Trial Outcomes & Findings for Saphenous Nerve Block for Foot and Ankle Surgery (NCT NCT02382744)

NCT ID: NCT02382744

Last Updated: 2018-04-02

Results Overview

Complete absence of sensation to pinprick at two different anatomic areas of the saphenous nerve at thirty minutes

• Recruitment status: COMPLETED
• Study phase: NA
• Target enrollment: 80 participants
• Primary outcome timeframe: 30 minutes post nerve block
• Results posted on: 2018-04-02

Participant Flow

Participant milestones

Measure	Ultrasound Guidance Saphenous nerve block placed using ultrasound guidance alone Ultrasound Guidance: Ultrasound guidance will be used to place a saphenous nerve block	Ultrasound Guidance and Nerve Stimulation Saphenous nerve block placed using ultrasound guidance and nerve stimulation Ultrasound guidance and nerve stimulation: Ultrasound guidance and nerve stimulation will be used to place a saphenous nerve block
Overall Study STARTED	40	40
Overall Study Allocated	40	40
Overall Study Analyzed	40	40
Overall Study COMPLETED	40	40
Overall Study NOT COMPLETED	0	0

Reasons for withdrawal

Withdrawal data not reported

Baseline Characteristics

Saphenous Nerve Block for Foot and Ankle Surgery

Baseline characteristics by cohort

Measure	Ultrasound Guidance n=40 Participants Saphenous nerve block placed using ultrasound guidance alone Ultrasound Guidance: Ultrasound guidance will be used to place a saphenous nerve block	Ultrasound Guidance and Nerve Stimulation n=40 Participants Saphenous nerve block placed using ultrasound guidance and nerve stimulation Ultrasound guidance and nerve stimulation: Ultrasound guidance and nerve stimulation will be used to place a saphenous nerve block	Total n=80 Participants Total of all reporting groups
Age, Continuous	50 years STANDARD_DEVIATION 15 • n=5 Participants	53 years STANDARD_DEVIATION 14 • n=7 Participants	52 years STANDARD_DEVIATION 15 • n=5 Participants
Sex: Female, Male Female	22 Participants n=5 Participants	29 Participants n=7 Participants	51 Participants n=5 Participants
Sex: Female, Male Male	18 Participants n=5 Participants	11 Participants n=7 Participants	29 Participants n=5 Participants
Body Mass Index	26 kg/m^2 STANDARD_DEVIATION 3 • n=5 Participants	25 kg/m^2 STANDARD_DEVIATION 4 • n=7 Participants	25 kg/m^2 STANDARD_DEVIATION 4 • n=5 Participants
American Society of Anesthesiologists (ASA) physical status I or II	37 participants n=5 Participants	33 participants n=7 Participants	70 participants n=5 Participants
American Society of Anesthesiologists (ASA) physical status III to V	3 participants n=5 Participants	7 participants n=7 Participants	10 participants n=5 Participants
Type of surgery Foot/ankle joint reconstruction/fusion/arthrodesis	15 participants n=5 Participants	24 participants n=7 Participants	39 participants n=5 Participants
Type of surgery Arthroscopy/debridement	7 participants n=5 Participants	7 participants n=7 Participants	14 participants n=5 Participants
Type of surgery Mass/hardware removal	9 participants n=5 Participants	3 participants n=7 Participants	12 participants n=5 Participants
Type of surgery Fracture fixation	5 participants n=5 Participants	3 participants n=7 Participants	8 participants n=5 Participants
Type of surgery Tendon repair/transfer	4 participants n=5 Participants	2 participants n=7 Participants	6 participants n=5 Participants
Type of surgery Amputation	0 participants n=5 Participants	1 participants n=7 Participants	1 participants n=5 Participants

PRIMARY outcome

Timeframe: 30 minutes post nerve block

Complete absence of sensation to pinprick at two different anatomic areas of the saphenous nerve at thirty minutes

