Acetabular revision surgery is challenging due to severe bone defects. Burch-Schneider anti-protrusion cages (BS cage: Zimmer-Biomet) is one of the options for acetabular revision, however higher dislocation rate was reported. A computed tomography (CT)-based navigation system indicates us the planned direction for implantation of a cemented acetabular cup during surgery. A large diameter femoral head is also expected to reduce the dislocation rate. The purpose of this study is to investigate short-term results of BS cage in acetabular revision surgery combined with the CT-based navigation system and the use of large diameter femoral head. Sixteen hips of fifteen patients who underwent revision THA using allografts and BS cage between September 2013 and December 2017 were included in this study with the follow-up of 2.7 (0.1–5.0) years. There were 12 women and three men with a mean age of 78.6 years (range, 59–61 years). The cause of acetabular revision was aseptic loosening in all hips. The failed acetabular cup was carefully removed, and acetabular bone defect was graded using the Paprosky classification. Structural allografts were morselized and packed for all medial or contained defects. In some cases, solid allograft was implanted for segmental defects. BS cage was molded to optimize stability and congruity to the acetabulum and fixed with 6.5 mm titanium screws to the iliac bone. The inferior flange was slotted into the ischium. The upside-down trial cup was attached to a straight handle cup positioner with instrumental tracker (Figure 1) and placed on the rim of the BS cage to confirm the direction of the target angle for cement cup implantation under the CT-based navigation system (Stryker). After removing the cement spacer around the X3 RimFit cup (Stryker) onto the BS cage for available maximum large femoral head, the cement cup was implanted with confirming the direction of targeting angle. Japanese Orthopedic Association score (JOA score) of the hip was used for clinical assessment. Implant position, loosening, and consolidation of allograft were assessed using anterior and lateral radiographies of the pelvis.Introduction
Methods
Robotic-assisted hip arthroplasty helps acetabular preparation and implantation with the assistance of a robotic arm. A computed tomography (CT)-based navigation system is also helpful for acetabular preparation and implantation, however, there is no report to compare these methods. The purpose of this study is to compare the acetabular cup position between the assistance of the robotic arm and the CT-based navigation system in total hip arthroplasty for patients with osteoarthritis secondary to developmental dysplasia of the hip. We studied 31 hips of 28 patients who underwent the robotic-assisted hip arthroplasty (MAKO group) between August 2018 and March 2019 and 119 hips of 112 patients who received THA under CT-based navigation (CT-navi group) between September 2015 and November 2018. The preoperative diagnosis of all patients was osteoarthritis secondary to developmental dysplasia of the hip. They received the same cementless cup (Trident, Stryker). Robotic-assisted hip arthroplasty were performed by four surgeons while THA under CT-based navigation were performed by single senior surgeon. Target angle was 40 degree of radiological cup inclination (RI) and 15 degree of radiological cup anteversion (RA) in all patients. Propensity score matching was used to match the patients by gender, age, weight, height, BMI, and surgical approach in the two groups and 30 patients in each group were included in this study. Postoperative cup position was assessed using postoperative anterior-posterior pelvic radiograph by the Lewinnek's methods. The differences between target and postoperative cup position were investigated.Introduction
Methods
Most of patients with unilateral hip disease shows muscle volume atrophy of pelvis and thigh in the affected side because of pain and disuse, resulting in reduced muscle weakness and limping. However, it is unclear how the muscle atrophy correlated with muscle strength in the patient with hip disorders. A previous study have demonstrated that the volume of the gluteus medius correlated with the muscle strength by volumetric measurement using 3 dimensional computed tomography (3D-CT) data, however, muscles influence each other during motions and there is no reports focusing on the relationship between some major muscles of pelvis and thigh including gluteus maximus, gluteus medius, iliopsoas and quadriceps and muscle strength in several hip and knee motions. Therefore, the purpose of the present study is to evaluate the relationship between muscle volumetric atrophy of major muscles of pelvis and thigh and muscle strength in flexion, extension and abduction of hip joints and extension of knee joint before surgery in patients with unilateral hip disease. The subjects were 38 patients with unilateral hip osteoarthritis, who underwent hip joint surgery. They all underwent preoperative computed tomography (CT) for preoperative planning. There were 6 males and 32 females with average age 59.5 years old. Before surgery, isometric muscle strength in hip flexion, hip extension, hip abduction and knee extension were measured using a hand held dynamometer (µTas F-1, ANIMA Japan). Major muscles including gluteus maximus, gluteus medius, iliopsoas and quadriceps were automatically extracted from the preoperative CT using convolutional neural networks (CNN) and were corrected manually by the experienced surgeon. The muscle volumetric atrophy ratio was defined as the ratio of muscle volume of the affected side to that of the unaffected side. The muscle weakness ratio was defined as the ratio of muscle strength of the affected side to that of the unaffected side. The correlation coefficient between the muscle atrophy ratio and the muscle weakness ratio of each muscle were calculated.Introduction
Material and Methods
