Cementless Oxford Research Articles

Cemented versus cementless Oxford unicompartmental knee arthroplasty for the treatment of medial knee osteoarthritis: an updated systematic review and meta-analysis.

This meta-analysis sought to compare the efficacy of cemented versus cementless Oxford unicompartmental knee arthroplasty(UKA) for the treatment of medial knee osteoarthritis. A comprehensive search of the following databases was conducted: Pubmed, The Cochrane Library, China National Knowledge Infrastructure (CNKI), Embase, the Web of Science, and MEDLINE. The objective was to identify literature comparing cemented versus cementless Oxford unicompartmental knee arthroplasty for the treatment of medial knee osteoarthritis. Duplicate literature, low-quality literature, literature with incompatible observations, and literature for which the full text was not available were excluded. Two independent researchers employed the Cochrane Risk Assessment Tool and the Newcastle-Ottawa Scale (NOS) to evaluate the quality of the included literature. The data then were extracted and subsequently meta-analyzed using RevMan 5.4. A total of 12 papers were included in the analysis, encompassing a cumulative of 2558 cumulative cases. Of these, 1258 were cemented and 1300 were cementless. A meta-analysis was conducted to compare the outcomes of cemented versus cementless Oxford UKA. The Oxford UKA group exhibited a significantly longer surgery time than the cementless Oxford UKA group [mean difference (MD) = 9.91, 95% confidence interval (CI) (7.64,12.17)]. Additionally, the cemented Oxford UKA group demonstrated a significantly lower knee OKS score compared to the cementless Oxford UKA group. The mean difference (MD) was - 1.58 (95% CI: -2.30, -0.86), indicating a significantly lower score for the cemented Oxford UKA group. Similarly, the mean difference (MD) was - 1.8 for the knee KSS clinical score, indicating a significantly lower score for the cemented Oxford UKA group. The results demonstrated that the knee KSS functional score was significantly lower in the cemented Oxford UKA group than in the cementless Oxford UKA group [MD=-1.72, 95% CI (-3.26, -0.37)]. 95% CI (-3.27,-0.17)], the cemented Oxford UKA group exhibited a significantly higher incidence of radiolucent lines around the prosthesis than the cementless Oxford UKA group [ratio of ratios (OR) = 3.62, 95% CI (1.08,12.13)]. The revision rate was significantly higher in the cemented Oxford UKA group than in the cementless Oxford UKA group [OR = 2.22, 95% CI (1.40,3.53)]. However, no significant difference was observed between the two groups in terms of reoperation rate, five-year prosthesis survival rate, and complication rate. The findings indicated that, in comparison to cemented Oxford UKA, cementless Oxford UKA resulted in a reduction in surgical time, an improvement in knee OKS score, KSS clinical score, and KSS functional score, and a decrease in the incidence of periprosthetic radiolucent lines and the rate of revisions.

Cementless Oxford Unicompartmental Knee Replacements: More Data, More Questions: Commentary on an article by Hasan R. Mohammad, MRCS, MRes(Dist), DPhil(Oxon), et al.: "A Matched Comparison of Implant and Functional Outcomes of Cemented and Cementless Unicompartmental Knee Replacements. A Study from the National Registry for England, Wales, Northern Ireland and the Isle of Man and the Hospital Episode Statistics Patient Reported

Cementless Oxford Unicompartmental Knee Replacements: More Data, More Questions: Commentary on an article by Hasan R. Mohammad, MRCS, MRes(Dist), DPhil(Oxon), et al.: "A Matched Comparison of Implant and Functional Outcomes of Cemented and Cementless Unicompartmental Knee Replacements. A Study from the National Registry for England, Wales, Northern Ireland and the Isle of Man and the Hospital Episode Statistics Patient Reported

Microporous titanium and hydroxyapatite improve fixation of the tibial wall in unicompartmental knee replacement.

