Popliteal Surface Research Articles

A rare anomalous muscle in the popliteal region - a case report.

Anomalous muscles are rarely seen in the popliteal region of the lower limb. Some of them are harmless and go unnoticed and some create problems such as neuropathies. We report a novel case of an unusual additional muscle in this region. The additional muscle was closely associated with the short head of the biceps femoris muscle. It took its origin from the lower part of the lateral supracondylar line and the adjoining popliteal surface of the femur. The muscle was 10cm in length, 1cm in breadth and was fleshy throughout. It was oriented parallel to the medial side of the tendon of biceps femoris. It was inserted to the posterior aspect of the head of the fibula, medial to the insertion of the biceps femoris. The additional muscle derived its nerve supply from the sciatic nerve. The common peroneal nerve was closely related to the medial border of the additional muscle.

A three-headed plantaris muscle with a bipartite insertion of its two accessory heads.

The plantaris muscle consists of a small muscular and a long tendinous part and is located at the superficial compartment of the posterior leg. The purpose of the current cadaveric report is to describe a rare variant of the plantaris muscle. During a routine dissection, a three-headed plantaris with two accessory heads was identified with a variant insertion of the two accessory heads. All heads originated from the femur popliteal surface, independently the one from the other. The first head contributed to the long and thin calcaneal tendon, and the two accessory heads were mainly inserted via their musculoaponeurotic expansion into the medial femoral condyle. The plantaris muscle morphological variability has been extensively studied lately. The incidence of the two-headed muscle has been estimated at 1.6%, while the three-headed muscle corresponds to an even rarer variation. This is the third case reported in the English literature, while the insertion of the two accessory heads has never been described before.

Locking plate augmentation of polymethylmethacrylate-filled distal femoral defects: A biomechanical study.

Benign, locally aggressive tumors of the distal femur are typically treated with intralesional curettage and polymethylmethacrylate (PMMA) cementation. However, it is not known whether plate fixation should be added to biomechanically augment these PMMA-filled defects. The purpose of this study was to evaluate the performance of two competing techniques for reconstruction of a distal femoral defect. For this biomechanical study, we used 12 composite femurs with properties comparable to bone. In nine femurs, identical contained medial distal femoral defects were created using a robotic arm. Group A contained three intact femurs, Group B three femurs with an unfilled defect, Group C three femurs reconstructed with PMMA alone, and Group D three femurs reconstructed with PMMA plus a medial locking plate. Locations of greatest stress concentration were determined by PhotoStress analysis, then three strain gauges were applied to each specimen at these high-stress locations. Specimens were loaded within a physiologic range followed by loading to failure. Outcome measures included construct stiffness, strain along the distal femur, and load at failure. Results showed that stiffness and strain were not significantly different between reconstructive techniques; however, both techniques reduced tensile strain along the popliteal surface by approximately 40% compared to non-reconstructed specimens. All specimens failed at the femoral neck before failing at the distal femur. These findings suggest that plate augmentation of PMMA-filled distal femoral defects like the one in this study offers insignificant biomechanical benefit within physiologic loads and therefore may be unnecessary.

Never undescribed four - headed plantaris muscle.

The plantaris is a small muscle of the superficial posterior compartment of the leg. It originates at the lateral supracondylar line of the femur and the knee joint capsule, from where it continues distally, forming a long and slender tendon distally attached to the calcaneal tuberosity. During standard anatomical dissection four-headed plantaris muscle was found and all of its heads connected to each other as a single muscle belly passing into tendinous structure which was distally attached as a standard plantaris muscle. The first head originated from the popliteal surface of the femur. The second one was originated from distal Kaplan fiber. In turn, the third and fourth heads were proximally attached to the lateral femoral epicondyle. Knowledge about morphological variations is necessary because of its potential clinical significance, which means not only neurovascular compressions, but also surgical procedures.

Novel innervation of accessory slip of lateral head of gastrocnemius muscle

The two heads of the gastrocnemius muscle, as well as the plantaris and soleus muscles, forms the superficial muscular group in the posterior compartment of the leg. The incidental occurrence of accessory slip of the lateral head of the gastrocnemius muscle in the right lower limb, innervated by a twig from the common peroneal nerve, is described in this report. We identified an anomalous 8 cm long muscle in the right popliteal fossa during standard academic dissection of a male corpse at the Department of Anatomy. It was attached to the lateral side of the femur's popliteal surface proximally and joined the lateral head of the gastrocnemius distally. In the left lower limb, no similar variation was observed.

