Neurovascular Anatomy of the Rectus Femoris Muscle Related to Functioning Muscle Transfer:

Effect of tasks on intramuscular regional differences in rectus femoris elasticity during isometric contraction: An ultrasound shear wave elastography study

PURPOSE

This study aimed to investigate intramuscular regional differences and task specificity of rectus femoris (RF) elasticity during isometric contraction.

METHODS

Sixteen healthy males (aged 24.3 ± 4.1 years) participated in this study. The tasks included isometric hip flexion (HF) and knee extension (KE). The contractions were maintained at 0%, 30%, and 60% of their respective maximum voluntary isometric contraction (MVC) forces for 5 s each at 50˚ hip flexion and 90˚ knee flexion. RF elasticity was measured in two regions, proximal (33%) and distal (67%). The shear modulus (kPa), measured by shear wave elastography, was used to determine RF elasticity.

RESULTS

A significant interaction effect was observed (intensity × region × task) (P = 0.01). Regarding regional differences during contraction, the proximal region exhibited a greater shear modulus than the distal region at 60% MVC in the hip flexion task (P = 0.001). Conversely, no regional differences were observed at either 30% MVC (P = 0.625) or 60% MVC (P = 0.568) in the knee extension task.

DISCUSSION

Muscle shear modulus during contraction reflects active force, suggesting that mechanical stress can be applied primarily to the proximal region of the RF during the HF task.

Distally Based Anterolateral Thigh Flap Algorithm for Unexpected Situations during Soft-Tissue Defect Reconstruction around the Knee

BACKGROUND

The distally based (d) anterolateral thigh (ALT) flap is an effective option for soft-tissue reconstruction around the knee; however, unexpected situations may occur intraoperatively, impeding flap harvest. The authors proposed an algorithm for surgical conversion for unexpected situations encountered intraoperatively.

METHODS

Between 2010 and 2021, 61 dALT flap harvests were attempted for soft-tissue defect reconstruction around the knee; 25 patients underwent surgical conversion for anomalies, including lack of a suitable perforator, hypoplasia of the descending branch, and compromised reverse flow from the descending branch. After excluding improper cases, 35 flaps were harvested as planned (group A) and 21 surgical conversion cases (group B) were finally enrolled for analysis. An algorithm was developed based on the cases in group B. Outcomes, including complication and flap loss rates, were compared between groups to verify the algorithm's rationality.

RESULTS

In group B, the dALT flap was converted to a distally based anteromedial thigh flap ( n = 8), bipedicled dALT flap ( n = 4), distally based rectus femoris muscle flap ( n = 3), free ALT flap ( n = 2), or other locoregional flap that required additional incision ( n = 4). No differences in outcomes were observed between the two groups.

CONCLUSION

The proposed contingency planning algorithm for dALT flap surgery proved rational, as surgical conversion could be made by means of the same incision in most cases, and outcomes generated by the algorithm were acceptable.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Repair of complex ovine segmental mandibulectomy utilizing customized tissue engineered bony flaps

Craniofacial defects require a treatment approach that provides both robust tissues to withstand the forces of mastication and high geometric fidelity that allows restoration of facial architecture. When the surrounding soft tissue is compromised either through lack of quantity (insufficient soft tissue to enclose a graft) or quality (insufficient vascularity or inducible cells), a vascularized construct is needed for reconstruction. Tissue engineering using customized 3D printed bioreactors enables the generation of mechanically robust, vascularized bony tissues of the desired geometry. While this approach has been shown to be effective when utilized for reconstruction of non-load bearing ovine angular defects and partial segmental defects, the two-stage approach to mandibular reconstruction requires testing in a large, load-bearing defect. In this study, 5 sheep underwent bioreactor implantation and the creation of a load-bearing mandibular defect. Two bioreactor geometries were tested: a larger complex bioreactor with a central groove, and a smaller rectangular bioreactor that were filled with a mix of xenograft and autograft (initial bone volume/total volume BV/TV of 31.8 ± 1.6%). At transfer, the tissues generated within large and small bioreactors were composed of a mix of lamellar and woven bone and had BV/TV of 55.3 ± 2.6% and 59.2 ± 6.3%, respectively. After transfer of the large bioreactors to the mandibular defect, the bioreactor tissues continued to remodel, reaching a final BV/TV of 64.5 ± 6.2%. Despite recalcitrant infections, viable osteoblasts were seen within the transferred tissues to the mandibular site at the end of the study, suggesting that a vascularized customized bony flap is a potentially effective reconstructive strategy when combined with an optimal stabilization strategy and local antibiotic delivery prior to development of a deep-seated infection.

