Introduction

Sagittal pelvic tilt (SPT) can change with spinal pathologies and fusion. Change in the SPT can result in impingement and hip instability. Our aim was to determine the magnitude of the SPT change for hip instability to test the hypothesis that the magnitude of SPT change for hip instability is less than 10° and it is not similar for different hip motions.

Introduction

Most of studies on Total Hip Arthroplasty (THA) are focused on acetabular cup orientation. Even though the literature suggests that femoral anteversion and combined anteversion have a clinical impact on THA stability, there are not many reports on these parameters. Combined anteversion can be considered morphologically as the addition of anatomical acetabular and femoral anteversions (Anatomical Combined Anatomical Anteversion ACA). It is also possible to evaluate the Combined Functional Anteversion (CFA) generated by the relative functional position of femoral and acetabular implants while standing. This preliminary study is focused on the comparison of the anatomical and functional data in asymptomatic THA patients.

Purpose

Minimally invasive anterolateral approach (ALA) for total hip arthroplasty (THA) has gained popularity in recent years as better postoperative functional recovery and lower risk of postoperative dislocation are claimed. However, difficulties for femur exposure and intraoperative complications during femoral canal preparation and component placement have been reported. This study analyzes the anatomical factors likely to be related with intraoperative complications and the difficulties of access noted by the surgeons through a modified minimally invasive ALA. The aim is to define the profile for patient at risk of intraoperative complications during minimally invasive ALA.

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.

Introduction

Post op cup anatomical and functional orientation is a key point in THP patients regarding instability and wear. Recently literature has been focused on the consequences of the transition from standing to sitting regarding anteversion, frontal and sagittal inclination. Pelvic incidence (PI) is now considered as a key parameter for the analysis of sagittal balance and sacral slope (SS) orientation. It's influence on THP biomechanics has been suggested. Interestingly, the potential impact of this morphological angle on cup implantation during surgery and the side effects on post op functional orientation have not been studied.

Our study explores this topic from a series of standing and sitting post-op EOS images

Introduction

Few studies are published about total hip arthroplasties (THA) in Parkinson's disease as it is often considered as a contraindication for hip replacement. THA for fracture is reported as a high complication rate surgery. Regarding bone quality these cases are assimilated to elderly patients and cemented implants are generally preferred. However, due to the improved length and quality of life, we face more potential indications for joint replacement. The aim of this study is to report our experience of cementless dual mobility implants for primary THAs for osteoarthrosis and THA revisions focusing on the risks and benefits of surgery.

Introduction

Optimal implant position is critical to hip stability after total hip arthroplasty (THA). Recent literature points out the importance of the evaluation of pelvic position to optimize cup implantation. The concept of Functional Combined Anteversion (FCA), the sum of acetabular/cup anteversion and femoral/stem neck anteversion in the horizontal plane, can be used to plan and control the setting of a THA in standing position. The main purpose of this preliminary study is to evaluate the difference between the combined anteversion before and after THA in weight-bearing standing position using EOS 3D reconstructions. A simultaneous analysis of the preoperative lumbo pelvic parameters has been performed to investigate their potential influence on the post-operative reciprocal femoro-acetabular adaptation.

Introduction

Understanding hip-spine relationships and accurate evaluation of the pelvis position are key- points for the optimization of total hip arthroplasty (THA). Hip surgeons know the importance of pelvic parameters and the adaptation mechanisms of pelvic and sub-pelvic areas. Literature about posture after THA remains controversial and adaptations are difficult to predict. One explanation can be the segmental analysis focused on pelvic parameters and local planning.

In a significant number of patients a global analysis may be important as a cascade of compensatory mechanisms is implemented, the hip being only one of the links of this chain reaction.

3 parameters can be measured on full body images:

The objective of this preliminary study is to report the post-operative evolution of posture after THA.

The current, most popular recommendation for cup orientation, namely the Lewinnek box, dates back to the 70's, that is to say at the stone age of hip arthroplasty. Although Lewinnek's recommendations have been associated with a reduction of dislocation, some complications, either impingement or edge loading related, have not been eliminated. Early dislocations are becoming very rare and most of them probably occur in “outlier” patients with atypical pelvic/hip kinematics. Because singular problems usually need singular treatments, those patients need a more specific personalised planning of the treatment rather than a basic systematic application of Lewinnek recommendations. We aim in this review to define the potential impacts that the spine-hip relations (SHRs) have on hip arthroplasty. We highlight how recent improvements in hip implants technology and knowledge about SHRs can substantially modify the planning of a THR, and make the «Lewinnek recommendations» not relevant anymore. We propose a new classification of the SHRs with specific treatment recommendations for hip arthroplasty whose goal is to help at establishing a personalized planning of a THR. This new classification (figures 1 and 2) gives a rationale to optimize the short and long-term patient's outcomes by improving stability and reducing edge loading. We believe this new concept could be beneficial for clinical and research purposes.

Introduction

The ESP prosthesis is a one-piece deformable but cohesive interbody spacer. it provides 6 full degrees of freedom about the 3 axes including shock absorption (fig1). The prosthesis geometry allows limited rotation and translation with resistance to motion (elastic return property) aimed at avoiding overload of the posterior facets. The rotation center can vary freely during motion in this “silentblock” implant. It thus differs substantially from current prostheses.

Introduction

Optimal implant position is the important factor in the hip stability after THA. Both the acetabular and femoral implants are placed in anteversion. While most hip dislocations occur either in standing position or when the hip is flexed, preoperative hip anatomy and postoperative implants position are commonly measured in supine position with CT scan. The isolated and combined anteversions of femoral and acetabular components have been reported in the literature. The conclusions are questionable as the reference planes are not consistent: femoral anteversion is measured according to the distal femoral condyles plane (DFCP) and acetabulum orientation in the anterior pelvic plane (APP)). The EOS imaging system allows combined measurements for standing position in the “anatomical” reference plane or anterior pelvic plane (APP) or in the patient “functional” plane (PFP) defined as the horizontal plane passing through both femoral heads. The femoral anteversion can also be measured conventionally according to the DFCP. The objective of the study was to determine the preoperative and postoperative acetabular, femoral and combined hip anteversions, sacral slope, pelvic incidence and pelvic tilt in patients who undergo primary THA.

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.

The current, most popular recommendation for cup orientation, namely the Lewinnek box, dates back to the 70's, that is to say at the stone age of hip arthroplasty. Although Lewinnek's recommendations have been associated with a reduction of dislocation, some complications, either impingement or edge loading related, have not been eliminated. Early dislocations are becoming very rare and most of them probably occur in “outlier” patients with atypical pelvic/hip kinematics. Because singular problems usually need singular treatments, those patients need a more specific personalised planning of the treatment rather than a basic systematic application of Lewinnek recommendations. We aim in this review to define the potential impacts that the spine-hip relations (SHRs) have on hip arthroplasty. We highlight how recent improvements in hip implants technology and knowledge about SHRs can substantially modify the planning of a THR, and make the « Lewinnek recommendations » not relevant anymore. We propose a new classification of the SHRs with specific treatment recommendations for hip arthroplasty whose goal is to help at establishing a personalized planning of a THR. This new classification gives a rationale to optimize the short and long-term patient's outcomes by improving stability and reducing edge loading. We believe this new concept could be beneficial for clinical and research purposes.

