Influence of Skin Marker Positioning and Their Combinations on Hip Joint Center Estimation Using the Functional Method.

Accurate estimation of hip joint center (HJC) position is crucial during gait analysis. HJC is obtained with predictive or functional methods. But in the functional method, there is no consensus on where to place the skin markers and which combination to use. The objective of this study was to analyze how different combinations of skin markers affect the estimation of HJC position relative to predictive methods. Forty-one healthy volunteers were included in this study; thirteen markers were placed on the pelvis and hip of each subject's lower limbs. Various marker combinations were used to determine the HJC position based on ten calibration movement trials, captured by a motion capture system. The estimated HJC position for each combination was evaluated by focusing on the range and standard deviation of the mean norm values of HJC and the mean X, Y, Z coordinates of HJC for each limb. The combinations that produced the best estimates incorporated the markers on the pelvis and on proximal and easily identifiable muscles, with results close to predictive methods. The combination that excluded the markers on the pelvis was not robust in estimating the HJC position.

Gait analysis after total hip arthroplasty by direct minimally invasive anterolateral approach: A controlled study.

INTRODUCTION: Clinical and functional improvement after minimally invasive total hip arthroplasty (THA) has become increasingly controversial. The minimally invasive anterolateral approach (MIALA) allows rapid recovery resulting in a reduced need for rehabilitation. Alterations in muscle and static balance have previously been demonstrated. Results in the context of quantified gait analysis (QGA) and MIALA compared to an asymptomatic population remain unknown beyond one year postoperatively. Thus, the main objective of this controlled study was to compare the spatiotemporal parameters of gait, obtained using a QGA, beyond one year postoperatively in subjects operated on for THA by MIALA, with a group of asymptomatic subjects of the same age. The secondary objectives of the study were to compare the other QGA and EMG data acquired in operated subjects with asymptomatic subjects. HYPOTHESIS: We hypothesized that QGA and EMG parameters would not normalize beyond one year postoperatively. PATIENTS AND METHODS: Thirty-one subjects were recruited, including 16 patients (68 years old; IQR: 65-70) who underwent MIALA, at 15.5 months postoperatively (IQR: 13-17) and 15 asymptomatic subjects (62 years old; IQR: 61-71). Subjects underwent QGA and maximal isometric muscle force tests on the gluteus medius, gluteus maximus, Tensor Fascia Lata (TFL) and Sartorius muscles. Spatiotemporal gait parameters were the primary endpoint. The other QGA parameters: kinetics (characteristic values of vertical ground reaction forces, peak hip moments) and kinematics (hip joint amplitudes and pelvic mobility in the frontal and sagittal plane) constituted the secondary criteria. RESULTS: Five subjects were excluded for unrestored offset. Walking speed was lower in operated patients (1.03m/s versus 1.18m/s, p=0.005). Maximal isometric muscle force moments were lower in patients operated on for the gluteus maximus and medius as well as the TFL (p<0.005). The vertical ground reaction forces were lower for the operated patients for the loading phase (FzFCmax, p=0.001), the single stance phase (FzSPmin, p=5.05.10-2) and the swing phase (FzTOmax, p=0.0002). The moments were lower in the sagittal plane for the operated patients (0.6N.m for the operated versus 1.1N.m for the asymptomatic, p=0.02). The pelvic amplitudes in the sagittal plane were lower for operated patients (3.3° versus 7.2°, p=0.05). DISCUSSION: Our hypothesis appears to be validated. Gait deficits persisted beyond one year postoperatively after THA with MIALA. A decrease in walking speed, maximal isometric muscle force of the gluteus medius and gluteus maximus and TFL was observed, as well as a decrease in propulsive force and peak hip moment. Functionally, these results could signify muscle damage following surgery, requiring rehabilitation for improved muscle function. LEVEL OF PROOF: III: Non-randomized controlled trial.

MRI assessment of minimally invasive anterolateral approaches in total hip arthroplasty.