Cementless Oxford unicompartmental knee replacement (OUKR) is associated with less pain than cemented OUKR 5 years postoperatively. This may be due to improved fixation at the tibial wall, which transmits tension and reduces stress in the bone below the tibial component. This study compares tibial wall fixation with three different types of fixation: cemented, cementless with hydroxyapatite (HA)and cementless with a microporous titanium coat and HA (HA + MPC). Three consecutive cohorts were identified (n = 221 cemented in 2005-2007, n = 118 HA in 2014-2015, n = 125 HA + MPC in 2016-2017). Analysis was performed on anterior-posterior radiographs aligned on the tibial component taken 1-2 years postoperatively. Aligned radiographs are needed to see narrow radiolucencies adjacent to the wall. Alignment was assessed with rotation ratio (RR = wall width/internal wall height). Perfect RR is 0.3, and a maximum threshold of 0.5 was used. Quality of fixation to the wall was assessed with fixation ratio (FR = bone wall contact height/total wall height). Notable radiographic features at the tibial wall were also recorded. A total of 33knees with cement, 37 knees with cementless with HAand 57 knees cementless with HA + MPC had adequately aligned radiographs. Fixation was significantly better with HA compared with cement (55% vs. 25%, p = 0.0016). The microporous coat further improved fixation (81% vs. 55%, p < 0.0001). FR > 80% was achieved in 3% of the cemented implants, 32% of HAand 68% of HA + MPC. In cementless cohorts, features suggestive of a layer of bone that had delaminated from the wall were seen in 8 (22%) HA and 3 (5%) HA + MPC knees. Radiographic tibial wall fixation in OUKR is poor with cement. It improves with an HA coating and improves further with an intermediary MPC. Improved tibial wall fixation may explain the lower levels of pain observed with cementless rather than cemented fixation described in the literature, but further clinical correlation is needed. Level III, retrospective cohort study.

A finite element model for investigating the influence of keel design and position on unicompartmental knee replacement cementless tibial component fixation

ObjectivesThe cementless Oxford Unicompartmental Knee Replacement (OUKR) tibial component relies on an interference fit to achieve initial fixation. The behaviour at the implant-bone interface is not fully understood and hence modelling of implants using Finite Element (FE) software is challenging. With a goal of exploring alternative implant designs with lower fracture risk and adequate fixation, this study aims to investigate whether optimisation of FE model parameters could accurately reproduce experimental results of a pull-out test which assesses fixation. Materials and methodsFinite element models of implants with three methods of fixation (standard keel, small keel, and peg) in a bone analogue foam block were created, in which implants were modelled using an analytical rigid definition and the foam block was modelled as a homogenous linear isotropic material. The total interference and elastic slip were varied in these models and optimised by comparing simulated and experimental results of pull-out tests for two (standard and peg) implant geometries. Then the optimised interference and elastic slip were validated by comparing simulated and experimental data of a third (small keel) implant geometry. ResultsThe optimisation of parameters established an interference of 0.16 mm and an elastic slip of 0.20 mm as most suitable for modelling the experimental force–displacement plots during pull-out. This combination of parameters accurately reproduced the experimental results of the small keel geometry. The maximum pull-out forces from the FE models were consistent with experimental data for each implant design. ConclusionsThis study shows that experimental pull-out tests can be accurately modelled using adjusted interference values and non-linear friction and outlines a method for determining these parameters. This study demonstrates that complex problems in modelling implant behaviour can be addressed with relatively simple models. This can potentially lead to the development of implants with reduced risk of failure.

Less pain reported 5 years after cementless compared to cemented unicompartmental knee replacement: an analysis of pain, neuropathy, and co-morbidity scores

