The axes of rotation of the knee

Knee motion is believed to occur about a variable flexion-extension (FE) axis perpendicular to the sagittal plane and a longitudinal rotation (LR) axis. The authors used a mechanical device to locate the FE and the LR axes of six fresh anatomic specimen knees. The motion of points on the LR axis produced circular, planar paths about the fixed FE axis. Magnetic resonance (MR) images in planes perpendicular to the FE axis showed a circular profile for the femoral condyles. The FE axis is constant and directed from anterosuperior on the medial side to posteroinferior on the lateral side, passing through the origins of the medial and lateral collateral ligaments and superior to the crossing point of the cruciates. The LR axis is anterior and not perpendicular to the FE axis, the anatomic planes. This offset produces the valgus and external rotation observed with extension. The implications of two fixed offset axes for knee motion on prosthetic design, braces, gait analysis, and reconstructive surgery are profound.     

Experimental study of promoting the rates of dog''s tooth rotation by circumferential supracrestal fiberotomy just before rotation

The focus of this study was satisfaction with health and its relationship to good health practices, symptoms and current use of medication. A self-administered questionnaire was circulated to employees of a railroad company. 3,639 males aged 18 to 54 (41.4 +/- 7.61) were selected. Seven good health practices each scored 1 were not smoking including quitting, not drinking or drinking less than six days a week, exercise more than two days per week, body mass index (BMI) being 20 to 28, total nightly sleeping time between six and nine hours, having breakfast everyday, and not eating between meals. Each score was summed up as health practice index (HPI). We also asked about health satisfaction for the past year, subjective symptoms over the last two to three months, and present medication history. HPI increased significantly in the group aged 45 to 54, this group being satisfied with their health. A decrease in the percentage of eating between meals in the under 35 group, inappropriate BMI in the 45 to 54 group, and regular exercise in the group aged 50 or older was recognized. Health satisfaction was predicted using symptoms, present medication, age and health practice. Standardized discriminant coefficients of symptoms and present medication were 0.672 and 0.610, and they were more associated to health satisfaction than health practice.     

Total knee replacement after failed tibial osteotomy: results of a matched-pair study

Sixty-three total knee replacements were performed after a failed tibial osteotomy. The goal of this study was to compare the perioperative problems and the outcome of this group of patients (study group) to a group of patients with primary arthroplasties matched for age, gender, length of follow-up, weight, and preoperative Charnley class. Operative problems were more frequently encountered in the study group, with 7 tibial tubercle elevations and 15 lateral retinaculum releases needed, whereas lateral retinaculum release was necessary for only 1 knee in the control group. Outcome was assessed using both the International Knee Society (IKS) scoring system and Hospital for Special Surgery (HSS) knee score. The follow-up period averaged 4.6 years. The IKS score of the control group was significantly higher, averaging 80.9 +/- 13.8, whereas it was 74.4 +/- 14.8 for the study group (P = .0001). Among the parameters included in the knee score, only pain was significantly different with the control group (P = .03). The IKS function score and the HSS score were not statistically different. Conversion of a failed tibial osteotomy is a technically demanding procedure. Careful preoperative planning is needed. Results, especially on pain, appeared to be inferior to those for primary arthroplasties.     

The effect of tibial torsion of the pathology of the knee

Measurements of tibial torsion using a tropometer were made in more than 1200 consecutive patients attending an adult knee clinic. In total 1672 readings from 836 patients in 11 diagnostic categories were analysed. Patients with either patellofemoral instability or Osgood-Schlatter disease had a significant increase in lateral tibial torsion. The most important finding was a significant reduction in this torsion in patients with panarticular disease.     

Thickness of tibial inserts in total knee arthroplasty

The thickness of the ultrahigh-molecular-weight polyethylene used in the tibial inserts of total knee arthroplasties has become topical in recent years. A discrepancy has been found between the nomenclature of tibial inserts and the actual minimum thickness of polyethylene. Although the recommended minimum thickness is being discussed, it is important to clarify what is actually being used, with an indication to change and unify how these inserts are named.     

