Innervation of vastus lateralis muscle

Comparative Study of the Morphological Characteristics of Perforators of the Transverse and Descending Branches of the Lateral Circumflex Femoral Artery in Anterolateral Thigh Flap Surgery

BACKGROUND

The anterolateral thigh flap (ALTF) is a kind of lateral thigh flap that uses branches of the lateral circumflex femoral artery (LCFA) as the vessel pedicle and is widely used in plastic surgery. During classic ALTF surgery, some perforators from the descending branch of the lateral circumflex femoral artery (LCFA-db) are hard to harvest due to their anatomical variants and individual differences; thus, it is necessary to design an appropriate alternative surgical plan. The transverse branch of the LCFA (LCFA-tb) has unique advantages and can be a potential complement to ALTF vascular pedicle selection. The aim of this study was to compare the difference in morphology between LCFA-db and LCFA-tb, and to verify the feasibility and clinical effect of ALTF with LCFA-tb as the source artery.

METHODS

The morphological and clinical data of patients who underwent wound repair of the extremities with the ALTF pedicled with the LCFA-tb and LCFA-db were retrospectively analyzed. This study consisted of the clinical data of 62 patients who accepted an ALTF pedicled with LCFA-tb, and 45 patients accepted an ALTF pedicled with LCFA-db.

RESULTS

A total of 68 cutaneous perforators originating from the LCFA-tb were found in the surgical field, of which 35 perforators were direct cutaneous perforators (51.5%), 28 perforators were septocutaneous perforators (41.2%), and 5 perforators were musculocutaneous perforators (7.3%). Seventy-four cutaneous perforators were found in the LCFA-db group. The proportions of septocutaneous perforators and musculocutaneous perforators were 23% and 77%, respectively, and the number of direct cutaneous perforators was 0. The harvest time of flaps pedicled with LCFA-tb was remarkably shortened. Regarding prognosis, there were no significant differences between the curative effects of the 2 types of flaps.

CONCLUSIONS

This study verified that most LCFA-tb perforators are direct cutaneous perforators and that the piercing-in positions of LCFA-tb perforators on superficial fascia were higher than those of LCFA-db perforators. Furthermore, the ALTF pedicled with LCFA-tb can provide satisfactory soft tissue reconstruction and can be used as a useful supplement to the traditional flap design.

Anatomical Relations of the Perforators from the Descending Lateral Femoral Circumflex Artery and Vastus Lateralis Motor Nerve Branches

Background

The anterolateral thigh (ALT) flap, which is nourished by perforators from the descending branch of the lateral femoral circumflex artery (P), is one of the most commonly used flaps in soft tissue reconstruction. With the growing use of ALT flaps, attention toward donor-site morbidity has increased in recent years. Damage to the motor nerve branches of the vastus lateralis muscle (N) is one of the causes of donor-site morbidity, particularly muscle weakness. This study investigated the anatomical locations of the P and N in fresh-frozen cadaveric specimens.

Methods

This study included 43 cadaver limbs. A silicone rubber compound (30 mL) was injected into the femoral artery to visualize the vessel. The locations of the P and motor points of N were measured to assess the risk of N injury during ALT flap harvesting.

Results

There were one to six (mean, 2.7) P and two to seven (mean, 4) N. When the two most proximal perforators were used for flap harvesting, an average of 1.5 motor nerve branches (42%) was damaged because transection of the motor nerve branches was required for flap harvesting. In 33% of the limbs, only one motor nerve branch remained after the flap harvest. However, there were no cases where all motor nerve branches were severed.

Conclusion

When an ALT flap with two perforators is harvested, weakness of the vastus lateralis muscle may occur in cases with a small number of motor nerve branches.

