Re: 지독한 골반통증의 원인 '천장관절 증후군'

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Pain Medicine: Review Article

Sacroiliac Joint Pain: A Comprehensive Review of Anatomy, Diagnosis, and Treatment

Cohen, Steven P. MD

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Anesthesia & Analgesia 101(5):p 1440-1453, November 2005. | DOI: 10.1213/01.ANE.0000180831.60169.EA

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Abstract

Sacroiliac (SI) joint pain is a challenging condition affecting 15% to 25% of patients with axial low back pain, for which there is no standard long-term treatment. Recent studies have demonstrated that historical and physical examination findings and radiological imaging are insufficient to diagnose SI joint pain. The most commonly used method to diagnose the SI joint as a pain generator is with small-volume local anesthetic blocks, although the validity of this practice remains unproven. In the present review I provide a comprehensive review of the anatomy, function, and mechanisms of injury of the SI joint, along with a systematic assessment of its diagnosis and treatment.

초록
천장관절(SI) 관절 통증은 

축성 요통 환자의 15~25%에 영향을 미치는 까다로운 질환으로, 

장기적인 표준 치료법이 없습니다. 

최근 연구에 따르면 병력 및 신체 검사 소견과 방사선 영상만으로는 

SI 관절 통증을 진단하기에 불충분하다는 사실이 밝혀졌습니다. 

SI 관절을 통증 유발 요인으로 진단하는 데 가장 일반적으로 사용되는 방법은 

소량 국소 마취 블록을 사용하는 것이지만, 

이 방법의 유효성은 아직 입증되지 않았습니다. 

본 리뷰에서는 

SI 관절의 해부학, 

기능 및 손상 메커니즘에 대한 포괄적인 검토와 함께 

진단 및 치료에 대한 체계적인 평가를 제공합니다.

Anatomy

The sacroiliac (SI) joint is the largest axial joint in the body, with an average surface area of 17.5 cm2 (1). There is wide variability in the adult SI joint, encompassing size, shape, and surface contour. Large disparities may even exist within the same individual (2,3). The SI joint is most often characterized as a large, auricular-shaped, diarthrodial synovial joint. In reality, only the anterior third of the interface between the sacrum and ilium is a true synovial joint; the rest of the junction is comprised of an intricate set of ligamentous connections. Because of an absent or rudimentary posterior capsule, the SI ligamentous structure is more extensive dorsally, functioning as a connecting band between the sacrum and ilia (4). The main function of this ligamentous system is to limit motion in all planes of movement. In women the ligaments are weaker, allowing the mobility necessary for parturition (Figs. 1 and 2).

해부학
천장(SI) 관절은 평균 표면적이 17.5cm2(1)인 신체에서 가장 큰 축 방향 관절입니다. 성인 SI 관절은 크기, 모양, 표면 윤곽을 포함하여 매우 다양합니다. 심지어 같은 개인 내에서도 큰 차이가 존재할 수 있습니다(2,3). 

SI 관절은 대부분 귓바퀴 모양의 큰 이관절 활액막 관절로 특징지어집니다. 

실제로는 

천골과 장골 사이의 앞쪽 1/3 부분만 진정한 활액막 관절이며, 

나머지 관절은 복잡한 인대 연결로 이루어져 있습니다. 

후방 캡슐이 없거나 초보적이기 때문에 

SI 인대 구조는 등쪽으로 더 광범위하여 

천골과 장골을 연결하는 밴드 역할을 합니다(4). 

이 인대 시스템의 주요 기능은 

모든 운동 평면에서 움직임을 제한하는 것입니다.

 여성의 경우 인대가 더 약하여 

분만에 필요한 이동성을 허용합니다(그림 1 및 2).

Figure 1.: 

Posterior view of the articulations and associated ligaments of the sacroiliac joint and surrounding structures. Drawing by Jee Hyun Kim.

Figure 2.: 

Anterior view of the articulations and associated ligaments of the sacroiliac joint and surrounding structures. Drawing by Jee Hyun Kim.

The SI joint is also supported by a network of muscles that help to deliver regional muscular forces to the pelvic bones. Some of these muscles, such as the gluteus maximus, piriformis and biceps femoris, are functionally connected to SI joint ligaments, so their actions can affect joint mobility. The potential for vertical shearing is present in approximately 30% of SI joints, owing to the more acute angulation of the short, horizontal articular component (5).

Age-related changes in the SI joint begin in puberty and continue throughout life. During adolescence, the iliac surface becomes rougher, duller, and coated in some areas with fibrous plaques. These senescent changes accelerate during the third and fourth decades of life and are manifested by surface irregularities, crevice formation, fibrillation and the clumping of chondrocytes. Degenerative changes on the sacral side generally lag 10–20 yr behind those affecting the iliac surface. In the sixth decade, motion at the joint may become markedly restricted as the capsule becomes increasingly collagenous and fibrous ankylosis occurs. By the eighth decade of life, erosions and plaque formation are inevitable and ubiquitous (4).

또한 SI 관절은 

골반 뼈에 국소 근육의 힘을 전달하는 데 도움이 되는

 근육 네트워크에 의해 지지됩니다. 

대둔근, 이상근, 대퇴 이두근과 같은 일부 근육은 

SI 관절 인대와 기능적으로 연결되어 있으므로 

이러한 근육의 작용이 관절 이동성에 영향을 미칠 수 있습니다. 

SI 관절의 약 30%에서 수직 전단 가능성이 존재하는데, 

이는 짧은 수평 관절 구성 요소의 각도가 더 급격하기 때문입니다(5).

SI 관절의 연령 관련 변화는 

사춘기에 시작되어 평생 동안 지속됩니다. 

청소년기에는 

장골 표면이 더 거칠어지고 둔해지며 

일부 부위에 섬유질 플라크로 코팅됩니다. 

이러한 

노화 변화는 인생의 30~40대에 가속화되며

 표면 불규칙성, 틈새 형성, 세동 및 연골 세포의 응집으로 나타납니다. 

천골 쪽의 퇴행성 변화는 

일반적으로 장골 표면에 영향을 미치는 것보다 10~20년 뒤늦게 나타납니다. 

6년째에는 캡슐이 점점 더 콜라겐화되고 

섬유성 강직증이 발생하면서 

관절의 움직임이 현저하게 제한될 수 있습니다. 

인생의 80년차에는

미란과 플라크 형성이 불가피하며

어디에나 존재합니다(4).

Innervation

The innervation of the SI joint remains a subject of much debate. The lateral branches of the L4-S3 dorsal rami are cited by some experts as composing the major innervation to the posterior SI joint (1). Other investigators claim that L3 and S4 contribute to the posterior nerve supply (6,7). The innervation of the anterior joint is similarly ambiguous. Early 20th century German literature asserts the anterior SI joint is supplied by the obturator nerve, superior gluteal nerve and the lumbosacral trunk (8). More recent literature suggests the anterior joint is innervated by L2-S2 (1), L4-S2 (9), and the L5-S2 ventral rami (10). Some authors have even suggested that the anterior SI joint is devoid of nervous tissue (7,11). In a study testing the ability of L5 dorsal ramus and S1-4 lateral branch blocks to protect the SI joint from an experimental stimulus, 6 of 10 subjects retained the ability to perceive ligamentous probing (12).

