Aims. Unicompartmental knee arthroplasty (UKA) is the preferred treatment for anterior medial knee osteoarthritis (OA) owing to the rapid postoperative recovery. However, the risk factors for UKA failure remain controversial. Methods. The clinical data of Oxford mobile-bearing UKAs performed between 2011 and 2017 with a minimum follow-up of five years were retrospectively analyzed. Demographic, surgical, and follow-up data were collected. The Cox proportional hazards model was used to identify the risk factors that contribute to UKA failure. Kaplan-Meier survival was used to compare the effect of the prosthesis position on UKA survival. Results. A total of 407 patients who underwent UKA were included in the study. The mean age of patients was 61.8 years, and the mean follow-up period of the patients was 91.7 months. The mean Knee Society Score (KSS) preoperatively and at the last follow-up were 64.2 and 89.7, respectively (p = 0.001). Overall, 28 patients (6.9%) with UKA underwent revision due to prosthesis loosening (16 patients), dislocation (eight patients), and persistent pain (four patients). Cox proportional hazards model analysis identified malposition of the prostheses as a high-risk factor for UKA failure (p = 0.007). Kaplan-Meier analysis revealed that the five-year survival rate of the group with malposition was 85.1%, which was significantly lower than that of the group with normal position (96.2%; p < 0.001). Conclusion. UKA constitutes an effective method for treating anteromedial knee OA, with an excellent five-year survival rate. Aseptic loosening caused by prosthesis malposition was identified as the main cause of UKA failure. Surgeons should pay close attention to prevent the potential occurrence of this problem. Cite this article: Bone Jt Open 2023;4(12):914–922

Aims. The aim of this study was to investigate the distribution of phenotypes in Asian patients with end-stage osteoarthritis (OA) and assess whether the phenotype affected the clinical outcome and survival of mechanically aligned total knee arthroplasty (TKA). We also compared the survival of the group in which the phenotype unintentionally remained unchanged with those in which it was corrected to neutral. Methods. The study involved 945 TKAs, which were performed in 641 patients with primary OA, between January 2000 and January 2009. These were classified into 12 phenotypes based on the combined assessment of four categories of the arithmetic hip-knee-ankle angle and three categories of actual joint line obliquity. The rates of survival were analyzed using Kaplan-Meier methods and the log-rank test. The Hospital for Special Surgery score and survival of each phenotype were compared with those of the reference phenotype with neutral alignment and a parallel joint line. We also compared long-term survival between the unchanged phenotype group and the corrected to neutral alignment-parallel joint line group in patients with Type IV-b (mild to moderate varus alignment-parallel joint line) phenotype. Results. The most common phenotype was Type I-b (mild to moderate varus alignment-medial joint line; 27.1% (n = 256)), followed by Type IV-b (23.2%; n = 219). There was no significant difference in the clinical outcomes and long-term survival between the groups. In Type IV-b phenotypes, the neutrally corrected group showed higher 15-year survival compared with the unchanged-phenotype group (94.9% (95% confidence interval (CI) 92.0 to 97.8) vs 74.2% (95% CI 98.0 to 100); p = 0.020). Conclusion. Constitutional varus was confirmed in more than half of these patients. Mechanically aligned TKA can achieve consistent clinical outcomes and long-term survival, regardless of the patient’s phenotype. The neutrally corrected group had better long-term survival compared with the unchanged phenotype group. Cite this article: Bone Joint J 2024;106-B(5):460–467

