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PubMed2003

[Initial experience with implantation of the cemented Beznoska/S.V.L. total knee joint endoprosthesis].

PURPOSE OF THE STUDY: The authors present the results of their first trial of a new, Beznoska/S. V. L. type, knee prosthesis in order to introduce it to a broad orthopedic public. MATERIAL: Clinical and radiological evaluation was carried out on 34 knee prostheses implanted in 31 patients between September 1997 and October 1999. The average patient age at the time of surgery was 71.3 years and the average interval between surgery and assessment was 22.4 months (range 6 to 31 months). All patients underwent implantation due to primary or secondary gonarthosis. A brief description of the implant and the instrumentation and used surgical technique is provided. METHODS: Clinical outcomes were evaluated according to the "Knee-Society Clinical Rating System" by John N. Insall. The system classifies both knee joint parameters and knee function. X-ray films were assessed on the basis of the "Knee-Society Total Knee Arthroplasty Roentgenographic Evaluation and Scoring System" by Frederic C. Ewald. In standardized X-ray projections, this allowed us to evaluate the implant position as well as radiolucent lines. RESULTS: On stability evaluation, we found anteroposterior instability up to 5 mm in 85% of the implants and mediolateral instability up to 9 degrees in 97% of them. A maximum flexion of 90 degrees to 120 degrees was achieved in 91% of the implants. The final outcome in terms of knee score was on average 80.3 points (range, 40 to 97 points), which was a very good result. Evaluation by function score showed that only 17% of the patients were not able to walk farther than 500 meters. Although 82% of them had to hold on a railing when going upstairs, all were able of stair ascent and descent; 13% had to use a walking stick permanently. The average function score was 68.4 points (range, 30 to 100), which was a good outcome. Radiograms in anteroposterior projection, assessed according to Ewald, showed the average femoral flexion angle (alpha) to be 95.2 degrees, the average tibial angle (beta) to be 89 degrees and the total valgus angle (omega) to be 3.2 degrees. In lateral projection, the femoral flexion angle (gamma) was on average 2.5 degrees and the average tibial angle (delta) was 86.7 degrees. An optimal position of the patella was achieved in 27 implants. Five radiolucent lines, up to 1 mm, were found in zone 1 of the femoral component and further lines were observed in zones 1, 2 and 4 of the tibial component. DISCUSSION: When assessing the results by the knee and function scores, it had to be taken into consideration that the average age of the patients was 71.3 years. At this age, walking without a stick, or stair ascent or descent without the use of a railing can hardly be expected. The average result of 68.4 points achieved can, therefore, be considered a very satisfactory outcome. The values shown by X-ray examination were close to the normal condition. The patients were also asked for their subjective opinion of the effect of arthroplasty; 97% of them regarded the effect as good or very good, only one patient reported no benefit. CONCLUSIONS: The results of the first trial of the use of a cemented prosthesis, type Beznoska/S. V. L., in total knee arthroplasty are presented, together with practical recommendations. Although the patient sample was small and the follow-up period short, the results are promising and suggest excellent prospects for this implant.

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PubMed1986

[The knee joint].

The knee is very important in the treatment of rheumatic diseases. Differentiating between the indications for different forms of therapy is dependent upon knowledge of the prospects for success. Synovectomy, preventive and palliative procedure, is the most important joint-saving measure, as confirmed by the long-term results presented here. Synoviorthese and arthroscopic operative procedures are alternatives and have expanded the spectrum. However, their long-term effectiveness has not yet been proved. Rheumatic, recurring synovitis has not yet been defined satisfactorily. Additional soft tissue operations should always be included in preoperative planning and determine the form of therapy. Alloarthroplasty of the knee is the foremost reconstructive measure, and excellent long-term results have already been achieved in some cases. It should be remembered, however, that modifications of individual models occasionally have a considerable influence on the results. Particularly for rheumatic knee joint deterioration, knee prosthesis models that guarantee long-term success should be given preference if the time and effort expended are justifiable. Continuous passive mobilization seems to be the most valuable postoperative measure.

Arthritis, Rheumatoid↗
PubMed1986

Myositis ossificans following porous-ingrowth TK replacement.

Clinically significant myositis ossificans of the distal thigh following virginal porous-ingrowth total knee arthroplasty has not been previously reported. Associated and potentially contributing factors in this particular case were (1) the patient's preoperative hypertrophic gonarthrosis, (2) our difficulty in regulating her postoperative sodium warfarin (Coumadin) dosages, (3) the postoperative knee manipulation, and (4) possibly, the additional surgical exposure of this patient's distal femur required to use the femur-based alignment instrumentation. Postoperative heterotopic ossification developing in the vicinity of a porous-ingrowth total knee prosthesis can have clinical significance. Treatment of this problem by a means that does not interfere with early bone ingrowth into the implant is a practical concern that warrants investigation.

