Arthroscopic Treatment of Avascular Necrosis of the Femoral Head

Abstract

Avascular necrosis of the femoral head arises due to inadequate blood supply to the femoral head, leading to cell death, fracture, and eventually collapse. The disease often begins as asymptomatic but can present with pain, stiffness, and limited range of motion in later phases. These symptoms cause disability, predominantly in young to middle-aged individuals. Both conservative and operative treatment modalities have been used depending on the progression of the disease. Timely surgical intervention is essential to enhance outcomes and avert stress fractures, subchondral collapse, and secondary hip arthritis. This technical note presents an arthroscopic approach to core decompression for the minimally invasive management of avascular necrosis of the femoral head.

Avascular necrosis of the femoral head (AVNFH) results from inadequate blood supply and can lead to pain, stiffness, limited range of motion, and disability for patients. This condition mainly affects young to middle-aged adults between the ages of 20 and 50.¹ AVNFH most commonly develops due to traumatic injuries, such as femoral neck fractures and hip dislocation.^1,2 Beyond injury, nontraumatic causes include corticosteroid treatment, alcohol abuse, hyperlipidemia, systemic lupus erythematosus, sickle cell disease, and HIV.² Furthermore, AVNFH can be a complication of surgical procedures involving the fixation of femoral neck fractures.^1,2 The failure of bone formation by osteoblasts to match bone resorption by osteoclasts is the main mechanism regardless of the cause. Approximately 20,000 to 30,000 cases of avascular necrosis occur per year in the United States alone.³

There is limited consensus on the standard of treatment for AVNFH. Conservative management has been used in the early stages of the disease. These treatments include observation and medications, such as disphosphonates and statins. Unfortunately, the disease often progresses despite conservative measures.

Early surgical treatment of AVNFH is a vital component of improving outcomes for patients. If left untreated, AVNFH can lead to localized stress fractures, irreparable subchondral collapse, and secondary hip osteoarthritis, which may require more aggressive joint preservation methods.^1,2,4 Current surgical treatment methods include core decompression, bone grafting, osteotomy, adjunctive cell therapy, resurfacing arthroplasty, and total hip arthroplasty.^2,4 Core decompression is the most common surgical intervention for pre-collapse AVNFH and is shown to have positive long-term outcomes in patients, although the specific surgical technique is still being improved. In this Technical Note and the associated video (Video 1), we describe a technique for arthroscopic core decompression in a retrograde fashion using multiple small-diameter drill holes while providing subchondral support using a hydroxyapatite screw and improving healing with the use of bone marrow aspirate concentrate (BMAC).

Surgical Technique

Indications and Preoperative Planning

Before the arthroscopic treatment of AVNFH, magnetic resonance imaging (MRI) and radiographs should be obtained to define the area of necrosis. MRI can also be used to identify areas of intra-articular pathology such as labral tears (Fig 1). The advantages and disadvantages of this technique are shown in Table 1.

Fig 1.

Radiographs of the right hip (right side modified supine). Plain T2-weighted image showing the precollapse avascular necrosis (AVN) (blue square) (A). Dunn view showing the area of necrosis (blue square) and a large cam deformity (B).

Table 1.

Advantages and Disadvantages

Advantages

Disadvantages

•Use of arthroscopy allows direct visualization or Doppler of the lateral epiphyseal vessels. •A combination of fluoroscopy and direct visualization can be used to prevent penetration through the femoral head while drilling. •A hydroxyapatite screw can be used for extra subchondral support when needed through a 6.5-mm diameter drill hole. This technique provides structural support without the need for autograft harvest and the associated morbidities.

•This technique is ideally used for the precollapse stage of avascular necrosis and has limited applicability when femoral head collapse is present. •This technique does not offload weightbearing portions of the femoral head. •This technique does not introduce a vascularized graft

Harvest of the Bone Marrow Concentrate

Before the patient’s surgery, a BMAC harvest is collected from the ipsilateral posterior superior iliac spine with the patient in prone position. The bilateral posterior iliac spines are then palpated, identified, and marked. The skin and deeper tissues, including the periosteum over the ipsilateral posterior iliac crest, are anesthetized with approximately 10 mL of preservative-free 0.25% bupivacaine. The bone marrow aspirate trocar is then used to access the patient’s bone marrow in the posterior iliac crest. The contralateral side is prepped if more aspirate is required.

Patient Positioning and Diagnostic Arthroscopy

Standard hip arthroscopy setup and patient positioning is performed. Anterolateral and midanterior portals are established, followed by an interportal capsulotomy. A diagnostic arthroscopy is performed followed by any other necessary central or peripheral compartment work.

