ABOS Foot & Ankle MCQs: Fractures & Diabetic Foot

Question 1

A 50-year-old woman who underwent a joint replacement of the hallux metatarsophalangeal joint 6 months ago now has pain and swelling about the great toe. Radiographs are shown in Figures 39a and 39b. What is the next most appropriate step in management?

Explanation

The radiographs show displacement of the prosthesis, and there has been large amounts of bone resected to insert the implant. Arthrodesis is indicated with interposition bone graft to stabilize the joint and restore length to the first ray.

Question 2

What is the most common foot and ankle deformity in patients with arthrogryposis?

Explanation

Clubfoot (talipes equinovarus) in patients with arthrogryposis is a rigid and resistant deformity. However, multiple studies document limited success with nonsurgical management. Manipulation and casting are generally a preliminary treatment before surgery; successful correction will most like require a talectomy. Guidera KJ, Drennan JC: Foot and ankle deformities in arthrogryposis multiplex congenita. Clin Orthop 1985;194:93-98. Handelsman JE, Badalamente MA: Neuromuscular studies in clubfoot. J Pediatr Orthop 1981;1:23-32.

Question 3

A 16-year-old girl has had pain and swelling along the medial arch of her left foot for the past 3 months. She also reports pain from shoe wear and while running. Nonsteroidal anti-inflammatory drugs have failed to provide relief. Radiographs are shown in Figures 40a through 40c. What is the next most appropriate step in management?

Explanation

Nonsurgical management of a symptomatic accessory navicular should be attempted prior to surgery. Good relief is often obtained with a semi-rigid orthosis with a medial arch support. Myerson MS: Foot and Ankle Disorders. Philadelphia, PA, WB Saunders, 2000, p 655.

Question 4

A 28-year-old man was shot in the foot with a .22 caliber handgun approximately 2 hours ago. Examination reveals an entrance wound dorsally and a plantar exit wound. The foot is neurovascularly intact. Radiographs reveal a nondisplaced fracture of the third metatarsal. Soft-tissue management for this injury should consist of

Explanation

The patient has sustained a low-velocity, low-caliber gunshot wound to the foot. Because the injury occurred within a period of 8 hours, this is classified as a type I wound. Several studies support the use of surface debridement, cleansing, and sterile dressings as the treatment of choice. More aggressive measures are reserved for high-velocity injuries and shotgun injuries. Brettler D, Sedlin ED, Mendes DG: Conservative treatment of low velocity gunshot wounds. Clin Orthop 1979;140:26-31. Hampton OD: The indications for debridement of gunshot bullet wounds of the extremities in civilian practice. J Trauma 1961;1:368-372.

Question 5

The photomicrograph seen in Figure 41 shows which of the following conditions?

Explanation

The photomicrograph shows a synovial cell sarcoma with a characteristic histology of a biphasic pattern of pleomorphic spindle cells and well-differentiated cuboidal to columnar cells forming gland-like spaces. The glandular zones contain mucous-like material that stains positively with periodic acid Schiff. Microscopic calcifications are usually found. Synovial cell sarcoma has a high rate of local recurrence as well as metastases. It is the most common malignancy found in the foot. Krall RA, Kostianovsky M, Patchefsky AS: Synovial sarcoma: A clinical, pathological and ultrastructural study of 26 cases supporting the recognition of a monophasic variant. Am J Surg Pathol 1981;5:137-151.

Question 6

A 33-year-old man had his foot run over by a forklift 1 hour ago. Examination reveals that the head of the fifth metatarsal is extruded through the plantar aspect of the foot. The foot is severely swollen and pale, there is no sensation in the toes, and the pulses are not palpable. Radiographs are shown in Figures 42a and 42b. Emergent management should consist of

Explanation

Following a severe crush injury, the patient has an acute compartment syndrome. Even though there is an open fracture, this is not sufficient to decompress the compartment syndrome. Therefore, splinting and observation are not appropriate. The surgical treatment of choice is fasciotomy with fixation of the multiple fractures. A primary amputation is not indicated because there is potential for salvage of this devastating injury. Fakhouri AJ, Manoli A II: Acute foot compartment syndromes. J Orthop Trauma 1992;6:223-228. Myerson MS: Management of compartment syndromes of the foot. Clin Orthop 1991;271:239-248.

Question 7

A 2-year-old boy has been referred for musculoskeletal evaluation. Examination reveals shortened proximal limbs, hip and knee flexion contractures, an abducted thumb, and ear abnormalities. His parents are concerned about his deformed feet. What is the most common foot deformity associated with this patient's diagnosis?

Explanation

The patient has diastrophic dysplasia. Affected individuals have rhizomelic short stature, cauliflower ears, severe joint contractures (especially knees and hips), hitchhiker's thumb, and a cleft palate. The most common foot abnormality is a rigid equinovarus deformity. Surgical results are poorer than those for idiopathic clubfeet and often require bony procedures or talectomy. Ryoppy S, Poussa M, Merikanto J, Marttinen E, Kaitila I: Foot deformities in diastrophic dysplasia: An analysis of 102 patients. J Bone Joint Surg Br 1992;74:441-444.

Question 8

A 31-year-old woman has a history of a painful ankle that has failed to respond to conservative management. She has associated night pain that is relieved with nonsteroidal anti-inflammatory drugs. MRI and technetium Tc 99m scans are consistent with an osteoid osteoma. Management should now consist of

Explanation

Surgical curettage or en bloc resection is the treatment of choice for osteoid osteoma. Night pain and relief of symptoms with nonsteroidal anti-inflammatory drugs are classic findings for osteoid osteoma. Donley BG, Philbin T, Rosenberg GA, Schils JP, Recht M: Percutaneous CT guided resection of osteoid osteoma of the tibial plafond. Foot Ankle Int 2000;21:596-598. Kenzora JE, Abrams RC: Problems encountered in the diagnosis and treatment of osteoid osteoma of the talus. Foot Ankle 1981;2:172-178.

