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PubMed2001

The role of knee alignment in disease progression and functional decline in knee osteoarthritis.

CONTEXT: Knee osteoarthritis (OA) is a leading cause of disability in older persons. Few risk factors for disease progression or functional decline have been identified. Hip-knee-ankle alignment influences load distribution at the knee; varus and valgus alignment increase medial and lateral load, respectively. OBJECTIVE: To test the hypotheses that (1) varus alignment increases risk of medial knee OA progression during the subsequent 18 months, (2) valgus alignment increases risk of subsequent lateral knee OA progression, (3) greater severity of malalignment is associated with greater subsequent loss of joint space, and (4) greater burden of malalignment is associated with greater subsequent decline in physical function. DESIGN AND SETTING: Prospective longitudinal cohort study conducted March 1997 to March 2000 at an academic medical center in Chicago, Ill. PARTICIPANTS: A total of 237 persons recruited from the community with primary knee OA, defined by presence of definite tibiofemoral osteophytes and at least some difficulty with knee-requiring activity; 230 (97%) completed the study. MAIN OUTCOME MEASURES: Progression of OA, defined as a 1-grade increase in severity of joint space narrowing on semiflexed, fluoroscopically confirmed knee radiographs; change in narrowest joint space width; and change in physical function between baseline and 18 months, compared by knee alignment at baseline. RESULTS: Varus alignment at baseline was associated with a 4-fold increase in the odds of medial progression, adjusting for age, sex, and body mass index (adjusted odds ratio [OR], 4.09; 95% confidence interval [CI], 2.20-7.62). Valgus alignment at baseline was associated with a nearly 5-fold increase in the odds of lateral progression (adjusted OR, 4.89; 95% CI, 2.13-11.20). Severity of varus correlated with greater medial joint space loss during the subsequent 18 months (R = 0.52; 95% CI, 0.40-0.62 in dominant knees), and severity of valgus correlated with greater subsequent lateral joint space loss (R = 0.35; 95% CI, 0.21-0.47 in dominant knees). Having alignment of more than 5 degrees (in either direction) in both knees at baseline was associated with significantly greater functional deterioration during the 18 months than having alignment of 5 degrees or less in both knees, after adjusting for age, sex, body mass index, and pain. CONCLUSION: This is, to our knowledge, the first demonstration that in primary knee OA varus alignment increases risk of medial OA progression, that valgus alignment increases risk of lateral OA progression, that burden of malalignment predicts decline in physical function, and that these effects can be detected after as little as 18 months of observation.

Aged↗

PubMed2003

[Gait-analytical studies in patients treated by valgus tibial head osteotomy].

So far, the use of imaging methods has been the only way of evaluating unicompartmental gonarthritis caused by malalignment of lower extremity axes and the results of operative correction. Unfortunately, radiological visualization does not give any information about the actual loads on the joint, i.e.the forces and moments acting on it under dynamic conditions. These can be determined by means of gait-analytical measurements. The authors explain how the anomalous loading that occurs in the knee joint in the case of varus gonarthritis can be calculated and assessed. The mean maximum varus moment of knee joints in a group of patients with varus deformity was 0.74 Nm\kg, which was significantly higher than that in a control group (0.63 Nm\kg). Even after correction of the axes, increased maximum moments--some of them independent of the angle of the knee and of the correction angle--were observed in 30% of the cases investigated. These cases were found to be characterized by a predisposition to revarization. Knee joints in which the preoperative varus moment was significantly high or there was a tendency to under-correction were especially likely to show these features. For these reasons, valgus tibial head osteotomies should generally be performed with slight overcorrection. If the preoperative gait analysis has already confirmed that significantly increased varus forces are in play, a definite overcorrection to about 5 degrees beyond the physiological angle should be the aim.

Adult↗

PubMed2002

Distribution of bone mineral density at the proximal tibia in knee osteoarthritis.

