The surgical installation accuracy of the components in unicompartmental knee arthroplasty (UKA) is an important factor affecting the joint function and the implant life. Taking the ratio of the medial-lateral position of the femoral component relative to the tibial insert (a/A) as a parameter, and considering nine installation conditions of the femoral component, this study established the musculoskeletal multibody dynamics models of UKA to simulate the patients’ walking gait, and investigated the influences of the medial-lateral installation positions of the femoral component in UKA on the contact force, joint motion and ligament force of the knee joint. The results showed that, with the increase of a/A ratio, the medial contact force of the UKA implant was decreased and the lateral contact force of the cartilage was increased; the varus rotation, external rotation and posterior translation of the knee joint were increased; and the anterior cruciate ligament force, posterior cruciate ligament force and medial collateral ligament force were decreased. The medial-lateral installation positions of the femoral component in UKA had little effect on knee flexion-extension movement and lateral collateral ligament force. When the a/A ratio was less than or equalled to 0.375, the femoral component collided with the tibia. In order to prevent the overload on the medial implant and lateral cartilage, the excessive ligament force, and the collision between the femoral component and the tibia, it is suggested that the a/A ratio should be controlled within the range of 0.427−0.688 when the femoral component is installed in UKA. This study provides a reference for the accurate installation of the femoral component in UKA.
ObjectiveTo explore the gait trajectory characteristics and effectiveness after unicompartmental knee arthroplasty (UKA).MethodsThirty patients (30 knees) with anterior medial compartment osteoarthritis who were treated with UKA between January 2017 and December 2018 were selected as subjects (UKA group). According to age, gender, and side, 30 patients (30 knees) with knee osteoarthritis treated with total knee arthroplasty (TKA) were selected as control (TKA group). In addition to the range of motion (ROM) before operation showing significant difference between the two groups (t=4.25, P=0.00), there was no significant difference in gender, age, disease duration, sides, body mass index, and preoperative hip-knee-ankle angle (HKA), Western Ontario and McMaster University Osteoarthritis Index (WOMAC) score between the two groups (P>0.05). The incision length, drainage volume within 24 hours after operation, and the changes of hemoglobin and albumin were recorded. The WOMAC score, ROM, and HKA before and after operation were compared between the two groups. At 1 year after operation, the gait trajectory characteristics of two groups were analyzed by Vicon three-dimensional gait capture system, and the absolute symmetry index (ASI) of the lower limbs of the two groups was calculated.ResultsThe incisions of the two groups healed by first intention, with no complications. The incision length, drainage volume within 24 hours, and the changes of hemoglobin and albumin after operation in the UKA group were significantly smaller than those in the control group (P<0.05). All patients were followed up completely, the follow-up time ranged from 13 to 20 months of UKA group (mean, 18 months) and 16 to 24 months of control group (mean, 20 months). The imaging review showed that the lower limb alignment of the two groups were restored to a neutral position, and the position of prosthesis was good. At 1 year after operation, the WOMAC score, HKA, and ROM of two groups were significantly improved when compared with those before operation (P<0.05); the postoperative WOMAC score and ROM of the UKA group were significantly better than those of the control group (P<0.05), and there was no significant difference in HKA between the two groups (t=1.54, P=0.13). Gait analysis at 1 year after operation showed that the walking speed, stride length, knee extension at mid-stance, and flexion at swing in the UKA group were significantly better than those in the TKA group (P<0.05); there was no significant difference in cadence, knee flexion at initial contact, and knee flexion at loading response between the two groups (P>0.05). The ASI of bilateral knee flexion in the UKA group was significantly greater than that in the TKA group during the initial contact and loading response period (P<0.05).ConclusionCompared with TKA, UKA has the advantages of small incision, less blood loss, and quicker functional recovery. The early gait after UKA is mainly manifested as the increase in walking speed, stride length, knee flexion at swing, and extension at mid-stance phase. From the analysis of gait symmetry, during the initial contact and loading response phase, the operation side after UKA undertakes more shock absorption and joint stabilization functions than the contralateral side.