Question 9

A 13-year-old girl has had pain in her ankle and difficulty with sporting activities for the past 6 months. Nonsteroidal anti-inflammatory drugs and use of a short leg cast have provided minimal relief. A radiograph and MRI scan are shown in Figures 43a and 43b. What is the next most appropriate step in treatment?

Explanation

The MRI scan shows an obvious talocalcaneal coalition of the medial facet. Because nonsurgical management has failed, surgical resection of the coalition is indicated. Arthrodesis would be indicated only if resection fails to relieve pain or if advanced degeneration of the hindfoot joints is present. McCormack TJ, Olney B, Asher M: Talocalcaneal coalition resection: A 10-year follow-up. J Pediatr Orthop 1997;17:13-15.

Question 10

A 16-year-old female dancer has persistent posterior ankle pain, particularly after a vigorous dancing schedule. Examination reveals tenderness both posteromedially and posterolaterally. MRI scans are seen in Figures 44a and 44b. What is the most likely diagnosis?

Explanation

Posterior ankle impingement or os trigonum syndrome is well described in dancers, and it is often associated with flexor hallucis longus tendinitis. High-quality MRI imaging will reveal the inflammation about the os trigonum and flexor hallucis longus tendinitis. Mizel MS, Miller RA, Scioli MW (eds): Orthopaedic Knowledge Update: Foot and Ankle 2. Rosemont IL, American Academy of Orthopaedic Surgeons, 1998, pp 315-332.

Question 11

Which of the following nerves is most commonly injured during ankle arthroscopy?

Explanation

The superficial peroneal nerve, which is adjacent to the location of the lateral arthroscopic portal is most commonly injured. Ferkel RD, Heath DD, Guhl JF: Neurological complications of ankle arthroscopy. Arthroscopy 1996;12:200-208.

Question 12

An obese 56-year-old woman with hypertension has had posterior heel pain for the past 6 months. She also notes some enlargement over the posterior aspect of the heel. Examination reproduces pain with palpation at the insertion of the Achilles tendon. A lateral radiograph is shown in Figure 45. What is the most likely diagnosis?

Explanation

The lateral radiograph shows a traction spur consistent with tendinopathy of the Achilles tendon. There is no displacement of the spur to suggest a rupture of the Achilles tendon, and os trigonum is not seen on the radiograph. The examination findings are not consistent with nerve entrapment. Schepsis AA, Wagner C, Leach RE: Surgical management of Achilles tendon overuse injuries: A long-term follow-up study. Am J Sports Med 1994;22:611-619.

Question 13

A 42-year-old woman has a history of nontraumatic ankle swelling with tenderness over the Achilles tendon and plantar fascia. She reports that while vacationing in Connecticut 2 months ago she noted the presence of a "red bull's eye" rash. Management should consist of

Explanation

The most likely diagnosis is Lyme disease because of the patient's recent vacation in an area with a high risk of exposure. The most effective treatment is doxycycline. Neu HC: A perspective on therapy of Lyme infection. Ann NY Acad Sci 1988;539:314-316.

Question 14

A 50-year-old woman has a painful hallux valgus and a painful callus beneath the second metatarsal head. A radiograph is shown in Figure 46. To correct these problems, treatment of the great toe deformity should consist of

Explanation

The patient has a significant hallux valgus and instability of the first ray, causing transfer metatarsalgia to the second metatarsal head. Therefore, the best procedure is fusion of the metatarsal cuneiform joint with soft-tissue realignment of the first metatarsophalangeal joint. This procedure provides the best chance of relieving symptoms under the second metatarsal head, as well as correcting the hallux valgus.

Question 15

The lower extremity motor dysfunction in Charcot-Marie-Tooth disease most commonly involves which of the following muscles?

Explanation

The motor dysfunction in Charcot-Marie-Tooth disease involves the tibialis anterior muscle. Charcot-Marie-Tooth disorders most commonly cause distal motor dysfunction in the foot intrinsics, anterior compartment musculature, and peroneals. There is evidence that the peroneus brevis is affected selectively and the peroneus longus is spared. This is based on clinical muscle testing, muscle cross-sections on MRI, and electrodiagnostic testing. Mann RA, Missirian J: Pathophysiology of Charcot-Marie-Tooth disease. Clin Orthop 1988;234:221-228.

Question 16

Fixed hyperextension of the metatarsophalangeal joint is associated with

Explanation

Claw toe and hammer toe deformities are associated with dorsal subluxation of the interossei, which can no longer serve to flex the metatarsophalangeal joint. The extensor digitorum longus then loses its tenodesing effect on the proximal interphalangeal and distal interphalangeal joints and works unopposed to extend the metatarsophalangeal joint and the proximal phalanx. Without the antagonistic action of the extensor digitorum longus, the extrinsic flexors become unopposed flexors of the proximal and distal interphalangeal joints. Marks RM: Anatomy and pathophysiology of lesser toe deformities. Foot Ankle Clin 1998;3:199-213.

Question 17

The orthosis shown in Figure 47 is commonly used for

Explanation

The orthosis shown is a carbon reinforced Morton's extension, and it is commonly used for hallux rigidus. It decreases motion of the first metatarsophalangeal joint and subsequently decreases pain.

