Rasterstereographic Analysis of Lateral Shift in Patients with Lumbar Disc Herniation: A Case Control Study.

OBJECTIVE: Detection of a lateral shift (LS) in patients with diagnosed disc herniation compared to healthy controls. SUMMARY OF BACKGROUND DATA: A specific lateral shift (LS) pattern is observed in patients with disc herniation and low back pain, as shown in earlier studies. METHODS: Rasterstereography (RS) was used to investigate the LS. Thirty-nine patients with lumbar disc herniation diagnosed by radiological assessment and low back pain and/or leg pain (mean age 48.2 years, mean BMI 28.5, 28 males and 11 females) and 36 healthy controls (mean age 47.4 years, mean BMI 25.7, 25 males and 11 females) were analysed. LS, pelvic tilt, pelvic inclination, lordotic angle, and trunk torsion were assessed. RESULTS: The patient group showed a nonsignificant increase in LS, that is, 5.6 mm compared to the healthy controls with 5.0 mm (p = 0.693). However, significant differences were found between groups regarding pelvic tilt in degrees (patients 5.9°, healthy controls 2.0°; p = 0.016), trunk torsion (patients 7.5°, controls 4.5°; p = 0.017), and lordotic angle (patients 27.5°, healthy controls 32.7°; p = 0.022). The correlation between pain intensity and the FFbH-R amounted 0.804 (p = < 0.01), and that between pain intensity and the pain disability index was 0.785 (p < 0.01). DISCUSSION: Although some studies have illustrated LS with disc herniation and low back pain, the present findings demonstrate no significant increase in LS in the patient group compared to healthy controls. CONCLUSION: The patients with lumbar disc herniation did not demonstrate an increased LS compared to healthy controls. Other parameters like pelvic tilt and inclination seemed to be more suitable to identify changes in posture measured by RS in patients with low back pain or disc herniation.

Bilateral Scapulothoracic Osteochondromas in a Patient With Hereditary Multiple Exostosis: A Case Report and Review of the Literature.

Hereditary multiple exostosis (HME) is an autosomal dominant disorder characterized by two or more benign growing, cartilage capped tumors of long bones called osteochondromas. If abnormal growth and clinical symptoms of osteochondromas newly appear in adults, malignant transformation of the usually benign growing tumors should be suspected and diagnostic testing should be initiated. Against the background of hypothesized higher malignant transformation of osteochondromas into chondrosarcoma in individuals with shoulder exostoses, we report a case of bilateral scapulothoracic osteochondromas in a patient suffering from HME. A 60-year-old female with HME complained of chest pain while being hospitalized for bilateral femoral fractures. A computed tomography scan of the chest was performed to rule out pulmonary embolism. However, bilateral osteochondromas in the scapulothoracic spaces were detected. Due to absence of radiographic evidences for malignant transformation in the patient, invasive diagnostic procedures such as biopsy and histological examination were recommended in order to exclude malignant transformation of both osteochondromas. Physicians should be aware that patients with HME who present with shoulder pain should be examined for osteochondromas in the scapulothoracic space. Due to possible sarcomatous transformation, regular follow-ups are necessary for adolescents and adults.

Initial stability of a new cementless fixation method of a tibial component with polyaxial locking screws: a biomechanical in vitro examination.

INTRODUCTION: Cementless fixation of the tibial component is critical as reduced initial stability leads to implant failure. In this experimental in vitro study, a new fixation method of the tibial component using polyaxial locking screws is evaluated using Roentgen stereophotogrammetric analysis (RSA). MATERIALS AND METHODS: A special prototype of a tibial component with four polyaxial locking screws was tested on 10 fresh-frozen human tibia specimens. The components were tested with an axial load of 2000 N for 10,000 cycles. Radiographs in two views were performed before loading, after 1000 and after 10,000 cycles, respectively. Besides rotation and translation along the x-, y-, and z-axes, endpoints for RSA were maximum subsidence (MaxSub), maximum lift off (MaxLiftOff) and maximum total point motion (MTPM). RESULTS: MaxSub increased from -0.5 mm (SD = 0.2) after 1000 cycles to -0.9 mm (SD = 1.1). MaxLiftOff was 0.1 mm after 1000 cycles and did not increase after 10,000 cycles. The MTPM was 0.7 mm (SD = 0.3) after 1000 cycles and 1.1 mm (SD = 1.1) after 10,000 cycles. Two out of nine implants showed an MTPM ≥ 1.0 mm after 10,000 cycles. CONCLUSIONS: Polyaxial locking screws can potentially improve the initial stability of tibial components. The results of this study indicate that the use of such screws in total knee arthroplasty may be of interest in the future. Further experimental and clinical investigation is needed.