Effects of growth on muscle architecture of knee extensors

This study aimed to investigate the effects of growth on the muscle architecture of knee extensors. The present study included 123 male children and adolescents. The muscle thicknesses of the rectus femoris (RF) and vastus intermedius (VI), and pennation angles and fascicle lengths of RF were measured in three regions using ultrasonography technique at rest. The relative muscle thickness was calculated by dividing the absolute muscle thickness by body mass1/3 . The years from age at peak height velocity were estimated for each participant, and used as a maturity index. The maturity index was significantly correlated with the relative muscle thicknesses of RF and VI in all regions. The slope of the relationship between the maturity index and the relative muscle thickness did not differ significantly between muscles within the same region or between regions within the individual muscles. The fascicle length and pennation angle of RF were significantly correlated with the absolute muscle thickness in all regions. In the proximal RF region, the coefficient of correlation between the muscle thickness and fascicle length was significantly greater than that between the muscle thickness and pennation angle. The present results showed that growth changes in muscle thickness were uniform between and within RF and VI. Our findings suggest that growth changes in the muscle thickness of RF depend on the increases in both pennation angle and fascicle length, but their contributions to the growth of muscle thickness differ among muscle regions.

Normalisation of a biarticular muscle EMG signal using a submaximal voluntary contraction: Choice of the standardised isometric task for the rectus femoris, a pilot study

BACKGROUND

Electromyography (EMG) signal amplitude is often altered by factors related to the participants and the measurement system. To overcome this issue, a normalisation of the EMG signal amplitude can be performed. Recently, it has been demonstrated that a submaximal voluntary contraction (subMVC) normalisation approach, inspired by grade 3 of manual muscle testing, could produce reliable results. However, rectus femoris (RF) normalisation resulted in low reliability. While the normalisation task chosen for this biarticular muscle was to maintain a knee extension against gravity (ISO-K), a hip flexion isometric task (ISO-H) could also be applied.

RESEARCH QUESTION

This pilot study aimed to assess the impact of the normalisation task on the RF EMG signal quality and related intra-rater within-day reliability during ISO-K and ISO-H, and intra-rater between-day reliability of the EMG signal amplitude during gait.

METHODS

Twenty-four asymptomatic participants were asked to perform ISO-K and ISO-H tasks with both legs and then to walk at self-spontaneous speed, in two identical sessions one week apart. A wireless EMG system was used to record the EMG signal of bilateral RF during each task.

RESULTS

Signal-to-noise ratio during ISO-K and ISO-H was ≥ 15 dB in respectively 51% and 98% of all task repetitions. Intra-rater within-day reliability was acceptable using ISO-K (ICC = 0.71 (0.57; 0.83)) with high %SEM of 35%, and excellent using ISO-H (ICC = 0.94 (0.90; 0.96)) with high %SEM of 34%. Intra-rater between-day reliability during gait was acceptable using ISO-K (ICC = 0.74 (0.61; 0.81)) with a high %SEM of 49%, and excellent using ISO-H (ICC = 0.87 (0.76; 0.93)) with a high %SEM of 38%.

SIGNIFICANCE

The reliability (ICC) of RF EMG signal normalisation was higher using ISO-H than using ISO-K. However, even if signal-to-noise ratio was notably improved using ISO-H, %SEM remains high whatever the normalisation task used. Some additional improvements might thus still be needed to obtain a normalisation protocol allowing more reproducible measurements.

Central Tendon Injury Impairs Regional Neuromuscular Activation of the Rectus Femoris Muscle

We aimed to uncover which rectus femoris strain injury types affect regional activation within the rectus femoris. The rectus femoris has a region-specific functional role; the proximal region of the rectus femoris contributes more than the middle and distal regions during hip flexion. Although a history of strain injury modifies the region-specific functional role within the rectus femoris, it was not obvious which rectus femoris strain injury types affect regional activation within it. We studied 12 soccer players with a history of rectus femoris strain injury. Injury data were obtained from a questionnaire survey and magnetic resonance imaging. To confirm the region-specific functional role of the rectus femoris, surface multichannel electromyographic signals were recorded. Accordingly, eight legs had a history of central tendon injury, four had a history of myofascial junction injury, and four had a healed strain injury. When the injury was limited to the central tendon, the region-specific functional role disappeared. The region-specific functional role was confirmed when the injury was outside the central part. The neuromuscular function was also inhibited when the longitudinal range of the injured region was long. Our findings suggest that a central tendon injury with a long injury length impairs regional neuromuscular activation of the rectus femoris muscle.

Novel Insights Into Biarticular Muscle Actions Gained From High-Density Electromyogram

Biarticular muscles have traditionally been considered to exhibit homogeneous neuromuscular activation. The regional activation of biarticular muscles, as revealed from high-density surface electromyograms, seems however to discredit this notion. We thus hypothesize the regional activation of biarticular muscles may contribute to different actions about the joints they span. We then discuss the mechanistic basis and methodological implications underpinning our hypothesis.

