Endoprothesenwechsel am Kniegelenk

[Very rare cases of periprosthetic malignant neoplasms : Data from 4000 cases of endoprosthetic joint replacements from the histopathologic implant register]

BACKGROUND

In 2016, the AG 11 (work group for implant-material-intolerance) of the German society for Orthopaedics and Orthopaedic Surgery (DGOOC) created a histopathologic implant register (HIR). The goal was to conduct a retrospective data analysis based on the revised SLIM-consensus-classification, which defines eight different failure mechanisms.

QUESTIONS

The analysis of 4000 cases of endoprosthetic joint replacements addressed the following questions: 1. What is the frequency distribution of different SLIM-types? 2. How does durability of endoprosthetic joint replacements differ among SLIM-types? 3. What kind of periprosthetic malignant neoplasia can be detected and how often?

RESULTS

SLIM-type I was diagnosed in 1577 cases (n = 1577, 39.4%), SLIM-type II in 577 cases (n = 577; 14.4%), SLIM-type III in 146 cases (n = 146; 3,7%), SLIM-type IV in 1151 cases (n = 1151; 28.8%), SLIM-type V in 361 cases (n = 361; 9.0%), SLIM-type VI in 143 cases (n = 143; 3.6%), SLIM-type VII in 42 cases (n = 42; 1.0%), and SLIM-type VIII in 3 cases (n = 3; 0.075%). There was statistical significance in implant durability between the different SLIM types. Among the different reasons for endoprosthetic joint replacement failure, non-infectious causes have the biggest share at 81%, with SLIM-type I (39.5%), and SLIM-type IV (29.4%) being the predominant SLIM types. Three cases of periprosthetic malignant neoplasia (SLIM-type VIII) were detected: one case of small B lymphocytic lymphoma/BCLL (C85.9; ICD-O: 9670/3), one case of diffuse large B‑cell lymphoma/DLBCL (C83.3; ICD‑O 9680/3), and one case of anaplastic large cell lymphoma (C84.7; ICD-O: 9714/3), with the latter ones being the causes for joint replacement , which indicates that malignant neoplasia is a very rare cause of endoprosthetic joint replacement (n = 2; 0.05%).

DISCUSSION

These data are complete new, especially as concerns arthrofibrosis (SLIM-type V), adverse inflammatory reactions (SLIM-type VI), and the very rare cases of periprosthetic malignant neoplasia, SLIM-type VIII, as a reason for revision. Since neither the annual review (2017) of the EPRD, nor the national evaluation report (2017) of the IQTIG provide sufficient data, this indicates the relevance of the HIR of the AG 11 of the DGOOC.

Ten-Year Results of Medial Open-Wedge High Tibial Osteotomy and Chondral Resurfacing in Severe Medial Osteoarthritis and Varus Malalignment

BACKGROUND

High tibial osteotomy (HTO) is a widely used treatment option for medial osteoarthritis and varus malalignment, especially in young patients with early osteoarthritis. Limited outcome data are available for this procedure in severe osteoarthritis, and no long-term data are available using newer implants.

PURPOSE

To determine survivorship and functional results of medial open-wedge HTO combined with a chondral resurfacing (CR) procedure (abrasion plus microfracture) in severe medial osteoarthritis (Kellgren-Lawrence grade 3 and 4) and varus malalignment. Furthermore, factors that potentially influence the outcome were analyzed.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

From September 2005 to December 2008, all cases of HTO (fixation with an angular-stable internal fixator) combined with CR were prospectively surveyed with regard to survival (Kaplan-Meier-method, not requiring arthroplasty) and functional outcome (subjective International Knee Documentation Committee [IKDC] score). Cartilage regeneration at the time of hardware removal, tibial bone varus angle (TBVA), pre- and postoperative mechanical medial proximal tibial angle (MPTA), and postoperative alignment were analyzed with regard to the result.

