Greater trochanteric bone ap grafting with vascular pedicles for the treatment of femoral head osteonecrosis in patients with systemic lupus erythematosus: A retrospective study

Background: Osteonecrosis of the femoral head is a complication of systemic lupus erythematosus,that affect the patient's quality of life seriously.This article reviewed the radiographs of osteonecrosis of the femoral head in patients with systemic lupus erythematosus and assessed the effect of using the greater trochanteric bone ap grafting with vascular pedicles. Methods: We retrospectively reviewed 17 patients (26 hips) with systemic lupus erythematosus who underwent the greater trochanteric bone ap grafting with vascular pedicles for the treatment of osteonecrosis of the femoral head. According to Ficat and Arlet classication, 16 hips were in stage II; 10 hips were in stage III. All patients were followed up for a mean of 32 months (ranging 12~48 months) and were assessed clinically and radiologically according to Harris scoring. Results: No hips were treated with total hip arthroplasty in the follow-up. The mean HHS was improved from preoperative 69.1 points (ranging 52–83 points) to postoperative 89.4 points (ranging 56–100 points). At the latest follow-up, of 26 hips, radiographically 21 hips (80.77%) were improved, 3 hips (11.54%) were unchanged and just 2 hips (7.69%) were worse. Conclusion: The greater trochanteric bone ap grafting with vascular pedicles was successful in maintaining joint function and in delaying the need for joint replacement procedure.


Introduction
Systemic lupus erythematosus (SLE) is a diffuse connective tissue disease with multiple system damage mediated by autoimmune reactions. Osteonecrosis of the femoral head (ONFH) is one of the most serious complications of SLE (1). Its morbidity has been reported to be about 4%-30% with an overall average of 10%, which is higher than that of general populatio (1)(2)(3).The etiology of this disorder has not been clari ed, and no prophylaxis has been established to date. Although the pathogenesis remains unclear, involvement of high-dose corticosteroids therapy(4), immunosuppressive drug therapy(5), hypercoagulability (6), and lipid metabolism abnormality (7) has been suggested. ONFH seriously affects the quality of life of patients , which is an urgent medical problem to be solved.
Total hip arthroplasty (THA) is an effective method to treat ONFH (8), which can reduce patients' pain and improve the function of hip joint. Without early surgical intervention, total hip advanced lesions would appear, and eventually THA was unavoidable. However, SLE is more common in younger patients, premature THA will face many problems, such as prosthetic loosening, infection and repeated revision surgery (9,10). In addition, patients with SLE who take hormones for a long time often have other systemic diseases, which increase the risk of surgery and perioperative complications (9). These will have serious impact on the patient's physiology, psychology and economy, so total hip arthroplasty for younger patient populations need be paid very careful attention. Therefore, on the basis of improvement in symptoms, what kind of surgical methods to delay or even avoid arti cial joint replacement has become the focus in theapy research of ONFH. Current research methods include core decompression surgery, osteotomy and vascularized bone graft, the therapeutic effect of core decompression and osteotomy has been questioned for the patients whose cartilage damaged and collapsed (11,12). It had reported that vascularized greater trochanter bone ap transplantation was effective for the treatment of ONFH, and the femoral head preservation rate was 88.2% (13) Rheumatology Association criteria (14). ONFH was identi ed by one or more of the following imaging techniques: plain X-ray, computsd tomography and MRI. According to the Ficat and Arlet classi cation(15),16 hips were in stage II (61.5%); 10 hips were in stage III (38.5%). The diagnosis of osteonecrosis was con rmed in all cases by a histological examination of the subchondral bone that was obtained from a core biopsy of the femoral head during the surgery.