The Anatomic Feasibility of a Functional Chimeric Flap in Complex Abdominal Wall Reconstruction

BACKGROUND

Dynamic and functional abdominal wall reconstruction (FAWR) remains a complex challenge. The ideal flap should have a minimal donor-site morbidity and cover a large surface area with motor and sensory capabilities. The goal was to investigate the feasibility of using a free chimeric flap with anterolateral thigh (ALT) and rectus femoris (RF) components pedicled only on the motor nerve branch.

METHODS

Ten fresh cadavers were dissected with a designed chimeric thigh flap including ALT and RF flaps. Anterolateral thigh was designed and raised with the lateral femoral cutaneous nerve integrated, and the descending branch of the lateral circumflex femoral artery was preserved. Rectus femoris was elevated and the common pedicle was dissected up to the femoral origin. Accompanying motor nerve branches were carefully dissected to their femoral origin.

RESULTS

Twenty RF flaps were dissected and 9 were harvested as a true chimeric flap with ALT. The mean number of neurovascular bundles associated with RF flap was 2.11 ± 0.47, and the mean primary motor nerve average length was 9.40 ± 2.42 cm. The common vascular bundle in all 9 chimeric flaps was ligated, and the flap was rotated toward the abdomen pedicled only by primary motor nerve of the RF muscle. Nerve length was adequate for reach up to xiphoid area in all 20 flaps.

CONCLUSIONS

This study demonstrates the feasibility of the chimeric ALT/RF muscle free flap pedicled only by the motor nerve branch, with adequate flap rotation. Even with the limitations in a live patient, this flap would be an excellent option for FAWR in the right patient.

Revisiting the Blood Supply of the Rectus Femoris: A Case Report and Computed Tomography Angiography Study

BACKGROUND

Rectus femoris necrosis is a rare but severe complication after anterolateral thigh flap (ALTF) harvesting. It has been previously reported that the blood supply of the rectus femoris (RF) often arises from the same source artery as the ALTF; however, precise descriptions of the relationship remain limited. This article revisits the blood supply of the RF based on computed tomography angiography (CTA) and analyzes the possible influence of the blood supply on the RF during ALTF harvesting.

METHODS

Between December 2017 and June 2018, CTA images of the bilateral lower extremities of 25 patients were studied. The RF length, number, and diameter of branches at the entry point into muscle, location, and overall branch vessel origins were recorded.

RESULTS

The average ± SD RF length was 384.73 ± 19.28 mm. There were 170 branches (mean ± SD, 3.4 ± 0.96 branches per thigh), mainly arising from the lateral circumflex femoral artery. The average ± SD diameter was 1.90 ± 0.51 mm. The first branch was located at 1/5 of the proximal site of the RF, and 91% of all branches were located above the midpoint. The RF vascularity can be classified into 2 types: type 1 (36% of sides) has branches that arise from a single artery (descending lateral circumflex femoral artery or femoral artery), whereas type 2 (64% of sides) has branches at the 1/5 proximal and 4/5 distal parts, which arise from different arteries.

CONCLUSIONS

Preoperative CTA can provide anatomic information about the RF's nutrient vessel(s) and helps to optimize ALTF design.

Anatomical variants of the rectus femoris motor innervation

Adult periacetabular osteotomy (PAO) was originally performed through the classic Smith-Petersen approach for optimal operative visibility and acetabular fragment correction. Evolution towards an abductor-sparing technique significantly lowered the post-operative morbidity. The rectus-sparing approach represents a step further, but the innervation of the rectus femoris is theoretically more at risk. Although the topographic anatomy of the femoral nerve has been well described, it was never studied with specificity to surgical landmarks. The femoral nerve’s spatial relation with the anterior-inferior iliac spine (AIIS) and the amount of possible dissection in the rectus femoris and iliopsoas interval is uncertain. Seven formalin-preserved human cadaveric specimens without history of inguinal injury or surgery were dissected using the distal limb of an iliofemoral approach. The level of entry of motor innervation was measured and number of branches to the rectus femoris was noted. The average longitudinal distance from the AIIS to the first motor nerve to the rectus femoris was 8.6 ± 1.4 cm. The number of branches varied between 1 and 4 with the most common innervation pattern being composed of two segments. Dissection medial to the rectus femoris should not be carried out further than 7 cm distal to the AIIS and stretching of that interval during surgical exposure should be done cautiously. The clinical efficiency of the rectus-sparing approach should be studied further in order to confirm its advantage over the classic direct anterior approach. The study provides a better understanding of the localization and the anatomical variations of the structures encountered at the level of and below the AIIS. It also assesses the relative risk of denervation of the rectus femoris during PAO through the rectus-sparing approach. The authors recommend that the dissection medial to the rectus femoris should be carried out no further than 7 cm distal to the AIIS and stretching of that interval during surgical exposure should be done cautiously.

