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Distal Radius Fractures: Epidemiology, Surgical Anatomy, Biomechanics, & Complication Management

Orthopedic Board Prep: Distal Radius Fracture Management & Surgical Indications MCQs

23 Apr 2026 84 min read 92 Views
Chinese graduating exam

Key Takeaway

Surgical intervention for distal radius (Colles) fractures is primarily indicated when acceptable alignment cannot be maintained or achieved non-operatively. Key factors include persistent dorsal tilt (>10-20 degrees), radial shortening (>2-3mm), significant articular step-off (>1-2mm), severe comminution, and open fractures, especially after initial reduction attempts.

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Question 1

A 68-year-old female presents after a fall on an outstretched hand (FOOSH) with a 'dinner fork' deformity of her right wrist. Radiographs confirm a dorsally displaced, dorsally angulated, comminuted distal radius fracture with an associated ulnar styloid fracture. Initial closed reduction under hematoma block achieves reasonable alignment, but post-reduction radiographs show a residual dorsal tilt of 15 degrees, radial shortening of 4 mm, and a positive ulnar variance of 2 mm. The fracture extends into the articular surface. Which of the following is the most significant indication for surgical intervention in this patient?





Explanation

The most significant indication for surgical intervention in this scenario is the persistent dorsal tilt and radial shortening after reduction. While comminution, age, and ulnar styloid fracture are relevant factors, residual displacement parameters (dorsal tilt > 10 degrees, radial shortening > 3 mm) after initial attempts at closed reduction signify an unstable fracture that is likely to lose reduction, leading to malunion and functional impairment. These unstable parameters typically mandate surgical stabilization to restore and maintain anatomical alignment, preventing complications like pain, decreased range of motion, and post-traumatic arthritis. An ulnar styloid fracture alone is rarely an absolute indication unless it significantly contributes to DRUJ instability, which is not explicitly stated as the primary driver here. Comminution contributes to instability but the resultant unacceptable alignment after reduction is the direct surgical trigger.

Question 2

Regarding the surgical management of unstable Colles fractures with volar locking plates, which anatomical landmark is crucial to avoid hardware impingement on the flexor tendons and potential rupture?





Explanation

The volar watershed line is a critical anatomical landmark in volar plating of distal radius fractures. Plates placed distal to this line, or with screws protruding distally, risk irritation and rupture of the flexor tendons, particularly the flexor pollicis longus (FPL). The watershed line represents the ridge where the volar capsule and ligaments attach, marking the safe zone for plate placement proximally. Lister's tubercle is on the dorsal aspect, the pronator quadratus covers the plate proximally and protects tendons, but proper plate positioning relative to the articular surface, guided by the watershed line, is paramount for preventing distal tendon impingement.

Question 3

A 45-year-old construction worker sustains a highly comminuted, intra-articular Colles fracture (Frykman Type IV). After closed reduction, radiographs show significant residual articular step-off (>2mm) and metaphyseal comminution with loss of radial height. He has no neurovascular deficits. What is the most appropriate definitive management strategy?





Explanation

For a highly comminuted, intra-articular distal radius fracture with significant articular step-off and metaphyseal comminution in a relatively young, active patient, ORIF with a volar locking plate is generally considered the gold standard. A volar locking plate provides rigid fixation, allows for accurate restoration of articular congruence, and permits early mobilization, which is crucial for functional recovery. External fixation alone might not adequately reduce and maintain articular fragments, and K-wires are often insufficient for highly comminuted or intra-articular patterns. Cast immobilization would predictably result in malunion and severe functional deficit given the instability and articular involvement.

Question 4

Which of the following is NOT typically considered a stable parameter after closed reduction of a Colles fracture?





Explanation

An articular step-off of 3 mm is NOT considered a stable or acceptable parameter. Generally, an articular step-off or gap of >2 mm is considered unstable and an indication for surgical management, especially in active patients, due to the high risk of post-traumatic arthritis. Radial inclination of 22 degrees, volar tilt of 5 degrees (neutral to slight volar is acceptable for Colles), radial length difference of 2 mm (usually <3mm difference is acceptable), and ulnar variance of 0 mm (neutral) are all generally within acceptable post-reduction radiographic parameters for stable Colles fractures.

Question 5

A 72-year-old patient undergoes closed reduction and casting for a Colles fracture. Three weeks post-reduction, they develop increasing pain, swelling, skin discoloration, and temperature changes in the affected hand, out of proportion to the injury. Active and passive range of motion of the digits is severely limited. What is the most likely diagnosis?