In approximately 20 years, surgical treatment of femoro-acetabular impingement (FAI) has been widely accepted, and its indications refined. However, the current approach of the disease prevents a good understanding of its pathophysiology, and numerous uncertainties remain. Comprehending inter-individual spine-hip relations (SHRs) can further clarify the pathophysiology of impingement, and explain occasional surprising mismatch between clinical assessment and imaging or intraoperative findings. The rational is simple, the more the spino-pelvic complex is mobile (sagittal ROM) and the more the hip is protected against hip impingement but would probably become at risk of spine-hip syndrome if the spino-pelvic complex comes to degenerate. Grouping patients based on their spine-hip relation can help predict and diagnose hip impingement, and assess the relevance of physiotherapy. With the proposed new classification of FAIs, every patient can be classified in homogeneous groups of complexity of treatment. The primary aim of this paper is to raise awareness of the potential impact that the spine-hip relations have on the hip impingement disease. Two new classifications are proposed, for FAIs and SHRs that can help surgeons in their comprehension, and could be beneficial in clinical and research areas.

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.

Introduction

Rottinger published a description of an anterior muscle sparing approach to the hip. It utilizes the same muscle interval as the classic WatsonJones approach between the gluteus medius laterally and tensor fascia lata medially. However, this technique has the disadvantage of needing asplit table and a sterile bag to mobilize the operative leg as extension, adduction and external rotation are the key points for femoral preparation. This study describes our experience for an equivalent of the Watson Jones approach with a simplified technique for the femoral preparation.

Explanations for “bearing” noise in ceramic-on-ceramic hips (COC) included stripe-wear formation and loss of lubrication leading to higher friction. However clinical and retrieval studies have clearly documented stripe wear in patients that did not have squeaking. Seldom highlighted has been the risk of metal-on-metal or metal-on-ceramic impingement present in total hip arthroplasty (THA) with metal and ceramic cup designs. The limitation in THA positioning studies has been (i) reliance on 2-dimensional radiographic images and (ii) patients lying supine on the examination table, thus not imaged in squeaking positions. We collected eleven squeaking COC cases for an EOS 3D-imaging functional study. Hip positions were documented in each patient's functional ‘squeaking’ posture using standard and 3-D EOS images for sitting, rising from a chair, hip extension in striding, and single-legged stance.

EOS imaging documented for the 1st time that postural dysfunctions with potential impingements were demonstrable for each squeaking case. The 1st major insight in this study came from a female patient who complained of squeaking while walking in flat-soled shoes (Figs. 1a, b). She found that when wearing high-heeled shoes her hip stopped squeaking (Figs. 1c, d). Her lateral EOS view in standing position with heeled shoes revealed that the femoral stem had approximately 3o less hyper-extension compared to flat shoes (Figs. 1b, d, arrows #1,3). The three-dimensional ‘sky-view’ EOS reconstruction of pelvis and femurs (Fig. 2) showed that her femur was also more internally rotated when she wore heels. These subtle shifts in position changed her COC hip from one of squeaking to non-squeaking. A squeaking male patient observed similar postural effects while walking up his boat ramp but not going down the ramp. In both cases, the squeaking was a consequence of cup impinging on a metal femoral neck. Thus the primary cause of squeaking appeared to be hip impingement, i.e. repetitive subluxations that patients generally were not aware of. Another case is representative of situations due to atypical and subtle cup/stem mal-adjustments (Fig. 3); frontal pelvic-tilt, thoracolumbar scoliosis, with 1cm of femur lengthening and a significant increase of offset are observed. Also evident was the femoral-neck retroversion in both standing and sitting. Squeaking occurred when modification of the functional neck orientation occured in one-legged stance (Fig. 3c) or when climbing a stair (Fig. 3d).

It was apparent in our EOS studies that patient functionality controlled whether squeaking occurred or not. Thus the new data indicated COC squeaking was a three-fold consequence of component positioning, spine and pelvic adaptions, and variations in patient posture. One limitation here is that our conclusions are based on a small sample of patients and may not be applicable to all. A consequence of such repetitive impingement can be cup rim damage and neck-notching, with release of metal debris. It is well documented that retrieved ceramic bearings are frequently stained black. Thus hip squeaking may likely result from (i) impingement and secondarily (ii) due to ingress of metal particles, and then (iii) producing a failure of lubrication.

To view tables/figures, please contact authors directly.

Introduction

The combination of spinal fusion and THP is not exceptional. Disorders of the pelvic tilt and stiffness of the lumbosacral junction modify the adaptation options while standing or sitting. Adjusting the cup can be difficult and THP instability is a potential risk. This study reports an experience with EOS® simultaneous measurements on AP and lateral views of spine and hips in THP patients.

Component placement and the individual's functional posture play key roles in mechanical complications and hip dysfunction after total hip arthroplasty (THA). The challenge is how to measure these. X-rays lack accuracy and CT scans increase radiation dose. A newer imaging modality, EOSTM, acquires low-dose, simultaneous, perpendicular anteroposterior and lateral views while providing a global view of the patient in a functional standing or sitting position, leading to a 3D reconstruction for parameter calculation. The purpose of the present study was to develop an approach using the EOS system to compare patients with good versus poor results after THA and to report our preliminary experiences using this technique.

A total of 35 patients were studied: 17 with good results after THA (G-THA), 18 with poor results (P-THA). The patients were operated on or referred for follow-up to a single expert surgeon, between 2001 and 2011, with a minimum follow-up of at least two years.

Acetabular cup orientation differed significantly between groups. Acetabular version relative to the coronal plane was lower in P-THA (32°±12°) compared to G-THA (40°±9°) (p=0.02). There was a strong trend towards acetabular cup inclination relative to the APP being higher in P-THA (45°±9°, compared to 39°±7°; p=0.07). Proportions of P-THA vs. G-THA patients with cup orientation values higher or lower than 1 SD from the overall mean differed significantly and substantially between groups. All revision cases had a least four values outside 1 SD, including acetabular cup orientation, sagittal pelvic tilt, sacral slope, femoral offset and neck-shaft angle.

This is the first study to our knowledge to provide acetabular, pelvic and femoral parameters for these two groups and the first to provide evidence that a collection of high/low parameters may together contribute to a poor result. The results show the importance of acetabular component placement, in both inclination and version and the importance of looking at individuals, not just groups, to identify potential causes for pain and functional issues. With the EOS system, a large cohort of individuals can be studied in the functional position relatively quickly and at low dose. This could lead to patient-specific guidelines for THA planning and execution.

Background

Recent literature points out the potential interest of standing and sitting X-rays for the evaluation of THA patients. The accuracy of the anterior pelvic plane measures is questionable due to the variations in the quality of lateral standing and sitting X-rays. The EOS® (EOS imaging, Paris, France) is an innovative slot-scanning radiograph system allowing the acquisition of radiograph images while the patient is in weightbearing position with less irradiation than standard imagers. This study reports the “functionnal” positions of a 150 THA cohort, including the lateral orientation of the cups.

