Analysis of the causes of primary revision after unicompartmental knee arthroplasty: A case series

BACKGROUND Unicompartmental knee arthroplasty(UKA)has great advantages in the treatment of unicompartmental knee osteoarthritis,but its revision rate is higher than that of total knee arthroplasty.AIM To summarize and analyse the causes of revision after UKA.METHODS This is a retrospective case series study in which the reasons for the first revision after UKA are summarized.We analysed the clinical symptoms,medical histories,laboratory test results,imaging examination results and treatment processes of the patients who underwent revision and summarized the reasons for primary revision after UKA.RESULTS A total of 13 patients,including 3 males and 10 females,underwent revision surgery after UKA.The average age of the included patients was 67.62 years.The prosthesis was used for 3 d to 72 months.The main reasons for revision after UKA were improper suturing of the surgical opening(1 patient),osteophytes(2 patients),intra-articular loose bodies(2 patients),tibial prosthesis loosening(2 patients),rheumatoid arthritis(1 patient),gasket dislocation(3 patients),anterior cruciate ligament injury(1 patient),and medial collateral ligament injury with residual bone cement(1 patient).CONCLUSION The causes of primary revision after UKA were gasket dislocation,osteophytes,intra-articular loose bodies and tibial prosthesis loosening.Avoidance of these factors may greatly reduce the rate of revision after UKA,improve patient satisfaction and reduce medical burden.

Analysis of causes for revision in unicompartmental knee arthroplasty

The study by Zhao et al identifies the factors leading to the failure of unicompartmental knee arthroplasty(UKA)in their patients.These factors include substandard suturing of the wound,the presence of osteophytes and intra-articular loose bodies causing impingement,premature loosening of the tibial component,choosing unsuitable patients for the procedure,dislocation of the movable insert,and damage to the anterior cruciate ligament and medial collateral ligament.The findings suggest that employing the correct surgical techniques and indications is essential for successful outcomes in the UKA.

How to manage and avoid revision after unicompartmental knee arthroplasty?

The article by Zhao et al presents a retrospective case series on the reasons for initial revision after unicompartmental knee arthroplasty(UKA).Clarifying the reasons that may cause UKA revision can further reduce the rate of revision UKA,focusing on gasket dislocation,osteophytes,intra-articular loose bodies,and tibial prosthesis loosening.This article provides valuable insights,not only by detailing the revision status of 13 patients who underwent revision after initial UKA but also by providing a comprehensive analysis of the incidence of revision after initial UKA.By reviewing and analyzing the causes,they established references for the early detection of risk factors for revision in clinical practice and for formulating surgical strategies and rehabilitation programmes.This commentary emphasizes the need for a meticulous understanding and an analysis of the revision rate following initial UKA and related management strategies.The implant rates,regional variation,and benefits of uncemented Oxford UKA have been explored,particularly in terms of bone preservation,appropriate surgical techniques,and weight management to control complications and improve patient prognosis.

Insights into complications after unicompartmental knee arthroplasty

Zhao's study,offers a comprehensive analysis of unicompartmental knee arthroplasty(UKA)revision indications.The study provides a detailed,case-by-case analysis of the factors leading to knee revision surgery in 13 patients.Not only elucidates the complexities of UKA revisions but also underscores the importance of continuous improvement in surgical techniques and the adoption of innovative technologies.

Outcomes of mobile bearing unicompartmental knee arthroplasty in medial osteoarthritis knee with and without preoperative genu recurvatum

AIM To compare clinical outcomes of patients with and without preoperative genu recurvatum(GR) following mobile bearing unicompartmental knee arthroplasty(UKA). METHODS We prospectively followed 176 patients for at least 24 mo who had been treated by unilateral, minimally invasive, Oxford UKA. Patients with medial osteoarthritis(OA) knee and preoperative GR(Group Ⅰ) accounted for 18%(n = 32) and patients without preoperative GR(Group Ⅱ) accounted for the remaining 82%(n = 144). Knee score, pain scores, and functional scores were assessed for each patient and compared between the two groups. The incidence of postoperative GRand the postoperative hyperextension angles also were recorded and analyzed. RESULTS The pain score, knee score and functional score were not significantly different between the two groups. Similarly, the incidence of postoperative GR and the measured hyperextension angles were not significantly different between the two groups. The incidence of postoperative GR was 1/32(3.12%) in Group Ⅰ and 1/144(0.69%) in Group Ⅱ(P = 0.34). The mean postoperative hyperextension angles were 2.40°± 2.19°(range: 1°-7°) for Group Ⅰ and 1.57°± 3.51°(range: 1°-6°) for Group Ⅱ(P = 0.65).CONCLUSION Medial OA of the knee and concomitant GR is not a contraindication for the mobile bearing UKA.

