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Percutaneous drilling, lightbulb techniques can postpone THA
Osteonecrosis of the femoral head is a devastating disease that results in hip necrosis from impaired blood flow. Over their lifetime, patients will most likely require multiple surgeries; thus, when possible, we aim to preserve the joint and try to postpone hip arthroplasty.
At our institution, we use the following four radiographic factors for the determination of whether a patient is a candidate for one of the joint preserving procedures we describe in this article: lesion size; pre- or post-collapse state; head depression and acetabular involvement. We typically treat small- to medium-sized pre-collapse lesions with core decompression through a percutaneous technique, while larger and/or early post-collapse lesions are frequently treated with non-vascularized bone grafting through the femoral head-neck junction — the “lightbulb” technique. However, when we encounter a patient who has progressed to post-collapse state with greater than 2 mm head depression and/or acetabular involvement, total hip arthroplasty is necessary.
Core decompression
For patients who have a small- to medium-sized pre-collapse lesion, we believe core decompression might be a good option. The rationale behind this technique is to relieve the intraosseous pressure thought to be causing vascular occlusion to the femoral head.
The traditional technique of core decompression utilizes an 8-mm to 10-mm trephine to relieve intraosseous pressure in the femoral head. However at our institution, a type of core decompression is performed with a percutaneous technique with a 1/8-inch Steinmann pin. Depending on the size of the lesion, either a single pass or multiple passes using the same starting point can be utilized. Small-sized lesions are typically treated with one to two passes, whereas larger lesions are treated with two to three passes in order to adequately decompress the femoral head.
All patients are administered routine preoperative prophylactic antibiotics prior to the start of the procedure. The patient is brought back to the operating room and placed supine on a radiolucent table. Care must be taken to position the patient so that adequate, high-quality fluoroscopic images can be obtained that are free from metal artifact obstruction. The procedure is typically done under sedation, although general anesthesia also can be used if necessary. A bump is placed under the affected hip to compensate for native femoral anteversion. Once the patient is adequately sedated, the fluoroscopy unit is brought into the field to ensure that adequate images of the hip in the anteroposterior and lateral planes can be obtained as previously described. The affected hip is prepped and draped in the usual sterile fashion. We typically have an assistant slightly internally rotate the hip at the end of the operating room table to help allow for visualization of the femoral neck and face.
Figure 1. Core decompression through the percutaneous drilling technique is shown (a) with fluoroscopy of the drilling starting point at the metaphyseal flare of the lateral cortex, above the superior level of the lesser trochanter. AP and lateral radiographs of the femur with Steinmann pin in the osteonecrotic lesion for the femoral head can be seen (b and c).
Images:Cherian JJ
Under fluoroscopic guidance, a percutaneous starting point is made just inferior to the lateral cortical flare at the metaphyseal-diaphyseal junction in the center of the proximal femur (Figure 1a). Care must be taken to ensure the starting point is made at or above the proximal level of the lesser trochanter to minimize the risk of creating a subtrochanteric stress riser. A 1/8-inch Steinmann pin is then advanced through the lateral proximal femoral cortex and guided into the necrotic segment of the femoral head. The entry site at the skin is copiously irrigated with sterile saline during pin advancement to avoid thermal skin necrosis from the pin. Judicious use of fluoroscopy in orthogonal planes is utilized throughout the procedure to ensure the proper trajectory of the pin. While drilling, it is common for the surgeon to encounter areas of sclerotic bone in the osteonecrotic lesion. It is important to avoid applying too much pressure while drilling through the dense bone and penetrating the femoral head articular surface. Larger lesions can be treated with multiple passes through the same starting hole in the proximal lateral cortex using the same technique.
Once adequate penetration and decompression of the lesion is confirmed under fluoroscopic guidance on both AP and frog-leg lateral views (Figures 1b and 1c), the Steinmann pin is removed and the wound is irrigated. Firm pressure is held over the percutaneous hole until hemostasis is achieved. The wound is covered with a sterile dressing or, on rare occasion, a nonabsorbable monofilament suture is used.
Postoperatively, patients are discharged home and placed on 50% partial weight-bearing precautions with crutches for 4 weeks to 6 weeks. After that, the patients progress to full weight-bearing and are encouraged to perform simple hip strengthening exercises every other day. Patients are instructed to avoid high impact activities for the first year following this procedure.
Lightbulb procedure
We reserve non-vascularized bone grafting through the “lightbulb” technique for patients with large or early post-collapse lesions. This technique is thought to remove the necrotic area of involvement, and provide new biomechanical structural support while there is new bone growth.
