ANATOMY-IMAGING SELF-
SCORED SELF-ASSESSMENT
EXAMINATION
AAOS 2025
,Anatomy-Imaging Self-Scored Self-Assessment Examination 2025 Ahmed Altaei
Question 1 of 100
Figures 1a and 1b are the MR images of a 69-year-old woman with bilateral leg pain that is worse
with ambulation. She feels better when she is sitting down or leaning on a grocery cart. Which
condition or structure is indicated by the arrows?
1- Disk herniation
2- Synovial cyst
3- Arachnoid cyst
4- Epidural lipomatosis
PREFERRED RESPONSE: 2- Synovial cyst
DISCUSSION
This patient has neurogenic claudication as demonstrated by her “shopping cart” sign. Typically,
spinal stenosis is attributable to bony spurs and/or a thick ligamentum flavum. However, for this
patient, a large synovial cyst is the main contributing factor to stenosis. A cyst typically is filled
with gelatinous material. If symptomatic, surgical excision is typically recommended because
success with aspiration is unreliable. The need for fusion is debatable.
A disk herniation is not bright on T2. An arachnoid cyst is a sac filled with cerebrospinal fluid.
Spinal arachnoid cysts are relatively uncommon, and typically are intradural, but they also can be
extradural. Epidural lipomatosis is a condition caused by excessive accumulation of fat within the
epidural space. It is not well circumscribed as seen with this lesion.
RECOMMENDED READINGS
• Epstein NE, Baisden J. The diagnosis and management of synovial cysts: Efficacy of surgery versus
cyst aspiration. Surg Neurol Int. 2012;3(Suppl 3):S157-66. doi: 10.4103/2152-7806.98576. Epub 2012
Jul 17. PubMed PMID: 22905322. View Abstract at PubMed
• Xu R, McGirt MJ, Parker SL, Bydon M, Olivi A, Wolinsky JP, Witham TF, Gokaslan ZL, Bydon A.
Factors associated with recurrent back pain and cyst recurrence after surgical resection of one hundred
ninety-five spinal synovial cysts: analysis of one hundred sixty-seven consecutive cases. Spine (Phila
Pa 1976). 2010 May 1;35(10):1044-53. PubMed PMID: 20173680. View Abstract at PubMed
1
,Anatomy-Imaging Self-Scored Self-Assessment Examination 2025 Ahmed Altaei
Question 2 of 100
Figures 2a and 2b are the clinical photographs taken at the time of cubital tunnel surgery. The ulnar
nerve is indicated by the red arrow. What is the name of the structure at the tip of the blue arrow?
1- Extensor digitorum manus
2- Anconeus epitrochlearis
3- Medial triceps
4- Flexor carpi medialis
PREFERRED RESPONSE: 2- Anconeus epitrochlearis
DISCUSSION
The clinical photographs reveal an anconeus epitrochlearis. This is an atavistic or anomalous
muscle that originates on the medial olecranon (ulna) and inserts on the medial epicondyle. It is
widely present in animals that move their elbows in the coronal plane. The anconeus epitrochlearis
muscle may be contributing a factor to the development of cubital tunnel syndrome. When present,
this muscle can compress the ulnar nerve and should be released.
RECOMMENDED READINGS
• Masear VR, Meyer RD, Pichora DR. Surgical anatomy of the medial antebrachial cutaneous nerve. J
Hand Surg Am. 1989 Mar;14(2 Pt 1):267-71. PubMed PMID: 2703673. View Abstract at PubMed
• Masear VR, Hill JJ Jr, Cohen SM. Ulnar compression neuropathy secondary to the anconeus
epitrochlearis muscle. J Hand Surg Am. 1988 Sep;13(5):720-4. PubMed PMID: 3241044. View
Abstract at PubMed
Question 3 of 100
Which nerve is at greatest risk in the setting of an anterior shoulder dislocation?
1- Axillary
2- Musculocutaneous
3- Radial
4- Suprascapular
PREFERRED RESPONSE: 1- Axillary
2
, Anatomy-Imaging Self-Scored Self-Assessment Examination 2025 Ahmed Altaei
DISCUSSION
A traumatic primary anterior shoulder dislocation puts the axillary nerve at greatest risk for a
traction injury. Lesions in the suprascapular nerve, radial nerve, musculocutaneous nerve, and
ulnar nerve are less common (in respective decreasing frequency). When other nerve injuries are
present, an associated axillary nerve palsy usually is involved.
RECOMMENDED READINGS
• de Laat EA, Visser CP, Coene LN, Pahlplatz PV, Tavy DL. Nerve lesions in primary shoulder
dislocations and humeral neck fractures. A prospective clinical and EMG study. J Bone Joint Surg Br.
1994 May;76(3):381-3. PubMed PMID: 8175837. View Abstract at PubMed
• Lynch JR, Clinton JM, Dewing CB, Warme WJ, Matsen FA 3rd. Treatment of osseous defects
associated with anterior shoulder instability. J Shoulder Elbow Surg. 2009 Mar-Apr;18(2):317-28. doi:
10.1016/j.jse.2008.10.013. Review. PubMed PMID: 19218054. View Abstract at PubMed
• Pavlov H, Warren RF, Weiss CB Jr, Dines DM. The roentgenographic evaluation of anterior shoulder
instability. Clin Orthop Relat Res. 1985 Apr;(194):153-8. PubMed PMID: 3978907. View Abstract at
PubMed
CLINICAL SITUATION FOR QUESTIONS 4 THROUGH 7
An 18-year-old woman was skateboarding when she fell and sustained the injury seen in Figures
4a through 4c.
Question 4 of 100
What is the most serious outcome associated with this injury?