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PubMed2005

Analysis of wear asymmetry in a series of 94 retrieved polyethylene tibial bearings.

Knee joint kinematics is the focus of a significant amount of experimental study for the purpose of knee prosthesis design and for testing the wear of current and prospective bearing materials. This study reports the wear assessment of a series of 94 explanted tibial bearings of various designs and manufacturers and focuses on the extent to which clinical wear is symmetric in the medial-lateral aspect, or is indicative of a systematic asymmetry that would be informative to the design and testing of knee prostheses or surgical practice. Wear assessment of the series of retrievals indicates that, statistically, there was more clinical wear on the medial side. Patterns of wear varied greatly among individual knees; a majority showed very similar extents of wear on the medial and lateral sides, however there were cases with significantly more wear on one condylar articulation than the other. Evidence of edge loading, whereby the femoral component articulates at the margin of the tibial bearing, was common. It was seen most frequently in the central zone of the medial condylar area, and, like the overall wear, edge loading was significantly more frequent on the medial side of bearings. Total bearing wear was seen to generally increase with time over the 208 months of in vivo duration covered by the retrievals in the study. The medial-lateral asymmetry of the wear does not appear to be significantly dependent on duration, however.

Biocompatible Materials↗
PubMed2005

Osteolysis after total knee arthroplasty: influence of tibial baseplate surface finish and sterilization of polyethylene insert. Findings at five to ten years postoperatively.

BACKGROUND: Debris displaced from the articular and backside surfaces of the polyethylene inserts of modular tibial components is considered a chief cause of osteolysis at the sites of total knee arthroplasties. One design of total knee replacement featured changes, over time, in the proximal surface roughness of the tibial baseplate and the method of sterilization of the polyethylene insert. We hypothesized that polishing the baseplate surface and sterilizing the insert with means other than gamma radiation in air had reduced the prevalence of osteolysis. METHODS: Three hundred and sixty-five posterior cruciate ligament-retaining Anatomic Modular Knee primary total knee arthroplasties were performed in 300 patients from 1987 to 1998. Anteroposterior and lateral radiographs of the knees were made within a five to ten-year postoperative interval. Two arthroplasty specialists independently examined the radiographs for evidence of osteolysis (defined as any nonlinear region of cancellous bone loss with delineable margins). RESULTS: Osteolysis was identified in 34% (eighty-two) of 242 knees treated with an insert that had been gamma-irradiated in air and affixed to a rough baseplate surface, and it was identified in 9% (nine) of ninety-eight knees treated with an insert that had been gamma-irradiated in an inert gas, or had not been irradiated, and joined to a polished surface. Osteolysis was associated with six factors, including one related to the patient (male gender), one related to the tibial baseplate (the proximal surface finish), three related to the polyethylene insert (the material from which it was machined, the sterilization method, and the shelf age), and one related to the technique (hyperextension of the femoral component relative to the tibial component). CONCLUSIONS: In this design of a total knee prosthesis, polishing the tibial baseplate counterface and implementing a more contemporary sterilization practice (as opposed to gamma radiation in air) noticeably diminished but did not eliminate osteolysis.

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PubMed1992

Distal femoral replacement with allograft/prosthetic reconstruction for treatment of supracondylar fractures in patients with total knee arthroplasty.

Large-segment distal femoral allografts were used in conjunction with non-linked total knee prostheses to reconstruct bone deficits following supracondylar fracture of the femur in seven patients with previous total knee arthroplasties. Three patients with multiple medical problems died of unrelated causes prior to a minimum 2 year follow-up. Indications for surgery were previously failed attempts at osteosynthesis and significant fracture comminution, osteopenia, and intercondylar extension or femoral component loosening. Specifics of the surgical technique included subperiosteal excision of the involved distal femur with retention of a soft tissue sleeve containing the collateral ligaments and reconstruction with a large-segment allograft and a stemmed, semiconstrained total knee prosthesis. Cement fixation using pressurized technique with intramedullary plugging of the tibial and femoral canal was routinely used to secure the prosthesis/allograft construct to the host bone. Postoperative complications included one dislocation, which was successfully treated closed, and one popliteal artery injury, which was successfully repaired. There were no postoperative infections. Two patients, however, had some degree of persistent instability, warranting bracing at the time of last follow-up. Using the Knee Society rating system, the average knee score for these patients was 71, and the average pain score and function score were 33 and 49, respectively. Range of motion averaged 96 degrees. All of the femoral components were well fixed at last follow-up. Results of this study indicate that large-segment distal femoral allografts used in conjunction with nonlinked knee prostheses can be an acceptable method of treatment of these difficult reconstructive problems.