Surgical procedure
After the patient is anesthetized, they were placed in the supine position with the ilium elevated to 60°. A skin incision was made 4 cm distal to the iliac crest down to the top of greater trochanter, and then extend vertically down along the anterior margin of the trochanter. After we identi ng the transverse branch of the lateral femoral circum ex vessel, we separated these vessels to where they entered the greater trochanter. We harvested a vascular graft bone ap about 3x2cm from the anterolateral side of the greater trochanter. Then, we harvested a volume of 1-2 cm 3 of cancellous bone from the greater trochanter area.The hip capsule was incised in a T shape to expose the femoral head and neck. We made an approximately 2x2cm bone window at the femoral head-neck junction using an osteotome. According to the imaging evaluation and the judgment of the surgeon,we determined the range of femoral head necrosis.We used the high-speed drill and curette spatula to remove the necrotic bone tissue in the femoral head, until the necrotic tissue is removed compeletly and fresh blood ows out. The vascularized bone ap was implanted into the femoral head lesion area after the necrotic bone was removed, and the cancellous bone was lled in insu cient places. The bone ap and the lled cancellous bone were properly tamped to restore the shape of the collapsed femoral head.We required bleeding from the cancellous surface of the greater trochanter graft as an indication of vessel patency.

Clinical evaluation
Clinical follow-up is performed every 3 months for 1 year and annually thereafter.The mean length of follow-up was 32 months (ranging 12 to 48 months) in our hospital. Before the procedure and at each follow-up, patients were evaluated using the Harris Hip Score (HHS) (16).The HHS is an objective index of hip joint function that quanti es the four categories of (1) pain, (2)

Clinical Results
The Surgical procedure took 50 to 90 minutes to complete with the mean of 65 minutes.Mean perioperative blood loss was 320 mL (range 220-510 mL).All patients received perioperative prophylactic antibiotics until after removal of the drains.There were no intraoperative complications. Fat necrosis of incision occurred in one patient postoperatively and the incision healed untill 3 weeks after debridement.
There were no other complications, such as infection, hematoma and deep vascular thrombosis, during the period of follow-up.

