Effect of Patellar Thickness on Knee Flexion in Total Knee Arthroplasty: A Biomechanical and Experimental Study

A biomechanical computer-based model was developed to simulate the influence of patellar thickness on passive knee flexion after arthroplasty. Using the computer model of a single-radius, PCL-sacrificing knee prosthesis, a range of patella–implant composite thicknesses was simulated. The biomechanical model was then replicated using two cadaveric knees. A patellar-thickness range of 15 mm was applied to each of the knees. Knee flexion was found to decrease exponentially with increased patellar thickness in both the biomechanical and experimental studies. Importantly, this flexion loss followed an exponential pattern with higher patellar thicknesses in both studies. In order to avoid adverse biomechanical and functional consequences, it is recommended to restore patellar thickness to that of the native knee during total knee arthroplasty.     

髌骨置换与否对全膝关节置换效果的影响

目的评价髌骨置换与否对全膝关节表面置换的影响。方法对2000年1月至2001年6月间行膝关节表面置换的165例病人随机分为髌骨置换组和不置换组。置换组均采用同一种膝关节假体系统，由同组医生完成，术前和随访时评价HSS评分、髌骨评分和髌骨适合角、髌骨高度等影像学结果。所有评价均采用双盲的方式。结果在HSS评分和髌骨评分方面，两组无统计学差异。影像学评价两组无统计学差异。髌骨置换组的手术时间明显长于非置换组。结论对于骨关节炎病人，不置换和置换髌骨临床效果相当，影像学表现无明显区别。但置换组的手术时间更长。不论置换与否，手术时应注意对下肢力线的矫正。     

Patellar Denervation Reduces Postoperative Anterior Knee Pain After Patellar Resurfacing Total Knee Arthroplasty: A Randomized Controlled Trial

BackgroundThe benefit of patellar denervation (PD) in patellar resurfacing total knee arthroplasty (TKA) is still debatable. This prospective, randomized controlled trial investigated whether circumferential PD should be performed in patellar resurfacing TKA.MethodsA total of 241 patients who underwent unilateral TKA were randomized into PD or non-PD groups. Incidence, intensity, and presentation time of anterior knee pain (AKP) and clinical outcomes were evaluated at 3, 6, 9, 12, 18, and 24 months postoperatively.ResultsThe incidence of AKP was significantly lower in the PD group (6.4% vs 16.2%, P = .032). The intensity of AKP and patient satisfaction scores were significantly better in the PD group at 3 months but not after 3 months. The presentation time of AKP mostly occurs at 3 months after surgery. The Knee Society score, range of motion, Oxford score, patellar score, activity of daily living score, and visual analog scale of overall knee pain were not significantly different between the two groups during the follow-up period.ConclusionGiven that PD can improve AKP and patient satisfaction at an early period postoperatively without jeopardizing clinical outcomes at no additional cost, this inexpensive procedure readily available in nearly every operation room is strongly recommended during primary TKA with patellar resurfacing.     

Influence of Total Knee Arthroplasty on Patellar Kinematics and Patellofemoral Pressure

Background

Patellofemoral complications are one of the main problems after total knee arthroplasty (TKA). The design of the TKA component may affect the patellar biomechanics, which may be associated with this postoperative complication. The purpose of this study was to assess the influence of TKA and prosthesis designs on the patellar kinematics and patellofemoral pressure.

Patellar Resurfacing in Total Knee Arthroplasty: A Cost-Effectiveness Analysis

Background

This study estimates the cost-effectiveness of patellar resurfacing in total knee arthroplasty (TKA).

Low Incidence of Postoperative Complications With Navigated Total Knee Arthroplasty

Background

A number of postoperative complications of navigated total knee arthroplasty (TKA) have been discussed in the literature, including tracker pin site infection and fracture. In this article, we discuss the low postoperative complication rate in a series of 3100 navigated TKAs and the overall complication rate in a systematic analysis of the literature.

