1 Introduction

Avascular necrosis (AVN) in the femoral head significantly affects young and middle-aged individuals and has various contributing factors like alcohol abuse, steroid usage, coagulation disorders, and post-traumatic events.^1,2 Notably, an increase in AVN cases post-COVID-19 infection underlines the importance of early detection for effective management.¹²

Treatment options for femoral head osteonecrosis can be categorized into non-surgical and surgical approaches. Non-surgical methods involve activity modification and pharmacological agents, but these measures do not effectively halt disease progression.³ While pharmacological agents like bisphosphonates and antiplatelet drugs are used, they lack the potency to stop the disease's advancement.³

Core decompression stands as the primary surgical option for early-stage osteonecrosis, but in advanced cases, total hip arthroplasty (THA) becomes more appropriate.⁴ However, given that many AVN patients undergoing THA are relatively young, potential issues such as implant loosening and the need for revision surgeries in the future must be considered.⁵

The main goal in treating early osteonecrosis is to prevent femoral head collapse, emphasizing the significance of early intervention, particularly in stages I and II ⁶. The consensus recommends joint-preserving surgeries for early-stage patients, while arthroplasty, including THA, suits those in advanced stages.

Core decompression, with or without adjuvants like bone marrow and platelet-rich plasma, is the recommended strategy for treating early femoral head osteonecrosis (Ficat & Arlet stage < 2A). This aims to delay or halt AVN progression and prevent femoral head collapse before mechanical failure occurs.⁷ However, to address potential voids in the femoral head after core decompression, various adjuvants are used to enhance repair and offer structural support, such as autologous bone marrow and bone grafts.^7,8 These augment core decompression, improving its effectiveness in treating early femoral head osteonecrosis.

2 Surgical technique

Surgery is performed under spinal anesthesia with the patient lying supine on a radiolucent table, the affected limb under traction on a fracture table, and the contralateral limb in the lithotomy position to facilitate image intensifier guidance for proper antero-posterior and lateral views of the hip joint. The ipsilateral iliac crest and hip joint are prepped and draped following standard sterile protocol. Cancellous bone graft is harvested from the inner table of the ipsilateral iliac crest and minced (Fig. 1 and 2).

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Fig. 1 Armamentarium A. Guide wire. B. Reamer (size 6–10mm). C. Carrier. D. Guiding device with handle. E. Bone punch Main steps of surgical technique.

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Fig. 2 a) Markings under C-arm guidance in AP. b) Markings under C-arm guidance in lateral position, incision made on point of intersection.

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With the guidance of the image intensifier, the anterior aspect of the hip joint is marked by placing a guide wire parallel to the neck, and a lateral image is taken to mark a line parallel to the shaft. The intersection point of both lines serves as the entry point for the guide wire to the femoral head (Fig. 3). A 2.5 cm longitudinal skin incision is made at the entry point, deepening with a no. 15 scalpel through subcutaneous tissue, fascia lata, and vastus lateralis, which are split in line with fibers. A thick guide wire (2 mm) is inserted into the affected femoral head area, usually supero-lateral, under image intensifier guidance on both AP and lateral views. The guide wire is advanced up to 5 mm beneath the articular cartilage. The use of a thick wire facilitates negotiating the sclerosed necrotic area without bending. A conical proximal femoral nail helical blade reamer, conical in shape (end cutting tip distal 4 mm, proximal end 7 mm), is used to over-drill over the guide wire. The conical shape of this reamer aids in advancing through the sclerosed area with ease and generating less heat during reaming compared to a large cylindrical reamer. The reamer is withdrawn, and the guide wire remains in place. Cylindrical end-cutting reamers with a diameter of up to 10 mm are used to serially ream over the guide wire. Serial reaming helps avoid heat necrosis of the tunnel wall as its advanced with less force. A long curette is introduced into the canal to curette the walls of the necrotic area and tunnels, removing as much sclerotic bone as possible and opening up lacunae in the bones (Fig. 5a, 5b). The lateral cortex is reamed with a 10 mm reamer, facilitating the introduction of a graft-passing tube into the canal. Minced cancellous bone graft is filled into the 10 mm graft-passing plastic tube (Fig. 4a, 4b and 4c) (Fig. 6a, 6b).

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Fig. 3 a) Intraoperative image of guide wire passed to the AVN part of femoral head. b) Fluroscopy image of guide wire passed to the AVN part of femoral head.

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Fig. 4a Intraoperative image of conical proximal femoral nail helical blade reamer which is conical in shape is used to over drill over the guide wire.

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Fig. 4b Fluroscopy image of conical proximal femoral nail helical blade reamer which is conical in shape is used to over drill over the guide wire.