INTRODUCTION: Total hip arthroplasty (THA) on a minimally invasive anterolateral (MIAL) approach frequently leads to gluteus minimus and gluteus medius lesions, and sometimes to tensor fasciae latae (TFL) denervation. We therefore developed compensatory strategies, which we assessed on pre- and post-operative MRI: 1) to assess gluteus minimus and gluteus medius fatty infiltration (FI), 2) to assess TFL FI, and 3) to assess FI in the other periarticular muscles. HYPOTHESIS: The modified MIAL approach reduces the rate of gluteus minimus and gluteus medius lesion. MATERIALS AND METHODS: A continuous prospective single-surgeon series of THA using a MIAL approach included 25 patients. Femoral implantation was performed with the hip in extension so as to distance the proximal femur from the gluteals, avoiding muscle trauma. The superior gluteal nerve branch in the space between the gluteus medius and TFL, running toward the TFL, was systematically released and protected. MRI was performed preoperatively and at 3 months and 1 year post-surgery. FI was analyzed according to the Goutallier classification in all periarticular muscles. RESULTS: One patient lacked preoperative MRI and was excluded, leaving 24 patients, for 72 MRIs. In 10/24 patients (41.7%) the gluteus minimus and in 8/24 patients (33.3%) the anterior third of the gluteus medius showed ≥2 grade increase in FI between preoperative and 1-year MRI, with significant increases in both at 3 months (p<0.001) and 1 year (p<0.001). At least a 2 grade increase in FI at 1 year was seen in 1 patient (4.2%) in the TFL, in 2 (8.3%) in the piriformis, and in 1 (4.2%) in the obturator internus. There were no significant differences in FI between preoperative, 3-month or 1-year MRI in any other periarticular muscles. CONCLUSION: Femoral implantation in hip extension did not reduce the rate of gluteal lesions, which remained frequent. In contrast, release of the superior gluteal nerve branch could be effective in conserving TFL innervation. Some rare lesions of the proximal part of the pelvi-trochanteric muscles were also observed. LEVEL OF EVIDENCE: IV, Prospective case series.

Comparative MRI assessment of three minimally invasive approaches in total hip arthroplasty.

INTRODUCTION: Minimally invasive approaches (direct anterior approach: DAA; minimally invasive anterolateral: MIAL; piriformis-sparing posterior approach: PSPA) are widely used for total hip arthroplasty (THA), with a muscle-sparing objective. There are no published comparative studies of muscle damage secondary to these approaches. The aim of the present study was to compare fatty infiltration (FI) on MRI induced by DAA, MIAL and PSPA in THA 1) in the tensor fasciae latae (TFL) and sartorius muscles, 2) in the gluteal muscles, and 3) in the pelvitrochanteric muscles. HYPOTHESIS: Greater FI is induced by DAA in anterior muscles, by MIAL in gluteal muscles and by PSPA in pelvitrochanteric muscles. MATERIALS AND METHODS: Three continuous prospective series of THA by DAA, MIAL and PSPA included 25 patients each. MRI was performed preoperatively and at 1 year postoperatively. FI was graded on the Goutallier classification in all periarticular hip muscles. Muscles showing ≥2 grade aggravation at 1 year were considered damaged. RESULTS: Nine patients whose preoperative MRI was uninterpretable were excluded. In all, 66 patients (21 DAA, 24 MIAL and 21 PSPA) with 132 MRI scans were analyzed. TFL was damaged in 2/21 DAA patients (9.5%), 1/24 MIAL patients (4.2%) and 0/21 PSPA patients (0%). There were no sartorius lesions. The anterior third of the gluteus medius was damaged in 8/24 MIAL patients (33.3%) and the gluteus minimus in 10/24 (41.7%), compared to 1/21 DAA patients (4.8%) and 0/21 PSPA patients (0%). The mid and posterior thirds of the gluteus medius and the gluteus maximus were never damaged. The piriformis muscle was damaged in 3/21 DAA patients (14.3%), 2/24 MIAL patients (8.3%) and 2/21 PSPA patients (9.5%). The obturator internus was damaged in 4/21 DAA patients (19%), 1/24 MIAL patients (4.2%) and 16/21 PSPA patients (76.2%). The obturator externus and quadratus femoris were mainly damaged in PSPA patients: respectively, 5/21 (23.8%) and 4/21 patients (19%)). CONCLUSION: The muscle-sparing properties of minimally invasive hip approaches are only theoretical. In the present series, there were rare TFL lesions with DAA and MIAL. Gluteus medius and minimus lesions were frequent in MIAL. Pelvitrochanteric muscles lesions were more frequent in PSPA, but found in all 3 approaches. These findings should help guide surgeons in their choice of approach and in informing patients about the damage these minimally invasive approaches can cause. LEVEL OF EVIDENCE: III, prospective comparative study.