Question 18

A 14-year-old boy has medial ankle pain, progressive unilateral flatfoot deformity, and pain with most activities of daily living. He denies any recent injury. His parents recall that at age 7 years he sustained an injury that was treated as a sprain. Examination reveals valgus deformity with painless, unrestricted passive motion of the ankle. He has grossly equal limb lengths. A radiograph of the affected ankle is shown in Figure 48a, and the contralateral ankle is shown in Figure 48b. Management should consist of

Explanation

Angular deformities of the ankle can occur following physeal injury. While an orthosis may be beneficial, the deformity is at the level of the ankle rather than the hindfoot. An epiphysiodesis or physeal bar resection would not be indicated as the growth plates are closed. Correction of the angular deformity should level the ankle joint and normalize the weight-bearing stresses on the ankle. This is most easily achieved with a closing wedge distal tibial osteotomy with or without concomitant osteotomy of the fibula. Thompson DM, Calhoun JH: Advanced techniques in foot and ankle reconstruction. Foot Ankle Clin 2000;5:417-442. Ting AJ, Tarr RR, Sarmiento A, Wagner K, Resnick C: The role of subtalar motion and ankle contact pressure changes from angular deformities of the tibia. Foot Ankle 1987;7:290-299.

Question 19

What is the most common organism found following a nail puncture wound through tennis shoes in a host without immunocompromise?

Explanation

The association of a nail puncture wound with a gram-negative infection (Pseudomonas aeruginosa) has been attributed to the local environmental factors in shoes. Osteomyelitis is rare, occurring only in about 1% of patients. Tetanus prophylaxis should be given if it is not up to date. While the remaining organisms listed are periodically involved, they are more common in patients who are immunocompromised or who have diabetes mellitus. Therefore, obtaining a culture of the infected wound is appropriate in such individuals because of the multifactorial nature of the infection. Green NE, Bruno J III: Pseudomonas infections of the foot after puncture wounds. South Med J 1980;73:146-149.

Question 20

Examination of a 28-year-old woman reveals a moderate hallux valgus deformity and a prominence of the medial eminence. She reports that she can participate in all activities, wear 3-inch heels with minimal discomfort, and walk in a 1-inch heel with no pain. However, she is concerned that the deformity will get worse and requests recommendations regarding surgical correction. What is the best course of action?

Explanation

Because the patient is essentially asymptomatic, the most appropriate course of action is observation. Prophylactic hallux valgus surgery is not medically indicated. Steroid injection would only risk infection, as well as joint and capsule damage. There are no data to support the use of a custom orthosis to delay the progression of a hallux valgus deformity. Special shoe wear or an extra-depth shoe is not necessary and is unlikely to be accepted by the patient. Donley BG, Tisdel CL, Sferra JJ, Hall JO: Diagnosing and treating hallux valgus: A conservative approach for a common problem. Cleve Clin J Med 1997;64:469-474.

Question 21

A 25-year-old man has ankle instability and a lateral foot callosity. Radiographs are shown in Figures 49a through 49c. Management options are best determined by the

Explanation

The patient has a cavovarus deformity that has resulted in lateral foot overload and stressing of the lateral ligaments. Further treatment depends on the ability to correct the deformity. The Coleman block test indicates whether a deformity is fixed or supple. A supple deformity will respond to orthotic management or soft-tissue procedures, while a fixed deformity requires corrective osteotomy or fusion. Physical therapy, casting, and injection will not address the underlying pathophysiology. There is no indication that this is a neuropathic problem.

Question 22

A 17-year-old boy underwent open reduction and internal fixation of a navicular fracture 5 days ago. A follow-up examination now reveals a tensely swollen foot with erythema and multiple skin bullae. The patient is febrile and has marked pain with palpation of the entire forefoot and hindfoot. What is the next step in management?

Explanation

Necrotizing fasciitis is a rapidly progressive soft-tissue infection with the potential to threaten both life and limb. Patients who are immunocompromised (HIV infection, diabetes mellitus, alcohol abuse) are at increased risk. However, any patient in the immediate postoperative phase is susceptible to wound infection. Early detection is the key. Necrotizing fasciitis is primarily a surgical problem that requires urgent debridement and broad-spectrum IV antibiotics. Rapid diagnosis and prompt treatment help to reduce mortality, which may approach 30%. Debridement of the bullae and observation are not indicated. Although elevation and close follow-up may be warranted early on, in this patient, surgical debridement is the next step. Ault MJ, Geiderman J, Sokolov R: Rapid identification of group A streptococcus as the cause of necrotizing fasciitis. Ann Emerg Med 1996;28:227-230.

Question 23

A 14-year-old girl has had mild pain and nail deformity of the great toe for the past 4 months. A radiograph is shown in Figure 50. What is the most likely etiology of the lesion?

Explanation

The lesion is typical of a subungual exostosis, which is most often found on the medial aspect of the great toe in children and young adults. The diagnosis is confirmed on radiographs and usually requires excision for relief. Lokiec F, Ezra E, Krasin E, Keret D, Wientraub S: A simple and efficient surgical technique for subungual exostosis. J Pediatr Orthop 2001;21:76-79. Letts M, Davidson D, Nizalik E: Subungual exostosis: Diagnosis and treatment in children. J Trauma 1998;44:346-349.

Question 24

The third plantar intrinsic muscle layer of the foot consists of which of the following structures?

Explanation

The plantar intrinsic muscles are divided into four layers with respect to depth from the plantar fascia. They are (from superficial to deep): 1) abductor hallucis, flexor digitorum brevis, abductor digiti minimi; 2) quadratus plantae, lumbricals; 3) flexor digiti minimi, flexor hallucis brevis, adductor hallucis brevis; and 4) dorsal and plantar interosseous muscles. The flexor hallucis brevis and adductor hallucis brevis originate from the midtarsal bones, encompass the sesamoids, and insert into the base of the proximal phalanx. The adductor hallucis brevis consists of two muscle bellies forming a conjoined tendon and inserting into the lateral portion of the proximal phalanx and the lateral sesamoid. The adductor hallucis brevis is stronger than the abductor hallucis brevis, which may contribute to hallux valgus. The flexor digitorum minimi travels under the fifth metatarsal, arising at the base and inserting into the lateral base of the fifth proximal phalanx.