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PubMed2004

Antibiotic-loaded bone cement spacers in two-stage management of infected total knee arthroplasty.

We reviewed the current use of spacers in the management of the infected knee prosthesis. There are two types of temporary spacers: block or non-articulating spacers and articulating or mobile spacers. Generally, spacers improve mobilisation and hasten recovery with shorter hospital stay between stages. Furthermore, spacers facilitate the second-stage procedure by maintaining joint space, and articulating spacers may also maintain range of motion. Last but not the least, the cost of spacers represents only a small fraction of the total expenses for management of infected knee arthroplasties.

Anti-Bacterial Agents↗
PubMed2007

Experimental evaluation of the biomechanical performances of a PMMA-based knee spacer.

Infection of knee prostheses is still one of the major concerns of the reliability over time of these implantable devices. The preferred treatment of this condition has turned out to be the use of a knee spacer in a two-stage reimplantation technique. The advantages of this technique associated with the use of a mobile spacer lies both in the possibility for the patient to move during the interim period, thus decreasing the risk of muscle contracture due to immobilisation, as well as in the ability to release antibiotics directly to the site of infection. The evaluation of the biomechanical properties of new mobile spacers preformed in three different sizes has been carried out subjecting the spacers to i) cyclic tests on a knee simulator for 500,000 walking cycles, ii) constraint tests in medio-lateral, antero-posterior and internal-external directions, iii) fatigue tests on the tibial tray. Particular attention was addressed to the evaluation of the mechanical resistance of the devices, to the quantity of wear debris produced during the tests and to the extent that such debris was influenced by the test parameters and geometrical dimensions of the spacers themselves. Results showed no sign of failure for any of the tested spacers, the constraint and fatigue behaviours were similar to those shown by a total knee prosthesis and the amount of debris turned out to be directly correlated to the size of the devices: in conclusion, the devices showed a good level of mechanical performance and, consequently, a sufficiently high degree of suitability for clinical use.

Anti-Bacterial Agents↗
PubMed2006

[Early clinical outcome of total knee arthroplasty for flexion-contracture deformity knees of different degrees].

OBJECTIVE: To make a retrospective analysis on an early clinical outcome of total knee arthroplasty (TKA) for the knees with different degrees of flexion-contracture deformities. METHODS: Ninety-seven knees of 65 patients undergoing total knee arthroplasty with the Scorpion posterior-stabilized knee prosthesis from January 2000 to December 2003 were reviewed, including 51 osteoarthritis patients (74 knees) and 14 rheumatoid arthritis patients (23 knees). Thirty-three patients underwent unilateral TKA, and 32 patients underwent bilateral TKA. The average range of motion (ROM) before operation was 82.8 degrees (range, 5-140 degrees). According to the preoperative flexion-contracture degrees of the knees, these patients were divided into 2 groups, group A and group B. Group A consisted of the patients with flexion-contracture less than 20 degrees (range, 0-15 degrees), and group B consisted of the patients with flexion-contracture not less than 20 degrees (range, 20-60 degrees). In group A, the average flexion-contracture degree, ROM, KSS (knee society score), and function score were 10.7 +/- 8.0 degrees, 104.6 +/- 20.0 degrees, 29.1 +/- 18.0, and 32.6 +/- 20.7, respectively. But the corresponding data were much worse in group B than in group A, which were 28.2 +/- 7.8 degrees, 60.8 +/- 26.6 degrees, 12.1 +/- 13.2, and 26.8 +/- 18.1. All the operations were primary total knee arthroplasty, and they were performed by the same group of surgeons. The time for the prosthesis installed lasted for 25.6 minutes, and the average tourniquet time was 34.7 minutes. Three or four days after operation, the patients began the continuous passive motion (CPM) and active functional exercise of the knee. RESULTS: The patients were followed up for an average of 2 years and 7 months(range, 8 mon-3.5 yr). During the follow-up period, the average flexion-contracture degree, ROM, KSS, and function score in group A were 0.4 +/- 2.1 degrees, 108.6 +/- 19.0 degrees, 82.1 +/- 13.8, and 72.3 +/- 29.1, respectively; and the corresponding data in group B were 1.3 +/- 3.2 degrees, 98.6 +/- 16.40, 75.9 +/- 8.2, and 81.4 +/- 26.9, respectively. There was no significant difference between the 2 groups. No revision or deep infection was found. CONCLUSION: The curative effect is mainly determined by the surgeon's good operational skills, rich clinical experience, and familiarity with the prosthesis, and it is not influenced by severity of the knee flexion-contracture deformity. The knee ROM after TKA, which has a "toward middle ROM" phenomenon, is influenced by many clinical factors. It is very important for the patient to perform a functional exercise of the knee as early as possible after operation.