Application of Fibre Bragg Grating Sensors in Strain Monitoring and Fracture Recovery of Human Femur Bone

Fibre Bragg Grating (FBG) sensors are gaining popularity in biomedical engineering. However, specific standards for in vivo testing for their use are absolutely limited. In this study, in vitro experimental tests were performed to investigate the behaviors and applications of gratings attached to intact and fractured thighbone for a range of compression loading (<300 N) based around some usual daily activities. The wavelength shifts and the corresponding strain sensitivities of the FBG sensors were measured to determine their effectiveness in monitoring the femoral fracture healing process. Four different arrangements of FBG sensors were selected to measure strains at different critical locations on the femoral sawbones surface. Data obtained for intact and plated sawbones were compared using both embedded longitudinal and coiled FBG arrays. Strains were measured close to the fracture, posterior linea aspera and popliteal surface areas, as well as at the proximal and distal ends of the synthetic femur; their responses are discussed herein. The gratings on the longitudinally secured FBG arrays were found to provide high levels of sensitivity and precise measurements, even for relatively small loads (<100 N). Nevertheless, embedding angled FBG sensors is essential to measure the strain generated by applied torque on the femur bone. The maximum recorded strain of the plated femur was 503.97 µε for longitudinal and −274.97 µε for coiled FBG arrays, respectively. These project results are important to configure effective arrangements and orientations of FBG sensors with respect to fracture position and fixation implant for future in vivo experiments.

The popliteal surface axis may define hip anteversion.

Objectives This study aims to investigate the usability and reliability of our new axis in a three-dimensional modelling work and demonstrate if it is a reproducible method for anteversion measurement that sufficiently correlates with other computed tomography (CT)-derived gold standards including trans- epicondylar axis (TEA) and posterior condylar axis (PCA).Patients and methods Three-dimensional solid models were derived from left femoral CT data of 100 participants (50 males, 50 females; mean age 57 years; range, 21 to 86). The newly proposed popliteal surface axis (PSA) was compared with TEA and PCA in terms of anteversion measurement on these solid models.Results Popliteal surface axis was found as a reproducible reference axis in our study as it could be measured in 99% of our sample. The mean value of PSA based anteversion was (-) 1.8° which was 10.7° and 4.4° for PCA and TEA, respectively. Popliteal surface axis was perfectly correlated with PCA and TEA for anteversion measurements (p<0.001, r=0.92 for both).ConclusionOur findings suggest that the newly defined PSA may be used as an alternative method for determination of anteversion.

A highly complex variant of the plantaris tendon insertion and its potential clinical relevance

The body is home to a number of unique and intriguing anatomical structures, plenty of which concern the muscles and their tendons. Of these, the plantaris muscle is reported to present a particularly high range of morphological variations. The muscle, passing distally throughout the length of the lower leg, consists of a small muscle belly and a long, thin tendon. It originates, traditionally, on the popliteal surface of the femur and the knee joint capsule, and then inserts to the calcaneal tuberosity. It has been suggested that mid-portion Achilles tendinopathy may be caused by certain plantaris tendon morphologies. This case report describes a new anomalous plantaris tendon insertion, closely related to the Achilles tendon. It comprise four distinct insertions and one direct merge with the calcaneal tendon. The current classification should be extended to accommodate such ‘rare cases’ to facilitate more successful Achilles tendinopathy treatment.

Proposal for a new classification of plantaris muscle origin and its potential effect on the knee joint

PurposeThe plantaris muscle (PM) is typically characterized by a short, slim and spindle-shaped muscle belly and long, thin tendon. It is situated posterior to the popliteal muscle, and anterior to the lateral head of the gastrocnemius muscle (GM). Little information exists regarding the high variability of origin of the PM. The main aim of the study was hence to characterize the morphology of the PM and its place of origin, classify it and evaluate its prevalence. MethodsClassical anatomical dissection was performed on 142 lower limbs (77 left, and 65 right) fixed in 10% formalin solution. The morphology of the origin of the PM and its prevalence was evaluated. ResultsThe PM was present in 128 lower limbs (90.1%). Six types of origin were observed, the most common being Type I (48.4%). This type was divided into two subtypes (A–B): subtype A attaching to the lateral head of the GM, lateral femoral condyle and to the capsule of the knee joint, and subtype B, attaching to the lateral head of the GM, the lateral femoral condyle, knee joint capsule and the popliteal surface of the femur. The second most common type was Type II (25%), attaching to the capsule of the knee joint and, indirectly, to the lateral head of the GM through the lateral femoral condyle. The third most common type was Type III (10.15%), attaching to the lateral femoral condyle and the knee joint capsule. Type IV (6.25%), the rarest type, attached to the lateral femoral condyle, knee joint capsule and to the iliotibial band. Type V (8.6%) originated only from the lateral condyle of the femur. Type VI (1.6%) contains only "rare cases". ConclusionThe PM presents high morphological variability, and its status as a residual muscle should be reconsidered. Our presented classification of its types of origin is a valuable addition for both clinicians and anatomists.Level of Evidence – II Basic Science Research

Segmental torsion assessment is a reliable method for in-depth analysis of femoral alignment in Computer Tomography

