We describe the results of 81 consecutive revision total hip replacements with impaction grafting in 79 patients using a collared polished chrome–cobalt stem, customised in length according to the extent of distal bone loss. Our hypothesis was that the features of this stem would reduce the rate of femoral fracture and subsidence of the stem.

The mean follow-up was 12 years (8 to 15). No intra-operative fracture or significant subsidence occurred. Only one patient suffered a post-operative diaphyseal fracture, which was associated with a fall. All but one femur showed incorporation of the graft. No revision for aseptic loosening was recorded.

The rate of survival of the femoral component at 12 years, using further femoral revision as the endpoint, was 100% (95% confidence interval (CI) 95.9 to 100), and at nine years using re-operation for any reason as the endpoint, was 94.6% (95% CI 92.0 to 97.2).

These results suggest that a customised cemented polished stem individually adapted to the extent of bone loss and with a collar may reduce subsidence and the rate of fracture while maintaining the durability of the fixation.

Purpose of the study: Three-screw fixation is the classical treatment for true Garden I in the elderly patient. Complication rates have been high in the literature. Furthermore, in this context outcome for arthroplasty after failed osteosynthesis is less satisfactory than first-intention arthroplasty. This is why functional treatment of Garden I fractures of the neck of the femur has been proposed, including rapid return to the upright position and strict radiographic and clinical control. The purpose of this work was to first evaluate the results of this management option for true Garden I fractures in patients aged over 65 years and second to search for factors predictive of secondary displacement.

Material and methods: All patients aged over 65 years and admitted to the unit for true Garden I fractures from January 2005 to December 2006 were included in this prospective study. A functional treatment including early return to the upright position and walking test on day 1 was instituted, followed by radiographic controls on days 2, 7, 14, 21, and 45 then at 3 months and one year. Referral to a rehabilitation centre at discharge on day 5 was scheduled if there was no displacement. In the event of a displacement, arthroplasty was performed. Fifty-seven patients, mean age 82.8±8.5 years (range 65–99) were included. The radiographic and clinical follow-ups were made by an independent observer.

Results: The displacement rate was 29.8%. These patients were treated by arthroplasty. In the group of patients without displacement, at minimum one year follow-up, there has been no need for surgical revision excepting one case of osteonecrosis at one year requiring implantation of a total prosthesis. The mean Parker score in this group was 6.4 and the mean Harris score 83, it was 85 in the arthroplasty group. Among the predictive factors identified at multivariate analysis were: age, gender, side, type of fracture, fracture orientation, degree of valgus or sagittal displacement, general status. Displacement was not statistically predictive.

Discussion: The results of our prospective study show that 70% of patients included were treated successfully without surgery, confirming reports in the literature and justifying utilisation of this management strategy.

Purpose of the study: It has been demonstrated that the anatomy of the distal femur differs by gender. The ratio of the mediolateral/anteroposterior distance, the shape of the distal femur, and the orientation of the trochlea differ between males and females. To adapt to these differences, prostheses specifically designed for female patients (TKAgender) were developed. The purpose of our study was to compare the first objective and subjective outcomes with these prostheses.

Material and methods: Thirty women who underwent bilateral surgery within a six month interval for degenerative joint disease of the knee between March 2006 and March 2008 were included in a comparative prospective study. The side receiving the gender implant was determined at random. Operative and postoperative protocols were the same excepting the femoral implant. Patients were not informed of which knee had received the gender prosthesis. Mean age in this series was 67 years and mean BMI 26. All implants were cemented. At minimum one year follow-up, objective and subjective analysis included specific questions concerning preference and quality of life presented by an independent observer.

Results: The Knee Society clinical scores were comparable in the two groups, as were the results for the different items of the KOOS score. For preferences: the patients preferred the gender knee in 75% of the cases (p< 0.01), they reported less noise or cracking sounds in the anterior part of the knee for 68% (p=0.03) and had the impression that the knee recovered faster in 64% (p=0.04).

Discussion: To our knowledge, this is the first report of results concerning implants specifically designed for female patients. At short-term, the only difference in the patients’ preference was a subjective feeling of less impairment for the patellar track. It will be interesting to follow these patients to assess the long-term impact on the patellofemoral articulation.