Question 25

Which of the following results cannot be achieved with an in-shoe orthosis?

Explanation

Depending on the type of materials used, an orthotic can be fabricated to achieve a variety of results. While a rigid fixed deformity can be stabilized or cushioned, an orthotic will not correct a deformity that is not passively correctable. Mizel MS, Miller RA, Scioli MW (eds): Orthopaedic Knowledge Update: Foot and Ankle 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1998, pp 55-64. Bono CM, Berberian WS: Orthotic devices: Degenerative disorders of the foot and ankle. Foot Ankle Clin 2001;6:329-340.

Question 26

A 55-year-old poorly controlled diabetic presents with a swollen, erythematous, warm, and painless right foot. Pulses are palpable and bounding. Radiographs are unremarkable. MRI demonstrates diffuse marrow edema in the midfoot without focal fluid collections. What is the most appropriate initial management?

Explanation

This presentation is classic for Eichenholtz Stage 0 Charcot arthropathy, characterized by clinical inflammation and marrow edema on MRI prior to radiographic destruction. Strict immobilization in a total contact cast (TCC) is the gold standard to prevent progression to fragmentation and deformity.

Question 27

According to the classic biomechanical study by Ramsey and Hamilton, a 1-mm lateral displacement of the talus within the ankle mortise following an ankle fracture reduces the tibiotalar contact area by approximately what percentage?

Explanation

Ramsey and Hamilton demonstrated that a 1-mm lateral shift of the talus decreases the tibiotalar contact area by 42%. This highlights the critical importance of anatomic reduction of the lateral malleolus to prevent rapid onset of post-traumatic arthritis.

Question 28

A 62-year-old diabetic patient presents with a deep plantar neuropathic ulcer under the first metatarsal head. On examination, a sterile metal probe smoothly passes through the ulcer base and strikes hard, gritty bone. Which of the following is true regarding this clinical finding?

Explanation

The probe-to-bone test is highly predictive of osteomyelitis in the presence of an infected diabetic foot ulcer. It has a high positive predictive value, often negating the absolute need for advanced imaging like MRI before starting tailored therapy.

Question 29

In a Supination-External Rotation (SER) stage IV ankle fracture, which of the following structures is injured last (Stage IV) according to the Lauge-Hansen classification?

Explanation

The SER progression sequence is: 1) AITFL rupture, 2) spiral/oblique fibula fracture, 3) PITFL rupture or posterior malleolus fracture, and 4) deltoid ligament rupture or medial malleolus transverse fracture.

Question 30

A 60-year-old diabetic woman with a history of recurrent forefoot ulcers and osteomyelitis presents for preoperative evaluation for a planned Syme amputation. Which of the following noninvasive vascular parameters is the most reliable predictor of successful wound healing at this specific amputation level?

Explanation

Healing of a Syme or hindfoot amputation typically requires an absolute ankle systolic pressure greater than 70 mm Hg. Toe pressures > 40 mm Hg are used to predict forefoot healing, while a minimum serum albumin of 3.0 g/dL is generally required for reliable soft tissue healing.

Question 31

A 45-year-old man sustains a pronation-external rotation (PER) ankle fracture. Intraoperatively, after rigid internal fixation of the medial and lateral malleoli, an intraoperative Hook test demonstrates 3 mm of lateral syndesmotic widening. Which of the following represents the most appropriate next step?

Explanation

Widening of the syndesmosis during a stress examination after bony fixation of the malleoli indicates persistent dynamic instability. It requires stabilization with trans-syndesmotic screws or a flexible suture-button construct.

Question 32

A 50-year-old diabetic male undergoes total contact casting for Eichenholtz Stage I Charcot arthropathy of the midfoot. Which of the following radiographic findings marks the transition to Eichenholtz Stage II (Coalescence)?

Explanation

Eichenholtz Stage I (Development) involves active fragmentation and joint dislocation. Stage II (Coalescence) is marked radiographically by the absorption of fine debris, early bony fusion, and marginal sclerosis. Stage III is consolidation and remodeling.

Question 33

A 30-year-old male presents with a severely displaced ankle fracture-dislocation. Closed reduction under conscious sedation in the ED is mechanically blocked. A true lateral radiograph shows the proximal segment of the fibula locked posterior to the tibia. Behind which specific anatomic structure is the fibula typically entrapped in this rare injury pattern?

Explanation

This describes a Bosworth fracture-dislocation, an irreducible injury where the proximal fragment of the fractured fibula becomes entrapped behind the posterior tibial tubercle (Volkmann's triangle). It requires urgent open reduction to prevent soft tissue necrosis.

Question 34

A 65-year-old poorly controlled diabetic sustains an unstable bimalleolar ankle fracture. Operative fixation is planned. Compared to a non-diabetic patient, what is the most appropriate modification to the surgical technique and postoperative protocol?

Explanation

Diabetic patients with ankle fractures have significantly higher complication rates, including loss of fixation and Charcot arthropathy. Augmented fixation (e.g., multiple syndesmotic screws, locking plates) and prolonged non-weight-bearing (typically 10-12 weeks) are recommended to minimize hardware failure.

Question 35

A 55-year-old patient with long-standing diabetes presents with a unilateral warm, erythematous, and swollen foot and ankle. There are no open wounds. Radiographs show soft tissue swelling without bony abnormalities. Which of the following physical examination findings is most useful to differentiate acute Charcot arthropathy from cellulitis?

Explanation

In acute Eichenholtz stage 1 Charcot arthropathy, the limb is erythematous and warm due to autonomic neuropathy and arteriovenous shunting. Elevating the affected limb for 5 to 10 minutes typically results in the resolution of erythema, distinguishing it from cellulitis.

