Compared with the cruciate-retaining (CR) insert for total knee arthroplasty (TKA), the cruciate-substituting (CS) insert has a raised anterior lip, providing greater anterior constraint, and thus, can be used in cases of posterior cruciate ligament (PCL) sacrifice. However, studies have shown that the PCL maintains femoral rollback during flexion, acts as a stabilizer against distal traction force and aids knee joint proprioception; therefore, the argument for PCL excision in CS TKA remains controversial. The purpose of this study was to analyze CS TKA kinematics and identify the role of the PCL. Seven fresh-frozen lower-extremity cadaver specimens were analyzed using Orthomap® Precision Knee Navigation software (Stryker Orthopaedics, Mahwah, NJ, USA). They were surgically implanted with Triathlon® components (Stryker Orthopaedics). The CS insert has a raised anterior lip, and the posterior geometry shares the same profile as the CR, so we can choose retaining or sacrificing the PCL. Six patterns were analyzed: (1) natural knee; (2) only anterior cruciate ligament excision; (3) CS TKA, PCL retention, and bony island preservation; (4) CS TKA, PCL retention, and bony island resection; (5) CS TKA and PCL excision; and (6) CR TKA and PCL excision. Center of the knee and center of the proximal tibia were registered using navigation system, and the magnitudes of the condylar translation were evaluated. And then, using trigonometric function, the magnitude of anterior-posterior translation of the femur was calculated.Introduction
Methods
The number of total hip arthroplasties has been increasing worldwide, and it is expected that revision surgeries will increase significantly in the near future. Although reconstructing normal hip biomechanics with extensive bone loss in the revision surgery remains challenging. The custom−made acetabular component produced by additive manufacturing, which can be fitted to a patient's anatomy and bone defect, is expected to be a predominant reconstruction material. However, there have been few reports on the setting precision and molding precision of this type of material. The purpose of this study was to validate the custom−made acetabular component regarding postoperative three−dimensional positioning and alignment. Severe bone defects (Paprosky type 3A and 3B) were made in both four fresh cadaveric hip joints using an acetabular reamer mimicking clinical cases of acetabular component loosening or osteolysis in total hip arthroplasty. On the basis of computed tomography (CT) after making the bone defect, two types of custom−made acetabular components (augmented type and tri−flanged type) that adapted to the bone defect substantially were produced by an additive manufacturing machine. A confirmative CT scan was taken after implantation of the component, and then the data were installed in an analysis workstation to compare the postoperative component position and angle to those in the preoperative planning.Introduction
Methods
Recently the taper wedged stems (TWS) are used widely in Japan because of good bone fixation and ease of the procedure. However, it is unclear how TWS get initial fixation in Japanese, especially dysplasia hip or elderly patients who had stovepipe canal. The purpose of this study is to evaluate initial bone fixation of the TWS in Japanese using computed tomography and to estimate biological bone fixation of the TWS using the Tomosynthesis. We evaluated 100 hips underwent primary total hip arthroplasty using TWS. All patients were performed computed tomography within 2 weeks postoperatively and evaluated which part of the canal was made contact with the stem. 24 hips were male and 76 hips were female. According to the canal flare index, 9 hips were champagne flute canal, 80 hips were normal canal and 11 hips were Stovepipe canal. 10 hips were Dorr type A, 80 hips were Dorr type B and 10 hips were Dorr type C. The initial bone fixation was classified as Medio-lateral fit (fixed at Gruen zone 2 and 7), Flare fit (fixed at zone 2 and 6), Varus 2-point fit (fixed at zone 3 and 7), Valgus 3-point fit (fixed at zone 2, 5 and 7), Distal fit (fixed at zone 3 and 5), Total fit (fixed at zone 2,3,5,6 and 7) by the stem A-P view. Moreover, we defined Medio-lateral fit, Flare fit and Total fit as Adequate fit, Varus 2-point fit and Valgus 3-point fit as Varus or Valgus fit, Distal fit as Distal fit. The stem alignment was classified as flexion, neutral and extension by the stem lateral view. Femoral component fixation was graded as bone ingrowth, fibrous ingrowth and unstable by hip radiographs after surgery at 1 year. Spot-welds were evaluated using tomosynthesis after surgery at 6 months.Background
Methods
In total hip arthroplasty (THA), the femoral component influences leg length inequality and gait, and is associated with poor muscle strength and other unsatisfactory long-term results. We have therefore used intraoperative radiographs to acquire accurate measurements of femoral component size and position. At the last meeting of this society, we reported that accurate positioning was successfully achieved in 68 cases (87.2%) as a consequence of taking intraoperative radiographs. However, we have little understanding as regards to the accuracy of X-ray measurements. We accordingly undertook an examination of the accuracy of such measurements. The purpose of this study was to evaluate the difference between leg length discrepancy (LLD) measured using X-ray and computed tomography (CT). The study group comprised 48 primary THAs performed between October 2010 and April 2012. Using 2D template software (JMM Corporation), we measured LLD using pre-operative anteroposterior (AP) radiographs of the pelvis. On the basis of both teardrop lines, we measured LLD of the lesser trochanter top (Fig. 1), lesser trochanter direct top (Fig. 2), and trochanteric top (Fig. 3). Furthermore, using Aquarius NET software, we measured LLD using AP and lateral scout views of the pelvis and bilateral femurs. This data was defined as the true LLD. The difference between the X-ray data (lesser trochanter top, lesser trochanter direct top, and trochanteric top) and the CT data was defined as accuracy. Additionally, we measured the size of the lesser trochanter and examined the association.Objective
