Background. Tension band epiphysiodesis for lower limb length discrepancy in children Planned physeal growth arrest (epiphysiodesis) for the treatment of limb length discrepancy (LLD) in growing children is a well described treatment modality in the literature. We describe our experience of temporary epiphysiodesis using a tension band technique with the “8-plate” in the treatment of LLD in growing children. Aim. The main objective of this study was to confirm whether bilateral 8-plates achieve an epiphysiodesis or not?. Methods and results. This is a prospective study of 27 patients who were treated with 8-plate epiphysiodesis for limb length discrepancy with a mean follow up of 28 months. Perthes disease was the most common underlying pathology for the LLD. The average preoperative LLD was 25.9 mm (15–49 mm). 17 patients successfully corrected to < 15 mm LLD, 5 patients corrected to between 15–20 mm and 5 patients did not correct to with in 15 mm LLD (22.2%). In those patients whom have corrected, the average correction length was 25.6 months with an average correction rate of 1.52 mm per month. There was a trend for insufficient equalisation if the procedure was performed < 1.5 years prior to skeletal maturity. The was also a trend for insufficient equalisation if performed at single physis only (femur or tibia). Complications included one superficial infection and one deep infection following plate removal at the end of treatment. Screw breakage was noticed in one patient. No long term complications were reported. No angular deformity was reported. Conclusion. This study has confirmed that bilateral 8 plates produce an epiphysiodesis. Failures are mainly due to late insertion or single physis usage. Future application depends on demonstrating reversibility when applied to younger children

Purpose: Surgical epiphysiodesis is one technique used to correct lower limb length discrepancy. Methods described include: in situ graft (Phemister, 1993), stapling (Blount, 1949), percutaneous curettage (Bowen, 1984). The purpose of this work was to evaluate a new technique described in 1998 (Metaizeau) which uses two percutaneous transphyseal screws. Material and methods: Forty-two patients (29 boys, 13 girls), mean age 13.1 years underwent the procedure. The cause of leg length discrepancy was unknown (n=12), fracture (n=16), congenital (n=7), other (n=7). Epiphysiodesis using two percutaneous screws was performed on the distal femur (n=24), the proximal tibia (n=7), both (n=11). Stance radiograms were obtained of the lower limbs before the intervention and at last follow-up to measure length of the lower limb, the tibia, and the femur. Difference with the healthy limb was determined as well as the percentage of growth comparing the healthy and epiphysiodesis sides. The operative time, duration of hospital stay and complications were studied. Results: Preoperatively, mean limb length discrepancy was 22.3 mm (10 to 70); at skeletal maturity, the difference measured 11 mm (28 to −20). Mean percent growth from epiphysiodesis to last follow-up was 3.15% for the epiphysidesis side and 6.26% for the contralateral side. Mean operative time was 20 min per bone (15–40). Complication rate was 16% including 7% stiff knee postoperatively with total recovery in two weeks, and 9% discomfort due to the presence of the screws. The growth curves showed that the epiphysiodesis was effective before three months. Mean hospital stay was 1.3 days (1–4). Discussion: The final outcome in terms of leg length discrepancy were comparable with other techniques. The rate of complications appears to be more favourable since there were no infections, no frontal or sagittal deviations, no vascular or nerve injuries, and since all complications resolved without sequelae. This intervention can be proposed as an outpatient procedure. Epithysiodesis is always obtained within three months. Conclusion: Epiphysiodesis using a percutaneous transphyseal screw is a simple method with minimal complications which provides reliable results and many advantages compared with other methods

