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An anatomic and clinical study of the suprascapular and axillary nerve blocks for shoulder arthroscopy
J Shoulder Elbow Surg (2011) 20, 1061-1068
www.elsevier.com/locate/ymse
An anatomic and clinical study of the suprascapular and axillary nerve blocks for shoulder arthroscopy Yong-Seok Nam, PhDa, Jae-Jung Jeong, MDb, Seung-Ho Han, MDa, Sang-Eun Park, MDb, Sang-Mook Lee, MDc, Min-Jeong Kwon, PhDd, Jong-Hun Ji, MDb,*, Kwang-Sub Kim, MDb a
Department of Anatomy, Catholic Institute for Applied Anatomy, College of Medicine, The Catholic University of Korea, Seoul, South Korea b Department of Orthopedic Surgery, Daejeon St Mary’s Hospital, College of Medicine, The Catholic University of Korea, Daejeon, South Korea c Department of Anesthesiology, College of Medicine, The Catholic University of Korea, Daejeon, South Korea d Department of Radiology, Daejeon St Mary’s Hospital, College of Medicine, The Catholic University of Korea, Daejeon, South Korea Hypothesis: The combination of suprascapular nerve block (SSNB) and axillary nerve block (ANB) has been reported to provide safe and effective analgesia for arthroscopic shoulder surgery. This study was designed to identify anatomic landmarks of the suprascapular nerve (SSN) and axillary nerve (AN) and to evaluate the effects of SSNB and ANB using the identified landmarks. Materials and Methods: This study included 52 cadaveric shoulders and 30 patients in the anatomic and clinical studies, respectively. After the exact location of the SSN and AN was identified from the cadavers, the clinical study at the end of the operation and at 8, 16, 24, 32, 40, and 48 hours postoperatively was performed in 2 groups: without both SSNB and ANB (group I) and with both SSNB and ANB (group II). Results: The SSN was located at a length of one-half (2/5-3/5, 88%) from the anterior tip of the acromion to the superior angle of the scapula and at a length of two-fifths (1/3-1/2, 100%) from the anterior tip of the acromion to the medial border of the spine. The AN was located at a length of three-fifths (2/5-4/5, 98%) from the acromial angle to the inferior insertion of the teres major muscle. The depth from the skin was 3.20 0.58 cm for the SSN and 2.07 0.45 cm for the AN. The clinical study showed that the total amount of analgesic for patient-controlled anesthesia was markedly decreased at the end of the operation and at 8 hours postoperatively in group II compared with group I. Conclusions: The SSNB and ANB were considered to provide safe and effective analgesia in terms of early postoperative pain in arthroscopic shoulder surgery. Level of evidence: Level II, Prospective Cohort Study, Treatment Study-Basic Science, Anatomic Study, Cadaver Dissection. Ó 2011 Journal of Shoulder and Elbow Surgery Board of Trustees. Keywords: Suprascapular nerve block; axillary nerve block; shoulder arthroscopy
The Institutional Review Board of The Catholic University of Korea approved this study (DC11RISI0036). *Reprint requests: Jong-Hun Ji, MD, Department of Orthopedic Surgery, Daejeon St Mary’s Hospital, The Catholic University of
Korea, 520-2, Dae-Heung Dong, Joong-gu, Daejeon 302-803, South Korea. E-mail address: [email protected] (J.-H. Ji).
1058-2746/$ - see front matter Ó 2011 Journal of Shoulder and Elbow Surgery Board of Trustees. doi:10.1016/j.jse.2011.04.022
1062 Surgical procedures on the shoulder joint are very painful interventions in orthopedic practice, and major shoulder surgeries are associated with severe postoperative pain during the 48 hours after the operation.23,27 Arthroscopic shoulder surgery has especially been associated with severe intraoperative and postoperative pain that is serious enough to interfere with initial recovery and rehabilitation in 45% of cases.16 A variety of approaches including opiate therapy, intraarticular anesthetic injections, and patient-controlled anesthesia (PCA) have been used to relieve the postoperative pain after outpatient shoulder surgery. Recently, regional nerve blocks such as interscalene brachial plexus block, suprascapular nerve block (SSNB), and axillary nerve block (ANB) have been suggested to reduce both intraoperative and postoperative pain for arthroscopic shoulder surgery. Particularly, the combination of SSNB and ANB has been reported to provide safe and effective intraoperative and postoperative analgesia for certain arthroscopic surgical procedures of the shoulder. These blocks could be considered especially in older patients with pulmonary comorbidity such as chronic obstructive lung disease, restrictive lung disease, prior pneumonectomy on the opposite side, and so on. For the regional nerve blocks, it is of utmost importance to inject the local anesthetic as close to the nerve as possible: the landmarks should be precisely identified to ensure that all sections of the nerve are exposed to the anesthesia. However, the consistency of SSNB and ANB has not been confirmed because of the absence of accurate criteria for the anatomic landmarks of the suprascapular nerve (SSN) and axillary nerve (AN). This anatomic study aimed to determine the anatomic landmarks of the SSN and AN and to evaluate the effects of the combination of SSNB and ANB using the identified landmarks.
Materials and methods Anatomic study A total of 52 shoulders from 26 Korean cadavers (22 men and 4 women; age range, 55-88 years) were used for the study (Table I). Fifty shoulders were dissected, and two were used for the verification of results. To measure the location of the SSN and AN, 50 shoulders were dissected first. After the trapezius muscle and the supraspinatus muscle were removed, all branches of the SSN were clearly identified (Fig. 1, A). The AN was identified by exposing the latissimus dorsi muscle and the teres major muscle after elevating the skin and superficial fascia (Fig. 1, B). The distance and depth of the SSN and AN were measured with a digital caliper (Mitutoyo, Kawasaki, Japan). To clarify the course of the SSN and AN, the relationship of the nerves with constant anatomic landmarks and structures was examined: the anterior tip of the acromion, the superior angle of the scapula, the medial border of the spine, the acromial angle, and the inferior insertion of the teres major muscle. For the SSN, the distances from the anterior tip of
Y.-S. Nam et al. the acromion to the superior angle of the scapula and from the anterior tip of the acromion to the medial border of the spine were measured. For the AN, the distance from the acromial angle to the inferior insertion of the teres major muscle was measured. In addition, the depth from the skin to the SSN and AN was measured. The SSN passes posterolaterally from its origin, through the suprascapular foramen, to reach the posterior scapular region, where it lies in the plane between bone and muscle. The AN exits the axilla by passing through the quadrangular space in the posterior wall of the axilla, and it enters the scapular region. The inferior boundary of the quadrangular space is formed by the superior margin of the teres major muscle. The inferolateral aspect of the posterior wall of the axilla is formed from the terminal part of the teres major muscle and tendon of the latissimus dorsi muscle. These 2 structures lie under the posterior axillary fold, which marks the posterior inferior border of the axilla. As a consequence, inferior insertion of the teres major muscle defines the inferior limit of the axilla laterally.9 To verify that the identified location of the SSN and AN was accurate enough to be used as the landmark, 2 shoulders were dissected and a needle tip was positioned at the identified location. The needle tip was confirmed to be very close to the SSN and AN.