For patients with Developmental Dysplasia of the Hip (DDH) who progress to needing total joint arthroplasty it is important to understand the morphology of the femur when planning for and undertaking the surgery, as the surgery is often technically more challenging in patients with DDH on both the femoral and acetabular parts of the procedure1. The largest number of male DDH patients with degenerative joint disease previously assessed in a morphological study was 122. In this computed tomography (CT) based morphological study we aimed to assess whether there were any differences in femoral morphology between male and female patients with developmental dysplasia undergoing total hip arthroplasty (THA) in a cohort of 49 male patients, matched to 49 female patients. This was a retrospective study of the pre-operative CT scans of all male patients with DDH who underwent THA at two hospitals in Japan between 2006–2017. Propensity score matching was used to match these patients with female patients in our database who had undergone THA during the same period, resulting in 49 male and 49 female patients being matched on age and Crowe classification. The femoral length, anteversion, neck-shaft angle, offset, canal-calcar ratio, canal flare index, lateral centre-edge angle, alpha angle and pelvic incidence were measured for each patient on their pre-operative CT scans.Objectives
Methods
The purpose of this experimental study was to elucidate the accuracy of neck-cut PSG setting, and femoral component implantation using neck-cut PSG in the THA through the anterolateral-approach relative to the preoperative planning goals, and to determine the usefulness of PSG compared with the procedure without PSG. A total of 32 hips from 16 fresh Caucasian cadaveric samples were used and classified into 4 groups: cementless anatomical stem implantation with wide-base-contact PSG (AWP: 8 hips, Fig.2); (2) cementless anatomical stem implantation with narrow-base-contact PSG (ANP: 8 hips, Fig.2); (3) cementless anatomical stem implantation without PSG (Control: 8 hips); and (4) cementless taper-wedge stem implantation with wide-base-contact PSG (TWP: 8 hips). The absolute error of PSG setting in the sagittal plane of the AWP group was significantly less than that of the ANP (p=0.003).THA with wide-base- contact PSG resulted in better alignment of the femoral component than THA without PSG or with narrow- base-contact PSG. Although the neck-cut PSG did not control the sagittal alignment of taper-wedge stem, the neck-cut PSG was effective to realise the preoperative coronal alignment and medial height for THA via the anterolateral approach regardless of the femoral component type. For figures and tables, please contact authors directly.
The purposes of this study were to review retrospectively the 25-year survival of cemented and cementless THA for hip dysplasia and to compare the effect of fixation methods on the long-term survival in patients with DDH. We retrospectively reviewed all patients with OA secondary to hip dysplasia treated with a cemented Bioceram hip system between 1981 and 1987, and a cementless cancellous metal Lübeck hip system between 1987 and 1991. The studied subjects were 76 hips of cemented THA (Group-C) and 57 hips of cementless THA (Group-UC). Both hip implants had a 28-mm alumina head on polyethylene articulation. The mean age at operation was 50.5 years (range, 36–60 years) in Group-C and 50.0 years (range, 29–60 years) in Group-UC. The survival at 25 years regarding any revision as the endpoint was 46% in Group-C and 76% in Group-UC. These difference was significant using Log-rank test (P=0.008). The cup survival at 25 years was 47% in Group-C and 83% in Group-UC (P= 0.0003). The stem survivals at 25 years were 95% in Group-C and 92% in Group-UC. (P= 0.416). Cementless THA in patients with DDH showed a higher survival rate at 25 years than cemented THA because of the excellent survival of the acetabular component without cement. We conclude that cementless THA with the cancellous metal Lübeck hip system led to better longevity at 25 years than cemented THA with the Bioceram in patients with OA secondary to DDH.
Patients with hip osteoarthritis have a substantial loss of muscular strength in the affected limb compared to the healthy limb preoperatively, but there is very little quantitative information available on preoperative muscle atrophy and degeneration and their influence on postoperative quality of life (QOL) and the risk of falls. The purpose of the present study were two folds; to assess muscle atrophy and degeneration of pelvis and thigh of patients with unilateral hip osteoarthritis using computed tomography (CT) and to evaluate their impacts on postoperative QOL and the risk of falls. We used preoperative CT data of 20 patients who underwent primary total hip arthroplasty. The following 17 muscles were segmented with our developed semi-automated segmentation method: iliacus, gluteus maximus, gluteus medius, gluteus minimus, rectus femoris, tensor facia lata, adductors, pectinus, piriformis, obturator externus, obturator internus, semimenbranosus, semitendinosus, vastus medialis and vastus lateralis/intermedius (Fig. 1). Volume and radiological density of each muscle were measured. The ratio of those of affected limb to healthy limb was calculated. At the latest follow-up, the WOMAC score was collected and a history of falls after surgery was asked. The average follow- up period was 6 years. Comparison of the volume and radiological density of each muscle between affected and healthy limbs was performed using the Wilcoxon signed rank test. Correlations between the volume and radiological density of each muscle and each score of the WOMAC were evaluated with Spearman's correlation coefficient. The volume and radiological density of each muscle between patients with and without a history of falls were compared using Mann-Whitney U test.Introduction
Methods
