From 1985 through 1997, 56 isolated tibial insert exchange revisions were performed at our institution. Fifty-five patients with wear or instability were included. Those with loosening of any of the components, history of infection, severe knee stiffness or problems with the extensor mechanism were excluded. There were 29 males (1 bilateral) and 26 female patients with a mean age of 66 years (range 35 to 83 years) at the time of revision surgery. Twenty-seven inserts were exchanged based on ligamentous instability, 24 because of insert wear or breakage including two cases of polyethylene dislodgment from the tibial base-plate and 5 for other reasons. Twelve knees had one to three prior revisions. Surveillance from index arthroplasty averaged 8.3 years (range 1.6 to 16.2 years) and since revision 4.6 years (range 2 to 14 years). Knee Society and Function Scores improved from 56 and 50.9 prior to revision to 76 and 59 at final surveillance, respectively. Fourteen (25%) of the 56 knees subsequently required re-revision after a mean of only three years (range 0.5 to 6.8) from tibial insert exchange. The cumulative survival at 5.5 years was 63.5% (95% CI=+/−14.4, n=19). Of the 27 patients with preoperative instability, eight were revised and another four were considered as failures due to severe pain. Of the 24 failed inserts, five were re-revised, one was amputated as a result of chronic ankle osteomyelitis concomitant to a chronically painful arthroplasty, and another two inserts failed due to severe pain. Isolated tibial insert exchange led to a surprisingly high early failure rate. Tibial insert exchange should therefore be undertaken with caution as an isolated method of total knee revision surgery even in those circumstances for which the modular insert was designed and felt to be of greatest value

From 1985 through 1997, 56 isolated tibial insert exchange revisions were performed at our institution. Fifty-five patients with wear or instability were included. Those with loosening of any of the components, history of infection, severe knee stiffness or problems with the extensor mechanism were excluded. There were 29 males (1 bilateral) and 26 female patients with a mean age of 66 years (range 35 to 83 years) at the time of revision surgery. Twenty-seven inserts were exchanged based on ligamentous instability, 24 because of insert wear or breakage including two cases of polyethylene dislodgment from the tibial base-plate and 5 for other reasons. Twelve knees had one to three prior revisions. Surveillance from index arthroplasty averaged 8.3 years (range 1.6 to 16.2 years) and since revision 4.6 years (range 2 to 14 years). Knee Society and Function Scores improved from 56 and 50.9 prior to revision to 76 and 59 at final surveillance respectively. Fourteen (25%) of the 56 knees subsequently required re-revision after a mean of only three years (0.5–6.8) from tibial insert exchange. The cumulative survival at 5.5 years was 63.5% (95%CI=+/−14.4, n=19). Of the 27 patients with pre-operative instability, eight were revised and another four were considered as failures due to severe pain. Of the 24 failed inserts, five were re-revised, one was amputated as a result of chronic ankle osteomyelitis concomitant to a chronically painful arthroplasty, and another two inserts failed due to severe pain. Isolated tibial insert exchange led to a surprisingly high early failure rate. Tibial insert exchange should therefore be undertaken with caution as an isolated method of total knee revision surgery even in those circumstances for which the modular insert was designed and felt to be of greatest value

Total knee replacement is one of the most successful procedures in orthopaedic surgery. Although originally limited to more elderly and less active individuals, the inclusion criteria for TKA have changed, with ever younger, more active and heavier patients receiving TKA. Currently, wear debris related osteolysis and associated prosthetic loosening are major modes of failure for TKA implants of all designs. Initially, tibial components were cemented all-polyethylene monoblock constructs. Subsequent long-term follow up studies of these implants have demonstrated excellent durability in survivorship studies out to twenty years. Aseptic loosening of the tibial component was one of the main causes of failure in these implants. Polyethylene wear with osteolysis around well fixed implants was rarely (if ever) observed. Cemented metal-backed nonmodular tibial components were subsequently introduced to allow for improved tibial load distribution and to protect osteoporotic bone. Long-term studies have established that many one-piece nonmodular tibial components have maintained excellent durability. Eventually, modularity between the polyethylene tibial component and the metal-backed tray was introduced in the mid-80s mainly to facilitate screw fixation for cementless implants. These designs also provided intra-operative versatility by allowing interchange of various polyethylene thicknesses, and to also aid the addition of stems and wedges. Other advantages included the reduction of inventory, and the potential for isolated tibial polyethylene exchanges as a simpler revision procedure. However, since the late 1980's, the phenomena of polyethylene wear and osteolysis have been observed much more frequently when compared with earlier eras. The reasons for this increased prevalence of synovitis, progressive osteolysis, and severe polyethylene wear remain unclear, but it is likely associated with the widespread use of both cementless and cemented modular tibial designs. Backside wear between the metal tray and polyethylene has been implicated. Recent RSA studies comparing fixation of all-polyethylene to modular components has shown that their RSA migration patterns are superior and fixation is in fact better with the all-polyethylene construct. Further, in a recent meta-analysis, all-polyethylene components were equivalent to metal-backed components regarding revision rates and clinical scores. The promise of modular tibial components affording a simple liner exchange to revise a knee has not borne out in the literature. Several studies have revealed that the effectiveness of isolated tibial insert exchange in revision TKR is of limited value. 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. Because of the modularity, extra materials, and extra processing, modular tibial components are significantly more expensive than all-polyethylene components

