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Complete Wound Dehiscence after Peripheral Nerve Block for Knee Arthroplasty. A Nursing Issue?

D Kevin Lester

Address for Correspondence:

D Kevin Lester,
6085 N. First Street, Fresno, CA 93710,
United States

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Three patients of 222 who had total knee arthroplasty (TKA) with peripheral nerve blocks (PNB) suffered a post-operative in-hospital fall with complete wound disruption requiring emergency re-operation. These complications all occurred late in our experience with PNB and followed a change in ward nursing organization. All three patients attempted to ambulate to or from the bathroom without assistance despite instruction to the contrary.

J.Orthopaedics 2010;7(3)e2


knee arthroplasty; peripheral nerve block; complications; nursing


Peripheral nerve blockade (PNB) for total knee arthroplasty decreases pain, motor function, and proprioception in the involved limb. It has been reported to lessen postoperative use of narcotics and their attendant side effects [1,2,3], lower pain scores [2,4], speed recovery [2,4,5], and lower costs [6] but may give rise to serious complications [7]. Nerve injuries are uncommon with use of ultrasound guidance and nerve stimulation to increase the anatomic and physiologic accuracy of injection [7,8].   Other complications have been described uncommonly. 

We report three patients that sustained falls with complete traumatic wound dehiscence within hours of successful administration of PNB for TKA.  This unanticipated complication of new technology has been reported by others in small numbers [7-9].   Possible causes and methods of avoiding this severe complication are discussed.

Materials and Methods:

Three patients of 222 had falls with complete wound dehiscence following TKA. For the first 9 months of our experience (105 patients) continuous femoral nerve block (FNB) by pump with an indwelling catheter was used.  During the following 10 months (117 patients) a single-dose sciatic nerve block (SNB) was added to address posterior pain [10, 11].  Preoperatively, informed consent was obtained and all patients were carefully instructed that they must not ambulate after surgery until otherwise instructed.

Ultrasound and electrical stimulation confirmed that the catheter was properly placed near and not in the femoral nerve. A constant infusion of  0.2% ropivacaine was administered at a rate of 6 ml/hr by commercial external pump designed for this purpose.  The catheter was left in place the day of surgery and through the first postoperative day.  The rate was adjusted down to 2 ml/hr at the nurse’s discretion. Supplemental parenteral and/or oral narcotic medication was provided as necessary.

When SNB was used, the sciatic nerve was identified approximately 15 cm proximal to the posterior knee. Ultrasound and electrical stimulation were used as above to guide a single preoperative 20 ml injection of 0.25% bupivacaine . 

On postoperative arrival to the ward, patients were again reminded that they must not ambulate unassisted until otherwise instructed.   With diminution of anesthetic effect after scheduled removal of the catheter and pump, a physical therapist experienced in working with PNB TKA patients evaluated the patient for readiness for ambulation by a defined protocol. First, the patient is asked to perform a quadriceps activation ("quad set").  If satisfactory, the patient is assisted to sit at the bedside and asked to perform a "large arch" range of motion of the knee.  If acceptable, the patient is asked to attempt to stand without physical assistance, using the walker.   If unable, or if physical therapist examination determines that altered proprioception still exists, the effort is deferred. If each of these elements is evaluated as acceptable by the physical therapist, ambulation proceeds with the use of the walker under the careful guidance of the physical therapist. Otherwise, the attempt is terminated and re-evaluation is scheduled for a later time.


Case 1:  A 56-year-old woman with traumatic arthritis and valgus deformity required use of a walker.  She had failed conservative treatment, including NSAIDs and injections of hyaluronic acid and cortisone.  She had unilateral TKA with PNB of the femoral and sciatic nerves as above. Eight hours after her surgery she tried to go to the bathroom unassisted. She had inadequate control of the leg. She fell and flexed her knee with complete wound dehiscence.  She had not asked for assistance.

Case 2:  A 41-year-old woman with bilateral degenerative arthritis with mild varus deformity of the knees was planned for left TKA with FNB and SNB.  She used a cane and failed the same conservative maneuvers as Case 1. A physical therapist assisted her to walk to the bathroom, and then was left alone for privacy. The patient attempted to get off the toilet unassisted and fell to the floor due to lack of leg control.  The wound completely dehisced.  

