Introduction

The assessment of leg length is essential for planning the correction of deformities and for the compensation of length discrepancy, especially after hip or knee arthroplasty. CT scan measures the “anatomical” lengths but does not evaluate the “functional” length experienced by the patients in standing position. Functional length integrates frontal orientation, flexion or hyperextension. EOS system provides simultaneously AP and lateral measures in standing position and thus provides anatomical and functional evaluations of the lower limb lengths.

The objective of this study was to measure 2D and 3D anatomical and functional lengths, to verify whether these measures are different and to evaluate the parameters significantly influencing these potential differences

Introduction

Coronal misalignment of the lower limbs is closely related to the onset and progression of osteoarthritis. In cases of severe genu varus or valgus, evaluating this alignment can assist in choosing specific surgical strategies. Furthermore, restoring satisfactory alignment after total knee replacement promotes longevity of the implant and better functional results. Knee coronal alignment is typically evaluated with the Hip-Knee-Ankle (HKA) angle. It is generally measured on standing AP long-leg radiographs (LLR). However, patient positioning influences the accuracy of this 2D measurement. A new 3D method to measure coronal lower limb alignment using low-dose EOS images has recently been developed and validated. The goal of this study was to evaluate the relevance of this technique when determining knee coronal alignment in a referral population, and more specifically to evaluate how the HKA angle measured with this 3D method differs from conventional 2D methods.

Introduction

The gold standard for knee surgery is the restoration of the so-called «neutral mechanical alignment ». Recent literature as pointed out the patients with «constitutional varus »; in these cases, restoring neutral alignment could be abnormal and even undesirable. The same situation can be observed in patients with «constitutional valgus alignment ». To date, these outliers cases have only been explored focusing on the lower limb; the influence of the pelvic morphotype has not been studied. Intuitively, the pelvic width could be a significant factor. The EOS low dose imaging technique provides full body standing X-rays to evaluate the global anatomy of the patient. This work explores the influence of the pelvic parameters on the frontal knee alignment.

Introduction

Accurate evaluation of femoral offset is difficult with conventional anteroposterior (AP) X-rays. Routine CT imaging is costly and exposes patients to a significant dose of radiation. The EOS® imaging system is an innovative slot-scanning radiography system that makes possible the acquisition of simultaneous and orthogonal AP and lateral images of the patient in standing position. These 2-dimensional (2D) images are equivalent to standard plane X-rays. Three-dimension (3D) reconstructions are obtained from these paired images according to a validated protocol. This prospective study explores for the first time the value of the EOS® imaging system for comparing measurements of femoral offset obtained from 2D images and 3D reconstructions.

Introduction

The viscoelastic lumbar disk prosthesis ESP is an innovative one-piece deformable but cohesive interbody spacer; it provides 6 full degrees of freedom about the 3 axes including shock absorption. 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. It thus differs substantially from current prostheses. This study reports the results of a prospective series of 120 patients who are representative of the current use of the ESP implant since 2006.

Introduction

The position and orientation of the lower extremities are fundamental for planning and follow-up imaging after arthroplasty and lower extremity osteotomy. But no studies have reported the reproducibility of measurements over time in the same patient, and experience shows variability of the results depending on the protocols for patient positioning. This study explores the reproducibility of measurements in the lower extremity with the patients in “comfortable standing position” by the EOS® imaging system.

Introduction

Femoral stem anteversion after total hip arthroplasty (THA) has always been assessed using CT scan in supine position. In this study, we evaluated the anteversion of the femoral prosthesis neck in functional standing position using EOS® technology with repeatability and reproducibility of the measurements. The data obtained were compared with conventional anatomic measurements.

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: Progressive cervical myelopathy secondary to cervical stenosis is generally treated surgically. Results of surgical decompression are generally good, but the progression and the type of neurological recovery have not been studied. We followed a cohort of patients who underwent cervical decompression in order to study the kinetics and the mode of the neurological recovery after surgery.

Material and methods: This was a prospective mono-centric observation study conducted in a routine clinical setting. The cohort included 60 patients (mean age 65.7 years) who underwent surgery around 2006. Inclusion criteria were an association of stenosis documented on the imaging and clinical signs of medullary compression. One surgeon performed all interventions (80% posterior approach, 15% anterior and 5% mixed). Preoperative evaluation used complete cervical imaging and three validated function tests: the global JOA score, the Crockard walking test, and the nine-hold plug test of manual dexterity (9HPT) for both hands. Patients were reviewed postoperatively at 1, 3, 6, 12, 18 and 24 months. Two populations were distinguished: group 1 with mild to moderate compression: mean preoperative JOA > 10; group 2 with severe compression: mean pre-operative JOA ≤10.

