Varus Valgus Research Articles

Intraoperative evaluation of total knee replacement: kinematic assessment with a navigation system

Interest in the kinematics of reconstructed knees has increased since it was shown that the alteration of knee motion could lead to abnormal wear and damage to soft tissues. We performed intraoperative kinematic measurements using a navigation system to study knee kinematics before and after posterior substituting rotating platform total knee arthroplasty (TKA). We verified intraoperatively (1) if varus/valgus (VV) laxity and anterior/posterior (AP) laxity were restored after TKA; (2) if TKA induced abnormal femoral rollback; and (3) how tibial axial rotation was influenced by TKA throughout the range of flexion. We found that TKA improved alignment in preoperative osteoarthritic varus knees which became neutral after surgery and maintained a neutral alignment in neutral knees. The VV stability at 0 degrees was restored while AP laxity at 90 degrees significantly increased after TKA. Following TKA, the femur had an abnormal anterior translation up to 60 degrees of flexion, followed by a small rollback of 12 +/- 5 mm. TKA influenced the tibia rotation pattern during flexion, but not the total amount of internal/external rotation throughout whole range of flexion, which was preserved after TKA (6 degrees +/- 5 degrees ). This study showed that the protocol proposed might be useful to adjust knee stability at time zero and that knee kinematic outcome during total knee replacement can be monitored by a navigation system.

Femoral neck fracture following hip resurfacing

A total of 20 pairs of fresh-frozen cadaver femurs were assigned to four alignment groups consisting of relative varus (10 degrees and 20 degrees) and relative valgus (10 degrees and 20 degrees), 75 composite femurs of two neck geometries were also used. In both the cadaver and the composite femurs, placing the component in 20 degrees of valgus resulted in a significant increase in load to failure. Placing the component in 10 degrees of valgus had no appreciable effect on increasing the load to failure except in the composite femurs with varus native femoral necks. Specimens in 10 degrees of varus were significantly weaker than the neutrally-aligned specimens. The results suggest that retention of the intact proximal femoral strength occurs at an implant angulation of > or = 142 degrees . However, the benefit of extreme valgus alignment may be outweighed in clinical practice by the risk of superior femoral neck notching, which was avoided in this study.

Varus–valgus laxity correlates with pain in osteoarthritis of the knee

Pain during osteoarthritis (OA) of the knee does not necessarily correlate with the severity of the radiographic grade, and the mechanism of pain has not been completely clarified. The purpose of this study was to evaluate risk factors for pain in the knee OA using epidemiologic analyses. We evaluated 518 out of 4183 people over the age of 40 (156 males and 362 females) from Shinyoshitomi village, Japan. Mean ages were 63.8 years for men and 60.7 years for women. Screening included a physical examination of the knee and a standing AP roentgenogram of the bilateral knee. Radiographic OA was defined as a Kellgren–Lawrence grade 2 or higher. All data were coded and pain risk factors were evaluated using a multiple logistic regression model. Radiographic OA was observed in 18.4% of men and 26% of women. Of these subjects with OA, 10.9% of men and 32.5% of women complained of knee pain. Seven factors—age, gender, BMI, radiographic grade, varus–valgus laxity, torque of quadriceps muscles, and varus–valgus alignment—were evaluated as potential risk factors for pain. A significant increase in the odds ratio was observed with varus–valgus laxity ( p = 0.005; odds ratio, 3.04). Our results suggest that varus–valgus laxity is a risk factor for pain during knee OA.

Accuracy, Reliability, and Repeatability of Navigation Systems in Clinical Practice

Navigation in orthopedic surgery is now a widely accepted technique for the measurement of in vivo knee kinematics and has been proposed to possibly improve final outcome during surgery. In vivo results of navigated kinematic tests during surgery are affected by external factors, such as surgeon-subjective variability, limb positioning, and patient-specific laxity. The purpose of this study was to assess the reliability of navigation technology to assess knee laxities during an in vivo setup and to evaluate intraobserver reliability and interobserver repeatability. Intraoperative evaluation was performed on more than 70 consecutive anterior cruciate ligament surgical reconstructions. Intratester reliability and intertester repeatability were evaluated by correlating the results of repeated tests of antero-posterior translation, varus–valgus and internal–external rotations. Percentage standard error, the α-Crombach test, and interclass correlation (ICC) were used to estimate the measurement variability. The results showed repeatability on anteroposterior translation (1.2-mm repeatability) and good correlation (ICC > 0.60). Repeatability of Varus–valgus rotation was 0.9° (ICC > 0.46) in knees with small laxities, and repeatability of internal–external rotation was 2.4° (ICC > 0.72). Navigation systems have shown to be reliable, complete, and objective in intraoperative kinematic evaluations.

