Particle size and morphology of UHMWPE wear debris in failed total knee arthroplasties--a comparison between mobile bearing and fixed bearing knees.

Osteolysis induced by ultrahigh molecular weight polyethylene wear debris has been recognized as the major cause of long-term failure in total joint arthroplasties. In a previous study, the prevalence of intraoperatively identified osteolysis during primary revision surgery was much higher in mobile bearing knee replacements (47%) than in fixed bearing knee replacements (13%). We postulated that mobile bearing knee implants tend to produce smaller sized particles. In our current study, we compared the particle size and morphology of polyethylene wear debris between failed mobile bearing and fixed bearing knees. Tissue specimens from interfacial and lytic regions were extracted during revision surgery of 10 mobile bearing knees (all of the low contact stress (LCS) design) and 17 fixed bearing knees (10 of the porous-coated anatomic (PCA) and 7 of the Miller/Galante design). Polyethylene particles were isolated from the tissue specimens and examined using both scanning electron microscopy and light-scattering analyses. The LCS mobile bearing knees produced smaller particulate debris (mean equivalent spherical diameter: 0.58 microm in LCS, 1.17 microm in PCA and 5.23 microm in M/G) and more granular debris (mean value: 93% in LCS, 77% in PCA and 15% in M/G).     

Long-Term Clinical Outcomes and Survivorship After Total Knee Arthroplasty Using a Rotating Platform Knee Prosthesis : A Meta-Analysis

A systematic search identified 29 papers reporting survivorship and clinical and function Knee Society Scores (KSS) of 6437 total knee replacements using the Low Contact Stress (LCS) Rotating Platform (RP) mobile bearing knee. Low Contact Stress RP survivorship and KSS outcomes were compared with non-LCS knees in the Swedish knee registry at comparable time periods and in 2 independent systematic reviews of knee arthroplasty outcomes. There is a substantial body of mainly observational evidence supporting the LCS RP knee. Knee Society Score outcomes were comparable for LCS RP and non-LCS RP knees at up to 15 years of follow-up, with mean clinical and function scores ranging from 72 to 96 and 58 to 90, respectively. Survivorship of LCS RP knees up to 14 years was higher than that for all knees in the Swedish Knee Registry.     

Total knee arthroplasty using the kinematic rotating hinge prosthesis

Patients receiving a Kinematic Rotating Hinge total knee prosthesis with a 25-month minimum follow up were reviewed. A total of 46 patients and 54 knees were included in the study. A detailed clinical assessment was available on 38 knees. Twenty of these knees had primary arthroplasties performed with the Kinematic Rotating Hinge prosthesis and 18 knees had revision arthroplasty. Ninety-five percent of primary knees and 83% of revision knees caused no or mild pain postoperatively. Using the Brigham and Women's Hospital and Harvard Medical School knee rating system, 80% of primary knees and 61% of revision knees were rated as good to excellent. Using the criteria defined in this article, 90% of primary knees and 83% of revision knees were labeled as having a satisfactory result. Forty-five percent of primary components and 52% of revision components demonstrated lucent lines on radiographic review. Seven percent of primary knees and 20% of revision knees showed evidence of aseptic lucency progression in one or more zones. No radiographic evidence of aseptic loosening was noted in this review. Documented sepsis occurred in one primary knee and two revision knees. Patellar instability occurred in 21% of primary knees and 36% of revision knees, representing the major complication. The Kinematic Rotating Hinge prosthesis is intended for use in arthroplasty cases where there is functional absence of collateral ligament stability. This review suggests that a high percentage of satisfactory clinical results can be achieved with this prosthesis with long-term radiographic stability.     

