Aims

This study aimed to investigate the incidence of ≥ 5 mm asymmetry in lower and whole leg lengths (LLs) in patients with unilateral osteoarthritis (OA) secondary to developmental dysplasia of the hip (DDH-OA) and primary hip osteoarthritis (PHOA), and the relationship between lower and whole LL asymmetries and femoral length asymmetry.

Aims

This study aimed to develop and validate a fully automated system that quantifies proximal femoral bone mineral density (BMD) from CT images.

Aims

Pelvic incidence (PI) is considered an important anatomical parameter for determining the sagittal balance of the spine. The contribution of an abnormal PI to hip osteoarthritis (OA) remains controversial. In this study, we aimed to investigate the relationship between PI and hip OA, and the difference in PI between hip OA without anatomical abnormalities (primary OA) and hip OA with developmental dysplasia of the hip (DDH-OA).

The purposes of this study were to evaluate the accuracy and feasibility of a robotic preparation for acetabular metal augments in patients with developmental dysplasia of the hip (DDH). Mako robotic arm reaming was used in 7 DDH to prepare the bony cavities for both Trident PSL cups and Tritanium acetabular wedge augments in six hips with Crowe 2 or 3 DDH. In CT-based planning, a properly sized cup was placed in the original acetabulum, and the same sized cup was also placed to fit the superolateral acetabular defect. The coordinates of the planned positions of cup and augment were recorded to manage the robotic arm reaming. After registration of the patient's pelvis, robotic reaming was performed first for the augment, then, for the cup by changing the target position of reaming as planned. The accuracy of the cup and augment placement was assessed on postoperative CT. To evaluate the feasibility of the robotic procedure, the OR time and blood loss were compared with those of 13 patients who received the same cup and augment systems with a conventional technique. All procedures were done without fracture or fixation failure. There were no differences in OR time or blood loss between the two procedures. Postoperative CT measurements of the distance between the cup center and the augment sphere center showed less than 2mm difference from the Mako preoperative planning.

Although a longer time of follow up evaluation is mandatory, our robotic acetabular augment preparation technique is accurate and feasible.

Introduction

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.

Introduction

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.

Introduction

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.

Objectives

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.

Aims

The aim of this study was to examine whether hips with unilateral osteoarthritis (OA) secondary to developmental dysplasia of the hip (DDH) have significant asymmetry in femoral length, and to determine potential related factors.

The purposes of this study were to review retrospectively the 10-year outcome of cementless total hip arthroplasty (THA) using an active robot system in the femoral canal preparation for an anatomic short stem and navigation in the cup placement through a mini incision posterior approach. We reviewed all patients who underwent THA with this procedure in 53 hips between 2004 and 2007. There were no intraoperative fracture nor navigation- or robotic-related complications. All implant sizes were same as planned ones. All cases were followed up at least two years and all implants showed bone ingrowth stable according to the Engh's criteria. After then, six patients died of unrelated causes. Two patients (three hips) could not come to the 10-year follow-up examination. The remaining 44 hips were followed for 10 to 12 years (11 years on average). There is no dislocation. The average JOA hip score improved from 48 preoperatively to 96 at the final examination. On the postoperative x-ray measurements, the average cup radiographic inclination was 39° and the radiographic anteversion was 14°. There was no stem which showed more than 2° of varus or valgus alignment. There was no case who showed more than 5mm of limb length discrepancy. Postoperative CT images of 38 hips were obtained at 2 weeks. After matching the coordinates of the pelvis and femur with the preoperative planning, we got very small differences in alignment parameters between the measured values and the planed ones. The difference differences between the plan and measured values were −0.1° in cup inclination, −1.4° in cup anteversion, stem 0.5° in coronal alignment, 0.6° in stem sagittal alignment, and −1.6° in stem anteversion, respectively. We conclude that our robotic femoral preparation for a short anatomical stem and navigated cup placement thru a mini-posterior approach was safe and feasible without affecting the accuracy of the procedure. There were no long term adverse effect of the procedure.