Effects of Ankle Joint Motion on Pelvis-Hip Biomechanics and Muscle Activity Patterns of Healthy Individuals in Knee Immobilization Gait

The purpose of the study was to investigate the pelvis-hip biomechanics and trunk and lower limb muscle activity patterns between healthy people walking in two gaits and evaluate the effects of ankle joint motion on these two gaits. The two gaits included walking with combined knee and ankle immobilization and with individual knee immobilization. Ten healthy participants were recruited and asked to walk along a 10 m walk away at their comfortable speeds in the two gaits. Kinematic data, ground reaction force, and electromyography waveforms of trunk and lower limb muscles on the right side were collected synchronously. Compared to individual knee immobilization gait, people walking in the combined knee and ankle immobilization gait increased the range and average angle of the anterior pelvic tilt during the first double support and the single support phase, respectively. The combined knee and ankle immobilization gait also increased the range of hip abduction during the second double support phase. These kinematic alternations caused changes in trunk and lower limb muscle activity patterns. The ankle immobilization increased the range of gluteus maximus activation in the first double support phase, the range of rectus abdominis activation, the average amplitude of rectus femoris activation in the single support phase, and the range of rectus femoris activation in swing phase and decreased the range of and tibialis anterior activation in the first double support phase. The ankle immobilization also increased the average values of proximodistal component in AKI gait during the single support phase. This study revealed significant differences in pelvis-hip biomechanics and trunk and lower limb muscle activity patterns between the two gaits.

The Effect of a Previous Strain Injury on Regional Neuromuscular Activation Within the Rectus Femoris

The rectus femoris (RF) has a region-specific functional role; that is, the proximal region of the RF contributes more than the middle and distal regions during hip flexion. This study aimed to investigate whether RF strain injury affected the region-specific functional role of the muscle. We studied seven soccer players with a history of unilateral RF strain injury. Injury data were obtained from a questionnaire survey and magnetic resonance imaging (MRI). Multichannel surface electromyographic (SEMG) signals were recorded from the proximal to distal regions of the RF with 24 electrodes during isometric knee extension and hip flexion. The SEMG signals of each channel during hip flexion were normalised by those during knee extension for the injured and non-injured RF (HF/KE), and compared among the proximal, middle, and distal regions. Six RF strain injuries showed a low signal area in MRI. There was no significant difference in muscle strength between the injured and non-injured RF. While the HF/KE in the proximal region was significantly higher than those in the middle and distal regions in the non-injured RF, a difference in the HF/KE was seen only between the proximal and distal regions of the injured RF. Furthermore, the HF/KE of the most proximal channel in the injured RF was significantly lower than that in the non-injured RF. However, there was no significant difference between injured and non-injured areas in the HF/KE. Our findings suggest that the region-specific functional role of the RF muscle is partly affected by RF strain injury.

A cadaveric analysis of the blood supply to rectus Femoris

BACKGROUND

Rectus femoris is a versatile muscle frequently used as a pedicled flap in reconstructive surgery. The anatomy and blood supply of rectus femoris needs to be clearly understood in order to safely preserve its reconstructive and functional capabilities. Classical anatomical description states that the proximal pedicle insertion into rectus femoris is 10- 15 cm from the anterior superior iliac spine (ASIS). The aim of this study was to dissect and identify the pedicular blood supply to rectus femoris and further map its morphology relative to the ASIS.

METHODS

A dissection of 20 embalmed thighs from 10 cadavers was conducted. The distance of arterial insertions into rectus femoris from the ASIS were recorded. The cohort was 60% male of median age 79 with statistical significance defined as p < 0.05.

RESULTS

5%, 50%, and 45% of muscles demonstrated 1, 2, and 3 pedicles respectively. The mean distance from the ASIS to insertion of these pedicles was: proximal 13 cm (SD 2.6), middle 15 cm (SD 2.8), and distal 18 cm (SD 4.1). When grouped by number of pedicles, there was no difference in the mean height of proximal insertion. However, there was significant difference in mean intramuscular proximal-distal difference. These results were replicated when data were expressed as % of cadaver height.

CONCLUSIONS

This study confirms the pedicular supply of rectus femoris but in contrast to classical literature demonstrates a greater range of pedicle insertions heights. We believe these observations should be considered when safely harvesting the pedicled rectus femoris flap.

Additional insight into biarticular muscle function: The influence of hip flexor fatigue on rectus femoris activity at the knee

We evaluated the compensatory adaptations in muscle regionalization and synergist activity after fatiguing a biarticular muscle at one joint with different muscle lengths. Eleven men (mean ± SD age = 23 ± 3 years) performed 50 maximal concentric isokinetic contractions of the dominant hip flexors on two occasions. For one trial, the knee joint was fully extended. For the other, the knee joint was fixed at 70°. Maximal voluntary contractions of the knee extensors were performed immediately before and after the hip flexion fatigue protocol while bipolar surface electromyographic signals were detected from the vastus lateralis and at five points along the length of the rectus femoris. Regardless of knee joint angle during the hip flexion fatigue protocol, knee extension peak torque was unchanged following hip flexion fatigue. Electromyographic amplitude for the vastus lateralis (p = .047, η² = .338) and rectus femoris (p < .001, η² = .667) showed main effects for time, indicating higher and lower post-fatigue values, respectively. There was no evidence of region-specific rectus femoris adaptations during extension at the knee following fatigue of the hip flexors. These data suggest that synergistic adaptations were involved in maintaining knee extension peak torque following hip flexion fatigue.

