Eur Spine J DOI 10.1007/s00586-016-4440-5
IDEAS AND TECHNICAL INNOVATIONS
Decompression of the gluteus medius muscle as a new treatment for buttock pain: technical note Kyongsong Kim1 • Toyohiko Isu2 • Yasuhiro Chiba2 • Naotaka Iwamoto2 Daijiro Morimoto3 • Masanori Isobe2
•
Received: 2 November 2015 / Revised: 3 February 2016 / Accepted: 4 February 2016 Ó Springer-Verlag Berlin Heidelberg 2016
Abstract Purpose The clinical features and etiology of low back pain and buttock pain remain poorly understood. We report ten patients with buttock pain who underwent gluteus medius muscle (GMeM) decompression under local anesthesia. Methods Between December 2012 and November 2013 we surgically treated ten patients (four men, six women; mean age 65.1 years) for buttock pain. The affected side was unilateral in seven and bilateral in three patients (total sites, n = 13). The interval from symptom onset to treatment averaged 174 months; the mean postoperative followup period was 24 months. Decompression of the tight gluteal aponeurosis over the GMeM was performed under local anesthesia. Assessment of the clinical outcomes was on the numeric rating scale (NRS) for low back pain (LBP), the Japanese Orthopedic Association (JOA) score, and the Roland–Morris Disability Questionnaire (RDQ) score before and at the latest follow-up after treatment. Results There were no intraoperative surgery-related complications. The buttock pain of all patients was improved after surgery; their NRS decreased from 7.0 to 0.8 and JOA and RMDQ scores indicated significant improvement (p \ 0.05).
& Kyongsong Kim [email protected] 1
Department of Neurosurgery, Chiba Hokuso Hospital, Nippon Medical School, 1715, Kamagari, Inzai, Chiba, Japan
2
Department of Neurosurgery, Kushiro Rosai Hospital, Hokkaido, Japan
3
Department of Neurosurgery, Nippon Medical School, Tokyo, Japan
Conclusion In patients with buttock pain, pain around the GMeM should be considered as a causative factor. Less invasive surgery with cutting and opening of the tight gluteal aponeurosis over the GMeM under local anesthesia yielded excellent clinical outcomes. Keywords Buttock pain Decompression Gluteal aponeurosis Gluteus medius muscle Less invasive surgery Low back pain
Introduction The incidence of low back pain (LBP) is relatively high and LBP often results in functional disability [1–6]. The cause of about 90 % of LBP is non-specific [1, 3, 6] and radiological and clinical findings are diagnostically important. In some patients, LBP is not adequately controlled by conservative treatment and medications for pain control may be poorly tolerated [1–6]. The gluteus medius muscle (GMeM) is located in the buttock over the gluteus minimus muscle and partially under the gluteus maximus muscle. We encountered patients whose buttock pain was not controlled by medication and physiotherapy. While GMeM block yielded significant symptom improvement in some patients, its effect was transient. Here we report our successful treatment of these patients by GMeM decompression surgery.
Materials and methods All patients gave their prior written informed consent for participation in this study. We excluded patients with a history of hip joint surgery or lumbar spine surgery, loss of
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muscular strength or balance, and urinary or fecal incontinence. We also excluded patients with acute fracture and diseases related to malignancy, infection, osteoarthritis of the hip joint, or other bone diseases, except osteoporosis, that could affect mechanical integrity. None of the included patients had suffered trauma to the affected area. Criteria for the diagnosis of gluteus medius syndrome We carefully assessed our patients to ascertain that the GMeM played a role in their buttock pain. To exclude patients with osteoarthritis of the hip joint we evaluated radiograms. Buttock pain was considered to be due to the GMeM when it was unilateral or bilateral and involved the area around the GMeM with the trigger point located on the GMeM at the edge of the gluteus maximus muscle at the same distance from the iliac crest and the greater trochanter (Fig. 1) and when significant albeit transient symptom relief (pain reduction by more than 50 % on the NRS) was obtained within 2 h of inducing local GMeM block by injecting 5 ml of 1 % lidocaine. Patient population From among the patients not affected by our exclusion criteria, we extracted those with a GMeM diagnosis based on our diagnostic criteria including the effectiveness of GMeM block. Then we removed patients whose buttock
Fig. 1 Schematic of the gluteus medius muscle (GMeM). Right Pain trigger point (the arrow identifies the iliac crest, the arrow head the greater trochanter, the white arrow the trigger point). Left Skin incision for GMeM decompression surgery. A 5-cm-long skin incision was made across the trigger point on the buttock