Clinical study In total, 30 patients (12 men and 18 women) who underwent arthroscopic rotator cuff repair between September 2008 and February 2009, performed by a single surgeon, participated in the clinical study. The mean age of the patients was 58.27 10.08 years. The patients were divided into 2 equal groups: group I underwent surgery without SSNB and ANB and group II had both SSNB and ANB. For the patients in group I, general anesthesia was performed with PCA. For the patients in group II, the locations of the SSN and AN were marked on the skin based on the landmarks from the anatomic study, and a mixture of local anesthetics (10 mL of 2% mepivacaine and 20 mL of 0.75% ropivacaine ) was injected in the marked locations of the SSN and AN at a volume of 15 mL each. In the sitting position, we used a bluntbeveled, 25-gauge block needle. The needle tip was inserted perpendicular to the skin. When we inserted the needle tip, the patients could feel the paresthesia of that area and then we could verify the proper location of these blocks during needle passage. We then administered general anesthesia with PCA. After we excluded patients whose PCA device was removed because of early discharge, 30 patients (12 men and 18 women) were finally selected for the clinical study. After the administration of each anesthetic, elbow joint or finger mobility confirmed the blockage of the motor nerves through the skin sensory nerves. Information regarding age and gender in each group is shown in Table I. In the recovery room, the degree of sedation of the patients was measured with a modified Ramsay score1 to evaluate respiratory distress, paralysis, movement, and blockage of the sensory nerve. For PCA, 80 mL of saline solution was mixed with 0.5 mg of fentanyl, 180 mg of ketorolac, and 12 mg of ondansetron. This mixture was then added to a pain management system (Provider; Abbott Laboratories, North Chicago, IL, USA). The amount of persistent infusion, the dose of initial maintenance, the patient selection of a 1-time dose (bolus), and the limited time for ondemand analgesics were set at 0.02 mg/kg per hour, 0.1 mL/kg, 2.0 mL, and 5 minutes, respectively. Patients requesting treatment
Suprascapular and axillary nerve blocks Table I
1063
Characteristics of cadavers and patients in both study groups Mean SD
Cadaver characteristics (anatomic study) Age (y) 71.76 8.18 Patient characteristics (clinical study) Age (mean SD) (y) Gender (male/female)
Minimum-maximum
Group I
Group II
59.07 10.10 7/8
57.47 10.35 8/7
55-88
residents, blinded to which procedure was performed on each patient. The VAS score and the frequency of complications were measured using a 10 cm scale (where 0 indicates no pain and 10 is the most severe pain) and a 4-point scale (0, asymptomatic; 1, mild [there was subjective nausea and recovery was made without drug treatment]; 2, moderate [there was subjective nausea and recovery was made with the administration of antiemetics]; and 3, severe [there were subjective symptoms such as nausea or vomiting and gastric contents were released]), respectively. The highest score was selected for the analysis among the scores recorded at each time.
Statistical analysis SPSS software for Windows (version 16.0; SPSS, Chicago, IL, USA) was used for the statistical analysis. The independentsamples t test and 1-way analysis of variance were performed for patient characteristics, VAS score, and total amount of analgesic for PCA. The frequency of complications was assessed with the c2 test. Statistical significance was defined as P .05.
Results Anatomic study The locations of the SSN and AN were identified in the cadavers. On the basis of palpable skin markers, the fraction between skin markers and the distance from each nerve were measured and calculated.
Location of SSN
Figure 1 (A) Dissection of SSN. ATA, Anterior tip of acromion; SA, superior angle of scapula; MBS, medial border of spine. (B) Dissection of AN. IS, Infraspinatus muscle; D, deltoid muscle; Tm, teres minor muscle; AA, acromial angle.
for severe nausea after surgery were given 10 mg of metoclopramide intravenously. The visual analog scale (VAS) score, the total amount of analgesic for PCA, and the frequency of complications such as nausea and vomiting at the end of the operation and at 8, 16, 24, 32, 40, and 48 hours postoperatively were measured by orthopedic surgery
The distance between the anterior tip of the acromion and the superior angle of the scapula was 10.66 0.85 cm. The SSN was located 5.74 0.60 cm to the anterior tip of the acromion. The distance between the anterior tip of the acromion and the medial border of the spine was 13.43 0.94 cm. The SSN was located 5.47 0.57 cm to the anterior tip of the acromion. The depth of the SSN was 3.20 0.58 cm from the surface of the skin. The SSN was located at a length of one-half (2/5-3/5, 88%) from the anterior tip of the acromion to the superior angle of the scapula and at a length of two-fifths (1/3-1/2, 100%) from the anterior tip of the acromion to the medial border of the spine. The location of the SSN is shown in Table II and Figures 2 and 3.
1064 Table II
Y.-S. Nam et al. Location of SSN Mean SD (cm)
Minimum-maximum (cm)
ATA-SA 10.66 0.85 8.30-12.62 ATA-SSN 5.74 0.60 4.36-6.80 ATA-SSN/ATA-SA 0.54 0.06 (1/2) 0.39-0.68 (2/5-3/5) ATA-MBS 13.43 0.94 11.13-15.22 ATA-SSN 5.47 0.57 4.46-6.72 ATA-SSN/ATA-MBS 0.41 0.03 (2/5) 0.33-0.48 (1/3-1/2) Depth of SSN 3.20 0.58 1.84-4.49 ATA, anterior tip of acromion; SA, superior angle of scapula; MBS, medial border of spine.
Figure 3 Injection point of SSN. The SSN was located at a length of one-half from ATA to SA and at a length of two-fifths from ATA to MBS. ATA, Anterior tip of acromion; SA, superior angle of scapula; MBS, medial border of spine.
Table III
Location of AN
AAeinferior insertion of TM AA-AN AA-AN/AAeinferior insertion of TM Depth of AN Width of TM
Mean SD (cm)
Minimum-maximum (cm)
8.25 1.08
6.02-10.15
4.71 0.85 3.25-8.44 0.57 0.08 (3/5) 0.44-0.89 (2/5-4/5) 2.07 0.45 2.98 0.44
1.32-3.60 1.82-4.26
AA, acromial angle; TM, teres major muscle.
To verify that the identified location of the SSN and AN was accurate enough to be used as the landmark, 2 shoulders were dissected and a needle tip was positioned at the identified location. We confirmed the needle tip to be very close to the SSN and AN (Fig. 6). Figure 2 Location of SSN. (A) The distance between ATA and SA on SSN. (B) The distance between ATA and MBS on SSN. ATA, Anterior tip of acromion; SA, superior angle of scapula; MBS, medial border of spine.
