UK poSt Arthroplasty Follow-up rEcommendations (UK SAFE): what does analysis of linked, routinely collected national datasets tell us about mid-late term revision risk after knee replacement?

[Current AWMF guidelines on knee and hip arthroplasty - individual risks]

BACKGROUND

In the year 2022, more than 300,000 total hip and knee primary arthroplasties were recorded in the German Arthroplasty Registry. The ever-increasing number of interventions naturally leads to an increase in the absolute number of possible complications. The abundance of internationally available data makes it possible to determine risk factors for postoperative complications.

RISK FACTORS

Professional societies involved in the German guidelines in the field of orthopedics place great emphasis on modifiable risk factors, as their adequate management can consequently reduce the likelihood of postoperative complications. One of the most common modifiable risk factors is obesity, with its prevalence remaining consistently high in most developed countries. In the field of orthopedics, the Association of the Scientific Medical Societies in Germany focuses on modifiable risk factors including obesity, diabetes mellitus and smoking.

OBESITY

In the case of obesity in particular, the guidelines for knee and hip arthroplasty recommend a weight loss attempt for patients with a BMI > 30 kg/m2. A BMI ≥ 40 kg/m2 is considered a "relative contraindication" in the guidelines. Shared decision making is emphasized in both guidelines. Ultimately, the particularly critical individual assessment of risk and benefit for each obese patient remains crucial for the final decision.

Finite element analysis of the effect of tibial osteotomy on the stress of polyethylene liner in total knee arthroplasty

AIM

To explore the effects of tibial osteotomy varus angle combined with posterior tibial slope (PTS) on the stress of polyethylene liner in total knee arthroplasty (TKA) by building finite element model (FEM).

METHODS

Established the FEM of standard TKA with tibial osteotomy varus angle 0° to 9° were established and divided into 10 groups. Next, each group was created 10 FEMs with 0° to 9° PTS separately. Calculated the stress on polyethylene liner in each group in Abaqus. Finally, the relevancy between tibial osteotomy angle and polyethylene liner stress was statistically analyzed using multiple regression analysis.

RESULTS

As the varus angle increased, the area of maximum stress gradually shifted medially on the polyethylene liner. As the PTS increases, the percentage of surface contact forces on the medial and lateral compartmental of the polyethylene liner gradually converge to the same. When the varus angle is between 0° and 3°, the maximum stress of the medial compartmental surfaces of polyethylene liner rises smoothly with the increase of the PTS. When the varus angle is between 4° and 9°, as the increase of the PTS, the maximum stress of polyethylene liner rises first and then falls, forming a trough at PTS 5° and then rises again. Compared to the PTS, the varus angle has a large effect on the maximum stress of the polyethylene liner (p < .001).

CONCLUSION

When the varus angle is 0° to 3°, PTS 0° is recommended, which will result in a more equalized stress distribution of the polyethylene liner in TKA.

Routine follow-up may not be needed for people undergoing joint replacement surgery

The studyKingsbury SR, Smith LK, Czoski Murray CJ, et al. Safety of disinvestment in mid- to late-term follow-up post primary hip and knee replacement: the UK SAFE evidence synthesis and recommendations. Health Soc Care Deliv Res 2022;10. doi:10.3310/KODQ0769To read the full NIHR Alert, go to: https://evidence.nihr.ac.uk/alert/joint-replacement-many-people-can-safely-wait-10-years-for-follow-up/.