Introduction. Hip resurfacing (HRA) designer centres have reported survivorships between 88.5–96% at 12 years. Arthroplasty Registries (AR) reported less favourable results especially in females gender and small sizes. The aim of this study was to evaluate the minimum 10-year survival and outcome of the Birmingham Hip Resurfacing (BHR) from an independent specialist centre. Methods. Since 1998, 1967 BHRs have been implanted in our centre by a single hip resurfacing specialist. The first 249 BHR, implanted between 1999 and 2001 in 232 patients (17 bilateral) were included in this study. The majority of the patients were male (163; 69%). The mean age at surgery was 50.6 years (range: 17–76), with primary OA as most common indication (201; 81%), followed by avascular necrosis (23; 9.2%) and hip dysplasia (11; 4.4%). Mean follow up was 10.2 years (range: 0.1 (revision) to 13.1). Implant survival was established with revision as the end point. Harris Hip Scores (HHS), radiographs and metal ion levels were assessed in all patients. Sub-analysis was performed by gender, diagnosis and femoral component size (Small: <50 mm; Large: ≥50 mm). Results. Of the 232 patients, 15 were deceased (4 bilateral BHR), 16 lost to follow-up and 9 revised. 205 BHR were evaluated at minimum 10 years postoperatively. Failure modes included 2 component malpositioning, 2 loose femoral heads, 1 fracture, 1 metal sensitivity, 2 impingement and 1 with high metal ions. The overall survival was 95.1% (95% CI: 93.6–96.6) at 12.8 years. The mean HHS was 97.8 (range: 65–100). Survivorship in men was 98.6% (95%CI: 97.4–99.8%) at 13 years. Survivorship in women was inferior to men (log rank = 0.003): 87.9% (95%CI: 84.3–91.5%) at 12 years. There was no difference in HHS between genders in the non-revised cases (p = 0.46). There was no difference in survivorship with different pre-operative diagnosis (log-rank = 0.83) but a significant difference in 12-year survivorship between Small (90.1%) and Large components (97.2%) (log rank = 0.01). After adjusting for head size, the difference in survival between males and females was no longer significant (log-rank = 0.125). The median ion levels were Cr:2.0μg/l; Co:1.0μg/l. In 24 patients the ion levels were undetectable. Four patients (1.9%) had ions above the upper acceptable limits of Cr:4.6μg/l;Co:4.0μg/l for unilateral or Cr:7.4μg/l;Co:5.0μg/l for bilateral HRA. In 67 patients with consecutive ion measurements, levels decreased significantly with time with a mean decrease of 0.97μg/l for Cr and 0.60μg/l for Co. Discussion. This study reports the more than 10-year survival of BHR and reflects an experienced specialist's practice, including his learning curve of the procedure. The overall 12.8-year survival was superior to registry reported figures of THA amongst young patients and corresponded well with reports from designer centres. Survivorship and clinical outcome were excellent in men. In women survivorship was significantly inferior and related to smaller component sizes, but the >10-year clinical outcome in non-revised cases was excellent. In well-functioning BHR, the metal ions decrease significantly with time. The results of this study support the use of HRA with a good design

Aim: To assess the survival rate of implants and the effect of UKR on knee pain, function, stiffness and quality of life in a prospective study.

Methods: All of the knee replacements were performed using minimally invasive techniques. SF36 and WOMAC were evaluated pre-operatively and at six-monthly intervals post-operatively.

Results: There were 506 knees. The mean post-operative evaluation time was two years and six months and the maximum time was three years and nine months. The status of all knees was established. There were nine failures as determined by the need for revision procedures. Six patients died with their implants functioning.

Survival analysis: 99% at 12 months 98% at 24 months 98% at 36 months.

The scores on SF36 and WOMAC were adjusted to the Australian Population Norm. The WOMAC score showed an increase in function, and a decrease in the pain and stiffness scores. The physical and mental component summaries of the SF-36 both indicated an increased quality of life post-operatively. Implant failure was due to loosening of tibial and femoral components and progression of arthritic changes in the lateral compartments.

