Introduction. Orthopaedic rehabilitation of adolescences and young adults with high dislocation of the femur is rather challenging. The role of palliative salvage procedures is controversial enough in the cohort of patients. Materials and Methods. Treatment outcomes of 10 patients with congenital hip dislocation were analyzed. Mean age at intervention was 17,8 years (15–22). The grade of dislocation were assessed according to Eftekhar: type C − 2, type D − 8. The mean baseline shortening was 4.7±0.36 cm. All subjects underwent PSO with the Ilizarov method. Another osteotomy for lengthening and realignment was produced at the boundary of the upper and middle third of the femur. The mean time in the Ilizarov frame was 5.3 months. Results. The mean follow-up was 2.6±.1 years (range, 15 to 32 years). Limb shortening of 1 cm to 1. 1. /. 2. cm was observed in four cases. Functional outcomes according to d'Aubigne-Postel were: Pain 4,4±0,15 points. ROM − 4,1±0,3 points. Walking ability − 4,5±0,2 points. Two cases had good results (15–17 points), and seven patients had fair outcomes (12–14 points). A poor result (7 points) was recorded in one female patient 28 years after PSO followed by THA. Conclusions. Hip reconstruction with the Ilizarov method can be used in specific clinical situations as an alternative salvage procedure to delay THR in young patients with high dislocation of the femur

Introduction. Dislocation is one of the most important complications after primary total hip replacement (THR). The low incidence of this finding makes it difficult to analyse the possible risk factors. The surgical technique can also influence this rate through cup position or an adequate reconstruction of the hip. We assessed the demographic data and radiological reconstruction of the hip related to the appearance of dislocation after primary THR. Material and Methods. 1414 uncemented THRs were recorded from our Local Joint Registry. The mean age of the patients was 60.1 years old (range, 14 to 95), and the mean weight was 73.3 kg (42 to 121). There were 733 men and 974 patients were classified with an activity level of 4 or 5 according to Devane. The most frequent diagnosis was primary osteoarthritis, 795 hips, followed by avascular necrosis 207 hips. An alumina-on-alumina THR was implanted in 703 hips and a metal-on-polyethylene THR in 711 hips. A femoral head size of 28 mm was used in 708 hips and 32 mm in 704. Radiological cup position was assessed using the acetabular abduction angle, the height of the center of the hip, and the horizontal distance of the cup. Cup anteversion was measured according to Widmer and the reconstruction of the center of rotation of the hip according to Ranawat. The radiographic reconstruction of the abductor mechanism was measured using two variables: the lever arm and the height of the greater trochanter. Results. There were 38 dislocations (2.6%) and 11 hips were revised for recurrent instability (0.8%). The probability of not having a dislocation at 20 years was 97.3%. 22 hips that had dislocated were within a box for a cup position of a version between 10º to 25º and an acetabular abduction angle between 35º to 55º (p<0.001). The probability of not having a dislocation at 20 years was 98.48% for the cups within the box and 93.9% for cups outside the box (p<0.001, Log Rank test). 21 hips that had dislocated were within a box for a height of the greater trochanter between −2 mm to 5 mm and a lever arm between 56 to 64 mm (p<0.001). The probability of not having a dislocation at 20 years was 98.33% for the hips within the box and 94.6% for hips outside the box (p<0.001, Log Rank test). Adjusted Cox regression analysis showed that alumina-on alumina THR tended to dislocate less than metal-on-polyethylene THRs (p=0.061, Hazard Ratio: 2.238, Confidence Interval 95% 0.964–5.195), and hips outside the box evaluated for cup position and outside the lever arm and height of the greater trochanter box) had a higher risk for dislocation (p<0.001, HR: 3.418, CI 95% 1.784–6.549, and, p<0.001, HR:2.613, CI 95% 1.357–5.032, respectively). Conclusions. A proper reconstruction of the hip is essential to decrease the risk for dislocation after primary THR. The choice of the bearing surface may affect this risk. The weakness of the abductor muscles of the hip may be one of the most important causes for dislocation