PurposeTo compare patient-reported pain scores and assess the influence of neuropathy and co-morbidity, on knee pain following cemented and cementless medial unicompartmental knee replacement (UKR) 5 years after surgery.MethodIn this longitudinal study, 262 cemented and 262 cementless Oxford UKR performed for the same indications and with the same techniques were recruited. Patients were reviewed at five years, evaluating patient-reported pain and association with clinical outcomes. Intermittent and Constant Osteoarthritis Pain (ICOAP), PainDETECT (PD), Charnley score, Oxford Knee Score (OKS) and American Knee Society Score (AKSS) were compared.ResultsIn both cohorts, intermittent pain was more common than constant pain (47% vs 21%). Cementless knees reported significantly less pain than cemented (ICOAP-Total 5/100 vs 11/100, p < 0.0001). A greater proportion of cementless knees experienced no pain at all (ICOAP = 0/100, 61% vs 43%, p < 0.0001) and 75% fewer experienced severe or extreme pain. Pain sub-scores in PD, OKS and AKSS follow this trend. Pain was unlikely to be neuropathic (PD positive: 5.26%), but patients reporting high levels of ‘strongest’ pain were three times more likely to be neuropathic. Patients with co-morbidities (Charnley C) experienced greater pain than those without (Charnley A+B) across all knee-specific scores, despite scores being knee specific.ConclusionBoth cemented and cementless UKR in this study had substantially less pain than that reported in literature following TKR. Cementless UKR had significantly less pain than cemented UKR in all scores. Two-thirds of patients with a cementless UKR had no pain at all at 5 years, and pain experienced was most likely to be mild and intermittent with no patients in severe or extreme pain. Patients with cementless UKR that had higher levels of pain were more likely to have co-morbidity or evidence or neuropathic pain. It is unclear why cementless UKR have less pain than cemented; further study is necessary.

EARLY TIBIAL SUBSIDENCE OF THE CEMENTLESS OXFORD UNICOMPARTMENTAL KNEE ARTHROPLASTY

AbstractIntroductionAnecdotal reports suggest some cementless Oxford Unicompartmental Knee Replacements (OUKRs) have painful early subsidence of the tibial component with valgus rotation and/or posterior tilting. The incidence of subsidence and its association with pain is poorly understood. This radiographic study aimed to evaluate the incidence of tibial subsidence and five-year patient reported outcome measures (PROMs) of a cementless OUKR cohort.MethodologyCementless OUKRs from a high-volume centre with acceptable post-operative and five-year radiographs were included. Subsidence was determined by measuring the angle of the tibial tray/tibial axis angle and distance between the tibial tray axis and fibula head on anteroposterior and lateral radiographs using a custom MATLAB program. Analysis of 5-year PROMs assessed the relationship between subsidence and pain. Radiographs indicating tibial subsidence were validated by two observers.ResultsRadiographs of 94 cementless OUKRs were analysed of which five tibial components had subsided (incidence=5%) with an average of 1.92° varus rotation and 2.97° posterior tilt. Subsidence appeared to occur within the first post-operative year with all tibial components fixed securely at 5 years. Two subsiders had moderate pain (ICOAP=20.5,15.9, AKSS Pain=20,45) and lower Oxford Knee Scores (OKS=26,31) compared to the cohort means (ICOAP=3.91, AKSS Pain=45.9, OKS = 43.6). These two subsiders had BMIs greater than 30.ConclusionThis study found 5% of cementless OUKRs in the cohort underwent tibial subsidence. Subsidence with moderate pain occurred in 2% of cases, and pain may be associated with obesity. A larger study is needed to study subsidence in greater detail.

Clinical and Functional Results of Cementless Unicompartmental Knee Arthroplasty with a Minimum Follow Up of 5 Years—A Consecutive Cohort of 201 Patients

The number of unicompartmental knee replacements (UKR) is increasing. Alongside various advantages, the revision rate of cemented UKR is higher compared to total knee arthroplasty (TKR). In contrast, cementless fixation shows reduced revision rates, compared to the cemented UKR. However, most of the recent literature is based on designer-dependent studies. In this retrospective, single-center cohort study, we investigated patients who underwent cementless Oxford UKR (OUKR) between 2012 and 2016 in our hospital with a minimum follow-up of five years. Clinical outcome was evaluated using the OKS, AKSS-O, AKSS-F, FFbH-OA, UCLA, SF-36, EQ-5D-3L, FJS, ROM, pain, and satisfaction measures. Survival analysis was performed with reoperation and revision as endpoints. We included 201 patients (216 knees) for clinical evaluation. All outcome parameters increased significantly from pre- to postoperative stages. The five-year survival rate was 96.1% for revision surgery and 94.9% for reoperation. The main reasons for revision were the progression of osteoarthritis, inlay dislocation, and tibial overstuffing. Two iatrogenic tibial fractures appeared. Cementless OUKR shows excellent clinical outcome and high survival rates after five years. The tibial plateau fracture in cementless UKR represents a serious complication and requires modification of the surgical technique.

