This study was approved by the Ethics Committee of our hospital (No: HK2019-01-04) and the written informed consent was obtained from all subjects and/or their legal guardian. A total of 103 patients (149 hips) underwent the SDBS for ONFH in a single centre between October 2016 and October 2020. Seven patients (10 hips) were excluded because they were lost to follow-up. The final study cohort comprised 139 hips in 96 patients (79 males and 17 females; mean age 37.53±10.31 years, range 14–58 years; mean body mass index 25.15±3.63 kg/m2). The ONFH was bilateral in 43 patients and unilateral in 53 patients (29 left hips, 24 right hips). The ONFH was caused by prolonged excessive alcohol intake in 32 patients (44 hips), glucocorticoid administration in 42 patients (66 hips), trauma in nine patients (nine hips), and had no clear aetiology in 13 patients (20 hips). All patients were diagnosed in accordance with Chinese guidelines for the diagnosis and treatment of ONFH [7]. Osteonecrosis was classified as Association Research Circulation Osseous (ARCO) stage II in 63 hips, and ARCO stage III in 76 hips. Based on the Japanese Osteonecrosis Investigation Committee (JIC) classification system, the ONFH was classified as type B in 21 hips, type C1 in 54 hips, and type C2 in 64 hips. Characteristics of the patients and hips are listed in Table 1.
Table 1
Characteristics of the patients and hips
|
Patients
|
Hips
|
Male
|
79
|
-
|
Female
|
17
|
-
|
Age(years)
|
37.53 ± 10.31
|
-
|
BMI
|
25.15±3.63
|
-
|
Bilateral
|
43
|
86
|
unilateral
|
53
|
53
|
Alcohol abuse
|
32
|
44
|
Corticosteroid application
|
42
|
66
|
Post-traumatic
|
9
|
9
|
Idiopathic
|
13
|
20
|
ARCOII
|
-
|
63
|
ARCOIII
|
-
|
76
|
JIC B
|
-
|
21
|
JIC C1
|
-
|
54
|
JIC C2
|
-
|
64
|
Surgical technique
All patients received epidural anaesthesia and were fixed on the traction bed. The operation area was routinely disinfected and sterilely draped. After selecting the position of the entrance point, a 2-cm skin incision was made. The first guidewire was drilled into the region below and inside the area of femoral head necrosis (Fig.1.A). A 10-mm bit was then reamed along the guidewire to 3 mm below the cartilage(Fig.1.B). Fresh-frozen allograft particles (7.5 mg) (Shanxi AoRui Biological Material Co., Ltd., Taiyuan, China) were transplanted into the channel from the necrotic area to the normal area (Fig.1.C). A second guidewire was then introduced through the same entrance point into the outer, top necrotic area (Fig.1.D), and the 10-mm bit was again reamed along the guidewire to 3 mm below the cartilage (Fig.1.E). Fresh-frozen allograft particles (2.5 mg) were transplanted into the second channel (Fig.1.F). After reaming the proximal femur (Fig.1.G), a suitable nano – hydroxyapatite/polyamide 66 (n-HA/PA66) support rod (Sichuan National Nanotechnology Co., Ltd., Chengdu, China) was inserted into the second channel (Fig.1.H). Finally, the wound was irrigated and sutured.
Postoperative care and follow-up
Postoperatively, cefazolin sodium pentahydrate for injection (1 g) was administered once to prevent infection. Flurbiprofen axetil injection (100 mg twice daily) was routinely given as analgesia for 3 days. All patients participated in a rehabilitation and training program after surgery. After recovery from anaesthesia, the patients began ankle dorsiflexion exercises to prevent deep vein thrombosis without the need for medication. Patients began walking with two crutches from postoperative day 1 and were restricted to partial weight bearing for 6 months. From 6 months postoperatively, patients were permitted to exercise and walk intermittently without crutches. By 1 year postoperatively, patients were fully weight bearing. Postoperative follow-up was carried out at 3, 6, and 12 months postoperatively, and annually thereafter.
Efficacy assessment
The Harris hip score (HHS) was used to assess the hip function as excellent (HHS ≥ 90), good (HHS 80–89), fair (HHS 70–79), or poor (HHS < 70). At each follow-up visit, all patients underwent CT and radiography (anteroposterior and frog position) of the hip. CT was used to detect subchondral fracture of the femoral head, while radiographs were used to check the depth of the femoral head collapse. Treatment failure was defined as the performance of hip replacement. Other assessed variables included the operation time, intraoperative blood loss volume, and postoperative complications.
Statistical analysis
SPSS version 22.0 (IBM Corp.; Armonk, NY, USA) was used for statistical analysis. Data are expressed as means ± standard deviations. The paired t test and Wilcoxon test were used to compare the preoperative HHS with the HHS at final follow-up. Rate comparisons were performed using the χ2 test. Single risk factor analysis for surgical failure was performed using the Kaplan-Meier method. P < 0.05 was considered to indicate statistical significance.