Converting UKA to TKA can be difficult, and specialised techniques are needed. Issues include bone loss, joint line approximation, sizing, and rotation. Determining the complexity of conversion preoperatively helps predict the need for augmentation, grafting, stems, or constraint. In a 2009 study from our center, 50 UKA revised to TKA (1997–2007) were reviewed: 9 modular fixed-bearing, 4 metal-backed nonmodular fixed-bearing, 8 resurfacing onlay, 10 all-polyethylene step-cut, and 19 mobile bearing designs; 5 knees failed due to infection, 5 due to wear and/or instability, 10 for pain or progression of arthritis, 8 for tibial fracture or severe subsidence, and 22 due to loosening of either one or both components. Insert thickness was no different between implants or failure modes. Stemmed component use was most frequent with nonmodular components (50%), all-polyethylene step-cut implants (44%), and modular fixed-bearing implants (33%; P=0.40). Stem use was highest in tibial fracture (86%; P=0.002). Augment use was highest among all-polyethylene step-cut implants (all-polyethylene, 56%; metal-backed, 50%; modular fixed-bearing, 33%; P=0.01). Augmentation use was highest in fracture (86%) and infection (67%), with a significant difference noted between failure modes (P=0.003). Failure of nonmodular all-polyethylene step-cut devices was more complex than resurfacing or mobile bearing. Reestablishing the joint line, ligamentous balance, and durable fixation are critical to assuring a primary outcome. In a 2013 multicenter study of 3 institutions including ours, a total of 175 revisions of medial UKA in 168 patients (average age: 66 years) performed from 1995 to 2009 with a minimum 2-year clinical follow-up were reviewed. The average time from UKA to revision TKA was 71.5 months (2–262). The four most common reasons for failure were femoral or tibial loosening (55%), progressive arthritis of the lateral or patellofemoral joints (34%), polyethylene failure (4%) and infection (3%). Mean follow-up after revision was 75 months. Nine of 175 knees (4.5%) were subsequently revised at an average of 48 months (6–123). The average Knee Society pain and function score increased to 75 and 66, respectively. In the present series, the re-revision rate after revision TKA from UKA was 4.5% at an average of 75 months. In a current study from our center, 184 patients (193 UKA) underwent revision procedures (1996–2015) with minimum 2-year follow-up. Mean age was 63.5 (37–84) years, body mass index was 32.3 (19–57) kg/m. 2. , and interval after UKA was 4.8 (0–35) years. Most prevalent indications for revision were aseptic loosening (42%), arthritic progression (20%) and tibial collapse (14%). At 6.1 years mean follow-up (2–20), 8 knees (4.1%) have required re-revision involving any part, which is similar to what we recently reported at 5.5 years in a group of patients who underwent primary TKA (6 of 189; 3.2%), and much lower than what we observed at 6.0 years in a recent report of patients who underwent aseptic revision TKA (35 of 278; 12.6%). In the study group, Knee Society clinical and function scores improved from 50.8 and 52.1 preoperatively to 83.4 and 67.6 at most recent evaluation, respectively. Re-revisions were for aseptic loosening (3), instability (2), arthrofibrosis (2), and infection (1). Compared to published individual institution and national registry data, re-revision rates of failed UKA are equivalent to revision rates of primary TKA and substantially better than re-revision rates of revision TKA. These data should be used to counsel patients undergoing revision UKA to TKA

The use of stems in revision TKA enhances implant stability and thus improves the survival rate. Stemmed components obtain initial mechanical stability when there is deficient metaphyseal bone. However the optimal method of stem fixation remains controversial, which includes selection of stem size, length or the use of cemented vs. cementless stems. Although postulated by many surgeons, there is no sufficient evidence, that cementless or hybrid fixation does perform better in the long term outcome, than cemented stems. In addition a number of studies, even from the U.S., suggested that there might be a benefit for the long term survival for cemented stems in revision TKA. Obviously cemented stems have some few advantages in revision set up as: topic antibiotic delivery and initial strong fixation. While main disadvantages arise during limited/poor bone quality for initial cancellous bone-cement fixation; revision with removal of a long cement mantle and re-cementing into a previously cemented canal. Furthermore removing a fully cemented implant can be much more time consuming. The Endo Klinik has currently over 30 years of experience utilising cemented stems in combination with a rotating hinge implant in revision TKA, including satisfactory long-term results. However we are aware of this technique associated limitations, including aseptic loosening and further conversion to a re-revision with necessary impaction bone grafting. Generally it has to be mentioned, that type of stem and reconstruction type if often driven by surgeons own and institutional preference

