A higher reliability with a computed tomography scan-based three dimensional technique than with a two dimensional measurement for lower limb discrepancy in total hip arthroplasty planning.

PURPOSE: The goal was to compare the reliability of a novel 3D method with the standard 2D technique for lower limb discrepancy (LLD) measurement during pre-operative THA planning. METHODS: This prospective study included 100 consecutive patients who underwent THA using 3D planning based on a low-dose CT scan. The LLD was subdivided into three parameters: the intra-articular LLD (IA-LLD), the segmental extra-articular LLD (EA-LLD), and the total LLD (T-LLD). The LLD was assessed with a standard 2D technique on CT scanograms and also with a 3D method. A pelvic reference line (PBL) was determined as the 3D line joining the deepest part of the two great sciatic notches. The IA length was measured from the lesser trochanters (MLT) to the PBL. The EA length was measured from the MLT to the ankle center, and the total length was measured from the ankle center to the PBL. The intra- and inter-observer reliability of the measurements was assessed with the intra-class correlation coefficient (ICC). RESULTS: The intra-observer ICC was higher with the 3D technique for IA-LLD (0.96-0.97 vs. 0.79-0.84), EA-LLD (0.96 vs. 0.78-0.92), and T-LLD (0.99 vs. 0.90-0.97). Inter-observer ICC was also higher with the 3D technique for IA-LLD (0.90-0.94 vs. 0.70-0.84) and EA-LLD (0.93-0.96 vs. 0.80-0.82), but not for T-LLD (0.91-0.94 vs. 0.91-0.94). CONCLUSION: The presented 3D method has a higher reliability than 2D assessment of LLD during pre-operative THA planning. This article presents the first discussion of measuring LLD from 3D models. As 3D reconstruction becomes both more feasible and less-invasive, this study has interest to the orthopaedic surgeon.

Pre-operative bone mineral density is a predictive factor for excellent early patient-reported outcome measures in cementless total hip arthroplasty using a proximally fixed anatomic stem. A prospective study at two year minimum follow-up.

PURPOSE: The goal of the study was to analyze the impact of the pre-operative bone mineral density on the patients' reported outcomes at two year minimum follow-up of cementless THA using a proximally fixed anatomic stem. METHODS: A prospective study included all patients who underwent a cementless THA using a specific proximally fixed anatomic stem and a 3D preoperative CT scan-based planning. The bone mineral density (BMD) of the metaphyseal cancellous bone was computed in a volume (of 1 mm thick and of 1 cm2 surface) at the level of the calcar 10 mm above the top of the lesser trochanter. Patients were assessed at two year follow-up using self-administered auto-questionnaires corresponding to the modified Harris (mHHS), the Oxford (OHS), and the Forgotten Hip (FHS) scores. A multiple linear regression statistical analysis was performed to assess the link between the mHHS, the age, body mass index (BMI), BMD, gender, and ASA grade. RESULTS: Fifty patients were included (29 men, 21 women), with an average age of 62 ± 12 years and an average BMI of 27 ± 5 kg/m2. At two year follow-up, on multivariate analysis, excellent mHHS (≥ 90%) was significantly associated with only two parameters: a BMI ≤ 25 kg /m2 with an odd ratio OR = 10 (CI95% [2.1-48.3], p = 0.004) and a BMD ≥ 72 mg/cm3 with an odd ratio OR = 4.87 (CI95% [1.2-18.6], p = 0.02). CONCLUSION: The short-term PROMs after cementless THA are impacted by pre-operative cancellous bone density. However, the BMI remains the most influential parameter on the clinical outcomes.

Comparison of custom cutting guides based on three-dimensional computerized CT-scan planning and a conventional ancillary system based on two-dimensional planning in total knee arthroplasty: a randomized controlled trial.