Arthroscopic Decompression of the Avascular Necrosis

We next turn our attention to the AVNFH. If any defect in the articular cartilage is present, a microfracture awl is used to verify viable tissue. A positive ballottement test can be confirmed. To perform the ballottement test, a probe is used to compress the articular cartilage overlying the area of avascular necrosis. This articular cartilage can be compressed and found to rebound back to its normal position once the probe is lifted. Additionally, the lateral epiphyseal blood vessels are visualized for pulsation or verified to be intact with a Doppler ultrasound probe. After confirmation, the decision is made for a core decompression.

A smooth wire is carefully placed along the femoral neck with the entry point at the head-neck junction and directly into the lesion under direct multiplanar fluoroscopic evaluation. An Eflex Ablator (Smith & Nephew, Andover, MA) is used to triangulate the area of interest under fluoroscopic visualization (Fig 2). Once the correct position is confirmed, the 5.5-mm drill is placed over the wire, and core decompression is performed directly into the lesion, taking care not to penetrate the articular cartilage. After this, a 1.5-mm JuggerKnot drill (Biomet Orthopedics, Warsaw, IN) is used in retrograde fashion to decompress the area through the femoral neck to the site of the lesion within the femoral head. At least 5 passes are made around the 5.5-mm drill hole with the JuggerKnot drill, and bleeding is noted from the drill holes after arthroscopic fluid is turned off and the shaver device is used to create negative pressure. A 6.5-mm hydroxyapatite (HA) TwinFix Ultra anchor (Smith & Nephew) is then placed into the drill site to provide subchondral support at the area of interest (Fig 3).

Fig 2.

Confirmation of the area of necrosis (right side modified supine). The patient is in supine position. Arthroscopic view of the ballottement test using the Eflex device on area of avascular necrosis (AVN) with the arthroscope in the mid-anterior portal (A). Arthroscopic view of the lateral epiphyseal vessels with the arthroscope in the anterolateral portal viewed posteriorly (B). The Eflex device is used along with fluoroscopy to help triangulate for drilling (C and D).

Fig 3.

Core decompression (right side modified supine). Arthroscopic view of the drill guide at femoral head-neck (FHN) junction. (A and B) The arthroscope is in the anterolateral portal, and instrumentation is through the MAP. (C) Arthroscopic view of the bleeding from drill holes. (D) Insertion of hydroxyapatite (HA) screw for avascular necrosis (AVN) lesion subchondral support (d).

The ballottement test can be repeated at this point and is often negative or greatly diminished due to the subchondral support from the HA screw. If a defect is noted in the femoral head cartilage, 1 cc of Tisseel fibrin glue (Baxter, Deerfield, IL) can be prepared and used to fill the crevasse. The previously collected BMAC is injected into the drill holes using an #18-gauge spinal needle before capsular closure. Pearls and pitfalls of this procedure are summarized in Table 2.

Table 2.

Pearls and Pitfalls

Pearls

Pitfalls

•Traction can be used to access the area of AVN. A probe can be used to perform the ballottement test of the femoral head to help identify areas of AVN and pre-collapse. •An Eflex device can help triangulate the area of AVN on fluoroscopy while drilling. •A 1.5-mm drill is used to make small-diameter holes in the femoral neck. •Injection of the BMAC aspirate can be paced directly through the canulated hydroxyapatite screw. •Tisseel fibrin glue can be used along femoral head cartilage fissuring.

•The BMAC aspirate yield can be lower than desired. This can be avoided by prepping out both posterior superior iliac spines before beginning the procedure. •Pin trajectory into the AVN femoral head defect can be difficult depending on the location of the lesion. With the hip in traction, changes in hip position can be difficult. Use of a curved drill guide and flexible drill can be helpful in these situations.

AVN, avascular necrosis; BMAC, bone marrow aspirate concentrate.

Rehabilitation

Postoperatively, the patient is allowed flatfoot weightbearing with 20 pounds of pressure for 6 weeks. They may then progress to full weightbearing. Antirotational boots are used to protect the capsular repair for 10 days, and a postoperative hip brace is applied for 10 days. To prevent formation of scar tissue, a continuous passive motion device is initiated postoperatively and used for 6 weeks, in addition to circumduction exercises with physical therapy.

Discussion

This Technical Note describes an arthroscopic approach to core decompression for the minimally invasive management of AVNFH. We have previously described a core decompression with multiple small-diameter retrograde drill holes through the femoral neck and BMAC injection. However, in this note, we are reporting the use of the ballottement test to localize the area of necrosis and core decompression through the femoral head. This technique also uses an HA screw placed in a retrograde fashion under the subchondral bone to provide structural support to the AVNFH lesion without the morbidity associated with using autograft bone.