A neurophysiologic study conducted in cats identified 29 mechanosensitive afferent units, 26 of which were found in the joint capsule and 3 in adjacent muscles (13). Twenty-eight of these units were classified as nociceptive and 1 as proprioceptive. Among these 29 receptive fields, 16 were located in the proximal third of the posterior SI joint and 11 in the middle third. The average mechanical threshold of an SI joint nociceptive unit was 70 g, as compared to the 6 g mean mechanical threshold for lumbar facet joint nociceptive units and the 241 g threshold for units residing in the anterior lumbar disk (14–16). This indicates that the pain sensitivity of the SI joints may be lower than that of the lumbar facet joints but higher than the anterior portions of lumbar discs. As all animals underwent posterior midline incisions, somatosensory units in the anterior SI joint were not stimulated.

신경 분포

SI 관절의 신경 분포는 여전히 많은 논쟁의 대상이 되고 있습니다. 

일부 전문가들은 

L4-S3 등쪽 라미의 측면 가지가 후방 SI 관절의 주요 신경을 구성하는 것으로 인용합니다(1). 

다른 연구자들은 

L3와 S4가 후방 신경 공급에 기여한다고 주장합니다(6,7). 

전방 관절의 신경 분포도 마찬가지로 모호합니다. 20세기 초 독일 문헌에서는 전방 SI 관절이 폐쇄 신경, 상둔 신경 및 요천골 줄기에 의해 공급된다고 주장합니다(8). 최근의 문헌에 따르면 전방 관절은 L2-S2(1), L4-S2(9) 및 L5-S2 복측 라미(10)에 의해 신경을 공급받는다고 합니다. 일부 저자는 심지어 전방 SI 관절에 신경 조직이 없다고 제안하기도 했습니다(7,11). 실험 자극으로부터 SI 관절을 보호하는 L5 등쪽 라무스와 S1-4 측면 가지 블록의 능력을 테스트한 연구에서 피험자 10명 중 6명은 인대 프로빙을 인지하는 능력을 유지했습니다(12).

고양이를 대상으로 실시한 신경생리학 연구에서는 29개의 기계 민감성 구심성 유닛을 확인했으며, 그 중 26개는 관절낭에서, 3개는 인접 근육에서 발견되었습니다(13). 이 중 28개는 통각 수용, 1개는 고유 수용으로 분류되었습니다. 이 29개의 수용 영역 중 16개는 후방 SI 관절의 근위 1/3에, 11개는 중간 1/3에 위치했습니다. SI 관절 통각 단위의 평균 기계적 역치는 70g으로, 요추 면 관절 통각 단위의 평균 기계적 역치 6g과 요추 전방 디스크(14-16번)에 위치한 단위의 역치 241g에 비해 훨씬 컸습니다. 이는 SI 관절의 통증 민감도가 요추 면 관절보다는 낮지만 요추 디스크의 앞쪽 부분보다는 높을 수 있음을 나타냅니다. 모든 동물이 후방 중앙선 절개를 받았기 때문에 전방 SI 관절의 체성 감각 단위는 자극되지 않았습니다.

Function and Biomechanics

The SI joints are designed primarily for stability. Their functions include the transmission and dissipation of truncal loads to the lower extremities, limiting x-axis rotation, and facilitating parturition. Compared to the lumbar spine, the SI joints can withstand a medially directed force 6 times greater but only half the torsion and 1/20th of the axial compression load (17). These last 2 motions may preferentially strain and injure the weaker anterior joint capsule (18).

There have been numerous attempts to discern the biomechanics of the SI joint. These motion studies can be summarized as follows: the SI joint rotates about all 3 axes, although the movements are very small and difficult to measure (19,20). Miller et al. (21) studied the load-displacement behavior of single and paired SI joints in 8 elderly cadavers. Various static test loads were applied in the superior, lateral, anterior and posterior directions, and rotations about all 3 axes were measured. These tests were conducted with one and both ilia fixed. The authors found that with 1 leg immobile, movements in all planes ranged from between 2 to 7.8 times more than that measured with both legs fixed. In a series of cadaveric studies, Vleeming et al. (22,23) found that the total range of motion during flexion and extension at the SI joint rarely exceeded 2 degrees, with 4 degrees being the upper limit during sagittal rotation. In another cadaver study, Brunner et al. (24) found that the main motion in male specimens tended to be translation, whereas in female specimens it was rotational. The maximum range of motion in this study was 1.2 degrees in men and 2.8 degrees in women. In a study by Egund et al. (25) examining SI joint movements in 4 volunteers using radiographic stereophotogrammetry, the authors found the maximal rotations and translations to be 2.0 degrees and 2.0 mm, respectively. A larger study (n = 24) by Jacob and Kissling (26) conducted in healthy young and middle-aged men and women found similarly small limits on rotation (1.7 degrees) and translation (0.7 mm). However, one individual with a history of SI joint pain exhibited more than 6 degrees of rotation about the y-axis. Finally, Sturesson et al. (27) measured multiple SI joint movements in 25 patients diagnosed with SI joint pain. Movements in all planes were found to be small, with translations never exceeding 1.6 mm, and rotations being limited to 3 degrees. No differences were found between symptomatic and asymptomatic joints, leading the authors to conclude that 3-dimensional motion analysis was not useful for identifying painful SI joints in most patients. Possible exceptions to the finding that hypermobility is not a typical cause of SI joint pain include traumatic instability, multiparity, muscular atrophy, and lower motor neuron disease (28).

기능 및 생체 역학

SI 관절은 주로 안정성을 위해 설계되었습니다. 

이 관절의 기능에는 하지로 전달되는 하중을 분산하고, 

X축 회전을 제한하며, 

분만을 촉진하는 것이 포함됩니다. 

요추와 비교했을 때, 

SI 관절은 내측으로 향하는 힘은 6배 더 크지만 

비틀림은 절반, 축 방향 압박 하중은 1/20에 불과합니다(17). 

이 마지막 두 동작은 약한 전방 관절낭을 우선적으로 긴장시키고 손상시킬 수 있습니다(18).

SI 관절의 생체 역학을 규명하려는 시도는 수없이 많았습니다. 이러한 움직임 연구는 다음과 같이 요약할 수 있습니다. 

SI 관절은 세 축 모두에서 회전하지만 움직임이 매우 작고 측정하기 어렵습니다(19,20). 

