The purpose of this preliminary study was to evaluate the feasibility and accuracy of HipAlign (OrthAlign, Inc., USA) system for cup orientation in total hip arthroplasty (THA). The subjects of this study were 5 hips that underwent primary cementless THA via a posterior approach in the lateral decubitus position. Evaluation 1; after reaming acetabular bone, a trial cup was placed in the reamed acetabulum in an aimed alignment using HipAlign. Then, the trial cup alignment was measured using HipAlign and CT-based navigation system in the radiographic definition. Evaluation 2; a cementless cup was placed in the reamed acetabular in an aimed alignment using CT-based navigation and cup alignment was measured using both methods. After operation, we measured the cup alignment using postoperative CT in each patient. In the results, the average cup inclination measured with HipAlign was around 5 degrees of true cup inclination angles. The average cup anteversion with HipAlign tended to be larger than that with CT-based navigation or postoperative CT in both evaluations. That is because there is a difference in the pelvic sagittal tilt between the lateral position and supine position. In conclusion, this study suggests that guiding cup alignment with the use of HipAlign is feasible through a posterior approach and the mean cup inclination measured with HipAlign showed an acceptable level of accuracy, but the mean cup anteversion is not reliable. We need a further modification for pelvic registration to improve the accuracy of cup anteversion.
To obtain appropriate joint gap and soft tissue balance, and to correct the lower limb alignment are important factor to achieve success of total knee arthroplasty (TKA). A variety of computer-assisted navigation systems have been developed to implant the component accurately during TKA. Although, the effects of the navigation system on the joint gap and soft tissue balance are unclear. The purpose of the present study was to investigate the influence of accelerometer-based portable navigation system on the intraoperative joint gap and soft tissue balance. Between March 2014 and March 2015, 36 consecutive primary TKAs were performed using a mobile-bearing posterior stabilized (PS) TKA (Vanguard RP; Biomet) for varus osteoarthritis. Of the 36 knees, 26 knees using the accelerometer-based portable computer navigation system (KneeAlign2; OrthAlign) (N group), and 10 knees using conventional alignment guide (femur side; intramedullary rod, tibia side; extramedullary guide) (C group). The intraoperative joint gap and soft tissue balance were measured using tensor device throughout a full range of motion (0°, 30°, 45°, 60°, 90°, 120°and full flexion) at 120N of distraction force. The postoperative component coronal alignment was measured with standing anteroposterior hip-to-ankle radiographs.INTRODUCTION
METHODS
The concept of anatomical stam is fit-and-fill in the proximity of the femur and to expect wall fixation, following to reduce thigh pain and stress shielding. Although the femoral medullary form and size are different in each races. CentPillar TMZF stem (stryker ®) is anatomical stem designed based on computer-tomography of Japanese femurs. The purpose of this study was to evaluate clinical and radiographic outcomes of CentPillar TMZF stem at a mean of 3.6 years postoperatively. We asseses the results of 98 primary total hip arthroplasty (THA) performed using a CentPillar TMZF stem in 91 Japanese patients (4 males, 94 females) undergoing surgery between August 2007 and June 2011, the mean age at the time of surgery was 62.0 (41–81) years old. The Diagnosis were osteoarthritis (OA) in 91 hips, rapidly destructive coxopathy (RDC) in 4 hips, rheumatoid arthritis (RA) in 3 hips. Clinical and radiographic assessments were performed for every patient for every follow up using Japan Orthopaedic Association (JOA) Score, thigh pain, revision surgery and complications. Radiographic assessments were including stem alignment on anteroposterior radiograph, stress shielding, bone remodeling, radiolucent line, osteolysis, loosening and subsidence.INTRODUCTION