Relationship between regional neuromuscular regulation within human rectus femoris muscle and lower extremity kinematics during gait in elderly men

Biomechanical and neurophysiological mechanisms of age-related gait dysfunction have not been fully understood. We aimed to investigate the relationship between region-specific electromyography (EMG) response of the rectus femoris (RF) muscle and lower extremity kinematics during swing phase of gait for the elderly. For thirteen elderly men (age: mean 71.3 years, standard deviation 5.7 years), multi-channel surface EMG from the proximal to distal regions of the RF muscle and lower extremity kinematics were measured during normal gait on a treadmill. At minimum foot clearance during swing phase, relationship between central locus activation (CLA), which is indicator of spatial distribution of surface EMG along the RF muscle and lower joint kinematics were calculated. No significant correlations were found between CLA and any joint angle (p > 0.05). The results of our study suggested that regional neuromuscular activation of the RF muscle is not associated to lower extremity joint movements and toe clearance strategy during gait in the elderly.

Region-specific modulation of tendon reflex along human rectus femoris muscle

INTRODUCTION

We investigated regional differences in amplitude modulation of the spinal reflex along the human rectus femoris (RF) muscle to test the hypothesis that this muscle is regionally regulated at the spinal cord or a higher level.

METHODS

Surface electromyography was conducted at six different sites along the RF muscle during the conditioned patellar tendon reflex in eight healthy young men.

RESULTS

A significant difference in the reflex amplitude among the channels was observed during 20% of the maximal voluntary contraction (MVC) and there was a significant difference in normalized reflex amplitude between 10 and 20% of the MVC at most proximal channel (p < 0.05), but not at the other channels (p > 0.05), during knee flexion of the ipsilateral leg.

DISCUSSION

From the results in the present study, we infer that the amplitude modulation of the tendon reflex within the RF muscle is regionally regulated, and that this regulation is dependent on the performed tasks.

Longitudinal sequencing in intramuscular coordination: A new hypothesis of dynamic functions in the human rectus femoris muscle

The punctum fixum-punctum mobile model has been introduced in previous publications. It describes general principles of intersegmental neuromuscular succession patterns to most efficiently generate specific movement intentions. The general hypothesis of this study is that these principles—if they really do indicate a fundamental basis for efficient movement generation—should also be found in intramuscular coordination and should be indicated by “longitudinal sequencing” between fibers according to the principles of the punctum fixum-punctum mobile model. Based on this general hypothesis an operationalized model was developed for the rectus femoris muscle (RF), to exemplarily scrutinize this hypothesis for the RF. Electromyography was performed for 14 healthy male participants by using two intramuscular fine wire electrodes in the RF (placed proximal and distal), three surface electrodes over the RF (placed proximal, middle, and distal), and two surface electrodes over the antagonists (m. biceps femoris and m. semitendinosus). Three movement tasks were measured: kicking movements; deceleration after sprints; and passively induced backward accelerations of the leg. The results suggest that proximal fibers can be activated independently from distal fibers within the RF. Further, it was shown that the hypothesized function of “intramuscular longitudinal sequencing” does exist during dynamic movements. According to the punctum fixum-punctum mobile model, the activation succession between fibers changes direction (from proximal to distal or inversely) depending on the intentional context. Thus, the results seem to support the general hypothesis for the RF and could be principally in line with the operationalized “inter-fiber to tendon interaction model”.

Effect of aging on region-specific functional role and muscle geometry along human rectus femoris muscle

INTRODUCTION

We compared the region-specific neuromuscular activation and muscle morphology along the rectus femoris (RF) muscle between young and elderly.

METHODS

Ratios of surface electromyography amplitude between hip flexion and knee extension (HF/KE) were compared among regions along the muscle for 9 young and 9 elderly men. Muscle thickness was also compared among the regions.

RESULTS

HF/KE in the proximal region was significantly greater than in the middle and distal regions for both the young and elderly (P < 0.05). However, a significant difference in HF/KE between the middle and distal regions was found in the young (P < 0.05), but not in the elderly (P > 0.05). A difference in the region-specific muscle thickness was observed between the young and elderly.

CONCLUSION

These findings suggest that functional role and muscle morphology are regionally affected by aging along the RF muscle. Muscle Nerve 56: 982-986, 2017.

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.

