Introduction. While research has been carried out widely for sagital pelvic tilt, research reports for coronal pelvic obliquity are few. The aim of this study is to evaluate changes of the pelvic obliquity before and after total hip arthroplasty. Material and Methods. This retrospective study includes 146 cases of hips that were received total hip arthroplasty. There were 20 cases of revision, and 2 cases of re-revision. 17 cases were received bilateral total hip arthroplasty. The standing plain X-ray was used for evaluation of the pelvic obliquity in both before and 1-year after surgery. The correlation of pelvic obliquity was assessed between before and after surgery. 146 cases were classified into 3 groups (A, B, and C) according to the severity of the pelvic obliquity (0º−3º, 3º−6º, and >6º). Among the groups, statistical analysis was evaluated in the leg length discrepancy and the range of motion of the hip (flexion, extension, abduction, adduction, internal and external rotation) before and after surgery with 95% confidence intervals. Results. The mean pelvic obliquity angle was 2.6º with the range of 0 to 15.9º preoperatively, while the mean angle was 2.0º with the range of 0 to 8.8º postoperatively. There was statistical correlation in pelvic obliquity between before and after surgery. The mean leg length discrepancy was −8.3 before surgery, and was 0.1 after surgery. Comparing three groups of pelvic obliquity, preoperative leg length discrepancy was significantly longer in larger pelvic obliquity groups. The range of motion in hip flexion was also significantly smaller in larger pelvic obliquity groups. There were not significant differences in postoperative leg length discrepancy and other parameters. Discussion. The most important finding of present study was that postoperative pelvic obliquity related only the preoperative leg length discrepancy and the range of motion in hip flexion. We expected that pelvic obliquity is improved by correction of leg length difference. Nevertheless, there were not significant differences in postoperative leg length discrepancy. This indicated that contracture of the hip joint is contribute to pelvic obliquity more than leg length discrepancy. Previous study reported that pelvic obliquity would be improved by physical therapy 4 to 6 month after surgery. However, in our data, pelvic obliquity still remained at 1-year follow up. Moreover, postoperative pelvic obliquity related the preoperative range of motion in hip flexion. Therefore, preoperative pelvic obliquity is one of the most important parameter to make decision of postoperative leg length discrepancy. There is certain limitation in our study. We did not assess patient outcome in each groups. Extensive studies are needed to reveal correlation between pelvic obliquity and patient outcome. Conclusion. Pelvic obliquity related the preoperative leg length discrepancy and the range of motion in hip flexion. Contracture of the hip joint may cause pelvic obliquity

Introduction. Limb-length discrepancy (LLD) is a common postoperative complication after total hip arthroplasty (THA). This study focuses on the correlation between patients’ perception of LLD after THA and the anatomical and functional leg length, pelvic and knee alignments and foot height. Previous publications have explored this topic in patients without significant spinal pathology or previous spine or lower extremity surgery. The objective of this work is to verify if the results are the same in case of stiff or fused spine. Methods. 170 patients with stiff spine (less than 10° L1-S1 lordosis variation between standing and sitting) were evaluated minimum 1 year after unilateral primary THA implantation using EOS® images in standing position (46/170 had previous lumbar fusion). We excluded cases with previous lower limbs surgery or frontal and sagittal spinal imbalance. 3D measures were performed to evaluate femoral and tibial length, femoral offset, pelvic obliquity, hip-knee-ankle angle (HKA), knee flexion/hyperextension angle, tibial and femoral rotation. Axial pelvic rotation was measured as the angle between the line through the centers of the hips and the EOS x-ray beam source. The distance between middle of the tibial plafond and the ground was used to investigate the height of the foot. For data with normal distribution, paired Student's t-test and independent sample t-test were used for analysis. Univariate logistic regression was used to determine the correlation between the perception of limb length discrepancy and different variables. Multiple logistic regression was used to investigate the correlation between the patient perception of LLD and variables found significant in the univariate analysis. Significance level was set at 0.05. Results. Anatomical femoral length correlated with patients’ perception of LLD but other variables were significant (the height of the foot, sagittal and frontal knee alignment, pelvic obliquity and pelvic rotation more than 10°). Interestingly some factors induced an unexpected perception of LLD despite a non-significant femoral length discrepancy less than 1cm (pelvic rotation and obliquity, height of the foot). Conclusions. LLD is a multifactorial problem. This study showed that the anatomical femoral length as the factor that can be modified with THA technique or choice of prosthesis is not the only important factor. A comprehensive clinical and radiological evaluation is necessary preoperatively to investigate spinal stiffness, pelvic obliquity and rotation, sagittal and coronal knee alignment and foot deformity in these patients. Our study has limitations as we do not have preoperative EOS measurements for all patients. We cannot assess changes in leg length as a result of THA. We also did not investigate the degree of any foot deformities as flat foot deformity may potentially affect the patients perception of the leg length. Instead, we measured the distance between the medial malleolus and ground that can reflect the foot arch height. More cases must be included to evaluate the potential influence of pelvis anatomy and functional orientation (pelvic incidence, sacral slope and pelvic tilt) but this study points out that spinal stiffness significantly decreases the LLD tolerance previously reported in patients without degenerative stiffness or fusion

