Outcome of isolated tibial polyethylene insert exchange after uncemented total knee arthroplasty: 27 patients followed for 8-71 months

Background The outcome of performing isolated tibial polyethylene insert exchange (ITPIE) after total knee arthroplasty (TKA) is under debate. We evaluated the survival probability of ITPE after uncemented TKA.

Method 27 patients (27 knees) with an ITPIE performed mean 9 (0.9-17) years after the initial TKA were included in the study (22 patients also had the patellar component replaced simultaneously). All patients had their exchange performed at our department between 1997 and 2001 and had their latest follow-up examination mean 40 (8-71) months after the exchange.

Results During the follow-up, 2 patients had total knee revision because of aseptic loosening and 2 patients had isolated patella component exchange (in 1 of the patients, combined with a new ITPIE). Kaplan-Meier survival analysis gave a survival probability of 80% at 34 months of follow-up.

Interpretation The short-term survival after an ITPIE was similar to that of a total knee revision with exchange of all components. Since the ITPIE is a much smaller operation with fast rehabilitation, we recommend it in elderly patients with a well-fixed and wellaligned prosthesis without surface damage of the components.     

Angled polyethylene insert exchange for sagittal tibial malalignment in total knee arthroplasty

Tibial component malposition in total knee arthroplasty can cause early failure and result in the need for revision surgery. Excessive posterior slope of the tibial component is an uncommon, but difficult problem to correct. Component revision risks additional loss of deficient posterior tibial bone stock. As an alternative, a custom-made angled insert can correct for component malalignment and possibly avoid prosthesis revision. In this report, we present the use of a custom-angled bearing for sagittal alignment correction with 6-year follow-up. The procedure is simple and has little risk, but the cost, potential limitations for correcting excessive deformity, and uncertainty of long-term results make the use of angled inserts a rare and selective procedure. However, when possible to use, an angled insert may be a useful alternative to complete prosthetic revision.     

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.     

The incidence of modular tibial polyethylene insert exchange in total knee arthroplasty when polyethylene failure occurs

One of the primary reasons for utilizing modular tibial polyethylene inserts (MTPI) at the time of total knee arthroplasty is to have the ability to simply exchange the polyethylene at the time of revision surgery when polyethylene failure has occurred. During a 2-year period from January 1993 to December 1994, 62 revision total knee arthroplasties were reviewed from five different institutions in North America, which were performed secondary to modular tibial insert failure. In 55 cases (88.7%), significant scoring and/or damage to the femoral and/or tibial components occurred necessitating revision of one or both components. This series does not support the premise that polyethylene exchange is common at the time of revision surgery for MTPI failure. Of the patients 88.7% had MTPI failure resulted in femoral and/or tibial component revision secondary to surface damage to the femoral component and/or tibial component baseplate. In order to avoid femoral and tibial component wear secondary to MTPI failure, early recognition is necessary to allow the much simpler operation consisting of polyethylene liner exchange only.     

Clinical results of modular polyethylene insert exchange with retention of total knee arthroplasty components

BACKGROUND: Modular polyethylene inserts have enabled surgeons to perform an isolated tibial insert exchange while retaining well fixed components. The purpose of this study was to review the results of insert revision and to clarify the role of this option compared with that of revision total knee arthroplasty. METHODS: Fifty-six patients (sixty-three knees) were managed with revision of a tibial polyethylene insert and retention of well aligned and stable femoral and tibial components. The implants had been in situ for an average of fifty-nine months (range, two to 108 months) at the time of the insert exchange. The inserts that were removed at the time of exchange were evaluated with regard to wear of the articular surface according to the classification system of Hood et al. and with regard to undersurface wear according to the method described by Wasielewski et al. Forty-eight knees were followed for an average of 7.4 years (range, 3.0 to 12.2 years) after the insert exchange. Knees that did not require an additional operation were considered to have had a successful exchange. RESULTS: Seven of the forty-eight exchanges failed, at an average of fifty-four months, because of accelerated wear of the new insert. All seven knees required complete revision of all components. Of the twenty-two exchanges that were performed because of severe wear of the primary insert, six (27 percent) failed at an average of less than five years; thus, knees in which the exchange was performed because of advanced wear were more likely to fail again (p < 0.05). In addition, primary inserts that were removed from knees in which the exchange procedure subsequently failed had higher delamination scores than those that were removed from knees in which the exchange was successful (p < 0.05). Most of the primary inserts had substantial undersurface wear at the time of the exchange procedure. Metallosis (thirty knees) and osteolysis (nineteen knees) were unrelated to failure of the exchange. CONCLUSIONS: An isolated revision of the tibial polyethylene insert should not be performed when there is accelerated wear of the insert with severe delamination and grade-3 or 4 undersurface wear within ten years after the primary procedure. Because a variety of patient-related, implant-related, and technical factors influence polyethylene wear, the orthopaedist must consider multiple variables whenever contemplating a limited revision.     

