 22 for the QT and STG, respectively. Hop test demonstrated lower limp symmetry for QT graft than STG graft of 91% and 97% respectively.

CONCLUSION

QT graft for ACLR did not result in inferior subjective outcome compared with STG graft. However, QT graft was associated with lower donor site morbidity than STG grafts but resulted in more quadriceps muscle strength deficiency than hamstring grafts. Both graft types had similar knee stability outcome.

TRIAL REGISTRATION NUMBER

NCT02173483.

Magnetic resonance imaging of the quadriceps tendon autograft in anterior cruciate ligament reconstruction

BACKGROUND

Quadriceps tendon (QT) autograft is emerging as a popular technique for primary anterior cruciate ligament (ACL) reconstruction. Studies have shown that it has comparable outcomes to bone-patellar tendon-bone (BPTB) and hamstring tendon (HT) autografts while mitigating post-operative complications associated with these grafts.

PURPOSE

To provide a literature summary of the important pre- and post-operative magnetic resonance imaging (MRI) findings of the quadriceps tendon and pertinent postoperative complications associated with the QT harvest. Radiologists should be familiar with MR findings after autologous graft harvest of the quadriceps tendon for reconstruction of the ACL.

LEVEL OF EVIDENCE

Level IV.

Quadriceps Tendon Autograft Medial Patellofemoral Ligament Reconstruction

PURPOSE

Critically evaluate the published literature related to quadriceps tendon (QT) medial patellofemoral ligament (MPFL) reconstruction.

RECENT FINDINGS

Hamstring tendon (HT) MPFL reconstruction techniques have been shown to successfully restore patella stability, but complications including patella fracture are reported. Quadriceps tendon (QT) reconstruction techniques with an intact graft pedicle on the patella side have the advantage that patella bone tunnel drilling and fixation are no longer needed, reducing risk of patella fracture. Several QT MPFL reconstruction techniques, including minimally invasive surgical (MIS) approaches, have been published with promising clinical results and fewer complications than with HT techniques. Parallel laboratory studies have shown macroscopic anatomy and biomechanical properties of QT are more similar to native MPFL than hamstring (HS) HT, suggesting QT may more accurately restore native joint kinematics. Quadriceps tendon MPFL reconstruction, via both open and MIS techniques, have promising clinical results and offer valuable alternatives to HS grafts for primary and revision MPFL reconstruction in both children and adults.

Nonuniform Deformation of the Patellar Tendon During Passive Knee Flexion

The purpose of this study was to evaluate localized patterns of patellar tendon deformation during passive knee flexion. Ultrasound radiofrequency data were collected from the patellar tendons of 20 healthy young adults during knee flexion over a range of motion of 50°-90° of flexion. A speckle tracking approach was used to compute proximal and distal tendon displacements and elongations. Nonuniform tissue displacements were visible in the proximal tendon (P < .001), with the deep tendon undergoing more distal displacement than the superficial tendon. In the distal tendon, more uniform tendon motion was observed. Spatial variations in percent elongation were also observed, but these varied along the length of the tendon (P < .002), with the proximal tendon remaining fairly isometric while the distal tendon underwent slight elongation. These results suggest that even during passive flexion the tendon undergoes complex patterns of deformation. Proximal tendon nonuniformity may arise from its complex anatomy where the deep tendon inserts onto the patella and the superficial tendon extends to the quadriceps tendon. Such heterogeneity is not captured in whole tendon average assessments, emphasizing the relevance of considering localized tendon mechanics, which may be key to understanding tendon behavior and precursors to injury and disease.

The evaluation of muscle recovery after anatomical single-bundle ACL reconstruction using a quadriceps autograft

PURPOSE

The purpose of this study was to reveal the degree of muscle recovery and report the clinical results of anatomical single-bundle ACL reconstruction using a quadriceps autograft.

METHODS

Twenty subjects undergoing anatomical single-bundle ACL reconstruction using a quadriceps autograft were included in this study. A 5-mm-wide, 8-cm-long graft, involving the entire layer of the quadriceps tendon, was harvested without bone block. The average graft diameter was 8.1 ± 1.4 mm. An initial tension of 30 N was applied. The femoral tunnel was created from the far-medial portal. Each femoral and tibial tunnel was created close to the antero-medial bundle insertion site. For the evaluation of muscle recovery (quadriceps and hamstring), a handheld dynamometer was used. The evaluation of muscle recovery was performed pre-operatively, and at 3, 6, 9, and 12 months after surgery. Muscle recovery data were calculated as a percentage of leg strength in the non-operated leg. Anterior tibial translation (ATT), pivot shift test, and IKDC score were evaluated.