Adult↗
PubMed1993

Improvement in gait one year after surgery for knee osteoarthrosis: a comparison between high tibial osteotomy and prosthetic replacement in a prospective randomized study.

The aim of this study was to analyse gait improvement one year after high tibial osteotomy and unicompartmental knee arthroplasty in patients with strictly unilateral osteoarthrosis of the medial compartment of the knee. Thirty-six patients, 18 men and 18 women, received a unicompartmental Brigham knee prosthesis and 23 patients, 10 men and 13 women, were operated on with a high tibial osteotomy. Clinical and radiographical assessments were supplemented by a functional test, measurements of thigh muscle torque with a Cybex II dynamometer and analysis on a force plate walkway with electrogoniometers. All patients were assessed prior to, and one year after surgery. Both groups showed overall clinical improvement, as assessed by the British Orthopaedic Association (BOA) score. Pain during walking decreased. The range of knee flexion remained unchanged. The ability to ascend and descend steps improved. The isokinetic thigh muscle torque remained unchanged. In the prosthetic group free walking speed increased from 1.03 to 1.09 m/s (p < 0.001). Step frequency and step length increased (p < 0.001). Single stance phase ratio increased from 0.96 to 0.99 (p < 0.01), indicating a more symmetrical gait. Double stance phase (% gait cycle) of both legs decreased (p < 0.001), indicating a faster transfer of weight during walking. In the osteotomy group, free walking speed did not increase. Step length of the uninvolved leg increased (p < 0.01). Double stance phase of the involved leg decreased (p < 0.001) and double stance phase of the uninvolved leg decreased (p < 0.01). Both groups improved after surgery and there was no difference between the groups.(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMedDate not supplied

[Mechanical loading and biomechanical problems of total joint surface replacement of the tibial plateau].

Recent reports of fractures of the tibial component of total knee prostheses have raised the question of their long term endurance. The mechanical load for the tibial plateau consists of the two forces deriving from the condyles of the femur. As the collateral and crucial ligaments always allow a little play for the femoral and tibial components, the location of the load of the condyles on the tibial plateau is either on the medial or lateral side depending on minor disturbances during gait. For a tibial plateau with only little medullary anchorage this load pattern means an alternating induction of compression and tensile stresses for the underlying bone. This alternating stress pattern is discussed as a possible mechanism of aseptic loosening of such tibial components. For two cases of such aseptic loosening and consecutive fracture of the tibial plateau of a metal backed unconstrained sledge knee prosthesis the radiologic findings are demonstrated and correlated to the biomechanical mechanisms described. It is demonstrated that the structural endurance of the tibial plateau does not withstand the mechanical stresses of such a situation of aseptic loosening. In these cases further loosening or fracture of the tibial plateau results.

Biomechanical Phenomena↗
PubMed1992

Range of motion after total condylar knee arthroplasty.

In this study the function of the knee measured at a medium-follow-up of 5-6 years was correlated with influencing factors concerning the implant of total condylar knee prosthesis in 90 patients. The only variable affecting postoperative extension was the preoperative range of extension whereas postoperative flexion was influenced by the preoperative flexion, valgus deviation of the preoperative AP tibial-femoral angle, position of the patella, and thickness of the resection of the distal femur cut.

Humans↗
PubMed2003

Impact of patellofemoral design on patellofemoral forces and polyethylene stresses.