Miller 등(21)은 8명의 노인 시체에서 단일 및 쌍 SI 관절의 하중-변위 거동을 연구했습니다. 상부, 측면, 전방 및 후방 방향으로 다양한 정적 시험 하중을 가하고 세 축에 대한 회전을 측정했습니다. 이 테스트는 한쪽 및 양쪽 장골을 고정시킨 상태에서 수행되었습니다. 저자들은 한쪽 다리를 움직이지 않은 상태에서 모든 평면의 움직임이 양쪽 다리를 고정했을 때보다 2~7.8배 더 많다는 것을 발견했습니다. 일련의 사체 연구에서 Vleeming 등(22,23)은 SI 관절의 굴곡 및 신전 시 총 운동 범위가 2도를 거의 넘지 않으며 시상 회전 시 상한은 4도라는 것을 발견했습니다. 또 다른 사체 연구에서 Brunner 등(24)은 남성 표본의 주요 동작은 이동인 반면, 여성 표본은 회전인 경향이 있음을 발견했습니다. 이 연구에서 최대 운동 범위는 남성의 경우 1.2도, 여성의 경우 2.8도였습니다. 방사선 입체 사진 측정을 사용하여 지원자 4명의 SI 관절 움직임을 조사한 Egund 등(25)의 연구에서 저자는 최대 회전과 이동이 각각 2.0도 및 2.0mm인 것으로 나타났습니다. 건강한 청년 및 중년 남성과 여성을 대상으로 실시한 Jacob과 Kissling(26)의 대규모 연구(n = 24)에서도 회전(1.7도)과 이동(0.7mm)의 한계가 비슷하게 작다는 것을 발견했습니다. 그러나 SI 관절 통증의 병력이 있는 한 사람은 Y축을 기준으로 6도 이상의 회전 제한이 나타났습니다. 마지막으로 스투어슨 등(27)은 SI 관절 통증으로 진단받은 25명의 환자에서 여러 SI 관절 움직임을 측정했습니다. 모든 평면에서의 움직임은 작은 것으로 나타났으며, 이동은 1.6mm를 넘지 않았고 회전은 3도로 제한되었습니다. 증상이 있는 관절과 무증상 관절 사이에는 차이가 발견되지 않았기 때문에 저자들은 3차원 동작 분석이 대부분의 환자에서 통증이 있는 SI 관절을 식별하는 데 유용하지 않다고 결론지었습니다. 과운동성이 SI 관절 통증의 전형적인 원인이 아니라는 결과에 대한 가능한 예외로는 외상성 불안정성, 다발성, 근육 위축 및 하부 운동 신경 질환이 있습니다(28).

Preval‎ence

Although it is widely acknowledged that dysfunctional SI joints may cause low back pain (LBP), the preval‎ence of this condition has not been well studied. Preval‎ence studies are further compromised by the fact that most have used either physical examination findings and/or radiological imaging techniques to make the diagnosis of SI joint pain. The largest of these is a retrospective study by Bernard and Kirkaldy-Willis (29), who found a 22.5% preval‎ence rate in 1293 adult patients presenting with LBP. Diagnoses in this series were based predominantly on physical examination.

Schwarzer et al. (30) conducted a preval‎ence study involving 43 consecutive patients with chronic LBP principally below L5-S1 using fluoroscopically guided SI joint injections. Fifty-seven other patients with LBP were excluded on the basis of more rostral symptoms. Three criteria were used to diagnose SI joint pain: analgesic response to local anesthetic (LA), abnormalities on post-arthrography computed tomography (CT) scanning, and concordant pain provocation during joint distension. Using significant pain relief after LA injection as the sole criterion for diagnosis, the preval‎ence of SI joint pain in the 43 subjects was determined to be 30% (95% confidence interval [CI], 16%–44%), with 4 patients obtaining complete pain relief. Using analgesic response combined with a ventral capsular tear (the most common radiologic finding) as the criteria, the preval‎ence decreased to 21% (95% CI, 9%–33%). Only 7 patients satisfied all 3 diagnostic criteria, for a lower limit preval‎ence rate of 16% (95% CI, 5%–27%). The presence of groin pain was the only referral pattern found to distinguish patients with SI joint pain from those with LBP of non-SI joint origin.

Maigne et al. (31) conducted a preval‎ence study in 54 patients with unilateral LBP using a series of blocks done with different LA based on International Spinal Injection Society guidelines (32). Nineteen patients had a positive response (≥75% pain relief) to the lidocaine screening block. Among these patients, 10 (18.5%) responded with >2 h pain relief after the confirm‎atory block with bupivacaine and were considered to have true SI joint pain (95% CI, 9%–29%). Based on these studies, the preval‎ence of SI joint pain in carefully screened LBP patients appears to be in the 15%–25% range.

유병률
SI 관절의 기능 장애가 요통(LBP)을 유발할 수 있다는 사실은 널리 알려져 있지만, 이 질환의 유병률은 잘 연구되지 않았습니다. 유병률 연구는 대부분 신체 검사 결과 및/또는 방사선 영상 기술을 사용하여 SI 관절 통증을 진단했기 때문에 더욱 어렵습니다. 이 중 가장 규모가 큰 연구는 1293명의 성인 환자에서 22.5%의 유병률을 보인 버나드와 커칼디-윌리스(29)의 후향적 연구로, LBP를 앓고 있는 성인 환자 1293명을 대상으로 했습니다. 이 시리즈의 진단은 주로 신체 검사를 기반으로 이루어졌습니다.
Schwarzer 등(30)은 주로 L5-S1 이하의 만성 LBP 환자 43명을 대상으로 형광 투시 유도 SI 관절 주사를 사용하여 유병률 연구를 수행했습니다. 다른 57명의 LBP 환자는 더 많은 요추 증상을 이유로 제외되었습니다. SI 관절 통증 진단에는 국소 마취제(LA)에 대한 진통 반응, 관절 조영술 후 컴퓨터 단층 촬영(CT) 스캔의 이상, 관절 팽창 중 일치하는 통증 유발이라는 세 가지 기준이 사용되었습니다. LA 주사 후 유의미한 통증 완화를 유일한 진단 기준으로 사용한 결과, 43명의 피험자에서 SI 관절통의 유병률은 30%(95% 신뢰구간[CI], 16%-44%)로 확인되었으며, 4명의 환자는 완전한 통증 완화를 얻었습니다. 진통제 반응과 복측 관절낭 파열(가장 흔한 방사선학적 소견)을 기준으로 삼았을 때 유병률은 21%(95% CI, 9%-33%)로 감소했습니다. 3가지 진단 기준을 모두 충족한 환자는 7명에 불과하여 하한 유병률은 16%(95% CI, 5%-27%)였습니다. 사타구니 통증의 존재는 SI 관절 통증 환자와 비 SI 관절 기원의 LBP 환자를 구별하는 유일한 의뢰 패턴이었습니다.

Maigne 등(31)은 국제 척추 주사 학회 가이드라인(32)에 따라 다양한 LA로 일련의 차단을 수행하여 일측성 LBP 환자 54명을 대상으로 유병률 연구를 수행했습니다. 19명의 환자가 리도카인 선별 차단에 대해 긍정적인 반응(≥75% 통증 완화)을 보였습니다. 이 환자 중 10명(18.5%)은 부피바카인으로 확진 차단 후 2시간 이상 통증이 완화되어 실제 SI 관절 통증이 있는 것으로 간주되었습니다(95% CI, 9%-29%). 

