Elhadi Sariali

Dislocation After Total Hip Arthroplasty Using Hueter Anterior Approach

A prospective study including 1764 hips has been carried out to evaluate the frequency of dislocation while using the Hueter anterior approach and the correlated factors. The dislocation group was compared with the patients without dislocation. We observed 27 dislocations (1.5%). The dislocation rate when using 28 mm head diameter was 0.5%. Two patients underwent a revision for recurrent dislocations. Correlated factors for dislocation were male sex, high body mass index, etiology of osteonecrosis, low head diameter, high bleeding, and low postoperative ROM. Dislocation risk while using Hueter approach is one of the lowest in the literature. The main disadvantages are the necessity for a specific orthopedic table and a more difficult exposure of the femur.

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.

Accuracy of the preoperative planning for cementless total hip arthroplasty. A randomised comparison between three-dimensional computerised planning and conventional templating.

INTRODUCTION A high accuracy was recently reported for the three-dimensional (3D) computerised planning of total hip arthroplasty (THA), comparing well with navigation regarding leg length and femoral offset. However, there is no randomised study comparing 3D preoperative planning with conventional 2D templating in terms of accuracy and clinical relevance. HYPOTHESIS The 3D preoperative planning has a higher accuracy than the conventional 2D preoperative templating regarding the implants size and their positioning. PATIENTS AND METHODS A prospective comparative randomised study was carried out from 2008 to 2009, including two groups of 30 patients who underwent THA for primary osteoarthritis. One surgeon performed all the surgical procedures using a minimally invasive direct anterior approach. In one group, the planning was made on calibrated X-rays using 2D templates. In the other group, a CT-scan based 3D computerised planning was performed with dedicated software. The reconstructed hip final anatomy was compared postoperatively to the preoperative planning and the accuracy was expressed as the mean difference (±SD) between the planned positioning and the final positioning of the implants. RESULTS The prediction rate for the stem and the cup sizes were respectively of 100% and 96% in the 3D group versus 43% for both components in the 2D group. When combining both components, the prediction rate was 96% in the 3D group versus 16% in the 2D group. In the 3D group, a high accuracy was achieved for the planning of the leg length (-1.8±3.6 mm ranging from -8 to+4mm) and the femoral offset (-0.07±2.7 mm ranging from -5 to+4mm) versus 1.37±6.4mm ranging from -9 to 13 mm and 0.33±5.7 mm (-16 to 11 mm) in the 2D templating group (P<0.0001). DISCUSSION The 3D planning gives a higher accuracy than conventional 2D templating in forecasting the size of cup and the stem. This contributes to the prediction for leg length and offset that is more reliable with the 3D technique. This study suggests that 3D planning CT-scan data is an attractive alternative to navigation to restore these parameters. The high accuracy achieved by a low-experience surgeon suggests that 3D planning may help shorten the learning curve when using the minimally invasive direct anterior approach. LEVEL OF EVIDENCE Level III low-powered prospective randomized trial.

Infected total hip arthroplasty revision: one- or two-stage procedure?

INTRODUCTION Better outcomes have been reported for two-stage total hip arthroplasty (THA) revision for infection. However, one-stage revision arthroplasty remains an attractive alternative option since it requires only one operation. A decision tree has been developed by the authors in order to determine which type of surgical procedure can be performed safely. The goal of this study was to assess this decision tree for THA replacement in the case of a peri-prosthetic infection. HYPOTHESIS A one-stage procedure may be as successful as a two-stage procedure provided some criteria are fulfilled. METHODS A prospective study included 84 patients, all diagnosed with infected THA who had prosthesis replacement. A one-stage exchange was performed in 38 cases and a two-stage procedure in 46 cases. A two-stage procedure was decided in the case of important bone loss or unidentified germ. Postoperatively, patients received intravenous antibiotics (six weeks), then oral antibiotics (six weeks). The main evaluation criterion was the rate of infection eradication at 2 years minimal follow-up since surgery. If new infection was suspected, a hip aspiration was performed to determine whether it was non-eradication (same germ) or a new re-infection (other germ), which was not considered as a failure. RESULTS The initial infection was cured in 83 out of 84 patients (98.8%), 38 (100%) for the one-stage group and 45 (97.8%) for the two-stage group. Three patients were re-infected with different germs in the two-stage group. Eighty out of 84 (95.2%) patients were infection free, all patients (100%) of the one-stage group and 42 patients (91.3%) of two-stage group. DISCUSSION If some selection criteria were respected, a high success rate in THA replacement for infection may be achieved with a one-stage procedure. It permits to reduce the costs with no loss of chance for the patients. The decision tree was validated. LEVEL OF EVIDENCE Level III; prospective case control study.