Conclusion: The results from the health assessment forms indicated a high patient satisfaction with the operation and a sustained improvement in quality of life, flexibility and function.

Population-based studies from the United States have reported that sarcoma patients living in rural areas or belonging to lower socioeconomic classes experience worse overall survival; however, the evidence is not clear for universal healthcare systems where financial resources should theoretically not affect access to standard of care. The purpose of this study was to determine the survival outcomes of soft-tissue sarcoma (STS) patients treated in Ontario, Canada over 23 years and determine if the patient's geographic location or income quintile are associated with survival. We performed a population-based cohort study using linked administrative databases of patients diagnosed with STS between 1993 – 2015. The Kaplan-Meier method was used to estimate 2, 5, 10, 15 and 20-year survival stratified by age, stage and location of tumor. We estimated survival outcomes based on the patient's geographic location and income quintile. The Log-Rank test was used to detect significant differences between groups. If groups were significantly different, a Cox proportional hazards model was used to test for interaction effects with other patient variables. We identified 8,896 patients with biopsy-confirmed STS during the 23-year study period. Overall survival following STS diagnosis was 70% at 2 years, 59% at 5 years, 50% at 10 years, 43% at 15 years, and 38% at 20 years. Living in a rural location (p=0.0028) and belonging to the lowest income quintile (p<0.0001) were independently associated with lower overall survival following STS diagnosis. These findings were robust to tests of interaction with each other, age, gender, location of tumor and stage of disease. This population-based cohort study of 8,896 STS patients treated in Ontario, Canada over 23 years reveals that patients living in a rural area and belonging to the lowest income quintile are at risk for decreased survival following STS diagnosis. We extend previous STS survival reporting by providing 15 and 20-year survival outcomes stratified by age, stage, and tumor location

Abstract. Background. To determine the long-term survival outcomes of Copeland Resurfacing Hemiarthroplasty (CRHA) performed by a single surgeon series. Methods. A retrospective cohort study which looked at patients who underwent CRHA over 6 years. Re-operations including revisions with component exchange taking place in our hospital and at local centres were reviewed. Oxford Shoulder Score (OSS) was used to assess their functional outcomes pre- and post-CRHA. Results. 80 CRHAs were performed in 72 patients between 2007 and 2013 with a mean follow-up of 6.5 years. The mean follow-up was 79 months (50–122). The primary indication for CRHA was osteoarthritis (76.3%), cuff tear arthropathy (16.3%), rheumatoid arthritis (5%) and post-trauma (1.3%). The mean pre-operative OSS was 16, which doubled following CRHA surgery. Fifteen patients underwent revision surgery due to ongoing glenoid pain with a mean revision time following primary CRHA being 49 months. Projected survival at the endpoints 5,7 and 10 years were 83, 81 and 79% respectively. Conclusion. This study provides us with a much longer average follow-up period in comparison to many other studies published. Previous studies, support resurfacing as a useful implant in reducing pain and improving function in the short-term; but this series demonstrates over the medium-term a relatively high revision rate of about 20% in comparison with other arthroplasty options, despite the revision rate seeming to plateau from the 5-year mark onwards

Robotic assistance in knee arthroplasty has become increasingly popular due to improved accuracy of prosthetic implantation. However, literature on the mid-term outcomes is limited especially that of hand-held robotic-assisted devices. We present one of the longest follow-up series to date using this novel technology and discuss the learning curve for introducing robotic technology into our practice. The purpose of this single-surgeon study is to evaluate the survival, patient-reported outcomes and learning curve for handheld boundary-controlled robotic-assisted unicompartmental knee arthroplasties (HBRUKAs) at our hospital. This retrospective study evaluates 100 cases (94 Medial, 6 Lateral) performed by a single surgeon between October 2012 and July 2018. 52% were males, mean age was 64.5y (range 47.3y-85.2y) and mean BMI was 31.3 (range 21.8–43). Both inlay (40%) and onlay (60%) designs were implanted. Patients were followed up routinely at 1 and 5 years with Oxford Knee Scores (OKS) recorded. The learning curve was determined by tourniquet times. At a mean follow-up of 4.3 years (range 1.6y–7.3y), survivorship was 97%. There were three revisions: One case of aseptic loosening (1.5y), one case of deep-infection (3.8y) and one case of contralateral compartment osteoarthritis progression (5y). Mean 5-year OKS was 39.8. A 14.3% reduction in mean tourniquet times between the first 25 cases (105.5minutes) and subsequent cases (90.4minutes) was seen. This single-surgeon study showed good survivorship and patient-reported outcomes for HBRUKAs at our hospital. A learning curve of approximately 25 cases was shown, with significant decreases in tourniquet times with respect to increased surgeon experience

