Einfluss der Retropatellararthrose auf das funktionelle Ergebnis nach unikondylären Schlittenprothesen

UKA can be safely revised to primary knee arthroplasty by using an autologous bone plate from the proximal lateral tibia

The bone-preservation by UKA in medial osteoarthritis constitutes only an advantage if in the case of revision an unconstrained TKA can be implanted. The aim of this study was to evaluate a revision technique using an autologous bone slice from the lateral to the medial proximal tibia. We report on 17 patients with a mean follow up of 3.1years. Patient's satisfaction and pain, WOMAC- and Oxford-Knee-Score, radiological and clinical knee symptoms/function were assessed. No loosening, wear or implant subsidence could be detected during the follow up. In comparison with results after primary TKA in the literature we found our clinical results to be within the range. The study demonstrates that thismethod is safe and produces good midterm results.

[Patella position and patellofemoral osteoarthritis after unicompartmental arthroplasty]

BACKGROUND

Changes of patellar position (height, tilt, and shift) and arthritis of the patellofemoral joint might potentially influence outcome after unicompartmental knee replacement.

OBJECTIVES

The purpose of this work is to evaluate the influence of the aforementioned parameters on postoperative outcome.

METHODS

Literature analysis via PubMed.

RESULTS

A total of 12 relevant studies (three about Patellar height, two about patellar tilt and shift, seven about patellofemoral osteoarthritis) could be identified. Regarding Patellar height, two out of three studies demonstrated a postoperative decrease. With regard to patellar tilt and shift, only one study identified postoperative lateralization of the patella to be a predictor for poor outcome. The radiological appearance of arthritis of the patellofemoral joint does not significantly influence postoperative knee function except for cases where only the lateral patellar facet is affected. Anterior knee pain has no influence on clinical outcome.

CONCLUSION

Literature data do not allow for a precise statement about the possible influence of patellar position on the outcome after unicompartmental knee replacement. With proper patient selection, good results can be achieved despite patellofemoral osteoarthritis.

Joint line reconstruction in medial unicompartmental knee arthroplasty: development and validation of a measurement method

PURPOSE

Preservation of the joint line in total knee arthroplasty (TKA) has shown to be an important factor for the long-term outcome, especially in revision TKA. For unicompartmental knee arthroplasty (UKA), the role of the joint line has neither been investigated nor is it consciously respected during implantation. Thus, the aim was to establish and validate a standardised measurement method to determine the joint line in UKA.

METHODS

As there is no established method to evaluate changes in the joint line radiologically, we introduced two methods and correlated them. The methods were first validated in a cadaver model by a controlled rotational study. Then, the joint line of 29 patients with an UKA (Oxford, Biomet, Bridgend, UK) was determined on pre- and post-operative radiographs. Both methods were tested by intra- and inter-rater reliability.

RESULTS

Both methods showed a good intra- and inter-rater reliability. Furthermore, there was only little bias in agreement between both methods and raters. Measurements of the 29 UKA patients revealed that the joint line was more distally by a mean of 4.4 ± 1.2 mm after surgery.

CONCLUSIONS

The study provides for the first time a reliable and standardised measurement tool to determine the changes in the joint line after implantation of an UKA. The instrument should be used in further studies to evaluate the impact of the joint line on the long-term outcome, the load in the two non-replaced knee compartments and on the ligaments.

[The bicompartmental knee joint prosthesis Journey Deuce: failure analysis and optimization strategies]

BACKGROUND

The Journey Deuce bicompartmental knee system is intended for patients with medial and patellofemoral arthritis of the knee and is aimed at diversifying the treatment options for knee arthritis. The prosthesis consists of a combined femoral shield with a medial condylar resurfacing component and a fixed bearing unicondylar tibial knee prosthesis. The advantages of the Journey Deuce system compared to total knee arthroplasty (TKA) are the bone sparing and cruciate retaining implantation. Outcome studies and investigation with respect to success and revision rates are rare. Thus the aim of this study was to investigate the early functional outcome as well as the revision and complication rates in patients with a Journey Deuce prosthesis within the first 2 years.

METHODS

In this study 43 patients (25 female/18 male, average age 62.4 ± 8 years and mean body mass index27.3 ± 4.5 kg/m(2)) underwent bicompartmental knee arthroplasty using the Journey Deuce prosthesis between March 2008 and March 2009. Inclusion criteria were clinically and radiographically confirmed patellofemoral arthritis, ligament stability and flexion > 90°. Exclusion criteria were extension deficits > 5°, axis deviation > 10° and patellofemoral malalignment. Patients were followed up for 6, 12 and 24 months postoperatively. Follow-up consisted of clinical and radiographical examination as well as a survey of the Knee Society score (KSS), a pain score (visual analog scale VAS, range 0-10) and a satisfaction score.

RESULTS

Of the patients 35 (82%) patients reached the 2-year follow-up and of these 35 patients 26 (75%) had a good to very good satisfaction, a mean KSS of 93 (range 65-100) and a minimal pain score of 1.2 (range 0-4). After 12 months all patients had a knee flexion of more than 90° (mean 116°, range 95°-140°). Loosening was not detected but 8 (18%) patients had to undergo revision within the first year due to persistent knee pain and instability.

CONCLUSIONS

Under clear indications and exact anatomical positioning the Journey Deuce prosthesis enables a good functional outcome; however, a high revision rate occurred in this study caused by technical complexity and insufficient variety of implant sizes which led to malalignment and instability. Additional positional guidance and a higher variability in implant sizes are required to enable an adequate treatment with anatomically correct positioning. The Journey Deuce prosthesis would then be a reasonable diversification of the endoprosthesis spectrum in knee arthroplasty and would allow a more individual and selective treatment of patients with knee arthritis.

Lateral unicompartmental knee arthroplasty: a review

Lateral unicondylar knee arthroplasty (UKA) has been utilized as a treatment for isolated lateral tibiofemoral osteoarthritis (OA) since the first description of UKA in the 1970s. To date, there remains some controversy on UKA procedures. As indications for lateral UKA are usually rare, surgeon experience seems to be the key factor for a successful intervention. Better understanding of biomechanics of the knee joint, recent developments in prosthesis design, surgical techniques and indications may add to improved outcomes of lateral UKA. Alternatives that are applied to treat lateral tibiofemoral OA include arthroscopic interventions, osteotomies and total knee arthroplasty (TKA). In comparison with TKA, potential advantages of UKA include a minimally or less invasive approach, less bone resection, preservation of the cruciate ligaments, preservation of the medial tibiofemoral and the patellofemoral compartments, shorter rehabilitation, and physiological knee kinematics. This review aims to summarize the current concepts of implant designs as well as indications and contraindications for lateral UKA. The literature will be presented and discussed as well as results and realistic expectations on both the surgeon's and the patient's side. Alternative treatments and future concepts for lateral UKA will be presented.

[Pre- and postoperative radioligical evaluation of knee joint endoprothesis. Orthopedist's view]

The implantation of a knee arthroplasty is still a demanding operation. There is still no "golden standard" available, although a lot of guidelines have been declared. Because of this fact this article should provide the radiologist with an overview of and some background knowledge for the radiological evaluation of knee arthroplasty.