Case 3:  A 72-year-old man with right knee arthritis, varus deformity, and significant heart disease used a cane and had failed conservative maneuvers, as Case 1.  He underwent TKA with FNB and SNB.  Postoperatively, he tried to walk unassisted to the bathroom. The nurse was standing at the door of the room.  His knee flexed as he fell to the floor with the same wound dehiscence as Cases 1 and 2 and was found to have a peroneal nerve dysfunction after the fall.


In each case after their injury the patient recalled the admonition to not walk without assistance.  Post-fall, each patient was treated identically. The wound was immediately packed in Betadine antiseptic-soaked gauze, parenteral antibiotics were administered, and the patient was taken back to the operating room where the knee and soft tissue was irrigated with 10 liters of sterile saline, 200 cc Betadine and Bacitracin (antibiotic)  solution, and the wound was primarily reclosed. Prophylactic IV antibiotics were switched after 3 days to oral antibiotics, which were continued for two weeks.  Intraoperative cultures were negative for bacterial growth in all 3 cases. Each patient was informed that data concerning their case would be submitted for publication. 

Results :

At early follow-up (6, 7, and 8 months for Case 1, 2 and 3, respectively) none of these patients had developed a superficial or deep infection.  All had primary wound healing. Case 2 had restriction of range of motion of 0-30 degrees six weeks after her repair. This was treated with closed manipulation under general anesthesia resulting in  knee range of motion to 0-100 degrees 3 months after initial surgery. Case 3 had an extended hospital stay due to cardiac issues unrelated to his knee surgeries. His peroneal nerve dysfunction was not completely resolved six months after the surgery.

Discussion :

Sequelae of falls with dehiscence reported to date include loss of range of motion, fracture, and prolonged drainage, but fortunately not post-operative infection [8].             In the report of major complications associated with FNB by Feibel, et al, [7]  8 of 1190 (0.6%) TKA patients had falls of which only 3 (38%) had wound dehiscence. This group has subsequently reduced usage of PNB in favor of periarticular injections.  Atkinson, et al [9] reported four cases of patient falls and Kandasami, et al [8] reported five cases of falls of a cohort of 235 (2.1%).  These authors suggest that the loss of pain, proprioception and motor control were responsible for the falls. Whiting, et al, [12] reported sciatic perineural use of clonidine and buprenorpine in 2 cases of knee surgery with preservation of below-knee gross motor function. 

Fall with complete wound dehiscence was first seen rather late in our PNB experience. For the first 191 patients over 16 months, no such complications occurred.  This was followed by 3 occurrences in 31 patients over a 3-month period following a change in nursing unit organization. In an endeavor to avoid future problems of this type, we evaluated possible contributing factors to patient falls.

Addition  of SNB.  After 9 months of using FNB only (105 patients) we adopted the addition of single-dose sciatic nerve blocks to address residual posterior pain [10,11]. This resulted in a nearly equal number of FNB only and FNB + SNB patients (105 and 117 respectively). There were no falls with FNB only or during our first 7 months (159   patients) after addition of SNB but before the change in nursing organization (see below).

It seems unlikely, therefore, that addition of SNB precipitated our cluster of cases.

Adequacy of pre-ambulation evaluation.  An inadequate evaluation by personnel could conceivably lead to premature permission to ambulate.  We utilized physical therapists well experienced and trained in the evaluation of PNB TKA patients. Both the nurses and the patients themselves agreed that the three case patients had not yet received permission to stand or ambulate without assistance, so this possible factor was rejected.

Patient failure to follow instructions.  A factor common to these patients’ falls was failure of the patient to follow instructions to avoid ambulation without assistance.  In each case, after their injury the patients acknowledged they had received this instruction. Patient 1 and 3 fell when they attempted to get to the bathroom without assistance. Case 2 had assistance from bed to bathroom, where she was left alone for privacy.  When done with the toilet, she attempted to stand without calling for assistance and fell. The PNB likely caused these patients to overestimate their capabilities.