PURPOSE: Incorrect positioning of components during total knee arthroplasty (TKA) increases the risk of pain, instability, and early revision. The purpose of this study was to compare 3D planning-assisted and a conventional system for TKA positioning. We hypothesized that the use of three-dimensional CT-scan planning and custom cutting guides would increase the accuracy of component positioning. METHODS: A randomized, controlled, prospective study of two groups was performed. In one group, patient-specific custom cutting guides (PSCG) were used for component positioning based on 3D CT-scan planning. In the control group, TKA was performed with a conventional ancillary system. The components' positioning angles were measured on 3D reconstructions. The main evaluation criterion was the percentage of outliers outside of a target zone of ± 3° for the coronal positioning of the femoral component. RESULTS: Eighty patients were included. The percentage of outliers for the femoral component was significantly lower in the 3D-guided group (1 patient) compared to the control group (7 patients p = 0.02). The coronal femoral angle was restored with greater accuracy in the 3D-assisted group (- 0.1° ± 1.4°) compared to the control group (1.6° ± 2.5°). Surgery was significantly shorter in the 3D group. The clinical outcomes were better in the 3D group at the two year follow-up with fewer failures and a lower standard deviation in IKS scores. CONCLUSION: The use of a 3D planning and custom guides can improve TKA component positioning by increasing the accuracy of implants alignment and reducing the percentage of outliers. The same benefit was not demonstrated for the global knee alignment and the clinical scores with no indisputable clinical advantage for the PSCG.

Clinical outcomes following arthroscopic treatment of femoro-acetabular impingement using a minimal traction approach and an initial capsulotomy. Minimum two year follow-up.

PURPOSE: Although the arthroscopic management of femoroacetabular impingement (FAI) is increasing, severe complications have been reported due to traction. We developed an arthroscopic technique based on an initial capsulotomy and a minimal traction approach. The main purpose of this study was to analyze the clinical outcomes of FAI treatment using this technique after at least two years of follow-up. METHODS: Forty-seven consecutive patients underwent surgery for FAI. There were two initial portals: a proximal anterolateral portal and a distal anterior instrumental portal. An anterior working space was created and a T-shaped incision was made in the anterior capsule to relieve joint distraction. Short traction (less than 20 mn) made it possible to approach the central compartment. Acetabuloplasty was performed in the presence of pincer impingement. Traction was then released. A head-neck femoral osteochondroplasty was performed in case of bump impingement. All patients underwent a mean 3.3 ± one years of follow-up based on two self-administered questionnaires: the Harris hip score and the QOL Oxford score. None of the patients were lost to follow-up. RESULTS: There were three complications: two ossifications and one case of injury to the femoral cutaneous nerve with good clinical outcomes at the final follow-up. Five patients (10%) underwent surgical revision after a mean 1.4 years of follow-up: three total hip arthroplasties, one peri-acetabular osteotomy, and one repeat arthroscopic hip debridement. The Harris score increased significantly from 60 ± 10 to 86 ± 15 (p < 0.0001) and the Oxford score improved from 34 ± 15 to 50 ± 11. Only 25% of patients had a "forgotten hip" at the final follow-up. CONCLUSION: Our clinical results were comparable to previously reported outcomes with other surgical techniques for the management of FAI. However, it should also be noted that despite these good clinical outcomes, the percentage of patients with a "forgotten hip" is low, and patients should be informed of this.

Three-dimensional analysis of the proximal anterior femoral flare and torsion. Anatomic bases for metaphyseally fixed short stems design.

PURPOSE: The use of femoral stems with a short metaphyseal fixation may lead to fractures or subsidence. Such failures may be related to a mismatch between the torsions or the sagittal flares of the stem and the femur. The goal of our study was to perform a 3D analysis of the proximal metaphyseal femur anatomy with a special focus on the anterior proximal flare and torsion. Such data may help to detect the outlier patients for whom a short metaphyseal fixation should be avoided. METHODS: A prospective study included 80 consecutive patients who underwent a primary cementless THA with a 3D CT-scan based pre-operative planning. A femoral frame was determined in order to analyse the proximal metaphyseal torsion and flares of the femur. RESULTS: The mean metaphyseal torsion was 21.6° ± 7° at 5 mm above the lesser trochanter (LT) and 34.7° ± 8.8 at 15 mm under LT generating a differential torsion of 13° around the LT. The mean flare index was 4.3 ± 0.9 medially, 3.7 ± 0.8 laterally, 2 ± 0.6 anteriorly and 3.1 ± 0.6 posteriorly. The anterior flare was the only flare significantly correlated to the bone density, to the age and to the femoral off-set: the higher the anterior flare index, the younger the patient, the higher the bone density and the higher the femoral offset. The anterior flare was not significantly correlated to the femoral anteversion, the metaphyseal torsion and the coronal neck-shaft angle. CONCLUSION: The proximal femoral metaphysis presents a highly variable anterior flare and torsion that may explain a mismatch between the femur and the femoral stem, consequently generating a risk of subsidence or fracture when using shortly fixed stems. LEVEL OF EVIDENCE: Level IV.