Cup anteversion and inclination are important to avoid implant impingement and dislocation in total hip arthroplasty (THA). However, it is well known that functional cup anteversion and cup inclination also change as the pelvic sagittal inclination (PSI) changes, and many reports have been made to investigate the PSI in supine and standing positions. However, the maximum numbers of subjects studied are around 150 due to the requirement of considerable manual input in measuring the PSIs. Therefore, PSI in supine and standing positions were measured fully automatically with a computational method in a large cohort, and the factors which relate to the PSI change from supine to standing were analyzed in this study. A total of 422 patients who underwent THA from 2011 to 2015 were the subjects of this study. There were 83 patients with primary OA, 274 patients with DDH derived secondary OA (DDH-OA), 48 patients with osteonecrosis, and 17 patients with rapidly destructive coxopathy (RDC). The median age of the patient was 61 (range; 15–87). Preoperative PSI in supine and standing positions were measured and the number of cases in which PSI changed more than 10° posteriorly were calculated. PSI in supine was measured as the angle between the anterior pelvic plane (APP) and the horizontal line of the body on the sagittal plane of APP, and PSI in standing was measured as the angle between the APP and the line perpendicular to the horizontal surface on the sagittal plane of APP (Fig. 1). The value was set positive if the pelvis was tilted anteriorly and was set negative if the pelvis tilted posteriorly. Type of hip disease, sex, and age were analyzed with multiple logistic regression analysis if they were related to PSI change of more than 10°. For accuracy verification, PSI in supine and standing were measured manually with the previous manual method in 100 cases and were compared with the automated system used in this study.Background
Methods
Although many distal fit and fill design cementless stems have shown a very good long term stable fixation, short proximal coated stems are recently increasing in their use with an expectation of less stress shielding and an ease of removal at revision surgery. We introduced an anatomic short stem made from titanium alloy with proximal plasma-spray titanium and hydroxyapatite coating (CentPillar, Stryker, Mahwah) in 2002. To evaluate a minimum 10-year outcome of the system in terms of fixation and stress shielding, we reviewed initial 100 consecutive cases operated by a single surgeon. There were 91 hips with osteoarthritis and 9 hips with osteonecrosis. There were 94 females and 6 males. Average age at operation was 58 years. The patients were followed up for an average of 11 years. Average JOA hip score improved significantly from 46.9 preoperatively to 96.7 at the final examination. There were no dislocation, or revision, or radiographic loosening. When we looked at the level of bone atrophy, 80% of cases showed no stress shielding below the lessor trochanter. We conclude that the CentPillar stem showed mild stress shielding due to short proximal bone ongrowth coating while keeping a long term good clinical score and radiographic stability.
The purpose of this study is to elucidate longitudinal kinematic changes of the hip joint during heels-down squatting after THA. 66 patients with 76 primary cementless THAs using a CT-based navigation system were investigated using fluoroscopy. An acetabular component and an anatomical femoral component were used through the mini-posterior approach with repair of the short rotators. The femoral head size was 28mm (9 hips), 32mm (12 hips), 36mm (42 hips), and 40mm (12 hips). Longitudinal evaluation was performed at 3 months, 1 year, and 2≤ years postoperatively. Successive hip motion during heels-down squatting was recorded as serial digital radiographic images in a DICOM format using a flat panel detector. The coordinate system of the acetabular and femoral components based on the neutral standing position was defined. The images of the hip joint were matched to 3D-CAD models of the components using a2D/3D registration technique. In this system, the root mean square errors of rotation was less than 1.3°, and that of translation was less than 2.3 mm. We estimated changes in the relative angle of the femoral component to the acetabular component, which represented the hip ROM, and investigated the incidence of bony and/or prosthetic impingement during squatting (Fig.1). We also estimated changes in the pelvic posterior tilting angle (PA) using the acetabular component position change. In addition, when both components were positioned most closely during squatting, we estimated the minimum angle (MA) up to theoretical prosthetic impingement as the safety margin (Fig.2).INTRODUCTION
METHODS
Range of motion (ROM) simulation of the hip is useful to understand the maximum impingement free ROM in total hip arthroplasty (THA). In spite of a complex multi-directional movement of the hip in daily life, most of the previous reports have evaluated the ROM only in specific directions such as flexion-extension, abduction-adduction, and internal - external rotation at 0° or 90° of hip flexion. Therefore, we developed ROM simulation software (THA analyzer) to measure impingement free ROM in any positions of the hip. Recent designs of the hip implants give a wider ROM by increasing the head diameter and then, bone to bone impingement can be a ROM limit factor particularly in a combination of deep flexion, adduction and internal rotation of the hip. Therefore, the purpose of this study were to observe an individual variation in the pattern of the bone impingement ROM in normal hip bone models using this software, to classify the bone impingement ROM mapping types and to clarify the factors affecting the bone impingement type. The subjects were 15 normal hips of 15 patients. Three dimensional surface models of the pelvis and femur were reconstructed from Computer tomography (CT) images. We performed virtual hip implantation with the same center of rotation, femoral offset, and leg length as the original hips. Subsequently, we created the ROM mapping until bone impingement using THA analyzer. We measured the following factors influenced on the bone impingement map patterns; the neck shaft angle, the femoral offset, femoral anteversion, pelvic tilt, acetabular anteversion, sharp angle, and CE angle. These factors were compared between the two groups. Statistical analysis was performed with Mann-Whitney U test, and statistical significance was set at P<0.05.Introduction
Methods