Clinical study The outcomes in the clinical study were compared in the 2 groups. Analysis on the age and gender of patients showed no significant differences.
Location of AN
VAS score
The distance between the acromial angle and the inferior insertion of the teres major muscle was 8.25 1.08 cm. The AN was located 4.71 0.85 cm to the acromial angle. The depth of the AN was 2.07 0.45 cm from the surface of the skin. The width of insertion in the teres major muscle was 2.98 0.44 cm. The AN was located at a length of three-fifths (2/5-4/5, 98%) from the acromial angle to the inferior insertion of the teres major muscle. The location of the AN is shown in Table III and Figures 4 and 5.
At the end of the operation, the VAS score was lower in group II than in group I (Table IV, Fig. 7). In group I, the VAS score changed over time: 7.13 at 0 hours, 5.20 at 8 hours, 4.00 at 16 hours, 4.00 at 24 hours, 3.71 at 32 hours, 3.42 at 40 hours, and 3.09 at 48 hours. This meant that pain was markedly decreased from the severe state in the early stage to the mild state as time went on. In group II, the VAS score also changed over time: 5.00 at 0 hours, 5.27 at 8 hours, 5.47 at 16 hours, 4.92 at 24 hours, 4.67 at 32 hours,
Suprascapular and axillary nerve blocks
Figure 4 Location of AN. TM, Teres major muscle; AA, acromial angle.
4.25 at 40 hours, and 3.70 at 48 hours. However, the VAS score was not significantly increased until 16 hours. At 16 hours, the VAS scores in group I (4.00) and group II (5.47) were significantly different (P ¼ .021).
Total amount of analgesic for PCA At 8 hours after the operation, the total amount of analgesic for PCA was significantly less in group II than in group I (P ¼ .036) (Table IV, Fig. 8).
Frequency of complication such as nausea and vomiting At all time points, there was no significant difference between the 2 groups in the frequency of complications such as nausea and vomiting (Table IV). However, the frequency was lower in group II at all times.
Discussion Shoulder surgery is often associated with severe postoperative pain. More than 50% of patients have inadequate pain relief after surgical procedures.11 During arthroscopic shoulder surgery, the severity of postoperative pain has been reported to be greater compared with arthroscopic knee joint surgery. Boss et al6 reported that severe
1065
Figure 5 Injection point of AN. The AN was located at a length of three-fifths from AA to the inferior insertion of the teres major muscle. TM, Teres major muscle; AA, acromial angle.
postoperative pain, particularly within the first 48 hours postoperatively, is frequently observed after rotator cuff repair. The glenohumeral joint is innervated mainly from the posterior cord of the brachial plexus.9 The capsule is supplied by the SSN (posterior and superior parts), AN (anteroinferior), and lateral pectoral nerve (anterosuperior).9 During surgery, these nerves are injured, and this exerts pressure on the nociceptors. Moreover, due to intraoperative damage, reflexive muscle contraction is induced in many muscles with connections between the vertebral spines and upper extremities that are adjacent to these joints. This further aggravates the postoperative shoulder pain. In the areas adjacent to the shoulder joint, A-d afferent fibers as well as C afferent fibers are abundant.4 Among these fibers, the A-d afferent fibers have almost no analgesic effects from opioids.18 Approximately 30% to 70% of patients have severe postoperative pain.16 For early rehabilitation exercise, postoperative pain control is essential after surgery.5 Several methods for controlling pain exist, including opiate therapy, PCA, intra-articular anesthesia, interscalene block, and SSNB. Intravenous PCA is commonly used, but satisfactory analgesic effects cannot be achieved in some cases because of increases in the occurrence of nausea, vomiting, or sedation. In addition, continuous local analgesic infusion is not very effective for controlling pain and
1066
Figure 6 Injection of SSN (A) and AN (B) for results. AA, Acromial angle.
has several associated complications.12,21 The standard of care for shoulder arthroscopy at many institutions is interscalene nerve block. Interscalene block is very effective for arthroscopic shoulder surgery,1 for which various methods have been introduced.3,10,13,14,20 The most powerful analgesic effects have been reported with continuous interscalene block via a catheter after open shoulder surgery. The success rate of this block is very high. However, these methods produce side effects in 5% to 10% of cases. Rebound pain as well as incomplete effects, such as partial block or failure of the nerve block, have been reported to occur.1,2,7,28 Furthermore, most patients who receive rotator cuff surgery are older, so we should consider the safety of the interscalene block in this age group with pulmonary comorbidity. All the successful interscalene blocks could affect the phrenic nerve, and this might lead to respiratory distress or diaphragmatic paresis.24 Recently, more attention has been paid to why one would ever consider SSNB/ ANB versus an interscalene block. SSNB has been reported
Y.-S. Nam et al. to be effective, and several surgical techniques have been reported.3,13,15 It has also been reported to reduce the amount of postoperative analgesics used and has been associated with early discharge.3 Anatomic studies of the SSN and AN have been performed. According to Vorster et al,26 there are articular branches of the SSN. Uz et al25 reported that the AN also has articular branches. Performing a block of these nerve branches would be effective for controlling postoperative pain. Methods used for SSNB and ANB include approximating the nerve under electromyographic guidance14 or others, such as fluoroscopy, ultrasound, or computed tomography.20,22 Efforts are made to block the nerve accurately, and a variety of criteria and surgical techniques have been proposed. However, given the absence of accurate criteria for the anatomic landmarks, for each nerve block, the technical consistency of the procedures has been limited. Price19 and Checcucci et al8 have reported simultaneous SSNB and ANB. For SSNB, Barber3 used the base point at the junction of the middle and distal third of the spine or the Neviaser portal. Checcucci et al used the base point 2 cm medial to the medial acromion border and 2 cm cranial to the margin of the superior scapular spine. However, application of these techniques can vary with the size of the patient. In the technique reported by Matsumoto et al,15 there would be a high frequency of average error due to the obliquity of needle tip placement. In our cadaveric study, the SSN was located at a length one-half (2/5-3/5, 88%) from the anterior tip of the acromion to the superior angle of the scapula and two-fifths (1/3-1/2, 100%) from the anterior tip of the acromion to the medial border of the spine. In addition, the AN was located at a length three-fifths (2/5-4/5, 98%) from the acromial angle to the inferior insertion of the teres major muscle. The accuracy was very high, and our clinical study was performed using this technique. We sought to clarify the course of the SSN and AN and to determine the relationship between the nerves and the following anatomic landmarks and structures: the anterior tip of the acromion, the superior angle of the scapula, the medial border of the spine, the acromial angle, and the inferior insertion of the teres major muscle. The landmark of the superior angle of the scapula for the SSN was easy to identify when the scapula was elevated and rotated upward, whereas the landmark of the inferior insertion of the teres major muscle for the AN was easy to identify when the humerus was in an abduction position. All the parameters were measured in anatomic position after clearly identifying the landmark. SSNB is effective in blocking the sensory nerves that innervate the shoulder joint and adjacent tissue. However, it takes approximately 10 hours (mean time to first significant pain, 594 minutes) for symptoms to reappear.20 This time difference delays the occurrence of postoperative pain and reduces the intensity of the postoperative pain after an interscalene block. Contrary to the study reported by Neal et al,17 in this study, the analgesic efficacy of SSNB and
Suprascapular and axillary nerve blocks
1067
Table IV Results of clinical study including VAS score, total amount of analgesic for PCA, and frequency of complications such as nausea and vomiting according to time after operation 0h
8h
16 h
VAS score Group I 7.13 1.60 5.20 2.01 4.00 2.00 Group II 5.00 2.39 5.27 1.83 5.47 1.13 Total amount of analgesic for PCA (unit; mL) Group I 26.75 13.02 37.01 15.61 Group II 18.27 7.32 30.60 12.88 Frequency of complications such as nausea and vomiting Group I 4 5 7 Group II 3 4 4
Figure 7
VAS score.