Poor outcomes of isolated tibial insert exchange and arthrolysis for the management of stiffness following total knee arthroplasty.

BACKGROUND: Severe stiffness after total knee arthroplasty is a debilitating problem. In patients with securely fixed and appropriately aligned components, arthrolysis of adhesions and exchange to a thinner tibial polyethylene insert may appear to be a reasonable and logical solution. We reviewed our experience with this procedure to determine its efficacy. METHODS: From 1992 through 1998, seven knees with marked stiffness after total knee arthroplasty were treated at our institution with arthrolysis of adhesions and conversion to a thinner tibial polyethylene insert. Only patients in whom the total knee prosthesis was well aligned, well fixed, and not associated with infection were included. There were five women and two men with a mean age at revision of sixty-one years (range, thirty-eight to seventy-four years). The average time to revision was twelve months, and the mean arc of motion prior to revision was 38.6 degrees (range, 15 degrees to 60 degrees ). The duration of follow-up after the insert exchange averaged 4.2 years (range, two to eight years). RESULTS: Mean Knee Society pain and function scores changed from 44 and 36.4 points preoperatively to 39.6 and 46 points at the time of final follow-up. Two knees were rerevised, one because of infection and the other because of aseptic loosening of the components. The five remaining knees were painful and stiff at the time of final follow-up. Four of these five knees were severely painful, and one knee was moderately and occasionally painful. The mean arc of motion of these five knees was 58 degrees (range, 40 degrees to 70 degrees ) at the time of final follow-up. CONCLUSION: Isolated tibial insert exchange, arthrolysis, and débridement failed to provide a viable solution to the difficult and poorly understood problem of knee stiffness in a group of carefully selected patients following total knee arthroplasty. We therefore have little enthusiasm for the continued use of this strategy.     

Locking mechanism failure between tibial baseplate and polyethylene insert in cruciate retaining total knee arthroplasty

We describe a case of total knee arthroplasty performed with one type of cruciate retaining knee prosthesis (Vanguard CR, Zimmer Biomet), wherein failure of locking mechanism occurred between the tibial baseplate and the polyethylene insert 10 months after initial surgery. While there are very few case reports in literature describing such locking mechanism failure, all of these have been in constrained and posterior stabilized knees. This case, to the best of our knowledge is the first such case seen with a cruciate retaining knee design. A 73-year old lady, having undergone left total knee arthroplasty with the above-mentioned prosthesis, presented 10 months after the index surgery with a 3-week history of worsening knee pain and medially protruding hardware. She mentioned an episode of minor twisting of her knee after which she developed pain and swelling over the medial aspect, and was found to have the locking bar backed out on X-rays. She underwent revision surgery, wherein the locking bar was found to have buttonholed through the medial capsule. She underwent polyethylene liner exchange, with a new locking bar. There was no evidence of infection. Her symptoms fully settled following revision surgery.     

Monoblock versus modular polyethylene insert in uncemented total knee arthroplasty

Background and purpose — Backside wear of the polyethylene insert in total knee arthroplasty (TKA) can produce clinically significant levels of polyethylene debris, which can lead to loosening of the tibial component. Loosening due to polyethylene debris could theoretically be reduced in tibial components of monoblock polyethylene design, as there is no backside wear. We investigated the effect of 2 different tibial component designs, monoblock and modular polyethylene, on migration of the tibial component in uncemented TKA.