类风湿性关节炎全膝关节置换术中膝外侧支持带松解的应用

目的:类风湿性关节炎病人髌骨凹陷性缺损、髌骨中央磨损如何处理,是全膝关节置换手术的难点。本文报道该手术技术及早期临床效果,并总结对此类病例手术时髌骨处理的经验。方法:自1997年1月至2002年11月选择49例(49膝)类风湿性关节炎病人,对术中髌骨有中央凹陷性缺损者常规行髌骨假体置换,置换后髌骨厚度大于置换前,所有病例均行髌外侧支持带松解。手术后随访时间最长6年,最短4个月,平均2.7年、结果:病人术前HSS疼痛评分平均为2.4分,功能评分平均为6.22分,膝关节活动评分平均为6.5分。术后48膝疼痛评分平均为30分,1膝于1年后手术探查。49膝功能评分平均为22分,活动评分平均为10分。所有病例均未发生髌骨骨折及髌骨坏死。结论:重症类风湿性关节炎病人在全膝关节置换术中常会出现一些比较特殊的困难,其髌骨常表现为中央凹陷性缺损,行髌骨假体置换后髌骨厚度将会增加。应用股骨假体外旋、外移放置及胫骨假体外旋放置、髌骨假体内置等方法后,仍需通过髌外侧韧带松解来改善髌骨的压力及髌股关节的对合关系。     

Influence of Patellar Morphology Classified by Wiberg Classification on Knee Joint Function and Patellofemoral Tracking After Total Knee Arthroplasty Without Patellar Resurfacing

BackgroundTo evaluate the influence of patellar morphology on knee joint function and patellofemoral tracking in patients with primary osteoarthritis after total knee arthroplasty (TKA) without patellar resurfacing.MethodsWe performed a retrospective study of 156 patients with primary osteoarthritis who underwent TKA without patellar resurfacing from April 2018 to July 2019. As per Wiberg classification, patients were divided into Wiberg type I (group A, n = 38), II (group B, n = 88), and III (group C, n = 30) groups. The clinical data, postoperative follow-up data, and radiological data between three groups were compared.ResultsThere was no statistically significant difference in the HSS score and Feller score between the three groups before surgery and at each follow-up point after surgery (P > .05). At the last follow-up, there were no significant differences in the height and relative thickness of the patella between the three groups (P > .05). However, the incidence of anterior knee pain was significantly higher in group C than in the group B (P < .05). The patellar tilt angle was significantly larger in group C than in the groups A and B (both P < .05). The patellar facet angle was significantly larger in group A than in group B and C, which was also significantly larger in group B than in group C (both P < .05).ConclusionPatients with three different morphologic types of the patella both exhibited improved knee joint function after TKA, however, patients with Wiberg type Ⅲ patella were more prone to have poor patellofemoral tracking and anterior knee pain after surgery.     

Patellar Height After Total Knee Arthroplasty: Comparison of 3 Methods

Background

Total knee arthroplasty (TKA) is the gold standard procedure for knee osteoarthritis. However, there have been conflicting reports concerning whether TKA is associated with modifications in patellar height. This controversy might be partially explained by the diversity of methods used to measure patellar height. Therefore, we aimed at assessing the reproducibility of 3 radiological indices commonly used to evaluate patellar height—Insall-Salvati (IS), Blackburne-Peel (BP), and Caton-Deschamps (CD) ratios. Additionally, we aimed at evaluating the short-term differences between preoperative and postoperative patellar heights as measured by those 3 methods.

Total Patellar Skin Loss From Cryotherapy After Total Knee Arthroplasty

The use of cryotherapy after total knee arthroplasty is a very common therapeutic adjunct accepted as routine postoperative care. We present 2 cases of total patellar skin loss due to cryotherapy after total knee arthroplasty. Substantial soft tissue defects were created after the initial debridement of the necrotic tissue. Both patients were evaluated for frostbite, and the wounds were sharply debrided. Application of an advanced wound management technique involves the use of a collagen-glycosaminoglycan biodegradable bilayer matrix, silver impregnated antimicrobial dressing, and low-pressure vacuum device, followed by delayed split thickness skin grafting and low-pressure vacuum device. We find that this technique provided durable soft tissue coverage for necrotic wounds of the knee that do not involve the joint capsule.     

Onlay Patellar Resurfacing in a Posterior-Stabilized Total Knee Arthroplasty Increases Patellar Crepitus Complication: A Randomized,Controlled Trial