Complications, Reasons for Reoperation, and 5-Year Prosthesis Survival Compared between the Cemented and Cementless Oxford Unicompartmental Knee Arthroplasty in Thai Patients

Background: Oxford unicompartmental knee arthroplasty (OUKA) yields favorable outcomes in patients with medial compartmental knee osteoarthritis. However, it remains unknown whether cemented or cementless OUKA fixation delivers better outcomes in Asian population. Objective: To investigate the complications, reasons for reoperation, and 5-year prosthesis survival compared between cemented and cementless OUKA in Thai patients. Materials and Methods: Four hundred sixty-six cemented and 36 cementless OUKA performed between 2011 and 2015 with a minimum follow-up of five years were included. With reoperation for any reason as the endpoint, Kaplan-Meier analysis was performed to compare 5-year implant survival between groups. Complications, reasons for reoperation, and 90-day morbidity and mortality were compared between groups. Cox proportional hazards model was used to identify independent predictors of implant survival. Results: There was no significant difference in 5-year implant survival between the cemented and the cementless groups at 96.4% versus 94.4% (p=0.375). The mean implant survival time was 113.0±0.8 and 70.8±1.9 months in the cemented and the cementless groups, respectively (p=0.383). The most common reason for reoperation was bearing dislocation, and only one patient had 90-day morbidity. There was no significant difference between groups for complications or reasons for reoperation. No independent predictors of implant survival were identified in multivariate analysis. Conclusion: OUKA was shown to be a safe and durable reconstructive procedure in Thai patients with medial compartmental knee osteoarthritis. There was no significant difference in implant survival between the cemented and the cementless groups during the 5-year follow-up, and no independent predictors of implant survival were identified. Trial registration: Thai Clinical Trials Registry, TCTR20200427004, registered 27 April 2020, retrospectively registered Keywords: Complications; Reasons for reoperation; 5-year implant survival; Oxford unicompartmental knee arthroplasty (OUKA); Thailand

SIXTEEN-YEAR SURVIVAL AND FUNCTIONAL RESULTS OF THE CEMENTLESS OXFORD UNICOMPARTMENTAL KNEE REPLACEMENT

Cementless fixation is an alternative to cemented unicompartmental knee replacement (UKR), with several advantages over cementation. This study reports on the 15-year survival and 10-year clinical outcomes of the cementless Oxford unicompartmental knee replacement (OUKR).This prospective study describes the clinical outcomes and survival of first 693 consecutive cementless medial OUKRs implanted in New Zealand.The sixteen-year survival was 89.2%, with forty-six knees being revised. The commonest reason for revision was progression of arthritis, which occurred in twenty-three knees, followed by primary dislocation of the bearing, which occurred in nine knees. There were two bearing dislocations secondary to trauma and a ruptured ACL, and two tibial plateau fractures. There were four revisions for polyethylene wear. There were four revisions for aseptic tibial loosening, and one revision for impingement secondary to overhang of the tibial component. There was only one revision for deep infection and one revision where the indication was not stated. The mean OKS improved from 23.3 (7.4 SD) to 40.59 (SD 6.8) at a mean follow-up of sixteen years.In conclusion, the cementless OUKR is a safe and reproducible procedure with excellent sixteen-year survival and clinical outcomes.

Medium term results of the cementless Oxford mobile bearing medial unicompartmental knee replacement.