Explanation

The constellation of symptoms including increasing pain, swelling, skin discoloration, temperature changes (autonomic dysfunction), and severely limited digital motion, out of proportion to the injury and occurring weeks after reduction, is highly suggestive of Complex Regional Pain Syndrome (CRPS) Type I, also known as Reflex Sympathetic Dystrophy (RSD). This condition is a common complication after distal radius fractures. Compartment syndrome is an acute emergency, typically occurring within hours to days, characterized by severe pain with passive stretching and potentially paresthesias and pallor, which is not the typical presentation here. Median nerve compression usually presents with specific sensory and motor deficits. EPL rupture causes a specific loss of thumb extension, and ulnar styloid nonunion would primarily cause focal pain and possibly DRUJ instability, not generalized hand symptoms.

Question 6

Which of the following describes the classic radiographic appearance of a Colles fracture?





Explanation

The classic radiographic appearance of a Colles fracture is characterized by dorsal displacement and dorsal angulation (apex volar) of the distal radius fragment. It is typically extra-articular but can have intra-articular extension. Volar displacement and angulation describe a Smith's fracture (reverse Colles). An intra-articular fracture of the radial styloid with carpal subluxation describes a Chauffeur's or Hutchinson's fracture (though not always subluxation), or a Barton's fracture if it's the rim.

Question 7

When performing closed reduction of a Colles fracture, what is the correct sequence of maneuvers after adequate anesthesia?





Explanation

The classic sequence for closed reduction of a Colles fracture involves: 1. Disimpaction and traction (to restore length and separate fragments), 2. Exaggeration of deformity (dorsiflexion) to unlock fragments, followed by volar translation, 3. Supination (to correct pronation of the distal fragment, which is common with dorsal displacement), 4. Ulnar deviation (to restore radial inclination), and 5. Palmar flexion (to correct dorsal angulation and maintain reduction). Therefore, traction, supination, ulnar deviation, and flexion are the key components after disimpaction.

Question 8

Which median nerve symptom is most common in the acute phase following a Colles fracture?





Explanation

In the acute phase following a Colles fracture, compression or contusion of the median nerve at the carpal tunnel level is common due to swelling and hematoma. This typically presents as paresthesia (numbness and tingling) in the median nerve distribution: the thumb, index finger, middle finger, and radial half of the ring finger. Thenar muscle atrophy is a sign of chronic median nerve compression. Sensory loss in the ulnar digits indicates ulnar nerve involvement. Wrist drop indicates radial nerve palsy. Tinel's sign over the cubital tunnel relates to ulnar nerve compression at the elbow.

Question 9

A 30-year-old male presents with a minimally displaced, extra-articular Colles fracture. He is active and concerned about returning to sports. Which of the following is the most appropriate initial management?





Explanation

For a minimally displaced, stable extra-articular Colles fracture, especially in a young, active patient, closed reduction and sugar tong splint followed by a cast is the most appropriate initial management. The question states 'minimally displaced' implying it is not grossly unstable. If closed reduction can achieve and maintain acceptable parameters, conservative management is appropriate. Surgical options are reserved for unstable or irreducible fractures, or those with unacceptable post-reduction parameters. Activity modification alone is insufficient for a fracture.

Question 10

What is the primary goal of surgical fixation of a Colles fracture with a volar locking plate?





Explanation

The primary goal of surgical fixation, particularly with a volar locking plate, for an unstable Colles fracture is to restore anatomical alignment (radial length, inclination, and volar tilt) and articular congruence (if intra-articular), and to provide sufficient stability to allow for early range of motion of the wrist and digits. Early mobilization is critical to prevent stiffness, promote cartilage healing, and improve functional outcomes. While other options might be secondary benefits or unrelated, restoring anatomy and facilitating early motion are paramount.

Question 11

Which classification system for distal radius fractures emphasizes the involvement of the radiocarpal and radioulnar joints?





Explanation

The Frykman classification system is widely used for distal radius fractures and is based on the involvement of the radiocarpal and radioulnar joints (articular vs. extra-articular, and presence/absence of ulnar styloid fracture). The AO classification is more complex and describes fracture patterns by location (metaphyseal), articular involvement (extra-articular, partial articular, complete articular), and comminution. Gartland and Werley primarily assess outcome. Universal classification is another system that considers similar parameters as Frykman. Fernandez classification is based on the mechanism of injury and fracture morphology.