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.

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Background

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.

Introduction

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.

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.

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.

INTRODUCTION

The purpose of this study is to elucidate longitudinal kinematic changes of the hip joint during heels-down squatting after THA.

Introduction

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.

Introduction

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.

Introduction

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.

Introduction

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.

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.

Introduction

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.

Puropose

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.

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 10^o 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 10^o in the standing position, although only 9% showed the change more than 10^o 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.

Introduction

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.

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: Bone Joint J 2014;96-B:580–9.

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 versus Mode 2 tears in FAI hips (72% (n = 13) vs 28% (n = 5)) and severe dysplastic hips (25% (n = 2) vs 75% (n = 6)). The frequency of cartilage damage adjacent to Mode 1 tears was significantly higher (42% (n = 14)) than that adjacent to Mode 2 tears (14% (n = 3)).

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: Bone Joint J 2013;95-B:1320–5.

Background

Growing of the geriatric population has brought about increase of lower extremity fractures. The purpose of this study was to investigate the occurrence of surgical site infection after the surgery for lower extremity fractures, except proximal femoral fracture, in over eighty years old patients.

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.

Purpose

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.

Introduction

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.

Introduction

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.

Purpose

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.

Introduction

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.

Introduction

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.

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.

Introduction

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.

Introduction

In osteonecrosis of the femoral head (ONFH), progression of collapse is influenced by a repair reaction, especially bone resorptive activity, around the necrotic bone. Alendronate is a potent inhibitor of bone resorption by inhibiting osteoclast activity. We performed a clinical study to test if systemic alendronate treatment would prevent the development of collapse in patients with ONFH.

Introduction

Femoral neck fracture (FNF) is a common trauma in the elderly individuals. When the blood supply to the femoral head is impaired with a fracture event, the reduction or disruption of blood supply to the bone, hypoxia, leads to death of the bone marrow and trabecular bone, and eventual late segmental collapse. In the reparative process, osteoblasts and osteoclasts perform the important function of repairing the fracture site at the femoral neck. However, the reparative reaction including angiogenesis and osteogenesis remains unknown. In order to investigate the reparative reaction in patients with FNF, the distribution of tartrate resistant acid phosphatase (TRAP)-positive cells and expression of HIF-1 alpha, VEGF, and FGF-2 were observed in 36 hips in 35 patients.

Using a larger diameter femoral head in total hip arthroplasty (THA) has advantages in terms of the increased joint stability and range of motion. And the wear resistance of highly cross-linked polyethylene (HXLPE) even combined with a larger head has already been demonstrated by in vitro studies. The purpose of this study was to compare the in vivo wear of Longevity HXLPE sockets against 32 mm and 26 mm heads at a 5-year follow-up.

From November 2000 to November 2001, 51 primary cementless THAs were performed with a 26 mm cobalt-chromium head and a Longevity HXLPE socket (Zimmer). A cohort of 32 mm cobalt-chromium heads was comprised of 51 THAs with the same prosthesis performed from December 2001 to December 2003. No significant differences between the groups were observed in gender, age, and BMI, however, polyethylene liners with 32 mm heads were significantly thinner than those with 26 mm heads. Two-dimensional linear wear was measured using PolyWare software on annual x-rays, and total head penetration rates at postoperative 5-year and steady state wear rates were calculated. In addition, periprosthetic osteolysis was evaluated.

At the 5-year follow-up, the total head penetration rates were 0.047±0.022 mm/year with 26 mm heads and 0.048±0.026 mm/year with 32 mm heads. The steady state wear rates were −0.008 mm/year with 26 mm heads and 0.001 mm/year with 32 mm heads. No significant differences were seen between the two groups (p=0.82 and p=0.24). Osteolysis was not observed around pros-theses in any hips.