Question 36

A 42-year-old man sustains an ankle injury. Radiographs reveal an ankle fracture-dislocation that is irreducible in the emergency department. A CT scan demonstrates the proximal fibular shaft fragment is locked behind the posterior tubercle of the tibia. Which of the following is the most likely diagnosis?

Explanation

A Bosworth fracture-dislocation is characterized by the entrapment of the proximal fibular fragment behind the posterior tubercle of the distal tibia. This injury is notoriously irreducible by closed means and requires prompt open reduction.

Question 37

The most common anatomic location for the development of Charcot neuroarthropathy in the diabetic foot is:

Explanation

The tarsometatarsal (Lisfranc) joint complex is the most common site of Charcot neuroarthropathy. Collapse at this level typically leads to a characteristic rocker-bottom foot deformity and increased risk of midfoot plantar ulceration.

Question 38

A 35-year-old woman sustains a trimalleolar ankle fracture. The posterior malleolus fracture involves 30% of the articular surface. Which of the following is the primary biomechanical advantage of open reduction and internal fixation of the posterior malleolus compared to placing a trans-syndesmotic screw?

Explanation

Anatomical fixation of the posterior malleolus effectively restores the posterior inferior tibiofibular ligament (PITFL) footprint. This provides superior biomechanical stability to the syndesmosis compared to isolated trans-syndesmotic screw fixation.

Question 39

A 60-year-old diabetic patient presents with a chronic, recurrent plantar neuropathic ulcer under the first metatarsal head despite the use of total contact casting and accommodative footwear. Ankle dorsiflexion is limited to 5 degrees past neutral with the knee extended, but improves to 15 degrees with the knee flexed. What is the most appropriate surgical intervention to promote healing and prevent recurrence?

Explanation

The patient has a positive Silfverskiold test, indicating isolated gastrocnemius tightness. A gastrocnemius recession reduces forefoot plantar pressures, promoting the healing of recalcitrant plantar forefoot ulcers in patients with equinus contracture.

Question 40

According to the Lauge-Hansen classification, what is the initial ligamentous injury in a supination-external rotation (SER) type ankle fracture?

Explanation

In an SER injury, the sequence of failure begins with the anterior inferior tibiofibular ligament (AITFL) (Stage I). This is followed by a short oblique fracture of the lateral malleolus (Stage II), the PITFL (Stage III), and finally the medial malleolus or deltoid ligament (Stage IV).

Question 41

A 58-year-old patient with poorly controlled type 2 diabetes presents with an ulcerated, swollen midfoot. The clinician is concerned about osteomyelitis versus acute Charcot arthropathy. Which of the following MRI findings is most specific for diagnosing osteomyelitis over Charcot arthropathy?

Explanation

While bone marrow edema is present in both conditions, the replacement of normal T1 marrow fat with contiguous soft tissue ulceration or a sinus tract is highly specific for osteomyelitis. Charcot arthropathy typically shows periarticular marrow edema without direct extension from a cutaneous ulcer.

Question 42

A 60-year-old diabetic patient presents with a swollen, erythematous foot without an open ulcer. Radiographs show periarticular fragmentation and subluxation at the tarsometatarsal joint. Skin temperature is elevated compared to the contralateral side. What is the most appropriate initial management?

Explanation

The patient is presenting with acute Eichenholtz stage I Charcot neuroarthropathy. The initial treatment of choice is immediate immobilization with a total contact cast and non-weight bearing until the acute inflammatory phase resolves.

Question 43

A 45-year-old man sustains an ankle injury. Radiographs show an isolated lateral malleolus fracture at the level of the syndesmosis. A gravity stress view shows 6 mm of medial clear space widening. What Lauge-Hansen classification does this injury represent?

Explanation

An SER-IV injury involves a fracture of the fibula at the syndesmosis with disruption of the deltoid ligament or medial malleolus. The disruption of the medial structures is indicated by medial clear space widening on a stress view.

Question 44

In a patient with long-standing diabetes mellitus and a plantar forefoot ulcer that has failed to heal despite total contact casting, what surgical intervention is most likely to promote healing and prevent recurrence?

Explanation

Equinus contracture increases forefoot plantar pressures, which is a major contributor to recurrent forefoot ulcers. Lengthening the Achilles tendon or performing a gastrocnemius recession reduces these pressures and significantly aids in ulcer healing.

Question 45

Which of the following clinical tests has the highest positive predictive value for diagnosing osteomyelitis beneath a diabetic foot ulcer?

Explanation

A positive probe-to-bone test is highly predictive of underlying osteomyelitis in a diabetic foot ulcer. While MRI is the most sensitive imaging modality, the clinical probe-to-bone test remains a critical diagnostic tool.

Question 46

A 55-year-old poorly controlled diabetic patient undergoes open reduction and internal fixation of a bimalleolar ankle fracture. What modification to the standard postoperative protocol is most strongly recommended for this patient?

Explanation

Diabetic patients with ankle fractures have a significantly higher risk of complications, including Charcot arthropathy and loss of fixation. Prolonged immobilization and at least a doubled non-weight-bearing period (8 to 12 weeks) are standard recommendations.

Question 47

A patient sustains a pronation-external rotation (PER) ankle injury. According to the Lauge-Hansen classification, what is the first structure injured in this sequential failure pattern?

Explanation

In a pronation-external rotation injury, the sequence of failure begins medially with the deltoid ligament or medial malleolus (Stage I). This is followed by the AITFL (Stage II), a high fibula fracture (Stage III), and finally the PITFL or posterior malleolus (Stage IV).

Question 48

What is the pathomechanical consequence of a 1-mm lateral shift of the talus within the ankle mortise following a malreduced ankle fracture?

Explanation

Classic biomechanical studies by Ramsey and Hamilton demonstrated that a 1-mm lateral displacement of the talus reduces the tibiotalar contact area by 42%. This severely increases joint contact pressures and accelerates post-traumatic arthritis.