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pain responded to observation therapy lasting at least 3 months, including those who had undergone repeat GMeM block. We then enrolled and surgically treated the remaining ten consecutive patients with buttock pain due to GMeM pain who were treated between December 2012 and November 2013. The workflow is diagrammed in Fig. 2. Two co-authors (Y. C. and N. I.) who did not operate on any of the patients performed the analyses. As shown in Table 1, the enrolled patients were four men and six women ranging in age from 39 to 87 years (mean 65.1 years). Radiologic findings did not yield evidence for the cause of their GMeM pain. The affected side was unilateral in seven and bilateral in three patients; 13 sites were involved. The interval between symptom onset and treatment averaged 174 months (range 24–360 months). The mean follow-up period was 24 months (range 19–31 months). In all patients, lumbar magnetic resonance imaging studies revealed abnormalities such as lumbar spinal canal stenosis (n = 5), lumbar disc hernia (n = 3), or chronic osteoporotic vertebral fracture (n = 2). For pain control, the patients usually took acetaminophen and/or non-steroidal anti-inflammatory drugs and/or tramadol; none were given codeine or morphine. All underwent at least 3 months of physiotherapy and repeated GMeM blockage. These treatments failed to alleviate severe symptoms and affected the patients’ quality of life. Surgical technique Wide decompression is necessary for sufficient GMeM decompression. The GMeM is located partially under the gluteus maximus muscle; fascial attachment to fibrous tissue of the gluteus maximus is very tight. For sufficient exposure of the GMeM, the gluteus maximus and medioinferior tracts must be fully exposed and the tight fibrous tissue and fascia must be dissected. With the patient in the prone position we performed microsurgical decompression of the GMeM. Under local skin anesthesia we made a 5-cm-long skin incision across the trigger point on the buttock (Fig. 1) and identified the gluteal aponeurosis over the GMeM in the subcutaneous space (Fig. 3). Then we cut the fascia border between the gluteus maximus muscle and the gluteal aponeurosis and applied infero-medial traction to the gluteus maximus muscle (Fig. 4). Portions of the superior gluteal nerve and vessels run between the gluteus maximus muscle and the GMeM; this may affect gluteus maximus muscle traction. As these nerves and vessels are located in an area from the midpoint to a point at the inner third of the superior posterior iliac spine to the trochanter line, known as the spine-trochanter line, it is necessary perform dissection carefully in this area. After confirming wide exposure of the gluteal aponeurosis over the GMeM we cut and opened it for
Eur Spine J Fig. 2 Workflow diagram of patient recruitment
Table 1 Characteristics of our patients with buttock pain from the gluteus medius muscle
Case
Age (yo)
Gender
Site
BP duration (mo)
F/U
NRS (mo)
RDQ
JOA score
Pre
Post
Pre
Post
Pre
Post
1
64
M
B
360
27
5
1
12
0
18
28
2
41
F
L
24
28
6
1
9
0
11
25
3
72
M
L
240
19
8
0
19
0
6
27
4
39
M
L
120
20
8
0
16
0
9
27
5
73
F
R
276
19
8
0
24
0
2
27
6
80
F
B
96
18
7
1
19
0
4
28
7
60
M
L
360
24
7
1
12
0
12
27
8
87
F
B
132
20
10
2
10
2
13
22
9 10
56 79
F F
L L
58 72
25 30
7 4
1 1
10 22
0 6
14 10
28 24
yo years old, M male, F female, BP buttock pain, R right, L left, B bilateral, mo months, F/U follow-up period, pre pretreatment, post post-operation, NRS numeric rating scale, RDQ Roland–Morris disability questionnaire, JOA Japanese Orthopedic Association
sufficient GMeM decompression; the procedure was carried out rostral to the iliac crest, medial to the sacroiliac joint, caudal to near the greater trochanter, and lateral to the tensor fasciae latae muscle (Fig. 5). The thin membrane covering the GMeM was also opened for sufficient decompression and GMeM expansion was confirmed (Fig. 5). The average surgical time was 40 min. Postoperatively the patients’ movements were not restricted. A subcutaneous drain was removed one day after the operation and the patients were discharged.
Evaluation of treatment outcomes Treatment outcomes were assessed by comparing the NRS for LBP, the Japanese Orthopedic Association (JOA) score, and the Roland–Morris Disability Questionnaire (RDQ) score recorded before treatment and at the latest follow-up. For statistical analysis, we subjected our data to the Wilcoxon signed-rank test using Statmate III software (ATMS Co. Ltd.). Differences of p \ 0.05 were considered to indicate statistical significance.
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Fig. 3 The fascia of the gluteus medius muscle (single asterisk) is partially covered by the gluteus maximus muscle (double asterisk) on the fat layer over the subcutaneous space. a Schema, b operative
view. The dotted line is the border between the gluteus maximus muscle and the gluteus medius muscle
Fig. 4 The gluteus medius muscle (asterisk) as it appears upon infero-medial traction of the gluteus maximus muscle. a Schema, b operative view. The dotted line is the border between the gluteus maximus muscle and the gluteal aponeurosis
Fig. 5 a The gluteal aponeurosis over the gluteus medius muscle (GMeM) is cut for GMeM decompression. b, c The GMeM (asterisk) is widely exposed and decompressed by cutting and opening the gluteal aponeurosis over the GMeM. b Schema, c operative view
Results All ten patients suffered buttock pain; eight also reported lateral and posterior femoral pain. In all, pain was induced by walking, standing, and standing on one leg. In four each it was exacerbated by standing and prolonged sitting and in two by rolling from side to side. Buttock pain was also induced and increased by compression above the trigger
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point (Fig. 1) and it radiated to the lateral-posterior thigh. The pretreatment NRS-, JOA-, and RDQ scores averaged 7.0 (4–10), 9.9 (2–18), and 15.3 (9–24), respectively. The senior author (T.I.) operated 13 sites in ten patients because non-surgical pain alleviation was transient. Only two patients operated early in this series experienced buttock pain recurrence and underwent re-operation for wider decompression. There were no surgical complications.