Patients and methods — In this randomized study, 53 patients (mean age 61 years), 32 in the monoblock group and 33 in the modular group, were followed for 2 years. Radiostereometric analysis (RSA) was done postoperatively after weight bearing and after 3, 6, 12, and 24 months. The primary endpoint of the study was comparison of the tibial component migration (expressed as maximum total point motion (MTPM)) of the 2 different implant designs.

Results — We did not find any statistically significant difference in MTPM between the groups at 3 months (p = 0.2) or at 6 months (p = 0.1), but at 12 and 24 months of follow-up there was a significant difference in MTPM of 0.36?mm (p = 0.02) and 0.42?mm (p = 0.02) between groups, with the highest amount of migration (1.0?mm) in the modular group. The difference in continuous migration (MTPM from 12 and 24 months) between the groups was 0.096?mm (p = 0.5), and when comparing MTPM from 3–24 months, the difference between the groups was 0.23?mm (p = 0.07).

Interpretation — In both study groups, we found the early migration pattern expected, with a relatively high initial amount of migration from operation to 3 months of follow-up, followed by stabilization of the implant with little migration thereafter. However, the modular implants had a statistically significantly higher degree of migration compared to the monoblock. We believe that the greater stiffness of the modular implants was the main reason for the difference in migration, but an initial creep in the polyethylene metal-back locking mechanism of the modular group could also be a possible explanation for the observed difference in migration between the 2 study groups.     

Changes in postoperative extension angle after total knee arthroplasty: Effect of polyethylene insert thickness

BackgroundFlexion contracture is a serious complication after total knee arthroplasty (TKA). Polyethylene insert (PE) thicker than the extension gap during surgery causes flexion contracture. The purpose of this study was to identify the changes over time in postoperative extension angle and the correlation between extension gap and PE thickness.MethodsOverall, 127 knees were analyzed to evaluate the changes in extension angle over time. “Gap difference” was defined as the distance obtained by subtracting the extension gap from the PE thickness. Patients were divided into four groups according to gap difference (0–3 or greater mm). We evaluated the correlation of gap difference and changes in postoperative extension angle over time.ResultsThe extension angles of all knees were ?4.2 ± 3.9 (deg. mean ± s.d.) at surgery, ?5.9 ± 5.7 at 3 months, ?3.4 ± 5.4 at 6 months, and ?1.3 ± 5.4 at 2 years. Gap difference was negatively correlated with the extension angle at surgery and at 2 years (r = 0.40, r = 0.36). The extension angles at 2 years in each group (groups 0, 1, 2, 3 or greater) were 2.0°±4.7°, ?0.8°±5.3°, ?3.4°±5.3°, ?4.0°±4.1° (p < 0.05), respectively.ConclusionsThe extension angle became worse at 3 months compared to that at surgery (p = 0.01) and then improved until 2 years. The correlation between gap difference and extension angle was maintained at 2 years, and thicker PE caused flexion contracture even after 2 years. Hence, PE selection considering the extension gap is important.     

Polyethylene insert exchange for wear after total shoulder arthroplasty

Virtually no information is available in the literature to guide clinical decision-making in regard to modular polyethylene exchange with metal-backed glenoid components in total shoulder arthroplasty for the indication of polyethylene wear. This level IV study reports our experience with exchange of the modular polyethylene glenoid component during revision total shoulder arthroplasty. We retrospectively identified 12 shoulders in 11 patients who underwent exchange of the modular polyethylene glenoid component during revision arthroplasty. The primary reason for revision arthroplasty with polyethylene exchange was wear-through or displacement of the polyethylene portion of the glenoid component, but rotator cuff tearing and instability often coexisted. The average follow-up from time of revision to latest evaluation or repeat revision arthroplasty was 68 months. Preoperative pain was a mean of 4.5 (range, 4-5), and postoperative pain was a mean of 2.6 (range, 1-5). Preoperative average active forward elevation was 93 degrees, and external rotation was 51 degrees. Postoperative active forward elevation was 89 degrees, and external rotation was 64 degrees. Average patient satisfaction was rated as the same. According to the modified Neer rating system, 4 shoulders (33%) had a satisfactory result, and 8 (62%) had an unsatisfactory result. Polyethylene exchange of glenoid component after total shoulder arthroplasty can be an effective treatment option in patients who do not have coexistent rotator cuff tear or instability. For most, instability, rotator cuff tear, and glenoid wear occur together, and this is a challenging problem to treat successfully.     