Anatomic and histomorphometric study of the nerve to the vastus lateralis in cadaver for its clinical application in facial reanimation

BACKGROUND

The innervated vastus lateralis flap (IVLF) is a barely used possibility for facial palsy reconstruction because of its thickness compared to the gracilis, latissimus dorsi, and pectoralis minor flaps. The aim of this study is to perform a precise description of the intramuscular distribution of the nerve motor branches and its relationship with the vascular pedicle in order to harvest a segmental muscle flap with the best contractile strength to restore facial reanimation.

METHODS

The study was performed on 16 adult cadaver thighs identifying the vastus lateralis muscle and the distribution and relationships of its neurovascular pedicle and branches. We evaluated where the nerve pierced the muscle and the course of the nerve within it. Transverse segments of the nerve were obtained from the proximal and distal ends of the nerve and stained using anti-ChAT (Choline acetyltransferase) antibodies which are specific of motor neurons.

RESULTS

A nerve for the vastus lateralis from the posterior division of the femoral nerve divided into 2 branches in 56% of cases; the principal branch coursed along the vascular pedicle and pierced the muscle more proximally than the respective vessels, and a minor branch that pierced the muscle 25-60 mm proximally. There were 3 main intramuscular branches. The nerve length (mean 132.65 ± 22.89 mm) allowed to reach the contralateral side of the face in almost all cases (95%). The mean ChAT positive fibers was 351.0 ± 92.4/mm² at the proximal end, and 270.3 ± 87.9/mm² at the distal end (p = 0.49). The number of ChAT negative fibers was higher than ChAT positive in both proximal and distal ends of the nerve.

CONCLUSION

We propose the IVLF as a one-step surgical flap for facial paralysis reanimation due to the constant neurovascular pattern and lengthy pedicle. The amount of motor fibers in several segments of the nerve is appropriate to produce a powerful contraction for dynamic reconstruction.

Incidence of and Risk Factors for Lateral Trochanteric Pain After Direct Anterior Approach Total Hip Arthroplasty

Lateral trochanteric pain (LTP) is a common complication after total hip arthroplasty (THA). The goals of this study were to report the incidence of LTP after direct anterior approach (DAA) THA, describe the treatment course and outcomes, and examine patient-specific and implant-related potential risk factors. A retrospective review identified patients who underwent primary DAA THA with at least 1-year follow-up. Postoperative functional outcome scores and LTP occurrence were recorded. Patient demographics, surgical indications, implant characteristics, medical comorbidities, and radiographic parameters were obtained. Logistic regression analysis was used to identify risk factors. A total of 610 THA procedures were performed for 563 patients (mean follow-up, 30.9±15.2 months). The overall incidence of LTP was 11.6%. All cases of LTP were successfully treated conservatively, although these patients, compared with patients who did not have postoperative LTP, experienced significantly lower functional outcome scores (Harris Hip Score, 96.6±4.7 [range, 55-100] vs 89.9±8.5 [range, 42-100], respectively; P<.001). Logistic regression analysis identified female sex (odds ratio, 2.30; 95% CI, 1.32-4.02), diabetes mellitus (odds ratio, 2.32; 95% CI, 1.11-4.88), hypertension (odds ratio, 1.94; 95% CI, 1.15-3.28), and the use of an offset acetabular liner (odds ratio, 2.50; 95% CI, 1.06-5.91) as independent risk factors for LTP. There was no correlation between LTP and radiographic parameters. The incidence of LTP after DAA THA is similar to reported rates for other THA surgical approaches. Female sex, medical comorbidities, and the use of offset acetabular liners are likely associated, and patients should be counseled appropriately. Postoperative LTP results in worse functional outcomes, although all cases can be treated conservatively. [Orthopedics. 2022;45(2):e79-e85.].