Question 12

A common late complication of a malunited Colles fracture with significant dorsal angulation and radial shortening is:





Explanation

A common late complication of a malunited Colles fracture, particularly with significant dorsal angulation, is rupture of the Extensor Pollicis Longus (EPL) tendon. The sharp dorsal prominence of the malunited distal radius can cause attrition and eventual rupture of the EPL tendon as it traverses Lister's tubercle. Avascular necrosis of the scaphoid is typically associated with scaphoid fractures. Acute carpal tunnel syndrome and compartment syndrome are early complications. Ulnar nerve palsy is less directly related to Colles malunion itself.

Question 13

What is the typical mechanism of injury for a Colles fracture?





Explanation

The typical mechanism of injury for a Colles fracture is a fall onto an outstretched hand (FOOSH) with the wrist in dorsiflexion (extension). This forces the distal radius dorsally and typically results in dorsal angulation and displacement. A fall onto a pronated hand with the wrist in flexion would typically result in a Smith's fracture (reverse Colles), with volar displacement and angulation.

Question 14

In the setting of an acutely unstable Colles fracture, what is the role of an external fixator?





Explanation

External fixation for distal radius fractures primarily provides indirect reduction and maintains length and alignment through a principle called ligamentotaxis. By distracting across the wrist joint, it tension the intact soft tissue ligaments (radiocarpal ligaments) to indirectly pull the fracture fragments into a more anatomical position. It does not allow immediate full weight-bearing and is not solely for open fractures. It restricts wrist motion initially, though dynamic external fixators aim for controlled motion.

Question 15

Which radiographic measurement is typically decreased in a Colles fracture?





Explanation

In a typical Colles fracture with dorsal displacement and impaction, radial length (or radial height) is decreased due to compression of the distal radius. Radial inclination is also often decreased, and volar tilt becomes dorsal tilt (a negative volar tilt). Ulnar variance becomes positive (ulna appears longer relative to the radius). Carpal height ratio can also be affected, often decreased.

Question 16

A 55-year-old active female sustains a Colles fracture. Post-reduction radiographs demonstrate acceptable alignment, but she develops severe pain and swelling within 6 hours, with paresthesias in all fingers and pain with passive extension of the digits. Peripheral pulses are present. What is the most immediate concern?





Explanation

The acute onset of severe pain, swelling, paresthesias in all fingers, and critically, pain with passive extension of the digits, within hours of reduction, are classic signs of acute forearm compartment syndrome. Although peripheral pulses may still be present early on, this is a surgical emergency requiring immediate fasciotomy to prevent permanent muscle and nerve damage. Median nerve injury would typically affect only the median nerve distribution. CRPS develops later, and loss of reduction wouldn't typically cause these diffuse neurological and pain symptoms acutely.

Question 17

What is the primary anatomical purpose of the pronator quadratus muscle in relation to volar plating of the distal radius?





Explanation

The pronator quadratus muscle is typically reflected from lateral to medial during a volar approach for distal radius plating. After plate application, it is usually repaired over the plate. Its primary purpose in this context is to provide a soft tissue coverage for the volar locking plate and screws, thus protecting the overlying flexor tendons (especially FPL and FDP) from direct contact and irritation by the hardware. While it contributes to pronation and DRUJ stability, its role in protecting tendons from hardware is crucial in volar plating.

Question 18

Which type of fracture would be classified as a Frykman Type II?





Explanation

The Frykman classification system categorizes distal radius fractures based on articular involvement and the presence of an ulnar styloid fracture: Type I: Extra-articular, no ulnar styloid. Type II: Extra-articular, with ulnar styloid. Type III: Intra-articular (radiocarpal), no ulnar styloid. Type IV: Intra-articular (radiocarpal), with ulnar styloid. Type V: Intra-articular (radiocarpal + DRUJ), no ulnar styloid. Type VI: Intra-articular (radiocarpal + DRUJ), with ulnar styloid. Type VII: Intra-articular (DRUJ only), no ulnar styloid. Type VIII: Intra-articular (DRUJ only), with ulnar styloid. Therefore, Frykman Type II is an extra-articular distal radius fracture with an associated ulnar styloid fracture.

Question 19

In the setting of an open reduction internal fixation of a Colles fracture, what is the primary advantage of fixed-angle locking screws compared to non-locking screws?





Explanation

The primary advantage of fixed-angle locking screws in volar plating, especially in older patients with osteoporotic bone, is their ability to resist pullout. They create a 'fixed-angle construct' or 'internal fixator' where the screws lock into the plate, providing angular stability independent of bone-plate compression. This is highly beneficial in comminuted fractures or poor bone quality where traditional screws might lose purchase. While some compression can be achieved, their main strength lies in angular stability and pullout resistance, not necessarily superior compression (which is achieved by dynamic compression holes in non-locking plates).