Introduction. Limb length discrepancy after THA can result in medicolegal litigation. It can create discomfort for the patient and potentially cause back pain or affect the longevity of the implant. Some patients tolerate the length inequality better compared to others despite difference in anatomical femoral length after surgery. Methods and materials. We analyzed the 3D EOS images of 75 consecutive patients who underwent primary unilateral THA (27 men, 48 women). We measured the 3D length of the femur and tibia (anatomical length), the 3D global anatomical length (the sum of femur and tibia anatomical lengths), the 3D functional length (center of the femoral head to center of the ankle), femoral neck-shaft angle, hip-knee-ankle angle, knee flexum/recurvatum angle, sacral slopes and pelvic incidence. We correlated these parameters with the patient perception of the leg length. Results. The values for leg length and pelvic parameters are shown in table 1. 37 patients had a perception of the LLD (49.3%). When the global anatomical length was shorter on the operated side, the perception of the discrepancy was observed in 56% of the cases. In case of anatomical length longer on the operated side, the perception of the discrepancy was described by the patients in 46% of the cases. The LLD perception was correlated with difference in functional length (p=0.0001), pelvic obliquity (p=0.003) and sacral slope (p=0.023). The anatomical femoral length was not correlated with the LLD perception (p=0,008). Discussion. The perception of LLD is a multifactorial complication. We found that the anatomical femoral length (that can be directly affected by the position of the stem) is not the only important factor. The functional length of the lower extremity which can also be affected by the knee deformities is better correlated with the LLD. The pelvic obliquity and version also affect the patient perception of the LLD

Objective. By retrospective analysis of clinical data, to find new risk factors for postoperative dislocation after total hip replacement and the dose-effect relationship when multiple factors work simultaneously. Methods. A nested case-control study was used to collect the dislocated hips from 5513 primary hip replacement case from 2000 to 2012. Apart from the patients with given cause of dislocation, 39 dislocated hips from 38 cases were compared with 78 hip from 78 cases free from dislocation postoperatively, which matched by the admission time. The factors that may affect the prosthetic unstable was found by the univariate analysis, and then they were performed multivariate logistic regression analysis and evaluation of a dose-effect factors. Results. The clinical scores between the two groups was no significant difference before and after surgery. Univariate analysis revealed the position of acetabular prosthesis (P = 0.05) and the big ball (P=0.01) differences were statistically significant. While patient with adduction deformity incorporating limb lengthening≧2cm(P<0.01) or the knee valgus deformity incorporating pelvic obliquity (P=0.01), as well as bilateral cases (P=0.02) were also the risk factors for dislocation. Big head decrease the dislocation rate. Multivariate analysis confirmed these newly founded factors are more important than the classic factors in this group of patients. Conclusion. Patients with hip adduction deformity combined with limb lengthening, knee valgus deformity combined with pelvic obliquity and bilateral pathological hip seem more predisposed to dislocation after total hip arthroplasty, who should be strengthened preoperative education and postoperative management to prevent. Key Word. total hip arthroplasty, dislocation, multivariate analysis