In cemented total hip arthroplasty, the cement-bone interface can be considerably degraded in less than one year in-vivo service (Figure 1). This makes the interface much weaker relative to the direct post-operative situation. Retrieval studies show that patients do, to a certain extent, not suffer from the degraded cement-bone interface itself. It is, however, unknown whether the degraded cement-bone interface affects other failure mechanisms in the cemented hip reconstruction. A good understanding of the mechanics of the cement-bone interface is therefore essential. The aim of this study was to investigate the mechanics of the cement-bone interface in the direct post-operative and degraded situation by the utilization of finite element analysis (FEA) and laboratory experiments. It was subsequently analyzed how the mechanics of the cement-bone interface affect failure of the cement mantle in terms of crack formation. In order to investigate the mechanical response of the cement-bone interface, laboratory prepared (direct post-operative state) and postmortem (degraded state) specimens were loaded in various directions in the laboratory and FEA environment. From all specimens, multiple interface morphology parameters were documented, which were related to the interfacial response and subsequently converted to a numerical cohesive model. As a validation, this cohesive model was implemented into two FEA models of transverse sections of cemented hip reconstructions with distinct mechanical characteristics (Figure 2). Finally, the differences in fatigue crack formation in a complete hip reconstruction were determined by varying the cement-bone interface compliance (Figure 3). When loaded in multiple directions, the interface compliance could not be related to the cement interdigitation depth (r. 2. =0.08). However, compliance did correlate to the gap thickness between the bone and cement (r. 2. =0.81) and the amount of interfacial contact (r. 2. =0.50). Surprisingly, for the same amount of contact, the interface was more compliant in degraded state than in the direct post-operative state. The mechanical response of the experimental and FEA cement-bone interface tests could, independent on the direct post-operative or degraded state, successfully be described by a cohesive model. The cohesive model was even more confirmed by the successful reproduction of the mechanics of the retrieved transverse sections. When the cohesive model was implemented in a complete reconstruction, we found that a compliant cement-bone interface resulted in considerably more fatigue cracks in the cement mantle than a very stiff interface. This study showed that an increased compliancy of the cement-bone interface results in an increase of cement cracks in the cement mantle. It is therefore crucial to minimize the interfacial gaps and, as a result, increase the amount of contact between the bone and cement to generate a stiff cement-bone interface. It is, unfortunately, unknown how this well fixed interface can be maintained. We finally conclude that the derived cohesive model of the cement-bone interface can be used for multiple applications in orthopaedics, including pre-clinical of implants and patient specific studies of failed cemented reconstructions

Introduction

Metal-on-polycarbonate urethane (MPU) is a cutting-edge new bearing technology for hip arthroplasty. The acetabular component consists of a 2.7mm-thick polycarbonate-urethane liner inserted into a specially manufactured uncemented titanium shell coated with hydroxyapatite [(HA) Fig. 1]. The liner is pliable and biomechanically mimics human cartilage. In vitro studies have shown minimal wear, fluid film lubrication, physiological load transmission and shock absorption capacity equal to the normal hip. This system includes prosthetic heads of a diameter 12mm less than the socket diameter. The aim of this study was to clinically assess patients treated with this novel technology in a retrospective single centre study.

The childhood hip conditions of Developmental Dysplasia, Legg-Calve-Perthes Disease and Slipped Capital Femoral Epiphysis have a wide spectrum of anatomical outcomes following childhood treatment; ranging from morphologies, which result in normal hip function throughout life, to severely deranged morphologies, which result in pain and disability during childhood and adolescence. Some of these outcomes are as a result of well-intentioned interventions that result in catastrophic complications.

In 2003, after years of working with impingement complicating periacetabular osteotomies and building on the work of William Harris, Reinhold Ganz published his concepts of ‘cam’ and ‘pincer’ hip impingement, and how these anatomical morphologies resulted in hip arthritis in adulthood. These concepts of impingement were added to his previous published work on hip instability to provide a comprehensive theory describing how hip arthritis develops on the basis of anatomical abnormalities. Surgical techniques have been developed to address each of these morphological pathologies.

Ganz's concepts of hip impingement and instability may be applied to severe paediatric hip deformities to direct reconstructive joint preserving surgery to both the femur and the acetabulum. Ganz's surgical approaches have also been refined for use in paediatric hip surgery to allow radical reshaping salvage osteotomies to be performed on the developing femoral head with minimal risk of the devastating consequence of vascular Necrosis.

Introduction

Instability accounts for one third of revision total hip arthroplasty(rTHA) performed in the United Kingdom. Removal of well-fixed femoral stems in rTHA is challenging with a risk of blood loss and iatrogenic damage to the femur. The Bioball Universal Adaptor (BUA) (Merete, Germany), a modular head neck extension adaptor, provides a mechanism for optimisation of femoral offset, leg length and femoral anteversion. This can avoid the need for femoral stem revision in selected cases. There is a relative paucity of clinical data available with the use of this device.