Purpose of the study: A population of 154 patients was studied to determine the advantages of continuous lengthening for congenital lower limb length discrepancy (LLLD). Material and methods: In a first series, we analyzed 80 progressive lengthenings using the standard rhythm (1 mm daily, 4 lenghtenings per day). In a second series (74 lengthenings) a high-frequency rhythm was used (1 mm daily, 60 lengthenings per day). Mean patient age was 10.3 years. Bone regeneration was not stimulated (either by extemporaneous compression or stable elastic centromedullary nailing) in this population. The automatic lengthening fixator was composed of the two standard pieces of the Ilizarov system and complementary blocks with self-propelled traction rods. Besides simplifying the lengthening procedure, these rods allowed high-frequency correction of associated deformities. Results: Femoral gain was 52 mm on average. For the tibia, the gain was 48 mm on average. For ordinary monosegmentary lengthenings, the healing index was 27.6 d/cm for the femur and 36.0 d/cm for the tibia. For multisegmentary lengthenings with the standard rhythm, the overall healing index was 20.3 d/cm. For patients with high-frequency lengthening, time to healing was shorter. The radiological findings showed the presence of significant bone regeneration which was never inhibited. For monosegmentary lengthenings, the healing index was 22.9 d/cm for the femur and 27.1 d/cm for the tibia. For the multisegmentary high-frequency lengthenings, the overall healing index was 14.7 d/cm. The difference between standard and high-frequency lengthening was significant. In the first series, motion of the adjacent joints was recovered within 12 to 18 months after removal of the fixator. The patients remained in the reclining position during the high-frequency lengthenings and very satisfactory results (complete recovery of joint motion) were obtained 12 months after removing the fixator. In addition, in the second series, there was no impact on the spontaneous growth of the lengthened segments. Discussion and conclusion: Congenital LLLD is generally more difficult to treat than acquired conditions (Damsin et al., Grill et al., Glorion Ch.). The rate of complications remains significant, particularly concerning healing complications and stiffness in the adjacent joints. Our clinical results prove that high-frequency lengthening provides optimal conditions for tissue regeneration. For children with congenital LLLD, continuous lengthening shortens the delay to healing and avoids stiffness in the adjacent joints

Introduction

Circumferential periosteal release is a rarely reported procedure for paediatric limb lengthening. The technique involves circumferential excision of a strip of periosteum from the metaphysis of the distal femur, tibia and fibula. This study aims to determine the mid to long-term effectiveness of this technique.

The 8-plate (Orthofix, SRL, Italy) is a titanium extraperiosteal plate with 2 screws which acts as a hinge at the outer limits of the physis. It has been used for correction of both angular and sagittal deformity around the knee. To our knowledge this is the first study describing the use of 8-plates in leg length discrepancy (LLD) correction.

We aimed to evaluate outcomes of temporary 8-plate epiphysiodesis in LLD, and to assess the complications associated with its usage.

This retrospective study included 30 patients between 2007 and 2010 whom underwent 8-plate epiphysiodesis to address LLD.

Leg length measurements were recorded using erect full leg length scanograms and comparison made between pre-operative, interval and final scanograms. Any deviations of the mechanical axis were also recorded.

During the study period 34 epiphysiodeses were performed on 30 patients. There were 17 males and 14 females. The average age at the time of procedure was 10.7 years (range 3–15). Average time to final follow-up was 24 months (range 52–10). The average pre-operative LLD was 2.5 cm (range 1.5–6 cm). The mean overall rate of correction was 1.0 cm per year. The mean residual LLD at end of treatment was 1.1 cm (range 0–4.5 cm). Two patients experienced genu recurvatum deformity. This was associated with placement of distal femoral plates anterior to the mid-lateral line.

Based on our experience 8-plate epiphysiodesis is a reversible, minimally invasive procedure with reliable results in length correction. However, careful device placement is required to prevent deformity.