Influence of a Training Session on Postural Stability and Foot Loading Patterns in Soccer Players.

Sport specific movements coming along with characteristic plantar pressure distribution and a fatigue of muscles result in an increasing postural sway and therefore lead to a decrease in balance control. Although single soccer specific movements were expatiated with respect to these parameters, no information is available for a complete training session. The objective of the present observational study was to analyze the direct influence of soccer training on postural stability and gait patterns and whether or not these outcomes were altered by age. One hundred and eighteen experienced soccer players participated in the study and were divided into two groups. Group 1 contained 64 soccer players (age 13.31±0.66 years) and Group 2 contains 54 ones (age 16.74±0.73 years). Postural stability, static plantar pressure distribution and dynamic foot loading patterns were measured. Our results showed that the soccer training session, as well as the age, has relevant influence on postural stability, while the age only (excluding the training) has an influence on static plantar pressure distribution. The parameters of dynamic assessment seem therefore to be affected by age, training and a combination of both. Training and young age correlate with a decreased postural stability; they lead to a significant increase of peak pressure in the previously most loaded areas, and, after reaching a certain age and magnitude of absolute values, to a change in terminal stance and preswing phase of the roll-over. Moreover, younger players show an inhomogenous static plantar pressure distribution which might be the result of the decreased postural control in the young age.

Role of Electrochemically Activated Solution in Asepsis in Osteoblasts and Chondrocytes in vitro.

PURPOSE: Implant infections are severe complications in orthopedic surgery. Treatment using antibiotics is often unsuccessful without removing the implant due to biofilm formation. In this context, antiseptics may be a potential option. These solutions have a wide antimicrobial spectrum but often cause damage to the local cell populations. In these cases, electrochemically activated solutions (ECAS) may be an alternative. METHODS: Staphylococcus aureus was cultured overnight on polyethylene platelets under different growing conditions (standard-/-different biofilm inducing conditions). The samples were treated with an ECAS (0%-30%) and analyzed with regard to their antimicrobial efficacy and their effect on biofilm structures by determining the living bacterial count and scanning electron microscopy. Osteoblast and chondrocyte cell lines (MG-63, and CAL-78, respectively) were cultured to confluence and treated with an ECAS. Total cell count, metabolic activity using FDA staining, and proliferation using Ki67 staining were analyzed. RESULTS: ECAS showed antimicrobial activity in concentrations <1%. In cases of biofilm formation, bacterial toxicity could be detected at concentrations from 3.75 -7.5%. At these same concentrations, a visible change in biofilm structure was observed. Regarding biocompatibility rates, up to 7.5% (of osteoblasts) and 3.75% (of chondrocytes) had little influence on metabolic activity and proliferation. CONCLUSION: ECAS provide good antimicrobial efficacy while maintaining high biocompatibility. These results suggest that these solutions may provide promising alternatives in the treatment of implant-associated infections.

The Validity of Rasterstereography: A Systematic Review.

To investigate and monitor the progression of scoliosis and other spinal deformities in patients following idiopathic scoliosis (IS), non-invasive and radiation-free techniques are recommended because of the need for repeated radiographs. In a clinical setting, spine parameters can be quickly, cheaply and easily assessed using rasterstereography (RS). To assess the validity of the radiation-free technique RS based on surface topography compared with radiographs. MEDLINE, the Cochrane Library and EMBASE were systematically searched for studies which investigate the validity of rasterstereography compared with x-ray measurements. Studies published between January 1, 1990 and July 31, 2013 in English, German and French were included. Studies dealing with magnetic resonance imaging were excluded. Twelve studies with 570 patients were included; these articles were published between 1990 and 2013. The majority of studies investigated patients with IS, but other spinal pathologies included were thoracic hyperkyphosis and Scheuermann's disease. With regard to the quality assessment criteria for the included studies, three out of twelve studies were evaluated using a twelve point scale and two used a scale with eleven points. We conclude that RS facilitates clinical practice by analysing the spinal column. It is completely radiation-free and could help to monitor scoliosis progression.