Eur Spine J
GMeM decompression led to significant buttock pain improvement. During the follow-up period no patients reported symptom exacerbation. At the last follow-up, the average NRS, JOA, and RDQ scores were 0.8 (0–2), 26.3 (22–28), and 0.8 (0–6), respectively, (p \ 0.05).
Discussion Some of our patients reported severe buttock pain that was not controlled by conservative treatments. Although their pain was improved by GMeM block, its effects were transient. We successfully treated these patients by less invasive GMeM decompression. To our knowledge, ours is the first report of surgical GMeM decompression for the treatment of buttock pain. The GMeM helps to keep the pelvis level when the opposite leg is raised during activities such as walking, running, or standing on one leg and it stabilizes the femur and pelvis during weight-bearing activities. The greatest GMeM activation is observed during the stance phase of gait [7]. Given its size, this muscle generates an exceptionally large force [8] and this anatomical background may result in GMeM pain when it is exposed to an excessive burden. LBP, whose cause, clinical features, etiology, and treatment are still poorly understood, is a frequent complaint that may result in functional disability [1–6]. Non-specific LBP is defined as pain and discomfort localized below the costal margin and above the inferior gluteal folds, with or without leg pain [2, 4]; buttock pain can be considered non-specific LBP. Hip dysfunction is associated with low back- and various lower-extremity pathologies; there is some relationship between hip dysfunction and LBP [7–9]. Nelson-Wong and Callaghan [7] reported that asymptomatic individuals with a tendency to develop LBP when subjected to prolonged standing demonstrated a pattern of co-activation of the bilateral GMeM compared with individuals who did not. According to Cooper et al. [9], GMeM weakness and associated tenderness are common findings in patients with chronic nonspecific LBP. They suggested that the GMeM plays a significant role in chronic LBP. As buttock pain may not only be the cause of non-specific LBP but may also lead to its aggravation, it must be considered in patients with LBP [2, 4, 9]. The symptom of GMeM anomaly is ipsilateral buttock pain without paresis. As radiological studies fail to diagnose buttock pain ascribable to the GMeM, its clinical features must be used. In all patients, pain from the GMeM was induced and exacerbated by walking, prolonged standing, and standing on one leg; in some it was elicited by prolonged sitting and by rolling from side to side. Buttock pain was induced and increased by compression of
the edge of the GMeM and it radiated to the lateral-posterior thigh. To confirm the diagnosis we applied a local block to the GMeM. When it produced significant pain alleviation we made a diagnosis of buttock pain ascribable to the GMeM. As drugs and physiotherapy were ineffective, we used single or multiple GMeM blockage. While this produces sufficient, long-lasting pain reduction in most patients, its effects were transient in the ten patients reported here and they were considered eligible for our less invasive surgical procedure under local anesthesia. Lumbar spine disease can be diagnosed based on neurological findings. It should be noted that in normal subjects, radiological studies can return abnormal findings [10]. In addition, a differential diagnosis is needed for several kinds of diseases around the buttocks. In the buttock, the superior and middle cluneal nerve (SCN, MCN) predominate. SCN entrapment neuropathy (SCN-EN) is one cause of non-specific LBP and buttock pain; 1.6–14.0 % of LBP has been reported to be due to SCN-EN [11–14]. It is exacerbated by lumbar movement [11–14] and tends to be wrongly attributed to lumbar spine disorder. In general, the chief symptom due to SCN-EN is localized to an area around the iliac crest and patients manifest the Tinel-like sign of SCN. Unlike GMeM pain, it is significantly decreased by SCN block. Pain due to piriformis syndrome and pain arising in the sacroiliac joint are also perceived in the gluteal region. The former resembles sciatic-type pain, i.e., there is tingling and numbness in the buttock along the sciatic nerve down to the lower thigh [15, 16]. The latter is commonly perceived in the gluteal region and can be referred to the lower limbs and/or lumbar region [17, 18]. Both are poorly understood and in the absence of gold-standard criteria, their diagnosis is often difficult [15– 17]. A definitive diagnosis is returned after other causes of the pain arising in the buttocks or lower limbs have been eliminated. Pain relief elicited by local anesthesia block of each site is diagnostically informative [15–17]. Pain from the GMeM arises in a specific anatomic area; it is superolateral to piriformis muscle- and lateral to sacroiliac joint pain. It can co-exist with buttock pain from the GMeM. In the current study, we excluded patients with a history of lumbar spine surgery although the relationship between failed back surgery syndrome and GMeM pain is of interest. As this report is a technical note on GMeM surgery we included only patients who had undergone GMeM surgery alone because we focused on the treatment outcome in patients free of the possible effects of prior lumbar operations. In future studies we will evaluate the possible relationship between failed back surgery syndrome and GMeM pain. In our series, refractory buttock pain, whose etiology is unknown, was successfully treated by GMeM decompression. Several lumbar diseases increase the load on the