이러한 연구에 따르면 

신중하게 선별된 LBP 환자에서 

SI 관절통의 유병률은 15%~25% 범위인 것으로 나타났습니다.

Mechanism of Injury

The mechanism of SI joint injury has previously been described as a combination of axial loading and abrupt rotation (18). On an anatomic level, pathologic changes affecting many different SI joint structures can lead to nociception. These include capsular or synovial disruption, capsular and ligamentous tension, hypomobility or hypermobility, extraneous compression or shearing forces, abnormal joint mechanics, microfractures or macrofractures, chondromalacia, soft tissue injury, and inflammation. Mechanistically, there are numerous reported etiologies for SI joint pain. To simplify matters, these causes can be divided into intraarticular and extra-articular sources. Arthritis and infection are two examples of intraarticular causes of SI joint pain. Extra-articular sources are the more common of the two and include enthesopathy, fractures, ligamentous injury, and myofascial pain. Clinical studies have demonstrated significant pain relief after both intraarticular and periarticular SI joint injections (33–36).

In addition to etiologic sources, there are numerous factors that can predispose a person to gradually develop SI joint pain. Risk factors that operate by increasing the stress borne by the SI joints include true and apparent leg length discrepancy (37), gait abnormalities (38), prolonged vigorous exercise (39), scoliosis (40), and spinal fusion to the sacrum (41). Whereas increased SI joint uptake using scintigraphy has been demonstrated after lumbar spine fusion (42), at least one study examining the long-term effects of spinal fusion on SI joint function concluded that neither biomechanical nor anatomical changes were more common in fusion patients than in those who underwent decompression procedures (43). Lumbar spine surgery has also been purported to trigger SI joint pain for reasons unrelated to increased force transmission. These factors include SI ligament weakening and/or surgical violation of the joint cavity during iliac graft bone harvest (44) and postsurgical hypermobility (45).

Pregnancy predisposes women to SI joint pain via the combination of increased weight gain, exaggerated lordotic posture, the mechanical trauma of parturition, and hormone-induced ligamental laxity (46,47). The laxity associated with pregnancy is attributable to increased levels of estrogen and relaxin, and it predisposes parturients to sprains of the SI joint ligaments. SI subluxation has also been reported to cause back pain in pregnancy (48).

Inflammation of one or both SI joints is considered to be an early and prominent symptom in all seronegative and HLA-B27-associated spondylarthropathies (49). Although the precise etiology of spondylarthropathy remains unknown in most patients, the strong association with HLA-B27 supports the view that these conditions are attributable to a genetically determined immune response to environmental factors in susceptible individuals. In a subset of patients with Reiter's syndrome/reactive arthritis, the disease is clearly induced by infection (50) (Table 1).

부상 메커니즘
SI 관절 손상의 메커니즘은 이전에 축 방향 하중과 갑작스러운 회전의 조합으로 설명되었습니다(18). 해부학적 수준에서 다양한 SI 관절 구조에 영향을 미치는 병리학적인 변화가 통증을 유발할 수 있습니다. 여기에는 관절낭 또는 활액질 파괴, 관절낭 및 인대 긴장, 저운동성 또는 과운동성, 외부 압박 또는 전단력, 비정상적인 관절 역학, 미세 골절 또는 거대 골절, 연골연화증, 연조직 손상 및 염증이 포함됩니다. 기계적으로 SI 관절 통증의 원인은 여러 가지가 보고되고 있습니다. 문제를 단순화하기 위해 이러한 원인은 관절 내 원인과 관절 외 원인으로 나눌 수 있습니다. 관절염과 감염은 SI 관절통의 관절 내 원인의 두 가지 예입니다. 관절 외 원인은 이 두 가지 중 더 흔한 원인으로 생착증, 골절, 인대 손상 및 근막 통증을 포함합니다. 임상 연구에 따르면 관절 내 및 관절 주위 SI 관절 주사 후 통증이 크게 완화되는 것으로 나타났습니다(33-36).

병인 외에도 SI 관절 통증을 점진적으로 유발할 수 있는 다양한 요인이 있습니다. SI 관절이 받는 스트레스를 증가시켜 작용하는 위험 요인으로는 실제 및 외관상 다리 길이 불일치(37), 보행 이상(38), 장기간의 격렬한 운동(39), 척추 측만증(40), 천골과의 척추 유합(41) 등이 있습니다. 요추 유합술 후 신티그래피를 이용한 SI 관절 흡수 증가가 입증되었지만(42), 척추 유합술이 SI 관절 기능에 미치는 장기적인 영향을 조사한 최소 한 연구에서는 유합술 환자에서 감압술을 받은 환자보다 생체역학적 또는 해부학적 변화가 더 흔하지 않다는 결론을 내렸습니다(43). 요추 수술은 또한 힘 전달 증가와 무관한 이유로 SI 관절 통증을 유발하는 것으로 알려져 있습니다. 이러한 요인으로는 장골 이식골 채취 중 SI 인대 약화 및/또는 수술 중 관절강 침범(44) 및 수술 후 과운동성(45) 등이 있습니다.

임신은 체중 증가, 과장된 전만 자세, 분만 시 기계적 외상, 호르몬으로 인한 인대 이완의 조합을 통해 여성에게 SI 관절 통증을 유발할 수 있습니다(46,47). 임신과 관련된 이완은 에스트로겐과 릴렉신 수치의 증가로 인해 발생하며, 분만 시 SI 관절 인대가 염좌될 가능성이 높습니다. SI 아탈구는 임신 중 요통을 유발하는 것으로도 보고되었습니다(48).

한쪽 또는 양쪽 SI 관절의 염증은 모든 혈청 음성 및 HLA-B27 관련 척추 관절 병증에서 조기에 두드러진 증상으로 간주됩니다(49). 대부분의 환자에서 척추관절병증의 정확한 원인은 아직 밝혀지지 않았지만, HLA-B27과의 강력한 연관성은 이러한 질환이 취약한 개인의 환경 요인에 대한 유 전적으로 결정된 면역 반응에 기인한다는 견해를 뒷받침합니다. 라이터 증후군/반응성 관절염 환자의 일부에서는 이 질환이 감염에 의해 유발되는 것이 분명합니다(50)(표 1).

Table 1: 

Sacroiliac Joint Involvement and Other Characteristics of the Adult Spondylarthropathies

The specific etiologies that can result in SI joint pain are widespread and protean. Potential causes range from rare events such as pyogenic infection (51) and malignancy (52), to more mundane occurrences such as bracing one's legs in a motor vehicle accident (53), falls (53), athletic injuries (54), prolonged lifting and bending (55), and torsional strain (55). In a retrospective study by Chou et al. (56) assessing the inciting events in 54 patients with injection-confirmed SI joint pain, the authors found trauma was the cause in 44% of patients, 35% were idiopathic, and 21% were attributed to the cumulative effects of repeated stress. In the 24 patients who cited trauma as the source of their pain, the most common events were motor vehicle accidents (n = 13), falls onto the buttock (n = 6), and childbirth (n = 3).