Lateral unicompartmental knee arthroplasty:A review

Isolated lateral compartment osteoarthritis of the knee is a rare condition affecting approximately 1%of the population,which is ten times less common than osteoarthritis affecting only the medial compartment.Unicompartmental knee arthroplasty(UKA)has many potential advantages over total knee arthroplasty.The benefits of UKA include a smaller incision,preservation of more native tissue(including cruciate ligaments and bone),decreased blood loss,and better overall proprioception.When UKA was first introduced in the 1970s,the outcomes of medial UKA(MUKA)were poor,but the few cases of lateral UKA(LUKA)showed promise.Since that time,there has been a relative paucity of literature focused specifically on LUKA given it is a rare procedure.Refinements in patient selection criteria,implant design,and surgical technique have been made leading to increased popularity.A review of the recent literature reveals that LUKA is associated with excellent long-term clinical outcomes and implant survivorship when performed in properly selected patients.Implant design options include fixed vs mobile bearing as well as metal backed vs all polyethylene tibial component,with improved outcomes noted with fixed bearing designs.Three reasons cited for revision(i.e.,fracture of the femoral component,fracture of the tibial component,and valgus malalignment)had been reported in past literature but not recently.Presently,while rare,the most common cause of failure and need for revision are osteoarthritis progression and aseptic loosening.Despite the need for an occasional revision procedure,the survivorship of LUKA is comparable to MUKA,although it should be noted that outcomes of MUKA have been notably varied.Continued pursuit of improved techniques and implant designs will continue to show LUKA to be an excellent procedure for appropriately indicated patients.

Unicompartmental knee prosthetization: Which key-points to consider?

Unicompartmental knee arthroplasty(UKA) has evolved into a suitable option for diseased knees that cannot be managed with arthroscopic treatment and at the same time are not good candidates for total knee replacement. Since meticulous execution of the surgical technique is essential to optimizing UKA outcome, some procedural key-points are mandatory. Templates(phantoms) are then used to size the required prosthetic component(using these radiographs. Arthritic varus(or valgus) knees with an asymptomatic patellofemoral joint are typically ideal for UKA. Metal-backed tibial components should be favourite instead of allpolyethylene tibial components to avoid polyethylene creep that may occur in fixed bearings. Moreover, a proper thickness of the polyethylene layer is mandatory, in order to avoid early failure.

Internal fixation and unicompartmental knee arthroplasty for an elderly patient with patellar fracture and anteromedial osteoarthritis:A case report

BACKGROUND Open reduction and internal fixation(ORIF)is the traditional surgical treatment for patellar fractures,and unicompartmental knee arthroplasty(UKA),especially Oxford UKA,has been increasingly used in patients with medial knee osteoarthritis(OA).However,the process of choosing treatment for patients with both patellar fractures and anteromedial knee OA remains unclear.We present the case of a patient with a patellar fracture and anteromedial OA.CASE SUMMARY We present the case of a 72-year-old woman with a history of bilateral medial compartment OA of the knees and a right Oxford UKA.She also experienced a recent left patellar fracture.ORIF and Oxford UKA were performed in a single stage.The patient showed excellent postoperative clinical results.CONCLUSION ORIF and Oxford UKA can be performed simultaneously for patients with patellar fracture and anteromedial OA on the same knee.