Posterior cruciate ligament-retaining total knee arthroplasty in patients with rheumatoid arthritis

BACKGROUND: Although initial reports on posterior cruciate ligament-retaining total knee arthroplasty in patients with rheumatoid arthritis have been encouraging, a high rate of late instability necessitating revision has been reported recently. The purpose of the present prospective study was to analyze the results of posterior cruciate ligament-retaining total knee arthroplasty in patients with rheumatoid arthritis. METHODS: Seventy-two posterior cruciate ligament-retaining total knee arthroplasties in fifty-one patients with rheumatoid arthritis were studied prospectively. All procedures were performed with the Miller-Galante I prosthesis. Eighteen patients (twenty-four knees) died before the eight-year follow-up and one patient (two knees) was lost to follow-up, leaving forty-six knees (thirty-two patients) for review. These forty-six knees were evaluated clinically (with particular attention to posterior instability) and radiographically at annual intervals for a mean of 10.5 years (range, eight to fourteen years). RESULTS: Forty-four (95%) of forty-six knees had a good or excellent result at a mean of 10.5 years. However, nine (13%) of the original seventy-two knees had revision of the implant, with six of the revisions performed because of failure of a metal-backed patellar component. The rate of survival at ten years was 93% 4% with femoral or tibial revision for any reason as the end point and 81% 5% with any reoperation as the end point. There was no aseptic loosening in any knee. Posterior instability was identified clinically and/or radiographically in two (2.8%) of the original seventy-two knees; both unstable knees were in the same patient. CONCLUSION: Posterior cruciate ligament-retaining total knee arthroplasty yielded satisfactory clinical and radiographic results in patients with rheumatoid arthritis at intermediate-term follow-up (mean, 10.5 years). Therefore, we believe that it remains an excellent treatment option for these patients.     

Medium-term results of a mobile bearing total knee replacement.

Mobile bearing total knee arthroplasty kinematically allows the advantages of large and congruent surface contact and low contact pressures, while preserving flexion, extension, and rotation in knee motion. In allowing for these degrees of freedom, the interface between bone and component also is protected from high stress. The Self Aligning I total knee arthroplasty initially was implanted in patients after its development at the authors' institution in 1990. Between 1990 and 1994, 141 patients with osteoarthritis of the knee underwent 172 total knee replacements using this system. At average followup of 5.6 years (range, 5-8 years), clinical results using this system showed a 94% satisfaction rate (good or very good). Two revision surgeries have been performed for polyethylene wear, with none of the remaining knees showing evidence of discernible wear. Complications included four cases of deep infection, four cases where a press fit femoral component failed (nonporous coated) and the patients required revision surgery, four traumatic fractures (three patellar and one supracondylar), one popliteal artery occlusion, and one revision for stiffness. Three patients required manipulation under anesthesia for arthrofibrosis. Kaplan-Meier survival curves show the probability of survival to be 91.7%, with revision surgery for any reason as an end point, and 98.8% for revision surgery because of polyethylene wear as an end point. Following the initial learning curve with this prosthesis, the medium term results using this system show maintenance of clinical success. No progressive evidence of polyethylene wear with time has been found, supporting the concept of mobile bearing arthroplasty in extending the service life of total knee arthroplasty.     

The effectiveness of isolated tibial insert exchange in revision total knee arthroplasty.

BACKGROUND: Despite improvements in the design and manufacturing of the components used in total knee arthroplasty, wear of the polyethylene bearing remains a potential source of failure. One theoretical advantage of modular tibial implants is that, when the components are well fixed, patients with wear or instability of the tibial insert can be treated with isolated polyethylene exchange. The aim of this study was to assess the results of isolated tibial insert exchange during revision surgery in a relatively large, consecutive group of patients. METHODS: From 1985 through 1997, we performed fifty-six isolated tibial insert exchanges in fifty-five patients (twenty-nine men [one man had bilateral revision] and twenty-six women; mean age, sixty-six years) primarily because of wear or instability. Patients with loosening of any of the components, a history of infection, severe stiffness of the knee, recognized malposition of any component, or problems with the extensor mechanism were excluded. Twelve knees had had one, two, or three prior revisions. The duration of follow-up averaged 8.3 years (range, 1.6 to 16.2 years) after the index arthroplasty and 4.6 years (range, two to fourteen years) after the revision. RESULTS: The mean Knee Society knee and function scores improved from 56 and 50.9 points prior to the revision to 76 and 59 points at the time of final follopcow-up. Fourteen (25%) of the fifty-six knees subsequently required rerevision at a mean of only three years (range, 0.5 to 6.8 years) after the tibial insert exchange. The cumulative survival rate at 5.5 years was 63.5% (95% confidence interval, 14.4%, with nineteen patients remaining at risk). Of the twenty-seven knees with preoperative instability, eight were rerevised and another four were considered failures because of severe pain. Of the twenty-four knees that were treated with the index revision because of wear of the insert, five were rerevised. In addition, one extremity in this group was amputated above the knee as a result of chronic osteomyelitis of the ankle concomitant with chronic pain at the site of the total knee arthroplasty and another two inserts were considered failures because of severe pain. CONCLUSIONS: Isolated tibial insert exchange led to a surprisingly high rate of early failure. Tibial insert exchange as an isolated method of total knee revision should therefore be undertaken with caution even in circumstances for which the modular insert was designed and believed to be of greatest value.     