천장관절 침범 및 성인 척추 관절 병증의 기타 특징

SI 관절 통증을 유발할 수 있는 특정 원인은 매우 광범위하고 다양합니다. 

화농성 감염(51) 및 악성 종양(52)과 같은 드문 경우부터 

자동차 사고로 다리를 고정하는 것(53), 

낙상(53), 

운동 부상(54), 

장시간 들어올리거나 구부리는 것(55), 

비틀림 긴장(55) 등 일상적인 경우까지 잠재적인 원인이 다양합니다. 

주사가 확인된 SI 관절통 환자 54명의 유발 사건을 평가한 Chou 등(56)의 후향적 연구에서 저자는 환자의 44%에서 외상이 원인이었고 35%는 특발성, 21%는 반복적인 스트레스의 누적된 영향에 기인한다는 사실을 발견했습니다. 

통증의 원인으로 외상을 꼽은 24명의 환자에서 가

장 흔한 사건은 

교통사고(n = 13), 

엉덩이로 넘어짐(n = 6), 

출산(n = 3)이었습니다.

Diagnosis and PresentationHistory and Physical Examination

One of the most challenging aspects of treating SI joint pain is the complexity of diagnosis. Literally dozens of physical examination tests have been advocated as diagnostic aids in patients with presumed SI joint pain (57). Many involve distraction of the SI joints, with 2 of the most common ones being Patrick's test and Gaenslen's test. Despite the plethora of diagnostic tests, clinical studies have for the most part demonstrated that neither medical history nor physical examination findings are consistently capable of identifying dysfunctional SI joints as pain generators (30, 58, 59) (Table 2). In addition, Dreyfuss et al. (60) found 20% of asymptomatic adults had positive findings on 3 commonly performed SI joint provocation tests.

진단 및 제시병력 및 신체 검사
SI 관절통 치료의 가장 어려운 측면 중 하나는 진단의 복잡성입니다. 말 그대로 수십 가지의 신체 검사가 SI 관절 통증으로 추정되는 환자의 진단 보조 수단으로 옹호되어 왔습니다(57). 그중 가장 일반적인 검사로는 패트릭 검사와 겐슬렌 검사 두 가지가 있으며, 대부분은 SI 관절의 산만함과 관련이 있습니다. 수많은 진단 검사에도 불구하고 대부분의 임상 연구에서는 병력이나 신체 검사 결과만으로는 기능 장애가 있는 SI 관절을 통증 유발 요인으로 식별할 수 없다는 것이 입증되었습니다(30, 58, 59)(표 2). 또한 Dreyfuss 등(60)은 무증상 성인의 20%가 일반적으로 시행되는 3가지 SI 관절 유발 검사에서 양성 소견을 보인다는 사실을 발견했습니다.

Table 2: 

Studies Assessing Accuracy of History and Physical Examination in the Diagnosis of Injection-Confirmed Sacroiliac (SI) Joint

Pain

The reliability of provocative SI joint maneuvers and alignment/mobility tests has also been questioned, with most studies conducted by chiropractors and physical therapists. Whereas some of these studies have found moderate to high inter-examiner reliability (61–63), most have not (64–68). Generally, reproducibility has been found to be greater for provocative tests than for mobility and alignment assessments. In the Dreyfuss et al. study (59) conducted in 85 patients with injection-confirmed SI joint pain, there was moderate agreement (kappa = 0.6) between chiropractors and medical doctors with regard to provocative maneuvers of painful joints. Even when agreement was perfect, the maneuvers were still found to lack diagnostic utility.

통증
대부분의 연구는 카이로프랙틱 의사와 물리 치료사가 수행했으며, 자극적인 SI 관절 동작과 정렬/이동성 테스트의 신뢰성에 대한 의문도 제기되었습니다. 이러한 연구 중 일부는 검사자 간 신뢰도가 보통에서 높은 것으로 나타났지만(61-63), 대부분은 그렇지 않은 것으로 나타났습니다(64-68). 일반적으로 재현성은 이동성 및 정렬 평가보다 자극 테스트에서 더 높은 것으로 나타났습니다. 주사로 확인된 SI 관절 통증 환자 85명을 대상으로 실시한 Dreyfuss 등의 연구(59)에서는 통증이 있는 관절의 자극적 동작에 대해 카이로프랙터와 의사 간에 중간 정도의 일치도(kappa = 0.6)가 있었습니다. 의견이 완벽히 일치하더라도 해당 동작은 여전히 진단적 유용성이 부족한 것으로 나타났습니다.

Radiological Studies

Results of studies examining radiologic findings in patients with SI joint pain have been similarly disappointing. In studies by Maigne et al. (69) and Slipman et al. (70), the investigators found sensitivities of 46% and 13%, respectively, for the use of radionuclide bone scanning in the identification of SI joint pain. Despite the high specificites in these studies (89.5% for Maigne et al. and 100% for Slipman et al.), the low sensitivies indicate bone scanning is a poor screening test for SI joint pain. Poor correlation with diagnostic injections and symptoms have also been found for CT and radiographic stereophotogrammetry (71,27). In a retrospective analysis by Elgafy et al. (71), CT imaging was found to be 57.5% sensitive and 69% specific in diagnosing SI joint pain.

방사선 연구
SI 관절 통증 환자의 방사선학적 소견을 조사한 연구 결과도 비슷하게 실망스러운 결과를 보였습니다. Maigne 등(69)과 Slipman 등(70)의 연구에서 연구자들은 SI 관절 통증을 식별하는 데 방사성 핵종 뼈 스캔을 사용할 때 각각 46%와 13%의 민감도를 발견했습니다. 이 연구들의 높은 특이도(Maigne 등 89.5%, Slipman 등 100%)에도 불구하고 낮은 민감도는 뼈 스캔이 SI 관절통에 대한 선별 검사로 적절하지 않다는 것을 나타냅니다. 진단 주사 및 증상과의 낮은 상관관계는 CT 및 방사선 입체 사진 측정에서도 발견되었습니다(71,27). 엘가피 등(71)의 후향적 분석에 따르면, CT 영상은 SI 관절통 진단에 57.5%의 민감도와 69%의 특이도를 보이는 것으로 나타났습니다.

Pain Referral Patterns

There have been several attempts to identify pain referral patterns from SI joints. In one of the earliest studies conducted in 10 asymptomatic volunteers, Fortin et al. (72) performed provocative SI joint injections using contrast and lidocaine. Sensory changes were localized to the ipsilateral medial buttock inferior to the posterior superior iliac spine in 6 of the 10 subjects. In 2 subjects, the area of hyperesthesia extended to the superior aspect of the greater trochanter. The last 2 subjects experienced sensory changes radiating into the upper thigh. In a follow-up study, independent examiners selected 16 individuals among 54 with chronic LBP whose pain diagrams most closely resembled the pain referral patterns obtained in the first study (73). These 16 patients proceeded to undergo provocative SI joint injections with contrast and LA. All 16 experienced concordant pain during the injection, with 14 obtaining pain relief after deposition of LA. Ten patients reported ≥50% pain reduction. Six of the 16 patients had ventral capsular tears revealed during arthrography. After the SI joint injections, provocative discography and lumbar facet joint injections were performed in 9 patients each. In none of the patients was either test positive.

