Core Decompression Surgery for Hip AVN: What to Expect

What Is Core Decompression?

Core decompression is a joint-preserving surgical procedure used to treat avascular necrosis (AVN) of the femoral head before the bone collapses. The surgeon drills one or more channels into the dead ("necrotic") segment of the femoral head. This relieves the elevated pressure inside the bone, restores blood flow into the affected area, and triggers the body's natural healing and new-vessel formation.

The procedure is based on the idea that AVN behaves, in part, like a "compartment syndrome" of bone: dead and swollen marrow raises the internal pressure, which further chokes the already-compromised blood supply. By decompressing the bone, the surgeon interrupts this cycle and creates a channel through which healing tissue can grow.

Core decompression is most effective in early, pre-collapse disease (Ficat Stages I and II) with small-to-medium lesions. Once the femoral head has collapsed, the procedure is far less reliable, and total hip replacement is usually recommended instead.

Who Is a Candidate?

Core decompression is typically considered for patients with:

• Early-stage AVN (Stages I–II) without femoral head collapse
• Small or medium-sized necrotic lesions (large lesions have higher failure rates)
• Significant hip pain from confirmed AVN on MRI
• Younger, active patients in whom preserving the native hip and delaying replacement is a priority

It is generally not recommended when:

• The femoral head has already collapsed (Stage III or IV)
• Secondary arthritis is well established
• The necrotic lesion is very large

Goals of Surgery

• Relieve intraosseous pressure within the femoral head
• Stimulate revascularization (regrowth of blood vessels) and new bone formation
• Reduce pain in the affected hip
• Prevent or delay collapse of the femoral head
• Preserve the native joint and postpone or avoid total hip replacement

Variations and Augmentation

Core decompression is often combined with additional techniques to improve healing and provide structural support:

• Small-diameter multiple drilling: Using several small drill holes (percutaneous "multiple drilling") instead of one large channel; reduces the risk of weakening the bone
• Bone grafting: Filling the channel with the patient's own bone (autograft) or donor bone (allograft) to support the subchondral surface
• Vascularized bone graft: Transferring living bone with its own blood supply (such as a free vascularized fibula graft) into the channel — technically demanding but biologically powerful
• Biologic augmentation: Adding bone marrow aspirate concentrate (containing stem cells), bone morphogenetic proteins, or other growth factors to enhance healing
• Synthetic bone substitutes and tantalum rods: Used in some centers to provide mechanical support to the subchondral bone

Day of Surgery

Pre-Operative Preparation

• MRI review to confirm staging and map the necrotic segment
• Evaluation of the opposite hip (AVN is frequently bilateral)
• Discussion and management of the underlying cause (steroid use, alcohol, clotting disorders)
• Anesthesia pre-assessment
• NPO (nothing to eat or drink) from midnight before surgery
• Arrangement for crutches and help at home during the protected weight-bearing period

Anesthesia Options

• Spinal anesthesia (common): Numb from the waist down with sedation for comfort
• General anesthesia: Full sleep throughout the procedure
• Nerve blocks: May be added for post-operative pain control

Surgical Steps (30–60 minutes)

1. The patient is positioned on a fracture or radiolucent table allowing X-ray imaging
2. Sterile prep and draping
3. A small incision is made over the lateral thigh, below the greater trochanter
4. Under live X-ray (fluoroscopic) guidance, a guidewire is advanced up the femoral neck into the center of the necrotic segment
5. A drill or trephine is passed over the guidewire to create the core channel (or several small channels) into the dead bone — without breaching the joint surface
6. Necrotic bone may be removed and sent for analysis
7. The channel is augmented as planned — bone graft, vascularized graft, or biologic material may be inserted
8. The instruments are removed and final imaging confirms position
9. The small incision is closed in layers

This is frequently a same-day (outpatient) procedure through a small incision, particularly when multiple small drillings are used without extensive grafting.

Recovery Overview

• Protected weight-bearing: Crutches are used for roughly 6 weeks to protect the weakened femoral head while it heals and to reduce the risk of fracture or collapse
• Pain control: Pain typically improves within weeks as intraosseous pressure is relieved
• Physical therapy: Gentle range-of-motion and gradual strengthening as healing allows
• Imaging follow-up: Repeat X-rays and MRI monitor healing and watch for any progression to collapse
• Return to activity: Gradual return to low-impact activity over months; high-impact loading is avoided early
• Addressing the cause: Continued management of the underlying risk factor is essential to protect both hips

Risks and Complications

• Progression despite surgery: AVN may continue to advance and the femoral head may still collapse, ultimately requiring hip replacement — this is the most common reason for failure, especially with large or late-stage lesions
• Femoral fracture: Drilling weakens the bone temporarily; a subtrochanteric or femoral neck fracture can occur, which is why protected weight-bearing is important
• Infection: Uncommon with a small incision but possible
• Bleeding or hematoma
• Incomplete pain relief
• Anesthesia-related risks
• Need for further surgery: If decompression fails, total hip replacement remains the definitive option

What to Bring

• Comfortable, loose-fitting clothing
• Crutches (or arrangement to receive them) for protected weight-bearing
• Slip-on shoes to minimize bending at the hip
• Arranged help at home for the first weeks
• A list of current medications and details of the underlying cause of AVN

Outlook

When performed early — before the femoral head collapses — core decompression can meaningfully relieve pain and delay or prevent the need for total hip replacement, preserving the patient's own joint for years. Success rates are highest with small, pre-collapse lesions and decline substantially once collapse has occurred. Because outcomes depend so strongly on early diagnosis, prompt MRI evaluation of unexplained groin pain in at-risk patients is critical.