One hundred and thirteen knees with osteoarthritis (OA) were studied to assess the distribution of bone mineral density (BMD) in the proximal tibia and the potential relation between osteoarthritis and osteoporosis in evaluating hip BMD. All patients had severe knee pain and were diagnosed with Kellgren and Lawrence grade IV osteoarthritis. According to the magnitude of the axial deformity, four categories were created: varus>10 degrees ( 28.3%), varus 4-10 degrees (38.9%), aligned 180 +/- 3 degrees (13.3%), and valgus>4 degrees (19.5%). For each category, the medial and lateral proximal tibial density were assessed. BMD was measured at the femoral neck and at 14 regions of interest (ROI) in the proximal part of the tibia using dual X-ray absorptiometry. Based on the femoral neck BMD, patients were classified according to the World Health Organization (WHO) definition of osteoporosis. The mean knee BMD was positively correlated with the hip BMD value (knee BMD m = 0.38 + 0.73 x hip BMD, r = 0.60, P<0.001). The knee BMD distribution of the 113 patients was negatively correlated with the axial deformity (BMD MT-LT = 5.15 - 0.027 x HKA, r = 0.77, P<0.0001). In the varus deformity, BMD of the medial side was higher than that of the lateral side with an important asymmetry (0.587 g/cm2). This asymmetry was also found in the valgus deformity for the lateral side but was less important (-0.112 g/cm2). With equal deformity, the asymmetry of BMD was higher in varus deformity (0.587 g/cm2) than in valgus deformity (-0.112 g/cm2). Asymmetry of the knee BMD distribution revealed that progression of the deformity (either varus or valgus) with joint space narrowing led to an increase in the medio-lateral difference of the proximal tibia density. Lesser severity of Kellgren and Lawrence grades may reveal different results. Twenty patients with osteoporosis developed knee osteoarthritis (OA) and the relation between osteoporosis and knee OA remains unclear.

Absorptiometry, Photon↗

PubMed2006

[Influence of rotatory malposition of femoral implant in failure of unicompartimental medial knee prosthesis].

PURPOSE OF THE STUDY: Rotatory malposition of the femoral component of a unicompartmental knee arthroplasty (UKA) is a key element of mechanical failure despite proper alignment and position of the tibial implant. The purpose of this study was to describe a method for measuring femoral implant rotation on the anteroposterior x-ray using an original geometric model. MATERIAL AND METHODS: 276 medial UKA (227 non-cemented Uni Goeland, Depuy; Uni, AMP) and 49 cemented (Miller-Galante, Zimmer) were reviewed and analyzed at a mean 11 years (range 7 - 15) using the Knee Society Score. Mean objective and functional scores were 43 and 47 points preoperatively. Postoperative alignment and position of the femorotibial contact point were determined. The frontal and sagittal position of the tibial plateau was noted by the angle formed with the mechanical axis. Angles alpha and B of the femoral implant formed between the mechanical axis and the greater condylar axis and the inferior condylar line passing through the apex of the condylar convexity respectively were measured on the AP view. Frontal rotation (angle B) of the femoral implant reflected the orientation of the distal condylar cut. The frontal measurement (angle alpha) was validated using simple geometric formulas: knowing angles alpha and B and the size of the implant and the displacement of the point of contact was measured together with the true rotation of the femoral implant or anteroposterior divergence, function of the difference alpha-B which is its frontal projection and reflects the orientation of the posterior condylar cut. RESULTS: Mean alignment was 3 degrees varus. At last follow-up, outcome was satisfactory in 81.2% of the knees (224 UKA). Mean objective and functional scores were 90 and 87 points. Angles alpha and B were parallel and orthogonal to the mechanical axis or off by less than 4 degrees external rotation (+6 degrees to -4 degrees). The mean difference alpha-B (frontal projection of the femoral implant transverse rotation) was 1 degrees. The point of contact was 4 mm or less from the middle of the tibia. Failures were observed in 18.8% of knees (52 UKA): 4 for diverse reasons and 48 for mechanical failure, including 3 with polyethylene wear without loosening (two by eccentric point of contact and neutral position and one by inverted misalignments). 45 UKA (16.3%) presented loosening of the tibial plateau alone with rotatory femoral malposition: mean a angle off 13% from the mechanical axis (+16 degrees to -9 degrees ), mean B angle off 8 degrees (+12 degrees to -8 degrees), mean alpha-B difference 5 degrees , femoral implant in square position on polyethylene with a peripheral point of contact > or 5 mm from the middle of the tibial plateau. The tibial implant exhibited mean varus of 1.5 degrees. DISCUSSION: The main cause of failure was rotatory malposition of the condylar implant often associating frontal with transversal rotation. This increased mediolateral translation of the point of contact during knee motion causing abrasion and excessive pressure on the medial portion of the plateau. Frontal malrotation externalizes the posterior cut on the condyle tilted by the varus position, without correcting the varus of the mechanical axis in flexion. To avoid such prosthetic malrotations, three corrections must be made before making the bone cuts: cancel the external rotation of the condyles in flexion by positioning the distal cut guide in extension; re-establish the mechanical axis by reducing the internal tilt of the condyles resulting from the varus position both in extension (distal cut) and flexion (posterior cut). Improved instrumentations and reproducible techniques are needed to re-establish the 3D anatomic orientation of the femoral component, a key element for longer life of unicompartmental prostheses. This method for measuring the rotation of the femoral implant and the displacement of the point of contact using a geometric model applied to the AP view is useful for better understanding UKA failures.

