Range of motion and function are similar in patients undergoing TKA with posterior stabilised and high-flexion inserts

Abstract

It is debatable whether high-flexion (HF) total knee arthroplasty (TKA) designs will improve postoperative flexion and function or will diminish the need for manipulation under anaesthesia (MUA). We retrospectively analysed range of motion (ROM), flexion, Knee Society Score (KSS), and rate of MUA in a consecutive group of patients who underwent TKA with a conventional posterior stabilised (PS) insert or an HF insert using identical surgical technique, implant design, and postoperative care. Fifty TKAs with a standard PS insert were matched for patient's age, gender, preoperative ROM, and KSS with 50 TKA performed with an HF insert. The patient's ROM and KSS were evaluated at six weeks, four months, and one year postoperatively. The outcome variables (flexion, ROM, KSS, and manipulation rate) in both groups were compared using the generalised estimating equations method. A second analysis of patients with preoperative flexion ≥120°was performed. The ROM, flexion, and patient-reported KSS was similar in both groups at each time period. The rate of MUA was also similar. Patients with a preoperative ROM of at least 120°showed similar results. Our study found that one year after surgery, patients who underwent TKA with a PS or an HF insert achieved similar flexion, ROM, and function.

Can a High-flexion Total Knee Arthroplasty Relieve Pain and Restore Function Without Premature Failure?

“…Numerous comparative reports comparing patients implanted with a HF-TKA versus a conventional TKA using the same implant system have been published [1,4,11,15,18,22,28,32]. Some observed similar degrees of maximal knee flexion [18,22,28,32], while others demonstrated superior flexion was obtained using a HF-TKA [1,4,11,15].…”

“…Some observed similar degrees of maximal knee flexion [18,22,28,32], while others demonstrated superior flexion was obtained using a HF-TKA [1,4,11,15]. The amount of increase in flexion in studies reporting superior flexion with a HF-TKA design was typically limited (5°-10°).…”

“…A myriad of HF-TKA prosthetic designs have recently been introduced with the goal of increasing the magnitude of flexion obtained after TKA [1,4,11,12,15,18,19,22,25,28,32]. As with introduction of any new medical device, clinical evaluation of its performance and any associated adverse events is critical.…”

“…Several factors affect postoperative flexion after TKA, including preoperative (preoperative flexion, body habitus, presence of previous knee surgery [13,20,30,34]), intraoperative (ligament and gap balance, component size and position, removal of osteophytes, extensor mechanism tension and balance [10,20,21,24]), and postoperative (postoperative rehabilitation [34], postoperative complications) factors. More recently, the effect of prosthesis design on postoperative knee flexion has been of interest, resulting in development of numerous high-flexion TKA (HF-TKA) implants [1,4,11,12,15,18,19,22,25,28,32]. Early reports of patients implanted with these devices demonstrated differing data, with some reporting enhanced knee flexion and others demonstrating flexion magnitudes similar to traditional ''non-high-flexion'' TKA implants [1,15,18,19].…”

“…Others demonstrated premature failure secondary to femoral component loosening [4,12]. Many of the reports involved subjects of Asian heritage, analyzed fixedbearing types of HF-TKA [1,4,12,18,19], and had shortterm followup of 28 months or less [1,11,15,19,22,28]. Thus, the literature contains contradictory reports on whether increased motion can be achieved and whether there is an increased risk of premature failures.…”