Revision total hip arthroplasty (rTHA) in the presence of femoral defects can be technically challenging. Reconstruction with long stems is widely accepted as the standard. However long stems can be difficult to insert and can compromise distal bone stock for future revisions. The aims of this study were to identify whether there was a difference in survival and outcomes following rTHA using a long versus standard or short femoral stem. A comprehensive systematic review was performed according to PRISMA guidelines using the MEDLINE, EMBASE, Chochrane Library and Web of Science databases. Inclusion criteria were (i) adult patients >18 years; (ii) randomised controlled trials, joint registry, or cohort studies; (iii) single or staged rTHA for Paprosky 1–3B femoral defects. Exclusion criteria were (i) mixed reporting without subgroup analysis for revision stem length; (ii) ex-vivo studies. Screening for eligibility and assessment of studies was performed by the authors. Out of 341 records, 9 studies met criteria for analysis (including 1 study utilising joint registry data and 1 randomised controlled trial). Across studies there were 3102 rTHAs performed in 2982 patients with a mean age of 67.4 years and a male: female ratio of 0.93. Revision prostheses were long-stemmed in 1727 cases and short or standard in 1375 cases with a mean follow up of 5 years (range, 0-15 years). On subgroup analysis the use of a long cemented stem compared to a long cementless prosthesis was associated with fewer complications and periprosthetic fracture in older patients. Survivorship was 95% with short stems compared to 84% with long stems at 5 years. Moderate quality evidence suggests that in rTHA with Paprosky type 1-3B femoral defects, the use of a short or standard stem can achieve comparable outcomes to long stems with fewer significant complications and revisions. Using a shorter stem may yield a more straightforward surgical technique and can preserve distal bone stock for future revision

The aim of this study was to determine the long term 20 year survival and outcomes of high tibial osteotomy (HTO). 100 consecutive subjects underwent HTO under the care of a single surgeon between 2000 and 2002, consented to participation in a prospective study and completed preoperative WOMAC scores. Subjects were reviewed at 10 years, and again at a minimum of 20 years after surgery. PROMS included further surgery, WOMAC scores, Oxford Knee Score (OHS), KOOS, and EQ-5D, and satisfaction with surgery. 20 year survival was assessed with Kaplan-Meir analysis, and failure defined as proceeding to subsequent knee arthroplasty. The mean age at HTO was 50 years (range 26-66), and 72% were males. The 5, 10, and 20 year survival of the HTO was 88%, 76%, 43% respectively. On multiple regression analysis HTO failure was associated with poor preoperative WOMAC score of 45 or less (HR 3.2, 95% CI 1.7-6.0, p=0.001), age at surgery of 55 or more (HR 2.3, 95% CI 1.3-4.0, p=0.004), and obesity (HR 1.9, 95% CI 1.1-3.4, p=0.023). In patients who met all criteria of preoperative WOMAC score of 45 or less, age <55 years and body mass index of <30 HTO survival was 100%, 94%, and 59% at 5, 10 and 20 years respectively. Of those who had not proceeded to TKA the mean Oxford Score was 40, KOOS Pain score was 91 and KOOS function score was 97. 97% reported they were satisfied with the surgery and 88% would have the same surgery again under the same circumstances. At 20 years after HTO 43% had not proceeded to knee arthroplasty, and were continuing to demonstrate high subjective scores and satisfaction with surgery. HTO survival was higher in those under 55 years, with BMI <30 and baseline WOMAC score of >45 at 59% HTO survival over 20 years. HTO may be considered a viable procedure to delay premature knee arthroplasty in carefully selected subjects