Aims. Meniscal allograft transplantation (MAT) for patients with symptomatic meniscal loss has demonstrated good clinical results and survivorship. Factors that affect both functional outcome and survivorship have been reported in the literature. These are typically single-centre case series with relatively small numbers and conflicting results. Our aim was to describe an international, two-centre case series, and identify factors that affect both functional outcome and survival. Methods. We report factors that affect outcome on 526 patients undergoing MAT across two sites (one in the UK and one in Italy). Outcomes of interest were the Knee injury and Osteoarthritis Outcome Score four (KOOS4) at two years and failure rates. We performed multiple regression analysis to examine for factors affecting KOOS, and Cox proportional hazards models for survivorship. Results. Our results indicate that baseline KOOS4 score affects functional outcome at two years, but no other included factors were significantly related to functional outcome. The only factor that affected failure rate was the presence of cartilage lesions down to bone on both the femur and tibia, decreasing the five-year survivorship from 95% (95% confidence interval (CI) 91 to 99) to 84% (95% CI 74 to 94). Conclusion. To our knowledge, this is the largest international cohort reporting on MAT. Our results indicate that factors such as age, BMI, and cartilage lesions down to bone on both the femur and tibia of the affected compartment should not present barriers to offering MAT. Baseline KOOS4 score and the presence of bone-on-bone arthritis can be used to help counsel patients regarding the expected risks and rewards of surgery. Cite this article: Bone Joint J 2022;104-B(6):657–662

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

We describe 119 meniscal allograft transplantations performed concurrently with articular cartilage repair in 115 patients with severe articular cartilage damage. In all, 53 (46.1%) of the patients were over the age of 50 at the time of surgery. The mean follow-up was for 5.8 years (2 months to 12.3 years), with 25 procedures (20.1%) failing at a mean of 4.6 years (2 months to 10.4 years). Of these, 18 progressed to knee replacement at a mean of 5.1 years (1.3 to 10.4). The Kaplan-Meier estimated mean survival time for the whole series was 9.9 years (. sd. 0.4). Cox’s proportional hazards model was used to assess the effect of covariates on survival, with age at the time of surgery (p = 0.026) and number of previous operations (p = 0.006) found to be significant. The survival of the transplant was not affected by gender, the severity of cartilage damage, axial alignment, the degree of narrowing of the joint space or medial versus lateral allograft transplantation. Patients experienced significant improvements at all periods of follow-up in subjective outcome measures of pain, activity and function (all p-values < 0.05), with the exception of the seven-year Tegner index score (p = 0.076)

Using meta-analysis we compared the survival and clinical outcomes of cemented and uncemented techniques in primary total knee replacement. We reviewed randomised controlled trials and observational studies comparing cemented and uncemented fixation. Our primary outcome was survival of the implant free of aseptic loosening. Our secondary outcome was joint function as measured by the Knee Society score. We identified 15 studies that met our final eligibility criteria. The combined odds ratio for failure of the implant due to aseptic loosening for the uncemented group was 4.2 (95% confidence interval (CI) 2.7 to 6.5) (p < 0.0001). Subgroup analysis of data only from randomised controlled trials showed no differences between the groups for odds of aseptic loosening (odds ratio 1.9, 95% CI 0.55 to 6.40, p = 0.314). The weighted mean difference for the Knee Society score was 0.005 (95% CI −0.26 to 0.26) (p = 0.972). There was improved survival of the cemented compared to uncemented implants, with no statistically significant difference in the mean Knee Society score between groups for all pooled data

Current analysis of unicondylar knee replacements (UKRs) by national registries is based on the pooled results of medial and lateral implants. Consequently, little is known about the differential performance of medial and lateral replacements and the influence of each implant type within these pooled analyses. Using data from the National Joint Registry for England and Wales (NJR) we aimed to determine the proportion of UKRs implanted on the lateral side of the knee, and their survival and reason for failure compared with medial UKRs. By combining information on the side of operation with component details held on the NJR, we were able to determine implant laterality (medial versus lateral) for 32 847 of the 35 624 unicondylar replacements (92%) registered before December 2010. Of these, 2052 (6%) were inserted on the lateral side of the knee. The rates of survival at five years were 93.1% (95% confidence interval (CI) 92.7 to 93.5) for medial and 93.0% (95% CI 91.1 to 94.9) for lateral UKRs (p = 0.49). The rates of failure remained equivalent after adjusting for patient age, gender, American Society of Anesthesiologists (ASA) grade, indication for surgery and implant design using Cox’s proportional hazards method (hazard ratio for lateral relative to medial replacement = 0.88 (95% CI 0.69 to 1.13); p = 0.32). Aseptic loosening/lysis and unexplained pain were the main reasons for revision in both groups, although the reasons did vary depending on whether a mobile- or a fixed-bearing design was used. At a maximum of eight years the mid-term survival rates of medial and lateral UKRs are similar