Results: The mean preoperative JOA was 11.7/17 (5; 15), the mean Crockard 34.5s (24; 140), and the mean time for the 9HPT 23s for both hands. Analysed by group according to the JOA showed that cervical myelopathy is mainly expressed by sensorial disorders. The JOA score, the walking test and the hand dexterity test for the dominant hand described the same pattern of recovery with a clear improvement for the first three postoperative months then a neurological stabilisation of the acquired improvement on a plateau that persisted till the end of follow-up. There was no improvement in the non-dominant hand. The same pattern was observed in both groups: the severe group presented a better improvement, reaching a final JOA score equivalent to that in the “mild-to-moderate” group.

Discussion: The pattern of recovery of cervical neurological deficits occurs rapidly during the first three months following surgical decompression, then stabilises on a plateau, irrespective of the severity of the initial condition. The benefit is certain for initially severe compression.

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.

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.

Purpose of the study: Misalignment after insufficient treatment of unstable fracture of the pelvis is often poorly tolerated, compromising quality-of-life due to limping, leg length discrepancy, posterior pain, uncomfortable sitting position and/or sexual disorders due to mechanical problems. Secondary surgical treatment can be proposed despite its invasive nature (generally three phase surgery). The purpose of this work was to present the technique and the results of standardized correction of pelvis misalignment using a two-phase procedure.

Material and methods: Eight consecutive patients (May 2002–May 2004) with sequelae of Tile C fractures were treated on average eight years after the initial trauma. A double-approach was used. The series included four men and four women, aged 18–43 years. The first posterior approach in the ventral supine position was used for osteotomy of the sacroiliac callus and systematic debridement by section of the sacroiliac ligaments. The secondary ilioinguinal approach was performed in the dorsal supine position to achieve osteotomy of the symphyseal callus, reduction of the iliac wing, and symphyseal synthesis using a sacroiliac plate anteriorly and percutaneous screws.

Results: The mean operative time was four hours 30 minutes. Blood loss required transfusion of 3.5 packed red cell units on average. Anatomic reduction was achieved in six cases, partial reduction in two. Despite one nosocomial infection and two partial popliteal external sciatic deficits, all patients wer satisfied with the operation at mean eight months follow-up. Bone healing was achieve din all cases.

Discussion: Standard two-phase surgery is possible for a wide range of cases. The anatomic result is reliable with good clinical outcome. The duration of the operation and blood loss are reduced compared with classical techniques.

Conclusion: Despite the advantage of this original operative strategy, surgery for correction of pelvis misalignment remains a difficult surgical procedure for selected and motivated patients informed of the operative risks.

Purpose of the study: The aim of this retrospective epidemiological study was to report the complete arthroscopic results concerning meniscus or cartilage injuries for procedures performed to repair the anterior cruciate ligament (ACL). The goal was to search for risk factors and improve patient care.

Material and methods: Between 2000 and 2004, the same operator performed 129 consecutive ligamentoplasties to repair ACL tears. The following preoperative factors were analyzed: body weight, height, type and level of sports activity, laxity, positive pivot test, morphotype, time from accident to surgery. Meniscal lesions were identified and classified according to Trillat. The Beguin and Locker classification was used for cartilage lesions. The Panthéon-Sorbonne statistics laboratory performed the statistical analysis.

Results: Meniscal lesions were found in 53.5% of knees and cartilage lesions in 24.2%. The medial meniscus was involved in 75.4% and the lateral meniscus in 20.3%, both in 4.3%. The injury could be repaired by suture or a conservative procedure for 45%. The medial compartment presented cartilage injury in 51.6% of knees, the patella in 29%, the trochlea in 19.35% and the same percentage for the lateral condyle. The degree of preoperative laxity, the time from accident to surgery and body mass index were statistically correlated with presence of a meniscal injury. Age, the degree of pre-operative laxity and body mass index were statistically correlated with presence of a cartilage injury.

Discussion: Meniscal injuries are frequent in knees with ACL tears. The posterior segment of the medial ligament, which blocks anterior translation of the tibia if the ACL is absent, is predominantly involved. The amount of tibial movement below the femur and stress applied to the knee (particularly related to body mass) favor such lesions. Many lesions will heal spontaneously after surgery. Inversely others are more frequent after a longstanding tear. Cartilage injury is also frequent and occurs often on aging cartilage. The extent of tibial movements and their repetition as well as important stress are factors predictive of such injuries.