Background. Lateral Unicompartmental Knee Arthroplasty (UKA) is a recognised treatment option in the management of lateral Osteoarthritis (OA) of the knee. Whilst there is extensive evidence on the indications and contraindcations in Medial UKA there is limited evidence on this topic in Lateral UKA. The aim of this study was to assess our experience of mobile lateral UKR and to look specifically at the effect of Contraindications on the outcome. Method. A total of 325 consecutive domed lateral UKAs undertaken for the recommended indications were included, and their functional and survival outcomes were assessed. The effects of age, weight, activity, and presence of full- thickness erosions of cartilage in the patellofemoral joint on outcome were evaluated. Results. Median follow- up was seven years (3 to 14), and mean age at surgery was 65 years (39 to 90). Median Oxford Knee Score (OKS) was 43 (interquartile range (IQR) 37 to 47), with 260 (80%) achieving a good or excellent score (OKS > 34). Revisions occurred in 34 (10%). In total, 14 (4%) were for dislocation, of which 12 had no recurrence following insertion of a new bearing. In all, 12 (4%) were revised for medial osteoarthritis (OA). Ten- year survival was 85% (95% confidence interval (CI) 79 to 90, at risk 72). Age, weight, activity, and patellofemoral erosions did not have a significant effect on the clinical outcome or survival. Conclusion. Mobile (domed) lateral UKA provides a good alternative to total knee arthroplasty (TKA) in the management of lateral compartment OA. Although dislocation is relatively easy to treat successfully, the dislocation rate of 4% is high. Younger age, heavier weight, high activity, and patellofemoral erosions did not detrimentally affect outcome, so should not be considered contraindications

Abstract. Background/Objectives. The incidence of reverse total shoulder replacement (rTSR) implantation is increasing globally, but apprehension exists regarding complications and associated challenges. We retrospectively analysed the senior author's series of rTSR from a tertiary centre using the VAIOS shoulder system, a modular 4th generation implant. We hypothesised that the revision rTSR cohort would have less favourable outcomes and more complications. Methods. 114 patients underwent rTSR with the VAIOS system, over 7 years. The primary outcome was implant survival. Secondary outcomes were Oxford shoulder scores (OSS), radiographic analysis (scapular notching, tuberosity osteolysis, and periprosthetic radiolucent lines) and complications. Results. There were 55 Primary rTSR, 31 Revision rTSR and 28 Trauma rTSR. Implant survival: Primary rTSR- 0 revisions, average 3.35-year follow-up. Revision rTSR-1 revision (4.17%), average 3.52-year follow-up. Trauma rTSR- 1 revision (3.57%), average 4.56-year follow-up OSS: Average OSS improved from 15.39 to 33.8 (Primary rTSR) and from 15.11 to 29.1 (Revision rTSR). Average post-operative OSS for the Trauma rTSR was 31.4 Radiological analysis and complications: Low incidence of scapular notching One hairline fracture below the tip of stem, noted incidentally, which required no treatment. One periprosthetic fracture after alcohol related fall. Treated non-surgically One joint infection requiring two-stage revision to rTSR. One dislocation noted at 2 year follow up. This patient had undergone nerve grafting within 6 months of rTSR for axillary nerve injury sustained during the original fracture dislocation. One acromial fracture with tibial and distal humeral fracture after a fall. Conclusions. The 4th generation modular VAIOS implant is a reliable option for various indications. The revision rTSR cohort had favourable outcomes with low complication rates. In this series, early-to-medium term results suggest lower revision rates and good functional outcomes when compared to published reports. We plan to monitor long-term implant survivorship and patient reported outcomes. Declaration of Interest. (a) fully declare any financial or other potential conflict of interest

Aims

The aim of this study is to determine the predictors of overall survival (OS) and predictive factors of poor prognosis of conventional high-grade osteosarcoma of the limbs in a single-centre in South Africa.

Aims

Understanding of open fracture management is skewed due to reliance on small-number lower limb, specialist unit reports and large, unfocused registry data collections. To address this, we carried out the Open Fracture Patient Evaluation Nationwide (OPEN) study, and report the demographic details and the initial steps of care for patients admitted with open fractures in the UK.