Introduction: Computer assisted total hip replacement (THA) usually uses the anterior pelvic plane (plane of Lewinneck, APP) for reference because the anatomical landmarks are easy to access during the surgical procedure. However, a recent study shows the lack of correlation in between the Lewinnek angle in standing position (L) and the spinal radiological parameters for sagittal balance, specifically the incidence angle and the sacral slope. The anatomical variations of the anterior superior iliac spines account for the discrepancy. The authors propose here the assessment of the Lewin-nek – sacrum angle (LS) (anterior pelvic plane to the sacral endplate) Methods: 120 asymptomatic patients with THA had low dose lateral X-rays of the lumbo-pelvic area (Definium 8000, GE Healthcare ;dose 0,6 mSivert). The measurements of the sacral slope, incidence angle, and APP were done by two independent observers.

Results: The sacral slope and incidence angles were similar to other series. The APP was no clearly identified in 78 cases. The average L angle was −3° (SD 8°) in standing position, −23° (SD 11°) in sitting postion, and −2° (SD 8°) in lying position. The average LS angle was 47° (SD 13°). The geometrical relationship between the LS a ngle, the L angle and the sacral slope is reported.

Conclusion: THA stability supposes that the orientation of the acetabular component shall remain within extreme values in standing, sitting, and lying postures. The adjustment of the acetabulum takes into account the functionnal anatomy of the lumbopelvic area. The sacral slope is a reliable radiological reference and is related to the sagittal balance of the spine. The APP presents some interindividual variability and is poorly visible on the radiographs, but it is easily accessible during surgery. The author suggest using the Lewinnek sacrum (LS) angle for radiological planification and for surgical navigation procedures.

Purpose of the study: The analysis of hip prostheses often remains limited to standard x-rays taken in the upright position or a CT scan taken in the supine position. The EOS^® system enables imaging the entire body for head to foot in a lateral and anteroposterior views, in an upright or sitting position. The purpose of this work was to compare the standard radiographic work-up with the EOS system for the analysis of postural elements in patients with hip arthroplasty.

Material and method: This prospective study included 50 patients free of complications. The standard radiographic work-up included AP and lateral views in the upright and sitting positions. The standard then EOS imaging protocols were performed in two different locations. Images were acquired with the patients in a comfortable position: for the sitting position, the knees were flexed 90°. Two operators took measurements to be able to analyse reproducibility of the morphological parameters (incidence, sacroacetabular angle, and the positional parameters (version, sacral slope, Lewinnek angle, sagittal and frontal cup inclinations, pelvifemoral angle and orientation of the prosthetic neck on the lateral standing then AP sitting position). Pelvic rotation was determined on the AP view by comparative measurement of the projected width of the iliac wings in each pelvis. Hip extension reserve was calculated on the hyperextension lateral view.

Results: Reproducibility of position was excellent for different times and locations. Twelve hip (24%) presented significant reproducible rotation in the AP view; for eight of these hips (16%), the phenomenon disappeared in the sitting position. Four hips (8%) had pelvic rotation in the sitting position on the AP view. On the AP pelvic view in the sitting position, three patients had a femoral neck in functional retroversion while the anatomic femoral anteversion was normal on the scanner. The pelvic parameters were equivalent to those already described. The reproducibility of the measures was excellent between the standard x-rays and the EOS images with the exception of measurements involving the centre of the femoral head (incidence, pelvifemoral angle). It was easier to align the femoral axis on the EOS lateral images, particularly for additional calculation of extension reserve. The Lewinnek angle could not be measured in the sitting position in 32 hips (60%) because of insufficient resolution.

Conclusion: The overall evaluation of the pelvis and the subpelvic sector provides new information concerning the respective positions of the cup and the femur in functional situations.

Introduction: Wear performances and fracture toughness of the alumina-matrix composite (AMC) Biolox-delta^® are pointed out in the literature. Clinical and radiological studies are needed to assess the potential benefits of AMC/AMC bearing surfaces. The aim of this study is the prospective evaluation of complications and risk factors in patients implanted with AMC liners and 32–36 mm AMC femoral heads.

Methods: 323 consecutive patients were included prospectively since 2006.

243 were implanted for primary surgery with 32 or 36 mm ball heads for a 10–12, 6° tapers.

In 80 cases, we used 32 and 36 mm Delta^® sleeved heads (M,L,XL) for the adaptation on 12–14,5°43 tapers or 10–12, 6° tapers (acetabular revisions in absence of stem exchange, or to increase the lenght of the femoral neck and the offset) All the clinical and radiological files were evaluated at a minimum 2 years follow-up with a special attention for the fracture risk and squeaking. Radiological data were analysed using Dicomesure^® software.

Results: We did not face any significant problem in this series. No fracture occurred. No abnormal wear or implants migration could be detected. We did not observe squeaking phenomenons. 2 THP were revised for septic complications ; the retrivials were analysed for transformation studies(Xray diffraction method XRD). The phase transformation tetragonal to monoclinic was mild, in accordance with previous experimental data.

Conclusion: The limitation of this study is its short follow-up; nevertheless the clinical results are in accordance with the previously published experimental data.

Dislocation remains one of the most common complications after total hip arthroplasty.

Precise cup position appears to be a main factor as significant variations occur for frontal and sagittal acetabular tilt and anteversion according to sitting or standing positions.

An innovative dual mobility ceramic-on-ceramic joint has been developed to solve these problems.

The dual mobility ceramic-on-ceramic joint allows to move the rotation center much deeper inside the insert in order to increase the joint stability without negative impact on the ROM. This device revealed higher torques against subluxation in comparison to the classical Al-Al systems, even with 36mm head diameters, or 41 mm metal on metal bearings.

The additional outer-bearing surface motion creates a second “adjustable acetabulum” due to the eccentration between the rotation center of the ball head and the rotation center of the bipolar head. This offset creates a resultant force that rotates the bipolar component.

Using two bearing ceramic surfaces, the intermediate component acts as a “self adjusting cup”, dealing with the variations of pelvic orientation and acetabulum anteversion.

The use of the dual mobility ceramic-on-ceramic joint seems an interesting alternative when facing difficult or unexpected situations for cup adjustment and cases with hip instability In a hip simulator in micro separation condition, the wear of the dual mobility ceramic-on-ceramic was less than 0.01 mm3/million cycles, the detection limit for wear measurement. There was no change in the surface roughness of the inserts.

The design of the joint with the mobile ceramic head prevented edge loading of the head on the edge of the cup. No stripe wear was observed.

Since 2006 more than 2000 dual mobility ceramic-on-ceramic systems have been implanted in Europe and clinical studies are conducted. The aim is to demonstrate the resistance to dislocation in primary total hip arthroplasty. Previous results over 125 patients in a prospective multicentric study show a Harris and Womac score equivalent to a standard hip prosthesis. No dislocations have been reported. No ceramic breakage or “squeaking” phenomenon appears.

Dislocation and microseparation are major causes of failure for ceramic-ceramic hip prosthesis. When no ideal solution has been found for acetabular implantation, the dual mobility ceramic-on-ceramic device is a real alternative. The exclusive design of the bipolar head give the high resistance to wear and stripe wear to the dual mobility ceramic-on-ceramic joint. Reducing the risk of dislocation and reducing wear drastically are two advantages that can place the dual mobility ceramic-on-ceramic joint as the best choice in primary Total Hip Arthroplasty. Obviously this choice applies to recurrent dislocation also.