Revision total knee arthroplasty after failed unicompartmental knee arthroplasty or high tibial osteotomy

A retrospective matched-pair comparative analysis was done between 30 total knee arthroplasties following failed high tibial osteotomies and 30 total knee arthroplasties following failed unicompartmental knee arthroplasties. The groups were matched according to age, gender, type of prosthesis, primary disease, and length of followup. A minimum followup of 2 years was required for inclusion in the study, and the average followup was 3.8 years (range, 2-9 years). The Knee Society Knee Score for the high tibial osteotomy group was significantly higher than that for the unicompartmental arthroplasty group. More osseous reconstructions were required in the unicompartmental revisions. Difficulty with exposure was not significantly greater in the osteotomy group. Rates of component loosening were not significantly different between the groups. A failed unicompartmental knee arthroplasty and a failed high tibial osteotomy can be revised successfully to a total knee arthroplasty. The results confirm that revisions after unicondylar arthroplasty and high tibial osteotomy are technically demanding. In this series, the results of total knee arthroplasty following unicompartmental knee arthroplasty approached but did not equal those obtained after high tibial osteotomy.     

Posterior tilting of the tibial component decreases femoral rollback in posterior-substituting knee replacement: a computer simulation study

The extensor tendons of the fingers and toes form part of the capsule of the interphalangeal joint and press against the proximal phalanx during flexion. Previous work on the fingers has shown that there is a "sesamoid" fibrocartilage on the deep surface of each tendon that labels immunohistochemically for a variety of glycosaminoglycans and collagens. However, we know little about the molecular composition of the tendon in the toes. This question is of special interest, because the mechanics of the interphalangeal joints differ in the upper and lower limbs-the toes balance the forefoot, distribute load during the gait cycle, and transmit the pull of larger muscles. This means that their extensor tendons are more often under higher tension than those in the fingers. Here, we report the presence of an equivalent fibrocartilage and compare its immunolabelling characteristics in all the toes. Six forefeet were removed from elderly cadavers, and the interphalangeal (IP) joints were fixed in 90% methanol. The extensor tendon and its enthesis were dissected out from the IP joint of the big toe and from the proximal interphalangeal (PIP) joint of all lesser toes, decalcified, cryosectioned, and immunolabelled with a panel of monoclonal and polyclonal antibodies for type I, II, III, and VI collagens; chondroitin 4 and 6 sulphates; and dermatan and keratan sulphate. Antibody binding was detected with the Vectastain ABC Elite avidin-biotin-peroxidase kit (Vector Laboratories, Burlingame, CA). The extensor tendon in all the toes had a metachromatic, sesamoid fibrocartilage on its deep surface that immunolabelled for all glycosaminoglycans and for type I, III, and VI collagens. Labelling for type II collagen was seen in the sesamoid fibrocartilage of all toes but was particularly characteristic of the 2nd through 5th toes. The immunolabelling patterns of the enthesis fibrocartilage were similar in all toes and to results reported previously for fingers. The normal occurrence of type II collagen in the sesamoid fibrocartilage of the 2nd through 5th toes is in contrast to our published data on the fingers. The finding can be related to the more constant loading of the tendon in the toes. The greater prominence of type II collagen in the sesamoid fibrocartilage of the 2nd through 5th toes could be related to a difference in joint position during walking between the 1st toe and the 2nd through 5th toes--the PIP joints of the latter are usually more flexed than the IP joint of the former.     

Effect of tibial component position on patellar strain following total knee arthroplasty

Gliosarcomas are morphologically heterogeneous tumors of the central nervous system composed of gliomatous and sarcomatous components. The histogenesis of the latter is still a matter of debate. As mutations of the p53 tumor suppressor gene represent an early event in the development of gliomas, we attempted to determine whether both components of gliosarcomas share identical alterations of the p53 gene. Using single-strand conformation analysis (SSCA) and direct DNA sequencing of the p53 gene, we analyzed dissected gliomatous and sarcomatous parts of 12 formalin-fixed, paraffin-embedded gliosarcomas. The two tumors that contained a p53 alteration were found to carry the identical mutation (exon 5; codon 151, CCC-->TCC; codon 173, GTG-->GTA) in the gliomatous and the sarcomatous components. These findings suggest a common origin of the two cellular components from neoplastic glial cells.     

