Socket Position Research Articles

Cup Overhanging in Anatomic Socket Position or High Hip Center of Rotation in Total Hip Arthroplasty for Crowe III and IV Dysplasia: A CT-Based Simulation.

Cup overhanging in total hip arthroplasty is a predisposing factor to iliopsoas impingement. In dysplastic hips, cup implantation was simulated in an anatomic hip center of rotation (AHCR) and in high hip center (HHCR). We sought to assess: (1) the percentage of prominent cups; (2) quantify the cup protrusion at different sites on frontal, axial and sagittal views. In 40 Crowe III-IV hips, using a 3D CT-based planning software, cup planning in AHCR and HHCR (CR height ≥ 20 mm) was performed for every hip. Cup prominence was assessed on every plane. HHCR cups were less anteverted (p < 0.01), less medialized (p < 0.001) and less caudal (p = 0.01) than AHCR sockets. AHCR cups were more frequently prominent on at least one plane (92.5% vs. 77.5%), with minimal agreement between the two configurations (k = 0.31, p = 0.07). AHCR cups protruded more than HHCR sockets in the sagittal (p = 0.02) and axial planes (p < 0.001). Axially, at the center of the cup, prominence 6−11 mm occurred in nine (22.5%) AHCR and one (2.5%) HHCR socket. In conclusion, while a routine high hip center should not be recommended, cup placement at a center of rotation height < 20 mm is associated with higher rates and magnitudes of anterior cup protrusion in severe dysplasia.

Effects of Dynamic Alignment on the Transtibial Prosthetic Gait in the Sagittal Plane of a Kinematic Model Using OpenSim

A sensitivity analysis of the kinematics of the transtibial amputee gait has been performed in the sagittal plane in relation to the dynamic alignment (position of the prosthesis components): flexion/extension and abduction/adduction of the socket, as well as plantar flexion/dorsiflexion and eversion/inversion of the prosthetic foot. The analysis has led to the determination of the effects on the flexion and extension in the sagittal planes of the hips, knees, and ankles of the amputated leg and the non-amputated leg. The estimation has been performed for all gait phases through a model developed in OpenSim® and Matlab®, by using the measurements of a patient with Technaid® inertial sensors and by varying the socket position in the sagittal and frontal planes between 2, 6, and 10 degrees. These measurements have been processed in Matlab® in order to deliver a motion vector. A script has been developed in order to generate the modified structural model of OpenSim® based on the static position of the vector in each case. Once the model has been obtained, the inverse kinematics of the hip, knee, and ankle have been calculated. By considering that it is not possible to perform variations on the prosthetic foot without compromising the stability of the user while taking measurements, a model variant in which a neural network is trained to estimate the kinematics of the hip, knee, and ankle has been developed. Regarding the prosthetic foot, the changes derived from modifications in dorsiflexion, plantar flexion, eversion, and inversion positions significantly alter the kinematics of the hip and knee.

InsertionNet - A Scalable Solution for Insertion

Complicated assembly processes can be described as a sequence of two main activities: grasping and insertion. While general grasping solutions are common in industry, insertion is still only applicable to small subsets of problems, mainly ones involving simple shapes in fixed locations and in which the variations are not taken into consideration. Recently, RL approaches with prior knowledge (e.g., LfD or residual policy) have been adopted. However, these approaches might be problematic in contact-rich tasks since interaction might endanger the robot and its equipment. In this letter, we tackled this challenge by formulating the problem as a regression problem. By combining visual and force inputs, we demonstrate that our method can scale to 16 different insertion tasks in less than 10 minutes. The resulting policies are robust to changes in the socket position, orientation or peg color, as well as to small differences in peg shape. Finally, we demonstrate an end-to-end solution for 2 complex assembly tasks with multi-insertion objectives when the assembly board is randomly placed on a table.