Abstract. Introduction. Double-level knee osteotomy (DLO) is a challenging procedure that requires precision in preoperative planning and intraoperative execution to achieve the desired correction. It is indicated in cases of severe varus or valgus deformities where a single-level osteotomy would yield significantly tilted joint line obliquity (JLO). Methods. A single-centre, retrospective analysis of prospectively collected data for 26 patients, who underwent DLO by PSCGs for valgus malaligned knees. Post-operative alignment was evaluated and the delta for different lower limb alignment parameters were calculated; HKA, MPTA, and LDFA. At the two-year follow-up, changes in KOOS sub-scores, UCLA scores, lower limb discrepancy, and mean time to return to work and sport were recorded. All intraoperative and postoperative complications were recorded. Results. The postoperative mean ΔHKA was 0.9 ± 0.9°, the mean ΔMPTA was 0.7 ± 0.7°, and the mean ΔLDFA was 0.7 ± 0.8° (all values with p > 0.05). All KOOS subscores’ mean values were improved to an extent two-fold superior to the reported MCID (all with p < 0.0001). There was a significant increase in the UCLA score at the final follow-up (5.4 ± 1.5 preoperatively versus 7.7 ± 1.4, p < 0.01). The mean time to return to sport and work was 4.7 ± 1.1 and 4.3 ± 2.1 months, respectively. There was an improvement in Lower-limb discrepancy preoperative (LLD = 1.3+/−2cm) to postoperative measures (LLD= 0.3 +/− 0.4 cm) p=0.02. Conclusion. DLO is effective and safe in achieving accurate correction in bifocal valgus malaligned knees with maintained lower limb length and low complication rate with no compromise of JLO

Introduction. The reconstruction of the knee in growing children considers many options and the chosen solution is often patient (or surgeon) based. Megaprostheses represent a reliable solution but quite expensive in the non-invasive growing version and not free from complications. In an Italian reference center for Bone and Soft tissue sarcomas, following the experience of Rizzoli Institute in Bologna, we performed the reconstruction with a resurfaced allograft for the distal femur or the proximal tibia in selected patients. The aim of the study is to confirm the reliability of this technique and to identify its potential advantages and indications. Methods. Among 60 children below 16 years old with bone sarcomas (39 osteosarcomas, 21 Ewing's sarcomas, age range 4–16) treated since 2007, 35 cases were around the hip and the knee. 7 pediatric knees (age range 5–12 ys) with the tumor involving the epiphysis were reconstructed using a resurfaced allograft for distal femur (2) or proximal tibia (6) leaving intact the other half of the joint. Functional outcome (MSTS score), complication rate, and oncologic follow up were evaluated. Results. Oncologic follow up has been regularly conducted (range 2–9 years). No patient died of disease or developed a local recurrence. Two patients are alive with stable lung disease. Mean MSTS score was 32. No complications such as delayed union at the junction allograft-host bone, segmental deformities, fractures of the allograft, or infection have been observed. No prosthesis-related complications occurred. One limb length discrepancy with secondary scoliosis and 2 requiring a contralateral epiphysiodesis were also observed. Conclusions. In children older than 12 years old and with an expected lower limb discrepancy within 5 cm an adult megaprostheses eventually oversized is the gold standard; in children younger than 6 years old with an expected limb discrepancy longer than 10 cm the big choice is between an amputation (conventional or rotantionplasty) or a temporary reconstruction for the future implant of a growing megaprostheses. In the range 6–12 years old with an expected limb length discrepancy of 5–10 cm one of the options is the resurfaced allograft. It has been found a reliable solution in our case series with an excellent functional result probably derived from the capsule and ligaments reconstruction. Applying this protocol we observed a low mechanical-implant related complication rate. Comparing our results to Literature data of other techniques (induced membrane technique, distraction epiphysiolisis, custom-made or growing prostheses) we observed a lower reintervention rate. It is not possible to evaluate the infection rate among the different techniques used because of the low number of cases. A revision with a conventional first implant or revision total knee arthroplasty is always feasible reducing mechanical complications from megaprostheses. Further studies with longer follow up are mandatory to obtain an international consensus on reconstructive techniques in children with bone sarcomas around the knee