In total hip arthroplasty (THA), it is important to define the coordinate system of the pelvis and femur for standardization in measuring the implant alignment. A coronal plane of the pelvis (functional pelvic coordinates) in supine position has been recommended as the pelvic coordinates for cup orientation and an anatomical plane of the femur (posterior condylar plane: PCP) is widely used as the femoral coordinates to measure stem or femoral anteversion. It has been reported that the pelvic sagittal tilt in supine does not change a lot after THA. However, changes in the axial rotation of the posterior condylar plane after THA have not been well studied. If the horizontal tilt of PCP of the femur in a resting position changes a lot after THA, the combined anteversion theory cannot be functional. Therefore, we evaluated the angulation changes of the posterior condylar plane after THA and analyzed the related factors by using CT images. Forty patients (5 men and 35 women, mean age 58 years) with hip osteoarthritis who had undergone THA were the subjects of this study. CT images used for measurements were taken preoperatively (preop-CT) and 3 weeks after THA (postop-CT), and more than 2 years after THA (2nd postop-CT). Measurements were done on the reconstructed CT images using 3D viewer software. The axial rotation of the femur was measured as the angle between the posterior condylar line (PCL) and a line through the bilateral anterior superior iliac spines. To analyze the factors relating to the rotational change of the femur, change in femoral anteversion, leg length, and leg medialization after THA were also measured. Surgical approach (posterolateral: 32 cases, direct anterior: 8 cases) was also evaluated as a factor relating to the rotational change.Introduction
Methods
Metal on metal hip resurfacing (MoM HR) is attractive for young active patients. Patients with osteonecrosis of the femoral head (ONFH) are relatively young. HR can be an option of treatment, however, long-term stability of the femoral component is a concern because of the necrotic lesion in the femoral head. There is also a concern of ARMD for MoM implants. The purpose of this study is review a 10 year outcome of a consecutive patients with ONFH who underwent MoM HR. The subjects of this study were 30 hips of 26 patients with ONFH who underwent HR between 1998 and 2004. There were 21 hips of 18 males and 9 hips of 8 females. The average age at operation was 40 years (range, 20–63 years). 19 ONFHs were induced by steroid and 11 ONFHs were alcohol related. According to the Japanese Investigation Committee classification, there were 8 hips with Type C1 and 22 hips with Type C2. There were 16 hips in stage 3A, 7 hips in Stage 3B, and 7 hips in Stage 4. Operation was performed through a posterior approach. A fragile necrotic bone was curettage thoroughly and the defect was filled with cement.Introduction
Methods
The incidence of dislocation after total hip arthroplasty (THA) was reported to be 0.5 to 10% in primary THA and 10 to 25 % in revision THA. The main causes of instability after THA were reported to be implant malalignment and inappropriate soft tissue tension. However, there was no study about quantitative data of soft tissue tension of unstable THA. The purpose of this study is to clarify the features of soft tissue tension of unstable THA in comparison to stable THA. The subjects were 15 patients with 15 THAs who had developed recurrent dislocation after primary THA. Thirty four patients with 37 THAs who developed no dislocation for one year after surgery were recruited as a stable THA group. In both group, all THAs were performed through posterolateral approach. In order to assess the soft tissue tension of THA, we recorded antero-posterior radiographs of the hips while applying distal traction to the leg with traction forces of 20?, 30%, 40% of body weight (BW). The distance of separation of the head and the cup after traction was measured under correction of magnification. Nine of 15 THAs in the unstable THA group and 32 of 37 THAs in the stable THA group were unilateral involvement. In the hips with unilateral involvement, the femoral offset difference between the healthy hip and the reconstructed hip were evaluated. Statistical analysis was performed with χ2 testand Mann-Whitney U test, and statistical significance was set at P<0.05.Introduction
Methods
Rotational acetabular osteotomy (RAO) for developmental dysplasia of the hip (DDH) may not restore normal hip range of motion (ROM) due to the inherent deformity of the hip and it may lead to femoro-acetabular impingement. The purpose of this study was to investigate morphological factors of the pelvis and femur influencing on simulated ROM after RAO with a fixed target for femoral head coverage. We retrospectively reviewed CT images of 52 DDHs with an average lateral centre edge angle (CEA) of 7.9° (−12° to 19°). After virtual RAO with 30° of lateral CEA and 55° of anterior CEA producing femoral head coverage similar to that of the normal hips, we measured simulated flexion ROM using pelvic and femoral computer models reconstructed from the CT images. Pelvic sagittal inclination, acetabular anteversion, lateral CEA, femoral neck anteversion, femoral neck shaft angle (FNSA), alpha angle and the position of the anterior inferior iliac spine (AIIS) were investigated as morphological factor. When the most prominent point of the AIIS existed more distally than the cranial tip of the acetabular joint line in a lateral view of the pelvis model in supine position, the subjects were defined as AIIS-Type1; the remaining subjects were defined as Type 2. There were 10 hips with Type 1 and 42 hips with Type 2 AIIS. The Kappa value of inter-observer reproducibility to classify AIIS was 0.82. Multiple regression analyses were performed to analyse the relationship between ROM and the morphological parameters. We also analysed the relationship between the probability of flexion ROM being less than 110° and the factors which influenced on flexion ROM. FNSA and AIIS-Type independently influenced on simulated flexion ROM after RAO (standard regression coefficient: −0.51 and 0.37, respectively. p< 0.001). The multiple correlation coefficient was 0.68. Flexion ROM after RAO with a fixed femoral head coverage similar to that of the normal hips ranged from 95° to 141° with an average of 121°±8°. The probability of ROM being less than 110° was significantly higher in subjects with AIIS-Type 1 than in those with Type 2 (odds ratio: 13.3, p<0.01). It was also significantly higher in subjects with more than 135° of FNSA than in those with less than 135° of FNSA (odds ratio: 9.5, p<0.05). FNSA and the type of AIIS influenced on flexion ROM after RAO with approximately 40° of variation in spite of a fixed target for femoral head coverage. A large FNSA and a distal positioning of AIIS were independently associated with smaller flexion ROM after RAO.