Digital templating was used in 50 patients who underwent THA using Merge Ortho software, Cedara. Clinical examination was performed first, to measure leg lengths and account for pelvic obliquity and flexion deformity. Good quality digital radiographs were obtained with anteroposterior and lateral views extending beyond the tip of the femoral component and the cement restrictor. A coin was placed on the ASIS to help in determining radiological magnification. Digital radiographs were saved in DICOM format and imported to EndoMap software system. A 6-step technique was used for templating as follows:. Radiographic assessment; looking at the quality of bone, amount of bone stock, dysplasia, osteophytes, and other abnormalities. Correction of magnification; following the specific instructions of the software, by measuring the diameter of the coin on the digital radiograph. 3. Measuring leg length discrepancy; the software system automatically calculated the leg length discrepancy, even in the presence of pelvic obliquity (Figure1). 4. Templating acetabular component; the desired cup was selected from the implant library after identifying important landmarks. The size and position was modified to fit the acetabulum and to restore the center of rotation of the hip, considering minimal bone removal and sufficient bone coverage laterally. Templating femoral component; the size and position of the desired stem was adjusted to fit the femoral canal, different offsets were compared to find the best match for the patient's original offset. Correction of leg length discrepancy and measuring length of neck resection; the height of the femoral stem was adjusted to correct any leg length discrepancy by placing the center of the head above the center of the cup by the same length of discrepancy. Then the level of the neck resection was marked at the level of the stem collar and the femoral neck cut was measured by a digital ruler from the tip of the lesser trochanter to the mark of neck resection. In case of leg length discrepancy, the height of the femoral neck cut was adjusted accordingly to compensate for the leg length discrepancy. For example, if the affected leg is 20 mm short, place the centre of the head 20 mm above the centre of the cup. Intraoperatively, the surgeon performed the femoral neck osteotomy at the level determined by preoperative templating. Postoperatively, the leg length was measured and compared to the preoperative leg length. Preoperatively, the leg length discrepancy ranged from 5 to 30 mm. In all cases, the leg was short on the side of THR (ipsilateral). Leg length discrepancy was adjusted in all THR cases. Postoperatively, the accuracy of the correction was found to be within 5 millimeters i.e. less than 5mm of shortening or lengthening). Intraoperatively, the level of femoral neck cut ranged from 1 to 44 mm. Digital templating is useful in adjusting leg length discrepancy. In addition, there were other benefits such as predication of femoral and acetabular implant sizes, restoration of normal hip centre, and optimization of femoral offset

Anteroposterior (AP) pelvic radiographs are the standard tool used for pre-operative planning and post-operative evaluation during total hip arthroplasty (THA). The accuracy of this imaging modality is, however, limited by errors in pelvic orientation and image distortion. Pelvic obliquity is corrected for by orienting measurements to a reference line such as the interteardrop line or the interischial line, while several methods for correcting for pelvic tilt have been suggested, with varying levels of success. To date, no reliable method for correcting for pelvic rotation on pelvic imaging is available. The purpose of this study was to evaluate a novel method for correcting pelvic rotation on a standard anteroposterior (AP) radiographs. Computed tomography (CT) scans from 10 male cadavers and 10 female THA patients were segmented using 3D Slicer and used to create 3D renderings for each pelvis. Synthetic AP radiographs were subsequently created from the 3D renderings, using XRaySim. For each pelvis, images representing pelvic rotation of 30° left to 30° right, at 5° increments were created. Four unique parameters based on pelvic landmarks were used to develop the correction method: i) the horizontal distance from the upper edge of the pubic symphysis to the sacroiliac joint midline (PSSI), ii) the ratio of the horizontal distances from the upper edge of the pubic symphysis to the outer lateral border of both obturator foramina (PSOF), iii) the width ratio of the obturator foramina (OFW) and iv) the ratio of the horizontal distance from each anterior superior iliac spine to the sacroiliac joint midline (ASISSI). The relationships between the chosen parameters and pelvic rotation were investigated using a series of 260 (13 per pelvis) synthetic AP radiographs. Male and female correction equations were generated from the observed relationships. Validation of the equations was done using a different set of 50 synthetic radiographs with known degrees of rotation. In males, the PSSI parameter was most reliable in measuring pelvic rotation. In females, PSOF was most reliable. A high correlation was noted between calculated and true rotation in both males and females (r=0.99 male, r=0.98 female). The mean difference from the male calculated rotation and true rotation value was 0.02°±1.8° while the mean difference from the female calculated rotation and true rotation value was −0.01°±1.5°. Our correction method for pelvic rotation using four pelvic parameters provides a reliable method for correcting pelvic rotation on AP radiographs. For any figures or tables, please contact authors directly