Converting unicompartmental knee arthroplasty (UKA) to total knee arthroplasty can be difficult, and specialised techniques are needed. Issues include bone loss, joint-line, sizing, and rotation. Determining the complexity of conversion preoperatively helps predict the need for augmentation, grafting, stems, or constraint. We examined insert thickness, augmentation, stem use, and effect of failure mode on complexity of UKA conversion. Fifty cases (1997–2007) were reviewed: 9 implants (18%) were modular fixed-bearing, 4 (8%) were metal-backed nonmodular fixed-bearing, 8 (16%) were resurfacing onlay, 10 (20%) were all-polyethylene step-cut, and 19 (38%) were mobile bearing designs; 5 knees (10%) failed due to infection, 5 (10%) due to wear and/or instability, 10 (20%) for pain or progression of arthritis, 8 (16%) for tibial fracture or severe subsidence, and 22 (44%) due to loosening of either one or both components. Complexity was evaluated using analysis of variance and chi-squared 2-by-k test (80% power; 95% confidence interval). Insert thickness was no different between implants (P=0.23) or failure modes (P=0.27). Stemmed component use was most frequent with nonmodular components (50%), all-polyethylene step-cut implants (44%), and modular fixed-bearing implants (33%; P=0.40). Stem use was highest in tibial fracture (86%; P=0.002). Augment use was highest among all-polyethylene step-cut implants (all-polyethylene, 56%; metal-backed, 50%; modular fixed-bearing, 33%; P=0.01). Augmentation use was highest in fracture (86%) and infection (67%), with a significant difference noted between failure modes (P=0.003). Failure of nonmodular all-polyethylene step-cut devices was more complex than resurfacing or mobile bearing. Failure mode was predictive of complexity. Reestablishing the joint-line, ligamentous balance, and durable fixation are critical to assuring a primary outcome

Converting UKA to TKA can be difficult, and specialised techniques are needed. Issues include bone loss, joint line approximation, sizing, and rotation. Determining the complexity of conversion pre-operatively helps predict the need for augmentation, grafting, stems, or constraint. In a 2009 study from our center, 50 UKA revised to TKA (1997–2007) were reviewed: 9 implants (18%) were modular fixed-bearing, 4 (8%) were metal-backed nonmodular fixed-bearing, 8 (16%) were resurfacing onlay, 10 (20%) were all-polyethylene step-cut, and 19 (38%) were mobile bearing designs; 5 knees (10%) failed due to infection, 5 (10%) due to wear and/or instability, 10 (20%) for pain or progression of arthritis, 8 (16%) for tibial fracture or severe subsidence, and 22 (44%) due to loosening of either one or both components. Insert thickness was no different between implants (P=0.23) or failure modes (P=0.27). Stemmed component use was most frequent with nonmodular components (50%), all-polyethylene step-cut implants (44%), and modular fixed-bearing implants (33%; P=0.40). Stem use was highest in tibial fracture (86%; P=0.002). Augment use was highest among all-polyethylene step-cut implants (all-polyethylene, 56%; metal-backed, 50%; modular fixed-bearing, 33%; P=0.01). Augmentation use was highest in fracture (86%) and infection (67%), with a significant difference noted between failure modes (P=0.003). Failure of nonmodular all-polyethylene step-cut devices was more complex than resurfacing or mobile bearing. Failure mode was predictive of complexity. Reestablishing the joint line, ligamentous balance, and durable fixation are critical to assuring a primary outcome. In a 2013 multicenter study of 3 institutions including ours, a total of 175 revisions of medial UKA in 168 patients (81 males, 87 females; average age of 66 years) performed from 1995 to 2009 with a minimum of 2-year clinical follow-up were reviewed. The average time from UKA to revision TKA was 71.5 months (range 2 months to 262 months). The four most common reasons for failure of the UKA were femoral or tibial loosening (55%), progressive arthritis of the lateral or patellofemoral joints (34%), polyethylene failure (4%) and infection (3%). Mean follow-up after revision was 75 months. Nine of 175 knees (4.5%) were subsequently revised at an average of 48 months (range 6 months to 123 months). The rate of revision was 1.23 revisions per 100 observed component years. The average Knee Society pain and function score increased to 75 and 66, respectively. In the present series, the re-revision rate after revision TKA from UKA was 4.5% at an average of 75 months or 1.2 revisions per 100 observed component years. Compared to published individual institution and national registry data, re-revision of a failed UKA is equivalent to revision rates of primary TKA and substantially better than re-revision rates of revision TKA. These data should be used to counsel patients undergoing revision UKA to TKA