Inter- and intramuscular differences in training-induced hypertrophy of the quadriceps femoris: association with muscle activation during the first training session

The purpose of this study was to examine whether inter- and intramuscular differences in hypertrophy induced by resistance training correspond to differences in muscle activation during the first training session. Eleven young men completed 12 weeks of training intervention for knee extension. Before and after the intervention, T1-weighted magnetic resonance (MR) images were recorded to determine the volume and anatomical cross-sectional area (CSA) along the length of the individual muscles of the quadriceps femoris. The T2-weighted MR images were also acquired before and immediately after the first training session. The T2 was calculated for each pixel within the quadriceps femoris, from which the muscle activation was evaluated as %activated volume and area. The results showed that the %activated volume after the first training session was significantly higher in the vastus intermedius than the vastus medialis. However, the relative change in muscle volume after the training intervention was significantly greater in the rectus femoris than the vasti muscles (vastus lateralis, intermedius and medialis). Within the rectus femoris, both the %activated area and relative increase in CSA were significantly greater in the distal region than the proximal region. In contrast, the %activated area and relative increase in CSA of the vasti were nearly uniform along each muscle. These results suggest that the muscle activation during the first training session is associated with the intramuscular difference in hypertrophy induced by training intervention, but not with the intermuscular difference.

Non-uniform recruitment along human rectus femoris muscle during transcutaneous electrical nerve stimulation

PURPOSE

To test the hypothesis that motor units with different axonal excitability levels are localized in specific portions of the rectus femoris (RF) muscle using transcutaneous electrical nerve stimulation.

METHODS

M-waves were elicited by transcutaneous electrical nerve stimulation and detected from 24 sites along longitudinal line of the muscle. The stimulation was applied to the femoral nerve, and the current level was gradually increased.

RESULTS

The central locus activation, which is calculated from the spatial distribution of M-waves, appeared at the proximal regions at low stimulation level and then moved to the middle site of the muscle with an increase in the stimulation level. The results reveal that groups of motor units activated at different stimulation levels are located in different positions in the proximal-distal muscle direction.

CONCLUSION

Our results suggest that motor unit properties in proximal and other regions are not uniform within the RF muscle.

Medial triceps brachii free flap in reconstructive surgery: a prospective study in eight patients

INTRODUCTION

In this study, we present a prospective series of medial triceps free flaps for ankle and foot complex defects coverage and discuss its numerous advantages.

MATERIALS AND METHODS

Between January 2011 and December 2012, eight patients, two women and six men underwent medial triceps brachii (MTB) free flap procedure to cover defects localized at the ankle and foot in our department. Patient mean age was 37.3 ± 15.2 years at the time of surgery (range of 13-53 years). Mean defect size to be covered was 21.8 ± 9.9 cm(2). The bone was exposed at the level of the calcaneum in six cases, at the level of the forefoot in one case, and at the level of the lateral malleolus in one case. Special attention was accorded to intra-operative findings. Flap survival and complications on both the donor and recipient site were prospectively evaluated.

RESULTS

Mean MTB flap raising time was 51.3 ± 6.0 min. All the flaps survived and there was no partial flap necrosis. A skin graft was performed after a mean time of 11.8 ± 2.1 days post-operative. The mean follow-up was 18.1 ± 3.8 months. Complications at the donor site level included one hematoma and a case of hypertrophic scar. Complete healing of both the donor and recipient sites was achieved in all cases.

CONCLUSIONS

MTB free flap appears to be a useful option for covering small to medium defects in lower limb extremities. Due to the constant anatomy of the MTB nerve, we suggest that the flap could also be used as an innervated free flap for small or medium muscular reanimation such as sequelae of forearm and hand muscle impairment, or facial palsy.

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.

New surgical algorithm for femoral head split fractures with anatomical study

BACKGROUND

The femoral head split fracture line is usually located in the anterior-inferior portion of the head. Proper fixation is difficult using the conventional approach without tenotomy, and thus, the authors sought to devise an effective, safe, fixation approach for the most common type of head fracture.

METHODS

Anatomical dissection of 80 femoral triangles was performed. The authors evaluated the locations of femoral nerves, vessels, and branches within femoral triangles. On the basis of these observations we used a new anterior approach via the non-dangerous lateral space of the femoral triangle. This approach was applied to 12 femoral head split fractures treated from 2002 to 2009.

RESULTS

A safe area was found within the femoral triangle at the proximal 17.5-32.5 % of the full length of the rectus femoris. In Brumback type 1A and 2A cases, screws were inserted at right angles relative to the fracture plane through the space.

CONCLUSIONS

This study contributes by providing a new technique for femoral head split fractures. This anterior approach using the lateral aspect of femoral triangle provided excellent and good results for Brumback type 1A and 2A femoral head split fractures. On the basis of this study, we produced new treatment algorithm for femoral head split fracture.