Proximal tibial osteotomy for osteoarthritis of the knee (author's transl)

One hundred and seventeen cases of osteoarthritis of the knee-joint, were treated with tibia osteotomy. The result of the different types of the osteotomy are discussed. The proximal tibial osteotomy without metal-fixation has the best results.     

Small wire external fixation of high energy tibial plateau fractures

Open plate osteosynthesis for high energy tibial plateau fractures with dissociation between the metaphysis and diaphysis has been plagued with frequent soft tissue complications. The Harbor-University of California at Los Angeles Medical Center's experience with small wire external fixation supplemented by limited internal fixation is examined. This alternative method of adequate stable fixation offers the advantage of minimal soft tissue compromise. Twenty-four patients with Schatzker Type VI tibial fractures were treated with small wire external fixation. Supplementary limited internal fixation was used with percutaneous screws in 10 patients and with open reduction in one patient. Sixteen patients had isolated fractures, and eight others suffered multiple injuries. Minimum followup was 12 months. All fractures healed. Complications included one septic knee, two infections at screw sites, and one 10 degrees knee flexion contracture. One knee had Grade 3 radiographic arthrosis, five had Grade 2, 10 had Grade 1, and eight showed no arthrosis. The outcomes (Knee Society clinical rating system) of this study compare favorably with outcomes described in reports published previously for this type of fracture, despite inclusion of eight multiply injured patients. This technique preserves the goals of early range of motion and stable fixation for these devastating injuries, while decreasing the observed major wound complications and nonunion rates. However, longer followup may reveal higher arthrosis rates, specifically in those fractures that were not anatomically reduced.     

Early catastrophic tibial component wear after unicompartmental knee arthroplasty

Unicompartmental knee arthroplasty is an appropriate method of treating selected patients with osteoarthritis of the medial compartment of the knee. The common causes of failure are aseptic loosening, infection, patellofemoral pain, and deterioration in the opposite compartment. Seven cases of a cohort of 32 Robert Brigham unicondylar knee replacements that failed because of early catastrophic wear of the polyethylene tibial component are reported. Possible reasons suggested for failure include inadequate thickness of polyethylene, fusion defects in the polyethylene structure as a result of the sterilization process, increased rotational freedom, and reduced conformity in the design of the prosthesis.     

Experimental ligation versus embolization of the external carotid artery: a comparative hemodynamics study

Patterns of collateral vascularization were investigated by SEM evaluation of microvascular corrosion casts following either ligation or embolization of the external carotid artery in the rabbit. Results indicated that rich collateral channels were established soon after ligation of this artery, and blood supply to the lesional area was never cut off. In contrast, embolization effectively obstructed blood supply by reducing collateral branches. We concluded that for purposes of controlling blood loss, it is more helpful to employ external carotid embolization rather than ligation for oral maxillofacial lesions with a rich blood supply.     

Intracondylar knee joint prosthesis with rotation capacity- Endo model

The St. Georg total knee prosthesis has been modified to incorporate axial rotation of the tibial component. The kinematics approximate more those of the normal knee and the stress imposed at the bone-cement interface are attenuated, thus reducing the risk of mechanical failure. The construction and laboratory testing are described.     

Experimental study on the thermoelastic martensitic transformation in shape memory alloy polycrystal induced by combined external forces

Combined tension and torsion experiments with thin wall specimens of Cu-Al-Zn-Mn polycrystalline shape memory alloy (SMA) were performed at temperatureT =A _f + 25 K. The general stress-strain behaviors due to the thermoelastic martensitic transformation, induced by a combination of external forces of axial load and torque, were studied. It is shown that the progress of martensitic transformation (MT) at general stress conditions can be well considered as triggered and controlled by the supplied mechanical work (a kind of equivalent stress) in the first approximation. Pseudoelastic strains in proportional as well as nonproportional combined tension-torsion loadings were found fully reversible, provided that uniaxial strains were reversible. The axial strain can be controlled by the change of torque andvice versa due to the coupling among tension and torsion under stress, not only in forward transformation, but also in reverse transformation on unloading. The pseudoelastic strains of SMA polycrystal are path dependent but well reproducible along the same stress path. The evolution of macroscopic strain response of SMA polycrystal, subjected to the nonproportional pseudoelastic loading cycles with imposed stress path, was systematically investigated. The results bring qualitatively new information about the progress of the MT in SMA polycrystal, subjected to the general variations of external stress. PETR SITTNER, Research Associate, formerly with the Faculty of Engineering, Mie University     

