Imaging Corner

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Imaging Case Self-Test

Michelle A Wessely, DC, DACBR (1) and Timothy J Mick, DC, DACBR (2)

(1) Director of Radiology
Institut Franco-Europeen de Chiropratique (IFEC),
24 Boulevard Paul Vaillant Couturier, 94200 Ivry Sur Seine, France
mwessely@ifec.net

2) Imaging Consultants, Inc.
565 Arlington Avenue West, 55117, St. Paul. Minnesota, USA
mickici@msn.com

Published: September, 2009
Journal of the Academy of Chiropractic Orthopedists
September 2009, Volume 6, Issue 3
Received: 16 August 2009
Accepted: 18 September 2009

This review is available from: http://www.dcorthoacademy.com © 2009 Wessely, Mick and the Academy of Chiropractic Orthopedists. This is an Open Access article which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Case presentation
A 27 year old male patient presented to a chiropractor in France, with low back pain which extended in to the left buttock region. On questioning, the patient felt that the pain had started during the previous rugby season and was gradually worsening. The pain travelled down the left leg to the toes initially on occasion and now more constantly. His father, a medical doctor, ordered imaging and having consulted an orthopedic surgeon, recommends surgery. The patient, a medical student, wishes not to have surgery and presented to the teaching clinic for a second opinion.

Imaging had previously been performed, which is presented for analysis – see Figures 1 and 2b.

1. What are the imaging findings?
2. What is the imaging diagnosis?
3. What are the management options available for this patients´ treatment?

Figure 1a.

Figure 1b.

Figure 2a.

Case Discussion

A 27 year old male patient presented to the chiropractor in France, with low back pain which extended in to the left buttock region. On questioning, the patient felt that the pain had started during the previous rugby season and was gradually worsening. The pain travelled down the left leg to the toes initially on occasion and now more constantly. His father, a medical doctor, ordered imaging and having consulted an orthopedic surgeon, is recommended surgery. The patient, a medical student wishes not to have surgery and presented to the teaching clinic for a second opinion. Imaging had previously been performed, which is presented for analysis.

1) What are the imaging findings?

In Figures 1a and b, a focal region of abnormality is noted about the left ischial tuberosity, which has separated from the parent bone. Mild irregularity is noted about the avulsed segment, which is likely due to degenerative enthesopathy. On the false oblique view of Lesquene (Figure 1b) a closer evaluation of the region is possible, demonstrating a subchondral bony margin along the proximal aspect of the avulsed bony fragment, suggestive of being long–standing and of a possible pseudoarticulation.

Figure 1a.

Figure 1b.

In figures 2a through c, CT imaging was performed, figure 2a demonstrating coronal pelvic bone window sections, noting the avulsed fragment with overgrowth of the avulsed fragment as well as evidence of a 3 mm radiolucent gap between the avulsed fragment and parent bone. Similarly in figure 2b, an axial bone window CT section of the pelvis, similar features can be identified, and again in figure 2c, a sagital bone window CT slice through the left ischium demonstrating the avulsed fragment.

Figure 2a.

Figure 2b.

Figure 2c.

In figures 3, MR imaging was performed, in figure 3a, a T1-weighted sequence in the coronal or frontal plane of the pelvis demonstrating the displaced avulsed fragment superolaterally, with an additional smaller fragment medially which is less obviously appreciated on the radiographs and also noted on the CT imaging. STIR coronal (figure 3b) and axial (figure 3c) imaging demonstrates an increase in signal intensity within the avulsed fragment and also in the region between the avulsed segment and parent bone, suggestive of a pseudoarticulation. On the axial image in particular, an image slice performed at the level of the ischial tuberosity, the lateral displacement of the ischial tuberosity fragment is noted which is likely displacing the sciatic nerve (white circle) which may be the cause of the sciatic neuropathy suffered by the patient. At the site of the chronic avulsion is evidence of callus and bony hypertrophy with proliferation of the bone in this region, particularly anteriorly.

Figure 3a.

Figure 3b.

2) What is the imaging diagnosis?

Chronic avulsion injury to the left ischial tuberosity, with the likely development of a pseudoarticulation and compression of the sciatic nerve at the level of the ischial tuberosity.

3) What are the management options available for this patients´ treatment?