Outcome measures

Measure	Ultrasound Guidance n=40 Participants Saphenous nerve block placed using ultrasound guidance alone Ultrasound Guidance: Ultrasound guidance will be used to place a saphenous nerve block	Ultrasound Guidance + Nerve Stimulation n=40 Participants Saphenous nerve block placed using ultrasound guidance and nerve stimulation Ultrasound guidance and nerve stimulation: Ultrasound guidance and nerve stimulation will be used to place a saphenous nerve block
Block Success	18 participants	22 participants

SECONDARY outcome

Timeframe: 30 minutes post nerve block

Persistent sensation in the saphenous nerve distribution at 30 minutes (i.e., absence of any evidence of blockade [decreased or complete absence of sensation] at both areas: normal sensation.

Outcome measures

Measure	Ultrasound Guidance n=40 Participants Saphenous nerve block placed using ultrasound guidance alone Ultrasound Guidance: Ultrasound guidance will be used to place a saphenous nerve block	Ultrasound Guidance + Nerve Stimulation n=40 Participants Saphenous nerve block placed using ultrasound guidance and nerve stimulation Ultrasound guidance and nerve stimulation: Ultrasound guidance and nerve stimulation will be used to place a saphenous nerve block
Block Failure Rate Normal sensation	1 participants	3 participants
Block Failure Rate Decreased or no sensation	39 participants	37 participants

SECONDARY outcome

Timeframe: 30 min

Participants with any evidence of blockade (decreased or complete absence of sensation) at the two different anatomic areas in the distribution of the saphenous nerve (2 cm proximal to the medial malleolus and 10 cm distal to the medial tibial condyle)

Outcome measures

Measure	Ultrasound Guidance n=40 Participants Saphenous nerve block placed using ultrasound guidance alone Ultrasound Guidance: Ultrasound guidance will be used to place a saphenous nerve block	Ultrasound Guidance + Nerve Stimulation n=40 Participants Saphenous nerve block placed using ultrasound guidance and nerve stimulation Ultrasound guidance and nerve stimulation: Ultrasound guidance and nerve stimulation will be used to place a saphenous nerve block
Any Evidence of Blockade (Decreased or Complete Absence of Sensation)	39 participants	37 participants

SECONDARY outcome

Timeframe: 30 minutes post nerve block

incomplete [decreased only] loss of sensation in the saphenous nerve distribution at 30 minutes at both areas of assessment

Outcome measures

Measure	Ultrasound Guidance n=40 Participants Saphenous nerve block placed using ultrasound guidance alone Ultrasound Guidance: Ultrasound guidance will be used to place a saphenous nerve block	Ultrasound Guidance + Nerve Stimulation n=40 Participants Saphenous nerve block placed using ultrasound guidance and nerve stimulation Ultrasound guidance and nerve stimulation: Ultrasound guidance and nerve stimulation will be used to place a saphenous nerve block
Incomplete Block Rate Decreased sensation	21 participants	15 participants
Incomplete Block Rate Normal or no sensation	19 participants	25 participants

SECONDARY outcome

Timeframe: 30 minutes post nerve block

Population: Participants with complete absence of sensation to pinprick at the two different anatomic areas of assessment in the distribution of the saphenous nerve (2 cm proximal to the medial malleolus and 10 cm distal to the medial condyle of the tibia)

Median (Kaplan-Meier curve "survival") time required to reach complete absence of sensation to pinprick at the two different anatomic areas of assessment in the distribution of the saphenous nerve (2 cm proximal to the medial malleolus and 10 cm distal to the medial condyle of the tibia).