The Pelvic Support Osteotomy (PSO) or Ilizarov Hip Reconstruction(IHR) is well described for the treatment of septic sequelae of infancy. The purpose of this study was to clinically, functionally and radiographically assess our short-term results of this procedure.

25 patients (16 boys, 9 girls) who had undergone a IHR using the Ilizarov/TSF construct over a period of 10 years for a variety of pathologies were reviewed. The mean age at surgery was 15 years 4 months. The pre-operative diagnoses were SCFE(10), hip sepsis (6), DDH (6) and Perthes (3). All had significant leg length discrepancies, 16 had a painful stiff hip, 6 had a painful mobile hip and 3 had a painless unstable hip. At surgery, a mean measured proximal valgus angle of 51° and a mean extension angle of 15° was achieved. Distal femoral lengthening averaged 4.2 cm and distal varus correction was a mean of 8°. The mean fixator time was 173 days.

At a mean of 2 years and 7 months follow-up the lower-extremity length discrepancy had improved from a mean of 5.6 cm apparent shortening to 2.3 cm. Trendelenberg sign was eliminated in 18/25 cases. Improvements in range of hip movements and gait parameters were observed. Stance time asymmetry, step length asymmetry, pelvic dip and trunk lurch improved significantly. One patient had conversion to a total hip replacement after 7 years, 4 patients required re-do PSO due to remodelling of the proximal osteotomies, two had heterotopic ossification and two had significant knee stiffness due to lack of compliance.

The early results of IHR are encouraging to equalise limb lengths, negate trendelenburg gait, provide a mobile hip with a reasonable axis and the possibility of conversion to THR in the future if needed. Complications need to be anticipated and the effects of remodelling and maintaining adequate knee range of motion must be emphasised.

A retrospective single-center review has been performed to gather clinical data on the use of polycarbonate-urethane (PCU) as an articulating bearing material inside a cobalt-chrome (Co-Cr) press-fit acetabular shell.

As of January 2010, the Co-Cr shell and PCU liner have been implanted into 25 total hip patients which were retrospectively followed. The indications for use were in 24 cases of osteoarthritis, and 1 revision case. No patient was lost to follow-up. The average follow-up time was 17.6 months (range 8-27). The average age of these patients was 67.9 (range 44-84), the sex distribution was 14 female and 11 male patients, of whom 15 were right and 10 left side. 24 patients received a total hip replacement with the metal acetabular system and a cementless femoral stem and 1 patient received the metal acetabular shell coupled to a cemented resurfacing head.

None of the cases has had a dislocation, revision, dislodgement, or infection. At follow-up, the mean Harris hip score was 98 points (80-99). X-rays showed good bone-implant contact without any osteolysis or bone rarefaction.

A detailed review of the clinical data of these patients shows that a PCU liner inserted into a Co-Cr acetabular shell is as safe and effective as other commonly used acetabular shells in other total hip systems currently available. No new or unintended adverse or device-related events were discovered with the clinical use of PCU in a Co-Cr acetabular shell.

