Restoration of normal knee kinematics with respect to tibial insert design in mobile bearing lateral unicompartmental arthroplasty using computational simulation

The risk of tibial eminence avulsion fracture with bi-unicondylar knee arthroplasty : a finite element analysis

AIMS

The aim of this study was to determine the risk of tibial eminence avulsion intraoperatively for bi-unicondylar knee arthroplasty (Bi-UKA), with consideration of the effect of implant positioning, overstuffing, and sex, compared to the risk for isolated medial unicondylar knee arthroplasty (UKA-M) and bicruciate-retaining total knee arthroplasty (BCR-TKA).

METHODS

Two experimentally validated finite element models of tibia were implanted with UKA-M, Bi-UKA, and BCR-TKA. Intraoperative loads were applied through the condyles, anterior cruciate ligament (ACL), medial collateral ligament (MCL), and lateral collateral ligament (LCL), and the risk of fracture (ROF) was evaluated in the spine as the ratio of the 95^th percentile maximum principal elastic strains over the tensile yield strain of proximal tibial bone.

RESULTS

Peak tensile strains occurred on the anterior portion of the medial sagittal cut in all simulations. Lateral translation of the medial implant in Bi-UKA had the largest increase in ROF of any of the implant positions (43%). Overstuffing the joint by 2 mm had a much larger effect, resulting in a six-fold increase in ROF. Bi-UKA had ~10% increased ROF compared to UKA-M for both the male and female models, although the smaller, less dense female model had a 1.4 times greater ROF compared to the male model. Removal of anterior bone akin to BCR-TKA doubled ROF compared to Bi-UKA.

CONCLUSION

Tibial eminence avulsion fracture has a similar risk associated with Bi-UKA to UKA-M. The risk is higher for smaller and less dense tibiae. To minimize risk, it is most important to avoid overstuffing the joint, followed by correctly positioning the medial implant, taking care not to narrow the bone island anteriorly.Cite this article: Bone Joint Res 2022;11(8):575-584.

Return to Sport After Unicompartmental Knee Arthroplasty: A Systematic Review and Meta-analysis

Background:

Patients undergoing unicompartmental knee arthroplasty (UKA) often want to return to sport (RTS) after surgery. However, the time taken to RTS and proportion of patients who RTS after UKA remain unknown.

Purpose:

To determine the time to RTS and proportion of patients who RTS after UKA.

Study Design:

Systematic review; Level of evidence, 4.

Methods:

A search was performed using PubMed, Medline, Embase, SPORTDiscus and the Cochrane Library databases for clinical trials reporting on RTS after UKA published between database inception and September 2021. In addition, a manual search was performed of relevant sports medicine and orthopaedic journals, and bibliographies were reviewed for eligible trials. The PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines were used to undertake this study.

Results:

This meta-analysis included 11 studies (749 patients) that reported on RTS after UKA. The proportion of patients returning to sports increased over time: 6 studies (432 patients) demonstrated an overall pooled proportion of 48.1% (95% CI, 36.3%-60.2%) of patients who returned to sport at 3 months after surgery, while 7 studies (443 patients) demonstrated an overall pooled proportion of 76.5% (95% CI, 63.9%-87.1%) of patients who returned to sport at 6 months after surgery. Overall, 92.7% (95% CI, 85.8%-97.4%) of 749 patients were able to RTS at 4 years after surgery. Overall excellent patient-reported functional outcomes scores and low risk of complications with RTS after UKA were reported.

Conclusion:

The authors found that 48.1% of patients were able to RTS at 3 months after surgery and 76.5% were able to RTS at 6 months after UKA. Pooled proportion analysis showed that >90% of patients undergoing UKA were able to RTS at 48 months after surgery. The majority of patients who were able to RTS after UKA did so at a lower level of intensity than their preoperative level. RTS after UKA was associated with good patient-reported functional outcomes scores and a low risk of complications.