Mathematical evaluation of jumping distance in total hip arthroplasty: influence of abduction angle, femoral head offset, and head diameter.

Background and purpose The jumping distance (JD) is the degree of lateral translation of the femoral head center required before dislocation occurs. The smaller the distance, the higher the theoretical risk of dislocation. The aim of our study was to evaluate this jumping distance and its variation according to the characteristics of the implant, and also the theoretical gain in using large head diameters of above 38 mm. Methods The JD was calculated as a function of the cup ante-version and abduction angles, the head diameter, and the head offset (defined as the distance between the center of the femoral head and the cup opening plane). Head diameters of 28, 32, 36, 40, 44 and 48 mm were analyzed. The abduction angle was increased from 0° to 80° with a 10° increment. The anteversion angle was increased from 0° to 40° with a 5° increment. Results The jumping distance was found to decrease as the cup abduction angle increased (0.25 mm each 1° for 32-mm head diameter). It increased by 0.05 mm for a 1° increase in the ante-version angle. The jumping distance increased as the head diameter increased (0.4 mm each mm diameter for a 45° abduction angle). The net gain obtained by increasing the diameter, however, decreased when abduction angle increased (0.25 each mm diameter for 60° abduction). The JD decreased by 0.92 mm for each 1-mm increase in head offset, showing that head offset was the most important parameter influencing the JD. Interpretation The theoretical gain in stability obtained by using a large femoral head (above 36 mm) is negligible in cases where there is a high cup abduction angle. An increase in offset of the femoral head substantially reduces the jumping distance and it should therefore be avoided.

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.

In vitro investigation of friction under edge-loading conditions for ceramic-on-ceramic total hip prosthesis.

Edge‐loading generates higher wear rates in ceramic‐on‐ceramic total hip prosthesis (THP). To investigate the friction coefficient (FC) in these conditions, three alumina ceramic (Biolox Forte) 32 mm‐diameter components were tested using a hip friction simulator. The cup was positioned with a 75° abduction angle to achieve edge‐loading conditions. The motion was first applied along the edge and then across the edge of the cup. First, tests were conducted under lubricated conditions with 25% bovine serum. Next, to simulate an extremely high contact pressure, the tests were run with the addition of a third body alumina ceramic chip inserted between the edge of the cup and the head. Engineering blue was used to analyze the contact area. Reference values were determined using a 0° cup abduction angle. Edge loading was achieved. The FC increased by three‐ to sixfold when the motion was applied along the edge, and by 70% when the motion was applied across the edge. However, the FC value was still low (about 0.1), which is similar to metal‐on‐metal THP. With the third body alumina ceramic particle inserted, the FC was 26 times higher than in the ideal conditions and intermittent squeaking occurred. High cup abduction angles may generate edge‐loading and an increase in the friction coefficient for ceramic THP.

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.

Three-dimensional modeling of in vitro hip kinematics under micro-separation regime for ceramic on ceramic total hip prosthesis: An analysis of vibration and noise

Micro-separation corresponds to a medial-lateral hip laxity after total hip replacement (THR). This laxity has been shown to generate higher wear rates and a specific pattern of stripe wear caused by edge loading of the head on the rim of the cup. Recently some authors have implicated edge loading as a source of noise generation and in particular squeaking. The goal of this study was to model hip kinematics under the micro-separation regime in a computational simulation of total hip prosthesis including joint laxity and to analyze the vibration frequencies and the potential for noise generation. A three-dimensional computer model of the Leeds II hip simulator was developed using ADAMS((R)) software, simulating a controlled micro-separation during the swing phase of the walking cycle and replicating the experimental conditions previously reported. There was an excellent correlation between the theoretical values and the experimental values of the medial-lateral separation during the walking cycle. Vibratory frequencies were in the audible zone but were lower in magnitude than those reported clinically in relation to squeaking. Micro-separation and rim loading may explain the generation of some sounds from noisy hips after THR. However, the computational model, and the experimental model of micro-separation were unable to replicate the higher frequency squeaking reported clinically. In contrast, other experimental studies involving normal kinematics in combination with third-body particles have replicated clinically relevant frequencies and noises.

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.