ELBOW LOAD DURING DIFFERENT TYPES OF BENCH-PRESS EXERCISE

The bench press is one of the most popular weight training open-kinetic chain exercise (OKCE) for the upper extremity. Reviewing the literature, there is a very little research regarding the biomechanical analysis of the OKCE of the upper extremity. The purpose of this study is to develop an OKCE testing model of the upper extremity by using the 3D Motion Analysis System. Furthermore, elbow joint loading of two different hand grip position during the bench-press exercise will be investigated. Thirteen male students volunteered for the study. Their average age was 26.1 years, with an average height of 170.6 cm, and an average weight of 70.3 kg. With both hands in neutral position, each subject was asked to perform bench-press type 1 (normal shoulder width), and bench-press type 2 (150% shoulder width). During the type 2 bench-press exercise, there is a significant increase in anterior–posterior and medial–lateral force on the elbow joint loading than the type 1 bench-press exercise. The valgus–varus, flexion–extension moment, and supination–pronation moment of the type 2 bench-press exercise are also greater than the type 1 bench-press exercise. As shown in this study, keeping the distance of both hand grips as shoulder width may reduce the elbow joint loading during bench-press exercise. These data will provide helpful information in clinical rehabilitation and treatment of the upper-extremity injures.

Erfahrung mit der PAUWELS-Osteotomie und ihre Weiterentwicklung in den letzten 20 Jahren

Intertrochanteric osteotomies (Pauwels) were performed in 203 hips. Their average age at operation was 41 years (range 15 to 66 years). Average follow-up was 16 years and 5 months. 78 of 203 hips had been undergone varus osteotomies (P1) and valgus osteotomies (P2) were in 125 hips. All the hips were evaluated clinically and radiologically. 140 hips (69%) had no pain. 132 hips (65%) showed no arthritic changes. In summary, we feel that Pauwels' osteotomy is a reliable method in the treatment of the young and middle aged patient.

Influences of hip external rotation strength on knee mechanics during single-leg drop landings in females

Background To determine the influence of hip external rotation strength on kinematic and kinetic variables during single-leg drop landings. Methods Females were divided into strong and weak groups based on isometric hip external rotation strength and lower extremity flexion–extension and varus–valgus kinematics and kinetics were evaluated during single-legged 40 cm drop landings. Findings Hip external rotation strength had no effect on sagittal or frontal plane angular motion throughout the landing cycle at the hip and knee. The strong group generated a statistically significant decrease in the peak vertical ground reaction force and external knee flexor moment. The weak group produced a greater external knee adduction moment, net knee anterior shear joint reaction force, and a greater hip external adduction moment. Interpretation Subjects with greater hip and quadriceps/hamstring strength exhibited a significant decrease in the vertical ground reaction force and external knee adduction and flexor moments. Hip and knee strength appear to relate to differences in high risk landing strategies.

Nutritional factors affecting poultry bone health

Outlined are two main current research concerns relating to skeletal disorders in poultry: (a) osteoporosis in egg-laying hens; (b) leg problems caused by rapid bone growth in broiler chickens. Surveys indicate that 30% of caged laying hens suffer at least one lifetime fracture (a severe welfare issue). Modern hybrids produce one egg per d for 50 weeks. For this period 'normal' bone turnover ceases; only medullary bone (MB) is formed, a woven bone type of limited structural value. MB is resorbed for eggshell formation alongside structural bone, leading to increased fracture risk. Avian osteoporosis is reduced by activity and genetic selection but nutrition is also important. Fluoride and vitamin K are beneficial but the timing of nutritional intervention is important. Ca, inorganic P and vitamin D must be adequate and the form of Ca is critical. Limestone fed as particulates benefits skeletal and eggshell quality. In hens fed particulate limestone compared with flour-fed hens the tibiotarsus breaking strength and radiographic density are increased at 56 weeks of age (P<0.01 and P<0.001 respectively) and the number of tartrate-resistant acid phosphatase-positive stained active osteoclasts (mean number per microscopic field) is decreased (P<0.001). In broiler (meat) chickens selection for rapid growth from approximately 50 g to 3 kg in 42 d has inadvertently produced skeletal disorders such as tibial dyschondroplasia, rickets and associated valgus-varus deformities leading to lameness. The beneficial skeletal effects during growth of increased dietary n-3 PUFA:n-6 PUFA (utilising salmon oil) have been demonstrated. Experiments simulating daylight UVB levels have produced beneficial skeletal effects in Ca- and vitamin D-deficient chicks.