Adult↗

PubMed1995

Effect of rotational malposition of the femoral component on knee stability kinematics after total knee arthroplasty.

Excessive external rotation of the femoral component can cause an abnormally tight popliteus tendon complex, which induces loss of rotational laxity of the knee in the late phase of knee flexion after total knee arthroplasty. This study evaluated the effect of popliteus tendon release on rotational and varus-valgus laxity of implanted knees with an excessively externally rotated femoral component. Rotational and varus-valgus laxity was measured with a knee kinematics testing device before and after total knee arthroplasty. External rotational positions of the femoral component of 5 degrees and 8 degrees were compared, and the effects of popliteus tendon release on rotational and varus-valgus laxity were evaluated. To further investigate this question, the effect of a conforming articular design was compared with that of a flat tibial surface. External rotational position of 5 degrees did not change rotational or varus-valgus laxity of the knee. With an 8 degrees external rotational position, however, external rotational laxity significantly decreased in knees with a conforming surface at angles of 30 degrees, 45 degrees, 60 degrees, and 90 degrees. After popliteus tendon release, external rotational laxity significantly improved at 90 degrees flexion and was identical to that of the normal knee. Internal rotational range was similar before and after popliteus tendon release. Popliteus tendon release did not affect the varus-valgus laxity (stability) with either articular surface.

Biophysical Phenomena↗

PubMed1997

Axial lower-limb alignment: comparison of knee geometry in normal volunteers and osteoarthritis patients.

Osteoarthritis of the knee is associated with deformities of the lower limb and malalignment of the limb segments. Pathogenetic relationships between the two are poorly understood. Alignment was studied by standardized radiography in 167 symptomatic Canadian osteoarthritis patients, and compared with 119 healthy adult volunteers. In healthy adults overall alignment (hip-knee-ankle angle) was principally determined by distal femoral valgus (condylar hip angle) and proximal tibial-plateau varus (plateau-ankle angle): the angle between the joint surfaces (condylar plateau) was relatively constant. In osteoarthritis, disease-associated differences included condylar-plateau angles that were divergent: accentuated medial convergence in varus osteoarthritis and lateral convergence in valgus osteoarthritis. This was interpreted as change arising from focal loss of cartilage in the medial (varus osteoarthritis) or lateral (valgus osteoarthritis) compartments of the knee. The changes would contribute to increasing limb malalignment during disease progression. But differences of limb geometry also contributed to malalignment. These were the average trends: in varus osteoarthritis there was abnormal femoral geometry (lesser femoral condylar valgus), but tibial surface geometry was the same. In valgus osteoarthritis, the opposite was true: abnormal tibial geometry (lesser plateau varus), but normal femoral geometry. A possible explanation is that these abnormal knee geometries pre-exist and predispose to osteoarthritis, although it is not impossible that they (like condylar-plateau angle) change as disease progresses. Further approaches to population studies are discussed based on these findings, along with their implications for knee surgery.