ObjectiveTo compare the early effectiveness and safety of simultaneous bilateral and staged bilateral unicompartmental knee arthroplasty (UKA) in treatment of anteromedial compartment osteoarthritis.MethodsThe clinical data of 31 patients with bilateral anteromedial compartment osteoarthritis who underwent bilateral UKAs between January 2015 and January 2017 was retrospectively analyzed. Of them, 17 patients were treated with simultaneous bilateral UKAs (simultaneous group) and 14 patients with staged bilateral UKAs (staged group). There was no significant difference in gender, age, body mass index, osteoarthritis grading, and preoperative hip-knee-ankle angle, knee society score (KSS), visual analogue scale (VAS) score, and range of motion (ROM) of knee between the two groups (P>0.05). The operation time, blood loss, hospitalization stay, minimum hemoglobin value during 10 days after operation, and hospitalization cost were recorded. The staged group was compared by the sum of two operations. The effectiveness was evaluated by KSS score, VAS score, ROM at 3, 6, 12 months after operation, and patient satisfaction scores were recorded at 12 months after operation.ResultsThe operation time, hospitalization stay, and hospitalization cost of the simultaneous group were significantly lower than those of the staged group (P<0.05). There was no significant difference in blood loss and the minimum hemoglobin value during 10 days after operation between the two groups (P>0.05). Superficial infection occurred in 1 side of 1 case (7.1%) in staged group. Postoperative delirium occurred in 1 case (5.9%) in simultaneous group. There was no significant difference in incidence of postoperative complications between the two groups (P=1.000). Patients in both groups were followed up 12-32 months (mean, 24.7 months). There was no significant difference in KSS score between the two groups at 3 months after operation (t=0.896, P=0.392). KSS scores were significanly higher in simultaneous group than in staged group at 6 and 12 months after operation (P<0.05). There was no significant difference in ROM and VAS scores between the two groups at 3, 6, and 12 months after operation (P>0.05). At 12 months after operation, the patient satisfaction scores were significantly higher in simultaneous group than in staged group (P<0.05). X-ray films showed no loosening of the prosthesis in the two groups.ConclusionSimultaneous bilateral UKAs has the same security as staged bilateral UKAs. Meanwhile knee function recovery was better, hospitalization stay and hospitalization cost reduced, and patient satisfaction was higher in simultaneous bilateral UKAs.
ObjectiveTo compare the short-term effectiveness of medial unicompartmental knee arthroplasty (UKA) between patients younger or older than 60 years of age, and to investigate the impact of age on the effectiveness. Methods The clinical data of 182 patients (182 knees) who underwent medial UKA between July 2016 and June 2018 were retrospectively analyzed, of which 72 patients were less than 60 years old (group A) and 110 patients were more than 60 years old (group B). There was a significant difference in age between groups (t=−20.198, P<0.001). No significant difference was found in gender, body mass index, surgical sides, Kellgren-Lawrence grading, disease duration, and preoperative Western Ontario and McMaster University Osteoarthritis Index (WOMAC) score between groups (P>0.05). The postoperative hospital stay and complications were recorded, and the WOMAC score, satisfaction score, and prosthesis revision were compared between groups. Results The length of postoperative hospital stay was (4.50±1.09) days in group A, and (4.46±1.29) days in group B, with no significant difference between groups (t=0.198, P=0.844). All incisions healed by first intention. The incidences of early postoperative complications in groups A and B were 5.6% and 3.6%, respectively, and the difference was not significant (χ2=0.061, P=0.804). All patients were followed up. The follow-up time were 28-50 months (mean, 36 months) in group A and 28-50 months (mean, 35 months) in group B. At last follow-up, the WOMAC scores of both groups significantly improved when compared with those before operation (P<0.05), and there was no significant difference between groups (P>0.05) in the difference before and after operation. The satisfaction scores were 6.6±1.7 in group A and 6.9±1.6 in group B, with no significant difference between groups (t=−1.326, P=0.186). There was no revision surgery in both groups during follow-up period. ConclusionAge has no significant effect on the prognosis of medial UKA, and patients younger than 60 years of age can also obtain good short-term effectiveness.
Objective To conclude the failure factors of unicompartmental knee arthroplasty (UKA), and summarize the research progress of revision surgery. MethodsThe literature on UKA at home and abroad in recent years was reviewed to summarize its risk factors, treatment methods, including the evaluation of bone loss, prosthesis selection, and surgical techniques. ResultsThe factors inducing UKA failure mainly include improper indications, technical errors, and others. The application of digital orthopedic technology can reduce failures caused by surgical technical errors and shorten the learning curve. There are a variety of options for revision surgery after UKA failure, including polyethylene liner replacement, revision with UKA or total knee arthroplasty, with adequate preoperative evaluation prior to implementation. The biggest challenge in revision surgery is the management and reconstruction of bone defects. ConclusionThere is a risk of failure in UKA, which needs to be treated with caution and should be determined according to the type of failure.