A Research on the Early Effect of Unicompartmental Knee Arthroplasty for Unicompartment Osteoarthritis of the Knee

Objective: To evaluate the early clinical effect of unicompartmental knee arthroplasty (UKA) for medial unicompartment osteoarthritis of knee in the old people, providing the evidence for the treatment of clinic. Methods: From January of 2016 to January of 2017, 20 cases of knee osteoarthritis in medial unicompartment were treated by unicompartmental knee arthroplasty. The knee joint range of motion (ROM), visual analogue scale (VAS) and knee functional Hospital for Special Surgery (HSS) scores were preoperatively recorded. The loss of blood and time of operation were intraoperative recorded. The satisfaction of patient, knee joint range of motion (ROM) and knee functional special surgical hospital score (HSS score) were postoperatively recorded at one year. Results: All patients have been followed up at an average of twelve months. The operation time was 94 - 135 min, mean 105.6 min. The blood loss was 150 - 500 ml, mean 315 ml. The postoperative HSS and ROM were both reduced. The last follow-up, there were no meniscus subluxation, loose prosthesis, and lateral ventricular osteoarthritis or other complications. Conclusion: Unicompartmental knee arthroplasty has the advantages of small operation trauma, early postoperative effect and quick recovery.

Unicompartmental Knee Arthroplasty: A Perspective from Computer Assisted Navigation

Unicompartmental Knee Arthroplasty (UKA) is an established procedure for the treatment of unicompartmental arthritis. Success depends on a clear understanding of the principles and kinematics of the knee. Restoration of the physiological axis and soft tissue balancing is the key to a successful outcome. We outline the basic principles of UKA and the role of computer assisted surgery in achieving these goals.

Determining the Effect of Deprivation on Quality of Life after Total and Unicompartmental Knee Arthroplasty

Determining the effect of deprivation on quality of life after total and unicompartmental knee arthroplasty Quality of life (QoL) following joint replacement is now a national priority, with every patient being assessed using the Oxford Knee Score. The current literature is conflicted as to whether deprivation has any effect on outcome after knee surgery. The type of surgery is another variable that may determine outcome. We set out to investigate which of these factors was a more powerful predictor of outcome. A prospective trial began where, 68 patients were telephoned, (30 TKA’s and 38 UKA’s). Each were asked a series of questions comprising the Oxford Knee Score (post operation), Imperial Knee Score (post operation), EuroQol-5D (pre and post operation) and individual deprivation questions. This was compared with the deprivation status using Townsend scores. A comparison of total and unicompartmental outcomes were also analysed including cost-effectiveness. No correlation was found between outcome and Townsend scores (p < 0.05). Age was seen to be a significant indicator of pre surgical QoL. However, a large and significant difference was found between UKA and TKA when using the EQ-5D (p < 0.05) and the Imperial Knee Score (p < 0.09). This was not reflected in the Oxford Knee Score. UKA’s were also found to be more cost-effective than TKA’s. Deprivation has no major effect on the outcome of knee surgery in London. A clear difference in efficacy exists between TKA’s and UKA’s. Sensitivity of scores needs to be addressed.

<i>In vitro</i>measurement of tibiofemoral kinematics after patient-specific unicompartmental knee replacement

It is suggested that unicompartmental knee replacement (UKR) offers the potential to restore normal knee kinematics better than total knee replacement (TKR) because of retaining the cruciate ligaments, and better preservation of the overall geometry. It was hypothesized that patient-specific UKR would restore normal knee kinematics even better because of a customised articular shape. A comparative kinematics study was conducted on three cadaver limbs using two different test setups, a loaded ankle rig and an unloaded ankle rig. Kinematics was compared between a patient-specific UKR and a conventional fixed-bearing UKR. Both the UKRs showed similar kinematic patterns to the normal knee using both the test apparatus. The patient-specific UKR showed good results and with the other benefits it shows potential to dramatically improve clinical outcomes of knee replacement surgery.

Influence of patellofemoral joint degeneration on clinical outcomes after medial unicompartmental knee arthroplasty