Introduction: In patients with gonarthrosis secondary to a femoral or a tibial mal union, the technical problems are different according to the localization and the importance of the deformity, the presence of boneless, the cutaneous and ligamenteous status and the degree of preoperative motion.

Material and Methods: Between 1995 and 2003, 34 TKR have been performed in patients with mal unions either post trauma (26 cases) either secondary to surgery (osteotomy with hypercorrection). There were 21 males and 13 females. The average age was 63 years (38 to 77) The mal union was localized to the femur (9 cases) or the tibia (23 cases) or to the both femur and tibia (2 cases). The deformity was variable : varus, valgus, flessum, recurvatum or rotationnal mal union. IKS scoring, HKA, MFA and MTA angles were evaluated pre and post operatively. 11 cases of intra articular mal unions, secondary to epiphyseal fractures were operated : a TKR posterostabilized (9 cases) or constrained (2 cases) was performed.

In the extra articular mal unions (23) the technique depended on the degre of intraosseous deformity : medial or lateral release or osteotomy performed when the intra osseous deformity was more than 10°. TKR was associated with an osteotomy in one time surgery in 5 femoral mal unions and 12 tibial deformities.

Results: The average follow up was 8 years (4 to 13 years). Complications consisted in 5 phlebitis, 2 superficial skin necrosis, 4 stiff knees (flexion less than 80°). There was no infection in this short serie. The average IKS score was 65 before and 163 after operation. The average flexion was 83° preoperatively and 98° after surgery. Average HKA angle was 167° pre and 182° post operatively in the varus deformities. In the valgus deformity it was 191° pre and 181° post surgery.

Discussion: Average IKS scoring is less good in post traumatic mal unions than in the habitual TKR specially because of the motion : the knee is often stiff preoperatively and remain often stiff postoperatively. A quadriceps release is sometimes indicated either during the TKR either in a second time. Constrained implants (constrained condylar knee or rotating hinge) are necessary in some cases of medial or lateral insuffisency of the collateral ligament.

Introduction: In patients with gonarthrosis secondary to a femoral or a tibial mal union, the technical problems are different according to the localization and the importance of the deformity, the presence of boneless, the cutaneous and ligamenteous status and the degree of preoperative motion.

Matériel et méthodes: Between 1995 and 2003, 34 TKR have been performed in patients with mal unions either post trauma (26 cases) either secondary to surgery (osteotomy with hypercorrection).

There were 21 males and 13 females. The average age was 63 years (38 to 77)

The mal union was localized to the femur (9 cases) or the tibia (23 cases) or to the both femur and tibia (2 cases). The deformity was variable : varus, valgus, flessum, recurvatum or rotationnal mal union. IKS scoring, HKA, MFA and MTA angles were evaluated pre and post operatively. 11 cases of intra articular mal unions, secondary to epiphyseal fractures were operated : a TKR posterostabilized (9 cases) or constrained (2 cases) was performed.

In the extra articular mal unions (23) the technique depended on the degre of intraosseous deformity : medial or lateral release or osteotomy performed when the intra osseous deformity was more than 10°. TKR was associated with an osteotomy in one time surgery in 5 femoral mal unions and 12 tibial deformities.

Results: The average follow up was 8 years (4 to 13 years). Complications consisted in 5 phlebitis, 2 superficial skin necrosis, 4 stiff knees (flexion less than 80°). There was no infection in this short serie. The average IKS score was 65 before and 163 after operation. The average flexion was 83° preoperatively and 98° after surgery. Average HKA angle was 167° pre and 182° post operatively in the varus deformities. In the valgus deformity it was 191° pre and 181° post surgery.

Discussion: Average IKS scoring is less good in post traumatic mal unions than in the habitual TKR specially because of the motion : the knee is often stiff preoperatively and remain often stiff postoperatively. A quadriceps release is sometimes indicated either during the TKR either in a second time. Constrained implants (constrained condylar knee or rotating hinge) are necessary in some cases of medial or lateral insufficiency of the collateral ligament.

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.

Introduction: The goal of the study was to analyse the modification of the sagittal lombo-pelvic equilibrium after total hip replacement for osteoarthritis.

Materials and Methods: The sagittal lombo-pelvic equilibrium was analysed among 89 patients who underwent total hip replacement for osteoarthritis, using lateral X-rays of the whole spine including the hips performed pre-operatively and at one year post-operatively. Reference values were calculated by carrying out the same analysis among 100 asymptomatic healthy volunteers. The studied parameters were: the sacral tilt (ST), the pelvic version (PV) and the sacral incidence (SI).

Results: The mean pre-operative value of STangle was significantly lower in the osteoarthritis group (20.6° +/−6) compared to the reference group (39.4 +/6, p< 0,00001). The mean pre-operative value of VP angle was significanlty higher in the osteoarthritis group (31°+/−8) compared to the reference group (13.5 +/−6 p < 0,00001). There was no significant difference between the two groups for the sacral incidence (p=0,3). At one year post-operatively, the sacral tilt has significantly increased by 5.5° (p< 0.00001).

Discussion: Compared to asymptomatic healthy volunteers, patients affected by osteoarthritis had a pelvic retroversion that has decreased post-operatively but still remained lower than the norm.

Conclusion: The lombo-pelvic equilibrium is different in case of osteoarthritis. After total hip replacement the pelvis remained retroverted. This phenomenon should be taken into account for the planning of total hip arthroplasty.

Hip-spine relationships should be better investigated in THP as lumbo-sacral orientation in the sagittal plane plays a critical role in the function of the hip joints. Lateral X-rays showing spine and hips together in standing, sitting or squatting positions characterize the adaptations of the sagittal balance and the functionnal interactions between hips and spine.

Acetabular cup implantation has to be planned for frontal inclination, axial anteversion, and sagittal orientation. The later refers to the sacro-acetabular angle, key-point in the spine – hip relationships, and that is redefined by the surgeon at the time of implantation.

Usual standard CT-sections are biased for evaluating acetabular anteversion. The conventional CT procedure does not refer to the pelvic bony frame and. the measured anteversion is a projected angle on a transverse plane, depending on the pelvic adaptation in lying position. This measured angle is often considered as anatomical anteversion, leading to some confusion. Therefore this angle is only a “functional” supine anteversion, reflecting the anterior opening angle of the acetabulum in a specific position. According to the sagittal orientation of the pelvis, the true functional acetabular orientation can virtually be assessed in various postures from adjusted CT-scan sections.

The EOS^™ low irradiation 2D-3D X-ray scanner is an innovative technology already used for global evaluation of the spine. This technology allows simultaneously “full body” frontal and lateral X-rays with the patient in standing, sitting or squatting positions; a tridimensionnal patient specific bone recontruction can be performed and the cup anteversion can be directly assessed according to the position.

We investigated the lumbo-pelvic parameters influencing the tridimensionnal orientation of the acetabulum. We compared the data obtained for real postural situations using the EOS^™ system and the measures from plane X Rays and classical CT scan cuts replicating standing, and sitting positions.368 patients with cementless THP were involved in a prospective follow-up protocol. Sacral slope and pelvic tilt, incidence angle, acetabular frontal and sagittal inclination were evaluated on AP and lateral standard XRays. Functionnal anteversion of the cup has been measured using a previously described protocol with CTscan cuts oriented according to standing and sitting sacral slope. The mean difference between CTscan and EOS^™ system was 4,4° with comparable accuracy and reproductibility.

