Influence of offset stem couplers in femoral revision knee arthroplasty: a radiographic study

Hot spots and trends in knee revision research since the 21st century: a bibliometric analysis

Background

With the popularization of knee replacement surgery in the treatment of the advanced lesions of knee joint, the amount of knee revision surgery is increasing unceasingly. Meanwhile, the continuous introduction of new clinical concepts and new technology poses a challenge to researchers and surgeons. Our study aims to inform the future scientific research and clinical treatment, by investigating the hot spots and trends of the knee revision research field with the method of bibliometric analysis.

Methods

Publications on knee revision included in the database of Web of Science Core Collection (WoSCC) between 2000 and 2018 were reviewed and MeSH terms of them were extracted from PubMed. Online bibliometric analysis website (http://bibliometric.com/), two pieces of software called “CiteSpace” and “Bibliographic Item Co-Occurrence Matrix Builder” (BICOMB) were used to analyze the publications reviewed at quantitative level. Another piece of software called “gCLUTO”, was used to investigate the hot spots with visualization techniques at qualitative level.

Results

A total of 906 publications were retrieved between 2000 and 2018. There is an increasing number of publications, from 15 in 2000 to 86 in 2018. Journal of Arthroplasty is the leading journal which has the most publications on knee revision. The United States has been the biggest contributor. Mayo Clinic became the leader among the institutions which have conducted correlational researches. David G. Lewallen, Robert L. Barrack and Michael A. Mont should be regarded as the scholars who have made outstanding contribution. Hot spots were summed up in six clusters, respectively, the solutions for infection, prostheses, the adverse effects, the surgical techniques, epidemiological characters, and the pathophysiology of the revision knee.

Conclusions

We found a growing trend in knee revision research and extracted the most contributive researchers, institutions, countries, journals, and most-cited articles worldwide. The solutions for complications, surgical applications and analysis for epidemiological characters have been the hot spots. Multi-disciplinary integration is becoming the time-trend of hot spots. Minimally invasive and navigation are directions of revision surgery. They together constitute a solid foundation and set up a fingerpost for the future scientific research and clinical treatment.

Rotating Hinge Implants in Knee Arthroplasty

Due to demographic transition an increasing number of primary knee arthroplasty is expected. A consequence is a rise in frequency in revision knee arthroplasty. Rotating hinge prostheses are a development of former hinge prostheses, due to changes in implant design the outcome of modern rotating hinge implants clearly improved in comparison to former models. Interpretation of outcome in present literature is difficult due to the small number of cases and the heterogeneous indications. Nevertheless the use of rotating hinge knee prostheses in primary and revision arthroplasty is associated with good clinical outcomes, when indicated appropriately.

Patellar complications following total knee arthroplasty: a review of the current literature

Total knee arthroplasty is a common operation for treating patients with end-stage knee osteoarthritis and generally has a good outcome. There are several complications that may necessitate revision of the implants. Patella-related complications are difficult to treat, and their consequences impact the longevity of the implanted joint and functional outcomes. In this review, we explore the current literature on patellar complications in total knee arthroplasty and identify risk factors as well as strategies that can help in preventing these complications. We present pertinent findings relating to patellar complications. They can be classified into bony or soft tissue complications and include bone loss, aseptic loosening, periprosthetic fractures, patella fracture, patellar clunk syndrome, patellofemoral instability, extensor mechanism complications, maltracking, patella baja and malrotation. We conclude that patellar complications in total knee arthroplasty are common and have significant implications for the functional outcome of total knee arthroplasty. A high index of suspicion should be maintained in order to avoid them. Implant malpositioning and other forms of intraoperative technical error are the main cause of these complications, and therefore, primary prevention is crucial. When dealing with these established problems, a clear plan of action should be formulated in advance to allow appropriate management as well as anticipation of adverse outcomes.

Tibial shaft anatomy differs between Caucasians and East Asian individuals

PURPOSE

The orientation and distance from the shaft of the femur and tibia to the articular surface centre is important for performing total knee arthroplasty (TKA) with cementless stems. It is important to understand anatomic differences between races to match the tibial and femoral shaft axis to the knee articular surface. Thus, the purpose of this study was to compare knee morphology between Caucasian and East Asian individuals to determine the optimal placement of tibial and femoral stems.