ANB as an adjunct to PCA in patients undergoing arthroscopic rotator cuff surgery was assessed. In this study, the VAS score at the end of the operation was lower in group II than in group I. Group I had better pain control during the early stage of recovery but poor pain control at 8 hours after the operation. At 16 hours postoperatively, the VAS scores in group I and group II were significantly different (P ¼ .021). This might be explained by the plasma level of analgesics being maintained at a relatively lower concentration, because of the low PCA demand but also because of possible rebound pain because the nerve block was no longer effective. Compared with group I, a similar VAS score and decreased use of analgesics were observed in group II at 8 hours after the operation. In addition, the frequency of complications such as nausea and vomiting was lower in group II than group I, even though the difference was not significant. The results of this study confirm that group II had reduced use of PCA for postoperative pain. Eight hours after surgery, group II showed a significantly lower use of PCA compared with group I (P ¼ .036). This finding extended to 16 hours after surgery; however, at this time, there was no significant difference between the 2 groups. These results suggest that pain control was easier to achieve in the recovery room and that it was more difficult to obtain 8 hours after the procedure in group II. The
24 h
32 h
40 h
48 h
4.00 1.88 4.92 1.04
3.71 1.38 4.67 1.61
3.42 1.62 4.25 1.49
3.09 1.22 3.70 1.06
48.79 17.24 46.00 17.73
59.82 18.24 55.83 20.02
68.21 18.38 67.33 23.27
79.09 20.24 74.60 25.90
4 3
1 2
2 0
4 0
Figure 8
Total amount of analgesic for PCA (unit; mL).
combined SSNB and ANB had excellent analgesic effects in the recovery room and during the early stage of recovery compared with the control group. In our study, the described selective block of the SSN and AN has several advantages. Although the SSNB and ANB could not eliminate postoperative pain altogether because of the other branches of the brachial plexus and the lateral pectoral nerve, this combination could control the immediate postoperative pain. During the initial several hours, it also reduced the occurrence of severe pain and the total amount of PCA used. Compared with the interscalene block, this selective block may be needed in older patients with lung problems and it may also be used by surgeons in cases when an interscalene block is not performed by the anesthesiologist. The limitations of this study include the following: First, a small number of patients were enrolled in the clinical study, and it is difficult to conclude whether this block is superior to the interscalene block. However, we still continue to study this combined block in patients with lung problems and find its effectiveness. Further study will be needed with more patients. Second, PCA was used simultaneously as a baseline in both groups, which likely biased the PCA effects of the nerve block. The effects of isolated PCA use on postoperative pain control should be
1068 considered in a future study. Third, it is difficult to palpate the inferior insertion of the teres major muscle on the skin compared with the cadavers. Because this muscle is pretty deep and difficult to palpate ‘‘in vivo,’’ especially on the humeral side, we also measured the length in centimeters from the postero-external angle of the acromion directed distally and the AN was located 4.71 0.85 cm to the acromial angle. This measure could be used in difficult cases to palpate the inferior border of the teres major muscle in patients.
Y.-S. Nam et al.
9. 10.
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Conclusions The results of this study identified new landmarks that could be used for the SSNB and ANB. These nerve blocks were very effective for the management of early postoperative pain and also were associated with reduced use of postoperative analgesia. These results might aid in a more rapid recovery and earlier rehabilitation after surgery.
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Disclaimer 18.
The authors have received a National Research Foundation of Korea grant funded by the South Korean Government (314-2008-1-E00002).
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27. 28.
block: an evaluation of the first results. Arthroscopy 2008;24:689-96. doi:10.1016/j.arthro.2008.01.019 Drake RL, Vogl AW, Mitchell AWM. Upper limb. In: Gray’s anatomy for students. Philadelphia: Churchill Livingston Elsevier; 2009. p. 665-720. Feigl GC, Anderhuber F, Dorn C, Pipam W, Rosmarin W, Likar R. Modified lateral block of the suprascapular nerve: a safe approach and how much to inject? A morphological study. Reg Anesth Pain Med 2007;32:488-94. doi:10.1016/j.rapm.2007.06.394 Filos KS, Lehmann KA. Current concepts and practice in postoperative pain management: need for a change? Eur Surg Res 1999; 31:97-107. Henn P, Steuer K, Fischer A, Fischer M. Effectiveness of morphine by periarticular injections after shoulder arthroscopy [in German]. Anaesthesist 2000;49:721-4. Jerosch J, Saad M, Greig M, Filler T. Suprascapular nerve block as a method of preemptive pain control in shoulder surgery. Knee Surg Sports Traumatol Arthrosc 2008;16:602-7. doi:10.1007/s00167008-0520-3 Karatas¸ GK, Meray J. Suprascapular nerve block for pain relief in adhesive capsulitis: comparison of 2 different techniques. Arch Phys Med Rehabil 2002;83:593-7. doi:10.1053/apmr.2002.32472 Matsumoto D, Suenaga N, Oizumi N, Hisada Y, Minami A. A new nerve block procedure for the suprascapular nerve based on a cadaveric study. J Shoulder Elbow Surg 2009;18:607-11. doi:10.1016/j.jse. 2009.01.005 Moote CA. The prevention of postoperative pain. Can J Anesth 1994; 41:527-33. Neal JM, McDonald SB, Larkin KL, Polissar NL. Suprascapular nerve block prolongs analgesia after nonarthroscopic shoulder surgery but does not improve outcome. Anesth Analg 2003;96:982-6. doi:10.1213/ 01.ANE.0000052380.69541.D4 Pirec V, Laurito CE, Lu Y, Yeomans DC. The combined effects of N-type calcium channel blockers and morphine on A delta versus C fiber mediated nociception. Anesth Analg 2001;92:239-43. Price DJ. The shoulder block: a new alternative to interscalene brachial plexus blockade for the control of postoperative shoulder pain. Anaesth Intensive Care 2007;35:575-81. Schneider-Kolsky ME, Pike J, Connell DA. CT-guided suprascapular nerve blocks: a pilot study. Skeletal Radiol 2004;33:277-82. doi:10. 