Rasterstereographic evaluation of interobserver and intraobserver reliability in postsurgical adolescent idiopathic scoliosis patients.

STUDY DESIGN: Evaluation of rasterstereographic examinations in postsurgical adolescent scoliosis patients: a reliability study. OBJECTIVE: To investigate the interobserver and intraobserver reliability of rasterstereographic 3-dimensional back surface analysis and reconstruction of spine parameters including trunk length, trunk inclination, lateral deviation, kyphotic and lordotic angles in adolescent idiopathic scoliosis patients after scoliosis surgery. SUMMARY OF BACKGROUND DATA: The rasterstereography device formetric III 4D has been in routine clinical use for patients with scoliosis and other spinal deformities, reducing the patients' radiation exposure considerably. The reliability of this device has previously been examined in healthy volunteers but not in patients after scoliosis surgery. MATERIALS AND METHODS: Thirty-nine adolescent idiopathic scoliosis patients (32 women and 7 men) after scoliosis surgery with a mean age of 23.5 years (±10.6 y) were examined rasterstereographically by 5 investigators. Each investigator made a series of 3 measurements of each participating patient consecutively. The intraclass correlation coefficient (ICC) and the Pearson product moment correlation were calculated. In addition, the comparative analysis of the first and 15th measurements was assessed. RESULTS: The ICCs of all investigated parameters demonstrated very high interobserver and intraobserver reliability. The maximum ICC (0.988) for interobserver reliability of the 5 investigators was found for the trunk length and the minimum ICC (0.918) for lateral deviation. There were highly significant positive correlations between the first, second, and third measurements (r=0.994-0.697; P<0.001) for intraobserver reliability. Overall highly significant correlation was found comparing the results of the first and the 15th rasterstereographic measurement. CONCLUSIONS: The reliability of rasterstereography formetric III 4D in regard to the investigated parameters is excellent. The device can be used very efficiently by 1 or multiple investigators to analyze postsurgical adolescent idiopathic scoliosis patients in clinical practice, requiring only a single investigational exposure.

Test-retest reliability of 3D ultrasound measurements of the thoracic spine.

OBJECTIVE: To explore the reliability of the Zebris CMS 20 ultrasound analysis system with pointer application for measuring end-range flexion, end-range extension, and neutral kyphosis angle of the thoracic spine. SETTING: The study was performed within the School of Physiotherapy in cooperation with the Orthopedic Department at a University Hospital. PARTICIPANTS: The thoracic spines of 28 healthy subjects were measured. METHODS: Measurements for neutral kyphosis angle, end-range flexion, and end-range extension were taken once at each time point. The bone landmarks were palpated by one examiner and marked with a pointer containing 2 transmitters using a frequency of 40 kHz. A third transmitter was fixed to the pelvis, and 3 microphones were used as receiver. The real angle was calculated by the software. Bland-Altman plots with 95% limits of agreement, intraclass correlations (ICC), standard deviations of mean measurements, and standard error of measurements were used for statistical analyses. The test-retest reliability in this study was measured within a 24-hour interval. MAIN OUTCOME MEASUREMENTS: Statistical parameters were used to judge reliability. RESULTS: The mean kyphosis angle was 44.8° with a standard deviation of 17.3° at the first measurement and a mean of 45.8° with a standard deviation of 16.2° the following day. The ICC was high at 0.95 for the neutral kyphosis angle, and the Bland-Altman 95% limits of agreement were within clinical acceptable margins. The ICC was 0.71 for end-range flexion and 0.34 for end-range extension, whereas the Bland-Altman 95% limits of agreement were wider than with the static measurement of kyphosis. Compared with static measurements, the analysis of motion with 3-dimensional ultrasound showed an increased standard deviation for test-retest measurements. CONCLUSIONS: The test-retest reliability of ultrasound measuring of the neutral kyphosis angle of the thoracic spine was demonstrated within 24 hours. Bland-Altman 95% limits of agreement and the standard deviation of differences did not appear to be clinically acceptable for measuring flexion and extension.