Background:Patellofemoral joint(PFJ)degeneration has traditionally been regarded as a contraindication to unicompartmental knee arthroplasty(UKA).More recently,some researchers have proposed that PFJ degeneration can be ignored in medial UKA,and others have proposed that this change should be reviewed in PFJ degenerative facets and severity.This study aimed to systematically evaluate the effect of PFJ degeneration on patient-reported outcome measures(PROMs)and revision rates after medial UKA.Methods:Electronic databases(PubMed,Embase,Web of Science,etc.)were searched for studies assessing the influence of PFJ degeneration on medial UKA.A random-effects meta-analysis was conducted for the Oxford knee score(OKS),Knee society score(KSS),and revision rates and stratified by PFJ degenerative facets(medial/lateral/trochlear/unspecified),severe PFJ degeneration(bone exposed),and bearing type(mobile/fixed).Heterogeneity was assessed by the Cochran Q test statistic and chi-squared tests with the I-squared statistic.Results:A total of 34 articles with 7007 knees(2267 with PFJ degeneration)were included(5762 mobile-bearing and 1145 fixed-bearing and 100 unspecified).Slight to moderate degenerative changes in the medial and trochlear facets did not decrease the OKS and KSS,and only lateral facets significantly decreased the OKS(mean difference[MD]=-2.18,P<0.01)and KSS(MD=-2.61,P<0.01).The severity degree of PFJ degeneration had no additional adverse effect on the OKS,KSS,or revision rates.For mobile-bearing UKA,only lateral PFJ degeneration significantly decreased the OKS(MD=-2.21,P<0.01)and KSS(MD=-2.44,P<0.01).For fixed-bearing UKA,no correlation was found between PROMs/revision rates and PFJ degeneration.Conclusion:For medial mobile-bearing UKA,slight to moderate degenerative changes in the PFJ,except lateral facet,did not compromise PROMs or revision rates.For medial fixed-bearing UKA,although it might not be conclusive enough,PROMs or revision rates were not adversely affected by PFJ degeneration(regardless of the facet).

Finite Element Analysis of Mobile-bearing Unicompartmental Knee Arthroplasty： The Influence of Tibial Component Coronal Alignment

Background： Controversies about the rational positioning of the tibial component in unicompartmental knee arthroplasty （UKA） still exist. Previous finite element （FE） studies were rare, and the results varied. This FE study aimed to analyze the influence of the tibial component coronal alignment on knee biomechanics in mobile-bearing UKA and find a ration range of inclination angles. Methods： A three-dimensional FE model of the intact knee was constructed from image data of one normal subject. A 1000 N compressive load was applied to the intact knee model for validating. Then a set of eleven UKA FE models was developed with the coronal inclination angles of the tibial tray ranging from 10° valgus to 10° varus. Tibial bone stresses and strains, contact pressures and load distribution in all UKA models were calculated and analyzed under the unified loading and boundary conditions. Results： Load distribution, contact pressures, and contact areas in intact knee model were validated. In UKA models, von Mises stress and compressive strain at proximal medial cortical bone increased significantly as the tibial tray was in valgus inclination 〉4°, which may increase the risk of residual pain. Compressive strains at tibial keel slot were above the high threshold with varus inclination 〉4°, which may result in greater risk of component migration. Tibial bone resection comer acted as a strain-raiser regardless of the inclination angles. Compressive strains at the resected surface slightly changed with the varying inclinations and were not supposed to induce bone resorption and component loosening. Contact pressures and load percentage in lateral compartment increased with the more varus inclination, which may lead to osteoarthritis progression. Conclusions： Static knee biomechanics after UKA can be greatly affected by tibial component coronal alignment. A rauge from 4° valgus to 4° varus inclination oftibial component can be recommended in mobile-bearing UKA.

A modified technique for tibial bone sparing in unicompartmental knee arthroplasty

Background:Previously,the authors modified the surgical technique to preserve tibial bone mass for Oxford unicompartmental knee arthroplasty(UKA).The purpose of this study was to determine the clinical outcomes and values of this modified technique.Methods:Clinical data of 34 consecutive patients who underwent the unilateral modified UKA technique(modified group,34 knees)were retrospectively analyzed.To compare the outcome,a match-paired control group(conventional group,34 knees)of an equal number of patients using the conventional technique system in the same period were selected and matched with respect to diagnosis,age,pre-operative range of motion(ROM),and radiological grade of knee arthrosis.Clinical outcomes including knee Hospital for Special Surgery(HSS)score,ROM,and complications were compared between the two groups.Post-operative radiographic assessments included hip-knee-ankle angle(HKA),joint line change,implant position,and alignment.Results:The mean follow-up time was 38.2±6.3 months.There was no difference in baseline between the two groups.The amount of proximal tibial bone cut in the modified group was significantly less than that of the conventional group(4.7±1.1 mm vs.6.7±1.3 mm,t=6.45,P<0.001).Joint line was elevated by 2.1±1.0 mm in the modified group compared with-0.5±1.7 mm in the conventional group(t=-7.46,P<0.001).No significant differences were observed between the two groups after UKA with respect to HSS score,VAS score,ROM,and HKA.Additionally,the accuracy of the post-operative implant position and alignment was similar in both groups.As for implant size,the tibial implant size in the modified group was larger than that in the conventional group(x^2=4.95,P=0.035).Conclusions:The modified technique for tibial bone sparing was comparable with the conventional technique in terms of clinical outcomes and radiographic assessments.It can preserve tibial bone mass and achieve a larger cement surface on the tibial side.

