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PubMed2002

The influence of alignment on risk of knee osteoarthritis progression according to baseline stage of disease.

OBJECTIVE: Varus and valgus malalignment increase the risk of medial and lateral osteoarthritis (OA) progression, respectively. The impact of a mechanical factor such as alignment depends not only on the factor itself, but also on the state of the joint. The less-damaged joint of mild OA may be less vulnerable to malalignment effects than the more-damaged joint of moderate OA. Our goal was to explore the impact of alignment on subsequent progression of knee OA according to the baseline stage of disease. METHODS: Two hundred thirty patients with knee OA (defined by the presence of osteophytes and symptoms) recruited from the community underwent assessment of both lower limbs at baseline and at an 18-month followup. Alignment was measured on a full-limb radiograph as the angle made by the intersection of the femoral and tibial mechanical axes. Compartment-specific progression was defined as an increase between baseline and 18 months in the grade of severity of joint space narrowing on radiographs of semiflexed knees taken after fluoroscopic confirmation of position. Knees were grouped according to their baseline stage of OA as Kellgren/Lawrence (K/L) grades 0-1, 2, or 3. Progression odds ratios were estimated from logistic regression using generalized estimating equations. RESULTS: There were 377 K/L grade 0-3 knees in 230 subjects (173 women and 57 men, mean age 64.0 years, mean body mass index 30.4 kg/m(2)) in this longitudinal study. In knees with mild OA (K/L grade 2), the odds of 18-month progression in the medial compartment were significantly increased 4-fold by varus alignment at baseline. In K/L grade 2 knees, the odds of lateral progression were increased 2-fold by valgus alignment (approaching significance). In knees with moderate OA (K/L grade 3), the risk of progression was comparably increased by varus or valgus alignment (10-fold). CONCLUSION: While some effect of malalignment was suggested at almost all stages of knee OA examined, the impact of varus or valgus malalignment on the odds of OA progression over the ensuing 18 months was greater in knees with moderate (K/L grade 3) OA at baseline, possibly due to greater joint vulnerability with some contribution from slightly more severe malalignment.

Aged↗

PubMed1984

In vivo strain patterns in the four major canine knee ligaments.

Using mercury gauges, we measured strains in vivo in the four major ligaments of the canine knee joint as the tibia was loaded in valgus or varus at fixed angles of knee flexion. Free axial rotation of the tibia on the femur was allowed. Forces up to 78.4 N were applied to the tibia, producing moments of approximately 9 N-m. We found that with valgus loading, significant strains were observed in the medial collateral ligament at extension. At 45 degrees of flexion, the medial collateral, posterior cruciate, and anterior cruciate were strained. At 90 degrees of flexion, all four ligaments were strained. With varus loading, significant strains were found in the lateral collateral and anterior cruciate at extension. The lateral collateral and anterior cruciate ligaments were strained at 45 degrees of flexion. At 90 degrees of flexion, the lateral collateral, anterior cruciate, and posterior cruciate ligaments were strained. With valgus loading, the tibia rotated internally and the degree of axial rotation increased with flexion. External rotation of the tibia resulted from varus loading, and was relatively constant through the range of flexion. Thus when axial rotation is allowed, stability of the knee in response to valgus and varus loads is maintained by the cruciates as well as the collaterals, and the role of the cruciates increases with flexion and axial rotation.

Animals↗

PubMed1992

Primary and coupled motions in the intact and the ACL-deficient knee: an in vitro study in the goat model.

Quadrupeds are commonly used as animal models to study healing of anterior cruciate ligament (ACL) reconstructions. While rabbits, dogs, goats, and sheep have been used, goats and sheep are increasingly being employed because of the larger joint size that facilitates surgery, ease of availability, and lower expense to maintain in the farm environment. In spite of this, little is known about the function of the ACL in controlling primary and coupled motions in the quadruped. We report here on the measurements of these motions in goats, with the application of anterior-posterior forces, varus-valgus moments, and internal-external moments in the intact and ACL-deficient knee. Sectioning the ACL caused significant increases in primary anterior translation, and in varus-valgus and internal rotations. The increases in anterior translation were similar in amount and dependence on flexion angle to those seen in human knees. The increase in varus averaged 7 degrees and did not depend on flexion angle, whereas the increase in valgus was significant only in the flexed knee. The increases in internal tibial rotation were greatest in extension, whereas the increases in external rotation were small and independent of flexion angle. When the ACL was cut, coupled internal rotation increased with an anterior force as well as a valgus moment. Large increases were seen in coupled anterior translation with the application of varus and valgus moments, whereas smaller increases were seen with internal and external moments. These findings demonstrate that the ACL restrains multiple motions in the goat knee. This study also provides baseline data for future studies of ACL reconstruction.