Most discussions of alignment after TKA focus on defining “malalignment”; the prefix mal- is derived from Latin and refers to bad, abnormal or defective and thus by definition malalignment is bad, abnormal or defective alignment. No one then wants a “malaligned” knee. The intellectually curious, however, might switch the focus to the other end of the spectrum and ask what does an ideally aligned knee look like in 2015? Is there really one simple target value for alignment in all patients undergoing TKA? Is that target broad (zero +/−3 degrees mechanical axis) or is it a narrow target in which a penalty, in regard to durability or function, is incurred as soon as you deviate even 1 degree? Is that ideal target the same if we are evaluating the functional performance of the TKA versus the durability of the TKA or could there be 2 different targets, one that maximises function and one that maximises durability? Is that target adequately described by a single 2-dimensional value (varus/valgus alignment in the frontal plane) as measured on a static radiograph? Is that value the same if the patient has a fixed pelvic obliquity, a varus thrust in the contralateral knee or an abnormal foot progression angle?. It is revealing to ask “do we understand TKA alignment better in 2015 than in 1979…?” Maybe not. We allowed ourselves over the past 2 decades to be intellectually complacent in regard to questions of ideal alignment after TKA. The constraints on accuracy imposed by our standard total knee instruments and the constraints on assessment imposed by 2-dimensional radiographs made broad, simple targets like a mechanical axis +/− 3 degrees reasonable starting points yet we have not further worked to verify if we can do better. It is naïve to think that the complex motion at the knee occurring in 6-dimensions over time can be reduced to a single static target value like a neutral mechanical axis and have strong predictive value in regard to the success or failure of an individual TKA. We assessed 399 knees of 3 different modern cemented designs at 15 years and found that factors other than alignment were more important than alignment in determining the 15-year survival. Until more precise alignment targets can be identified for individual patients or sub-groups of patients then a neutral mechanical axis remains a reasonable surgical goal. However, the traditional description of TKA alignment as a dichotomous variable (aligned versus malaligned) defined around the broad, generic target value of 0 +/− 3 degrees relative to the mechanical axis is of little practical value in predicting the durability or function of modern TKA

Accelerometer based gait analysis (AGA) is a potential alternative to the more commonly used skin marker based optical motion analysis system(OMAS). The use of gyroscopes in conjunction with accelerometers (i.e. inertial sensors), enables the assessment of position and angular movements of body segments and provides ambulatory kinematic characterisation of gait. We investigated commonly used gait parameters and also a novel parameter, Pelvic obliquity (PO) and whether they can be used as a parameter of physical function and correlate with classic clinical outcome scores. Gait was studied in healthy subjects (n=20), in patients with end stage hip OA (n=20) and in patients with end stage knee OA (n=20). Subjects walked 20 metres in an indoor environment along a straight flat corridor at their own preferred speed. A 3D inertial sensor was positioned centrally between the posterior superior iliac spines (PSIS) overlying S1. Comparing gait parameters of end stage hip OA patients with an age and gender matched healthy control group, significantly lower walking speed, longer step duration and shorter step length was observed. After correcting for walking speed between groups, significantly less average range of motion of PO (RoM. po. ) was observed for patients with end stage hip OA compared to healthy subjects and patients with end stage knee OA. IGA allows objective assessment of physical function for everyday clinical practice and allows assessment of functional parameters beyond time only. IGA measures another dimension of physical function and could be used supplementary to monitor recovery of OA patients after TJR