Sacral slope decrease in sitting position was linked to anteversion increase (38,8° SD 5,4°). Sacral slope increase in standing position was linked to lower ante-version (31,7° SD 5,6°). The anatomical acetabular anteversion, the frontal inclination, and the sagittal inclination were functional parameter which significantly varied between the standing, sitting, and lying positions. We noticed that the acetabular parameters in lying position highly correlated to the one in standing position, while poorly correlated with the one in sitting position. The difference between the lying and the sitting positions was about 10°, 25°, and 15° for the cup anteversion (CA) and the frontal and sagittal inclinations (FI,SI) respectively. The poor correlation between the lying and sitting positions suggests that the usual CT scan protocol is biased and not fully appropriate for investigating the cases of posterior THP dislocation and subluxation, which happen in sitting position. On the contrary, a strong correlation was observed between lying and standing measurements with all the acetabular parameters (CA,FI, SI), suggesting that the classical CT assessment of the cup anteversion remains an interesting source of information in case of anterior THP

Each patient is characterized by a morphological parameter, the incidence angle. High incidence angle is linked to low acetabular anteversion, increasing the instability risk and anterior impingement in sitting and squatting position; higher anteversion angles are observed in low incidence angle patients, leading to more internal rotation of the hip in any position.

Lumbo-sacral orientation in the sagittal plane influences the tridimensionnal orientation of the acetabulum, especially for anteversion. Aging of the hip-spine complex is linked to progressive pelvic posterior extension. Impingement phenomenons, orientation of stripe wear zones and some instability situations can be interpreted according to those data.

This study points out the opportunity to adjust the CT scan sections to the sacral slope in functional position for properly investigating the orientation of the acetabular cup, mainly in case of posterior dislocation.

In addition, the mobility of the lumbo-sacral junction could be a crucial parameter in the mechanical functioning and the stability of a THP due to its impact on sacral slope and pelvic tilt. Therefore we also recommend doing dynamic lateral radiographs of the lumbo sacral junction in standing and sitting position for planning a THP implantation in order to detect stiff lumbosacral junction or sagittal pelvic malposition.

While there are many variation laboratory and clinical studies using metal-on-metal (MOM) bearings after introduction of the 28mm MOM THR in 1988, the mapping of wear phenomena in such retrieval cases has been mimimal. In laboratory study, 28mm MOM bearing’s wear-rate was low with “run-in” and “steady-state” than large diameter MOM without theory of fluid-filum lubrication. In clinical results were not superior to the same way of laboratory study. We present a detailed analysis of 33 retrieved MOM hip bearings with 1–11 years follow-up,

We compiled 33 retrieval cases (MetasulTM: Zimmer/CenterPulse Inc., Austin, TX) including clinical information, ion concentrations from ball diameters, cup designs and stripe wear damage. The bearing surfaces were mapped using reflected light microscope (RLM), white light interferometer (Zygo Newview 600, Zygo.) and SEM(XL-30 FEG). Wear maps were constructed according to types of surface wear identified.

Patients ranged from 36 to 76 years of age (Means: 56.9 years); 54% were males. Main causes for revision were progressive radiographic lines around the cups, osteolysis and pain. The 28mm ball diameter was used in 86% of cases (largest = 52mm ball). The CoCr liner incorporated a polyethylene adaptor in 75% of cases. Cup diameter > 50mm was present in 75% of cases. Eight femoral stems were recovered and all showed major impingement marks around the neck and five also had a metallosis (Mode-4A). Stripe wear was evident on 71% of CoCr balls with medial stripes twice as common as lateral. Stripe wear was identified in 25% of CoCr liners and extended 25–160° circumference around the liners. Clear liner rim damage was present in 10 (30%) and 3 demostrated severe damage of polyethelene adaptors.

There are many limitations to such retrieval studies. These data are biased to cases that failed due to hip pain, radiographic signs of progressive osteolysis and some with high levels of metal ions. There was also the bias of having predominantly a CoCr sandwich design (polyethylene adaptor in 75% of cases). In early 1980s, the thin walled UHMWPE cup was introduced and used larger diameter balls for decreased risk of dislocation. However, unfortunally these big-ball cups produced significant PE wear debris, and diameter trends were returned to the Chanley’s small-ball paradigm again. In the same time (late of 1980’s), these second-generation MOM (28,32mm) was introduced for low wear characteristics alternate THR bearings, with sacrificing of joint stability and motion range. However, use of the small ball added well-known risks of impingement, subluxation and dislocation with rigid cups. In this study, using the ‘damage modes’ from McKellop, normal mode-1 wear occurred in only 14% of cases whereas modes 2–4 had an incidence approaching 30% each and signs of cup impingement were evident in 64% of cases. Thus summarizing MOM wear phenomena in “small” 28mm sandwich cup designs, there was retrieval evidence showing that damage modes 2–4 likely placed these patients at risk for adverse wear effects.

Anterior approaches have been suggested for THP revision in order to reduce dislocation rate. However, the exposure is considered to be more strenuous. The goal of the study was to evaluate if anterior approach in lateral position may improve the exposure.

From 2005 to 2007, 47 patients underwent THP revision, 34 times on the acetabular side, 2 times on the femoral side and 11 patients had a bipolar revision. Mean age was 64 years and mean BMI was 23. Patients were positioned on the lateral side and had an antero-lateral approach. During the femoral procedure, the leg was placed in a sterile bag stuck on the lateral side in order to optimize the exposure by positioning the femur in adduction and posterior translation.

Acetabular and femoral exposures were achieved correctly in all the cases allowing to perform all the revisions using this technique and no additional approach was needed in any patient. Antero-posterior femorotomies were performed in 7 patients for stem replacement and cement extraction, without any specific complication. Early post-operative anterior dislocations occurred in 2 patients who underwent monopolar cup revision. Dislocation was explained by an excessive anteversion of the remaining stems. 2 patients had an incomplete and transitory sciatic deficiency due to excessive posterior translation of the femoral head in the sciatic notch.

Using this technique, THP revision seems to be achievable even in complicated cases requiring stem revision and femorotomy. Dislocation rate was low; however a larger cohort is needed to confirm these preliminary results.

The new technology using femoral heads with sleeves allows conservative procedures for revision hip arthroplasty. The implantation of classical ceramic heads on a previously used femoral taper is not recommanded. When there is no loosening of the femoral implant, the use of sleeves is a good solution for using an alumine on alumine couple, specially in young and active patients.

Material and methods: 25 hips in 25 patients were included. In 12 cases the cause of revision was an acetabular osteolysis with or without loosening in metal on metal cimented THR.

In 13 patients the revision was performed for a loosening and a wear of the PHE cup with osteolysis (4 zyrcon and 9 chrome-cobalt heads). The mean age was 49 years for the metal on metal revisions (36 to 75) and 54 years for the prosthesis using a polyethylen socket.

Cementless cups were implanted using XLW delta alumina inserts. The 32 mm delta alumina sleeved heads were adjusted on the existing femoral 12–14 tapers. Patients were evaluated preoperatively and followed-up with clinical and radiological examinations.