Preliminary Functional Outcomes and Quality of Life after Tongue Reconstruction with the Vastus Lateralis Myofascial Free Flap

The aim of the present study is to report our preliminary experience with the vastus lateralis myofascial free flap (VLMFF) for tongue reconstruction according to tongue and donor site functional outcomes. Twelve consecutive patients (F: 5; median age: 54.0 years, interquartile range or IQR 42.75-69.0) were included. The validated European Organization for Research and Treatment of Cancer of the Head and Neck 35 Quality of Life Questionnaire (EORTC QLQ-H&N35) and the performance status scale for head and neck cancer (PSS-HN) questionnaires were used to assess the health-related quality of life (HRQOL). The lower extremity functional scale (LEFS) was used to self-report the donor area function. All patients were successfully treated, and no VLMFF failure was detected during a median follow-up period of 10.5 months (IQR: 6.5-33.0). The HRQOL showed a median EORTC QLQ-H&N35 score of 56.0 (IQR: 50.0-72.5). The median PSS-HN score was 80.0 (IQR: 45.0-95.0), 75.0 (IQR: 62.5-100.0), 75.0 (IQR: 62.5-100.0) for "Normalcy of Diet," "Public Eating," and "Understandability of Speech," respectively. The self-reported function of the lower extremities (donor area) showed a median LEFS of 59.0 (IQR: 32.5-74.0). This study reports optimistic data regarding the functional and quality of life outcomes after tongue reconstruction using VLMFF. Prospective controlled studies are needed to demonstrate advantages and disadvantages when compared with other reconstructive techniques.

The proximal vastus lateralis flap: An anatomical and radiological study

INTRODUCTION

Soft-tissue reconstruction following acetabular or proximal femur resection for bone tumors is challenging. The vastus lateralis flap has been proposed as an advancement or rotational flap to cover soft-tissue defects for such locoregional indications. We performed an anatomical and a radiological study to assess the vascularization of the proximal vastus lateralis muscle achieved through the transverse branch of the lateral circumflex femoral artery in order to decrease the morbidity of the classical flap retrieval technique.

MATERIAL AND METHODS

Five fresh adult cadavers were dissected bilaterally. Each vastus lateralis dissection was prealably injected with contrast-media agent through the lateral circumflex artery and CT scan images was recorded. A descriptive and an analytical study were carried out.

RESULTS

The median length and width of the entire muscle were 31.2cm (Q1-Q3: 29.7-33.3) and 12.7cm (Q1-Q3: 7.0-14.9), respectively; the median surface area of the entire vastus lateralis muscle was 282cm² (Q1-Q3: 172.6-455.6) cm². The median length and width of the perfused area were 13.3cm (Q1-Q3: 12.3-16.6) and 9.4cm (Q1-Q3: 6.9-8.8) cm, respectively; the median surface of the perfused area was 89.4cm² (Q1-Q3: 67.4-110.5) cm². The mean length of the pedicle measured on the CT scan was 6.3cm (95% CI: 5.5-7.1).

CONCLUSION

The proximal vastus lateralis flap as a pedicled muscular flap supplied by the transverse branch of the lateral circumflex femoral artery is a muscular flap that can be used by reconstructive and orthopaedic surgeons to repair soft-tissue defects around the hip joint without undue damage to the functional apparatus of the knee.

Gross anatomical investigation of the muscular head between the vastus lateralis and intermedius in the Japanese population: a cadaver study

Unlike the general understanding of the quadriceps femoris, the existence of a new muscular head between the vastus lateralis and the vastus intermedius was reported, and named the tensor of the vastus intermedius in the Swedish population. The purpose of this study was to investigate the presence and form of the muscular head in the Japanese population and to clarify its structure by gross anatomical approaches. A total of 35 thighs of 20 Japanese cadavers were investigated. We searched for the muscular head and classified it into four types. In addition, nerve fiber analysis was performed for each classification type. Regarding classification, 11% were the independent type, 29% were the common type, 37% were the vastus lateralis type, and 23% were the vastus intermedius type. Based on nerve fiber analysis, in the common type, the muscular head was under dual nerve supply from the vastus lateralis and intermedius. The other three types were innervated only by nerves from the vastus lateralis. The target muscular head may always be present in Japanese. The nerves from the vastus lateralis were always distributed in the target muscular head based on nerve fiber analysis; therefore, this muscular head may be most closely related to the vastus lateralis. The name of this muscular head should be "the accessory head of the vastus lateralis" rather than "the tensor of the vastus intermedius."

