MODULAR NECK FEMORAL STEMS IN TOTAL HIP ARTHROPLASTY: IS THERE A HIGHER RISK OF REVISION? TEN-YEAR FOLLOW-UP OF 612 CASES

Modular Neck Femoral Stems (MNFS) in Total Hip Replacements (THR) gathered a lot of interest following its introduction due to its intra-operative versatility. Later due to fractures of modular necks there was recall of a few prostheses and more recently published data demonstrated higher revision rates associated with MNFS, which lead to Medicines and Healthcare products Regulations Agency (MHRA) producing a device safety advice. Media reports (‘my NHS hip replacement poisoned me’) suggested potential sequelae of high chromium levels due to double trunnion. The UK National Joint Registry (NJR), reported higher revision rates for indications as adverse reaction to metal debris or fracture of modular neck. Our retrospective study of MNFS done at a single centre between 2013 and 2022, studied Microport Stem® using cemented/Uncemented Profemur modular neck stems combined with uncemented Procotyl cup. Revision and mortality rates were analysed. Of 612 MNFS performed, there were eight revisions (1.3%). A Subset analysis showed 5 cemented THRs (no revisions), 60 uncemented THRs (1 revision- 1.7%), 547 hybrid THRs (7 revisions- 1.3%) with no significant difference in revision rates between subsets. Of 322 cases between 2013 and 2017, with follow-up ranging from 5 to 10 years, there were 1.6% revisions. Over the ten-year period, the standardised revision rate for MNFS in our institution (1.3%) was consistently remained below the national average. The NJR Implant level report at 13 years shows overall revision rate of 2.79%. No reported mortalities in last 5 years follow-up. The MHRA investigation showed 6/1000 high metal ion and a device fracture risk of 39/1000 in the highest risk group, while NJR showed a twofold revision risk of 9/100 patients. Our cohort on analysis identified only one patient in the highest risk group. In conclusion we had favourable outcomes in our cohort for modular neck THRs, with a lower revision risk than overall registry rate, for the combination of MNFS used in our hospital.