At the 5-year follow-up, the wear rate of Longevity HXLPE was very low. A Longevity HXLPE socket will undergo the same level of wear whether with a 32 mm head or a 26 mm head.

The long-term results of grafting with hydroxyapatite granules for acetabular deficiency in revision total hip replacement are not well known. We have evaluated the results of revision using a modular cup with hydroxyapatite grafting for Paprosky type 2 and 3 acetabular defects at a minimum of ten years’ follow-up. We retrospectively reviewed 49 acetabular revisions at a mean of 135 months (120 to 178). There was one type 2B, ten 2C, 28 3A and ten 3B hips. With loosening as the endpoint, the survival rate was 74.2% (95% confidence interval 58.3 to 90.1). Radiologically, four of the type 3A hips (14%) and six of the type 3B hips (60%) showed aseptic loosening with collapse of the hydroxyapatite layer, whereas no loosening occurred in type 2 hips. There was consolidation of the hydroxyapatite layer in 33 hips (66%). Loosening was detected in nine of 29 hips (31%) without cement and in one of 20 hips (5%) with cement (p = 0.03, Fisher’s exact probability test). The linear wear and annual wear rate did not correlate with loosening.

These results suggest that the long-term results of hydroxyapatite grafting with cement for type 2 and 3A hips are encouraging.

We compared a modular neck system with a non-modular system in a cementless anatomical total hip replacement (THR). Each group consisted of 74 hips with developmental hip dysplasia. Both groups had the same cementless acetabular component and the same articulation, which consisted of a conventional polyethylene liner and a 28 mm alumina head. The mean follow-up was 14.5 years (13 to 15), at which point there were significant differences in the mean total Harris hip score (modular/non-modular: 98.6 (64 to 100)/93.8 (68 to 100)), the mean range of abduction (32° (15° to 40°)/28 (0° to 40°)), use of a 10° elevated liner (31%/100%), the incidence of osteolysis (27%/79.7%) and the incidence of equal leg lengths (≥ 6 mm, 92%/61%). There was no disassociation or fracture of the modular neck.

The modular system reduces the need for an elevated liner, thereby reducing the incidence of osteolysis. It gives a better range of movement and allows the surgeon to make an accurate adjustment of leg length.

Ceramic heads and highly cross-linked polyethylene (HXLPE) as bearing surface materials have been introduced to reduce the production of polyethylene wear particles. The present study hypothesized that the wear rate of HXLPE could be further reduced when combined with a ceramic head. The purpose of this study was to compare the in vivo wear of Longevity HXLPE against cobalt-chromium and zirconia heads after a minimum 5-year follow-up.

A prospective cohort study was performed in 102 cementless total hip arthroplasties (THAs) with the Longevity HXLPE socket (Zimmer) between June 2000 and October 2001. Same prostheses were used in all cases both acetabular cups (Trilogy; Zimmer) and femoral stems (Versys Fiber Metal Taper; Zimmer). 26-mm zirconia heads (NGK) or 26-mm cobalt-chromium heads (Zimmer) were randomly used in 51 hips each. A minimum 5-year follow-up was completed for 47 hips with zirconia heads and 46 hips with cobalt-chromium heads. Two-dimensional linear wear of Longevity HXLPE was measured using computer-assisted methods (PolyWare) on annual x-rays, and total head penetration rates and steady state wear rates were calculated. In addition, periprosthetic osteolysis was evaluated.

At a mean 6-year follow-up, the total head penetration rates were 0.034±0.016 mm/year (zirconia) and 0.031±0.015 mm/year (cobalt-chromium). The steady state wear rates were −0.01 mm/year (zirconia) and −0.01 mm/year (cobalt-chromium). No significant difference was seen between the two groups (p=0.4 and p=0.91). Osteolysis was not observed around prostheses in any hips.

In conclusion, no advantage was seen for the zirconia head compared with the cobalt-chromium head in this time period.