METHODS

A retrospective study was conducted on a matched cohort of 50 East Asians (21F, 29M) and 50 Caucasians (21F, 29M) by age and gender. CT scans were obtained in healthy volunteers using < 2-mm slices. The distance from the proximal tibial diaphysis axis to the tibial plateau centre and the distance from the distal femoral diaphysis axis to the centre of distal femoral articular surface were measured separately. Tibial measurements were taken using Akagi's anteroposterior (AP) axis and the widest mediolateral (ML) diameter, and femoral measurements were based on Whiteside's line and the surgical epicondylar axis.

RESULTS

The ML distance between the tibial shaft centre and Akagi's line was significantly higher for Asians (9.9 ± 2.7 mm, Caucasians 7.7 ± 3.1 mm, p < 0.001). The distance between the femoral shaft centre and Whiteside's line was lower, although not significantly different (Asians 1.9 ± 1.0 mm, Caucasians 2.2 ± 1.1 mm, n.s.). However, there were no differences in the AP dimension for the femur or tibia comparing Asians to Caucasians in both tibial side (Asians 10.6 ± 3.3 mm vs. Caucasians 10.9 ± 4.0 mm) and femoral side (Asians 18.1 ± 1.7 mm vs. Caucasians 17.5 ± 1.6 mm).

CONCLUSION

East Asian individuals have more offset in the ML dimension for the tibia. This finding is clinical relevant, as this dimensional difference should be taken into consideration when designing primary and revision TKA stemmed tibial implants for East Asian individuals.

LEVEL OF EVIDENCE

Case-control study, Level III.

Posterior condylar offset is an independent predictor of functional outcome after revision total knee arthroplasty

Objectives

Preservation of posterior condylar offset (PCO) has been shown to correlate with improved functional results after primary total knee arthroplasty (TKA). Whether this is also the case for revision TKA, remains unknown. The aim of this study was to assess the independent effect of PCO on early functional outcome after revision TKA.

Methods

A total of 107 consecutive aseptic revision TKAs were performed by a single surgeon during an eight-year period. The mean age was 69.4 years (39 to 85) and there were 59 female patients and 48 male patients. The Oxford Knee Score (OKS) and Short-form (SF)-12 score were assessed pre-operatively and one year post-operatively. Patient satisfaction was also assessed at one year. Joint line and PCO were assessed radiographically at one year.

Results

There was a significant improvement in the OKS (10.6 points, 95% confidence interval (CI) 8.8 to 12.3) and the SF-12 physical component score (5.9, 95% CI 4.1 to 7.8). PCO directly correlated with change in OKS (p < 0.001). Linear regression analysis confirmed the independent effect of PCO on the OKS (p < 0.001) and the SF-12 physical score (p = 0.02). The overall rate of satisfaction was 85% and on logistic regression analysis improvement in the OKS (p = 0.002) was a significant predictor of patient satisfaction, which is related to PCO; although this was not independently associated with satisfaction.

Conclusion

Preservation of PCO should be a major consideration when undertaking revision TKA. The option of increasing PCO to balance the flexion gap while maintaining the joint line should be assessed intra-operatively.

Cite this article: N. D. Clement, D. J. MacDonald, D. F. Hamilton, R. Burnett. Posterior condylar offset is an independent predictor of functional outcome after revision total knee arthroplasty. Bone Joint Res 2017;6:172–178. DOI: 10.1302/2046-3758.63.BJR-2015-0021.R1.

The role of offset stems in revision knee arthroplasty

Revision total knee arthroplasty (TKA) represents a technically challenging procedure. The use of an offset stem extension can help in addressing some of the difficulties that can be encountered during surgery and, in particular, anatomical mismatch, malalignment, and gap balancing. Different offset stem extensions are available and can be classified according to four parameters: modularity, location of the offset, direction, and size of the displacement. Offset stem extensions can assist with implant alignment on the metaphysis if there is an offset diaphysis, can avoid medial-lateral or anterior-posterior component overhang, can reduce the incidence of coronal or sagittal malalignment, and can help in balancing the flexion and extension spaces by effectively translating the components. The aim of this study is to give an overview of the currently available evidence regarding the use of offset stem extensions in revision TKA as well as some useful surgical tips.