Clinical Outcomes and Risks of Single-stage Bilateral Unicompartmental Knee Arthroplasty via Oxford Phase III

Background： Osteoarthritis often affects the joint bilaterally, and the single-stage （SS） unicompartmental knee arthroplasty （UKA） is advantageous in terms of a single anesthesia administration, a short hospital stay, lower medical costs, and enhanced patient convenience. However, the complication risk of SS UKA continues to be debated. The aim of this article was to evaluate the clinical effectiveness, complications, and functional recovery of SS and two-stage （TS） UKA. Methods： From January 2008 to December 2013, we compared a series of 36 SS UKA with 45 TS UKA for osteoarthritis. The mean age was 65.4 years （range： 55-75 years）. The mean body mass index was 25.2 kg/m^2 （range： 22-29 kg/m^2）. The preand post-operative Oxford Knee Scores （OKSs）, complications, operative times, tourniquet times, the amount of drainage, and hemoglobin （Hb） were evaluated. The Chi-square test, Fisher＇s exact test, and paired and grouped t-tests were used in this study. Results： The mean tbllow-up was 50 months. No complications of death, fat embolism, deep vein thrombosis, and prosthetic infection were reported. Patients who underwent SS U KA had a shorter cumulative anesthesia time （ 113.5 vs. 133.0 rain, P 〈 0.01 ）. There were no significant variations between the values of the mean tourniquet time, the amount of drainage, pre- and post-operative Hb in the different groups. No patient required a blood transfusion. No statistical differences were found in the complications between two groups （P 〉 0.05）. At the final follow-up, the mean OKS improved from 39.48 ±5.69 to 18.83 ± 3.82 （P 〈 0.01 ）, with no statistical differences between the two groups （P 〉 0.05）. Patients who underwent SS UKA had a faster recovery. Conclusions： The single-staged UKA offers the benefits of a single anesthesia administration, redticed total anesthetic time, decreased overall rehabilitation time, and absence of an increase in perioperative mortality or complications compared with the TS bilateral UKA.

Glycosaminoglycan Content of the Lateral Compartment Cartilage in Knees Conforming to the Indications for Oxford Medial Unicompartmental Knee Arthroplasty

Background： The quality of the lateral compartment cartilage is important to preoperative evaluation and prognostic prediction of unicompartmental knee arthroplasty （UKA）. Delayed gadolinium-enhanced magnetic resonance imaging of cartilage （dGEMRIC） enables noninvasive assessment of glycosaminoglycan （GAG） content in cartilage. This study aimed to determine the GAG content of the lateral compartment cartilage in knees scheduled to undergo Oxford medial UKA. Methods： From December 2016 to May 2017, twenty patients （20 osteoarthritic knees） conforming to the indications fbr Oxford medial UKA were included as the osteoarthritis （OA） group, and 20 healthy volunteers （20 knees） paired by sex, knee side, age （±3 years）, and body mass index （BMI） （i3 kg/m2） were included as the control group. The GAG contents of the weight-bearing femoral cartilage （wbFC）, the posterior non-weight-bearing femoral cartilage （pFC）, the lateral femoral cartilage （FC）, and tibial cartilage （TC） were detected using dGEMRIC. The dGEMRIC indices （T1Gd） were calculated in the middle three consecutive slices of the lateral compartment. Paired t-tests were used to compare the T1Gd in each region of interest between the OA group and control group. Results： The average age and BMI in the two groups were similar. In the OA group, TIGd of FC and TC was 386.7 ± 50.7 ms and 429.6 ± 59.9 ins, respectively. In the control group, T1Gd of FC and TC was 397.5 ± 52.3 ms and 448.6 ±62.5 ms, respectively. The respective T 1Gd ofwbFC and pFC was 380.0 ± 47.8 ms and 391.0 ± 66.3 ms in the OA group and 400.3 ± 51.5 ms and 393.6 ± 57.9 ms in the control group. Although the T 1Gd ofwbFC and TC tended to be lower in the OA group than the control group, there was no significant difference between groups in the TIGd in any of the analyzed cartilage regions （P value ofwbFC, pFC, FC, and TC was 0.236, 0.857, 0.465, and 0.324, respectively）. Conclusions： The GAG content of the lateral compartment cartilage in knees confonning to indications for Oxford medial UKA is similar with those of age- and BMl-matched participants without OA.

