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PubMed2000

[Computerized tomography assessment of femoral and tibial rotation in total knee prosthesis].

PURPOSE: CT assessment of the axial deviation of the femoral and tibial prosthetic components in total knee arthroplasty. MATERIAL AND METHODS: January to July 1999, seventeen patients, 10 males and 7 females, mean age 66 years (standard deviation +/- 4) were examined after total knee arthroplasty. Exclusion criteria were prosthesis loosening and severe (equal or superior to 7 degrees) varus or valgus deviation. All patients were examined with knee radiography in the standing position completed by axial projections of patella and by CT scanning. We used a modification of Berger technique and carried out comparative CT scans extended lower limbs and acquisitions perpendicular to the mechanical axis of the knee, from the femoral supracondylar region down to the plane crossing the distal end of the tibial prosthetic component. Reference lines were then drawn electronically on given scanning planes to reckon the axial deviation of the femoral and tibial prosthetic components. RESULTS: Six patients, one female and 5 males, with normal rotational values of femoral and tibial prosthetic components presented no clinical symptoms. Eight patients, 4 females and 4 males, with abnormal values presented the following clinical symptoms: medial impingement, (incomplete) dislocation patella, and lateral instability. One female patient with a normal rotational value of femoral prosthetic component and an altered value of tibial prosthetic component presented medial impingement. Finally two patients, one female and one male, were absolutely asymptomatic although the rotational values of the two prosthetic components were beyond the normal range. CONCLUSIONS: Total knee arthroplasty is presently a standard treatment for many conditions involving this joint. There are several possible postoperative complications, namely fractures, dislocations (a)septic loosening and femoropatellar instability. The latter condition is the most frequent complication among implant failures and is caused by bad orientation of the femoral and tibial components on frontal and axial planes. We measured the orientation of the prosthetic components introducing a CT procedure which modifies the uniarticular with four scans introduced by Berger. The new method uses Berger's parameters and the CT study of both joints by means of Helical CT. With a single examination lasting less than 4 minutes and with the patient in a more comfortable position, we can obtain: 1) comparative and simultaneous assessment of the contralateral joint; 2) several scans to better define Berger's parameters and to accomplish measurement of the rotational deviation with higher precision and markedly decreasing the error margin. The analysis of the results confirms the international literature findings and especially the fundamental importance in positioning both prosthetic components within normal values, as emphasized by the relationship between the clinical symptoms and the rotational degree of the femoral and tibial prosthetic components.

Aged↗
PubMed1993

Breakage of a Total Condylar III knee prosthesis. A case report.

The authors report the failure of a Total Condylar III (Cintor, Johnson and Johnson, Raynham, MA) knee arthroplasty, implanted in a second revision knee surgery, due to fracture of the tibial spine. The tibial component was in varus position and externally rotated relative to the tibia. This imparted torque and resulted in a spiral fracture of the polyethylene spine. This is the first report of failure of a Total Condylar III prosthesis by mechanical breakage.

Aged↗
PubMedDate not supplied

The Miller-Galante knee prosthesis system: a review of 42 cases.

The authors report their experience in 42 total Miller-Galante knee prostheses; 40 of the prostheses have an average follow-up of 25 months (minimum 9, maximum 55). Based on the Hungerford-Kenna clinical evaluation system, 59% of the patients obtained excellent results, 26% good results, 10% fair results, and 5% poor results. Radiographically, there were no cases of loosening of the implant. The joint axis was always well-corrected. A total of 12% of the patients complained of patellar pain (3 cases without either a prosthesis or keiloplasty; 2 cases with a patellar prosthesis). Overall, 85% of the patients obtained excellent or good results.

Aged↗
PubMed2005

Fatigue resistance analysis of tibial baseplate in total knee prosthesis--an in vitro biomechanical study.