Adult↗

PubMedDate not supplied

Knee angles and rickets in nigerian children.

Knee angles of 2,036 normal Nigerian children up to 12 years old were measured directly or from photographs. The knees were bowed (varus) in the first 6 months. At 21 to 23 months, the distribution of angles became strongly bimodal: about half were varus and half were valgus (knock-kneed), with few in between. After this they were all valgus, with few exceptions. Hence, the change from varus to valgus in individual infants must be sudden (a few weeks), although the changeover of the whole population appears smooth and gradual. They became maximally and uniformly knock-kneed (-7.1 degrees +/- 1.4 degrees) between 3 and 3.5 years, with little change thereafter. On the other hand, 120 patients with rickets discovered during screening had large knee angles, in either sense, with a bimodal distribution and frequency maxima at +10 degrees (varus) and -12 degrees (valgus). Varus knee is uncommon after 2 years. Large knee angles between 2 and 5 years suggest rickets.

Age Factors↗

PubMed2001

Remodeling of the temporomandibular joint following mandibular distraction osteogenesis in the transverse dimension.

Transverse mandibular distraction osteogenesis involves moving the osteotomized segments of the mandible in either a varus or valgus direction. This maneuver allows for widening of the bigonial distance or for a lateral shift of an asymmetric mandibular midline. During this process, a significant amount of torque is placed on the mandibular condyles, because they act as the pivot point for the mandibular translation. Although standard linear distraction osteogenesis induces transient, reversible changes in the temporomandibular joint, it is not known what effect the varus and valgus stresses of transverse distraction have on the temporomandibular joint. We therefore designed a study to document the temporomandibular joint changes following various degrees of transverse distraction. Bilateral transverse mandibular distraction was performed on 10 adult, female mongrel dogs using an external, multiplanar mandibular distraction device. The distraction protocol was as follows: (1) complete osteotomy at the angle of the mandible, (2) 5-day latency period, (3) distraction rate of 1 mm/day, (4) rhythm of one turn per day, (5) linear activation 16 to 30 mm bilaterally, and (6) 8-week consolidation period. A variety of varus and valgus distraction vectors were applied to the mandible only after 10 mm of initial linear distraction had been achieved. Posteroanterior and lateral cephalograms were performed throughout the entire process. Pre-distraction and post-consolidation computed tomographic scans were also performed. Changes in mandibular conformation, axis of rotation, temporomandibular joint structure, and glenoid fossa changes were directly assessed by evaluating the postmortem craniofacial skeleton. The findings were compared with those of normal, age-matched mongrel dog skulls. Significant remodeling changes were observed in the temporomandibular joints of all animals involved in the study. The mandibular condyles demonstrated varying degrees of flattening and erosion at all contact points with the craniofacial skeleton. In some cases, the condyle became part of the distraction regenerate process and was hypertrophied in all dimensions. The condyles were frequently displaced out of the glenoid fossa, particularly on the side in the direction of varus distraction. When the latter occurred, a new fossa was created on the undersurface of the zygomatic arch. Varying degrees of mandibular rotation in the sagittal plane were also observed, which led to abnormal torquing of the condyles in the coronal plane, depending on whether the axis of rotation occurred primarily around the condyle or around the distraction regenerate zone.In conclusion, transverse mandibular distraction is an effective means of producing a varus or valgus shift in the gonion relative to the midsagittal plane. However, unlike linear or angular mandibular distraction, transverse distraction has a multitude of nontransient effects on the temporomandibular joint. Therefore it must be emphasized that in clinical practice, transverse distraction should be used cautiously. One must also be aware that such a maneuver in distraction can have negative effects on the temporomandibular joint.

Animals↗

PubMed1983

A biomechanical analysis of the etiology of tibia vara.