Animals↗

PubMed1996

Effects of combined knee loadings on posterior cruciate ligament force generation.

Resultant forces in the posterior cruciate ligament were measured under paired combinations of posterior tibial force, internal and external tibial torque, and varus and valgus moment. The force generated in the ligament from a straight 100 N posterior tibial force was highly sensitive to the angle of knee flexion. For example, at 90 degrees of flexion the mean resultant force in the posterior cruciate ligament was 112% of the applied posterior tibial force, whereas at 0 degree, only 16% of the applied posterior force was measured in the ligament. When the tibia was preloaded by 10 Nm of external torque, only 9-13% of the 100 N posterior tibial force was transmitted to the posterior cruciate ligament at flexion angles less than 60 degrees; at 90 degrees of flexion, 61% was carried by the ligament. This "off-loading" of the posterior cruciate ligament also occurred when the tibia was preloaded by 10 Nm of internal torque, but only at knee flexion angles between 20 and 40 degrees. The addition of 10 Nm of valgus moment to a knee loaded by a 100 N posterior tibial force increased the mean force in the posterior cruciate ligament at all flexion angles except hyperextension; this represents a common and potentially dangerous loading combination. The addition of 10 Nm of varus moment to a knee loaded by a 100 N posterior tibial force decreased the mean force in the ligament between 10 and 70 degrees of flexion. External tibial torque (alone or combined with varus or valgus moment) was not an important loading mechanism in the posterior cruciate ligament. The application of internal torque plus varus moment at 90 degrees of flexion produced the greatest posterior cruciate ligament forces in our study and represented the only potential injury mechanism that did not involve posterior tibial force.

Aged↗

PubMed1984

Rotatory instability of cadaver knees after transection of collateral ligaments and capsule.

The importance of the medial and lateral compartment ligaments of the knee in relation to valgus-varus and axial rotation instability was investigated. Mobility patterns were drawn from 20 osteoligamentous knee preparations after successive transections of the structures. Cutting of the medial collateral ligament resulted only in slight valgus instability and modest anteromedial instability. When the medial posterior joint capsule was also cut, both types of instability increased, and moreover, the knee became posteromedially unstable. Cutting of the lateral collateral ligament produced only a little varus instability and anterolateral rotatory instability, but varus instability increased considerably when the posterior lateral capsule was also transected. In this latter situation, even marked posterolateral rotatory instability was found. Isolated transection of the medial or lateral collateral ligament did not cause any major valgus or varus instability, but when the posterior capsule was also transected, a considerable degree rotatory instability could be found even though the cruciate ligaments were intact.

Biomechanical Phenomena↗

PubMed1985

The pronation capacity of the foot--its consequences for axial deformity after tibial shaft fractures.

In spite of the fact that discomfort from the subtalar area is common after varus-deformed tibial shaft fractures no plausible mechanism is to be found in the literature. A mechanical analysis of the problems shows that a varus deformity is compensated as pronation of the foot. A limited pronation capacity could thus be the cause of the pain. Pronation capacity was accurately measured in ten osteoligamentous preparations. The average pronation capacity was found to be 9.5 degrees +/- 7.0 degrees. There was a marked interindividual variation. In two of the specimens the pronation capacity was less than 1 degree. Capacity decreased by 0.21 degree for every degree increase in plantar flexion of the ankle joint. Thus, a small pronation capacity may be the mechanical basis for ankle complaints after varus-deformed tibial shaft fractures. An anterior angulation, compensated as planar flexion, further decreases the pronation capacity and adds to the risk associated with varus deformities.

