Radiological Stability after Revision of Infected Total Knee Arthroplasty Using Modular Metal Augments

Mid-term results of complex primary total knee arthroplasty using a rotating-hinge implant

BACKGROUND

The indications and outcomes of semi- or fully-constrained knee implants in primary total knee arthroplasty (TKA) are still controversially discussed. The present study aims to evaluate the mid-term results and complications of a modular/non-modular rotating-hinge implant in complex primary TKA.

METHODS

Eighty-two patients (86 knees) following primary TKA were retrospectively evaluated with a mean follow-up of 63 months. The functional outcome was assessed using the American Knee Society Score (AKSS) and the Oxford Knee Score (OKS). A Visual Analog Scale (VAS) was used to determine pain levels. Implant survival and reoperation rateswere estimated using competing risk analysis. Cox regression analysis wasperformed to evaluate the influence of modularity on implant survival.

RESULTS

The survival rate with the endpoint implant revision was 90% (95 %CI:83-98%) and the survival rate with the endpoint all reoperations was 84% (95 %CI:75-94%) at 7 years. The AKSS improved significantly from 24 (SD 14.9, range:0-69) preoperatively to 83 (SD 14.3, range:57-100) postoperatively (p < 0.001); functional AKSS improved significantly from 27 (SD 24.3, range:0-100) to 46 (SD: 32.9, range 0-100) (p = 0.003), and OKS from 19 (SD: 8.3, range:5-43) to 29 (SD: 10.7, range:6-48), respectively (p < 0.0001). VAS decreased significantly from 8 (SD: 2.6, range:0-10) preoperatively to 3 (SD: 2.9, range:0-9) postoperatively (p < 0.0001). There was no significant influence of modularity on revision rates comparing modular to non-modular implants (p = 0.072).

CONCLUSIONS

The present rotating-hinge implant provides substantial improvement in function and reduction of pain with good implant survival in the mid-term. Modularity was not associated with higher rates of revision.

Bilateral Primary Total Knee Arthroplasty and Reconstruction of the Medial Tibial Plateau by an Asymmetric Cone in a Patient with Charcot Arthropathy

Charcot arthropathy of the knee is an extremely rare orthopedic disease that is very challenging for the treating physician and is associated with many complications, especially if it is occurring on both knees. Meanwhile, in the advanced stage, despite many potential complications, TKA is recognized as the gold standard. However, destruction of the medial tibial plateau is typical for the disease, which makes a stable anchorage of the prosthesis much more difficult. Therefore, we present a case in which sufficient primary stability could be achieved with an asymmetrical second-generation tibial cone with an anatomical design and implantation instruments adapted to the bony anatomy in the presence of severe tibial destruction on both sides. In the two-year follow-up, the patient showed good mobility and stability on both sides. In advanced Charcot arthropathy of the knee, the use of asymmetric tibial cones appears to be an appropriate solution for secure fixation and stability of the implant.

Bone Defects in Revision Total Knee Arthroplasty and Management

This article reviews the recent updates in revision of total knee arthroplasty (RTKA). We reviewed the recent articles on RTKA in databases including PubMed, Google Scholar, and SCOPUS. Total knee arthroplasty (TKA) involves the replacement of all three compartments of the knee in surgery of the knee joint to restore capacity and function. TKA is one of the most common and reliable surgical treatment options for the treatment of knee diseases. However, some patients require revision of TKA (RTKA) after primary TKA for various reasons, including mechanical wear, implant loosening or breakage, malalignment, infection, instability, periprosthetic fracture, and persistent stiffness. Unfortunately, the overall outcome of RTKA is not as satisfactory as for primary TKA due to the uncertainty regarding the actual success rate and the risk factors for failure. Cementation, modular metal augmentation, bone grafting, autologous bone grafting, allogenic bone grafting, impactation bone grafting, structural bone allografting, metaphyseal fixation, using porous titanium coated press fit metaphyseal sleeves and porous tantalum structural cones, and megaprostheses or customized prostheses are the currently available management options for RTKA. However, most of the management systems possess specific complications. Novel approaches should be developed to improve functional capacity, implant survival rates, and quality of life in a cost‐efficient manner.

Factors affecting the choice of constrained prostheses when performing revision total knee arthroplasty

PURPOSE

The purposes of the present study were to assess the levels of prosthetic constraint chosen during revision total knee arthroplasty (TKA) and to identify factors influencing the choice of a constrained prosthesis.