BACKGROUND: Tibial baseplates were occasionally reported with clinical fatigue failures. This study postulated that tibial baseplate of a specific mobile bearing design with a uniform thickness across the baseplate offers more fatigue resistance than the fixed-bearing design. Tibial baseplates of a fixed bearing and a mobile bearing design were fatigue-tested in vitro to study their fatigue resistance. METHODS: Five samples of each design were tested under a sinusoidal loading between 90 N and 900 N at 30 Hz till failure or 10 million cycles. Experimental setup followed a standard published test method. Scanning electron microscope was used for inspecting the fracture surface of the failed baseplate. FINDINGS: Two baseplates of fixed bearing design failed before 10 million cycles. Fatigue crack advancement marks were visible on the fractured surface of the failed samples. The fractured cross-section showed that the failure started near the end of the fin, it was likely due to the stress concentration as stress singularity existed at a point of sudden geometrical change. Five mobile bearing baseplates passed the test. Design of the tibial baseplate without fin structure and with a uniform thickness across the whole baseplate could help reducing the incidence of fatigue failure. INTERPRETATION: The prosthesis survival rate was influenced by the long-term integrity of the metallic part of the prostheses such as the tibial baseplate. This study revealed that the tibial baseplate of a mobile bearing design with a uniform thickness provided better fatigue resistance than fixed bearing one. Standardized fatigue screening of the tibial baseplate was considered important in designing knee prostheses.

Biomechanical Phenomena↗
PubMed2006

Comparison of different microprocessor controlled knee joints on the energy consumption during walking in trans-femoral amputees: intelligent knee prosthesis (IP) versus C-leg.

The purpose of this study was to investigate the characteristic differences between the IP and C-Leg by making a comparative study of energy consumption and walking speeds in trans-femoral amputees. The subjects consisted of four persons with traumatic trans-femoral amputations aged 17 - 33 years who had been using the IP and were active in society. Fourteen able-bodied persons served as controls. First the energy consumption at walking speeds of 30, 50, 70, and 90 m/min was measured when using the IP. Then the knee joint was switched to the C-Leg. The same energy consumption measurement was taken once the subjects were accustomed to using the C-Leg. The most metabolically efficient walking speed was also determined. At a walking speed of 30 m/min using the IP and C-Leg, the oxygen rate (ml/kg/ min) was, on average, 42.5% and 33.3% higher (P< 0.05) than for the able-bodied group. At 50 m/min, the equivalent figures were 56.6% and 49.5% (P< 0.05), while at 70 m/min the figures were 57.8% and 51.2% (P<0.05), and at 90m/min the figures were 61.9% and 55.2% (P<0.05%). Comparing the oxygen rates for the subjects using the IP and C-Leg at walking speeds of 30 m/min and 90 m/min it was found that subjects who used C-Leg walked somewhat more efficiently than those who used IP. However, there was no significant difference between the two types at each walking speed. It was also determined that the most energy-efficient walking speed for subjects using the IP and C-Leg was the same as for the controls. Although the subjects in this study walked with comparable speed and efficiency whether they used the IP or C-Leg, the subjects' energy consumption while walking with the IP and C-Leg at normal speeds were much lower than previously reported. This study suggested that the microprocessor controlled knee joints appeared to be valid alternative for improving walking performance of trans-femoral amputees.

Adolescent↗
PubMed2003

Kinematics of three variations of the Freeman-Samuelson total knee prosthesis.

The effect of changes in the articulating surfaces on the kinematics of the Freeman-Samuelson total knee replacement was evaluated. Twenty-two patients (22 knees) (median age, 69 years) were randomized to a standard design with a fixed polyethylene bearing, a design with a mobile bearing, or a new design with a spherical medial femoral condyle with a fixed bearing. The patients were studied with radiostereometry and film-exchangers at 0 degrees nonweightbearing and during active weightbearing extension from 45 degrees to 15 degrees. The center of the tibial tray with a mobile-bearing prosthesis occupied a more anterior position than observed in the designs with a fixed bearing. The medial femoral condyle center had a more posterior position in the standard design than in the design with a spherical medial condyle. From a distally displaced position at 45 degrees, the medial condylar center displaced a mean of 1.8 mm proximally during extension in the standard design and had a constant position in the meniscal design. In the spherical design the medial condyle was displaced proximally at 45 degrees and displaced a mean of 1.6 mm distally during extension. The reduced anteroposterior and proximodistal translations in the meniscal design are compatible with improved congruency between the components. The design with a spherical medial condyle stabilized anteroposterior motions, but showed more pronounced proximodistal displacement medially than did the other two designs.

