Unicompartmental knee arthroplasty (UKA) is a feasible alternative to total knee arthroplasty (TKA) for selected patients with severe single-compartment knee osteoarthritis. Robotic-assisted UKA (rUKA) has recently emerged as a complementary tool to ameliorate previous difficulties with manual UKA (mUKA). However, the influence of rUKA compared to mUKA on patient outcomes are still largely unknown.
To compare outcomes of the manual technique and a single robotic-assisted system in patients undergoing unicompartmental knee arthroplasty.
The PubMed-Medline was searched using terms: "robotic," "unicompartmental," "knee," and "arthroplasty" to identify all studies comparing outcomes of mUKA and rUKA. Data pertaining to the following outcomes were extracted: (1) studies comparing robotic-assisted UKA to manual UKA; (2) reports which only included the Mako UKA system (Mako Surgical Corporation, Fort Lauderdale, Florida) as the robotic-assisted system; and (3) studies which discussed implant survivorship, complications, early postoperative parameters, functional outcomes, or implant positioning. Review articles were excluded.
A total of eight publications with 337 patients who underwent rUKA and 481 who underwent mUKA were included in our analysis. Two studies reported that early postoperative pain was decreased with rUKA compared to mUKA. In one study, pain levels in the first eight postoperative weeks were 54% lower in the rUKA group and in the other, pain scores based on the numeric rating scale were significantly lower in rUKA (2.5) compared to mUKA (4.2) upon discharge (p<0.001). Furthermore, mean time to hospital discharge in this study was reduced with rUKA (42.5 ± 5.9 hours) compared to mUKA (71.1 ± 14.6 hours) (p<0.001). One study demonstrated a significant improvement in range of motion at two-year follow up in the rUKA group (15°, range, 5° to 25°) compared to the mUKA group (10°, range 0° to 20°; p=0.04). One study reported that at three-month follow up, mean Knee Society scores were significantly better in the rUKA group (164; interquartile range [IQR] 131 to 178) compared the mUKA group (143; IQR 132 to 166; p=0.04). Three studies reported more accurate implant positioning with rUKA compared to mUKA. Among the five studies that reported implant survivorship, four studies (including a randomized control trial) found no difference between techniques in implant survival rate, while one retrospective analysis reported improved survivorship with mUKA.
In conclusion, unicompartmental knee arthroplasty implants demonstrated comparable survivorship rates whether performed manually or with robotic assistance. However, compared to the manually performed procedure, robotic-assisted unicompartmental knee arthroplasty were found to offer benefits including shorter lengths of hospital stays, decreased postoperative pain scores, and improved functional outcomes.