SuperPATH approach is considered a muscle-sparing approach,because except of a small incision of gluteus maximus, it takes advantage of the interval between gluteus medius and the piriformis to reach the superior hip joint capsule. In complex cases or where access proves difficult, the incision may be extended into a standard posterolateral approach.In this study, we found that compared with the conventional PLA,the SuperPATH approach for THA had some advantages, such as shorter incision, lower postoperative VAS, and better postoperative HHS at 1 and 3 months after surgery.However, SuperPATH approach did not reduce surgical bleeding and shorten hospital stay and was associated with a significantly longer operative time.
One of the advantages of minimally invasive surgery is that it can reduce the muscle and soft tissue impairment.In previous studies, SuperPATH approaches are correlated with lower levels of inflammation markers comparing with standard approaches.However,a recent study demonstrated that the SuperPATH group unexpectedly yielded more soft tissue damage and significantly increased serum CK levels compared with the PLA group on day 3 postoperatively.In our study, no difference was found concerning the increase of serum CRP,CK and ESR levels between the two groups.These inconsistent results are possibly attributable to additional intraoperative soft tissue (mainly muscle) damage from many sources , including intraoperative stretching , unintentional detachment , and varied instrument retraction , during the significantly elongated time taken to perform the procedure.A cadaveric model study by Amanatullah et al showed that the piriformis-sparing posterior approach to the hip causes inadvertent damage to the piriformis muscle in >90% of cases and that this damage occurs outside of the surgical field.
Operative time usually increases in the learning curve for a new surgical approach[15, 16].SuperPATH technology were related to more operative time and blood loss than conventional approaches[17-19].Due to insufficient exposure and limited visual field, it took more time to perform the operation.Lei et alreported that the average operation time in the first 20 patients undergoing THA using the SuperPATH approach was 122.65±27.45 min, and the operative time continued to decrease, which droped to 82.85±5.44 in the third 20 cases and 79.00±8.22 in the fourth 20 cases .A recent systematic analysis confirmed that the operative time of the SuperPATH group was 18.4 min longer than the conventional approach group.With the increase of operative time, the intraoperative blood loss will also increase.Mas et al reported that the mean blood loss in the SuperPath cohort was greater than posterior cohort(977.85±285.1 ml VS 752.46±299.3 ml),the differences were statistically significant.In our study,the mean operative time was 79.26 mini ,which was significantly higher than the PLA group.The increase of operative time was related to the following factors: insufficient surgical field of vision ,the learning curve stage and intraoperative fluoroscopy.This fact might have played a role in the greater intraoperative bleeding in the SuperPATH group, even though it is an approach that preserves the soft tissues better.Therefore, if the operative time is well controlled, the intraoperative blood loss will be greatly reduced.
Previous studies had confirmed that the VAS score were lower and HS was higher in the SuperPATH cohort comparing to the conventional approach in the early operative phase.Our study also confirmed the same results.However,the meta-analysis by Ramadanov found that no differences in pain VAS between hip replacements via SuperPATH and conventional approaches 1, 3 days, 3 and 12 months postoperatively.On the contrary,Meng et al found that pain VAS was significantly higher in the SuperPath group (7.05) compared with the PLA group (6.55) on postoperative day 3 and remained comparable between both groups at other time points within 1 year postoperatively.The meta-analysis by Ramadanov reported that HS on 7 days postoperatively was 10.2 higher in hip replacement via SuperPATH approach compared to hip replacement via conventional approaches. Meng et al reported that differences in average HHS were not significant between the PLA groups and SuperPath groups at any time point,hip function was observed to be significantly improved on postoperative day 14 (70.66±6.22) in the PLA group, but only showed a significant improvement at 3 months postoperatively (82.44±3.51) in the SuperPath group. Their data indicated that SuperPAHT was associated with overall inferior patient-reported outcomes during the early postoperative phase in terms of pain symptoms and hip function.
Intraoperative complications and component misalignment could be more prevalent in MIS-THA due to the constrained surgical field, which makes visualization of anatomical landmarks and alignment of the components more challenging.The correct position of the prosthetic components is essential for long-term implant survival.Deficient acetabular cup positioning might increase the wear rate and deteriorate the long-term stability of the hip implants,which is also the main cause of postoperative dislocation[23, 24].Implant malposition was one of considerable controversy for the minimally invasive technique due to poor exposure. In the present study, we found a lager average inclination and anteversion angle in the SuperPath group than in PLA group.A study by Tottas et al had revealed statistically significant larger average cup inclination and smaller cup anteversion in the SuperPATH group than in the Hardinge group.However, previous studies had found no difference between SuperPATH approach and conventional approach neither in anteversion nor in inclination[7, 20].Conversely,Meng W et al found that a significantly lower average abduction angle in the SuperPath group compared with the PLA group for hip OA.In this study,the complications of SuperPATH group did not increase compared with the PLA group. The risk of postoperative dislocation in the SuperPATH approach is theoretically lower than traditional approach due to preserving the short external rotator muscle and jiont capsule.However, it is very interesting that there were still two cases of anterior dislocations(4.3%) in the SuperPATH group,which was only single case of posterior dislocation(2.1%) in the PLA group.The two dislocations in the SuperPATH group occurred within 2 hours after operation and successfully treated by closed reduction without anesthesia,which was related to excessive anteversion of acetabular prosthesis.LLD can occur following THA and is a common source of patient dissatisfaction and litigation. In terms of LLD, Tottas et al confirmed that no significant differences were found between SuperPATH approach and standard modified Hardinge approach.The higher rate of LLD associated with the piriformis-sparing approach may be attributable to the lack of visualisation of the lesser trochanter, which is often used as a reference point for femoral neck osteotomy.This situation also exists in the SuperPATH approach.
The present study also has some limitations. Firstly,the sample size of the study is relatively limited and the postoperative follow-up was short,longe-term efficacy of the SuperPATH are still needed to observed.Secondly, different implants utilized for both approaches might have influenced on the postoperative outcomes,especially the long-term survival rate of prosthesis.Third, the extent of muscle damage was only assessed with serum markers within 2 weeks postoperatively, while no radiographic analyses, such as magnetic resonance imaging, were performed to confirm perioperative alterations of these serum markers.
In conclusion, we found SuperPATH approach in THA had better postoperative recovery efficacy with better hip function and less pain than patients with conventional PLA.However, the SuperPATH approach had a longer operative time and more blood loss and the long-term effect needs to be further observed.