Is revision total hip arthroplasty through the direct anterior approach feasible?

BACKGROUND

To date, only limited literature exists regarding revision of total hip arthroplasty (THA) through the direct anterior approach (DAA). However, as the popularity of the DAA for primary surgery is increasing, surgeons will be confronted with the challenge of performing revision surgery through the DAA. The aim of this study was to review the potential of the DAA in the revision setting and to report the clinical results, radiologic outcomes and complication rates of 63 patients undergoing revision THA through the DAA.

METHODS

From 01/2009 to 08/2017, 63 patients underwent revision THA through the DAA. Depending on the performed procedure, patients were separated into 4 groups: liner and head exchange (21 patients), revision of the acetabular cup (26 patients), revision of the femoral stem (13 patients) or revision of both components (3 patients). Postoperative complications as well as the clinical and radiological outcome were assessed retrospectively.

RESULTS

At a mean follow-up of 18 months, the overall complication and re-operation rates were 14.3% and 12.7%, respectively. Specifically, the complication and re-operation rates were 14.2% and 9.5% after liner and head exchange, 15.4% after revision of the acetabular cup, 15.3% after revision of the femoral stem and 0% after revision of both components. The mean postoperative HHS at 1 year postoperatively was 91 (range 74-100).

CONCLUSION

The DAA offers appropriate exposure for exchange of mobile liners and acetabular cup revision. In selected cases with appropriate stem design, femoral stem revision through the DAA is feasible. However, surgeons should be aware of the technical difficulties related to femoral revision and be prepared to extend the approach distally or perform a trochanteric osteotomy.

Triceps, quadriceps or pentaceps femoris? Need for proper muscle definition

INTRODUCTION

Over the last years, the definition of quadriceps femoris (QF) has evolved somewhat and some authors now define a fifth head: the tensor of vastus intermedius (TVI). Descriptions of the different components of QF in textbooks and recent findings remain confusing. Therefore, the aim of this study is to obtain more information on this possible fifth head.

MATERIALS AND METHODS

Twenty lower limbs of 10 embalmed cadavers, six females and four males, were investigated by macro-dissection. The dissection and separation of the different heads were performed with the fingers and a distinction between the different parts of the quadriceps was noted only if it was possible to separate the heads without scalpel to avoid artificial separation of muscle parts.

RESULTS

In 9 lower limbs we found a QF as classically described in textbook. TVI was found in only 7 limbs and in 4 cases we were not able to differentiate VI and VM or VI and VL (triceps femoris as described by Testut). These results, and the diversity of descriptions found in the literature have led us to review the definition of an isolated muscle.

CONCLUSION

In this study, the presence of TVI was not demonstrated in all limbs unlike previously published studies on the subject. Harmonisation of dissection techniques, but also a clear definition of a muscle is required in order to be able to compare studies and draw clear conclusions.

The Relative Location of the Major Femoral Nerve Motor Branches in the Thigh

In peripheral nerve surgery, repair of the femoral nerve (FN) requires identification of normal nerve elements both proximal and distal to the level of the injury. We identified FN branches to the sartorius (SRT) and quadriceps muscles in 16 embalmed specimens and calculated the length of each branch to its point of entry into its respective muscle. The SRT and rectus femoris (RF) muscles were mobilized but not transected to mimic the surgical approach. Ratios of the length of each motor branch as a unit of the total length of the thigh, defined as the FN at the inguinal ligament to the superior margin of the patella were also calculated. The proximal branch to RF spanned a ratio of .19 ± .11 (mean ± standard deviation) from the FN at the inguinal ligament to its endpoint. The ratio of the distal branch to the RF was .29 ± .08. The ratio of the proximal SRT branch was .20 ± .05. The distal branch to SRT was located at a ratio of .43 ± .11. The proximal branch to vastus lateralis (VL) was .26 ± .08. The distal branch to VL was .39 ± .07. The ratio of the motor branch to vastus intermedius (VI) was .30 ± .05. Lastly, the branch to vastus medialis (VM) was .55 ± .06. The motor branch to SRT frequently emerged as a bifurcation of itself and saphenous nerve within the adductor canal. Knowledge of the relative location of the motor branches of the FN in the thigh can be helpful to surgeons during the nerve exploration and repair.

