Clinical correlations

Introduction – Metacarpal fractures represent approximately 40% of all injuries to the hand. When these fractures occur over the neck of  the 4th or 5th metacarpals, they are said to be “Boxer’s Fractures.” The metacarpal neck is the most common metacarpal segment to be fractured. The 5th metacarpal is the most commonly fractured. Mechanism of fracture is most commonly due to direct blow (axial load) to a clenched fist (punching a wall or fixed object).

Epidemiology – Most common among males, ages 10-29

Anatomy – The metacarpals are concave over the palmar surface and have several distinct regions: a head that articulates with the phalanges at the MCP joint, and narrower neck that connects the head to the shaft, and a base that articulates with the carpals (CMC joint). The 2nd and 3rd metacarpals are slightly more rigid with regard to bony and ligamentous attachments, making it less likely for these to be fractured.

Diagnosis – Physical exam will demonstrate swelling and pain on palpation over the affected metacarpal. There may be a palpable “bump” over the dorsum of the affected hand, representing fractured bone tenting the skin. There may be a laceration over the fracture if the fracture protruded through the skin – an open fracture. If there is rotation of the fracture segments, there may be overlapping of fingers when the patient is asked to partially and/or fully flex the fingers (see diagram, showing overlapping 4th and 5th digits).

X-ray is used to characterize the injury. Three views are obtained—standard AP, lateral, and oblique.

Treatment – If the fracture is open (protruded through the skin), immediate surgery is indicated to wash the wound and repair the fracture. If not open, patient’s are typically splint-immobilized. Reduction (manual pushing/movement by physician) may be attempted if there is significant angulation in the AP or radio-ulnar planes; this may be difficult if there is rotation of the bones. Once swelling has subsided (1-2 weeks post-injury), the patient may be casted for 4 weeks, or may need surgery if the splint or attempted reduction failed to align the fracture to acceptable angulation and/or shortening of the bone segments. Surgery includes pinning the fracture using small Kirschner wires (K-wires) or screws.

Introduction – Fractures involving the humerus can occur in the proximal, middle, and distal portions of the bone, with each fracture location representing a different potential nerve palsy syndrome..

Epidemiology – All of these fracture locations have a bimodal distribution of occurrence, both in the young (often males) and elderly (often females).

Anatomy – The location of the axillary nerve near the surgical neck of the humerus makes deltoid muscle paralysis most common in proximal humerus fractures. Patients may present with a “flat” deltoid and weak arm abduction. Because the radial nerve courses along the spiral groove of the humerus, a midshaft fracture can lead to “Saturday Night” palsy of the wrist extensors. Also may be caused by compression by crutches or in an individual who “falls asleep” with his or her arm draped over a chair, hence “Saturday Night”. Patients will have poor wrist extension, leading to “wrist drop”. Median nerve (near supracondylar humerus) and the ulnar nerve (cubital tunnel) palsies are most common in fractures of the distal humerus and medial epicondyle, respectively.

Diagnosis – Patients present with pain, bruising, swelling, and possibly mal-alignment of the upper arm. Younger patients will often report a history of higher-energy falls or trauma, while elderly patients will report a history of low energy falls (fracture is due to osteoporotic bone in this case). The diagnosis is made using radiographs of the upper arm. Look for cortical interruption and evidence of angulation or displacement. In patients with supracondylar (a sub-type of proximal humerus fracture), compartment syndrome of the forearm may result due to vascular compromise of the brachial artery. Distal pulses and neuro status must be carefully monitored. 

Treatment – Patients make undergo operative fixation or non-operative treatment (casting) to reduce the fracture and stabilize the bone so that it may properly heal. 

Introduction – Rotator cuff injury describes a spectrum of disease that includes both impingement and tears. The rotator cuff is a common tendinous sheath that covers the humeral head and facilitates shoulder stability and motion. It includes 4 muscles: supraspinatus, infraspinatus, teres minor, and subscapularis. Tears may be caused by impingement of cuff muscles during motion (especially overhead motion involving the supraspinatus), shoulder instability, or trauma (especially avulsion involving the subscapularis).

Epidemiology – Tears are especially common in overhead throwing athletes. Chronic tears are characteristic of older patients, while traumatic tears may occur in younger patients.

Anatomy – The supraspinatus lies over the top of the humeral head and is responsible for arm abduction. It is most predisposed to impingement due to its location between the humeral head and the acromion, which compresses the tendon during shoulder movement. The infraspinatus and teres minor cover the back of the humeral head and are external rotators of the arm. The subscapularis crosses over the front of the joint and internally rotates the arm. 

Diagnosis – Patients present with insidious shoulder pain exacerbated by overhead activities and nighttime pain. Diagnosis can be made using provocative maneuvers on exam that test resisted elevation, external rotation, and internal rotation of the arm. Definitive diagnosis is usually made with a shoulder MRI, which can demonstrate a tear or tendinopathy.

Treatment – Decisions regarding treatment depend upon age and activity of the patient, tear mechanism, and characteristics of tear (size, partial vs. full). Non-operative treatment with physical therapy to strengthen the cuff, NSAIDs, and corticosteroid injections are first line for most tears. If non-op management fails, patients may undergo arthroscopic or open cuff repair.