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paravertebral muscle tonus. This may induce muscle spasm; sinuvertebral nerves play an important role [19, 20]. An increase in the paravertebral muscle tonus and in muscle tightness results in referred (axial) pain [19, 20]. Biomechanical studies have shown that contraction of the paravertebral muscle affects the tension in the posterior layer of the thoracolumbar fascia. Increased tension and mechanical forces are transmitted to the buttock and lower limbs due to fascial continuity of the posterior layer with the latissimus dorsi superiorly with the fascia of the superficial layer and the fascia of the dorsal spine. In addition, inferiorly, there is extensive attachment to the tight gluteal aponeurosis over the GMeM, the tenor fascia latae muscle, and the iliotibial tract [21]. Cutting the tight gluteal aponeurosis over the GMeM may stop transmission to the buttock and biceps femoris elicited by increased fascia tension and may explain the postoperative symptom improvement experienced by our patients. If the transfer of tension from the thoracolumbar fascia to the gluteal aponeurosis is the sole origin of buttock pain, then their separation via a transverse incision just below the iliac crest should be curative. However, during surgery, we observed GMeM expansion upon GMeM decompression. We also encountered patients with recurrence of GMeM pain due to insufficient GMeM decompression; it was improved by subsequent additional GMeM decompression. In a different series of patients with SCN neurolysis, GMeM pain was not alleviated by partial cutting of the thoracolumbar fascia near the iliac crest. This suggests that partial separation of the thoracolumbar fascia from the gluteal aponeurosis by transverse incision just below the iliac crest may also not be sufficient in patients with GMeM pain. Gluteal compartment syndrome (GCS) has been reported to elicit gluteal pain. It manifests as gluteal tenderness and pain and can progress to sciatic nerve palsy and rhabdomyolysis [22, 23]. The most common cause is gluteal muscle compression under prolonged immobilization. While rare, GCS tends to progress rapidly. As none of our patients manifested rapid progression and none suffered sciatic nerve palsy or rhabdomyolysis, we do not think that GCS played a role in the etiology of their buttock pain. Chronic compartment syndrome of the paraspinal muscle is elicited by chronic exertion; it is asymptomatic at rest but exaggerates LBP on exertion. Fasciotomy is useful for pain control [24, 25]. As the GMeM is located on the iliac bone and covered by a dense gluteal aponeurosis, its full expansion may be restricted. We cannot completely exclude the possibility that chronic compartment syndrome of the GMeM was involved in our patients because we did not take intramuscular pressure measurements. An alternative hypothesis suggests that the SCN and MCN are indirectly decompressed by cutting the gluteal aponeurosis
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and that this alleviates SCN-EN pain even though SCN block failed to improve GMeM pain in our series. Study limitations This study was designed to report preliminary technical results on a specific subset of patients whose buttock pain failed to respond to conventional treatments. We do not know how many of all patients with buttock pain seen at our hospital underwent surgery. Due to strict exclusion criteria our study population was small. The follow-up period was short (mean 24 months). For an accurate evaluation of the surgical outcomes, mid- (around 5 years) and long-term (around 10 years) follow-up is needed. Nonetheless, we did not observe functional deterioration due to surgery and none of the operated patients registered complaints. Additional studies are underway to determine whether our diagnostic criteria are appropriate. We are also planning a prospective study on a large patient cohort to determine the number of patients with recalcitrant LBP who benefit from GMeM surgery.
Conclusion Our successful treatment of patients with severe buttock pain by GMeM decompression surgery under local anesthesia suggests that it be considered in patients with intractable buttock pain or refractory LBP. Compliance with ethical standards Conflict of interest cial disclosures.
We have no conflicts of interest and no finan-
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Eur Spine J 5. Hestbaek L, Leboeuf-Yde C, Mannlche C (2003) Low back pain: what is the long-term course? A review of studies of general patient populations. Eur Spine J 12:149–165 6. Koes BW, van Tulder MW, Thomas S (2006) Diagnosis and treatment of low back pain. BMJ 332:1430–1434 7. Nelson-Wong E, Callaghan JP (2010) Is muscle co-activation a predisposing factor for low back pain development during standing? A multifactorial approach for early identification of atrisk individuals. J Electromyogr Kinesiol 20:256–263 8. Ward SR, Winters TM, Blemker SS (2010) The architectural design of the gluteal muscle group: implications for movement and rehabilitation. J Orthop Sports Phys Ther 40:95–102 9. Cooper NA, Scavo KM, Strickland KJ, Tipayamongkol N, Nicholson JD, Bewyer DC, Sluka KA (2015) Prevalence of gluteus medius weakness in people with chronic low back pain compared to healthy controls. Eur Spine J (epub ahead of print) 10. Boden SD, Davis DO, Dina TS, Patronas NJ, Wiesel SW (1990) Abnormal magnetic-resonance scans of the lumbar spine in asymptomatic subjects. A prospective investigation. J Bone Jt Surg Am 72:403–408 11. Chiba Y, Isu T, Kim K, Iwamoto N, Morimoto D, Yamazaki K, Hokari M, Isobe M, Kusano M (2015) Intermittent low back pain attributable to superior cluneal nerve entrapment neuropathy. J Neurosurg Spine 13:1–5 12. Maigne JY, Doursounian L (1997) Entrapment neuropathy of the medial superior cluneal nerve. Nineteen cases surgically treated, with a minimum of 2 years’ follow-up. Spine 22:1156–1159 13. Morimoto D, Isu T, Kim K, Imai T, Yamazaki K, Matsumoto R, Isobe M (2013) Surgical treatment of superior cluneal nerve entrapment neuropathy. J Neurosurg Spine 19:71–75 14. Kuniya H, Aota A, Kawai T, Kaneko K, Konno T, Saito T (2014) Prospective study of superior cluneal nerve disorder as a potential cause of low back pain and leg symptoms. J Orthop Surg Res 9:139–151