Question 20

A patient with a Colles fracture is treated with closed reduction and casting. One week later, they complain of worsening pain, difficulty extending their thumb, and a 'giving way' sensation. On examination, there is tenderness over Lister's tubercle. What is the most likely diagnosis?





Explanation

Pain, difficulty extending the thumb, and tenderness over Lister's tubercle one week after a Colles fracture suggests Extensor Pollicis Longus (EPL) tenosynovitis or impending rupture. The EPL tendon makes a sharp turn around Lister's tubercle, and swelling, hematoma, or subtle displacement can cause irritation and compromise its integrity. An actual EPL rupture typically presents as a sudden inability to extend the IP joint of the thumb actively. FPL rupture would affect thumb flexion. Median nerve palsy causes sensory changes and thenar weakness, not necessarily specific thumb extension issues in this pattern. Infection would have systemic signs. Acute carpal tunnel would cause median nerve distribution symptoms.

Question 21

Which of the following is an absolute indication for surgical intervention in an acute Colles fracture?





Explanation

An open fracture with significant contamination is an absolute indication for surgical intervention (irrigation and debridement followed by stabilization), regardless of the fracture pattern or displacement, due to the high risk of infection. Persistent radial shortening of >5mm after reduction is a strong relative indication for surgery (unstable fracture), as is a Frykman Type II in an elderly patient if unstable, but not an absolute one. Associated ulnar styloid fracture and 2mm positive ulnar variance are not absolute indications on their own.

Question 22

When performing a volar approach for distal radius plating, the median nerve is most at risk of injury in which position?





Explanation

The median nerve typically lies superficially, just ulnar (medial) to the flexor carpi radialis (FCR) tendon in the distal forearm. During a standard Henry approach or similar volar approach, care must be taken to retract the FCR tendon radially to protect the median nerve from direct injury during incision and subsequent dissection. The radial artery is more lateral. The pronator quadratus covers the bone. The carpal tunnel is distal, but the initial approach and retraction put the nerve at highest superficial risk.

Question 23

What is the acceptable range for post-reduction volar tilt in a Colles fracture?





Explanation

Acceptable post-reduction parameters for volar tilt generally range from neutral (0 degrees) to slight volar angulation (up to 10-15 degrees volar tilt). Some sources might accept a small degree of dorsal tilt (e.g., up to 5 degrees dorsal, or -5 degrees volar) in older, lower-demand patients, but beyond that, it signifies instability or malreduction with increased risk of functional impairment. The typical volar tilt of a normal distal radius is around 11-12 degrees. Therefore, -5 to 10 degrees is the most reasonable acceptable range, encompassing neutral or mild dorsal as potentially acceptable in certain contexts, and avoiding excessive dorsal tilt.

Question 24

A patient presents with a dorsally displaced, comminuted Colles fracture in osteoporotic bone. Which factor is most predictive of early loss of reduction after closed reduction and casting?





Explanation

Significant dorsal comminution (dorsal metaphyseal comminution or the 'dorsal rind' fragment) is the most predictive factor for early loss of reduction after closed reduction and casting of a Colles fracture, especially in osteoporotic bone. The dorsal cortex provides a stable buttress, and its comminution removes this support, making it difficult to maintain the reduction in a cast. While age and ulnar styloid fractures contribute to instability, dorsal comminution directly undermines the stability of the reduced fracture. Minimal initial radial shortening might suggest a more stable fracture, but if comminution is present, it's still at high risk.

Question 25

In patients undergoing external fixation for a Colles fracture, what is the most common early complication?





Explanation

Pin tract infection is the most common early complication associated with external fixation for Colles fractures. While other complications like loss of reduction (if reduction was poor or fixator fails), CRPS, and EPL rupture can occur, pin site issues (infection, loosening) are particularly prevalent and require meticulous pin site care. Nonunion is rare for distal radius fractures.

Question 26

Which of the following statements about malunion after a Colles fracture is true?





Explanation

Malunion is defined as a fracture that has healed in an anatomically unacceptable position, leading to persistent deformity and potentially functional impairment (pain, stiffness, weakness, altered grip strength, DRUJ issues, post-traumatic arthritis). It is not always asymptomatic and often requires further intervention, especially if symptomatic. It does not always require surgical correction; asymptomatic malunions can be observed. It is more common in fractures treated conservatively or with unstable patterns, as opposed to appropriately managed surgical fixation. It affects wrist and forearm mechanics, not primarily intrinsic hand muscles.

Question 27

What is the main advantage of a volar locking plate over traditional K-wire fixation for an unstable, comminuted Colles fracture in an elderly patient?