Total Hip Arthroplasty After Periacetabular and Intertrochanteric Valgus Osteotomy

BackgroundWe performed periacetabular osteotomy (PAO) combined with intertrochanteric valgus osteotomy (TVO) to obtain better congruity for patients with acetabular dysplasia and nonspherical femoral head. These patients with PAO-combined TVO demonstrate long-term progression of osteoarthritis, thereby, needing conversion to total hip arthroplasty (THA) and is difficult due to morphological changes. The objective of the present study was to investigate outcomes of patients who underwent THA after PAO-combined TVO. MethodsWe performed 3 groups' case-control study. The participants were 20 patients (20 hips) who underwent THA after PAO-combined TVO (PAO-TVO group); these patients had a mean age at surgery of 56.3 years and underwent postoperative follow-up for a mean period of 6.8 years. For the control group, we included 53 patients (57 joints) who underwent THA after PAO and 76 patients (80 joints) who underwent primary THA for hip dysplasia matching age, sex, and time of surgery. ResultsHarris hip score at the last follow-up was significantly poorer in PAO-TVO group compare with PAO group and primary group. Short Form-36 of Physical Component Summary was significantly poorer in PAO-TVO group compared with primary group. The socket position in the PAO-TVO group was significantly superior and lateral compared with that in the primary THA group. Considering socket placement in Lewinnek's safe zone and stem malalignment, there were no significant differences in the 3 groups. ConclusionHarris hip score and Short Form-36–Physical Component Summary for THA after PAO-combined TVO were significantly poorer compared to those of primary THA.

初回人工股関節置換術（THA）時の患者体位のソケット設置に及ぼす影響: 続報

初回人工股関節置換術（THA）時の患者体位のソケット設置に及ぼす影響: 続報

The Synergistic Effect of Leukocyte Platelet-Rich Fibrin and Micrometer/Nanometer Surface Texturing on Bone Healing around Immediately Placed Implants: An Experimental Study in Dogs.

Aims. This study evaluated the effects of L-PRF presence and implant surface texture on bone healing around immediately placed implants. Methods. The first mandibular molars of 8 beagle dogs were bilaterally extracted, and implants (Blossom™, Intra-Lock International, Boca Raton, FL) were placed in the mesial or distal extraction sockets in an interpolated fashion per animal. Two implant surfaces were distributed per sockets: (1) dual acid-etched (DAE, micrometer scale textured) and (2) micrometer/nanometer scale textured (Ossean™ surface). L-PRF (Intraspin system, Intra-Lock International) was placed in a split-mouth design to fill the macrogap between implant and socket walls on one side of the mandible. The contralateral side received implants without L-PRF. A mixed-model ANOVA (at α = 0.05) evaluated the effect of implant surface, presence of L-PRF, and socket position (mesial or distal), individually or in combination on bone area fraction occupancy (BAFO). Results. BAFO values were significantly higher for the Ossean relative to the DAE surface on the larger mesial socket. The presence of L-PRF resulted in higher BAFO. The Ossean surface and L-PRF presence resulted in significantly higher BAFO. Conclusion. L-PRF and the micro-/nanometer scale textured surface resulted in increased bone formation around immediately placed implants.

Direct anterior approach to THR: what it is and what it is not.

Direct anterior approach to THR: what it is and what it is not.

Anatomic ACL reconstruction produces greater graft length change during knee range-of-motion than transtibial technique

Because distance between the knee ACL femoral and tibial footprint centrums changes during knee range-of-motion, surgeons must understand the effect of ACL socket position on graft length, in order to avoid graft rupture which may occur when tensioning and fixation is performed at the incorrect knee flexion angle. The purpose of this study is to evaluate change in intra-articular length of a reconstructed ACL during knee range-of-motion comparing anatomic versus transtibial techniques. After power analysis, seven matched pair cadaveric knees were tested. The ACL was debrided, and femoral and tibial footprint centrums for anatomic versus transtibial techniques were identified and marked. Asuture anchor was placed at the femoral centrum and a custom, cannulated suture-centring device at the tibial centrum, and excursion of the suture, representing length change of an ACL graft during knee range-of-motion, was measured in millimeters and recorded using a digital transducer. Mean increase in length as the knee was ranged 120°–0° (full extension) was 4.5 mm (±2.0 mm) for transtibial versus 6.7 mm (±0.9 mm) for anatomic ACL technique. A significant difference in length change occurs during knee range-of-motion both within groups and between the two groups. Change in length of the ACL intra-articular distance during knee range-of-motion is greater for anatomic socket position compared to transtibial position. Surgeons performing anatomic single-bundle ACL reconstruction may tension and fix grafts with the knee in full extension to minimize risk of graft stretch or rupture or knee capture during full extension. This technique may also result in knee anterior–posterior laxity in knee flexion.

How Far above the True Anatomic Position can the Acetabular Cup be Placed in Total Hip Arthroplasty?