1- Osteonecrosis
2- Subtalar arthritis
3- Wound necrosis
4- Complex regional pain syndrome
3
SCORED SELF-ASSESSMENT
EXAMINATION
AAOS 2025
,Anatomy-Imaging Self-Scored Self-Assessment Examination 2025 Ahmed Altaei
Question 1 of 100
Figures 1a and 1b are the MR images of a 69-year-old woman with bilateral leg pain that is worse
with ambulation. She feels better when she is sitting down or leaning on a grocery cart. Which
condition or structure is indicated by the arrows?
1- Disk herniation
2- Synovial cyst
3- Arachnoid cyst
4- Epidural lipomatosis
PREFERRED RESPONSE: 2- Synovial cyst
DISCUSSION
This patient has neurogenic claudication as demonstrated by her “shopping cart” sign. Typically,
spinal stenosis is attributable to bony spurs and/or a thick ligamentum flavum. However, for this
patient, a large synovial cyst is the main contributing factor to stenosis. A cyst typically is filled
with gelatinous material. If symptomatic, surgical excision is typically recommended because
success with aspiration is unreliable. The need for fusion is debatable.
A disk herniation is not bright on T2. An arachnoid cyst is a sac filled with cerebrospinal fluid.
Spinal arachnoid cysts are relatively uncommon, and typically are intradural, but they also can be
extradural. Epidural lipomatosis is a condition caused by excessive accumulation of fat within the
epidural space. It is not well circumscribed as seen with this lesion.
RECOMMENDED READINGS
• Epstein NE, Baisden J. The diagnosis and management of synovial cysts: Efficacy of surgery versus
cyst aspiration. Surg Neurol Int. 2012;3(Suppl 3):S157-66. doi: 10.4103/2152-7806.98576. Epub 2012
Jul 17. PubMed PMID: 22905322. View Abstract at PubMed
• Xu R, McGirt MJ, Parker SL, Bydon M, Olivi A, Wolinsky JP, Witham TF, Gokaslan ZL, Bydon A.
Factors associated with recurrent back pain and cyst recurrence after surgical resection of one hundred
ninety-five spinal synovial cysts: analysis of one hundred sixty-seven consecutive cases. Spine (Phila
Pa 1976). 2010 May 1;35(10):1044-53. PubMed PMID: 20173680. View Abstract at PubMed
1
,Anatomy-Imaging Self-Scored Self-Assessment Examination 2025 Ahmed Altaei
Question 2 of 100
Figures 2a and 2b are the clinical photographs taken at the time of cubital tunnel surgery. The ulnar
nerve is indicated by the red arrow. What is the name of the structure at the tip of the blue arrow?
1- Extensor digitorum manus
2- Anconeus epitrochlearis
3- Medial triceps
4- Flexor carpi medialis
PREFERRED RESPONSE: 2- Anconeus epitrochlearis
DISCUSSION
The clinical photographs reveal an anconeus epitrochlearis. This is an atavistic or anomalous
muscle that originates on the medial olecranon (ulna) and inserts on the medial epicondyle. It is
widely present in animals that move their elbows in the coronal plane. The anconeus epitrochlearis
muscle may be contributing a factor to the development of cubital tunnel syndrome. When present,
this muscle can compress the ulnar nerve and should be released.
RECOMMENDED READINGS
• Masear VR, Meyer RD, Pichora DR. Surgical anatomy of the medial antebrachial cutaneous nerve. J
Hand Surg Am. 1989 Mar;14(2 Pt 1):267-71. PubMed PMID: 2703673. View Abstract at PubMed
• Masear VR, Hill JJ Jr, Cohen SM. Ulnar compression neuropathy secondary to the anconeus
epitrochlearis muscle. J Hand Surg Am. 1988 Sep;13(5):720-4. PubMed PMID: 3241044. View
Abstract at PubMed
Question 3 of 100
Which nerve is at greatest risk in the setting of an anterior shoulder dislocation?
1- Axillary
2- Musculocutaneous
3- Radial
4- Suprascapular
PREFERRED RESPONSE: 1- Axillary
2
, Anatomy-Imaging Self-Scored Self-Assessment Examination 2025 Ahmed Altaei
DISCUSSION
A traumatic primary anterior shoulder dislocation puts the axillary nerve at greatest risk for a
traction injury. Lesions in the suprascapular nerve, radial nerve, musculocutaneous nerve, and
ulnar nerve are less common (in respective decreasing frequency). When other nerve injuries are
present, an associated axillary nerve palsy usually is involved.
RECOMMENDED READINGS
• de Laat EA, Visser CP, Coene LN, Pahlplatz PV, Tavy DL. Nerve lesions in primary shoulder
dislocations and humeral neck fractures. A prospective clinical and EMG study. J Bone Joint Surg Br.
1994 May;76(3):381-3. PubMed PMID: 8175837. View Abstract at PubMed
• Lynch JR, Clinton JM, Dewing CB, Warme WJ, Matsen FA 3rd. Treatment of osseous defects
associated with anterior shoulder instability. J Shoulder Elbow Surg. 2009 Mar-Apr;18(2):317-28. doi:
10.1016/j.jse.2008.10.013. Review. PubMed PMID: 19218054. View Abstract at PubMed
• Pavlov H, Warren RF, Weiss CB Jr, Dines DM. The roentgenographic evaluation of anterior shoulder
instability. Clin Orthop Relat Res. 1985 Apr;(194):153-8. PubMed PMID: 3978907. View Abstract at
PubMed
CLINICAL SITUATION FOR QUESTIONS 4 THROUGH 7
An 18-year-old woman was skateboarding when she fell and sustained the injury seen in Figures
4a through 4c.
Question 4 of 100
What is the most serious outcome associated with this injury?
1- Osteonecrosis
2- Subtalar arthritis
3- Wound necrosis
4- Complex regional pain syndrome
3