Explanation

Volar locking plates provide superior rotational stability and better maintenance of reduction, especially in comminuted fractures and osteoporotic bone, compared to K-wire fixation. This rigid fixation allows for earlier mobilization of the wrist and hand, which is crucial for preventing stiffness and improving functional outcomes in elderly patients. While K-wires are less invasive, they often provide less stable fixation, particularly in osteoporotic bone, and can lead to loss of reduction. K-wire fixation is not contraindicated in the elderly, but its indications are more limited. Dorsal hardware (plates or wires) is more likely to cause extensor tendon irritation than volar.

Question 28

The 'watershed line' on the volar aspect of the distal radius is an important surgical consideration to prevent which complication?





Explanation

The 'watershed line' on the volar aspect of the distal radius represents the distal limit for volar plate placement. Placing the plate or screws distal to this line risks impingement on and subsequent irritation or rupture of the flexor tendons, particularly the flexor pollicis longus (FPL). This line marks the insertion of the volar capsule and ligaments. Avoiding distal plate placement past this line is critical for preventing tendon complications.

Question 29

What is the typical anesthetic technique used for closed reduction of an uncomplicated Colles fracture in the emergency department?





Explanation

For closed reduction of an uncomplicated Colles fracture in the emergency department, a hematoma block is a common and effective anesthetic technique. This involves injecting a local anesthetic (e.g., lidocaine) directly into the fracture hematoma, which infiltrates the fracture site and provides pain relief. Regional blocks or general anesthesia might be used for more complex or prolonged reductions, or for surgical fixation, but a hematoma block is usually sufficient for acute, simple reductions.

Question 30

Which factor is LEAST likely to contribute to the development of Complex Regional Pain Syndrome (CRPS) Type I after a Colles fracture?





Explanation

Aggressive early physical therapy mobilization of the wrist is LEAST likely to contribute to CRPS Type I; in fact, early, gentle mobilization, within pain limits, is often part of CRPS prevention and management. Factors that are known to contribute to CRPS include prolonged immobilization, excessive edema, psychological factors, and severe pain. The pathophysiology of CRPS is complex, involving neuropathic, inflammatory, and sympathetic nervous system dysfunction.

Question 31

A 25-year-old active male sustains a Colles fracture. Radiographs show a small intra-articular step-off (<1mm) and minimal dorsal angulation (8 degrees). He is anxious to return to sports. What is the most appropriate management plan?





Explanation

For a minimally displaced, stable Colles fracture, even with a small intra-articular component, closed reduction (if needed) followed by sugar tong splint for initial swelling control, then a short arm cast for 4-6 weeks, is often appropriate. The parameters (8 degrees dorsal angulation, <1mm articular step-off) are typically within acceptable limits for conservative management, especially if maintained post-reduction. While a younger, active patient might push for anatomical reduction, these specific parameters don't automatically mandate surgery unless reduction is lost or symptoms are refractory. ORIF would be overtreatment for these parameters. Immediate full activity is inappropriate.

Question 32

Which of the following ligaments is most commonly injured in association with a Colles fracture, particularly if there is DRUJ instability?





Explanation

The Triangular Fibrocartilage Complex (TFCC) is most commonly injured in association with a Colles fracture, particularly when there is involvement of the distal radioulnar joint (DRUJ) or an associated ulnar styloid fracture. The TFCC is the primary stabilizer of the DRUJ. Scapholunate and lunatotriquetral ligaments relate to carpal instability. Radial collateral ligament is on the radial side of the wrist. Transverse carpal ligament forms the roof of the carpal tunnel.

Question 33

A patient with a Colles fracture treated with a volar locking plate returns at 6 weeks with good union but complains of persistent numbness in the median nerve distribution, which was not present pre-operatively. What is the most likely cause?





Explanation

Persistent numbness in the median nerve distribution developing post-operatively after volar plating, when it was not present pre-operatively, strongly suggests carpal tunnel syndrome. This can be caused by scar tissue formation, plate prominence (especially if placed too distally or volarly), or swelling around the median nerve within the carpal tunnel. Infection would typically have other signs like pain, erythema, and discharge. CRPS has a broader symptom complex. EPL rupture causes loss of thumb extension. DRUJ instability relates to mechanical symptoms, not median nerve neuropathy directly.

Question 34

What constitutes an 'unstable' Colles fracture that typically warrants surgical consideration after initial closed reduction attempts?





Explanation

An unstable Colles fracture, generally defined by unacceptable radiographic parameters after closed reduction, is a strong indication for surgical consideration. These parameters include: persistent dorsal tilt greater than 10-15 degrees, radial shortening greater than 3-5mm (or 2-3mm difference compared to contralateral), significant articular step-off or gap greater than 1-2mm, or significant comminution (dorsal or volar) making maintenance of reduction difficult. A minimally displaced ulnar styloid or extra-articular fracture alone are not typically considered unstable unless associated with other parameters.