Inappropriate soft tissue tension around an artificial hip is regarded as one cause of dislocation or abductor muscle weakness. It has been considered that restoration of leg offset is important to optimise soft tissue tension in THA, while it is unclear what factors determine soft tissue tension around artificial hip joints. The purpose of the present study was to assess how postoperative leg offset influence the soft tissue tension around artificial hip joints. The subjects were 89 consecutive patients who underwent mini-incision THA using a navigation system through antero-lateral or postero-lateral approach. Soft tissue tension was measured by applying traction amounting to 40% of body weight with the joint positioned at 0°, 15°, 30°, and 45° of flexion. The distance of separation between the head and the cup was measured using the navigation system.Introduction
Materials and Methods
Three-dimensional (3D) templating based on computed tomography (CT) in total hip arthroplasty improves the accuracy of implant size. However, even when using 3D-CT preoperative planning, getting the concordance rate between planned and actual sizes to reach 100% is not easy. To increase the concordance rate, it is important to analyze the causes of mismatch; however, no such studies have been reported. This study had the following two purposes: to clarify the concordance rate in implant size between 3D-CT preoperative planning and actual size; and to analyze risk factors for mismatch. A single surgeon performed 149 THAs using Trident Cup and Centpillar Stem (Stryker) with CT-based navigation between September 2008 and August 2011. Minimal follow-up was 2 years. Patients with incomplete postoperative CT were excluded from this study. Based on these criteria, the study examined 124 hips in 111 patients (mean age, 60 years, mean BMI 23.2 kg/m2). The preoperative diagnosis was primary osteoarthritis in 8 hips, secondary osteoarthritis in 102 hips, osteonecrosis in 9 hips, rapidly destructive coxopathy in 4 hips and rheumatoid arthritis in 1 hip. We compared cup and stem sizes between preoperative planning and intraoperatively used components. Radiological evaluations were cortical index and canal flare index on preoperative X-rays. We evaluated preoperative planning and postoperative components for cup orientation, cup position, and stem alignment (anteversion, flexion and varus angle) on the CT-navigation system. Fixation of the stem was evaluated by X-ray radiography at 2 years postoperatively according to Engh's criteria. Statistical analysis was performed with the Mann-Whitney U test, and values of P<0.05 were considered statistically significant.Puropose
Materials and Methods
In total hip arthroplasty (THA), inappropriate cup alignment cause edge loading and prosthetic impingement, which lead to various mechanical problems including dislocation, excessive wear and breakage of bearing materials, and stem neck fracture. To find the optimal cup alignment, various computer simulation studies have been conducted. However there have been few studies focusing on pelvic coordinate system as a reference of cup positioning. Our hypothesis is that the functional pelvic coordinate system with pelvic sagittal inclination in the supine position is appropriate for a reference frame of cup alignment. To test the hypothesis, we have been investigating preoperative and postoperative kinematics of pelvis and hip of THA patients. In 25 % of the consecutive 163 patients, the difference in preoperative pelvic inclination angle between the supine and standing positions (positional change of pelvic inclination [PC]) was 10o or more. Patients’ age and age-related spinal disorders including compression fracture and lumbar spondylolisthesis were independent factors associated with large preoperative PC. This raises a concern that large PC might increase the risk of edge loading and posterior prosthetic impingement when cup was positioned referencing supine pelvic position, especially in elderly patients. We compared kinematics of the hip after THA in patients with a preoperative large PC (≥10°) with that in patients with a preoperative small PC (<10°), assuming that the supine position as a zero position of the pelvis. First, we compared intraoperative passive range of motion (ROM) after implantation of the 91 hips using navigation system. No significant differences in intraoperative hip ROM were observed between the both groups. Next, we compared postoperative ROM of the 50 hips during motion of daily livings using our 4-dimentional motion analysis system within two year after THA. No significant differences in postoperative hip flexion or extension angles were observed between the both groups. These results suggested that if cup was positioned referencing the supine pelvic position, the degree of preoperative PC does not matter early after primary THA. Regarding long-term change of pelvic inclination after THA, 49 % of 70 patients followed for 10 years showed the change more than 10o in the standing position, although only 9% showed the change more than 10o in the supine position. This means that aging after THA increase discrepancy of pelvic inclination between the preoperative supine position as the reference for preoperative planning and the postoperative standing positions in some patients. However we could not find any preoperative predictors of this long-term change of pelvic inclination in the standing position. Therefore, although it is unclear whether surgeons should change the reference pelvic plane for cup alignment taking the longitudinal change of pelvic inclination in the standing position, at least, strict cup alignment control at primary THA is considered to be important to minimize the risk of edge loading and prosthetic impingement due to longitudinal changes of pelvic inclination. In conclusion, our current recommendation of pelvic coordinate system as a reference of cup alignment is a functional pelvic coordinate system with pelvic sagittal inclination in supine position.
