The influence of total knee-replacement design on walking and stair-climbing.

The relationship between gait and prosthetic design was studied during level walking and stair-climbing for twenty-six asymptomatic patients after total knee replacement. An age-matched group of fourteen control subjects was also studied. Five designs of total knee replacement Geomedic, Gunston, total condylar, duopatellar, and Cloutier were used. Differences in gait could be identified on the basis of prosthetic design. The more stressful stair-climbing test produced more clearly differentiated function among the different designs. Patients who were treated with the least-constrained cruciate-retaining (Cloutier) design of prosthesis were the only group that had a normal range of motion during climbing up and down stairs. Two groups of patients with semiconstrained (total condylar and Geomedic) designs had a lower than normal range of knee fiexion while descending stairs. Patients with the other designs of prosthesis had a normal range of knee motion on stair-climbing. Kinematic and anatomical differences among the five designs did not have as great an influence on function during level walking as they did during stair-climbing. The results of this study indicate that after total knee replacement even asymptomatic patients with excellent clinical results have an abnormality of gait. The features of the abnormality were common to most of the patients in the series, and consisted of a shorter than normal stride length, reduced mid-stance knee flexion, and abnormal patterns of external flexion-extension moment of the knee. Although an explanation of these abnormalities of gait is not completely possible at this time, they appear to be related to the interaction of the kinematics of the knee and surrounding soft tissues. CLINICAL RELEVANCE: It appears that patients with less constrained cruciate-retaining designs of total knee replacement have a more normal gait during stairclimbing than patients with more constrained cruciate-sacrificing designs. During level walking, patients with five quite different designs all had abnormalities of gait in spite of a successful clinical result. There is currently a great deal of controversy regarding which type of total knee prosthesis provides better Funded in part by National Institutes of Health Grants KO4AMO()493 and ROIAM2O7O2 and by the Arthritis Foundation. 1 Department of Orthopedic Surgery . Rush-Presbyterian-St. Luke’s N’lcdical Center. 753 Wcst Congress Parkway, Chicago. Illinois 60612. gait. An improved understanding of gait and the variables associated with total knee designs is essential in addressing this controversy. Quantitative studies of gait during activities of daily living are needed to generate this information, and will be useful for the evaluation of total kneereplacement devices and for providing understanding of the loading patterns that may occur during normal activity. Several studies have evaluated gait in patients with knee disease. These investigations included kinematic analyses I .6.7.9.I i.2I , time-distance measurements, and force-plate measurements. There have also been several kinetic and force-analysis studies of function in normal subjects and in patients after treatment for knee disabilitiesaIa14l7ao. The common finding of these studies was that patients who appear to be clinically asymptomatic after joint replacement have abnormal gait patterns. Currently, little is known about the nature of the gait abnormality in patients after total knee replacement or its relationship to total knee-replacement design. The purpose of this study was to evaluate the relationship between gait and total knee-replacement design. The prosthetic knees that were selected for this study were considered to be representative of cruciate-sacrificing and sparing designs with varying amounts of constraint. The parameters ofgait that we observed included time-distance patterns and motion and moments of the knee joint. The gait of patients who had received one of five different designs of total knee replacement was evaluated and cornpared with that of control subjects. Materials and Methods Twenty-six patients. in five experimental groups. were studied during level walking and stair-climbing. Patients were grouped according to which of five total knee designs they had received. The five implants selected for this study were the Geomedic, Gunston, total condylar. duopatellar, and Cloutier designs. The five designs of prosthesis were selected to represent varying shapes of the articular surfaces and the retention of one, both, or neither cruciate ligament. The Geomedic prosthesis has fairly congruous articular surfaces. requires removal of the anterior cruciate ligament, permits retention of the ps)sterior cruciate ligament. and does not include a patellar flange or resurfacing. The Gunston prosthesis consists of two separate semicircular runners that articulate with two independent tibial components, permits retention of both cruciate ligaments. and does not include patellar resurfacing or a patellar flange. The total condylar design requires the sacrifice of both cruciate ligaments. with anterior-posterior stability provided by the conformity of the tibial articulating surfaces; all patients with this design had patellar resurfacing. The duopatellar prosthesis permits retention of the posterior cruciate ligament. includes a patellar flange. and allows patellar resurfacing, which was performed in all of the patients whom we examined. The Cloutier prosthesis allows retention of both cruciate ligaments and the femoral condyles are asymmetneal, diverge. and have varying radii of curvature. The tibial component of the Cloutier device consists of flat articular surfaces supported on a metal retainer, and the design has a patellar flange. but patellar resurfacing was not performed in our patients. The patients selected for this study were matched according to postoperative pain. function, passive range of motion, and joint stability. A point system based on The Hospital for Special Surgery knee.rating system was used to quantitate