Presenter’s name (Last, First): KIRWAN, David

Qualifications: MB.,BS, FRACS, FAOrthA

Affiliations: Insight Private Hospital, ALBURY, NSW

Other authors:
As above

Email: davidkirwan59@gmail.com

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Background / Introduction:
The AOANJRR reports prosthetic revision rates. Conversely, it reports survivorship. The latter involves the recording date of patient death. The authors looked at early post-op mortality, following total knee replacement, comparing the use of conventional intra-medullary instrumentation (CIS) with an imputed high dose of fat embolism, with the use of technology assisted surgery (TAS), which avoids the insertion of intra-medullary alignment rods.

Patients / Methods:
AOANJRR data from 2002 – 2019, for 581,818 unilateral TKRs and 34,908 BSTKRs were assessed. The 30-day all-cause mortality after TKA performed for osteoarthritis, was compared
between conventional instrumentation and technology-assisted instrumentation. Firth logistic regression was used, to calculate odds ratios (ORs), adjusting for age, sex, use of cement and procedure year for the whole period and, additionally adjusting for American Society of Anesthesiologists physical status classification (ASA) and body mass index (BMI) for the period 2015 to 2019. These analyses were repeated for 7-day and 90-day mortality.

Results:

581 818 unilateral TKA procedures performed for osteoarthritis were included, of which 602 (0.10%) died within 30 days of surgery. The OR of death within 30 days following TKA performed with conventional
instrumentation compared with technology-assisted instrumentation, adjusted for age, sex, cement use, procedure year, ASA and BMI was 1.72 (95% CI, 1.23 to 2.41, p=0.001). The corresponding ORs for 7-day and 90-day mortality were 2.21 (96% CI, 1.34 to 3.66, p=0.002) and 1.35 (95% CI,
1.07 to 1.69, p=0.010), respectively.
A total of 34,908 BSTKAs were identified. The proportion of cases utilising technology-assisted instrumentation, for both TKA and BSTKA, increased over the study period. The OR of death within 30 days after technology-assisted BSTKA, adjusted for age, sex, and procedure year, was 0.26 (95% confidence interval [CI], 0.08 to 0.83; p = 0.02). The odds ratio, adjusted for age,s ex, procedure year, American Society of Anesthesiologists classification, and body mass index, was0.26 (95% CI, 0.09 to 0.74; p = 0.01). The corresponding odds ratios for 90-day mortality were 0.25(95% CI, 0.09 to 0.72; p = 0.01) and 0.26 (95% CI, 0.10 to 0.67; p = 0.005), respectively.

Conclusion:
The 30 day all-cause mortality following unilateral TKR using CIS was 1.72 times higher than with use of TAS. The 7 day mortality rate was even higher (2.21 times). The additional corresponding finding of a 4 fold increased death rate for BSTKR, requires reflection by knee arthroplasty surgeons. Insertion of intra-medullary alignment rods, that involves blunt trauma and raised hydro-static pressure, can cause a “marrow fat venogram” and therefore fat embolism. The use of technology, or a review and modification of instrumentation or technique is recommended.

Level of Evidence & Study type: III prospective observational study

Declarations of Conflict: No conflicts of interest