Introduction. Total hip arthroplasty (THA) dislocation has been associated with different risk factors. The main difficulty in analysing dislocation is its low rate of incidence, necessitating large series for study. We assessed factors related with patients, implant characteristics, and quality of the hip reconstruction to better identify their influence on the THA dislocation rate. Material and Methods. Dislocations in 2,732 THAs performed between 2001 and 2016 were assessed with regard to factors related with the patient (gender, age, preoperative diagnosis, lumbar pathology); the implant (femoral head size, bearing surface, stem offset, femoral head/neck ratio); and the surgical technique (approach, cup and stem position, and abductor mechanism reconstruction). Regression analysis was used for different risk factors and Kaplan-Meier for survival analysis. Results. After ERAS implementation, opioid consumption decreased for hospital day one (49.5MME to 35.4MME; p=0.000) and overall hospitalization (79.5MME to 59.5MME; p=0.000). Average LOS decreased (57.84hrs to 51.87hrs; p=0.011), blood transfusion rate was unchanged (4.25% to 3.81%; p=0.725), and disposition to home over skilled nursing facility increased (80.4% to 82.5%; p= 0.022). Unplanned return-to-hospital encounters were unchanged (8.51% to 8.88%; p=0.8486). Readmission trended up during postoperative days 0–30 and trended down during postoperative days 31–90. (1.42% to 2.96%; p=0.1074) and (1.21% to 0.85%; p=0.5748), respectively. There were 92 dislocations (3.4%), of these, 62 were treated conservatively (2.3%) and 30 surgically (1.1%). Survivorship analysis for dislocation was 96.0% (95% CI:95.0–97.0) at 17 years. Among patient-related factors, greater age (p=0.001), lower activity level (p=0.001) and lumbar fusion (p<0.001) were associated with a higher dislocation rate. Among implant-related factors, a ceramic-on-ceramic THA (p<0.001) and a femoral size of 32 or 36 mm in diameter had lower dislocation rates. With regards to surgical technique, a greater acetabular abduction angle (p=0.001) and a greater distance to the hip anatomic center (p=0.006) had higher dislocation rates. A cup position outside Lewinnek´s safe zone (p<0.001) and the abductor mechanism window (p<0.001) also had a higher dislocation rate. Multivariate analysis revealed that only significant lumbar pathology (p=0.001) and lumbar fusion (p<0.001) were significant dislocation-related factors among patient-related factors. Poor reconstruction of the hip rotation (p=0.035), a cup position outside of Lewinnek's safe zone (p<0.001) and the abductor mechanism window (p<0.001) were significantly associated with a higher dislocation risk among surgical technique-associated factors. Conclusions. Significant lumbar spine pathology increases the rate of dislocation. A proper reconstruction of the hip, including appropriate cup position and rotation centre reconstruction of the hip are essential to decrease the risk of dislocation after primary THA. The weakness of the abductor muscles is also an important cause for dislocation

Introduction. Hip arthrodiastasis for paediatric hip conditions such as Perthes disease is growing in popularity. Intended merits include halting the collapse of the femoral head and maintaining sphericity by minimising the joint reaction force. This can also be applied to protecting hip reconstruction following treatment of hip dysplasia. Our aim was to assess functional outcomes and complications in a cohort of paediatric patients. Materials and Methods. A retrospective single-surgeon cohort study was performed in a University teaching hospital from 2018–2021. Follow-up was performed via telephone interview and review of patient records. Complications, time in frame and functional scores using the WOMAC hip score were recorded. Results. Following review, 26 procedures were identified in 24 patients. Indications included 16 cases of Perthes disease, 4 following slipper upper femoral epiphysis, 3 avascular necrosis, and single cases following infection, dysplasia and a bone cyst. Pre-treatment WOMAC scores averaged 53.9, improving to 88.5 post-removal. Pin site infections were encountered in 11 patients, all treated with oral antibiotics. Two patients required early removal of frame due to pin loosening. Average time in frame was 3.9 months. Conclusions. This series displays how hip arthrodiastasis can be used to manage paediatric hip conditions. Complex reconstructions may be required in patients with severe deformity following perthes disease, DDH or SUFE. The use of arthrodiastasis in these patients aims to protect the reconstruction and potentially improve outcomes. A dedicated team of specialist nurses, physiotherapists and psychologists are crucial to the treatment program

The Superior Hip Approach allows for safe reconstruction of the hip while maximizing preservation of the surrounding soft tissues. The procedure involves an incision in the hip joint capsule posterior to the gluteus medius and minimus and anterior to the short external rotators. The technique involves preparation of the femur in-situ through the superior femoral neck and then excision of the femoral head, which avoids the attendant soft tissue dissection or injury associated with dislocation of the native hip. After component implantation, the capsule is closed anatomically. Two separate studies have demonstrated that over a 90-day period, patients whose hips were replaced using this technique consumed the least amount of cost of any patients treated by hip arthroplasty in the Commonwealth of Massachusetts. One study assessed all hips replaced in patients insured by Medicare over a four-year period. In this study, patients treated by the Superior Hip Approach were less costly by an average of more than $7,000 over 90 days. A second study assessed all hips replaced in patients insured by a large private insurer. This study showed again that patients treated by the Superior Hip Approach were the lowest cost patients. Notable, the cost on average was $23,500 less per procedure compared to the most well-known medical care organization in the state or roughly half the cost. Lower cost was due to both lower inpatient cost and reduced utilization of post-acute care resources. Since reduced resource utilization is a direct measure of accelerated recovery, these economic data combine with clinical outcomes and anatomical studies that document that the Superior Hip Approach is a reliable technique for achieving optimal results following THA

