Clinical Outcomes Following the Use of Constrained Condylar Knees in Primary Total Knee Arthroplasty

Background

Certain clinical or adverse intraoperative situations require the use of increased constraint in primary total knee arthroplasty (TKA). These include significant angular deformities causing incompetent collateral ligaments, or inadvertent intraoperative injury to collateral structures as well as the inability to achieve a balanced flexion and extension gap. Clinical success has been described with the use of constrained condylar knee arthroplasty in the primary setting in these situations. Traditionally, increasing constraint has been in conjunction with intramedullary stems, referred to as stemmed constrained condylar knees (SCCK); however, some devices provide an intermediary option by increasing constraint without the use of stems, herein referred to as nonstemmed constrained condylar knees (NSCCK). The aim of this study was to compare the clinical outcomes of both these devices in primary TKA in terms of revision rates and change in outcome measures over the follow-up period.

Revision Total Knee Arthroplasty Using a Constrained Condylar Knee Prosthesis in Conjunction with A Posterior Stabilized Articular Polyethylene

Legacy constrained condylar knee (LCCK) components are designed in the way that they can also be used in conjunction with a posterior-stabilized (PS) polyethylene insert, when adequate collateral stability is present. This study comprised 27 revision total knee arthroplasties (TKA) treated using an LCCK prosthesis and a PS polyethylene insert. Substantial range of motion and Knee Society score improvements were achieved in all subjects. Radiolucent lines between the block-cement were noted in 6 of 27 knees, but not significant. During TKA requiring the use of a femoral augment or stem extension, the design offering least constraint can be chosen, and an LCCK prosthesis with a PS polyethylene insert could be a satisfactory option.     

Results of a second-generation constrained condylar prosthesis in primary total knee arthroplasty

This is a prospective study of the results of a second-generation modular constrained condylar knee (CCK) prosthesis in primary total knee arthroplasty. Of 418 consecutive total knee arthroplasties performed by 1 surgeon, a second-generation modular CCK prosthesis was indicated for intraoperative stability in 30 knees (7.2%). Three knees were lost to follow-up, and 27 knees had a mean follow-up time of 5.4 years (range, 2-11.5 years). All tibial components had a cemented 35-mm stem extension, and 26 femoral components had a 100-mm uncemented stem extension. The indication for use of the CCK components was most commonly severe valgus deformity and incompetent medial collateral ligament. There were no revisions for loosening, patella problems, or tibial post fracture. A lateral retinacular release of the patella was performed in 6 knees (22%). An asymptomatic, minimally displaced patella fracture was noted in 2 knees (7.4%). Constrained condylar knees are used infrequently now but are successful for the treatment of the unstable primary knee that cannot be balanced. These results may be design specific.     

Survival of Primary Condylar-Constrained Total Knee Arthroplasty at a Minimum of 7 Years

The purpose of the present study is to retrospectively analyze clinical and radiographic outcomes in primary constrained condylar knee arthroplasty at a minimum follow-up of 7 years. Given the concern for early aseptic loosening in constrained implants, we focused on this outcome. Our cohort consists of 127 constrained condylar knees. The mean age of patients in the study was 68.3 years, with a mean follow-up of 110.7 months. The diagnosis was primary osteoarthritis in 92%. There were four periprosthetic distal femur fractures, with a rate of revision of 0.8%. No implants were revised for aseptic loosening. Kaplan–Meier survivorship analysis with removal of any component as the end point revealed that the 10-year rate of survival of the primary CCK was 97.6% (95% CI, 94%–100%).     

Five Cases of Failure of the Tibial Polyethylene Insert Locking Mechanism in One Design of Constrained Knee Arthroplasty

We describe 5 cases of failure of the locking mechanism of the polyethylene insert and tibial base-plate in one design of constrained condylar knee prosthesis due to disengagement of the locking screw. Loosening of the screw is believed to occur because of a counterclockwise torque created by the axial rotation of the femur on the tibia that occurs as the knee extends during gait. This torque is transmitted via the highly rotationally constrained femoral housing and tibial post to the locking screw. These failures suggest that an alternative locking mechanism should be considered for this prosthesis.     

