Pre-emptive peripheral nerve block delays recovery after total knee arthroplasty

Mean length of stay for patients who recovered on postoperative day one was 4.8 days and on postoperative day two was 5.6 days.

One-third of patients who received pre-emptive peripheral nerve blocks perioperatively for total knee replacement had a delayed recovery, according to a prospective study.

Rohit Singhal, MRCS, and Karen L. Luscombe, FRCS, sought to determine the rate of delayed recovery in cases of primary total knee replacement (TKR) in which bupivacaine was used as a sciatic or femoral nerve block and whether the analgesia influenced length of stay. They also aimed to standardize length of stay by eventually adjusting the concentration and amount of peripheral nerve block (PNB) used.

“The study was conducted with an aim to see whether we can reduce the length of stay because length of stay in total knee replacement is one of the primary determinants of the financial cost that is involved,” Rohit, who presented the research at the British Orthopaedic Association and Irish Orthopaedic Association Combined Meeting 2011, told Orthopedics Today.

The researchers interviewed 34 patients who underwent TKR between April 2010 and January 2011. The patients had an average age of 70.1 years, and the group included 19 men.

Each patient received 0.375% bupivicaine, 20 mL each in their sciatic and femoral nerve. Patients who received any other type of anesthetic were excluded from the study. The researchers also excluded patients with postoperative complications or social reasons that would delay discharge. Follow-up was conducted until patients achieved mobility of flexion, walking on a flat surface without assistance, stair climbing and other physical therapy exercises.

The team found that one-third of patients who received bupivicaine had a delayed recovery. Mean length of stay for patients who recovered on postoperative day one was 4.8 days. Mean length of stay for patients who recovered on postoperative day two was 5.6 days.

“We were not surprised by the findings, because if their recovery is delayed by one day, then the length of stay should be increased by one day because, logistically, it could be difficult to provide them with physical therapy if they have not recovered on the first day,” Singhal explained.

The study was limited by a small number of patients and short examination period lasting until 4:00 p.m., after which patients could not receive physical therapy. The investigators examined some patients the next day at 8:00 a.m.

For the future, Singhal and Luscombe hope to test various drug combinations to see if they can shorten length of stay. – by Renee Blisard

References:

• Singhal R, Luscombe KL. Incidence of delayed recovery from peripheral nerve block in primary total knee replacement and its influence on length of stay. Presented at the British Orthopaedic Association and Irish Orthopaedic Association Combined Meeting 2011. Sept. 13-16. Dublin.

• Rohit Singhal, MRCS, can be reached at Flat #3, Lundstrom House, Ormskirk General Hospital, Orsmkirk, UK; +44-7838008900; email: singhal.rohit75@gmail.com.
• Disclosure: Singhal has no relevant financial disclosures.

This addresses an important issue, which is the balance between achieving optimal analgesia in order to allow patients to mobilize quickly after knee arthroplasty and the risk that that analgesic modality will delay the mobilization and delay discharge. This paper is potentially interesting in that it reaches the conclusion — that many surgeons assume at the outset — which is that nerve blocks delay mobilization and, hence, lengthen hospital stay after knee replacement surgery.

This study is weak in that it is not a randomized study. We are not provided with detail around time of day of surgery. In simple terms, the authors conclude that those patients who recover from their nerve block on day one go home a day earlier than those who recover from their nerve block on day two. The data in the study is predictable. It is too small a study on which to base guideline changes, but it is clear that a great deal of work still needs to be done to work out the best analgesic modality after knee arthroplasty and to ensure that modality does not limit subsequent mobilization.

Until nerve blocks can be demonstrated to work effectively and not increase length of stay, other modalities such as intra-articular infiltration should be used as a first line.

— Fares S. Haddad, FRCS (Orth)
University College Hospital
London, UK
Disclosure: Haddad has no relevant financial disclosures.

A recent retrospective study by Drs. Singhal and Luscombe followed patients having total knee arthroplasty who were treated with both a femoral and a sciatic nerve blocks. Of the 34 patients in the study, 10 patients had a persistent block on the second postoperative day and these patients ended up with a longer length of stay in hospital by 0.8 days than the 24 patients who recovered from their block within the first postoperative day.

This study addresses an important issue: it is necessary to balance the analgesia needs of patients while maintaining an efficient use of hospital resources. While these study results are interesting (it shows that prolonged motor block may increase the length of hospital stay), they are limited by the small sample size, the non-randomized comparison between groups and the lack of a control group that was not treated with a regional block. As such, the difference between the two groups of patients in this study may be due to factors other than the duration of block. It may be a chance finding that would not persist with a larger sample of patients and, without a control group, it is not really clear that regional blocks actually do increase length of stay.

In a recent meta-analysis by our team at McMaster University, we analyzed the results of 23 randomized controlled trials that investigated femoral and sciatic block for total knee arthroplasty, and we found that these blocks did not influence length of stay.

— James Paul, MD
Associate clinical professor
Research Chair & Director,
Acute Pain Service
McMaster University Department of Anesthesia
Hamilton Health Sciences
Hamilton, ON, Canada
Disclosure: Paul has no relevant financial disclosures.