Support cages are often used for reconstruction of acetabular bone defects in revision total hip arthroplasty. A Burch-Schneider cage is one of the most reliable systems that has shown good clinical results. It has an ischial flange and an iliac plate for screw fixation to the ilium. It is sometimes necessary to bend the flange or the plate to fit the shape of the peri-acetabulum. However, the frequency, indications, and characteristics of bending the flange or plate have not been reported. To clarify them, a simulation study was conducted. Twenty-five cases with acetabular bone defects of Paprosky type 2, 3, or 4 were the subjects of this study. A 3D template surgical simulation was conducted using 3D surface models of the Burch-Schneider cage and acetabulum. The size of the cage was determined by the size of the cavitary bone defect. Placement of the cage was performed in two ways. One was the iliac plate fitting method, in which fitting of the iliac plate to the ilium was performed first, followed by bending of the ischial flange to keep the flange in the center of the ischium. When bending of the flange was needed, it was bent at the base. The other method was the ischial flange fitting method, in which the ischial flange was inserted from the center of the ischium, followed by bending of the iliac flange to adapt to the ilium. When bending of the plate was needed, it was bent at the base. In both methods, the direction and angle of bending were measured.Introduction
Materials and methods
Although there are several reports of excellent long-term survival after cemented total hip arthroplasty (THA), cemented acetabular components are prone to become loose when compared with femoral components. On the other hand, the survival of cementless acetabular components has been reported to be equal or better than cemented ones and the use of cementless acetabular components is increasing. However, most of the reports on survival after THA are for patients with primary hip osteoarthritis (OA) and there is no report of 20-year survival of cementless THA for patients with hip dysplasia. It is supposed to be more difficult to fix cementless acetabular components for OA secondary to hip dysplasia than primary OA. The purposes of this study were to review retrospectively the 20-year survival of cemented and cementless THA for hip dysplasia and to compare the effect of fixation methods on the long-term survival for patients with hip dysplasia. We retrospectively reviewed all patients with OA secondary to hip dysplasia treated with a cemented Bioceram hip system between 1981 and 1987, and a cementless cancellous metal Lübeck hip system between 1987 and 1991. We excluded patients aged more than 60 years, males, and Crowe 4 hips. The studied subjects were 70 hips of cemented THA (Group-C) and 57 hips of cementless THA (Group-UC). Both hip implants had a 28-mm alumina head on polyethylene articulation. The mean age at operation was 50.5 years (range, 36–60 years) in Group-C and 50.0 years (range, 29–60 years) in Group-UC. The mean BMI was 23.2 kg/m2 in Group-C (range, 17.3–29.3 kg/m2) and 22.9 kg/m2 in Group-UC (range, 18.8–28.0 kg/m2). There were no significant differences in age and BMI between the two groups. The average follow-up period was 18.0 years in Group-C and 18.4 years in Group-UC. In Group-C, revision was performed in 33 hips due to aseptic cup loosening (30 hips), stem loosening (one hip), and loosening of both components (two hips). In Group-UC, revision was performed in 10 hips due to stem fracture secondary to distal fixation (4 hips), cup loosening (three hips), polyethylene breakage (two hips), and extensive osteolysis around the stem (one hip). The survival at 20 years regarding any revision as the endpoint was 51% in Group-C and 84% in Group-UC. This difference was significant using Log-rank test (P=0.006). The cup survival at 20 years was 54% in Group-C and 92% in Group-UC. This difference was also significant (P = 0.0003). The stem survival at 20 years was 95% in Group-C and 92% in Group-UC. This difference was not significant (P = 0.4826). Cementless THA showed a higher survival rate at 20 years for hip dysplasia than cemented THA because of the excellent survival of the acetabular component without cement. We conclude that cementless THA with the cancellous metal Lübeck hip system led to better longevity at 20 years than cemented THA with the Bioceram for patients with OA secondary to hip dysplasia.