Aims. The aims of this retrospective study were to determine the incidence of extra-articular deformities (EADs), and determine their effect on postoperative alignment in knees undergoing mobile-bearing, medial unicompartmental knee arthroplasty (UKA). Patients and Methods. Limb mechanical alignment (hip-knee-ankle angle), coronal bowing of the femoral shaft and proximal tibia vara or medial proximal tibial angle (MPTA) were measured on standing, full-length hip-to-ankle radiographs of 162 patients who underwent 200 mobile-bearing, medial UKAs. Results. Incidence of EAD was 7.5% for coronal femoral bowing of >5°, 67% for proximal tibia vara of >3° (MPTA<87°) and 24.5% for proximal tibia vara of >6° (MPTA<84°). Mean postoperative HKA angle achieved in knees with femoral bowing ≤5° was significantly greater when compared to knees with femoral bowing >5° (p=0.04); in knees with proximal tibia vara ≤3° was significantly greater when compared to knees with proximal tibia vara >3° (p=0.0001) and when compared to knees with proximal tibia vara >6° (p=0.0001). Conclusion. Extra-articular deformities are frequently seen in patients undergoing mobile-bearing medial UKAs, especially in knees with varus deformity>10°. Presence of an EAD significantly affects postoperative mechanical limb alignment achieved when compared to limbs without EAD and may increase the risk of limbs being placed in varus>3° postoperatively. Clinical Relevance. Since the presence of an EAD, especially in knees with varus deformity>10°, may increase the risk of limbs being placed in varus>3° postoperatively and may affect long-term clinical and implant survival outcomes, UKR in such knees should be performed with caution

Aims

Socioeconomic and racial disparities have been recognized as impacting the care of patients with cancer, however there are a lack of data examining the impact of these disparities on patients with bone sarcoma. The purpose of this study was to examine socioeconomic and racial disparities that impact the oncological outcomes of patients with bone sarcoma.

Aims

This systematic review aims to compare the precision of component positioning, patient-reported outcome measures (PROMs), complications, survivorship, cost-effectiveness, and learning curves of MAKO robotic arm-assisted unicompartmental knee arthroplasty (RAUKA) with manual medial unicompartmental knee arthroplasty (mUKA).

Aims. The aim of this to study was to compare the previously unreported long-term survival outcome of the Oxford medial unicompartmental knee arthroplasty (UKA) performed by trainee surgeons and consultants. . Patients and Methods. We therefore identified a previously unreported cohort of 1084 knees in 947 patients who had a UKA inserted for anteromedial knee arthritis by consultants and surgeons in training, at a tertiary arthroplasty centre and performed survival analysis on the group with revision as the endpoint. Results. The ten-year cumulative survival rate for revision or exchange of any part of the prosthetic components was 93.2% (95% confidence interval (CI) 86.1 to 100, number at risk 45). Consultant surgeons had a nine-year cumulative survival rate of 93.9% (95% CI 90.2 to 97.6, number at risk 16). Trainee surgeons had a cumulative nine-year survival rate of 93.0% (95% CI 90.3 to 95.7, number at risk 35). Although there was no differences in implant survival between consultants and trainees (p = 0.30), there was a difference in failure pattern whereby all re-operations performed for bearing dislocation (n = 7), occurred in the trainee group. This accounted for 0.6% of the entire cohort and 15% of the re-operations. . Conclusion. This is the largest single series of the Oxford UKA ever reported and demonstrates that good results can be achieved by a heterogeneous group of surgeons, including trainees, if performed within a high-volume centre with considerable experience with the procedure. Cite this article: Bone Joint J 2016;(10 Suppl B):22–7

Aims

The aim of this study to compare 30-day survival and recovery of mobility between patients mobilized early (on the day of, or day after surgery for a hip fracture) and patients mobilized late (two days or more after surgery), and to determine whether the presence of dementia influences the association between the timing of mobilization, 30-day survival, and recovery.