Most of computer-assisted computer assisted system rely on the peri-operative acquisition of the anterior pelvic plane defined as the plane crossing the two anterior iliac spine and the symphysis. The goal of this study was to evaluate in vivo and in vitro the accuracy of the anterior pelvic plane acquisition, considered as the reference for computer-assisted total hip arthroplasty (THA).

Cup placement was performed using an imageless computer-assisted system in thirty patients during THA. Post-operatively the position of the cup was evaluated on computed tomography using a validated tridimensional software. The differences between the perioperative and postoperative angles for abduction and anteversion were compared using a two-group pair test.

On two cadavers four clinicians performed ten times the anterior pelvic plane acquisition using three Methods: percutaneously, with ultrasound and by direct bony acquisition defined as the reference. The mean error for each anterior pelvic plane acquisition method was compared using a univariate variance model for repeated measurements.

In vivo, the mean difference between the perioperative and postoperative abduction angles was 4° and not statistically significant. For anteversion, the difference was 4° and not significant in patients with BMI < 27. The difference was 11° and significant in patients with BMI > 27 (p< 0.001). In vitro, the mean errors for rotation and tilt were respectively 3.8 ° and 19.25 ° for cutaneous acquisition, 2.8° and 6.2° for ultrasound acquisition method. The errors were statistically higher with the percutaneous method (p< 0.001).

According to our results, the accuracy of the standard percutaneous acquisition method of the anterior pelvic plane in computer-assisted THA is limited. The ultrasound acquisition method may represent a reliable alternative.

Purpose of the study: Because of the growing number of aseptic loosening of total hip arthroplasty (THA), a reliable biological marker would be useful to diagnosis osteolysis early and non-invasively while avoiding the risk of false positives. The purpose of this study was to analyse the value of the interleukin-10(IL10)-alphaTNF ratio in serum and synovial fluid as a marker of THA aseptic loosening.

Material and methods: Blood synovial fluid samples were collected in 27 volunteers with a cemented THA (group THA) and 30 healthy subjects comparable for age and gender who were programmed for total hip arthroplasty because of primary osteoarthritis (group OA). We analysed: locally by the level of alphaTNF and IL10 in the supernate of differentiated THP-1 with and without adjunction of synovial fluid (SF); in the bloodstream the production of alphaTNA and IL10 by monocytes; the correlation between serum and SF levels and the presence or not of loosening.

Results: In the THA group, SF induced a relative decrease in IL10 strangly not associated with an increase in alphaTNF. However, the IL10/alphaTNF ratio was significantly lower in the OA group. Circulating monocytes produced more alphaTNF in the THA group while there was no significant difference in the production of IL10 by the two groups. However, the IL10/alphaTNF ratio was significantly higher (2-fold) in the THA group. Regarding serum cytokine levels, there was a local accumulation of alphaTNF in the THA group and IL10 in the OA group.

Discussion: The IL10/alphaTNF ratio alone was significantly correlated with aseptic loosening, locally and in the general bloodstream. IL10 or alphaTNF did not alone correlate in all conditions. These results show that use of this ratio appears to be more effective than assay of a single proinflammatory cytokine for the early diagnosis of aseptic loosening. The validity of this ratio is supported by its local and general correlation. A comparative prospective study in healthy subjects using a non-invasive method (except for the blood samples) should be conducted to confirm the clinical pertinence of this marker.

Purpose of the study: Besides enabling a precise calculation of the needs for blood (in ml) for each type of orthopaedic surgery, an adequate estimation of average total blood loss (TBL) as a function of total blood volume (TBV) enables initiation of blood sparing techniques. Thus, when the balance is negative, erythropoietin could be advisable. The purpose of this work was to analyse the impact of prescribing erythropoietin as a function of the expected blood balance on the rate of homologous blood transfusions. We also wanted to determine the financial impact of this prescription strategy.