Outcome measures

Measure	Ultrasound Guidance n=18 Participants Saphenous nerve block placed using ultrasound guidance alone Ultrasound Guidance: Ultrasound guidance will be used to place a saphenous nerve block	Ultrasound Guidance + Nerve Stimulation n=22 Participants Saphenous nerve block placed using ultrasound guidance and nerve stimulation Ultrasound guidance and nerve stimulation: Ultrasound guidance and nerve stimulation will be used to place a saphenous nerve block
Speed of Onset for Nerve Block (Complete Blockade)	25.0 Minutes Interval 20.0 to 30.0	17.5 Minutes Interval 15.0 to 25.0

SECONDARY outcome

Timeframe: 5 minutes

successful elicitation of any "tapping" sensation in the saphenous nerve distribution within the 5 min stimulation time limit

Outcome measures

Measure	Ultrasound Guidance n=40 Participants Saphenous nerve block placed using ultrasound guidance alone Ultrasound Guidance: Ultrasound guidance will be used to place a saphenous nerve block	Ultrasound Guidance + Nerve Stimulation Saphenous nerve block placed using ultrasound guidance and nerve stimulation Ultrasound guidance and nerve stimulation: Ultrasound guidance and nerve stimulation will be used to place a saphenous nerve block
Rate of Success of Elicitation of a Tapping Sensation	32 participants	—

SECONDARY outcome

Timeframe: 5 minutes

Population: Participants in the "Ultrasound Guidance and nerve stimulation" group with available data

the mean minimum stimulation current magnitude to elicit "tapping" sensation in the saphenous nerve distribution (cf. 3.2.3 below)

Outcome measures

Measure	Ultrasound Guidance n=26 Participants Saphenous nerve block placed using ultrasound guidance alone Ultrasound Guidance: Ultrasound guidance will be used to place a saphenous nerve block	Ultrasound Guidance + Nerve Stimulation Saphenous nerve block placed using ultrasound guidance and nerve stimulation Ultrasound guidance and nerve stimulation: Ultrasound guidance and nerve stimulation will be used to place a saphenous nerve block
Mean Minimum Stimulation Current	0.39 mA Interval 0.31 to 0.48	—

SECONDARY outcome

Timeframe: 5 minutes

Population: Participants in the "Ultrasound Guidance and nerve stimulation" group with successful stimulation and available current magnitude data

Successful elicitation of "tapping" sensation in the saphenous nerve distribution at ≤ 0.6 mA

Outcome measures

Measure	Ultrasound Guidance n=26 Participants Saphenous nerve block placed using ultrasound guidance alone Ultrasound Guidance: Ultrasound guidance will be used to place a saphenous nerve block	Ultrasound Guidance + Nerve Stimulation Saphenous nerve block placed using ultrasound guidance and nerve stimulation Ultrasound guidance and nerve stimulation: Ultrasound guidance and nerve stimulation will be used to place a saphenous nerve block
Rate of Success of Elicitation of a Tapping Sensation at < 0.6 Milliampere (mA)	25 participants	—

SECONDARY outcome

Timeframe: 10 minutes

The time required for the block to be completed (from scanning to removal of needle)

Outcome measures

Measure	Ultrasound Guidance n=40 Participants Saphenous nerve block placed using ultrasound guidance alone Ultrasound Guidance: Ultrasound guidance will be used to place a saphenous nerve block	Ultrasound Guidance + Nerve Stimulation n=40 Participants Saphenous nerve block placed using ultrasound guidance and nerve stimulation Ultrasound guidance and nerve stimulation: Ultrasound guidance and nerve stimulation will be used to place a saphenous nerve block
Time Required to Administer Block	207 s Standard Deviation 76	314 s Standard Deviation 125

SECONDARY outcome

Timeframe: 60 minutes post block completion

Any complications as a result of block placement (e.g. local anesthetic toxicity, hematoma, pain etc.)