Question 35

In the surgical approach for a volar locking plate, the Flexor Carpi Radialis (FCR) tendon is commonly retracted in which direction?





Explanation

In the standard volar (Henry) approach to the distal radius, the incision is made between the Flexor Carpi Radialis (FCR) tendon and the radial artery. The FCR tendon is then retracted radially (laterally) to expose the underlying structures, specifically the median nerve which lies ulnar to the FCR, and then deeper, the pronator quadratus muscle and distal radius.

Question 36

Which statement regarding dorsal plating for Colles fractures is generally true?





Explanation

Dorsal plating for Colles fractures generally carries a higher risk of extensor tendon irritation and rupture compared to volar plating due to the prominence of hardware beneath the thin dorsal skin and the close proximity of extensor tendons. For this reason, volar plating has become the preferred approach for most dorsally displaced distal radius fractures. Dorsal plates are not primarily indicated for volar comminution (which volar plates address better), and the radial artery is not typically involved in a dorsal approach.

Question 37

After a Colles fracture has been surgically stabilized with a volar locking plate, what is the recommended immediate post-operative rehabilitation protocol for finger motion?





Explanation

A significant advantage of stable surgical fixation with a volar locking plate is the ability to initiate immediate, active and passive range of motion exercises for the fingers and thumb. This helps prevent stiffness, tendon adhesions, and reduces the risk of CRPS. The wrist itself may be protected initially with a removable splint, but finger motion is encouraged from day one. Full immobilization of digits is detrimental. Restricted passive motion is less beneficial than active.

Question 38

A patient sustained a Colles fracture and underwent closed reduction and casting. One year later, they complain of chronic pain at the distal radioulnar joint (DRUJ), limited forearm rotation, and a prominent ulnar head. What is the most likely cause?





Explanation

Chronic DRUJ pain, limited forearm rotation (pronation/supination), and a prominent ulnar head after a Colles fracture strongly indicate malunion of the distal radius, specifically with positive ulnar variance (radial shortening). This malunion alters the mechanics of the DRUJ, leading to impingement, arthritis, and instability. SLAC wrist is related to chronic scapholunate dissociation. Carpal tunnel would present with median nerve symptoms. Nonunion is very rare in the distal radius. Flexor tendon rupture is specific to loss of active flexion.

Question 39

Which of the following describes a 'Die-punch' fracture component in the context of a distal radius fracture?





Explanation

A 'Die-punch' fracture refers to an intra-articular depression fracture of the lunate fossa of the distal radius. This occurs when the lunate bone acts as a 'die' and impacts into the articular surface of the radius during the injury, creating a depressed fragment. This type of fracture often requires specific attention during reduction to restore articular congruence and prevent post-traumatic arthritis.

Question 40

When assessing a Colles fracture on lateral radiographs, what measurement quantifies the normal volar angulation of the distal radial articular surface relative to the shaft?





Explanation

Volar tilt (also known as palmar tilt) quantifies the normal volar angulation of the distal radial articular surface relative to the longitudinal axis of the radial shaft on a lateral radiograph. Normal volar tilt is typically around 11-12 degrees. In a Colles fracture, this tilt is lost or reversed, resulting in dorsal tilt.

Question 41

In the surgical planning for a highly comminuted intra-articular Colles fracture in an elderly patient with significant bone loss, what advanced technique might be considered in conjunction with volar plating?





Explanation

For highly comminuted intra-articular Colles fractures, especially in elderly patients with significant bone loss or metaphyseal defects, bone grafting (autograft or allograft) may be considered in conjunction with volar plating. This helps to support the articular surface, prevent subsidence, and promote healing in areas of deficient bone stock. While volar plating provides stability, it doesn't always address large metaphyseal voids that can lead to collapse. Dorsal plating has higher complication rates. External fixation may not provide adequate articular reduction. K-wires are typically insufficient for such complex fractures.

Question 42

Which type of Colles fracture, according to Frykman's classification, carries the worst prognosis for post-traumatic arthritis?





Explanation

Frykman Type IV fracture (intra-articular involving the radiocarpal joint, with an ulnar styloid fracture) carries a worse prognosis for post-traumatic arthritis among the initial types because it involves the radiocarpal articular surface, which is crucial for pain-free motion. More generally, any fracture with significant intra-articular involvement (Types III, IV, V, VI, VII, VIII) has a higher risk of post-traumatic arthritis, but Type IV specifically combines radiocarpal articular involvement with ulnar styloid involvement, indicating a more severe injury with potential DRUJ impact. Type VIII (intra-articular DRUJ only, with ulnar styloid) also has a poor prognosis for DRUJ arthritis. However, Type IV typically signifies significant articular disruption of the main radiocarpal joint.