Medial Unicompartmental Knee Replacement (UKR) has well-documented benefits over Total Knee Replacement in the treatment of anteromedial osteoarthritis of the knee. There has been an increasing move from cemented to cementless UKR over the last decade. This non-design centre study assesses the initial experience using the cementless Oxford medial partial knee replacement and provides medium term revision data, as well as Patient Reported Outcome Measures (PROMs). A cohort of 200 consecutive patients undergoing medial UKR using the cementless Oxford were identified from our knee groups prospectively collected database. Cases were performed in a single centre under the care of one of four surgeons. All patients were beyond the 5-year minimum timepoint following UKR surgery in order to produce medium term results, at a mean of 7.9years. Eligible patients completed a postal questionnaire to collect PROMs: Oxford Knee Score, WOMAC and modified American Knee Society Score questionnaires in January 2020 and had their clinical records reviewed. The survivorship in our cohort was 94.5% at a mean follow up of 7.9years following surgery. There were 11 re-operations in total with a three percent risk of re-operation within the first 18months following surgery. There was a sustained improvement in Oxford Knee Score with a near 20 points improvement on pre-operative scores. Our results provide further evidence that partial knee replacements using the cementless Oxford produce good clinical outcomes. Revision rates are similar to those published in the National Joint Registry. III.

Comparisons of the Radiolucent Lines Between Cemented and Cementless Oxford Unicondylar Knee Arthroplasty: A Non-designer Group Report

Comparisons of the Radiolucent Lines Between Cemented and Cementless Oxford Unicondylar Knee Arthroplasty: A Non-designer Group Report

The Short-Term Results of Unıcondylar Knee Prosthesis in Patients with Body Mass İndex Over 35

Objective: To evaluate the short-term results and complications of unicondylar knee prosthesis in obese patients with medial compartment arthrosis.&#x0D; &#x0D; Method: Unicondylar knee prosthesis was applied to 41 patients (36 females, 5 males; average age 56 years) with BMI &gt;35 for the treatment of medial compartment arthrosis. Cementless Oxford phase 3 prosthesis was applied to all patients. Joint range of motion before and after surgery, VAS, OKS, and the KSS part 1 and part 2 scores of the patients were examined.&#x0D; &#x0D; Results: Flexion was measured as mean 115° (range, 90°- 135°) preoperatively, and 120° (range, 90° - 130°) postoperatively, extension as mean 0° (range, -10°- 0°) preoperatively and 0° (range,-15° - 0°) postoperatively, with no significant difference determined. The KSS Part 1 score was mean 58 (range, 36-82) preoperatively, and 85 (range, 57 - 96) postoperatively (p

Short distance from the keel to the posterior tibial cortex is associated with fracture after cementless Oxford UKA in Asian patients.

Tibial plateau fractures are serious complications of Oxford mobile-bearing unicompartmental knee arthroplasty (OUKA). This study examined where the fracture lines arises and evaluated the keel-cortex distances (KCDs) using three-dimensional computed tomography (3D-CT) and the effects of technical error (assessed by tibial component positions) and proximal tibial morphology on the KCDs. This retrospective study included 217 OUKAs with cementless tibial components. Fifteen patients had tibial fractures after surgery. Anterior and posterior KCDs and fracture line origins were assessed using 3D-CT postoperatively. Proximal tibial morphology was assessed using the medial eminence line (MEL), which runs parallel to the tibial axis and passes through the tip of the medial intercondylar eminence of the tibia on long-leg anteroposterior radiograph. Knees had overhanging medial tibial condyle if the MEL passed medially to the medial tibial cortex. KCDs were compared between patients with/without fractures. Tibial component positions were evaluated, considering effects of tibial morphologies and component positions on fracture prevalence and KCDs. Fracture lines were found between the keel and posterior cortex in 12/15 patients. Posterior KCDs were significantly shorter in patients with fractures than in patients without (2.7 ± 1.6mm vs 5.2 ± 1.7mm, P < 0.001). Patients with medial overhanging condyles were more likely to have fracture (10/51 vs 5/166, P < 0.001) and had significantly shorter posterior KCD than those without (3.6 ± 1.5mm vs 5.5 ± 1.8mm, P < 0.001). Patients with tibial component that was set too medial, low, and valgus had higher rates of fracture than those without (7/39 vs 8/178, P = 0.008). Medial (r = 0.30, P < 0.001), low (r = -0.33, P < 0.001), and valgus implantations (r = 0.35, P < 0.001) of tibial components were related to shorter posterior KCDs. Short posterior KCD after OUKA is a risk factor for postoperative tibial fracture. Patients with either malposition of the tibial component (too medial, low, and valgus) and/or a medial overhanging condyle exhibit a shorter distance of posterior KCD and higher rate of fracture. Level III.