Materials and Methods
Hip resurfacing arthroplasty has been surgical options in younger and more active patients with osteoarthritis (OA) and osteonecrosis (ON) of the femoral head. Although excellent midterm results of this procedure have been reported, there is a concern about postoperative impingement between the preserved femoral neck and the acetabular component. There were few reports about kinematics after hip resurfacing. Therefore, the purpose of this study was to investigate the postoperative motion analysis after hip resurfacing using a noble dynamic flat-panel detector (FPD) system by which clear sequential images were obtained with low dose radiation exposure. 11 patients (mean age: 47.8 ± 7.4), 15 hips were included in this study. There were ten men and one woman. The preoperative diagnoses were ON of the femoral head in 10 hips, OA in 3 hips, and others in 2 hips. Mean postoperative follow-up period was 25.1 ± 21.6 months. Femoral anteversion, cup inclination and cup anteversion were measured on computed tomography and plain radiograph. Impingement signs such as the reactive osteophyte formation and divot around the femoral neck were also investigated on the anteroposterior (AP) and lateral radiographs. Sequential images of active and passive flexion motion in 45-degrees semilateral position, and active abduction motion in a supine position were obtained using a noble dynamic FPD system.Introduction
Materials and methods
The aim of this study was to assess the accuracy of aligning the cup with the transverse acetabular ligament (TAL) in total hip arthroplasty (THA) and the reproducibility of this procedure by using computer-assisted navigation. Between January 2011 and March 2012, 75 patients (81 hips) underwent primary THA using the posterolateral approach at our hospital. We excluded 4 hips with a history of pelvic osteotomy; thus, the study included 77 hips. We measured the anatomical anteversion of the TAL intraoperatively by aligning the inferomedial rim of the cup trial with the TAL using computer-assisted navigation. We set the abduction to 45° at measure of the anteversion of the TAL. Measurements for each hip were independently performed thrice by 2 surgeons chosen among 1 expert and 6 non-experts. The surgeon performing the measurement was blinded during this process; the navigation screen was turned away from the surgeon's field of view. Anatomical inclination and anteversion were measured with reference to the functional pelvic plane. The intraclass correlation coefficient (ICC) was used to assess intra- and inter-observer reliability. The mean value of all 6 measurements was used to determine the anteversion of the TAL in each hip.Introduction
Methods
Intramedullary femoral alignment guide is mostly used in total knee arthroplasty (TKA). Accurate preoperative plan is critical to get good alignments when we use intramedullary femoral guide, because the center of femoral head cannot be looked directly during operation. Commonly, the planning is carried out using preoperative anteroposterior radiographs of the femur. The angles formed between mechanical axes of the femur and distal femoral anatomic axes (AMA) are measured as reference angles of resection of distal femur, and the entry points of intramedullary femoral guide are also planned. The purpose of this study is to investigate the influence of femoral position on radiographic planning in TKA. We examined 20 knees of 20 female patients who received TKA. Fourteen patients suffered from primary osteoarthritis of the knees, and 6 suffered from rheumatoid arthritis. Fifteen patients have varus knee deformities and 5 patients have valgus knee deformities. Long leg computed topography scans were performed in all cases before operations, and all images were stored in DICOM file format. The analyses were performed with computer software (3D template, JMM, Osaka, Japan) using DICOM formatted data. The planes containing the center of femoral head and transepicondylar axes were defined as reference planes, and the reference planes were fixed all through analyses. At first, to assess the influence of femoral rotation, the femur was rotated from 30 degrees external rotation to 30 degrees internal rotation in 5 degrees increments in full extension. After that, to examine the influence of knee flexion, the knee was bended from full extension to 30 degrees flexion in 5 degrees increments in neutral rotation. Reconstructed coronal planes parallel to the reference planes were made, the angles between mechanical axes of the femur and distal femoral anatomic axes (AMA) and the distance from entry points to the center of femoral intercondylar notch were measured in each position. The distal anatomic axes were made by connecting the center of femoral canal at 8 centimeters proximal to joint line and that at 16 centimeters proximal to joint line. The entry points of intramedullary femoral guide were defined the points where distal anatomic axes meets intercondylar notch.Introduction
Materials and Methods