ObjectiveTo compare the effectiveness of unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA) in the treatment of severe medial compartment osteoarthritis (OA).MethodsA clinical data of 69 patients (69 knees), who underwent joint replacement due to severe medial compartment OA between February 2015 and September 2018 and met the selection criteria, was retrospectively analyzed. Among them, 38 cases were treated with UKA (UKA group) and 31 cases with TKA (TKA group). There was no significant difference in gender, age, body mass index, course of disease, lesion side, and preoperative visual analogue scale (VAS) score, Hospital for Special Surgery (HSS) score, Western Ontario and McMaster University Osteoarthritis Index (WOMAC) score, Feller score, range of motion of knee, physiological and psychological scores of short-form 12 health survey scale (SF-12) between the two groups (P>0.05). The femorotibial angle (FTA) of TKA group was bigger than that of UKA group, and hip-knee-ankle angle (HKA) was smaller, showing significant differences (P<0.05). The operative time, incision length, blood loss, time for flexion 90°, ambulation time, hospital stay, and incidence of deep venous thrombosis of lower extremity were recorded and compared between the two groups. The VAS score, HSS score, WOMAC score, Feller score, range of motion, and physiological and psychological scores of SF-12 were used to evaluate patients’ quality of life. FTA, HKA, and prosthesis looseness were observed by X-ray films. Kaplan-Merier survival analysis was used to evaluate the survival rate of prosthesis.ResultsAll operations were successfully completed in both groups. Compared with TKA group, UKA group had shorter incision length, longer operative time, and less blood loss (P<0.05). There was no significant difference in time for flexion 90°, ambulation time, hospital stay, and the incidence of deep venous thrombosis of lower extremity between the two groups (P>0.05). The incisions in both groups healed by first intention. During follow-up, 3 patients in the UKA group and 1 patient in the TKA group developed mild anterior knee pain. Patients were followed up (30.7±9.6) months in the UKA group and (34.9±8.7) months in the TKA group, and the difference was not significant (t=–1.832, P=0.071). At last follow-up, there were significant differences in the HSS score, Feller score, WOMAC score, range of motion, VAS score, and physiological and psychological scores of SF-12 between pre- and post-operation (P<0.05). The range of motion in the UKA group was bigger than that in the TKA group (Z=–2.666, P=0.008), and there was no significant difference in the other indexes between the two groups (P>0.05). X-ray films showed that the alignment of the two groups recovered well, and the FTA and HKA of the two groups were improved at 1 week after operation (P<0.05). No radiolucency was found around the prosthesis during follow-up, no prosthesis loosening and meniscal bearing dislocation occurred. The survival rates of the prostheses in the two groups were 100%.ConclusionFor severe medial compartment OA, the early survival rates of the two prostheses are similar, but UKA has less traumatic, can preserve the normal structure of the knee, and the range of motion of the knee after operation is significantly better than TKA.
ObjectivesTo systematically review the efficacy of unicompartmental knee arthroplasty on forgotten joint score (FJS) in patients with knee osteoarthritis.MethodsPubMed, EMbase, The Cochrane Library, Web of Science, CNKI, CBM, WanFang Data and VIP databases were electronically searched to collect randomized controlled trials (RCTs) and cohort studies on unicompartmental knee arthroplasty on FJS in patients with knee osteoarthritis from inception to December 31st, 2019. Two reviewers independently screened literature, extracted data and assessed risk of bias of included studies, then, meta-analysis was performed by using RevMan 5.3 software.ResultsA total of 2 RCTs and 11 cohort studies were included. The results of meta-analysis based on RCTs showed that: compared to posterior stabilized total knee arthroplasty (PS-TKA), unicompartmental knee arthroplasty could improve FJS on 12-month (MD=9.23, 95%CI 0.53 to 17.93, P=0.04) after operation. The results of meta-analysis based on cohort studies showed that: compared to PS-TKA, unicompartmental knee arthroplasty could improve FJS on 6-week (MD=8.90, 95%CI 6.87 to 10.94, P<0.000 01), 6-month (MD=18.72, 95%CI 8.71 to 28.74, P=0.000 2), 1-year after operation (MD=13.41, 95%CI 8.87 to 17.95, P<0.000 01), and the last follow-up (MD=0.99, 95%CI 0.47 to 1.54, P=0.000 2).ConclusionsCurrent evidence shows that, comparing with PS-TKA, unicompartmental knee arthroplasty in knee osteoarthritis shows advantage in the improvement of FJS. Due to limited quality and quantity of the included studies, more high-quality studies are required to verify above conclusions.