Three-dimensional planning-guided total hip arthroplasty through a minimally invasive direct anterior approach. Clinical outcomes at five years' follow-up.

PURPOSE: The direct anterior approach is an attractive option for total hip arthroplasty (THA) in order to achieve a quicker rehabilitation. However, this surgical technique presents a longer learning curve and a higher complications rate compared with the standard approach. We investigated whether three-dimensional (3D) planning anticipated the surgical difficulties and helped to achieve a low complications rate with respect to intra-operative complications, dislocation risk and lower limb discrepancy (LLD). METHODS: One hundred and fifty-four consecutive patients underwent a primary cementless THA using a direct anterior approach. A 3D planning was performed in order to anticipate the difficulties that may be encountered regarding femur perforation or fracture, dislocation and LLD. All patients were assessed at a mean five years' follow-up. RESULTS: No false route and no fracture occurred at the time of surgery. All the surgical difficulties were anticipated. A motorised reaming procedure of the femur was required in six patients because of a very dense bone or a narrow femur. A retroverted neck was used in 7 % of patients because of a torsional abnormality and enabled an increase in stability. The real implant sizes were the same as the ones planned in 97 % for the cup, 96 % for the stem and 100 % for the neck. At five years' follow-up, no dislocation occurred, no patient complained about LLD and excellent clinical outcomes were achieved. CONCLUSIONS: This study demonstrates that 3D pre-operative planning-guided THA through a minimally invasive direct anterior approach is a safe and accurate procedure. LEVEL OF EVIDENCE: Level IV.

Low Dose Computed Tomography for 3D Planning of Total Hip Arthroplasty: Evaluation of Radiation Exposure and Image Quality.

OBJECTIVE: The aim of the study was to compare radiation exposure and image quality between dedicated computed tomography (CT) protocols for preoperative total hip arthroplasty (THA) planning. METHODS: Three protocols with automated tube current modulation using 64-slice (n = 177) and 128-slice CT scanners without (n = 129) and with automated tube voltage preselection (n = 84) were compared. RESULTS: All 390 CTs were of sufficient quality for THA planning. Mean DLP was 235.0 mGy*cm (effective dose 2.8 mSv). Lowest radiation exposure (2.5 mSv) was seen with automated voltage preselection and the algorithm's selection was 100 kV (90.5% of patients) and 120 kV. Lowest image noise was seen in the highest dose group (3.1 mSv, 128-slice CT fixed tube voltage). A significant difference in cortical bone radiodensity was seen between 100 kV and 120 kV (P < 0.0001). CONCLUSIONS: Preoperative pelvic CT for THA planning is possible with very low radiation dose and reliable quality. Automated voltage preselection further decreases the effective dose by 18.2%.

Muscle histone deacetylase 4 upregulation in amyotrophic lateral sclerosis: potential role in reinnervation ability and disease progression.

Amyotrophic lateral sclerosis is a typically rapidly progressive neurodegenerative disorder affecting motor neurons leading to progressive muscle paralysis and death, usually from respiratory failure, in 3-5 years. Some patients have slow disease progression and prolonged survival, but the underlying mechanisms remain poorly understood. Riluzole, the only approved treatment, only modestly prolongs survival and has no effect on muscle function. In the early phase of the disease, motor neuron loss is initially compensated for by collateral reinnervation, but over time this compensation fails, leading to progressive muscle wasting. The crucial role of muscle histone deacetylase 4 and its regulator microRNA-206 in compensatory reinnervation and disease progression was recently suggested in a mouse model of amyotrophic lateral sclerosis (transgenic mice carrying human mutations in the superoxide dismutase gene). Here, we sought to investigate whether the microRNA-206-histone deacetylase 4 pathway plays a role in muscle compensatory reinnervation in patients with amyotrophic lateral sclerosis and thus contributes to disease outcome differences. We studied muscle reinnervation using high-resolution confocal imaging of neuromuscular junctions in muscle samples obtained from 11 patients with amyotrophic lateral sclerosis, including five long-term survivors. We showed that the proportion of reinnervated neuromuscular junctions was significantly higher in long-term survivors than in patients with rapidly progressive disease. We analysed the expression of muscle candidate genes involved in the reinnervation process and showed that histone deacetylase 4 upregulation was significantly greater in patients with rapidly progressive disease and was negatively correlated with the extent of muscle reinnervation and functional outcome. Conversely, the proposed regulator of histone deacetylase 4, microRNA-206, was upregulated in both patient groups, but did not correlate with disease progression or reinnervation. We conclude that muscle expression of histone deacetylase 4 may be a key factor for muscle reinnervation and disease progression in patients with amyotrophic lateral sclerosis. Specific histone deacetylase 4 inhibitors may then constitute a therapeutic approach to enhancing motor performance and slowing disease progression in amyotrophic lateral sclerosis.