Aged↗
PubMed1993

A case of massive osteolysis after knee prosthesis polyethylene failure.

A case of massive osteolysis of the distal femur in response to particulate polyethylene from a broken uncemented tibial component is described. The osteolysis was so extensive that it made the revision arthroplasty extremely difficult. Early detection and early revision is recommended.

Femur↗
PubMed1990

GUEPAR total knee prosthesis. Results and outcome of seven years' use in a district general hospital.

Between 1980 and 1987, 44 total knee arthroplasties of the GUEPAR type were performed in 38 patients with severe degenerative joint disease. The patients have been followed up for 7 years and 70% of cases had a good or fair result. The 13 poor results included five cases of deep sepsis, three of whom subsequently underwent successful arthrodesis at this hospital. Other causes of a poor outcome were loosening and patellofemoral dysfunction. Radiological review of 27 knees showed that 80% had lucent lines at either cement/prosthesis or bone/cement interface, although these radiological findings were not associated with clinical evidence of loosening. The major long-term complication was shown to be retropatellar pain, which was recognized in 16% of all cases. However, this would seem to be the only significant long-term complication, and we believe that with the use of a patellar button the GUEPAR prosthesis should continue to be used in selected cases of severe degenerative joint disease.

Adult↗
PubMed1982

The spherocentric knee prosthesis (long term results in 18 cases).

The authors report the clinical and radiographic results at from six months to two years after the insertion of spherocentric knee prostheses in fourteen patients with rheumatoid arthritis and four patients with arthrosis of the knee. The results were satisfactory and there were no complications. This type of prosthesis has therefore become the treatment of choice in cases of varus or valgus deformity in excess of 30 degrees and those involving extreme instability. It is also an alternative after failures with other types of prosthesis.

Adult↗
PubMed1991

Localised mastocytosis at the bone and porous coated interface of a knee prosthesis.

A porous coated tibial plateau component, which was not loose, was removed 6 weeks after operation. An absence of bony ingrowth was demonstrated by histological and microradiographic examination. The radiolucent space was filled by young connective tissue and inflammation was indicated by the presence of a few macrophages or foreign body giant cells; there was also an increased number of mast cells near the metallic beads. Such inflammatory cells have not previously been reported around a firmly fixed joint prosthesis, but they have been associated with metallic particles. Since accumulations of mast cells can interfere with the process of bony ingrowth, further studies of removed porous coated prostheses should be made with adequate histological techniques so that the clinical significance of these cells can be better understood.

Aged↗
PubMed1982

The effect of knee-prosthesis geometry on cruciate ligament mechanics during flexion.

UNLABELLED: We used buckle transducers in conjunction with a mathematical model to investigate the mechanics of the cruciate ligaments during flexion of knees containing prostheses with differing component geometries. With normal component placement and both cruciate ligaments intact, the full range of flexion is restricted in a knee with the conforming, single radius-of-curvature geometric prosthesis because of large constraint forces in the posterior cruciate ligament. Ligament incompatibility is avoided with multicurvature designs, as represented by the kinematic prosthesis. Low conformity of components allows anterior-posterior displacements to accompany flexion, which provides for a full range of flexion and allows cruciate ligament forces to approach those of a normal knee. CLINICAL RELEVANCE: This analysis points out that special precautions must be taken to avoid ligament constraint forces (and potential loosening) if an implant with highly conforming components is used when both cruciate ligaments are intact. The information presented here, relating implant geometry to cruciate ligament mechanics, must be considered when choosing an appropriate prosthetic design to ensure ligament compatibility in the presence of one, both, or no cruciate ligaments.

Biomechanical Phenomena↗
PubMedDate not supplied

CKS knee prosthesis: biomechanics and clinical results in 42 cases.

