Time is an enemy of all orthopaedic implants, just as it is the bane of native joints. It is therefore helpful to accurately measure how long and well specific implant types last. That is what Kim et al. have done with their 19-year follow up of 90 patients (107 knees) who underwent total knee arthroplasty (TKA) with a constrained condylar knee prosthesis. Their findings appear in the April 15, 2020 issue of The Journal of Bone & Joint Surgery.
Knee arthroplasty surgeons often choose constrained prostheses to improve joint stability in patients with ligament dysfunction, and the typically longer stems of these implants can also compensate for poor bone stock. Kim et al. evaluated the same patient population (mean age of 65 years; mean BMI of 26.9 kg/m2) that they reported on in an earlier study, finding the following outcomes after a mean follow-up of 19 years:
- 96% survival in terms of mechanical failure
- 91% survival in terms of reoperation for any reason
- Patient-reported outcome scores that remained significantly improved from pre-revision values
- Only 1 knee with osteolysis around a component
Among the few knees that required re-revision, 5 such operations were performed due to aseptic loosening and 4 due to infection. The authors note that these very good long-term results are similar to those in previous studies of revision TKAs using various implant types. Kim et al. attribute these findings to several possible factors:
- Low prevalence of comorbidities, including obesity, among the patients
- Excellent surgical technique, including good cementing and correct flexion and extension gaps
- Use of compression-molded polyethylene
This tip comes from Fred Nelson, MD, an orthopaedic surgeon in the Department of Orthopedics at Henry Ford Hospital and a clinical associate professor at Wayne State Medical School. Some of Dr. Nelson’s tips go out weekly to more than 3,000 members of the Orthopaedic Research Society (ORS), and all are distributed to more than 30 orthopaedic residency programs. Those not sent to the ORS are periodically reposted in OrthoBuzz with the permission of Dr. Nelson.
It is well-established that total hip arthroplasty (THA) improves quality of life, but how about longevity itself? Cnudde et al.1 attempted to identify associations between THA and lower mortality rates, acknowledging that such rates may also be influenced by diagnostic, patient-related, socioeconomic, and surgical factors.
Using data from the Swedish Hip Arthroplasty Register, the authors identified 131,808 patients who underwent THA between January 1, 1999 and December 31, 2012. Among those patients, 21,755 died by the end of follow-up. Relative survival among the THA patients was compared with age- and sex-matched survival data from the entire Swedish population.
Patients undergoing elective THA had a slightly improved survival rate compared with the general population for approximately 10 years after surgery, but by 12 years, there was no survival-rate difference between patients undergoing THA and the general population (r = 1.01; 95% CI, 0.99-1.02; p = 0.13).
After controlling for other relevant factors and using primary osteoarthritis as the reference diagnosis, the authors found that patients undergoing THA for osteonecrosis of the femoral head, inflammatory arthritis, and secondary osteoarthritis had poorer relative survival.
In addition, married patients and those with higher levels of education fared better. The authors could not pinpoint the reasons for the increase in relative survival among THA patients, but these findings suggest that the explanation is most likely multifactorial.
- Do Patients Live Longer After THA and Is the Relative Survival Diagnosis-specific?Cnudde P, Rolfson O, Timperley AJ, Garland A, Kärrholm J, Garellick G, Nemes S. Clin Orthop Relat Res. 2018 Feb 28. doi: 10.1007/s11999.0000000000000097. [Epub ahead of print]