1007/s00256-003-0733-y Scoggin JF, Mayfield G, Awaya DJ, Pi M, Prentiss J, Takahashi J. Subacromial and intra-articular morphine versus bupivacaine after shoulder arthroscopy. Arthroscopy 2002;18:464-8. doi:10.1053/jars. 2002.29895 Shah RV, Racz GB. Pulsed mode radiofrequency lesioning of the suprascapular nerve for the treatment of chronic shoulder pain. Pain Physician 2003;6:503-6. Tuominen M, Pitknen M, Rosenberg PH. Postoperative pain relief and bupivacaine plasma levels during continuous interscalene brachial plexus block. Acta Anaesth Scand 1987;31:276-8. Urmey WF, McDonald M. Hemidiaphragmatic paresis during interscalene brachial plexus block: effects on pulmonary function and chest wall mechanics. Anesth Analg 1992;74:352-7. Uz A, Apaydin N, Bozkurt M, Elhan A. The anatomic branch pattern of the axillary nerve. J Shoulder Elbow Surg 2007;16:240-4. doi:10. 1016/j.jse.2006.05.003 Vorster W, Lange CP, Bri€et RJ, Labuschagne BC, du Toit DF, Muller CJ, et al. The sensory branch distribution of the suprascapular nerve: an anatomic study. J Shoulder Elbow Surg 2008;17:500-2. doi: 10.1016/j.jse.2007.10.008 Wilson AT, Nicholson E, Burton L, Wild C. Analgesia for day-case shoulder surgery. Br J Anaesth 2004;92:414-5. doi:10.1093/bja/aeh071 Wurm WH, Concepcion M, Sternlicht A, Carabuena JM, Robelen G, Goudas LC, et al. Preoperative interscalene block for elective shoulder surgery: loss of benefit over early postoperative block after patient discharge to home. Anesth Analg 2003;97:1620-6. doi:10.1213/01. ANE.0000090320.46129.BE
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An anatomic and clinical study of the suprascapular and axillary nerve blocks for shoulder arthroscopy Yong-Seok Nam, PhDa, Jae-Jung Jeong, MDb, Seung-Ho Han, MDa, Sang-Eun Park, MDb, Sang-Mook Lee, MDc, Min-Jeong Kwon, PhDd, Jong-Hun Ji, MDb,*, Kwang-Sub Kim, MDb a
Department of Anatomy, Catholic Institute for Applied Anatomy, College of Medicine, The Catholic University of Korea, Seoul, South Korea b Department of Orthopedic Surgery, Daejeon St Mary’s Hospital, College of Medicine, The Catholic University of Korea, Daejeon, South Korea c Department of Anesthesiology, College of Medicine, The Catholic University of Korea, Daejeon, South Korea d Department of Radiology, Daejeon St Mary’s Hospital, College of Medicine, The Catholic University of Korea, Daejeon, South Korea Hypothesis: The combination of suprascapular nerve block (SSNB) and axillary nerve block (ANB) has been reported to provide safe and effective analgesia for arthroscopic shoulder surgery. This study was designed to identify anatomic landmarks of the suprascapular nerve (SSN) and axillary nerve (AN) and to evaluate the effects of SSNB and ANB using the identified landmarks. Materials and Methods: This study included 52 cadaveric shoulders and 30 patients in the anatomic and clinical studies, respectively. After the exact location of the SSN and AN was identified from the cadavers, the clinical study at the end of the operation and at 8, 16, 24, 32, 40, and 48 hours postoperatively was performed in 2 groups: without both SSNB and ANB (group I) and with both SSNB and ANB (group II). Results: The SSN was located at a length of one-half (2/5-3/5, 88%) from the anterior tip of the acromion to the superior angle of the scapula and at a length of two-fifths (1/3-1/2, 100%) from the anterior tip of the acromion to the medial border of the spine. The AN was located at a length of three-fifths (2/5-4/5, 98%) from the acromial angle to the inferior insertion of the teres major muscle. The depth from the skin was 3.20 0.58 cm for the SSN and 2.07 0.45 cm for the AN. The clinical study showed that the total amount of analgesic for patient-controlled anesthesia was markedly decreased at the end of the operation and at 8 hours postoperatively in group II compared with group I. Conclusions: The SSNB and ANB were considered to provide safe and effective analgesia in terms of early postoperative pain in arthroscopic shoulder surgery. Level of evidence: Level II, Prospective Cohort Study, Treatment Study-Basic Science, Anatomic Study, Cadaver Dissection. Ó 2011 Journal of Shoulder and Elbow Surgery Board of Trustees. Keywords: Suprascapular nerve block; axillary nerve block; shoulder arthroscopy
The Institutional Review Board of The Catholic University of Korea approved this study (DC11RISI0036). *Reprint requests: Jong-Hun Ji, MD, Department of Orthopedic Surgery, Daejeon St Mary’s Hospital, The Catholic University of
Korea, 520-2, Dae-Heung Dong, Joong-gu, Daejeon 302-803, South Korea. E-mail address: [email protected] (J.-H. Ji).
1058-2746/$ - see front matter Ó 2011 Journal of Shoulder and Elbow Surgery Board of Trustees. doi:10.1016/j.jse.2011.04.022
1062 Surgical procedures on the shoulder joint are very painful interventions in orthopedic practice, and major shoulder surgeries are associated with severe postoperative pain during the 48 hours after the operation.23,27 Arthroscopic shoulder surgery has especially been associated with severe intraoperative and postoperative pain that is serious enough to interfere with initial recovery and rehabilitation in 45% of cases.16 A variety of approaches including opiate therapy, intraarticular anesthetic injections, and patient-controlled anesthesia (PCA) have been used to relieve the postoperative pain after outpatient shoulder surgery. Recently, regional nerve blocks such as interscalene brachial plexus block, suprascapular nerve block (SSNB), and axillary nerve block (ANB) have been suggested to reduce both intraoperative and postoperative pain for arthroscopic shoulder surgery. Particularly, the combination of SSNB and ANB has been reported to provide safe and effective intraoperative and postoperative analgesia for certain arthroscopic surgical procedures of the shoulder. These blocks could be considered especially in older patients with pulmonary comorbidity such as chronic obstructive lung disease, restrictive lung disease, prior pneumonectomy on the opposite side, and so on. For the regional nerve blocks, it is of utmost importance to inject the local anesthetic as close to the nerve as possible: the landmarks should be precisely identified to ensure that all sections of the nerve are exposed to the anesthesia. However, the consistency of SSNB and ANB has not been confirmed because of the absence of accurate criteria for the anatomic landmarks of the suprascapular nerve (SSN) and axillary nerve (AN). This anatomic study aimed to determine the anatomic landmarks of the SSN and AN and to evaluate the effects of the combination of SSNB and ANB using the identified landmarks.