There are concerns of soft-tissue reactions such as metal hypersensitivity or pseudotumors for metal-on-metal (MoM) bearings in hip arthroplasty, however, such reactions around ceramic or polyethylene bearings are incompletely understood. The present study was conducted to examine the capabilities of ultrasound screening and to compare the prevalence of periarticular soft-tissue lesions among various types of bearings. Ultrasound examinations were conducted in 163 hips (153 patients) with arthroplasty after mean a follow-up of 8.1 years (range, 1–22 years). This included 39 MoM hip resurfacings (M-HR) including 30 Birmingham hip resurfacings (BHR) and 9 ADEPT resurfacings; 36 MoM total hip arthroplasties (M-THA) with a large femoral head including 26 BHR and 10 ADEPT bearings; 21 ceramic-on-ceramic THAs (C-THA) of Biolox forte alumina bearings; 24 THAs with a conventional polyethylene liner (cPE-THA) including 19 Lubeck and 5 Omnifit systems; and 43 THAs with a highly cross-linked polyethylene liner (hxPE-THA) including 28 Crossfire and 15 Longevity liners. All procedures were performed in the lateral position through the posterior approach without trochanteric osteotomy. The M-HR group had a significantly higher frequency of male patients than the C-THA, cPE-THA, and hxPE-THA groups, and the patients in the M-HR group were younger than those in the other four groups. Ultrasound images were acquired as a still picture and in video format as the hip moved in flexion and rotation, and 4 qualitative classifications for periarticular soft-tissue reactions were determined as normal pattern, joint-expansion pattern (marked hypoechoic space between the anterior capsule and the anterior surface of the femoral component), cystic pattern (irregularly shaped hypoechoic lesions), and mass pattern (a large mass extending anterior to the femoral component). Magnetic resonance imaging (MRI) was subsequently performed in 45 hips with high-frequency encoding bandwidths. For the reliability of ultrasound screening, positive predictive value, negative predictive value, and the accuracy of the presence of abnormal patterns on ultrasound were calculated using the abnormal lesions on MRI as a reference.Purpose
Methods
Preoperative planning is an essential procedure for successful total hip arthroplasty. Many studies reported lower accuracy of two-dimensional analogue or digital templating for developmentally dysplastic hips (DDH). There have been few studies regarding the utility of three-dimensional (3D) templating for DDH. The aim of the present study is to assess the accuracy and reliability of 3D templating of cementless THA for hip dysplasia. We used 86 sets of 3D-CT data of 84 patients who underwent consecutive cementless THA using an anatomical stem and a rim-enlarged cup. There were six men and 78 women with the mean age of 58 years. The diagnosis was developmental dysplasia in 70 hips and osteonecrosis in 14 hips and primary osteoarthritis in 2 hips. There were 53 hips in Crowe group I, 11 hips in Crowe group II and 6 hips in Crowe group III. Each operator performed 3D templating prior surgery using a planning workstation of CT-based navigation system. Planned-versus-achieved accuracy was evaluated. The templating results were categorized as either exact size or +/− 1 size of implanted size. To assess the intra- and inter-planner reliabilities, 3D templating was performed by two authors blinded to surgery twice at an interval of one month. Kappa values were calculated. The accuracy and the intra- and inter-planner reliabilities were compared between the DDH group (70 hips) and the non DDH group (16 hips).Introduction
Methods
The shuck test was widely used to assess the overall soft-tissue tension around the hip joint during surgery. There have been few attempts to standardize how one evaluates soft tissue tension in total hip arthroplasty. The aim of this study was to ask how reliable the shuck test was as a measure of soft tissue tension in total hip arthroplasty. First, we assessed the intra- and inter-examiner variability of the force generated in the shuck test. Next, we asked how the strength of traction forces and joint position on the distance of displacement of the prosthetic head at surgery. Twenty-one hip surgeons, consisting of seven experienced hip surgeons, seven junior hip surgeons, and seven surgeons in training were included in the first study. Test subjects were instructed to pull a traction gauge with their customary range of force. Each subject performed two sets of the shuck test in one week interval. Eighteen patients who had cementless THA through postero-lateral approach using 3D-CT based navigation system were enrolled in the second study. After implantation of components, the leg was pull caudally using our original device [Fig. 1]. The strength of applied traction force was 20 %, 30 %, 40 % and 50 % of body weight of each patient. The distance of displacement of a prosthetic head during traction was recorded at flexion angles of 0, 15, 30 and 45 degrees using the navigation system. Internal or external rotation of legs was controlled within 5 degrees.Introduction
Methods
Ceramic-on-ceramic bearings in total hip arthroplasty (CoC THA) have theoretical advantages of wear resistance and favorable biocompatibility of ceramic particles to the surrounding bony and soft tissue. Long-time durability of CoC THA has been expected, however, clinical results over 10 years after operation were scarcely reported. In the present study, clinical results at follow of 10 years were examined for CoC THAs with a changeable femoral neck which allowed correction of anteversion of the femoral component in cases with abnormal femoral anteversion in dysplastic hips. During 1997 and 2000, 203 cementless CoC THAs in 158 patients were conducted in our hospital. Six patients died because of unrelated causes and 5 patients were lost to followup, and the remaining 188 hips in 147 patients were analyzed at the mean followup period of 10.8 years (3.7 to 13.5). There were 24 men and 123 women, and the average age at operation was 54 years (26 to 73). The hip diseases for operation were osteoarthritis in 165 hips, osteonecrosis of the femoral head in 21 hips and failure of hemiarthroplasty in 2 hips. The operation was performed in the lateral position through the posterior approach without trochanteric osteotomy. The articulation was composed of Biolox forte alumina liner fitted into beads-coated hiemispherical titanium shell, and a 28-mm Biolox forte alumina femoral head (Cremascoli). The femoral component was either AnCA stem or custom-designed stem, coupled with a modular neck allowing selection of 5 variable offsets and anteversions (Cremascoli). Clinical and radiological findings, and complications during the followup period were analyzed.Purpose