Introduction. EOS® is a low dose imaging system which allows the acquisition of coupled AP and lateral high-definition images while the patient is in standing position. HipEos has been developped to perform pre-surgical planning including hip implants selection and virtual positioning in functional weight-bearing 3D. The software takes advantage of the real size 3D patient anatomical informations obtained from the EOS exam. The aim of this preliminary study on 30 consecutive THP patients was to analyze the data obtained from HipEos planning for acetabular and femoral parameters and to compare them with pre and post-operative measurements on standing EOS images. Material and methods. Full body images were used to detect spino-pelvic abnormalities (scoliosis, pelvic rotation) and lower limbs discrepancies. One surgeon performed all THP using the same type of cementless implants (anterior approach, lateral decubitus). The minimum delay for post-op EOS controls was 10 months. A simulation of HipEos planning was performed retrospectively in a blinded way by the same surgeon after the EOS controls. All measurements were realized by an independent observer. Comparisons were done between pre and post-op status and the “ideal planning” taking in account the parameters for the restitution of joint offset and femur and global limb lengths according to the size of the selected implants. Regarding cup anteversion, the data included the anatomical anteversion (with reference to the anterior pelvic plane APP) and functionnal anteversion (according to the horizontal transverse plane in standing position). Results. The difference between pre-op and post-op APP angles is not statistically significant (p = 0.85), likewise for the sacral slope (p = 0.3). Thus, there has been no change in the orientation of the pelvis after THP. Comparing the two hips on post-op EOS data shows that the difference in femoral offset is not statistically significant (p = 0.76). However, the femoral length is statistically different (p <0.05) (mean 4mm, 0–12mm). The difference for femoral offset between HipEOS planning and post-op EOS data is not statistically significant (p = 0.58). However, the mean difference is significant (p <0.05) for femur length (5mm), inclination (5°) and anteversion of the cup. The mean post-op anatomic anteversion measured in the APP is 27°, whereas it is 11° with HipEOS planning. The mean functional anteversion of the cup on standing post-op EOS data is 35° while planning it is 17°. Otherwise, differences in femoral anteversion are not significant. Conclusion. The planning tools currently available include only the local anatomy of the hip for THP adjustment. This software integrates weight-bearing position, which allows to consider the impact of spine deformities and length discrepancies. This preliminary study is only retrospective, but it highlights the potential interest this “global planning” particularly for the optimization of acetabular anteversion and length adjustment according to pelvic tilt. Planning using the standing lateral view is interesting not only for visualization of the sagittal curvature of the femur and the detection of potential difficulties, but also for the visual data provided on the sagittal orientation of the cup

Introduction: Although distraction osteogenesis techniques have been used clinically for the treatment of many skeletal conditions with great success over the last 2 decades, one-step larger extent tibial lengthening (> 5 cm) still remains a clinical challenge. In which tension unbalance of bone and soft-tissue may occur, and complications such as foot drop, ankle and knee dysfunction, cartilage injure and secondary osteoarthritis were common. We have designed and manufactured a new lengthener, which allows bone and soft tissue to be lengthened in synchronism, and ankle joint remain in functional position and may move freely during lengthening. Methods: A dynamic cross joint apparatus at ankle level was added to a classic Ilizarov circular four-ring lengthener, the apparatus is consisted of a half ring, two dynamic junctions and an elastic (spring) device. In application pins were inserted into distant and proximal segment of the tibia, also through calcanues, the external fixator with the trans-joint device was then applied. Total 296 patients (age 6–46, average 21), 466 legs, were treated with this new lengthener, among them were 55 cases of infantile paralysis, 38 cases of post-trauma bone defects, 33 cases with congenital dysplasia and 170 cases of chordrodysplasia, rickets, dwarf and short stature (height < 148cm). Unilateral tibia lengthening was performed in 126 legs and bilateral tibia lengthening was performed in 340 legs. Results: Average lengthening for lower limb discrepancy cases was 6.8 cm (2–8cm), and 8.8 cm (8–18cm) for dwarf and short stature. Patients can stand straight and walk during the lengthening. Average movement of ankle joint remained at 10 degree in all cases and x-ray confirmed that average ankle joint space was 2.2 mm (1–4mm). There was no foot drop and ankle joint deformity seen, and in 98% cases ankle joint function fully recovered within 1.5 years after lengthening (6–8 months). Common complications were pinhole infection (25 cases) and broken pin (8 cases). If total lengthening was over 10cm, 70% cases developed slight ankle joint stiffness that would gradually recover after physiotherapy. Severe complications occurred in 5 cases (1%), including nonunion 1 case, mal-union 1 case, bone deformity 1 case and re-fracture 2 cases. All of those cases were cured with satisfactory clinical outcome. Discussion: The challenge of larger range tibial lengthening is mainly the soft tissue complications, such as foot drop, varus and valgus deformity of ankle joint and loss of ankle function. Prolonged soft tissue traction around the ankle joint may lead to increasing cartilage compression, cartilage damage and partial or permanent loss of joint function. Our dynamic lengthener would allow synchronized lengthening of triceps, Achilles tendon and prosterior tibia muscle with tibia, maintain ankle joint space and free ankle movement. This device was simple and easy to apply, with no need of additional Achilles tendon lengthening. Our clinical study has demonstrated that this device drastically reduced the rate of soft tissue complication. This device makes larger extent tibial lengthening (> 5cm) safer and realistic in clinical practice

