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
The purpose of this retrospective study was to estimate the outcome improvements after Total Hip Arthroplasty (THA) using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) in patients who underwent THA with a navigation system in our institutions, and to compare them with those undergoing THA without a navigation system that had been reported in the literatures. The subjects in this study comprised 245 patients (39 males, 206 females; mean age, 59.9±12.0 years; mean BMI, 22.8±3.2 kg/m2) who underwent THA. All patients had adequate data to allow complete scoring of the WOMAC for a minimum one-year postoperative follow-up. CT-based navigation was used in all THAs. Postoperatively, no restrictions were imposed. A MEDLINE search was conducted using the search terms ‘Total hip’, ‘Quality of life (QOL)’, and ‘WOMAC’. 10 articles evaluated all WOMAC subscales one to two years after THA. The WOMAC subscale scores were compared statistically between our study and the results reported in the 10 articles using Welch's t-test. The present physical function subscale scores were the best of the 10 studies, and in 8 of the 10 studies, the differences were significant. WOMAC subscale results in our study were significantly better than those reported in most articles in which THA was performed without navigation. These results show that THA using navigation can improve patients' postoperative QOL.
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
Femoral head diameters in THA have been increasing due to good long-term outcomes of 1st generation HXLP cups. Furthermore, some 2nd generation HXLP cups allow 36mm or larger heads. However, larger femoral head diameters increase the frictional torque and may lead to early cup migration and loosening. And there is a concern that larger head diameters and reduced liner thickness may increase polyethylene wear. In this study, we compared early acetabular component migration and wear rates between a group of larger heads using a 2nd generation HXLP and a group smaller heads using a 1st generation HXLP. The larger head group comprising 30 hips underwent THA between February 2010 and March 2011 with the use of a sequentially cross-linked polyethylene liner (X3). 30 patients were included in this study (30 women). Their mean age was 59.3years; mean weight was 53.6kg. Trident HA-coated cementless cups were used and the sizes ranged from 46mm to 56mm (mean 50.5mm). The head diameters were 36mm in 23hips, 40mm in 5 hips, and 44mm in 2hips. All X3 liners were 5.9mm or less in thickness. A control group was selected from a previous case series that had undergo THA between July 2007 and January 2008 using a 1st generation HXLP liner (Crossfire) by matching age and sex. Therefore 30 patients were included in this study (30 women) too. Their mean age was 60.0 years; mean weight was 55.5kg. The same Trident cups were used and the sizes ranged from 46mm to 56mm (mean 49.5mm). The head diameters were 26mm in 19hips and 32mm in 11hips. The liner thicknesses were 7.8mm or more. All hips had standardized anteroposterior pelvic digital radiographs performed postoperatively and cup migration was measured on digital radiographs at the immediate postoperative period and two year using EBRA-CUP software. We analyzed horizontal and vertical cup migration distance and the difference in cup anteversion and inclination angle at two years. Additionally, total head penetrarion and polyethylene liner volumetric wear rates were measured using a computer-assited method with PolyWear software. The larger head group revealed an average of 0.48mm of horizontal migration, 0.75mm of vertical migration, 0.19degree of inclination change, and 1.26 degrees of anteversion change. The control group showed an average of 0.63mm of horizontal migration, 0.36mm of vertical migration, 0.07 degree of inclination change, and 0.88 degree of anteversion change. Based on the EBRA-CUP measurements, there were no cases of significant early loosening which was indicated by more than 1mm of migration, more than 2.5 degree of inclination change, or more than 3.3 degree of anteversion change. The liner penetration rates were 0.388±0.192mm/yr in the large head group and 0.362±0.178mm/yr in the control group. The difference was not significant (p=0.64.) The volumetric wear rates were 42.8±27.9mm⁁3/yr in the large head group and 42.0±33.0mm⁁3/yr in the control group. Again, the difference was not significant (p=0.94). No significant early cup migration or increased wear rate were detected in THA with the sequentially cross-linked polyethylene liner and 36mm or large heads at two years.
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
To confirm whether developmental dysplasia of
the hip has a risk of hip impingement, we analysed maximum ranges
of movement to the point of bony impingement, and impingement location
using three-dimensional (3D) surface models of the pelvis and femur
in combination with 3D morphology of the hip joint using computer-assisted methods.
Results of computed tomography were examined for 52 hip joints with
DDH and 73 normal healthy hip joints. DDH shows larger maximum extension
(p = 0.001) and internal rotation at 90° flexion (p <
0.001).
Similar maximum flexion (p = 0.835) and external rotation (p = 0.713)
were observed between groups, while high rates of extra-articular
impingement were noticed in these directions in DDH (p <
0.001).
Smaller cranial acetabular anteversion (p = 0.048), centre-edge
angles (p <
0.001), a circumferentially shallower acetabulum,
larger femoral neck anteversion (p <
0.001), and larger alpha
angle were identified in DDH. Risk of anterior impingement in retroverted
DDH hips is similar to that in retroverted normal hips in excessive
adduction but minimal in less adduction. These findings might be
borne in mind when considering the possibility of extra-articular
posterior impingement in DDH being a source of pain, particularly
for patients with a highly anteverted femoral neck. Cite this article:
We investigated differences in the location and
mode of labral tears between dysplastic hips and hips with femoroacetabular
impingement (FAI). We also investigated the relationship between
labral tear and adjacent cartilage damage. We retrospectively studied
72 symptomatic hips (in 68 patients: 19 men and 49 women) with radiological
evidence of dysplasia or FAI on high-resolution CT arthrography.
The incidence and location of labral tears and modes of tear associated
with the base of the labrum (Mode 1) or body of the labrum (Mode
2) were compared among FAI, mildly dysplastic and severely dysplastic
hips. The locations predominantly involved with labral tears were
different in FAI and mild dysplastic hips (anterior and anterosuperior
zones) and in severely dysplastic hips (anterosuperior and superior
zones) around the acetabulum. Significant differences were observed
in the prevalence of Mode 1 Hip pathology is significantly related to the locations and modes
of labral tears. Mode 1 tears may be a risk factor for the development
of adjacent acetabular cartilage damage. Cite this article:
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
Lesion location and volume are critical factors to select patients with osteonecrosis for whom resurfacing arthroplasty is appropriate. However, no reliable surgical planning system which can assess relationship between necrotic lesions and the femoral component has been established. We have developed a 3D-MRI-based planning system for resurfacing arthroplasty. The purpose of the present study was to evaluate its feasibility. The subjects included five patients with osteonecrosis of ARCO stage 3 or 4 who had undergone resurfacing THA at our institute. All patients had an MRI before surgery using 3D-SPGR sequences and fat suppression 3D-SPGR sequencea. In cases where it was difficult to distinguish bone marrow edema and reparative zone on 3D-SPGR images, fat suppression 3D-SPGR sequences were used. Simulation of resurfacing arthroplasty was performed on image analysis software where multidirectional oblique views could be reconstructed. The femoral neck axis was determined by drawing line through centers of two spheres which were fitted to the normal portion of the femoral head and the mid-portion of femoral neck. A femoral component was virtually implanted to align the femoral neck axis and match the implant center and femoral head center.Introduction
Methods
