Size, Shape, Prominence and Localization of Gerdy’s Tubercle in Dry Human Tibial Bones

 

J. S Thaslima Nandhini¹, K. Yuvaraj Babu², Karthik Ganesh Mohanraj^3*

¹Graduate Student Saveetha Dental College, Saveetha Institute of Medical and Technical Sciences (SIMATS), Saveetha University, Chennai, India

²Assistant Professor, Department of Anatomy, Saveetha Dental College, Saveetha Institute of Medical and Technical Sciences (SIMATS), Saveetha University, Chennai, India

³Senior Lecturer, Department of Anatomy, Saveetha Dental College, Saveetha Institute of Medical and Technical Sciences (SIMATS), Saveetha University, Chennai, India

 

ABSTRACT:

Introduction:Morphometric parameters of upper end of tibia can be used to guide treatment and monitor outcome of total knee replacement surgeries. Gerdy’s tubercle is a triangular facet situated on the anterolateral side of the lateral condyle of proximal end of tibia. It serves as a critical landmark in most of the surgical approaches to the proximal tibia and distal femur. Aim of the study is to evaluate and analyze the size, shape, prominence and localization of Gerdy’s tubercle in dry tibial bones. Material and Methods: In the present study a total of 50 dry human tibial bones were obtained from the Department of Anatomy, Saveetha Dental College and Hospitals and from Madras Medical College, Chennai and evaluated. The size, shape, prominence and localization of Gerdy’s tubercle were evaluated. With the help of Vernier caliper and ruler the diameter and localization of the tubercle was measured. Shape and prominence of the tubercle was observed morphologically. All observations were noted, tabulated, evaluated and represented graphically. Results: The mean diameter of Gerdy’s tubercle on left tibia was 13.1mm ± 2.45 and 12.20mm ± 1.87 on right tibia. The shape of the Gerdy’s tubercle on left tibia was found to be triangular in 70% and oval in 30%. On right side the shape was triangular in 60%, oval in 20% and irregular in 20%. The surface prominence of Gerdy’s tubercle on left tibia was rough in 30%, smooth 70% and 40% rough, 60% smooth on right side. For localization the distance from the tip of the Tibial tuberosity to the tip of the Gerdy’s tubercle was measured and found to be 55.90mm ± 6.34 on left side and 57.60mm ± 5.89 on right side. Conclusion: The present study furnishes morphological and morphometrical information on South Indian tibial bones, providing an anatomical baseline to correlate anatomical findings with surgical and radiological presentations. Apart from being of morphological and morphometric interest these variations may be useful even for clinical interests.

 

 

 

INTRODUCTION:

Clear knowledge on the morphology and morphometry of upper end of the tibia is of utmost importance as it provides reliable method of evaluating knee deformity and related arthroplastic surgeries.

 

 

Morphometric parameters of upper end of tibia can be used to guide and treat outcome of total knee replacement surgeries. It is also a site for the insertion of a periosteal needle by with intramedullary fluids may be infused in neonates ¹. Any fracture of this tubercle occurs along with tibial tuberosity ². It has been used as a source of bone graft ³. As the peroneal nerve runs near the tubercle it serves as an important landmark ⁴ which provides sensation and motor function to parts of lower leg ⁵.

 

 

The term tubercle in Gerdy’s tubercle is in fact a misnomer. It is actually facet present on upper end of tibia on the antero-lateral surface of lateral condyle ⁶. Gray’s anatomy describes it to be located around 1 cm below joint line and 2cm lateral to tibial tuberosity. It is produced by the tibial attachment of iliotibial tract ⁷. Generally, tubercle is defined as a round projection or nodule or small eminence on the surface of the bone. Whereas the bones display articular surfaces at synovial joints with their neighbouring structures and if small, these are called facets ⁸. These osseous surfaces are smooth. In addition, some large tendons are attached to facets which lack regular contours of articular surfaces but resemble them in texture they are being poorly vascularized and are sometimes depressed ⁹.

 

Recognition of Gerdy's tubercle is an important landmark for several approaches to the knee particularly in the case of knee arthroplasty. The clinical significance of Gerdy’s tubercle concerns the tibia’s big oblong-shaped elevation ¹⁰. Most surgical approaches to the proximal tibia and distal femur show Gerdy's tubercle as a critical landmark. Identification of this bony landmark can be interrupted by several physical factors such as soft tissue swelling, morbid obesity, or disruption from bony injury ¹¹. Anatomically tubercle’s surface texture and shapes are categorized into triangular - smooth, circular - smooth, vertically oval - smooth, transversely oval - smooth, irregular - rough and triangular - rough types ¹².

 

The main objective of this study is to determine a reliable way of identifying the normal anatomical localization, size and shape of Gerdy's tubercle with reference to the surrounding bony features during various surgical approaches to the knee using simple morphometric measurements.

 

MATERIALS AND METHODS:

A total of 50 dry human Tibial bones were obtained from the Department of Anatomy, Saveetha Dental College and Hospitals and from Madras Medical College, Chennai and evaluated. With the help of Vernier caliper, the Gerdy’s tubercle was evaluated for size, shape, prominence and localization. The diameter of the tubercle was determined by measuring the two short side to side margins as Breadth and the longest superior to inferior margins of the tubercle as Length. Localization of the tubercle was determined by taking tibial tuberosity as reference point thereby measuring the distance between tibial tuberosity to Gerdy’s tubercle. Tubercle’s surface texture and shapes were categorized into triangular-smooth, circular-smooth, vertically oval-smooth, transversely oval- smooth, irregular-rough and triangular-rough types. These shapes and prominences of the tubercle were observed morphologically and photographed. All observations were noted, tabulated, evaluated and represented graphically.

