The incidence of physiological radiolucency following Oxford unicompartmental knee replacement and its relationship to outcome

Background Bone mineral density (BMD) in the proximal tibia decreases after TKA and is believed to be a factor in implant migration and loosening. Unicompartmental knee arthroplasty (UKA) is a less invasive procedure preserving knee compartments unaffected by degeneration. Finite element studies have suggested UKA may preserve BMD and that implants of differing stiffnesses might differentially affect BMD but these notions have not been clinically confirmed. Questions/purposes We therefore asked whether (1) proximal tibial BMD decreases after UKA, and (2) a cemented metal tibial component with a mobile polyethylene (PE) bearing would have greater BMD loss than a cemented PE tibial component. Methods We prospectively followed 48 patients who underwent 50 UKAs using one of two implants: one with a cemented metal tibial baseplate and a mobile PE insert (n = 26) and one with a cemented all-PE tibial component (n = 24). In followup we assessed pain and function (Oxford Knee Score, SF-12, The Knee Society Score Ó ) and radiographs. BMD changes were assessed using quantitative CT osteodensitometry performed postoperatively and at 1 and 2 years after the index procedure. Results Mean cancellous BMD decreased 1.9% on the medial side and 1.1% on the lateral side. Mean cortical BMD was static, decreasing 0.4% on the medial side and increasing 0.5% on the lateral side. The greatest observed difference between implants for any region was 3.7%. There were no differences in pain or functional outcome scores. Conclusions BMD was preserved 2 years after UKA with no major differences seen between implant types.

Section: Discussionmentioning

confidence: 99%

Proximal Tibial Bone Density Is Preserved After Unicompartmental Knee Arthroplasty

Richmond

Hadlow

Lynskey

et al. 2013

“…Additionally, the UKA cementing technique is technically demanding, particularly if limited incisions are used and if the bone is sclerotic [7,14]. We believe that aseptic loosening is a substantial reason for revision, but, especially for the Oxford 1 UKA prosthesis (Biomet Inc, Warsaw, IN, USA), radiolucent lines under the tibial tray may be misleading [6], but only in a relatively small number of patients. Even so, it appears that reliable fixation for UKAs remains an unsolved problem [20].…”

Section: Discussionmentioning

confidence: 99%

Unicompartmental Knee Arthroplasty Survivorship is Lower Than TKA Survivorship: A 27-year Finnish Registry Study

Niinimäki

Eskelinen

Mäkelä

et al. 2014

154

Background Balancing the relative advantages and disadvantages of unicompartmental knee arthroplasties (UKAs) against those for TKAs can be challenging. Survivorship is one important end point; arthroplasty registers repeatedly report inferior midterm survival rates, but longer-term data are sparse. Comparing survival directly by using arthroplasty register survival reports also may be inadequate because of differences in indications, implant designs, and patient demographics in patients having UKAs and TKAs. Questions/purposes The aims of this study were to assess the survivorship of UKA in the context of one large, northern European registry, and to compare the rates of survivorship with those of cemented TKAs performed for primary knee osteoarthritis during the same 27-year period. Methods From the Finnish Arthroplasty Register, we obtained the data for 4713 patients undergoing UKAs for primary osteoarthritis (mean age, 63.5 years; minimum followup, 0 years; mean, 6.0 years; range, 0-24 years) who had surgical revision between 1985 and 2011. From this cohort, we calculated the Kaplan-Meier survivorship for revision performed for any reason and compared it with the survivorship of 83,511 patients (mean age, 69.5 years; minimum followup 0 years; mean, 6.4 years; range, 0-27 years) with TKAs treated for primary osteoarthritis during the same period. Data were adjusted for age and sex in a comparative analysis.

“…The presence of radiolucent lines was noted on standard AP and lateral radiographs of the knee. The ICC for interrater reliability of assessment of the presence of radiolucent lines after UKA is greater than 0.98 [8]. Progression of medial compartment degenerative disease was defined as progression of the medial compartment to a more severe stage of degeneration according to the International Knee Documentation Committee (IKDC) system [10].…”

Section: Methodsmentioning

confidence: 99%

Lateral Unicompartmental Knee Arthroplasty Relieves Pain and Improves Function in Posttraumatic Osteoarthritis

Lustig

Parratte

Magnussen

et al. 2012

Background Posttraumatic arthritis secondary to lateral tibial plateau fracture malunion causes pain and limited function for patients. It is sometimes technically challenging to correct malalignment in these patients with advanced arthritis using osteotomies. Lateral unicompartmental knee arthroplasty (UKA) may be an option to treat such patients. Questions/purposes We asked whether UKA for lateral posttraumatic osteoarthritis (1) reliably alleviates pain and improve function, (2) restores lower limb alignment, and (3) is as durable as UKA for primary lateral osteoarthritis. Patients and Methods We retrospectively reviewed 13 patients with lateral cemented UKA (mean age at surgery, 50.1 years) treated at two institutions between 1985 and 2007. We obtained Knee Society scores and evaluated radiographs for evidence of implant loosening or progression of arthritis in the medial compartment. Minimum followup was 3 years (mean, 10.2 years; range, 3-22.1 years). Results Mean Knee Society knee score improved from 51 points (range, 29-75 points) preoperatively to 88 points (range, 65-100 points) at last followup, suggesting the procedure relieved pain. Mean function score improved from 51 points (range, 10-89 points) preoperatively to 87 points (range, 35-100 points) at last followup. The mean hip-knee-ankle angle was 188°preoperatively (range, 184°-1938) and 185°(range, 183°-188°) at last followup. Prosthesis survivorship was 100% at 5 and 10 years and 80% at 15 years.