There is controversy about which is more suitable for determining correct socket position in patients with severe bone deficiency of the acetabular roof because of developmental dysplasia of the hip (DDH): the anatomic centre of hip rotation or a high centre. We evaluated the relationship, in 200 hips, between the centre of rotation and presence of the Trendelenburg sign to determine the upper limit of cup position from the standpoint of hip-abductor strength. Of the 200 hips, 20 (10%) showed a positive Trendelenburg sign. There were no statistically significant differences between parameters (the centre of rotation, femoral offset, abductor lever arm) regarding the presence of the Trendelenburg sign except for age at surgery. Patients with a positive Trendelenburg sign were significantly older (64.1 ± 9.4 years) than those with a negative Trendelenburg sign (58.8 ± 7.7 years) (P = 0.01). Our findings indicate that a high centre of hip rotation of up to approximately 30 mm from the inter-teardrop line is a feasible option for patients with DDH from the standpoint of hip-abductor strength if stems are used that allow the restoration of femoral offset and the abductor lever arm.

Transfemoral sockets with vacuum-assisted suspension comparison of hip kinematics, socket position, contact pressure, and preference: Ischial containment versus brimless

The objective of this study was to investigate the effect of brimless compared with ischial ramus containment (IRC) prosthetic sockets when using vacuum-assisted suspension (VAS) on persons with a unilateral transfemoral amputation (TFA). A randomized crossover design with a 2 d accommodation was used. People with unilateral TFA (n = 9 analyzed) were enrolled. Interventions were IRC VAS and brimless VAS sockets. Main outcome measures included coronal hip angle and vertical and lateral socket movement as measured by X-ray, skin pressure measured by Tekscan, and preference measured subjectively. The brimless design was statistically equivalent to IRC in all measured coronal hip angles and vertical and lateral socket displacement. The peak/stance mean pressure in the medial proximal aspect of the socket was 322 mmHg in the IRC compared with 190 mmHg in the brimless condition. Except for medial proximal pressure, no other measures reached statistical significance. All subjects reported the brimless design to be more comfortable than the IRC in short-term preference. Brimless VAS socket design may be a clinically viable choice for people with TFA.

Socket position determines hip resurfacing 10-year survivorship.

Modern metal-on-metal hip resurfacing arthroplasty designs have been used for over a decade. Risk factors for short-term failure include small component size, large femoral head defects, low body mass index, older age, high level of sporting activity, and component design, and it is established there is a surgeon learning curve. Owing to failures with early surgical techniques, we developed a second-generation technique to address those failures. However, it is unclear whether the techniques affected the long-term risk factors. We (1) determined survivorship for hips implanted with the second-generation cementing technique; (2) identified the risk factors for failure in these patients; and (3) determined the effect of the dominant risk factors on the observed modes of failure. We retrospectively reviewed the first 200 hips (178 patients) implanted using our second-generation surgical technique, which consisted of improvements in cleaning and drying the femoral head before and during cement application. There were 129 men and 49 women. Component orientation and contact patch to rim distance were measured. We recorded the following modes of failure: femoral neck fracture, femoral component loosening, acetabular component loosening, wear, dislocation, and sepsis. The minimum followup was 25 months (mean, 106.5 months; range, 25-138 months). Twelve hips were revised. Kaplan-Meier survivorship was 98.0% at 5 years and 94.3% at 10 years. The only variable associated with revision was acetabular component position. Contact patch to rim distance was lower in hips that dislocated, were revised for wear, or were revised for acetabular loosening. The dominant modes of failure were related to component wear or acetabular component loosening. Acetabular component orientation, a factor within the surgeon's control, determines the long-term success of our current hip resurfacing techniques. Current techniques have changed the modes of failure from aseptic femoral failure to wear or loosening of the acetabular component. Level III, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

Anteromedial versus central single-bundle graft position: which anatomic graft position to choose?