Materials and methods Anatomic study A total of 52 shoulders from 26 Korean cadavers (22 men and 4 women; age range, 55-88 years) were used for the study (Table I). Fifty shoulders were dissected, and two were used for the verification of results. To measure the location of the SSN and AN, 50 shoulders were dissected first. After the trapezius muscle and the supraspinatus muscle were removed, all branches of the SSN were clearly identified (Fig. 1, A). The AN was identified by exposing the latissimus dorsi muscle and the teres major muscle after elevating the skin and superficial fascia (Fig. 1, B). The distance and depth of the SSN and AN were measured with a digital caliper (Mitutoyo, Kawasaki, Japan). To clarify the course of the SSN and AN, the relationship of the nerves with constant anatomic landmarks and structures was examined: the anterior tip of the acromion, the superior angle of the scapula, the medial border of the spine, the acromial angle, and the inferior insertion of the teres major muscle. For the SSN, the distances from the anterior tip of
Y.-S. Nam et al. the acromion to the superior angle of the scapula and from the anterior tip of the acromion to the medial border of the spine were measured. For the AN, the distance from the acromial angle to the inferior insertion of the teres major muscle was measured. In addition, the depth from the skin to the SSN and AN was measured. The SSN passes posterolaterally from its origin, through the suprascapular foramen, to reach the posterior scapular region, where it lies in the plane between bone and muscle. The AN exits the axilla by passing through the quadrangular space in the posterior wall of the axilla, and it enters the scapular region. The inferior boundary of the quadrangular space is formed by the superior margin of the teres major muscle. The inferolateral aspect of the posterior wall of the axilla is formed from the terminal part of the teres major muscle and tendon of the latissimus dorsi muscle. These 2 structures lie under the posterior axillary fold, which marks the posterior inferior border of the axilla. As a consequence, inferior insertion of the teres major muscle defines the inferior limit of the axilla laterally.9 To verify that the identified location of the SSN and AN was accurate enough to be used as the landmark, 2 shoulders were dissected and a needle tip was positioned at the identified location. The needle tip was confirmed to be very close to the SSN and AN.
Clinical study In total, 30 patients (12 men and 18 women) who underwent arthroscopic rotator cuff repair between September 2008 and February 2009, performed by a single surgeon, participated in the clinical study. The mean age of the patients was 58.27 10.08 years. The patients were divided into 2 equal groups: group I underwent surgery without SSNB and ANB and group II had both SSNB and ANB. For the patients in group I, general anesthesia was performed with PCA. For the patients in group II, the locations of the SSN and AN were marked on the skin based on the landmarks from the anatomic study, and a mixture of local anesthetics (10 mL of 2% mepivacaine and 20 mL of 0.75% ropivacaine ) was injected in the marked locations of the SSN and AN at a volume of 15 mL each. In the sitting position, we used a bluntbeveled, 25-gauge block needle. The needle tip was inserted perpendicular to the skin. When we inserted the needle tip, the patients could feel the paresthesia of that area and then we could verify the proper location of these blocks during needle passage. We then administered general anesthesia with PCA. After we excluded patients whose PCA device was removed because of early discharge, 30 patients (12 men and 18 women) were finally selected for the clinical study. After the administration of each anesthetic, elbow joint or finger mobility confirmed the blockage of the motor nerves through the skin sensory nerves. Information regarding age and gender in each group is shown in Table I. In the recovery room, the degree of sedation of the patients was measured with a modified Ramsay score1 to evaluate respiratory distress, paralysis, movement, and blockage of the sensory nerve. For PCA, 80 mL of saline solution was mixed with 0.5 mg of fentanyl, 180 mg of ketorolac, and 12 mg of ondansetron. This mixture was then added to a pain management system (Provider; Abbott Laboratories, North Chicago, IL, USA). The amount of persistent infusion, the dose of initial maintenance, the patient selection of a 1-time dose (bolus), and the limited time for ondemand analgesics were set at 0.02 mg/kg per hour, 0.1 mL/kg, 2.0 mL, and 5 minutes, respectively. Patients requesting treatment
Suprascapular and axillary nerve blocks Table I
1063
Characteristics of cadavers and patients in both study groups Mean SD
Cadaver characteristics (anatomic study) Age (y) 71.76 8.18 Patient characteristics (clinical study) Age (mean SD) (y) Gender (male/female)
Minimum-maximum
Group I
Group II
59.07 10.10 7/8
57.47 10.35 8/7
55-88
residents, blinded to which procedure was performed on each patient. The VAS score and the frequency of complications were measured using a 10 cm scale (where 0 indicates no pain and 10 is the most severe pain) and a 4-point scale (0, asymptomatic; 1, mild [there was subjective nausea and recovery was made without drug treatment]; 2, moderate [there was subjective nausea and recovery was made with the administration of antiemetics]; and 3, severe [there were subjective symptoms such as nausea or vomiting and gastric contents were released]), respectively. The highest score was selected for the analysis among the scores recorded at each time.
Statistical analysis SPSS software for Windows (version 16.0; SPSS, Chicago, IL, USA) was used for the statistical analysis. The independentsamples t test and 1-way analysis of variance were performed for patient characteristics, VAS score, and total amount of analgesic for PCA. The frequency of complications was assessed with the c2 test. Statistical significance was defined as P .05.
Results Anatomic study The locations of the SSN and AN were identified in the cadavers. On the basis of palpable skin markers, the fraction between skin markers and the distance from each nerve were measured and calculated.
Location of SSN
Figure 1 (A) Dissection of SSN. ATA, Anterior tip of acromion; SA, superior angle of scapula; MBS, medial border of spine. (B) Dissection of AN. IS, Infraspinatus muscle; D, deltoid muscle; Tm, teres minor muscle; AA, acromial angle.
for severe nausea after surgery were given 10 mg of metoclopramide intravenously. The visual analog scale (VAS) score, the total amount of analgesic for PCA, and the frequency of complications such as nausea and vomiting at the end of the operation and at 8, 16, 24, 32, 40, and 48 hours postoperatively were measured by orthopedic surgery
The distance between the anterior tip of the acromion and the superior angle of the scapula was 10.66 0.85 cm. The SSN was located 5.74 0.60 cm to the anterior tip of the acromion. The distance between the anterior tip of the acromion and the medial border of the spine was 13.43 0.94 cm. The SSN was located 5.47 0.57 cm to the anterior tip of the acromion. The depth of the SSN was 3.20 0.58 cm from the surface of the skin. The SSN was located at a length of one-half (2/5-3/5, 88%) from the anterior tip of the acromion to the superior angle of the scapula and at a length of two-fifths (1/3-1/2, 100%) from the anterior tip of the acromion to the medial border of the spine. The location of the SSN is shown in Table II and Figures 2 and 3.
