Vascularized Greater Trochanter Bone Flap Transfer for Treatment of ARCO Stage-IIB to IIIB Osteonecrosis of the Femoral Head

Abstract

Background:

The goal of a vascularized bone flap transfer is to replace the necrotic bone of the femoral head, restore the blood supply, and provide new bone and mechanical support for the femoral head.

Description:

The major steps of the procedure that are demonstrated in this article are: (1) using the anterolateral approach to the hip, the incision is made; (2) the interval between the rectus femoris and vastus lateralis is split, the transverse branch of the lateral femoral circumflex artery is identified, and the pedicle is isolated and protected; (3) the vascularized bone flap is harvested from the greater trochanter; (4) necrotic bone is debrided through a bone window made at the junction of the femoral neck and head; (5) the cancellous bone from the greater trochanter is implanted, and the vascularized bone flap is positioned and fixed; and (6) the wound is closed in layers. Complications are rare, and full weight-bearing is allowed after 3 months postoperatively.

Alternatives:

Free vascularized fibular graft.

Rationale:

Compared with a free vascularized fibular grafting technique, vascularized bone-grafting of the greater trochanter has the advantages of being less invasive, incurring lower donor-site morbidity, and not requiring any microsurgical technique because there is no vascular anastomosis.

Introductory Statement

Use of vascularized greater trochanter bone flap transfer to treat osteonecrosis of the femoral head is a joint-preserving procedure that can be considered for younger patients who have symptomatic disease with cysts of the femoral head and either no subchondral fracture or a subchondral fracture with <4 mm of collapse, without any changes from degenerative hip disease.

Indications & Contraindications

Indications

• Patients who are <45 years old and have symptomatic disease with cysts of the femoral head and either no subchondral fracture or a subchondral fracture with <4 mm of collapse, without any changes from degenerative hip disease¹.

Contraindications

• Association Research Circulation Osseous (ARCO) stage IV (presence of degenerative disease).

• Defect of the greater trochanter due to previous surgeries.

• Active infection of the hip joint or any other region.

Step 1: Positioning and Incision

With the patient in the supine position, raise the affected side and use the modified anterolateral approach.

• Place the patient in the supine position with the ilium elevated to 60° and drape only the involved leg.

• Identify and mark the anterior superior iliac spine (ASIS) and the greater trochanter.

• Make a skin incision 4 cm from the ASIS, extending it distally from the iliac crest down to the tip of the greater trochanter and then extending it vertically down along the anterior margin of the trochanter (Video 1).

Video 1.

Download video file ^{(9.2MB, mp4)}

DOI: 10.2106/JBJS.ST.18.00092.vid1

Anterolateral approach to the affected hip.

Step 2: Identification of the Pedicle

Locate the transverse branch of the lateral femoral circumflex vessels (TLFCVs) in the muscle interval.

• Locate and split the interval between the rectus femoris and vastus lateralis in the direction of the skin incision.

• Identify the TLFCVs beneath the rectus femoris and vastus lateralis interval (Fig. 1, Video 2).

• Isolate and protect the pedicle (TLFCVs).

Fig. 1.

The transverse branch of the lateral femoral circumflex vessel (TLFCV) is identified in the interval between the rectus femoris and vastus lateralis.

Video 2.

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DOI: 10.2106/JBJS.ST.18.00092.vid2

Identification of the transverse branch of lateral circumflex femoral artery.

Step 3: Bone Flap Preparation (Videos 3 and 4)

Harvest the vascularized bone flap, pedicled along with the TLFCVs, from the greater trochanter.

• Incise part of the vastus lateralis and protect it as a flap.

• As the TLFCVs go along the deeper muscle bundles to the greater trochanter, do not further dissect the vessels within these muscle bundles to prevent any vessel injury.

• In the lateral region of the greater trochanter, where the TLFCVs enter, use an osteotome to obtain a bone flap that is approximately 3 cm long and 2 cm wide, with a vascular pedicle of as long as 5 cm (Figs. 2 and 3).

• Save the pedicled bone flap in a saline solution-soaked gauze for later use.

Fig. 2.

The greater trochanter bone flap is approximately 3 cm long and 2 cm wide.

Fig. 3.

The vascularized bone flap is taken from the greater trochanter.

Video 3.

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DOI: 10.2106/JBJS.ST.18.00092.vid3

Separating the vascular pedicles from the vastus lateralis muscle.

Video 4.

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DOI: 10.2106/JBJS.ST.18.00092.vid4

Harvesting a bone flap from the greater trochanter along with the vascular pedicle based on the transverse branch of the lateral circumflex femoral artery.

Step 4: Debridement

Debride necrotic bone through a bone window made at the junction of the femoral neck and head.

• Expose the anterior aspect of the hip joint capsule in the interval between the rectus femoris muscle and gluteus medius muscle.

• Incise the capsule in a T shape to expose the femoral head and neck. Cut the upper border of the head and neck transversely for 4 cm, and then cut along the femoral neck longitudinal axis, making a T shape.

• Use an osteotome to make a bone window that is approximately 2 cm long and 2 cm wide at the femoral head-neck junction (Fig. 4).