To elucidate the cause of tibia vara, finite element analysis of the proximal tibia was used to investigate the stresses occurring in the physeal plate during one-legged stance in 2- and 5-year-old children. A modification of the method of Kettlekamp and Chao was used to assign forces to the medial and lateral plateaus and lateral ligament. Stresses were calculated in the physeal plate for the two age groups as a function of degree of varus and body weight. Our results show that increasing varus resulted in increasing compressive stress in the medial tibial physis to a level seven times normal at 30 degrees of varus. Further, tensile stresses determined in the lateral tibial physis were increased above normal. Changes were more marked in the obese child and in the 5 year old. Using the data from Strobino et al. it appears that in the 2 year old 20 degrees of varus resulted in forces sufficient to retard growth. In the 5 year old, however, 10 degrees of varus resulted in borderline forces in a child of normal weight, but forces exceeding those necessary to retard physeal growth were calculated in the model of the obese child. Our data are consistent with the hypothesis that Blount's disease is primarily the result of the proximal tibial epiphysis responding to physical phenomena.

Biomechanical Phenomena↗

PubMed2004

Load-sharing at the wrist following radial head replacement with a metal implant. A cadaveric study.

BACKGROUND: Surgical excision of the radial head is frequently required after a comminuted fracture of the radial head. The outcome of this procedure is often unpredictable, with some patients experiencing ulna-sided pain in the wrist secondary to proximal migration of the radius. Insertion of a radial head prosthesis could prevent proximal radial migration and restore normal load-sharing at the wrist. The thickness of the radial head implant is an important variable in restoring anatomical radial length; however, the effects of varying the length of implants that were used to reconstruct the radius on load-sharing at the wrist have not been studied biomechanically, to our knowledge. METHODS: A miniature load cell was attached to fifteen fresh-frozen cadaveric forearms to record force in the distal part of the ulna as the wrist was axially loaded to 134 N of compression force. Proximal displacement of the radius relative to the capitellum was also recorded. Loading tests on intact forearms were performed with the elbow in valgus and varus alignment and with three positions of wrist rotation (neutral, 45 degrees of pronation, and 45 degrees of supination). Loading tests were then repeated, with the same positions of varus and valgus elbow alignment and wrist rotation as had been used in the tests of the intact forearm, after radial head excision and subsequent insertion of metal radial head implants that restored anatomical length, implants that produced a radial length that was longer than the anatomical length, and implants that produced a radial length that was shorter than the anatomical length. Testing of these different implant thicknesses was repeated after sectioning of the interosseous membrane. RESULTS: The mean distal ulnar forces and mean proximal radial displacements following insertion of an implant that restored anatomical length were not significantly different from the corresponding values for the intact forearm. At neutral wrist rotation, replacing that implant with an implant that increased the radial length by 4 mm (after sectioning of the interosseous membrane) decreased the mean distal ulnar force from 13.4% to 3.3% of the applied wrist force with the elbow in valgus alignment and from 29.1% to 8.6% with the elbow in varus alignment. Replacing the implant that restored anatomical length with one that decreased the length by 4 mm (after sectioning of the interosseous membrane) significantly increased the mean distal ulnar force from 13.4% of the applied wrist load to 33.3% with the elbow in valgus alignment and from 29.1% to 51.6% with it in varus alignment. The mean distal ulnar forces were not significantly affected by the position of wrist rotation when the elbow was in valgus alignment. However, when the elbow was in varus alignment, the mean distal ulnar forces associated with all reconstructed radial lengths were significantly higher when the wrist was placed in 45 degrees of supination. CONCLUSIONS: In this cadaveric model, insertion of a metal implant maintained distal ulnar forces at normal levels, at all three positions of wrist rotation, when the radius had been restored to its original anatomical length. Distal ulnar forces and proximal radial displacements were significantly affected by the reconstructed length of the radius. CLINICAL RELEVANCE: Radial head implants are utilized to prevent proximal migration of the radius as the wrist is loaded; this is especially important when the interosseous membrane has been ruptured and thus cannot help to limit radial displacement. At the time of surgery, comminution and displacement of a radial head fracture may make estimation of the original radial length difficult. Our results demonstrate that, in terms of distal ulnar loading, it is preferable to insert an implant that is too thick rather than too thin.