Long-term results of basal wedge osteotomy in metatarsus primus varus in the young patient

Aim of this retrospective study was to analyse the long term results after basal closing wedge osteotomy for correction of metatarsus primus varus and hallux valgus in the younger patient. 49 patients (70 feet) were operated according to a basal closing wedge osteotomy from 1974 to 1985 at our institution. Age was under 40 years in all patients at the time of surgery. 34 patients (50 feet) were evaluated in respect to their clinical and 26 patients (37 feet) to their radiological outcome. The average age was 26 years (14-39 years). The follow-up was 12 to 22 years (Median: 18 years). Analysis was performed using the patient's record, weight-bearing X-rays, a standardized questionnaire and clinical investigation. 82% of the patients had very good and good subjective results. Cosmetics was rated very good and good in 78%, 88% of the patients were painfree. Radiological analysis at follow-up: Hallux valgus-angle 19,3 degrees, intermetatarsal I/II-angle 6 degrees, shortening of first metatarsale 5 mm, at average; dorsal elevation of first metatarsale 38%, degenerative arthritis of the metatarsocuneiforme joint 19%, congruency of first metatarsophalangeal joint 54%,sesamoid subluxation: 46% grade 0, 30% grade I, 14% grade II and 10% grade III. In 14 feet (28%) metatarsalgia was found. The basal closing wedge osteotomy is rather a technically demanding procedure conjuncted with a higher risk of failure. Satisfactory long term results can be obtained by an ideal operating technique. As undesirable side effects shortening of the first ray and dorsal malangulation of the first metatarsale may occur consecutively leading to metatarsalgia. Lower risk procedures like the crescentic osteotomy according to Mann or chevron osteotomy should be preferred.

Mechanical factors relate to pain in knee osteoarthritis

Background Pain experienced by people with knee osteoarthritis is related to psychosocial factors and damage to articular tissues and/or the pain pathway itself. Mechanical factors have been speculated to trigger this pain experience; yet mechanics have not been identified as a source of pain in this population. The purpose of this study was to identify whether mechanics could explain variance in pain intensity in people with knee osteoarthritis. Methods Data from 53 participants with physician-diagnosed knee osteoarthritis (mean age = 68.5 years; standard deviation = 8.6 years) were analyzed. Pain intensity was reported on the Western Ontario and McMaster Universities Osteoarthritis Index. Mechanical measures included weight-bearing varus–valgus alignment, body mass index and isokinetic quadriceps torque. Gait analysis captured the range of adduction–abduction angle, range of flexion–extension angle and external knee adduction moment during level walking. Findings Pain intensity was significantly related to the dynamic range of flexion–extension during gait and body mass index. A total of 29% of the variance in pain intensity was explained by mechanical variables. The range of flexion–extension explained 18% of variance in pain intensity. Body mass index added 11% to the model. The knee adduction moment was unrelated to pain intensity. Interpretation The findings support that mechanical factors are related to knee osteoarthritis pain. Because limitations in flexion–extension range of motion and body size are modifiable factors, future research could examine whether interventions targeting these mechanics would facilitate pain management.

The Modified Lapidus Procedure

This technique provides a powerful and durable correction of metatarsus primus varus and hallux valgus, and careful attention to detail should help in acheiving a successful outcome while avoiding complications.

Computational assessment of constraint in total knee replacement

Anterior–posterior (AP) and internal–external (IE) rotational constraint of total knee replacement (TKR) components is frequently assessed experimentally in a multi-axis loading machine. This constraint is of clinical interest because it represents the contribution of the implants to passive joint constraint following surgery. A standard has been published to establish a uniform protocol of constraint testing (American Society of Testing and Materials (ASTM) International, 2005; Designation: F 1223-05. Standard Test Method for Determination of Total Knee Replacement). In the present study a dynamic computer simulation of a posterior-substituting TKR design undergoing an AP and IE range of constraint test was developed and tested. Implant surfaces in the simulation were specified based on the manufacturer's CAD representations, and contact between implants was computed using a rigid-body-spring-model formulation. Predictions of constraint force compared favorably to experimental values when the compliance of the testing frame was modeled. The simulated constraint test was then used to evaluate the selective locking of secondary degrees of freedom (motions other than AP displacement and IE rotation) during constraint testing. The published ASTM standard does not clearly define either the design of the testing machine to accommodate secondary motions or which coupled motions should be allowed. Predicted component constraint for a posterior cruciate-retaining TKR design was sensitive to both varus–valgus joint location and the combinations of allowed secondary motions. Computational prediction of implant constraint can expedite the design cycle and allow an objective comparison between TKR components tested in different locations.