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PubMed2004

[Stability, bone healing and loss of correction after valgus realignment of the tibial head. A roentgen stereometry analysis].

In high tibial closing-wedge osteotomies (HTO), closure of an osteotomy gap after resection of a bony wedge can be associated with a fissure of the medial cortex of the tibial head (MCT). The effect of a broken MCT on the recurrence of varus deformity is disputed. In this study, serial roentgen stereometric analysis (RSA) was used to determine the fixation stability of a rigid internal "L" plate after HTO. Full weight lower limb radiographs were used to determine the sagittal alignment in patients with varying degrees of varus malalignment and correction over time. Forty-two patients with varus gonarthrosis stage I-III (Ahlback) were treated with HTO and internal fixation with an L-shaped rigid plate. Patients were followed by serial RSA, conventional radiographs, and clinical evaluation (Hospital of Special Surgery score) over a 12-month period. In 19 of 42 successive patients, an average wedge size of 6.9 degrees was resected leaving the MCT intact (group 1). In 23 of 42 of patients, the MCT was unintentionally fissured during surgery when an average 10.3 degrees -wedge was resected (group 2). In group 2, RSA revealed a fivefold increase in lateral displacement of the distal tibial segment within 3 weeks after HTO. Twelve weeks after HTO, translations between tibial segments were below the accuracy of the RSA setup in the majority of patients. Group 1 patients demonstrated a higher initial fixation stability, less occurrence of varus deformity, and a higher HSS score compared to patients with larger wedge sizes and frequent fracture of the MCT (group 2). Before bone healing is achieved, the integrity of the MCT plays a crucial role for the clinical and radiological outcome after HTO.

Adult↗

PubMed1999

[The Charcot joint].

Charcot foot in its original sense is equivalent to stage 4 of hereditary motor and sensory neuropathy (HMSN) which is known as Charcot-Marie-Tooth disease since 1886. This entity, which can be subdivided into 3 groups including subgroups, predominantly begins during childhood and progresses slowly. The first symptom, often unnoticed by the patient for a long period, is weakness of the intrinsic foot muscles with consecutive hammer-toe formation and mobile pes cavus. Progredient atrophy of the peroneal, extensor, tibialis posterior and finally triceps surae muscles leads to fixed pes cavus varus excavatus with severe varus deformity of the hindfoot, secondary varus position of the talus at the ankle level and subsequent arthrosis of the medial compartment. Permanent varus deformity of the ankle almost invariably leads to stress fractures of the malleoli because of repetitive microtrauma (stage 5 of HMSN). Early detection of the disease with nerve conduction studies at clinical suspicion allows tibialis posterior transfer, correctional osteotomy of the hindfoot or arthrodesis of Chopart's or Lisfranc's joint and can postpone or prevent the otherwise inevitable triple arthrodesis which has a less favorable long-term prognosis. At stage 4 (manifest Charcot foot) and stage 5 (neuropathic fracture of the ankle) a reorientating ankle arthrodesis is advocated, with additional subtalar pathology correctional double arthrodesis becomes necessary. In diabetic arthropathy of the ankle (Type IV according to Sanders and Frykberg), which is often referred to as "Charcot Ankle", tibiocalcanear arthrodesis is indicated. In case of supervening infection or extensive necrosis a modified Pirogoff amputation is carried out as a salvage procedure. Doubled periods of non weight-bearing, immobilization and brace protection of the ankle help to reduce the frequently observed implant failure in both forms of osteoarthropathy. In addition to stable implants retrograde calcaneotalotibial transfixation with a Steinmann pin may help to protect the achieved result despite prolonged bone consolidation.

Adult↗

PubMed2002

Long-term outcome following high tibial osteotomy with tension bend principle.