METHODS
Rotational alignment of the femoral and tibial component in total knee arthroplasty (TKA) are separately determined based on the anatomy of each bone. Popular references are the transepicondylar axis (TEA) for femoral component, and medial one-third of the tibial tubercle for the tibial component. It was reported that these references are not in accordance with each other in osteoarthritic (OA) knees and rotational mismatch could occur even when the components were accurately aligned. There has been, however, a paucity of data as for the rotational mismatch after TKA for OA knees. The purpose of this study was to evaluate the rotational mismatch between the femoral and tibial component after TKA for OA knees. Eighty-four knees which underwent primary TKA for the varus osteoarthritis of the knee were analyzed. Those knees were chosen by the retrospective confirmation of the precise rotational alignments of both femoral and tibial components by postoperative computed tomography (with ±3 degrees to the targeted reference lines described below). The femoral reference line was the surgical epicondylar axis and the tibial reference line was Akagi's line; a line connecting the midpoint of the tibial insertion of the posterior cruciate ligament and the medial border of patellar tendon. Intraoperative, dynamic evaluations of the rotational mismatch between femoral and tibial components was performed with a special device attached to the mobile-bearing trials at full extension and in neutral, passive external rotation and passive internal rotation.INTRODUCTION
SUBJECTS & METHODS
Modulus femoral prosthesis is a modular cementless femoral system which consists of 5 degree tapered conical stem made of a titanium alloy with 8 fins of 1mm and modular neck. Modular neck enables to control any ideal stem anteversion as a surgeon prefers. This system is considered to be useful in severe hip deformity, for example developmental dysplasia of the hip (DDH). In this study, clinical and radiographic outcomes of the Modulus femoral prosthesis were evaluated at a mean of 3.6 (2–6) years postoperatively. We assessed the results of 193 primary total hip arthroplasty using a Modulus femoral prosthesis in 169 patients (15 males, 154 females) undergoing surgery between September 2007 and December 2011. The mean age at the time of surgery was 65.6 (31–86) years old. The diagnoses were osteoarthritis (OA) in 178 hips (including 167 hips of DDH), rapidly destructive coxopathy (RDC) in 6 hips, rheumatoid arthritis (RA) in 6 hips, osteonecrosis in 2 hips, and subchondral insufficiency fracture in one hip. Clinical outcomes were assessed using Japan Orthopedic Association (JOA) hip scores and complications. Radiographic assessments were including stem alignment, bone on-growth, cortical hypertrophy, stress shielding and stem subsidence. 43.8 points of the preoperative mean JOA score was significantly improved to 93.1 points postoperatively. In one case intraoperative femoral fracture was occurred. One dislocation had occurred and thigh pain was observed in one hip. No revision surgery was required. In 192 hips of 193 hips (99.5%), stem was implanted in neutral position (within ±2 degrees). Bone on-growth was observed in all cases (94.3% in zone 3; 73.1% in zone 5; 30.6% in zone 2; 22.3% in zone 6). Cortical hypertrophy was observed in 66 hips (34.2%) at zone 3 and 5. Reduction of bone density due to stress shielding was observed (1st degree was 58.5%; 2nd degree was 29.5%; 3rd degree was 11.9%; 4th degree was 0%). In 22 cases (11.4%), more than 2mm of stem subsidence was observed, however the subsidence was stopped within 6 months in all cases. Modulus femoral prosthesis showed good clinical results and radiographic findings up to 6 years postoperatively.