INTRODUCTION. The Dorr Bone Classification, devised in 1993 is commonly used to categorize bone types prior to hip reconstruction. The purpose of the present study is to quantify the Dorr classification system using 4 morphologic parameters – morphologic cortical index (MCI), canal-flare index (CFI), canal-bone ratio (CBR), and canal-calcar ratio (CCR). METHODS. 816 hips were reviewed. Demographic data reviewed includes age, sex, and laterality. Each hip was reviewed by 2 separate evaluators for Dorr classification. The MCI, CCR, CBR, and CFI were calculated for each hip on anteroposterior radiographs (Fig 1). One-way ANOVA statistical analysis was used to examine if there are mean differences for each measurement. IRB approval was obtained before collection of data. RESULTS. The average age of patients was 61 (range 20–96). There were 367 left hips and 449 right hips. The prevalence of Dorr A was 45.8%. The prevalence of Dorr B bone was 38.9% and of Dorr C bone was 15.3%. One-way ANOVA analysis confirmed the mean differences for each measurement. Measurements of the MCI, CCR, CBR, and CFI were statistically significantly different between the three types of bone. The MCI and CFI were significantly higher in Type A than Type B and higher in Type B than Type C. The CBR and CCR were significantly lower in Type A than Type B and lower in Type B than Type C. DISCUSSION. To our knowledge, the present study is the first to attempt to quantify the Dorr Bone classification system using MCI, CCR, CBR, and CFI using a large series of patients. Classification of the proximal femur geometry is important as it may play a role in implant fixation for patients undergoing total hip arthroplasty (THA). Furthermore, this information can be used to guide future implant choices

Introduction. The success of cementless total hip arthroplasty (THA) depends on the primary stability of the components. One of the biomechanical factors that comes into play is the mechanical quality of the bone. To our knowledge, there are no reported studies in the literature analyzing the impact of the preoperative bone mineral density on the outcomes of cementless THA. The goal of the study was to analyze the clinical results at 2 year follow-up according to the preoperative cancellous bone mineral density (BD). Our hypothesis was that the clinical outcomes were correlated to the BD. Material and methods. From January to June 2013, a prospective study included patients who underwent a cementless THA using a proximally shortly fixed anatomic stem. A 3D preoperative CTscan-based planning was performed according to the routine protocol using the Hip-Plan software in order to determine the hip reconstruction goals as well as the implants size and position. The Hounsfield bone density (BD) of the metaphyseal cancellous bone was computed in a volume (of 1 mm thick and of 1cm² surface) at the level of the calcar 10 mm above the top of the lesser trochanter and laterally to the medial cortical (Figure 1). Intra-and inter-observer repeatability measurements were performed. Patients were clinically assessed at 2 years follow-up using self-administered auto-questionnaires corresponding to the Harris and the Oxford scores. A Multivariate statistical analysis assessed correlations between clinical scores, age, gender, body mass index, and BD. Results. 50 patients were included consisting of 29 men and 21 women, with an average age of 62 ± 12 years and an average BMI of 25.8. The average preoperative BD was 69.4 ± 54 HU. At 2 years follow-up, the hip function scores were significantly correlated with the preoperative BD (0.42, p = 0.002) and the age (0.39, p = 0.005). However, there was no significant correlation between BD and BMI. Discussion Bone density appears to be an important parameter to consider when planning THA. This highlights also the importance of preoperative image calibration. Conclusion. The functional outcomes after cementless THA are correlated with preoperative cancellous bone density. Bone density needs to be integrated into THA 3D planning

Intro. Sciatic nerve injury (SNI) is a rare and potentially devastating complication after total hip arthroplasty (THA). Neural monitoring has been found in several studies to be useful in preventing SNI, but can be difficult to practically implement during surgery. In this study, we examine the results of using a handheld nerve stimulator for intraoperative sciatic nerve monitoring during complex THA requiring limb lengthening and/or significant manipulation of the sciatic nerve. Methods. We retrospectively reviewed a consecutive series of 11 cases (9 patients, 11 hips) with either severe developmental dysplasia of the hip (Crowe 3–4) or other underlying conditions requiring complex hip reconstruction involving significant leg lengthening and/or nerve manipulation. Sciatic nerve function was monitored intra-operatively with a handheld nerve stimulator by obtaining pre- and post-reduction conduction thresholds during component trialling. The results of nerve stimulation were then used to influence intraoperative decision- making (downsizing components, shortening osteotomy). Results. No permanent postoperative sciatic nerve complication occurred, with an average increase of 28.5mm in limb length, ranging from 6 to 51mm. In 2 out of 11 cases, a change in nerve response was identified after trial reduction, which resulted in an alternate surgical plan (femoral shortening osteotomy and downsizing femoral head). In the remainder cases, the stimulator demonstrated a response consistent with the baseline assessment, assuring that the appropriate lengthening was achieved without SNI. One patient had a transient motor and sensory peroneal nerve palsy, which resolved within two weeks. Conclusions. The intraoperative use of a handheld nerve stimulator facilitates surgical decision-making and can potentially prevent SNI. The real-time assessment of nerve function allows immediate corrective action to be taken before nerve injury occurs