Material and methods: This prospective study included 229 patients (153 THA and 76 TKA) who underwent surgery from January 2005 to December 2008 with a standard anaesthesia, analgesia and surgical protocol. TBL was considered to be 10% of TBV for THA and TKA. Mean gain in serum haemoglobin (Hb) per injection of erythropoietin (1 ampoule Eprex) was 0.8 g/dl. Using the patient’s Hb level at the preop exam (Hbpreop), the anaesthetist determined the volume available (VA) for each patient and for each type of operation. When VA was negative, the Hb needed to reach the desired level (HbA) so that VA=0 (zero risk of transfusion) was calculated. The number of Eprex ampoules prescribed (amp) was determined from the formula: (HbA-Hbpreop)/0.8. Hb levels on day 0, day 1, day 3(discharge) and day 28 were noted, as were the number of homologous transfusions and the total number of ampoules of Eprex delivered.

Results: Sixty-six patient received one amp (33.2%), 96 had two amp (42%), 40 three amp (17.5%) and 17 four amp (7.4%). For 220 patients (92%), Eprex delivered was within the approved dose (92%). The mean Hb levels were: Hbpreop=12.4, HbA=13.5, Hbd0=13.9, Hbdischarge=11.2, and Hbd28=11.9. Total consumption was 456 amp instead of 916 (229x4), i.e. a savings of 460 amp corresponding to 173 880 euros (460 x 378 euros). There were six homologous transfusions (2.6%).

Discussion: In orthopaedic surgery, adapted prescription of erythropoietin as a function of the TBL enabled, in this series, a simplification of the prescription procedure and avoided the risks related to high Hb levels > 15g with a financial savings of 760 euros per operation (173880 euros for 229 patients) without increasing the rate of homologous transfusion. This strategy is currently being evaluated for prosthesis revision surgery.

Previosuly, Komistek et al. have shown that the kinematics of the patellofemoral joint is altered after a TKA surgery. Specifically the implanted patella experiences significantly less rotation than the natural patella. Also, in early flexion, the patellofemoral contact positions differed significantly between implanted and non-implanted patellae. It was also found that some of TKA subjects experience patellofemoral separation. These kinematical differences may lead to adverse mechanical conditions and increase fatigue or cause loosening of the implant components. This study’s objective was to determine the three-dimensional patellofemoral kinematics and correlate it with the in vivo sound (vibrations) detected using accelerometers for subjects having a TKA and a non-implanted knee under in vivo, weight bearing conditions. The correlation of the knee mechanical conditions with the vibration data may indicate new parameters that may be used to diagnose the condition of the articular cartilage or implant components.

Fifteen subjects (average age 71.8 ±7.4years) having one implanted knee (mobile bearing Hi-Flex PS) and the healthy contralateral knee, performed

deep knee bend to maximum flexion,

Three miniature, piezoelectric, three-axial accelerometers were attached to the patella and femoral epicondyle. The study was approved by the Institutional Review Board and informed consent was obtained from all subjects. The sensors detected the vibration magnitudes and frequencies of the articulating patellofemoral joint surfaces. The signals were amplified and low-pass filtered at 5 kHz by a signal conditioner. The 3D tibiofemoral and patellofemoral kinematics were derived for both knees using a previously published 3D-to-2D registration technique. The 3D bone models were recovered from CT scans, while implant models were obtained from the manufacturer. The patellofemoral rotations were described using the Grood and Suntay convention. The kinematics and sound data were synchronized and recorded under fluoroscopic surveillance, for 10 patients. Then a subset of seven subjects having a TKA was re-analyzed for their contralateral (non-implanted) knee. The vibration signal was then converted to audible sound and correlated with the 3D kinematics.

On average, the subjects achieved more flexion with their TKA (103.4°±15.9°) than with their contralateral knee (96.3°±18.3°). The patellofemoral kinematics varied between the TKA and nonimplanted patella groups; the resurfaced patella experienced less flexion, less medial rotation and less tilt than the contralateral patella. The patellar flexion results were consistent with previously reported literature for both TKA and non-implanted patellae. Also, the resurfaced patellae contacted the femur more proximally than healthy patellae. Audible signals were found for both groups of subjects. The frequency analysis demonstrated that specific frequencies were in similar range for both groups, but the magnitudes and variations were different for the TKA and contralateral knees.