Metal on metal total hip arthroplasty (MoM THA) provides the potential improvement in articular wear. However, several adverse events including pseudotumor had been reported. Magnetic resonance imaging (MRI) was considered to be the proposal tool for detection of pseudotumor after MoM THA. In this study, we performed the screening of pseudotumor after MoM THA using the MRI. We studied 43 patients with M2a Magnum® (Biomet) and 34 patients with M2a Taper® (Biomet) of MoM THA from December 2009 to December 2011 with follow-up of 2.5 years (2.0–4.0 years) after surgery. MRI assessments were performed at a mean of 2.1 years postoperatively. Pseudotumor findings were graded using Anderson classification (Skeletal Radiol, 2011: 40; 303). Age, sex, height, weight, Harris Hip Score, EQ5D satisfaction score, UCLA activity score, and blood metal ion levels were evaluated. The prevalence of pseudotumor was 27.2%; 56 normal (Type A), 13 mild (C1), 8 moderate (C2) and none were graded severe (C3). Weight and BMI in the mild group was significantly higher than those in normal. There was no significant difference in age, sex and height among these groups. With regard to Harris Hip score, pain and ROM score in moderate group was significantly lower than that in normal and mild group. EQ5D satisfaction score and UCLA activity score showed not significant differences among groups. 3.01±3.32 μg/L of blood cobalt ion levels in the moderate groups was significantly higher than 0.97±0.64 μg/L in normal group. Blood cobalt ion levels of 1 mild and 2 moderate were over the threshold of 7 μg/L. These patients were implanted with M2a Taper, not M2a Magnum. 14% of the prevalence in the patients with M2a Magnum was significantly lower than 41% in the patients with M2a Taper. No revision surgeries were required. The patients with no pseudotumor did not show the increase of blood metal ion. Contrarily, several patients showed the increase of blood metal ion in case of detecting pseudotumor. MRI assessments were useful for screening of pseudotumor after MoM THA and blood metal ion should be investigated for patients with mild and moderate pseudotumor in MoM THA.
It has been reported that rotational deformity is present in varus osteoarthritis (OA) of the knee and the tibia rotates externally as the varus deformity progresses. Although many studies addressed the rotational alignment of the femoral and tibial component in total knee arthroplasty (TKA), the pre-and postoperative changes of the rotational alignment in varus OA knee has not been evaluated. The purpose of this study was to quantitatively analyze the alteration of rotational deformity after TKA for the varus OA knee. Between July 2011 and December 2012, 157 patients (159 knees) with primary varus OA knee undergoing TKA were included. A mobile-bearing, posterior stabilized knee prosthesis was implanted with cement in all patients. Rotational deformities were evaluated with computed tomography (CT) before and after the operation. On the selected CT slices, the relative rotational position of the femur and tibia was quantified as an angle between the line perpendicular to the surgical epicondylar axis of the femur and the line connecting the tibial tubercle tip and the geometric center of the tibia. The knees were divided into three groups according to the preoperative varus deformity (Group I; 0–8° varus, n = 78, Group II; 9–17 ° varus, n = 71 and Group III; 18 ° or greater varus, n = 10) and the difference among the groups were statistically analyzed.INTRODUCTION:
METHODS:
Metal on metal total hip arthroplasty provides the potential improvement in articular wear and the use of large-diameter femoral heads following the prospect for reduction in the risk of dislocation. The purpose of this study was to compare the clinical and radiographic outcomes as well as serum metal ion level between the two different component designs with small and large femoral heads in metal on metal total hip arthroplasty. We studied 39 patients with large head (Magnum®, Biomet; cup size minus 6 mm) and 37 patients with small head (M2a taper®, Biomet; 28 or 32 mm head) of metal on metal total hip arthroplasty between December 2009 to October 2011 with follow-up of 2.1 years (1.0–3.3 years) after surgery. Harris Hip Score, UCLA activity score, EQ-5D, radiographic assessment, and serum cobalt and chromium ion levels were evaluated. Harris Hip Score, UCLA activity score, and EQ-5D were improved after surgery in small and large head groups, however, no significant differences were observed between both groups. Cup inclination was below 50 degree in all prosthesis. No loosening and no osteolysis were observed. Cobalt and chromium ion was not detected before surgery; however, metal ion levels of both groups were increased after surgery in time dependent manner. There was no significant difference between two groups at one year after surgery. One patient in each group showed the increase of cobalt ion level over 7 ppb (15.4 ppb, 12.9 ppb) without any clinical symptom including pain. Cup inclination was 29 degree in both patients and cup anteversion was 38 and 41 degree, respectively. There was no significant difference of ion levels between both groups. No dislocation was observed in large head group while one dislocation occurred in small head group. No patients required the revision surgery. This metal on metal component, especially with large femoral heads, showed the good clinical results at the maximum follow up of 3.3 year after surgery. However, the ion level of two patients increased over 7 ppb and longer follow-up will be needed.
