SL-PLUS MIA stem (Smith & Nephew Orthopaedics AG) is a modified implant of Zweymuller type SL-PLUS standard stem (Smith & Nephew Orthopaedics AG). We constructed finite element (FE) models and analysed equivalent stresses in the femur. In addition, we measured bone mineral density (BMD) in the femur by dual-energy X-ray absorptiometry (DEXA) after THA. The purpose of this study was to investigate the equivalent stress and to compare the results of the FE analyses with changes in BMD after THA. Twenty-one patients (18 women and 3 men) who underwent primary cementless THA with SL-PLUS MIA or SL-PLUS formed the basis of this study. Eleven patients received SL-PLUS MIA and ten patients received SL-PLUS. Zones were defined according to Gruen's system (zones 1∼7). Computed-tomography (CT) images of the femur were taken before and at 1 week after THA. FE models of the femur and prosthesis were obtained from CT data by Mechanical Finder (Research Center of Computational Mechanics Inc., Tokyo, Japan), software that creates FE models showing individual bone shape and density distribution. Equivalent stresses were analysed in zones 1 to 7 and compared to the DEXA data. FE studies revealed that there was no significant difference in equivalent stress between SL-PLUS MIA and SL-PLUS. BMD was maintained after THA in zones 3, 4, and 5, whereas BMD decreased in zones 2, 6, and 7. In zone 1, BMD decreased in SL-PLUS MIA stem group by 14%, while BMD was maintained in SL-PLUS standard stem.

In this study, we evaluated the labrum tear using radial sequence 3D Multiple Echo Recombined Gradient Echo (MERGE) MRI without arthrography based on modified Czerny's classification, comparing with actual arthroscopic findings. A total of 61 hips including 27 hips of femoroacetabular impingement (FAI), 19 hips of borderline development dysplasia of the hip (BDDH) and 15 hips of early stage osteoarthritis (OA) were enrolled this retrospective study. MRI findings evaluated in each three regions of interest; anterior region, anterolateral region, and lateral region. The cases with severe degeneration that is not concordant with any original Czerny's classification is defined as stage4. We compared MRI findings with arthroscopic findings and calculated the sensitivity, specificity, and likelihood ratio in terms of the existence of labrum tear. MRI findings revealed labrum tear more frequently in anterolateral than lateral (p<0.001). Especially in FAI group, labrum tear was more frequently observed by MRI in anterolateral than lateral (p=0.006). In comparison with MRI findings and arthroscopic findings, the sensitivity was 97%, specificity was 79% and likelihood ratio was 4.59 as average of all regions in terms of the existence of labrum tear. In each region, sensitivity and specificity was 97% and 50% in anterior, 97% and 100% specificity in anterolateral, 94% and 81% in lateral, respectively. Thus, MERGE MRI revealed excellent sensitivity and specificity for diagnosis of labrum tear, especially in anterolateral region. The cases with severely degenerated labrum were classified as newly defined stage 4, which was recognized frequently in OA cases.

Infection is one of the most serious complications of orthopedic surgery, particularly in implant-related procedures. Minimum inhibitory concentration (MIC) for identified bacteria is an important factor for successful antibiotic treatment. We investigated the MIC of antibiotics in Staphylococcus species from orthopedic infections, comparing with isolates from respiratory medicine. Staphylococcus species isolated in our laboratory from January 2013 to July 2016 were retrospectively reviewed. The MIC of vancomycin (VCM), arbekacin (ABK), teicoplanin (TEIC), linezolid (LZD), and rifampicin (RFP) was reviewed. Differences in the MIC of each antibiotic in orthopedic and respiratory samples were determined. A total of 259 isolates were evaluated (89 orthopedic, 170 respiratory). Staphylococcus aureus was the most commonly identified species (58%). In comparison with orthopedic samples, the number of isolates with a VCM MIC <0.5 μg/ml in methicillin sensitive staphylococcus aureus (MSSA) was significantly higher in respiratory isolates, while a MIC of 2 μg/ml was significantly lower (P = 0.0078). The proportion of isolates with a VCM MIC of 2 μg/ml in methicillin-resistant coagulase-negative staphylococci (MRCNS) was significantly higher in orthopedic isolates than that seen in respiratory isolates of methicillin-resistant staphylococcus aureus (MRSA; P < 0.001). When comparing MRCNS and other orthopedic Staphylococci, the rate of RFP MIC >2 μg/ml in MRCNS isolates was significantly higher (P = 0.0058). The MIC of VCM in Staphylococcus species from orthopedic infection was higher than that of respiratory samples, particularly in MRCNS from implant-related samples. MRCNS showed a significantly higher rate of resistance for RFP versus other orthopedic isolates.

