A Cost-Effective Novel Surgical Technique of Core Decompression with Bone Marrow Aspiration Concentrate: A Preliminary Cadaveric Study

Abstract

Introduction

Core decompression supplemented by stem cell incorporation is an upcoming field of research in avascular necrosis of the femoral head. Plugging the canal to avoid loss of the concentrate injected has been recognized as a crucial step to improve the efficacy of the procedure. We describe a new surgical technique that results in native bone plug formation and eliminates the need for any additional blocker.

Methodology

This pilot study was performed on 4 cadaveric proximal femurs. The standard technique was used for core decompression and bone marrow aspirate concentrate (BMAC) injection. Additionally, two more tracts were drilled, superolateral, and inferomedial to the primary tract.

Results

No leakage of the radiopaque dye was observed from the entry point of the primary tract, ensuring its complete blockage in all 4 cadaveric proximal femurs. This was confirmed by sectioning the femur specimens which manifested bone plug formation at the confluence of the three tracts.

Conclusion

Our technique is a unique and economical method of preventing leakage of BMAC through the entry point in the proximal femoral metaphysis. This may not only benefit patients but can also provide the groundwork for further research in this field.

Introduction

Core decompression has been widely employed to slow the disease progression in early avascular necrosis (AVN) of the femur head [1]. Combining it with adjunctive procedures like bone marrow aspiration concentrate (BMAC)/vascularized bone graft/mesenchymal stem cell therapy has shown to further improve the clinical outcome and postpone the need for total hip arthroplasty (THA) in young patients [2–4]. In the case of BMAC, optimal delivery to the required necrotic area and preventing its extravasation is challenging. A thorough literature search revealed a few described methods of plugging the canal to prevent stem cell leak [5–8]. Materials like bone wax, gel foam, and allogenic bone graft used to occlude the outlet tend to increase overall surgical cost and carry an inherent theoretical risk of foreign body reaction. Moreover, Hernigou et al. [9] believed that despite closing the entry point with a bone plug, some leakage of bone marrow might still occur. Considering the aforementioned problems, we aimed at devising a novel surgical technique to ensure sufficient retention of stem cell concentrate in the dispatched area. We further conducted a cadaveric experiment using a radiopaque dye to substantiate the theoretical effectiveness of our technique.

Method

To prove its effectiveness, we conducted our novel surgical technique on four freshly dissected formalin-preserved cadaveric femur specimens obtained from the anatomy department of our institution (Fig. 1a).

Fig. 1.

a Formalin mounted cadaveric specimen of proximal femur fracture. b Insertion of a guidewire. c Insertion of 8 mm drill bit over a guide wire. d A through and through channel is formed by the drill bit. e, f Secondary superolateral and superomedial tracts drilled

Technique

The cadaveric bone was fixed on a radiolucent table. A guidewire was inserted starting from the lateral aspect of the metaphysis, through the neck, into the head crossing its articular surface under fluoroscopic guidance (Fig. 1b). An 8 mm cannulated drill was passed over the guidewire making a complete channel exiting through the femur head (Fig. 1c, d). This tract was termed as the “primary tract”. Then the guidewire was removed, the drill bit was partially withdrawn up to the lateral one-third of the primary tract, and two tracts were drilled superolaterally and inferomedially with reference to primary tract (Fig. 1e, f) and these were termed as “secondary tracts”. To check its efficacy in preventing BMAC extravasation, A radiopaque dye (methylene blue) was injected from the cranial aspect of the primary tract under fluoroscopic guidance. The proximal femur specimens were cut with the help of an oscillating saw in a coronal plane traversing through the tract to identify the bone plug.

Results

The radiology revealed the formation of a bone plug at the base of the primary tract. The radiopaque dye which was injected from the cephalic aspect of the primary tract did not show caudal leakage in any of the 4 cadaveric specimens (Fig. 2a–c). Instead, it accumulated at the junction of the three tracts (Fig. 2d). Moreover, even coronal sections of the proximal femur showed occlusion of the primary tract by a bone plug (Fig. 3).