Limb lengthening and limb reconstruction using the Ilizarov system is a recognized treatment for children with congenital and acquired lower limb discrepancy and/or deformity. It is a complicated, costly, time consuming and challenging procedure for the multidisci-plinary team, the child and their family. Traditional outcome measures for this group of children tend to focus on X-ray appearances, lengthening indices and problems, obstacles and complications occurring during the treatment phase. At the present time there are unanswered questions as to their functional status as adults. The literature does not appear to have addressed this question as yet. For families considering this difficult treatment option, the potential function for their child as an adult may be valuable in the decision making process The aim of this study was to discover the physical, occupational and psychosocial function of a group of young adults who underwent Ilizarov procedures as children at Great Ormond Street Children’s Hospital. Forty young adults, aged 18 – 27 years (mean age 19.9 years), who had Ilizarov procedures between 1992 and 2000, were sent questionnaires. Items included in the questionnaire were taken from the Toronto Extremity Salvage Score (TESS) to assess function and the Pediatric Orthopaedic Society of North America (POSNA) Adolescent Musculoskeletal Functional Health Questionnaire to assess psychosocial and occupational domains. Questions were also included to gather demographic information. A total of 27 responses were received from 14 males and 13 females. Twenty four patients had Ilizarov procedures for limb lengthening or lengthening with deformity correction. Deformity correction only was carried out in three patients. Mean time since treatment was 5.6 years (range 9 – 2 years). A total of 24 tibial frames, 6 femoral, 4 whole leg and 2 foot frames were applied. Four patients had had repeat Ilizarov procedures. Six patients had had previous lengthenings using uniaxial fixators. Functional ability indicators were high but activities such as kneeling, walking up and down slopes or hills, walking long distances and running were significant problems reported by more than half. Assistive devices (crutches, shoe raises, AFO, knee brace) were needed full time by five, with crutches, sticks and wheelchair used occasionally by three others. Seven adults chose not to partake in sporting activity, with a further three finding it extremely hard and two impossible. Swimming was the most popular activity. Activity related pain was uncommon but pain in the limb requiring occasional analgesia was reported. All but one respondent worked full time or were students. Most occupations were office or shop based. Three men were manual workers. Time off work for problems related to their limb problem was minimal. Socialising with friends and family was high with only one respondent expressing extreme difficulty. Four men and five women identified scarring from the Ilizarov treatment as a cause of concern. Ten women and eight men raised body image issues. Twenty six adults said they would recommend Ilizarov treatment to others, if asked. Conclusions: We view this data as important to provide information for use when counselling It weill also help prospective patients and families of expectation for function in adult life

