Scottie dog sign
| Scottie dog sign | |
|---|---|
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| X-ray of lateral lumber spine showing spondylolysis of L5/S1 |
Scottie dog sign is a radiological sign which refers to the appearance of lumbar spine in oblique view X-ray.[1] It was once used as a diagnostic sign in x-rays for lumbar spondylolysis, but it is not commonly in use nowadays because of the advent of more sensitive diagnostic methods such as the CT scan and MRI scan.[2]
Radiological appearance
On lumbar x-ray, a Scottie dog can be seen laterally, with the pedicle as the eye, transverse process as the nose, superior articular facet as the ear, spinous process as the body, and inferior articular facet as the front leg[3]. The pars interarticularis defect presents itself as the neck of the dog. Since plain radiographs have limitations and are not as sensitive, initial diagnosis is made by plain xray followed by MRIs to confirm the diagnosis. [4] CT scans are then used to rule out other lesions and to assess healing during treatment.
Clinical relevance
Risk factors
Environmental stress such as repetitive motion or weight bearing are common risk factors for developing spondylosis[5]. There's a proportionate increase in relation to age up until the age of 18, presumed to be due to weight bearing. Although spondylolysis is less common in children, it is the leading cause of low back pain in adolescent athletes, especially those in spinal extension intensive sports such as gymnastic, baseball, rowing, and soccer. Race and sex may also play a risk as caucasian male are most commonly affected followed by African American males, Caucasian females, and African American females. Spinal deformities also puts patients at a higher risk of spondylolysis. A study in Japan showed patients with spina bifida occulta had almost four times increase in the incidence of spondylolysis, likely due to failure of vertebral arch fusion leading to increased stress on the pars interarticularis and eventually its fracture.[5] Patients with Scheuermann's kyphosis have also been reported to have thirty to fifty percent incidence rate of spondylolysis, likely due to the anatomical nature of lumbar lordosis and excessive lumber extension.
Symptoms
Spondylolysis most commonly presents asymptomatic and found incidentally on imaging, however, its most common complaint is lower back pain that is relieved with rest and aggravated by movement[5]. On physical exam, midline tenderness also a sign of spondylolysis.
Management
First line therapy for patients with spondylolysis is conservative management such as restricting activity, physical therapy, bracing, and external electrical stimulation.[5] Each of these therapies can be used individually, however, there's greater efficacy and recovery with combination therapy. Conservative treatment's goal is to heal the spinal defect, prevent worsening of the lesion, and provide symptomatic relief for the patient. Typically spinal bracing is used after a failed trial of activity modification and is seen more effective in younger patients, likely due to decreased initiation of bone healing.[5] External electrical stimulation can also be used to repair bone fractures by increasing bone-forming stem cells, inducing mineralization of the bone, forming extracellular matrix, and increasing the expression of osteogenic genes. Studies show the combination of cessation of sports, spinal bracing, and bone stimulator followed by physical therapy and rehab in adolescent athletes with spondylolysis results in great outcomes such as resuming sports.[4]
Surgical treatment such as decompression or decompression and fusion is considered when over 6 months conservative therapy fails to decrease pain, associated symptoms, along with persistent fracture shown on imaging.[5] Decompression consists of a laminectomy, which removes part of the vertebra, while fusion joins the vertebrae together.[6] Decompression alone is an option if the spine appears to be stable with an intact posterior arch, however, not recommended as there's a twenty five to thirty percent progression to slippage. Decompression and fusion is the primary surgical treatment for spondylolysis as it's more stable.
References
- ↑ Millard, L. (January 1976). "The Scotty dog and his collar". The Journal of the Arkansas Medical Society. 72 (8): 339–40. PMID 129461.
- ↑ Morimoto, Masatoshi; Sakai, Toshinori; Goto, Tsuyoshi; Sugiura, Kosuke; Manabe, Hiroaki; Tezuka, Fumitake; Yamashita, Kazuta; Takata, Yoichiro; Chikawa, Takashi; Sairyo, Koichi (29 May 2018). "Is the Scotty Dog Sign Adequate for Diagnosis of Fractures in Pediatric Patients with Lumbar Spondylolysis?". Spine Surgery and Related Research. 3 (1): 49–53. doi:10.22603/ssrr.2017-0099. ISSN 2432-261X. PMC 6690120. PMID 31435551.
- ↑ Baig, MN; Byrne, Fergus; Devitt, A; McCabe, J P (2018). "Signs of Nature in Spine Radiology". Cureus. 10 (4) e2456. doi:10.7759/cureus.2456. ISSN 2168-8184. PMC 5991933. PMID 29888160.
- 1 2 Choi, Jeffrey H.; Ochoa, Jonathan K.; Lubinus, Ariadna; Timon, Stephen; Lee, Yu-po; Bhatia, Nitin N. (2022-10-01). "Management of lumbar spondylolysis in the adolescent athlete: a review of over 200 cases". The Spine Journal. 22 (10): 1628–1633. doi:10.1016/j.spinee.2022.04.011. ISSN 1529-9430.
- 1 2 3 4 5 6 Li, Nathan; Amarasinghe, Sam; Boudreaux, Kyle; Fakhre, Waddih; Sherman, William; Kaye, Alan D. (2022). "Spondylolysis". Orthopedic Reviews. 14 (3) 37470. doi:10.52965/001c.37470. ISSN 2035-8164. PMC 9425520. PMID 36045696.
- ↑ Rustagi, Tarush; Lavelle, William F.; Tallarico, Richard A. (2014-12-01). "Surgical management of adult spondylolysis and spondylolisthesis". Seminars in Spine Surgery. Spondylolysis. 26 (4): 238–246. doi:10.1053/j.semss.2014.09.006. ISSN 1040-7383.