From 1991 to 1993 a total of 42 CKS prostheses were implanted for the following reasons: osteoarthrosis (34 cases), rheumatoid arthritis (7 cases) tibial necrosis (1 case). At follow-up obtained after 17 to 41 months the results were: excellent or good: 41; the only poor result was probably related to excessive tension of the posterior cruciate ligament. 94% of the patients reported complete regression of pain, 85% was capable of going up and down stairs without support. Mean joint flexion was 105 degrees. Radiologically the anatomical axis of the knee had a mean valgus of anatomical axis of the knee had a mean valgus of 6 degrees. The prosthetic components were always cemented. The posterior cruciate ligament was removed in 7 knees, so that the prosthesis with "posterior stability" was used. The patella was never prosthetized. One patient complained of peri-patellar pain two months after surgery which then regressed completely.

Aged↗
PubMedDate not supplied

[Baropodometric walking analysis in healthy elderly and in arthritic patients before and after knee prosthesis implantation].

Standing and walking are complex activities which require integral skeletal-muscular and central nervous systems. Body is usually, evenly distributed between both the lower limbs with 40% on the ball of the foot and 60% on the heel, therefore, the body's centre of gravity falls between the feet in correspondence to Chopart's articulation. Some diseases can influence standing and walking including cardiovascular diseases (chronic edema, claudication, cardiopathies etc.) neurosensorial ones (cataract, Menière's disease, Parkinson's disease etc.) and orthopedic ones (kyphosis, scoliosis, hallux valgus, metatarsalgia, osteoarthritis etc.). In this study arthritis was considered the main cause of changes in posture and deambulation. An electric baropodometer with a modular platform 240 cm long and 40 cm wide was used which provided the pressure information for each in three distinct phases: static, dynamic and postural Baropodometric step analysis was performed on ten healthy, elderly subjects and ten elderly subjects with arthritis of the knee. The latter group was evaluated both pre- and post prosthetic knee surgery. The data revealed that the ten healthy subjects with arthritis who, prior to surgery presented unequal weight distribution on the diseased side which was slowly redistributed after surgery.

Age Factors↗
PubMed1981

Guepar total knee prosthesis. Experience at the Vancouver General Hospital.

Eighty-three Guepar valgus-hinge prostheses and 30 prostheses with collinear femoral and the tibial components were inserted in 97 patients at Vancouver General Hospital between March 1975 and May 1978. One hundred and nine arthroplasties were reviewed between January 1979 and April 1980, after an average follow-up of 19 months. It was found that the amount of bone resected made arthrodesis difficult, that there was a very high incidence of patellar instability and that the disintegration of the Silastic bumper created a severe chemical synovitis. The results were excellent in 32, good in 23, fair in 8, and poor in 30. Patellar subluxation occurred in 28 per cent of the valgus prostheses, and in 10 per cent with the straight prostheses; it did not occur with the straight prostheses in rheumatoid joints. The chemical synovitis led to failure with devastating complications necessitating further operations in some knees.

Adult↗
PubMed2000

Evaluation of preoperative cultures before second-stage reimplantation of a total knee prosthesis complicated by infection. A comparison-group study.

BACKGROUND: Two-stage reimplantation has proven to be highly successful in the treatment of patients with infection at the site of a total knee arthroplasty. However, up to 20 percent of patients have a recurrence of infection following this treatment. The purpose of our study was to determine whether aspiration of the affected joint and culture of the specimen, performed before reimplantation and after discontinuation of antibiotic therapy, would help to identify patients who might have a recurrent infection. METHODS: We prospectively followed sixty-nine patients who were treated for a culture-proven deep infection at the site of a total knee arthroplasty. Group I consisted of thirty-five patients who were treated with removal of the prosthetic components and irrigation and debridement of the joint, followed by six weeks of antibiotic therapy and reimplantation of a prosthesis. Group II was composed of thirty-four patients who were treated with removal of the components and irrigation and debridement of the joint, six weeks of antibiotic therapy, and then repeat culture four weeks after the antibiotic course had ended. If the culture was negative, the patient was managed with a second-stage reimplantation of a prosthesis. If the culture was positive, the protocol was repeated, beginning with irrigation and debridement. The two groups were similar with regard to male-to-female ratio, age, preoperative Knee Society scores, time since primary surgery, types of infectious organisms, duration of symptoms, duration of follow-up, and number of previous revisions. All of the patients were evaluated clinically with use of the objective scoring system of the Knee Society and were followed with serial radiographs. Success was defined as no infection and a functional prosthesis, with a Knee Society score of at least 75 points at the last (thirty-six-month-minimum) follow-up evaluation. RESULTS: Of the thirty-five patients in Group I, five (14 percent) had recurrence of infection. One of the patients was managed with a successful second-stage revision, three were managed with arthrodesis of the knee, and one continued with chronic antibiotic suppressive treatment. Of the thirty-four patients in Group II, three (9 percent) had a positive culture after the course of antibiotics. The protocol was repeated for all three, and they subsequently had a successful second revision. One other patient (3 percent) in Group II, who had a negative culture, had a recurrent infection and was eventually managed with arthrodesis of the knee. CONCLUSIONS: Prerevision cultures, grown after discontinuation of antibiotic treatment and before reimplantation of the components, helped to identify the patients with infection at the site of a total knee arthroplasty in whom the infection might recur. The performance of aspiration and cultures resulted in a substantial improvement in the clinical outcome.