Results: At 2 years mean follow-up, average Harris Hip Score was significantly improved (97 vs 54, p< 0.05). We did not observe ceramic fracture or squeaking. The radiographic results did not demonstrate acetabular loosening, osteolysis, or femoral abnormalities.

Concerning the metal on metal revisions, the aseptic loosening of the socket was combined with high rates of cobalt and chromium serum levels. Mean delay before revision was 4 years (2 to 11). Unipolar acetabular revisions were only decided after a carefull inspection of the remaining stems to detect any taper alteration or impingement lesions.

Postoperative cobalt and chromium serum levels significantly decreased postoperatively.

Concerning the metal on PHE and the zyrcon on PHE revisions, the mean delay before revison was 11 years (4 to 21).

At this short follow up, we did not notice any parasitic impingement due to the additional sleeve or any ceramic fracture or squeaking. The radiographic results did not demonstrate acetabular loosening, osteolysis, or femoral abnormalities.

Discussion: Failures of metal-on-metal or metal on PHE hip arthroplasties raise new technical problems. Conversion to ceramic on ceramic has been suggested in case of hypersensibility reactions or high rate of serum metal ions, and in case of osteolysis in young population. This prospective study evaluates a revision strategy using ceramic cups and delta ceramic heads with titanium adapter sleeves when a femoral revision is not required. Despite the limitation due to short follow-up, this technical option should be considered when wear surfaces exchange is decided.

Current total disc prostheses are 2- or 3-pieces devices, including 1 or 2 bearing surfaces, and providing 3 or 5 degrees of freedom but with no, or very little, resistance. The ESP^® is a one-piece deformable implant made of silicon and polycarbonate polyurethane elastomer securely fixed to titanium endplates. It allows limited rotation and translation with elastic return. This cushion without fixed rotation center achieves 6 degrees of freedom including shock absorption. An earlier attempt to use elastomers (Acroflex^®) failed clinically due to the polymer. This highlights the need for accurate in-vitro fatigue testing and clinical evaluations.

In-vitro fatigue testing with more than 40 millions cycles were performed on different samples for compression, flexion-extension bending, lateral bending, torsion and shear. A prospective trial was initiated in 2004 for L3L4, L4L5 and L5S1 levels. Total disc replacements have been performed in 153 lumbar levels through extra-peritoneal mini-invasive anterior approach.

After in-vitro testing, microscopic examination showed that the polymer core remained unchanged without evidence of cracking or other degradation. Gravimetric analysis revealed insignificant changes in weight. The geometrical characteristics and the cohesion of the implants remained stable. After 3 years clinical experience, there was no device related complication, except one early revision for a post-traumatic implant migration. VAS and ODI scores improvements were equivalent to other published series.

In-vitro fatigue testing and short term results of the innovative ESP^® prosthesis demonstrate the reliability of the concept. The results are equivalent to other series with conventional implants.

Purpose of the study: PEEK (polyetheretherketone)is increasingly used for spinal fusion since its elasticity modulus is close to that of cancellous bone. This favors harmonious force distribution within and around the implant and thus stimulates bone healing by remodeling. The purpose of this work was to report the mid-term radiographic outcome with this material used for sagittal correction.

Material and methods: Fifty-seven patients aged 54.6 years on average were reviewed 4 to 8 years after isolated intervertebral fusion for degenerative disease. Levels varied from L2L3 to L5S1. Posterior instrumentation used a rigid or semi-rigid pedicle screw-plate configuration associated with an anterior approach to install a lordozing intersomatic PEEK cage and a cancellous autograft. Six patients were overweight. Regional lordosis was unchanged postoperatively for 47 patients but increased 8.2° on average for ten. The clinical outcome and radiographic fusion were noted using the Brantigan classification. Multivariate analysis was used to search for correlation between regional sagittal correction at last follow-up and the following variables: age, body weight, level, quantity of intersomatic autograft as assessed by CT, rigidity of the posterior instrumentation, posterior regional correction and size of the cage.

Results: The clinical outcome was excellent for 24 patients, good for 25, fair for 6 and poor for 2. Mean sagittal correction was decreased in 13 (5.6° on average). Multivariate analysis demonstrated a significant correlation (p< 0.01, R2=0.590) between loss of correction and the following variables: degree of initial correction, rigidity of the posterior instrumentation, age, lower level, size of the cage.

Discussion and conclusion: Despite the excellent rate of fusion, sagittal correction of the regional lordosis did not persist over time and tended to return to the initial state irrespective of the patient’s weight or the quality of the initial graft. A rigid posterior instrumentation should be considered in parallel with the effect of the PEEK for explaining its role in the loss of correction.

This preliminary study concerns the results of THR using a minimally invasive computer assisted technique: We use the Siguier and Judet procedure. The patient is in supine position and we use an orthopedic table. The skin incision is 6 to 8 cm long and we dont cut any muscle during the approach.

The first 30 cases are studied: The navigation system is scanner free and allows different controls: cup inclination and anteversion, center of rotation, laterality, lengh of the lower limb.

The acetabular implant is a cementless impacted cup and the femoral implant is either cemented or cementless.

The first results are rapported and the technical modifications are descreibed.

A randomized study of 50 patients with CAS and 50 without CAS is now begining to determine if the risk of bad positionning the implants in MIS decreases when we use computer assisted surgery.

Purpose: Transverse fractures of the upper part of the sacrum are exceptional (3–5% of sacral fractures). The neurological implications are serious: loss of the anatomic relation between the pelvic girdle and spine.

Material and methods: We reviewed the cases of 50 patients treated between 1997 and 2001 (31 women, 19 men, mean age 31 years). Most of the patients had fallen from windows (n=46) and many had multiple injuries (n=38). There were 31 associated spinal fractures (18 L1 fractures). The Roy Camille classification was: type I (n=6), type II (n=34),and type III (n=20) with involvement of the pelvic girdle in 30, especially for type II and III (3 Tile A, 10 Tile B, 17 Tile C). Neurological lesions were observed in 42 patients: ten patients had paraplegia (seven total, three partial), 38 had L5 and/or S1 radicular pain, and 36 presented perineal involvement. Functional treatment was given in 11 patients (including five with neurological involvement and serious cutaneous lesions). Surgery was performed early in 25 patients (three with no deficit, 22 with neurological deficit), and late (one month) after callus formation in 14 (13 with neurological deficit, 1 for a cutaneous indication).

Results: Mean follow-up was nine years. The gravity of the pelvic injury corresponded with the degree of associated neurological deficit. Incomplete functional recovery was observed in three patients given functional treatment. For patients undergoing early surgery, ten achieved functional recovery (six total and four partial) with no case of aggravation. Surgery after formation of a callus was followed by total functional recovery in three and partial recovery in six. Surgical complications included infection (n=9) and cerebrospinal fluid fistula (n=2) which resolved after re-operation. Progress in surgical techniques (subtraction osteotomy, better stabilisation) has improved the mechanical results.

Discussion and conclusion : Analysis of these fractures must consider the frontal and sagittal planes to determine the degree of pelvic girdle involvement. The final outcome depends on the time to surgical treatment (particularly for type II and III fractures) and reconstitution of the sagittal alignment of the spine with the pelvis.