Varus-Valgus Constrained Implants With a Mobile-Bearing Articulation: Results of 367 Revision Total Knee Arthroplasties

BackgroundVarus-valgus constrained (VVC) implants are used for compromised ligamentous stability in revision total knee arthroplasties (TKAs). Mobile-bearing VVC implants may reduce rotational forces; yet, limited clinical data exist. The purpose of this study is to report mid-term risk of re-revision, complications, and clinical outcomes with a mobile-bearing VVC implant.MethodsThree hundred thirty-seven patients (367 TKAs) who underwent revision TKA with a mobile-bearing VVC implant between 1999 and 2013 at a single institution were reviewed. Mean age at revision was 67 years. Mean follow-up was 4 years. The main indications for revision were aseptic loosening in 158 cases (43%), reimplantation after 2-stage exchange arthroplasty in 120 (33%), instability in 61 (17%), and other in 28 (7%). Clinical outcomes were assessed by Knee Society Scores, and survivorship was analyzed with death as the competing risk.ResultsThe 5-year cumulative incidences of any re-revision or re-revision for aseptic loosening were 9% and 3%, respectively. Twenty-six knees (7%) were re-revised: 15 for infection, 6 for aseptic loosening, and 5 for other causes. There were 17 cases of irrigation and debridement, 10 cases of manipulations under anesthesia, and 9 cases of periprosthetic fractures. There were no bearing “spin-outs.” The mean Knee Society Scores improved from 45 preoperatively to 77 at most recent follow-up (P < .001).ConclusionThe functional improvement and 5-year cumulative incidence of revision of a mobile-bearing VVC implant demonstrated acceptable outcomes with no unique complications related to the mobile-bearing construct. Additional follow-up will be needed to determine long-term implant survivorship.     

Superior Survivorship for Posterior Stabilized Versus Constrained Condylar Articulations After Revision Total Knee Arthroplasty: A Retrospective,Comparative Analysis at Short-Term Follow-Up

BackgroundThe decision to use a posterior stabilized (PS) or constrained condylar knee (CCK) articulation in revision total knee arthroplasty (RTKA) has traditionally been based on surgeon preference and knee stability. The purpose of this study is to compare various outcomes and survivorship in RTKA with PS or CCK articulations.MethodsA retrospective comparative study of RTKA with CCK or PS articulations (PS = 106/CCK = 147) was performed with minimum 2-year follow-up. Exclusion criteria were patients with rotating hinged implants or non-CCK/PS constructs. Multivariate logistic regression models were constructed to determine whether implant articulation influenced (1) complications, (2) aseptic loosening, and (3) re-revision. Kaplan-Meier estimates of cumulative implant survival were constructed with revision as the failure variable.ResultsPS articulation was an independent predictor of increased postoperative knee flexion (6.4°, P = .010) and the knee society functional score (10.0, P = .002). Survivorship was significantly reduced for CCK revision articulations when all-cause re-revision was the primary endpoint (P = .0003, log-rank test of equality). The primary reason for re-revision in the CCK cohort was a recurrent/persistent infection of the operative knee (N = 16, 37.2%), followed by aseptic loosening (N = 13, 30.2%). PS articulations conferred a lower likelihood of re-revision (odds ratio [OR] 0.3, P = .001), but articulation design was not associated with complications (OR 0.5, P = .123) or aseptic loosening (OR 2.6, P = .143).ConclusionThe PS articulation when used for appropriate indication conferred superior survivorship for the primary endpoint of all-cause re-revision and overall knee function when compared to the CCK articulation after RTKA. Implant articulation was not a predictor of aseptic loosening or complications.     

The Association Between Cement Viscosity and Revision Risk After Primary Total Knee Arthroplasty

BackgroundRecent case series have reported early failure with the use of high-viscosity cement (HVC) in total knee arthroplasty (TKA). We evaluated revision risk after TKA with HVC compared with medium-viscosity cement (MVC) in a large cohort.MethodsWe conducted a cohort study using data from Kaiser Permanente’s Total Joint Replacement Registry. Patients who underwent fully cemented primary TKA for osteoarthritis were identified (2001-2018). Only posterior-stabilized, fixed-mobility designs of the 3 highest-volume implant systems (DePuy PFC, Zimmer NexGen, and Zimmer Persona) were included to mitigate confounding from implant characteristics. Palacos (Zimmer/Heraeus) and Simplex (Stryker) cements comprised the HVC and MVC exposure groups, respectively. Propensity score–weighted Cox proportional hazards regression was used to evaluate risk for any revision during follow-up and risk for revision from aseptic loosening specifically.ResultsThe final cohort comprised 76,052 TKAs, 41.1% using MVC. The crude 14-year cumulative revision probability was 4.55% and 5.12% for TKA with MVC and HVC, respectively. In propensity score–weighted Cox models, MVC compared with HVC had a lower risk of any revision (hazard ratio = 0.82, 95% confidence interval = 0.70-0.95) while no difference was observed for revision from aseptic loosening (hazard ratio = 0.80, 95% confidence interval = 0.56-1.13).ConclusionWhile we observed a lower risk for any revision with the use of Simplex MVC compared with Palacos HVC, we did not observe a difference in revision for aseptic loosening specifically. Given the widespread use of HVC, additional research to investigate other HVC and potential mechanisms for failure outside of loosening is warranted.Level of EvidenceLevel III.     

