Review Question - QID 220002

This patient has sustained multiple metacarpal shaft fractures. Malunion is a common complication of these injuries, and rotational malunion can result in scissoring of the digits, requiring corrective osteotomy (Answer 3).

Metacarpal fractures are the most common injury to the hand, accounting for around 40% of all hand injuries. Given that these occur often in isolation, the vast majority can be treated nonoperatively. Stable, closed fractures without malrotation have well-established tolerances for closed treatment, with the index and long finger tolerating 10-15 degrees of neck and shaft angulation and the small finger tolerating up to 40 degrees of the shaft and 50-70 degrees of neck angulation. Open or unstable fractures, malrotation, intra-articular involvement, and multiple metacarpal fractures are all general indications to consider operative treatment. Various fixation constructs are available, depending on the fracture pattern, and include crossed Kirschner wires, plate-screw constructs, and headless intramedullary screws.

Duerinckx and Caekebeke described a technique for minimally invasive corrective osteotomy of metacarpal fractures with rotational malalignment in a 2021 case series. The authors used a minimally invasive, fluoroscopy-guided technique for the osteotomy and a headless intramedullary compression screw for fixation. Benefits of the procedure include minimal soft tissue injury and periosteal stripping, and the intramedullary screw allows early active range of motion.

Koh et al. published a 2020 case report of a corrective metacarpal osteotomy using an intramedullary screw construct. The authors present a case of a metacarpal fracture with angulated malunion. They state that plate osteosynthesis can lead to soft tissue irritation, which may necessitate secondary surgeries for tenolysis and implant removal. This case study highlighted their use of an intramedullary wire as an additional guide to the ideal site of osteotomy and then the use of an intramedullary screw for stabilization of the osteotomy site. This technique minimizes damage to the important articular surface of the metacarpal head and allows for early active ROM while causing less extensor lag, soft tissue injury, and periosteal stripping.

Kollitz et al. published a 2014 review on the treatment and complications of metacarpal fractures. The authors stress that rotational deformity is poorly tolerated in finger fractures. Malrotation may not be apparent with finger extension other than mild nail malalignment but becomes pronounced with flexion. Each degree of rotation at the metacarpal results in 5° of rotation at the fingertip, leading to 1.5 cm of digital overlap in the closed fist. To assess rotation, the examiner should compare the affected and contralateral hands. Normally, all fingers point to the scaphoid tubercle, and deviation from this alignment may indicate a rotated fracture fragment.

Figure A is an AP radiograph of a hand showing transverse acute fractures of the second through fifth metacarpal shafts.

Incorrect Answers:
Answer 1: An inability to actively straighten the MCP joint from a flexed position, but a preserved ability to maintain an extended position if passively extended, indicates a sagittal band rupture. This exam finding is not classically found in metacarpal shaft fractures.
Answer 2: Loss of key pinch strength is classically due to an ulnar neuropathy, leading to weakness of the intrinsics, including the adductor pollicis. Loss of thumb adduction can lead to as much as 70% of lost pinch strength. This exam finding is not classically found in metacarpal shaft fractures.
Answer 4: Involuntary small finger abduction (Wartenberg sign) is a sign of ulnar neuropathy. This exam finding is not classically found in metacarpal shaft fractures.
Answer 5: Loss of sensation over the ulnar aspect of the small finger is a sign of ulnar neuropathy. This exam finding is not classically found in metacarpal shaft fractures.