Comparison of metal-backed and all-polyethylene tibial components in cruciate condylar total knee arthroplasty

An evaluation of 78 knees in 63 patients using the cruciate-sparing total condylar prosthesis was performed. At a mean of 10 years following the arthroplasty there were 86% good or excellent results in knees with an all-polyethylene tibial component compared to 95% with a metal-backed tibial component (NS). Survivorship at 10 years using an endpoint of revision was 96% (NS) in both groups; using an endpoint of revision or poor knee score was 85% (NS) in the metal-backed compared to 92% (NS) in the all-polyethylene groups; using an endpoint of revision, poor knee score, or complete radiolucent line was 85% in the metal-backed compared to 90% (NS) in the all-polyethylene groups. There were no significant differences in the frequency of radiolucent lines at the last evaluation. Two percent of the tibial components in the metal-backed group had complete radiolucent lines compared to none in the allpolyethylene group. The cruciate-sparing total condylar prosthesis provides satisfactory results with no significant differences between the metal-backed or all-polyethylene tibial components at 10 years.     

Complex primary and revision total knee arthroplasty using the condylar constrained prosthesis: An average 5-year follow-up

The condylar constrained total knee arthroplasty was performed on 29 patients undergoing 33 procedures and were reviewed clinically and radiographically at an average follow-up of 5 years (range, 2–10 years). There were 21 women and 8 men. The average age at the time of surgery was 70 years (range, 32–84). Of the 16 knees that were revision total knee arthroplasties, 8 had a previous infected total knee arthroplasty, and 17 knees had severe deformities requiring, the use of the condylar constrained prosthesis. The patients were rated according to the Knee Society clinical and radiological evaluation protocol. Measurements of femoral and tibial component position were obtained as well as femoral tibial angle, patella position, and cement bone radiolucencies. All clinical measurements were made by an independent physical therapist. Clinical results revealed an improvement from an average preoperative knee score of 38 points to an average postoperative score of 86 points. The clinical results for 19 (58%) knees were excellent, 8 (24%) had a good result, 1 (3%) was fair, 2 (6%) were poor, and 3 (9%) were failures. The patients' average functional levels increased from 24 to 58. The final average flexion was 96°. Three knees have been revised (9%). One was revised for recurrent infection, one for periprosthetic fracture, and one for mechanical loosening of the tibial component. There were no other knees with evidence of radiologic loosening. We conclude that the condylar constrained total knee prosthesis provides an acceptable solution for revision and complex primary total knee replacements at an intermediate follow-up term of 5 years.     

Biomechanical comparison of fixed‐ and mobile‐bearing for unicomparmental knee arthroplasty using finite element analysis

Unicomparmental knee arthroplasty (UKA) is a popular alternative to total knee arthroplasty (TKA) and high tibial osteotomy for unicompartmental knee conditions, especially in young patients. However, failure of UKA occurs due to either progressive osteoarthritis (OA) in the other compartment or wear on the polyethylene (PE) insert. This study used finite element (FE) analysis to investigate the effects of PE insert contact pressure and stress in opposite compartments for fixed‐ and mobile‐bearing UKA. Analysis was performed using high kinematics displacement and rotation inputs, which were based on the kinematics of the natural knee. ISO standards were used for axial load and flexion. The mobile‐bearing PE insert had lower contact pressure than the fixed‐bearing PE insert. With the mobile‐bearing UKA, lower stress on the opposite compartment reduces the overall risk of progressive OA in the knee. The fixed‐bearing UKA increases the overall risk of progressive OA in the knee due to higher stress on the opposite compartment. However, the PE insert of mobile‐bearing showed pronounced backside stress at the inferior surface. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:338–345, 2014.     