Distal Extension of the Anterior Approach to the Hip Using the Femoral Interbundle Technique: Surgical Technique and Case Series

BACKGROUND

The direct anterior approach (DAA) is becoming more popular as the standard surgical approach for primary total hip arthroplasty. However, it has been associated with an increased incidence of intraoperative femoral fractures in particular during the learning curve. Distal extension of the approach may be needed in case of intraoperative complications. The aim of the present study is to describe the distal extension of the DAA using the femoral interbundle technique.

METHODS

A stepwise approach based on a cadaveric study to extend the DAA distally is presented. The interval between the neurovascular bundles running to the vastus lateralis is used to gain access to the femur. Clinical and electromyography results of 5 patients undergoing a revision of the femoral component through an extended anterior approach are reported.

RESULTS

In 2 cases, the proximal bundle was exposed whereas in 3 cases the interval between the proximal and distal bundle was developed and cerclage wires were applied around the isthmus of the femur. All fractures had healed at 6 months of follow-up. Four cases had a normal electromyography, and 1 case demonstrated a neuropraxia of a branch to the vastus lateralis. All cases had a 5/5 extension power of the quadriceps muscle clinically.

CONCLUSION

The interbundle technique is an alternative way to gain additional exposure of the femur during the DAA and is based on precise knowledge of the periarticular neurovascular structures. This approach can be helpful to safely deal with intraoperative complications such as fractures requiring proximal femoral cerclage wiring during the anterior approach.

Distal Extension of the Direct Anterior Approach to the Hip: A Cadaveric Feasibility Study

BACKGROUND

The direct anterior approach (DAA) is becoming more popular as the standard surgical approach for primary total hip arthroplasty. However, femoral complications of up to 2.8% have been reported. Therefore, it is important for surgeons to understand the periarticular neurovascular anatomy in order to safely deal with intraoperative complications.

METHODS

Anatomic dissections were performed on 20 cadaveric hips. The neurovascular structures anterior to the femur and distal to the intertrochanteric line were dissected and its position was described in relation to anatomic landmarks easily identified through the DAA: anterior superior iliac spine (ASIS), the insertion of the gluteus minimus (GM), and the lesser trochanter (LT).

RESULTS

Two clearly distinguishable neurovascular bundles running to the vastus lateralis were seen in 17 of 20 specimens. The average distances to the landmarks were as follows: ASIS-1st bundle = 12.3 cm (range, 9.7-14.5); GM-1st bundle = 3.2 cm (range, 2.2-4); LT-1st bundle = 1.6 cm (range, 0.7-2.8); 1st bundle-2nd bundle = 3.3 cm (range, 1.8-6.1).

CONCLUSION

A consistent pattern of 2 clearly distinguishable neurovascular bundles was seen in 85% of the specimens. Knowledge of the position of these neurovascular bundles in relation to the anatomic landmarks makes distal femoral extension of the DAA feasible. Further clinical studies are needed to confirm the safety of the extensile anterior approach.

FDG-PET detects nonuniform muscle activity in the lower body during human gait

INTRODUCTION

Nonuniform muscle activity has been partially explained by anatomically defined neuromuscular compartments. The purpose of this study was to investigate the uniformity of skeletal muscle activity during walking.

METHODS

Eight participants walked at a self-selected speed, and muscle activity was quantified using [¹⁸ F]-fluorodeoxyglucose positron emission tomography imaging. Seventeen muscles were divided into 10 equal length sections, and within muscle activity was compared.