15. Michel F, Decavel P, Toussirot E, Tatu L, Aleton E, Monnier G, Garbuio P, Parratte B (2013) Piriformis muscle syndrome: diagnostic criteria and treatment of a monocentric series of 250 patients. Ann Phys Rehabil Med 56:371–383 16. Miller TA, White KP, Ross DC (2012) The diagnosis and management of piriformis syndrome: myths and facts. Can J Neurol Sci 39:577–583 17. Hancock MJ, Maher CG, Latimer J, Spindler MF, McAuley JH, Laslett M, Bogduk N (2007) Systematic review of tests to identify the disc, SIJ or facet joint as the source of low back pain. Eur Spine J 16:1539–1550 18. Vanelderen P, Szadek K, Cohen SP, De Witte J, Lataster A, Patijn J, Mekhail N, van Kleef M, Van Zundert J (2010) Sacroiliac joint pain. Pain Pract 10:470–478 19. Cloward RB (1963) Lesions of the intervertebral disks and their treatment by interbody fusion methods. The painful disk. Clin Orthop Relat Res 27:51–77 20. Pedersen HE, Blunck CF, Gardner E (1956) The anatomy of lumbosacral posterior rami and meningeal branches of spinal nerves (sinu-vertebral nerves) with an experimental study of their functions. J Bone Jt Surg Am 38:377–391 21. Vleeming A, Pool-Goudzwaard AL, Stoeckart R, van Wingerden JP, Snijders CJ (1995) The posterior layer of the thoracolumbar fascia. Its function in load transfer from spine to legs. Spine 20:753–758 22. Rudolph T, Løkebø JE, Andreassen L (2011) Bilateral gluteal compartment syndrome and severe rhabdomyolysis after lumbar spine surgery. Eur Spine J 20:S180–S182 23. Hill SL, Bianchi J (1997) The gluteal compartment syndrome. Am Surg 63:823–826 24. Nathan ST, Roberts CS, Deliberato D (2012) Lumbar paraspinal compartment syndrome. Int Orthop 36:1221–1227 25. Styf J, Lysell E (1987) Chronic compartment syndrome in the erector spinae muscle. Spine 12:680–682
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IDEAS AND TECHNICAL INNOVATIONS
Decompression of the gluteus medius muscle as a new treatment for buttock pain: technical note Kyongsong Kim1 • Toyohiko Isu2 • Yasuhiro Chiba2 • Naotaka Iwamoto2 Daijiro Morimoto3 • Masanori Isobe2
•
Received: 2 November 2015 / Revised: 3 February 2016 / Accepted: 4 February 2016 Ó Springer-Verlag Berlin Heidelberg 2016
Abstract Purpose The clinical features and etiology of low back pain and buttock pain remain poorly understood. We report ten patients with buttock pain who underwent gluteus medius muscle (GMeM) decompression under local anesthesia. Methods Between December 2012 and November 2013 we surgically treated ten patients (four men, six women; mean age 65.1 years) for buttock pain. The affected side was unilateral in seven and bilateral in three patients (total sites, n = 13). The interval from symptom onset to treatment averaged 174 months; the mean postoperative followup period was 24 months. Decompression of the tight gluteal aponeurosis over the GMeM was performed under local anesthesia. Assessment of the clinical outcomes was on the numeric rating scale (NRS) for low back pain (LBP), the Japanese Orthopedic Association (JOA) score, and the Roland–Morris Disability Questionnaire (RDQ) score before and at the latest follow-up after treatment. Results There were no intraoperative surgery-related complications. The buttock pain of all patients was improved after surgery; their NRS decreased from 7.0 to 0.8 and JOA and RMDQ scores indicated significant improvement (p \ 0.05).
& Kyongsong Kim [email protected] 1
Department of Neurosurgery, Chiba Hokuso Hospital, Nippon Medical School, 1715, Kamagari, Inzai, Chiba, Japan
2
Department of Neurosurgery, Kushiro Rosai Hospital, Hokkaido, Japan
3
Department of Neurosurgery, Nippon Medical School, Tokyo, Japan
Conclusion In patients with buttock pain, pain around the GMeM should be considered as a causative factor. Less invasive surgery with cutting and opening of the tight gluteal aponeurosis over the GMeM under local anesthesia yielded excellent clinical outcomes. Keywords Buttock pain Decompression Gluteal aponeurosis Gluteus medius muscle Less invasive surgery Low back pain
Introduction The incidence of low back pain (LBP) is relatively high and LBP often results in functional disability [1–6]. The cause of about 90 % of LBP is non-specific [1, 3, 6] and radiological and clinical findings are diagnostically important. In some patients, LBP is not adequately controlled by conservative treatment and medications for pain control may be poorly tolerated [1–6]. The gluteus medius muscle (GMeM) is located in the buttock over the gluteus minimus muscle and partially under the gluteus maximus muscle. We encountered patients whose buttock pain was not controlled by medication and physiotherapy. While GMeM block yielded significant symptom improvement in some patients, its effect was transient. Here we report our successful treatment of these patients by GMeM decompression surgery.