Background

Knee osteoarthritis (OA) is a major cause of ambulatory disabilities. Although total knee arthroplasty (TKA) has been reported as the most effective treatment for severe knee OA, quantitative evaluation of ambulatory function have not been well investigated.

We hypothesized that better functional recovery would result in better patient satisfaction. The purpose of this study was to quantitatively evaluate ambulatory functional recovery and assess the influence on patient satisfaction after TKA.

Background

In measured resection (MR) technique it is sometimes not easy to equalize extension gap (EG) and flexion gap (FG) because the size of femoral component is generally determined only depending on the anteroposterior and mediolateral size of femoral condyle in MR technique. In order to equalize the EG and FG, femoral implant size should be determined so that the FG is similar to the EG. We developed the novel sizing technique of femoral component to equalize the EG and FG in MR technique. The purpose of this study was to examine the usefulness of this technique.

Introduction

Computed tomography (CT) based preoperative planning provides useful information for severe TKA and revision TKA cases, such as the amount of augmentation, length of stem extension and component alignment, to achieve correct alignment and joint line. In this study, we evaluated TKA alignment performed with CT preoperative planning.

Objectives

Excessive acetabular coverage is the most common cause of pincer-type femoroacetabular impingement. To date, an association between acetabular over-coverage and genetic variations has not been studied. In this study we investigated the association between single nucleotide polymorphisms (SNPs) of paralogous Homeobox (HOX)9 genes and acetabular coverage in Japanese individuals to identify a possible genetic variation associated with acetabular over-coverage.

There are several methods for evaluating stability of the joint during total knee replacement (TKR). Activities of daily living demand mechanical loading to the knee joint, not only in full extension, but also in mid-flexion. The purpose of this study was to compare the varus-valgus stability throughout flexion in knees treated with either cruciate-retaining or posterior-stabilised TKR, using an intra-operative navigation technique. A total of 34 knees underwent TKR with computer navigation, during which the investigator applied a maximum varus-valgus stress to the knee while steadily moving the leg from full extension to flexion both before and after prosthetic implantation. The femorotibial angle was measured simultaneously by the navigation system at every 10° throughout the range of movement. It was found that posterior-stabilised knees had more varus-valgus laxity than cruciate-retaining knees at all angles examined, and the differences were statistically significant at 10° (p = 0.0093), 20° (p = 0.0098) and 30° of flexion (p = 0.0252).

Cite this article: Bone Joint J 2013;95-B:493–7.

Introduction

Anterior cervical decompression and fusion (ACDF) is considered a standard surgical treatment to degenerative discogenic diseases. Lately, the question arises whether or not ACDF significantly influences the progression of adjacent disc degeneration (ADD). The etiology of ADD is obscure and it has not been fully understood whether ADD is a consequence of fusion or it represents the aging pathway of the degenerative cervical process, thus making it a controversial topic [1-3]. There have been several discussions about the possibility of ACDF altering biomechanical conditions at adjacent segments, therefore resulting in increased load and excessive motion [3,4]. The purpose of this study was to compare the cervical segmental motion pre- and post-ACDF using novel 3D analytical techniques.

Introduction: Recent studies suggested that trans-epicondylar axis (TEA) as the origin of collateral ligament was valuable axis for the parallel cut of the posterior condyle. An alternative landmark of the angle between the TEA and anterior trochlear line of the lateral and medial femoral condyles (trochleo-epicondylar angle) for determining the rotational positioning of the femoral component could be considered. We here report a simple radiographic view with a landmark of the anterior and posterior femoral condyle for determining the rotational alignment of the femoral component in TKA.