RESULTS

Nonuniform activity was detected in 12 of 17 muscles (ƒ > 4.074; P < 0.046), which included both uni- and multi-articular muscles. Greater proximal activity was detected in 6 muscles (P < 0.049), and greater distal versus medial activity was found in the iliopsoas (P < 0.042).

CONCLUSIONS

Nonuniform muscle activity is likely related to recruitment of motor units located within separate neuromuscular compartments. These findings indicate that neuromuscular compartments are recruited selectively to allow for efficient energy transfer, and these patterns may be task-dependent. Muscle Nerve 54: 959-966, 2016.

A newly discovered muscle: The tensor of the vastus intermedius

The quadriceps femoris is traditionally described as a muscle group composed of the rectus femoris and the three vasti. However, clinical experience and investigations of anatomical specimens are not consistent with the textbook description. We have found a second tensor-like muscle between the vastus lateralis (VL) and the vastus intermedius (VI), hereafter named the tensor VI (TVI). The aim of this study was to clarify whether this intervening muscle was a variation of the VL or the VI, or a separate head of the extensor apparatus. Twenty-six cadaveric lower limbs were investigated. The architecture of the quadriceps femoris was examined with special attention to innervation and vascularization patterns. All muscle components were traced from origin to insertion and their affiliations were determined. A TVI was found in all dissections. It was supplied by independent muscular and vascular branches of the femoral nerve and lateral circumflex femoral artery. Further distally, the TVI combined with an aponeurosis merging separately into the quadriceps tendon and inserting on the medial aspect of the patella. Four morphological types of TVI were distinguished: Independent-type (11/26), VI-type (6/26), VL-type (5/26), and Common-type (4/26). This study demonstrated that the quadriceps femoris is architecturally different from previous descriptions: there is an additional muscle belly between the VI and VL, which cannot be clearly assigned to the former or the latter. Distal exposure shows that this muscle belly becomes its own aponeurosis, which continues distally as part of the quadriceps tendon.

Limitations of the Vastus Lateralis Muscle as a Substitute for Lost Abductor Muscle Function: An Anatomical Study

Abductor insufficiency after hip arthroplasty resulting from an impaired gluteus medius and minimus remains an unsolved problem in orthopaedic surgery. The vastus lateralis (VL) was described as a functional substitute for abductor insufficiency in 2004. We carried out a macrodissection of twelve cadaveric hemipelvises to investigate the innervation of the VL and adjacent muscles to assess the extent the VL can be safely transferred. Results showed that direct muscle branches to proximal portions of the VL are too short to allow a significant shift; the shift may be as small as 13 mm. Nerves that supply the VL also extend to the vastus intermedius. This innervation pattern makes it impossible to shift the VL significantly without damaging branches to both.

Distal extension of the direct anterior approach to the hip poses risk to neurovascular structures: an anatomical study

BACKGROUND

The anterior approach to the hip gained popularity for total hip arthroplasty in recent years. Distal extension of the anterior approach, sometimes needed intraoperatively, potentially endangers neurovascular structures to the quadriceps. The aim of this study was to determine the anatomical structures placed at risk by distal extension of the anterior approach to the hip.

METHODS

Seventeen cadaveric hemipelves from twelve human specimens were dissected. The femoral nerve and its branches and the vessels arising from the lateral femoral circumflex artery were assessed in relation to the distal extension of the anterior approach. The damage caused by the introduction of a cerclage cable passer was also investigated.

RESULTS

The area immediately distal to the intertrochanteric line is a common entry point for several nerve branches and is a useful distal landmark for surgeons to use to protect important neurovascular structures. The distal extension of the anterior approach compromises the nerve supply to the anterolateral portions of the quadriceps. Introduction of a cerclage cable passer through the anterior access also jeopardizes nerve branches to the vastus lateralis, lateral parts of the vastus intermedius, and branches of the lateral femoral circumflex artery.