• Remove the dead bone with a high-speed abrasive drill according to the preoperative magnetic resonance imaging (MRI) scan or computed tomography (CT) evaluation and use a curet to create a cavity in the femoral head until bleeding surface can be seen (Fig. 5).

• Ensure that care is taken to avoid “cutting out” the subchondral bone and compromising the femoral head cartilage surface (Videos 5, 6, and 7).

Fig. 4.

A 2 × 2-cm bone window is made at the junction of femoral head and neck using an osteotome.

Fig. 5.

Debridement is done with a high-speed abrasive drill, and a curet is used to create a cavity in the femoral head.

Video 5.

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DOI: 10.2106/JBJS.ST.18.00092.vid5

Exposure of the anterior aspect of the femoral head and neck.

Video 6.

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DOI: 10.2106/JBJS.ST.18.00092.vid6

Creation of a 2 × 2-cm window at the junction of femoral head and neck.

Video 7.

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DOI: 10.2106/JBJS.ST.18.00092.vid7

Debridement and removal of the necrotic bone in the femoral head.

Step 5: Bone Implantation

Implant the cancellous bone and position the vascularized bone flap.

• Transfer the autologous cancellous bone taken from the great trochanter into the excavated region of the femoral head and impact it firmly.

• Attempt to elevate the collapsed segment of the femoral head, if present, with a bone impactor¹.

• Transfer the vascularized bone flap by translating the graft on its vascular pedicle toward the femoral neck corticotomy (Fig. 6).

• Make sure the bone flap is fixed firmly. The bone flap is jammed into place with a bone impactor. If the stability of the graft with only interference fit is insufficient, then fixation of the graft using an absorbable screw is an option (Videos 8, 9, and 10).

Fig. 6.

The vascularized bone flap pedicled with the TLFCVs is transferred to the femoral head.

Video 8.

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DOI: 10.2106/JBJS.ST.18.00092.vid8

Harvesting of cancellous bone from the greater trochanter.

Video 9.

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DOI: 10.2106/JBJS.ST.18.00092.vid9

Implantation of the cancellous bone and insertion of the vascularized bone flap.

Video 10.

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DOI: 10.2106/JBJS.ST.18.00092.vid10

Fixation of the bone flap.

Step 6: Wound Closure

The wound is closed layer by layer.

• During closing, suture back the vastus lateralis flap that had been sectioned.

• A drain can be used for 24 to 48 hours (Video 11).

Video 11.

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DOI: 10.2106/JBJS.ST.18.00092.vid11

Performance of layered wound closure.

Results

In our previous study, in which we reported the overall outcome after vascularized greater trochanter bone flap transfer, the femoral head preservation rate was 88% of 195 hips¹. Twenty-three hips required conversion to a total hip arthroplasty at a mean of 8 years. Comparing all patients preoperatively and those without subsequent hip failure at the time of follow-up, there was a reduction in pain. However, the range of motion was not improved.

Osteonecrosis of the femoral head often affects young active adults and leads to destruction of the hip joint and severe arthritis^2-5. Despite improvements in hip arthroplasty design and techniques, it is unlikely that prosthetic replacements will endure for a lifetime in these young patients.

Alternatively, various head-preserving procedures have been used to avert or delay the need for a total hip arthroplasty^6-11.

Precollapse femoral heads are associated with a better outcome than collapsed heads. Of the patients younger than 45 years in our previous study¹, 93.3% had successful results, whereas only 87.5% of the patients older than 45 years had successful results.

Our results suggest that vascularized greater trochanter bone flap transfer combined with autologous cancellous bone impaction is indicated for patients younger than 45 years who have no collapse or mild collapse (<4 mm) of the femoral head with integrity of the weight-bearing surface. The results were satisfactory, with an average Harris hip score of >80 points, regardless of the extent of the necrotic lesion. The procedure is not appropriate for patients with advanced stages of osteonecrosis of the femoral head.

Pitfalls & Challenges

• It may be difficult to completely remove the necrotic bone during surgery, especially for an ARCO stage-IIB or IIIB femoral head with larger lesions. For these cases, the core or central area of the necrotic lesion should be debrided. Thus, preoperative evaluation with CT or MRI scans is crucial for defining the anatomy of the necrotic lesion.

• After debridement of large necrotic femoral head lesions, insufficient bone implantation and impaction may result in femoral head collapse on postoperative weight-bearing.

• When a high-speed abrasive drill is used for debriding, care should be taken to avoid “cutting out” the subchondral bone and compromising the femoral head cartilage. This is more likely to happen in patients with a collapsed femoral head (ARCO stage III) when a subchondral fracture already exists.

• Compared with free vascularized fibular grafting, a vascularized greater trochanter bone-grafting procedure has the advantages of being less invasive, having a low donor-site morbidity, and not needing any microsurgical technique because there is no vascular anastomosis. However, the mechanical support for the femoral head is not as strong as the support that vascularized fibular grafting provides.

• Preoperative digital subtraction angiography can be used to evaluate the intraosseous blood supply of the femoral head and the condition of the LFCVs, which can help in the decision to use ascending or transverse vessels.