BACKGROUND: High tibial osteotomy has been successfully performed on patients with varus gonarthrosis for many years now. The prospective study presented here serves to verify the long-term outcome of this procedure. METHODS: A supratuberous high tibial osteotomy was carried out on 100 patients with varus gonarthrosis. Since then, 5 patients have died, and 6 patients could not be traced. The regaining rate was 94%. From a total of 89 patients with 101 operated knee joints, 46 were men and 43 women. The mean age at the time of surgery was 58 years. The patients were clinically and radiologically examined 10 years postoperatively and the knee score and function score ascertained according to the International Knee Society. RESULTS: The knee score showed a statistically significant increase from 31 points prior to surgery to 79 points at the time of follow-up; the function score likewise increased from 46 points to 78 points. In addition, 77.5% of patients would undergo the same surgery again, while 79% of patients claimed their condition to have improved following surgery. The preoperative full-length weight-bearing radiograph demonstrated an axis shift in the varus position of on average 9.6 degrees at 10 years postoperatively, an overcompensation in the valgus position of 1 degrees on average. At the time of follow-up, 81% did not require repeat surgery of the knee. CONCLUSION: With a correct diagnosis and accurate surgical techniques, positive clinical and radiological long-term results can be expected. Therefore, high tibial osteotomy may constitute an important contribution to our algorithm in the treatment of varus gonarthrosis.

Adult↗

PubMed2003

The influence of alignment on the musculo-skeletal loading conditions at the knee.

BACKGROUND AND AIM: High tibial osteotomies attempt to recreate physiologically normal joint loading. Previous studies have discussed the influence of mal-alignment on the distribution of static loads to the medial and lateral compartments of the knee. The aim of this study was to determine the influence of mal-alignment on the tibio-femoral loading conditions during dynamic activities. MATERIAL AND METHODS: Using a musculo-skeletal model of the lower limb, which had been previously validated with in vivo data, in this study we modified the alignment of the knee in four patients, from a normal position to the extremes of 8 degrees valgus and 10 degrees varus mal-alignment. The resulting tibio-femoral joint contact forces were examined while patients were walking and stair climbing. RESULTS: Varying the mal-alignment resulted in a highly individual response in joint loads. Deviations from the normal alignment produced an increase in loading, with valgus generating a more rapid increase in loading than a varus deformity of the same amount. Varus deformities of 10 degrees resulted in increases in peak contact force from an average of 3.3-times bodyweight (BW) up to a peak of 7.4 BW (+45% to +114%) while patients were walking, whilst increases of 15% up to 35% were determined for stair climbing. Increases of up to 140% were calculated at 8 degrees valgus during walking and up to 53% for stair climbing. CONCLUSION: This study demonstrated a clear dependence of the individual joint loads on axial knee alignment. Based on the sensitivity of joint loading to valgus mal-alignment, more than 3 degrees of over-correction of a varus deformity to valgus should be carefully reconsidered.

Biomechanical Phenomena↗

PubMed2003

Recovery of muscle strength after high tibial osteotomy.

To assess muscle strength after high tibial osteotomy (HTO) using percutaneous drilling, we prospectively evaluated the isometric and isokinetic muscle torque of the thigh before operation and after operation over time. We evaluated 27 joints of 26 patients with a mean age of 66 years. The muscle torque/weight ratio was seen to decrease, and the hamstrings/quadriceps (H/Q) ratio increased at 3 months after HTO; both ratios showed no significant difference at 6 months. Improved muscle strength appeared at isometric extensor of 50 degrees, not 80 degrees, and at slow isokinetic speeds of 30 degrees /s, not 90 degrees /s. There was no significant difference in terms of the age of patients regarding the recovery of muscle strength. We also compared patients with a varus angle of >/=5 degrees and those with a varus angle <5 degrees before the operation. In terms of extension, the group with varus angles <5 degrees showed a greater postoperative increase in isometric torque at 80 degrees flexion of the knee and isokinetic torque at 90 degrees /s than did the group with varus angles of >/=5 degrees.

Aged↗

PubMed2003

Juvenile Blount's disease: bilateral case with asynchronous onset.