Question 43

A patient is undergoing closed reduction of a Colles fracture. What maneuver is used to correct the dorsal displacement of the distal fragment?





Explanation

After applying strong traction to disimpact the fracture, the reduction maneuver typically involves exaggerating the deformity (dorsiflexing the wrist to unlock the fragments), then applying a volar translational force to the distal fragment while simultaneously correcting other deformities (supination, ulnar deviation, palmar flexion). The key for dorsal displacement is the volar translation of the distal fragment. Wrist extension would worsen dorsal displacement.

Question 44

What is the primary role of the radiolunate angle in assessing distal radius fractures?





Explanation

The radiolunate angle is measured on a lateral radiograph and evaluates the alignment between the distal radius and the lunate bone. In a normal wrist, the axis of the radius and the lunate should be collinear, or the lunate should be slightly volar tilted relative to the radius. Disruption of this relationship (e.g., dorsal angulation of the lunate relative to the radius) indicates carpal malalignment and often accompanies a dorsally angulated distal radius fracture or carpal instability. Volar tilt assesses the angle between the radial shaft and the articular surface.

Question 45

Which complication is most characteristic of a malunited Colles fracture with excessive radial shortening and positive ulnar variance?





Explanation

Excessive radial shortening and positive ulnar variance (where the ulna is relatively longer than the radius) following a Colles fracture can lead to ulnar impaction syndrome. This condition is characterized by chronic pain at the ulnar side of the wrist, particularly with pronation and ulnar deviation, due to increased load transmission through the TFCC and impaction of the ulnar head against the carpus (specifically the triquetrum and lunate). Radial nerve palsy, scaphoid nonunion, and tendon ruptures are not directly caused by ulnar impaction, though other tendon issues can occur.

Question 46

When assessing radiographs for a Colles fracture, which view is most critical for evaluating articular congruence and intra-articular step-off?





Explanation

While both AP and lateral views are essential, the lateral view is most critical for evaluating articular congruence, particularly for assessing dorsal or volar displacement/angulation of the articular surface and identifying intra-articular step-off or gap. The AP view is best for assessing radial length, radial inclination, and ulnar variance. Oblique views can provide additional information, and traction views can aid in discerning fracture lines, but the lateral view is paramount for articular surface assessment in the sagittal plane.

Question 47

What is the primary concern for a patient with an unstable Colles fracture undergoing surgical fixation who is also on anticoagulant therapy (e.g., warfarin)?





Explanation

The primary concern for a patient on anticoagulant therapy undergoing surgical fixation for a Colles fracture is an increased bleeding risk during and after surgery. This necessitates careful preoperative management to optimize coagulation status, often involving temporary cessation or bridging therapy, to minimize hematoma formation and blood loss. Anticoagulants do not directly affect fracture reduction or nonunion rates, nor are they a primary risk factor for CRPS or DVT (in fact, they reduce DVT risk).

Question 48

Which clinical sign would raise immediate concern for potential median nerve compression following closed reduction and casting of a Colles fracture?





Explanation

Paresthesia (numbness and tingling) in the median nerve distribution (thumb, index, middle fingers, radial half of ring finger) combined with pain radiating proximally are classic signs of median nerve compression. While pain with passive finger flexion can be a sign of compartment syndrome, the specific nerve distribution points to median nerve. Inability to extend the thumb IP joint suggests EPL rupture. Numbness in the little finger points to ulnar nerve. Warm, dry, red skin might be seen in CRPS, but not typically in acute median nerve compression.

Question 49

In the context of Colles fracture management, what is the 'ligamentotaxis' principle primarily applied for?





Explanation

Ligamentotaxis is the principle of achieving indirect reduction and maintaining length and alignment of fracture fragments by applying tension to intact soft tissue ligaments, particularly the radiocarpal ligaments, often via external fixation with distraction. This pulls the fragments into a more anatomical position without direct manipulation. It is not for direct visualization or dynamic compression and aims for stability rather than micro-motion for healing.

Question 50

What is the most common cause of nonunion in the distal radius following a Colles fracture?





Explanation

Nonunion of the distal radius is exceedingly rare due to its rich blood supply and cancellous bone composition. Distal radius fractures typically heal, though often with malunion (healing in an unacceptable position) rather than nonunion (failure to heal). While high-energy trauma, open fractures, and poor compliance can complicate healing, they are far more likely to result in malunion, infection, or other complications than a true nonunion of the distal radius itself.