Purpose: Uncertain position of the acetabular implant has been the cause of dysfunction in certain cases of total hip arthroplasty (THA). Classical computed tomographic analysis of anteversion has certain limitations. Integrated reconstruction of positions at risk allows a better diagnostic approach.

Material and methods: We studied 46 THA because of posterior malposition (n=17, anterior subluxation in the standing position in twelve, and true dislocation in five) and anterior malposition (n=29, posterior subluxation in sixteen and true dislocation in thirteen). Two groups of 70 naïve hips and a group of 56 THA with no functional problem served as controls. The position of the acetabulum was studied on optimised computed tomography slices reconstructing the planes of analysis for the standing, sitting and reclining positions. The reference planes for the slices was given by the sacral tilt angle measured on the lateral views of the patient in the corresponding positions. The optimised computed tomographic measurements of anteversion were compared with the classical measures. None of the patients had abnormal femoral anteversion and/or an oblique pelvis and/or leg length discrepancy greater than 10 mm. The frontal inclination of the acetabular implants was 40°–50°.

Results: In the naïve hips, acetabular anteversion varied: 19.2 with the conventional method, 15.7 in the standing position and 31 in the sitting position. In the THA controls, anteversion measurements differed: 21.3 with the conventional method, 21.4 in the standing position and 35.8 in the sitting position. In the THA with a posterior malposition, 18/29 could not be explained by the conventional measurement, but the optimised measurement enabled an understanding in 17 hips (defective anteversion in the sitting position).

Discussion: Changes in pelvis orientation between the sitting and standing positions modifies real anteversion of the cup. In particular, subjects with THA tend to have a spontaneous posterior tilt of the pelvis related to trunk ageing. This element should be taken into account for the analysis of both major and minor THA dysfunction.

Introduction Infection of posterior instrumentation supposes a severe failure in long arthrodeses with a demineralized skeleton.

Materials and methods From 1998 to 2002, ten patients of 19 to 76 years (mean 56 years) have been grafted with anterior Peek cages filled with autograft.

Four cases of scoliosis were operated as an average 5 times by posterior approach (3 – 9 times), all of them suffered fistulised non-unions recidivating after every one of the previous operations. 4 times the germ xas a Staph. Aureus Met. resist (1 associated with a streptococcus and 2 of them with an enterococcus). Three patients presented severe radicular pain.

Six posttraumatic cases underwent a surgical extraction of the posterior instrumentation. All of them presented a non-union with total loss of the initial angular correction. In one case the septic destabilisation affected the level proximal to the fixation. The germ responsible was every time a Staph. Aureus Met. Res. with an enterococcus associated in one of the cases.

Two inveterate fistulae were operated before. The grafts were performed on 1 to 4 levels without a new posterior fixation but in one case (5 thoracolumar approaches, 5 on lumbosacral fusions, external support by a 3 points corset between 4–6 months). The postoperative antibiotherapy has been maintained for 4 months in average (3–12 mos). The fusion was appreciated by the graft aspect on CT scan with a mean follow-up of 22 months (12 months minimum).

Results: No anterior infection has been observed, but in one post-traumatic case with a violation of the discal space by a screw. (Flare-up of the infection without anterior collection, treated by a new posterior approach with definitive kyphotic fusion as a result). All the nine others fused with clinical improvement (sevrance of the rigid corset and decreasing analgesic doses in a mean time of six months) and without significant correction loss. Three cases of radicular pain improved too. As a complication, one female patient previously operated three times by an anterior approach, was operated a new by a minimal left approach without incidents. She suffered in the postoperative period an ureteral necrosis needing a secondary nephrectomy.

Conclusion This strategy of intersomatic graft is a recovering solution in the mechanical failures of severe and reccurrent infections, often germs association. With these severe deformities on aged patients this technique is more difficult. The positive culture of disc material is a bad prognostic factor. In case of previous anterior approach, it is a good procedure the catheterisation of the ureteral duct to prevent a possible necrosis. The intersomatic cage has been a safe procedure assuring a primary and late stability in those patients with a deficient bone-stock. The cages did not induced any additionnal septic problems.

Purpose: Infection of a posterior fixation can lead to a therapeutic dilemma, particularly if the extensive fixation involves a demineralised spine.

Material and methods: From 1998 to 2001, seven patients aged 19 to 76 years (mean 58) were treated with an interbody cage and an autologous graft. Four patients with scoliosis had had prior posterior surgery (mean five operations, range 3 – 9 operations). All had exhibited non-union with repeated fistulisation at each prior anterior approach, in four cases with meti-R Staphylococcus associated once with a Streptococcus and twice with an Enterococcus. Three patients suffered severe radicular pain. Three of the post-trauma patients had undergone revision procedures to remove the posterior implants. All had developed nonunion with total loss of the initial correction in two cases, one with septic instability concerning the level above the fixation. Both infections were caused by meti-R Staphylococcus, associated with an Enterococcus in one case. Two persistent posterior fistulae had been reoperated earlier. The grafts involved one to four levels with no new posterior fixation except for one patient (two accesses to the thoracolumbar junction, five lumbosacral fusions, immobilisation for four to six months with a corset). Mean duration of postoperative antibiotics was four months (3–12 months). Fusion was confirmed by the radiological aspect of the grafts on the scan obtained at a mean 22 months follow-up (minimum follow-up 12 months).

Results: There were no cases of anterior infection except for one post-trauma patient where a posterior screw touched the disc (reactivation of infection without anterior abscess, posterior approach for revision and final fusion in kyphosis). There was no appreciable improvement in correction, but the six other patients fused with a clear clinical improvement (removal of rigid corset, reduction of antalgesics, mean time 6 months). Improvement was observed in the three patients with radicular pain. One patient who had undergone three prior anterior operations underwent the minimally invasive posterior revision with no particular intraoperative problem but later presented ureteral necrosis (secondary nephrectomy).

Discussion: This interbody grafting strategy is a possible solution to salvage mechanical failures subsequent to recurrent severe infection often due to multiple germs. The technique is more difficult in older patients with complex malformations. A positive disc sample is a factor of less satisfactory outcome. In the event of prior anterior revision, an ureteral catheter is advisable to limit the risk of necrosis. Use of intersomatic cages is not a problem and has allowed us to achieve primary and secondary stability in these patients with poor bone stock and this without supplementary infection problems.

Purpose: We analysed the radiographic course of anterior lumbar interbody fusion achieved via a minimal anterior extraperitoneal approach.

Material and methods: From January 1996 to December 2001, we operated 198 patients with this technique. Twenty-one patients were excluded from the analysis (two deaths, three tumours, 16 follow-ups less than 12 months). Mean age of the 177 patients retained for study was 53 years (range 22–78). Mean follow-up was 2.7 years. The 55 post-trauma cases involved essentially thoracolumbar junction. The 122 cases of degenerative lumbar spine included 14 cases of scoliosis, 26 cases of spondylolisthesis, 72 cases of unstable spines after primary posterior surgery, and 10 isolated degenerative discs. Only eight patients did not have posterior fixation. Fusion (globally 360 levels) concerned one disc in 89 patients, two discs in 71, three discs in 17. Cancellous autologous grafts were used with cages. Tricortical grafts were implanted after corporectomy (n=23). Radiological fusion was confirmed by the absence of a mobility chamber around the pedicular screws, the cages or the tricortical grafts, and by searching for loss of sagittal angles (digitalized scans and x-ray, Auto Cad L.T.2000).

