To evaluate the medium-long term clinical outcomes of osteonecrosis of the femoral head (ONFH) patients treated with decompression of the femoral head, allograft, and porous tantalum rod implantation (porous tantalum rod implantation for short), and whether postoperative failure would affect the clinical outcomes of subsequent total hip arthroplasty (THA).

A total of 38 patients (40 hips) with non traumati ONFH admitted to Hip Research Center, Guangzhou University of Chinese Medicine from January 2008 and December 2011 were selected. All affected hips were implanted with porous tantalum rod implantation. Intramedullary decompression of the femoral head was performed under fluoroscopy to remove part of the dead bone and allograft bone. Finally, a porous tantalum rod was inserted. Patients who underwent THA after the failure of porous tantalum rod implantation were assigned to the second surgery group (n=12). In the second surgery group, femoral neck osteotomy was performed and tantalum rod was truncated and implanted, and the proximal residual end was removed at the same time. Fifty-seven patients who had no previous history of hip preservaton surgery and underwent primary THA in non traumatic ONFH [Association Research Circulation Osseous Committee (ARCO) Ⅳ] were included as the control group according to the principle that 1 patient in the second surgery group was matched with 4-6 patients of similar gender and age (±15 years old). Primary THA was performed in the control group. The hip preservation rates of patients at 24, 60 and 96 months after porous tantalum rod implantation were analyzed and compared in the whole population, different ARCO stages and different Japanese Osteonecrosis Investigation Committee (JIC) ONFH patients. The hip preservation rates of patients with different radiographically progressive of ARCO stages and different JIC types of ONFH were compared at the last follow-up. Harris hip scores at 24, 60, and 96 months after porous tantalum rod implantation were evaluated in the population, different ARCO stages, and different JIC types of ONFH. Harris hip scores of the second surgery group and the control group were compared before and 60 months after surgery. Anteroposterial and frog radiographs, as well as MRI and CT scan data were collected from all patients. The progression of hip collapse was assessed by the method of modified Nish Ⅱ and the radiographic progression rate was calculated at the last follow-up. Data were processed with Wilcoxon signed-rank test, Mann Whitney U test and chi-square test.

The mean follow-up time was (117.1±4.1) months after porous tantalum rod implantation. and the hip preservation rates at 24, 60 and 96 months after surgery were 92.5%(37/40), 82.5%(33/40) and 75%(30/40), respectively. At 24, 60 months after surgery, there were no statistically significant differences in hip preservation rates between ARCO Ⅱ patients and ARCO Ⅲ patients (χ²=0.001, 1.396; P=1.000, 0.457). At 96 months after surgery, the hip preservation rate of ARCO Ⅱ patients [89.6% (23/27)] was higher than that of ARCO Ⅲ patients [53.8% (7/13)], the difference was statistically significant (χ²=4.596, P=0.042). At 24 and 60 months after surgery, there were no statistically significant differences in hip preservation rates between JIC C1 patients and JIC C2 patients (χ²=0.041, 0.145; P=0.839, 0.703). At 96 months after surgery, the hip preservation rate of JIC C1 patients [83.3% (25/30)] was higher than that of JIC C2 patients [50.0% (5/10)], the difference was statistically significant (χ²=4.444, P=0.035). Before receiving porous tantalum rod implantation, the Harris hip score of ONFH patients was 59 (55, 61) points, and the Harris hip scores of ONFH patients were 72(61, 80), 89 (82, 91), and 94(91, 96) points at 24, 60, and 96 months after surgery, respectively, the difference was statistically significant (Z=4.627, P<0.05). There were no statistically significant differences in Harris hip scores between ARCO Ⅱ patients and ARCO Ⅲ patients before surgery, 60 and 96 months after surgery (Z=123.5, 180.0, 101.0; P=0.114, 0.994, 0.871). At 24 months after surgery, there were no statistically significant differences in Harris hip scores between between ARCO Ⅱ patients and ARCO Ⅲ patients (Z=100.0, P=0.043). Before and 96 months after surgery, there were no statistically significant differences in Harris hip scores between JIC C1 patients and JIC C2 patients (Z=164.0, 90.0; P=0.279, 0.355). At 24 and 60 months after surgery, there were statistically significant differences in Harris hip score between JIC C1 patients and JIC C2 patients (Z=96.5, 93.0, P=0.042, 0.038). The overall radiographic progression rate at the last follow-up was 55.0%(22/40). The imaging progression rate of ARCO Ⅱ patients was 48.1%(13/27), compared with ARCO Ⅲ patients [69.2%(9/13)], there was no statistically significant difference (χ²=1.255, P=0.391). The imaging progression rate of JIC C1 patients was 46.7% (14/30), compared with JIC C2 patients [80%(8/10)], there was no statistically significant difference (χ²=1.835, P=0.086). There was statistically significant difference in hip preservation rates between ARCO Ⅲ patients with radiographic progression[11.1%(1/9)] and ARCO Ⅱ patients with radiographic progression[76.9% (10/13)](χ²=3.035, P=0.024). The hip preservation rate of JIC C2 patients with radiographic progression [12.5% (1/8)] was significantly different from that of JIC C1 patients with radiographic progression [71.4% (10/14)](χ²=2.659, P=0.009). There were statistically significant differences in Harris hip scores in the second surgery group and the control group before THA and 60 months after THA (Z=6.511, 7.471; P<0.05). At 60 months after surgery, the Harris hip score of the second surgery group and the control group was 88 (85, 93) points and 94 (92, 96), respectively, there was no statistically significant difference (Z=0.044, P=0.090).

In the medium-long term follow-up, porous tantalum rod implantation in the treatment of ONFH has a high hip preservation rate in ARCO Ⅱ and JIC C1 patients, while the effect of ARCO Ⅲ or JIC C2 patients is not so good. The key to the application of this technology is to select the appropriate patients. Patients with advanced ONFH who underwent THA and patients who underwent THA after porous tantalum rod implantation failed has similar clinical outcomes.