IOA 2022

Subsidence of Femoral Stems in Different Hemiarthroplasty Implants

דניאל כהן Elad Harats Yaakov Tolwin Moshe Lifshitz Michael Toybenshlak Yadin Levy
Orthopedics, Sharee Zedek Medical Center, Israel

Background:
Commonly, displaced intra-capsular fractures in the elderly are treated using bipolar hemiarthroplasty, with either cemented or cementless fixation of the femoral component. Since cement can be associated with intraoperative morbidity due to the Bone Cement Implantation Syndrome, some surgeons prefer cementless implants. However, the risk of intraoperative fractures and implant subsidenece are common complications when utilizing cementless implants. Since cementless implants have multiple stem designes, we questioned if the stem design can be related with these complication.

Methods:
We retrospectivly reviewed hip hemiarthroplasties preformed at our institution, all by arthroplasty surgeons. We compared 3 groups: 50 patient recived a collarless straight tapered metaphyseal coated stem (group1), 50 patient recived a collared double tapered metaphyseal stem (Group 2) and 34 patients recived the same implant design whitout a collar (Group 3). We compared patient demographics, ASA score, intraoperative complications and radiographic asessment evaluation including implant subsidence, and proper sizing.

Results:
The average subsidence of the different implants was of 0.5 cm (Group 1), 0.17 cm (Group 2 ), and 0.7 cm (group 3). The comparison between Group 2 and the two other groups was statistically significant. Intra-operative fracture rates were 4%, 6% and 8.8% respectively. The average follow-up for all groups was six months. Demographics were similar in all groups – female/male ratio was 59%, the operated side was left in 55% of the cases, the average age was 81.7 and the average ASA score was 2.7.

Conclusion:
The collared double tapered stem (Group 2) had the least subsidence of all implants, with a similar rate of intra-operative fractures. The collar can prevent distal migration and crack propagion if such have happened during femoral braoching. It might also decrease the likelihood of intraoperative fractures, due to force dispersion over the medial calcar.