BACKGROUND: The patellofemoral joint is a complex articulation because it relies mainly on soft-tissue constraints for stable tracking. The presence of a functioning posterior cruciate ligament and the design parameters of a total knee arthroplasty, such as trochlear groove alignment and cam-post configuration, can have a major effect on patellar biomechanics. METHODS: A finite element model of a knee implanted with femoral, tibial, and patellar components was generated. The model was validated by experimental testing of three cadaver knees implanted with a total knee prosthesis and a patellar force transducer. Two femoral component designs with different valgus angles of the trochlear groove (0 degrees and 7 degrees ) were studied. The effects of femoral rollback, rotation of the femoral component, medialization of the patellar implant, and alignment of the trochlear groove on patellar forces were then analyzed. RESULTS: A consistent reduction of up to 7% in patellofemoral forces was seen with progressive magnitudes of femoral rollback. The 0 degrees -aligned trochlear groove generated some lateral patellofemoral shear force throughout knee flexion. The 7 degrees -aligned trochlear groove generated medial shear force at flexion angles of <20 degrees and lateral shear force at flexion angles of >20 degrees. A more medial patellar component position reduced peak lateral shear forces by up to 10 to 15 N. However, a corresponding increase in medial shear forces was seen. CONCLUSIONS: This model predicted substantial reduction in patellofemoral lateral shear forces with a medialized patellar component or with external rotation of the femur. The model supported the hypothesis that femoral rollback reduces patellofemoral forces by improving the efficiency of the extensor mechanism. CLINICAL RELEVANCE: Patellofemoral complications after total knee arthroplasty include anterior knee pain, patellar subluxation and dislocation, abnormal polyethylene wear and damage, and loosening. There is a wide variation in the design features of current total knee prostheses, such as the sagittal radius, depth, and orientation of the trochlear groove of the femur and the geometry of the patellar component surface. The finite element model used in the present study can provide insight into the effects of design parameters on patellofemoral forces and on local contact stresses.

Arthroplasty, Replacement, Knee↗
PubMed1990

Long-term survivorship analysis of cruciate-sparing versus cruciate-sacrificing knee prostheses using meniscal bearings.

A comprehensive, interchangeable, low-contact-stress, mobile-bearing knee prosthesis system was developed and used over a 12-year period with both cemented and cementless fixation. Individual components of the system included a bicruciate-retaining meniscal bearing, a posterior cruciate-retaining meniscal bearing, and a cruciate-sacrificing, rotating-platform tibial component mated to the same femoral and rotating patellar components. Survivorship analysis of each implant type was performed to identify specific failure modes and trends for long-term survival of the implants in a wide variety of primary knee arthroplasties. Clinically, there were 46 prostheses of the bicruciate type followed for up to 12 years, 57 prostheses of the posterior-cruciate type followed for up to six years, and 108 prostheses of the rotating-platform type followed for up to ten years. All knees in this study had rotating-bearing patellar prostheses. Cumulative survivorship analysis using an end point of implant revision or a poor knee score revealed a small early failure rate of each implant in the first three years, associated with technical positioning or undersizing errors. This study indicates a predictable long-term survival of both cruciate-retaining and cruciate-sacrificing mobile-bearing knee prostheses as well as rotating-bearing patellar prostheses when used in primary knee arthroplasties that minimized technical errors of insertion.

Adult↗
PubMed2006

Influence of polyethylene constraint on tibial component fixation in total knee arthroplasty: follow-up report after 5 years.

The influence of articulating surface design of AMK total knee prosthesis (DePuy, Johnson & Johnson) on migration and radiographic outcome at 5 years was evaluated. The knees were randomly allocated to receive a flat or a concave insert with retention of the posterior cruciate ligament when preoperative deformity was less severe and either a concave or a posterior-stabilized insert with resection of the posterior cruciate ligament when deformity was more pronounced. In 64 knees, migration was measured with radiostereometry. The posterior-stabilized component displayed more varus-valgus tilting than the concave insert. Other statistically significant differences in migration were not seen. Radiolucent lines were frequently seen without differences between prosthesis groups.

Arthroplasty, Replacement, Hip↗
PubMed1992

A study of Chinese knee joint geometry for prosthesis design.

This study for the first time provides the geometric parameters of the knee joint of Chinese, which is indispensible to the design of knee prosthesis used for compatriotic patients. Thirty-five items, including linear, radial and angular measurements, were taken from 105 cadaveric knees and knee X-ray films of 1,100 subjects. The method and calculation for proper correction of the X-ray image magnification and joint cartilage space was established. Correlation was found to exist between the X-ray correction coefficients and the body weight, which formed the basis for individualized correction of X-ray measurements. Statistical analysis revealed that most of the linear and radial measurements were highly related while the angular measurements were independent of others. Principal component analysis showed that the width of femoral condyle might be taken as the leading index in determining the dimension of the knee, and regression functions were established to supply the serial parameters for prosthetic design. Multivariate discriminate functions could aid the selection of knee prosthesis.

Anthropometry↗
PubMedDate not supplied

Patellar complications in total knee replacement.

Over the past 26 years there have been marked changes in total knee arthroplasty components. Combinations of metal and polyethylene have been used in a variety of ways in the development of the three major components of the knee prosthesis. The metal-backed patellar implant that was considered state-of-the-art in the early 1980s soon came under criticism due to the high rate of failure and subsequent revision. A closer look at patellar resurfacing may suggest that some patellar compartments do just as well without being resurfaced.

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