Subjects and methods: Our new radiograph presented an axial view of distal femur of a patient. The patient lay in the supine position and flexed the knee about 120 to 130 degrees. An x-ray beam was applied to the knee at the angle of 20 degrees to the ground surface. We measured the external rotational angle between posterior condylar (PC) line and clinical TEA that was condylar twist angle, and the internal rotational angle between the anterior trochlear line (AT line) and clinical TEA. This study involved 122 knees in 82 patients with osteoarthritis of the knee, an average age of 67.3 years. And we compared our measured angle with the angle from 3D reconstructed images with 3-dimensional helical CT system (n=35).

Results: The former angle was 5.7° ± 3.2° and the latter was −5.6° ± 2.9°. There was a variation by individual patients, the condylar twist angle was negative correlation with tibio-femoral angle. The internal rotation angle of the trochlear line and clinical TEA (trochleo-epicondylar angle) was 4.9°±2.1°. The tibio-femoral angle was positively correlated with the trochlear line angle. The trochlear line angle from 3D-CT was 5.4°±1.9°. The average of the difference between our view and the 3D-CT was 0.5°± 1.0°, R=0.87 with a Spearman’s rank test.

Discussion and conclusion: We improved the simple radiographic view in order to evaluate the TEA and PC line, and also the anterior trochlear line, for assessing the rotational alignment of the distal femur in total knee arthroplasty (TKA). We are able to measure and evaluate both angles and do double-checking the condylar twist angle and trochlear line angle. Our new radiographic technique is easy to measure the condylar twist angle, and the angle between AT line and clinical TEA (trochleo-epicondylar angle), simple and reliable, and may be an alternative method for the assessment of TEA of the femur in TKA as preoperative planning.

Introduction: Recent studies suggested that trans-epicondylar axis (TEA) as the origin of collateral ligament was valuable axis for the parallel cut of the posterior condyle. An alternative landmark of the angle between the TEA and anterior trochlear line of the lateral and medial femoral condyles (trochleo-epicondylar angle) for determining the rotational positioning of the femoral component could be considered. We here report a simple radiographic view with a landmark of the anterior and posterior femoral condyle for determining the rotational alignment of the femoral component in TKA.

Subjects and methods: Our new radiograph presented an axial view of distal femur of a patient. The patient lay in the supine position and flexed the knee about 120 to 130 degrees. An x-ray beam was applied to the knee at the angle of 20 degrees to the ground surface. We measured the external rotational angle between posterior condylar (PC) line and clinical TEA that was condylar twist angle, and the internal rotational angle between the anterior trochlear line (AT line) and clinical TEA. This study involved 122 knees in 82 patients with osteoarthritis of the knee, an average age of 67.3 years. And we compared our measured angle with the angle from 3D reconstructed images with 3-dimensional helical CT system (n=35).

Results: The former angle was 5.6° ± 2.8° and the latter was −5.7° ± 3.2°. There was a variation by individual patients, the condylar twist angle was negative correlation with tibio-femoral angle. The internal rotation angle of the trochlear line and clinical TEA (trochleo-epicondylar angle) was 4.9°±2.1°. The tibio-femoral angle was positively correlated with the trochlear line angle. The trochlear line angle from 3D-CT was 5.6°±2.0°. The average of the difference between our view and the 3D-CT was 0.5°± 1.0°, R=0.87 with a Spearman’s rank test.

Discussion and conclusion: We improved the simple radiographic view in order to evaluate the TEA and PC line, and also the anterior trochlear line, for assessing the rotational alignment of the distal femur in total knee arthroplasty (TKA). We are able to measure and evaluate both angles and do double-checking the condylar twist angle and trochlear line angle. Our new radiographic technique is easy to measure the condylar twist angle, and the angle between AT line and clinical TEA (trochleo-epicondylar angle), simple and reliable, and may be an alternative method for the assessment of TEA of the femur in TKA as preoperative planning.