The SI joint is a synovial joint with hyaline cartilage on the sacral side of the joint [4]. It is believed that the joint is entirely innervated by the sacral dorsal rami [5]. The joint is mostly a bony structure supported by a number of ligaments and the surrounding muscles. The joint shares these muscles with the hip joint and is subject to all the same shear forces that the hip experiences [4]. SI joint pain is commonly due to trauma or strain. Repetitive motions associated with athletic activities can also cause repetitive shear .

Lumbar disc degeneration is a known cause of persistent groin pain [21]. The groin is innervated by the genitofemoral and ilioinguinal nerves; degeneration of the spinal canal can cause referred pain to the groin. In particular, patients with herniated discs (most commonly in the L4–L5 or L5–S1 levels) have been known to report groin pain [21]. These discs can cause compression on transversing sacral nerve roots (S1–S3). Additionally, herniation at the L1/L2 levels is rarer but can cause characteristic symptoms of groin pain, manifesting as buttock pain and anterolateral thigh pain [22].

Stenosis is defined as the narrowing of the spinal canal, usually to an absolute diameter of less than 75 mm² as characterized by imaging [27]. Similar to degeneration, nerve root stenosis at the L1/L2 levels will affect the L2/L3 nerve roots, manifesting in a positive femoral stretch test and anterolateral thigh pain [28]. Imaging is not definitive; in one study, more than 30 % of patients had images consistent with lumber stenosis but did not feel any of the associated symptoms [29]. Diagnosis is made through physical examination using similar tests reported for SI joint dysfunction, as well as through exclusion of other possible diagnoses. Once diagnosed, the most effective treatment for spinal stenosis involves patient education, therapy, exercise, and training [27]. For symptoms of pain, exercises that focus on strengthening the muscles involved in thoracic extension and lumbar rotation were found to be most effective in relieving pain [30, 31], presumably because these types of exercises were the most important for increasing flexibility in the groin region. Intervention for severe spinal stenosis includes epidural steroid injections and surgery. Injections have increased in popularity in recent years, but their efficacy has been controversial [32]. Surgical versus nonsurgical approaches have recently been evaluated by the Spine Patient Outcome Study (SPORT) [33]; the authors concluded that patients with degenerative spondylolisthesis treated with surgery had significantly better outcomes at four years compared to those who were managed noninvasively. The outcomes for patients with stenosis without spondylolisthesis were not as clearly defined.

Herniated discs are one of the most common discogenic causes of groin pain. The most common sites of herniation are at the L4–5 and L5–S1 levels. Additionally, other sites of herniation that will manifest as groin pain include the L1/L2 and S3/S4 levels. S3/S4 involvement likely is not due to direct S3/4 disc herniation, rather by S3/4 nerve root compression by more rostral disc herniations (i.e., L4–5 or L5–S1). L1/L2 disc herniation will localize to the inner thigh, while a herniation that affects the S3/S4 level will localize to the scrotal region. It is believed that decreased hydration of the annular disc leads to decreased ability of the disc to cushion load. This dehydration can be due to age, genetics, and environmental factors. A sharp stabbing pain that radiates down to the extremities below the knees is highly suggestive of herniation [34]. On physical exam, increased pressure on the annular fibers of the disc will help distinguish herniation from low back pain, which is typically made worse by twisting motions of the lower back muscles. The straight leg raise is usually indicative of a pinched nerve or nerve root.

Nonsurgical approaches to the management of a herniated disc are similar to those for other forms of disc degeneration. These approaches include physical therapy, focused exercises, and epidural injections. The natural history of lumbar herniated disc is that a majority of patients will resolve their symptoms without intervention given enough time. Surgery may be indicated in severe cases that cause significant pain or disability and also in cauda equina syndrome [34].

Spondylolisthesis refers to anterior subluxation of the vertebral body that is caused by a defect in the pars interarticularis [35]. Spondylolisthesis falls into three categories: spondylolysis, isthmic, and degenerative [36]. Isthmic is the most common form, occurring in 4–8 % of the general population and is found twice as often in males compared to females [37]. Although isthmic spondylolisthesis can usually be detected in childhood, patients usually do not present with symptoms until later in life. Presenting symptoms include pain in the lumbar area that can manifest as groin pain that radiates into the buttocks and thighs [37]. The pain can be exacerbated with weight lifting maneuvers or Valsalva. Higher grade spondylolisthesis can also manifest in hamstring tightness [37]. Degenerative spondylolisthesis usually presents much later in life and is caused by long-standing instability in the lumbar segments. The instability is most frequently due to arthritis, malfunction of the ligaments stabilizing the lumbar joints, or ineffective muscle stabilization [38]. The treatment for spondylolisthesis is dependent on the extent of listhesis. Most patients who present are asymptomatic and can be managed nonoperatively using modalities such as steroid injections, brace therapy, and restriction of heavy lifting and intense athletic activities [37]. When nonoperative therapies fail, surgical intervention may be needed. Generally, the indications for surgery include (1) persistence of debilitating pain and function, (2) progression of listhesis greater than 30 %, and (3) cosmetic deformities that result in functional disability [37]. Typical surgical procedures involve decompression and fusion of the segments undergoing listhesis.