Question 49

A 35-year-old man presents with an ankle fracture-dislocation. Radiographs show a posterior dislocation of the proximal fibular fragment behind the lateral ridge of the distal tibia, which is irreducible by closed means. What is this specific injury pattern named?

Explanation

A Bosworth fracture-dislocation involves the proximal fragment of the fractured fibula becoming entrapped behind the posterior tubercle of the distal tibia. It typically requires open reduction to dislodge the fibula.

Question 50

In the treatment of acute Charcot neuroarthropathy (Eichenholtz stage I), when is the transition from a total contact cast to a Charcot Restraint Orthotic Walker (CROW) or custom therapeutic footwear most appropriate?

Explanation

The clinical resolution of the acute inflammatory phase of Charcot arthropathy is best indicated by the equalization of skin temperatures (within 1-2°C) and reduction in edema compared to the unaffected foot. Radiographic consolidation occurs much later in Stage III.

Question 51

A 50-year-old diabetic woman with peripheral neuropathy undergoes ORIF for an unstable ankle fracture. To enhance construct stability and reduce the high risk of catastrophic failure, which of the following techniques is most appropriate?

Explanation

In diabetic patients with ankle fractures, augmented fixation techniques are strongly recommended to prevent hardware failure in osteopenic bone. This includes multiple trans-syndesmotic screws (even without obvious syndesmosis injury), locking plates, and quadricortical pro-tibia screws.

Question 52

A 65-year-old diabetic patient presents with a deep, non-healing plantar midfoot ulcer. Radiographs show a bony prominence causing the ulcer, but MRI is equivocal for osteomyelitis. What is the gold standard for diagnosing osteomyelitis in this setting?

Explanation

While imaging and clinical signs are helpful, a bone biopsy is the gold standard for definitively diagnosing osteomyelitis. It also provides reliable deep culture data to direct targeted antibiotic therapy in the diabetic foot.

Question 53

What is the most appropriate indication for repairing the deltoid ligament during open reduction and internal fixation of a supination-external rotation stage IV ankle fracture?

Explanation

Routine repair of the deltoid ligament in ankle fractures is not indicated and does not improve outcomes. It is indicated almost exclusively when the medial clear space fails to reduce, suggesting the deltoid ligament is inverted and entrapped, blocking talar reduction.

Question 54

A 40-year-old patient presents with a trimalleolar ankle fracture. The posterior malleolus fracture involves 35% of the articular surface and is displaced. What is the primary biomechanical rationale for surgical fixation of the posterior malleolus in this case?

Explanation

Fixation of a large, displaced posterior malleolus fracture restores the articular surface to prevent post-traumatic arthritis. It also significantly restores the stability of the syndesmosis by recreating the tension in the posterior inferior tibiofibular ligament (PITFL).

Question 55

In diabetic patients, measuring tissue oxygenation is critical for determining the healing potential of an ulcer or a planned surgical incision. What is the minimum transcutaneous oxygen tension (TcPO2) generally considered necessary to support wound healing?

Explanation

A TcPO2 greater than 40 mmHg is generally associated with a high probability of wound healing. Values below 30 mmHg indicate severe ischemia and a high likelihood of wound failure, often necessitating vascular intervention or higher-level amputation.

Question 56

A 55-year-old patient with long-standing, poorly controlled diabetes presents with a red, hot, swollen left foot. The patient denies any trauma. Pedal pulses are bounding. Inflammatory markers are within normal limits. Radiographs show soft tissue swelling but no fractures or joint subluxation. What is the most appropriate next step in management?

Explanation

This clinical presentation is classic for Eichenholtz Stage 0 (prodromal) Charcot neuroarthropathy. The mainstay of treatment is immediate immobilization and offloading, typically with a total contact cast, to prevent progression to fragmentation and severe deformity.

Question 57

When treating a trimalleolar ankle fracture, which of the following is the most widely accepted absolute indication for operative fixation of the posterior malleolus?

Explanation

Persistent posterior subluxation of the talus indicates gross tibiotalar instability and is an absolute indication for posterior malleolar fixation. Fragment size criteria vary, though >25% of the articular surface is commonly considered a relative indication.

Question 58

A 60-year-old poorly controlled diabetic patient has a chronic plantar foot ulcer beneath the first metatarsal head. Which of the following clinical findings has the highest positive predictive value for underlying osteomyelitis?

Explanation

A positive probe-to-bone test (palpating hard, gritty bone with a sterile metal probe) is highly predictive of underlying osteomyelitis in the setting of an infected diabetic foot ulcer. It significantly increases the probability of bone infection.

Question 59

A 32-year-old man presents to the emergency department after a skiing fall. He complains of severe medial ankle pain and proximal lateral leg pain. Ankle radiographs show an isolated widening of the medial clear space. Knee radiographs reveal a proximal third fibula fracture. According to the Lauge-Hansen classification, what is the mechanism of this injury?

Explanation

This describes a Maisonneuve fracture, which involves a proximal fibular fracture with syndesmotic disruption and medial ankle injury. This pattern typically results from a Pronation-External Rotation (PER) mechanism.

Question 60

A 65-year-old diabetic patient presents with a recurrent neuropathic ulcer beneath the first metatarsal head despite compliant use of a total contact cast and custom orthotics. Examination reveals that ankle dorsiflexion is limited to 5 degrees of plantarflexion when the knee is fully extended, and remains limited to 5 degrees of plantarflexion when the knee is flexed to 90 degrees. What is the most appropriate surgical intervention?

Explanation

The patient has a positive Silfverskiöld test demonstrating equinus contracture with both the knee extended and flexed, indicating combined gastrocnemius-soleus tightness. An Achilles tendon lengthening (TAL) is indicated to reduce forefoot pressures and aid ulcer healing.