RESULTS

The average quadriceps strength pre-operatively, and at 3, 6, 9, and 12 months after ACL reconstruction was 90.5 ± 19, 67.8 ± 21.4, 84 ± 17.5, and 85.1 ± 12.6 %, respectively. The average hamstring strength pre-operatively, and at 3, 6, 9, and 12 months after ACL reconstruction was 99.5 ± 13.7, 78.7 ± 11.4, 90.5 ± 19, and 96.7 ± 13.8 %, respectively. ATT pre-operatively and at 12 months after surgery was 5.4 ± 1.3 and 1.0 ± 0.8 mm, respectively. No subjects exhibited positive pivot shift after surgery. Within 6 months following surgery, quadriceps hypotrophy was observed in all subjects. However, the hypotrophy had recovered at 12 months following surgery. No subjects complained of donor site pain after surgery.

CONCLUSION

Anatomical single-bundle ACL reconstruction using a quadriceps autograft resulted in equivalent level of muscle recovery and knee stability when compared with previously reported ACL reconstruction using hamstrings tendon with no donor site complications.

LEVEL OF EVIDENCE

Case controlled study, Level III.

New insight in the architecture of the quadriceps tendon

BACKGROUND

Published data regarding the structure of the quadriceps tendon are diverse. Dissection of the quadriceps muscle group revealed that beside the rectus femoris, vastus lateralis, vastus intermedius and vastus medialis a fifth muscle component- named the tensor vastus intermedius consistently fused into quadriceps tendon. It can be hypothesized that all these elements of the extensor apparatus of the knee joint must also be represented in the quadriceps tendon. This study investigated the multi-layered quadriceps tendon with special emphasis on all components of the quadriceps muscle group including the newly discovered tensor vastus intermedius.

METHODS

Ten cadaveric lower limbs were dissected. All muscle bellies of the extensor apparatus of the knee joint were identified and traced distally until they merged into the quadriceps tendon. Connections between the different aponeurotic layers of each muscle were studied from origin to insertion. The fusing points of each layer were marked. Their distance to the patella and the distances between the fusing points were measured.

RESULTS

Six elements of the quadriceps muscle group form a tri-laminar structure of the quadriceps tendon. The intermediate layer could be further sub-divided. The elements of the quadriceps tendon are 1. lateral aponeurosis of the vastus intermedius, 2. deep and 3. superficial medial aponeurosis of the vastus intermedius, 4. vastus lateralis, 5. tensor vastus intermedius and 6. rectus femoris. Even with differences in fiber direction - these elements join each other a certain distance proximal to the patella. All elements were fused over a region measuring 13 to 90 mm proximal to the patella. Lateral parts of the vastus intermedius formed the deepest layer of the quadriceps tendon. The superficial and deep layer of the medial vastus intermedius aponeurosis fused 56 mm (range, 30 to 90 mm) and 33 mm (range, 13 to 53 mm) above the patella with the aponeurosis of the tensor vastus intermedius and vastus lateralis respectively. Together they built the two-layered intermediate layer of the quadriceps tendon. The tendon of the rectus femoris forms the superficial layer. The vastus medialis inserts medially in all layers of the quadriceps tendon. Fibers of the lateral muscle components were oriented towards the medial, and fibers of the medial muscle components were oriented towards the lateral femoral condyle.

CONCLUSIONS

The three-layered quadriceps tendon is formed by six elements. These are 1. lateral aponeurosis of the vastus intermedius, 2. deep and 3. superficial medial aponeurosis of the vastus intermedius, 4. vastus lateralis, 5. tensor vastus intermedius and 6. rectus femoris. These elements of the extensor apparatus join each other proximal to the patella in a complex onion-like architecture. Its two-layered intermediate layer shows variable fusions points. The vastus medialis contributes to the quadriceps tendon with its medial insertion into all layers of the quadriceps tendon.

Minimally invasive harvest of a quadriceps tendon graft with or without a bone block

The quadriceps tendon (QT) as a graft source for anterior cruciate ligament (ACL) and posterior cruciate ligament reconstruction has recently achieved increased attention. Although many knee surgeons have been using the QT as a graft for ACL revision surgery, it has never gained universal acceptance for primary ACL reconstruction. The QT is a very versatile graft that can be harvested in different widths, thicknesses, and lengths. Conventionally, the QT graft is harvested by an open technique, requiring a 6 to 8 cm longitudinal incision, which often leads to unpleasant scars. We describe a new, minimally invasive, standardized approach in which the QT graft can be harvested through a 2- to 3-cm skin incision and a new option of using the graft without a bone block.