The management of chronic avulsion injuries of the ischial tuberosity/apophysis depends on a number of factors, discussed in the text below. However options include conservative management, in particular spinal manipulative therapy and rehabilitative exercises about the pelvic musculature, therapeutic injection into the region, or more interventional procedures including removal of the avulsed fragment.

Discussion

Avulsion injuries occur either in the acute or less commonly in the chronic setting. The mechanism of injury is that of a forceful muscular contraction, which results in the pulling off of a fragment of bone, or periosteum, which may be associated with injury to the tendon of the muscle involved. Avulsion fractures about the pelvis are relatively common, particularly in the adolescent population involved in sports activities, during the development, ossification and then eventual fusion of the apophysis with the parent bone, hence the term traumatic apophysiolysis which may be applied to these types of injuries (1). In the case of the ischial apophysis, the fusion of the apophysis occurs from the age of 16 through to 18, but may be up to 25 years old, being one of the last about the pelvis to fuse. Depending on the type of sports activity, different regions of avulsion will be involved but in the adolescent age group generally involve the newly formed ossification centre or apophysis. Different activities and thus muscular contractions may result in different sites of avulsion injury, though about the pelvis the ischial tuberosity is the most common region, followed by the anterior inferior iliac spine (related to the direct head of the rectus femoris) and then the anterior superior iliac spine (related to sartorius and/or tensor fascia lata). A more uncommon site of avulsion about the pelvis is the iliac apophysis. Avulsion injuries involving the ischial tuberosity, such as in the case illustrated here are particularly common in sports involving kicking, including rugby and soccer, both sports demanding that the player kick and run, athletes who are involved in sprinting and gymnasts involved in performing the “splits” (2).

The patient usually presents acutely following an injury during the sports activity. In the case of the ischial apophysis, tendons of muscles potentially implicated are the adductor magnus, quadratus femoris, and the hamstring group of muscles. Often the patient has to pull up early due to severe pain in the region of the origin of the tendinous attachment to bone referred to the involved ischial tuberosity. The patient is often seen to limp and lack the normal muscular strength of the involved muscle group and indeed on muscle testing, weakness and pain is noted, along with possible soft tissue swelling in the region.

Following clinical examination, a variety of imaging tools are available to assist in confirming the diagnosis. Although radiography would be considered to be the most logical, due to the bony injury, it may not provide the final diagnosis in those cases of subtle avulsion or predominantly periosteal involvement (3). However it remains the benchmark initial imaging tool of choice. It is however important to assess not only the extent of bony avulsion, but the consequences of the avulsion on the tendinous insertion points, and therefore special imaging, particularly MR imaging is very useful to determine this as well as the relationship of the injury to additional structures such as the sciatic nerve. More recently, diagnostic ultrasound has been advocated to determine the bony injury, tendinous and neural involvement but this still remains a challenge form of imaging for general use.

Radiography therefore may demonstrate slight irregularity about the ischial apophysis. Displacement of small flecks of ossification may be noted due to the nature of the avulsion injury. Soft tissue swelling is in general not appreciated on radiography even with the use of digital imaging in this region. Radiography may be used to follow the patients´ recovery in which case, it may be possible to note the progressive ossification of the avulsed fragment, separated from the parent bone. Depending on the age that the injury occurred, if there is a potential for further growth, the avulsed fragment may become sizeable, and has been termed a “Rider´s bone” or “Prussian´s bone”. If the fragment is noted to be separated either at the time of the acute injury or in the recovery or chronic stage, the golden measurement is that of 2 cms., over which orthopedic intervention is recommended, depending on the literature source. Diagnostic ultrasound may also be used in the initial diagnostic phase or as follow up during the following 1 to 2 months to determine the gradual resolution of the inflammatory response associated with the injury as well as in the evaluation of the tendons and associated neural components. MR imaging however is the gold standard in the evaluation of potential sources of complications, particularly the somewhat unusual sciatic nerve impingement (4), as seen with the patient presented in this radiology corner. In addition, as in this patient, evidence of a pseudoarticulation can be appreciated by evidencing fluid signal in either or both the avulsed fragment and parent bone, as well as in the intervening anatomic space. The development of a pseudoarticulation may be an additional source of pain which may be treated conservatively or with therapeutic injection.