The anterior pelvic plane (APP) through the bilateral anterior superior iliac spines (ASIS) and pubic tuberosities is often used as a pelvic reference in measuring orientation of the acetabular cup in total hip arthroplasty. Apophyses such as ASIS are, however, anatomically variable among patients and APP does not always represent the functional pelvic tilt in the sagittal plane in each patient. Therefore, malposition of the cup and recurrent dislocation may occur even though the cup is placed in a safe zone when measured against APP. We analyzed dynamic pelvic tilt angle in the sagittal plane using a motion analysis system after THA and we found a case of recurrent dislocation due to an unusual APP tilt.

A 77-year-old woman underwent primary THA 3 years ago and cup re-implantation was done with the use of a 10-degree elevated liner and the head diameter was increased from 26mm to 28 mm after two anterior dislocations. However, posterior dislocation occurred 11 times after this. A second revision was performed with a 36 mm head and cup anteversion was optimized against APP. Further posterior dislocations occurred twice again. To probe the cause of recurrent dislocation, we performed motion analysis using a 6-camera VICON system and the markers were registered to the bone and implant models based on the postoperative CT images. This system visually represents four-dimensional dynamic motions that include the time sequential transitions of components and their posture. The cup had been placed in 6 degrees of radiographic anteversion against APP, and in −13 degrees of radiographic retroversion in supine (FPP), because the pelvic flexion angle in supine was 17.6 degrees. Furthermore, when standing, the pelvic flexion angle increased 10 degrees.

Malposition of the acetabular cup in THA is the most common cause of dislocation. To avoid errors in cup placement, computer navigation systems have been introduced and most of the navigation systems refer APP to establish cup orientation. There are two drawbacks in using APP as the reference. One is that apophyses such as ASIS develop variably in each patient with a resulting variability in APP tilt in the sagittal plane in supine. The other is significant changes in pelvis tilt during various activities of daily living such as standing, walking, and sitting. Therefore, even if cup orientation is acceptable when referencing APP, it can be mal-oriented in a functional position of the pelvis as in this case, which showed proper anteversion against APP but retroversion in supine, standing and sitting.

In conclusion, we found that there exists a case in which APP is not a suitable pelvic reference in determining orientation of the cup.

To analyze the long term results of a third generation ceramic on ceramic bearing in cementless total hip arthroplasty (THA), we reviewed the clinical and radiological results of 100 consecutive THAs performed in 86 patients (68 females, 80 hips; 18 males, 20 hips) between 1996 and 1998. The average age at operation was 55 years with a range of 26 to 73 years. The diagnoses were osteoarthritis in 83 hips, osteonecrosis in 10 hips and rheumatoid arthritis in 7 hips. The articulation was composed of a hemispherical titanium porous bead-coated cup (AnCA), a Biolox Forte alumina ceramic cup liner and a ball with a diameter of 28-mm. The modular ceramic liner was fixed directly to the metal cup without polyethylene sandwich or metal rim. A press-fit technique of 1 mm under-reaming without screws was used for cup fixation. The ceramic head was fixed to a 12/14 taper cone of a modular neck which allowed changes in neck-shaft angle, anteversion, and offset. All operations were performed via a posterolateral approach under general anesthesia. To measure the cup orientation, an ellipse was fitted to the acetabular component rim on the early postoperative AP radiographs using computer software. The average cup inclination and anteversion in the radiographic definition were 41 (range 28 to 63) and 17 (range 3 to 34) degrees, respectively. 22 cups were outside the Lewinnek safe zone. All patients were radiographically evaluated in term of implant stability at two years using Engh’s criteria. All of the acetabular components radiologically were judged to be bone-ingrown stable at two years except one cup. 98 stems were judged to be bone-ingrown stable and the remaining two stems were judged to be fibrous stable at two years. After two years, all patients except for two were followed up clinically and radiologically for at least 10 years or until revision or death. One unstable cup was revised at 2.5 years. This case had a previous Chiari’s pelvic osteotomy and insufficient press-fit of the cup was assumed to have led to loosening. One of the two fibrous stable stems was revised at six years due to aseptic loosening. One rheumatoid arthritis hip with stable bone ingrown fixation developed late infection at six years and was revised. One stable cup showed chipping of the acetabular liner at 8 years and required revision. The orientation of this cup was 55 degrees of inclination and 17 degrees of anteversion and the high inclination was thought to be related to the ceramic liner chipping. The remaining hips showed no osteolysis or loosening at the final follow-up. There were no squeaking hips. The 10-year survivorships with the endpoint of mechanical loosening or revision were 96.7% and 95.6%, respectively. We conclude that the third generation ceramic on ceramic hip bearing without polyethylene sandwich provided long term stability and eliminated periprosthetic osteolysis.