We encountered a rare case of bilateral juvenile Blount's disease diagnosed as unilateral at the onset. The patient was a 9-year-old girl who visited our outpatient clinic with pain and deformity in the left knee. Examination of the left knee showed severe varus deformity. Correction of the varus deformity and tibial shortness was carried out at the same time by the callotasis method using an Orthofix external fixator. During follow-up the varus deformity in her right knee gradually progressed. At 18 months after the initial surgery, the right varus deformity and tibial shortness were corrected at the same time by the callotasis method using an Orthofix external fixator; proximal epiphysiodesis was also performed. The coronal-plane alignment of both knees remains good. In cases with bilateral involvement of Blount's disease, the onset of the deformity is usually nearly synchronous. In some cases, however, it begins unilaterally, as with this patient, so it is essential to check both sides by means of tomography or magnetic resonance imaging and not just radiography. Moreover, we must be careful to plan the treatment in such a case so as to anticipate possible leg-length discrepancy problems.

Bone Diseases, Developmental↗

PubMed1986

Effect of muscular activity on valgus/varus laxity and stiffness of the knee.

Quantitative changes in valgus/varus knee stability with different levels of muscular activity were determined for five subjects. A specially designed machine was used to measure resistance to angulation in the frontal plane. This device held the thigh stationary, the knee straight, an cycled the leg from side to side at a constant rate between present moment limits. Resistance to this forced valgus/varus motion was measured simultaneously with torque about the knee in the sagittal plane. Muscle activity was monitored by electromyography (EMG). Direct comparison of moment-rotation characteristics allowed changes in stability to be quantified as a function of extension and flexion torque. Extension torques less than 20% of the maximum increased varus stability more than valgus stability. Flexion torques of the same relative magnitude increased valgus stability more than varus stability. Comparison with the literature suggested that prevention of opening of the lateral side of the joint under varus loading was responsible for increased varus stability with increasing torque, both with extension and flexion torques.

Electromyography↗

PubMed1991

Rotational flexibility of the human knee due to varus/valgus and axial moments in vivo.

Knee ligamentous injuries persist in the sport of Alpine skiing. To better understand the load mechanisms which lead to injury, pure varus/valgus and pure axial moments were applied both singly and in combination to the right knees of six human test subjects. The corresponding relative knee rotations in three degrees of freedom were measured. Knee flexion angles for each test subject were 15 and 60 degrees for the individual moments and 60 degrees for the combination moments. For both knee flexion angles the hip flexion angle was 0 degrees. Leg muscles were quiescent and axial force was minimal during all tests. Tables of data include sample statistics for each of four flexibility parameters in each loading direction. Data were analyzed statistically to test for significant differences in flexibility parameters between the test conditions. In flexing the knee from 15 to 60 degrees, the resulting knee rotations under single moments depended upon flexion angle with varus, valgus, and internal rotations increasing significantly. Also, rotations were different depending on load direction; varus rotation was significantly different and greater than valgus rotation at both flexion angles. Also external rotation was significantly different and greater than internal at 15 degrees flexion, but not at 60 degrees flexion. Coupled rotations under single moments were also observed. Applying pure varus/valgus moments resulted in coupled external/internal rotations which were inconsistent and hence not significant. Applying pure axial moments resulted in consistent and hence significant varus/valgus rotations; an external axial moment induced varus rotation and an internal axial moment induced valgus rotation. For combination moments, varus/valgus rotations decreased significantly from those rotations at similar load levels in the single moment studies. Also, a varus moment significantly increased external rotation and a valgus moment significantly decreased internal rotation. These differences indicate significant interaction between corresponding load combinations. These results suggest that load interaction is a potentially important phenomenon in knee injury mechanics.

Adult↗

PubMed2005

Effects of laterally wedged insoles on knee and subtalar joint moments.

OBJECTIVE: To assess the biomechanic effects of wearing a lateral wedge on the knee joint varus moment during gait in elders with and without knee osteoarthritis (OA). DESIGN: Crossover design whereby subjects walked under 2 different insole conditions: a 0 degrees control wedge and a 6 degrees lateral wedge. SETTING: A gait laboratory with 3-dimensional motion analysis and force platform equipment. PARTICIPANTS: Thirteen healthy subjects and 13 knee patients with OA. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Frontal plane angles and moments at the knee and subtalar joints, ground reaction forces, and center of pressure. Moments were derived by using a 3-dimensional inverse dynamics model of the lower extremity. RESULTS: The 6 degrees lateral wedge significantly reduced knee joint varus moment and increased subtalar joint valgus moment in both groups when compared with no wedge. All patients had a greater knee joint varus moment with a similar subtalar joint valgus moment compared with the people without OA. There were diverse, sometimes reversed effects with the insole among the patients. CONCLUSIONS: The 6 degrees lateral wedge did not consistently reduce the knee joint varus moment in patients with knee OA. The biomechanic indications and limitations of laterally wedged insoles should be confirmed by a larger study.