Early neurological recovery course after surgical treatment of cervical spondylotic myelopathy: a prospective study with 2-year follow-up using three different functional assessment tests.

PURPOSE: Though surgical decompression is today a common option for treatment of cervical spondylotic myelopathy (CSM), little is known about the exact postoperative early neurological recovery course. The purpose of this study was to analyze the functional recovery, its dynamics, its intensity and its pattern, in the early postoperative period after surgical decompression for CSM. METHODS: A prospective non-controlled observational study was performed from March 2006 to July 2008, and included consecutive patients with CSM who underwent surgical decompression. Functional assessments were done before the operation, at 1 month, 6, 12, 18 and 24 months after surgery using three tests: the Japanese Orthopaedic Association (JOA) test, the nine-hole peg test (9HPT) and the Crockard walking test. RESULTS: Sixty-seven patients were included (mean age of 61 years). The global JOA score improved after surgery, reaching statistical significance at 1 month (from 11.5 ± 2.6 to 13.6 ± 2.0 points, p = 0.0078), then settling to a plateau till the end of follow-up at 24 months (12.7 ± 2.6 points). The 9HPT and the Crockard test did not show any significant improvement after surgery. CONCLUSIONS: Neurological recovery after surgical decompression has been proved to be very fast during the first month, but stabilizes afterwards. The JOA score is the best assessment to reveal neurological improvement in the early recovery course.

The effect of femoral offset modification on gait after total hip arthroplasty.

BACKGROUND AND PURPOSE: A decrease of 15% in femoral offset (FO) has been reported to generate a weakness of the abductor muscle, but this has not been directly linked to an alteration of gait. Our hypothesis was that this 15% decrease in FO may also generate a clinically detectable alteration in the gait. PATIENTS AND METHODS: We performed a prospective comparative study on 28 patients who underwent total hip arthroplasty (THA) for unilateral primary osteoarthritis. The 3D hip anatomy was analyzed preoperatively and postoperatively. 3 groups were defined according to the alteration in FO following surgery: a minimum decrease of 15% (9 patients), restored (14), and a minimum increase of 15% (5). A gait analysis was performed at 1-year follow-up using an ambulatory device. Each limb was compared to the contralateral healthy limb. RESULTS: In contrast to the "restored" group and the "increased" group, in the "decreased" group there was a statistically significant asymmetry between sides, with reduced range of motion and a lower maximal swing speed on the operated side. INTERPRETATION: A decrease in FO of 15% or more after THA leads to an alteration in the gait. We recommend 3-D preoperative planning because the FO may be underestimated by up to 20% on radiographs and it may therefore not be restored, with clinical consequences.

Does the bone mineral density measured on a preoperative CT scan before total hip arthroplasty reflect the bone's mechanical properties?