Highly conforming polyethylene inlays reduce the in vivo variability of knee joint kinematics after total knee arthroplasty.

The use of highly conforming polyethylene inlays in total knee arthroplasty (TKA) provides improved anteroposterior stability. The aim of this fluoroscopic study was to investigate the in vivo kinematics during unloaded and loaded active extension with a highly conforming inlay and a flat inlay after cruciate retaining (CR) total knee arthroplasty (TKA). Thirty one patients (50 knees) received a fixed-bearing cruciate retaining total knee arthroplasty (Genesis II, Smith & Nephew, Schenefeld, Germany) for primary knee osteoarthritis. Twenty two of them received a flat polyethylene inlay (PE), nine a deep dished PE and 19 were in the control group (physiological knees). The mean age at the time of surgery was 62 years. Dynamic examination with fluoroscopy was performed to assess the "patella tendon angle" in relation to the knee flexion angle (measure of anteroposterior translation) and the "kinematic index" (measure of reproducibility). Fluoroscopy was performed under active extension and flexion, during unloaded movement, and under full weight bearing, simulated by step climbing. No significant difference was observed between both types of polyethylene inlay designs and the physiological knee during unloaded movement. Anteroposterior (AP) instability was found during weight-bearing movement. The deep-dish inlay resulted in lower AP translation and a non-physiological rollback. Neither inlay types could restore physiological kinematics of the knee. Despite the fact that deep dished inlays reduce the AP translation, centralisation of contact pressure results in non-physiological rollback. The influence of kinematic pattern variability on clinical results warrants further investigation.

Initial stability of tibial components in primary knee arthroplasty. A cadaver study comparing cemented and cementless fixation techniques.

The purpose of this roentgen stereophotogrammetric analysis (RSA) study was to evaluate the initial stability of cemented and cementless tibial components in vitro. Twenty tibia specimens were matched into two groups. In the first group, the tibial trays were cemented superficially and in the second group cementless fixation with stem and screws was performed. An axial load of 2000 N for 1000 and 10,000 cycles was applied onto the specimens and RSA was performed. The experimental results after 1000 cycles showed a higher migration with significant differences for the parameters maximum lift off (p = 0.011) and maximum total point motion (p = 0.002) in the cementless group. After 10,000 cycles, the migration in the cementless group increased significantly for maximum lift off (p = 0.043), maximum subsidence (p = 0.045) and maximum total point motion (p = 0.013). The higher migration rates in the cementless group demonstrate a lower initial mechanical stability of cementless tibial components which can cause an early component loosening.

Gait analysis and electromyography in fixed- and mobile-bearing total knee replacement: a prospective, comparative study.

PURPOSE: The theoretical superiority of mobile-bearing total knee arthroplasties (TKAs) has not yet been proven in clinical studies. The aim of the current study was to compare and to analyse in a patient population that had received either a fixed or a mobile TKA differences in gait analysis electromyography and clinical scores. METHODS: In a prospective, randomized, patient- and observer-blinded clinical study, 33 patients with primary osteoarthritis of the knee were included. All patients received a Genesis II total knee replacement. Sixteen patients received a mobile and 17 a fixed-bearing cruciate retaining Genesis II TKA. Clinical and quality-of-life scores, electromyography and gait analysis were applied preoperatively and postoperatively with a follow-up of 24 months. RESULTS: In both groups, improvements from pre- to postoperative were detected. whereas the results of gait analysis and electromyography did not show any differences. The results from the clinical and the quality-of-life scores improved from pre- to postoperative, while the Knee Society Score showed a superiority of the mobile-bearing group (mean 159 ± 28) over the fixed-bearing group (mean 134 ± 41). CONCLUSION: No functional advantage of mobile over fixed-bearing TKA was detected, although the mobile-bearing group had better clinical results for which a reason could not be found. These results only apply to cruciate retaining mobile-bearing TKA with a bearing which allows both rotation and anteroposterior translation.