Slipman et al. (74) conducted a retrospective study to determine the pain referral patterns in 50 patients with injection-confirmed SI joint pain. In contrast to the findings by Fortin et al. (72) and Schwarzer et al. (30), the authors found the most common referral patterns for SI joint pain to be radiation into the buttock (94%), lower lumbar region (72%), lower extremity (50%), groin area (14%), upper lumbar region (6%), and abdomen (2%). Twenty-eight percent of patients experienced pain radiating below their knee, with 12% reporting foot pain. Based on the existing data, the most consistent factor for identifying patients with SI joint pain is unilateral pain (unless both joints are affected) localized predominantly below the L5 spinous process (30,59,72–74).

통증 유발 패턴
SI 관절에서 통증 유발 패턴을 확인하려는 시도는 여러 차례 있었습니다. 무증상 지원자 10명을 대상으로 실시한 초기 연구 중 하나에서 Fortin 등(72)은 조영제와 리도카인을 사용하여 자극성 SI 관절 주사를 시행했습니다. 감각 변화는 10명 중 6명의 피험자에서 후상 장골보다 아래쪽 동측 내측 엉덩이에 국한되었습니다. 2명의 피험자에서는 감각 이상 부위가 대퇴골의 상부까지 확장되었습니다. 마지막 2명의 피험자는 허벅지 위쪽으로 방사되는 감각 변화를 경험했습니다. 후속 연구에서 독립적인 검사자들은 만성 LBP 환자 54명 중 통증 다이어그램이 첫 번째 연구(73명)에서 얻은 통증 의뢰 패턴과 가장 유사한 16명을 선정했습니다. 이 16명의 환자들은 조영제와 LA를 이용한 자극성 SI 관절 주사를 받았습니다. 16명 모두 주사 중 일관된 통증을 경험했으며, 14명은 LA를 주입한 후 통증이 완화되었습니다. 10명의 환자는 50% 이상의 통증 감소를 보고했습니다. 16명 중 6명의 환자에서 관절 조영술 중 복측 관절낭 파열이 발견되었습니다. SI 관절 주사 후, 9명의 환자에서 각각 자극성 디스크 조영술과 요추면 관절 주사를 시행했습니다. 환자 중 어느 누구도 양성 반응을 보이지 않았습니다.

슬립만 등(74)은 주사로 확인된 SI 관절 통증 환자 50명의 통증 의뢰 패턴을 확인하기 위해 후향적 연구를 수행했습니다. Fortin 등(72)과 Schwarzer 등(30)의 연구 결과와 달리, 저자들은 SI 관절통의 가장 일반적인 의뢰 패턴이 엉덩이(94%), 요추부(72%), 하지(50%), 사타구니(14%), 요추부(6%), 복부(2%)로 나타났다는 것을 발견했습니다. 환자의 28%는 무릎 아래로 방사되는 통증을 경험했으며, 12%는 발 통증을 호소했습니다. 기존 데이터에 따르면 SI 관절 통증 환자를 식별하는 가장 일관된 요인은 주로 L5 극돌기(30,59,72-74) 아래에 국한된 편측 통증(양쪽 관절이 모두 영향을 받지 않는 한)입니다.

Diagnostic Blocks

It is often assumed that an analgesic response to a properly performed diagnostic block is the most reliable method to diagnose SI joint pain. Although this may seem to be self-evident, the validity of intraarticular SI joint blocks remains unproven. There are many factors that can impact on the sensitivity and specificity of diagnostic blocks. These include the placebo effect, convergence and referred pain, neuroplasticity and central sensitization, expectation bias, unintentional sympathetic blockade, systemic absorption of LA, and psychosocial issues (75). In addition, SI joint block can be one of the most challenging spinal injection procedures. Extravasation of LA to surrounding pain-generating structures such as muscles, ligaments, and lumbosacral nerve roots can lead to false-positive blocks. Conversely, failure to obtain adequate LA spread to the anterior and cephalad portions of the SI joint can result in false-negative blocks. In a classic study by North et al. (76) examining the specificity and sensitivity of a battery of lumbosacral LA blocks in 33 patients with a chief complaint of sciatica, the authors found the specificity of all blocks to be exceedingly low. SI joint blocks were not performed in this study.

In a pilot study by Fortin et al. (72) mapping SI joint referral patterns in asymptomatic volunteers, extravasation of contrast (mean 1.6 mL injected) occurred in 9 of 10 subjects during SI joint injection, with half having at least moderate spread outside the joint. After the injection of LA, 40% of subjects noted lower extremity numbness, indicating inadvertent anesthetization of the lumbosacral nerve roots. In the Maigne et al. (31) study, 3 of the initial 67 patients were excluded because of “sciatic palsy” after the screening block and another 7 were excluded because penetration of the SI joint was impossible. Other investigators have reported much less frequent (<5%) failure rates with fluoroscopically guided SI joint injections (30,59,77). Technical difficulties may be more frequently encountered in elderly patients and those with spondylarthropathies, in whom degenerative changes are more pronounced. If persistent difficulties entering the SI joint are encountered using fluoroscopy, the 3-dimensional imaging capabilities of CT may facilitate entry into the joint (34, 78) (Fig. 3).