Materials and methods All patients gave their prior written informed consent for participation in this study. We excluded patients with a history of hip joint surgery or lumbar spine surgery, loss of
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muscular strength or balance, and urinary or fecal incontinence. We also excluded patients with acute fracture and diseases related to malignancy, infection, osteoarthritis of the hip joint, or other bone diseases, except osteoporosis, that could affect mechanical integrity. None of the included patients had suffered trauma to the affected area. Criteria for the diagnosis of gluteus medius syndrome We carefully assessed our patients to ascertain that the GMeM played a role in their buttock pain. To exclude patients with osteoarthritis of the hip joint we evaluated radiograms. Buttock pain was considered to be due to the GMeM when it was unilateral or bilateral and involved the area around the GMeM with the trigger point located on the GMeM at the edge of the gluteus maximus muscle at the same distance from the iliac crest and the greater trochanter (Fig. 1) and when significant albeit transient symptom relief (pain reduction by more than 50 % on the NRS) was obtained within 2 h of inducing local GMeM block by injecting 5 ml of 1 % lidocaine. Patient population From among the patients not affected by our exclusion criteria, we extracted those with a GMeM diagnosis based on our diagnostic criteria including the effectiveness of GMeM block. Then we removed patients whose buttock
Fig. 1 Schematic of the gluteus medius muscle (GMeM). Right Pain trigger point (the arrow identifies the iliac crest, the arrow head the greater trochanter, the white arrow the trigger point). Left Skin incision for GMeM decompression surgery. A 5-cm-long skin incision was made across the trigger point on the buttock
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pain responded to observation therapy lasting at least 3 months, including those who had undergone repeat GMeM block. We then enrolled and surgically treated the remaining ten consecutive patients with buttock pain due to GMeM pain who were treated between December 2012 and November 2013. The workflow is diagrammed in Fig. 2. Two co-authors (Y. C. and N. I.) who did not operate on any of the patients performed the analyses. As shown in Table 1, the enrolled patients were four men and six women ranging in age from 39 to 87 years (mean 65.1 years). Radiologic findings did not yield evidence for the cause of their GMeM pain. The affected side was unilateral in seven and bilateral in three patients; 13 sites were involved. The interval between symptom onset and treatment averaged 174 months (range 24–360 months). The mean follow-up period was 24 months (range 19–31 months). In all patients, lumbar magnetic resonance imaging studies revealed abnormalities such as lumbar spinal canal stenosis (n = 5), lumbar disc hernia (n = 3), or chronic osteoporotic vertebral fracture (n = 2). For pain control, the patients usually took acetaminophen and/or non-steroidal anti-inflammatory drugs and/or tramadol; none were given codeine or morphine. All underwent at least 3 months of physiotherapy and repeated GMeM blockage. These treatments failed to alleviate severe symptoms and affected the patients’ quality of life. Surgical technique Wide decompression is necessary for sufficient GMeM decompression. The GMeM is located partially under the gluteus maximus muscle; fascial attachment to fibrous tissue of the gluteus maximus is very tight. For sufficient exposure of the GMeM, the gluteus maximus and medioinferior tracts must be fully exposed and the tight fibrous tissue and fascia must be dissected. With the patient in the prone position we performed microsurgical decompression of the GMeM. Under local skin anesthesia we made a 5-cm-long skin incision across the trigger point on the buttock (Fig. 1) and identified the gluteal aponeurosis over the GMeM in the subcutaneous space (Fig. 3). Then we cut the fascia border between the gluteus maximus muscle and the gluteal aponeurosis and applied infero-medial traction to the gluteus maximus muscle (Fig. 4). Portions of the superior gluteal nerve and vessels run between the gluteus maximus muscle and the GMeM; this may affect gluteus maximus muscle traction. As these nerves and vessels are located in an area from the midpoint to a point at the inner third of the superior posterior iliac spine to the trochanter line, known as the spine-trochanter line, it is necessary perform dissection carefully in this area. After confirming wide exposure of the gluteal aponeurosis over the GMeM we cut and opened it for
Eur Spine J Fig. 2 Workflow diagram of patient recruitment
Table 1 Characteristics of our patients with buttock pain from the gluteus medius muscle
Case
Age (yo)
Gender
Site
BP duration (mo)
F/U
NRS (mo)
RDQ
JOA score
Pre
Post
Pre
Post
Pre
Post
1
64
M
B
360
27
5
1
12
0
18
28
2
41
F
L
24
28
6
1
9
0
11
25
3
72
M
L
240
19
8
0
19
0
6
27
4
39
M
L
120
20
8
0
16
0
9
27
5
73
F
R
276
19
8
0
24
0
2
27
6
80
F
B
96
18
7
1
19
0
4
28
7
60
M
L
360
24
7
1
12
0
12
27
8
87
F
B
132
20
10
2
10
2
13
22
9 10
56 79
F F
L L
58 72
25 30
7 4
1 1
10 22
0 6
14 10
28 24
yo years old, M male, F female, BP buttock pain, R right, L left, B bilateral, mo months, F/U follow-up period, pre pretreatment, post post-operation, NRS numeric rating scale, RDQ Roland–Morris disability questionnaire, JOA Japanese Orthopedic Association
sufficient GMeM decompression; the procedure was carried out rostral to the iliac crest, medial to the sacroiliac joint, caudal to near the greater trochanter, and lateral to the tensor fasciae latae muscle (Fig. 5). The thin membrane covering the GMeM was also opened for sufficient decompression and GMeM expansion was confirmed (Fig. 5). The average surgical time was 40 min. Postoperatively the patients’ movements were not restricted. A subcutaneous drain was removed one day after the operation and the patients were discharged.
