Association between low back pain and quality of life in patients with rheumatoid arthritis according to patient-reported outcomes using the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ): A cross-sectional study.

OBJECTIVES: To evaluate factors associated with low back pain (LBP) and effect on quality of life (QOL) using patient-reported outcome in patients with rheumatoid arthritis (RA). METHODS: Overall, 414 patients with RA who answered the Japanese Orthopedic Association Back Pain Evaluation Questionnaire (JOABPEQ) were included in this study. LBP-positive was defined a visual analog scale (VAS) of LBP (LBP VAS) of ≥ 30 mm. RESULTS: The rate of LBP-positive group was 24.9%. Body mass index (BMI) (odds ratio [OR]: 1.116), tender joint count (TJC) (OR: 1.598), global VAS (OR: 1.016), and Health Assessment Questionnaire Disability Index (HAQ-DI) (OR: 2.392) were found as significant LBP-associated factors. When adjusted for sex and van der Heijde-modified total Sharp score, BMI (OR: 1.120), TJC (OR: 1.619), global VAS (OR: 1.016), pain VAS (OR: 1.015), and HAQ-DI (OR: 2.312) were found to be the significant factors associated with LBP. Moreover, LBP VAS had relatively high correlations in all domains of the JOABPEQ scores (correlation coefficient: LBP, -0.601; lumbar function, -0.624; walking ability, -0.548; social life function, -0.479; and mental health, -0.463). CONCLUSIONS: This study investigated the effect of LBP in patients with RA. The results of this study indicate that LBP is associated with the physical function and QOL in patients with RA. We believe that our results will be useful for physical function and QOL assessments in patients with RA with LBP.

The importance of bony impingement in restricting flexion after total knee arthroplasty: computer simulation model with clinical correlation.

We constructed patient-specific models from computed tomography data after total knee arthroplasty to predict knee flexion based on implant-bone impingement. The maximum flexion before impingement between the femur and the tibial insert was computed using a musculoskeletal modeling program (KneeSIM; LifeModeler, Inc, San Clemente, California) during a weight-bearing deep knee bend. Postoperative flexion was measured in a clinical cohort of 21 knees (low-flex group: 6 knees with <100° of flexion and high-flex group: 15 size-matched knees with >125° of flexion at 2 years). Average predicted flexion angles were within 2° of clinical measurements for the high-flex group. In the low-flex group, 4 cases had impingement involving the bone cut at the posterior condyle, and the average predicted knee flexion was 102° compared with 93° measured clinically. These results indicate that the level of the distal femoral resection should be carefully planned and that exposed bone proximal to the tips of the posterior condyles of the femoral component should be removed if there is risk of impingement.

Age-related changes in kinematics of the knee joint during deep squat.

Researchers frequently use the deep knee squat as a motor task in order to evaluate the kinematic performance after total knee arthroplasty. Many authors reported about the kinematics of a normal squatting motion, however, little is known on what the influence of aging is. Twenty-two healthy volunteers in various age groups (range 21-75 years) performed a deep knee squat activity while undergoing motion analysis using an optical tracking system. The influence of aging was evaluated with respect to kinematics of the trunk, hip, knee and ankle joints. Older subjects required significantly more time to perform a deep squat, especially during the descending phase. They also had more knee abduction and delayed peak knee flexion. Older subjects were slower in descend than ascend during the squat. Although older subjects had a trend towards less maximal flexion and less internal rotation of the knee compared to younger subjects, this difference was not significant. Older subjects also showed a trend towards more forward leaning of the trunk, resulting in increased hip flexion and anterior thoracic tilt. This study confirmed that some aspects of squat kinematics vary significantly with age, and that the basic methodology employed here can successfully detect these age-related trends. Older subjects had more abduction of the knee joint, and this may indicate the load distribution of the medial and lateral condyles could be different amongst ages. Age-matched control data are therefore required whenever the performance of an implant is evaluated during a deep knee squat.

Anterior border of the tibia as a landmark for extramedullary alignment guide in total knee arthroplasty for varus knees.

A disadvantage to using extramedullary alignment guides of the tibia for total knee arthroplasty (TKA) is difficulty in correctly identifying the ankle center. The anterior border of the tibia is easily palpable, as it is not covered by muscles and its shape is convex anteriorly. We hypothesized that appropriate points exist along the anterior border that can be used as landmarks for extramedullary guides. Prior to TKA, computed tomographic images of the entire tibia were obtained from 101 osteoarthritic knees with varus deformities. The relationship between the lines connecting two points on the anterior border and the mechanical axis was evaluated using 3D imaging software. The mean angles between each of 10 determined axes and the mechanical axis varied from 3.2° varus to 2.1° valgus in the coronal plane. In the sagittal plane, all axes referencing the anterior border of the tibia showed anterior inclination to the mechanical axis. The line connecting the medial one-third of the patellar tendon attachment and the distal one-fourth of the anterior border, however, was highly consistent and parallel to the mechanical axis in the coronal plane. This axis can be effectively used as a landmark for extramedullary guides during TKA.