Outcome measures

Measure	Ultrasound Guidance n=40 Participants Saphenous nerve block placed using ultrasound guidance alone Ultrasound Guidance: Ultrasound guidance will be used to place a saphenous nerve block	Ultrasound Guidance + Nerve Stimulation n=40 Participants Saphenous nerve block placed using ultrasound guidance and nerve stimulation Ultrasound guidance and nerve stimulation: Ultrasound guidance and nerve stimulation will be used to place a saphenous nerve block
Immediate Complications Local anesthetic systemic toxicity	0 participants	0 participants
Immediate Complications Hematoma	0 participants	0 participants
Immediate Complications Pain on needle manipulation	1 participants	0 participants
Immediate Complications Paresthesia	3 participants	2 participants
Immediate Complications Positive aspiration (of blood)	0 participants	1 participants
Immediate Complications Pruritus of the blocked leg in saph. n. distrib.	1 participants	0 participants
Immediate Complications Transient increase in pain in medial malleolus	1 participants	0 participants

SECONDARY outcome

Timeframe: 7 days post operative

Any complication as a results of nerve block placement (e.g. persistent paresthesia, nerve injury)

Outcome measures

Measure	Ultrasound Guidance n=40 Participants Saphenous nerve block placed using ultrasound guidance alone Ultrasound Guidance: Ultrasound guidance will be used to place a saphenous nerve block	Ultrasound Guidance + Nerve Stimulation n=40 Participants Saphenous nerve block placed using ultrasound guidance and nerve stimulation Ultrasound guidance and nerve stimulation: Ultrasound guidance and nerve stimulation will be used to place a saphenous nerve block
Delayed Complications Paresthesia	0 participants	1 participants
Delayed Complications Other	0 participants	0 participants

POST_HOC outcome

Timeframe: 30 min

Population: Participants with any evidence of sensory blockade (decreased or complete absence of sensation) in the area 2 cm proximal to the medial malleolus only

Median (Kaplan-Meier curve "survival") time required to reach any evidence of sensory blockade (decreased or complete absence of sensation) in the area 2 cm proximal to the medial malleolus only

Outcome measures

Measure	Ultrasound Guidance n=35 Participants Saphenous nerve block placed using ultrasound guidance alone Ultrasound Guidance: Ultrasound guidance will be used to place a saphenous nerve block	Ultrasound Guidance + Nerve Stimulation n=36 Participants Saphenous nerve block placed using ultrasound guidance and nerve stimulation Ultrasound guidance and nerve stimulation: Ultrasound guidance and nerve stimulation will be used to place a saphenous nerve block
Speed of Onset for Any Blockade in the Area 2 cm Proximal to the Medial Malleolus Only	30.0 Minutes Interval 20.0 to 30.0	17.5 Minutes Interval 15.0 to 25.0

POST_HOC outcome

Timeframe: 30 min

Sensation to pinprick with an 18 gauge blunt needle was assessed individually at the two different anatomic areas in the distribution of the saphenous nerve: Here, the results are reported for the area 2 cm proximal to the medial malleolus only

Outcome measures

Measure	Ultrasound Guidance n=40 Participants Saphenous nerve block placed using ultrasound guidance alone Ultrasound Guidance: Ultrasound guidance will be used to place a saphenous nerve block	Ultrasound Guidance + Nerve Stimulation n=40 Participants Saphenous nerve block placed using ultrasound guidance and nerve stimulation Ultrasound guidance and nerve stimulation: Ultrasound guidance and nerve stimulation will be used to place a saphenous nerve block
Sensory Blockade Scores by Individual Assessment Area: Medial Malleolus 2 = absent sensation	24 participants	31 participants
Sensory Blockade Scores by Individual Assessment Area: Medial Malleolus 1 = decreased sensation	14 participants	5 participants
Sensory Blockade Scores by Individual Assessment Area: Medial Malleolus 0 = normal sensation (no block)	2 participants	4 participants

POST_HOC outcome

Timeframe: 30 min

Sensation to pinprick with an 18 gauge blunt needle was assessed individually at the two different anatomic areas in the distribution of the saphenous nerve: Here, the results are reported for the area 10 cm distal to the medial tibial condyle only