We evaluated the rates of survival and cause of revision of seven different brands of cemented primary total knee replacement (TKR) in the Norwegian Arthroplasty Register during the years 1994 to 2009. Revision for any cause, including resurfacing of the patella, was the primary endpoint. Specific causes of revision were secondary outcomes. Three posterior cruciate-retaining (PCR) fixed modular-bearing TKRs, two fixed non-modular bearing PCR TKRs and two mobile-bearing posterior cruciate-sacrificing TKRs were investigated in a total of 17 782 primary TKRs. The median follow-up for the implants ranged from 1.8 to 6.9 years. Kaplan-Meier 10-year survival ranged from 89.5% to 95.3%. Cox’s relative risk (RR) was calculated relative to the fixed modular-bearing Profix knee (the most frequently used TKR in Norway), and ranged from 1.1 to 2.6. The risk of revision for aseptic tibial loosening was higher in the mobile-bearing LCS Classic (RR 6.8 (95% confidence interval (CI) 3.8 to 12.1)), the LCS Complete (RR 7.7 (95% CI 4.1 to 14.4)), the fixed modular-bearing Duracon (RR 4.5 (95% CI 1.8 to 11.1)) and the fixed non-modular bearing AGC Universal TKR (RR 2.5 (95% CI 1.3 to 5.1)), compared with the Profix. These implants (except AGC Universal) also had an increased risk of revision for femoral loosening (RR 2.3 (95% CI 1.1 to 4.8), RR 3.7 (95% CI 1.6 to 8.9), and RR 3.4 (95% CI 1.1 to 11.0), respectively). These results suggest that aseptic loosening is related to design in TKR. Cite this article: Bone Joint J 2013;95-B:636–42

We describe a prospective survival analysis of 63 consecutive meniscal allografts transplanted into 57 patients. The lateral meniscus was transplanted in 34, the medial meniscus in 17, and both menisci (combined) in the same knee in six. For survival analysis we used persistent pain or mechanical damage as clinical criteria of failure. A total of 13 allografts failed (5 lateral, 7 medial, 1 medial and lateral). A significant negative correlation (p = 0.003) was found between rupture of the anterior cruciate ligament (ACL) and successful meniscal transplantation. A significant difference (p = 0.004) in the clinical results was found between lateral and medial meniscal transplants. The cumulative survival rate of the lateral, medial and combined allografts in the same knee, based on the life-table method and the Kaplan-Meier calculation, was 76%, 50% and 67%, respectively. The survival of medial meniscal allografts may improve when reconstruction of the ACL is carried out at the same time as meniscal transplantation in an ACL-deficient knee

The purpose of this study was to undertake a meta-analysis to determine whether there is lower polyethylene wear and longer survival when using mobile-bearing implants in total knee replacement when compared with fixed-bearing implants. Of 975 papers identified, 34 trials were eligible for data extraction and meta-analysis comprising 4754 patients (6861 knees). We found no statistically significant differences between the two designs in terms of the incidence of radiolucent lines, osteolysis, aseptic loosening or survival. There is thus currently no evidence to suggest that the use of mobile-bearing designs reduce polyethylene wear and prolong survival after total knee replacement. Cite this article: Bone Joint J 2013;95-B:1057–63

Aims

The tibial component of total knee arthroplasty can either be an all-polyethylene (AP) implant or a metal-backed (MB) implant. This study aims to compare the five-year functional outcomes of AP tibial components to MB components in patients aged over 70 years. Secondary aims are to compare quality of life, implant survivorship, and cost-effectiveness.