Fig. 2.

a Proximal femur after tract formation with a syringe of methylene blue. b C arm image showing radiopaque dye at the cranial aspect of the proximal femur. c Filling of the primary tract with radiopaque dye. d No seepage of radiopaque dye from the entry of tract and getting accumulated at a site where primary and secondary tracts are crossing

Fig. 3.

Coronal section of the specimen showing the newly formed bone plug

Discussion

Core decompression coupled with adjuvants like BMAC has shown to be of great benefit in the early stages of osteonecrosis of the hip [10]. A problem faced during implantation of bone marrow concentrate in the femoral head is its leakage. Hernigou et al. [9] hypothesized that the injected bone marrow is lost in two ways. Firstly, the leakage occurs through the entry point of the injection, and secondly, seepage into the circulatory system of the proximal femur. Whereas we cannot prevent the loss of valuable BMAC in the circulation, various methods have been tried to prevent leakage from the entry site [5–8].

Our novel technique not only provides an effective way to prevent this leak but also avoids the need for any additional plug. We proposed that while drilling the secondary tracts, the drill bit would have compressed the bone on the edges and pushed it into the primary tract resulting in the bone plug formation at the base. Our hypothesis was further strengthened by the bone plug we discovered in the coronal sections.

The materials used to plug the drilling canals are divided into three types: Autogenic bone graft, Allogenic bone graft, and synthetic materials. Autogenic bone grafts are considered the safest of all three, but it increases the morbidity of the patient. The allogenic bone graft used for bone plugging increases the risk of transmission of viral infections, immune response and it also requires the facility of a bone bank which is not present in all hospitals. The synthetic materials commonly used to plug the canal are bone wax, gel foam, and synthetic bone grafts. This synthetic material can induce a foreign body reaction or immune response, predisposing to the risk of infection and increased morbidity [11–13]. Synthetic bone grafts like calcium sulphate and phosphate are only osteoconductive; take around 6–18 months to absorb in the human body and add to the total cost of the surgery, 10 ml synthetic bone graft costs around 300 dollars. Our technique converts in situ bone into a plug, thereby avoiding the aforementioned issues.

Core decompression is an established surgical technique to reduce the intraosseous pressure in the femoral head by drilling and which later on activates the neovascularization. Simank et al. [14] demonstrated in the hips of sheep that within 3 weeks following drilling, there is the formation of new vessels that originates from the periosteum as well as from the bone marrow; these vessels also form anastomoses between the periosteal-diaphyseal-metaphyseal and the epiphyseal-physeal circulatory system. The Rehabilitation protocol after core decompression is usually 6–12 weeks with the help of crutches; protected weight bearing to prevent further collapse of the femoral head and during that time, formation of neo-vascularization and new bone formation is seen. The patients usually resume their normal daily activities 3 months post-surgery [2, 7, 8].

Finally, our study has some limitations which must be acknowledged. Primarily, it is a cadaveric study and more data on its in vivo efficacy is required to conclude any clinical advantage. Additionally, drilling thrice with an 8 mm drill might predispose the patients to postoperative fractures and a long rehabilitation period. However, the usual protocol after core decompression is to allow full weight bearing on the operated limb only after 6–12 weeks [2, 7, 8]. This might allow the primary and the secondary tracts to heal thereby decreasing the chances of postoperative fractures. The rehabilitation protocol and follow-up investigation like MRI to validate the healing nature of tracts are required in future clinical trials.

Conclusion

In conclusion, we report a cost-effective novel technique to prevent leakage of BMAC through the entry point of the decompression tract. We recommend further clinical studies to substantiate our claims and decide the effectiveness of this innovative method.

Funding

Nil.

Declarations

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical standard statement

This article does not contain any studies with human or animal subjects performed by the any of the authors.

Informed consent

For this type of study informed consent is not required.