Converting UKA to TKA can be difficult, and specialised techniques are needed. Issues include bone loss, joint line approximation, sizing, and rotation. Determining the complexity of conversion pre-operatively helps predict the need for augmentation, grafting, stems, or constraint. In a 2009 study from our center, 50 UKA revised to TKA (1997–2007) were reviewed: 9 implants (18%) were modular fixed-bearing, 4 (8%) were metal-backed nonmodular fixed-bearing, 8 (16%) were resurfacing onlay, 10 (20%) were all-polyethylene step-cut, and 19 (38%) were mobile bearing designs; 5 knees (10%) failed due to infection, 5 (10%) due to wear and/or instability, 10 (20%) for pain or progression of arthritis, 8 (16%) for tibial fracture or severe subsidence, and 22 (44%) due to loosening of either one or both components. Insert thickness was no different between implants (P=0.23) or failure modes (P=0.27). Stemmed component use was most frequent with nonmodular components (50%), all-polyethylene step-cut implants (44%), and modular fixed-bearing implants (33%; P=0.40). Stem use was highest in tibial fracture (86%; P=0.002). Augment use was highest among all-polyethylene step-cut implants (all-polyethylene, 56%; metal-backed, 50%; modular fixed-bearing, 33%; P=0.01). Augmentation use was highest in fracture (86%) and infection (67%), with a significant difference noted between failure modes (P=0.003). Failure of nonmodular all-polyethylene step-cut devices was more complex than resurfacing or mobile bearing. Failure mode was predictive of complexity. Reestablishing the joint line, ligamentous balance, and durable fixation are critical to assuring a primary outcome. In a 2013 multicenter study of 3 institutions including ours, a total of 175 revisions of medial UKA in 168 patients (81 males, 87 females; average age of 66 years) performed from 1995 to 2009 with a minimum of 2-year clinical follow-up were reviewed. The average time from UKA to revision TKA was 71.5 months (range: 2 months to 262 months). The four most common reasons for failure of the UKA were femoral or tibial loosening (55%), progressive arthritis of the lateral or patellofemoral joints (34%), polyethylene failure (4%) and infection (3%). Mean follow-up after revision was 75 months. Nine of 175 knees (4.5%) were subsequently revised at an average of 48 months (range 6 months to 123 months.) The rate of revision was 1.23 revisions per 100 observed component years. The average Knee Society pain and function score increased to 75 and 66, respectively. In the present series, the re-revision rate after revision TKA from UKA was 4.5 % at an average of 75 months or 1.2 revisions per 100 observed component years. In a current study from our center, 174 patients (180 UKA) underwent revision procedures (1996–2017). Most prevalent indications for revision were aseptic loosening (45%) arthritic progression (17%) and tibial collapse (13%). At 4 years mean follow-up, 5 knees (2.8%) have required re-revision involving any part, which is similar to what we recently reported at 5.5 years in a group of patients who underwent primary TKA (6 of 189; 3.2%), and much lower than what we observed at 6.0 years in a recent report of patients who underwent aseptic revision TKA (35 of 278; 12.6%). Compared to published individual institution and national registry data, re-revision of a failed UKA is equivalent to revision rates of primary TKA and substantially better than re-revision rates of revision TKA. These data should be used to counsel patients undergoing revision UKA to TKA

Aims

Distal femoral osteotomies (DFOs) are commonly used for the correction of valgus deformities and lateral compartment osteoarthritis. However, the impact of a DFO on subsequent total knee arthroplasty (TKA) function remains a subject of debate. Therefore, the purpose of this study was to determine the effect of a unilateral DFO on subsequent TKA function in patients with bilateral TKAs, using the contralateral knee as a self-matched control group.

