In total hip arthroplasty (THA), the accurate positioning of implants is the key to achieve a good clinical outcome. Computer-assisted orthopaedic surgery (CAOS) has been developed for more accurate positioning of implants during the THA. There are passive, semi-active, and active systems in CAOS for THA. Navigation is a passive system that only provides information and guidance to the surgeon. There are 3 types of navigation: imageless navigation, computed tomography (CT)-based navigation, and fluoroscopy-based navigation. In imageless navigation system, a new method of registration without the need to register the anterior pelvic plane was introduced. CT-based navigation can be efficiently used for pelvic plane reference, the functional pelvic plane in supine which adjusts anterior pelvic plane sagittal tilt for targeting the cup orientation. Robot-assisted system can be either active or semi-active. The active robotic system performs the preparation for implant positioning as programmed preoperatively. It has been used for only femoral implant cavity preparation. Recently, program for cup positioning was additionally developed. Alternatively, for ease of surgeon acceptance, semi-active robot systems are developed. It was initially applied only for cup positioning. However, with the development of enhanced femoral workflows, this system can now be used to position both cup and stem. Though there have been substantial advancements in computer-assisted THA, its use can still be controversial at present due to the steep learning curve, intraoperative technical issues, high cost and etc. However, in the future, CAOS will certainly enable the surgeon to operate more accurately and lead to improved outcomes in THA as the technology continues to evolve rapidly.
Arthroplasty ; Arthroplasty, Replacement, Hip* ; Hip ; Learning Curve ; Methods

BACKGROUNDThe acetabular teardrop is often used to guide acetabular component placement in total hip arthroplasty (THA). Placing the lower acetabular component aspect at the same level as the lower teardrop edge was assumed to restore the hip center of rotation. Here we radiographically analyzed the relationship between cup center and normal contralateral acetabulum center height on unilateral THA using this placement method.

METHODSA total of 106 unilateral THA cases with normal contralateral acetabula were reviewed and the vertical and horizontal distances in relation to the lower acetabular teardrop edge from both hip joint centers, cup inclination, and anteversion were measured radiographically. The paired t-test was used to compare left and right hip center heights. Scatter plots and Pearson's correlation coefficients were used to evaluate differences in hip center heights, cup anteversion, inclination angles, and medialized cup center distance compared to the contralateral hip joint.

RESULTSCup center height was significantly greater (P < 0.01) than contralateral hip joint center height (93.4% in the 0-5 mm range, 6.6% >5 mm). There was a weak correlation between hip center height difference and inclination (r = 0.376, P < 0.01) and between difference and anteversion (r = 0.310, P < 0.01) but no correlation between difference and outer cup diameter (r = 0.184, P = 0.058) or difference and medialized cup center distance (r = -0.098, P = 0.318).

CONCLUSIONSAlthough this method did not exactly replicate anatomic hip center height, the clinical significance of cup center height and anatomic hip center height differences is negligible. This acetabular component placement method has high simplicity, reliability, and stability.

The use of acetabular cup revision arthroplasty is on the rise as demands for total hip arthroplasty, improved life expectancies, and the need for individual activity increase. For an acetabular cup revision to be successful, the cup should gain stable fixation within the remaining supportive bone of the acetabulum. Since the patient's remaining supportive acetabular bone stock plays an important role in the success of revision, accurate classification of the degree of acetabular bone defect is necessary. The Paprosky classification system is most commonly used when determining the location and degree of acetabular bone loss. Common treatment options include: acetabular liner exchange, high hip center, oblong cup, trabecular metal cup with augment, bipolar cup, bulk structural graft, cemented cup, uncemented cup including jumbo cup, acetabular reinforcement device (cage), trabecular metal cup cage. The optimal treatment option is dependent upon the degree of the discontinuity, the amount of available bone stock and the likelihood of achieving stable fixation upon supportive host bone. To achieve successful acetabular cup revision, accurate evaluation of bone defect preoperatively and intraoperatively, proper choice of method of acetabular revision according to the evaluation of acetabular bone deficiency, proper technique to get primary stability of implant such as precise grafting technique, and stable fixation of implant are mandatory.
Acetabulum* ; Arthroplasty ; Arthroplasty, Replacement, Hip ; Classification ; Hip ; Hip Prosthesis ; Life Expectancy ; Methods ; Reoperation ; Transplants

The writers performed Sbarbaro type total hip replacement arthroplasty on two cases with degenerative arthriris of both hips complicated by avascular necrosis of the femoral head. In each case, the procedure was carried out on the worse hip, while in one case a standard femoral head prosthesis was inserted to the less severely involved hip. The Sbarbaro type prosthesis consists of a modified Austin Moore head component and an acetabular cup with tynes that fix the metal to the acetabulum and does not require the use of cement. The initial results in both cases, evaluated by the method of D'Aubigne and Postel, are as follows; Grade 5 for pain(pain both slight or intermittent), Grade 5 for motion(very good or 161 to 210 degrees), and Grade 5 for ability to walk(very good; no cane or crutch but a slight limp).
Acetabulum ; Arthroplasty ; Arthroplasty, Replacement, Hip ; Canes ; Head ; Hip ; Hip Prosthesis ; Methods ; Necrosis ; Prostheses and Implants