INTRODUCTION: No method exists to quantify the bone quality and factors that will ensure osteointegration of total hip arthroplasty (THA) implants. A preoperative CT scan can be used to evaluate the bone mineral density (BMD) when planning a THA procedure. The aim of this study was to validate BMD measurement as a marker of bone quality based on a preoperative CT scan. HYPOTHESIS: BMD reflects the bone's mechanical properties for the purposes of preoperative THA planning. METHODS: Patients who underwent primary THA for hip osteoarthritis or dysplasia with cementless implants and 3D preoperative plan were enrolled prospectively. The cortical BMD was calculated on CT scans used in the preoperative planning process. During the surgical procedure, the femoral head and neck were collected. These bone samples were subsequently scanned with a calibrated micro-CT scanner. The BMD was derived from the micro-CT scan and used as input for a finite element model to determine the bone's mechanical properties. Correlations between BMD, apparent moduli of elasticity and porosity were calculated. RESULTS: The values of cortical BMD measured on the micro-CT and CT scan were significantly correlated (cc=0.52). The mean angular cortical BMD measured with the micro-CT scan was 1472.33mg/cm3 (SD: 357.53mg/cm3, 980.64-2830.6mg/cm3). There was no significant correlation between cortical BMD and the various apparent moduli of elasticity, except for Eyy and Gzy. Cortical BMD and porosity were inversely correlated with a Spearman coefficient of -0.41 (CI95: [-0.71; -0.02], p=0.03). There was also an inverse correlation between the apparent moduli of elasticity (independent of their orientation) and porosity (p<0.01). DISCUSSION: BMD provides information about porosity, which is a major factor when evaluating the bone's mechanical properties before THA. LEVEL OF EVIDENCE: IV.

Higher femoral anteversion restoration accuracy after total hip arthroplasty with a proximally fixed anatomic stem than with a generic straight double-tapered stem.

BACKGROUND: Femoral antetorsion in uncemented hip replacement hardly can be modified and the restoration of the anatomic anteversion might be difficult with standard stems. We compared femoral anteversion restoration of a generic straight stem with a proximally fixed anatomic stem that included a dual sagittal curvature and a proximal torsion. It was hypothesised that the restoration of the anteversion was more accurate with the anatomic stem. PATIENTS AND METHODS: In this comparative study data were collected prospectively of 80 consecutive patients with total hip arthroplasty for primary osteoarthritis. In the first 40 patients (Group I) a cementless proximally fixed anatomic stem with 15° antetorsion of the shaft and a dual sagittal curvature was used. Its design was based on a database of 3D CT images of 600 hips. For comparison a cementless generic straight double-tapered stem was implanted in the next 40 patients (Group II). All operations were performed by one experienced surgeon. All patients had a preoperative 3D planning. A low-dose CT scan was performed at 3 months postoperatively to determine the postoperative stem anteversion. RESULTS: The demographics were similar in both groups. In group I the mean postoperative femoral anteversion was similar to the preoperative one (22.1° ± 10.2° vs. 20.4° ± 9°; p = 0.2). In Group II, the mean postoperative femoral anteversion was lower (12.9° ± 10.8°, vs. 18.3° ± 12°; p = 0.02). CONCLUSIONS: Uncemented standard femoral stems tend to reduce femoral anteversion. The used anatomic stem restored femoral anteversion better. The clinical impact of this finding has to be proven.

High 10-year survival rate with an anatomic cementless stem (SPS).

BACKGROUND: Proximal cementless fixation using anatomic stems reportedly increases femoral fit and avoids stress-shielding. However, thigh pain was reported with the early stem designs. Therefore, a new anatomic cementless stem design was based on an average three-dimensional metaphyseal femoral shape. However, it is unclear whether this stem reduces the incidence of thigh pain. QUESTIONS/PURPOSES: We asked whether this stem design was associated with a low incidence of thigh pain and provided durable fixation and high function. METHODS: One hundred seventy-one patients (176 THAs) who had the anatomic proximal hydroxyapatite-coated stem implanted were reviewed. Eleven (6%) patients were lost to followup and 34 (20%) died without revision surgery. We used the Harris hip score (HHS) to assess pain and function. We evaluated femoral stem fixation and stability with the score of Engh et al. and also calculated a 10-year survival analysis. We assessed 126 patients (131 hips) at a mean followup of 10 years (range, 8-11 years) RESULTS: At last followup, two patients described slight thigh pain that did not limit their physical activities. All stems appeared radiographically stable and one stem was graded nonintegrated but stable. Five patients had revision surgery: one on the femoral side (for posttraumatic fracture) and four on the acetabular side. Considering stem revision for aseptic loosening as the end point, survivorship was 100% (range, 95.4%-99.9%) at 10 years. CONCLUSION: This anatomic cementless design using only metaphyseal fixation with a wide mediolateral flare, a sagittal curvature, and torsion, allowed durable proximal stem stability and fixation.