Contemporary Total Hip and Total Knee Arthroplasty Results in Patients with Hemochromatosis

BackgroundHemochromatosis can result in metabolic bone pathology (due to excessive iron absorption) and degenerative joint disease, leading to total joint arthroplasties. The aim of this study is to analyze the survivorship, complications, radiographic results, and clinical outcomes of patients with hemochromatosis who received either a total hip arthroplasty (THA) or a total knee arthroplasty (TKA).MethodsWe identified 34 lower extremity arthroplasties in 29 patients with hemochromatosis performed between 2000 and 2016. There were 17 primary THAs in 15 patients and 17 primary TKAs in 14 patients. Mean age at arthroplasty was 63 years with 76% being male. The mean body mass index was 28 kg/m². Mean follow-up was 5 years.ResultsThe survivorship free from any revision for THAs was 94% at 10 years. One patient was revised for aseptic loosening of the femoral stem at 6 months. In THA patients, no infections, no other complications, and no radiographic evidence of aseptic loosening were identified. Harris Hip Scores improved from a mean of 55 preoperatively to 94 postoperatively (P < .001). The survivorship free from any revision for TKAs was 100% at 10 years. Two patients (12%) developed acquired idiopathic stiffness postoperatively; no infections were identified. There was no radiographic evidence of aseptic loosening in any TKA. Knee Society Scores improved from a mean of 61 preoperatively to 94 postoperatively (P < .001).ConclusionThis study found excellent survivorship, significant improvements in clinical outcomes, and a very low complication profile for both THA and TKA in patients with hemochromatosis.     

高屈曲度假体与全髁型假体早期临床疗效比较

目的 对比高屈曲度假体与传统全髁型假体全膝关节表面置换术后早期临床效果的差异。方法 选取2004年10月至2005年10月间50例（67个膝关节）接受全膝关节表面置换术的膝骨关节炎患者，随机分为A组（高屈曲度假体组，使用LPS—Flex假体）和B组（全髁型假体组／TTC组，使用PFC∑及GⅡ假体）。A组包括26例患者（32个膝关节），男5例，女21例，平均年龄（65．29±5．96）岁。B组包括24例患者（35个膝关节）。男4例，女20例，平均年龄（64．32±8．32）岁。平均随访时间为1年8个月（1～2年）。结果 术前HSS评分为A组（58．61±11．40）分，B组（55．73±13．42）分，两组间无显著差异；术前膝关节活动度为A组（92±12．6）。（-15°～110°），B组（95±11．8）。（-15°～115°），两组间无显著差异。术后末次随访时HSS评分为A组（91．42±6．1）分，B组（92．67±6．33）分，两组间无显著差异；膝关节活动度为A组（124．68±10．32）。（-5°～137°），B组（102．56±15．44）。（-5°～118°），两组间有显著差异，A组患者膝关节屈曲功能明显优于B组。术后并发症包括：A组1例双膝全膝关节置换患者术后3个月时右膝关节感染，1例患者术后深静脉血栓形成；B组1例单膝全膝关节置换患者术后2周伤口脂肪液化，2例患者术后发生深静脉血栓。结论 全膝关节置换术中使用高屈曲度假体与使用传统全髁型假体相比，在改善患者疼痛、恢复行走功能以及手术并发症率方面无显著差别，但术后所能达到的屈曲度有显著差异。     

Midterm Clinical and Radiographic Results of Mobile-Bearing Revision Total Knee Arthroplasty

Background

Constrained implants are frequently required in revision total knee arthroplasty (TKA) and are associated with an increase in aseptic component loosening and damage or wear to the constraining mechanisms, compared with primary TKA. The purpose of the following study was to evaluate the midterm clinical and radiographic results including the incidence of bearing complications in a group of patients undergoing revision TKA using mobile-bearing revision TKA implants.

No Difference in Revision Rate Between Low Viscosity and High Viscosity Cement Used in Primary Total Knee Arthroplasty