We report the ten-year survival of a cemented total knee replacement (TKR) in patients aged < 55 years at the time of surgery, and compare the functional outcome with that of patients aged > 55 years. The data were collected prospectively and analysed using Kaplan-Meier survival statistics, with revision for any reason, or death, as the endpoint. A total of 203 patients aged < 55 years were identified. Four had moved out of the area and were excluded, leaving a total of 221 TKRs in 199 patients for analysis (101 men and 98 women, mean age 50.6 years (28 to 55)); 171 patients had osteoarthritis and 28 had inflammatory arthritis. Four patients required revision and four died. The ten-year survival using revision as the endpoint was 98.2% (95% confidence interval 94.6 to 99.4). Based on the Oxford knee scores at five and ten years, the rate of dissatisfaction was 18% and 21%, respectively. This was no worse in the patients aged < 55 years than in patients aged > 55 years. These results demonstrate that the cemented PFC Sigma knee has an excellent survival rate in patients aged < 55 ten years post-operatively, with clinical outcomes similar to those of an older group. We conclude that TKR should not be withheld from patients on the basis of age

As the surgical indications for total knee replacement (TKR) expand to include younger, heavier and more active patients, knowledge of the effect of these demographic variables on the outcome and survival of the implant is increasingly important. Between November 1986 and September 1990, 402 patients underwent 562 primary cemented cruciate-retaining TKRs carried out by a single surgical team. The overall results showed a survival of 96.8% at 14 years with 1.44% lost to follow-up. Evaluating the demographics of these patients showed that certain groups fared significantly less well. The best results were seen in non-obese women with osteoarthritis who were over 60 years of age in whom there was ten-year survival of 99.4%. The worst results were in obese men with osteoarthritis who were less than 60 years of age in whom there was a ten-year survival of 35.7%. Caution should be exercised when considering TKR on a patient with this combination of poor risk factors. By identifying demographic factors at the time of consultation the surgeon is better able to predict the survival of the TKR. This information is important when considering the best options for treatment of a patient and in providing accurate information during preoperative counselling

Correct positioning and alignment of components during primary total knee replacement (TKR) is widely accepted to be an important predictor of patient satisfaction and implant durability. This retrospective study reports the effect of the post-operative mechanical axis of the lower limb in the coronal plane on implant survival following primary TKR. A total of 501 TKRs in 396 patients were divided into an aligned group with a neutral mechanical axis (± 3°) and a malaligned group where the mechanical axis deviated from neutral by > 3°. At 15 years’ follow-up, 33 of 458 (7.2%) TKRs were revised for aseptic loosening. Kaplan-Meier survival analysis showed a weak tendency towards improved survival with restoration of a neutral mechanical axis, but this did not reach statistical significance (p = 0.47). We found that the relationship between survival of a primary TKR and mechanical axis alignment is weaker than that described in a number of previous reports

This retrospective study evaluated the midterm clinical and radiographic outcomes of a second-generation total knee replacement system. In a multicentre consecutive series of 1512 patients, 1970 knees were treated with the PFC Sigma knee system (Depuy, Warsaw, Indiana). The patients were reviewed for functional outcome, and underwent independent radiographic evaluation at a mean follow-up of 7.3 years (5 to 10). A total of 40 knees (2%) required revision, 17 (0.9%) for infection. The incidence of osteolysis was 2.2%. The ten-year survival with revision for any cause other than infection as the endpoint was 97.2% (95% CI 95.4 to 99.1). The PFC Sigma knee system appears to provide excellent results in the medium term

We reviewed the rate of revision of unicompartmental knee replacements (UKR) from the New Zealand Joint Registry between 1999 and 2008. There were 4284 UKRs, of which 236 required revision, 205 to a total knee replacement (U2T) and 31 to a further unicompartmental knee replacement (U2U). We used these data to establish whether the survival and functional outcome for revised UKRs were comparable with those of primary total knee replacement (TKR). The rate of revision for the U2T cohort was four times higher than that for a primary TKR (1.97 vs 0.48; p < 0.05). The mean Oxford Knee Score was also significantly worse in the U2T group than that of the primary TKR group (30.02 vs 37.16; p < 0.01). The rate of revision for conversion of a failed UKR to a further UKR (U2U cohort) was 13 times higher than that for a primary TKR. The poor outcome of a UKR converted to a primary TKR compared with a primary TKR should contra-indicate the use of a UKR as a more conservative procedure in the younger patient