BackgroundPatellar crepitus (PC) is a potentially problematic complication after total knee arthroplasty (TKA) more commonly occurring with a posterior-stabilized (PS) prosthesis. Patellar resurfacing has been reported to reduce PC complications; however, no study has compared the PC complication rates between 2 different resurfacing techniques, namely inlay and onlay.MethodsA prospective, randomized controlled trial was conducted to compare the PC complication between inlay and onlay patellar resurfacing techniques. A total of 222 patients who underwent unilateral TKA using a Legion PS Total Knee System were randomized into 2 groups. PC incidence, time of PC presentation, radiographic parameters associated with PC development, and clinical outcomes were evaluated at 3, 6, 9, 12, 18, and 24 months postoperatively.ResultsPC occurred significantly more in the onlay group (17.9% vs 6.5%, P = .009). Time of PC presentation in both groups was not different. Anterior knee pain was found in 11.5% of PC patients, and none required any surgical procedure. Postoperative radiographic parameters, range of motion, Knee Society score, Oxford score, patellar score, incidence and intensity of anterior knee pain, and visual analog scale of overall knee pain were not significantly different between the 2 groups during the follow-up period.ConclusionTo reduce the chance of PC development, we suggest an inlay patellar resurfacing technique during PS-TKA with this knee system.     

A Meta-Analysis of Patellar Replacement in Total Knee Arthroplasty for Patients With Knee Osteoarthritis

Background

This meta-analysis (MA) aims at comparing the clinical outcomes of resurfacing and nonresurfacing the patella in patients undergoing total knee arthroplasty in the treatment of knee osteoarthritis.

Tibial Tubercle-Trochlear Groove Distance Influences Patellar Tilt After Total Knee Arthroplasty

BackgroundTibial tubercle-trochlear groove (TT-TG) distance is associated with a greater risk of recurrent patellar dislocation in young, active patients. However, the effect of TT-TG distance after total knee arthroplasty (TKA) has not been investigated. The purpose is to analyze the effect of TT-TG distance and component rotation on patellar tilt and patellar shift after TKA.MethodsAfter TKA, axial computed tomography scans and axial radiograph were taken in 115 consecutive knees. TT-TG distance was measured between the most anterior point of the tibial tuberosity and the deepest point of the femoral component relative to a line connecting the anterior condyles. Femoral and tibial component rotation was measured relative to the femoral and tibial rotational axis, respectively. Pearson correlation coefficients were calculated.ResultsTT-TG distance had a significant correlation with patellar tilt in extension (R = 0.220, P = .018), patellar tilt in flexion (R = 0.438, P < .001), and patellar shift (R = 0.330, P < .001). Tibial component rotation had a significant correlation with patellar tilt in flexion (R = −0.251, P = .007) and patellar shift (R = −0.360, P < .001). Femoral component rotation had no significant correlations. Tibial component rotation had a significant correlation with TT-TG distance (R = −0.573, P < .001), whereas femoral component rotation had no correlation (P = .192).ConclusionTT-TG distance had a significant correlation with patellar tilt and patellar shift. Surgeons need to understand the factors affecting TT-TG distance and to pay attention to avoiding excessive TT-TG distance after TKA.     

Patellar Fracture After Total Knee Arthroplasty for Rheumatoid Arthritis

Patellar fracture is one of the most challenging complications of total knee arthroplasty, but relatively, little is known about it in patients with rheumatoid arthritis. We retrospectively analyzed 329 total knee arthroplasties performed in 230 female patients with rheumatoid arthritis to identify the incidence and risk factors for postoperative patellar fractures. The mean age was 61.8 years, and the mean follow-up period was 6.2 years. Patellar resurfacing was performed in all cases. Five postoperative patellar fractures (1.51%) were identified, and a thin residual patellar thickness and the use of posterior-stabilizing components were identified as significant risk factors, although the number of fractures was small in both groups. There was also tendency of higher age and greater joint line change observed in patients with fracture compared with those without fracture.     

MRI Diagnosis of Patellar Clunk Syndrome Following Total Knee Arthroplasty

Background

Patellar Clunk Syndrome is a painful condition associated with a mechanical catching or clunking during active extension following total knee arthroplasty (TKA). The syndrome is caused by growth of interposing soft tissue usually at the superior pole of the patella. This interposed soft tissue cannot be visualized on plain radiographs.

Questions

The aim was to ascertain if magnetic resonance imaging (MRI) would prove helpful in confirming the clinical diagnosis of patellar clunk by visualizing the interposed soft tissues adjacent to the patella and that the recognition of this tissue would be highly reproducible.

Methods

MRI scans of 12 patients with clinical suspicion or related symptoms of a patellar clunk syndrome following primary TKA were retrospectively evaluated. Size of soft tissue masses proximal to the patella were determined in sagittal and axial MRI views. Largest diameters were recorded in two dimensions by two independent observers, and interobserver reliability was determined by intra-class correlation coefficients (ICC).