Current Trends in Clinical Practice for the Minimal Invasive Medial Unicondylar Knee Arthroplasty

Unicondylar Knee Arthroplasty (UKA) is an early alternative surgical procedure for the unicondylar osteoarthritis or damaged knee joint with artificial prosthesis for the release of disabling painful condition and restoring the normal knee functions. Minimally UKA is one of the recent and the majority successful procedures in modern orthopedics for the osteoarthritis which is spreading throughout the worldwide. Recently, many orthopedic surgeons are expanding their abilities in this field. However, it needs good knowledge and well experience for the successful clinical outcomes. The minimal invasive approach is more efficient for short hospital stay and faster postoperative recovery with low morbidity of the patients after UKA. The aim of this article is to emphasize the steps in UKA based on modern facts: function of knee joint, diagnosis, less invasive approach for medial condylar replacement, radiographic evaluation, and earlier recovery, selecting the patient and implant survivorship with review of surgery.

Clinical Characteristics and Treatment of Spontaneous Osteonecrosis of Medial Tibial Plateau： A Retrospective Case Study

Background： In a small proportion of cases, spontaneous osteonecrosis of the knee （SONK） involves the medial tibial plateau （MT）. Here, we introduced the clinical characteristics of spontaneous osteonecrosis of the MT and unicompartmental knee arthroplasty （UKA） as the favorable treatment for this situation based on a retrospective case study. Methods： Patients with spontaneous osteonecrosis of the MT, confirmed by magnetic resonance imaging （MRI） at Guangdong Provincial Hospital of Chinese Medicine （China） from March 2015 to June 2016, were included as a case serial and analyzed retrospectively. All patients underwent Oxford Medial UKA. The characteristics of their lesions, corresponding treatment, and results of follow-up were presented. The lesion scores and grade were determined according to the criteria of Ficat and Arlet. Results： In total, 22 patients （5 men, 17 women： mean age, 64.1 years） with spontaneous osteonecrosis of the MT were analyzed. The lesion stages assessment showed that 3 （14%） were Stage 11, 10 （45%） were Stage Ⅲ, 7 （32%） were Stage IV, and 2 （9%） were Stage V. In the sagittal plane, 7 （32%） were in the anterior region （MTa） and 15 （68%） were central （MTc）. The lesion volume averaged 2.24 ± 0.79 cm3 （range： 1.57-3.08 cm3）. Seventeen patients （77%） had Level Ⅲ posterior medial meniscus root tears （MM RTs）. All the patients underwent UKA. Average follow-up was 30.0 ± 6.4 months with a range of 23.0-38.0 months. The visual analog scale score was 7.78 ± 0.67 belbre surgery while decreased to 2.22 ± 1.09 at the final follow-up （P 〈 0.001 ）. The Hospital for Special Surgery scores of pre-/post-surgery were 65.67 ± 5.45 and 84.10 ± 4.20, respectively （P 〈 0.001 ）. Conclusions： SONK often occurs in the anterior and central tibial plateau due to abnormal stresses. Most of the patients had Level Ⅲ posterior medial meniscus root tears. MRI is recommended for suspected cases to identity SONK at an early stage. The use of the Oxford Medial UKA for SONK of the MT is reliable both immediately and at follow-up.