Mid-term clinical results of primary total knee arthroplasty using metal block augmentation and stem extension in patients with rheumatoid arthritis

Abstract

BackgroundDespite recent advancements in rheumatoid arthritis (RA) pharmacotherapy, surgeons still encounter severely damaged knees. The purpose of the present study was to analyze the mid-term clinical results of total knee arthroplasty (TKA) with metal block augmentation and stem extension.MethodsA total of 26 knees in 21 patients who underwent primary TKA with metal block augmentation and stem extension were retrospectively reviewed. All patients with a mean age of 63 years had RA for a mean duration of 15 years. Functional and radiographic results as well as complications were evaluated at the mean follow-up period of 6 years after TKA. Eight knees were lost follow-up after the two-year evaluation.ResultsTibial bone defects with average depth of 19 mm were preoperatively recognized in all 26 knees. The postoperative joint line was reconstructed on average 11 mm above the fibular head using average thickness of 11 mm tibial inserts and 9 mm metal blocks with stem extension. Significant improvements (p < 0.05 for all comparisons) were observed postoperatively in maximum extension angle from −10° to −1°, range of motion from 101 ° to 115 °, and Knee Society Score (knee score/function score) from 35/18 to 90/64. Non-progressive radiolucent lines beneath the metal block and osteosclerotic changes around the medullary stem were found in 16 knees (62 %) and 14 knees (54 %), respectively. There was two failures (8 %): fragile supracondylar femur fractures and knee instability. No knees showed any radiographic implant loosening, dislocation, polyethylene insert breakage, peroneal palsy, or infection.ConclusionsPrimary TKA with metal block augmentation and stem extension could effectively restore function in RA patients with advanced forms of knee joint destruction, and be reliable and durable for a mean postoperative period of 6 years. Further study is needed to determine the long-term results of TKA using metal block augmentation and stem extension.

Design of Porous Metal Block Augmentation to Treat Tibial Bone Defects in Total Knee Arthroplasty Based on Topology Optimization

“…This showed that the stress on the block had been effectively reduced. Previous studies reported the radiolucent line beneath the block as a shortcoming in TKA, which might be due to bone resorption (Guha et al, 2008;Hamai et al, 2015). Stress shielding can cause bone resorption, resulting in the radiolucent line.…”

Total knee arthroplasty in osteogenesis imperfecta

“…The role of these tools has not yet been clearly delineated, but they may potentially be useful for OI patients with severe extraarticular deformities or abnormally small extremities [16] , [17] . Stem extensions may be helpful to restore function in patients with significant joint destruction or prevent loosening in patients with a significant angular deformity [18] , [19] . However, further data to help analyze the costs and benefits of extended stems are still needed.…”

Finite element analysis of the effect of tibial prosthesis extension stem length in total knee arthroplasty in the Chinese population

“…However, even when the stem length reached a higher measurement range of 70-80 mm, the influence of stem length on prosthesis stability tended to be similar. Previous studies have reported that using the tibial extension stem indeed improved prosthesis stability during primary TKA [10,11,13,14]; however, these studies only compared the stability of tibial prosthesis between cases in which the extension stems were used and cases in which they were not used. They also lacked an accurate analysis of the effects of different stem lengths on the stability of tibial prostheses.…”

“…The most common cause of TKA failure is prosthesis loosening [6,7], particularly on the tibial side [8,9]. Some osteoporosis patients with severe varus deformities and poor soft tissue conditions due to RA are more likely to experience loosening of the tibial prostheses after primary TKA [10,11,12].…”