Effect of ski boot settings on tibio-femoral abduction and rotation during standing and simulated skiing

Ski boots are designed to transfer high forces from the skier to the ski. For this purpose they are made of stiff materials and constrain the leg of the skier to an unnatural position. To overcome the problem of unnatural knee posture, the ski boots can be adjusted in the frontal plane as well as in the horizontal plane by the canting mechanism and the “v-position”, respectively. Canting enables lateral and medial orientation of the shaft with respect to the base of the boot. The “v-position” is a pronounced outward rotation of the boot's base with respect to the ski's long axis. The purpose of this study is to investigate the effect of different foot rotations and ski boot canting settings on knee kinematics during standing and simulated skiing. Knee kinematics was measured by means of motion analysis and with the help of skin-mounted markers on 20 subjects. The ski boots in their standard settings significantly constrained the skier to an unnatural valgus position. Ski boot base rotation had a significant effect on internal external knee rotation, whereas canting had an effect on varus–valgus angles during standing. However, for the simulated skiing position no effects were observed. The study suggests that the constraints of the ski boots result in a clinically relevant valgus misalignment. Canting settings reduced the misalignment but only by about 10%. Increased ski boot canting settings would therefore be desirable. Knee kinematics showed that rotational misalignment could not be linked to any significant increase in injury risk.

Arthrodesis of the first metatarsophalangeal joint with convex and concave drills

The arthrodesis of the metatarsophalangeal joint of the hallux remains a reliable method in the treatment of the severe deformities caused by rheumatoid affection, recurrences of hallux valgus, iatrogenic varus and arthrosic hallux valgus (hallux rigidus). This operation is not crippling since the talocrural and interpahalangeal joints are preserved. The technique using a set of concentric drills allows a better positioning of the great toe, however it seems to generate a higher partial fusion rate but without repercussions on the final functional result.

In vivo knee laxity in flexion and extension: A radiographic study in 30 older healthy subjects

In order to determine how “tight” a total knee prosthesis should be implanted, it is important to know the amount of laxity in a healthy knee. The objective of this study was to determine knee laxity in extension and flexion in healthy, non-arthritic knees of subjects similar in age to patients undergoing a total knee arthroplasty and to provide guidelines for the orthopaedic surgeon in his attempt to restore the stability of an osteoarthritic knee to normal. Thirty healthy subjects (15 male, 15 female), mean age 62 (SD 6.4) years, were included in the study. For each subject one, randomly selected, knee was stressed in extension and in 70° flexion (15 Nm). Varus and valgus laxity were measured on radiographs. The passive range of motion and active flexion was assessed. Mean valgus laxity in extension was 2.3° (SD 0.9, range 0.2°–4.1°). In extension mean varus laxity was 2.8° (SD 1.3, range 0.6°–5.4°). In flexion, mean valgus laxity was 2.5° (SD 1.5, range 0.0°–6.0°) and mean varus laxity was 3.1° (SD 2.0, range 0.1°–7.0°). Varus and valgus knee laxity in extension and in flexion were comparable. This study shows that the normal knee in this age group has an inherent degree of varus–valgus laxity. Whether the results of the present study can be used to optimise the total knee arthroplasty implantation technique requires further investigation.

Sensitivity of tibio-menisco-femoral joint contact behavior to variations in knee kinematics

Use of computational models with kinematic boundary conditions to study the knee joint contact behavior for normal and pathologic knee joints depends on an understanding of the impacts of kinematic uncertainty. We studied the sensitivities of tibio-menisco-femoral joint contact behavior to variations in knee kinematics using a finite element model (FEM) with geometry and kinematic boundary conditions derived from sequences of magnetic resonance (MR) images. The MR images were taken before and after axial compression was applied to the knee joint of a healthy subject. A design of experiments approach was used to study the impact of the variation in knee kinematics on the contact outputs. We also explored the feasibility of using supplementary hip images to improve the accuracy of knee kinematics. Variations in knee kinematics (0.25 mm in medial–lateral, 0.1 mm in anterior–posterior and superior–inferior translations, and 0.1° in flexion–extension and varus–valgus, 0.25° in external–internal rotations) caused large variations in joint contact behavior. When kinematic boundary conditions resulted in close approximations of the model-predicted joint contact force to the applied force, variations in predictions of contact parameters were also reduced. The combination of inferior–superior and medial–lateral translations accounted for over 70% of variations for all the contact parameters examined. The inclusion of hip images in kinematic calculations improved knee kinematics by matching the femoral head position. Our findings demonstrate the importance of improving the accuracy and precision of knee kinematic measurements, especially when utilized as an input for finite element models.

