The clinical outcomes of cementless unicompartmental knee replacement in patients with reduced bone mineral density

Abstract

Background: Osteoporosis and osteopenia are conditions characterised by reduced bone mineral density (BMD). There is concern that bone with reduced BMD may not provide sufficient fixation for cementless components which primarily rely on the quality of surrounding bone. The aim of our study was to report the midterm clinical outcomes of patients with reduced BMD undergoing cementless unicompartmental knee replacements (UKR). Our hypothesis was that there would be no difference in outcome between patients with normal bone and those with reduced BMD. Methods: From a prospective cohort of 70 patients undergoing cementless UKR surgery, patients were categorised into normal (n = 20), osteopenic (n = 38) and osteoporotic groups (n = 12) based on their central dual-energy X-ray absorptiometry (DEXA) scans according to the World Health Organization criteria. Patients were followed up by independent research physiotherapists and outcome scores; Oxford Knee Score (OKS), Tegner score, American Knee Society Score Functional (AKSS-F) and Objective (AKSS-O) were recorded preoperatively and at a mean of 4 years postoperatively. The prevalence of reoperations, revisions and mortality was also recorded at a mean of 5 years postoperatively.Results: There were no significant differences in the midterm postoperative OKS (P = 0.83), Tegner score (P = 0.17) and AKSS-O (P = 0.67). However, the AKSS-F was significantly higher (P = 0.04) in normal (90, IQR 37.5) compared to osteoporotic (65, IQR 35) groups. There were no significant differences (P = 0.82) between normal and osteopenic bone (80, IQR 35). The revision prevalence was 5%, 2.6% and 0% in the normal, osteopenic and osteoporotic groups respectively. The reoperation prevalence was 5%, 7.9% and 0% respectively. There were no deaths in any group related to the implant. Conclusions: We found that patients with reduced BMD could safely undergo cementless UKR surgery and have similar clinical outcomes to those with normal BMD. However, larger studies with longer follow-up are needed to confirm our findings and ensure that cementless fixation is safe in patients with reduced BMD.

The effect of age on the outcomes of cementless mobile bearing unicompartmental knee replacements

“…The oldest age group (≥ 75 years) is also of concern given the generally poorer quality of bone; however, in this study, there were no cases of aseptic loosening in this group. This supports the notion that the Oxford UKR achieves similar clinical outcomes in patients with generally reduced bone mineral density [ 24 ]. This is probably partly, because with the Oxford UKR, the bone resection is minimal as 3 mm or 4 mm bearings are usually used so the retained subchondral bone is relatively dense.…”

“…Younger patients generally have higher levels of activity resulting in greater and more frequent loads being applied to the bone-prosthesis interface [ 13 ]. Older patients are more likely to have poor quality bone in which press fit implants are likely to be less reliable [ 6 , 24 ].…”

Does gender influence the outcomes of total ankle arthroplasty in patients with ankle osteoarthritis?

“…The most important aim of TAA is to provide an improved and pain-relieved ankle joint. Differences of operative outcomes for TAA between men and women could be expected, since there are differences in bone mineral density (BMD), the prevalence of generalized joint laxity, physical activity, and anatomic variations including alignment of lower extremity and bone size between the genders [27,[38][39][40][41][42]. Thus, the primary purpose of this study was to compare the intermediateterm outcomes of TAA depending on gender difference.…”

Does Gender Influence the Outcomes of Total Ankle Arthroplasty in Patients with Ankle Osteoarthritis?

“…Differences of operative outcomes for TAA between men and women could be expected, since there are differences in bone mineral density (BMD), the prevalence of generalized joint laxity, physical activity, and anatomic variations including alignment of lower extremity and bone size between the genders. [24,[34][35][36][37][38] Thus, the primary purpose of this study was to compare the intermediate-term outcomes of TAA depending on gender difference. In this study, primary outcomes were greatly improved in both groups, but we did not find differences with most patient-reported outcomes, complication rates, and survivorship between the two groups.…”