This study correlated 3D patellofemoral kinematics with sound under in vivo conditions for three different activities. Variable audible signals were detected for TKA and non-implanted knees. Vibration magnitude and frequency identification, under in vivo conditions, for TKA may lead to a better understanding of wear and failure modes with respect to the patellofemoral mechanics, more specifically, the patellar insert. Currently this initial study is being expanded to degenerated knee joints and failed TKAs for possible applications of the vibration analysis to the early diagnosis of knee arthritis, detection of implant loosening or wear and monitoring of implant osteointegration progress.

Unicompartmental knee arthroplasty (UKA) is a logic procedure when osteoarthritis or avascular necrosis is limitad to one femorotibial compartment. The indications for the procedure includes osteoarthrosis or osteonecrosis with full-thickness loss of articular cartilage limited to one of the tibiofemoral knee compartments. Physical examination should ensure full range of knee motion. Frontal and sagittal knee stability has to be tested. A particular attention should be given to the state of the anterior cruciate ligament. The status of the patellofemoral joint should be analysed by physical examination and patellofemoral view at 30, 60 and 90° of flexion. Preoperative anteroposterior varus and valgus stress radiographs should be done to confirm the complete loss of articular cartilage in the involved compartment, the full thickness cartilage in the opposite compartment and the possibility of full correction of the deformity to neutral.

The so-called minimally invasive surgery (MIS) procedure using a specific instrumentation is able to provide quicker recovery since the extensor mechanism disruption is eliminated. More importantly the radiological evaluation has shown that precise implantation of the components is possible with an MIS approach which is important for the long term results of the arthroplasty. The clinical results at ten years of follow-up of cemented metal-backed UKA performed through a conventional approach have shown results comparable to those obtained with total knee arthroplasty. The in vivo kinematic evaluation of patients implanted with UKA has shown that kinematics similar to the normal knee can be obtained, enhancing the importance of a functional anterior cruciate ligament.

Recent design improvements have increased the femorotibial area of contact to accommodate high flexion angles. Additionally our experience has demonstrated that modern UKA is a valid alternative for young and active patients with unicompartmental tibiofemoral noninflammatory disease, including both osteoarthritis and avascular necrosis. Compared to medial UKA lateral UKA represents in our experience only 5% of all UKA implantations.

However the long term results of lateral UKA compares at least equally with those reported for medial UKA.

Introduction: The incidence of contralateral, second hip fractures after a first hip fracture is as high as 20% in the elderly. Femoroplasty using an injectable and resorbable bi-phosphonate loaded bone substitute to prevent controlateral hip fracture may represent a promising preventive therapy. We aimed to evaluate the biomechanical consequences of the femoroplasty using this bone substitute.

Materials and Methods: Twelve paired human cadaveric femora from donors with a mean age of 86 years (7 women and 6 men) were randomly assigned for femoroplasty and biomechanically tested for fracture load against their native contralateral control. Anterior–posterior and lateral radiographs and DXAscan’s were made before injection. Femoroplasty were performed under fluoroscopic guidance with an injectable and resorbable bi-phosphonate loaded bone substitute. All femurs were fractured by simulating a fall on the greater trochanter by an independent observer.

Results: Mean T-score of the tested femur were −3. Bone density was comparable for each pair of femur. All the observed fractures were Kyle II throchanteric fractures. Mean fracture load was 2786 Newton in the femoroplasty group (group F) versus 2116 Newton in the control group (group C) (p< 0.001). Fracture loads were always higher in the group F: mean 41.6% (mini: 1.2%/maxi:102.1%). Effect of femoroplasty was significantly superior for women and also correlated to initial bone density (p< 0.0001).

Discussion:According to our results, femoroplasty with an injectable and resorbable bi-phosphonate loaded bone substitute can provide significant biomechanical reinforcement of the proximal femur to prevent controlateral fracture.

Introduction: Women have gender specific shape of the distal femur. To fit these gender characteristics, gender specific femoral implants were developed for total knee arthroplasty (TKA). We aimed to compare

objective and subjective functional improvement;

Materials and Methods: 30 women (60 knees) operated on successively (6 months in between) for a bilateral TKA between March 2006 and March 2008 by the same surgeon were included in this prospective study. The same surgical protocol and the same post-operative management protocol were applied for both sides. Mean age was 67±3 and mean BMI 26±4 Kg/m². At a minimum follow-up of one year, evaluation objective and subjective functional improvement, patient satisfaction and preference and cost-utility analysis were performed double blind.