Quantitative gait analysis after total hip arthroplasty through a minimally invasive direct anterior approach: A case control study.

INTRODUCTION: Total Hip Arthroplasty (THA) leads to excellent clinical and functional results. The Minimally Invasive Anterior Approach (MIAA) theoretically allows rapid recovery and a reduction in the need for rehabilitation, but alterations in muscle and static balance have previously been demonstrated. Kinetic, kinematic and muscular alterations have been shown to persist up to 1year postoperatively but data beyond 1year postoperatively is lacking. Thus, the objective of this study was to compare the data from Quantitative Gait Analysis (QGA) coupled with electromyography (EMG), of patients one year postoperatively with THA through MIAA, compared to an asymptomatic control group. HYPOTHESIS: We hypothesized that QGA and EMG parameters would not normalize beyond one year postoperatively. PATIENTS AND METHODS: Twenty-seven patients were recruited, including 15 subjects (64.6±6.6years) operated on by MIAA, who at 15.9±3.1months postoperatively, along with 12 asymptomatic control subjects (68.9±9.7years), who underwent QGA and maximal isometric muscle strength tests, coupled with EMG on the gluteus medius and maximus, Tensor Fascia Lata (TFL) and Sartorius muscles. The spatiotemporal parameters of walking (step length, walking speed, cadence, single leg support time), kinetics (vertical ground reaction forces, hip moments in the 3 planes) and kinematics (coxofemoral and pelvic amplitudes) were analyzed. RESULTS: The walking speed was lower on the non-operated side of the experimental subjects (0.96ms-1 compared to 1.13ms-1 for asymptomatic [p=0.018]), as was the step length on the operated side (0.53m compared to 0.60m for asymptomatic [p=0.042]). Maximal isometric muscle strength was lower in subjects operated on for the gluteus maximus and medius (p=0.004), compared to asymptomatic subjects. Moments were lower in the subjects operated on in extension (0.72Nm on the operated side, 0.75Nm on the non-operated side compared to 1.06Nm for asymptomatic [p=0.007 and p=0.024]) and lateral rotation (0.09Nm on the operated side, 0.05Nm on the non-operated side compared to 0.16Nm for asymptomatic subjects [p=0.009 and p=0.0005]). Hip adduction amplitudes were lower on the operated side compared to asymptomatic subjects (3.93° versus 9.14° for asymptomatic [p=0.005]). Pelvic amplitudes in the frontal plane were lower amongst operated subjects (0.44° against 1.97° for asymptomatic [p=0.041]). Pelvic amplitudes in the sagittal plane were higher in the operated subjects (15.74° on the operated side, 15.43° on the non-operated side compared to 9.65° for asymptomatic [p=0.041 and p=0.032]). DISCUSSION: Our initial hypothesis was validated, since walking deficits persisted beyond one year postoperatively after THA through MIAA. A decrease in maximal isometric muscle strength of the gluteus medius and gluteus maximus was observed, as well as an alteration of kinetic and kinematic parameters in the sagittal and frontal planes. The results were in agreement with the literature and reflected the establishment of compensatory mechanisms to overcome alterations in joint strength and range more than one year postoperatively. These results would allow rehabilitation programs to be more specific and would justify a study on the other approaches for THA. LEVEL OF EVIDENCE: III; non-randomized control trial.