To compare the time-zero stability of an anatomic anteromedial (AM) single-bundle ACL reconstruction to an anatomic central (CTR) single-bundle ACL reconstruction. Twelve (6 paired) hip to knee cadaveric specimens were studied. Using custom ACL computer navigation software, a Lachman test and a previously validated, navigated mechanized pivot shift test were performed on 4 separate experimental groups in each specimen: (1) intact ACL, (2) ACL deficient with total medial and lateral meniscectomy, (3) following anatomic AM single-bundle ACL reconstruction, and (4) after anatomic CTR single-bundle ACL reconstruction. Maximum anterior tibial translation in each group was measured. Lachman: No significant difference was observed between the AM and CTR reconstructions (n.s.) or between reconstruction and the intact ACL (3.4±1.7mm) (n.s.). Pivot Shift: Both the AM and CTR ACL reconstructions significantly reduced anterior translation relative to the ACL/menisci-deficient condition (lateral compartment: 8.9±3.8 mm and 6.75±4.6 mm vs. 17.25±3.5mm, respectively; P<0.001 and medial compartment: -3.0±5.3 mm vs. -3.7±5.7 mm vs. 6.2±6.7mm, P<0.05). There was also a significant difference between the AM (P<0.001) and CTR (P<0.05) ACL reconstructions and the intact ACL (2.8±4.4mm) for lateral compartment translation. Further, no difference was found between lateral or medial compartment translations in the AM versus CTR reconstructions (n.s.). It has been shown that there was no difference in the time-zero biomechanical stability between an anatomic anteromedial and anatomic central single-bundle ACL reconstruction. Given the current debate on the best anatomic ACL reconstruction technique, anatomic socket position in either the anteromedial or central locations provides similar time-zero biomechanics.

A Radiological Study of the True Anatomical Position of the Acetabulum in Japanese Women

There is sometimes uncertainty concerning the correct socket position prior to total hip arthroplasty (THA). We conducted a study to determine the hip centre in Japanese women in order to define the true anatomical position of the acetabulum. The study involved 200 consecutive female patients in whom the contralateral hip joint was normal or was prearthritic and who underwent unilateral THA. The 'normal' group comprised 100 hip joints with no acetabular hip dysplasia, and the prearthritis group comprised 100 hip joints with Crowe type I dysplasia. The length of a perpendicular line drawn under the teardrop (interteardrop line) connecting both inferior edges of the teardrop with the centre of the femoral head was recorded as the vertical distance, and the distance from the intersection of the perpendicular line and interteardrop line up to the teardrop was recorded as the horizontal distance. We measured these distances on the femoral head of the side that did not undergo THA. The mean vertical distances in the 'normal' and prearthritis groups were 14.6 ± 2.8 mm and 16.8 ± 2.7 mm, respectively, and the mean horizontal distances were 30.2 ± 2.8 mm and 32.5 ± 2.7 mm, respectively. We therefore determined the mean centre of the hips to lie at a vertical distance of 11 to 22 mm and a horizontal distance of 27 to 38 mm. These values can serve as a useful index for socket positioning in THA.

Effect of Femoral Socket Position on Graft Impingement After Anterior Cruciate Ligament Reconstruction

Background: Despite improved biomechanical stability and kinematics with anatomic anterior cruciate ligament (ACL) reconstruction, concerns regarding notch impingement of the graft have persisted, particularly with increasingly anterior tibial tunnel position. The potentially mitigating effect of anatomic femoral socket position, however, has not been evaluated. Hypothesis: Placement of the femoral socket in the central or posterolateral bundle footprint reduces the risk and magnitude of graft impingement after ACL reconstruction compared with placement in the anteromedial bundle footprint. Study Design: Controlled laboratory study. Methods: This study employed computer-assisted navigation in a cadaveric model to evaluate the effect of tibial and femoral tunnel position on ACL graft impingement. Sixteen cadaveric knees were tested using the Praxim ACL Surgetics Navigation System, with the tibial tunnel positioned in the footprint of the anteromedial bundle and the femoral socket placed in the (1) anteromedial bundle footprint, (2) center of footprint, or (3) posterolateral bundle footprint. The amount of maximum impingement, angle of initial impingement, and location of graft impingement were documented through a full arc of knee motion. Results: Impingement occurred with all 3 femoral socket positions, but the mean angle of impingement with the anteromedial femoral position (42.8° ± 26.4°) was significantly greater (P < .003) than the mean angles of impingement with the central femoral position (19.4° ± 19.2°) and the posterolateral bundle femoral position (16.7° ± 13.3°). Conclusion: Although notch impingement was seen in all femoral socket locations with an anteromedial tibial socket position, femoral socket position in a central or posterolateral bundle location may reduce the risk and magnitude of graft impingement after ACL reconstruction. Additional studies are necessary to determine the influence of these different constructs on graft isometry and knee kinematics. Clinical Relevance: Anatomic femoral socket position in the center of the native ACL footprint may reduce the risk and magnitude of notch impingement compared with an anteromedial bundle position with ACL reconstruction.