Results: Knee Society knee score and Knee Osteoarthritis Outcome Score (KOOS) improvements were comparable in both groups. However, 75% of the women preferred their gender TKA (p< 0.001). 68% of the women described less crepitus or anterior knee bothering after gender TKA (p=0.003) and 64% had faster recovery with the gender implant (p< 0.001). The cost-utility analysis was favorable for the gender knee.

Discussion: No objective or subjective superiority in terms of functional improvement was shown with gender specific implants at this short-term follow-up. However significant differences in terms of patient satisfaction and preference and a favorable cost-utility analysis were observed. These results should now be confirmed at longer-follow-up. Despite comparative functional improvement, patient satisfaction and preference were higher for the side implanted with a gender specific TKA in this prospective comparative study.

Introduction and Method: For 16 years, now, we have been using custom made femoral stems (titanium stem, HA coated) based on preoperative patient CT scans in young patients presenting with symptomatic osteoarthritis of the hip. The aim was to provide optimum initial fit-and-fill of the stem in the femoral medullary canal, conferring the best chance of secondary osteoin-tegration. This, with a goal of long term survivorship. The custom stem also enables dialling-in correction of the (often abnormal) femoral neck version (in young patients presenting with arthritis) to a more normalised 15 degrees of anteversion.

Results: We present the long term results (5–16 year, mean of 10 years), clinical, survivorship and radiological, of 312 primary total hip arthroplasties in 280 patients, all of whom were under the age of 50 years of age (mean age 40).

At 10 years we have a survivorship, if femoral aseptic loosening is used as an end point, of 97.6%. There was a deep infection rate of 1.2%, and a dislocation rate of 1.9%. There were no cases of thigh pain, and no intra-operative femoral neck/shaft fractures.

Discussion: The under 50’s with hip arthritis requiring total hip arthroplasty are a highly challenging group, they are young, active and tend to have distorted anatomy. Our results are superior to those previously published using either cemented or standard uncemented stems. Thus, justifying the increased initial financial outlay on the custom-made stem.

Introduction: Due to the diversity of the prosthetic implants for hip arthroplasty, a better matching between the implant and the intra and extra-medullary characteristic of the patient anatomy is now possible. This adaptation however requires a perfect understanding of the tridimensional characteristics of the patient hip anatomy. Little data are available in the literature. We aimed to analyze the muscular and bony anatomy of the hip at the time of arthroplasty.

Material and Methods: data acquisition was performed according a standardized CT-scan in the same center for all patients within the standard workup before arthroplasty. Standardized measurements were obtained after automatic tridimensional bone reconstructions using dedicated software. 549 femurs in 469 patients including primitive coxarthrosis (COX), dysplasic development of the hip (DDH) and aseptic osteonecrosis (ONA) were analyzed. Mean age was 58 and 70% of the patients were women. Tridimensional reconstruction of the muscular anatomy of the hip was performed for 30 patients using manual contouring on dedicated software. Characteristics of the bony and muscular anatomy were then analyzed according to the etiology and correlations between bony and muscular anatomy were evaluated.

Results: Concerning the bone analysis, mean offset was 23.2 ±1.5mm in the DDH group, 40.5±1.2 mm in the COX group and 29.6± 0.9mm in the ONA group(p< 0.001). Neck-shaft angle was 132±25º in the DDH group, 130±0.5º in the COX group and 134±1º in the ONA group (p< 0.001). Mean anteversion was 33±3.5º in the DDH group, 25±3.8º in the COX group and 16±3.2º in the ONA group (p< 0.001). Concerning the muscular analysis, gluteus medius and minimus volumes were correlated with the body mass index and with the gender, but not with patient age (p: NS). Location of the muscular insertion of the gluteus medius and minimus on the greater trochanter were correlated with the femoral anteversion.

Discussion: The results of our study demonstrated that bony and muscular anatomical characteristics were correlated with the etiology of the degenerative joint disease, with the patient body mass index and gender. Surgeons should be aware of these characteristics to improve the patient anatomy reconstruction during the arthroplasty.

Introduction: morphological analysis of the general shape of the bones and of their particular variations according to the patient age, gender and pathology is an important step to improve the orthopedic management. We aimed to performed a gender specific analysis of the bi and tridimensional anatomy of the distal femur in vitro and in vivo.