Aims. Meningococcal septicaemia can result in growth arrest and angular deformities. The aim of this case series was to review the pattern of involvement in the lower leg. Patients and Methods. The notes and radiographs of all patients presenting with a growth arrest or deformity affecting the lower leg following meningococcal septicaemia between 1995 and 2010 were reviewed. There were fourteen patients, eight girls and six boys. The mean age of the patients at the time of presentation was 9.6 years. Results. There was a variety of deformities with some patients exhibiting several deformities in the same limb and/or bilateral deformities. Some of the deformities were complex. Nine patients had a lower limb length discrepancy (mean 4.8cms, range: 1 to 13cms). There were a total of 27 lower limb deformities; three patients had bilateral lower limb deformities. In 14 the proximal tibia was involved causing genu varum in 12 cases and genu valgum in two cases. Seven distal tibia deformities all resulted in varus deformity. In all cases, the fibula was spared. Discussion. In this series involvement of the tibial physeal growth plates was frequently asymmetric and with two exceptions resulted in a varus deformity. The medial and anterior proximal tibial physis seems particularly susceptible to the sequelae of meningococcal septicaemia whereas the fibula physeal plates were always spared. These observations confirm the work of other authors and this characteristic pattern of involvement is likely to reflect the vascular anatomy of the physeal plates. The fibula may be protected from damage because of the nature of its blood supply. Modern limb reconstruction techniques, particularly the Spatial frame now permit correction of these complex and difficult deformities

Introduction. Uncemented components necessitate accurate intraoperative assessment of size to avoid complications such as calcar fracture and subsidence whilst maintaining bone stock on the acetabular side. Potential problems can be anticipated pre-operatively with the use of a templating system. We proposed that pre-operative digital templating could accurately assess femoral and acetabular component size. Methods. Pre-operative templating data from 100 consecutive patients who received uncemented implants (Trident cup, Accolade stem) and who were operated on by the senior author were included in the study. Calibrated pelvis anterior-posterior X-rays were templated with Orthoview™ software. Demographic data, templating data (stem and cup size, femoral neck cut), operative records (actual stem and cup size, head size) and post-operative data (femoral stem alignment, radiographic leg length, acetabular cup abduction angle) were collected. Results. There were 51 males and 49 females with a mean age of 60 yrs (SD = 7.3 yrs). Seventy five percent of stems were templated to within 0.5 size and 98% to within 1 size. A total of 80% of cups were templated to within 2mm and 98% to within 4mm. 62% of head length was accurately template. Seven patients were converted from a templated 132° to a 127° femoral prosthesis neck angle. The acetabulum cup abduction angle was 45° (SD = 4.81) and stem alignment was 1.5° (SD = 1.13). The mean lower limb length discrepancy was +0.05mm (SD = 5.1 mm) post-operatively. Conclusion. Digital templating is a accurate method of assessing femoral and acetabular component sizes. This allows surgeons to foresee potential problems and also recognize an intra-operative error when a large discrepancy exists between a trial component and the templated size

Purpose of the study: Data are scarce in the literature on lower limb length discrepancy (LLD) after total hip arthroplasty (THA). This parameter is difficult to evaluated intraoperatively with conventional instruments. In addition LLD after THA is often poorly tolerated and can be a source of legal suites. The purpose of this work was to evaluate the contribution of navigation for controlling lower limb length during implantation of a THA. Material and method: Sixty-five THA were implanted in 63 patients, aged 35–81 years, using a passive navigation system based on a function reference system which controlled the position of the implants and the length of the operated leg. Limb length and femur length were measured radiographically on both sides before and after surgery. The horizontality of the acetabular U lines was measured on the AP view of the pelvis. An independent radiologist made all measurements. Results: The precision of the radiographic measurements was < 3 mm. The precision of the navigation system was < 3 mm. Subjectively, 56 of the 63 patients did not have a feeling of LLD preoperatively. No un programmed difference > 3 mm in leg length between the before and after THA measurements was noted. Preoperatively, seven patients complained of lower back pain related to LLD and three had a compensated shoe measuring 5 to 10 mm. These latter three patients had a horizontal pelvis (< 1) after THA. In all cases, the overall length correction was achieved by adapting the length of the neck. Discussion: In our opinion, not all radiologically determined and/or clinically perceived LLD should be corrected. Care must be taken to ensure that permanent preoperative hip flexion does not perturb limb length measurements. Conclusion: The navigation system used in this series for the implantation of THA was able to control operated limb length with precision