Question 61

A 40-year-old male sustains a severe ankle fracture-dislocation. Closed reduction in the emergency department is unsuccessful despite adequate sedation. A CT scan reveals that the proximal fragment of the fibula is locked behind the posterior tubercle of the distal tibia. What is the eponymous name for this specific injury pattern?

Explanation

A Bosworth fracture-dislocation occurs when the proximal fibular fragment becomes entrapped behind the posterior tubercle of the tibia. It is characteristically irreducible by closed means and requires prompt open reduction.

Question 62

Operative reconstruction (e.g., corrective arthrodesis) for a patient with midfoot Charcot neuroarthropathy is most commonly indicated and safely performed during which Eichenholtz stage?

Explanation

Major reconstructive surgery for Charcot foot is ideally delayed until the consolidation phase (Eichenholtz Stage III), when the active inflammatory process has resolved. Operating during the acute fragmentation phase carries a high risk of failure and hardware pullout.

Question 63

When treating a Weber B (supination-external rotation) distal fibula fracture, what is the primary biomechanical advantage of utilizing a posterior antiglide plate compared to a lateral neutralization plate?

Explanation

A posterior antiglide plate converts posterior shear forces into compressive forces at the fracture site during axial loading. It mechanically resists the posterosuperior displacement of the distal fibular fragment better than a lateral plate.

Question 64

A diabetic patient is undergoing evaluation for a major lower extremity amputation due to gangrene. Compared to a healthy individual, what is the approximate percentage increase in energy expenditure required for ambulation following a unilateral transtibial (below-knee) amputation?

Explanation

Unilateral transtibial (below-knee) amputees typically require about 25% (range 20-30%) more energy for ambulation compared to baseline. A unilateral transfemoral (above-knee) amputation increases energy expenditure by approximately 65%.

Question 65

Ankle radiographs of a 28-year-old male reveal a vertical shear fracture of the medial malleolus and a transverse fracture of the lateral malleolus at the level of the joint line. According to the Lauge-Hansen classification, what is the most likely mechanism of injury?

Explanation

A Supination-Adduction (SAD) injury pattern classically presents with a transverse avulsion fracture of the lateral malleolus (or lateral ligament rupture) below the joint line, followed by a vertical shear fracture of the medial malleolus.

Question 66

According to the Wagner classification system for diabetic foot ulcers, a lesion described as a deep ulcer with localized gangrene isolated to the great toe and forefoot is classified as:

Explanation

Wagner Grade 4 indicates localized gangrene (e.g., involving the forefoot, heel, or toes). Grade 3 involves a deep ulcer with osteomyelitis or abscess, while Grade 5 describes extensive gangrene of the entire foot.

Question 67

A 35-year-old woman is 4 months postoperative from open reduction and internal fixation of an ankle fracture, which included placement of two 3.5mm trans-syndesmotic screws. She is completely asymptomatic and asks if the screws must be removed. Based on current orthopedic literature, what is the recommendation regarding routine removal of syndesmotic screws?

Explanation

Current evidence demonstrates that routine removal of syndesmotic screws is unnecessary. Clinical outcomes are comparable whether the screws are removed, retained intact, or broken, and elective removal exposes the patient to unnecessary surgical risks.

Question 68

Differentiating acute Charcot neuroarthropathy from osteomyelitis in the diabetic foot is challenging. On magnetic resonance imaging (MRI), which of the following findings is most specific for osteomyelitis rather than acute Charcot arthropathy?

Explanation

The "ghost sign" (where bone margins become invisible or indistinct on T1-weighted images but 'reappear' on T2/STIR images) is highly indicative of osteomyelitis. Charcot arthropathy typically demonstrates bone marrow edema strictly localized to the subchondral bone adjacent to affected joints.

Question 69

A 14-year-old adolescent sustains a twisting ankle injury. Radiographs demonstrate a Salter-Harris III fracture of the anterolateral aspect of the distal tibial epiphysis. What anatomical structure is responsible for the avulsion of this fracture fragment?

Explanation

This scenario describes a juvenile Tillaux fracture. The avulsion of the anterolateral distal tibial epiphysis is caused by tension from the anterior inferior tibiofibular ligament (AITFL) as the medial portion of the distal tibial physis closes before the lateral portion.

Question 70

During the radiographic evaluation of a suspected syndesmotic injury, external rotation stress views are obtained. Which of the following radiographic measurements on an AP or mortise view is the most reliable indicator of deep deltoid ligament incompetence and syndesmotic instability?

Explanation

A medial clear space of >4 mm (or >5 mm depending on specific literature criteria) on an AP, mortise, or stress radiograph is a highly reliable indicator of lateral talar shift and underlying deep deltoid ligament rupture.

Question 71

A 62-year-old patient with poorly controlled type 2 diabetes and profound peripheral neuropathy sustains a displaced bimalleolar ankle fracture. Which of the following modifications to standard internal fixation is most strongly recommended to minimize catastrophic complications?

Explanation

Diabetic patients with neuropathy are at high risk for Charcot arthropathy, nonunion, and hardware failure following ankle fractures. Enhanced rigid fixation (e.g., multiple syndesmotic screws, supplementary K-wires, or locked plating) combined with prolonged non-weight-bearing is recommended to minimize catastrophic loss of fixation.

Question 72

A 55-year-old man with a 15-year history of diabetes presents with a red, swollen, and warm right foot. He denies trauma or fevers. Radiographs show periarticular debris, fragmentation of the tarsometatarsal joints, and subluxation. What is the most appropriate initial management?

Explanation

This patient presents with acute Eichenholtz Stage I Charcot neuroarthropathy, characterized by fragmentation and debris in the setting of neuropathy. The most appropriate initial management for the acute, active phase is immobilization with a total contact cast and strict non-weight-bearing.