Introduction. Implantation of total hip replacement (THR) remains a concern in patients with developmental dysplasia of the hip (DDH) because of bone deformities and previous surgeries. In this frequently young population, anatomical reconstruction of the hip rotation centre is particularly challenging in severe, low and high dislocation, DDH. The basic principles of the technique and the implant selection may affect the long-term results. The aim of the study was to compare surgical difficulties and outcome in patients who underwent THR due to arthritis secondary to moderate or severe DDH. Material and Methods. We assessed 131 hips in patients with moderate DDH (group 1) and 56 with severe DDH (Group 2) who underwent an alumina-on-alumina THR between 1999 and 2012. The mean follow-up was 11.3 years (range, 5 to 18). Mean age was 51.4 years in group 1 and 42.2 in group 2. There were previous surgery in 5 hips in group 1 and in 20 in group 2 (p<0.001). A dysplastic acetabular shape type C according to Dorr and a radiological cylindrical femur were both more frequent in group 2 (in both cases p<0.001). We always tried to place the acetabular component in the true acetabulum. Smaller cups (p<0.001), screw use for primary fixation (p<0.001) and bone autograft used as segmental reinforcement in cases of roof deficiency (p<0.001) were more frequent in group 2. Radiological analysis of the cup included acetabular abduction, version and Wiberg angles, horizontal, vertical, and hip rotation centre distances, and acetabular head index. Abductor mechanism reconstruction according to the lever arm distance and height of the greater trochanter was also evaluated. Cup placement within or outside Lewinnek´s safe zone was recorded. Two-way ANOVA with repeated measures were used to analyse clinical and radiological changes. Results. There were 6 cups revised for aseptic loosening, three in each group. Survivorship analysis at 15 years: 97.3% (95% IC 94.4–100) for group 1 and 93.0% (95% IC 85.2–100) for group 2 (p=0.186). Despite a worse preoperative status in group 2, the outcome improved similarly in both groups. Postoperative radiological measurements were better in group 1 except for acetabular acetabular and version angles. The improvement from the pre- to the post-operative situation was greater in group 2 except for the height of the greater trochanter. Acetabular component placement within the Lewinnek´s safe zone was similar in both groups. All revised cups were outside this zone. No osteolysis or complications related to the use of ceramics were found. Conclusions. The alumina-on-alumina THR provided good results in both groups including pain relief and functional improvement. Placing the acetabular component in the true acetabulum inside the Lewinnek safe zone can ensure a good result in these challenging dysplastic hips

Introduction. According to the literature, the gait does not return to normal after THA. However, the three-dimensional hip anatomy is usually not assessed before and after surgery. Our hypothesis was that an accurate reconstruction of the hip anatomy, based on a three-dimensional preoperative planning, may normalize the gait after THA. Material and method. 18 consecutive patients, graded Charnley A, aged of 59.3 ±13 years, underwent THA for unilateral primary osteoarthritis using a direct anterior minimal invasive approach. A 3D computerised planning was performed, the implants size and position were chosen in order to restore, the leg length, the off-set, the centre of rotation and the anteversion angles (Figure 1). At 1 year follow up, a 3D gait analysis was performed and included 29 parameters describing the kinetics and the kinematics. Each patient was compared to himself using the contra-lateral healthy hip, as well as to a group of 13 healthy volunteers. Results. The real implants were the same than the ones planned in all the patients. The hip anatomy was restored with a high accuracy: 0.1±3mm for the hip rotation centre, −1.4±3 mm for the leg length and −0.9±3.5mm for the femoral offset. With respect to the gait, there was no significant difference between the operated side and the control-lateral leg. When compared to the control group, all the patients were within the normal range for all the parameters (Figure 2). Discussion and conclusion. The results suggest that the combination of an accurate 3D reconstruction and a direct anterior minimal invasive approach may allow to achieve a normal gait after THA at one year follow up