Surgical epicondylar axis is not orthogonal to the femoral mechanical knee axis in valgus knees with primary osteoarthritis: Three-dimensional analysis according to knee coronal alignment in 112 patients.

BACKGROUND: During total knee arthroplasty (TKA), most surgeons align the femoral component along the surgical epicondylar axis (SEA) considering it as orthogonal to the femoral mechanical axis. However, it is still unclear how SEA coronal alignment varies according to the native coronal knee alignment. The main goal of this study was to analyze the SEA orientation according to the native coronal knee morphotype. METHODS: A total of 112 patients underwent a three-dimensional (3D) -planning-based TKA. The SEA was then determined by locating the epicondyles on 3D models. The 3D femoral and tibial mechanical axes were marked and the femoral (FMA) and tibial (TMA) mechanical angles were measured. The native HKA angle was measured as FMA + TMA. The SEA orientation angles were measured in the coronal (SEA-α) and axial (SEA-ß) plane. SEA orientation was compared between the valgus, neutral, and varus knees. RESULTS: The mean SEA-α angle was 90.2 ± 3° and the mean axial SEA-ß angle was 92.2 ± 1.3°. The SEA-α angle was significantly higher in the valgus group compared with the neutral group (92.3 ± 2.9°, 90 ± 2.9°, P = 0.0009) whereas there was no significant difference in the SEA-α angle between the varus and the neutral group (89.7 ± 2.3°, 90 ± 2.9°, P = 0.32). CONCLUSIONS: In contrast to the neutral and varus knees, the SEA was not orthogonal to the femoral mechanical axis in patients undergoing TKA for primary osteoarthritis. Our results suggest adapting the coronal alignment of the femoral component during TKA, while maintaining an average 2° valgus in valgus knees. By contrast, with varus and neutral knees, our data support the use of a mechanical alignment.

Undetected fracture of an alumina ceramic on ceramic hip prosthesis.

An unusual case of undetected ceramic fracture was discovered by coincidence during total hip arthroplasty revision for sepsis. To our knowledge, this kind of fracture has never been described before. The cup liner was broken in 2 parts, consisting of a large outer annulus and a smaller round central piece that was detached from the superior and posterior part of the cup, creating a hole in the cup. The analysis of the retrievals suggests that the fracture occurred during walking at the contact point between the head and the cup. The ceramic breakage was asymptomatic with no mechanical disorder, suggesting that some ceramic fracture may be tolerated in vivo. However, any evidence of a fractured ceramic component should cause the surgeon to strongly consider revision.

Modification of regional bone mineral density due to femoral rasping in cementless proximally fixed total hip arthroplasty.

BACKGROUND: Three-dimensional planning (3DP) in total hip arthroplasty using computed tomography (CT) to analyze bone mineral density (BMD) at the stem-femur interface has a high reported accuracy and excellent mid-term results in the literature. However, 3DP does not take into account the effect of femoral rasping on BMD distribution within the rasped cavity. Characterizing the impact of femoral rasping on BMD may help avoid mechanical failures, but this data is not accurately investigated. Therefore, we set out a cadaveric study to identify if: (1) Femoral rasping modified regional BMD in areas considered critical for bone anchorage of cementless metaphyseally fixed anatomic stems. (2) In areas of bone-implant contact with an initial high BMD, does femoral rasping increase BMD? HYPOTHESIS: Femoral rasping increases BMD in some zones considered critical for bone anchorage of cementless metaphyseally fixed anatomic stems within the rasped femoral cavity. METHODS: Four cadaveric femurs were selected to undergo a rasping procedure similar to surgical techniques used for metaphyseally fixed anatomic stems. Images of femurs before and after rasping were obtained with a micro-CT scanner (pixel size 35µm). BMD values before and after rasping were compared in a trabecular bone ring of 3mm thickness around the cavity created by the rasps, in a region extending 3cm above and 2cm below the middle of the lesser trochanter. RESULTS: Average BMD increased significantly after rasping in 3 of the 4 femurs (13% (0.27 to 0.30) (p=0.004)), 12% (0.32 to 0.36 (p=0.034)) and 15% (0.4 to 0.46 (p=0.001)), while there was no significant variation in the last femur (0.32 to 0.32 (p>0.05)). Increases in regional BMD were significantly higher in the lateral and medial areas, as well as in the most distal femoral regions. There were significantly lower variations of BMD in regions with initially higher BMD. DISCUSSION: Current opinion considers trabecular bone debris from femoral rasping to have an impact on final stem position and outcome. Our study has demonstrated an overall positive effect of femoral rasping on BMD in the rasped cavity. Understanding this in the context of 3DP may help avoid mechanical failures such as, suboptimal implant fit, fill, and stability as well as femoral fractures during stem implantation. LEVEL OF EVIDENCE: IV, Prospective in vitro study.