Total knee arthroplasty without patellar resurfacing in isolated patellofemoral osteoarthritis

Thirty-one patients (33 knees) with symptomatic patellofemoral osteoarthritis and minimal tibiofemoral changes underwent LCS total knee arthroplasty without patellar resurfacing. Average age was 73 years (range, 58-89 years) with a female-to-male ratio of 5:1. Average follow-up was 20 months (range, 12-40 months). All except 4 patients had grade 3 or 4 patellofemoral osteoarthritis. Preoperatively, all patients had significant knee pain. Sleep disturbance was reported in 21 patients. All but 10 patients required walking aids. Average range of motion was 108 degrees (range, 80-125 degrees ). At latest review, 21 knees were pain-free, the remaining 12 knees being described as having only occasional knee pain. Two patients continued to have night pain. Average range of motion was 104 degrees (range, 70-135 degrees ). Lateral patellar tilt improved in all but 5 knees by an average of 7 degrees (range, 1-26 degrees ). Patellar congruency improved in all but 3 knees by an average of 18% (range, 3-63%). None of the patients to date have required revision surgery. Total knee arthroplasty without patellar resurfacing is an effective option in older patients with isolated patellofemoral osteoarthritis.     

10-year evaluation of the cementless low-contact- stress rotating-platform total knee arthroplasty

We present the clinical and radiographic outcomes of the cementless low-contact-stress (LCS) rotating-platform total knee arthroplasty. Overall, 423 prostheses were implanted in 393 consecutive patients (30 patients had bilateral total knee replacement) for primary varus gonarthrosis (381 patients) and rheumatoid arthritis (12 patients). There were 81 men and 312 women with a mean age of 73 years (range, 58-85 years). Patella replacement was not performed in any case. Clinical and radiographic evaluation was performed using the Knee Society Score (KSS) and the Knee Society Assessment Form, respectively. The mean follow-up was 10 years (range, 5-15 years). Three patients were lost to follow-up. Survival of the prostheses was 98% at 10 years; three prostheses required revision for deep infection, bearing dislocation, and periprosthetic fracture. The mean KSS improved significantly, from 42 and 44 points preoperatively to 90 and 79 points, respectively, at the latest evaluation (P < 0.001); results were excellent in 278 cases, good in 106, fair in 27, and poor in nine. Radiolucent lines were observed in 80 cases; revision arthroplasty was not performed in any of these cases. Complications included deep infection in one patient, bearing dislocation in one, skin necrosis in four, and a supracondylar fracture in one. The cementless LCS rotating-platform total knee arthroplasty is associated with excellent mid- and long-term results for patients with osteoarthritis and rheumatoid arthritis of the knee.     

Total knee replacement in previous recipients of fresh osteochondral allograft transplants

BACKGROUND: Fresh osteochondral allograft transplantation is a treatment option for young patients with osteochondral lesions of the knee. The present study evaluated the surgical complexity of, and the prevalence of complications related to, total knee arthroplasty in patients who had had a previous osteochondral graft transplantation. METHODS: A retrospective analysis was performed on thirty-three consecutive patients (thirty-five knees) who underwent total knee arthroplasty from 1974 to 2000 after having had a previous transplantation of a fresh osteochondral allograft into the same knee. The mean duration of follow-up was ninety-two months. Perioperative data were analyzed with regard to etiology, preoperative impairment, intraoperative technical complications, early and late postoperative complications, and postoperative functional and subjective outcomes. The Knee Society clinical rating system was used for clinical evaluation beginning in 1990. RESULTS: Four knees required additional techniques for exposure. Three knees required stemmed components, one knee required a tibial augment, and two knees required morselized grafts. The mean Knee Society objective score (available for eighteen knees) improved from 34.7 preoperatively to 87.9 at the time of the latest follow-up, and the mean Knee Society function score improved from 45 to 82. The mean range of motion of all knees improved from 85 degrees to 105 degrees . Six of the thirty-five knees underwent revision total knee arthroplasty because of aseptic loosening, with two knees being revised within two years after the index total knee arthroplasty. CONCLUSIONS: Total knee arthroplasty after previous fresh osteochondral allograft transplantation provides improvements in knee function and range of motion, with manageable technical difficulties. Compared with routine total knee arthroplasty, an increased rate of early revision can be expected.     