Background and aim. Total hip replacement (THR) in young patients has been associated to higher revision rates than in older population. Different conditions may lead to end-stage arthritis of the hip in these patients. We compared the clinical and radiological outcome of two different groups of young and very young patients who underwent a ceramic-on-ceramic THR. Patients and Methods. 120 hips were prospectively followed for a mean of 10.4 years (range, 5 to 17). 38 patients (46 hips) were less than 30 years old (group 1), and, 68 (74 hips) were between 31 and 40 years old (group 2). Weight (p<0.001) and physical activity level were greater in group 2 (p<0.001). Preoperative function (p=0.03) and range of mobility (p=0.03) were worse in group 1. Primary osteoarthritis was not found in any case. Rheumatoid juvenile arthritis was the most frequent diagnosis in group 1 and avascular necrosis of the femoral head in group 2. A femoral funnel-shaped type 1 according to Dorr was more frequent in group 2 (p=0.04). The same ceramic-on-ceramic uncemented THR was used in all cases. Screws for cup fixation were only used when strictly needed. We analysed the clinical results according to the Merle-D´Aubignè and Postel scale, the postoperative radiological reconstruction of the hip and the radiological appearance of cup loosening. Kaplan-Meier survivorship analysis was used to estimate the cumulative probability of not having a revision surgery. Results. Screw use required to obtain a secured interference fit of the acetabular component was found more frequently in group 1 (p=0.01). Postoperative pain (p=0.002) and function (p=0.002) were better in group 1. Mean acetabular abduction angle of the cup was greater in group 1 (p=0.03) and reconstruction to the hip rotation center according to Ranawat (p=0.01) was better in group 2. Placement of the acetabular component inside the Lewinnek´s zone and stem position were similar in both groups. No hips were revised due to complications related to ceramic or to stem loosening. Three cups were revised for aseptic loosening in group 1 and four in group 2. The survival rate for cup aseptic loosening at 15 years was 92.3% (95% CI: 83.7 to 100) for group 1 and 93.1% (95% CI: 85.3 to 99.9) for group 2 (Log rank, p=0.88). Conclusion. Ceramic-on-ceramic uncemented THR is an excellent option for young and very young patients. Despite worse preoperative conditions in patients under the age of 30 years, a similar clinical outcome was found in this series

Introduction. In the evaluation of patients with pre-arthritic hip disorders, making the correct diagnosis and identifying the underlying bone pathology is of upmost importance to achieve optimal patient outcomes. 3-dimensional imaging adds information for proper preoperative planning. CT scans have become the gold standard for this, but with the associated risk of radiation exposure to this generally younger patient cohort. Purpose. To determine if 3D-MR reconstructions of the hip can be used to accurately demonstrate femoral and acetabular morphology in the setting of femoroacetabular impingement (FAI) and development dysplasia of the hip (DDH) that is comparable to CT imaging. Materials and Methods. We performed a retrospective review of 14 consecutive patients with a diagnosis of FAI or DDH that underwent both CT and MRI scans of the same hip with 3D reconstructions. 2 fellowship trained musculoskeletal radiologists reviewed all scans, and a fellowship trained hip preservation surgeon separately reviewed scans for relevant surgical parameters. All were blinded to the patients' clinical history. The 3D reconstructions were evaluated by radiologists for the presence of a CAM lesion and acetabular retroversion, while the hip preservation surgeon also evaluated CAM extent using a clock face convention of a right hip, location of femoral head blood supply, and morphological anterior inferior iliac spine (AIIS) variant. The findings on the 3D CT reconstructions were considered the reference standard. Results. Of 14 patients, there were 9 females and 5 males with a mean age 32 (range 15–42). There was no difference in the ability of MRI to detect the presence of a CAM lesion (100% agreement between 3D-MR and 3D-CT, p=1), AIIS morphology (p=1, mode=type 1 variant), or acetabular retroversion (85.7%, p=0.5). 3D-MR had a sensitivity and specificity of 100 in detecting a CAM lesion relative to 3D-CT. Four CT studies were inadequate to adequately evaluate for presence of a CAM. Five CT studies were inadequate to evaluate for location of the femoral head vessels, while MRI was able to determine location in those patients. In the 10 remaining patients for presence of CAM, and nine patients for femoral head vessel location, there was no statistically significant difference between 3D-MR and 3D-CT in determining the location of CAM lesion on a clock face (p=0.8, mean MRI = 12:54, mean CT: 12:51, SD = 66 mins MR, 81 mins CT) or in determining vessel location (p=0.4, MR mean 11:23, CT mean 11:36, SD 33 mins for both). Conclusion. 3D MRI reconstructions are as accurate as 3D CT reconstructions in evaluating osseous morphology of the hip, and may be superior to CT in determining other certain clinically relevant hip parameters. 3D-MR was equally useful in determining the presence and extent of a CAM lesion, acetabular retroversion, and AIIS morphologic variant, and more useful than 3D CT in determining location of the femoral head vessels. In evaluating FAI or hip dysplasia, a 3D-MR study is sufficient to evaluate both soft tissue and osseous anatomy, sparing the need for a 3D CT scan and its associated radiation exposure and cost