Five-year results of a randomised controlled trial comparing cemented and cementless Oxford unicompartmental knee replacement using radiostereometric analysis

BackgroundCementless fixation is an alternative to cemented unicompartmental knee replacement (UKR). The aim of this study was to determine if cementless UKR fixation is as good as cemented by comparing the five-year migration measured radiostereometric analysis (RSA) in a randomised controlled trial. MethodsThirty-nine patients were randomised to receive either a cemented or a cementless Oxford UKR and were studied at intervals up to five years to assess migration with RSA and radiolucencies with radiographs. ResultsDuring the first year there was a small and significant amount of migration, predominantly in an anterior direction, of both the cemented (0.24 mm, SD 0.32, p = 0.01) and cementless (0.26 mm, SD 0.31, p = 0.00) femoral components. Thereafter there was no significant migration in any direction. At no stage was there any significant difference between the migrations of the cemented or cementless femoral components. During the first year, particularly the first three months, the cementless tibial components subsided 0.28 mm (SD 0.19, p = 0.00). This was significantly (p = 0.00) greater than the subsidence of the cemented tibial component (0.09, SD 0.19, p = 0.28). Between the second and fifth years there was no significant migration of either cemented or cementless tibial components.At five years radiolucent lines occurred significantly less with cementless (one partial) compared to cemented (six partial and one complete) tibial components. ConclusionsAs, between two and five years, there was no significant migration of cemented or cementless components, and no significant difference between them, we conclude that cementless fixation is as reliable as cemented. It may be better as there are fewer radiolucent lines.

Impact of correctable mediolateral tibiofemoral subluxation on unicompartmental knee arthroplasty implant survival in patients with anteromedial osteoarthritis

ABSTRACT BACKGROUND: Medial unicompartmental knee arthroplasty (UKA) is advocated for treating symptomatic anteromedial osteoarthritis (AMOA). Correctable mediolateral tibiofemoral (TF) subluxation can be safely ignored according to the UKA enthusiasts. However, no clinical studies compare the results in AMOA patients with and without subluxation. This study reports the early prospective clinical outcomes of medial UKA in AMOA, with and without correctable mediolateral TF subluxation and the comparison to the retrospective larger patient cohort. METHODS: The results of an initial retrospective study (R) consisting of 436 consecutive UKA cases (patients treated from May 2012 to October 2017) were compared to a prospective study (P) consisting of 272 consecutive UKA cases in 248 patients with AMOA (evaluated from November 2017 to May 2020). All patients in both cohorts underwent cementless Oxford UKA and were classified into two groups: group 1 (AMOA without mediolateral subluxation) and group 2 (AMOA with mediolateral subluxation) on anteroposterior (AP) radiological knee stress views. Survival analysis methods (Kaplan-Meier and logrank test) were utilised to compare implant survival between the two groups (1 and 2) and the cohorts (R and P). The multivariable Cox proportional hazards model was used to determine risk factors for time to revision. RESULTS: The two cohorts, R and P, had patient groups (group 1 vs group 2) matched for age, sex, wear pattern, preoperative Oxford Knee Score and follow-up period. The overall implant survival for the P cohort that had at least 20 months of follow-up was 98%. The overall implant survival for group 1 (99%) was significantly better compared to group 2 (93%). These results are amplified in the R cohort with an average follow-up of 54 months, and with the group 1 survival at 97% and group 2 at 86%. Subsequent months of follow-up show more failures in group 2 compared to group 1. Patient-reported outcome measures (PROMs) and range of movement were similar for both groups. CONCLUSION: Patients with AMOA and correctable mediolateral TF subluxation have a significantly higher risk of implant failure compared to those without subluxation. This study establishes this association, which has an important implication on patient selection, but does not confirm causality. Level of evidence: Level 4. Keywords: unicompartmental knee arthroplasty, partial, osteoarthritis, X-ray, implant

Tibial shape and size predicts the risk of tibial plateau fracture after cementless unicompartmental knee arthroplasty in Japanese patients.