진단 블록
제대로 시행된 진단적 차단에 대한 진통 반응이 SI 관절 통증을 진단하는 가장 신뢰할 수 있는 방법이라고 생각하는 경우가 많습니다. 이는 자명해 보일 수 있지만, 관절 내 SI 관절 블록의 유효성은 아직 입증되지 않았습니다. 진단 블록의 민감도와 특이도에 영향을 미칠 수 있는 요인은 여러 가지가 있습니다. 여기에는 위약 효과, 수렴 및 참조 통증, 신경 가소성 및 중추 감작, 기대 편향, 의도하지 않은 교감 차단, LA의 전신 흡수 및 심리 사회적 문제(75)가 포함됩니다. 또한 SI 관절 차단은 가장 까다로운 척추 주사 시술 중 하나가 될 수 있습니다. LA가 근육, 인대, 요천추 신경근과 같은 주변 통증 유발 구조로 퍼지면 위양성 차단으로 이어질 수 있습니다. 반대로, SI 관절의 앞쪽과 두부 부분으로 LA를 충분히 퍼뜨리지 못하면 위음성 차단이 발생할 수 있습니다. 좌골 신경통을 주로 호소하는 33명의 환자를 대상으로 요천추 LA 차단술의 특이도와 민감도를 조사한 North 등(76)의 고전적인 연구에서 저자는 모든 차단술의 특이도가 매우 낮다는 것을 발견했습니다. 이 연구에서는 SI 관절 블록을 시행하지 않았습니다.
무증상 지원자의 SI 관절 차단 패턴을 매핑한 Fortin 등(72)의 파일럿 연구에서 SI 관절 주사 중 10명 중 9명에서 조영제 혈관 외 유출(평균 1.6 mL 주입)이 발생했으며, 절반은 관절 밖으로 최소 중간 정도 퍼진 것으로 나타났습니다. LA 주사 후 피험자의 40%가 하지 마비 증상을 보였는데, 이는 요천추 신경근의 부주의한 마취를 나타냅니다. Maigne 등(31)의 연구에서 초기 67명의 환자 중 3명은 선별 차단술 후 “좌골 마비”로 인해 제외되었고, 나머지 7명은 SI 관절의 관통이 불가능하여 제외되었습니다. 다른 연구자들은 형광 투시 유도 SI 관절 주사의 실패율이 훨씬 더 적다고 보고했습니다(30,59,77). 퇴행성 변화가 더 뚜렷한 노인 환자와 척추 관절 병증이 있는 환자에게는 기술적 어려움이 더 자주 발생할 수 있습니다. 형광 투시법을 사용하여 SI 관절에 지속적으로 진입하는 데 어려움이 있는 경우, CT의 3차원 영상 기능이 관절 진입을 용이하게 할 수 있습니다(34, 78)(그림 3).

Figure 3.: 

Anteroposterior fluoroscopic image demonstrating a right-sided sacroiliac joint block with minimal extra-articular extravasation of contrast.

Regardless of the imaging modality used to confirm‎ intraarticular injection, SI joint injections should never be performed blindly. Rosenberg et al. (79) performed a double-blind study in 37 patients (39 joints) to determine the accuracy of clinically guided SI joint injections using CT imaging as the standard. The authors found that intraarticular injection was accomplished in only 22% of patients, whereas sacral foraminal spread occurred 44% of the time. In 3 patients, no contrast was seen on CT scanning, indicating probable vascular uptake. In 24% of injections, contrast extended into the epidural space.

As for facet blocks, some experts have advocated using a series of SI joint blocks to reduce the incidence of false-positives. In a prospective study involving 67 patients with unilateral LBP, SI joint-compatible referral patterns and joint tenderness, Maigne et al. (31) sought to determine the preval‎ence of SI joint pain using a series of blocks with 2 different LA. In the 54 patients who completed the study, 19 obtained ≥75% pain relief with the lidocaine screening block. After the bupivacaine confirm‎atory block, only 10 of the 19 patients achieved ≥75% pain relief lasting 2 or more hours, for a preval‎ence rate of 18.5%. The false-positive rate of 17% in this study is less than that previously reported for lumbar facet blocks (80). Yet without a diagnostic “gold standard,” there is no way of determining how many true positives were false positives and how many false positives were actually true positives. In clinical practice confirm‎atory SI joint blocks are almost never performed because a) the block itself is considered to be definitive treatment; b) double-blocks are not cost-effective (81); and c) the negative consequences of obtaining a false false-positive block (misdiagnosing true SI joint pain) outweigh the ramifications of overdiagnosing the condition. In summary, there is no infallible, universally accepted method for diagnosing pain originating in the SI joint(s).

관절 내 주사를 확인하는 데 사용되는 영상 방식에 관계없이 SI 관절 주사는 절대로 맹목적으로 시행해서는 안 됩니다. Rosenberg 등(79)은 37명의 환자(39개 관절)를 대상으로 이중맹검 연구를 수행하여 CT 영상을 표준으로 사용하여 임상적으로 유도된 SI 관절 주사의 정확성을 확인했습니다. 저자들은 환자의 22%에서만 관절 내 주사가 성공한 반면 천골공 확산은 44%에서 발생한다는 사실을 발견했습니다. 3명의 환자에서는 CT 스캔에서 조영제가 나타나지 않아 혈관 흡수 가능성이 있는 것으로 나타났습니다. 24%의 주사에서는 조영제가 경막외 공간으로 확장되었습니다.

패싯 블록의 경우, 일부 전문가들은 위양성 발생률을 줄이기 위해 일련의 SI 조인트 블록을 사용해야 한다고 주장했습니다. 일측성 LBP, SI 관절 호환성 의뢰 패턴 및 관절 압통을 가진 67명의 환자를 대상으로 한 전향적 연구에서 Maigne 등(31)은 2가지 다른 LA를 사용한 일련의 블록을 사용하여 SI 관절 통증의 유병률을 확인하고자 했습니다. 연구를 완료한 54명의 환자 중 19명이 리도카인 스크리닝 블록으로 75% 이상의 통증 완화 효과를 얻었습니다. 부피바카인 확진 차단 후 19명의 환자 중 10명만이 2시간 이상 지속되는 75% 이상의 통증 완화를 달성하여 유병률이 18.5%로 나타났습니다. 이 연구에서 17%의 위양성률은 이전에 보고된 요추면 차단술의 위양성률(80%)보다 낮은 수치입니다. 그러나 진단 '골드 스탠다드'가 없으면 얼마나 많은 위양성이 위양성인지, 얼마나 많은 위양성이 실제로는 진양성인지 확인할 방법이 없습니다. 임상에서 확진 SI 관절 차단술은 거의 시행되지 않는데, 그 이유는 a) 차단술 자체가 결정적인 치료로 간주되고, b) 이중 차단술은 비용 효율적이지 않으며(81), c) 거짓 위양성 차단(실제 SI 관절 통증 오진)으로 인한 부정적인 결과가 질환을 과잉 진단할 때의 결과보다 더 크다는 점 때문입니다. 요약하면, SI 관절에서 발생하는 통증을 진단하는 데 있어 정확하고 보편적으로 인정되는 방법은 없습니다.

Treatment

The treatment of SI joint pain is widely acknowledged to be one of the most challenging problems confronting pain physicians. Evidence supporting this statement can be seen by the plethora of different therapies that have been advocated for this disorder. Generally, these treatments can be divided into 2 categories: those directed at correcting the underlining pathology and those aimed at alleviating symptoms. For both of these categories, the evidence supporting any one therapy is limited by the lack of controlled outcome studies.

Psychosocial Issues

Recent studies have provided incontrovertible evidence that psychopathology and other psychosocial factors can influence both the development of chronic pain conditions and the response to treatment. In a study by Polatin et al. (82) conducted in 200 chronic LBP patients, the authors found that 77% met lifetime criteria and 59% demonstrated current symptoms for at least one psychiatric diagnosis, with the most common being depression, substance abuse, and anxiety disorders. Notably, more than 50% of those with depression and more than 90% of patients with substance abuse or an anxiety disorder experienced symptoms before the onset of LBP. Most, but not all, studies have shown untreated psychopathology to negatively affect LBP treatment outcomes (83).