1064 Table II
Y.-S. Nam et al. Location of SSN Mean SD (cm)
Minimum-maximum (cm)
ATA-SA 10.66 0.85 8.30-12.62 ATA-SSN 5.74 0.60 4.36-6.80 ATA-SSN/ATA-SA 0.54 0.06 (1/2) 0.39-0.68 (2/5-3/5) ATA-MBS 13.43 0.94 11.13-15.22 ATA-SSN 5.47 0.57 4.46-6.72 ATA-SSN/ATA-MBS 0.41 0.03 (2/5) 0.33-0.48 (1/3-1/2) Depth of SSN 3.20 0.58 1.84-4.49 ATA, anterior tip of acromion; SA, superior angle of scapula; MBS, medial border of spine.
Figure 3 Injection point of SSN. The SSN was located at a length of one-half from ATA to SA and at a length of two-fifths from ATA to MBS. ATA, Anterior tip of acromion; SA, superior angle of scapula; MBS, medial border of spine.
Table III
Location of AN
AAeinferior insertion of TM AA-AN AA-AN/AAeinferior insertion of TM Depth of AN Width of TM
Mean SD (cm)
Minimum-maximum (cm)
8.25 1.08
6.02-10.15
4.71 0.85 3.25-8.44 0.57 0.08 (3/5) 0.44-0.89 (2/5-4/5) 2.07 0.45 2.98 0.44
1.32-3.60 1.82-4.26
AA, acromial angle; TM, teres major muscle.
To verify that the identified location of the SSN and AN was accurate enough to be used as the landmark, 2 shoulders were dissected and a needle tip was positioned at the identified location. We confirmed the needle tip to be very close to the SSN and AN (Fig. 6). Figure 2 Location of SSN. (A) The distance between ATA and SA on SSN. (B) The distance between ATA and MBS on SSN. ATA, Anterior tip of acromion; SA, superior angle of scapula; MBS, medial border of spine.
Clinical study The outcomes in the clinical study were compared in the 2 groups. Analysis on the age and gender of patients showed no significant differences.
Location of AN
VAS score
The distance between the acromial angle and the inferior insertion of the teres major muscle was 8.25 1.08 cm. The AN was located 4.71 0.85 cm to the acromial angle. The depth of the AN was 2.07 0.45 cm from the surface of the skin. The width of insertion in the teres major muscle was 2.98 0.44 cm. The AN was located at a length of three-fifths (2/5-4/5, 98%) from the acromial angle to the inferior insertion of the teres major muscle. The location of the AN is shown in Table III and Figures 4 and 5.
At the end of the operation, the VAS score was lower in group II than in group I (Table IV, Fig. 7). In group I, the VAS score changed over time: 7.13 at 0 hours, 5.20 at 8 hours, 4.00 at 16 hours, 4.00 at 24 hours, 3.71 at 32 hours, 3.42 at 40 hours, and 3.09 at 48 hours. This meant that pain was markedly decreased from the severe state in the early stage to the mild state as time went on. In group II, the VAS score also changed over time: 5.00 at 0 hours, 5.27 at 8 hours, 5.47 at 16 hours, 4.92 at 24 hours, 4.67 at 32 hours,
Suprascapular and axillary nerve blocks
Figure 4 Location of AN. TM, Teres major muscle; AA, acromial angle.
4.25 at 40 hours, and 3.70 at 48 hours. However, the VAS score was not significantly increased until 16 hours. At 16 hours, the VAS scores in group I (4.00) and group II (5.47) were significantly different (P ¼ .021).
Total amount of analgesic for PCA At 8 hours after the operation, the total amount of analgesic for PCA was significantly less in group II than in group I (P ¼ .036) (Table IV, Fig. 8).
Frequency of complication such as nausea and vomiting At all time points, there was no significant difference between the 2 groups in the frequency of complications such as nausea and vomiting (Table IV). However, the frequency was lower in group II at all times.
Discussion Shoulder surgery is often associated with severe postoperative pain. More than 50% of patients have inadequate pain relief after surgical procedures.11 During arthroscopic shoulder surgery, the severity of postoperative pain has been reported to be greater compared with arthroscopic knee joint surgery. Boss et al6 reported that severe
1065
Figure 5 Injection point of AN. The AN was located at a length of three-fifths from AA to the inferior insertion of the teres major muscle. TM, Teres major muscle; AA, acromial angle.
postoperative pain, particularly within the first 48 hours postoperatively, is frequently observed after rotator cuff repair. The glenohumeral joint is innervated mainly from the posterior cord of the brachial plexus.9 The capsule is supplied by the SSN (posterior and superior parts), AN (anteroinferior), and lateral pectoral nerve (anterosuperior).9 During surgery, these nerves are injured, and this exerts pressure on the nociceptors. Moreover, due to intraoperative damage, reflexive muscle contraction is induced in many muscles with connections between the vertebral spines and upper extremities that are adjacent to these joints. This further aggravates the postoperative shoulder pain. In the areas adjacent to the shoulder joint, A-d afferent fibers as well as C afferent fibers are abundant.4 Among these fibers, the A-d afferent fibers have almost no analgesic effects from opioids.18 Approximately 30% to 70% of patients have severe postoperative pain.16 For early rehabilitation exercise, postoperative pain control is essential after surgery.5 Several methods for controlling pain exist, including opiate therapy, PCA, intra-articular anesthesia, interscalene block, and SSNB. Intravenous PCA is commonly used, but satisfactory analgesic effects cannot be achieved in some cases because of increases in the occurrence of nausea, vomiting, or sedation. In addition, continuous local analgesic infusion is not very effective for controlling pain and
1066
Figure 6 Injection of SSN (A) and AN (B) for results. AA, Acromial angle.
