Functional recovery after knee arthroplasty with regional analgesia.

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Editor, We read with interest the systematic review and meta-analysis of randomised controlled trials assessing functional recovery after knee arthroplasty performed by Osinski et al.1 Most relevant studies have assessed postoperative complication rate, hospital length of stay and readmission rate. However, these outcomes do not necessarily define recovery from the patients’ point of view, which is return to pre-operative functional level. Therefore, previous studies have not assessed the overall clinically important functional outcomes.2 Osinski et al. assessed the influence of regional analgesia on range of motion, in addition to other outcomes measures. The authors conclude ‘we can confirm with confidence that all regional analgesia techniques are superior to systemic analgesia in terms of the range of movement achieved in the early postoperative period’. However, such confidence may be misplaced because the studies included in the analysis had significant variability in peri-operative care. For example, there was variability in the anaesthetic techniques and analgesic regimen [type of regional analgesic techniques – epidural analgesia, peripheral nerve blocks (femoral nerve block, sciatic nerve block, adductor canal block), local infiltration analgesia or periarticular infiltration technique (e.g. variable local anaesthetic drug, volume, approach to infiltration, use of cocktails etc.) and the use of nonopioid analgesics (e.g. paracetamol, NSAIDs or cyclooxygenase-2-specific inhibitors, gabapentinoids etc.)]. Also, it is possible that there was variability in the physical therapy protocols, which may have influenced functional recovery. In addition, surgical technique and postoperative care were not described in detail, thereby limiting interpretation.3 Importantly, the studies included in the meta-analysis spanned a wide time period (1990 to 2015) during which there has been a significant change in the peri-operative care of patients undergoing knee arthroplasty including the introduction of ‘enhanced recovery after surgery’ principles that has allowed significant reduction in hospital length of stay.4,5 Hospital length of stay in the earlier studies was 16 to 21 days, while the current standard is 1 to 4 days.3 In fact, knee arthroplasty is increasingly being performed on an outpatient basis with excellent safety data. Finally, the studies included in the meta-analysis by Osinski et al. had inconsistent and insufficient quality of data, particularly for hospital length of stay and range of motion (primary outcome measures for this study), which required the authors to downgrade the quality of evidence. In summary, systematic reviews and meta-analyses based upon randomised controlled trials can help clinicians in decision-making. The authors have to be congratulated for undertaking a significant effort to review the evidence for functional recovery after knee arthroplasty. However, the peri-operative period is complex and thus there is a need for critical analysis of the present evidence for optimal care versus that repeated in previous studies. The authors have not taken into consideration the above-mentioned variabilities in the included studies. None of the studies included in their analyses utilised enhanced recovery care principles, and thus the conclusions of this meta-analysis may not reflect functional recovery after knee arthroplasty nor the specific role of regional analgesia in the current clinical practice.3 Consequently, this meta-analysis could have benefited from a critical analysis of the diverse clinical practice in the included studies as well as only inclusion of studies in which the hospital length of stay was 1 to 4 days.