Revision total knee arthroplasty for failed unicompartmental replacement

The results in nineteen patients (twenty-one knees) who had a failed unicompartmental knee replacement followed by a revision total knee arthroplasty were evaluated. There were twelve excellent, four good, one fair, and two poor results. The interval between the unicompartmental replacement and the revision total knee arthroplasty ranged from eight months to eight years. At the time of the revision, a major osseous defect was found in sixteen knees (76 per cent). The duration of follow-up after the revision ranged from two to ten years. At the most recent follow-up examination, radiographs revealed at least one radiolucent line in thirteen knees (62 per cent). The technical difficulties associated with the revision operation are evidence that unicondylar arthroplasty is not a conservative procedure that allows a total knee arthroplasty to be done easily later. The results also do not support the argument that a revision performed after failure of a unicondylar arthroplasty is less technically demanding than one performed after a failed primary total knee arthroplasty.     

Eighteen-Year Outcome of an Uncemented "Meniscal Bearing", Cruciate-Retaining Total Knee System

BackgroundThe aim of this study is to evaluate the survival, radiographic, and functional outcomes of the uncemented “meniscal bearing” cruciate-retaining Low Contact Stress (LCS) (DePuy Synthes, Warsaw, IN, USA) total knee system after a long-term follow-up period.MethodsA total of 56 patients (67 knees) who received an uncemented “meniscal bearing” cruciate-retaining LCS total knee system between 2000 and 2005 were retrospectively reviewed. Patients were 64 ± 7 years old with osteoarthritis as the indication for arthroplasty. The survivorship, radiographs, and patient-reported outcome measures (PROMs) were analyzed.ResultsThe all-cause survival after 5, 10, 15, and 18 years was 97.0%, 93.8%, 92.0%, and 92.0%, respectively. Survival with revision for aseptic loosening as an end point was 98.4% at 5 years and 96.7% at 10, 15, and 18 years. Reasons of revisions and their interventions consisted of anterior knee pain requiring secondary patellar resurfacing (n = 3, 60%), polyethylene wear requiring an insert exchange (n = 2, 40%), and bearing spin-out requiring an insert exchange (n = 1, 20%). Two of the 5 revision cases developed aseptic loosening of the tibial component later on during the study period. A radiographic analysis demonstrated radiolucent lines in 14/47 implants (30%) after 12.0 ± 3.8 years, but were not revised, respectively. After a mean follow-up of 18.5 years, PROMs (n = 20) were found comparable with the 1-year postoperative PROMs of all implants reported by the LROI (Dutch Arthroplasty Register).ConclusionThis present study demonstrates good results of the uncemented “meniscal bearing” cruciate-retaining LCS total knee system toward survival and functional outcomes after a long-term median follow-up of 17.5 years.Level of EvidenceTherapeutic retrospective cohort study, LEVEL III.     

Total knee arthroplasty for steroid-induced osteonecrosis.

There have been only a few reports that evaluate the outcome of total knee arthroplasty in patients with steroid-induced osteonecrosis of the knee. We retrospectively reviewed 31 total knee arthroplasties in 24 patients with confirmed steroid-induced osteonecrosis of the knee. The average follow-up was 64 months. Of surviving knees, 92% had significant improvement in knee scores. Five knees (16%) required a revision procedure. Reasons for revision were aseptic loosening in 3 knees and sepsis in 2 knees. Complications not requiring revision occurred in 6 of 31 knees (19%). Survivorship of total knee arthroplasty to revision in patients with steroid-induced avascular necrosis of the knee was 84% at 5 years. Although there was a slightly higher complication rate, this may, in part, be due to the severity of the patients' underlying disease processes. Total knee arthroplasty can be a successful procedure for chronically ill patients with steroid-induced osteonecrosis.     