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Fig. 4c Cylindrical end cutting reamers are used to serially ream up to 10 mm over the guide wire.

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Fig. 5a Intraoperative image of long curette is introduced into the canal and walls of necrotic area and tunnels are curetted out to remove as much as sclerotic bone and to open up lacunae in the bones.

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Fig. 5b Fluroscopy image of long curette is introduced into the canal and walls of necrotic area and tunnels are curetted out to remove as much as sclerotic bone and to open up lacunae in the bones.

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Fig. 6a Minced cancellous bone graft.

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Fig. 6b Bone graft from illiac crest filled into plastic tube.

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The prefilled plastic tube is inserted into the canal and snugly fits into the lateral cortical window, preventing graft slippage into soft tissues during impaction and protecting surrounding tissues. A round metallic punch with an 8mm diameter, matching the inner diameter of the graft-passing tube, is introduced into the outer aspect of the tube. The metallic punch is malletted into the tube, pushing the graft into the canal, which is confirmed using the image intensifier to ensure proper filling of the tunnel (Fig. 7a, 7b). Once the necrotic area is filled with the graft, the tube and punch are withdrawn. If more graft is needed, the same steps are repeated. The tip of the graft tube is plugged with bone wax and reintroduced into the canal, with the wax pushed into the lateral window using the punch to seal the hole. Plugging the lateral window's outer cortex with bone wax prevents graft material slippage into tissues post-surgery and aids in retaining the graft within the tunnel. The wounds are washed and closed layer by layer with absorbable sutures in a standard fashion, followed by the application of sterile dressings (Fig. 8a, 8b and 8c). The post-operative period was uneventful, with no surgical site oozing. Rehabilitation involved non-weight-bearing ambulation with a walker from day 1 onwards, and the patient was discharged the very next day. Suture removal took place after 2 weeks, followed by monthly follow-up appointments.

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Fig. 7a The prefilled tube gets snuggly fit into the lateral cortical window, then a round metallic punch which matches the inner diameter of graft passing tube is introduced into the outer aspect of tube.

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Fig. 7b The metallic punch is malleted into the tube which pushes the graft into the canal, which is confirmed under image intensifier as filling of empty tunnel made.

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Fig. 8a Tip of graft tube is plugged with bone wax and reintroduced into the canal and wax pushed into lateral window with punch to plug the hole.

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Fig. 8b Plugging lateral window outer cortex with bone wax will prevent slippage of graft material into tissues post-surgery and aid in retaining the graft within the tunnel.

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Fig. 8c A minimally made incision.

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3 Discussion

Osteonecrosis, also known as avascular necrosis (AVN), results from reduced blood supply, leading to bone tissue death primarily in the hip joints of younger individuals. This condition causes the collapse of the femoral head's internal structure, joint incongruity, and secondary hip osteoarthritis. Long-term effects include significant discomfort, persistent pain, walking difficulties, and decreased mobility. Timely intervention is crucial to prevent severe hip joint damage and the need for total hip replacement within two years of AVN onset.⁹ While non-surgical treatments offer limited pain relief and disease control, joint-preserving procedures are recommended in the early stages, reserving total hip replacement for advanced cases or unsuccessful prior procedures.¹⁰

Core decompression, often combined with bone grafting, is a globally accepted joint-preserving surgical method.¹⁰ Studies have shown that drilling holes to remove necrotic bone and reduce intraosseous pressure promotes revascularization. Incorporating structural bone grafts helps prevent subchondral collapse and promotes bone remodeling through various processes.¹¹

Our technique introduces several modifications from previous methods. Initially, using a conical reamer allows for more precise penetration of necrotic and hardened areas. Sequential canal dilation reduces the risk of further bone heat necrosis. The bone graft insertion via a specialized tube ensures accurate placement without graft loss. Moreover, a specialized tube and punch aid in graft impaction into the necrotic area. Unlike prior techniques, we seal the canal with bone wax after grafting, preventing graft displacement into soft tissues when the patient turns to the same side post-procedure. The minimally invasive approach of our technique helps preserve compromised femoral head vascularity, reducing blood loss and operating time.

Institutional ethical committee approval

Not applicable.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

Ethical statement

Institutional Ethical Committee Approval: Not applicable.

Funding statement

Funding/Sponsorship: This research received no specific grant from any funding agencies in the public, commercial, or not-for-profit sectors.

Consent

Informed Consent: Detailed written informed consent was obtained for the publication of data, images, and treatment-related documents without any objection.

CRediT authorship contribution statement

All authors contributed equally to the conceptualization, writing, review, and editing of the manuscript.