Alendronate is a potent inhibitor of bone resorptive activity, and has been shown to prevent and restore periprosthetic osteolysis in experimental models. A preliminary study was conducted to examine clinical usefulness of a lendronate treatment.

Twenty-five patients (27 hips) with radiological evidence of osteolysis after cemented total hip arthroplasty were included. Of these, 14 patients (15 hips) were administered 5 mg of alendronate daily (alendronate group), and 11 patients (12 hips) did not receive alendronate treatment (control group). The subjects were followed up for 12 months, using radiological examinations and biochemical markers. The radiological analysis was evaluated blindly by 2 joint arthroplasty experts, each with more than 10 years of experience, without knowledge of alendronate administration.

In the alendronate group, average serum bone alkaline phosphatase and urinary excretion of the N-telopep-tide of type I collagen values decreased from the baseline values after administration of alendronate, to 71% and 76% of baseline at the 3-month examination, and 57% and 62% at the 1-year examination, respectively. In the control group, expansion of osteolysis was found in 5 hips (42%) and no hip showed restoration of osteolysis. In the alendronate group, expansion of osteolysiswas found in 2 hips (13%), and restoration of osteolysis was found in 5 hips (33%). There was a statistically significant difference in ratio of hips with osteolysis restoration between the 2 groups (p< 0.05). In the alendronate group, there was no significant difference in age, average linear wear rate of polyethylene, and the biochemical markers, between the hips with and without diminishment of osteolysis.

Conclusions: The present results indicate that clinicala-lendronate treatment can prevent and restore periprosthetic osteolysis, which is generally thought to require surgical intervention. These findings warrant further study of the effects of duration and dose of alendronate treatment, component materials, and component fixation methods.

Introduction: Progression of collapse in osteonecrosis of the femoral head (ONFH) is greatly influenced by repair reactions, especially bone resorptive activity. This study was performed to test if systemic alendronate treatment, a potent inhibitor of osteoclast activity, can prevent the development of collapse in ONFH.

Materials and Methods: Daily administration of oral alendronate (5mg/day) was started in 14 hips in 11 patients with ONFH (Alendronate group). At the beginning of the study (3, 6, 12 months), plain radiographs, T1-weighted MR imaging, and biochemical makers of osteoclast activity (N-telopeptide of type-I collagen) and osteoblast activity (Bone-specific alkaline phosphatase), were examined. At 12 months, MR imaging was repeated. Eleven hips in 6 patients with ONFH who did not receive alendronate administration were considered as the control group.

Results: There was no significant difference with respect to gender distribution, etiology factors, initial ARCO stages, and extent of necrosis in the two groups. In the alendronate group, there was an early decrease of osteoclast activity at 3 months, with a decrease to 62% at 12 months, while the decrease of osteoblast activity was smaller with 80% at 12 months. Development of collapse was observed in 4 of the 11 hips (36%) in the control group, and in none of the 14 hips in the alendronate group. There was a significant difference of collapse development between the two groups (p=0.026, Mann-Whitney U-test). Signal change on serial MR images was observed in 5 of 9 hips (56%) in the control group, with only one of 9 hips (11%) in the alendronate group.