The management of ischial apophysis avulsion injuries depends on several factors (5). The degree of displacement of the avulsed fragment is noted, and as commented, if there is more than 2 cms. of displacement the literature suggests orthopedic consultation with a view to potentially surgically fixing the fragment. If there is injury to the tendinous structures, for example to the conjoined tendon, intervention may be considered necessary depending on the degree of disruption and the level of sports activity performed habitually by the patient. If the clinical scenario is one of avulsion injury which is seem to be contributing to sciatic symptoms and signs by virtue of anatomic position and relation to the sciatic nerve, surgery may be considered to relieve the compression. It is useful to perform nerve conduction tests prior to such intervention, following MR imaging to establish the level of compression to assist the surgeon in the surgical approach. Several reports are present in the literature regarding surgery to relieve sciatic symptoms and signs related to a large avulsive fragment although neural recovery was not always complete, even following 2 year follow up. However the pain was reduced for the patient.

Chiropractic management literature is rather limited but an article published in 2006, illustrates a chiropractic management plan to treat a patient with a chronic avulsion of the ischial apophysis suffering with sciatic pain, 6 months following a football injury, a recurrent injury from 3 years previously (6). In the patient presented in the radiology corner, the symptoms reduced to 30% of the original complaint, and the patient was satisfied with this. A combination of spinal manipulative therapy directed to the lumbar spine, sacroiliac joints and pelvic region, soft tissue manual therapy and rehabilitative exercises that are well illustrated in the cited article (6). The patient was symptom free 5-months post-initial treatment. The patient refused surgery that had been offered, and continues to improve particularly with the use of stretching exercises of the pelvic musculature.

Conclusions:

Ischial apophyseal injuries initially occur during adolescence, more commonly in male patients, but this depends on the sport activity that induces the injury. Though the patient may develop immediate pain, in a smaller subgroup symptoms and signs may not manifest until months or years later. Imaging is useful to determine the injury and the potential associated injuries. MR imaging of the pelvis would be recommended, indicating the region of interest, to extend the field of view distally enough in order to capture the region of interest. Alternatively MR imaging of the hip can be performed with similar instructions. Treatment may be conservative, using chiropractic manipulative therapy, soft tissue techniques, or depending on the complaint, therapeutic injection. Only in a selective few patients is surgery anticipated, and this currently tends towards repairing the involved soft tissue structures, particularly the tendinous attachments.

Clinical Pearls:

• The ischial apophysis is the most common
  location of avulsion injury about the pelvis.
• Symptoms usually relate to sports activity or
  forceful sudden muscular contraction.
• Diagnosis is made with the clinical history
  and examination, supported by the use of
  imaging, usually radiography and if
  available MR imaging.

References

1. 1) Freyschmidt´s “Koehler/Zimmer” (2003) Chapter 6. Pelvis. Borderlands of Normal and Early Pathological Findings in Skeletal Radiography. Fifth edition, Thieme, USA, 789-798.
2. 2) Resnick D Chapter 62 Physical injury: Concepts and Terminology. Diagnosis of Bone and Joint disorders, 2002, 4th edition, Volume 3, WB Saunders, USA, 2627-2782
3. 3) Gidwani S, Jagiello J and Bircher M: Avulsion fracture of the ischial tuberosity in adolescents – an easily missed diagnosis. BMJ, 329, 2004, 99- 100
4. 4) Miller A, Stedman GH, Beisaw NE and Gross PT: Sciatic caused by an avulsion fracture of the ischial tuberosity. A case report. J Bone Joint Surg Am. 1987;69:143-145.
5. 5) Salvi AE, Metelli GP, Corona M and Donani MT: Spontaneous healing of an avulsed ischial tuberosity in a young football player. A case report. Acta Orthop. Belg., 2006, 72, 223-225
6. 6) Mayrand N, Forgin J, Descarreaux M and Normand M: Diagnosis and management of posttraumatic piriformis syndrome. JMPT,26(6), 2006 486-491

Useful resources:

http://www.learningradiology.com/archives06/CO W%20205-Ischial%20Avulsion%20Fx/avulseischiumcorrect.htm

http://www.radsource.us/clinic/0702