Comparison Of Direct Anterior Approach And Posterior Approach For Total Hip Arthroplasty In Cases Of Osteonecrosis Of The Femoral Head

Background:The most widely used surgical intervention in treating femoral head osteonecrosis is Total Hip Arthroplasty.Throughout the ages,Total Hip Arthroplasty has undergone much evolution in terms of surgical techniques and material.Over time,different aspects of this surgery have been improved so as to make it more beneficial to both patients and doctors.There are various surgical approaches for this surgery and all these approaches have their respective advantages and disadvantages.Presently,among the various approaches,the Direct Anterior Approach and the Posterior Approach of THA have the most widespread use.Though many studies have been carried out in order to find the best surgical approach,a consensus has not yet been reached in the medical community.In our retrospective and comparative study,we investigated both the Direct Anterior Approach and the Posterior Approach so as to find out the better surgical approach for Total Hip Arthroplasty of the femoral head osteonecrosis.For this purpose,pre-operative,intraoperative and post-operative surgical parameters as well as early post-operative dislocation and periprosthetic fracture were investigated.Patients and Methods:Data was collected from September 2014 till December 2016(1 year follow up included)in the Orthopaedic Joint Surgery department at The Second Hospital of Dalian Medical University.78 patients,aged 39-89 years inclusive,took part in our study.The 78 cases were divided into two groups according to the surgical approach used: the Direct Anterior Approach group(DAA)and the Posterior Approach group(PA).The DAA group consisted of 35 cases(20 females and 15 males)aged 44-89 years old.The PA group consisted of 43 cases(20 females and 23 males)aged 39-81 years old.The study was based on the following parameters:(1)Demographics: Age,Gender and Body Mass Index(BMI);(2)Pre-operative parameters: Harris Hip Score,HHS(Pre-operative)and Haemoglobin level(pre-operative);(3)Intra operative parameters: Length of surgery time and Intra-operative blood loss and(4)Post-operative parameters: Post-operative blood loss(volume of blood in drain),Haemoglobin level difference(pre-operative and post-operative difference),Length of stay in hospital after surgery,Harris Hip Score,HHS at different time intervals after surgery(2 weeks,4 weeks,6 weeks,12 weeks,6months and 1year)and Post-operative radiographical examination for early postoperative dislocation and periprosthetic fracture.Data was analysed using SSPS software version 22.0.Descriptive statistics,student`s(independent)t-test,Pearson correlation and repeated measures test were carried out.Results:The mean age the patients from the Direct Anterior Approach group(DAA)was 59.83 ±9.473 years and the mean age from the Posterior Approach group(PA)was 55.74 ± 9.781 years.Age difference(t=1.860,p=0.067)and gender difference(X2=0.873,p=0.350)were not statistically significant.The mean BMI of the patients from the DAA group was24.978±3.002 kg/m2(range: 19.03-30.86 kg/m2).The patients from the PA group had a mean BMI of 25.189±3.009 kg/m2(range 18.67-31.25 kg/m2).The mean BMI difference was not statistically significant(t =-0.309,p=0.758).Pre-operative parameters: The mean pre-operative Harris Hip Score for the DAA group was 44.00±7.046 and for the PA group was 44.70±10.232.This result was not statistically significant(t =-0.342,p=0.733).The mean pre-operative Haemoglobin level of the DAA group was 13.157±1.398 g/d L and the PA group was 13.714±1.509 g/d L.The difference was not statistically significant(t =-1.675,p=0.098).Intra-operative parameters: The mean length of surgery time of the DAA group(81.86±13.778 min)was mildly longer than that of the PA group(77.79±13.597 min).This difference was not statistically significant(t =1.306,p=0.196).The intra-operative blood loss volume of the DAA group(275.71±129.689 m L)was less than that of the PA group(324.42±153.674 m L).This difference was not statistically significant(t =-1.491,p=0.140).Post-operative parameters: The mean length of post-surgery stay in hospital of the DAA group(14.31 ± 5.90 days)was less than that of the PA group(15.12 ± 7.13 days).This difference was not statistically significant(t =-0.533,p=0.595).The difference between pre-operative and post-operative haemoglobin level of the DAA group(2.074 ± 1.283g/d L)was less than that of the PA group(2.595 ± 1.310 g/d L).This difference was not statistically significant(t =-1.764,p=0.082).The mean post-operative blood volume in drainage of the DAA group(223.57 ± 118.195 m L)was less than that of the PA group(254.42 ± 114.024 m L).This difference was not statistically significant(t =-1.169,p=0.246).There was a statistical significant difference in the post-operative Harris Hip Score(HHS),between DAA and PA,measured at 2 weeks’,4 weeks’ and 6 weeks’ time interval.At 2 weeks’ time interval,the mean HHS of the DAA group(53.60±4.888)was higher than that of the PA group(47.00±6.381);t = 5.032,p=0.000.At 4 weeks’ time interval,the mean HHS of the DAA group(66.74 ± 2.683)was higher than that of the PA group(62.84 ± 1.825);t = 7.627,p=0.000.At 6 weeks’ time interval,the mean HHS of the DAA group(78.17 ± 4.253)was higher than that of the PA group(72.51 ± 1.932);t=7.802,p=0.000.When post-operative HHS was measured at 12 weeks,6 months and 1year time interval,the difference in HHS between DAA and PA was not statistically significant.For the PA group BMI was negatively correlated to HHS at 2 weeks’ time interval.This result was statistically significant(r=-0.331,p= 0.030).Throughout our study,there were neither early post-operative dislocation nor periprosthetic fracture.The complication rate between the two approaches was therefore not compared.The effect of THA Approach on early post-operative dislocation and periprosthetic fracture also could not be demonstrated.Conclusion:Our study showed that the early functional outcome,measured by the Harris Hip Score(HHS),was the only main difference between the two approaches: DAA and PA.At same time,there were no significant difference in other parameters.Even though,significant differences in the Harris Hip Score between DAA and PA were obtained in early stage post-operatively,after 12 weeks,when HSS were evaluated,there were no significant difference.So based on only one factor we cannot prove that DAA is better than PA because both have their respective advantages and disadvantages in nowadays clinical practice.Choosing the best surgical approach depends both on the patients’ case history and the surgeons’ experience.Several factors should be considered before choosing the surgical approach in cases of osteonecrosis of the femoral head.With the advent of new,better surgical techniques and materials,the post-operative complication rate in cases of osteonecrosis of the hip has decreased.Through this study,we wish we can assist orthopaedic doctors to choose an optimization to deal with THA practice.