RESULTS

Seventy-nine knees were included (73 patients; mean age 50.9 ± 7.6 years). The follow-up rate was 90% at 10.0 ± 1.2 years (range, 8.3-12.1 years). Pre- and postoperative mechanical tibiofemoral axis were 9.6° ± 3.0° of varus and 0.6° ± 2.7° of valgus, respectively. Survival rate was 81.7% (95% CI, 72.5%-90.9%) at 10 years. Subjective IKDC score significantly improved from 44 ± 11 preoperatively to 70 ± 13 at one, 66 ± 15 at three, 66 ± 15 at five, and 65 ± 17 at ten years ( P < .001 at any point of follow-up). Poor cartilage regeneration and low preoperative IKDC score (<40) were associated with decreased survival. High preoperative TBVA was associated with better and an overcorrected MPTA (>95°) with inferior functional outcome at final follow-up, respectively.

CONCLUSION

Even in cases of severe medial osteoarthritis and varus malalignment, HTO in combination with a CR procedure is a good to excellent treatment option. The role of the CR procedure remains unclear. Although good results are obtained with overcorrected MPTA, long-term functional outcome is inferior.

Third-body abrasive wear of tibial polyethylene inserts combined with metallic and ceramic femoral components in a knee simulator study

AIM

Total knee arthroplasties have reached a high grade of quality and safety, but most often fail because of aseptic implant loosening caused by polyethylene wear debris. Wear is generated at the articulating surfaces, e.g. caused by third-body particles. The objective of this experimental study was to determine the wear of tibial polyethylene inserts combined with metallic and ceramic femoral components under third-body wear conditions initiated by bone cement particles.


METHODS AND MATERIALS

Wear testing using a cemented unconstrained bicondylar knee endoprosthesis (Multigen Plus CR knee system) was performed in a knee wear simulator. Tibial polyethylene inserts were combined with the identical femoral component design, but made of two different materials (cobalt-chromium and ceramic). Bone cement debris including zirconium oxide particles was added every 500,000 cycles between the articulating surfaces. After 5 million load cycles, the amount of wear was determined gravimetrically and compared with results from standard wear test conditions. The surfaces of tibial inserts were also analyzed.


RESULTS

The average gravimetrical wear of the tibial polyethylene inserts in combination with 
cobalt-chromium and ceramic femoral components under third-body wear conditions amounted to 31.88 ± 4.53 mg and 13.06 ± 1.88 mg after 5 million cycles, respectively, and was higher than under standard wear test conditions in both cases.


CONCLUSIONS

The wear simulator test demonstrates that wear of polyethylene inserts under third-body wear conditions, in combination with ceramic femoral components, was significantly lower than with metallic femoral components.

Comparison of cross-sections of different femoral components for revision total knee replacement

PURPOSE. To compare the inner contour of the femoral component of 10 total knee replacement (TKR) designs for possible exchange in use.

METHODS

Inner contours of the femoral components of 10 cemented, cruciate-retaining TKR designs (e.motion, Genesis, Genia, Innex, LCS, Multigen Plus, NexGen, PFC, Scorpio, Vanguard) were scanned and reconstructed to 2-dimensional contours. Their cross-sections were compared by superimposition and aligning at the distal and anterior cuts. The patellar notch and outer contour were not analysed.

RESULTS

The maximum deviation was 5 mm in the posterior and posterior oblique cuts and 10 mm in the anterior oblique cut. Based on similarity of the inner contour, LCS and Innex was classified as group I, e.motion, Genesis, Scorpio, Vanguard, and Multigen Plus as group II, and Genia, NexGen, and PFC as group III. All 2 designs in group I were not compatible with the other 8 designs. Four of the 5 designs in group II showed good compatibility. All 3 designs in group III significantly differed in the posterior and oblique cuts.

CONCLUSION

A standardised inner contour of the femoral component can increase compatibility of different TKR systems in revision surgery and reduces the extent of bone resection.