Results

Nine patients (75%) showed obvious MRI findings consistent with a patellar clunk lesion with high interobserver reliability (ICC values >0.75). In eight patients, this lead to operative treatment with arthroscopic debridement.

Discussion

MRI helps confirm the clinical diagnosis of patellar clunk. The data indicate that MRI is effective in defining the soft tissue lesion that is implicated in clinically evident patellar clunk syndrome after TKA.     

A Missed Opportunity: The Impact of Hepatitis C Treatment Prior to Total Knee Arthroplasty on Postoperative Complications

BackgroundHepatitis C (HCV) is undertreated and increasing in prevalence. Its influence on outcomes following total knee arthroplasty (TKA) remains unclear. The purpose of this study is to examine the impact of HCV and prearthroplasty antiviral treatment on postoperative complications following TKA.MethodsA retrospective matched cohort study was conducted using an administrative claims database to compare postoperative complication rates following TKA for (1) patients with vs without HCV and (2) among patients with HCV, patients with antiviral treatment before TKA vs no treatment. In total, 6971 patients with HCV were matched 1:4 with 27,884 controls without HCV, and 708 HCV patients with antiviral treatment before TKA were matched 1:2 with 1416 HCV patients without treatment. Rates of joint complications at 1 and 2 years postoperatively were compared via multivariable logistic regression.ResultsThe HCV cohort exhibited significantly higher risk of prosthetic joint infection (PJI) than controls at both 1 (4.1 vs 2.1%; odds ratio [OR] 1.58) and 2 years (5.0% vs 2.7%; OR 1.55) postoperatively. Rates of revision TKA were also significantly higher for HCV patients at 1 (2.8% vs 1.8%; OR 1.40) and 2 years (4.1% vs 2.9%; OR 1.30). HCV patients with prearthroplasty antiviral treatment exhibited significantly lower risk of PJI at 1 (2.1% vs 4.1%; OR 0.50) and 2 years (2.7% vs 5.1%, OR 0.51) compared to patients without treatment.ConclusionPatients with HCV have significantly increased risk of PJI and revision arthroplasty following TKA. Antiviral treatment before TKA significantly decreases the risk of PJI postoperatively.Level of EvidenceLevel III.     

Lateral Patellar Facet Impingement After Primary Total Knee Arthroplasty: It Does Exist

The existence of the diagnosis “lateral patellar facet impingement” (LPFI) is controversial and the outcomes for surgical revision for symptomatic LPFI uncertain. We found that of the 3361 index knee revisions performed at our institution from 1995 to 2008, eleven were done for symptomatic LPFI. Their clinical histories and radiographic imaging were reviewed before and after revision TKA and were also compared to a group of control patients. We found no statistically significant differences between the groups in preoperative KS pain and function scores or radiographic features. However, the combined findings of pain in the subpatellar/lateral aspect of the knee post TKA and radiographic lateral facet contact were significantly associated with revision due to LPFI. Surgical revision results were variable, but ~ 2/3 of the patients were satisfied with the operation and had a significant improvement in KS function scores.     

Patellar Resurfacing in Total Knee Arthroplasty: Systematic Review and Meta-Analysis

Background

Patellar resurfacing in total knee arthroplasty remains controversial. The aim of this study is to evaluate this technique through an analysis of comparative studies in the current literature.

Arterial Injury in Total Knee Arthroplasty

Arterial complications associated with knee arthroplasty are relatively rare, although probably underreported, complications of knee arthroplasty that carry a risk of significant morbidity. Thorough preoperative assessment and close liaison with a vascular surgeon, combined with an appreciation of common anatomical variants or distorted anatomy, may help prevent both thromboembolic and direct injuries from occurring. Clinical features of arterial complications following knee arthroplasty may vary significantly from acute hemorrhage or ischemia in the immediate postoperative period to chronic pain and swelling presenting even months following the procedure. There is potential for diagnostic confusion and delay that may adversely affect outcome. Early diagnosis along with vascular surgical review and intervention is key to successful management.     

Association Between Body Mass Index and Thirty-Day Complications After Total Knee Arthroplasty

Background

Although previous studies have evaluated the effect of obesity on the outcomes of total knee arthroplasty (TKA), most considered obesity as a binary variable. It is important to compare different weight categories and consider body mass index (BMI) as a continuous variable to understand the effects of obesity across the entire range of BMI. Therefore, the objective of this study is to analyze the effect of BMI on 30-day readmissions and complications after TKA, considering BMI as both a categorical and a continuous variable.