Question 73

A 65-year-old poorly controlled diabetic with severe peripheral neuropathy sustains a closed, displaced bimalleolar equivalent ankle fracture. He undergoes stable open reduction and internal fixation. What is the most appropriate postoperative weight-bearing protocol for this specific patient?

Explanation

Diabetic patients with peripheral neuropathy undergoing ankle fracture fixation have a significantly higher risk of hardware failure, infection, and Charcot arthropathy. Extended periods of non-weight bearing, typically 10-12 weeks or double the standard duration, are recommended to prevent catastrophic mechanical failure.

Question 74

A 58-year-old male with long-standing diabetes presents with a red, hot, swollen unilateral foot without open wounds. Radiographs show periarticular fragmentation and subluxation at the tarsometatarsal joints. What is the most appropriate initial management?

Explanation

The patient is in Eichenholtz Stage I (fragmentation) of acute Charcot arthropathy. The gold standard for initial management of acute Charcot without deep ulceration is immobilization via total contact casting and strict non-weight bearing to halt deformity progression.

Question 75

A 32-year-old male sustains a pronation-external rotation (PER) ankle fracture. Intraoperatively, after medial and lateral malleolar fixation, the Cotton test is positive indicating syndesmotic instability. When placing a syndesmotic screw, what is the optimal ankle position and screw technique?

Explanation

Syndesmotic screws should be placed as position screws (not lagged) to maintain the relationship of the fibula in the incisura without over-compression. The ankle should be held in neutral or maximum dorsiflexion during placement to accommodate the wider anterior aspect of the talar dome.

Question 76

A 60-year-old diabetic male has a chronic plantar ulcer under the first metatarsal head. On examination, a sterile metal probe easily advances through the ulcer base and palpably taps against a hard, gritty surface. What is the approximate positive predictive value of this clinical finding for underlying osteomyelitis?

Explanation

The "probe-to-bone" test has a high positive predictive value (approximately 89%) for diagnosing osteomyelitis in the presence of a clinically infected diabetic foot ulcer. It is a rapid, validated, and highly useful initial clinical evaluation tool.

Question 77

A 45-year-old female sustains a trimalleolar ankle fracture. The posterior malleolar fragment involves 35% of the articular surface and remains displaced 3 mm after fibular fixation. Which of the following is the primary biomechanical advantage of directly fixing this posterior malleolar fragment?

Explanation

Direct fixation of the posterior malleolus restores the insertion of the posterior inferior tibiofibular ligament (PITFL). This anatomic restoration significantly enhances syndesmotic stability, often providing greater biomechanical rigidity than trans-syndesmotic screw fixation alone.

Question 78

A 28-year-old male presents with a severe ankle injury following a fall. Closed reduction in the emergency department is unsuccessful. Radiographs show a distinct fracture-dislocation of the ankle.

Which of the following pathoanatomic features most likely prevents closed reduction in this specific injury pattern?

Explanation

A Bosworth fracture-dislocation is characterized by the proximal fragment of the fibula becoming entrapped behind the posterior lateral tubercle of the tibia. This osseous entrapment creates an anatomic block that makes closed reduction impossible, necessitating emergent open reduction.

Question 79

A 72-year-old obese female with advanced diabetic neuropathy and a history of a contralateral Charcot midfoot presents with a closed, unstable, displaced bimalleolar ankle fracture. In addition to standard open reduction and internal fixation, what supplemental surgical strategy is increasingly favored to minimize the high risk of catastrophic failure?

Explanation

Unstable ankle fractures in severe diabetics with profound neuropathy carry a disproportionately high risk of failure and rapid Charcot progression. Primary tibiotalocalcaneal (TTC) retrograde nailing is increasingly utilized as a definitive treatment to provide rigid, load-sharing stabilization and prevent catastrophic collapse.

Question 80

A 55-year-old diabetic man presents with a plantar midfoot ulceration measuring 2 cm in diameter. Which of the following is an absolute contraindication to the use of a total contact cast for offloading this patient's ulcer?

Explanation

Total contact casting (TCC) strictly relies on offloading the foot to heal neuropathic ulcers. The presence of active deep infection, purulence, or severe ischemia is an absolute contraindication, as the enclosed cast environment can lead to rapid soft tissue destruction and systemic sepsis.

Question 81

A 24-year-old athlete sustains a twisting injury to the ankle. Anteroposterior (AP) and mortise radiographs are obtained to evaluate for a syndesmotic injury. Which of the following radiographic parameters is considered abnormal and highly suggestive of a syndesmotic disruption on a standard mortise view?

Explanation

On both AP and mortise views, a tibiofibular clear space greater than 5-6 mm measured 1 cm above the joint line is abnormal and strongly indicates a syndesmotic injury. A normal mortise view should also typically demonstrate a medial clear space of 4 mm or less.

Question 82

A 40-year-old male sustains an ankle fracture. Radiographs reveal a transverse fracture of the medial malleolus and a high spiral fracture of the fibula above the syndesmosis (Weber C).

According to the Lauge-Hansen classification, what was the mechanism of injury?

Explanation

A transverse medial malleolus fracture combined with a high or short oblique fibular fracture (Weber C) is the classic hallmark of a Pronation-External Rotation (PER) injury. The mechanism initiates medially with a tension failure (deltoid tear or transverse medial malleolus fracture) and progresses laterally through the syndesmosis.

AAOS & ABOS Foot & Ankle Board Review MCQs (Set 2): Ankle Fractures, Lisfranc, Diabetic Foot

ABOS Foot & Ankle MCQs (Set 4): Ankle Fractures & Diabetic Foot | OITE & SMLE Review

Key Takeaway

ABOS Foot & Ankle MCQs (Set 4): Ankle Fractures & Diabetic Foot | OITE & SMLE Review

Chapter Index