Flexion contracture persists if the contracture is more than 15° at 3 months after total knee arthroplasty.

After total knee arthroplasty, it is common for flexion contracture to exist during the early stages of postoperative course. We retrospectively investigated whether the early postoperative contracture would finally disappear, in 104 osteoarthritic knees after surgery with posterior-stabilized prostheses. The knees were divided into 5 groups based on their contracture 3 months after surgery (group I: no contracture, group II: 5°, group III: 10°, group IV: 15°, group V: ≥20°). The proportion of patients with residual contracture (≥5°) 2 years after surgery was 1/34 in group I, 4/30 in group II, 6/23 in group III, 6/6 in group IV, and 11/11 in group V. The results show that flexion contracture eventually existed if the contracture was more than 15° 3 months after surgery.

Changes in patellar alignment after total knee arthroplasty.

Although the results of total knee arthroplasty continue to improve, problems related to the patellofemoral joint remain significant. This study examined the factors affecting patellar alignment after total knee arthroplasty and subsequent changes in 56 knees during a postoperative period of 5.3 years. None of the knees examined displayed any clinical complications of the patellofemoral joint; no revision surgeries were necessary, with acceptable patellar alignment on average. The patellar resection angle had a strong influence on patellar alignment. Thinning of the patellar remnant on the medial side can increase postoperative lateral tilt, which leads to a need for lateral retinacular release. Although the changes in patellar alignment were minimal, the tendency that postoperative varus alignment resulted in patellar lateral tilt was observed. As postoperative femorotibial misalignment can lead to patellofemoral problems after total knee arthroplasty, surgeons need to pay scrupulous attention to femorotibial alignment and proper patellar preparation to decrease patellofemoral complications.

High-dose antibiotic infusion for infected knee prosthesis without implant removal.

BACKGROUND: Retention of a prosthesis represents an attractive surgical modality for the infected but well-fixed knee prosthesis because patients need to stay in bed after removal of all components. Some additional postoperative treatment would be needed, however, when treated only with débridement because of its low success rate. METHODS: In this study, intraarticular antibiotic infusion into the infected joints after débridement, while retaining the implants, was performed for six well-fixed total knee arthroplasties (TKAs), one revision TKA, and five tumor megaprostheses with an average follow-up period of 47.5 months (range 20-82 months). TKA patients with a polyethylene insert or those with all exchangeable components and all polyethylene parts in tumor megaprostheses underwent device removal and thorough débridement of the soft tissues. Subsequently, new polyethylene inserts were implanted in the TKA patients. The removed metallic prostheses were resterilized and reimplanted, and new polyethylene inserts were implanted in the tumor megaprostheses patients. The wound was closed in layers after insertion of a catheter percutaneously. The patients received organism-specific intraarticular antibiotics through the catheter twice a day until the infection disappeared clinically. RESULTS: There was no recurrence of infection in the TKA and revision TKA patients. Four of five knees treated with tumor megaprostheses exhibited recurrence of the infection. Infection was finally healed, however, in all cases by the same treatment procedure. CONCLUSIONS: Although some patients experienced recurrence of infection, successful implant salvage was achieved in all cases with the same treatment procedure. Patients do not need to stay in bed during this treatment. Therefore, this method should be considered as one of the treatment options for infected knee prostheses.

Mobile-bearing prosthesis did not improve mid-term clinical results of total knee arthroplasty.

A prospective study was performed to compare the clinical and radiological results of mobile- and fixed-bearing total knee arthroplasty with specific attention to rotational alignment and range of motion. Sixty-one knees were assigned to total knee arthroplasty with either the NexGen LPS Flex fixed-bearing or with the NexGen LPS Flex mobile-bearing prosthesis. Postoperatively, knees were compared with regard to range of motion, clinical score, and radiographic findings. Rotational alignment of the femoral and tibial components was evaluated by computed tomography. The median follow-up period was 5.9 years (range 2.1-8.8 years). Median postoperative Knee Society scores were 99 points (68-100) for the fixed-bearing group and 100 points (66-100) for the mobile-bearing group (n.s.). The median postoperative flexion angles of 120° (90°-150°) for the fixed-bearing group and 125° (90°-145°) for the mobile-bearing group were not significantly different from each other (n.s.). No knee required revision surgery due to wear of polyethylene or loosening of the component in either group. Computed tomography showed that 11 knees had rotational mismatches of more than 10° between the femoral and tibial components, but no significant difference was found in the postoperative extension and flexion angles or in the clinical score between the two treatment groups. Using the identical design for both fixed- and mobile-bearing prostheses, this prospective, randomized study did not show any clinical advantages of the mobile-bearing knee. Analysis of rotational alignment by CT scan did not reveal a particular advantage of the self-aligning mechanism of mobile-bearing implants.