 

RESULTS:

The morphological feature of Gerdy’s tubercle on right and left tibia is shown in the Figure - 1 and Figure - 2. The mean diameter of Gerdy’s tubercle on left tibia was 13.1mm ± 2.45 and 12.20mm ± 1.87 on right tibia (Figure - 3). The shape of the Gerdy’s tubercle on left tibia was found to be triangular, 70% (Figure - 4) and oval in 30% whereas on the right side the shape was triangular 60%, oval 20% and irregular 20% (Figure - 5). The surface prominence of Gerdy’s tubercle on left tibia was found to be rough in 30%, smooth in 70% (Figure - 6) and on right side it was rough 40%, smooth 60% (Figure - 7). For localization the distance from the tip of the Tibial tuberosity to the tip of the Gerdy’s tubercle was measured and found to be 55.90mm ± 6.34 on left side and 57.60mm ± 5.89 on right side (Figure - 8).

 

 

Figure - 1: Gerdy’s Tubercle on Right Tibia

 

 

Figure - 2: Gerdy’s Tubercle on Left Tibia

 

 

Figure - 3: Diameter of Gerdy’s tubercle of Tibia

 

 

 

 

Figure - 4: Shape of Gerdy’s tubercle of Tibia – Left Side

 

 

 

 

 

Figure - 5: Shape of Gerdy’s tubercle of Tibia – Right Side

 

 

Figure - 6: Prominence of Gerdy’s tubercle of Tibia – Left Side

 

 

Figure - 7: Prominence of Gerdy’s tubercle of Tibia – Right Side

 

 

Figure - 8: Localization of Gerdy’s tubercle of Tibia

DISCUSSION:

The present study demonstrated the anatomical variations in the shape, size, texture and localization of Gerdy’s tubercle in dry human tibial bones. These variations have not been reported in the literature of anatomy. Although different authors have described it to be of different shape and size but there is no consensus in the shape of the Gerdy’s tubercle or any previous study which has been demonstrated it’s inconsistency in texture. On reviewing various Atlas of Anatomy it has been observed that, Netter’s Atlas of Human Anatomy shows Gerdy’s tubercle to be transversely oval in one plate, where it is demonstrated to be triangular in other plates ¹³. Few other studies have described Gerdy’s tubercle as a flat but definite marking, which is triangular facet like on anterior part of lateral condyle of tibia but there was no statement of different shapes shown by them ¹⁴.

 

Generally many ligaments and tendons advance towards their point of attachment sites obliquely ¹⁵, as a result they make contacts with the bone immediately earlier to their attachment in certain positions of the joint were they act upon. Such contact between the tendon, ligament and bone influences impact upon stress dissipation at the entheses. The attachment of a tendon and ligament to the skeleton is obviously the fundamental function of any enthesis and they are vital to force transmission. By doing so the muscle, tendon and ligament makes a rigid contact and upon continuous pull and subsequent erosion on the point of contact on bone determines the shape, size and texture of any facet or tubercle.

 

As a matter of mere adaptation for securing skeletal anchorage the tendons and ligaments often flare at their attachment sites, which resist the effects of insertion angles to alter. Flaring of enthesis is particularly striking on the extremities ¹⁶. These studies may possibly elucidate the highly variable shape, size, texture and localization of Gerdy’s tubercle in the dry tibial bone. The importance of Gerdy’s tubercle in surgical practice is also vital. It is a very important anatomical landmark for many surgical processes in this region including bone graft and knee arthroplasty. Gerdy’s tubercle is also used as a light-house, the trajectory of the peroneal nerve defines the level of the proximal aspect of the tibial bone and marked previous to the placement of devices and the instrumentation, which avoids injury to the peroneal nerve and its branches in the leg.

 

Based on the osteotomy of Gerdy’s tubercle of the tibial bone and ilio-tibial band a novel technique has been used which permits excellent visualization and fixation of lateral intra-articular coronal fractures of the tibial condyle ¹⁷. These fractures are treated surgically by open reduction and internal fixation. Another study suggested that cancellous bone grafts might be harvested from Gerdy’s tubercle on the proximal metaphysis of the tibia for surgical procedures on the upper extremity ¹⁸. Harvesting the proximal end of tibia is a well recognized and important surgical procedure, for acute and chronic pathological bony defects of leg ^19,20. The lateral approach has been described using an oblique incision from Gerdy’s tubercle to apex of tibial tuberosity to successfully allow entry through the cortex to harvest cancellous bone avoiding the epiphyseal line ²⁰.

 

CONCLUSION:

In the present study examination of Gerdy’s tubercle at the anterolateral surface of lateral condyle of tibia shows more than usual variations in its shape and texture. Also the study shows that, the Gerdy’s tubercle has found to be more of the facet than a tubercle. The study furnishes morphological and morphometrical information on South Indian tibial bones with respect to Gerdy’s tubercle, providing an anatomical baseline to correlate anatomical findings with radiological and surgical presentations especially during knee replacement surgeries. Apart from being of morphometrical interest these variations may also be useful even for clinical interventions.

 

CONFLICT OF INTEREST:

No conflict of interest to declare.

 

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Accepted on 26.06.2018        © RJPT All right reserved

Research J. Pharm. and Tech 2018; 11(8): 3604-3608.