Harris hip scores
At last follow-up,The mean HHS was improved from preoperative 69.1 points (ranging 52-83 points) to postoperative 89.4 points (ranging 56-100 points) (The overall average increase in HHSs is shown in Figure 1). Core decompression provides pain relief,especially for patients with earlier stages of avascular necrosis (22).There is evidence that core decompression is an effective intervention in lupus patients with Ficat stage I and II.Several studies report , failure of core decompression and progression of osteonecrosis in lupus patients, especially in patients with Ficat stage III(23). Maniwa (24) have evaluated the results of core decompression for osteonecrosis of the hip in patients with SLE. The report suggest that patients with avascular necrosis of the femoral head and lupus do not respond as well as nolupus patiens treated with core decompression.
In 1978, Sugioka(25) rst introduced rotary osteotomy through greater trochanter of femur to treat ONFH which was intertrochanteric osteotomy of the femoral head necrosis rotation. The principle is the upper part of the front of the femoral head necrosis is transferred to the non-load-bearing parts, in order to prevent progressive collapse of the articular surface of the femoral head, and correct head and acetabulum mismatch caused by subluxation occured after the collapse of the articular surface of the femoral head. Then a variety of improved surgical procedures used in clinical, there is a big difference in the reported results. Although it is considered this kind of surgical mothod can prevent the collapse of the new weight-bearing area, but increased the incidence of instability and the corresponding joint osteoarthritis. Due to the high incidence of this surgical complication and followed by deformity of the proximal femur, the clinical application is limited. Greater trochanter of femur mainly comprised by spongy bone, have rich blood supply, bone ap have large range blood supply, the blood supply in the affected areas can be improved effectively after transplantation, the rebuilding process of the blood supply can be shortened.
The use of the free bular ap for the treatment of ONFH was initiated in an effort to enhance revascularization and arrest the progression of the necrosis.Soucacos (26) reported using free vascularized bular grafting for osteonecrosis of the femoral head in 184 hips, a mean follow-up of 11 years, only 7.6% of patients requiring total hip arthroplasty, and 62% patients without progression.However, the procedure of free bular ap transfer is technical demanding and time consuming.Moreover, complications associated with the use of bular ap, such as donor-site pain, peroneal nerve neuropathy and fracture of the femoral neck, have also been reported (27,28).
The greater trochanter bony structure with cancellous bone, peripheral rich blood supply, transplantation can effectively improve the blood supply, reduce blood supply reconstruction process.The thin cortical bone is very similar to head of femur, is ideal selected area to treat ONFH; and is able to improve the mechanical properties of necrosis of the femoral head effectively. After removing the necrotic bone completely, the transferred greater trochanter and the remaining part of femoral metastases t closely to promote fracture healing process; greater trochanter and femoral trabecular bone trabecular have same nature, which restored the continuity of cancellous bone trabecular, rebuilding the supporting role of trabecular bone of the femoral head, to recovey femoral neck bearing bracket, can be adapted to load normal joint activities; meanwhile as the cystic degeneration repair and new bone reconstruct, the femoral head restoring the force area, so that the stress beared by unit trabecular bone area reduced, the mechanical properties of the femoral head strengthened, preventing the collapse effectively. In addition, the vascularized bone ap can reconstruct a new blood supply system, accelerate the repair and rebuilding of bone necrosis, thereby restoring the biological characteristics of the femoral head necrosis.
And by mechanics, we proved the cut of the greater trochanter does not damage the mechanical properties and structure of the proximal femur trochanter major stress conductive zones, thus from a mechanical point of view, the selection of bone ap from the greater trochanter is safe and feasible. The bone ap transplantation located in front of the femoral neck, this area is a region of low stress distribution, can reduce the impact on the mechanical characteristics of the proximal femur. This provides bone ap entering the channel and select speci c operative incision from femur head and neck in greater trochanter vascularized bone grafting a strong theoretical basis, but also proves the safety of this surgical technique, and fewer complications.
On the use of vascularized the greater trochanteric bone ap graft treating 26 hips with secondary ONFH caused by SLE, by an average of 32 months of follow-up,medium-term clinical results were satisfactory,the excellent and good rate was 88.5% , this surgery can slow down or even stop the progress of ONFH. During follow-up, femoral head necrosis increasing with the progression of stage in two patients, DSA angiography showed: blood lling poorly in vascularized bone or no contrast agent lling the femoral head, maybe caused by the twist or spasm of the vascular pedicle, or constriction from surrounding tissue swelling, until to the last follow-up, both patients have no other further treatment requirements in addition to functional rehabilitation treatment.
But we are also aware of some limitations of our study. First, we had no control group treated with alternative joint-preserving procedures. Second, the length of follow-up is only 32 monthes. Longer term outcome analysis will be necessary to prove the longevity of the procedure. Third, the current study has only 26 hips; therefore, signi cant statistical conclusions are more di cult to make.

Conclusion
The effects of the greater trochanteric bone ap in patients with lupus on plain x-ray changes and HHSs demonstrate the bene ts of this technique. The greater trochanteric graft ap with pedicles are easy to perform and could be indicated in young patients with Ficat and Arlet stage II to III disease. Its could provide the necrotic femoral head with su cient blood supply and prevention of femoral head collapse. We declar that all procedures were approved by an Institutional Ethics Review Committee of Nanyang Orthopaedic Hospital, and obtained the consent of the participants.
Conception and design of the research:Qiang Yang; Acquisition, analysis and interpretation of data: Jixue Zhou and Lei Li; Statistical analysis: Zhaopeng Guo and Xiaolei Tian; Drafting the manuscript: Qiang Yang; Manuscript revision for important intellectual content: Qiang Yang. All authors have read and approved the manuscript.  Figure 1 The effect of the greater trochanteric bone ap with vascular pedicles grafting on HHS is shown.

Figure 2
The effect of the greater trochanteric bone ap with vascular pedicles grafting on Harris hip score (HHS) in stage II and III is shown.