Aged↗

PubMed2005

Comprehensive treatment of late-onset tibia vara.

BACKGROUND: Late-onset tibia vara (Blount disease) can be difficult to treat because of frequent morbid obesity and associated deformities, including distal femoral varus, proximal tibial procurvatum, and distal tibial valgus, that contribute to lower extremity malalignment. We present a comprehensive approach that addresses all components of the deformity and allows restoration of the anatomic and mechanical axes. METHODS: Fifteen consecutive patients (nineteen lower extremities) with late-onset tibia vara were managed with this comprehensive approach. The mean age of the patients at the time of surgery was 14.9 years, and the mean weight was 113 kg. Standing anteroposterior and lateral radiographs were made preoperatively and at the time of the final follow-up. Preoperatively, the mean mechanical axis deviation was 108 mm, the mean lateral distal femoral angle was 95 degrees , and the mean mechanical medial proximal tibial angle was 71 degrees . In all nineteen extremities, the proximal tibial varus deformity was corrected by means of a valgus osteotomy and application of an Ilizarov ring external fixator. Distal femoral varus was corrected by means of either hemiepiphyseal stapling or valgus osteotomy with blade-plate fixation in thirteen of the nineteen extremities. Distal tibial valgus was treated either with hemiepiphyseal stapling or with varus osteotomy and gradual correction with use of the Ilizarov external fixator in eleven of the nineteen extremities. RESULTS: After a mean duration of follow-up of 5.0 years, the mean mechanical axis deviation had improved to 1 mm (range, 20 to -30 mm), the lateral distal femoral angle had improved to 87 degrees (range, 83 degrees to 98 degrees), and the mechanical medial proximal tibial angle had improved to 88 degrees (range, 83 degrees to 98 degrees ). The mean time required for correction of the proximal tibial varus deformity was thirty-one days, and the external fixator was removed at a mean of 4.5 months postoperatively. All patients had development of one or more superficial pin-track infections (mean, 1.9 pin-site infections per patient). No wound infections, nonunions, or neurovascular complications occurred. Eighteen of the nineteen extremities were pain-free at the time of the final follow-up. CONCLUSIONS: This comprehensive approach allowed restoration of the mechanical and anatomic axes of the lower extremity in patients with late-onset tibia vara, resulting in a resolution of symptoms as a result of normalization of the weight-bearing forces across the knee and ankle. We believe that this approach will decrease the risk of early degenerative arthritis of the knee.

Adolescent↗

PubMedDate not supplied

Fracture separation of the distal humeral epiphysis in children younger than three years old.

This study evaluated the change of carrying angle and the causes of cubitus varus after the fracture separation of the distal humeral epiphysis in young children. Twelve cases of fracture separation of distal humeral epiphysis were treated from January 1995 to July 1997. The age of all patients was younger than 3 years old. A metaphyseal fragment was seen in all cases (Salter-Harris type II), but the size of the metaphyseal fragment was either a very small flake or a large Thurston-Holland fragment. Posteromedial displacement was seen in all cases. There were three treatment groups: closed reduction with percutaneous pinning, closed reduction with cast, and cast without reduction. Follow-up period averaged 23.5 months (range, 12-40). Cubitus varus deformity was seen in seven cases, and six of them had a partial defect of the medial condyle that was avascular necrosis. The methods of treatment, age of injury, and the type of epiphyseal injury had no influence on the development of cubitus varus, but avascular necrosis of the medial condyle was related to the cubitus varus deformity (p<0.05). The results of this study suggest that fracture separation of distal humeral epiphysis in young children is likely to produce cubitus varus deformity with the development of avascular necrosis of the medial humeral condyle.

Casts, Surgical↗

PubMed2001

[Dual x-ray absorptiometry assessment of bone density of the proximal tibia in advanced-stage degenerative disease of the knee].