Total knee arthroplasty in juvenile rheumatoid arthritis

BACKGROUND: There is a paucity of reports regarding the long-term results of total knee arthroplasty in patients with juvenile rheumatoid arthritis. The purpose of this study was to evaluate the outcome of total knee arthroplasty in patients with juvenile rheumatoid arthritis who had been followed for a minimum of twelve years. METHODS: Eight consecutive patients (fifteen knees) with juvenile rheumatoid arthritis underwent total knee arthroplasty at an average age of 16.8 years. Clinical evaluation of pain status, range of motion, and the ability to walk and radiographic evaluation of the alignment of the knees and component loosening were performed preoperatively and at a mean of 15.5 years postoperatively. RESULTS: All patients had substantial pain and functional limitation before the surgery, and seven of the eight patients used a wheelchair. At the time of the latest follow-up, which was after revision surgery in three patients, all of the knees were pain-free and six patients were able to walk about the community. The mean arc of motion had increased from 36 degrees to 79 degrees . The final radiographic evaluation showed that thirteen of the fifteen knees were in neutral alignment and two were in valgus. Failure, defined as revision of any of the components or definite loosening as seen radiographically, occurred in three knees. CONCLUSIONS: Good results, in terms of pain relief and restoration of function, were seen at a minimum of twelve years following total knee arthroplasty in our series of patients with juvenile rheumatoid arthritis. This procedure is a reasonable option when nonoperative therapy has been inadequate for patients with severe disability and pain in this relatively young population.     

Conversion of failed modern unicompartmental arthroplasty to total knee arthroplasty

Between January 1983 and January 1991, 29 patients (31 knees) with a failed Robert Brigham metal-backed knee arthroplasty (Johnson & Johnson, Raynham, MA) underwent revision to a total knee arthroplasty (TKA). Twenty-five patients had osteoarthritis, three avascular necrosis, and one rheumatoid arthritis. The average patient age was 72.3 years (range, 49–88 years), and the average weight was 179 lb. (range, 112–242 lb.). The interval between the primary and secondary index procedures averaged 62 months (range, 7–106 months), and mean postrevision follow-up period was 45 months (range, 24–104 months). The primary mechanism of failure of the UKA was tibial polyethylene wear in 21 knees and opposite compartment progression of arthritis in 10 knees. Sixteen knees had particulate synovitis with dense metallic staining of the synovium. At revision, the posterior cruciate ligament was spared in 30 knees and substituted in 1 knee. Restoration of bony deficiency at revision required cancellous bone—graft for contained defects in seven knees, tibial wedges in four knees, and femoral wedges in two knees. No defects received structural allografts. The data suggest that failed, modern unicompartmental knee arthroplasty can successfully be converted to TKA. In most cases, the posterior cruciate ligament can be spared and bone defects corrected with simple wedges or cancellous grafts. Moreover, the results of revision of failed unicompartmental knee arthroplasty are superior to those of failed TKA and failed high tibial osteotomy and comparable to the authors' results of primary TKA with similar-length follow-up periods. Although these results are encouraging, longer-term follow-up evaluation is required to determine survivorship of these revision arthroplasties.     

Comparison of the Clinical Outcomes after Total Knee Arthroplasty with the LCS Rotating Platform Mobile Bearing Knee System and the PFC Sigma RP-F Mobile Bearing Knee System

Background

We compared clinical outcomes after total knee arthroplasty with the Low Contact Stress (LCS) rotating platform mobile bearing knee system and the Press Fit Condylar Sigma rotating platform high flexion (PFC Sigma RP-F) mobile bearing knee system.

Methods

Fifty cases of total knee arthroplasty were performed with the PFC Sigma RP-F mobile bearing knee system and sixty-one cases were performed with the LCS mobile bearing total knee arthroplasty. The average duration of follow-up was 2.9 years.

Results

The mean Hospital for Special Surgery (HSS) knee score was 62.1 (range, 52 to 75) in the LCS group and 61.9 (range, 50 to 74) in the Sigma RP-F group preoperatively, and 90.1 (range, 84 to 100) in the LCS group and 89.8 (range, 83 to 100) in the Sigma RP-F group at the final follow-up. The mean preoperative flexion contracture was 6.7° (range, 0° to 10°) in the LCS group and 9.3° (range, 0° to 15°) in the Sigma RP-F group preoperatively. The mean range of motion was 124.6° (range, 105° to 150°) in the LCS group and 126.1° (range, 104° to 145°) in the Sigma RP-F group at the final follow-up.

Conclusions

After a minimum duration of follow-up of two years, we found no significant differences between the two groups with regard to the range of knee motion or the clinical or radiographic results.