Results: 1) Early postoperative status. For the post-trauma cases (65 fused levels, 55 patients), a simple callus was observed in 28. For the others, mean correction was 4° per level. 2) Angle loss. For the trauma cases, mean angle loss was 3.9° in 36 cases (29 grafts on a single level). There were two partial expulsions of the tricortical grafts implanted in osteoporotic patients; revision was not attempted. Mean angle loss for the 65 grafted levels was 2°. For the degenerative cases, mean angle loss was 3.7° for 172 fused levels (112 patients). Cage expulsion on a grade 3 spondylolisthesis did not warrant revision. Two cage impactions did not cause significant loss of angle. 3) Anatomic status of the grafts. Fusion was achieved at all levels without cage or tri-cortical graft rupture. We observed a partial but stable lucent line around the case in five cases.

Discussion: The rate of fusion reported after anterior lumbar interbody fusion has varied from 55 to 100% in the literature. This technique is an original approach for trauma victims avoiding the need for extensive posterior assemblies and/or the damage caused by a wide anterior approach. For the degenerative spine, the mediocre quality of the bone and the frequency of several level fusions is not a particular problem.

Conclusion: Anterior lumbar interbody fusion is an interesting method for reinforcing posterior fixation with a real efficacy in terms of effective fusion.

Purpose: Single-segment wedge osteotomy is classically proposed to correct for kyphosis subsequent to ankylosing spondylitits. We analysed the usefulness of this technique for other indications (revision procedures for flat back and deformed calluses of the lumbar spine) by studying the overall sagittal balance of the spine and tilt of the sacrum.

Material and methods: Between 1980 and 1999, we retained 68 patients with complet clinical and radiological data (37 patients with ankylosing spondylitis and 31 patients with “post-operative” flat back, including nine trauma cases and 22 degenerative spines). Opening osteotomy was performed in the first 19 patients and closure osteotomy in the next 49. The correction level was L2L3 in 26 patients and lower in 42. Digitalised lateral views of the entire spine were obtained at minimum follow-up of three years to measure:

- posterior displacement of T9 (between the vertical line and a line joining the geometric centre of T9 and the femoral heads (normal 11±5°),

Results and discussion: The overall angle of local correction was 44° and the correction of T9 displacement was 30.6°. For the low osteotomies, the local correction was 49° and the T9 displacement was +28° (−2° to +26°). Tilt of the sacrum varied from 4° to 7°. Tilt of the sacrum was influenced more and more for lower and lower osteotomies. T9 displacement stabilised between 12° and 26° (mean 19°) irrespective of the osteotomy level, although the angle of local correction was greater (up to 60°). This discordance was explained by adaptation of the pelvis. Seven patients developed secondary functional kyphosis (limited hip movement preventing the necessary adaptation to the overall correction of the sagittal balance).

Conclusion: Single-segment spinal osteotomy remains difficult but offers very important correction possibilities affecting the position of the trunk and adaptation of the pelvis. The level for the correction must be chosen with care because it conditions final adjustment and function consequences affecting the pelvis.

Purpose: The aim of this work was to evaluate the short- and long-term biocompatibility, tolerance and tissue response after implantation of an intersomatic bioresorbabled lumbar cage (Phusiline®).

Material and methods: Eighteen sheep were operated on in 1999; three animals were sacrificed for study at three, six, nine and twelve months after implantation. The cage was placed between two lumbar vertebrae and filled and covered with cancellous bone. Cerebrospinal fluid, lateroaortic lymph nodes, liver, spleen and kidney samples were taken after sacrifice. The spinal segment from L1 to S1 was removed with the surrounding ligaments and muscles for radiography, MRI, and CT scan. Histology sections were stained with Paragon. The pathology examination included: bone and cell density, degree of tissue differentiation in contact with the implant, remodeling and consolidation of the fusion, implant resorption and associated reactions. An epifluorescence study was performed to assess bone apposition. Reaction of tissue in contact with the implant or far from the implant (laterovertebral muscles, paravetebral lymph nodes, liver, kidney, spleen) were qualified histologically.

Results: At three months, there was no evidence of implant resorption; there was active formation of new bone around the implant. Implant resorption and osteointegration had started at six months and bone remodeling around the implant was increased. There were signs of bone fusion within and around the cage. Spondylodesis was effective at nine months with bone apposition. Implant resorption continued. Spondylodesis was confirmed. After nine and twelve months implantation, there was no sign of local or general intolerance. Degradation of the implants was visible after one month and appeared to be most marked at 12 months. Approximately 30% of the initial surfaced area of the implants had been resorbed at 12 months.

Conclusion: One year after implantation, the implant had not induced any sign of local intolerance (no sign of inflammation, necrosis, osteolysis). Fusion occurred within and around the case. This study will be pursued (two groups of three animals will be sacrificed at 24 and 36 months) and should confirm the long-term effectiveness of this technique.

Purpose: A significant increase in serum cobalt level has been reported after metal-on-metal total hip arthroplasty with wide individual variability related to activity level, mechanical conditions of the implant, and urinary elimination of cobalt. We studied serum cobalt levels over time to further analyse these factors.

Material and methods: The Metazul® prosthesis was implanted in 119 patients (72 men and 47 women, 12 bilateral implantations) (131 implants). We selected 50 patients (27 men and 23 women, mean age 53 years) who had two blood samples after the procedure allowing an assessment of the serum cobalt kinetics. Other chromium-cobalt implants, vitamin B12 intake, renal failure, or haematological disorders were recorded. An activity questionnaire was filled out by the patients at the time of the blood sample. Samples were drawn with a special kit to avoid metal contamination. The detection limit was 1 nmol/L (0.06 μg/L) with direct electrothermic atomic spectrometric absorption.

Results: In the overall series, serum cobalt level was 44 nmol/L for a physiological level in a control population of 4.28 nmol/L. The difference was significant (p < 0.0001) between the levels observed before surgery and after 18 months implantation. There was no significant correlation with the indication for arthroplasty, presence of dislocation or subdislocation, functional outcome or radiographic findings. Activity level the week before sampling did not influence the results. For the 50 cases evaluated longitudinally, four groups of patients could be identified. The first group (29 patients) had a serum cobalt level below 50 nmol/L over the entire study period. The second group (nine patients) had a level greater than 50 nmol/L followed by a decline ending with a final level below 50 nmol/L. In the third group (six patients) serum cobalt was greater than 50 nmol/L with no trend to a decline. In the fourth group (six patients) the cobalt levels were very high (greater than 150 nmol/L).

Discussion: The six patients in the fourth group were very particular. There were three patients with secondary bilateral implants with a late peak in serum cobalt, one with an impingement on the acetabular rim, one with renal failure, and one who had a very high level of physical activity. The first group had what appears to be a favourable course, similar to the second group where a stabilisation phenomenon could be operating. An explanation in the third group is difficult but could involve a third segment abrasion phenomenon.

Conclusion: Longitudinal analysis of serum cobalt levels provides more information than point measures in patients with metal-on-metal arthroplasties. Intercurrent mechanical phenomena can be detected; unexpected behaviour of the metal-on-metal junction can be suspected in certain patients.