METHODS

We retrospectively reviewed data on 274 revision TKAs. The mean follow-up period after revision TKA was 7.2 years. The femorotibial angle (FTA), joint line height (JLH), and Insall-Salvati ratio (ISR) were radiographically evaluated. Factors affecting the extent of constraint chosen were evaluated in terms of age, gender, body mass index, primary diagnosis, the cause of revision TKA, the Anderson Orthopedic Research Institute (AORI) classification, and changes in the JLH and ISR.

RESULTS

Totals of 247 (90.1%), 11 (4.0%), and 9 (3.4%) knees received posteriorly stabilized prostheses, constrained condylar knees, and rotating hinge prostheses, respectively. On multivariate analysis, the cause of revision TKA including loosening and instability and the changes in the JLH and ISR affected independently the choice of a constrained prosthesis.

CONCLUSIONS

The frequency of implantation of constrained prostheses was 7.4% in the present study. Consideration of various factors including the cause of revision TKA and changes in the JLH and ISR will aid the TKA surgeon in selecting prostheses with appropriate constraints when performing revision TKAs.

Comparison of mode of failure between primary and revision total knee arthroplasties

INTRODUCTION

Cognizance of common reasons for failure in primary and revision TKA, together with their time course, facilitates prevention. However, there have been few reports specifically comparing modes of failure for primary vs. revision TKA using a single prosthesis. The goal of the study was to compare the survival rates, modes of failure, and time periods associated with each mode of failure, of primary vs. revision TKA.

HYPOTHESIS

The survival rates, modes of failure, time period for each mode of failure, and risk factors would differ between primary and revision TKA.

MATERIAL AND METHODS

Data from a consecutive cohort comprising 1606 knees (1174 patients) of primary TKA patients, and 258 knees (224 patients) of revision TKA patients, in all of whom surgery involved a P.F.C^® prosthesis (Depuy, Johnson & Johnson, Warsaw, IN), was retrospectively reviewed. The mean follow-up periods of primary and revision TKAs were 9.2 and 9.8 years, respectively.

RESULTS

The average 10- and 15-year survival rates for primary TKA were 96.7% (CI 95%,±0.7%) and 85.4% (CI 95%,±2.0%), and for revision TKA 91.4% (CI 95%,±2.5%) and 80.5% (CI 95%,±4.5%). Common modes of failure included polyethylene wear, loosening, and infection. The most common mode of failure was polyethylene wear in primary TKA, and infection in revision TKA. The mean periods (i.e., latencies) of polyethylene wear and loosening did not differ between primary and revision TKAs, but the mean period of infection was significantly longer for revision TKA (1.2 vs. 4.8 years, P=0.003).

DISCUSSION

Survival rates decreased with time, particularly more than 10 years post-surgery, for both primary and revision TKAs. Continuous efforts are required to prevent and detect the various modes of failure during long-term follow-up. Greater attention is necessary to detect late infection-induced failure following revision TKA.

LEVEL OF EVIDENCE

Case-control study, Level III.

Use of autogenous onlay bone graft for uncontained tibial bone defects in primary total knee arthroplasty

Background

The use of autogenous bone graft is a well–known technique for reconstruction of tibial bone defects in primary total knee arthroplasty (TKA). In cases where the size of the bone graft is inappropriate, the stability of bone graft fixation and subsequent bone graft to host bone incorporation may be compromised. We describe a simple and reliable technique of reconstruction in a proximal tibia bone defect at the time of primary TKA by using autogenous onlay bone graft (AOBG).

Methods

Records were reviewed of 19 patients (mean age, 72 years) who underwent primary TKA using AOBG without the additional allogenous bone or metal augments, between August 2013 and August 2014.

Results

Mean Knee Society score (KSS) in the 22 knees was significantly higher postoperatively than preoperatively (92 ± 4 vs. 30 ± 7, P < 0.001). The mean range of motion (ROM) in the 22 knees, which was 106 ± 12° preoperatively, improved to 112 ± 10° at last follow-up, but this this difference was not significant (P = 0.32). No migration of implants and presence of radiolucent lines at the bone cement-prosthesis interface were observed. Furthermore, the serial radiographs of 19 patients had a mean time of 3.2 months (range, 2.7–4.4 months) for solid union with cross trabeculation between the proximal tibial bone and graft.

Conclusions

This simple AOBG supplement technique may biologically promote graft to host bone healing by enhancing fixation stability without the additional fixatives and assist the surgeon in managing the varying nature of uncontained bone defects.

Trial registration

Trial registration number: KCT0002328, May 15, 2017.