Arthroscopy after dysfunctional total knee arthroplasty: Two cases with peg fracture of the polyethylene insert

Summary: Arthroscopy may be indicated in patients with painful dysfunction of the knee joint following total joint replacement. Arthrofibrosis, impacted soft tissue, patellar malalignment, synovialitis, and intra-articular foreign bodies can be treated with the promise of a good outcome. Two cases of peg fracture of the polyethylene insert of a semiconstrained knee prosthesis are presented. In relation to fracture position, instability and locking-up of the joint were clinically manifest. When arthroscopy is used judiciously, its merits are found in ensuring the proper diagnosis and in the reliable planning of treatment. When the patient reports locking-up of the joint, the rare complication of a polyethylene peg fracture must be considered.Arthroscopy: The Journal of Arthroscopic and Related surgery, Vol 16, No 8 (November-December), 2000: pp 21e–21e     

高屈曲垫片与标准垫片全膝关节置换的早期疗效对照研究

目的 比较采用高屈曲垫片与标准垫片的膝关节假体行全膝关节置换术的早期临床疗效.方法 2005年2月至2008年7月采用GenesisⅡ型膝关节假体行初次全膝关节置换术203例216膝,随机分为高屈曲垫片组(A组,98例107膝)与标准垫片组(B组,105例109膝).术前两组膝关节协会评分(Knee Society score,KSS)系统中的膝评分及膝关节功能评分和膝关节活动度的差异均无统计学意义.术后2周、6周、3个月、6个月、1年及以后每年随访1次.以术后1年为观测终点,观察并发症发生情况,比较两组的KSS膝评分、KSS膝关节功能评分及膝关节活动度.结果 术后1年A组随访91例98膝,B组94例96膝.膝关节主动屈伸活动度A组121.1°±6.9°,B组118.6°±8.1°;膝关节主动屈伸活动度改善度A组17.1°±13.3°,B组16.1°±18.8°;膝关节被动屈伸活动度A组127.2°±7.1°,B组121.0°±7.8°;KSS膝评分A组(86.9±7.6)分,B组(87.5±6.8)分;KSS膝关节功能评分A组(91.2±8.7)分,B组(90.1±9.3)分.其中两组膝关节被动屈伸活动度的差异有统计学意义.术后发生深静脉血栓形成A组4例,B组3例;切口脂肪液化A组3例,B组5例;术后粘连A组2例,B组3例.结论 应用GenesisⅡ型膝关节假体行全膝关节置换术时,选择高屈曲垫片者术后早期膝关节被动屈伸活动范围大于选择标准垫片者,而在主动屈伸活动范围及关节功能评分方面无差异.     

Micromotion in cemented rotating platform total knee arthroplasty: cemented tibial stem versus hybrid fixation

INTRODUCTION: Improving the longevity and reliability of cemented total knee arthroplasty (TKA) remains a major step to achieve. It is still unclear, whether a cemented tibial stem reduces micromotion of the tibial tray and produces therefore a better initial stability or not. The higher conformity of rotating platform design and the possible rotary forces to the tibial platform may produce higher micromotion when the tibial stem remains cementless (hybrid fixation). MATERIALS AND METHODS: An in vitro study was performed using the PFC mobile bearing tibial tray (DePuy, Warswa, IN, USA) to test the hypothesis that the addition of cement surrounding the tibial stem reduces micromotion of the tibial tray in cemented TKA with mobile bearing design. Ten tibial trays with mobile design were implanted in sawbones with a 3-mm cement mantle beneath the baseplate of the tibial tray and with or without the cemented stem. Tibial trays were loaded additionally in the ventral, lateral, medial and posterior positions with 2,500 N using the Zwick Z010 instrumentation and HBM pick up Hottinger Baldwin. RESULTS: In this study, a significant increased mean maximum liftoff was found when only cementing the tibial baseplate (hybrid fixation), compared to the fully cemented tibial tray (P<0.02). CONCLUSION: In conclusion, the stem of mobile bearing tibial components should be cemented to provide increased micromotion and earlier loosening.     