Advantages of the unreamed tibial nail in comparison with external fixator in treatment of grade 3 B open tibial shaft fractures

Between 1987 and 1993, 41 grade 3B open tibial shaft fractures were treated with the unreamed tibial nail (URTN n = 22) or an external fixator (FIX n = 19). The method of treatment was left to the choice of the operating surgeon. Three below the knee amputations were performed, three patients died, and three were lost to follow-up. In all, 32 patients were followed up to union or at least for 1 year. There were no significant statistical differences between the two groups (P < 0.2, chi-squared, t-test) with respect to fracture type, fracture location, age, gender or accompanying injuries. The URTN group showed significantly better results regarding time to full weight-bearing (URTN 11 +/- 4 weeks; FIX 20 +/- 11 weeks, P < 0.01 M-W) Mann-Whitney Test, number of reoperations (URTN 1.04; FIX 2.89; P < 0.01 M-W), isolated bone grafting (URTN 3/22; FIX 8/19; P < 0.05 chi-squared), and average Karlstr?m and Olerud score (URTN 30 +/- 4; FIX 26 +/- 5; P < 0.05 M-W). In all, 15/17 URTN patients and only 6/15 FIX patients achieved unlimited walking distance (P < 0.01 M-W). Time to bony union, infection, and nonunion were not significantly different between groups.     

Experimental osteoarthritis in the rabbit knee joint

The development of arthrotic-like changes following the resection of the cruciate ligaments in the knee joint of rabbits has been studied at intervals from 2 weeks to 10 months in 35 animals. Signs of cartilage degeneration were followed by changes in the subchondral bone, where formation of osteophytes and condensation took place. An increased vascular supply was demonstrated by microangiographic and scintigraphic investigations. The uptake of 18F and 99mTc-polyphosphate reached a maximal value about 2 months after the operation and then diminished despite further development of arthrotic changes.     

The effects of thigh soft-tissue stiffness on the control of anterior tibial displacement by functional knee orthoses

BACKGROUND AND OBJECTIVE: Ovarian ultrasonography may be helpful in distinguishing the various types of precocious puberty, and the ovarian appearances increasingly influence choice of therapy in these girls. We examined retrospectively the ovarian volume and prevalence of polycystic ovarian appearance at ultrasound in girls with sexual precocity. DESIGN: Ultrasound examinations were obtained from girls who presented with sexual precocity. If there were several scans from the same individual, the latest was analysed. PATIENTS: The girls were divided into groups: untreated central precocious puberty (n = 25), central precocious puberty treated with GnRH analogue (n = 18) or with GnRH analogue and recombinant human GH (n = 11), girls who had stopped treatment with GnRH analogue and GH (n = 12), premature thelarche and thelarche variant (n = 15) and premature adrenarche (n = 14). MEASUREMENTS: Ovarian volume was calculated and the ovaries were assessed for polycystic appearance using standard criteria. Ovarian volume standard deviation (SD) scores were calculated using means and standard deviations derived from a control population and compared using analysis of variance. Differences from control data were assessed using Student's t-test. RESULTS: Ovarian volume SD scores for all the groups studied were greater than those for control subjects. Girls who had stopped treatment with GnRH analogue and GH had mean ovarian volume of 6.98 ml and ovarian volume SD score (+1.72) greater than that of girls having treatment with GnRH analogue alone (+1.24). Polycystic appearance ovaries were found in 83% of scans in girls who had stopped treatment with GnRH analogue and GH. The ovarian volume SD score of girls with premature adrenarche was less than that of girls with untreated central precocious puberty. CONCLUSIONS: Girls with central precocious puberty had large ovaries which did not return to a volume appropriate for age. Girls treated with GnRH analogue and GH developed very large ovaries when they stopped treatment, and had an increased prevalence of ovaries with a polycystic appearance. Central precocious puberty, or some aspect of its treatment, results in an increased prevalence of polycystic ovarian appearance.