Short Term Efficacy Evaluation And Analysis Of The Treatment Of Early-stage Osteonecrosis Of The Femoral Head With Tantalum Rod

BackgroundOsteonecrosis of the femoral head (ONFH) is a common debilitating hip disease, preserving their own femoral head (preserving hip joint) is the first choice for young patients. Early stage of ONFH is most valuable stage of treating and preserving the hip joint. Reducing the Stress/Strength Ratio (SSR) is effective in early ONFH. One of the typical surgical operations of treating and preserving hip joint is fibular graft. However, none of the procedures has been widely accepted so far.In view of the shortcomings of fibular graft, researchers have been seeking to find alternative materials for fibula, which can structurally support the subchondral plate of collapsing femoral head and avoid shortcomings caused by fibula transplantation. Therefore, The Trabecular Metal Osteonecrosis Intervention Implant (TMONII, referred to as tantalum rod) came into being. Tantalum rod has high volume pore structures, low elastic modulus and good biocompatibility, all of these features make the TMONII good structural materials. Its design philosophy is to provide biomechanical support for the subchondral plate, reducing the stress of bone around, as so to prevent collapse and provide revascularization approach and biological repair conditions in necrosis regions.Current domestic and abroad reports show the satisfactory results of postoperative using TMONII treating ONFH. Abroad Follow-up results showed that the survival rate of femoral head surgery after 4-6 years is about 70%, while domestic data indicates the survival rate of femoral head surgery after 1-3 years is over 80%. Our department's follow-ups showed that the survival rate of femoral head surgery after 24 months is 77.78%, which didn't show an overall better curative effect than fibula grafting although TMONII has a better biological compatibility and material mechanics properties. Consequently, the factor affecting the survival rate of impanation of TMONII and failure of TMONII operation should be greatly considered in order to standardize Surgical indications, modify operative techniques and finally improve the TMONII operation curative effect.MethodsFollow up visit patients with ONFH admitted in our in-patient department from June 2008 to October 2010.1 Preoperative curative effect indicators1.1 General conditions:patient's name, age, gender, hospital number, image number, side of operation with tantalum rod, associated basic systemic diseases, etiology, whether to continue using hormones.1.2 Preoperative indicators1.2.1 Indicators of hip function:Harris hip score1.2.2 Image Index:ARCO stage, modified anteroposterior classification based on mid-coronal T1-weighted MRI scans and the lateral classification based on mid -sagittal T,-weighted MRI scans, subchondral bone fracture (fracture of the location and degree of collapse) shown in CT, bone marrow edema grade shown in MRI and modified index of necrotic extent.2 Postoperative curative effect indicators2.1 Operation conditions:date of operation, blood loss and intraoperative bone grafting.2.2 Follow-up:The last follow up date and the last follow-up time from surgery.2.3 Distance between the Tantalum rod proximal end and the subchondral bone of femoral head.2.4 Degree of subchondral bone collapse.2.5 Indicators of hip joint function:Harris hip score.2.6 Progress in X-ray.3 Total clinical curative effect score= Harris hip score×60%+X-ray progress score×40%.Efficacy Evaluation Criteria:excellent≥80 points, good 75 to 79 points, 60 to 74 points, and poor<60 points.4 Team list of medical records and statistical MethodsAll the data were put into the CRF form. The relevant information or data entry queue Social Sciences statistical package SPSS 16.0 for statistical analysis software, and all the statistical tests, test standards are used bilateralα<0.05. Homogeneity of variance test of bilateralα<0.10, was considered homogeneity of variance, P<0.05 was considered statistically significant, P<0.01 as significant difference. General information was analyzed by descriptive analysis, measurement data was analyzed by independent samples T test and analysis of variance. If heterogeneity of variance happens, rank test was applied. Count data was analyzed by Chi square test, ranked data was analyzed by rank sum test, survival rate was analyzed by Kaplan-Meier method, and test model was compared of stratification factors using log-rank test, which applies the femoral head collapse>4mm as the endpoint. Cox proportional hazard model using multivariate analysis to determine the image caused by the failure of prognostic factors, all the statistics are reviewed by professional statisticians.Results1 General conditions58 cases of 63 hip-preserving surgeries with tantalum rod were done from June 2008 to October 2010. Gender:42 males of 45 hips,16 females of 18 hips. Lateral side:unilateral necrosis in 5 cases,53 