Heterogeneous atrophy occurs within individual lower limb muscles during 60 days of bed rest

To better understand disuse muscle atrophy, via magnetic resonance imaging, we sequentially measured muscle cross-sectional area along the entire length of all individual muscles from the hip to ankle in nine male subjects participating in 60-day head-down tilt bed rest (2nd Berlin BedRest Study; BBR2-2). We hypothesized that individual muscles would not atrophy uniformly along their length such that different regions of an individual muscle would atrophy to different extents. This hypothesis was confirmed for the adductor magnus, vasti, lateral hamstrings, medial hamstrings, rectus femoris, medial gastrocnemius, lateral gastrocnemius, tibialis posterior, flexor hallucis longus, flexor digitorum longus, peroneals, and tibialis anterior muscles (P ≤ 0.004). In contrast, the hypothesis was not confirmed in the soleus, adductor brevis, gracilis, pectineus, and extensor digitorum longus muscles (P ≥ 0.20). The extent of atrophy only weakly correlated (r = -0.30, P < 0.001) with the location of greatest cross-sectional area. The rate of atrophy during bed rest also differed between muscles (P < 0.0001) and between some synergists. Most muscles recovered to their baseline size between 14 and 90 days after bed rest, but flexor hallucis longus, flexor digitorum longus, and lateral gastrocnemius required longer than 90 days before recovery occurred. On the basis of findings of differential atrophy between muscles and evidence in the literature, we interpret our findings of intramuscular atrophy to reflect differential disuse of functionally different muscle regions. The current work represents the first lower-limb wide survey of intramuscular differences in disuse atrophy. We conclude that intramuscular differential atrophy occurs in most, but not all, of the muscles of the lower limb during prolonged bed rest.

Task-dependent inhomogeneous muscle activities within the bi-articular human rectus femoris muscle

The motor nerve of the bi-articular rectus femoris muscle is generally split from the femoral nerve trunk into two sub-branches just before it reaches the distal and proximal regions of the muscle. In this study, we examined whether the regional difference in muscle activities exists within the human rectus femoris muscle during maximal voluntary isometric contractions of knee extension and hip flexion. Surface electromyographic signals were recorded from the distal, middle, and proximal regions. In addition, twitch responses were evoked by stimulating the femoral nerve with supramaximal intensity. The root mean square value of electromyographic amplitude during each voluntary task was normalized to the maximal compound muscle action potential amplitude (M-wave) for each region. The electromyographic amplitudes were significantly smaller during hip flexion than during knee extension task for all regions. There was no significant difference in the normalized electromyographic amplitude during knee extension among regions within the rectus femoris muscle, whereas those were significantly smaller in the distal than in the middle and proximal regions during hip flexion task. These results indicate that the bi-articular rectus femoris muscle is differentially controlled along the longitudinal direction and that in particular the distal region of the muscle cannot be fully activated during hip flexion.

An unique variation of the peroneus tertius muscle

Peroneus tertius (fibularis tertius) is a muscle unique to humans. It often appears to be a part of extensor digitorum longus, and might be described as its "fifth tendon". Although its insertion variation has been reported by many authors, variations of its origin points are not common. A variation of the peroneus tertius muscle was found during routine dissection of a 75-year-old male cadaver. The muscle originated from the extensor hallucis longus. The muscle belly of the extensor hallucis longus arose from the middle two-fourths of the medial surface of the fibula, medial to the extensor digitorum longus, and anterior surface of the interosseous membrane. It lay under the extensor digitorum longus, and lateral to the tibialis anterior muscle. The muscle belly of the extensor hallucis longus divided into medial and lateral parts 17 cm below its origin point. The lateral part, named as peroneus tertius, continued downward to reach the medial part of the dorsal surface of the base of the fifth metatarsal bone. The medial part ran also downward and divided into two tendons reaching the dorsal surface of the base of the distal phalanx of the great toe. This kind of variation may be important during foot or leg surgery.

Accessory muscle belly of peroneus tertius in the leg--a rare anatomical variation with clinical relevance--utility in reconstructions

We report here a rare muscular anomaly of the lower leg in an adult male cadaver observed during routine cadaveric dissection. Peroneus tertius (PT) is peculiar to man, being a hallmark of bipedal locomotion and erect posture. During the course of gross anatomy dissection, a rare finding of accessory belly of PT muscle was discovered. A meticulous dissection was performed and the observations were noted. The PT displayed two distinct bellies of origin. Both the bellies were substantial in size and were eventually fused close to their insertion at the base of the fifth meta-tarsal bone. Innervation of both the bellies was derived from the deep peroneal nerve. Soft tissue defects of the leg may be effectively covered by local muscles in the vicinity of the wounds. PT has been reliably used in the past for local transposition flaps in the lower extremities. The relations of the superficial nerve and the PT during placement of the anterolateral portal in ankle arthroscopy are vital to avoid inadvertent neuromuscular injuries. The presence of two bellies of the PT muscle has been discussed in the comparative perspective. A precise and detailed knowledge of the anatomical details of the crural muscles is important for performing reconstructive surgeries.