Introduction. The systematic effects of joint replacement in rheumatoid arthritis (RA) patients are that inflamed synovium and pathological articular cartilage has dissipated. Expectations of total knee arthroplasty (TKA) are reduction of inflammatory cytokines, decreased disease activity and improvement of drug efficacy and ADL. Remission of rheumatoid arthritis is defined as having a Disease Activity Score DAS28 (ESR) of less than 2.6 and Health Assessment Questionnaire (HAQ) – Disability Index, less than 0.5. Purpose. We investigated whether TKA could reduce disease activity and improve ADL, and subsequent remission levels of DAS and HAQ or not. Material and Methods. We analyzed the Knee Society Score (KSS), KOOS score and DAS28 in 15 patients, 23 rheumatoid arthritic knees at pre-operation and 1 year after operation. Preoperatively patients had used non-steroidal anti-inflammatory drugs, prednisolone, disease-modifying anti-rheumatic drugs including methotrexate. TKA (Zimmer NexGen LPS Flex Knee implants and Stemmed Tibial component with stem) was performed with the modified gap technique or modified anatomical technique using original tensor with synovectomy. Results. Preoperative and postoperative KSS are 45.7±18.1 and 88.7±17.7 (P<0.01) respectively, and function scores were 40.1±21.7 and 74.8±24.0 (P<0.01) respectively (Figure 1). Preoperative and postoperative KOOS score (%) were ‘pain’ 50.6±37.8 and 95.4±19.3 (P<0.01), ‘symptom’ 56.6±32.8 and 94.7±18.6 (P<0.01), ‘ADL’ 60.6±27.9 and 89.5±32.4 (P<0.01), ‘QOL’ 28.4±32.1 and 63.6 ±22.9 (P<0.01) and ‘sport’ 20.56±29.52 and 47.10±33.9(P=0.06), respectively (Figure 2). Preoperative and postoperative DAS28(CRP) were 4.48±1.08 and 3.58±1.11(P<0.01), and DAS28 (ESR) were 4.90±1.02 and 4.13±0.99 (P=0.02) (Figure 3). Discussion. Each scores except ‘sport’ and DAS28 (ESR) improved statistically 1 year after operation. Function score, ‘ADL’ and ‘QOL’ scores also improved. HAQ score includes 2 categories related to walking ability and TKA was expected to improve the HAQ score, although the HAQ score is highly affected by upper arm function. The ‘sport’ score did not improve because almost all patients did not do sports preoperatively and postoperatively. DAS28 (ESR) and DAS28 (CRP) correlate strongly, but in this study there were statistical discrepancies in improvement. This might be because age, sex, disease duration, and existence of rheumatoid factors, anti-cyclic citrullinated peptide antibody and DLA-DRB1 shared epitope have been shown to influence ESR. DAS28 improved by a little less than 1.0, but there was limited control of disease activity. It was reported that the average DAS 28 didn't drop below 3.2 in 3 years follow-up after TKA. In this study we did not assess depending on preoperative disease activity, but it was reported that TKA had a systematic effect on severe or moderate RA activity, not low disease activity

Purpose. To evaluate the five year Radiostereometric Analysis (RSA) results of the NexGen LPS Trabecular Metal Tibial Monoblock component (TM) and the NexGen Option Stemmed cemented component (Cemented), (Zimmer, Warsaw IN). Method. 70 patients with osteoarthritis were included in a randomized series to receive either the TM implant or the cemented NG component. Surgery was performed by high volume arthoplasty specialists using standardized procedure. RSA exams were obtained postoperatively, at six months, one year, two years and five years. RSA outcomes were translations, rotations and maximum total point motion (MTPM) of the components. MTPM values were used to classify implants as ‘at risk’ or ‘stable’. Western Ontario and McMaster University Osteoarthritis Index (WOMAC) scores were gathered at all follow-ups. An analysis of variance was used to test for differences in age, body mass index (BMI), and subjective measures between implant groups. The Kruskal-Wallis test was used to investigate differences in maximum total point motion between implant groups. An analysis of variance was used to test for differences in translations and rotations between groups. Fishers exact test was used to investigate differences in proportions of implants found to be at risk between groups. Results. At the five year follow-up, 43 patients were able to be reached and were willing to participate in the follow-up exam. There were 25 in the trabecular metal group and 18 in the cemented group. There were no differences in subjective measures (WOMAC) between implant groups at any follow-up. At the five year follow-up there was no difference in MTPM between the cemented and trabecular metal groups (p=0.94) Compared to the cemented components, the trabecular metal tibial components had significantly higher subsidence than the cemented components (p=0.001). There were no other significant differences. The proportion of at risk components at five years was 2 of 16 (0.11, 95% CI, 0.03–0.33) in the cemented group and was 0 of 25 (0.0, 95% CI, 0.0–0.13) in the trabecular metal group (p=0.17). Conclusion. In the two year report on this cohort of patients, we indicated our uncertainty concerning the long term stability of the Trabecular Metal tibial implant due to the high initial migration seen in some cases. In this report we have seen stability of this implant out to five years and migrations in this period below the level of detection of our system in all cases. Given these results it is with increased confidence that we can state that this implant appears to achieve solid fixation despite high initial levels of migration