Conclusion: Indications for reconstruction of the ACL in the young subject are well identified, less so in the older subject. This study confirms the usefulness of reconstructing the ACL to protect the menisci and joint cartilage. Excessive weight appears to be another important point to take into consideration for the surgical management of these patients.

Mechanical failure in total hip arthroplasty is usually due to aseptic loosening related to wear particles as seen with polyethylene bearing. Alumina has been proposed for avoiding wear problems. In vitro and mid-term clinical studies showed tribological advantages but early acetabular fixation issues. Since alumina on alumina bearing is currently used with new fixation techniques, updated evaluations of the ancient series are informative regarding the long-term tolerance of alumina in vivo.

In this paper, we investigated 104 consecutive lumina on alumina cemented total hip arthroplasties (CER-VAER-OSTEAL, Roissy, France) implanted 20 years ago in 81 patients (from 1979 to 1983). Alumina femoral head was 32 mm in diameter. Alumina acetabular socket and titanium femoral stem were cemented. The clinical evaluation used Postel Merle d’Aubigné score. Radiological wear and appearance of osteolysis or loosening were noted for establishing actuarial curves. When accessible, histological samples from revision procedures were analyzed.

Six infected cases were not taken into account later. The average follow-up was 11 years, reaching 18 years in 38 cases. Twenty-three hip were revised for changing 23 acetabular sockets, 12 femoral heads, and 1 femoral stem. We noted 1 femoral head fracture, 24 definite ace-tabular loosenings, 12 probable acetabular loosenings, and 3 definite femoral loosenings. Radiological acetabular osteolysis was present in 4 cases, always limited to De Lee zone 1, and associated with loosening. Radiological wear was below eye detection. Peri-prosthetic tissue showed non-specific histological reaction to cement particles. Survival rate at 20 years was 61.4% in term of revision (57.1% and 95.2% concerning acetabular and femoral defininte loosening).

Beside the high rate of cemented fixation failure of the socket, loosened and non loosend cases showed an excellent tolerance of alumina on alumina bearing in the long-term, with minimal wear and osteolysis. This may also have protected the femoral component from complications.

Purpose: Alumina is a bioinert ceramic used for total hip arthroplasty as an alternative to metal-on-polyethylene bearings which can wear producing massive osteolysis and loosening. The purpose of this retrospective analysis was to examine the Ceraver combination implant which uses a cemented smooth titanium femoral stem, a 32 mm alumina head, and a cemented alumina cup.

Material and methods: Between December 1979 and February 1983. 104 total hip arthroplasties were performed in 81 patients, mean age 57.8 years (2.1–70.9). The main indication was primary degenerative disease (71 hips). The Postel Merle d’Aubigné score was used for clinical assessment. Plain x-rays were used to establish the actuarial survival curves using the Harris criteria for radiological loosening for the cup and the Massin criteria for the femoral piece. Periprosthetic femoral and acetabular osteolysis were noted. Histological samples taken during revision procedures were analysed.

Results: Six hips with suppuration were not retained for analysis. The clinical scores for the other 98 hips were, at last follow-up: excellent in 34, very good in 21, good in 16, fair in 21, and poor in 6. Mean follow-up was eleven years and reached 18 years for 38 hips. Fracture of the alumina head (n=1), aseptic certain radiographic loosening of the cup (n=24), probable radiolographic loosening of the cup (n=12), and certain radiographic loosening of the femoral piece (n=3) were noted. Revision was required for 23 hips for replacement of the cup (n=23), the head (n=12), or the femoral stem (n=1). There were no cases of massive radiographic osteolysis. The histological examination of surgical specimens obtained at revision were normal in all cases (very moderate aseptic foreign body reaction). Excepting the cases of suppuration, the estimated actuarial survival without revision at 20 years was 61.4% (57.1% for he radiographic cup loosening criteria and 95.2% for the radiographic femoral implant criteria).

Discussion: This analysis confirms the long-term biotolerance of the alumina-alumina bearing despite the poor maintenance of the cemented alumina cup. It also confirms the good maintenance of the cemented smooth titanium femoral stem.

Conclusion: Cup anchorage must be improved to use the alumina-alumina bearing which does not cause osteolysis nor histological reactions.