The aim was to study the use of limb reconstruction techniques in the management of Ollier’s Dysplasia over a period of 25 years. This was a retrospective review of case records and radiographs of patients who had lower limb reconstruction for deformity and limb length discrepancy. There were a total of 9 patients of whom 7 had reached maturity and four of these were still under follow up. The major aims of surgery were to correct lower limb length discrepancy and deformity. A total of twenty segments were operated upon. These were 11 femurs and 9 tibiae. In some segments repeated surgery was required. 41 index and 54 secondary procedures were necessary giving an average of 10.5 procedures per patient. The most common problems were difficulty in fixation in abnormal bone, premature consolidation reflecting the rich osteogenic potential and growth related recurrence of deformities and discrepancy. The mean length gained was 13.8 cms per patient. Healing of regenerate occurred with radiologically normal appearance even in chondro-dysplastic areas. All patients who had completed treatment had a satisfactory mechanical axis and the mean length discrepancy was 1.7 cms. Patients with Ollier’s dysplasia appear to respond well to limb reconstructive surgery. It is possible to correct severe limb length discrepancies and angular deformities. Surgeons should be aware of the possibility of premature healing and should consider faster lengthening rates of up to 1.5 mms per day. Distraction should begin early by day 5 or less. Immature patients should be warned about the possibility of recurrence of deformity and possible need for repeated surgery

Introduction: Hip dislocation remains a relevant complication of total hip arthroplasty.The implants position plays a major role, especially cup anteversion.It has been demonstrated that anteversion measured on CTscan depends on the pelvic position in a lying patient. This prospective study evaluates the influence of pelvic tilt according to standing and sitting positions. Material and Methods: The radiological records of 328 consecutive asymptomatic patients with THP were analyzed. These were routine radiological controls of non cemented THP with metal back acetabular implants. All patients had AP and lateral radiographs in standing and sitting position and a “low-dose” CT scan of the pelvis in lying position.Patients were checked for the absence lower limb length discrepancy and lumbosacral junction abnormality. All the measurements were done by two independent observers and averaged. From the standard radiographs, the sacral slope (SS), the acetabular frontal inclination (AFI), and the acetabular sagittal inclination (ASI) were measured in standing, sitting, and lying positions. From the CT scan sections, the anatomical ante-version (AA) was measured in lying position on axial images according to Murray. The results were compared to a previously described protocol replicating standing and sitting positions: CTscan sections were oriented according to sacral slope. Results: We confirmed that the anatomical anteversion (AA), the frontal inclination (FI), and the sagittal inclination (SI) were functional parameter which significantly varied between standing, sitting, and lying positions according to sacral slope variations.The acetabular parameters in lying position highly correlated to the one in standing position, while poorly correlated with sitting position. The difference between the lying and the sitting positions was about 10°, 25°, and 15° for the AA, the AFI, and the ASI respectively.Mean lying anteversion angle was 24.2° (SD6,9°).Posterior pelvic tilt in sitting position, (sacral slope decrease) was linked to anteversion increase (mean value 38,8° - SD 5,4°). Anterior pelvic tilt in standing position (sacral slope increase) was linked to lower anteversion (mean value 31,7° - SD5,6°). Discussion and Conclusions: Our study confirms the interest CTscan sections oriented according to sacral slope.The strong correlation between lying and standing measurements suggests that classical CTscan protocol is relevant for standing anteversion. According to the poor correlation between lying and sitting positions, it is less contributive for the investigation of dislocations in sitting position