Stabilometric assessments of two rehabilitation protocols on postural parameters after posterior total hip arthroplasty: A prospective randomized comparative study.

INTRODUCTION: After total hip arthroplasty (THA), patients continue to have muscular, functional and postural deficits. The literature seems to support the use of postoperative rehabilitation, especially self-directed programs. However, there is no set protocol for the management of postural disorders. Therefore, the purpose of this study was to compare postural parameters of a group of patients who underwent posterior THA followed by 2 different types of rehabilitation (stabilometric platform (SP) and home-based self-directed protocols) with a control group of operated patients who did not undergo rehabilitation and a control group of age-matched asymptomatic subjects. HYPOTHESIS: We hypothesized that rehabilitation would normalize the stabilometric parameters. PATIENTS AND METHODS: A total of 67 subjects were enrolled in this study (mean age 67.85±1.22years) and divided into 4 groups. Forty-one of these subjects had undergone a posterior THA were randomly assigned between D10 and D21 to one of the following 3 groups: no rehabilitation control group (THACG=14), supervised rehabilitation with a stabilometric platform group (RSPG=16), and a self-directed home-based rehabilitation group (SDHRG=11). The 4th group was a control group made up of 26 age-matched asymptomatic nonoperated subjects (CG55-80). These rehabilitation protocols lasted 3weeks. At the end of the 3weeks, the groups performed the same stabilometric single leg and double leg stance tests (considering lower limb dominance) on an SP. RESULTS: No significant differences were observed between groups in the bipedal stance, except between the CG55-80 and the THACG, where a higher energy expenditure was observed in the THACG during the static stance with eyes open (EO) and eyes closed (EC): increase in the path length (Plength) covered by the center of pressure (COP) (EO: p=01; EC: p=03) and the average velocity (Vavg) of the COP (EO: p=01; EC: p=03). These differences were not observed in the SDHRG and RSPG whether they were compared with one another or with both control groups. In the unipedal stance, subjects in the RSPG and SDHRG showed greater muscle activity in the anterior and posterior chains and hip abductors, and used less energy to maintain the stance than those in the CG55-80, regardless of lower limb dominance: decrease in the mediolateral range of COP displacement (Xrange) (hip abductor muscles) (p=02) and anteroposterior range of COP displacement (Yrange) (anterior and posterior chains) (p=3.49.10-3), 95% confidence ellipse area (Earea) of COP data (p=1.47.10-3), Plength (p=04) and Vavg (p=04). The RSPG had a smaller Earea than the SDHRG (p=04), demonstrating a better postural stability during the unipedal stance performed on the dominant operated leg. DISCUSSION: Our results were consistent with the literature on the benefits of rehabilitation after THA, thus confirming our hypothesis that rehabilitation normalized stabilometric parameters between D31-D45, depending on the subjects. These results provide new information regarding rehabilitation techniques to be implemented postoperatively after a THA. A home-based self-directed rehabilitation program is just as effective as an SP program in managing postural disorders. LEVEL OF EVIDENCE: II; randomized controlled trial with low statistical power.

MRI assessment of piriformis-sparing posterior approach in total hip arthroplasty.