We evaluated the survival of moulded monoblock and modular tibial components of the AGC total knee replacement in patients with rheumatoid arthritis. Between 1985 and 1995, 751 knees with this diagnosis were replaced at our institution. A total of 256 tibial components were of the moulded design and 495 of the modular design. The mean follow-up of the moulded subgroup was 9.6 years (0.5 to 14.7), and that of the modular group 7.0 years (0.1 to 14.7). The groups differed significantly from each other in Larsen grade, cementing of components and patellar resurfacing, but no statistically significant difference between the survival of the components was found (Log rank test, p = 0.91). The cumulative success rate of the moulded group was 96.8% (95% confidence interval 93.6% to 98.4%) at five years and 94.4% (95% confidence interval 90.4% to 96.7%) at ten years, and of the modular group 96.2% (95% confidence interval 94% to 97.6%) and 93.6% (95% confidence interval 89.7% to 96%), respectively. Revision was required in 37 total knee replacements, the main causes were infection, pain, loosening of the tibial component and patellar problems. Survival rates for both components were satisfactory

We report a ten-year rate of survival of 96% for the cemented Freeman-Samuelson knee arthroplasty in patients from the Swedish Knee Registry and the Royal London Hospital with revision for aseptic loosening as the criterion for failure

We performed a prospective study of 54 patients (76 knees) who underwent Osteonics series 3000 cruciate-retaining cementless total knee arthroplasty between December 1990 and June 1993. Five patients (seven knees) were lost to follow-up (90.7% completion). One patient required revision at 10.5 years after operation. The rate of survival was 100% at ten years and 96.7% at 13 years. The mean ten-year knee and function scores were 79 and 59 respectively. Both were significantly better than the pre-operative scores. The range of movement also improved. Although a radiolucent line around the tibial component enlarged in six knees (20.7%) at ten years, the clinical outcome was generally good. In a patient who died after 5.5 years, post-mortem examination of the knee showed no bony ingrowth into the tibial component. Despite poor bony ingrowth, press-fit fixation was satisfactory and good results can be obtained with this cementless, cruciate-retaining prosthesis

Aims. The primary objective of this registry-based study was to compare patient-reported outcomes of cementless and cemented medial unicompartmental knee arthroplasty (UKA) during the first postoperative year. The secondary objective was to assess one- and three-year implant survival of both fixation techniques. Methods. We analyzed 10,862 cementless and 7,917 cemented UKA cases enrolled in the Dutch Arthroplasty Registry, operated between 2017 and 2021. Pre- to postoperative change in outcomes at six and 12 months’ follow-up were compared using mixed model analyses. Kaplan-Meier and Cox regression models were applied to quantify differences in implant survival. Adjustments were made for patient-specific variables and annual hospital volume. Results. Change from baseline in the Oxford Knee Score (OKS) and activity-related pain was comparable between groups. Adjustment for covariates demonstrated a minimally greater decrease in rest-related pain in the cemented group (β = -0.09 (95% confidence interval (CI) -0.16 to -0.01)). Cementless fixation was associated with a higher probability of achieving an excellent OKS outcome (> 41 points) (adjusted odds ratio 1.2 (95% CI 1.1 to 1.3)). The likelihood of one-year implant survival was greater for cemented implants (adjusted hazard ratio (HR) 1.35 (95% CI 1.01 to 1.71)), with higher revision rates for periprosthetic fractures of cementless implants. During two to three years’ follow-up, the likelihood of implant survival was non-significantly greater for cementless UKA (adjusted HR 0.64 (95% CI 0.40 to 1.04)), primarily due to increased revision rates for tibial loosening of cemented implants. Conclusion. Cementless and cemented medial UKA led to comparable improvement in physical function and pain reduction during the initial postoperative year, albeit with a greater likelihood of achieving excellent OKS outcomes after cementless UKA. Anticipated differences in early physical function and pain should not be a decisive factor in the choice of fixation technique. However, surgeons should consider the differences in short- and long-term implant survival when deciding which implant to use. Cite this article: Bone Jt Open 2024;5(5):401–410