Thirty-eight free fasciocutaneous flap transfers in acute burned-hand injuries

The benefits of free flap transfers in the acute burn injury are early wound closure, early mobility, reduced hospitalization, and possibly limb salvage. This retrospective study will attempt to provide principles to the use of free fasciocutaneous flap for the reconstruction of acute burned-hand injuries. Between 1995 and 2004, 5521 patients were admitted to the burn unit at Linkou Chang Gung Memorial Hospital. Of these, 38 patients (0.7%) patients received free fasciocutaneous flap transfers. Each patient's chart was reviewed the following data: age, gender, burn injury type, percentage of the burned area to total body surface area, flap type, operations prior to free flap coverage, the size and location of recipient area, timing of free flap coverage, operative time, duration of hospital stay, complications, flap survival and returning to work. All 38 free flaps survived and healed well. Three flaps with partial necrosis due to wound infections required subsequent debridement and skin grafting. Arterial thrombosis occurred in one patient and was salvaged successfully. Minimal donor-site morbidity with no intraoperative mortality was observed. Free fasciocutaneous flap transfer is a safe, efficacious one-stage reconstruction for acute burned-hands with satisfactory aesthetic and functional outcomes. Flap survival is not affected neither by the etiologies of burn nor the timing of free flap coverage.

Split Flexor Carpi Ulnaris Transfer: A New Functioning Free Muscle Transfer with Independent Dual Function

BACKGROUND

A functioning free muscle transfer is a well-established modality of restoring upper limb function in patients with significant functional deficits. Splitting the neuromuscular compartments of the free muscle based on its intramuscular neural anatomy and using each compartment for a different function would allow for restoration of two functions instead of one at the new distant site.

METHODS

The authors previously reported on the clinical use of a pedicled split flexor carpi ulnaris muscle transfer. They now report the use of this muscle as a functioning free split muscle transfer to restore independent thumb and finger extension in a patient with total extensor compartment muscle loss in the forearm and a concomitant high radial nerve avulsion injury.

RESULTS

Nine months postoperatively, the patient was able to extend his thumb and fingers independent of each other.

CONCLUSION

This is the first report of a functioning free split muscle transfer demonstrating two independent functions in the upper limb.

The distally pedicled peroneus brevis muscle flap anatomic studies and clinical applications

Defects in the distal third of the lower leg with bone or tendon exposure may require local or free flap reconstruction. For small and moderate lesions, the distally pedicled peroneus brevis muscle flap may be an effective procedure with less morbidity than a free tissue transfer. Six cadaveric specimens were dissected to determine the location of distal pedicles and the flap type. This flap was found to be a Type IV flap, and the location of distal pedicle was always located within 6 cm from the fibula tip. This flap was performed on 6 patients to cover defects in the distal third of the lower leg. The defect areas were the pretibial region in 2 cases, the lateral malleolus in 3 cases, and the Achilles tendon in 1 case. The peroneus brevis muscle was detached from the uppermost point of the fibula to obtain enough length to cover the defect. All flaps survived except 1 that experienced distal flap necrosis. Minor complications included skin graft failure in 2 cases. However, the final results demonstrated a smooth contour that eliminated dead space. Limited donor site morbidity was obtained in all cases. The distally peroneus brevis muscle flap therefore offers an alternative for reconstructive surgeons dealing with soft tissue defects of the lower leg.

Motor branch of the rectus femoris: anatomic location for selective motor branch block in stiff-legged gait

OBJECTIVE

To determine the ideal target point for selective motor branch block of the rectus femoris to treat stiff-legged gait.

DESIGN

Descriptive study.

SETTING

Anatomic institute of a university school of medicine in Korea.

CADAVERS

Twenty-two preserved adult cadavers.

INTERVENTION

The anterior thigh of the cadaver was dissected below the inguinal ligament. The motor branches of the 4 heads of the quadriceps were identified and traced from just below the inguinal ligament to the motor points.

MAIN OUTCOME MEASURES

The point T, where the motor branch of the rectus femoris is divided into smaller subbranches, was identified. Its location in relation to the surface anatomic landmarks was determined on the basis of the 2 anatomic lines that connect the anterior superior iliac spine to the medial femoral condyle, and the issuing spot of the femoral nerve below the inguinal ligament to the middle of the superior pole of the patellar.

RESULTS

The motor branch of the rectus femoris was divided into 2 subbranches at point T just before it reached the muscle. It nearly touched the medial margin of the rectus femoris at a proximal one-fourth to one-fifth point on 2 anatomic lines. The superior subbranch penetrated the muscle fascia at the posterior surface of the proximal one third of the muscle, whereas the inferior subbranch penetrated the muscle fascia at the medial border of the muscle.

CONCLUSION

The point T is the most suitable target point to selectively block the motor branch of the rectus femoris without affecting the other 3 motor branches of the femoral nerve in the treatment of stiff-legged gait.