has several associated complications.12,21 The standard of care for shoulder arthroscopy at many institutions is interscalene nerve block. Interscalene block is very effective for arthroscopic shoulder surgery,1 for which various methods have been introduced.3,10,13,14,20 The most powerful analgesic effects have been reported with continuous interscalene block via a catheter after open shoulder surgery. The success rate of this block is very high. However, these methods produce side effects in 5% to 10% of cases. Rebound pain as well as incomplete effects, such as partial block or failure of the nerve block, have been reported to occur.1,2,7,28 Furthermore, most patients who receive rotator cuff surgery are older, so we should consider the safety of the interscalene block in this age group with pulmonary comorbidity. All the successful interscalene blocks could affect the phrenic nerve, and this might lead to respiratory distress or diaphragmatic paresis.24 Recently, more attention has been paid to why one would ever consider SSNB/ ANB versus an interscalene block. SSNB has been reported
Y.-S. Nam et al. to be effective, and several surgical techniques have been reported.3,13,15 It has also been reported to reduce the amount of postoperative analgesics used and has been associated with early discharge.3 Anatomic studies of the SSN and AN have been performed. According to Vorster et al,26 there are articular branches of the SSN. Uz et al25 reported that the AN also has articular branches. Performing a block of these nerve branches would be effective for controlling postoperative pain. Methods used for SSNB and ANB include approximating the nerve under electromyographic guidance14 or others, such as fluoroscopy, ultrasound, or computed tomography.20,22 Efforts are made to block the nerve accurately, and a variety of criteria and surgical techniques have been proposed. However, given the absence of accurate criteria for the anatomic landmarks, for each nerve block, the technical consistency of the procedures has been limited. Price19 and Checcucci et al8 have reported simultaneous SSNB and ANB. For SSNB, Barber3 used the base point at the junction of the middle and distal third of the spine or the Neviaser portal. Checcucci et al used the base point 2 cm medial to the medial acromion border and 2 cm cranial to the margin of the superior scapular spine. However, application of these techniques can vary with the size of the patient. In the technique reported by Matsumoto et al,15 there would be a high frequency of average error due to the obliquity of needle tip placement. In our cadaveric study, the SSN was located at a length one-half (2/5-3/5, 88%) from the anterior tip of the acromion to the superior angle of the scapula and two-fifths (1/3-1/2, 100%) from the anterior tip of the acromion to the medial border of the spine. In addition, the AN was located at a length three-fifths (2/5-4/5, 98%) from the acromial angle to the inferior insertion of the teres major muscle. The accuracy was very high, and our clinical study was performed using this technique. We sought to clarify the course of the SSN and AN and to determine the relationship between the nerves and the following anatomic landmarks and structures: the anterior tip of the acromion, the superior angle of the scapula, the medial border of the spine, the acromial angle, and the inferior insertion of the teres major muscle. The landmark of the superior angle of the scapula for the SSN was easy to identify when the scapula was elevated and rotated upward, whereas the landmark of the inferior insertion of the teres major muscle for the AN was easy to identify when the humerus was in an abduction position. All the parameters were measured in anatomic position after clearly identifying the landmark. SSNB is effective in blocking the sensory nerves that innervate the shoulder joint and adjacent tissue. However, it takes approximately 10 hours (mean time to first significant pain, 594 minutes) for symptoms to reappear.20 This time difference delays the occurrence of postoperative pain and reduces the intensity of the postoperative pain after an interscalene block. Contrary to the study reported by Neal et al,17 in this study, the analgesic efficacy of SSNB and
Suprascapular and axillary nerve blocks
1067
Table IV Results of clinical study including VAS score, total amount of analgesic for PCA, and frequency of complications such as nausea and vomiting according to time after operation 0h
8h
16 h
VAS score Group I 7.13 1.60 5.20 2.01 4.00 2.00 Group II 5.00 2.39 5.27 1.83 5.47 1.13 Total amount of analgesic for PCA (unit; mL) Group I 26.75 13.02 37.01 15.61 Group II 18.27 7.32 30.60 12.88 Frequency of complications such as nausea and vomiting Group I 4 5 7 Group II 3 4 4
Figure 7
VAS score.
ANB as an adjunct to PCA in patients undergoing arthroscopic rotator cuff surgery was assessed. In this study, the VAS score at the end of the operation was lower in group II than in group I. Group I had better pain control during the early stage of recovery but poor pain control at 8 hours after the operation. At 16 hours postoperatively, the VAS scores in group I and group II were significantly different (P ¼ .021). This might be explained by the plasma level of analgesics being maintained at a relatively lower concentration, because of the low PCA demand but also because of possible rebound pain because the nerve block was no longer effective. Compared with group I, a similar VAS score and decreased use of analgesics were observed in group II at 8 hours after the operation. In addition, the frequency of complications such as nausea and vomiting was lower in group II than group I, even though the difference was not significant. The results of this study confirm that group II had reduced use of PCA for postoperative pain. Eight hours after surgery, group II showed a significantly lower use of PCA compared with group I (P ¼ .036). This finding extended to 16 hours after surgery; however, at this time, there was no significant difference between the 2 groups. These results suggest that pain control was easier to achieve in the recovery room and that it was more difficult to obtain 8 hours after the procedure in group II. The
24 h
32 h
40 h
48 h
4.00 1.88 4.92 1.04
3.71 1.38 4.67 1.61
3.42 1.62 4.25 1.49
3.09 1.22 3.70 1.06
48.79 17.24 46.00 17.73
59.82 18.24 55.83 20.02
68.21 18.38 67.33 23.27
79.09 20.24 74.60 25.90
4 3
1 2
2 0
4 0
Figure 8
Total amount of analgesic for PCA (unit; mL).
combined SSNB and ANB had excellent analgesic effects in the recovery room and during the early stage of recovery compared with the control group. In our study, the described selective block of the SSN and AN has several advantages. Although the SSNB and ANB could not eliminate postoperative pain altogether because of the other branches of the brachial plexus and the lateral pectoral nerve, this combination could control the immediate postoperative pain. During the initial several hours, it also reduced the occurrence of severe pain and the total amount of PCA used. Compared with the interscalene block, this selective block may be needed in older patients with lung problems and it may also be used by surgeons in cases when an interscalene block is not performed by the anesthesiologist. The limitations of this study include the following: First, a small number of patients were enrolled in the clinical study, and it is difficult to conclude whether this block is superior to the interscalene block. However, we still continue to study this combined block in patients with lung problems and find its effectiveness. Further study will be needed with more patients. Second, PCA was used simultaneously as a baseline in both groups, which likely biased the PCA effects of the nerve block. The effects of isolated PCA use on postoperative pain control should be
1068 considered in a future study. Third, it is difficult to palpate the inferior insertion of the teres major muscle on the skin compared with the cadavers. Because this muscle is pretty deep and difficult to palpate ‘‘in vivo,’’ especially on the humeral side, we also measured the length in centimeters from the postero-external angle of the acromion directed distally and the AN was located 4.71 0.85 cm to the acromial angle. This measure could be used in difficult cases to palpate the inferior border of the teres major muscle in patients.
Y.-S. Nam et al.
9. 10.
11.
12.
13.
Conclusions The results of this study identified new landmarks that could be used for the SSNB and ANB. These nerve blocks were very effective for the management of early postoperative pain and also were associated with reduced use of postoperative analgesia. These results might aid in a more rapid recovery and earlier rehabilitation after surgery.
14.
15.
16. 17.
Disclaimer 18.
The authors have received a National Research Foundation of Korea grant funded by the South Korean Government (314-2008-1-E00002).
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