Liner exchange and bone grafting are commonly used in cases of wear and osteolysis around well- fixed acetabular components in revision total hip arthroplasty. However, in total knee revision, liner exchange is a more rare option. In a multicenter study, we evaluated 22 TKAs that were revised with liner exchange and bone grafting for wear and osteolysis. All knees were well-fixed and well-aligned, and all components were modular tibial components. Osteolytic areas averaged 21.1cm2 and 7.6cm2 on AP projections of the femur and tibia, respectively, and averaged 21.6cm2 and 5.7cm2 on lateral projections of the femur and tibia, respectively, with the largest area being 54cm2 on a single projection. Follow up was minimum 2 years and average 40 months. No knees were revised and radiographically, all osteolytic lesions showed evidence of complete or partial graft incorporation. In addition, there was no radiographic evidence of loosening at final follow up. The Mayo Clinic evaluated 56 isolated tibial insert exchange revisions at their institution. Cases of loosening, infection, knee stiffness, or extensor mechanism problems were excluded. At minimum 2-year follow up (average 4.6 years), 14 knees (25%) required re-revision. Baker et al. evaluated 45 total knees undergoing isolated tibial insert exchange. At minimum 2 years, 4 knees (9%) required revision. Significant improvement was seen in clinical outcomes questionnaires, but only 58% had clinical successful global WOMAC scores. In summary, isolated liner exchange in the revision total knee setting has variable results. It can be successful but it is indeed a rare option and should be limited to cases were the total knee arthroplasty is both well-fixed and well-aligned

Liner exchange and bone grafting are commonly used in cases of wear and osteolysis around well fixed acetabular components in revision total hip arthroplasty. However, in total knee revision, liner exchange is a more rare option. In a multicenter study, we evaluated 22 TKAs that were revised with liner exchange and bone grafting for wear and osteolysis. All knees were well fixed and well aligned, and all components were modular tibial components. Osteolytic areas averaged 21.1 cm2 and 7.6 cm2 on AP projections of the femur and tibia, respectively, and averaged 21.6 cm2 and 5.7 cm2 on lateral projections of the femur and tibia, respectively, with the largest area being 54 cm2 on a single projection. Follow up was minimum 2 years and average 40 months. No knees were revised and radiographically, all osteolytic lesions showed evidence of complete or partial graft incorporation. In addition, there was no radiographic evidence of loosening at final follow up. The Mayo Clinic evaluated 56 isolated tibial insert exchange revisions at their institution. Cases of loosening, infection, knee stiffness, or extensor mechanism problems were excluded. At minimum 2 year follow up (average 4.6 years), 14 knees (25%) required re-revision. Baker et al evaluated 45 total knees undergoing isolated tibial insert exchange. At minimum 2 years, 4 knees (9%) required revision. Significant improvement was seen in clinical outcomes questionnaires, but only 58% had clinical successful global WOMAC scores. In summary, isolated liner exchange in the revision total knee setting has variable results. It can be successful but it is indeed a rare option and should be limited to cases where the total knee arthroplasty is both well fixed and well aligned

A modular tibial insert exchange is a seemingly attractive benign and simple surgical alternative when compared to full knee revision. Unfortunately, the results have been less than satisfactory with modular insert exchange for polyethylene wear and knee instability. Babis et al reported the results of 56 isolated insert exchanges performed for wear or instability. The re-revision rate was 25% at a mean follow-up of 3-years and the cumulative survival rate was only 63.5% at 5.5 years. In another study, 27% (6/22) insert exchanges for wear required re-revision within 5 years. Bert et al reported scoring and damage in 89% of 55 retained components considered candidates for isolated insert exchange. Such damage could account for accelerated wear of a new insert. These studies are misleading. The new insert must be polyethylene not prone to oxidation and accelerated wear. In a recent study of 177 revisions for wear and osteolysis, the survivorship of insert exchange using non-irradiated poly was 100%. Insert exchange does not correct the problem of a poor tibial locking mechanism. Whiteside and Katerberg reported 3 failures in 49 insert exchanges, fabrication of the tibial locking mechanism was used to address this problem. With revision for instability, insert exchange must provide full stability in both flexion and extension. Tibial insert exchange must correct the underlying cause of failure that led to the revision surgery. Full knee revision is a complex procedure that brings with it increased risks of perioperative complications such as infection and should be reserved only for cases that will not do well with simple insert exchange