Objective To conclude the research progress of unicompartmental knee arthroplasty (UKA) in the treatment of elderly patients with knee osteoarthritis (KOA). Methods The literature on UKA at home and abroad in recent years was reviewed to summarize the clinical characteristics of elderly patients with KOA, perioperative management (including evaluating indications preoperatively, intraoperative prosthesis selection, postoperative complication management, etc). Results Through reasonable preoperative evaluation, prosthesis selection, and advanced perioperative management, for elderly patients with KOA who meet the indications, UKA can be considered. Compared with total knee arthroplasty, the incidence of postoperative complications in elderly patients undergoing UKA is lower, joint awareness is reduced, functional improvement and satisfaction are higher. Meanwhile, choosing appropriate prostheses and fixation methods can lead to a good survival rate. ConclusionUKA can provide a safe and effective treatment option for elderly patients with KOA within a certain range of indications.
ObjectiveTo summarize research progress of change in bone mineral density (BMD) after knee arthroplasty and its diagnostic methods, influencing factors, and drug prevention and treatment.MethodsThe relevant literature at home and abroad was reviewed and summarized from research status of the advantages and disadvantages of BMD assessment methods, the trend of changes in BMD after knee arthroplasty and its influencing factors, and the differences in effectiveness of drugs.ResultsThe central BMD and mean BMD around the prosthesis decrease after knee arthroplasty, which is closely associated with body position, age, weight, daily activities, and the fixation methods, design, and material of prosthesis. Denosumab, bisphosphonates, and teriparatide et al. can decrease BMD loss after knee arthroplasty.ConclusionBMD after knee arthroplasty decreases, which is related to various factors, but the mechanism is unclear. At present, some inhibitors of bone resorption can decrease BMD loss after knee arthroplasty. However, its long-term efficacy remains to be further explored.
ObjectiveTo evaluate the short-term effectiveness of unicompartmental knee arthroplasty (UKA) for medial compartmental osteoarthritis of the knee. MethodsBetween January 2008 and October 2013, 18 patients with medial compartmental osteoarthritis of the knee were treated by UKA, including 11 males and 7 females with an average age of 67.2 years (range, 60-72 years). The disease duration ranged from 3 to 5 years (mean, 3.7 years). All patients had loading pain and walk-associated pain of the medial compartmental knee. The preoperative visual analogue scale (VAS) score was 6.8±1.4. The full-length radiograph of lower limb and anteroposterior and lateral radiographs of the knee showed medial compartmental osteoarthritis of the knee. According to Ahlback staging, 8 knees were at stageⅡand 10 knees at stageⅢ. The knee range of motion (ROM) was (112.3±11.3)°, and the angle of genu varus was (13.2±1.3)°. The American Hospital for Special Surgery (HSS) score was 59.0±6.4. ResultsPrimary healing of incision was obtained in all patients, and no infection or lower limb deep venous thrombosis occurred. All of the patients were followed up 6-50 months (mean, 28 months). No prosthetic loosening and dislocation or lesions of contralateral compartment and patellofemoral joint developed. At 6 months after operation, the VAS score was significantly reduced to 2.8±1.2 (t=9.20, P=0.00); most of patients achieved significant relief of pain. The HSS score was significantly increased to 92.0±3.1 (t=19.69, P=0.00); and the results were excellent in 12 cases, good in 5 cases, and poor in 1 case, with an excellent and good rate of 94.4%. The knee ROM was (115.2±10.2)°, showing no significant difference when compared with preoperative one (t=-0.81, P=0.23). The alignment of limbs showed that the angle of genu varus was significantly reduced to (6.8±2.1)° (t=10.99, P=0.00). ConclusionUKA has satisfactory short-term effectiveness in the treatment of medial compartmental knee osteoarthritis, however, long-term effectiveness need further studies.