Core decompression for AVNFH has been conducted percutaneously in a retrograde manner through the lateral subtrochanteric femur. The rising popularity of hip arthroscopy has revolutionized this procedure, enhancing visualization for a more accurate diagnostic assessment and minimizing the risk of cartilage penetration during drilling. Performing a ballottement test allows for direct visualization of the necrotic region, providing a direct target for the subchondral support screw. Adopting arthroscopic core decompression eliminates the need for open surgery, yielding advantages such as a lower complication rate, reduced postoperative pain, and faster recovery time. Finally, arthroscopy allows direct visualization of the lateral epiphyseal vessels and gives the opportunity for Doppler assessment to ensure continued femoral head vascularity.

Alternative approaches using larger drill holes or a “trapdoor” technique for insertion of a vascularized bone graft have been previously described.⁵ Conversely, a previously described method by the senior author (M.J.P.) uses a 1.5-mm drill, creating smaller defects for precise tunneling into necrotic areas but without the desired subchondral bone support.⁶ The technique presented here involves using a 5.5-mm drill into the necrotic region, followed by the insertion of an HA screw or anchor for subchondral bone support. A 1.5-mm flexible drill through a curved guide is used to create smaller holes around the initial one, facilitating more diffuse blood flow in the necrotic area. Although outcomes data for arthroscopic core decompression remains limited, Li et al.⁷ showcased superior postoperative results with the use of multiple small-diameter drill holes in conjunction with hip arthroscopy, as opposed to drilling alone.

In conclusion, the presented technique expands on a previously described technique, using both arthroscopic and fluoroscopic modalities to aid in AVNFH lesion triangulation. This technique uses multiple 1.5-mm drill holes at the femoral head-neck junction with the added benefit of providing subchondral support by using a 6.5-mm HA screw to provide subchondral support to the necrotic area. The BMAC aspirate can be injected directly into this screw for precise placement into the lesion.

Disclosures

The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: M.J.P. reports a relationship with Steadman Philippon Research Institute that includes board membership and equity or stocks; a relationship with Smith and Nephew that includes consulting or advisory; a relationship with Arthrosurface that includes equity or stocks; a relationship with Vail Valley Surgery Center LLC that includes board membership and equity or stocks; and a relationship with the Steadman Clinic that includes board membership and equity or stocks. All other authors (E.K.A., D.K., O.M.J., J.V.H.B., H.N., A.N.) declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Supplementary Data

Video 1

This is a 17-year-old male patient who was involved in a bicycle accident and sustained a posterior hip dislocation that required closed reduction. Soon afterward, he developed avascular necrosis of the femoral head and failed nonoperative treatment. He was indicated for surgical intervention. Radiographs indicated area of avascular necrosis. Before standard hip arthroscopy, bone marrow aspirate concentrate harvest is performed using the ipsilateral posterior superior iliac spine, with the contralateral side being used if more aspirate is needed. The patient is placed in the modified supine position. Anterolateral and mid-anterior portals are placed. An interportal capsulotomy is performed followed by a diagnostic arthroscopy to identify any intra-articular pathology (Ballottement test: Arthroscope in the mid-anterior portal; Arthroscopic visualization of lateral epiphyseal vessels: Arthroscope in the anterolateral portal viewing posteriorly; Core decompression: Arthroscope in the anterolateral portal and instrumentation through the mid-anterior portal; Right side; modified supine).

An Eflex instrument can be used to show the ballottement test, indicating the area of avascular necrosis. One of the advantages of hip arthroscopy is direct visualization or Doppler ultrasound of the lateral epiphyseal vessels. While traction is applied, intra-articular work can be completed, including chondroplasty of the femoral head. In this situation, an acetabuloplasty is performed in preparation of necessary labral work. This patient had a large femoral neck lesion, which was initially removed with an osteotome followed by a motorized burr.

The use of both fluoroscopy and arthroscopy can help with exact placement of drilling into the femoral neck. A 5.5-mm drill is used followed by a 6.5-mm hydroxyapatite screw for structural support. Any prominent portion of the screw can be burred down to a flat surface. Further core decompression is then performed with a 1.5-mm JuggerKnot drill in a retrograde fashion to decompress the area from the femoral neck to the site of the lesion within the femoral head. Multiple passes are made with the drill, and bleeding is noted from the drill holes after arthroscopic fluid is turned off. The number of passes is variable with the objective of stimulating bleeding throughout the defect; typically, this is between 5 and 10. A key aspect of this technique is the creation of a relatively large number of small-diameter tunnels rather than 1 large-diameter tunnel, with the primary aim of stimulating blood flow more diffusely throughout the area of necrosis and avoiding the creation of an unnecessarily large cortical defect. The concentrated bone marrow aspirate collected earlier is then injected into these drill holes. The suction seal is then checked. As the final step, the capsular closure is performed.