Introduction. All current methods of cup placement use anterior pelvic plane (APP) as the reference. However, the majority of studies investigating the measurement of anteversion (AV) and abduction angles (AA) are inaccurate since the effect of pelvic tilt and obliquity are not considered. The aim of this study was to describe a reproducible, novel technique for functional cup positioning using internal and external bony landmarks and the transverse acetabular ligament (TAL). Methods. The pelvic obliquity and tilt are measured on the pre-operative weight bearing AP and lateral pelvic radiographs. Intra-operatively, the highest point of the iliac crest is identified and a line is drawn to the middle of the greater trochanter with knee flexed to 90 degrees and leg thigh horizontal to the floor, parallel to the APP. The cup is placed parallel to the TAL and inside the anterior acetabular wall notch, and then is adjusted for the femoral anteversion, pelvic tilt and obliquity. The angle between the drawn line and the cup handle is the operative anteversion. 78 consecutive total hip replacements (76 patients) were performed using this technique. The functional cup orientation was measured on post-operative weight bearing pelvic radiographs using EBRA software. Results. The mean follow-up was 1.2 ± 0.3 years. There were no fracture, dislocation or infection. The mean functional AV and AA were 17.9° ± 4.7° (7.8–28.7) and 41.7° ± 3.8° (33.4–50), respectively. The mean pelvic tilt and obliquity were −3.1° ± 9.7° (−25–9) and −1.5° ± 3.2° (−9.9–7.4), respectively. 96% of functional AV and 100% of functional AA measurements were within the safe zone. Discussion and Conclusion. This is an easy, accurate, and reproducible technique, which uses bony landmarks and TAL, adjusted for femoral anteversion and pelvis tilt and obliquity. Weight-bearing radiographs should be used to standardise the measurements with the goal to reproduce the functional cup orientation within the safe zone

Preoperative planning is important – an ounce of prevention is worth a pound of cure. It is perhaps useful to consider the process of preoperative planning in three areas: 1) the patient, 2) the hip, and 3) the operative environment. The Patient - The patient must first be an appropriate candidate for surgery. By this, they should have confirmed arthritis of the hip by radiograph and physical exam and should have failed conservative management. They should have pain and/or physical disability that impair their activities of daily living. They should be fit and willing to undergo surgery. Their expectations of surgical outcome should be reasonable and the anticipated net clinical benefit of the procedure should outweigh the risks. There are several patient variables that should be optimised prior to surgery. Blood glucose control in diabetics should be tightly controlled prior to surgery as failure to do so results in an increased risk of infection. Anemia should be ascertained in the history and diagnosed with a CBC if suspected. Reasons for anemia should be addressed and hemoglobin should be optimised preoperatively. Nutrition is important to reduce the risk of infection. Be aware of paradoxical malnutrition in the obese. Understand if the patient has an allergy to penicillin and what specifically the reaction is. Patients with a history that is not characteristic of an IgE mediated response should be offered a cephalosporin. The patient's risk of bleeding or clot as well as their tolerance of specific anticoagulants should be understood and planned for regarding the postoperative anticoagulant. Assess the patient for risk of dislocation. The Hip - Assessment of the hip is important. An AP of the pelvis and lateral of the hip should be obtained in all cases. Any pelvic obliquity should be assessed in relation to leg length discrepancy, and, if necessary, a 3-foot standing x-ray should be obtained. Leg length and offset should be assessed carefully. Beware of the patient with the operative hip presenting as the longer leg as it is difficult to shorten a hip via THA and the net effect of the intervention is most often lengthening. Patients with low offset should be planned for carefully so that low offset components are available. Patients with high offset need corresponding high offset implants in order to avoid leg lengthening. The acetabulum should be assessed for true center of rotation and orientation, as well as for dysplasia or deficiency. The femur should be assessed for shape, offset and neck angle, as well as for any proximal or distal mismatch. Be prepared to remove hardware that will be in the way. Template all your cases. The most experienced surgeons still template for THA. Have a Plan A and a Plan B for every case. The Operative Environment - The surgeon is ultimately in control of the operative environment. Make sure that the implants anticipated and sizes are available. I personally put them in the room before the case. Ensure that qualified assistants and nurses are available. Know in advance and communicate when high BMI patients are involved. Display the radiographs and anticipated plan and make sure the team is aware of it. Ensure that antibiotics and tranexamic acid (if not contra-indicated) are administered at a timely fashion. Tell the staff in the time out that traffic flow is important and should be reduced to a minimum. Plan to close one of the doors during the case. Make sure protective covering is available and worn, such as protective eyewear and hair covers

