Comparative evaluation of patellar height methods in the Brazilian population

Patellar height after unicompartmental knee arthroplasty: comparison between fixed and mobile bearing

PURPOSE

The purpose of this study was to determine the changes in patellar heights by comparing standardised pre- and post-operative radiographs in a consecutive series of patients undergoing unicompartmental knee arthroplasty (UKA) with two different approaches and implant designs [fixed bearing (FB) vs mobile bearing (MB)] and to correlate the patellar heights with clinical outcomes.

METHODS

One hundred and seventy-two UKA patients were prospectively enrolled in the study. 75 patients underwent a minimally invasive FB medial UKA (referred to hereinafter as the 'FB group'); 97 patients were treated with a minimally invasive MB medial UKA. The pre-operative and mid-term (1-year) post-operative patellar heights and clinical scores of these groups of patients were compared using the Insall-Salvati (IS) and Caton-Deschamps (CD) indices and the Oxford Knee Score (OKS).

RESULTS

No differences were found between the two groups either with regard to the pre-operative data (p > 0.05) or between pre- and post-operative radiographic scores at the time of each follow-up (p > 0.05). Both the groups reported a significant clinical improvement (p<0.05) as did all the sub-groups (p < 0.05). In the MB group, a higher CD index in females was found at the final follow-up stage (p = 0.043) and a higher pre-operative CD index was found in patients with BMI ≥ 28 (p = 0.040). A statistically negative correlation was found between the pre-operative OKS and pre-operative IS index (rho=- 0.165; p=0.031).

CONCLUSIONS

Both FB and MB arthroplastys with different surgical approaches did not change the patellar height regardless of the age, gender and BMI at short-medium-term follow-up. The post-operative patellar height seems not to be correlated with the clinical outcomes. A higher pre-operative IS index was correlated with knee pain and function.

LEVEL OF EVIDENCE

Level II-prospective comparative study.

STUDY REGISTRATION

Researchregistry6433- www.researchregistry.com .

A study of the possible effect of abnormal patella height on meniscal tears

Objective

Patellar height is key to knee biomechanics. Variations (alta/baja) have been associated with instability/dislocations, ACL ruptures etch. The effect of abnormal patella height and meniscal lesions is not clear yet; this is a first investigation of this relation.

Methods

100 patients with meniscal tears were X-Rayed to determine patellar height using the Insall-Salvati ratio and the Caton-Deschamps Index.

Results

20% had abnormal patellar height according to the Insall-Salvati ratio and 9% based on the Caton-Deschamps index.

Conclusion

This indicates that patella height could be a parameter in the occurrence of meniscal injuries worth investigating in larger populations; yet the mechanism remains unclear.