Materials and Methods: in vitro data were obtained from CT-scan performed on 92 dry men femurs and 52 dry women femurs. Using a manual contouring method and a segmentation method, tridimensional reconstructions were obtained and according to two different algorithms, the regions of discrepancies between men and women were determined. An automatic calculation of 59 defined measurements was then performed. In vivo data providing from 59 CT-scans of men femur and 73 CT-scan of women femurs were acquired. Standardized bidimensional measurements at the level of the trochlear cut were performed.

Results: in vivo, statistically significant differences were observed for the: medio-lateral distance (M-Ld women=7.4±0.4cm vs M-Ld men=8.4±0.5cm; p< 0.0001), anteroposterior distance (A-Pd women=5.9±0,4cm vs A-Pd men= 6.4±0.4cm; p< 0.0001) and for the ratio anterior-posterior distance/medio-lateral distance (p< 0.0001). The trochlear groove angle was comparable in the two groups. In vitro, the tridimensional shape of the distal femur was more trapezoidal in women than in men. Medio-lateral distances were also statistically greater in men than in women (p< 0.01), the ratio anterior-posterior distance/medio-lateral distance was also statistically greater in men than in women (p< 0.01) and the Q angle more open in women than in men (p< 0.01).

Discussion: Three types of differences between men and women were observed in this gender specific evaluation of the distal femur anatomy. First, for a same anteroposterior distance, the medio-lateral distance was smaller in women. Second, the global shape of the distal femur was more trapezoidal in women and third the Q angle was more open in women. This gender specific anatomy should be clinically considered when performing total knee arthroplasty in women and gender specific implants may be required.

A clinical and radiographic study was conducted on 97 total hip arthroplasties (79 patients) performed for congenital hip dislocation using three-dimensional custom cementless stem. The mean age was 48 years (17 to 72). The mean follow up was 123 months (83 to 182).

According to Crowe, there were 37 class 1, 28 class 2, 13 class 3 and 19 class 4. The average lengthening was 25 mm (5 to 58 mm), the mean femoral anteversion 38.6° (2° to 86°) and the correction in the prosthetic neck −23.6° (71° to 13°). The average Harris hip score improved from 58 to 93 points. Six hips (6.2%) required a revision. The survival rate was 97.7% ± 0.3% at 13 years.

Custom cementless stem allows anatomical reconstruction and good functional results in a young and active population with disturbed anatomy, while avoiding a femoral osteotomy.

Purpose of the study: Malposition of the acetabular implant of a total hip arthroplasty can provoke dislocation, limited joint movement, and early wear. The purpose of this prospective randomized study was to assess the efficacy of a image-free navigation system to achieve correct acetabular position for total hip arthroplasty.

Material and methods: The navigation software for the acetabular component used intraoperative anatomic acquisition. The prospective randomized study included two groups of 20 patients. In the first group, the acetabular implant was inserted using the computer-assisted system and in the second using the conventional method. The same operator performed all procedures via an anterolateral approach and using the same non-cemented hemispheric cup. The postoperative assessment was performed by an independent investigator who noted the cup inclination on the standard ap view and cup anteversion on the computed tomography; then using a dedicated system for 3D reconstruction, the same values were determined one month after surgery.

Results: Each group included ten men and ten women, mean age 63 years and mean body mass index 24. For the computed-assisted group, mean additional operative time for navigation was 13 minutes (range 8–20 min). The intraopeartive concordance with the surgeons subjective impression was excellent for 12 patients and good for 8. Mean intraoperative values were for the computer-assisted group were: for operative mode: inclination 30° (25–46°), anteversion 14° (0–25°), radiographic mode: inclination 35° (25–47°), anteversion 13° (0–26°), anatomic mode: inclination 36°, anteversion 19° (0–27°). There was no significant difference between the intraoperative and postoperative values for the computer-assisted group. There was no significant difference between the average values between the computer-assisted and conventional groups but the standard deviation was smaller in the computer-assisted group.