Mechanical spinal cord compression at the apex of a kyphosis: a propos of one case. Review of the literature.

There are a few case reports in the literature on mechanical compressions of the spinal cord associated with Scheuermann's disease and the treatment is not codified. We describe a case of spinal cord compression at the apex of the kyphosis, which disappeared with the reduction of the deformity. Given the skeletal immaturity, anterior and posterior fusions had to be performed together in order to obtain a good result.

Femoroacetabular impingement treatment using arthroscopy and anterior approach.

Femoroacetabular impingement (FAI) has been identified as a common cause of hip pain in young adults. However, treatment is not well standardized. We retrospectively reviewed 97 patients (100 hips) who underwent osteochondroplasty of the femoral head-neck for FAI using a mini-open anterior Hueter approach with arthroscopic assistance. The mean age of the patients was 33.4 years. The labrum was refixed in 40 hips, partially excised in 39 cases, completely excised in 14 cases, and left intact in seven. Six patients were lost to followup, leaving 91 (94 hips) with a minimum followup of 28.6 months (mean, 58.3 months; range, 28.6-104.4 months). We assessed patients clinically using the nonarthritic hip score (NAHS). One patient had a femoral neck fracture 3 weeks postoperatively. At the last followup, the mean NAHS score increased by 29.1 points (54.8 +/- 12 preoperatively to 83.9 +/- 16 points at last followup). Eleven hips developed osteoarthritis and subsequently had total hip arthroplasty. The best results were obtained in patients younger than 40 years old with a 0 Tönnis grade. Refixation of the labrum did not correlate with a higher NAHS score (87 +/- 11 with refixation versus 82 +/- 19 points without) at the last followup. The technique for FAI treatment allowed direct visualization of the anterior femoral head-neck junction while avoiding surgical dislocation, had a low complication rate, and improved functional scores.

Modification of tibial slope after medial opening wedge high tibial osteotomy: clinical study and mathematical modelling.

A prospective non-randomized non-comparative study involved 30 patients who underwent a medial opening wedge high tibial osteotomy for medial knee osteoarthritis using a specific surgical procedure. The tibial slope was calculated pre-operatively and at a mean follow-up of 14 months. A mathematical model of the surgical procedure was developed in order to plan the height of the medial opening wedge and to predict tibial slope changes. Tibial-slope measurements accuracy was good (0.04 degrees +/- 0.92 degrees ). There was no significant difference for the mean tibial slope before and after surgery (9.2 degrees +/- 5.6 degrees vs. 9.1 degrees +/- 5.6 degrees , P = 0.47). There was a perfect agreement between the model and the real values for the HKA angle (0.85) and the tibial slope (0.98). The surgical technique used did not modify the tibial slope. Our mathematical model for pre-operative planning was validated with very good accuracy.

Three-dimensional hip anatomy in osteoarthritis. Analysis of the femoral offset.

Two hundred twenty-three patients with osteoarthritic hips were analyzed using computed tomography and a specific image processing software (HIP-PLAN) to determine 3-dimensional morphological data of the hip focusing on femoral offset (FO). Mean FO was found to be 42.2 +/- 5.1 mm, 2.2 mm greater than the 2-dimensional FO values reported in the literature. The FO was found to be above 45 mm in 31% of patients and greater than 50 mm in 12%. The error associated with the use of conventional plane x-rays to measure FO was found to be 3.5 +/- 2.5 mm, the x-ray technique generally underestimating the measure of FO. The sum of acetabular and femoral anteversion was found to be out of the safe zone regarding dislocation risk in 47% of patients.