Discussion: The low incidence of signal change on serial MR images may reflect the decrease of repair activity in the alendronate group. The present study was the first clinical trial to show that alendronate has a significant preventive effect of collapse development in patients with osteonecrosis of the femoral head.

Introduction: There is controversy over whether the lesions of osteonecrosis of the femoral head (ONFH) will spontaneously decrease. This study reports a longitudinal study of lesion volume using high-resolution serial MRI and recently developed techniques for image registration to realign serial images.

Materials and Methods: Baseline and follow-up (minimum one year later) MRI scans were carried out on 15 patients (18 hips). Accurate subvoxel registration was performed and subtraction images were produced to reveal areas of regional necrotic lesion change. Volume-to-femoral head ratio (VFR) was calculated to normalize the measured volume to the total femoral head volume.

Results: Three of 18 hips showed spontaneous reductions in the size of the lesions. They were all related to steroid use and were within one year after initial steroid treatment The mean volume decrease of these 3 hips was 3.4 ± 2.0 cm³ (SD) and its VFR was 6.8 ± 3.1 % (SD). Mean necrotic lesion volumes at baseline of decreasing lesions and unchanged lesions were 4.6 ± 2.5 cm³ (VFR, 9.1 ± 3.9 %) and 7.5 ± 5.5 cm³ (VFR, 16.7 ± 12.4 %), respectively.

There was no statistically significant difference in baseline lesion volume between decreasing lesions and unchanged lesions.

Discussion: In conclusion, some early lesions within one year after onset can decrease in size on MRI, regardless their size at baseline.

Introduction: In order to investigate the relationship between the degeneration of the acetabular cartilage and the radiological staging of osteonecrosis of the femoral head, the following study was performed.

Materials and Methods: Acetabular cartilage with sub-chondral bone was taken from the superior dome from 34 hips from 30 patients undergoing total hip arthroplasty due to osteonecrosis of the femoral head. The specimens were stained with hematoxylineosin and safranin-O, and were evaluated as to the thinning of cartilage, fibrillation, clefts, and proliferation of chondrocytes. There were 18 females and 12 males with an average age of 49 years. We used the radiological staging system proposed by the working group of the Specific Disease Investigation Committee under the auspices of the Japanese Ministry of Health, Labor and Welfare. There were eight hips in stage IIIA disease (collapse of the femoral head less than 3 mm), 19 hips in stage IIIB disease (collapse 3 mm or greater), and seven stage IV disease hips.

Results: All 34 specimens showed histological abnormalities. In eight stage IIIA hips, six hips were mild and two were moderate histological degeneration. In 19 stage IIIB hips, five hips were mild, six were moderate, and eight had severe arthrosis. Seven stage IV hips had severe arthrosis.

Discussion: Although the radiographs cannot demonstrate early degeneration of cartilage, degenerative changes were present in all stage III hips. Histological degenerative changes in stage IIIB hips were more severe than those in stage IIIA hips. These findings should be kept in mind in treating patients with osteonecrosis of the femoral head.

In 52 patients we compared the accuracy of standard anteroposterior (AP) radiography, mortise radiography and MRI with arthroscopy of the ankle for the diagnosis of a tear of the tibiofibular syndesmosis. In comparison with arthroscopy, the sensitivity, specificity and accuracy were 44.1%, 100% and 63.5% for standard AP radiography and 58.3%, 100% and 71.2% for mortise radiography. For MRI they were 100%, 93.1% and 96.2% for a tear of the anterior inferior tibiofibular ligament and 100%, 100% and 100% for a tear of the posterior inferior tibiofibular ligament. Standard AP and mortise radiography did not always provide a correct diagnosis. MRI was useful although there were two-false positive cases. We suggest that arthroscopy of the ankle is indispensable for the accurate diagnosis of a tear of the tibiofibular syndesmosis.