Knee varus–valgus motion during gait – a measure of joint stability in patients with osteoarthritis?

To determine the validity of varus-valgus motion as a measure of knee joint stability by establishing the relationship of varus-valgus motion with muscle strength, joint proprioception, joint laxity and skeletal alignment in patients with knee osteoarthritis (OA). Sixty-three patients with OA of the knee were tested. Varus-valgus motion was determined with a video-based optoelectronic gait analysis system. Muscle strength was measured using a computer-driven isokinetic dynamometer. Proprioceptive acuity was assessed by establishing the joint motion detection threshold in the anterior-posterior direction. Laxity was assessed using a device which measures the passive angular deviation of the knee in the frontal plane. Alignment was assessed using a goniometer. Regression analyses were performed to assess the relationship between varus-valgus motion, muscle strength, joint proprioception, joint laxity and skeletal alignment. Varus-valgus motion was not related to muscle strength, joint proprioception, joint laxity and skeletal alignment. Knee joint stability cannot be measured as varus-valgus motion. Rather, a number of independent factors seem to contribute to the process of stabilization of the knee joint.

Arthrodesis of the first metatarso-phalangeal joint with convex and concave drills

The arthrodesis of the metatarso-phalangeal joint of the hallux remains a reliable method in the treatment of the severe deformities caused by rheumatoid affection, recurrences of hallux valgus, iatrogenic varus and arthrosic hallux valgus (hallux rigidus). This operation is not crippling since the talocrural and interpahalangeal joints are preserved. The technique using a set of concentric drills allows a better positioning of the great toe, however it seems to generate a higher partial fusion rate but without repercussions on the final functional result. The metatarso-phalangeal arthrodesis of the great toe is a tried-and-tested method described by Groulier et al. [1]. A certain number of studies, mostly Anglo-Saxon, report it as early as the end of last century. Its merits have been gradually emphasized for the revisions or to treat the severe deformities of the great toe, either with arthrosis complications, painful stiffening or metatarsalgiae. The arthrodesis of the metatarso-phalangeal of the hallux was first stated in 1894 as a successful treatment, achieving good and stable results in case of severe hallux valgus. Varied techniques of arthrodesis of the metatarso-phalangeal of the hallux have been described and 60 different types have been listed.

Varus–valgus motion and functional ability in patients with knee osteoarthritis

Objective:To assess the relationship between knee varus–valgus motion and functional ability, and the impact of knee varus–valgus motion on the relationship between muscle strength and functional ability in patients with...

Investigation into the effect of varus–valgus orientation on load transfer in the resurfaced femoral head: A multi-femur finite element analysis

Femoral head resurfacing is a popular procedure for younger active hip replacement patients. Whilst the current generation of metal-on-metal resurfacing arthroplasties appear to have cured the osteolysis problems that plagued earlier resurfacing implants, fracture of the femoral head and aseptic loosening are still factors of concern in its survivorship. Several studies have shown a tendency towards failure in resurfaced femurs where the implant has been set at a varus angle. This work aims to investigate the influence of varus-valgus orientation on load transfer within the resurfaced proximal femur. This study uses Computer Tomography based finite element analysis to determine the effect of implant orientation on load transfer in the proximal femur with respect to the intact femur. A group of 16 femurs were studied to take into account inter-patient variation; four models were produced for each femur, one of the intact femur, one resurfaced with the implant set inline with the femoral neck and one each representing varus and valgus implant alignment. Results showed the valgus aligned resurfaced femur to produce strain patterns more akin to the intact femur. As the implant's angle to the femoral shaft increases from varus to valgus the strains in the superior femoral neck are reduced while those in the inferior neck are increased. The study concluded that valgus alignment of the resurfacing arthroplasty is preferential to varus alignment; as it induces a more physiological strain pattern and reduces the risk of femoral neck fracture. These findings are in line with clinical experience, which has shown an increase of failure with varus implanted prostheses.