cases of bilateral necrosis. Etiology:33 hips of steroid,22 hips of alcohol,7 hips of idiopathic,1 hip of trauma. ARCO stage:1 case of 1 hip (1.6%) at stageⅠ,57 hips of 52 patients (90.5%) at stageⅡ,5 cases of 5 hips (7.9%) at stageⅢ; Age:37.43±10.3 years (17 years old -61 years old); 30 hips of 63 hips (47.6%) had pain symptoms, pain time:2.98±2.81 months; with basic systemic diseases in 12 cases of 13 hips.2 Situations of follow upall patients were followed up, beginning at the time of tantalum rod implant and ending at the time of collapse more than 4mm(failure event), failure event no longer included in the follow-up time, mean follow up time:16.03±8.16 months (up to 34 months, minimum 6 months).3 Treatment5 cases in 53 cases with bilateral necrosis received bilateral tantalum rod implant; another 48 cases received unilateral tantalum rod implant with other treatments for the other hip, which including Pure traditional Chinese medicine (8 hips), total hip replacement (8 hips), Modified core decompression combined with non-vascularized fibula graft (17 hips), debridement plus grafting with vascularized bone grafts with femoral greater trochanter (11 hips), and simple debridement grafting (4 hips).20 hips among the 63 hips of tantalum rod implant used autologous or allogeneic cancellous bone grafting. Compound Sheng Mai Cheng Gu Pills were dialectically used after operation.4 Efficacy evaluation4.1 Total Efficacy scoreThe last follow-up efficacy score:82.97±25.35 (19.8-100), which were excellent in 40 hips accounted for 63.5%,10 hips of medium accounted for 15.9% and poor in 13 hips accounted for 20.6%.4.2 Harris hip scoreMost patients'hip pain symptoms have partially relived after surgeries with functional recovery satisfaction, the Harris hip scores (excluding failure cases) were significantly different between pre and post operation (ΔP<0.05). In addition, after 6 months,12 months and final follow up were significantly improved (*P<0.01).4.3 Progressions in ImagingMost patients X-ray findings were stable.18 patients (19 hips) showed the X-ray of progression, including 13 cases of steroid, idiopathic in 4 cases and 1 case of alcohol; the average X-ray time to progression was 14.4months (6 to 28 months); the performance of the crescent sign, Fissure sign, step sign, cystic degeneration and collapse of articular surface; ARCO stages and distributions of imaging progression:1 hip of stage I has no progression, 8 hips among 48 hips of stageⅡhas progression with 7 hips failed,9 hips among 12 hips of pseudo-stageⅡhas progression with 5 hips failed; 2 hips among 5 hips of stageⅢhas progression with 2 hips failed; Imaging grading and distribution of modified index of necrotic extent:2 hips among 17 hips of index below 33 group has progression but 1 failed,3 hips among 25 hips of index between 34 to 66 group has progression but 1 failed; 14 hips among 21 hips of index over 66 group has progression but 12 failed; 14 cases of vertical collapse of the hip is more than 4mm, the average failure time was 14.6 months (6 to 28 months), of which 5 were 6 hips were transferred to total hip replacement.6 hips of 5 cases ARCO stage in accordance with the existing methods are preoperativeⅡstage, but the CT scan confirmed that 3 hips before surgery in 2 patients had subchondral cortical plate microfracture; According to MRI T1-weighted images, these 6 hips are large lesion of necrosis (modified index of necrotic extent greater than 67); classified according to etiology of steroid necrosis in 3 cases,1 case of alcohol necrosis, and 1 case of idiopathic necrosis. Observation of the femoral head gross specimen of hip cut found:separation of cartilage and subchondral bone, subchondral cortical plate fracture, articular surface collapse; necrosis without repair phenomenon, necrosis area tantalum rod no new bone formation and vascular ingrowths, located in the necrotic Tantalum rod region separating the front and sequestrum and there is an obvious mechanical unstable layer; Tantalum rod in live bone area has new bone on-grow, but no significant in-grow phenomenon.4.4 Survival rates of femoral headThere is no failure cases 3 months after surgery,2 failed 6 months after the surgery,8 failed 12 months after the surgery,13 failed 24 months after the surgery,14 failed over 24 months after the surgery. When follow-up is 24 months, clinical ending is set by necrosis progress collapse more than 4mm, and then the survival rate was 77.78%.4.5 ComplicationsTantalum rod itself is not associated with complications.4.6 Traditional Chinese differentiations17 cases of this group were Stagnation of Qi and blood stasis, with the rate of 29.31%. No single type of wind-cold-dampness, Phlegm-dampness, Weak Qi and Blood, and Liver and kidney deficiency was found during the study. Related integrative types are all based on type of Stagnation of Qi and blood stasis, and the integrative type of Phlegm-dampness takes up 31.03%, Liver and kidney deficiency type of 36.21% and