Discussion and conclusion: The image-free navigation system enables reliable positioning of the prosthetic cup for total hip arthroplasty and increases the precision of acetabular implantation without increasing significantly operative time. This first step must be integrated into the computerized preoperative planning for total hip arthroplasty. The next step will be to use the navigation system for implanting the femoral component.

Purpose of the study: Acetabular dysplasia is a recognized cause of premature hip degeneration. With increasing use of arthroplasty, the role of conservative treatment can be debated. The purpose of this work was to describe technical advances achieved with Ganz triple periacetabular osteotomy and evaluate long-term results.

Material and methods: This study included 32 dysplastic hips in 28 patients treated by Ganz triple osteotomy and assessed a mean 12 years follow-up (range 2 – 20 years). Mean age was 32 years (range 18–47). There were 24 women and four men. Hip joint measurements were made on preoperaive standard x-rays with complementary recentered views if needed as well as computed tomography (CT) to better distinguish progressive degeneration. For early patients, the iniail osteotomy involved three cuts (ilioischial, iliopubic, ilial) starting close to the acetabulum and performed via three approaches: sub coxofemoral, intrapelvic, extrapelvic. The first technical change involved osteotomy of the anterosuperior iliac spine and an oblique iliac cut farther from the acetabulum.

Results: Mean preoperative angles were: 135° (121 to 150°) for CC’D, 23.2° (3 to 40°) for HTE, 8.4° (−14 to 22°) VCE, 11.3° (−26 to 32°) for VCA. The postoperative values were: 134.5° (121 to 150°) for CC’D, 9.5° (−9 to 20°) for HTE, 31.7° (14 to 60°) for VCE, 31.7° (10 to 48°) for VCA. Six patients required total hip arthroplasty on average four years later (range 2 – 9 years), including one patient with aseptic necrosis of the acetabulum.

Discussion and Conclusion: This study confirms the usefulness of triple periacetabular osteotomy for conservative treatment of acetabular dysplasia. In light of our results, the following changes have been instituted:

all three cuts are performed via a single intra-pelvic approach;

Purpose of the study: Compter-assisted surgery enables improved precision of prosthetic implantations, but the basis of data acquisition remains variable. The purpose of this study was to assess the radiological quality of a total knee arthroplasty (TKA) implanted with a computer-assisted surgical technique with or without pre-operative imaging.

Material and methods: This was a case-control study of a group of 40 patients who underwent TKA implanted with a navigation systm (N+) which was compared with a control group of patients who underwent the same procedure with a conventional technique (N-). The two groups were comparable for: age, gender, BMI, preoperative HKA. The same surgeon operated all patients using the same cemented posterior stabilized TKA. Outcome was analyzed by an independent operator. The same navigation system was used for all knees, with, for the first 20 knees, acquisition based on preoperative computed tomography and for the next 20 knee, intra-operative acquisition. Postoperatively, six radiographic parameters were studied for each knee on the ap and lateral views. An optimal interval was determined for each parameter and the number of optimal criteria was noted for each knee.

Results: The mean HKA was 177.5° in the N- group and 179.2° in the N+ group. The angle of implantation of the femoral piece was 90.3° in the N- group and 90° in the n+ group. The mean posterior tibial slope was 3.5° in the N+ group and 3.1° in the N- group. There was a significant difference for the tibial prosthetic angle in favor of the N+ group, i.e. 89° compared with 87.3° for the N- group. The overall quality of the implantation was considered optimal for 54.5% of knees in the N+ group and for 29.8% in the N- group. There was no significant difference between computed tomographic acquisition and intraoperative acquisition.

Discussion and conclusion: This study demonstrates that the results exhibit a distribution closer to the ideal values for the navigation group but that the difference is solely significant for the tibial implantation. This improvement requires a longer operative time of 18 minutes. The lack of any difference between the computed tomographic acquisition and the intraoperative acquisition suggests that intraoperative acquisition should be favored for reasons of cost and simplicity. Computed tomography imaging can still be useful for a precision of the biepicondylar line in certain complex situations such as revision arthroplasty.

Purpose of the study: Changes in prosthetic design to adapt to knee flexion greater than 120 degrees can modify the bone-prosthesis fixation and also displace the femorotibial contact. The purpose of this study was to analyze mid-term results in a consecutive series of 186 arthroplasties and to examine the femorotibial kinematics in vivo.