Rotational acetabular osteotomy (RAO) is an effective treatment option for symptomatic acetabular dysplasia. However, excessive lateral and anterior correction during the periacetabular osteotomy may lead to femoroacetabular impingement. We used preoperative planning software for total hip arthroplasty to perform femoroacetabular impingement simulations before and after rotational acetabular osteotomies. We evaluated 11 hips in 11 patients with available computed tomography taken before and after RAO. All cases were female and mean age at the time of surgery was 35.9 years. All cases were early stage osteoarthritis without obvious osteophytes or joint space narrowing. Radiographic analysis included the center-edge (CE) angle, Sharp's acetabular angle, the acetabular roof angle, the acetabular head index (AHI), cross-over sign, and posterior wall sign. Acetabular anteversion was measured at every 5 mm slice level in the femoral head using preoperative and postoperative computed tomography. Impingement simulations were performed using the preoperative planning software ZedHip (LEXI, Tokyo, Japan). In brief, we created a three-dimensional model. The range of motion which causes bone-to-bone impingement was evaluated in flexion (flex), abduction (abd), external rotation in flex 0°, and internal rotation in flex 90°. The lesions caused by impingement were evaluated.Background
Methods
Alumina-on-alumina bearings exhibit low wear rates in vitro and one commonly used ceramic implant is the Trident system (Stryker, Mahwah, NJ). There are some reports of incomplete seating of the ceramic liner in the Trident acetabular shell. However, it is often difficult to detect incomplete seating intraoperatively. We sought to prevent incomplete seating using intraoperative radiography. We retrospectively reviewed 19 hips in 17 patients who had undergone primary total hip arthroplasty using a Trident shell with a metal-backed alumina liner between 2007 and 2010. There were 16 women and 1 man, with an average age of 45.7 years. Preoperative diagnosis revealed 14 cases of osteoarthritis and 5 cases of osteonecrosis. All procedures were performed using a posterolateral approach with PSL cups. The minimum follow-up time was 12 months (average 28 months). All procedures included an intraoperative anteroposterior view radiograph to evaluate cup seating. If incomplete seating was recognized we reinserted the liner. Postoperatively, radiographs (supine anteroposterior and cross table lateral views) and computed tomography were performed in all cases in order to assess any residual incomplete seating. We investigated whether it was possible to avoid incomplete seating using intraoperative radiography.Introduction
Materials and Methods
The treatment of osteonecrosis of the femoral head (ONFH) in young and active patients remains a challenge. The purpose of this study was to determine and compare the clinical and radiographic results of the two different hip resurfacing systems; hemi-resurfacing and metal-on-metal total hip resurfacing in patients with ONFH. This study was a retrospective review of 20 patients with 30 hips who had ONFH and underwent hemi-resurfacing or total hip resurfacing between November 2002 and February 2006. We mainly performed hemi-resurfacing for early stage ONFH, and total hip resurfacing for advanced stages. Fifteen hips in 11 patients had a hemi-resurfacing component (Conserve, Wright Medical Co) with a mean age at operation of 50 years and an average follow-up of 5.5 years. Fifteen hips in 10 patients had a metal-on-metal total hip resurfacing component (Birmingham hip resurfacing, Smith & Nephew Co.) with a mean age at operation of 40 years and an average follow-up years.Introduction
Methods
The position of the acetabular component affects the result of total hip arthroplasty(THA) in terms of postoperative dislocation, impingement, wear etc. However, as it is much difficult to place the component in the appropriate position for the cases of severe acetabular deformity, we used a Computed tomography(CT)-based navigation for THA in such cases. Therefore, the purpose of this study was to estimate the accuracy of a CT-based navigation in terms of acetabular component positioning in THA for severe acetabular deformities. 13 patients (1 man, 12 women), 14 hips underwent THA using a posterolateral approach with a CT-based navigation. The diagnoses were severe developmental dysplasia (Crowe group III, IV) in 6, ankylosis in 3, destructive arthritis after infection in 2, Charcot joint, and arthrodesed hip. And, we evaluated the differences of component position from the center of the anterior pelvic plane(APP), anteversion angle, and inclination angle relative to APP between the intraoperative data from the navigation system and the data from postoperative CT. Considering the intra-observer error, the measurement was done three times respectively and the mean value was accepted. We also estimated the difference between the component size planned and that implanted. The mean difference between intraoperative records and actual postoperative results of the component position shows 3.3 mm(range: 0–7.0, SD: 2.2) for the horizontal position, 3.2 mm(range: 0–9.7, SD: 4.5) for the vertical position, 4.4 mm(range: 2.0–7.7, SD: 1.6) for the antero-posterior position from the center of the APP, 1.3 degrees(range: 0–3.0, SD: 0.9) for the inclination and 2.9 degrees(range: 0.3–8.3, SD: 2.2) for the anteversion respectively. All components were placed in the safe zone by Lewinnek. The component size was predicted in 10/14(71.4%) hips. There were no complications related to the use of the navigation. This study showed the accuracy of cup positioning using a CT-based navigation in THA for the cases of severe acetabular deformity. We concluded that this system was a useful tool for surgeon to identify orientation, implant acetabular component at the precise position and angle, and to reduce the incidence of some complications especially for patients with these severe acetabular deformities.