Outcome measures

Measure	Ultrasound Guidance n=40 Participants Saphenous nerve block placed using ultrasound guidance alone Ultrasound Guidance: Ultrasound guidance will be used to place a saphenous nerve block	Ultrasound Guidance + Nerve Stimulation n=40 Participants Saphenous nerve block placed using ultrasound guidance and nerve stimulation Ultrasound guidance and nerve stimulation: Ultrasound guidance and nerve stimulation will be used to place a saphenous nerve block
Sensory Blockade Scores by Individual Assessment Area: Medial Tibial Condyle 2 = absent sensation	21 participants	23 participants
Sensory Blockade Scores by Individual Assessment Area: Medial Tibial Condyle 1 = decreased sensation	17 participants	14 participants
Sensory Blockade Scores by Individual Assessment Area: Medial Tibial Condyle 0 = normal sensation (no block)	2 participants	3 participants

POST_HOC outcome

Timeframe: 30 min

Percentage of block failure (persistent sensation in the saphenous nerve distribution at 30 minutes -- i.e., absence of any evidence of blockade [decreased or complete absence of sensation] at both areas: normal sensation) among participants in the Ultrasound Guidance and Nerve Stimulation group with response versus no response to nerve stimulation

Outcome measures

Measure	Ultrasound Guidance n=32 Participants Saphenous nerve block placed using ultrasound guidance alone Ultrasound Guidance: Ultrasound guidance will be used to place a saphenous nerve block	Ultrasound Guidance + Nerve Stimulation n=8 Participants Saphenous nerve block placed using ultrasound guidance and nerve stimulation Ultrasound guidance and nerve stimulation: Ultrasound guidance and nerve stimulation will be used to place a saphenous nerve block
Response Versus Lack of Response to Nerve Stimulation and Block Failure Rate Block failure (normal sensation)	0 participants	3 participants
Response Versus Lack of Response to Nerve Stimulation and Block Failure Rate No block failure (decreased or no sensation)	32 participants	5 participants

Adverse Events

Ultrasound Guidance

Serious events: 0 serious events

Other events: 3 other events

Deaths: 0 deaths

Ultrasound Guidance and Nerve Stimulation

Serious events: 0 serious events

Other events: 2 other events

Deaths: 0 deaths

Serious adverse events

Adverse event data not reported

Other adverse events

Measure	Ultrasound Guidance n=40 participants at risk Saphenous nerve block placed using ultrasound guidance alone Ultrasound Guidance: Ultrasound guidance will be used to place a saphenous nerve block	Ultrasound Guidance and Nerve Stimulation n=40 participants at risk Saphenous nerve block placed using ultrasound guidance and nerve stimulation Ultrasound guidance and nerve stimulation: Ultrasound guidance and nerve stimulation will be used to place a saphenous nerve block
Injury, poisoning and procedural complications Paresthesia (on regional nerve block needle manpulation/advancement)	7.5% 3/40 • Number of events 3 • Adverse event data were collected immediately (i.e., on the day of the intervention/postoperative day 0); on postoperative days 2 and 7, patients were contacted via telephone to enquire about the presence of any delayed complications. In case of presence of any delayed complications at the day 7 follow-up, patients were to be contacted every 7 days until symptom resolution, and further investigations and/or management were to be provided at this time. As noted above, all patients were systematically followed up via telephone to enquire about the presence of any delayed complications/adverse events.	5.0% 2/40 • Number of events 2 • Adverse event data were collected immediately (i.e., on the day of the intervention/postoperative day 0); on postoperative days 2 and 7, patients were contacted via telephone to enquire about the presence of any delayed complications. In case of presence of any delayed complications at the day 7 follow-up, patients were to be contacted every 7 days until symptom resolution, and further investigations and/or management were to be provided at this time. As noted above, all patients were systematically followed up via telephone to enquire about the presence of any delayed complications/adverse events.

Additional Information

Dr. Stephan Schwarz, Director of Research

Department of Anesthesia, St. Paul's Hospital/Providence Health Care

Phone: (604) 806-8337

Email: stephan.schwarz@ubc.ca

Results disclosure agreements

• Principal investigator is a sponsor employee
• Publication restrictions are in place