Material and methods: A posterior stabilized cemented prosthesis with a plateau with motion limited to rotation was used. Design changes concerned: lengthening of the posterior femoral condyle, scooping out the poly-ethylene anteriorly with reorientation and change in the height of the posterior stabilization stem. The same technique was used for all patients who followed the same rehabilitation protocol. Mean age was 69 years (range 22–87). All patients were evaluated clinically with the IKS score and radiologically on the anterioposterior and lateral images. An in vivo analysis of the femorotibial kinematics in the weight bearing condition was also performed in 20 patients under fluoroscopic control with automatic 3D modelization.

Results: Mean follow-up was 40 months (range 2–5 years). Mean IKS function score improved from 34 preoperatively to 96 at last follow-up. The knee score improved from 53 on average to 91 at last follow-up. The mean flexion was 115° (range 45–135°) preop-eratively and 120° (115–145°) at last follow-up. One implant was removed for infection and arthrolysis was performed for one case of stiff joint. Radiographically: the mean postoperative femorotibial alignment was 179° (178–181°), the mean tibial slope 3.8° (0–10°°, the mean patellar height (0.8° (0.56–1°), and the mean elevation of the joint space (4.5 mm. There were two cases of progressive lucent lines in the tibial zone which were stable at last follow-up. All patients analyzed showed a mean posterior displacement of the femorotibial point of contact of 9.7 mm at flexion.

Discussion and conclusion: Changes in prosthesis design to adapt to greater range of flexion do not appear to have a negative effect at mid-term on implant fixation. The clinical flexion ranges obtained were encourageing and the correlation with kinematic results show that the degree of preoperative flexion remains a determining factor for the postoperative outcome. Posterior displacement of the femoro-tibial point of contact, observed in all patients examined fluoroscopically, certainly contributed to the good postoperative flexion.

A clinical and radiological study was conducted on 97 total hip replacements performed for congenital hip dislocation in 79 patients between 1989 and 1998 using a three-dimensional custom-made cementless stem. The mean age at operation was 48 years (17 to 72) and the mean follow-up was for 123 months (83 to 182).

According to the Crowe classification, there were 37 class I, 28 class II, 13 class III and 19 class IV hips. The mean leg lengthening was 25 mm (5 to 58), the mean pre-operative femoral anteversion was 38.6° (2° to 86°) and the mean correction in the prosthetic neck was −23.6° (−71° to 13°). The mean Harris hip score improved from 58 (15 to 84) to 93 (40 to 100) points. A revision was required in six hips (6.2%). The overall survival rate was 89.5% (95% confidence interval 89.2 to 89.8) at 13 years when two hips were at risk.

This custom-made cementless femoral component, which can be accommodated in the abnormal proximal femur and will correct the anteversion and frontal offset, provided good results without recourse to proximal femoral corrective osteotomy.

Introduction: Deep flexion may affect both femorotibial contact pattern and patellofemoral interface. The objective of this study was to conduct the first in vivo kinematic analysis that determines the 3D motions of the femorotibial and patellofemoral joints, simultaneously from full extension into deep flexion.

Methods: Three-dimensional femorotibial and patello-femoral kinematics were evaluated during a deep knee bend using fluoroscopy for five subjects having a normal knee, five having an ACL-deficient knee and 20 subjects having a TKA designed for deep flexion.

Results: The average weight-bearing range-of-motion was 125 degrees, significantly higher than in previous studies. On average, subjects experienced 4.9o of normal axial rotation and only three subjects experienced an opposite rotation pattern. On average, subjects experienced −9.7 mm of posterior femoral rollback (PFR) and all subjects experienced at least −4.4 mm of PFR. These subjects experienced less patellofemoral translation than the normal knee, but the average motion was similar in pattern to the normal knee. On average, the subjects having a TKA experienced patella tilt angles that were similar to the normal knee.

Discussion: It is assumed that femorotibial kinematics can play a major role in patellofemoral kinematics. Altering the patella motion and/or the patellar ligament rotation could lead to much higher forces at the patel-lofemoral interface. In this study, these subjects experienced kinematic patterns that were very similar to the normal knee and it can be deducted that forces acting on the patella were not significantly increased for TKA subjects compared with the normal subjects.