Cementless unicompartmental knee arthroplasty (UKA) has advantages over cemented UKA, including improved fixation, but has a higher risk of tibial plateau fracture, particularly in Japanese patients. The aim of this multicentre study was to determine when cementless tibial components could safely be used in Japanese patients based on the size and shape of the tibia. The study involved 212 cementless Oxford UKAs which were undertaken in 174 patients in six hospitals. The medial eminence line (MEL), which is a line parallel to the tibial axis passing through the tip of medial intercondylar eminence, was drawn on preoperative radiographs. Knees were classified as having a very overhanging medial tibial condyle if this line passed medial to the medial tibial cortex. They were also classified as very small if a size A/AA tibial component was used. The overall rate of fracture was 8% (17 out of 212 knees). The rate was higher in knees with very overhanging condyles (Odds ratio (OR) 13; p < 0.001) and with very small components (OR 7; p < 0.001). The OR was 21 (p < 0.001) in those with both very overhanging condyles and very small components. In all, 69% of knees (147) had neither very overhanging nor very small components, and the fracture rate in these patients was 1.4% (2 out of 147 knees). Males had a significantly reduced risk of fracture (OR 0.13; p = 0.002), probably because no males required very small components and females were more likely to have very overhanging condyles (OR 3; p = 0.013). 31% of knees (66) were in males and in these the rate of fracture was 1.5% (1 out of 66 knees). The rate of tibial plateau fracture in Japanese patients undergoing cementless UKA is high. We recommend that cemented tibial fixation should be used in Japanese patients who require very small components or have very overhanging condyles, as identified from preoperative radiographs. In the remaining 69% of knees cementless fixation can be used. This approach should result in a low rate of fracture. Cite this article: Bone Joint J 2020;102-B(7):861-867.

Cementless medial Oxford unicompartmental knee replacement. Five-year results from an independent series

BackgroundUnicompartmental knee replacement (UKR) is a common treatment option for patients with advanced medial compartment knee arthritis. The Oxford UKR (OUKR) is the most commonly used implant for partial knee replacement. A cementless Oxford prosthesis was introduced in 2004 aiming to reduce the revision rate by potentially reducing radiolucencies as well as errors of cementation associated with the cemented prosthesis. Whilst results from the designer centre have been reported, there is little independent clinical evidence of outcomes.The aim of this study was to evaluate the survival of the cementless OUKR in a single surgeon series at an independent centre and to assess clinical and radiographic outcomes. MethodsAll patients who received a cementless medial OUKR and had a minimum of five-year follow-up were included in the series. The Oxford knee score was used to evaluate patient outcomes at five years postoperatively. Survival rates, complications and evidence of radiolucencies on plain radiographs were also reviewed. ResultsOne hundred and fifty-eight cementless medial OUKR were implanted in 126 patients. Three patients died and four knees were revised. The five-year survival was 97.4% and the median Oxford knee score was 43 at five years postoperatively. No Complete radiolucent lines were observed on radiographs at one year. Four tibial components subsided. ConclusionsThis independent series shows that low revision rates and excellent results can be achieved with the use of the cementless OUKR at five years. Early subsidence of the tibial component, which is specific to the cementless prosthesis, warrants further investigation.

Femoral migration of the cementless Oxford which caused the bearing dislocation: a report of two cases

BackgroundThere are no previous reports on the complications around the femoral component of cementless Oxford unicompartmental knee arthroplasty (UKA). However, we experienced two cases of femoral migration to the proximal side, which caused bearing dislocations after cementless Oxford UKA.Case presentationCase1. In an 82-year-old woman, bearing dislocation occurred 13 months postoperatively because of femoral migration that was resolved with an revision surgery to cemented component and thicker mobile insert.Case2. In a 52-year-old man, first bearing dislocation occurred 7 months postoperatively. Five months after revising the insert to a thicker one, another dislocation occurred mainly because of the femoral migration. Eventually, a revision to total knee arthroplasty was necessary.ConclusionsThe inferred main reasons of femoral migration of cementless Oxford were osteoporosis for the first case and early return to high performance sports activity for the second case. Although several merits of using cementless prosthesis, particularly better fixation and lesser radiolucency than cemented prosthesis, have been reported, surgeons should pay attention to the patient’s bone quality and advise a slow return to high-level physical activity.

