An assessment of early functional rehabilitation and hospital discharge in conventional versus robotic-arm assisted unicompartmental knee arthroplasty: a prospective cohort study

Bone Joint J. 2019 Jan;101-B(1):24-33. doi: 10.1302/0301-620X.101B1.BJJ-2018-0564.R2.


Aims: The objectives of this study were to compare postoperative pain, analgesia requirements, inpatient functional rehabilitation, time to hospital discharge, and complications in patients undergoing conventional jig-based unicompartmental knee arthroplasty (UKA) versus robotic-arm assisted UKA.

Patients and methods: This prospective cohort study included 146 patients with symptomatic medial compartment knee osteoarthritis undergoing primary UKA performed by a single surgeon. This included 73 consecutive patients undergoing conventional jig-based mobile bearing UKA, followed by 73 consecutive patients receiving robotic-arm assisted fixed bearing UKA. All surgical procedures were performed using the standard medial parapatellar approach for UKA, and all patients underwent the same postoperative rehabilitation programme. Postoperative pain scores on the numerical rating scale and opiate analgesia consumption were recorded until discharge. Time to attainment of predefined functional rehabilitation outcomes, hospital discharge, and postoperative complications were recorded by independent observers.

Results: Robotic-arm assisted UKA was associated with reduced postoperative pain (p < 0.001), decreased opiate analgesia requirements (p < 0.001), shorter time to straight leg raise (p < 0.001), decreased number of physiotherapy sessions (p < 0.001), and increased maximum knee flexion at discharge (p < 0.001) compared with conventional jig-based UKA. Mean time to hospital discharge was reduced in robotic UKA compared with conventional UKA (42.5 hours (sd 5.9) vs 71.1 hours (sd 14.6), respectively; p < 0.001). There was no difference in postoperative complications between the two groups within 90 days' follow-up.

Conclusion: Robotic-arm assisted UKA was associated with decreased postoperative pain, reduced opiate analgesia requirements, improved early functional rehabilitation, and shorter time to hospital discharge compared with conventional jig-based UKA.

Keywords: Hospital discharge; Pain; Rehabilitation; Robotics; Unicompartmental knee arthroplasty.

Publication types

  • Comparative Study
  • Evaluation Study

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Analgesia, Patient-Controlled / methods
  • Analgesics, Opioid / therapeutic use
  • Arthroplasty, Replacement, Knee / rehabilitation*
  • Female
  • Humans
  • Length of Stay / statistics & numerical data
  • Male
  • Middle Aged
  • Observer Variation
  • Osteoarthritis, Knee / physiopathology
  • Osteoarthritis, Knee / rehabilitation*
  • Osteoarthritis, Knee / surgery
  • Pain, Postoperative / etiology
  • Pain, Postoperative / rehabilitation
  • Postoperative Care
  • Prospective Studies
  • Range of Motion, Articular / physiology
  • Robotic Surgical Procedures / rehabilitation*
  • Treatment Outcome
  • Young Adult


  • Analgesics, Opioid