CONCLUSIONS

Distal extension of the direct anterior approach to the hip is challenging to accomplish without neurovascular injury to anterolateral parts of the quadriceps muscle group. In addition, important neurovascular structures are endangered with the introduction of a cable passer through the anterior approach.

CLINICAL RELEVANCE

Distal extension of the direct anterior approach to the hip beyond the intertrochanteric line may compromise neurovascular structures supplying the quadriceps muscle.

Radiological assessment of the safe zone for medial minimally invasive plate osteosynthesis in the distal femur with computed tomography angiography

INTRODUCTION

Surgical treatment options for distal femur fractures include intramedullary nailing or plating using a lateral or lateral parapatellar approach. However, medial plating is required for additional stability in some fractures such as severely comminuted fractures and periprosthetic fractures, and in those for which use of a lateral plate or nail is not appropriate. This study aimed to explore the safe zone for medial minimally invasive plate osteosynthesis of the distal femur with computed tomography angiography.

MATERIAL AND METHODS

In a series of 30 patients, the region of interest between the lesser trochanter (LT) to the adductor tubercle (AT) was divided into six levels (I to VI), and the distance from the femur to the femoral artery (FA) was measured. At each level, the medial half of the femur was divided into eight sections that were assigned ‘A to H’ from anteromedial to posteromedial, and the position of the FA and the deep femoral artery (DFA) was recorded.

RESULTS

The average length from the LT to AT was 295.0 mm. The average distance to FA was 38.0 mm, 29.9 mm, 26.9 mm, 27.0 mm, 21.8 mm, and 12.2 mm from level I to VI, respectively. The FA was positioned posteromedially below level IV and positioned at C–H below level II, which was out of the anterior aspect of the femur. The DFA was in the same location as the FA between levels II and III.

CONCLUSION

The anteromedial aspect of the distal half of the femur is the safe zone, and a long plate can be positioned safely in this zone at the anterior aspect up to the level of 8 cm below the LT.

Clinical anatomy of the quadriceps femoris and extensor apparatus of the knee

Most descriptions of the extensor mechanism of the knee do not take into account its complexity and variability. The quadriceps femoris insertion into the patella is said to be through a common tendon with a three-layered arrangement: rectus femoris (RF) most superficially, vastus medialis (VM) and lateralis (VL) in the intermediate layer, and vastus intermedius (VI) most deeply. We dissected 20 limbs from 17 cadavers to provide a more detailed description of the anterior components of the knee: the tendon, the patellar retinacula, and the patellofemoral ligaments. Only three of the 20 specimens exhibited the typically described quadriceps pattern. The remainder had bilaminar and even more complex trilaminar and tetralaminar fiber arrangements. We found an oblique head of the vastus lateralis (VLO), separated from the longitudinal head by a layer of fat or fascia, in 60% of the specimens. However, we found no distinct oblique head of the vastus medialis (VMO) in any specimen. The medial patellofemoral ligament (MPFL) was more common than the lateral (LPFL), supporting its suggested role as the principal passive medial stabilizer of the patella. Because the quadriceps muscle group plays a direct role in patellofemoral joint function, investigation into the clinical applications of its highly variable anatomy may be worthwhile with respect to joint dysfunction and failures of TKAs.

Gross morphology of the vastus lateralis muscle: An anatomical review

To understand the role of the vastus lateralis (VL) muscle in the pathogenesis of common knee disorders such as patellofemoral joint syndrome, knowledge of its anatomical structure is essential. The aim of this study was to review currently available information on the gross morphology of VL. A structured literature review was undertaken and 36 references, comprising 22 scientific papers and 14 anatomical textbooks, were included. Results of this literature review show that most of the included studies exhibited methodological limitations, and focused on different parameters of the VL muscle. Hence, reproducibility of these studies and comparison of results was difficult. This review also demonstrates a dearth of information on the muscle architecture, compartmentalization, nerve supply and fusion of VL, and that there has been no investigation of the muscle as a whole unit. Further research is required of the architecture and innervation of the VL muscle to better understand its function.