Background. Method of fixation in THA is a contentious issue, with proponents of either technique citing improved implant survival and outcomes. Current comparisons rely on insufficiently powered studies with short-term follow up or larger poorly controlled registry studies. Patient factors are considered a key variable contributing to the risk of implant failure. One way to overcome this confounder is to compare the survival of cementless and cemented THAs patients who have undergone bilateral THAs with cemented hip on one side and cementless hip on the other. We compared stem survival of patients who have bilateral THA with one cemented stem in one hip and a cementless stem in the contralateral hip in the National Joint Registry. Methods. UK National Joint Registry is the largest registry of its kind in the world. This study included 2934 patients with 5868 THAs who underwent bilateral THAs s between 2003 and 2016. These patients had undergone bilateral sequential THAs within 3 years of each other: cemented THA on one side and cementless on the other, Patients had identical pre-operative American Society of Anaesthesiologists group for both THAs and same indication for surgery. Implant survival was compared using Cox regression with an endpoint of stem revision. Results. Ten-year all-cause survival of cementless stems was lower than for cemented stems (p<0.001), as was survival to aseptic loosening revision (p<0.001). Similar trends were seen across all age groups including young and old patients. There was a non-significant trend towards superiority of cemented stems in survival until periprosthetic fracture, dislocation and infection. Conclusion. Comparison of cementless with cemented stems within patients is a novel method to compare the outcomes of orthopaedic implants. Survival was better for cemented stems including for younger patients and aseptic loosening

Background. In the late 1980's Michael Freeman conceived the idea that knee replacement would most closely replicate the natural knee joint, if the medial Tibio-Femoral articulation was configured as a “ball-in-socket”. Over the last three decades, medial rotation and medial pivot designs have proved successful in clinical use. Freeman's final iteration of the medial ball-in-socket concept was the Medial Sphere knee. We report the three-year survivorship, clinical outcomes, patient reported outcome measures (PROMs) and radiographic analysis of this implant in a multi-centre, multi-surgeon, prospective observational study. Methods. Patients awaiting total knee replacement were recruited by four centres. They had no medical contraindication to surgery, were able to provide informed consent and were available for follow-up. Primary outcome was implant survival at six months, one, two, three and five years. Secondary outcomes were patient reported outcome measures: Oxford Knee Score (OKS), Euroqol (EQ-5D), International Knee Society Score (IKSS), IKSS Functional score and Health State score, complications and radiographic outcomes. Radiographic analysis was undertaken using the TraumaCad software and data analysis was undertaken using SPSS. Results. To date, 328 female and 202 male patients with a mean age 66.9 years and mean body mass index 30.0 were recruited. Three year Kaplan-Meier survivorship analysis of cumulative failure showed an implant survival of 99.46% (95% confidence interval 100 – 96.74), when deaths and withdrawals were treated as censored data. Twelve patients withdrew (2.26%), seven died (1.32%) and two knees were revised (0.38%). The mean EQ5D, Health State Scores, OKS, IKSS & IKSS Function scores at three years improved significantly from pre- operative scores (Health State Score: 9.91 (65.59 pre-op to 75.50); OKS: 18.82 (19.90 pre-op to 38.72); IKSS: 39.87 (44.39 pre-op to 92.09); IKSS Function Score: 35.03 (49.42 pre-op to 84.45). The mean improvement of EQ5D at three years was: 0.34 (0.48 pre-op to 0.82). Discussion. Survival of the GMK Sphere to three years in this study was over 99%. Risk of revision compares favourably with UK National Joint Registry (NJR) data. The improvements that are seen in patient reported outcome measures reflect an enhancement in patient function and quality of life. Conclusion. At three years follow-up, the implant demonstrates satisfactory survival and outcomes. Patient matching and evaluation of more cases, at more time points will allow outcome comparison with other implant options