Introduction. Minimally invasive, computer navigated techniques are gaining popularity for total knee replacement (TKA). While these techniques may have the potential to provide improved functional outcomes with more rapid recovery, little quantitative data exists comparing long-term gait function following surgery with different exposure approaches. This study compares functional gait differences between surgical approach groups two year following TKA. Kinetics, kinematics, and temporospatial parameters were assessed to determine if differences exist between groups in long term follow-up. Methods. This study was approved by the Banner IRB (Sun Health Panel). 95 subjects volunteered to participate in the study and signed informed consent prior to testing. The subjects were prospectively randomized to one of four surgical approach groups, mini-midvastus (MV), mini-subvastus (SV), mini-parapatellar (MP), and standard parapatellar (SP). These subjects were also compared to 45 age-matched, asymptomatic controls. Surgery was performed by one of two fellowship trained orthopedic surgeons specializing in adult reconstruction. Subjects were assessed in the gait laboratory two years after receiving surgery. Three dimensional kinetic and kinematic data were captured using a ten-camera passive marker system, a modified Helen Hayes marker set (Eagle-4, Motion Analysis, Santa Rosa, CA), and four floor embedded force platforms (AMTI Inc., Watertown, MA). Subjects were instructed to walk at a self selected speed down an 8 meter walkway. Kinetic and kinematic data were post processed using EVaRT and OrthoTrak 6.23 biomechanical software (Motion Analysis, Santa Rosa, CA). Statistical analyses were performed using SPSS (v14.0, SPSS Inc, Chicago, IL) and included a one-way ANOVA and post hoc testing. Results. 50 subjects returned for a two year gait analysis. Selected results are provided in Table 1. All approach groups regained near normal knee function compared to age matched controls. Motion analysis provided specific statistical differences between parameters about the knee and hip. The MV approach group maintained greater flexion than other groups at the knee and hip throughout the gait cycle. The MP group maintained the most extended knee postures throughout the task with significant differences from controls being noted during peak flexion in swing (p = 0.039) and at foot strike (p = 0.034). They also had reduced external knee rotation angles (p = 0.010) and a larger pelvic rotation range of motion (p = 0.020). Although not significant, the MP group had a concurrent increase in pelvic obliquity on the operative limb during weight acceptance. The MP group also had the highest velocity, cadence, stride length, and the earliest toe off when compared to other groups. Discussion. The results indicate that there are subtle differences in gait strategy between approach groups at the two year time point. The MV group maintains increased flexion angles at the hip and knee throughout the gait cycle which could be characterized as a “bent-hip bent-knee” gait. This could be due to differences in capsular and muscle scarring between the different surgical approach groups. The MP approach group maintained more extended knee postures with improved velocity, cadence, and stride length. No differences in pain were detected in clinical scores

Aims

The Precice intramedullary limb-lengthening system has demonstrated significant benefits over external fixation lengthening methods, leading to a paradigm shift in limb lengthening. This study compares outcomes following antegrade and retrograde femoral lengthening in both adolescent and adult patients.