Outcome in primary cemented total knee arthroplasty with or without drain: A prospective comparative study

Background:

Suction drain insertion is a common practice in orthopedic surgery, especially after joint arthroplasty to prevent the formation of a hematoma. Theoretically the use of a drain should diminish the volume of hematoma; however the literature has conflicting data. Some authors state that drainage evacuates fluid from a limited area only and can be a cause of infection due to retrograde migration of bacteria. It can also impair the early postoperative rehabilitation. The aim of this study was to evaluate the clinical outcome (especially postoperative pain) and intake of analgesics in patients who had undergone primary cemented total knee arthroplasty (TKA) with or without a postoperative drain.

Materials and Methods:

A prospective comparative study of 108 consecutive patients (121 knees) was conducted. They were divided into two groups: A study group, with no drainage and a control group with drain inserted at the end of surgery. A total of 121 patients were recruited into two groups. A study group consisted of 59 knees, in which we did not use drainage after TKA and a control group with 62 knees, in which drain was inserted post surgery. Both groups were comparable in terms of preoperative characteristics. The indication for TKA was osteoarthritis (n = 105) and rheumatoid arthritis (n = 16).

Results:

In patients without drainage we observed lower need for opioids, higher blood loss on the 1^st postoperative day and a lower need for change of dressings. There were no statistically significant differences in terms of total blood loss, hidden blood loss, transfusion rate, range of motion, length of hospital stay or incidence of complications between the two groups. In 1 year observation there were no differences in clinical outcome between the two groups.

Conclusions:

The present study conclude that there is no rationale for the use of drain after primary TKA. There are benefits in terms of lower opioid intake, lower blood loss on the first postoperative day and lower need for dressing reinforcement during hospitalization.     

Posterior stabilization in total knee arthroplasty with use of an ultracongruent polyethylene insert

Fifty-three primary and 47 revision posterior cruciate ligament (PCL)-substituting total knee arthroplasties (TKAs) using a highly conforming (ultracongruent) polyethylene insert were retrospectively reviewed over a 48- to 106-month (mean, 60+/-11 months) follow-up period. These 100 knees were age and sex matched with another 100 TKAs performed using a PCL-sparing design. The ultracongruent design has an anterior buildup of 12.5 mm and a more conforming articular surface to match better the radius of the femoral component. In primary and revision TKAs, the average Hospital for Special Surgery knee score (P = .3) and range of motion (P = .43) were similar between the PCL-sparing and ultracongruent groups. In primary and revision TKAs, there were no revisions resulting from instability for patients receiving an ultracongruent insert versus 5 knees in the PCL-sparing control group secondary to subsequent postoperative anteroposterior instability and PCL insufficiency.     

Migration of all-polyethylene compared with metal-backed tibial components in cemented total knee arthroplasty

Background and purpose — With a rapidly increasing population in need of total knee arthroplasty (TKA), there is renewed interest in cost-saving all-polyethylene designs. Differences between metal-backed and all-polyethylene designs in initial component migration assessed by radiostereometric analysis (RSA), a proven predictor for late aseptic loosening, have been scantily reported. The purpose of this study was to compare implant migration and clinical outcomes of all-polyethylene tibial components versus metal-backed trays of similar geometrical shape.

Patients and methods — In this randomized controlled trial, 59 patients received a cemented Triathlon condylar-stabilizing implant (Stryker, Mahwah, NJ, USA) with either an all-polyethylene (n = 29) or a metal-backed tibial component (n = 30). RSA measurements and clinical scores (the Knee Society Score, Forgotten Joint Score, and Knee Osteoarthritis and Injury Outcome Score) were evaluated at baseline and postoperatively at 3, 12, and 24 months. A linear mixed-effects model was used to analyze the repeated measurements.

Results — A statistically significant difference in mean migration after 2 years was found in favor of the all-polyethylene group, with a mean maximum total point motion of 0.61?mm (95% CI 0.49–0.74) versus 0.81?mm (95% CI 0.68–0.96) for the cemented group (p = 0.03). However, this difference was smaller and not statistically significant after post hoc adjustment for surgeon effect. Both groups showed comparable improvements on all clinical outcome scores over time.

Interpretation — The Triathlon all-polyethylene tibial component showed less migration, suggesting a lower risk of late loosening as compared with its metal-backed counterpart. However, the found surgeon effect warrants further investigation.