INTRODUCTION: In total hip arthroplasty (THA), the posterior approach is the most common throughout the world. Dislocation is one of the main complications incurred, but the risk may be reduced by sparing posterior structures. Thus, piriformis-sparing posterior approaches (PSPA) were described, and satisfactory conservation of the muscle was reported. On the other hand, a recent cadaver study reported occult intrapelvic piriformis lesions in 91% of cases. In the light of this discordance, we performed pre- and postoperative MRI in THA by PSPA: 1) to assess the fatty infiltration of the piriformis induced by the approach, with particular attention to intrapelvic lesions; and 2) to assess fatty infiltration of the other periarticular muscles. HYPOTHESIS: The piriformis muscle will show little fatty infiltration following PSPA. MATERIALS AND METHODS: A continuous prospective single-surgeon series of THA by PSPA included 25 patients. MRI was performed preoperatively and at 3 months and 1 year postoperatively. Fatty infiltration was assessed on the Goutallier classification in all periarticular muscles. RESULTS: Preoperative MRI was lacking in 4 patients, who were excluded from analysis; 21 patients with MRI were thus analyzed. In the piriformis muscle, there was no significant change in fatty infiltration between preoperative and 3-month (p=0.29) or 1-year (p=0.41) MRI. Two of the 21 patients (9.5%) showed grade 3 or 4 fatty infiltration at 1 year, compared to 0/21 (0%) preoperatively; both showed sacral avulsion of the piriformis. Significant differences between preoperative and 1-year MRI were found for the obturator internus and externus, with grade 3 or 4 infiltration at 1 year in 14 cases for the obturator internus (14/21: 66.7%), in 3/21 for the obturator externus (14.3%) and in 6/21 for the quadratus femoris (28.6%), compared to respectively 0/21 (0%), 0/21 (0%) and 3/21 (14.3%) preoperatively. There were no significant differences for any of the other periarticular muscles. CONCLUSION: PSPA in THA ensured good conservation of the piriformis. There may, however, be rare and irreversible sacral lesions invisible intraoperatively. LEVEL OF EVIDENCE: IV; prospective case series.

Analysis of the coaptation role of the deltoid in reverse shoulder arthroplasty. A preliminary biomechanical study.

BACKGROUND: Lateralization of the glenoid implant improves functional outcomes in Reverse Shoulder Arthroplasty. Lateralization does not appear to impact the Deltoid's Moment Arm. Therefore, the stabilizing effect described in the literature would not be the result of an increase this moment arm. A static biomechanical model, derived from Magnetic Resonance Imaging, can be used to assess the coaptation effect of the Middle Deltoid. The objective of this study was to analyze the impact of increasing amounts of glenoid lateralization on the moment arm but also on its coaptation effect. METHODS: Eight patients (72.6 ± 6.5 years) operated for Reverse Shoulder Arthroplasty were included in the study. Three-dimensional models of each shoulder were created based on imaging taken at 6 months postoperative. A least square sphere representing the prosthetic implant was added to each 3D models. A static biomechanical model was then applied to different planar portions of the Middle Deltoid (from 3D models), first without lateralization and then with simulated lateralization of 6, 9 and 12mm. This static model enables to compute a Coaptation/Elevation Ratio and to measure the Deltoid's Moment Arm. The inter- and intra-rater agreement of the 3D models was evaluated. RESULTS: One patient was excluded due to motion during imaging. The inter- and intra-rater agreement was over 0.99. The ratio increased starting at 6 mm of lateralization (p<0.05), compared to the initial position. The moment arm was not affected by lateralization (p<0.05), except in two slices starting at 9 mm (S1 p<0.05 and S2 p<0.05). CONCLUSION: Our hypothesis that the Middle Deltoid's coaptation role would be greater with glenosphere lateralization was confirmed. This trend was not found in the moment arm, which showed little sensitivity to lateralization. The stabilizing effect therefore appears to stem from the coaptation role of the Middle Deltoid.

Fatty muscle infiltration of the hip lateral rotator muscles following direct anterior minimally invasive total hip arthroplasty.