Sagittal plane kinematics of fixed- and mobile-bearing total knee replacements.

PURPOSE: The objective of this prospective, randomized, patient- and observer-blinded study was to analyze, in vivo, the knee joint kinematics in the sagittal plane in a patient population that had received either a fixed or a mobile TKA. METHODS: Thirty-one patients (57 knees) were evaluated by means of fluoroscopy during unloaded flexion and extension against gravity as well as during step up and step down with full weight bearing. In these 31 patients, 22 fixed-bearing TKAs, 16 mobile-bearing TKAs, and 19 natural knee joints were included. Fluoroscopic radiographs were evaluated by measuring the "patella tendon angle" in relation to the knee flexion angle, as a measure of anteroposterior translation, as well as the "kinematic index," as a measure of reproducibility. RESULTS: During unloaded movement, fluoroscopic analysis did not show a significant difference between both types of prosthesis design and the natural knee. In the weight-bearing movement, both types of TKA designs revealed a more linear patellar tendon angle curve, with a greater angle in extension and in flexion than in the natural knees. In the mobile-bearing group, interindividual deviations from the mean during weight-bearing movements were significantly less than in the fixed-bearing group. CONCLUSIONS: No functional advantage of mobile-bearing TKA over fixed-bearing devices could be found. Both TKA designs showed the typical kinematics of an anterior instability. These results only apply to cruciate retaining mobile-bearing TKA with a bearing that allows both rotation and anteroposterior translation, using a sagittal plane kinematics analysis evaluated by such methodology. A possible influence of less variability of the kinematic pattern on clinical results still needs to be confirmed.

Revision of tibial TKA components: bone loss is independent of cementing type and technique: an in vitro cadaver study.

BACKGROUND: Different bone cements and various cementation techniques can lead to different bone loss in revision surgery. We investigated the degree of tibial bone loss depending on different cements and techniques. METHODS: 30 tibia specimens were matched into three groups (10 each). In all cases Genesis II tibia component were implanted. In two groups, the tibia base plate alone was cemented with Palacos® R+G and Refobacin® Bone Cement R. In the third group, both tibial base plate and tibial stem were cemented with Palacos® R+G. Afterwards, the specimens were axial loaded with 2000 N for 10,000 cycles. Tibial components were explanted and the required time to explantation was recorded. Bone loss after explantation was measured by CT. RESULTS: On CT, there was no significant difference in bone loss between cementing techniques (p = 0.077; 95% CI -1.14 - 21.03) or the cements themselves (p = 0.345; 95% CI -6.05 - 16.70). The required time to explantation was 170.6 ± 54.89, 228.7 ± 84.5, and 145.7 ± 73.0 seconds in the first, second, and third groups, respectively. CONCLUSIONS: Cement technique and type do not influence tibial bone loss in simulated revision surgery of the tibial component in knee arthroplasty.

Reproducibility of rasterstereography for kyphotic and lordotic angles, trunk length, and trunk inclination: a reliability study.

STUDY DESIGN: Determination of reliability with 3 investigators using a collective of healthy volunteers. OBJECTIVE: To determine the reliability of rasterstereography 3-dimensional back surface analysis and reconstruction of the spine in healthy test subjects. SUMMARY OF BACKGROUND DATA: Rasterstereography has been in clinical use since 1989 for patients with scoliosis and other spinal deformities and it significantly reduces the need for otherwise indispensable radiographs. The validity of this device has previously been examined in other studies. This study was performed to evaluate the reliability of rasterstereography for clinical application in diagnostic and follow-up examinations. METHODS: Fifty-one healthy volunteers were examined rasterstereographically by 3 investigators. Each investigator made a series of 3 measurements of each participant in which 8 spine parameters including kyphotic angle ICT-ITL (max.), kyphotic angle VP-ITL, kyphotic angle VP-T12, lordotic angle ITL-ILS (max.), lordotic angle ITL-DM, lordotic angle T12-DM, trunk length VP-DM and trunk inclination were measured. Cronbach alpha was calculated. The influence of high or low body mass index on the accuracy of the technique was evaluated as well. RESULTS: Cronbach alpha for the intratester-reliability of the kyphotic angle ICT-ITL (max.) for the 3 investigators has values between 0.921 and 0.992. The intertester-reliability for the same parameter is 0.979 (95% CI). In this study group a meaningful association between body mass index and reliability of the device was not found. CONCLUSION: The reliability revealed very good results, both for intratester and for intertester reliability. The technique is well suited for analysis of the back in standing position. The body mass index has no influence on the reproducibility.