Background. Navigation systems that increase alignment accuracies of the lower limbs have been applied widely in total knee arthroplasty and are currently being adopted for minimally invasive UKA (MIS UKA) with good alignment results. There is little debate that when compared with total knee arthroplasty (TKA), UKA is less invasive, causes less morbidity, better reproduces kinematics, and therefore offers quicker recovery, better range of movement and more physiologic function. However, despite improved alignment accuracies, advantages of use of navigation system in UKA in clinical outcomes and survivals are still debatable. To the best of our knowledge, no reports are available on the long-term results after UKA performing using a navigation system. The purpose of this prospective study was to compare the radiological, clinical, and survival outcomes of UKA that performed using the navigation system and using the conventional technique at average 8 years follows up. Methods. Between January 2003 and December 2005, Total of 98 UKAs were enrolled for this study, 56 UKAs in the navigation group and 42 UKAs in conventional group were included in this study after a average 8 years follow-up. At the final follow up, the radiological measurements with regard to the mechanical axis, the inclination of the femoral and tibial components, and radiolucent line or loosening were evaluated and compared between two groups. The clinical evaluations were performed using range of motion, Western Ontario and McMaster Arthritis index (WOMAC) scores and Knee Society (KS) score. Results. Of the 98 patients (98 UNI knees), 2 (2.0%) had died at a mean 5.8years after surgery because of cardiovascular disease, 3 (3.1%) underwent revision surgery that 1 cases of periprosthetic stress fractures in medial tibial plateaus in the navigation group and a case of tibial component loosening and polyethylene wear in conventional groups were observed. At a final follow up, the mean of mechanical axis was statistically different between two groups (2.7 vs. 3.9 of varus). And there were significant difference between 2 groups in terms of the mean values (p=0.042) for the tibial component coronal alignment, mean coronal alignments of tibial components were 89.1 ± 2.4° in the NA-MIS and 87.6 ± 1.8° in the MIS group, however outlier result were similar in the 2 group (5 and 5 knees, respectively, p=0.673). Sagittal alignments of femoral and tibial component were similar in the two groups (p>0.05) Significant differences were found in WOMAC or HSS knee scores, in which, stiffness did not show any difference between two groups, but pain and function showed difference at the last follow-up. The mean knee flexion has improved from 135.0 ± 14.8° and 135.0 ± 14.1° preoperatively to 137.1 ± 6.5° and 136.5 ± 7.2° in the NA-MIS and MIS groups on the latest follow-up, which was not significants different (p =0.883). Conclusion. The navigation system in UKA can provide improved alignment accuracy. And better clinical outcomes in pain and HSS score compared with conventional technique after a average of 8 year follow-up

Background. Total knee arthroplasty (TKA) overall is a very reliable, durable procedure. Biomechanical studies have suggested superior stress distribution in metal-backed tibial trays, however, these results have not been universally observed clinically. Currently, there is a paucity of information examining the survival and outcomes of all-polyethylene tibial components. Methods. We reviewed 31,939 patients undergoing a primary TKA over a 43-year period (1970–2013). There were 28,224 (88%) metal-backed and 3,715 (12%) all-polyethylene tibial components. The metal-backed and all-polyethylene groups had comparable demographics with respect to sex distribution (57% female for both), mean age (67 vs. 71 years), and mean BMI (31.6 vs. 31.1). Mean follow-up was 7 years (maximum 40 years). Results. The purpose of this investigation was to analyze the outcomes of all-polyethylene compared to metal-backed components in TKA and to determine: (1) is there a difference in overall survival? All-polyethylene tibial components had improved survivorship (P<0.0001) and metal-backed tibias were at increased risk of revision (HR 3.41, P<0.0001); (2) Does body mass index (BMI) or age have an effect on survival of all-polyethylene compared to metal-backed tibial components? All-polyethylene tibias had improved survival (P<0.01) in all age groups except in patients 85 years or greater, where there was no difference (P=0.16). All-polyethylene tibial components had improved survival (P<0.005) for all BMIs except in the morbidly obese (BMI ≥40) where there was no difference (P=0.20); (3) Is there an increased risk of post-operative infection? Metal-backed tibial components were found to have an increased risk of infection (HR 1.60, P=0.003); (4) Is there a difference in the rate of reoperation and post-operative complications? Metal-backed tibial components were found to have an increased risk of reoperation (HR 1.84, P<0.0001). Conclusions. The use of all-polyethylene tibias should be considered for the majority of patients, regardless of age and BMI