Introduction. Patients ≤ 55 years have a high primary TKA revision rate compared to patients >55 years. Guided motion knee devices are commonly used in younger patients yet outcomes remain unknown. Materials and Methods. In this sub-group analysis of a large multicenter study, 254 TKAs with a second-generation guided motion knee implant (Journey II Bi-Cruciate Stabilized Knee System, Smith & Nephew, Inc., Memphis) were performed between 2011–2017 in 202 patients ≤ 55 years at seven US and three European sites. Revision rates were compared with Australian Joint Registry (AOANJRR) 2017 data. Results. Average age 49.7 (range 18–54); 56.4% females; average BMI 34 kg/m. 2. ; 67.1% obese; patellae resurfaced in 98.4%. Average follow-up 4.2 years; longest follow-up six years; 27.5% followed-up for ≥ five years. Of eight revisions: total revision (one), tibial plate replacements (three), tibial insert exchanges (four). One tibial plate revision re-revised to total revision. Revision indications were mechanical loosening (n=2), infection (n=3), peri-prosthetic fracture (n=1), and instability (n=2). The Kaplan-Meier revision estimate was 3.4% (95% C.I. 1.7% to 6.7%) at five years compared to AOANJRR rate of 6.9%. There was no differential risk by sex. Discussion. Reasons for high TKA revision rates in younger patients remain unknown. Conclusion. The revision rate of the second-generation guided motion knee system is lower in younger patients compared to registry controls

Instability after TKA can result from ligament imbalance, attenuation of soft tissues, or ligament disruption. Flexion instability has been reported after both CR and PS TKA. However, the clinical manifestations of flexion instability can be quite variable. Symptoms of flexion instability include pain and swelling after activity. Bracing occasionally can be helpful. Revision options to treat flexion instability include tibial insert exchange and revision to increase constraint. However, more favorable results have been reported using implants with varus-valgus constraint. Constrained mechanisms include a varus-valgus constrained PS post or hinge. The constrained post relies on the mechanical function of the post to provide stability which may deform or wear in-vivo leading to recurrent instability if used for a completely deficient collateral ligament. The hinge, which provides more rigid constraint, is indicated for collateral ligament deficiency. However, the additional constraint also results in greater bone-implant interface stresses, which may be mitigated by use of stem fixation to minimise risk of loosening

Introduction. Symptomatic instability following total knee arthroplasty (TKA) is a leading cause of early failure. Despite numerous reports on instability, standardized diagnostic and treatment protocols for these patients continue to remain unclear. Most reports recommend component revision as the preferred treatment, because of poor outcomes and high failure rates associated with isolated tibial polyethylene insert exchange (ITPIE). However, modern implant systems and standardized protocols may potentially change this teaching. Methods. We performed an IRB-approved, retrospective review of 90 consecutive patients with minimum 2 years follow-up who underwent revision TKA for instability by one of four arthroplasty surgeons at a single institution. Mean age was 62.0 years (range, 41 to 83 years), and 73% of patients were women. Charts were reviewed for relevant preoperative clinical and physical exam findings, as well as pertinent intraoperative findings. Radiographs were analyzed for femoral and tibial component positioning. Pre- and post-operative Knee Society Scores (KSS) were calculated. Results. Mean follow-up was 3.7 years. Using standardized criteria, 40% of patients were treated with ITPIE while 60% underwent revision of one or both components. In those treated with ITPIE, mean increase in polyethylene thickness was 4.4mm; level of constraint was also increased whenever allowed by the primary implants (47% of ITPIE cases). Total arc of motion improved from 117° to 123°. There were significant postoperative improvements in both KSS knee (48.4 to 82.6) and function (49.0 to 81.0) scores. Subgroup analysis demonstrated no significant differences in motion or KSS between those treated with ITPIE versus revision of one or both components. Combined failure rates were 19.4% in the ITPIE group versus 18.5% in the component revision group (p = 1.00). Conclusions. Using an algorithmic approach to patients with instability following TKA, symptoms and function can reliably be improved. Contrary to conventional teaching, ITPIE can be an effective strategy at addressing instability symptoms when specific preoperative and intraoperative criteria can be fulfilled