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.
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.
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.
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.
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.
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.
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.
The use of two-dimensional plain X-rays for preoperative planning in total hip arthroplasty is unreliable. For example, in the presence of rotational hip contracture the lateral femoral off set can be significantly under-estimated. Pre-operative planning is of particular importance when using uncemented prostheses. The aim of this study was to determine the precision of a novel 3D CT-based preoperative planning methodology with the use of a cementless modular-neck femoral stem. Pre-operative computerised 3D planning was performed using HIP-PLAN® software for 223 patients undergoing THA with a cement-less cup and cement-less modular-neck stem. Components were chosen that best restored leg length and lateral off set. Postoperative anatomy was assessed by CT-scan and compared to the pre-operative plan. The implanted component was the same as the planned one in 86% of cases for the cup and 94% for the stem. There was no significant difference between the mean planned femoral anteversion (26.1° +/− 11.8) and the mean postoperative anteversion (26.9° +/− 14.1) (p=0.18), with good correlation between the two (coefficient 0.8). There was poor correlation, however, between the planned values and the actual post-operative values of acetabular cup anteversion (coefficient 0.17). The rotational centre of the hip was restored with a precision of 0.73mm +/3.5 horizontally and 1.2mm +/− 2 laterally. Limb length was restored with a precision of 0.3mm +/− 3.3 and femoral off set with a precision of 0.8mm +/− 3.1. There was no significant alteration in femoral off set (0.07mm, p=0.4) which was restored in 98% of cases. Almost all of the operative difficulties encountered were predicted pre-operatively. The precision of the three-dimensional pre-operative planning methodology investigated in this study is higher than that reported in the literature using two-dimensional X-ray templating. Cup navigation may be a useful adjunct to increase the accuracy of cup positioning.
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.
An extra articular correction may be necessary in osteoarthritis with an important post traumatic or congenital deformity. In the last 5 years we performed 11 TKR associated with a tibial (9 cases) or a femoral Osteotomy (2 cases), in one time surgery. The average intra osseous deformity was 14°. The technical problems are different in varus and valgus knees. 1- Which type of osteotomy ? In varus knees with a tibial deformity (6 cases) we use a hight tibial valgus osteotomy with opening wedge. Pre operative planning with long standing X rays allows precise determination of the amount of correction needed. A rigide wire, driven up to the fibular head, is placed. A provisional wedge of the desired size (degree of correction) is maintened temporarily by a staple, which will be removed later. Once the correction has been performed and maintened, the standard instrumentation to implant the prosthesis is used. In valgus knees with a tibial deformity (2 cases) a hight tibial closing wedge osteotomy, and in valgus knees with a femoral deformity (2 cases), a low femoral closing wedge osteotomy, are used. In all cases a medial approach without any release and without fibular osteotomy is performed. 2- Which kind of prosthesis? Two degrees of constraint are possible in fonction of particular needs. Most of the time, a non-constrained PS articular implants will be used and when more constraint will be needed (in lateral instability), CCK-type articular surfaces will be choised. In all cases, a stem will have to be, associated with the osteotomy (tibial or femoral). Different diameters will allow a good press-fit and if necessary, an offset stem will be used. 3- Associated osteosynthesis or not? Stability provided by the press-fit stem may allow not to use an osteosynthesis in most than 50% of cases. If a doubt remains about stability, a small plate can bee added on the medial tibial side of the tibia. 4- Which immediate post-op follow-up? Full weight bearing will be immediate. A splint will be used only for walking during six weeks. A standard rehabilitation protocole will be followed. In our 11 patients with a short follow up (1 to 5 years) complications consisted in one hematom and one phlebitis. Post-operative alpha angle was 96° and beta angle 91°. TKR with an associated osteotomy seems to be a possible alternative when osteoarthritis is associated with an important extra articular deformity.