Influence of patient position on socket position in total hip arthroplasty

Influence of patient position on socket position in total hip arthroplasty

Influence of patient position on socket position in total hip arthroplasty

Influence of patient position on socket position in total hip arthroplasty

Influence de l’indice de masse corporelle sur la réalisation d’une prothèse totale de hanche par voie d’abord antérieure réduite

Purpose of the study The purpose of this prospective study was to evaluate the influence of the BMI on the feasibility of minimally invasive total hip arthroplasty (THA). Material and methods This prospective study included 86 patients (88 THA) operated on via a single minimally invasive incision (7 cm) using an anterior approach on Judet's orthopedic table. Mean age was 63.7 years and mean BMI was 58.8. Forty-one patients were classified in group I (BMI < 25) and 46 in group II (BMI < 25). Perioperative data, pain, postoperative blood loss, duration of the procedure, and length of the incision were noted. All patients were reviewed at three months and radiographic analysis was performed to asses the position of the socket and the quality of the cementation. Results BMI did not appear to be a strict contraindication for a minimally invasive procedure. Nevertheless, bleeding and operative duration were statistically correlated with BMI (ɛ = 4.28 and ɛ = 2.66). Extension of the wound noted at the end of the procedure in patients with BMI ≥ 25 (t = 5.01) may have resulted from greater pressure on the skin and soft tissue due to stronger traction and more abrasion of the skin edges by reamers and rasps. Such damage may lead to more wound complications even though in our experience there was no statistical difference. On the other hand, socket position and cementation did not appear to be correlated with BMI. Discussion Results concerning duration of procedure, bleeding, hospital stay and rate of complications are contradictory in the literature. At the same time, criteria for patient selection remain unclear. It thus appeared to be of interest to determine whether BMI was a good criterion to determine the feasibility of THA via a minimally invasive procedure. Conclusion BMI appears to be a good criterion to evaluate the risk of wound complications after minimally invasive surgery. On the other hand, other criteria must be found since BMI does not evaluate muscle mass which seems to be of major concern in minimally invasive procedures.

Graft Length Changes in the Bi-Socket Anterior Cruciate Ligament Reconstruction: Comparison Between Isometric and Anatomic Femoral Tunnel Placement

To compare the length change of grafts in bi-socket anterior cruciate ligament (ACL) reconstruction between isometric and anatomic placement. Case series. The subjects were 110 knees of 110 patients with a mean age of 27 years. All knees were reconstructed using multistranded autogenous semitendinosus tendon and the bi-socket procedure. Of those, 43 knees were reconstructed in the isometric position, around the isometric point (group I) and the remaining 67 in the anatomic position, mimicking the anatomic footprint of ACL (group II). Grouping was performed based on the femoral socket position. Each femoral socket for the anterior medial graft (AMG) and the posterolateral graft (PLG) for the left knee was positioned at 1 o'clock and 2 o'clock to 2:30 in group I, or 2 o'clock and 3 o'clock in group II in the posterior border of the notch. Their positioning for the right knee was at 11 o'clock and 9:30 to 10 o'clock in group I, or 10 o'clock and 9 o'clock in group II. The length changes of grafts were intraoperatively measured while extending the knee from 120 degrees to full extension, using a commercially available isometric positioner. The Student t test was used for statistical analysis. All the grafts showed the pattern of elongation approaching extension. The length change of AMG and PLG was 1.3+/-0.6 mm and 2.2+/-1.0 mm in the group I, 1.4+/-0.7 mm and 2.5+/-0.9 mm in the group II, respectively. There was no statistically significant difference in the values of AMG (P = .51) and PLG (P = .074) between the 2 groups. The length change of ACL grafts placed in the anatomic position was not significantly different from that positioned in the isometric position. Level IV, case series.

Relationship between socket position and migration speed of loosened sockets in cemented THA

Relationship between socket position and migration speed of loosened sockets in cemented THA

両側変股症に対する人工股関節置換術

We analyzed 29 THRs of 22 patients with bilateral dysplastic osteoarthritic hips. The patients rarged in age from 37 to 62 years (mean: 59 years), and were evaluated on average 5.8 years after the replacement.Clinical evaluations were performed using the JOA score, ROM, MMT for abduction and leg length inequality. X-ray results evaluted the socket position, height of the major and minor trochanter and prosthetic loosening.On the operated side, the lower the socket position, the better the functional results as assessed by ROM and MMT. Results led us to conclude that the upperlimit of socket height (measured from the cup center) may be 30mm from the teardrop-line in order to achieve functional and long-lashng THR. A lower socket position leading to leg lengthening on the operafed side might also lead to better clinical results through a varus effect on the unoperated femoral head.