Evaluation of treatment outcomes Treatment outcomes were assessed by comparing the NRS for LBP, the Japanese Orthopedic Association (JOA) score, and the Roland–Morris Disability Questionnaire (RDQ) score recorded before treatment and at the latest follow-up. For statistical analysis, we subjected our data to the Wilcoxon signed-rank test using Statmate III software (ATMS Co. Ltd.). Differences of p \ 0.05 were considered to indicate statistical significance.
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Fig. 3 The fascia of the gluteus medius muscle (single asterisk) is partially covered by the gluteus maximus muscle (double asterisk) on the fat layer over the subcutaneous space. a Schema, b operative
view. The dotted line is the border between the gluteus maximus muscle and the gluteus medius muscle
Fig. 4 The gluteus medius muscle (asterisk) as it appears upon infero-medial traction of the gluteus maximus muscle. a Schema, b operative view. The dotted line is the border between the gluteus maximus muscle and the gluteal aponeurosis
Fig. 5 a The gluteal aponeurosis over the gluteus medius muscle (GMeM) is cut for GMeM decompression. b, c The GMeM (asterisk) is widely exposed and decompressed by cutting and opening the gluteal aponeurosis over the GMeM. b Schema, c operative view
Results All ten patients suffered buttock pain; eight also reported lateral and posterior femoral pain. In all, pain was induced by walking, standing, and standing on one leg. In four each it was exacerbated by standing and prolonged sitting and in two by rolling from side to side. Buttock pain was also induced and increased by compression above the trigger
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point (Fig. 1) and it radiated to the lateral-posterior thigh. The pretreatment NRS-, JOA-, and RDQ scores averaged 7.0 (4–10), 9.9 (2–18), and 15.3 (9–24), respectively. The senior author (T.I.) operated 13 sites in ten patients because non-surgical pain alleviation was transient. Only two patients operated early in this series experienced buttock pain recurrence and underwent re-operation for wider decompression. There were no surgical complications.
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GMeM decompression led to significant buttock pain improvement. During the follow-up period no patients reported symptom exacerbation. At the last follow-up, the average NRS, JOA, and RDQ scores were 0.8 (0–2), 26.3 (22–28), and 0.8 (0–6), respectively, (p \ 0.05).
Discussion Some of our patients reported severe buttock pain that was not controlled by conservative treatments. Although their pain was improved by GMeM block, its effects were transient. We successfully treated these patients by less invasive GMeM decompression. To our knowledge, ours is the first report of surgical GMeM decompression for the treatment of buttock pain. The GMeM helps to keep the pelvis level when the opposite leg is raised during activities such as walking, running, or standing on one leg and it stabilizes the femur and pelvis during weight-bearing activities. The greatest GMeM activation is observed during the stance phase of gait [7]. Given its size, this muscle generates an exceptionally large force [8] and this anatomical background may result in GMeM pain when it is exposed to an excessive burden. LBP, whose cause, clinical features, etiology, and treatment are still poorly understood, is a frequent complaint that may result in functional disability [1–6]. Non-specific LBP is defined as pain and discomfort localized below the costal margin and above the inferior gluteal folds, with or without leg pain [2, 4]; buttock pain can be considered non-specific LBP. Hip dysfunction is associated with low back- and various lower-extremity pathologies; there is some relationship between hip dysfunction and LBP [7–9]. Nelson-Wong and Callaghan [7] reported that asymptomatic individuals with a tendency to develop LBP when subjected to prolonged standing demonstrated a pattern of co-activation of the bilateral GMeM compared with individuals who did not. According to Cooper et al. [9], GMeM weakness and associated tenderness are common findings in patients with chronic nonspecific LBP. They suggested that the GMeM plays a significant role in chronic LBP. As buttock pain may not only be the cause of non-specific LBP but may also lead to its aggravation, it must be considered in patients with LBP [2, 4, 9]. The symptom of GMeM anomaly is ipsilateral buttock pain without paresis. As radiological studies fail to diagnose buttock pain ascribable to the GMeM, its clinical features must be used. In all patients, pain from the GMeM was induced and exacerbated by walking, prolonged standing, and standing on one leg; in some it was elicited by prolonged sitting and by rolling from side to side. Buttock pain was induced and increased by compression of
the edge of the GMeM and it radiated to the lateral-posterior thigh. To confirm the diagnosis we applied a local block to the GMeM. When it produced significant pain alleviation we made a diagnosis of buttock pain ascribable to the GMeM. As drugs and physiotherapy were ineffective, we used single or multiple GMeM blockage. While this produces sufficient, long-lasting pain reduction in most patients, its effects were transient in the ten patients reported here and they were considered eligible for our less invasive surgical procedure under local anesthesia. Lumbar spine disease can be diagnosed based on neurological findings. It should be noted that in normal subjects, radiological studies can return abnormal findings [10]. In addition, a differential diagnosis is needed for several kinds of diseases around the buttocks. In the buttock, the superior and middle cluneal nerve (SCN, MCN) predominate. SCN entrapment neuropathy (SCN-EN) is one cause of non-specific LBP and buttock pain; 1.6–14.0 % of LBP has been reported to be due to SCN-EN [11–14]. It is exacerbated by lumbar movement [11–14] and tends to be wrongly attributed to lumbar spine disorder. In general, the chief symptom due to SCN-EN is localized to an area around the iliac crest and