Biomechanical Phenomena↗

PubMed2006

The effect of coronoid fractures on elbow kinematics and stability.

BACKGROUND: Coronoid fractures often occur in the setting of more complex elbow trauma. Little is known about the influence of coronoid fracture size on elbow kinematics, particularly in the setting of concomitant ligament injuries. The purpose of this study was to determine the effect of coronoid fractures on elbow kinematics and stability in ligamentously intact and medial collateral ligament deficient elbows and to determine the effect of forearm position on elbow stability in the setting of coronoid fracture. METHODS: Eight cadaveric arms were tested during simulated active dependent elbow motion and gravity-loaded passive elbow motion. Kinematic data were collected from an electromagnetic tracking system. The protocol was performed in ligament origin repaired and medial collateral ligament deficient elbows with radial head arthroplasty. Testing was carried out with the coronoid intact, and with 10% (Type I), 50% (Type II), and 90% (Type III) removed. Varus-valgus angulation of the ulna relative to the humerus and maximum varus-valgus laxity were measured. FINDINGS: With repaired ligament origins and medial collateral ligament deficiency, there was increased varus angulation and increased maximum varus-valgus laxity following simulation of a Type II and Type III coronoid fracture. There was less kinematic change with the forearm in supination than in pronation. INTERPRETATION: Elbow kinematics are altered with increasing coronoid fracture size. Repair of Type II and Type III coronoid fractures as well as lateral ligament repair is recommended where possible. Forearm supination may be considered during rehabilitation following coronoid repair. Valgus elbow positioning should be avoided if the medial collateral ligament is not repaired.

Aged↗

PubMed2005

The kinematic importance of radial neck length in radial head replacement.

Comminuted radial head fractures can be treated with a radial head implant. The effects of lengthening (2.5 mm, 5 mm) and shortening (2.5 mm, 5 mm) of the radial neck, were compared to the nominal length in six human upper extremity cadavers. Total varus-valgus laxity and ulnar rotation were recorded. We hypothesized that restoring the exact length of the radius is important to maintain normal kinematics in the elbow joint. Lengthening or shortening of more than 2.5 mm significantly changed elbow kinematics. Lengthening caused a significant decrease (p < 0.001) in varus-valgus laxity, with the ulna tracking in varus and external rotation. Shortening caused a significant increase in varus-valgus laxity (p < 0.001) and ulnar rotation (p < 0.001), with the ulna tracking in valgus and internal rotation. Our study suggests that a restoration of radial length is important and that axial understuffing or overstuffing the radiohumeral joint by 2.5 mm or more, will alter elbow kinematics.

Aged↗

PubMed2004

Stem cell repair of physeal cartilage.

To evaluate the ability of cultured mesenchymal stem cells (MSC) to repair physeal defects, MSC-matrix constructs with 5% gelatin (group A), 10% gelatin/Gelfoam (Pharmacia, Peapack, NJ) (group B), and MSC grown in the presence of TGF-beta3 with Gelfoam (group C) were implanted in proximal tibial physeal defects created in 20 immature rabbits. Control groups (untreated partial defect and partial defect treated with Gelfoam) showed bony bar formation with varus deformities of 30 degrees and 28 degrees, respectively. Group A had an average 23 degrees varus deformity with bony bridge formation, and group B had mild varus angulation (average 14 degrees) of the proximal tibia. In group C, there was no significant varus deformity (average 9 degrees), and histologic examination showed that some of the columnation areas interspersed with chondrocytes were irregularly arranged in the matrix. These findings suggest that repair of physeal defects can be enhanced by the implantation of MSC cultured with TGF-beta3.

Animals↗