Aged↗
PubMed1999

[Traction-mobilization in 2-stage treatment of infected total knee prosthesis. Apropos of 12 cases].

INTRODUCTION: A two stages reimplantation is advised by most authors in salvage of infected total knee arthroplasty. This treatment is more difficult, but seems more successful in controlling infection. It set the problem of the attitude between the two operative stages: an antibiotic cement spacer is usually used, but articular mobilization is not possible, except with an articulating spacer. MATERIAL AND METHODS: Since 1989, we use traction-mobilisation between the two operative stages, with mobilization under traction up to 50 degrees, and on edge of bed up to 70-90 degrees, till the reimplantation. We used this method on 12 cases of chronic infection in total knee arthroplasty. The reimplantation was done 34 to 47 days later. The reimplantation was more easy and more comfortable in approach and exposition, and post operative mobilisation easier. RESULTS: We did not have any recurrence of infection in this patients, but the follow up is too short for some of them. One prosthesis was removed for mechanical failure. The mean range of motion is 86 degrees at two months, 96 degrees at one year. DISCUSSION: The antibiotic cement spacer presents the disadvantage of leaving material in a potentially infected environment. It does not allow mobilisation, except using an articulating spacer. Traction-mobilisation keep articular flexion, allows mobilization, and does not leave any material in articulation. But this method has the disadvantage of requiring an hospital care between the two stages: that is reasonable if the delay is short. CONCLUSION: Traction mobilization seems to be an alternative to cement spacer. It makes the reimplantation easier, facilitates post operative recovery of mobility, and does not seem to increase recurrence of infection.

Aged↗
PubMed1993

The Miller-Galante knee prosthesis for the treatment of osteoarthrosis. A comparison of the results of partial fixation with cement and fixation without any cement.

In a prospective, non-randomized study of 344 patients who had 392 primary total knee replacements with a Miller-Galante I prosthesis for the treatment of osteoarthrosis, the results of partial fixation with cement (insertion of the tibial and patellar components with cement and of the femoral component without cement) were compared with those of fixation without any cement. Of the 392 knees, 183 (163 patients) had fixation without cement (Group I) and 209 (181 patients), with and without cement (Group II). The average duration of follow-up was three years (range, two to five years). Nine patients died during the follow-up period, but no others were lost to follow-up. Analysis of the knee scores, range of motion of the knee, radiographs, and rates of complications revealed no differences between the outcomes in the two groups during the follow-up period. The rate of complications due to problems related to the extensor mechanism was high in both groups: a reoperation was performed in fifteen (8 per cent) of the knees that had had fixation without cement and in nineteen (9 per cent) of those that had had both types of fixation. Thirteen patients had additional operative treatment for recurrent patellar dislocations; twelve patients, for abnormal wear of the polyethylene of the patellar component: two patients, for avulsion of the patellar ligament from the tibia; and two patients, for unexplained pain in the knee. In addition, there were eight patellar fractures (two of which led to a reoperation) and three deep infections (all of which led to a reoperation).

Adult↗