patients manifest the Tinel-like sign of SCN. Unlike GMeM pain, it is significantly decreased by SCN block. Pain due to piriformis syndrome and pain arising in the sacroiliac joint are also perceived in the gluteal region. The former resembles sciatic-type pain, i.e., there is tingling and numbness in the buttock along the sciatic nerve down to the lower thigh [15, 16]. The latter is commonly perceived in the gluteal region and can be referred to the lower limbs and/or lumbar region [17, 18]. Both are poorly understood and in the absence of gold-standard criteria, their diagnosis is often difficult [15– 17]. A definitive diagnosis is returned after other causes of the pain arising in the buttocks or lower limbs have been eliminated. Pain relief elicited by local anesthesia block of each site is diagnostically informative [15–17]. Pain from the GMeM arises in a specific anatomic area; it is superolateral to piriformis muscle- and lateral to sacroiliac joint pain. It can co-exist with buttock pain from the GMeM. In the current study, we excluded patients with a history of lumbar spine surgery although the relationship between failed back surgery syndrome and GMeM pain is of interest. As this report is a technical note on GMeM surgery we included only patients who had undergone GMeM surgery alone because we focused on the treatment outcome in patients free of the possible effects of prior lumbar operations. In future studies we will evaluate the possible relationship between failed back surgery syndrome and GMeM pain. In our series, refractory buttock pain, whose etiology is unknown, was successfully treated by GMeM decompression. Several lumbar diseases increase the load on the
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paravertebral muscle tonus. This may induce muscle spasm; sinuvertebral nerves play an important role [19, 20]. An increase in the paravertebral muscle tonus and in muscle tightness results in referred (axial) pain [19, 20]. Biomechanical studies have shown that contraction of the paravertebral muscle affects the tension in the posterior layer of the thoracolumbar fascia. Increased tension and mechanical forces are transmitted to the buttock and lower limbs due to fascial continuity of the posterior layer with the latissimus dorsi superiorly with the fascia of the superficial layer and the fascia of the dorsal spine. In addition, inferiorly, there is extensive attachment to the tight gluteal aponeurosis over the GMeM, the tenor fascia latae muscle, and the iliotibial tract [21]. Cutting the tight gluteal aponeurosis over the GMeM may stop transmission to the buttock and biceps femoris elicited by increased fascia tension and may explain the postoperative symptom improvement experienced by our patients. If the transfer of tension from the thoracolumbar fascia to the gluteal aponeurosis is the sole origin of buttock pain, then their separation via a transverse incision just below the iliac crest should be curative. However, during surgery, we observed GMeM expansion upon GMeM decompression. We also encountered patients with recurrence of GMeM pain due to insufficient GMeM decompression; it was improved by subsequent additional GMeM decompression. In a different series of patients with SCN neurolysis, GMeM pain was not alleviated by partial cutting of the thoracolumbar fascia near the iliac crest. This suggests that partial separation of the thoracolumbar fascia from the gluteal aponeurosis by transverse incision just below the iliac crest may also not be sufficient in patients with GMeM pain. Gluteal compartment syndrome (GCS) has been reported to elicit gluteal pain. It manifests as gluteal tenderness and pain and can progress to sciatic nerve palsy and rhabdomyolysis [22, 23]. The most common cause is gluteal muscle compression under prolonged immobilization. While rare, GCS tends to progress rapidly. As none of our patients manifested rapid progression and none suffered sciatic nerve palsy or rhabdomyolysis, we do not think that GCS played a role in the etiology of their buttock pain. Chronic compartment syndrome of the paraspinal muscle is elicited by chronic exertion; it is asymptomatic at rest but exaggerates LBP on exertion. Fasciotomy is useful for pain control [24, 25]. As the GMeM is located on the iliac bone and covered by a dense gluteal aponeurosis, its full expansion may be restricted. We cannot completely exclude the possibility that chronic compartment syndrome of the GMeM was involved in our patients because we did not take intramuscular pressure measurements. An alternative hypothesis suggests that the SCN and MCN are indirectly decompressed by cutting the gluteal aponeurosis
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and that this alleviates SCN-EN pain even though SCN block failed to improve GMeM pain in our series. Study limitations This study was designed to report preliminary technical results on a specific subset of patients whose buttock pain failed to respond to conventional treatments. We do not know how many of all patients with buttock pain seen at our hospital underwent surgery. Due to strict exclusion criteria our study population was small. The follow-up period was short (mean 24 months). For an accurate evaluation of the surgical outcomes, mid- (around 5 years) and long-term (around 10 years) follow-up is needed. Nonetheless, we did not observe functional deterioration due to surgery and none of the operated patients registered complaints. Additional studies are underway to determine whether our diagnostic criteria are appropriate. We are also planning a prospective study on a large patient cohort to determine the number of patients with recalcitrant LBP who benefit from GMeM surgery.
Conclusion Our successful treatment of patients with severe buttock pain by GMeM decompression surgery under local anesthesia suggests that it be considered in patients with intractable buttock pain or refractory LBP. Compliance with ethical standards Conflict of interest cial disclosures.
We have no conflicts of interest and no finan-
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