Decrease in the expression of the type 1 PTH/PTHrP receptor (PTH1R) on chondrocytes in animals with osteoarthritis.

BACKGROUND: To evaluate the expression of the type 1 PTH/PTHrP receptor (PTH1R) on chondrocytes from hyaline cartilage over the course of osteoarthritis (OA). METHODS: In 12 NZW rabbits, the anterior cruciate ligament (ACL) was resected to create anterior instability of the knee. In 12 control rabbits, only a sham operation, without resection of the ACL, was performed. Four animals from each group were killed at 3, 6, and 12 weeks. After opening the knee joint, OA was macroscopically graded and hyaline cartilage of the load-bearing area was evaluated histologically according to the Mankin scale and by immunostaining for PTH1R. RESULTS: There was a positive linear correlation between the time after surgery and the macroscopic and histologic OA scores. The scores in the control group were constant over the time course. Immunostaining showed significantly less expression of PTH1R in the experimental compared to the control group after 6 (P < 0.05) and 12 weeks (P < 0.01). In the experimental group, a negative linear correlation between PTH1R expression and macroscopic and histologic grades was found. CONCLUSIONS: The results show an in vivo decrease in the expression of PTH1R on chondrocytes over the time course of OA. Further studies are needed to evaluate whether new treatment approaches could evolve from this knowledge.

Plantar contact stress and gait analysis after resection of tarsal coalition.

The purpose of this study was to assess the foot loading characteristics and foot function of patients after operative correction of a tarsal coalition. Ten patients who had undergone operative treatment of a tarsal coalition were included in this study. One foot was affected in five patients and both feet in the other five. A calcaneonavicular coalition was present in 12 feet and a talocalcaneal coalition in three feet. Mean follow-up was 11.3 years. Clinical evaluation was based on a standardized questionnaire, a visual analogue scale for pain (VAS), the American Orthopaedic Foot and Ankle Society (AOFAS) Score and radiographic evaluation of the last radiographs. An objective analysis of foot loading characteristics was carried out with instrumented gait analysis and pedobarography. The clinical results were overall fair for pain, range of motion and walking distance. The AOFAS also showed fair results (mean: 78.1) at follow-up. Gait analysis revealed alterations in kinematic and kinetic parameters for the operated foot. Pedobarographic analysis showed altered loadings for heel and forefoot. In this study, operative treatment of tarsal coalition achieved fair clinical and radiographic results and did not restore physiologic gait and foot loading.

Primary stability of tibial components in TKA: in vitro comparison of two cementing techniques.

In spite of improvements in cementing technique, migration of tibial component remains a problem in total knee arthroplasty. This study compares the primary stability of tibial components using two different cementing techniques with roentgen stereophotogrammetric analysis (RSA) in vitro. A total of 20 tibia specimens were matched into two groups, 10 specimens per group. Cementing technique was randomized to each group. In the first group only the base and in the second group the base and stem were cemented. The implants and the tibial metaphysis were marked with markers for the RSA analysis. All specimens were tested with an axial load of 2,000 N for 1,000 and 10,000 cycles and RSA analysis was performed. Endpoints for radiosterometric analysis were maximum total point motion, maximum subsidence, lift off, rotation and translation along the x-, y-, and z-axes. After 1,000 and 10,000 cycles, no significant differences could be found, but two tibial components of the surface cementing group showed a migration of more than 2 mm defined as failure compared to six failed tibial components in the full cementing group (P = 0.068). This higher number of failed arthroplasties in the fully cemented prosthesis group demonstrates a disadvantageous load distribution in the tibia apophysis which can cause an early component loosening.