Restraints.  Medications, strange surroundings, and fat embolism may contribute to confusion and failure to follow postoperative instructions.  In such case, strict bed rest with restraints may be necessary to enforce the instruction and thus avoid falls, but none of these patients was noted to have such problems in the nursing record or on post-fall evaluation. These patients were in possession of their faculties but misinterpreted their capabilities, probably as a result of their PNB treatment. The complications associated with restraints, their unpleasant patient experience, and the expense of the burdensome administrative overhead [13, 14] argue against their routine use but rather for close patient observation with very selective use.

Knee immobilizer.  It may be thought that use of a knee immobilizer would help patients stay in bed and/or prevented leg buckling and falls.  However patients and staff may overestimate the adequacy of its support. This may inappropriately encourage premature ambulation, thus actually increasing rather than reducing the risk of falls.  The immobilizer also impedes the use of CPM.  For these reasons, we prefer not to use knee immobilizers.

Urinary catheter use.  A factor common to the three cases was the patients’ need to empty their bladders. Routine use of urinary catheters would have eliminated the ill-fated desire to ambulate to the bathroom. Complications of urinary catheters are common, can be catastrophic (bacteremic seeding of the prosthesis, for instance) and such complications may not be reimbursable under new Medicare rules [15-17].  We do not routinely use urinary drainage catheters, but prefer prompt response to patients’ requests for assistance by trained and experienced personnel. Increased nursing awareness of patients' disability with PNB and the consequences of not meeting their bedpan needs might have diminished the risk of ill-fated attempts to walk to the bathroom. Our new motto is, “Don’t pee with your new knee”.

Dedicated Personnel.  For the first 16 months of our PNB use, our hospital had a dedicated Total Joint Arthroplasty (TJA) Program.  On the ward, this consisted of designated adjacent rooms, a dedicated group of nurses and a physical therapist. A mandated change resulted in our patients no longer having designated personnel or rooms for the final 3 months and 31 patients of the series.  The patients were then cared for in a general orthopedic ward.  Retrospective review revealed that 0 of 191 patients with the TJA program and 3 of 31 patients subsequent to its termination experienced falls with wound dehiscence. Case 1 occurred two weeks after the change.


The use of PNB and our desire to gain the benefits of early mobilization may not be wholly congruent.  Perhaps it is too much to ask of our patients and staff.   We remain attracted to the benefits of PNB for TKA as described in the literature, despite the increased risk of falls due to decreased motor, proprioception and pain sensations. It did not appear that addition of SNB was associated with the falls. Alterations in type, dosage, duration or concentration of injected perineural medications might decrease the risk of falls but this is yet to be elucidated. Routine use of restraints, knee immobilizers, or urinary drainage catheters in TKA patients does not appear appropriate at present. While they might diminish falls and compensate for inattentive nursing, the associated morbidity and delayed mobilization would be unattractive to patients and physicians alike.

Patient selection is important.  Use of PNB in the patient that is relatively weak in relation to his habitus or severely deconditioned as a result of arthritis, or who has neurologic or balance problems may not be appropriate. Suspicion that the patient cannot or might not follow instructions closely should preclude them from PNB.

Patient education appears crucial yet was ineffectual in these three cases.  All three patients reported that they had been instructed properly.  We have redoubled efforts at patient education, making sure we have thoroughly discussed the risk of this severe complication with each patient, to impress upon them the importance of the ambulation instructions. We ask the patients to weigh with us the risk of fall and dehiscence with PNB, to gain the benefits of reduced pain and diminished narcotic use.  We recognize the important role of specifically trained nurses in reinforcing patient education.

Our experience suggests that the most important factor in preventing this complication is an adequately staffed, trained and committed team. Noting the temporal association of the complication cluster with disbanding of the TJA service, we are reconstituting this service, to regain its perceived benefits. With a dedicated staff repeatedly working with the same physician(s), in the same rooms, with the same orders, the same type of anesthesia/analgesia, and type of operative procedure, this serious complication was absent during the first 19 months of our 22 month series.  Neither physician’s orders alone nor the use of restraints, catheters, or immobilizers are likely to equal a dedicated TJA nursing team that is vigilant and responsive to these particular patients’ subtle needs, and to the unintended consequences of new technology.


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This is a peer reviewed paper 

Please cite as: D Kevin Lester: Complete Wound Dehiscence after Peripheral Nerve Block for Knee Arthroplasty. A Nursing Issue?

J.Orthopaedics 2010;7(3)e2





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