How to remove the well fixed cement or cementless prosthesis and get a completely distal cement removal in the rTHR are critical to the outcome of revision. Because of higher rate of union, excellent intraoperative exposure, and adjustment of abductor tension, ETO has been widely applied to rTHR and complicated primary THR by foreign scholars. Furthermore, this technology has wide indications, very few contraindications, high cure rates,and low complications rate. ETO turns out to be a safe and effective revision technology. In the article, the indication, contraindication, complications and advantages of this technique were reviewed.
Arthroplasty, Replacement, Hip ; methods ; Humans ; Osteotomy ; adverse effects ; methods

To contrast the methodology of measuring cup placement precision utilizing Mimics and Matlab programming, based on clinical CT images of primary THA cases with computer assisted navigated surgery (CANS) and with the traditional manual method (MANS). The method was applied and analyzed to measure cup anteversion, cup abduction of 50 clinical cases with CANS and MANSThe results show that, cup placement precision differences exits between primary THA cases with CANS and MANS; more cases with CANS are within the safe zone contrasting MANS, and there was less variation and less placement error in CANS cases. CANS can improve cup placement precision and reduce the chance of dislocation efficiently.
Arthroplasty, Replacement, Hip ; instrumentation ; methods ; Humans ; Surgery, Computer-Assisted ; methods

OBJECTIVETo systematically review the effectiveness of minimally invasive total hip arthroplasty (MIS-THA) versus traditional total hip arthroplasty (THA) in patients with hip diseases.

METHODSThrough a method of combining Free words and keywords,we searched databases including PubMed,The Cochrane Library, EMbase,Web of Science, CBM , CNKI and Wanfang Data for randomized controlled trials (RCTs) on the comparison between MIS-THA and THA for hip disease from inception to June, 2014. Two reviewers independently screened literatures according to the inclusion and exclusion criteria, extracted data and assessed the quality of the included studies according to the "bias risk assessment" tool recommended by Cochrane Handbook 5.0 for Systematic Reviews. Then, meta-analysis was performed using RevMan 5.3 software.

RESULTSThirteen RCTs involving 1 213 cases of surgeries and total 1 284 hips (MIS-THA: n = 631; THA: n = 653) were identified. The results of meta-analysis showed that statistically significant differences were found in Harris hip score on the 3rd month after operation [MD = 8.37, 95% CI (6.02,10.72)], Hematocrit [MD = 0.02, 95% CI (0.01, 0.03)] and Hemoglobin [MD = 0.50, 95% CI (0.16, 0.85)] at the 48th hour after operation, changed value of femoral offset [MD = 0.30, 95% CI (0.04, 0.56)] between two groups. In the change value of femoral offset, THA was better than MIS-THA; There were no statistically significant differences between two groups in Harris hip score at 1st year after operation [MD = 3.26, 95% CI (-3.25, 9.76)], WOMAC score [MD = -0.53, 95% CI (-3.67, 2.60)] and Oxford score [MD = 1.34, 95% CI (-3.46, 6.13)] at the 6th week after operation, Hematocrit at the 8th hour after operation [MD = -0.01, 95% CI (-0.02, 0.00)], the incidence of hip varus [RR = 0.82, 95% CI (0.45,1.52)] and dislocation [RR = 1.40, 95% CI (0.48, 4.12)].

CONCLUSIONTHA brings less trauma, less hemorrhage and better early clinical outcome compared with MIS-THA, but the difference of the complication rates between the two groups is similar.

Arthroplasty, Replacement, Hip ; methods ; Bone Transplantation ; Femur ; surgery ; Humans

The incidence of acetabular fractures in the elderly has increased because of the increasing elderly population. To determine the treatment plan for acetabular fractures, the patient's age, gait ability, presence or absence of osteoporosis and osteoarthritis, underlying disease, and fracture pattern should be considered. The application of total hip arthroplasty for acetabular fractures with the proper indications can be expected to have a good prognosis. In this paper, the application of total hip arthroplasty as a treatment method for acetabular fractures is divided into acute and delayed phases.
Acetabulum ; Aged ; Arthroplasty ; Arthroplasty, Replacement, Hip ; Gait ; Hip ; Humans ; Incidence ; Methods ; Osteoarthritis ; Osteoporosis ; Prognosis

Biomechanical test in vitro was performed to study the biomechanical characteristics of the femoral component in the non-stemmed anatomical total hip prosthesis (A-Fix) arthroplasty. It mimics two stages, the early stage with cementless and the later stage with cement fixation that imitates bone ingrowth. The results were compared with that of normal proximal femur by normalized coefficient analysis. Translation of femoral head after hip replacement is slightly more than normal. The strain of femoral neck after replacement is lower than that of normal. It changes flatly. The security coefficient in early stage is raised by 13% on the tensile side and by 27.6% on the compressive side of femoral neck; that in later stage is raised by 29.6% and by 22.1% separately. The maximal torsional angle of femoral head is minimal, it is 0.02 times that of normal in early stage and 0.01 times in later stage. It demonstrated that A-Fix arthroplasty has the characteristics of low stress and deformation, high intensity and rigidity, and anti-loosening, thus affording mechanical evidences for its clinical use.
Adult ; Arthroplasty, Replacement, Hip ; methods ; Biomechanical Phenomena ; Cementation ; methods ; Hip Prosthesis ; Humans ; Male ; Prosthesis Design ; methods