PURPOSE OF THE STUDY: Axial deformity secondary to degenerative joint disease of the knee can modify stress forces. Certain studies have reported an inversely proportional relationship between degenerative disease and osteoporosis. The aim of this prospective study was to quantify the horizontal linear distribution of bone density using dual x-ray absorptiometry (DXA) of the proximal tibia as a function of the femoral neck bone density in patients with knee osteoarthritis. MATERIAL AND METHODS: Between September 1996 and March 1998, 90 cases of primary degenerative joint disease of the knee were programmed for total knee arthroplasty. Prior to the procedure, the patients were assessed clinically and radiologically according to the International Knee Society (IKS) criteria. The mechanical femorotibial angle was measured in all patients and the varus angles were recorded. Most of the patients were women (65 p. 100) with a mean age of 70 +/- 5 years. Valgus knees were excluded from this series. The mean mechanical femorotibial angle was 172 +/- 5 degrees. Fifteen patients had a normal axis (16 p. 100), 32 had a varus measuring 4 degrees to 10 degrees (35 p. 100) and 43 had a varus measuring 10 degrees or more (48 p. 100). The overall varus distance was 6.4 +/- 2 cm. All patients had two DXA explorations: femoral neck to determine the bone status according to the WHO criteria (normal, osteopenia, osteoporosis), knee to determine the linear distribution of bone density of the proximal tibia. A 7 mm high band including 7 regions of interest covering the width of the tibia were explored in the area where the tibial cut was to be made. These 7 regions of interest were: R1, R2 under the lateral compartment, R6, R7 under the medial compartment, and R3, R4, R5 on either side of the tibial spines. The level of significance was set at 5 p. 100. RESULTS: The mean Z score (0.54 +/- 1) in the 90 patients showed a symmetrical distribution. These patients were representative of their age range. Their T score was - 1.40 +/- 1 (m +/- SD) and most had osteopenia (54 p. 100) according to the WHO criteria, although 16 p. 100 had osteoporosis. Mean bone density of the knee was 0.898 +/- 0.163 g/cm(3) and was correlated with that of the femoral neck (r=0.61, p=0.001). There were significant correlations between the differences in the bone densities of the knee compartments (R6-R2, R7-R1) and the mechanical femorotibial angle [(r=0.39, p=0.0001); (r=0.52, p=0.001)]. Irrespective of the overall bone density, there was a strong medial compartment overloading, which correlated with the degree of varus deformation. CONCLUSION: DXA assessment of bone mineral density of the proximal tibia is a simple, reliable, precise and reproducible method. The distribution of bone density in the degenerative knee depends on the degree of deformation. The average level depends on the subject's general state of mineralization. Osteoporosis does not protect against degeneration of the knee joint since 16 p. 100 of our patients had osteoporosis according to the WHO criteria.

Absorptiometry, Photon↗

PubMedDate not supplied

[Conventional radiology in the choice of surgical treatment of gonarthrosis].

Gonarthrosis is a pathologic condition the incident of which is high in people over 50. Its etiologic factors are varus-valgus deformities, traumatic lesions, meniscal tears, osteochondritis, and metabolic diseases. The authors report their experience with the setting of a radiographic protocol for the study of 100 patients over 50. The protocol allowed both detection and quantification of: varus and valgus deformities studied in weight-bearing (teleradiography in weight-bearing) and extensor mechanism malalignment (tangential views); chondral wear of femoral and tibial joints (varus and valgus radiographs); varus and valgus knees instability (varus and valgus radiographs). The results are extremely satisfactory: this protocol allowed correct gonarthrosis grading and the evaluation of such associated lesions as lateral instability. The surgeon is thus provided with the essential elements for the choice of the correct treatment.

Female↗

PubMed1984

[Electromyographic analysis of the leg muscles in the hemiplegic patients with equinovarus deformity of the foot].