INTRODUCTION: There is no consensus as to the best surgical approach to use when doing total hip arthroplasty (THA). There has been renewed interest in recent years in so-called anatomic minimally invasive direct anterior approaches (DAA). However, their reduced impact has not been confirmed with imaging data. This led us to carry out a prospective study to 1) evaluate fatty infiltration (FI) of muscles around the hip joint and 2) analyze how this FI changes over time. HYPOTHESIS: THA done by the DAA induces FI of the anterolateral muscles around the hip adjacent to the approach. MATERIAL AND METHODS: A continuous case series of THA by DAA using a traction table was done by a single experienced surgeon. MRI images (GE Optima* MR360 1.5T) were taken preoperatively, then at 3 months and 1 year after the THA surgery. Muscle FI was classified as described by Goutallier by an independent radiologist on all the muscles around the hip joint. A Wilcoxon test was used to compare the preoperative MRI data to the data at 3 months and 1 year postoperative. RESULTS: Sixty-nine MRI examinations were done in 23 patients. Two were not interpretable because the patient moved during the preoperative acquisition. No intraoperative or postoperative complications were reported. None of the patients had hip pain or limped at 1 year postoperative. The FI was significantly worse from the preoperative MRI to the 3-month postoperative MRI (p=0.02) and 1-year MRI (p=0.0007) in the internal obturator muscle and at 1 year in the piriformis muscle (p=0.04). There was no significant difference for the other muscles. The rectus femoris, superior and inferior gemellus muscles and the quadratus femoris could not be analyzed. DISCUSSION: Our hypothesis was not confirmed, although we had a paradoxical finding of muscle FI in the posterior lateral rotator muscles not the anterolateral muscles after THA by DAA. These lesions may be secondary to detachment or denervation of these muscles when elevating the femur to prepare the femoral canal or insert the stem. LEVEL OF EVIDENCE: IV; Prospective case series.

Electromyographic study of hip muscles involved in total hip arthroplasty: Surprising results using the direct anterior minimally invasive approach.

BACKGROUND: The functional and clinical benefit of minimally invasive total hip arthroplasty (THA) is well-known, but the literature reports impaired gait and posture parameters as compared to the general population, especially following use of the anterior minimally invasive approach, which has more severe impact on posture than the posterior approach. The reasons for this impairment, however, remain unexplained. We therefore conducted a surface electromyography (sEMG) study of the hip muscles liable to be affected by arthroplasty surgery: gluteus maximus (GMax), gluteus medius (GMed), tensor fasciae latae (TFL), and sartorius (S). The study addressed the following questions: (1) Is bipodal and unipodal GMed activity greater following anterior THA than in asymptomatic subjects? (2) Is a single manual test sufficient to assess maximal voluntary contraction (MVC) in hip abductors (GMax, GMed, TFL) and flexors (TFL, S)? HYPOTHESIS: Bipodal and unipodal GMed activity is greater following anterior THA than in asymptomatic subjects. METHOD: Eleven patients with anterior THA and 11 asymptomatic subjects, matched for age, gender and body-mass index, were included. Subjects underwent 3 postural tests: bipodal, eyes closed (BEC), unipodal on the operated side (UOP), and unipodal on the non-operated side (UnOP), with unipodal results averaged between both sides in the asymptomatic subjects. Data were recorded from 4-channel EMG and a force plate. EMG test activity was normalized as a ratio of MVC activity. RESULTS: Postural parameters (mean center of pressure displacement speed) were poorer and sEMG activity higher in anterior THA than asymptomatic subjects (p<0.005). On the BEC test, GMax and GMed activity was higher on both operated and non-operated sides than in asymptomatic controls (respectively, 0.15±0.12 and 0.12±0.6 versus 0.07±0.06 for GMax, and 0.13±0.08 and 0.13±0.08 versus 0.08±0.05 for GMed; p<0.05). On unipodal tests, both UOP and UnOP GMed activities were higher than in controls (respectively, 0.51±0.3 and 0.48±0.27 versus 0.28±0.13; p<0.04); GMax and TFL activities were higher than in controls only on the UOP tests (respectively, 0.49±0.43 versus 0.24±0.18, and 0.23±0.17 versus 0.12±0.16; p<0.05). DISCUSSION: sEMG activity in the hip abductors, which are the main stabilizing muscles for the pelvis, is increased following anterior THA, in parallel with impaired postural parameters. This finding may be due to intraoperative TFL and S neuromuscular spindle lesion. The present preliminary study is to be followed up by a comparison of all 3 common minimally invasive approaches (anterior, anterolateral and posterior) using the same study protocol. LEVEL OF EVIDENCE: III, prospective case-control study.