Methods
Current standard cups of metal on metal resurfacing hip arthroplasty (RHA) have no dome holes and it is very difficult for surgeons to confirm full seating of these cups. This sometimes results in gap formation between the cup and acetabular floor. Although the incidence of initial gaps using modular press-fit cups with dome screw holes has been reported to range from 20 to 35%, few studies have reported the incidence of gap formation with monoblock metal cups and its clinical consequences in RHA. The purpose of this study was to investigate retrospectively the incidence of initial gap formation and whether the initial gap influences the clinical results in RHA. RHA was performed on 166 hips of 146 patients using the Birmingham Hip Resurfacing (BHR) (MMT, UK) between 1998 and 2007. Mean age at operation was 48.7 years (range, 19-85 years). Mean duration of follow-up was 6.9 years (2.0-10.6). Acetabular reaming was performed with the use of hemispherical reamers and the reamer size was increased up to an odd number diameter which provided tight rim fit in the antero-posterior direction. The same size hemispherical provisional cup with dome holes and slits was used to check the cavity for complete seating. If the provisional cup could not be seated on the floor, reaming was repeated with the same reamer to remove the rim bump until full seating was achieved. Acetabular cups of 1mm larger diameter were impacted into the acetabulum by a press-fit technique. After press-fit fixation, the stability of the cups was confirmed with a synchronized movement of the pelvis and the cup inserter by applying a gentle torque. Clinical evaluation was performed using WOMAC at the latest follow-up. Radiographic assessments were performed using radiographs immediately after the surgery, at 3 weeks, 3 months, 1 year, and then annually thereafter. We evaluated the height of the gap between the cup and acetabular surface, cup inclination angle, cup migration and the time to gap filling. To investigate the relationship between the magnitude of the gap and the radiographic results, the patients were divided into two groups according to the height of the initial gap; the cases with a gap of less than 3 mm on the initial radiograph were grouped into a small gap group, the cases with a gap of 3mm or more were grouped into a large gap group. We compared the changes in the height of the gap, in the cup inclination angle and the cup migration between the groups.Introduction
Material and Method
The initial mechanical stability of cementless femoral stems in total hip arthroplasty is an important factor for stable biological fixation. Conversely, insufficient initial stability can lead to stem subsidence, and excessive subsidence can result in periprosthetic femoral fracture due to hoop stress. The surface roughness of stems with a surface coating theoretically contributes to initial mechanical stability by increasing friction against the bone, however, no reports have shown the effect of surface roughness on stability. The purpose of this study was to evaluate the effect of differences in surface roughness due to different surface treatments with the same stem design on the initial stability. Proximally titanium plasma-sprayed femoral stems (PS stem) and proximally grit-blasted stems (GB stem) were compared. The stem design was identical with an anatomic short tapered shape for proximal fixation. The optimum size of PS stem based on 3D templating was implanted in one side of 11 pairs of human cadaveric femora and the same size of GB stems was implanted in the other side. After implantation, the specimens were fixed to the jig of a universal testing machine in 25cm of entire length so that the long axis of the femur was positioned at 15-degrees adduction to the vertical. Vertical load tests were conducted under 1 mm/minute of displacement-controlled conditions. After 200 N of preload to eliminate the variance in the magnitude of press-fit by manual implantation, load was applied until periprosthetic fracture occurred.Introduction
Materials and Methods
There have been few reports with efficient treatments for neglected distal tibiofibular syndesmosis disruption. Here we will report four cases of successful anatomical reconstruction with autologous gracilis tendon, using the interference fit anchoring (IFA) system. All four cases were males between 20 and 58 years of age at the time of surgery (mean age 36 years). The post-injury period to surgery was between 7 and 59 months (mean 20.1 months), with the consultation period being from 5 to 19 months (mean 9.5 months). Radiographs at the time of injuries were all malleolar fractures of pronation-external rotation (PE) stage 3 in the Lauge-Hansen classification. Stress tests for distal tibiofibular syndesmosis were positive in all cases (dilation more than 2 mm). Arthroscopic drilling was conducted in two cases with a cartilaginous injury of trochlea of talus. Distal tibiofibular syndesmosis was anatomically repositioned and was fixed with screws after bony and soft tissues within the tibiofibular syndesmosis were removed and fibular adhesion was dissected. Ipsilateral autologous gracilis tendon was passed through foramen in the insertion of the anterior inferior tibiofibular tendon on tibia and fibula, and was fixated using the IFA system. The preoperative Japanese society for surgery of the foot (JSSF) score was from 26 to 74 points (mean 43.5) and postoperative JSSF score was from 67 to 100 (mean 89.5). In a case where there was a poor outcome, five years of post injury had passed before the surgery. Although the JSSF score improved to 67 points postoperatively (from the preoperative score of 26) in this case, arthroscopic arthrodesis was conducted 5 months postoperatively due to persistent pain. Anatomical reconstruction with autologous gracilis tendon using the IFA system showed a favorable functional prognosis overall. However, there was a case with progressive degenerated changes of injured distal tibiofibular syndesmosis due to a prolonged post-injury period resulted in a poor outcome.