In addition to psychiatric illness, social factors have been demonstrated to impact the prognosis of LBP. These include return-to-work issues, secondary gain, catastrophizing, poor role models, codependency behavior, inadequate coping mechanisms, and attitudes, beliefs, and expectations (84). To optimize outcomes, the identification and treatment of concomitant psychosocial issues is of paramount importance. This is best accomplished via a multidisciplinary approach.

Conservative Management

The non-interventional management of SI joint pain should ideally address the underlining pathology. In patients with true or apparent leg length discrepancy, this might include the use of shoe inserts to more equitably distribute the load borne by the SI joints. Because leg length discrepancies are frequently found in asymptomatic individuals (37) and many patients already compensate for their lower extremity length difference by altering their gait or posture, most experts recommend starting out cautiously with inserts that correct only half the incongruity. For SI joint pain resulting from altered gait mechanics and spine malalignment, physical therapy and osteopathic or chiropractic manipulation have been reported to reduce pain and improve mobility (85,86). However, there are no prospective, controlled studies supporting these modalities.

Nonsurgical stabilization programs have been advocated for SI joint pain. These range from the application of pelvic belts that reduce the sagittal rotation of incompetent SI joints in pregnant women (87,88) to exercise-induced pelvic stabilization programs (89). In a study by Mooney et al. (89), the authors found that 5 women with injection-confirmed SI joint pain had electromyographic-documented hyperactivity of the ipsilateral gluteus muscles and contralateral latissimus muscle compared with 15 asymptomatic control patients. After a 2-1/2 month exercise program, all 5 patients achieved a significant reduction in pain and a return of myoelectric activity to normal patterns.

Ankylosing spondylitis (AS), the most well known and studied spondylarthropathy, is an inflammatory rheumatic disease characterized by spine and SI joint involvement that manifests as spondylitis and sacroiliitis. There are numerous studies assessing the efficacy of various pharmacologic treatment modalities in AS and other spondylarthropathies, but the conclusions that can be drawn from these studies are limited by several factors. These include the protean nature of rheumatic involvement, the systemic manifestations accompanying the disorders, and the fact that although the outcome measures generally include changes in pain complaints and mobility, most do not specifically address SI joint pain. Table 3 lists the evidence supporting various pharmacotherapies for AS and other spondylarthropathies.

Table 3: 

Evidence Supporting Various Pharmacologic Therapies in Spondylarthropathies

Intraarticular Injections

Intraarticular injections with steroid and LA often serve the dual function of being therapeutic and aiding in diagnosis. To summarize these studies, most but not all investigators have found radiologically guided SI joint injections to provide good to excellent pain relief lasting from 6 mo to 1 yr (Table 4). Along with a multitude of studies demonstrating prolonged pain relief after intraarticular SI joint steroid injections, double-blind studies have shown a beneficial effect for periarticular corticosteroid treatment as well (35,36).

Table 4: 

Clinical Studies Eval‎uating Corticosteroid Injections for Sacroiliac (SI) Joint Pain

Radiofrequency Denervation Procedures

Several investigators have performed radiofrequency (RF) denervation procedures in an attempt to provide prolonged pain relief to patients suffering SI joint pain. The techniques used have ranged from denervating the nerves supplying the SI joint (90–92) to cre-ating lesions in the joint itself (93), with one study using a combination of the two (94). The success rates of studies targeting the nerve supply are higher than those focusing on the joint itself, with approximately two thirds of patients reporting significant pain relief. The major drawback to percutaneous RF denervation procedures is that they should not be expected to alleviate pain emanating from the ventral SI joint. In the study by Schwarzer et al. (30), ventral capsular pathology was shown to account for 69% of all CT pathology in the 13 patients with a positive response to diagnostic SI joint blocks. Complicating matters further are that the nerves lesioned during RF procedures innervate other pain-generating structures besides the SI joint, and the SI joint is likely innervated by other nerves inaccessible for denervation (Table 5).

Table 5: 

Clinical Studies Eval‎uating Radiofrequency Procedures in the Treatment of Sacroiliac Joint Pain

Surgical and Other Invasive Interventions

In 1999, Srejic et al. (95) reported 12–16 mo of significant pain relief in 4 patients with SI joint pain who received a series of 3 intraarticular injections with hyaluronic acid. Three of these patients had postsurgical SI joint pain and one suffered from severe osteoarthritis of the spine. The rationale for this treatment stems from studies demonstrating long-term pain relief with hyaluronic acid injections in degenerative joint disease of the knee (96). However, one meta-analysis found only scant evidence for the use of viscosupplementation in knee osteoarthritis, especially when lower molecular weight hyaluronate formulations are used (97). In addition to questionable efficacy, another factor that mitigates against intraarticular hyaluronic acid injections for SI pain is that degenerative joint disease accounts for only a small percentage of cases.

Proliferative therapy (a.k.a. “prolotherapy”) has been advocated as a treatment for nonspecific LBP and SI joint pain (98). The rationale behind the use of “prolotherapy” is that the ligaments and other soft tissue structures are of primary importance in the development of LBP. Thus, the injection of a drug promoting fibroblast hyperplasia should theoretically increase the strength and reduce sensitization of these structures. In a double-blind study, Ongley et al. (99) found that LBP patients who received 6 wk of proliferant therapy had lower pain scores and disability indices at their 6-mo follow-up than “control” patients who received saline injections. Despite these findings, the lack of specific diagnoses, the numerous other treatment differences between groups, and the targeting of pain generators outside the SI joints limit the relevance of this study.

In patients with SI joint pain unresponsive to more conservative measures, several investigators have advocated surgical stabilization. Unfortunately, all published reports on SI joint fusion have been small case series or retrospective studies. Whereas the primary indications for SI joint fixation are either joint instability or fractures (100,101), successful arthrodesis has also been reported for degenerative joint disease (102). In some patients, successful stabilization can be done percutaneously using CT guidance (103). Regardless of the underlying etiology, based on the existing studies the long-term success rate for SI joint fusion appears to be in the range of 70% (100–102). Neuroaugmentation of the third sacral nerve root has also been reported to provide adequate pain relief in 2 patients with severe SI joint pain unresponsive to conventional therapy (104).

Conclusions

The SI joint is a real yet underappreciated pain generator in an estimated 15% to 25% of patients with axial LBP. Whereas historical and physical examination findings have been previously advocated as useful tools in identifying patients with SI joint pain, more recent studies have demonstrated they have limited diagnostic value. Presently, small-volume diagnostic blocks remain the most commonly used method for diagnosing this disorder, although their validity remains unproven. Owing to the complexity of the joint, the mechanisms of SI pain are numerous and ill-defined. When a pathological condition such as leg length discrepancy or altered gait mechanics is present, correcting the underlying defect is the safest and most reliable treatment option. Intraarticular and periarticular corticosteroid injections have been shown in most, but not all, studies to provide good to excellent pain relief lasting up to 10 mo in patients with and without spondylarthropathy. One promising area in the treatment of SI joint pain is RF denervation, although the conclusions that can be drawn are limited by the heterogeneous methods used and the lack of controlled studies.

References

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