BackgroundLoosening remains one of the most common reasons for revision total knee arthroplasty (TKA). Cement viscosity has a potential role in reducing revision rates for loosening. The aim of this study was to assess the outcome for loosening of the 5 most used cemented knee prostheses by constraint type, based on the cement viscosity type used.MethodsThere were 214,708 TKA procedures performed between 1999 and 2020 for a diagnosis of osteoarthritis using the 5 most commonly used minimally stabilized, posterior stabilized, and medial pivot design cemented tibial components. Only procedures with a cemented tibial component were included. Outcomes for two different cement viscosities, 140,060 high viscosity and 74,648 low viscosity cement, were compared for each fixation type within each of the three stability groups.ResultsThere was no difference in a risk of all-cause revision when high viscosity cement was used compared to low viscosity cement for minimally stabilized prostheses (hazards ratio [HR] 1.07 [95% CI 0.99-1.15], P = .09), posterior stabilized prostheses (HR 1.03 [95% CI 0.95-1.11], P = .53), and medial pivot design prostheses (HR 1.06 [95% CI 0.80-1.41], P = .67). No difference was observed between cement viscosity types for any of the prosthesis constraint types when aseptic loosening was assessed.ConclusionsWe found no difference in the risk of revision for any reason, or for loosening, with cement viscosity for the most commonly used minimally stabilized, posterior stabilized, and medial pivot TKA. The role of cement viscosity in the risk of TKA revision remains unclear and further research is required.Level of EvidenceLevel III Retrospective comparative study.     

Failure After Modern Total Knee Arthroplasty: A Prospective Study of 18,065 Knees

Background

We sought is to determine the mechanism of failure among primary total knee arthroplasties (TKAs) performed at a single high-volume institution by asking the following research questions: (1) What are the most common failure modes for modern TKA designs? and (2) What are the preoperative risk factors for failure following primary TKA?

Trends in the Use of High-Viscosity Cement in Patients Undergoing Primary Total Knee Arthroplasty in the United States

Background

Aseptic loosening remains the most common mode of failure following total knee arthroplasty (TKA). Although the risk of loosening is multifactorial, recent studies reported early failure via debonding at the tibial implant-cement interface and a potential association with high viscosity cement (HVC). The purpose of this study is to determine the type of cement used by surgeons performing elective, primary TKA in the United States.

Low-Dose Irradiation and Constrained Revision for Severe,Idiopathic, Arthrofibrosis Following Total Knee Arthroplasty

Treatment options for arthrofibrosis following total knee arthroplasty include manipulation under anesthesia, open or arthroscopic arthrolysis, and revision surgery to correct identifiable problems. We propose preoperative low-dose irradiation and Constrained Condylar or Rotating-hinge revision for severe, idiopathic arthrofibrosis. Irradiation may decrease fibro-osseous proliferation while constrained implants allow femoral shortening and release of contracted collateral ligaments. Fourteen patients underwent fifteen procedures for a mean overall motion of 46° and flexion contracture of 30°. One patient had worsening range of motion while thirteen patients had 57° mean gain in range of motion (range 5°–90°). Flexion contractures decreased by a mean of 28°. There were no significant complications at a mean follow up of 34 months (range 24 to 74 months).     

Modular Tibial Stem Use and Risk of Revision for Aseptic Loosening in Cemented Primary Total Knee Arthroplasty

BackgroundModular tibial stem extensions in total knee arthroplasty (TKA) are designed to reduce the risk of aseptic loosening of the tibial base plate. However, these implants add significant cost and an evaluation of their effectiveness in reducing this risk of loosening has not been studied in a large cohort. We sought to evaluate modular tibial stem utilization in primary TKA.MethodsWe conducted a cohort study using our integrated healthcare system’s Total Joint Replacement Registry. Patients who underwent cemented primary TKA were identified (2009-2019). Propensity scores were used to 1:1 match patients without to those with a stem extension. Cox proportional-hazards regression was used to evaluate the risk for revision due to aseptic loosening.ResultsTen thousand four hundred seventy six TKA with a modular tibial stem were matched to 10,476 TKA without a tibial stem. Stem utilization associated with a lower risk of revision for loosening across all postoperative follow-up (hazard ratio = 0.38, 95% confidence interval = 0.17-0.85).ConclusionIn a matched cohort study, we observed presence of a stem extension was associated with a lower risk of revision for aseptic loosening. Further study to identify specific risk factors for aseptic loosening and confirm the findings presented here are warranted.Level of EvidenceLevel III.     

Failure Mechanisms and Closed Reduction of a Constrained Tripolar Acetabular Liner

Unlike traditional bipolar constrained liners, the Osteonics Omnifit constrained acetabular insert is a tripolar device, consisting of an inner bipolar bearing articulating within an outer, true liner. Every reported failure of the Omnifit tripolar implant has been by failure at the shell-bone interface (Type I failure), failure at the shell-liner interface (Type II failure), or failure of the locking mechanism resulting in dislocation of the bipolar-liner interface (Type III failure). In this report we present two cases of failure of the Omnifit tripolar at the bipolar-femoral head interface. To our knowledge, these are the first reported cases of failure at the bipolar-femoral head interface (Type IV failure). In addition, we described the first successful closed reduction of a Type IV failure.