Posterior displacement of the tibia increases in deep flexion of the knee.

BACKGROUND: Deep knee flexion is important to proper function for some activities and in some cultures, although there are large posterior forces during high knee flexion. Most of what we know about posterior restraint and stability, however, has not been determined from deep flexion and without distinguishing motion in the medial and lateral compartments. QUESTIONS/PURPOSES: We therefore evaluated (1) the difference in posterior displacement between the medial and lateral compartments at a commonly used flexion angle of 90 degrees ; (2) that of deeply flexed knees at 135 degrees ; and (3) the difference in kinematics in the medial and lateral compartments. We analyzed posterior stability in 21 normal knees using interventional open magnetic resonance imaging (MRI) system. RESULTS: When manual posterior stress was applied, the posterior displacements of the tibia were 0.6 mm/2.1 mm (medial/lateral) at 90 degrees and 0.6 mm/3.6 mm at 135 degrees . The posterior aspect of the femoral medial condyle moved 7.5 mm anteriorly with knee flexion, whereas the lateral condyle moved 1.3 mm anteriorly. The contact point of the lateral compartment moved 9.2 mm posteriorly with knee flexion, whereas the contact point of the medial compartment moved 2.3 mm anteriorly. CONCLUSIONS: Posterior displacement was larger in the lateral compartment at both flexion angles with manual posterior stress. As the knees flexed from 90 degrees to 135 degrees , posterior displacement became larger in the lateral compartment. CLINICAL RELEVANCE: Cruciate-retaining total knee arthroplasty (TKA) or posterior cruciate ligament (PCL) reconstruction surgery should aim to achieve stability on the medial side and a few millimeters of laxity at the lateral side at 90 degrees flexion with increasing laxity only on the lateral side in deep flexion.

Accuracy of image-free navigation for severely deformed knees.

This study evaluated the accuracy of an image-free navigated total knee arthroplasty (TKA) system when used to align deformed tibia bone models. The accuracy was assessed in normal, 10 degrees varus, 20 degrees varus, 10 degrees valgus, and 20 degrees valgus tibia bone models (a total of five tibial models) by direct measurement of the navigated cutting guide. The mean angular errors in the tibial mechanical axes of the normal, 10 degrees, and 20 degrees varus models, respectively, were 0.0 degree, 0.7 degree varus, and 2.4 degrees varus. Thus, the errors seen with the two varus models were significantly larger than that associated with the normal model. The mean angular errors were 0.1 degree varus and 0.4 degree valgus in the 10 degrees and 20 degrees valgus models, respectively. These errors were not significantly different from those obtained with the normal model. These results suggest that in varus-deformed knees, image-free navigation has a tendency to cut the tibia in varus. This fact is considered to be one of the reasons for the lack of superiority of TKA alignment in severely deformed knees when using image-free navigation. Therefore, special attention must be paid when using image-free navigation TKA in such cases.

Short-term results of microendoscopic posterior decompression for lumbar spinal stenosis. Technical note.

OBJECT: The authors applied the technique of microendoscopic discectomy to posterior decompression procedures for lumbar spinal stenosis. The purpose of this study was to determine the feasibility of using an endoscopic technique to treat lumbar spinal stenosis and to evaluate the clinical and radiographic results of microendoscopic posterior decompression (MEPD). METHODS: Microendoscopic posterior decompression, which involves a unilateral endoscopic approach for bilateral decompression, was performed in 47 patients. Clinical and radiographic/neuroimaging results were evaluated during the follow-up period (minimum duration 1 year). The clinical results were compared with those of the conventional laminotomy. Radiographic instability and the degree of surgical invasion of the facet joints were evaluated. In a control a group of 29 patients open laminotomy was performed. The clinical outcome was evaluated in 44 patients. The mean follow-up duration was 22 months. The mean rate of improvement was 72% based on the Japanese Orthopaedic Association score, and good results were obtained in 38 patients. Although the rate of morbidity decreased in the MEPD group, the incidence of complication was slightly higher. Effective decompression was demonstrated in the majority of the patients by using magnetic resonance imaging. Radiographic instability appeared in one patient postoperatively, and based on computerized tomography scanning, a tendency toward invasion of the facet joint on the approach side was noted. CONCLUSIONS: Microendoscopic posterior decompression is a minimally invasive procedure and is as useful as other conventional procedures in treating lumbar spinal stenosis; however, a few technical problems remain to be solved.