A technique of predicting radiographic joint line and posterior femoral condylar offset of the knee

Purpose. To describe a reliable method of predicting native joint line and posterior condylar offset (PCO) using true lateral digital radiographs of the distal femur. Methods. PCO was measured relative to a line drawn parallel to the posterior cortex of the distal femur and the joint line was measured from the posterior condylar flare to the articular surface. A ratio was then calculated for these measurements relative to the width of the femur at the level of the flare. Two independent observers measured PCO and joint line ratio for 105 radiographs of the different knees and one repeated these measurements after one week. Results. There was a significant correlation between the width of the femoral diaphysis at the level of the posterior condylar flare with joint line (P = 0.008) and PCO (P = 0.003). Joint line and PCO could be predicted within 4 mm and 2 mm, respectively, using the identified ratio between the width of the femoral diaphysis at the level of the posterior condylar flare with measured joint line and PCO. The inter- (P < 0.001) and intra- (P < 0.001) observer reliability for these ratios were high. Conclusion. These ratios could be used to predict the native joint line and PCO.

Joint line position in revision total knee arthroplasty: the role of posterior femoral off-set stems

BACKGROUND

Elevation of the joint line frequently occurs in revision total knee arthroplasty (RTKA) because of a wider flexion space than extension space. One solution to balance this flexion-extension space involves the introduction of couplers between the stem and femoral components, and the use of posteriorly offset femoral stems that we hypothesized would improve gap balancing and facilitate joint line restoration.

METHODS

We retrospectively reviewed a selected series of 43 RTKA. Postoperative joint line height was subtracted from intended height using postoperative lateral radiographs. The value was negative if the joint line position was lowered, and positive if raised.

RESULTS

Forty knees were followed for a mean of 3.5years. Mean postoperative joint line position change from intended position was 1.5mm (range -2.5-7.5mm). In 28 knees (70%), the joint line position was restored to within ±2mm of the intended position; in eight knees (20%), from 2-4mm; and in four knees (10%), >4mm. Joint line position was raised in 32 knees (80%) and lowered in eight (20%). In the offset stem knees, the intended joint line position was 0.9mm (range -1.2-3.4mm) as compared with 3.2mm (range -2.5-7.5mm) for the straight stem knees.

CONCLUSIONS

A coupler system between the femoral stem and femoral component restored the joint line in 70% of cases. The posterior offset stem provided increased posterior condylar offset, addressed the wider flexion space, provided better positioning of the stem, and restored the joint line.

LEVEL OF EVIDENCE

Therapeutic Study Level IV.

The influence of stem length and fixation on initial femoral component stability in revision total knee replacement

Objectives

Orthopaedic surgeons use stems in revision knee surgery to obtain stability when metaphyseal bone is missing. No consensus exists regarding stem size or method of fixation. This in vitro study investigated the influence of stem length and method of fixation on the pattern and level of relative motion at the bone–implant interface at a range of functional flexion angles.

Methods

A custom test rig using differential variable reluctance transducers (DVRTs) was developed to record all translational and rotational motions at the bone–implant interface. Composite femurs were used. These were secured to permit variation in flexion angle from 0° to 90°. Cyclic loads were applied through a tibial component based on three peaks corresponding to 0°, 10° and 20° flexion from a normal walking cycle. Three different femoral components were investigated in this study for cementless and cemented interface conditions.

Results

Relative motions were found to increase with flexion angle. Stemmed implants reduced relative motions in comparison to stemless implants for uncemented constructs. Relative motions for cemented implants were reduced to one-third of their equivalent uncemented constructs.

Conclusions

Stems are not necessary for cemented implants when the metaphyseal bone is intact. Short cemented femoral stems confer as much stability as long uncemented stems.