Similar to core decompression, patients are administered routine preoperative prophylactic antibiotics. The patient is brought into the operating room and preferably given a spinal anesthetic. On occasion, general anesthesia is required if a contraindication to spinal anesthesia exists. The patient is then positioned in the lateral decubitus position on the operating room table with the affected side up. At our institution, we prefer to use padded hip positioners, one located anteriorly abutting the anterior superior iliac spine (ASIS) and one posteriorly over the sacrum. The surgeon must ensure that the operative extremity is able to flex to at least 90° in order to aid with surgical exposure and facilitate dislocation, if necessary.
All bony prominences are well-padded prior to the start of the procedure. We prefer to place a pneumatic compression device on the contralateral lower extremity throughout the duration of the procedure. The operative extremity is then prepped and draped in the usual aseptic manner. We prefer to use anterolateral approach to the hip for surgical exposure, although any approach can be used. Prior to the skin incision, anatomic landmarks including the ASIS, tip of the greater trochanter, and anterior and posterior borders of the proximal femur are marked out with a sterile marking pen. A 10-cm to 12-cm skin incision centered over the tip of the greater trochanter is then made in line with the lateral femur.
Figure 2. Cutting of 2x2 cortical window at the femoral head neck junction is seen.
The subcutaneous tissue is dissected down to the level of the fascia lata. The fascia lata is then incised in line with the skin incision in between the anterior and posterior borders of the proximal femur to expose the gluteus medius and vastus lateralis insertion onto the vastus ridge. A proximal sleeve is created by incising the anterior 40% of the gluteus medius muscle in line with its fibers to the level of the greater trochanter. The abductor tendon consisting of the gluteus medius and minimus muscle is then lifted from the greater trochanter and peeled off the anterior capsule ensuring that an adequate cuff of abductor tendon is created in order to facilitate later repair.
Figure 3. The 2x2 cortical window is removed.
Figure 4. Light in femoral head after removal of osteonecrotic region for inspection is shown.
At this point, an anterior capsulectomy is performed to create superior and inferior flaps. Care must be taken not to damage or incise the labrum while performing the capsulectomy. We inspect the femoral head through gentle longitudinal traction, adduction, and external rotation, but we do not dislocate the hip. Once the osteonecrotic lesion is identified, an approximate 2x2 cm cortical window is made in the femoral head neck junction lesion using a micro-sagittal saw and 0.25-inch osteotome (Figure 2). With the aid of curved curettes and a 6-mm round-tipped burr, the necrotic segment of the lesion is debrided until viable bone is reached (bleeding bone) (Figure 3). To assess the sufficiency of debridement, an arthroscope or light on a handle can be placed through the cortical window so that the area can be directly visualized (Figure 4). The defect is filled and gently packed using cortical cancellous bone graft with a bone tamp and mallet. We prefer to use a bone morphogenetic protein-enhanced allograft. Locally obtained bone marrow from the greater trochanter area can also be utilized. The cortical window is placed back into its original position and secured with three or four diverging 2-mm bioabsorbable pins (Figure 5). To ensure that the pins are flush with the articular surface, the ends can are sodered using electrocautery.
Figure 5. The cortical window is secured back into femoral head neck junction with two bioabsorbable pins.
Wound closure commences with repair of the abductor complex. The gluteus minimus tendon is separated from the gluteus medius with a pair of curved Mayo scissors. Using 5-0 Ethibond, two running Krackow-style locking stitches are placed through the gluteus minimus tendon and reattached to its insertion on the greater trochanter through bony tunnels. The gluteus medius tendon is then repaired back to its insertion on the greater trochanter. The fascia lata, subcutaneous tissue and skin are closed in layers using absorbable suture.
The cortical window is secured back into femoral head neck junction with two bioabsorbable pinsPostoperatively patients receive both mechanical and pharmacological prophylaxis. Patients are mobilized with physical therapy the same day with toe-touch weight-bearing precautions on the operative extremity, which is continued for 6 weeks with the use of crutches or a walker. The patient’s weight-bearing status is progressed to 50% partial weight-bearing after the first 6 weeks and outpatient physical therapy commences. Patients are progressed to full weight-bearing at approximately 12 weeks postoperatively. Similar to our postoperative protocol after a core decompression, patients are encouraged to continue performing maintenance hip abductor muscle strengthening exercises and avoid high-impact loading exercises for 1-year postoperatively.
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Disclosures: Mont receives royalties from Stryker and Wright Medical Technology Inc.; is a paid consultant for Biocomposites, DJ Orthopedics, Janssen, Joint Active Systems, Medtronic, Sage Products Inc., Stryker, TissueGene and Wright Medical Technology Inc.; has received research support from DJ Orthopedics; Joint Active System; National Institutes of Health (NIAMS & NICHD), Sage Products Inc., Stryker, Tissue Gene and Wright Medical Technology Inc. Cherian and Wu have no relevant financial disclosures.