A series of EMG study of the leg muscles was carried out with a wire electrode in 86 hemiplegic patients of stroke to visualize the role of each muscle either in the development of equinovarus deformity of the foot or in correcting the deformity through tendon transfer. The muscles examined were anterior tibialis, posterior tibialis, gastrocnemius, soleus, flexor digitorum longus and peroneus brevis of the affected side. Tonic discharge of those muscles was recorded as the patients were elevating the affected leg in supine, sitting or standing posture or were standing on legs. On lifting up the affected limb, most patients showed electrical activity of anterior tibialis with or without simultaneous activity of other muscles, most frequently with that of flexor digitorum longus or gastrocnemius. When the patient stood on legs electromyographic discharge appeared most frequently in soleus. Varus deformity of the foot significantly correlated to the lack of the electrical activity of peroneus brevis. Both such abnormal activity of anterior tibialis and the lack of activity of peroneus seemed to be the main causes for the varus deformity. Postoperative EMG study in the patients who underwent Watkins-Barr procedure of anterior transfer of the posterior tibialis tendon, showed that the posterior tibialis was rather inactive both in elevating the leg and in standing on legs. Varus deformity was corrected independent of the discharge of posterior tibialis. The author concluded that the correction of the varus deformity after Watkins-Barr procedure was mainly obtained from the tenodesis effect. The tenodesis provides the checkline effect on the equinus and varus deformity, which reinforces the dorsiflexing action of anterior tibialis and attenuates its inverting action of the same muscle.

Adult↗

PubMedDate not supplied

Evaluation of femoral osteotomy in the treatment of Legg-Calvé-Perthes disease.

The optimal time and type of the varus-innerrotation femoral osteotomy in the treatment of Legg-Calvé-Perthes disease (LCPD) was evaluated on the basis of 53 hips having early operations and 14 hips having late operations and also on the basis of the previous observations on the disturbed venous drainage in various stages of LCPD. The operation should be done as early as possible in the cases in which it is indicated. Both the operative results in the present series and the theoretical background based on the severe disturbances of venous circulation in the initial phases justify an early intervention. The anatomic results of the early operated-on hips (74% good, 17% fair, and 9% poor) were related to the degree of the varusation and to the postoperative uncovering of the head. In the good results, the attained varusation was greater and the positioning of the head within the acetabulum deeper than in the fair or poor results. Accordingly, in "risk" cases, the optimal angle of the neck immediately after the varusation should be 100--100 degrees. With such varusation, it is possible to obtain good containment and a remarkable relief of the load against the femoral head during walking and running.

Child↗

PubMed1994

Postoperative alignment of total knee replacement. Its effect on survival.

Four hundred twenty-one posterior cruciate condylar total knee arthroplasties were performed between 1975 and 1983. Anatomic alignment of the knee was recorded on follow-up evaluations from two months to 13 years postoperatively. Patients were stratified into a normal group that was 5 degrees to 8 degrees anatomic valgus, a varus group that was from 4 degrees anatomic valgus to any degree of varus, and a valgus group that was more than 9 degrees anatomic valgus. There were eight failures, five in the varus group and three in the normal group. There were no failures in the valgus group. Kaplan-Meier survival curves showed no significant difference between normal and valgus groups; however, there was a statistical difference between the valgus and varus and the normal and varus groups. A surgeon should align a total knee prosthesis in neutral or a slight amount of anatomic valgus to give the patient the best chance for long-term survival.

Aged↗

PubMed1977

Supracondylar fractures of the humerus: the role of dynamic factors in prevention of deformity.

In a retrospective survey of eighty-two children with supracondylar fractures of the humerus, forty were found to have sufficient clinical and roentgenographic data to classify the fractures as varus or valgus, and to determine the carrying angles at end result. The initial displacement (varus or valgus) of the distal fragment correlated with the final carrying angle, but the use of internal fixation, the adequacy of reduction achieved and the duration of traction or immobilization did not. The sixteen varus supracondylar fractures immobilized with the forearm in supination had a mean varus deformity of about 16 degrees, whereas the eight immobilized in pronation had a varus deformity of only 3 degrees. The findings in the few valgus fractures suggested that the valgus angulation was less at follow-up if they had been immobilized in supination. Dissection of eight cadaver limbs and electromyographic studies of one normal limb suggested that the position of the forearm affects the result by altering muscle tension.

Adolescent↗