EVALUATION OF RADIOLUCENCY AND SUBSIDENCE OF THE CEMENTLESS OXFORD MEDIAL UNICOMPARTMENTAL KNEE REPLACEMENT

Background: The most popular unicompartmental knee replacement(UKR) prosthesis to treat medial compartmentosteoarthritis (OA) is the Oxford knee (OUKR). This prosthesis now has cemented and cementless fixation options.The fixation of the new cementless implants has proved successful with significantly reduced radiolucent lines compared to the cemented prosthesis in the designer series. Unfortunately, some studies have reported tibial component subsidence as a specific complication to the cementless design. Aim of the Work: This study aims to review the fixation and clinical outcomes of the cementless prosthesis. We report the incidence of radiolucent lines associated with both cementless andcemented tibial prosthesis. More importantly, to study the incidence of tibial component subsidence. Materials and Methods: This is a prospective study of a consecutive series of the Oxford medial UKR. All patients had bone on bone arthritisfulfilling the criteria for anteromedial OA. All patients received cementless femur implants. The majority of patients received cementless tibial implants. Cemented tibial component was only used in elderly patients where the tibial metaphyseal bone was found potentially weak intraoperatively. Fluoroscopy-aligned radiographs were obtained post-operatively and at one-year.Radiolucent lines and subsidence were evaluated. All patients completed the Oxford kneequestionnaire (OKS) at one-year follow-up. Results: A total of 68 knees implanted in 59 patients completed the study. Fully cementless medial OUKR (n=61), and cemented tibial with cementless femur (n=7). The mean age was 67.5 years. Two patients required revision to TKR. The cemented design had higher incidence of radiolucent lines. One patient had Cementless tibial component subsidence. The median OKS was excellent in both groups. Conclusion: Both designs of the OUKR are valid treatment optionswith excellent OKS. Radiolucent lines are less frequent with the cementless design buttibial component subsidence and fracture have a higher incidence compared to the cemented prosthesis.

Cementless Oxford Medial Unicompartmental Knee Replacement-Clinical and Radiological Results of 228 Knees with a Minimum 2-Year Follow-Up.

(1) Background: Studies show several advantages of unicompartmental knee replacement (UKR) over total knee replacements (TKR), whereas registry based revision rates of UKR are significantly higher than for TKA. Registry data report lower revision rates for cementless UKR compared to cemented UKR. The aim of this study was to assess clinical and radiological results of cementless Oxford UKR (OUKR) in an independent cohort. (2) Methods: This retrospective cohort study examines a consecutive series of 228 cementless OUKR. Clinical outcome was measured using functional scores (Oxford Knee Score (OKS), American Knee Society Score (AKSS), Hannover Functional Ability Questionnaire for Osteoarthritis (FFbH-OA), range of motion (ROM)), pain and satisfaction. Radiographs were analyzed regarding the incidence of radiolucent lines (RL), implant positioning, and their possible impact on clinical outcome. (3) Results: At a mean follow-up of 37.1 months, the two and three year revision free survival-rates were 97.5% and 96.9%. Reasons for revision surgery were progression of osteoarthritis, inlay dislocation and pain. All clinical outcome scores showed a significant improvement from pre- to postoperative. The incidence of RL around the implant was highest within the first year postoperatively (36%), and decreased (5%) within the second year. Their presence was not correlated with inferior clinical outcome. Implant positioning showed no influence on clinical outcome. (4) Conclusion: Cementless OUKR showed excellent clinical outcome and survival rates, with reliable osteointegration. Neither the incidence of radiolucent lines nor implant positioning were associated with inferior clinical outcome.