Question 51

Which type of immobilization is typically preferred immediately after closed reduction of an acutely swollen Colles fracture to allow for swelling accommodation?





Explanation

Immediately after closed reduction of an acutely swollen Colles fracture, a sugar tong splint is typically preferred. A sugar tong splint is non-circumferential and allows for swelling to occur without compressing the limb, thereby reducing the risk of compartment syndrome. Once the swelling has subsided (usually after 7-10 days), it can be converted to a short arm or long arm cast. A tight circular cast is contraindicated due to compartment syndrome risk. Removable braces or buddy taping are insufficient immobilization for an acute fracture. A dynamic external fixator is a surgical treatment.

Question 52

Regarding the surgical management of Colles fractures, which specific nerve is most at risk during a standard volar (Henry) approach to the distal radius?





Explanation

During a standard volar (Henry) approach to the distal radius, the median nerve is most at risk. It lies just ulnar (medial) to the flexor carpi radialis (FCR) tendon. Careful retraction of the FCR radially is essential to protect the median nerve. The superficial radial nerve is on the dorsal-radial aspect. The ulnar nerve is on the ulnar side. The posterior interosseous nerve is a motor branch of the radial nerve, located dorsally. The anterior interosseous nerve (a branch of the median nerve) is deep in the forearm but generally protected if the median nerve is safely retracted.

Question 53

Which of the following is an acceptable range for radial inclination on an AP radiograph after reduction of a Colles fracture?





Explanation

Normal radial inclination (the angle formed by a line connecting the tips of the radial and ulnar styloids and a line perpendicular to the long axis of the radius) is typically around 22-23 degrees. Therefore, an acceptable range after reduction of a Colles fracture is generally considered to be 15 degrees to 25 degrees, aiming to restore it close to normal. Values below 15 degrees signify unacceptable loss of inclination.

Question 54

What is the primary function of the pronator quadratus muscle in the forearm, beyond its surgical relevance in plating?





Explanation

The pronator quadratus is a deep muscle of the forearm, located distally, and its primary function is forearm pronation. It also helps to stabilize the distal radioulnar joint (DRUJ) during forearm rotation. While the muscle provides soft tissue coverage over a volar plate, its physiological role is pronation.

Question 55

A patient with a Colles fracture treated conservatively develops significant stiffness and pain in the hand and wrist, with skin trophic changes and hypersensitivity. What is the most appropriate initial management step?





Explanation

The symptoms described (stiffness, pain, trophic changes, hypersensitivity) are classic for Complex Regional Pain Syndrome (CRPS) Type I. The most appropriate initial management involves a multidisciplinary approach including early referral for physical and occupational therapy focusing on pain control, desensitization, and gentle active range of motion. Pharmacological management (e.g., NSAIDs, gabapentinoids, bisphosphonates) and sympathetic blocks may also be considered. Further immobilization would worsen CRPS. Surgical exploration is not indicated for CRPS itself.

Question 56

Which type of fracture is typically confused with a Colles fracture but involves volar displacement and angulation of the distal fragment?





Explanation

A Smith's fracture (also known as a reverse Colles fracture) is typically confused with a Colles fracture but involves volar displacement and angulation of the distal fragment, usually resulting from a fall onto the back of the hand or a fall onto an outstretched hand with the wrist in flexion. A Barton's fracture is an intra-articular fracture of the dorsal or volar rim of the distal radius with associated carpal subluxation. Chauffeur's fracture is a radial styloid fracture. Galeazzi and Monteggia are forearm shaft fractures with associated dislocations.

Question 57

In the presence of an associated ulnar styloid fracture in a Colles fracture, when does it most significantly impact management decisions?





Explanation

An associated ulnar styloid fracture most significantly impacts management decisions when it is large, displaced, or, most critically, leads to gross instability of the distal radioulnar joint (DRUJ). The TFCC attaches to the ulnar styloid, so a displaced styloid fracture can destabilize the DRUJ. If the DRUJ is unstable after distal radius fixation, surgical management of the ulnar styloid (e.g., fixation or excision if comminuted) might be considered. Small, minimally displaced ulnar styloid fractures often heal well conservatively and don't typically affect the overall management of the distal radius fracture unless there's underlying DRUJ instability. It is not an absolute indication for surgery merely by its presence.

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Dr. Mohammed Hutaif
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Prof. Dr. Mohammed Hutaif
Consultant Orthopedic & Spine Surgeon
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