Changes of gait patterns and muscle activity after intraarticular treatment of patients with osteoarthritis of the knee: a prospective, randomised, doubleblind study.

Evaluation of gait performance and muscle activity patterns as well as clinical efficacy and safety after intraarticular injections with hyaluronan (Ostenil) compared with triamcinolone (Volon A10) injections in patients with knee osteoarthritis. This was a prospective, randomised, double-blind clinical trial evaluating the influence of five injections of hyaluronan or triamcinolone on gait pattern and muscle activity. For the clinical evaluation visual analogue scale, Lequesne index, and Knee Society Score were used. Quality of life was estimated with the SF-36. The definitive analysis was performed on the population who received all five injections and were examined in the two follow-up visits. Fifteen patients were treated with triamcinolone and 20 with hyaluronan. Significant improvement could be demonstrated for pain scale and clinical scores in both groups. Gait patterns showed significant differences only for Knee Abduction Moment (p=0.007) in the hyaluronan group and for Maximum Vertical Force 1 and 2 between the both groups in the follow up visit (p=0.018) (p=0.019). In both groups there was no significant difference regarding to muscle activity. Quality of life showed no changes in all visits between the groups. Hyaluronan was not superior to triamcinolone. The results suggest that treatment with hyaluronan can reduce pain and improve knee function. A significant short term improvement in gait and muscle activity patterns, however, was not observed, in either hyaluronan or triamcinolone.

Differences in patellofemoral contact stresses between mobile-bearing and fixed-bearing total knee arthroplasties: a dynamic in vitro measurement.

INTRODUCTION: Anterior knee pain is one of the most common problems after total knee arthroplasty (TKA). Mobile-bearing designs should improve patella tracking with a reduced rate of patella tilt as well as reduced patellofemoral contact stresses and improve knee flexion. The aim of this dynamic in vitro investigation was to evaluate the changes of patellofemoral contact stresses after TKA using fixed and mobile-bearing designs. MATERIALS AND METHODS: Seven knee specimens were mounted into a knee simulator imitating an isokinetic extension of the knee. The patellofemoral contact was measured before and after tricompartimental TKA with fixed and mobile-bearing designs using pressure-sensitive films. Contact stresses were measured from 120 degrees knee flexion to full extension with a simulated force of the quadriceps muscle up to 1,200 N. Additionally all measurements were performed with simulated co-contraction of the hamstrings muscles. RESULTS: Fixed-bearing TKA increases patellofemoral contact stresses compared to physiologic conditions. After patella resurfacing, contact stresses increase even more. By changing the prosthesis design to mobile bearing, maximum contact stress was measured to be punctual higher than in fixed-bearing implants. In the interval between 0 degrees -30 degrees and 70 degrees -105 degrees of flexion, obviously lower pressures were evaluated for the mobile-bearing design. With cocontraction of the hamstrings, a lower contact stress of the mobile-bearing design was evident for the complete measurement of the knee extension. CONCLUSION: An increase of patellofemoral contact stresses after patellar resurfacing in TKA could be demonstrated. This outcome implicates a higher risk of patellofemoral complications. The mobile-bearing design showed evidently lower patellofemoral contact stresses than the fixed-bearing design.

Poor mid-term results of total hip arthroplasty with use of a Hylamer liner.

Clinical results after total hip arthroplasty with the use of a Hylamer liner have been described as being poor. In this study, polyethylene wear rates as well as clinical results were assessed after hip arthroplasty using a Hylamer liner. Thirty patients were followed radiographically and clinically after total hip arthroplasty with a Hylamer liner. The mean follow-up was six years. Radiolucent lines and wear rates were evaluated in correlation to different parameters and clinical scores. Radiolucent zones were found in 40% of the femoral and 27% of the acetabular components. Wear rates showed no correlation to the clinical scores, nor to other parameters. The SF-36 questionnaire showed inferior results compared to healthy controls. These findings confirm the poor results described with Hylamer in current literature. A significant influence of the different patient or prosthesis specific parameters on the survival of the prosthesis could not be confirmed.