Introduction. Uncemented press-fit cups provide bone fixation in primary total hip replacement (THR). However, sometimes screws are needed to achieve primary stability of the socket. We analyzed biomechanical factors related to press-fit in seven cup designs and assessed whether screw use provides similar loosening rates to those of the press-fit technique. Materials y Methods. From a series of 1,350 primary uncemented THRs using seven different press-fit cup designs (a dome loading hemispheric cup and bi- or tri- radius cups), we only analyzed the 889 diagnosed of primary osteoarthritis. All cases were operated by the same surgical team. The use of screws was decided intraoperatively based on cup stability according to the pull-out test. There were 399 female and 490 male patients with a mean age of 65 years old. The mean follow-up was 8.6 years (5–13 years). The reconstruction of the hip rotation center was evaluated according to Ranawat. Results. Screws were required in 223 (25.1%) of the surgeries: 35% of all dome-loaded cups and less frequently with other cup designs (range 18%-24%) (p<0.001) All hips showed good clinical results and radiological bone fixation. Screws were used more frequently in women (p<0.001). Adjusted multivariate analysis revealed that female patients (p<0.001, Odds Ratio (OR): 1.98; 95% Confidence Interval (CI) 1.34–2.95), hips with one of the hemispherical cup designs (p=0.01, OR: 2.51; 95% CI 1.33–5.33) and a greater distance to the rotation hip centre (p<0.001, OR: 1.25; 95% CI 1.15–1.35) had a higher risk for screw use. Every increase of 5 mm in this distance increased the risk of screw use by three (LI=2–4.5). Conclusions. Gender, cup design and reconstruction of the rotation center of the hip determine the primary stability of the cup in uncemented THR. The use of screws, when necessary, provides similar results than the press-fit technique

Background. Robotics assisted surgery are tools that provide successful biomechanical reconstruction of the hip. We compare the accuracy of cup placement in the safe zones described by Lewinnek et al. and Callanan et al., leg length discrepancy (LLD) and global offset (GO) measurement in total hip arthroplasty (THA) using five diferent image guided techniques performed by six diferent surgeons. Methods. Between June 2008 and April 2014, 2330 THRs were performed by six different surgeons. Ninety-three (4.69%) patients underwent robotic-assisted THA anterior approach, 135 (6.8%) had robotic-assisted THA posterior approach, 942 (47.5%) patients underwent fluoroscopic guided THA anterior approach, 708 (35.7%) had THA without guidance using posterior approach, 43 (2.1%) patients underwent navigation-guided anterior approach and 59 (2.9%) patients underwent radiographic-guided posterior approach THAs (Figure 1). Results. One Thousand, nine hundred-eigthy patients met the inclusion and exclusion criteria. Robotic guidance groups had a significantly greater percentage of hips in the Lewinnek's and Callanan's safe zone (p < 0.005). Between robotic guidance groups, the group with posterior approach has more cups placed in the Lewinnek's and Callanan's safe zone (p < 0.005). The frequency of hips within the Lewinnek's safe zone was significantly greater in the navigation guided group, compared to the other groups except robotic guided (p < 0.05) (Figure 2). Sixty-four (3.2%) of our cases were with LLD greater than or equal to 10mm, five of those cases were (8.5%) in the group treated with x-ray guidance (p < 0.05) (Figure 3). The mean GOD for the overall cohort was 4.0mm ± 0.4mm (p < 0.0001) (Figure 3). Mean ages of patients in the treatment groups were significantly different (p < 0.0001). Conclusion. Robotic assisted surgery was more consistent than the other techniques in placing the acetabular cup into the Lewinnek and Callanan safe zone. In general, we can conclude that the useof the robot in hip arthroplasty surgery is more accurate fulfilling the goals needed to actual hip arthroplasty. We know new technologies will be developed