Purpose: The goal of this study was to investigate if musculoskeletal activation patterns measured with electromyography (EMG) are predictive of migration of total knee replacements (TKR) measured with radiostereometric analysis (RSA). Method: 37 TKR patients who were part of a larger randomized controlled RSA trial were recruited to this study. Study participants had been randomized to receive the Nexgen LPS Trabecular Metal tibial monoblock component (n = 19), or the cemented NexGen Option Stemmed tibial component (n = 18) (Zimmer, Warsaw IN). Ethics approval was received from the institutional review board. In the week prior to their surgery, the patients went to the dynamics of human motion laboratory and underwent EMG data collection. Surface electrodes were placed over the vastus lateralis, vastus medialis, rectus femoris, the lateral and medial hamstrings, and the lateral and medial gastrocnemius using standardized placements (Hubley-Kozey et al., 2006). The variability in subject EMG patterns was captured with a set of discrete scores that represented weightings on objectively-extracted features of the gait waveform data using principal component analysis (PCA). Within four days of surgery and at six months post-operatively, patients had bi-planar knee x-rays taken. RSA analysis was performed with MB-RSA (MEDIS, Leiden). RSA results were reported as maximum total point motion (MTPM), and six degrees of freedom translations and rotations at six months. Results: A correlation was found between the third principle component of the lateral gastrocnemius muscle (representing high gastrocnemius activation in late stance) and the anterior migration of the component (R2=0.247 P=0.002). A correlation was found between the vastus medialis principle component three (representing low vastus medialis activation in late stance) and the anterior migration of the component (R2= 0.338, P=0.000). A stepwise regression model was developed for anterior migration of the tibial component. To reduce the number of terms in the model only the two EMG variables that were correlated with anterior migration, implant type and BMI were entered leaving four possible terms. The stepwise regression eliminated all variables but the lateral gastrocnemius and the vastus medialis. The regression equation was Anterior-Posterior Migration = 0.01 +0.12*Vastus Medialis PC3 + 0.074*Lateral Gastrocnemius PC3 (R2=0.487, R2 Adj=0.457, P< 0.0001). Conclusion: It has previously been shown that anterior shear on the tibial component of TKR is temporally localized to the last third of stance phase of gait. Both the gastrocnemius and vastus muscle groups have the ability to produce large anterior posterior shear on an the knee during late stance. This result shows that variables which capture the temporal activation patterns of these muscles preoperatively are related to the migration of the tibial component of TKR postoperatively. This may have implications for rehabilitation of these patients

This study was conducted to investigate the cases which were obliged to receive revision surgery within the first 5 years after primary Total Knee Arthroplasty (TKA). The subjects of this study were 15 patients (5 males & 10 females, mean age at revision 72 years) who had undertaken revision surgery within 5 years since 1996. Intervals between primary and revision TKA averaged 29.8 months. Prosthesis used for primary TKA was as follows; 11 Zimmer NexGen LPS-flex fixed bearing, 2 mobile bearing, 2 CR type. Revised components, cause of revision, JOA score as clinical results and FTA as radiographic evaluation were examined. Revised parts were as follows;. All components: 2,. Both Femoral and Tibial components: 4,. only Femoral component: 2,. only Tibial component: 5,. only patella component: 1,. only articular surface: 1. Stemmed Femoral components were used in 6 out of 8 knees, stemmed Tibial components in 9 out of 11 knees. The causes of revision were as follows;. infection: 1,. loosening: 7,. inadequate component position: 4,. instability: 2,. pain: 1. JOA scores improved from 45 points to 78 points, and FTA proved to be 176 deg., postoperatively. Primary TKA remains one of the most successful orthopedic procedures. Survivorship was generally reported over 15 years in the previous article. However, there are some cases in which revision TKA is necessary by some causes. There seems to be various types of causes for revisions, such as loosening, inadequate position, abrasion of components and others. Though loosening of components due to traumatic cause was inevitable, other causes, such as inadequate position of component, imbalanced soft tissues and infection, which depend on our technique, should be cared during and after surgery. From our study, except for 7 (2 trauma, 5 unknown) out of 15 knees, almost half of revision TKA (8 knees) might be due to technical demand. As for surgical techniques, in the case of poor bony quality, we routinely use stemmed components and should try not to impact strongly on setting component to prevent from sinking. In the case of non-traumatic cause, 3 out of 12, though the position of tibial component was acceptable, tibial component sunk because of bony weakness and/or imbalanced soft tissues resulting pain. Adequate position and balance of components should be achieved during primary TKA. In our department, we are trying to revise and routinely use stemmed components as soon as possible, when loosening of component is confirmed. Metal augmentation, if necessary, is mainly used for bone defect to do early rehabilitation. We concluded that adequate position of components and soft tissue balance was very important at the time of primary TKA. Clinical results of revision TKA were almost equal to those of primary TKA, however, long term follow-up will be needed