the Weak Qi and Blood type of 3.45%.5 The statistical results of relevant factors prognosis5.1 Kaplan-Meier survival curves of relevant factors prognosisWorse prognosis presented in the group of modified index of necrotic extent≥67 compared with modified index of necrotic extent≤33 and modified index of necrotic extent between 34-66. Prognosis of MRI modified anteroposterior Classification type C2 is worse than C1 type. There was no significant difference between none-subchondral bone fracture and subchondral bone fracture. Group of tantalum rod proximal distance from the articular surface less than 5mm is better than that more than 5mm, but no statistically significant. There was no significant difference between the bone graft group and no bone graft group. TCM syndrome type analysis shows that Qi stagnation and blood stasis type has better prognosis than Deficiency of liver and kidney type and phlegm dampness type all survive.5.2 Prognostic factors out of the last follow-up effects and imaging scoresResults show that large lesions of necrosis group has worse performance in efficacy scores and imaging scores than medium and small lesions of necrosis. There was no significant difference between medium and small lesions of necrosis group in terms of the efficacy scores and imaging scores. Tantalum rod proximal distance from the articular surface less than 5mm group has a better performance in imaging scores compared with that more than 5mm group, and the latter shows significant difference.5.3 Survival rate associated with preoperative femoral head multivariate Cox proportional risks model analysisThe results show:necrosis extent,subchondral bone fracture,Distance between the tantalum rod proximal end and the subchondral bone of femoral head,modified anteroposterior classification are relevant risk factors associated with efficacy, and necrosis extent is the core risk factor affecting tantalum rod implant surgery efficacy.6 Pain with or without group of preoperative imaging findings and correlation analysis6.1 ARCO preoperative staging and distribution with or without painNo pain group:33 hips of stageⅠ,1 hip of stageⅡand 30 hips of "pseudo stageⅡ". Pain group:15 hips of stageⅡ,10 hips of "pseudo stageⅡ" and 5 hips of stageⅢ, and there is significant difference between the two groups (P<0.001)6.2 Pain with or without group of subchondral bone fracture distributionNo pain group:1 hip of bone fracture shown in CT,30 hips of no bone fracture shown in CT. Pain group:15 hip of bone fracture shown in CT,12 hips of no bone fracture shown in CT, and there is significant difference between the two groups (P<0.001)6.3 Pain with or without group of bone marrow edema grading and distribution No pain group:30 hips of zero grading,1 hip of first grading,0 hip of second grading and 1 hip of third grading. Pain group:5 hips of zero grading, 7 hips of first grading,7 hips of second grading and 6 hips of third grading, and there is significant difference between the two groups (P<0.001)Conclusions1 Overall evaluationSimilar to fibula, treatment with tantalum rod is effective method for early stage of ONFH. Appropriate patient selection and precise surgical technique is the key to achieve the desired effect.2 Indications and contraindications of Tantalum rod applying to hip-preservingThe indication of using tantalum rod in hip-preserving surgeries is ARCOⅠstage and stableⅡstage that MRI modified anteroposterior Classification C1-type and below C,-type or modified index of necrotic extent below 67, unstable ARCOⅡphase ("pseudo-phaseⅡ") is a relative contraindication.That modified index of necrotic extent over 67 or MRI modified anteroposterior Classification C2-type is a absolute contraindication.3 Implantation techniques of tantalum rodThe direction of Core decompression must point to the three-dimensional central necrotic area, making the tantalum rods accounted for the largest area of necrosis, the depth of decompression should be as closely as possible to the articular surface, but not piercing the articular surface; subchondral bone and tantalum rods should be between for cancellous bone grafting in order to facilitate access to the initial stability of tantalum rod and subsequent necrosis biological repair, suppression of the cancellous bone of the thickness of the tantalum rod in order to meet the distance from the articular surface is not greater than 5mm.4 The main reason for the failure of tantalum rodLarge lesions of necrosis, instability in the femoral head and inappropriate operation techniques are the main reasons of the failure of tantalum rod, because:First, if the necrotic extent is too large, the primary and secondary instability would appear after implantation of the tantalum rod; Second, due to the pre-existence of instability in the head before operation, the condition is difficult to be corrected after implantation; Third, due to the inappropriate operation techniques, stability can not be achieved after implantation.