OITE & AAOS Board Review MCQs – Master Prep Part 229

Question 1

During C1-C2 transarticular screw fixation, screw misplacement is most likely to result in injury to the

Accepted Answer

vertebral artery if the screw is angled too caudally.

Question 2

In a locking plate screw construct, axial forces are borne by which of the following?

Accepted Answer

Plate

Question 3

What is the most common complication following metatarsal osteotomy for a bunion deformity in an adolescent?

Accepted Answer

Recurrence of the hallux valgus

Question 4

A 40-year-old man sustains a fall while mountain biking and presents with a posterior elbow fracture-dislocation. The elbow is reduced in the ER and noted to be grossly unstable with varus and valgus stress. Imaging demonstrates a two part radial hea

Accepted Answer

Splint at 90 degree flexion and full pronationCorrent answer: 4This patient has persistent elbow instability likely secondary to medial collateral ligament (MCL) rupture and therefore should undergo repair of the MCL, followed by repeat fluoroscopic examination. Small coronoid fractures involving less than or equal to 10% of the coronoid tip do not confer major elbow instability and do not necessitate repair.Terrible triad injuries of the elbow are characterized by: 1. Radial head fracture, 2. Coronoid fracture, and 3. Elbow dislocation. Whether to surgically address the coronoid fracture depends on the size of the fragment (Reagan-Morrey types I-III; Illustration A) as well as elbow stability. Reagan and Morrey suggested that small fractures of the coronoid tip (type I) involving less than 10% of the coronoid may represent anterior capsule avulsions; however, recent cadaveric studies demonstrate that the capsule inserts more distally on the tip and that small fractures often do not contain capsule insertion. Gross elbow instability in the presence of a type I fracture is most likely due to an independent MCL injury and NOT the coronoid avulsion. Surgical repair of type I fractures has not been shown to affect stability and may detrimentally affect elbow range of motion.Matthew et al reviewed the terrible triad injury of the elbow. While the coronoid process provides substantial resistance to posterior subluxation, small fractures involving 10% of the coronoid process have been shown to have little effect on elbow stability. In a cadaveric study of a simulated terrible triad injury, when residual instability was present after radial head repair or arthroplasty and lateral ulnar collateral ligament (LUCL) repair, repair of the MCL was more effective than fixation of small coronoid fractures in restoring elbow stability. However, the authors note that in clinical series of terrible triad injuries, most coronoid fragments were larger than 10%, suggesting that fixation of the coronoid process is usually part of the treatment of terrible triad injuries.Papatheodorou et al performed a retrospective analysis of 14 patients with acute terrible triad injuries and type I or type II coronoid fractures whounderwent radial head fixation or arthroplasty and LUCL repair without coronoid fixation. Intraoperative stability was confirmed under fluoroscopy. At 2 year follow up, none of the patients demonstrated elbow instability. Mean elbow flexion-extension was 123 and forearm rotation 145. The authors concluded that terrible triad injuries with type I or II coronoid fractures can be treated without coronoid fixation when intraoperative stability is restored with radial head repair or arthroplasty and LUCL repair.Illustration A demonstrates the Regan-Morrey classification of coronoid fractures. Type I fractures involve < 10% of the coronoid tip and do not result in significant elbow instability. Type II fractures involve < 50% of the coronoid and may result in elbow instability secondary to loss of the anterior bony buttress that resists posterior displacement of the ulna, as well as loss of the anterior capsule insertion. These fractures are often repaired, particularly when associated with elbow instability. Type III fractures involve > 50% of the coronoid and often contain the insertion of the anterior band of the MCL (red arrow). The insertion of the brachialis (red triangle) may also be involved resulting in proximal displacement of the fracture fragment. Surgical repair of type III fractures is necessary to reconstitute the MCL and restore elbow stability. Illustration B is a CT scan of a type I coronoid fracture. Illustration C is a CT scan of a type II coronoid fracture. Illustration D is a CT scan of a type III coronoid fracture.Incorrect Answers:

Question 5

-What is the primary mechanism of wear of polyethylene acetabular components?

Accepted Answer

Adhesion and abrasion

Orthopedic Surgery Board Review MCQs: AAOS Master Bank Part 229

Key Medical Takeaway