PurposeDe-rotational osteotomies are indicated in patients with pathologic femoral torsion. However, there is disagreement whether an osteotomy should be performed proximally or distally. Conventionally only the total torsion is measured, which does not allow differentiation between a torsional deformity located in the proximal or distal metaphysis or the diaphysis. The aim of this study is to validate a new multi-level measurement protocol for evaluation of the magnitude of torsion of the respective femoral segments in CT.Patients and methodsThe torsional profile of 30 femora was evaluated in CT scans. For separate measurements of the torsion of the metaphysis and the diaphysis, four axes where determined: one through the femoral neck, a second determined by the midpoint of the femoral shaft and the lesser trochanter, a third determined by a tangent dorsal to the popliteal surface, and a fourth axis posterior to the condyles. The total femoral torsion was measured between the first and the fourth axis, proximal torsion between the first and the second, mid torsion between the second and the third, and distal torsion between the third and the fourth axis. Four investigators performed all measurements independently and intra-class correlation coefficients (ICC) were calculated to evaluate intra- and inter-rater reliability.ResultsAverage total femoral torsion was 22.6 ± 8.7°, proximal torsion 47.7 ± 10.6°, mid torsion −33.4 ± 9.9°, and distal torsion 8.3 ± 3.2°. Intra-rater ICC ranged between 0.504 and 0.957 and inter-rater ICC between 0.643 and 0.992. The majority of the ICC were graded as “almost perfect” and some as “substantial” agreement.ConclusionEvaluation of the segmental torsion of the femur allows in-depth analysis of femoral alignment. High reliability was shown for this measuring method in computed tomography, which can be deployed when studying interdependencies between joint pathologies and torsional deformities or when planning the site for an osteotomy.Level of evidenceLevel III.

Evaluation of Intra- and Inter-observer Measurement Variability of a Radiographic Stifle Osteoarthritis Scoring System in Dogs.

Objectives To evaluate the intra- and inter-observer measurement variability of an existing osteoarthritis (OA) stifle scoring system. Methods Paired caudocranial and mediolateral canine stifle radiographs were selected randomly. A total of 15 assessment points were evaluated independently and graded twice (integer numeric scale: 1-4) at an interval of 2 weeks by three observers with different levels of experience. The grades for each of the 15 factors were summed to obtain the OA score for each patient. Results The 15 independent assessment points measured by the three observers showed high reproducibility and low intra-observer variability. Inter-observer variability was also low (mean: 1.09 ± 4.99, 95% CI [confidence interval]: -0.35 to 2.55). The most discordant ratings among the three observers involved sesamoid bones of gastrocnemius muscle (assessment point 11 of 15) and popliteal surface of femur (assessment point 10 of 15). Clinical Significance A validated and feasible OA scoring method is prerequisite for reliable radiographic assessment of OA progression. The low overall inter- and intra-observer variabilities among the 15 independent measures of the OA scoring system presented herein support its feasibility for application in clinical practice as an objective tool for radiographic scoring of stifle OA.

Radiologic Manifestations of Senile Lymph Nodes in the Popliteal Fossa.

To determine the radiologic manifestations of senile lymph nodes in the popliteal fossa for radiologic and clinical application. A total of six lower extremities from four unembalmed human cadavers were studied. Under a surgical microscope, 6% hydrogen peroxide was used to detect the lymphatic vessels commencing from the foot and leg. A 30-gauge needle was inserted into the vessels and injected with a radio-opaque lead oxide mixture. The specimens were radiographed and photographed to demonstrate the lymph nodes in the popliteal fossa. The final results were transferred to the computer for image analysis. An average of two lymph nodes (range 1 to 3) were found in the popliteal fossa of the lower extremity. They were divided into superficial and deep popliteal groups. The superficial group was located in the superficial layer of the popliteal fossa around the small saphenous vein (SSV). The deep group was close to the popliteal surface of the femur and always located next to the popliteal vein. All lymph nodes were transparent in appearance and contained coiled lymphatic tubules. The size and density of the tubules varied. The radiologic manifestations of senile lymph nodes in the popliteal fossa have been presented and discussed to upgrade our radiologic and anatomical knowledge. This will be of benefit for radiologic and clinical applications.

Popliteal Vessels Entrapment by a Variant Accessory Belly of Medial Head of Gastrocnemius

The present case report regards the incidental finding of right popliteal vessels entrapment by a variant accessory belly of the medial head of gastrocnemius. The accessory head of gastrocnemius took origin from the popliteal surface of the femur and joined the medial head. The popliteal vessels passed between the medial and the accessory head of the gastrocnemius. The accessory head was quite large and was supplied by a branch of tibial nerve. Popliteal vessels compression usually leads to a condition called popliteal vascular entrapment syndrome which is a rare clinical entity, predominantly in young adults. This anomaly might cause intermittent claudication, aneurysmal dilatation, thromboembolism and eventually limb-threatening ischemia. Early recognition and diagnosis is important to minimize surgical treatment and avoid vascular reconstruction. Knowledge about the rare anatomical variants of popliteal vessels is helpful for correct diagnosis and planning of treatment.

The squatting facet on femora of West Coastal Indian population

104 out of 108 adult femora from the West Coastal region of India show a distinct identifiable squatting facet on their popliteal surface. The data on such features are reviewed and its relevance to medico legal and anthropological science is discussed.